Ecology of vascular epiphytes in West African rain forest

Transcription

1 ACTA PHYTOGEOGRAPHICA SUECICA 59 EDIDI:r' SVENSKA VAXTGEOGRAFISKA SA LLSKAPET Dick J ohansson Ecology of vascular epiphytes in West African rain forest Resume: Ecologie des epiphytes vasculaires dans la foret dense humide d' Afrique occidentale UPPSALA 1974

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3 ACTA PHYTOGEOGRAPHICA SUECICA 59 Distributor: Svenska vaxtgeografiska sallskapet, Box 559, S Uppsala, Sweden Dick Johansson ECOLOGY OF VASCULAR EPIPHYTES IN WEST AFRICAN RAIN FOREST Ecologie des epiphytes vas ulaires dans la foret dense humide d' Afrique occidentale (French summary) Doctoral dissertation to be publicly discussed in the Botanical auditorium, Uppsala University, on May 2, 1974, at 10 a.m., for the degree of Doctor of Philosophy (according to Royal proclamation No. 327, 1969) Abstract The ecology of 153 species of vascular epiphytes (101 orchids, 39 pteridophytes and 13 others) in the Nimba Mts in Liberia is described. 29 species are recorded in Liberia for the first time including one new species, Rhipidoglossum paucifolium, Orchidaceae. Field characteristics, flowering periods and some pollinators of the orchids are also given. In high forest with the canopy 30 m or more above the ground, 50.4 % of the trees (phorophytes) 10 m or higher carried epiphytes, compared to 14.8% for the phorophytes in regenerating forest. The ratio between fern and orchid species was 1 :3 at m alt. and 1:1 at m. Most of the epiphytic species occupy a ± restricted part of the phorophyte, as judged by their occurrence in the five sectors in which the phorophytes were subdivided. Ten different epiphyte communities are recognized. Their floral composition and development are also described. Certain species of phorophytes, e.g. Heritiera uti/is, Lophira alata and Parinari excelsa generally carry an. abundance of epiphytes, while others, e.g. Anthocleista nobilis, Fagara. tessmannii and Terminalia invorensis are mostly devoid of epiphytes. Colonization by epiphytes begins late in the life of the phorophyte, which is indicated by the higher frequency of epiphytes on the larger specimens. The effect of the epiphytes on their phorophytes is reviewed and observations from Nimba and East Africa provided. The environmental influences on the occurrence of the epiphytes on the phorophytes are discussed. In addition, field observations and experiments concerning water economy microclimate, substrate properties and light intensities are presented. ISBN 91" (ISBN ) 136 pp.

4 ACTA PHYTOGEOGRAPHICA SUECICA 59 EDIDIT SVENSKA V AXTGEOGRAFISKA SALLSKAPET Dick J ohansson Ecology of vascular epiphytes in West African rain forest Resume: Ecologie des epiphytes vasculaires dans la foret dense humide d' Afrique occidentale UPPSALA 1974

5 Suggested citation: Johansson, D., 1974, Ecology of vascular eopiphytes in West African rain forest. Acta Phytogeogr. Suec. 59. Uppsala. Doctoral dissertation at Uppsala University, Sweden ISBN (paperback) ISBN (cloth) Dick Johansson 1974 Svenska vaxtgeografiska sallskapet Box 559, S Uppsala, Sweden Technical editor: Gunnel Sjors Printed in Sweden 1974 Textgruppen i Uppsala AB

6 Abstract Johansson, D. 1974, Ecology of vascular epiphytes in West African rain forest. (Resume: Ecologie des epiphytes vasculaires dans la foret dense humide d'afrique occidentale.) Acta Phytogeogr. Suec. 59. Uppsala. 136 pp. The ecology of. 153 species of vascular epiphytes (10 1 orchids, 39 pteridophytes and 13 others) in the Nimba Mts in Liberia is described. 29 species are recorded in Liberia for the first time including one new species, Rhipidoglossum paucifolium, Orchidaceae. Field characteristics, flowering periods and some pollinators of the orchids are also given. In high forest with the canopy 30 m or more above the ground, 50.4 % of the trees (phorophytes) I 0 m or higher carried epiphytes, compared to 14.8% for the phorophytes in regenerating forest. The ratio between fe rn and orchid species was I :3 at m alt. and 1: 1 at m. Most of the epiphytic species occupy a ± restricted part of the phorophyte, as judged by their occurrence in the five sectors in which the phorophytes were subdivided. Ten different epiphyte communities are recognized. Their floral composition and development are also described. Certain species of phorophytes, e.g. Heritiera utilis, Lophira alata and Parinari excelsa generally carry an abundance of epiphytes, while others, e.g. Anthocleista nobilis, Fagara tessmannii and Terminalia invorensis are mostly devoid of epiphytes. Colonization by epiphytes begins late in the life of the phorophyte, which is indicated by the higher frequency of epiphytes on the larger specimens. The effect of the epiphytes on their phorophytes is reviewed and observations from Nimba and East Africa provided. The environmental influences on the occurrence of the epiphytes on the phorophytes are discussed. In addition, field observations and experiments concerning water economy microclimate, substrate properties and light intensities are presented.

7 Content Preface I. Introduction General notes on vascular epiphytes Distribution 2, Occurrence in various families 2, Phylogeny 2, Properties 2, Ecological subdivisions 4 Previous studies of vascular epiphyte ecology Scope of the present study Field work Terminology The area of investigation Climate Veg etation Primary and secondary forest I 3, The Liberian rain forest 14, Classification of the forest in the Nimba area 15, The phorophytes (the host trees) 17 If. The epiphytic flora Composition and geographical distribution List of species Pteridophytes 23, Orchids 26, Other vascular epiphytes 41 Ill. Biology of vascular epiphytes Reproduction biology Flowering periods of orchids 43, Observations of orchid pollination 44, Diaspore size and dispersal 45, Germination and establishment 45 Life forms Drought tolerance and drought avoidant epiphytes 4 7 Water economy Water uptake 48, Storage of water 51, Expenditure of water 53 IV. The occurrences of epiphytes Epiphytes on forest trees 1. Total number of epiphytic species known 55, 2. Quotient epiphytes/other vascular plants 55, 3. Percentage of tall trees carrying epiphytes 55, 4. Highest number of epiphytic species on one tree 59, 5. Number of epiphytic specimens or 'stands' on one tree 61 Epiphytes on other substrates On cultivated trees 62, On tree-ferns 63, On 'herbs' 64, On dead trees 64, On rocks and soil 65 Distribution of epiphytes on the phorophytes 66 Ecological subdivision of the phorophyte 66, Recording and registration of epiphytes 69, Ecological observations 72, General distribution pattern 75 Epiphyte communities 78 Terminology 78, Methods 79, Abundance 80, Epiphyte communities at altitudes below 1000 m 80, Epiphyte communities at altitudes above 1000 m 85, General observations 86 Epiphyte succession 86 Epiphyte succession in Himalayan Quercus forest 87, Succession indicated by floristic composition 87, Succession traced by analysis of humus deposits 87, Effects of environmental changes 89 Effects of the epiphytes on the phorophytes 91 Earl ier observations 91 Indirect effects 9 I, Direct effects 92 Author's observations 93 The leafless orchids 93 V. Environmental influence Climate 95 Macroclimate 95, Microclimate I 00, Light intensi ties 10 I, Daily variations in light intensity 104 Substrate 106 Properties of the substrate and their influence on the epiphytes 106 The bark 106, Bark ph and the epiphytic flora 107, Exudates 108, Humus deposits 109, Correlation between substrate and epiphytic flora 110 Biotic factors 115 Human influence 115, Animal influence II5, NutritionaJ importance of animals and microorganisms 115 VI. Distribution on the phorophytes General pattern 116, Specific patterns 116 Resume 121 Literature 124

8 Ecology of vascular epiphytes in West African rain forest 1 Preface My first contact with a tropical rain forest dates back to August 1964 when I commenced employment for Lamco J.V. Op. Co. in Liberia. As a high school teacher at the International school in Y ekepa I used my spare time during the following six years to explore the rain forest. In the vicinity of the newly constructed Yekepa community, at 500 m altitude, virgin rain forest covered the slopes of the Nimba range up to the peaks at 1300 m altitude. The rain forest was very poor in species in the field layer. On the trees, however, vascular epiphytes were abundant and soon caught my particular interest. While trying to learn about the ecology of the epiphytes it soon became evident that the literature on this subject was very scanty. Although the vascular epiphytes are a very characteristic floristic element in the rain forest inaccessible growing sites have resulted in few and often superficial reports on their ecology. After an introductory period in which to become acquainted with the tropical flora a preliminary plan for the future investigation was outlined in cooperation with Prof. Hugo Sjors at the Institute of Ecological Botany in Uppsala. After returning to Sweden in 1970 my work was continued at the newly started Afro-Botanical Dept. of the Institute of Systematic Botany in Uppsala under the guidance of Prof. Olov Hedberg. During an excursion to Kenya and Tanzania in January 1971, under the leadership of Prof. Hedberg, I was able to study epiphytes in several environments different from those of the lowland tropical rain forest. As an indirect result of a three months ecological study the same year for Sweco in the Kidatu area in Tanzania, a knowledge of epiphytes in dry environments was gained. Several persons have contributed to the completion of this study. Harvey Boettcher, Manuel Diaz and Franz Zimsek often accompanied my tours of the forest. K urt Eriksson helped in the construction of the light-measuring equipment and Miss Anne Cron e carried out some laboratory work in Liberia. Many other Lamco employees have in one way or another helped or simplified my field work. Help and guidance in the determination of critical specimens have been received from Jean Bowden, F.N. Hepper, Prances Jarrett, M. Sands and P. Taylor of the Kew Herbarium, and from L. Garay of the Oakes Ames Herbarium, Harvard Univ., Cambridge, Mass. Prof. Sanford, Univ. of Ile Ife, Nigeria, provided an unpublished manuscript on the use of epiphytic orchids in general ecology work. The determinations of the insects were performed by M.A. Grog an, S.L. Shute and I.H.H. Y arrow of the Entomological Dept. of the British Museum (Natural History). Aina Aim, Gertie Backlund, Margareta Hellman and Barbro Enander have typed the manuscript. Miirta Ekdahl has prepared the large tables and Ulla-Britt Sahlstrom has copied the photographs. The map over the investigated area was drawn by Per Ake Soderman. In the preparation of the manuscript valuable criticism has been provided by Doe. Orj an Nilsson. Dr Jerk Hellkvist at the Institute of Physiological Botany in Uppsala has commented on the section about the water economy of the epiphytes. The linguistic revision has been carried out by Andre Brochu and the French resume was translated by Renee Perrette. Granges International Mining Division, Stockholm, has supplied a grant for the photographic illustrations. Prof. Hedberg, my teacher and tutor, has through his never failing enthusiasm and encouragement actively contributed to the completion of this work. Finally, Astrid did a considerable amount of work behind the scenes. All persons and institutions mentioned above I want to sincerely thank for valuable cooperation. Uppsala, January 1974 Dick Johansson Institute of Systematic Botany Box 541, S Uppsala, Sweden

9 I. Introduction GENERAL NOTES ON VASCULAR salis, with numerous epiphyte species. Ericaceae EPIPHYTES ( 13 50) has a considerable number of epiphytes es Distribution Epiphytism, as defined by Barkman (1958:9), occurs in many plant orders. It has a very extensive geographical distribution among non-vascular plants such as algae, mosses, and lichens. The vascular epiphytes, pteridophytes and phanerogams, are on the other hand more or less restricted to tropical regions. In tropical rain forests especially, they form a significant part of the flora, and their presence and abundance are often used as a characteristic of such forests (Schimper 1903:260, Richards :8). Vascular epiphytes are rare in temperate climates. In humid climates, e.g. certain coastal and high mountain areas, a large number of plant species may occur for varying periods of time as epiphytes although lacking special adaptations to such a life (Sharp 1957). The somewhat confused terminology of the different types of epiphytes will be presented later in this chapter. Occurrence in various families In the tropical rain forest epiphytism among vascular plants occurs in a limited number of families, but in a large number of genera. Schimper (1888) mentioned 33 families and 232 genera. Naturally the number of known epiphytic genera has increased since then, but the number of families given by him is reasonably up to date (Richards 1964: I I 2). It is very difficult to estimate the to tal number of epiphytic species in the world. However, their presence in certain families is better known. The estimated total number of species in the families mentioned below, in parentheses, is taken from Willis (1966). The majority of the orchids (20 000) are epiphytes (cf. Hunt 1967, Summerhayes 1968). The bromeliads (1400) play an important part in the epiphyte flo ra of the New World and to a lesser extent this also applies to the Cactaceae (2000). The latter family also includes a pantropical genus, Rhip- pecially in the Vaccinioideae. The families of Araceae (2000), Asclepiadaceae (2000), Gesneriaceae (2000), Melastomataceae (3000), and Rubiaceae (6000) are also rich in epiphytes. A geographical pattern can be observed in the composition of the epiphyte flora. In Africa pteridophytes and orchids almost solely form the epiphyte flora, while in South America bromeliads and cactaceous plants also are important. In Asia and Australia species of Asclepiadaceae and Rubiaceae are well represented together with the pteridophytes and orchids. Phylogeny Schimper ( 1888) maintained that the tropical epiphytes have developed from te rrestrial types that were growing in dark humid fo rests. Went (1895) claimed that the epiphytes have evolved from root climbers. Pittendrigh (1948) suggested that the epiphytic bromeliads originated from terrestrial ancestors that lived under semi-desert conditions. The same would probably apply to the epiphytic Cactaceae and maybe the majority of the epiphytic flowering plants. Garay (1972:2 11) date the development of the epiphytic mode of life among the orchids back to the Pl iopleistocene. He also rightly states that while the terms geophytic and epiphytic convey the meaning of ecological habitats, in reality they express distinct evolutionary adaptations through morphological modifications in the roots. Properties What are the properties that make a plant successful as an epiphyte? Two conditions must be fulfilled. (1) The plant or its diaspores must in one way or another be able to reach a position on the phorophyte. (2) It must possess the ability to survive drought after its establishment. (1) The weight of the diaspores has been emphasized

10 Ecology of vascular epiphytes in West African rain forest 3 by Schimper (1888) as a chief limiting factor for potential epiphytes. He pointed out that many of the numerous epiphytic bromeliads in South and Central America have particular adaptations in the seeds for wind dispersal. The largest number of epiphytes occurs among the orchids and the pteridophytes which both have very minute diaspores. These are so small that they can easily be carried by the wind. 84 % of 50 true epiphytes in New Zealand exhibit minute spores or seeds (Oiiver 1930: 19). The weight of an orchid seed (Dendtobium attenuatum) was given as g by Ames ( 1922). The role of animals in the dispersals of the diaspores of epiphytes has been stressed by several authors. Holtum (1960) reports dispersal by insects: "Ants may have an important function in several ways. They may carry seeds, especially small seeds which contain food useful to them. Some of these seeds, including seeds of orchids, are sought chiefly fo r oil drops in the outer tissues and the embryos may not be destroyed by ants; the seeds grow in ants' nests, which provide shelter and minerals for the seedlings." Numerous birds, bats, monkeys and squirrels, living in the trees may also contribute to the dispersal of the epiphytes. Fruits may be eaten and the seeds spread with the excreta. A somewhat stranger way of dispersal is reported for the epiphytic bromeliad, Tillandsia usneoides, 'spanish moss', that occurs in the South Eastern parts of USA (Fig. 1). This lichen-like plant is used by certain birds as building material for their nests. The plant survives the breeding period and continues to develop afterwards. The most common way of dissemination, however, occurs during violent gales, when pieces are broken off and carried by the wind to new phorophytes in the same manner as among certain lichens (Pennfound & Deiler 1947). (2) Once located on the phorophyte the young plant must have an effective system of attachment to the substrate so as not to be washed down by the rainfall. The root systems are often very extensive, superficial or aerial, and in many cases specially developed only for anchoring purpose (certain bromeliads). A common problem is the short time of water uptake due to the limited ability of the substrate to store water. The plants are often adapted to a rapid up take and high storage capacity of water, replacing the storage in the substrate. Fig. 1. Tillandsia usneoides, 'spanish moss' (Bromeliaceae). New Orleans, La. Drought is the most serious threat to the life of the epiphytes. Drought resistance shows a wide range of variation, from the poorly adapted filmy fe rns to the extremely resistant epiphytic cactaceae and bromeliads. It is reported that bromeliads survive in areas with about 400 mm/year in N. Argentina (Tixier 1966:22). The greatest abundance of epiphytes is found where there is a yearly rainfall of 100 inches c 2500 mm) or more and where no month has an average of less than 2 or 3 inches (Holtum 1960). In Indochina the epiphytes disappear when the rainfall is less than 1000 mm per year (Tixier 1966:121). The temperature seems also to limit the geographical distribution of certain epiphytes, as can be observed e.g. in the East African high mountains where the pteridophytes occur at much higher altitudes than the orchids. The epiphytes show an interesting variety of both morphological and physiological adaptations for

11 4 Dick Johansson withstanding unfavourable conditions. It would, however, take too far to discuss these adaptations here. A brief description of the major life-forms is given in chapter II. Ecological subdivisions Several authors have grouped the epiphytes into large units, based upon life-forms, life-cy cles or their dependence on light, substrate and humidity. The divergent terminology for such groups makes comparisons between different investigations difficult. Barkman (1958:9-15) has given a valuable summary of the terminology concerning non-vascular epiphytic cryptogams. Regarding non-vascular cryptogams the term obligate is often used for typical epiphytes sensu Oliver (Table 1). Th e rest of the epiphytes are called facultative (Barkman 1958: 11). A subdivision of the facultative epiphytes into three categories, preferential, indifferent, and occasional has been used by Hilitzer ( 1925). Both vascular and non-vascular plants are incl uded in the micro and macro-epiphytes of Tixier ( 1966 :45) and in the Sonnen(licht), Schatten, and Epiphyllen vegetation of Knapp (1973). Oliver (1930) presented a scheme that will be used here as a base for comparing the terminology of different authors (Table 1). I. Typical epiphytes. Species which are habitually epiphytic. II. Occasional epiphytes. Here are included those plants which are under ordinary circumstances terrestrial. Occasionally they are found on trees where they appear to thrive until maturity. Ill. Hemi-epiphytes. These are trees which begin their existence on other trees or tree ferns, send down one or more taproots to the ground and eventually establish themselves as independent plants. IV. Ephemeral epiphytes. These are accidental epiphytes. They are for the most part seedlings of trees which fail to gain maturity in their epiphytic position, and consequently die after attaining a size which demands more nutrients than the substrate can furnish. Th e term 'ephemeral orchids' is used by Smith (1925) for plants that carry their flower only one day, e.g. Dendrobium crumenatum. In F.W.T.A. 1:1 (1954 :220) the term 'sub-epiphyte' is used for a Begonia that is 'creeping over logs, etc'. Th e typical epiphytes, have also been divided into a large num ber of units based on the habit or dependence of water, light, and substrate. Growth habit Schimper (1888) recognized three types: pro to, nest or bracket, and tank epiphytes, bas ed on the habit of the plant. Water Th e dependence on water is a common criterion for a subdivision. Oliver (I 930) distinguishes between hydrophytes, mesophytes and xerophytes. Schnell (1952:282) recognizes the sam e units as Lebrun ( 193 7) with one addition, 'l es epiphytes hygro-mesophiles'. The units used by Schnell are thus: I. Epiphytes hygrophiles de la base de troncs II. Epiphytes hygromesophiles de la region moyenne des troncs Ill. Epiphytes mesophiles des grosses branches et du sommet des troncs des grand arbres IV. Epiphytes xerophiles des branch es superieures Light A division into shade-, sun-, and extreme xerophilous epiphytes, has been used by Davis & Richards (1933: ), and Richards (1939:31-32). Richards admits the difficulties in distinguishing th e latter two groups. Table 1. Classification of epiphytes by some authors. Oliver 1930 Typical ep. Occasional ep. Hemi-ep. Ephemeral ep. Schimper 1888 Went 1895 Pessin 1925 Lebrun 1937 Hosokawa 1968 Schnelll970 Holo ep. Wahre ep. Eu-ep. Ep. authentique Ep. typica Ep. hygrophiles Ep. mesophiles Ep. xerophiles Pseudo ep. Ep. accidentel Ep. occasionalis Ep. accidentels Hemi-ep. Hemi-ep. Hemi-ep. Hemi-ep. Hemi-ep. Lian-ep. Pseudo ep. Ep. accidentel Ep. ephemeralis

12 Ecology of vascular epiphytes in West African rain forest 5 Grubb et al. (1963 :592) is also critical of this division. In his studies of mountain rain forests in Eq uador he remarks: "extreme xerophilous epiphytes, sensu Richards, are not markedly more distinct from each other in their biology than crownbase and bole-base skiophytes." Grubb et al., use the terms photophyte and skiophyte for epiphytes that live in well-l it and ill-lit habitats respectively. Guillaumet (1967 :60) distinguishes between a heliophile, a mesophile and a sciaphile group. Hosokawa (1968) groups the epiphytes into four ecological types: (a) the sun-type growing in direct sunshine, (b) the stem and/or leaf succulen t xerophilous type, (c) the shade-tolerant type growing in diffuse weak light, (d) the hygrophilous type. Substrate Went ( 1940) considers the demand on the substrate as a dividing line between epiphytes. He differentiates between two groups: bark epiphytes and those th at need an accumulation of humus to be able to develop, so called humus epiphytes. It is of course impossible to rank the importance of all the environmental factors without experimental proof. Which one of the many factors involved that is decisive can be very hard to determine since they are often in teracting. PREVIOUS STUDIES OF VASCULAR EPI PH YTE ECOLOGY Research on epiphytic plants was started by Schimper. In a pioneering and comprehensive work 'Die Epiphytische Vegetation Amerikas' (1888) he focuses his attention on the anatomy, mo rphology and ecology of epiphytes. Even though the epiphytes form a characteristic part of the rain forest they are usually mentioned only casually in ecological reports (see section Field work). In Asia specialized studies have been carried out on 1 ava by Van Oye (I 92 I, 1924 a), and Went (193 1, 1940), and in Micronesia and elsewhere by Hosokawa (I 952 a, b, I 954 a, b, c, 1955, 1957, 1968). Hosokawa has also written numerous articles on the terminology of epiphyte communities and the life-forms of epiphytes. From Vietnam Tixier (1 966) has presented a thorough study of epiphytes including bryophytes. In Africa, Van Oye (1924b) and Lebrun (1937) have studied epiphytes in the Belgian Congo. Sanford (1967, 1968 b, 1969, 1973) has presented a series of in teresting papers concerning the distribution and ecology of epiphytic orchids in Nigeria and elsewhere. Several authors e.g. Piers (1968), Morris (1968, 1970), and Stewart (in Stewart & Campbell 1970) have revealed interesting facts about the ecology of orchids in East and Central Africa. In a penetratin g study of the epiphytic fern genus Platycerium in, the Ivory Coast, Boyer (1964) assembled an impressive amount of facts, useful for the understanding of the ecology, not only of the Platycerium ferns but also of epiphytes in general. Regarding the New World surprisingly few publications are available (Dunn 1941). The bromeliads have naturally received interest from many directions. Picado ( 1913) published a report on the ecology of the bromeliads and their remarkable adaptations in the epiphytic life -forms. Their anatomy and importance as breeding sites for various insects have been studied by Pennfound & Dei ler ( 194 7) and Pittendrigh ( 1948). SCOPE OF THE PRESENT STUDY It is no exaggeration to say that the composition and geographical distribution of the vascular epiphytic flora both in Africa and elsewhere in the tropics are poorly known. Even less known are the presence and distribu tion of the various species in the great number of habitats that exist on the trees. This study has aimed at recording the growing sites of epiphytes in the rain forest and particularly the occurrence of epiphytes in the highest parts of the forest, since such information is extremely scarce. This is partly a quan titative study of the spatial distribution, since whenever possible the actual number of epiphytes was counted according to a special system. However, the ecological requirements for the individual species were also investigated. Special attention has thus been paid to the light and substrate and their possible effect on the presence and abundance of epiphytes. The often observed tendency of epiphytes to form some kind of commun ity induced a detailed invest gation of the abundance, floral composition and development of such communities. Previous reports of a correlation between the epiphyte flora and species of 'h ost tree' offered another aspect th at was investigated. The many adaptations that occur among the epiphytes induced studies into

13 6 Dick Johansson their water economy. The use of epiphytes as indicators of microclimate and forest destruction was also investigated (cf.. Sanford 1972). A more specialized study regarding the phenology, pollinators and special field characteristics of the orchids was also included. My study is restricted to the vascular epiphytes. However, the so-called filmy ferns, e.g. Trichomanes and Hymenophyllum, are in the main excluded, but the species observed are listed in chapter II (Table 7). In several ways these ferns resemble the nonvascular epiphytes. Their leaves are usually one cell layer thick and without stomata and can take up water in the same manner as mosses. The facultative (occasional, hemi- and ephemeral) epiphytes are also excluded but listed (Table 7) and referred to when of importance for the epiphyte flora. FIELD WORK My field work was carried out during , with the major part of the distribution recordings from the last two years of this period. The scanty knowledge of the presence and the distribution on the trees of epiphytes in the tropics can be traced back to two different causes. The first is the very inaccessible growing sites of these plants. The second is the difficulties connected with the determination of the epiphytes. Several species are extremely similar in size and shape in their flowerless states (Fig. 33). To overcome the first obstacle my research has been directed in three different ways: recording of the epiphyte flora, (1) on felled trees (close observation), (2) of standing trees (distance observation), (3) on a mi nor part of a tree by close or distance methods (occasional observation). The two first methods give a rather accurate picture of the distribution of epiphytes on the trees while the third is utilized fo r additional information. To get acquai nted with the epiphytes in various stages of their development I started from the very beginning to collect specimens and grow them in small wooden boxes in a specially constructed 'frame house'. The phenology of the various species could then easily be studied and minor characteristics observed. The investigation includes the examination of 220 felled trees and 236 trees examined according to the distance method on 4 7 species of phorophytes in the high forest. The so-called occasional recordings number more than three thousand obser- vations from roughly 1500 trees, palms, ferns and lianas. Outside the specially investigated area I have carried out surveys of the epiphyte flora in every county of Liberia. The neighbouring countries of Guinea and Ivory Coast have also been visited on several occasions enabling a comparison of the flora. Epiphytes in environments, different from the rain forest types, have been studied in Kenya and Northern Tanzania (Jan. 1971), and in Southern Tanzania (April-June 1971). Brief visits in Zambia (July 1971) and in Cameroon (M t Cameroon, July 1971) have supplied additional information. Efforts have been made to get photographs from specimens growing in situ, but difficulties in obtaini ng good pictures of some of the phorophytes in the dense forest and of the epiphytes in the crowns, explains why some of them had to be photographed in rather unnatural environments. All pictures, except Fig. 31, are taken by the author. TERMINOLOGY Epiphyte is here used as defined by Barkman (1 958:9). When nothing else is stated the term epiphyte refers to vascular epiphytes. The 'host tree' (shrub, palm etc.) of the epiphyte is referred to as the phorophyte following Ochsner 1928; (cf. Barkman 19 58, Sjogren 1961, Tixier 1966, Skye 1968). This term is according to the definition by Ochsner ( 1928). The no menclature of the phorophytes agrees with Voorhoeve (I 96 5) and for species not treated by him the nomenclature in Hutchinson & Dalziel: Flora of West Tropical Africa (F.W.T.A.) 2nd ed., is followed. The term high forest is applied to forests with a canopy at a height of 30 m or more regardless of the origin. Secondary or regenerating forest refers to forests in various stages of regrowth with the canopy below 30 m height. The area of investigation The area investigated, called the Nimba area, is situated in northern Liberia, near the border betw een Guinea and the Ivory Coast (Fig. 2) and includes parts of the Nimba Mts. The countries relevant to this investigation are shown in Fig. 3. Large mountains are poorly represented in West Africa but within the so-called Guinea Highland,

14 Ecology of vascular epiphytes in West African rain fo rest 7 BONA ljmt YULLITON GUINEA (/.EETON N I MT TOKAOEH I I I I / I I I I I I I I I I I I I I I I 'ZlJLO'Wit I Mf SOUTH NIMBA 3km..... L.::..:.J m j::::::::::] m Hh > 1300 m Fig. 2. Map of the investigated area and its location in Africa. stretching from Fouta-Djallon in Guinea to the Dans massif in the Ivory Coast, a series of ridges and peaks rise to altitudes of more than 1000 m. In northern Sierra Leone, the Loma Mountains reach m at the Bintumane peak. In Guinea, Mount Bala in the Ziama massif is m high, but even more imposing are the Nimba Mountains with a number of high peaks (e.g. Mt Molard 1752 m). In the Ivory Coast the Dans massif contains the two high peaks of Mount Tonkoui, 1240 m, and Mt Dou 1340 m. The Nimba Mountains stretch from Guinea into Liberia, where the ridge has a NE-SW direction with the highest part slightly above m (Fig. 4). Here the range is rising abruptly from a tableland at around 500 m altitude. Its highest part is built up by a narrow ridge or crest with steep slopes on each side Fig. 3. Some West African countries of relevance to this investigation. The distribution of rain forest at low and medium altitudes is marked by dots. '2/ Po r '7=""":---+--'-=--.,.,..- Guin I 6N W 2 Nigeria

15 8 Dick Johansson (Fig. 11). The southernmost part ends in a steep mountain, Bele (Bilimu). East of the ridge the two peaks Mt Gangra and Mt Yulliton of more than 1000 m dominate the landscape. South of these peaks rises another ridge with the highest part at Mt Tokadeh at around 1000 m altitude. After the discovery of iron ore in the Liberian Nimba in and the start of mining operations in 1963, a large influx of people has taken place into this previously sparsely populated area. The early stages in the exploration and the new developments in this area are described in Gardlund (1967). CLIMATE For Liberia as a whole the year can roughly be divided into a rainy season from March/ April to October/November, and a dry season during the remaining months. These extreme weather types are created by the yearly movements of the Inter Tropical Front (I.T.F.). This front is formed between the relatively cool, moist air of the equatorial zone over the Atlantic Ocean, the Equatorial Maritime Air Mass, and the hot dry mass of air over th e Sahara, the Tropical Continental Air Mass. During th e dry season the movements of these air masses are, simply speaking, regulated by the high-pressure belt formed over the Sahara and the low-pressure belt over the area of South Africa. The wind blowing from the high-pressure belt to the low is deflected to the west owing to the earth's rotation. This wind will thus appear as a north eastern dry often hot and dust-laden wind, commonly known as the Harmattan. During the rainy season the wind is blowing fro m a high-pressure belt above the subcontinent of South Africa towards a low-pressure belt formed above North Africa. This wind is in West Africa known as the southwest monsoon. When th e moist SW -monsoon reaches the Lib erian coast heavy rains start to fall. The rainfall in th e coastal strip is very high, generally mo re than 4000 mm a year. Towards the interior precipitation decreases, and in the northern part the precipitation is less than half of the amount of the coast. In the southeast of the country, a short dry period, 'the mi ddle dry', often appears in July-August, which in certain years is even felt in Nimba (Fig. 5). In periods of varying length the macroclimate at Y ek epa (51 0 m) has been measured, in a traditional way, with the instruments in a meteorological box, 1.5 m above the ground. The rainfall has been measured with a standard rain gauge also at 1.5 m above th e ground. The maximum and minimum temperatures were taken at seven o'clock for each 24 hours period. The relative humidity was recorded with a hygrograph, which was calibrated to a psychromet er (dry and wet bulb th ermometer). At the peak of th e ridge, the mining company, Lamco J.V.Op.Co., has since 1957 performed regular meteorological observations. Unfortunately the observation site has been moved twice, and the data after January 1967 only include rainfall and cloudiness. Th e microclimatical effects on the distribution of the ep iphytic plants within the trees are more conspicuous than macroclimatic effects. (However the difference between the epiphytic flora at the crest of the ridge and that in the surrounding lowland is no Fig. 4.. The Nimba Range seen from Mt Molard (1752 m) in Guinea in a SW direction. Note the absence of clouds on the west side of the Range and on Mt Gbahm. March 1965.

16 Ecology of vascular epiphytes in West African rain fo rest Yekepa 510 m, ,... "',,--,... \ / \ r;' \, \ r--,---- n r I Fig. 6. Temperature variations during a day in the wet and a day in the dry season. Yekepa 510 m. 250 J A N.,.--- Nimba Range 1248 m,----, f r--, DEC. Fig. 5. Monthly rainfall at Yekepa 510 m and at Nimba Range 1248 m, The number of days with rainfall is given below each month. doubt regulated by the macroclimate.) Unfortunately, microclimatical investigations in the treetops and along branches, meters above the ground, have been impossible to perform. The microclimate in a rain forest, discussed later in chapter V, has been investigated in Nigeria by Evans ( 1939) and in the Ivory Coast by Cachan (I 963), and Cachan & Duval ( 1963). Temperature In Yekepa the daily maximum temperature during the rainy season is close to 30 C and the minimum temperature around 22 C. The daily variation of the temperature in the rainy and dry seasons is shown in Fig. 6. A shower of rain will of course alter this daily pattern. The temperature may then drop 4-5 C in a few minu tes. In the dry season the difference between maximum and minimum temperatures is much wider than in the rainy season. This can, somewhat simplified, be correlated to the low frequency or to tal absence of clouds during that period. This results in an increased influx of radiation during the day, but also a larger outflow at night. With the arrival of the Harmattan winds from the north a few days often show very low night temperatures. The lowest temperature recorded is from February 1, 1970 when a reading of 12.5 C was registered during the night. The following day the maximum temperature reached 32.5 C which gives a difference of C (Fig. 8). The daily variation of the te mperature at the higher parts of the ridge is unknown but there is a five year ( ) series of maximum and minimu m temperature recordings from the Geologist's Camp Nimba. The figures from 1966 are given in Table 2. The differences between the mean maximum and minimum temperatures are small. The largest differences occur in the dry season. In a high forest, at ground level, the daily variation in temperature, as one would expect, is smaller than outside the forest (Table 3). Kunkel (1966), who has carried out occasional temperature recordings from various places in Liberia, estimates the temperature in an open area to be around 5 C higher than inside the forest.

17 10 Dick Johansson Table 2. Maximum and minimum temperatures (mean) at Nimba Range 1340 m, (Source: Lamco J.V.Op. Co.) m m 6 0 Temperature oc Period Max. Min. Mean January February March April May June July August September October November December Table 3. Temperature one meter above the ground, in a high forest and in the open, during a day in the wet and a day in the dry season. Seka V alley 600 m. Temperature C Date Season Max. Min. Diff. High forest wet dry Open area wet dry Rainfall In an area with differences in altitude of m within a few kilometers distance, local effects in the distribution of the rainfall will of course be pronounced. From the highest part of the ridge, at two different sites, records of the rainfall are available. The first series of observations are from the Geologist's Camp Nimba, 'N, 8 3 1'W, at an altitude of 1340 m, and _include the years The second observation point was at the Mine Office, 7 38'N, 8 29'W, at an altitude of 1248 m, from the years The average rainfall for the four years at Geologist's Camp Nimba was 3106 mm compared to 2487 mm for the threeyear-series at Mine Office. During 19 62, the rainfall in Yekepa was only 54.0% of th at at Geol. Camp. (Adam 1971:15). The distribution of the rai nfall in one month reveals some interesti ng details. Even in a month during the rainy season, June 1969, with a total of 316 mm, 14 days had no rainfall, and at the middle of the month it only rained 10 mm during a 12-dayperiod (Fig. 7). These 'dry periods' of shorter dura I. I I I I Fig. 7. Daily rainfall (in mm) during June Yekepa 510 m. tion probably influence the distribution pattern of epiphytes on the phorophytes. In the beginni ng of the rainy season, May -July, the rain often falls as a drizzle. In June, particularly, it may rai n more or less continuously for half a day, which is rare any other time of the year. This is the ti me when the surface front of the I.T.F. has passed. At the end of the rainy season, Sept.-_Nov. the mornings are often clear but in the afternoons heavy thunder-showers are usual. These rainfalls are of a convective nature, e.g. the humid air which is warmed by the sun rises and condensation occurs. In the afternoon huge clouds have built up and large amounts of water are released. These rainshowers are of a short duration. The number of days per month with rainfall varies from year to year. The figures for 19 69, at 1248 m and 510 m are shown in Fig. 5. The period August October has the largest number of rainy days. In Y ekepa, no rain was recorded during the period December 12, February 8, 1970 (58 days of drought), and at the Mine Office, 1248 m, no rain was recorded during the period November 16, February 16, 1970 (92 days of drought). Humidity At nightti me, the relative humidity is 100% or thereabouts during the whole year. The absolute content of water in the air varies naturally with the seasons. Even in the dry season the air is on the verge of saturation during the nights, a fact which the low night temperatures can account for. From the saturated level at nightti me the humidity level is

18 Ecology of vascular epiphytes in West African rain fo rest 11 mi.j-j-1.1-lu IIJ_H.) UII Hontag Monday Lundi Dit:nsfoq rue:sdoy i Z022t 6 8'"'"/. Hillwoch Wednesday Hercr i Donner&tag Thunday Jeudi I Freitag Friday Vendredi I Sonnobend Saturday Som i I Sonnlag Sutt d_ oy Dimonche I Monfaa t ' 6 8l12" 16 18Z022?Y "" 16 18Z Z02! i 8 10/l ? 8l""l182022?.., ; Mordi - rekepa 510 m 1 I I U_/ 1,[ I I u 7 0 I I'Jj I I L// ///rill 1/1/ 1/lrlllllrt /Tlr/1!rUt/ lrtl I TT /llrt /11 Jan. 26- Feb : I V" I I. r V V r - 1+-H - 1+ H / I I l- t--.,.. I J" A-T 1" I s s i7""/6 "2flt? /"; ;, ?; ' 6 8 1,0/ , 6 810l Z022f' i 6 81 /"16 181? "l"t22?, ; Honlog HOliday Lundi Dit:rutaq lut:sdo Hard( / Hillwoch Wednesday Hercredi / Donnerdog Thursday Jeudi / Freilag Friday Vendredi / Sonna!Hnd Solurdoy Sam i f Sonnlog Sunday Dimonche f Honloo V eke a ' '5to 'rind '. J,, P i U n,e l I! I I.. / I ---- I I I I I ',[ I I.L.! I l.f- {Il l! 11 11/ l rlltrr TTTr! l / 111 1/l llri i i i i i//ji-('v//1 1 l l I I I I I I I I I I I I I I 1 1 I 1//1 ;: o o 22.o Fig. 8. Relative humidity during a week in the wet and a week in the dry season. Yekepa 510 m. Figures for max imum and minimum temperature ( C) are given for each 24 hr period. lowered during the day as the temperature rises. The absolute minimum relative hum idity (Table 4), although only lasting for a short period in the afternoon, can be used to illustrate the yearly variation in the desiccation effect on the plants. Naturally large variations are found in the daily changes in the relative humidity. This applies to variations between individual days of the same season as well as between whole periods in different seasons. The daily variation of the relative humidity during a week in the rainy season (July 22-27, 1969) and the dry season (February 2-8, I 970) illustrates this (Fig. 8). The impact of the dry Harmattan winds is clearly visible in the graph from the dry season. During the period 31. I -5.2 I 970 the mean absolute minimum relative humidity was only 23.2 %. At higher levels, e.g. at Mt Gbahm 1300 m, where mist and rainfall particularly from June to August keep the air saturated, the daily variation is very small (Fig. 9). The weekly average of the absolute minimum relative humidity is as high as 84 %. Table 4. Absolute minimum relative humidity. Mean for the periods. Yekepa 510 m. Period Absolute minimum relative humidity (o/o) i I

19 12 Dick Johansson Monlog Hondoy l.undl Oi nslaq Tuesday Mardi Hilfwoch Wedn sday M rm:di Donn rslog Thrmdoy J udl FreUog FrldtJy Vendr l SonnabMd Saturday Sam i Sonnlag Sunday Oimanthe 1i. '{jjj,h rlt:, jfr i..,....,h.....,.;; "W...,..."j i ;""" { 11. _.L I 1>rt bf/.j th I rv I J I I rl L TLI I III I/ 1 U n lllll/111! rl!! '/Il l /'- I. f-!"- 'f-'f'- +' V.. -In Honla g Fig. 9. Relative humidity during a week in the wet season. Mt Gbahm 1300 m. Cloudiness The cloudiness has been recorded at the Geologist's Camp Nimba and Mine Office at 1248 m. The day was divided into two recording periods, and (Fig. 1 0). The ratio between cloudy and sunny days in 1969 reveals that June, July and August were the cloudiest months, although the period September to October had the same mean rainfall as the three earlier months. January 1970 showed only five mornings with more than 50 % cloud cover and all the afternoons were cloudless. During the period January 12 to February 6, 1970 no clouds whatsoever were reported at any period of the day. The local cloud or mist system that frequently can be observed around the highest parts of the ridge during the dry season seems to be correlated with the NE-winds (Fig. 11 ). Wind In general wind velocities are low. Thunderstorms are accompanied or rather preceeded by strong winds that usual ly last for only a few minutes. Kunkel (1966:59) reports that, at the end of February 1962, a very strong thunderstorm passed John-Davis Town (Putu district) in eastern Liberia. The wind had a hurricane-like strength and created an almost 100 m gap in the forest east of the settlement. Only around 20 % of the trees were still standing after the storm had passed. In the Nimba area no such storms of signs of earlier ones have been observed. For certain short periods the dry Harmattan winds are strongly felt in the Nimba area. The wind is weak, merely as a breeze, but is characterized by its dust-filled, very dry air. The visibility is low (a few DAYS 15-0 A M PM r-r r-r--1--_r--r-_r- -r- R:>< Rx. _. -? - r-r- r-r-- -r <g tx'x Altitude IJOO 600 Ivo ry Coast Air fo rced ja upwards/ = Air sinking \ wn Liberi a \Clouds diss J F M A M J J A s 0 N D Fig. 10. Annual distribution of cloudiness (hatched) and sun at Nimba Range 1248 m, The days are divided into two parts, AM and PM, and cloudiness means that more than 50 % of the sky was covered with clouds. (Source : Lamco J.V. Op. Co.). Fig. 11. Cloud formation over the crest of the Nimba Range under easterly winds during the dry season. (Schematic cross-section of the Range 1.1 km SW of the Three Border Point, in a NW-SW direction.)

20 kilometers only). The sun disappears as a redglowing ball in th e afternoon, and the relative humidity reaches its absolute yearly minimum. Ecology of vascular epiphytes in West African rain fo rest 13 VEGETATION Earlier botanical exploration The Nimba Mts in what today is part of Guinea and th e Ivory Coast were during the French administration subject to a series of studies covering several aspects of natural history (e.g. Lamotte et al. 1955). A remarkable work on the vegetation of the Nimba Mountains was presented by Schnell (1952). From the Liberian part of the Nimba Mountains botanical collections have been performed by W. Harley at and around Mt Bilumi (Mt Bele). Under the sponsorship of the Nimba Research Committee, headed by K. Curry-Lindahl, botanical collections were carried out by P. Adams (1964) and J. Adam ( and 1970). Based upon his extensive collections from all parts of the ridge, Adam (1971) published a work entitled 'Flare descriptive des Monts Nimba'. During his study of Liberian high forest trees, Voorhoeve (1965) visited the Nimba Mts and made collections there. Primary and secondary forest Generally speaking the rain forests can be divided into two main groups, primary and secondary. The primary forest does not bear any sign of human influ ence (Fig. 12), while the secondary has been affected in one way or the other by human activities (Figs. 13 and 14 ). There are diverging opinions as to the presence of true primary forest in West Africa and Liberia. The term 'high forest' is often used (Voorhoeve 1965 : 19) to describe a forest without stating an opinion of its origin. In French literature the term 'foret dense' (Aubreville 1938) is often used. It includes the ev ergreen rain forest as well as the mixed deciduous forest. 'Closed forest' (Richards 1964) is equivalent to th e 'foret dense' of modern French writers, and includes all types of lowland forest in which th e trees form a closed canopy and the ground i:; not covered with grass. The rain forest is often divided into mixed and single dominant communities. The greater part of the primary forest in the Nimba area consists of mixed forest composed of a very large number of species. The secondary forest (or degraded forest) is characterized by its physiognomy and th e abundance of trees from the lower strata of the primary Fig. 12. The canopy of the high forest. Mt Gbahm 800 m forest. It is in many cases ex tremely difficult to distinguish a mature secondary forest, e.g. a secondary forest of some hundred years age, from a primary one. It has been estimated that it takes 80 years for a moist forest species of tree to reach maturity (Cole 1968) and that the cycle towards a mature high forest lasts 300 to 400 years (Voorhoeve 1965 :20). It is very hard to characterize th e plant communities in tropical forests because they are very rich in species when compared to temperate forest stands of eq uivalent sizes (cf. Richards et al. 1940). Some ecologists name a closed forest using the em ergents in the A-stratum (th e canopy), but these emergents are generally few and far between and dominance by a few species is the exception rather than the rule. Even in the forest as a whole the majority of tree species are rare or occasional.aubreville (19 3 8) does not consider any true associations in the mixed rain forest of West Africa. The whole mix-

21 14 Dick Johansson Fig. 13. 'Farmland' in high forest. The forest is cut and burned. Rice, and cassawa (manioc) are cultivated in the clearing for a few years after which the farmland is abandoned. Mt Yullition 700 m Fig. 14. 'Farmland' in various stages of regrowth near a native village. West of Bona, ed forest in this case could be regarded as a single association of fluctuating composition. Richards (1964:262) states: "The failure of any one species to gain the upper hand in the mixture may be due, as Aubreville suggests, to all the species having very similar ecological requirements and responding in a very similar way to slight variations in the environment. As would be expected on grounds of probability, under these conditions the composition of these mixed communities will fluctuate in space and probably in time as well." The Liberian rain forest Through human interference only 35 % of Liberia is at present covered by high forest (Voorhoeve 1965: 19), although climatic and edaphic conditions would be favourable for it throughout most of the country. The Liberian rain forest is part of a rain forest belt that stretches from Ghana to Sierra Leone, and which is a western extension of the huge lowland rain forest of the Congo basin (Fig. 15). A region with dry climate from Western Nigeria to Eastern Ghana separates the two forested areas from each other. This break is commonly known as the 'Togo Dahomey gap'. The high forests of Liberia exhibit several features typical of tropical rain forests such as a large number of species which are mostly woody plants, e.g. many tree species (Cooper & Record 1931, Kunkel 1965, Voorhoeve 1965). The undergrowth is also mainly composed of woody plants. The herbaceous plants are mainly represented

22 Ecology of vascular epiphytes in West African rain fo rest 15 Fig. 15. Distribution of rain forests at low and medium altitudes. (From Keay 1959.) by epiphytes. A striking abundance of climbers, both herbaceous and woody (lianas) is also observed. Voorhoeve ( 1965) divides the Liberian rain forest into three categories: primary forest, old secondary forest that has reached climax, and old secondary forest which has not yet reached the climax. Concerning the distribution he remarks (1965: 19): "The first group appears to be extremely rare in Liberia, it is restricted to remote and limited localities of which only the gorges in the Nimba Mountains are known to me. Steep slopes prevented all agriculture there and the belief in numerous spirits made the people afraid to penetrate the area." In neighbouring Sierra Leone human activity started to take its toll in the forest very early. It is interesting to note that Adam Afzelius, in his Sierra Leone Journal (ed. by A.P. Kup, Uppsala 1967), already observed this. In his notes from May he states: "Fleming complained that there was now not to be found any timber on the Company ground, complaint which I have long expected, and from the manner of treating the wood, I am sure they won't 10 years hence have any timber in Sierra Leone, but in the highest and inaccessible mountains." Concerning the development of the Liberian forest interesting speculations have been presented : "It is possible that as recently as 300 years ago there was considerably less high forest area in Liberia than is found today. The subsequent sharp decline in population, as heavy tribal warfare and slaving activities exerted their drain, possibly coupled with the ravages of new diseases, would have permitted many cleared areas to complete their reversion to high forest. Over a period of several centuries, stands such as now occur throughout much of Liberia would probably develop. Their composition would differ notably from original stands in the same general area, but their density would be very similar. Only by such an hypothesis can the writer explain the over-all compositional inferiority of Liberian high forests as compared with those considered typical of the Ivory Coast and the Gold Coast." (Mayer 1951 :25.) A similar view is reflected in a report of the German Forestry Mission to Liberia, which express the opinion that all the forests of Liberia were once destroyed by shifting cultivation since remnants of villages have been found even in the most distant places of the forest. The human influence on the fauna may indirectly affect species' composition of the rain forest. The elephants that nowadays are almost extinct are said to promote the reproduction and distribution of Sacoglottis and Parinari trees. They eat the trees' fruits, and after passing through the alimentary canal the seed germinates extraordinarily well and at the same time is transported over a considerable distance. The high forest in the Nimba area that previously was sparsely populated is nowadays subject to a rapid deterioration (Adam 1966, 1970; Coe & Curry-Lindahl 1965). However, precautions recommended by I.U.C.N. are being taken by the Liberian government to spare certain areas from the devastating effects of shifting cultivation (Curry Lindahl 1969). Classification of the forest in the Nimba area Schnell (1952:444) divided the high forests into four groups: (1) Climax mesophile, caracterise par Triplochiton scleroxylon et Chrysophyllum perpulchrum. (2) Climax ombrophile a Lophira procera (3) Climax ombrophile a Ta rrietia uti/is (Heritiera uti/is) (4) Climax montagnard a Parinari excelsa

23 16 Dick Johansson Table 5. The number of trees, 40 cm or larger in diameter, in a forest at 525 m altitude east of Grassfield. Total area investigated, 4 ha. (From Adam 1969.) Piptadeniastrum 33 Ongokea Parinari excelsa 17 Terminalia Lophira 12 Erythroxylum Tarrietia (Heritiera) 10 Newtonia duparquetiana Calpocalyx 7 Funtumia Chlorophora 4 Nauclea Parkia 4 Lovoa Amp him as 2 Anthonotha fragrans Uapaca guineensis 2 Newtonia aubrevillei Anopyxis Klainedoxa Total 103 Adam (1969:384) recognizes two alliances in the rain forest in the lowlands surrounding the Nimba Mountains. On drained soils on peaks and slopes, Piptadeniastrum + Parinari excelsa + Parkia. In valleys and levelled areas an alliance with Lophira + Ta rrietia + Uapaca + Erythroxylum + Newtonia. Forest at altitudes below 800 m The species' composition of a forest east of the Grassfield Airstrip at 525 m has been investigated by Adam (1969: ). The canopy of this forest lies at approximately m height above the ground (Table 5). Remarkable is the dominance by the family Leguminosae. It is represented by seven genera, eight species and 49 individuals in the inventory. The species of this family constitute nearly 48 % of the total number of trees. Four families, Leguminosae, Rosaceae, Ochnaceae and Sterculiaceae together represent 85 % of the trees in the inventory. Adam ( 1969) also emphasizes the large differences in the flora composition betw en the Kitoma and the Nimba forests. The Kitoma forest is located 30 km south of the Nimba Mts. In Kitoma 177 individuals of Calpocalyx aubrevillei were found in an area of 15.2 ha, which gives 11.6 trees per ha. In Nimba 7 individuals were found which gives 1. 7 trees per ha. The figures for the Piptadeniastrum africanum are 0.9 trees per ha in Kitoma, and 8.2 trees per ha in Nimba. An inventory of the East Nimba National Forest and adjacent parts has been undertaken under the leadership of T.A. Gorgla (1969). This study included 15 species of trees that could be of commercial interest (Table 6). Although the study excludes Table 6. The number of 15 different timber trees, 45 cm or larger in diameter in East Nimba National Forest. Total area investigated, acres. (Source: Lamco J.V. Op. Co.) Genera or species Trade names Number Piptadeniastrum Dahoma 703 Chlorophora lroko 289 Lophira alata Azobe 28 1 Fagara Bahe 178 Tarrietia (Heritiera) Whismore 169 Terminalia ivorensis Frimare 117 Parkia Parkia 117 Erythrophleum Tali 101 Nauclea Bilinga 48 Entandrophragma Mahogany 30 Canarium White mahogany 29 Terminalia superba Limb a 21 Khaya Mahogany 15 Guarea Mahogany 6 Lovoa Mahogany 5 the very common Parinari excelsa and several other species, it gives valuable information of the proportions between the enumerated species. Farming activities in the high forest favour the development of many small and middle sized trees typical of the secondary forest, e.g. Musanga cecropioides (Moraceae), (Coombe & Hadfield 1962), Anthocleista nobilis. (Loganiaceae), Harungana madagascariensis (Guttiferae). Among the taller species easily observed in older secondary forests, Ceiba pentandra, Pycnanthus angolensis and Elaeis guineensis may be mentioned. Forest at altitudes above 1000 m In the higher parts of the Nimba Range a distinct change is noticed in the physiognomy and floral composition of the forest. These parts, which are very small and mainly consist of the narrow ridges, are covered by a low single dominant Parinari excelsa forest, reaching a height of m. The smaller trees have their ramifications close to the ground, and the field layer is usually built up by herbs. At m altitude the Aframomum herbs are typical. The single dominant Parinari forest is by no means something specific for the Nimba Mts but can be found at similar altitudes at e.g. Mount Wutivi in western Liberia ( Kunkel 1962 b), Mt Tonkoui in the Ivory Coast and Fouta Dj allon in Guinea. From Uganda a rain forest community occurring between 4500 and 5000 feet in. which Parinari excelsa fo rms about 80 % of the canopy is reported by Eggeling ( ).

24 Ecology of vascular epiphytes in West African rain forest 17 The canopy is not closed except in very minor sections. The light intensity in the lower parts of the forest and at the ground is therefore considerably higher than in the forest at the base of the mountains. Schnell (1952:338) remarks: "On retrouve dans les forets a Parinari excelsa du Nimba et des massifs voisins, un certain nombre de caracteres deja signales dans les forets montagnardes, par J. Lebrun, H. Scaetta (1973), Schluter, Eidmann: faible hauteur des arbres, tronc ramifie a quelques metres du sol, reduction du nombre des especes, reduction du nombre des lianes, abondance des epiphytes (surtout Cryptogames), feuillage generalement persistant." On the crests at m altitude the Parinari excelsa forest is in total dominance, but a little lower down at m trees of a rather large number of species can be found (Adam 1970: ). Seasonal changes in the fo rest In the Nimba forest, not much seasonal changes in leaf-fall are noticed. The evergreen trees at the various strata appear luxuriant at all times of the year because progressive leaf-fall occurs, while the few deciduous trees appear dormant only for a rather short time. These deciduous trees are so few and scattered that their presence does not alter the face of the forest. Bernhard-Reversat et al. ( 1972 :218) reveal that the maximum leaf-fall of various species in the Ivory Coast do no coincide, and there is no correlation with the precipitation, but rather with the incident radiation-a view that earlier had been stressed by Hopkins ( 1970) in a study of the seasonal growth in S Nigeria. Furthermore, the interspecific variation of the start and the length of the leaf-fall period at the same locality also tend to obscure the presence of these trees. Some of the more common deciduous trees in the forest are.{jombax buonopozense, Chlorophora regia, Ceiba pentandra, Daniellia ogea, Entandrophragma utile, Piptadeniastrum africanum, Rhodoghaphalon brevicuspe, Terminalia ivorensis, and Triplochiton scleroxylon. In a phenological study of Chlorophora regia at Njala, Sierra Leone, Cole (1968 :76) found not only an interspecific variation in leaf shedding time between trees growing within a radius of 100 yards, but also a difference in the length of the leafless period between male and female trees. The phorophytes (the host trees) As stated earlier the rain forest is very rich in tree species. When a doubt in the determination of species has arisen, the epiphyte flora has simply been recorded without correlation to a specific phorophyte. The list of phorophytes that briefly will be presented is dominated by medium to large sized trees. For each phorophyte a few properties that might be of importance for the epiphyte flora have been added. The majority of these phorophytes are included in the excellent study of the Liberian rain forest by Voorhoeve ( 1965). The properties of the phorophytes refer to tall specimens and it must be emphasized that many of these properties are rather vague and dependent on environmental influence. The roughness of the bark refers to the basal parts of large branches, and the terms low, medium and tall refer to the classes 10-20, 21-35, 36 m or more, respectively. The phorophytes are presented in alphabetical order without regard to family. Phorophytes in high fo rest Albizia glaberrima (Schum. & Thonn.) Benth. (Leguminosae) Large. Bark smooth. Crown open, spreading. Deciduous. Albizia zygia (DC.) MacBride (Leguminosae) Medium. Bark rather smooth. Crown open, spreading. Deciduous. Alstonia boonei De Wild. (Apocynaceae) Large. Bark rather smooth, soft. Crown fairly open, heavily branched. Evergreen. Amphimas pterocarpoides Harms (Leguminosae) Medium-large. Bark scaly. Crown dense. Deciduous. (Fig. 16). Anthocleista nobilis G. Don (Loganiaceae) Small. Bark with thorns. Crown open. Evergreen. Anthonotha fragrans (Bak.f.) Exell & Hillcoat (Leguminosae) Medium-large. Bark scaly. Crown dense. Deciduous. Antiaris toxicaria (Rumph. ex Pers.) Lesch. var. welwitschii (Engl.) Corner (Moraceae) Large. Bark smooth, thick. Crown fairly open. Briefly deciduous. Berlinia confusa Hoyle (Leguminosae) Medium-large. Bark smooth or scaly. Crown rather dense. Evergreen. Bombax buonopozense Beauv. (Bombacaceae) Medium. Rather smooth bark. Crown heavily branched. Deciduous. Bussea occidentalis Hutch. & Dalziel (Leguminosae) Medium. Bark smooth. Crown dense. Evergreen. Calpocalyx aubrevillei Pellegr. (Leguminosae) Medium. Bark smooth. Crown small. Evergreen.

25 18 Dick Johansson A Fig. 16. Trees common in the Nimba area. (A) Heritiera uti/is, (B) Piptadeniastrum africanum, (C) Amphimas pterocarpoides, (D) Lophira alata, (E) Ceiba pentandra, (F) Entandrophragma utile.

26 Ecology of vascular epiphytes in West African rain fo rest 19 Canarium schweinfurthii Engl. (Burseraceae) Large, often emergent. Crown rather open. Bark smooth. Briefly deciduous. Ceiba pentandra (L.) Gaertn. (Bombacaceae) Large to emergent. Bark smooth. Crown rather open. Deciduous. (Fig. 16). Chidlowia sanguinea Hoyle (Leguminosae) Small-medium. Bark smooth. Crown small, rather dense. Evergreen. Chlorophora regia A. Chev. (Moraceae) Large. Bark thick and rough. Crown dense. Briefly - deciduous. Chrysophyllum perpulchrum Mildbr. ex Hutch. & Dalziel (Sapotaceae) Medium. Bark smooth. Crown dense. Evergreen. Combretodendron macrocarpum (P. Beauv.) Keay (Lecythidaceae) Large. Bark thick, deeply grooved. Crown fairly dense. Briefly deciduous. Coula edulis Baill. (Olacaceae) Medium. Bark rough and scaly. Crown dense. Evergreen. Cryptosepalum tetraphyllum (Hook. f.) Benth. (Leguminosae) Medium. Bark smooth, superficially cracked. Crown open. Briefly deciduous. Daniellia ogea (Harms) Rolfe ex. Holl. (Leguminosae) Large to emergent. Bark smooth. Crown small, fairly open. Deciduous. Distemonanthus benthamianus Bail. (Leguminosae) Medium-large. Bark smooth, defoliating. Crown fairly open. Deciduous. Entandrophragma utile (Dawe & Sprauge) Sprauge (Meliaceae) Large-emergent. Bark grooved, thick. Crown dense. Briefly deciduous. (Fig. 16). Erythrophleum ivorense A. Chev. (Leguminosae) Large. Bark rough. Crown very dense. Evergreen. Fagara tessmannii Engl. (Rutaceae) Medium. Bark rough, with thorns. Crown open, translucent. Evergreen. (Fig. 17). Guarea cedrata (A. Chev.) Pellgr. (Meliaceae) Medium-large. Bark smooth, scaly. Crown fairly open. Evergreen. Heritiera uti/is (Sprauge) Sprauge (Sterculiaceae) Medium. Bark thin, peeling. Crown dense. Evergreen. (Fig. 16). Khaya anthotheca (Welw.) C. DC. (Meliaceae) Large-emergent. Bark smooth, sometimes peeling. Crown rather dense. Deciduous. Lophira alata Banks ex Gaertn. f. (Ochnaceae) Large-emergent. Bark scaly or grooved. Crown fairly open. Briefly deciduous. (Fig. 16). Lovoa trichilioides Harms (Meliaceae) Large. Bark scaly. Crown fairly open. Evergreen. Fig. 17. Some trees that seldom carry epiphytes. (A) Terminalia ivorensis, (B) Terminalia superba, (C) Fagara tessmannii. Mammea africana Sabine (Guttiferae) Large. Bark rather rough, scaly. Crown small, dense. Evergreen. Mitragyna ciliata Aubrev. & Pellegr. (Rubiaceae) Medium-large. Bark thin, scaly. Crown rather dense. Evergreen. Nauclea diderrichii (De Wild) Merrill (Rubiaceae) Large. Bark rather smooth, or somewhat scaly. Crown small. Evergreen. Parinari aubrevillei Pellegr. (Rosaceae) Medium. Bark smooth or somewhat scaly. Crown dense. Evergreen. Parinari excelsa Sabine (Rosaceae) Medium-large. Bark scaly. Crown fairly open. Evergreen. (Fig. 18). Parinari glabra Oliv. (Rosaceae) Large. Bark smooth, scaly. Crown rather open. Evergreen. Parkia bicolor A. Chev. (Leguminosae) Large. Bark thinly scaly. Crown fairly open. Deciduous. Pentaclethra macrophylla Benth. (Leguminosae) Medium-large. Bark irregularly scaly. Crown dense. Evergreen.

27 20 Dick Johansson Triplochiton scleroxylon K. Schum. (Sterculiaceae) Large-emergent. Bark rather smooth, more seldom scaly. Crown dense. Deciduous. (Fig. 77). Uapaca guineensis MUll. Arg. (Euphorbiaceae) Medium. Bark rough, cracked, scaly or flaky. Crown dense. Evergreen. (Fig. 76). Vitex micrantha Giirke (Verbenaceae) Small-medium. Bark grooved. Crown rather dense. Evergreen. Fig. 18. Parinari excels a. Grassfield 5 50 m. Pentadesma butyracea Sabine (Guttiferae) Medium. Bark rough. Crown rather dense. Evergreen. Piptadeniastrum africanum (Hook. f.) Brenan (Leguminosae) Large-emergent. Bark smooth. Crown open and spreading. Briefly deciduous. (Fig. 16). Pycnanthus angolensis (Welw.) Warb. (Myristicaceae) Medium. Bark fissured or scaly. Crown open. Evergreen. Rhodognaphalon brevicuspe (Sprauge) Roberty (Bombacacae) Large-emergent. Bark scaly, soft. Crown rather dense. Deciduous. Sacoglottis gabonensis (Baill.) Urb. (Humiriaceae) Large. Bark scaly, untidy. Crown very large, open, spreading. Evergreen. Te rminalia ivorensis A. Chev. (Combretaceae) Large. Bark deeply grooved. Crown rather open. Deciduous. (Fig. I 7). Terminalia superba Engl. & Diels (Combretaceae) Large. Bark grooved and scaly. Crown open. Deciduous. (Fig. 17). Phorophytes around villages and in fa rmlands This group includes cultivated trees of various origins as well as trees of the young secondary forest and grasslands. The very common oil palm is also listed here because of its importance for epiphytic ferns. Coffe a sp. (Rubiaceae) The coffee trees in cultivation are of heterogeneous origins. C. liberica Bull ex Hiern. and C. canephora Pierre ex Froehner. Low. Bark smooth or somewhat rough. Crown open. Evergreen. Cola nitida (Vent.) Schott & Endl. (Sterculiaceae) The common cola tree, cultivated around the villages for its edible caffein-rich seeds. Low-medium. Bark fissured, soft. Crown dense. Evergreen. Cussonia barteri Seemann (Arali'aceae) Low savanna tree. Bark deeply furrowed. Crown open, spreading. Deciduous. Delonix regia (Boj. ex Hook.) Raf. (Leguminosae) This tree is grown as an ornamental ("Flame of the forest" or "Flamboyant"). Low-medium. Bark smooth. Crown open, spreading. Foliage translucent. Deciduous. Elaeis guineensis Jacq. (Palmae) The oil palm. Low-medium. Hevea brasiliensis (A. Juss.) Mull. Arg. (Euphorbiaceae) The rubber tree. It is estimated (Kunkel 1965: 12) that this covers I % of the total land surface of Liberia. However, there are only minor rubber plantations within the Nimba area. Mangifera indica L. (Anacardiaceae) The well-known Mango tree (locally called Plum tree). Medium. Bark rough. Crown dense. Evergreen. Musanga cecropioides R. Br. (Moraceae) The common umbrella tree that rapidly colonizes old farmlands etc. Low-medium. Bark smooth. Crown rather open. Evergreen. Te rminalia catappa L. (Combretaceae) Cultivated for their edible seeds ("Almond tree") or as an ornamental. Low-medium. Bark fissured. Crown spreading, open. Deciduous. Th eobroma cacao L. (Sterculiaceae) The cacao tree. Low. Bark smooth. Crown dense. Evergreen.

28 11. The epiphytic flora Composition and geographical distribution The flora of Africa is generally considered to be poorer in species than those of other tropical regions. The orchids, of which the majority are epiphytes, have been estimated to comprise two to three thousand species in Africa south of the Sahara, including the island of the Malagasy republic (Madagascar), and the islands of the Seychelles, Comoro, and the Mascarene groups (Stewart & Campbell 1970). This figure may be compared to the more than three thousand species of orchids recorded in the South American republic of Colombia alone. Another example from the orchid family may illustrate the relative poverty of species. In the Zaire (former Belgian Congo) there are a total of 414 species (Nihoul et al. 1964), compared with an estimated 5000 in Malaysia alone (Van Steenis 1938). The general poverty of the African rain forest has been suggested to be a result of past climatic changes (Mildbraed 1922). Stewart (Stewart & Campbell 1970: 11) explains the relative low number of orchid species in Africa: "Vast tracts of the land mass are unsuitable as orchid habitats." However, the poverty of epiphytic plants in the African rain forest is by no means an exception. From Sarawak, Borneo, Richards (1936:15-16) remarks: "One of the most striking features of the Sarawak rain forest, especially when compared with that of tropical South America, is the poverty of the epiphytic vegetation both in species and individuals." The vascular epiphytic flora of the investigated area includes a total of 153 species (the facultative epiphytes excluded). The epiphytes may be divided into three major groups: ( 1) the Pteridophytes with Fig. 19. Records of Angraecum birrimense (O) and Cyrtorchis monteiroae (e). Fig. 20. Records of Polystachya saccata (O) and Rangai!'ris rhipsalisocia (e).

29 22 Dick Johansson Fig. 21. Records of Polystachya dalzielii (0) and P. leonensis ( ). (A) Picket Hill (B) Mt Kakouima (C) Loma Mts (D) Wologisi Range (E) Nimba Mts (F) Massif de Dans (G) Mt Cameroon Fig. 22. Records of A ngraecum classensii < ), Angraecopsis elliptica (e), Diaphananthe densiflora (.&) and Stolzia repens (0). Fig. 23. Records of Bulbophyllum magnibracteatum (.&), B. pavimentatum (0) and B. schimperanum (e). Fig. 24. Records of Begonia rubro-marginata (0) and Elaphoglossum isabelense (e).

30 Ecology of vascular epiphytes in West African rain fo rest spp., (2) the Orchids with 101 spp. and (3) the remammg species, called the Other vascular epiphytes, with 13 spp. This grouping is followed in the list and analyses. The orchid flora seems to be composed of three different elements: (A) Species of the rain forest, e.g. Angraecum birrimense and Cyrtorchis monteiroae, (B) Species of the deciduous forest, e.g. Ansellia africana and Rangaiiris rhipsalisocia, (C) and species restricted to high altitudes, e.g. Polystachya dalzielii and Polystachya leonensis (Figs ). A few species, e.g. Bulbophyllum inflatum, have only been reported from the Nimba Mountains in Liberia. However this endemic character may only result from insufficient knowledge (cf. Schnell 1952:407 and Curry-Lindahl 1969:23). Some species with a ± wide distribution in tropical Africa, e.g. Antrophyum immersum and Nephrangisfiliformis are in West Africa restricted to the Nimba region. Several other species have had their previously known area of distribution extended westwards, e.g. Angraecum classensii, Angraecopsis elliptica, Begonia rubro-marginata, Bulbophyllum magnibracteatum, B. pavimentatum, B. schimperanum Diaphananthe densijlora, Elaphoglossum isabelense, and Stolzia repens (Figs ). A total of thirty-two species were recorded in Liberia for the first time. List of species The following list for the Nimba area includes for each species (I) their known geographical distribution in West Africa, (2) a brief autecologic description, and (3) (for the orchids) some field characteristics. The notes on geographical distribution are based on F. W.T.A. 2nd ed. (1954, 1959, 1968) on Schnell 1952, Harley 1955, 1956, 1959, Alston 1959, Kunkel 1962 a, Ake Assi 1963, Guillaumet 1967, A dam 19 71, and my own collections. The abbreviations of the countries follow F.W.T.A. 2nd ed. 1963, 2. The autecological notes are based upon the quantitative studies (Tables 27-29) and general observations, and the terminology for light and substrate is in accordance with the one used during the field work. The abundance is given in three classes, subjectively estimated, common, rather common and rare. The flowering time is expressed in two months periods (when the most frequent flowering occurs). A brief description of the plant is added for the orchids only. The particulars of the flowers are, due to their limited duration, mostly of minor importance in the field work. In most cases the determination has to be based on vegetative characteristics only. The inflorescences which often remain on the plant for several years have proved useful. (A field key to the epiphytic orchids of Ghana based on vegetative characteristics has been presented by Hall & Bowling 1969, and in a key to the orchids of Zaire, former Belgian Congo, Tournay (19 55) used a similar technique.) Some species are difficult to determine even in a flowering state. The methods used to distinguish such species are discussed in connection with the presentation of the species. The size of the plants may vary widely due to environment. In the following list the grouping previously presented is followed. Within each of the three groups the names of the genera and their species are given in alphabetical order. The first set of my collections (with few exceptions), is kept in the Herbarium of the Institute of Systematic Botany at the University of Uppsala (UPS). A second (almost complete) set has been given to the Kew Herbarium (K). For each species a voucher is quoted, e.g. D.J (UPS). Pteridophytes Antrophyum Kaulf. A. mannianum Hook. Guin., S.L., Lib., S.Nig., Cam. A species of the high forest. Moss-covered trunks high above the ground or on the outer branches. "Occasionally on mossy boulders" (Harley 1955:9 I). Open shade, bark. Rare. D.J. 516 (K). A. immersum (Bory ex Willd.) Mett. Lib. In West Africa only recorded from the Nimba area. In humid habitats, almost exclusively on the trunks of large trees. Heavy - open shade, bark - minor humus deposits. Rare. D.J. 554 (K), 582 (UPS). Arthropteris J. Sm. A. monocarpa (Cordem.) C. Chr. Guin., S.L., Lib., lv.c., Ghana, Cam. Basal parts of trunks (particularly on the 'trunks' of the tree fern Cyathea manniana). Damp habitats in heavy shade, minor humus deposits. Rather common, similar to A. orientalis, which, however, occurs in better lit habitats. D.J (K, UPS). A. palisoti (Desv.) Alston Lib., Iv.C., Ghana, S.Nig., Cam.

31 24 Dick Johansson Fig. 25. Asplenium barteri. Harley {1955) reports three localities in Liberia. Middle part of branches of tall trees. Open shade, bark. Rare. D.J. 558 (K). A. orientalis (Gmel.) Posth. Guin., S.L., Lib., Jv.C., Ghana, N.Nig., S.Nig., Cam. Basal parts of large branches. Open shade, humus deposits. Rather common. D.J. 806 (K, UPS). Asplenium L. A. aethiopicum (Burm.) Becherer Guin., S.L., Lib., N.Nig., Cam. Harley {1955:84) and Kunkel (1962 :40) report it from various parts of Liberia. Trunks and branches. Open shade, humus deposits. Rare. D.J. 782 (K, UPS). A. africanum Desv. Guin., S.L., Lib., Jv.C., Ghana, S.Nig. Basal parts of large branches. Open shade, humus deposits. Rare. D.J. 852 (K), 834 (UPS). The roots hold humus in a fashion similar to Microsorium punctatum, which it resembles at a distance. A. barteri Hook. Guin., S.L., Lib., Jv.C., Ghana, Cam. Basal parts of the trunks or moss-covered rocks. Humid habitat. Heavy shade, varying substrate. Common. D.J. 555 (K), 629 (UPS). Fig. 25. A. dregeanum K unze Guin., S.L., Lib., Jv.C., Ghana, Togo, S.Nig., N.Nig., Cam. On trunks in humid habitats. Heavy shade and humus deposits. Rather common at altitudes above 1000 m. D.J. 513 (K, UPS). A. geppii Carruth. Syn : A. anisophyllum Kunze Guin., S.L., Lib., Jv.C., Ghana, S.Nig., Cam. Basal ramifications of tall trees. Open shade, large humus deposits. Rather common. D.J. 624 (K), 5 70 (UPS). A. hemitomum Hieron. Guin., S.L., Lib., Jv.C., Ghana, N.Nig., S.Nig., Cam. On trunks, often rather close to the ground. Open shade, humus deposits. Rare. D.J (K, UPS). Fig. 26. Drynaria laurentii, sterile and fertile leaves. A. megalura Hieron. ex Brause Guin., S.L., Lib., Jv.C., Ghana, Togo. Middle - outer parts of large branches. Full sun, humus deposits. Common. D.J. 780 (K, UPS). A. variable Hook. var. paucijugum (Ballard) Alston. Guin., S.L., Lib., Jv.C., Ghana, Cam. This taxon is often referred to as Asplenium paucijugum Ballard (Harley 1955:86, Kunkel 1962:43). Basal parts of trunks of tall trees or on moss-covered rocks. Wet and humid habitats. Heavy shade, humus deposits. Rather common. D.J. 589 K, 786 (UPS). Davallia Sm. D. chaerophylloides (Poir.) Steud. Guin., S.L., Lib., Jv.C., Ghana, Togo, N.Nig., S.Nig., Cam. Middle parts of large branches. Open shade - full sun, bark, - minor humus deposits. Rather common. D.J. 660 (K, UPS). Drynaria (Bory) J.Sm. D. laurentii (C hrist.) Hieron. Guin., S.L., Lib., Jv.C., Ghana, Togo, S.Nig. Basal - middle parts of large branches. Open shade - full

32 Ecology of vascular epiphytes in West African rain fo rest 25 sun. Colonizes bark surfaces. This is probably the most common epiphyte of the Nimba area. Several other epiphytes are associated to this fern in all types of forests. D.J. 431 (UPS). Fig. 26. Elaphog/ossum Schott E. barteri (Bak.) C.Chr. Guin., S.L., Lib., lv.c., S.Nig., Cam. Basal parts of trunks. Heavy - open shade, large humus deposits. Rare. D.J. 553 (K), 697 (UPS). E. chevalieri Christ. Guin., S.L., Lib., lv.c. Basal parts of moss-covered trunks. Heavy - open shade, humus deposits. Restricted to altitudes above 1100 m. Rare. D.J. 642 (K, UPS). E. isabelense Brause Lib. (new), F.Po. Middle - basal parts of large branches of tall trees. Open shade - full sun, bark or minor humus deposits. Common. D.J. 495 (K, UPS). E. kuhnii Hieron. S.L., Lib., Cam. Basal parts of tall trees, or rotten logs. Humid habitats. Heavy shade, humus deposits. Rare. D.J. 493 (K), 646 (UPS). E. salicifolium (Willd. ex Kaulf.) Alston Guin., Lib. (new), Cam. Widely distributed over the phorophyte, mostly in the basal parts of the large branches. Full sun - open shade, bark. Common. D.J. 644 (K), 825 (K, UPS). Lomariopsis Fee L. guineensis (Underw.) Alston Guin., S.L., Lib., Iv.C., Ghana, Togo, Dah., S.Nig., Cam. Reported from various parts of Liberia (Harley 1955:87, Kunkel 1962:52). Basal parts of trunks. Heavy - open shade, bark. Rare. Rooted at the base of the phorophyte, which it climbs. Very tightly attached to the bark by short rootlets of the rhizome. After some time it normally loses contact with the ground. D.J. 777 (K), 482 (UPS). Fig Loxogramme (Biume) Presl L. lanceolata (Sw.) Presl Guin., S.L., Lib., Iv.C., Ghana, N.Nig., S.Nig., Cam. Mainly on the trunks. Open shade, minor humus deposits. Rare. D.J. 833 (K), 742 (UPS). Lycopodium L. L. mildbraedii Hert. Syn: L. dacrydioides Bak. Guin., S.L., Lib. (new), Cam. On moss-covered branches and trunks. Open shade, minor humus deposits. Common at altitudes above 1000 m. D.J. 503 (K, UPS). L. warneckei (Hert.) Alston Guin., S.L., Lib., Jv.C., Cam. In the outer - middle parts of large branches. Full sun, Fig. 27. Nephrolepis biserrata. humus deposits. Rather common. Often associated with Drynaria laurentii. D.J. 535 (K, UPS). Microgramma Presl M. owariensis (Desv.) Alston Guin., S.L., Lib., Jv.C., Ghana, Togo, N.Nig., S.Nig., Cam. On trunks and branches. Open shade, minor humus deposits. Common on trees and palms around villages, less frequent in the high forest. From Liberia a new form, f. nana, has been described (Kunkel 1962:37-38). D.J. 567 (K, UPS). Microsorium Link M. punctatum (L.) Cope!. Guin., S.L., Lib., Ghana, S.Nig., Cam. Basal - middle parts of large branches. Open shade - full sun, minor humus deposits. Common. The debris held by the root system is often utilized by other epiphytes. D.J. 794 (UPS). Nephrolepis Schott N. biserrata (Sw.) Schott Guin., S.L., Lib., Jv.C., Ghana, Togo, S.Nig. Epiphytic or terrestrial, equally common in both habitats.

33 26 Dick Johansson As epiphyte mainly at the basal part of the large branches. Open shade - full sun, large humus deposits. Common in secondary forests (particularly at the leaf bases of oil palms). Rare in the high forest. Used by the natives in treatment of snake bites and urinary complaints (Harley 194 1). D.J. 765 (K). Fig. 27. N. undulata (Afzel. ex Sw.) J.Sm. Guin., S.L., Lib., Iv.C., Ghana, Togo, Dab., N.Nig., S.Nig., Cam. Basal - middle parts of large branches. Open shade - full sun, minor - large humus deposits. Occurs in several epiphyte communities, particularly with Platycerium ferns. Common. D.J. 707 (K, UPS). Oleandra Cav. 0. distenta Kunze Guin., S.L., Lib., Iv.C., Ghana, Togo, S.Nig., Cam. Around the basal ramifications of the tall trees. Open shade, humus deposits. Common in the high forest and on the trunks of the oil palm in farmlands. The humus held by this species is utilized by several other epiphytes. D.J. 805 (K), 427 (UPS). Fig. 80. Phymatodes Presl P. scolopendria (Burm.) Ching. Guin:, S.L., Lib., Iv.C., Ghana, Dab., Togo, N.Nig., S.Nig., Cam., F.Po. Basal - middle parts of large branches in high forest. On trunks of trees and oil palms around villages. In high forest in open shade, bark - minor humus deposits. In secondary forests it is found in a wider range of habitats. Common. D.J. 532 (K), 831 (UPS). Platycerium Desv. P. angolense Welw. ex Hook. Guin., S.L., Lib., Iv.C., Ghana, N.Nig., S.Nig. Middle parts of large branches of emergent trees or on the trunks of trees left in farmlands. Full sun, bark. Common on large Triplochiton scleroxylon trees in the Yekepa community. Rare in the high forest. In Iv.C. this species occurs mainly in the deciduous forests in the northern part of the country (Boyer 1964 ). D.J. 809 (UPS). Fig. 85. P. stemaria (P. Beauv.) Desv. Guin., S.L., Lib., Jv.C., Ghana, Dab., N.Nig., S.Nig., Cam. In its ecology very similar to P. angolense. Rare in high forest, more common on tall trees in secondary forest. In Iv.C., this species occurs mainly in the secondary evergreen forest in the southern part of the country, and is ± absent in the primary rain forest (Boyer 1964). D.J (UPS). Fig. 84. Pyrrosia Mirb. P. mechowii (Hieron.) Alston Guin., Lib. (new), N.Nig., Cam. Middle parts of large branches. Open shade - full sun, minor humus deposits. Humid habitats, e.g. swamp forests. Almost exclusively on Mitragyna ciliata. Rare. D.J. 808 (K, UPS). Tectaria Cav. T. angelicifolia (Sebum.) Copel. Guin., S.L., Lib., Iv.C., Ghana, N.Nig., S.Nig., Cam. In the basal parts of tall trees (or on rocks). Frequently on the trunks of Cyathea manniana. Heavy shade, on various kinds of substrate. Common. D.J (UPS). T. fernandensis (Bak.) C.Chr. Guin., S.L., Lib., Iv.C., Ghana, Togo, S.Nig., Cam. Basal parts of large trees. Heavy shade, humus deposits. Only in very humid habitats. Rare. D.J. 795 (K). Vittaria Sm. V. guineensis Desv. Guin., S.L., Lib., Jv.C., Ghana, Togo, S.Nig., Cam. On all parts of the trees, but mainly in the basal and middle parts of large branches. Open shade, minor humus deposits. Often associated with Microsorium punctatum. Common. D.J. 762 (UPS). Xiphopteris Kaulf. X. oosora (Bak.) Alston Guin., S.L., Lib. (new), Cam., F.Po. Basal - central parts of large branches. Open shade, humus deposits. At altitudes above 1200 m. Rather common. D.J. 826 (K), 514 (UPS). X. serrulata (Sw.) Kaulf. S.L., Guin., Lib., Jv.C., F.Po. Middle parts of large branches. Open shade, minor humus deposits. Rare. D.J. 592 a (UPS). X. villosissima (Hook.) Alston Guin., S.L., Lib., Jv.C., Cam., F.Po. Basal and middle parts of large branches. Open shade, minor humus deposits. At altitudes above I 100 m. Rare. D.J. 518 (K), 827 (UPS). Orchids Aerangis Rchb. A. biloba (Lindl.) Schltr. Sen., Guin., S.L., Lib., Iv.C., Ghana, Togo, N.Nig., S.Nig., Cam. Basal or middle parts of large branches. Full sun - open shade, bark - minor humus deposits. Common. Growing tips of roots orangish-pink (Piers 1959, Moir 1963, Sanford 1968). Stem short, woody. Leaves crowded at the apex of the stem, 8-18 cm, oblanceolate, curved and unequally bilobed, dark green. Inflorescence longer than the leaves, many flowered, somewhat pendulous. Flowers white, star-like. June-July. D.J. 562 (UPS). Fig. 28. A. laurentii (De Wild.) Schltr. Lib., Ghana. Anywhere on the large branches. Full sun, bark. Rare. Erect, cm. Stem short, woody. Leaves strap-shaped, arranged in a fan-shaped manner, acutely v-shaped in cross-section, rather thick and stiff. Inflorescence longer than the leaves, zigzag-shaped rachis. Flowers white, with a long spur. Jan.-Febr. The zigzag rachis distinguishes it from Rangae'ris muscicola. Plectrelminthus caudatus has also a zigzag rachis, but leaves of a different shape. DJ. 449 (K), 411 (UPS).

34 Ecology of vascular epiphytes in West African rain fo rest 27 Ancistrochilus Rolfe A. rothschildianus O'Brien Guin., S.L., Lib., Iv.C., S.Nig., Cam. Basal or central parts of large branches, occasionally on moss-covered trunks. Open shade, humus deposits. Rather common. Erect, cm. Pseudobulbs crowded, conical - pyriform, 2-3 cm high, up to 5 cm in diameter, longitudinally sulcated, green. Leaf cm, lanceolate oblanceolate, thin, ribbed, dark green. Inflorescence long, curved. Flower large (8 cm in diam.). Oct.-Nov. D.J. 703 (UPS). Fig. 29. Fig. 28. Aiirangis biloba. Ancistrorhynchus Finet A. capitatus (Lindl.) Summerh. S.L., Lib., S.Nig. Basal parts of large branches or on trunks. Open shade - full sun, bark - minor humus deposits. Common. Erect, cm. Stem short, woody. Leaves crowded, curved, x cm, with a few teeth at apex. Inflorescences short, dense, on the stem below the leaves, long persistant. Flowers small, white. July-Aug. D.J. 531 (K, UPS). A. cephalotes (Rchb.f.) Summerh. Guin., S.L., Lib., Iv.C., Ghana, N.Nig., S.Nig. Trunks or the middle parts of large branches. Full sun, bark. Common. Erect or scrambling. Stem long, woody, twisted, covered with old leatbases and inflorescences. Leaves 8-20 cm, linear, apex bilobed. Inflorescences on the stem below the leaves, short, with a very large number of flowers. Flower white, small. June-July. D.J. 524 (K, UPS). Fig A. clandestinus (Lindl.) Schltr. S.L., Lib., lv.c., Ghana, N.Nig., S.Nig., Cam. Trunks or basal parts of larger branches. Full sun, bark. Rare. Erect, in the Nimba area a small to medium-sized plant, stem short, woody. Leaves 5-8 x cm, stiff and fleshy, leathery, apical lobes of the leaf very acute and Fig.29. Ancistrochilus rothschildianus.

35 28 Dick Johansson unequal in length. (F.W.T.A. 2nd ed. 3:1, 1968:270 gives the length of the leaves up to 180 cm.) Inflorescence very short, dense, from the stem below the leaves. Flowers white, small. May-June. The leaves are similar to Chamaeangis vesicata, but the species is distinguished by the inflorescence. D.J. 804 (UPS). A. recurvus Finet Guin., Lib. (new), Ghana, S.Nig., Cam. Occurs in the same habitats as A. clandestinus. Rare. Leaves 8-15 x cm, not particularly stiff. Floral parts as A. clandestinus, but leaves of a different shape. D.J. 810 (UPS). Angraecopsis Summerh. A. elliptica Summerh. Lib. (new), N.Nig., Cam. Basal or central parts of large branches. Open shade, humus deposits. Rare. Erect, cm. Stem very short. Leaves 4-10 x 1-2 cm, ligulate, curved. Inflorescence filiform, ± as long as the leaves. Flowers very small and tiny, yellow-green. Aug.-Sept. D.J. 611 (K, UPS). Fig. 30. A ngraecum birrimense. Angraecum Bory A. birrimense Rolfe S.L., Lib., Iv.C., Ghana, S.Nig., Cam. Trunks, basal or middle parts of large branches. Open shade, humus deposits. Common. A climbing and pendulous plant, 1-2 m long. Stem woody. Leaves 6-12 cm, scattered, lanceolate - elliptical, bilobed, fleshy, light green. Inflorescence short. Flowers large. Tepals light green, lip white with a green centre. July-Aug. D.J. 436 (K), 568 (UPS). Fig. 30. A. chevalieri Summerh. Guin., Lib., Jv.C., Ghana, N.Nig., S.Nig. Basal parts of large branches. Open shade - full sun, bark - minor humus deposits. Rare. Climbing, somewhat pendulous, stem woody. Leaves 3-7 cm, narrowly strapshaped, fleshy, leathery. Inflorescence short. Flowers yellowish, small. June-July. D.J (UPS). A. classensii De Wild. Lib. (new), Nig. Trunks and branches of small trees, close to the ground. Full sun - open shade, bark. Rare. Ascending, cm long. Stem woody. Leaves 6-10 x cm, oblong - obovate, bilobed at apex. Inflorescences erect, 5-25 cm, usually much longer than the leaves. Flower ochracoloured. May-June. D.J. 512 (K, UPS). A. distichum Lindl. Guin., S.L., Lib., Iv.C., Ghana, Dah., N.Nig., S.Nig., Cam. Trunks or basal parts of large branches. Full sun - open shade, bark - minor humus deposits. Common. A dense tuft of branching stems, ± erect, 8-20 cm. Leaves 1.0 x 0.7 cm, fleshy, triangular, distichuous. Flower sessile, white, small. May-June. D.J. 525 (UPS). Fig. 59. A. podochiloides Schltr. Lib., Iv.C., S.Nig., Cam. Trunks of tall trees. Open shade - full sun, bark. Rare. Pendulous, cm. Leaves crowded, 1-2 cm, narrowly )anceolate - oblong, fleshy, hard. Flower small, sessile, white. June-July. D.J. 610 (UPS). Fig. 59. A. subulatum Lindl. S.L., Lib., lv.c., Ghana, S.Nig., Cam. Basal or middle parts of large branches. Open shade, minor humus deposits. Rare. Erect - pendulous. Leaves 3-8 x cm, subulate - terete, falcate. Flowers small, sessile, white. June-July. Two other species with terete leaves are Nephrangisfiliformis and Tridactyle tridentata. They are distinguished by a marked pendulous growth. D.J. 557 (K), 766 (UPS). Ansellia Lindl. A. africana Lindl. Lib., Jv.C., Ghana, S.Nig., F.Po. Basal or middle part of large branches. Full sun, large humus deposits. Erect cm. Pseudobulb cm. Leaves lanceolate, from the upper part of the pseudo bulb. Flower yellow witl:i large chocolate brown spots. Feb. March. Numerous erect aerial roots occur at the base of the plant (cf. Graphorchis lurida). D.J. 790 (UPS). Figs. 31 and 62.

36 Ecology of vascular epiphytes in West African rain fo rest 29 Fig. 32. Brachycorythis kalbreyeri. Fig. 31. Ansellia qfricana.photo: Harvey Boettcher. Bolusiella Schltr. B. ta/botii (Rendle) Summerh. S.L., Lib., Iv.C., Ghana, S.Nig. Outer parts of large branches. Full sun, bark. Rather common. Erect, 5-8 cm. Stem very short, woody. Leaves 2-4 cm, arranged in a fan-like manner, narrowly lanceolate, distinctly narrowed in the upper half, compressed, fleshy. Inflorescence thin, considerably longer than the leaves. Flowers scattered, minute, white. June-July. D.J. 438 (K), 1054 (UPS). Fig Brachycorythis Lindl. B. kalbreyeri Rchb. f. Guin., S.L., Lib., Cam. Basal parts of the trunks. Open shade, large humus deposits. Rare. Erect, up to 40 cm. Stem slender, spotted purple. Leaves evenly distributed along the stem, 6-9 cm, lanceolate, thin in texture. Flower large, up to 5 cm in diam, lilac-lavender. June-July. In the dry season the epigeal parts of the plant wilt and then it is difficult to trace but occasionally one finds the tubers in the humus. D.J. 497 (UPS). Fig. 32. Bulbophyl/um Thou. (Fig. 33) B. barbigerum Lindl. S.L., Lib., Iv.C., Ghana, S.Nig., Cam. Middle parts of large branches. Open shade, bark. Rare. Prostrate 4-10 cm. Pseudobulb 1-3 cm, elliptical in out- line, depressed, obtusely 3-4 angled, pale green. Leaf 3-6 cm, elliptical - oblong, flat, stiff, green. Inflorescence 2-4 times longer than the leaf, descending. Bracts large, spreading. Flower small, dark purple. Lip mobile, densely hairy. Longer hairs with club-shaped swollen ends. Oct. Nov. D.J. 658 (UPS). B. bifarium Hook. f. Lib. (new), lv.c., Cam. Middle or outer parts of branche's. Open shade, minor humus deposits. At altitudes above 1000 m. Rare. Erect, 5-10 cm. Pseudobulbs crowded, cm, ellipsoid or ovoid with sharp angles or protruding ridges, green with purple stripes and spots. Leaf 4-8 cm, strap shaped, light green. Inflorescence equating or longer than the leaves, bracts large, orange-red. Flower small, pale green. Oct. Nov. D.J. 706 (K, UPS). B. bufo (Lindl.) Rchb.f. Guin., S.L., Lib., Iv.C., Ghana, S.Nig., Cam. Basal parts of large branches. Open shade, humus deposits. Rather common. Erect, cm. Pseudobulb 3-5 cm, ovoid or conical ovoid, quadrangular. Leaf 8-15 cm, oblanceolate, green. Inflorescence erect, longer than the leaves. Rachis flattened up to one cm wide. Flower small. Sept.-Oct. This and some other B. spp. (e.g. B. fa lcatum) form a group in which it is difficult to distinguish the species on vegetative characteristics only. D.J. 711 (K, UPS). B. buntingii Rendle Guin., Lib., lv.c., N.Nig., S.Nig., Cam. Middle parts of large branches. Full sun, bark. Rather common. Erect, 5-10 cm. Pseudobulb cm, bluntly triangular, hard, red-brown, with a smooth or slightly reticulate surface. Leaf 4-7 cm, elliptical, obtuse, bluishgreen, purplish beneath. Inflorescence erect, double the length of the leaf, densely flowered almost to the base. Flower small, white. Oct.-Nov. D.J. 688 (K, UPS). B. calamarium Lindl. S.L., Lib., S.Nig. Middle or outer parts of large branches. Open shade,

37 Fig. 33. Simplified drawing of the Bulbophyllum species in the Nimba area. (The species are not in proportion to each other.) 1. Bulbophyllum josephii, 2. B. cocoinum, 3. B. flavidum, 4. B. pavimentatum, 5. B. recurvum, 6. B. nigritianum, 7. B. schimperanum, 8. B. buntingii, 9. B. schinzianum, 10. B. phaeopogon, 11. B. distans, 12. B. calamarium, 13. B. intertextum, 14. B. saltatorium, 15. B. barbigerum, 16. B. inflatum, 17. B. winkleri, 18. B. linderi, 19. B. magnibracteatum, 20. B. imbricatum, 21. B. fa lcatum, 22. B. melanorrachis, 23. B. lucifugum, 24. B. bufo, 25. B. congolanum, 26. B. maximum, 27. B. lupulinum, 28. B. cochleatum, 29. B. oreonastes, 30. B. rhizophorae, 31. B. scariosum, 32. B. bifarium.

38 Ecology of vascular epiphytes in West African rain fo rest 31 minor humus deposits. Rare. Prostrate, cm. Pseudobulb 4-5 cm, conical or ovoid, 3-4 angled, velvety, light green. Leaf cm, flat, stiff, oblong, green. Inflorescence cm, bracts less than 15 mm, overlapping each other. Flower small, lip hairy, sepals strongly reflexed, yellow with purple spots. July-Aug. Difficult to distinguish from B. schinzianum and B. phaeopogon without flowers. The size of the bracts gives a possibility. D.J. 856 (UPS). B. cochleatum Lindl. Guin., S.L., Lib., lv.c., N.Nig., S.Nig., Cam. Basal or middle parts of large branches. Open shade, bark or in minor humus deposits. Common. Erect, cm. Pseudo bulbs scattered, 3-10 cm, narrowly cylindrical, bluntly quadrangular, brownish-green with brown or purple stripes or dots. Leaf 8-14 x cm, strap-shaped, green, sometimes tinged purple. Inflorescence up to 30 cm long, curved. Flowers small, orange-red. Sept.-Oct. D.J (K, UPS). B. cocoinum Batem. ex Lindl. S.L., Lib., Ghana. Basal and middle parts of large branches. Open shade, humus deposits. Rather common. Erect, cm. Pseudobulbs crowded, 2-4 cm high, cm broad, ovoid, sharply 3-4 angled, pale yellow. Leaf lanceolate or oblanceolate, cm, acute, not stiff. Inflorescence long, arching, densely flowered. Flowers small, creamy white. Aug.-Sept. D.J. 541 (K, UPS). B. congolanum Schltr. Guin., S.L., Lib., Iv.C., Ghana, N.Nig., S.Nig. Middle parts of large branches. Full sun, bark or minor humus deposits. Rather common. Erect 8-14 cm. Pseudobulb 2-4 cm, ovoid - conical, 3-4 angled, light green-yellow. Leaf 6-10 cm, strap-shaped, green. Inflorescence erect, somewhat curved, of about the same length as the leaves. Flower, small creamy-white. Oct. Nov. D.J. 714 (K, UPS). Fig. 58. B. distans Lindl. Lib., Jv.C., Ghana, S.Nig., Cam. Middle or basal parts of large branches. Full sun - open shade minor humus deposits. Rather common. Ascending, cm. Pseudobulb depressed, 2-3 cm, conicalovoid, yellow-green. Leaf 8-12 cm, oblong, flat, stiff, green. Inflorescences (often two) erect, slender, cm. Bracts 6-10 mm. Flower small, dark purple, lip densely hairy. June-July. D.J. 855 (K), 857 (UPS). B. fa lcatum (Lindl.) Rchb.f. Guin., S.L., Lib., lv.c., Ghana, S.Nig., Cam., F.Po. Middle part uf large branches. Open shade, minor humus deposits. Common. Erect. Pseudobulb cm long, ovoid, 3-4 angled, green. Leaves 3-12 x cm, oblonglanceolate or oblanceolate. Inflorescence very long, up to 50 cm. Rachis cm broad. Flowers small, yellowpurple. Oct.-Nov. D.J. 668, 670 (K), 671 (UPS). B. jlavidum Lindl. Guin., S.L., Lib., Iv.C., Ghana, S.Nig., Cam. Middle part of large branches. Open shade, minor humus _ deposits. Rare. Erect, 8-16 cm. Pseudobulb 1-2 cm, light green, velvety. Leaf 6-12 cm, oblanceolate-narrowly oblong, acute, green. Inflorescence about the same length as the pseudobulb and the leaf, arching, densely flowered. Flower small, yellow or pink. June-July. D.J. 585 (K), 586 (UPS). B. imbricatum Lindl. S.L., Lib., Jv.C., Ghana, S.Nig., Cam. In the middle parts of large branches. Open shade, minor humus deposits. Rare. Erect, cm, stout. Pseudobulbs 3-4 cm, ovoid, green, scattered along the rhizome. Leaf cm, linear - oblong. Inflorescence longer than the leaves, erect stout. Rachis fleshy, dark purple. Flower small with purple spots. Sept.-Oct. D.J. 710 (K), 678 (UPS). B. injlatum Rolfe S.L., Lib. Trunks or in the basal parts of large branches. Heavy - open shade, minor humus deposits. At altitudes above 1000 m. Rather common. Pendulous, 8-20 cm. Pseudobulb 1-3 cm, ovoid quadrangular, rhomboid in cross section, green. Leaf 7-20 x cm, lanceolate - oblong or elliptical, leathery, green. Flower small, yellow-green. Jan.-Feb. Easy to recognize. The plant grow upside down. This species is very similar to B. comatum Lindl., in a sterile as well as fertile state. The latter has not been recorded in the Nimba Mts but from Mt Momi in the Ivory Coast. In the field work specimens without flowers that could be any of the two species have been recorded as B. injlatum. D.J. 717 (K, UPS). B. intertextum Lindl. S.L., Lib., Ghana, N.Nig., S.Nig., Cam. Middle parts of large branches. Full sun, bark. Common. Erect, 2-5 cm. Rhizome slender, forming mats. Pseudobulbs scattered, up to one cm, elliptical - ovoid, green. Leaf x cm, elliptical, light green. Inflorescence cm, slender. Flower minute, creamywhite. Oct.-Nov. A somewhat different form of this species occurs: Pseudobulb of similar shape and size as above, but with a purplish colour. Leaf strap-shaped, 1-4 x cm, dark greenish-purple. Inflorescence much shorter, 4-8 cm. Flower minute, purplish. Oct.-Nov. D.J. 687, 691 (K, UPS). B. josephii (K unze) Summerh. Guin., S.L., Lib. (new), lv.c., S.Nig., Cam. Basal parts of large branches. Open shade and humus deposits. Rare. Erect, cm high. Pseudobulbs crowded, 2-3 cm, narrowly ovoid-conical ovoid, velvety, redbrown. Inflorescence long, slender, arching. Flower purplish-violet. July-Aug. Other species with redbrown pseudobulbs are B. winklerii, and B. buntingii D.J. 441 (K), 699 (UPS). B. linderi Summerh. S.L., Lib., Jv.C. Basal or middle parts of large branches. Open shade, bark. Common. Erect, cm. Pseudobulb 2-3 cm, ovoid, triangular, with a shiny texture, green. Leaf 8-16 cm, oblong - lanceolate, green, often red coloured along

39 32 Dick Johansson the margin. Inflorescence erect, the apical part' with the white fleshy rachis is held in a horizontal position. Flowers white. Oct.-Nov. D.J. 675 (K, UPS). B. lucifugum Summerh. S.L., Lib. (new). Basal or middle parts of large branches. Open shade, minor humus deposits or on bark. Rare. Erect, cm. Pseudobulb 2-4 cm, conical - ovoid, obtusely quadrangular, surface wavy or verrucate, greenish with purple spots. Leaf strap-shaped, green, x cm. Inflorescence recurved, rachis flattened, green with purple dots, crinkled at the edges. Flower small. Feb. March. D.J. 744 (K), 730 (UPS). B. lupulinum Lindl. Guin., S.L., Lib. (new), Ghana, N.Nig., S.Nig. Middle parts of large branches. Full sun, bark - minor humus deposits. Rare. Erect, cm. Pseudobulb 4-6 cm, rectangular, yellow green. Leaf 8-18 cm, oblong, green. Inflorescence erect. Bracts large, with numerous short black or purplish hairs. Flower small, yellow with red spots. Jan.-Feb. D.J. 451 (K, UPS). B. magnibracteatum Summerh. Lib. (new), Ghana, S.Nig. Middle parts of large branches. Open shade, bark. Rare. Erect. Pseudobulbs cm long, ovoid, 3-angled. Leaves 5-7 x 1.5 cm, stiff. Inflorescence of about the same length as the plant. Rachis cm broad with bracts as broad as the rachis. When old and dry the rachis has a characteristic obovate shape ending in a short acute apex. Flowers small, purplish. April-May. D.J. 489 (UPS). B. maximum (Lindl.) Rchb. f. S.L., Lib., Iv.C., Ghana, S.Nig. Middle part of large branches. Open shade - full sun, bark. Rather common. Erect, cm, stout. Pseudo bulbs 3-7 cm, ellipsoid - conical ovoid, acutely quadrangular, green, scattered along the woody and stout rhizome. Leaf 7-10 cm, oblong - elliptical, stiff, dull green. Inflorescence cm, rachis cm broad, margins markedly undulate. Flowers minute, arranged along a central line of the rachis. Sept.-Oct. D.J. 656 (K, UPS). B. melanorrachis (Rchb. f.) Rchb. f. ex De Wild. Guin., S.L., Lib., Ghana, S.Nig. Middle part of large branches. Open shade and minor humus deposits. Rare. Erect. Pseudobulbs cm long, narrowly ovoid. Leaves 4-10 x cm, oblongoblanceolate, obtuse. Inflorescence 4-6 cm, rachis dark purple. Flowers crowded, small. Oct.-Nov. D.J. 648 (K, UPS). B. nigritianum Rendle S.L., Lib., Iv.C., Ghana, S.Nig. Basal or middle parts of large branches. Open shade, minor humus deposits. Rare. Erect. Pseudobulbs 2-4 cm long, conical ovoid, velvety, dark green. Leaf narrowly strap-shaped, I 0-15 x cm. Inflorescence erect, cm long, flowering almost to the base. Flower small, white. Oct.-Nov. D.J. 693 (K), 669 (UPS). B. oreonastes Rchb. f. Guin., S.L., Lib., Iv.C., Ghana, N.Nig., S.Nig., Cam. Middle part of large branches. Open shade - full sun, bark. The most common epiphytic orchid in the Nimba area. Erect, 6-10 cm. Pseudobulbs spaced out along the rhizome, 1-3 cm, ovoid, quadrangular, yellowish-green. Leaves 2-6 cm, oblong, leathery, green. Inflorescence longer than the bulb and leaves together. Rachis narrowly winged, flowers yellowish with purple lihes, lip purple. March-April. This species is vegetatively similar to B. zenkeranum Kraenzl. The latter species has been recorded from the Kitoma Range, south of the Nimba area. Specimens without flowers that could be any of the two species have been recorded in the field work as B. oreonastes. D.J. 640 (K, UPS). B. pavimentatum Lindl. Lib. (new), S.Nig. Middle parts of large branches. Open shade, bark. Rare. Erect, cm. Pseudobulbs crowded, about 2 cm long, ovoid, obscurely 2-3 angled, velvety green. Leaf 6-14 cm, oblong- elliptical, dark green. Inflorescence equal with or longer than the leaf, thin, peduncle longer than the rachis. Flower small, purplish. Oct.-Nov. D.J. 679 (UPS). B. phaeopogon Schltr. Lib. (new), Iv.C., Ghana, S.Nig., Cam. Outer parts of large branches. Open shade, minor humus deposits. Rare. Erect, cm., Pseudobulbs erect, crowded, 2-3 cm, ovoid, 3-4 angled, light green. Leaf oblong- lanceo1ate,7-14 cm, stiff, green. Inflorescence cm. Bracts more than 15 mm long, overlapping. Flower small, tepals yellow with red spots. Lip with long hairs, mobile. July-Aug. This species is hardly distinguishable from B. schinzianum when in a flowerless state. D.J. 811 (K ), 1061 (UPS). Fig. 54. B. recurvum Lindl. S.L., Lib., Cam., F.Po. Middle parts of large branches. Open shade, minor humus deposits-bark. Rare. Erect. Pseudobulbs cm long, ovoid or conical ovoid, obscurely 4-angled, green to brownish green. Leaves elliptical, 3-6 x 1-2 cm, acute or obtuse. Inflorescence erect, 8-13 cm, longer than the leaves, recurved in the upper flowering half. Flower small, greenish-yellow. Oct.-Nov. D.J. 659 (UPS). B. rhizophorae Lindl. S.L., Lib. (new), Jv.C., Ghana, S.Nig., Cam. On branches of small trees close to water. Open shade - full sun, bark. Rare. Pseudobulb 2-3 cm long, elliptical. Leaves oblong, ± as long as the pseuodobulbs. Inflorescence 6-10 cm, erect. Flower small, yellowishwhite. Oct.-Nov. D.J. 748 (K). B. saltatorium Lindl. -S.L., Lib. (new), Ghana. Basal or middle parts of large branches. Open shade, bark - minor humus deposits. Rare. Prostrate, lying on the substrate, 4-7 cm. Pseudobulbs crowded, 1-2 cm, ovoid, flattened, obtusely 3-4 angled, green. Leaf 3-5 cm, falcate, oblong-elliptical, dark green. Inflorescence shorter than the plant. Flowers small, dark purple, lip hairy, almost all

40 Ecology of vascular epiphytes in West African rain fo rest 33 flowering simultaneous. March-April. D.J. 468 (K, UPS). B. scariosum Summerh. Guin., S.L., Lib. Middle or outer parts of large branches. Full sun, bark - minor humus deposits. At altitudes above 1000 m. Common. Erect, 8-16 cm. Pseudobulb 2-4 cm, ovoid, quadrangular, light green-yellow, turning redbrown when old. Leaf 4-12 cm, oblong, light green. Inflorescence erect, arching in the apical part. Flower creamy white. March April. D.J. 716 (K, UPS). B. schimperanum Kraenzl. Lib. (new), S.Nig., Cam. Middle or outer parts of large branches. Full sun, bark. Rather common. Erect. Pseudobulbs 1-2 cm long, ovoid, triangular, light green-yellow, often tinged with red. Leaf 5-10 x cm, oblanceolate - oblong, obtuse. Inflorescence erect, cm long, carrying flowers almost to the base. Flowers small, white. Sept.-Oct. D.J. 890 (K), 694 (UPS). B. schinzianum Kraenzl. Lib., lv.c., N.Nig. Middle parts of large branches. Open shade - full sun, bark. Rather common. Erect, I 0-25 cm. Pseudobulbs crowded, erect, 2-4 cm, ovoid, sharply quadrangular, light yellow-green. Leaf cm, oblong-elliptical, stiff, green. Inflorescence cm. Flower small, dark purple; lip with short dense hairs. Sept.-Oct. In flowerless state similar to B. phaeopogon. D.J. 435 (K), 64 1 (UPS). Fig. 53. B. winkleri Schltr. Lib., N.Nig., S.Nig., Cam. Upper parts of trunks or basal parts of large branches. Open shade, bark. Rather common. Prostrate, 8-15 cm. Pseudobulbs crowded, cm, ovoid, obtusely quadrangular, surface wrinkled, red-brown. Leaf 5-12 cm long, lanceolate - oblanceolate, acute, flat, dark green. Inflorescence shorter than the leaf. Flower very small. April-May. D.J. 756 (K, UPS). Calyptrochilum Kraenzl. C. christyanum (Rchb. f.) Summerh. Port.G., Guin., S.L., Lib., Iv.C., Mali, Ghana, N.Nig,, S.Nig. Basal parts of large branches. Full sun, bark. Common. Might grow to several meters in length. Stem woody. Leaf 6-12 cm, strap-shaped, bilobed, leathery. Inflorescence 3-4 cm, many flowered, rather lax, rachis ± zigzag. Flower white. Dec.-Jan. D.J. 719 (K, UPS). C. emarginatum (Sw.) Schltr. Guin., S.L., Lib., Iv.C., Ghana, S.Nig., Cam. On trunks of trees in villages. Rare in the primary forest. Full sun, bark. This species can grow to several meters' length. Stem woody. Leaf 8-15 x cm, ovate - strapshaped, bilobed, fleshy, green. Inflorescence short, many flowered, very dense. Flower whitish - pale purple. May June. This plant might be confused with the closely related Calyptrochilum christyanum, which, however, has a zigzag rachis. D.J. 829 (K). Fig. 34. Fig. 34. Calyptrochilum emarginatum. Chamaeangis Schltr. C. vesicata (Lindl.) Schltr. Guin., S.L., Lib., lv.c., Ghana, S.Nig. Middle parts of large branches. Full sun, bark - minor humus deposits. Common. Stem short woody. Leaves x 1-3 cm, linear or narrowly lanceolate, often much curved, fleshy, v-shaped in cross-section, olive green or pale yellow. Inflorescences numerous, longer than the leaves, arching or pendulous, many flowered. Flower small, pale yellow. May-June. D.J. 530 (K), 430 (UPS). Cyrtorchis Schltr. C. arcuata Lindl. subsp. variabilis Summerh. Guin., Lib., Iv.C., Ghana, Dah., N.Nig., S.Nig. Basal or middle parts of large branches. Open shade - full sun, minor humus deposits or bark. Common. Erect, cm. Stem long, woody, thick, covered with old leaf sheaths. Leaf n long, oblong or slight_ly obovate, unequally bilobed at the apex. Inflorescence horizontal, equaling the --length of the leaves. Flowers white, rather scattered on the raceme. Aug.-Sept. F.W.T.A., Vol. 3:1 1968, recognizes three subspecies of C. arcuata. The subspp. variabilis and /eonensis would be impossible to separate in the field. Specimens that could be any of the two subspp. have been recorded as C. arcuata in the fieldwork. D.J. 627 (K, UPS). Acta phytogeogr. suec, 59

41 34 Dick Johansson Fig. 36. Eurychone rothschildiana. Fig. 35. Diaphananthe bidens. C. aschersonii (Kraenzl.) Schltr. S.L., Lib. (new), Ghana, S.Nig., Cam. Middle parts of large branches. Full sun, bark. Rather common. Erect, cm. Stem woody, thick, covered with old leafsheaths. Leaves 6-15 x cm, almost equally bilobed at the apex, very fleshy, rather stiff, strapshaped. Inflorescences much shorter than the leaves. Flowers crowded on the raceme, white. Aug.-Sept. D.J. 613 (K), 576 (UPS). C. monteiroae (Rchb. f.) Schltr. S.L., Lib., Iv.C., Ghana, S.Nig., Cam. Basal or middle parts of large branches. Open shade, minor humus deposits. Rare. Erect or pendulous, cm. Stem long, woody. Leaf 5-20 x 2-4 cm, oblongelliptical or oblanceolate, unequally bilobed, often with wrinkled margin. Inflorescence arching, exceeding the leaves. Flowers scattered, white. Oct.-Nov. D.J. 674 (UPS). Diaphananthe Schltr. D. bidens (Sw.) Schltr. Port.G., Guin., S.L., Lib., Iv.C., Ghana, S.Nig., N.Nig., Cam. On trunks, or in high forest in the middle parts of large branches. Open shade - full sun. Bark or minor humus deposits. Common. Up to several meters length. Stem woody. The plant grows out away from the substratum. Leaf 5-14 cm, oblong-lanceolate to narrowly ovate, apex unequally bilobed, flat, stiff, leathery, dark green. Inflorescence long, pendulous, many flowered. Flower small, salmon-pink, semi-transparent. July-Aug. D.J. 569 (UPS). Fig. 35. D. densiflora (Summerh.) Summerh. Lib. (new), Cam. On branches of small shrubs and trees, more seldom on taller trees. Open shade, bark. Rare. Semi-pendulous. Attached to the substrate by a large number of roots at the base of a 5-40 cm long stem. Aerial roots numerous along the stem. Leaves 5-10 x 1-2 cm, lanceolate - oblong, unequally bilobed. Inflorescences 2-5 cm. Flowers crowded, small, pale green. July-Aug. D.J. 571 (K, UPS). D. pellucida (Lindl.) Schltr. Guin., S.L., Lib., Iv.C., Ghana, S.Nig., Cam. Basal parts of large branches. Open shade, bark or minor humus deposits. Common. Stem short, woody, bearing the leaves in a dense tuft. Leaves arching, cm, oblanceolate, unequally bilobed or almost entire at the apex, fleshy. Inflorescences numerous, pendulous, many flowered. Flower pale yellow-pinkish. July-Aug. D.J. 612 (UPS). Fig D. rutila (Rchb. f.) Summerh. Guin., S.L., Lib., Iv.C., Ghana, N.Nig., S.Nig., Cam. On trunks or branches of small trees or shrubs. Full sun - open shade, bark. Rather common. Growth habit as D. bidens. Stem woody. Leaves 6-15 cm, unequally and obtusely bilobed. Inflorescence long, pendulous, with a large number of small, translucent, pale yellow-purplish flowers. July-Aug. D.J. 560 (K, UPS). Eurychone Schltr. E. rothschildiana (O'Brien) Schltr. Guin., S.L., Lib. (new), Iv.C., Ghana, S.Nig. Trunks or branches of smaller trees or shrubs. Full sun - open shade, bark. Rare. Stem very short, woody. Leaves few, 7-17 cm, broadly oblanceolate, unequally bilobed at the apex, leathery. Inflorescence shorter than the leaves. Flowers large, up to 5 cm in diam., 3-6, white and green. June-July. D.J. 853 (K, UPS). Fig. 36.

42 Ecology of vascular epiphytes in West African rain forest 35 Habenaria Willd. H. leonensis Dur. & Schinz Guin., S.L., Lib., Iv.C. Basal parts of large trees. Full sun - open shade, humus deposits. Rare. In the investigated area epiphytic, but in the grasslands of Guineean Nimba common as terrestrial. Erect, up to 30 cm high. Leaves 6-12 x cm, narrowly lanceolate. Inflorescence with a few flowers. Flower white. July-Aug. In a sterile state hard to separate from other Habenarias. D.J. 580 (K, UPS). H. procera (Sw.) Lindl. S.L., Lib., Iv.C., Ghana, S.Nig., Cam. On trunks of trees, but more often of oil palms. Full sun - open shade, humus deposits. Rare. Erect, up to 60 cm high. Leaves lanceolate, x cm. Inflorescence densely flowered. Flowers white. July-Aug. In a sterile state hard to separate from other Habenarias. D.J. 595 (K, UPS). Fig Liparis caillei. Genyorchis Schltr. G. pumila (Sw.) Schltr. S.L., Lib., Iv.C., Ghana. Middle or outer parts of branches on small trees or shrubs. Full sun, bark. Rare. Erect, 2-3 cm. Pseudobulb cm, ovoid, quadrangular. Leaf 1-2 cm, ligulate - oblong, green. Inflorescence slender, 5-6 cm. Flower minute, Polystachya-like, white-pale green. March-April. This small inconspicuous plant is similar to a Bulbophyllum sp. D.J. 485 (K, UPS). Graphorchis Thou. G. lurida (Sw.) 0. Ktze. Sen., Port.G., Guin., S.L., Lib., Iv.C., Ghana, N.Nig., S.Nig., Cam. Middle parts of large branches. Full sun, bark. Common. Erect, up to 50 cm. Pseudobulbs crowded, 5-10 cm, conical - ovoid, yellow, longitudinally wrinkled, with black transverse stripes. Leaves 4-6, in a dense tuft at the tip of the mature pseudobulb, lanceolate, up to 40 cm, thin, ribbed. Inflorescence from the base of the pseudobulb appearing before the leaves, cm, paniculate. Flower small, yellow and brown. Jan.-Feb. The yellow pseudobulb, surrounded by a dense tuft of white erect aerial roots, makes identification easy even when leaves or inflorescences are missing. DJ. 722 (UPS). Fig. 61. Liparis L. C. Rich. L. caillei Finet Guin., S.L., Lib., N.Nig., Cam. Basal parts of trunks. Open shade, humus deposits. Rare. Pendulous. A minute plant. Total size 3-6 cm, inflorescence excluded. Pseudobulb mm, globose, green. Leaves 2-4 cm, ovate or lanceolate, green. Inflorescence cm long, pendulous, rachis winged, many flowered. Flower pale yellow. June-July. The leaf and pseudobulb disappear among the debris in which the plant occurs. Even when flowering the inflorescence is hard to observe. D.J. 521 (UPS). Fig. 37. L. nervosa (Thun.) Lindl. Syn.: L. guineensis Lindl., and L. rufina (Ridl.) Rchb. f. ex Rolfe. Sen., Port.G., Guin., S.L., Lib., Iv.C., Ghana, Dah., N.Nig., S.Nig., Cam., F.Po. In the forest only as an epiphyte, elsewhere often terrestrial. In the lowest parts of trunks. Open shade - full sun, humus deposits. Rare. Erect, cm. Stem with a ± swollen base. Leaves 5-20 cm, lanceolate, thin, with undulating margins, yellow-green. Inflorescence erect, longer than the leaves. Flowers yellow. July-Aug. D.J. 556 (K, UPS). Listrostachys Rchb. f. L. pertusa (Lindl.) Rchb. f. S.L., Lib., Iv.C., Ghana, S.Nig. Middle parts of large branches. Full sun - open shade, bark. Common. Erect, cm. Leaves arranged in a fan-shaped manner on a short, woody stem, x 1-2 cm, strap shaped, unequally bilobed at apex, leathery, v shaped in cross-section. Inflorescence cm long, often longer than the leaves. Flowers small, white, arranged in two dense rows along the rachis. Aug.-Sept. This plant is of a shape similar to Ai!"rangis laurentii and Rangae'ris muscicola but has much more fleshy leaves. D.J. 700 (K), 443 (UPS). Fig. 38.

43 36 Dick Johansson Fig. 38. Listrostachys pertusa. Nephrangis Summerh. N. filiformis (Kraenzl.) Summerh. Lib. Middle or outer : parts of large branches. Open shade - full sun, bark. Common. Erect when small, pendulous with increasing size, cm. Stem slender, often branched. Leaves 2-8 cm long but only 1-2 mm broad, terete, much curved, acute. Inflorescence very short, few flowered. Flower small, with a white bilobed lip. April May. Two other species have terete leaves: T. tridentata and Angraecum subulatum. The shape of the leaves separates it from Tridactyle tridentata, and the pendulous growth separates it from Angraecum subulatum. D.J. 529 (K, UPS). Fig. 59. P/ectrelminthus Rafin. P. caudatus (Lindl.) Summerh. Guin., S.L., Lib., Iv.C., Ghana, N.Nig., S.Nig., Cam. Middle or outer parts of large branches. Full sun, bark. Rather common. Erect, stout, cm. Stem short, woody. Leaves cm, arranged in a fan-like manner, oblong or elliptical oblong, almost equally bilobed at apex. Inflorescence longer than the leaves, erect, rachis zigzagshaped. Flowers large, white, spur long, spirally twisted. Large capsules. April-May (Oct.-Nov.). D.J. 650 (UPS). Fig. 39. Podangis Schltr. P. dactyloceras (Rchb. f.) Schltr. Guin., S.L., Lib. (new), Ghana, N.Nig., S.Nig., Cam. Middle parts of large branches. Full sun, bark - minor humus deposits. At altitudes above 800 m. Rare. Erect, 7-12 cm. Leaves in a fan-like arrangement on top of a short woody stem, 6-10 cm, lanceolate, fleshy, green. Inflorescence arises below the leaves, and does not exceed the leaves in length. Flowers 5-10, semi-transparent, white. Feb.-March. Can be mistaken for a Bolusiella talbotii or a Rangaeris rhipsalisocia. The first, however, has a long thin inflorescence that exceeds the length of the leaves, the latter has sickle-shaped leaves. D.J. 421 (UPS). Fig. 39. Plectrelminthus caudatus. Polystachya Hook. P. adansoniae Rchb. f. Guin., S.L., Lib., Iv.C., Ghana, N.Nig., S.Nig., Cam. Middle or outer parts of large branches. Full sun, bark - minor humus deposits. Common. Erect, up to 20 cm high. Pseudobulb ellipsoid, 2-4 cm, light green. Leaves strapshaped, 8-16 cm, light green. Flowers small, yellow, arranged in a spike. May-June. D.J. 485, 858 (K), 437 (UPS). P. affinis Lindl. Guin., S.L., Lib., Iv.C., Ghana, S.Nig. More or less restricted to trunks. Open shade - full sun. Rather common. Growing in a vertical position on trunks. Pseudobulbs depressed, crowded, cm in diameter, orbicular or broadly elliptical, green. Leaf cm, oblanceolate, dark green. Leaf and paniculate inflorescence arching. Flower yellow with red markings. Jan-Feb. D.J (K, UPS). P. dalzielii Summerh. Guin., S.L., Lib., Jv.C. Middle or outer parts of large branches. Full sun, minor humus deposits. At altitudes over I 000 m. Common. A small plant. Pseudobulb around I cm high, conical, very hard, green. Leaf 2-6 cm, ovate-lanceolate, thin, purplish-

44 Ecology of vascular epiphytes in West African rain forest 37 Fig. 40. Polystachya elastica. green. Inflorescence up to 15 cm high but usually less, rising from a leafless pseudobulb. Flower white - lilac.feb. March. Inconspicuous in a flowerless state. Wet roots in cross-section purple-coloured. Polystachya pobeguinii, P. elastica and P. saccata have leaves and pseudobulbs of similar shape and sizes. D.J. 420 (K, UPS). P. elastica Lindl. S.L., Lib. Outer parts of large branches. Full sun, bark. Rare. Erect. Pseudobulbs crowded, 1-2 cm 'high. Leaves narrowly lanceolate 2-5 cm long. Inflorescence 5-15 cm, born on a leafless pseudobulb. Flower rose coloured. March-April. In a flowerless state similar to the more common P. pobeguinii. DJ (K), 753 (UPS). Fig. 40. P. galeata (Sw.) Rchb. f. Guin., S.L., Lib., lv.c., S.Nig. Middle and basal parts of large branches. Full sun - open shade, humus deposits. Common. Erect, cm. Pseudobulbs crowded, 5-15 cm, narrowly cylindrical, green. Leaf cm, at the apex of the pseudobulb, elliptical - oblong, fleshy, stiff, persistant for many years. Inflorescence erect, shorter than the leaf and pseudobulb. Flower large compared to most Polystachya species, yellow-green, with red or purplish markings. March-April. DJ. 429 (K, UPS). P. laxiflora Lindl. Guin., S.L., Lib., Jv.C., Ghana, Cam. Basal parts of large branches. Open shade, humus deposits. Common at altitudes above 1000 m, lower down uncommon. A large erect plant, up to 50 cm. Pseudobulb narrowly cylindrical. Leaves 8-20 cm long, oblanceolate. Fig. 41. Polystachya laxiflora. Inflorescence either a spreading panicle with long slender branches or, especially at higher altitudes, branches reduced to short tufts. When flowering, a large drop of clear viscid fluid is often present below each bract. Flower white - yellow. Feb.-March. This species turns black when dried and pressed. D.J. 614, 740 (K), 704 (UPS). Fig. 41. P. leonensis Rchb. f. Guin., S.L., Lib., Iv.C., Cam. On trunks, or in the basal and middle parts of large branches. Open shade, minor humus deposits. At altitudes above 1000 m. Common. Erect, cm. Pseudobulbs crowded, 1 cm, conical, covered with sheets of old leaves. Leaves 8-20 cm, lanceolate or oblanceolate, thin, green, arranged in a fan-like manner. Inflorescence paniculate. Flowers yellow-green, lip white. Feb.-March. D.J. 423 (K), 739 (UPS). P. microbambusa Kraenzl. Guin., S.L., Lib., Iv.C. On trunks. Full sun, minor humus deposits. At m altitudes. Rare. Common on rocks in the grasslands of the Nimba Ridge in Guinea. Erect, 5-15 cm. Pseudobulb cm, cylindrical, arising from upper part of the preceeding one. Leaves 2-4 cm, lanceolate. Flower small, yellow. Jan.-Feb. D.J. 459 a (UPS).

45 38 Dick Johansson Fig. 43. Polystachya saccata. Fig. 42. Polystachya polychaete. P. obanensis Rendle Lib., Iv.C., S.Nig. Basal parts of large branches. Open shade, humus deposits. Rare. Erect, cm. Pseudobulbs compressed, 2-4 cm, elliptical, shiny yellow, arranged in a more or less erect row, giving the impression that they are climbing on top of each other. Leaf 5-15 cm, oblong, green. One single leaf at the apex of the pseudobulb and two at the base. Inflorescence paniculate. Flower small, yellow. Scent strong, citrus-like. Sept.-Oct. D.J. 616 (K), 821 (UPS). P. paniculata (Sw.) Rolfe Guin., S.L., Lib., GHANAf3 S.Nig., Cam. Middle parts of large branches. Full sun - open shade, bark. Common. Erect, cm. Pseudobulbs 5-15 cm high, ellipsoid to long cylindrical, flattened, standing in a dense row, with the flattened sides towards each other, green with minute purple dots. Leaves 8-20 cm, oblong elliptical, bluish green with a waxy layer above, purplishgreen below. Flower small, orange with red markings. Oct.-Nov. D.J. 633 (K), 632 (UPS). P. pobeguinii (Finet) Rolfe Guin., S.L., Lib., Iv.C. Middle parts of large branches. Open shade, humus deposits. Rare. A small plant. Pseudobulbs crowded, cm, conical - ovoid, green and hard. Leaf 4-8 cm, oblonglanceolate, green - purplish green. Inflorescence arising from a leafless pseudo bulb. Flowering scape 7-15 cm long. Flowers rose or lilac, yellow hairs on the lip. Feb. March. Inconspicuous in a flowerless state. The pseudobulb and leaves similar to those of P. saccata and P. elastica. When flowering the rose flowers attracts attention. D.J. 457 (K), 788 (UPS). Fig. 50. P. polychaete Kraenzl. S.L., Lib., Iv.C., Ghana, S.Nig., Cam. Middle or basal parts of large branches. Full sun - open shade, humus deposits. Common. Erect, cm high. Pseudobulbs 1-2 cm in cross-sect., thin, stem like, slightly inflated at the base. Leaf 8-25 cm, lanceolate - elliptic. Flowers small, arranged in a very dense simple raceme, creamy white. Oct.-Nov. D.J. 708 (K), 418 (UPS). Fig. 42. P. puberula Lindl. Port.G., Guinea, S.L., Lib., lv.c. Middle and outer parts of large branches. Full sun, minor humus deposits. Common. Erect, cm high. Pseudobulbs crowded, 3-6 cm, conical, somewhat flattened, greenish-yellow with black transverse lines. Leaf cm, oblanceolate - linear, thin, light green. Flowers small, yellow, in a rather large and loose panicle. May-June. D.J. 511 (K, UPS). P. ramulosa Lindl. S.L., Lib., Ghana, S.Nig. On the lowest parts of trunks. Open shade, humus deposits. Rare. Erect, 5-10 cm. Pseudobulbs slightly swollen at the base. Leaf 4-8 cm, oblong - elliptical, dark green-somewhat purplish, often damaged by insects. Inflorescence much higher than the leaves. Flowers in a loose panicle, white, tinged with pink. June-July. D.J. 552 (K, UPS).

46 Ecology of vascular epiphytes in West African rain forest 39 Fig. 44. Polystachya tessallata and Platycerium stemaria. P. rhodoptera Rchb. f. S.L., Lib., Iv.C., S.Nig. Almost exclusively found on the lowest parts of trunks. Open shade, humus deposits. Rare. Erect, cm high. Leaf 7-12 x 1 cm, narrowly lanceolate. Inflorescence somewhat branched. Flower pale rose. Sept.-Oct. Leaves held in a more or less vertical position. Empty capsules, mm long, persist on the inflorescence for a year. D.J. 447 (K), 462 (UPS). P. saccata (Finet) Rolfe Port.G., Guin., Lib. (new), N.Nig. This is one of the few species that frequently occur on the upper parts of trunks. Full sun - open shade, bark. Rather common. A minute plant. Pseudobulb 0.5 cm, conical, green. Leaf 2-5 cm, oblong - lanceolate, green - purplish green. Inflorescence 3-8 cm, arising from the leafless pseudobulb. Flower white and rose. Feb.-March. Inconspicuous in a flowerless state. Leaves and pseudobulbs similar to those of P. pobeguinii and P. elastica. D.J. 460 (K), 456 (UPS). Fig. 43. P. subulata Finet Guin., S.L., Lib. (new), lv.c., N.Nig. Middle or basal parts of large branches. Open shade, minor humus deposits. Rare. Erect, cm high. Pseudobulb 5-8 cm high but less than 0.5 cm in crosssection, narrowly cylindrical, green. Leaf 6-10 cm, ligulate or oblanceolate, dark purplish-green. Inflorescence simple or seldom somewhat branched. Flower pale yellow-green with purple dots. Capsules large. June-July. D.J. 859 (K, UPS). P. tenuissima Kraenzl. Lib. (new), Iv.C., Ghana. Middle parts of large branches. Full sun - open shade, bark - minor humus deposits. Rare. Erect, cm. Pseudobulbs 2-6 cm, terete, green. Leaves terete, slightly Fig. 45. Rangai/ris brachyceras. falcate. Inflorescence paniculate. Flower minute, pale yellow. July-Aug. D.J. 657 (UPS). P. tessallata Lindl. Guin., S.L., Lib., lv.c., Ghana, N.Nig., S.Nig., Cam. Basal and middle parts of large branches. A tolerant species. Full sun - open shade, bark - large humus deposits. Common. Erect, up to 50 cm. Pseudobulb 1 cm, conical brown-yellow. Leaves cm, oblanceolate or oblong-elliptic, dark green, often somewhat purplish. Inflorescences much longer than the leaves, somewhat branched, branches secund. Flower small, greenish-yellow with purple markings. May-June. D.J. 522 (K, UPS). Fig. 44. Rangae.ris Summerh. R. brachyceras (Summerh.) Summerh. Guin., S.L., Lib. (new), lv.c., S.Nig. Middle or outer parts of large branches. Full sun, minor humus deposits. At altitudes above 1200 m. Rare. Erect, cm. Stem woody, short. Leaves in a fan-like arrangement, 6-16 x 1-2 cm, ligulate or slightly wider in the upper part, v-shaped in cross-section. Inflorescence longer than the leaves, slender. Flower pale, yellowish white. June-July. D.J. 594 (K). Fig. 45. R. muscicola (Rchb. f.) Summerh. Guin., S.L., Lib., lv.c., S.Nig., Cam. Middle parts of large branches. Full sun, bark. Common. Erect, 8-15 cm. Stem short, woody. Leaves x 1-2 cm, v-shaped in cross-section. Inflorescence straight, longer than the leaves. Flower white, star-shaped, with a long spur. Capsules 3-5 cm long and narrow. June-July. This plant might be confused with Aerangis laurentii, which, however, has a zigzag inflorescence. D.J. 540 (K, UPS). Fig. 59. R. rhipsalisocia (Rchb. f.) Summerh. Sen., Guin., S.L., Lib., Iv.C., Ghana, S.Nig., Cam. Middle or outer parts of large branches. Full sun, bark. Rare. Erect, 8-15 cm. Stem short, woody. Leaves arranged in a fan-shaped manner, 5-10 cm, fleshy, flattened, much curved, waxy, bluish green. Inflorescences longer than the leaves, stout. Flower white, rather small. Jan.-Feb. May resemble Podangis dactyloceras or Bolusiella talbotii. D.J. 724 (K, UPS).

47 40 Dick Johansson A F :. < i :...! / /,, 9.. : (j CJ D Fig. 46. Rhipidog/ossum paucifolium. (A) Flowering plant, (B) Flower with lip removed, front view, (C) Dorsal sepal, (D) Lateral sepal, (E) Petal.(F) Lip, (G) Column with anther cap and pollinia removed, side view, (H) Rostellum, front view, (I) Pollinium. (From Johansson 1974.) Rhipidoglossum Schltr. R. paucifolium Dick Johanss. Lib. (New). Basal parts of large trees and on small trees and shrubs. Open shade, bark. Rare. Stem very short, with a very large root system. Leaves few, 4-6 x cm, oblonglanceolate. Inflorescences pendulous. Flowers crowded, semi-transparent, pale green. Aug.-Sept. This species is only known from the Nimba area (Johansson 1974). D.J. 572 (K, UPS). Fig. 46. Stolzia Schltr. S. repens (Rolfe) Summerh. Lib. (new), S.Nig., Cam. Middle or outer parts of large branches. Open shade - full sun, minor humus deposits. Rare. Prostrate. Pseudobulb clubshaped, looking like a swollen part of the rhizome. Leaves elliptical or nearly orbicular, two at each pseudobulb. Never seen flowering in the Nimba area. F.W.T.A. 1968, 3:1 describes the penduncle as stout.. very short, flower small,orange, ochra-coloured or reddish. Its creeping habit makes it hard to detect. It can be mistaken for a Peperomia rotundifolia, since both grow in similar habitats. D.J. 604 (UPS). Fig Tridactyle bicaudata. Tridactyle Schltr. T. anthomaniaca (Rchb. f.) Summerh. S.L., Lib., Iv.C., S.Nig., Cam. Middle or outer parts of large branches. Full sun, bark. Common. Climbing or hanging. A rather large plant, branching in many directions. Stem stout, woody. Leaf 2-8 cm, oblong or elliptical oblong, broadly and obtusely bilobed at the apex, flat, somewhat fleshy but stiff, leathery. Inflorescences less than 0.5 cm, carrying 1-3 flowers. Flower small, yellow-brown. Oct.-Nov. D.J. 676 (K, UPS). T. armeniaca (Lindl.) Schltr. Guin., S.L., Lib., Ghana. Basal parts of large branches. Open shade, bark - minor humus deposits. Common. Erect, often branching and creating dense 'stands'. Stem long, woody in the basal part. Leaf 5-12 x cm, oblong - lanceolate, unequally bilobed at apex, flat, rather thin. Inflorescence mostly below the leaves. Flowers small, yellow or apricot. Feb.-March. T. fu sifera Mansf. and T. tridactylites are vegetatively similar to this species. The first species has not been observed although F.W.T.A :1, gives two records from the Nimba area. The latter species only occurs at altitudes above 1000 m where T. armeniaca is rare. D.J. 452 (K, UPS). T. bicaudata (Lindl.) Schltr. S.L., Lib., Iv.C., Ghana, N.Nig. Middle or basal parts of large branches. Open shade, bark - minor humus deposits. Rather common. Erect cm. Stem long, woody. Leaf x 1-2 cm, narrowly ligulate, unequally bilobed. Inflorescence from the leaf axils or below the leaves. Flower pale yellow-orange. Oct. Nov. Vegetatively similar to T. armeniaca. It is easy to identify by the very strong aromatic, somewhat vanillalike scent that is emitted from the roots, particularly when the plant is pulled off it's substrate. D.J. 684 (UPS). Fig. 47. T. crassifolia Summerh. Lib. (new), Ghana. On the trunk or anywhere on the large branches. Full sun, bark. Rare. Erect, or sometimes hanging, with a stout

48 Ecology of vascular epiphytes in West African rain fo rest 41 woody stem. Leaf 3-8 x cm, unequally bilobed, v shaped in cross-section, the upper surface concave with a narrow groove along the centre, the lower surface convex, very fleshy, stiff. Surface waxy, bluish green. Inflorescences very short. Flowers greenish yellow. March-April. D.J. 695 (K). T. tridactylites (Rolfe) Schltr. Guin., S.L., Lib. (new), Iv.C., N.Nig., S.Nig., Cam., F.Po. Basal or middle parts of large branches. Open shade, minor humus deposits. At altitudes above 1000 m. Common. Erect, often branching, forming large masses of growths. Stem woody. Leaves strap-shaped, distichous, deeply notched. Inflorescences short and few-flowered, in the lower le - afless part of the stem. Flower yellow. Jan. Feb. In vegetative parts similar to T. armeniaca, but has, however, never been observed at altitudes below 1000 m. The possible confusion of the two species is therefore limited to high altitudes. In observations of distribution (> 1000 m), T. tridactylites is considered the only species present. D.J. 726 (UPS). Fig. 86. T. tridentata (Harv.) Schltr. Guin., S.L., Lib. (new), Ghana. Middle or outer parts of large branches. Full sun, bark. Rather common. Pendulous, cm. Leaves 6-10 x cm in cross-section, terete, distichous, with a shallow groove running along their entire length. Inflorescence short, few-flowered. Flower pale yellowish. Aug.-Sept. This species can be confused with Nephrangis filiformis which, however, has leaves that are shorter and markedly falcate. D.J. 591 (K, UPS). Fig. 59. Vanilla Mill. V. crenulata Rolfe Guin., S.L., Lib., Iv.C., Ghana, S.Nig. Climbs the basal parts of the trunks. Open shade, large humus deposits. Rare. Climber. Sizes up to three meters in length have been observed. Stem slender. Leaf 5-10 cm, oblong - elliptical, waxy, yellow-green. Inflorescence a long hanging raceme. Flowers large, white or yellow with purple markings on the lip. July-Aug. Jn a flowerless state this species is difficult to differentiate from Vanilla africana Lindl. D.J. 723 (K, UPS). Fig. 51. Other vascular epiphytes Begonia L. (Begoniaceae) B. mannii Hook. S.L., Lib.. S.Nig., Cam., F.Po. Basal part of large branches. Open shade, humus deposits. Rare. D.J. 551 (K, UPS). B. polygonoides Hook. f. Guin., Lib., Iv.C., S.Nig., Cam. Basal parts of large branches. Heavy - open shade, humus deposits. Rather common. D.J. 545 (K) 735 (UPS). B. rubro-marginata Gilg. Lib. (new), Cam. Basal or middle parts of large branches. Open shade - full sun, humus deposits. Common. D.J. 736 (K), 733 (UPS). Fig. 65. Fig. 48. Left: A strangling fig. (Ficus anomani) established as an epiphyte in the crown_ of a palm. Later it will send roots to the ground and continue as an independent plant. Nimba Range 600 m. Right: A strangling fig when the roots have reached the ground. The original phorophyte is dead and has left a hollow formed by the decayed trunk.

49 42 Dick Johansson Ca/voa Hook. f. (Melastomataceae) C. monticola A. Chev. ex Hutch. & Dalz. Guin, S.L., Lib., Iv.C. The lowest parts of the trunks. Heavy shade, humus deposits. Common. D.J. 785 (K, UPS). C. trochainii Jac.-Fei. Guin., Lib. Basal parts of trunks or middle parts of large branches. Open shade, minor humus deposits. Common. D.J. 573 (UPS). Medinilla Gaud. (Melastomataceae) M. mannii Hook. f. Lib., F.Po. Middle or basal parts of large branches. Open shade, humus deposits. At altitudes above 1000 m, often solitary. At lower altitudes, often associated with Drynaria laurentii. Common. D.J. 725 (UPS). Peperomia Ruizd & Pav. (Piperaceae) P. fernandopoiana C. DC. Guin., Lib., Iv.C., S.Nig., Cam., F.Po. In all sections of the phorophyte in a wide range of habitats. Common. D.J. 475 (UPS). P. molleri C. DC. Lib., Ghana, Togo, S.Nig., Cam., F.Po. Basal parts of trunks. In heavy shade, minor humus deposits. Rare. D.J. 882 (K). P. rotundifolia (L) H.B. & K. S.L., Lib., Iv.C., Ghana, Togo, Cam. Basal or middle parts of large branches. Open shade, humus deposits. Rather common. D.J. 498 (UPS). Fig. 59. Preussiel/a Gilg. (Melastomataceae) P. chevalieri Jac.-Fel. Guin., Lib., Iv.C. Basal parts of large branches. Open shade, humus deposits. Rather common. D.J. 785 (K). P. kamerunensis Gilg. Lib., Cam. Basal parts of large branches. Open shade, humus deposits. At altitudes above 1000 m. Rare. D.J. 824 (K). Table 7. Facultative epiphytes and filmy ferns in the Nimba area. FACULTATIVE EPIPHYTES Pteridophytes Asplenium variable Hook var. variable Bolbitis fluviatilis (Hook.) Ching Bolbitis salicina (Hook.) Ching Lygodium smithianum Presl ex Kuhn Pityrogramma calomelanos (L.) Link Selaginella blepharophylla Alston Selaginella molleri Hieron. Selaginella myosurus (Sw.) Alston Selaginella versicolor Spring Selagim:lla zechii Hieron. Other vascular epiphytes Araceae Cersestis afzelii Schott Culcasia angolensis Welw. ex Schott Culcasia liberica N.E.Br. Raphidophora africana N.E.Br. Begoniaceae Begonia oxyloba Welw. ex Hook. Begonia quadrialata Warb. Melastomataceae Tristemma incompletum Benth. Moraceae Ficus anomani Hutch. (Fig. 48) Ficus kamerunensis Warb. ex Mildbr. & Burret. Ficus leprieurii Miq. Ficus sagittifolia Warb. ex Mildbr. & Burret. Urticaceae Urera oblongifolia Benth. Urera rigida (Benth.) Keay FILMY FERNS Hymenophyllum kuhnii C.Chr. Trichomanes africanum Christ Trichomanes chamaedrys Tanton Trichomanes erosum Willd. Trichomanes guineense Afzel. ex Sw. Trichomanes mannii Hook. Remusatia Schott. (Araceae) R. vivipara (Roxb.) Schott. Guin., S.L., Lib., Iv.C., Cam. Basal parts of large branches or trunks. Open shade, large humus deposits. Rare. D.J (K). Rhipsalis Gaertn. {Cactaceae) R. baccifera (J. Mill.) W.T. Steam S.L., Lib., Iv.C., Ghana, S.Nig., Cam., F.Po. Middle or outer parts of branches. Full sun - open shade, bark or minor humus deposits. Common. D.J. 793 (UPS). Fig. 59.

50 Ill. Biology of vascular epiphytes Reproduction biology Flowering periods of orchids The flowering periods are of particular interest since they may indicate an interbreeding barrier between closely allied species. The general pattern in the flowering of the orchids is presented in two-month-periods for the year 1969 (Fig. 49). Two flowering peaks are easily noticed. In his studies of the Nigerian rain forests Richards (1939) found this bimodal culmination of flowering to be a general rule for the vegetation. A similar pattern in flowering times of West African orchids is reported by Sanford (1971: 166): "Casually, the two blooming peaks seem to follow the long and short dry seasons. Such coincidence has probably lead to the belief that dry seasons trigger flowering in trees (see Ashton 1969)..., however, there is no evidence for orchids that it is either the dry season or the following moisture that actually induces flowering." (Cf. Arditti 1966.) The genera Bulbophyllum and Polystachya, accounting for about half of the number of species, show a marked difference in their blooming peaks (Fig. 49). The Polystachyas have the most frequent blooming late in the dry season or early in the rainy season, while the Bulbophyllums have a very pronounced peak during the end of the rainy season. Most of the Bulbophyllum species flower on mature shoots, e.g. at the end of the rainy season. Bulbophyllum winkleri and B. oreonastes are two exceptions. They flower on new growths early in the growing season. Among the Polystachyas that flower during the dry season there are four species bearing their flowers on leafless pseudobulbs (Curtis 1943), viz. P. dalzielii, P. elastica, P. pobeguinii, and P. saccata. At the end of the rainy season in Nov.-Dec. the No. of species 20 Orchids Rainfa ll Yekepa 510 m 1969,., _ _... "' JA N. FE B. NOV. DEC. 16 Bulbophyllum spp. Polystachya spp. Fig. 49. Flowering periods. Upper figure: Total number of flowering orchids in two-month-periods during a year in relation to the rain fall. Lower figure: Number of flowering species of the genera Bulbophyllum and Polystachya. 10,.,., ,......

51 44 Dick Johansson Fig. 51. V an ill a crenulata. genus Bulbophyllum which flower simultaneously favour the possibilities of hybridization. There are also examples of closely related species with different flowering times e.g. Calyptrochilum emarginatum and C. christyanum. These grow in the same habitat under non-limiting conditions (as in the Nimba area), but there are considerable intervals between their flowering periods. Fig. 50. Polystachya pobeguin i. leaves are shed, and the plant seemingly disappears since the pseudobulbs are very small (less than one centimeter) and the root system is hidden in cracks in the bark or covered by debris, lichens and mosses. Thus when the inflorescence appears one gets the impression that it is growing straight out of the bark (Fig. 50). It is evident that the species of some genera flower during a limited period of the year, while others have a more prolonged flowering time. The six species of the genus Angraecum flower in the middle of the rainy season. In July all of them flower simultaneously. In August the four Diaphananthe species have a similar synchronous blooming time. The genus Tridactyle, on the other hand, includes species that flower during every month of the year. The many closely allied species especially in the Observations of orchid pollination Since in sexual flowering plants pollination is a prerequisite for the seed formation, any limitation in this process will effect the total \ number of seeds. However, among the angiospermous epiphytes of Nimba all species seem to be pollinated with one exception. Vanilla crenulata has never been observed with capsules. Two plants of this species which were observed during three years ' produced a large number of flowers each year (Fig. 5 1) but no signs of pollination were noted. The flowers simply wilted away after the anthesis. No actual observation of the pollinators of any Vanilla species seems to exist, even if various insects and hummingbirds are said to participate in the process (Childers et al. 1959:483). The possibility of the Vanilla species being autogamous has also been considered (Van der Pijl Table 8. Insects caught on orchid flowers cultivated in Yekepa. Orchid Bulbophyllum buntingii Bulbophyllum calamarium Bulbophyllum schinzianum Cyrtorchis aschersonii Diaphananthe pellucida Polystachya pob(!guinii Tridactyle tridentata Insects frequently visiting the flower Syntomis sp. Trigona sp. Polybiodes tabida (Tab.), Polistes marginalis (Tab.) Bradylema sp., Gabonia nudeus (Weise) Euchromia lethe (F.) Trigona sp. Gabonia nudeus (Weise)

52 Ecology of vascular epiphytes in West African rain forest 45 Fig. 52. Euchromia lethe. & Dodson 1969: 125). Whether insufficient pollination is a limiting factor to this species is hard to tell from the few observations available. A list of some insect species caught visiting orchid flowers at Yekepa is given in Table 8. If all of these insects are effective in the pollination process is doubtful, but two of them, Euchromia le the (Fig. 52) and Polybiodes tabida were observed with pollinia attached to them from the orchids visited. Diaspore size and dispersal Judged by the types of diaspores (Table 9) among the epiphytes one may assume that the dispersal is mostly done by wind (cf. Oliver 1930, Curtis 1933). The seeds of the Peperomias and Rhipsalis baccifera, which have fleshy fruits said to be edible (Moreau 1935 :20), are probably dispersed by animals (Fig. 55). Orchid seeds are usually small, reduced, and very numerous. One seed weighs from 0.3 to 14 g (Arditti 1967:3). Ames (1946) estimated the number of seeds to 3, 770,000 in one single capsule of Cynoches chlorochilon. The sizes of the orchid seeds of the species in the Nimba area varies generally between I m. Particularly small seeds were found in Angraecum classensii (15-50 m) and A. podochiloides (20-50 m). Bulbophyllum seeds are Table 9. Diaspores of the epiphytes in the Nimba area. Diaspores No. of species Categories Total % Minute spores Pteridophytes Minute seeds Orchidaceae, Melastomataceae, Begoniaceae Seeds with viscid 0.7 Cactaceae coating Fleshy fruits Araceae, Piperaceae Fig. 53. Capsule, flower and bud of Bulbophyllum schinzianum. Several orchids open their flowers singularly or a few at a time. This may favour the possibility of pollination by insects. between m in size, and among the Polystachya species between m. Particularly large seeds are noticed for Liparis nervosa ( m) a species of the lower parts of the trunks. Fern spores are in general considerably smaller than orchid seeds, e.g. Drynaria laurentii ( 40 m) and Asplenium barteri (40-50 m). Germination and establishment After the diaspore has reached the phorophyte the germination and further development may be inhibited fo r several reasons. The dryness of the substrate can be assumed to be a usual reason - for such a failure. However, there are some reports that other properties of the bark may prevent germination. The influence of the substrate on the epiphyte flora will be discussed more specifically in chapter V. A list of factors that might influence the germination of orchid seeds has been presented by Arditti (1967).

53 46 Dick Johansson Fig. 54. Bulbophyllum phaeopogon. The hairy lip is mobile in a vertical direction and the slightest breeze will initiate a movement. The seeds of the orchids are dependent on certain mycorrhizal fungi for their development (Heagarty 1955, Arditti et al. 1972), although it is possible to grow them asymbiotically in vitro (Knudson 1922, Burgeff 1936, 1959). Thus, the presence of these fungi on the phorophyte is a prerequisite for the establishment of orchids (Withner 19 59:3 1 7). All the fungi belong to the Hymenomycetes. The majority are members of the imperfect genus Rhizoctonia, and as such are probably haploid mycelia of Corticiae (Burgeff 1959:376). Rhizoctonias are present in all green orchids. No specific relation between fungus species and orchid host seems to exist (Curtis 1939). The possibility for orchid seeds to be inoculated with mycorrhizal fungi in the early stages of germination at a temporary resting place, e.g. at the root system of the mother plant, and then blown to a final resting place, has been suggested (Ames 1922). Ames considers the slow germination of the orchid seeds to be of advantage, increasing their possibilities to get in contact with the fungi. "If orchid seeds germinated quickly and gained weight rapidly, if the embryo immediately put forth roots and in a brief time secured a firm Fig. 55. Rhipsalis baccifera with berries, each holding a large number of small seeds. hold on the substratum, the likelihood of dispersal after the entrance of the mycorrhizal fungi would be diminished and opportunities for successful dispersal severely limited." (Ames 1922:232.) The disadvantage for the seed in becoming a little heavier with their fu ngal freight is regarded to be of little importance. More critical is desiccation, but experiments with Goodyera pubescens R. Br. showed that the seeds in their early stages of germination easily could withstand a journey of twenty to thirty miles without lethal desiccation. Life forms The many strange life forms among epiphytes attracted attention early (Goebel 1888, Schimper 1888, Karsten 1895, 1925). A life form system has been created by Hosokawa (I 943, 1949, 1955). Objections towards this system have been raised by Holtum ( 1960). In a dense forest a general pattern can be observed. The epiphytes of the lowest parts of the trees are living under rather constant conditions

54 Ecology of vascular epiphytes in West African rain forest 47 Fig. 56. Asplenium nidus is an exceptionally large epiphyte. The fronds may reach a length of two metres Amani 950 m, Usambara Mts, Tanzania. of humidity. There is little need for adaptations against desiccation (Fig. 56). The filmy ferns, Trichomanes and Hymenophyllum that are common on the lowest parts of trunks, represent the most drought-sensitive epiphytes. Higher up on the trees the epiphytes with somewhat fleshy leaves establish themselves. A reduction of transpiration surface compared to the volume of the plant can also be observed. In more exposed habitats, the size and total number of leaves are reduced (Fig. 57). The common Bulbophyllum species have only one or two leaves with the basal part of the leaf developed into a pseudobulb (Fig. 58). Xeromorphic structures e.g. succulent and terete leaves are common in the most exposed habitats (Fig. 59). The number of stomata and their distribution on the leaves may also be of adaptative importance. A study of several orchids (Table 12) revealed that the stomata in general are located on the lower side of the leaves. The highest number of stomata per sq. Fig. 57. Xeromorphic epiphytes on the outer part of a branch of Lophira alata. Nimba Range 600 m. (A) Bulbophyllum schimperanum, (B) Nephrangis filiformis, (C) Chamaeangis vesicata, (D) Tridactyle anthomaniaca, (E) Bulbophyllum linderi. mm (108) was observed for Plectrelminthus caudatus, which grows in exposed habitats, while the lowest number was found in Habenaria leonensis from a more protected habitat. However, Ae'rangis laurentii, which occurs in the same habitat as Plectrelminthus caudatus, has only about half the number of stomata per sq. mm of the latter. From this scanty material it is hard to draw any conclusion, but the number of stomata may well prove to be of minor importance as an environmental adaptation. Drought tolerant and drought avoidant epiphytes One may divide the epiphytes into two major groups, the drought tolerant and the drought avoidant (cf. J arvis & J arvis 1963). The shape and texture of the leaves often indicate to which group a certain species

55 48 Dick Johansson Fig. 58. Bulbophyllum congolanum. belongs. The leaves of the drought avoidant epiphytes, being deciduous, are not adapted to survive the dry season. Examples of such plants are the ferns Davallia chaerophylloides, Drynaria laurentii, and Nephrolepis undulata. Among the orchids the species belonging to the genera Brachycorythis, Graphorchis, Habenaria, and Liparis are all deciduous, as well as many Polystachyas. Begonia rubro-marginata and Remusatia vivipara also exhibit this adaptation. The drought tolerant epiphytes often have a reduced number of leaves, e.g. Eurychone rothschildiana; succulent leaves, e.g. Microsorium punctatum, Angraecum distichum, Peperomia rotundifolia; or terete leaves, e.g. Angraecum subulatum, Nephrangis filiformis, Tridactyle tridentata. The combination of few and succulent leaves are exemplified by Bolusiella talbotii and Rangaeris rhipsalisocia. Rhipsalis baccifera represents the stem succulents. Sympodial and monopodial growth The two largest orchid genera, Bulbophyllum and Polystachya, have sympodial growth. This means that the plants develop a shoot which is limited in apical growth. Thus the development of pseudo bulbs and leaves takes place during the wet season, each shoot terminating in an inflorescence. The following wet season a new shoot will appear. This growth form is generally considered to be favourable for epiphytes (Holtum 1960) apart from giving them an indefinite length of life. (The Botanical Gardens of Copenhagen have a living plant of Oncidium sphacelatum from Mexico, which has been in cultivation for 127 years, Anonymus:1968.) One should expect that among the orchids with sympodial growth there would be no need of advanced adaptations towards desiccation. It is therefore somewhat surprising to find advanced adaptation against drought among e.g. the Bulbophyllum species. The Polystachyas give examples of leaves that have no adaptations and are deciduous, e.g.. P. puberula, as well as succulent leaves that remain on the pseudobulb during the dry season, e.g. P. tenuissima. Whether or not these succulent leaves remaining on the plant during the dry season are an asset or liability in the survival of the new shoot is hard to tell. They naturally lose water through transpiration, but their photosynthetic activity is difficult to estimate. Thus the adaptations against drought among the sympodials could be considered as much an adjustment to drought periods of varying length during the wet season as an adjustment to the dry season proper. The orchids with monopodia! growth, where each stem has an indefinite apical growth, are subject to a more serious threat to desiccation, since they keep their leaves during the dry season. Holtum ( 1960) states that monopodia! orchids are therefore found mainly in regions which have no long dry season. In the Nimba area there are 60 species of sympodial orchids compared to 41 monopodia} species. Water e:conomy Water uptake Most of the substrates used by epiphytes have a limited storage capacity for water. This means that the epiphytes themselves must be able to effect a rapid water uptake during the limited period when

56 Ecology of vascular epiphytes in West African rain fo rest 49 Fig. 59. Life forms of some epiphytes. (A) 1. Rangae"ris muscicola, 2. Nephrangis filiformis, 3. Tridactyle tridentata, (B) Angraecum podochiloides, (C) A. distichum, (D) Rhipsalis baccifera, (E) Peperomia rotundifo lia, (F) Polystachya a/finis.

57 50 Dick Johansson Fig. 61. Graphorchis lurida, aerial roots in the fore ground. Yekepa 500 m. Fig. 60. Roots of Ae'rangis laurentii. the substrate is wet, or collect the water in small pools between the leaves (tank or cistern epiphytes among many bromeliads of the Americas). Water absorbed in humus may also serve as a water supply (Fig. 113). The osmotic potential of epiphytes seem to be high (Harris 1918, 1934, Blum 1933). Waiter (1971: ) found that orchids with tubers had a value of -2.0 bar. Somewhat lower values (-4.7 to -6.7 bar), were found in orchids without tubers and the lowest values were found among epiphytic ferns (-9. 1 to bar). Non-vascular epiphytes such as mosses and lichens are well. known for their rapid water uptake. Indirectly their moisture holding capacity may be of importance for the vascular epiphytes. The filmy ferns have a water uptake similar to the mosses. The roots of epiphytic orchids exhibit several specialized features in their morphology and anatomy. The aerial roots are surrounded with a white, papery or spongy layer of dead cells called the velamen. Went (1940:9 1) claims that the velamen has an important role in the uptake of water and mineral nutrients: "Es ist nun klar, dass das Velamen sich direkt mit dem ersten mineralreichen Sickerwasser fiillt..." Dycus and Knudson (1957) found that the uptake of water was approximately equal to the rate of water lost by evaporation in the aerial roots of orchids. The absorption was equivalent to that required to saturate the velamen (cf. Wallach 1939). Condensation of water vapor by living roots could not be proved. If condensation did occur, it was so limited in comparison to the evaporation that it could not be detected. The principal roles of the velamen in free aerial roots were considered to be a mechanical protection and the prevention of an excess loss of water from the cortex. Goebel ( 1922) reports that roots of Epidendron nocturnum that had their velamen carefully removed, lost 20 % of their water content in 24 hrs as compared to a 7 % loss by roots with their velamen untouched. However, when an aerial root comes in contact with a solid surface the velamen cells at the point of attachment become markedly modified. Certain salts are absorbed by the modified part of the root and

58 Ecology of vascular epiphytes in West African rain fo rest 51 Fig. 62. Root system of Ansellia africana (D.J. 412 UPS). may enter the cortex. (Dycus & Knudson 1957.) In the Nimba area the velamen is particularly well developed among the species that grow in exposed positions on substrates with insignificant amounts of humus depostis, e.g. Ae rangis laurentii (Fig. 60), Plectrelminthus caudatus, and Rangae ris rhipsalisocia. A conspicuous habit of the aerial roots is exhibited by Ansellia africana and Graphorchis lurida (Fig. 61 ). From the "normal" aerial roots attached to the substrate numerous negatively geotropic roots arise (Fig. 62). These erect roots which are covered with velamen form a dense 'tussock'. No function has been shown for these erect roots, although Sanford (quoted from Sanford & Adanlawo 1973) suggested that they might be advantageous in catching and holding organic debris. Very recently an anatomical study of the erect roots of Ansellia africana (Sanford & Adanlawo 1973 :3 12) showed that the exodermal cells have very little thickening of their walls. The authors consider it very probable that these roots are more permeable than the others and so may have a special absorptive function. The geographical distribution of these two orchids (Fig. 63), (A nsellia africana occurs in deciduous forest or wooded grasslands and Graphorchis lurida in exposed habitats in dry and wet forest types), might also indicate that such roots may participate in the water uptake. The existence of th se roots greatly increases the surface area of the root system towards the air. Water vapour might condensate on the roots during the night and then be transferred to the living tissues of the plants. This could be one explanation to the occurrence of these two species in dry habitats. Incidentally, Ansellia gigantea (Fig. 102), which is closely related to A. africana, occurs in (for epiphytes) extremely dry habitats in East Africa (Piers 1968: 158). Storage of water By comparing the total weight of various organs and their water content the distribution of water in the plant may be obtained. In most cases it is very difficult to remove the total root system, which naturally limits the use and exactness of this method. Another problem is that the variation in water content during the year may be unproportional between various parts of the plants. This method, however, will give an idea of what part of the plant holds the bulk of the water (cf. Gessner 1956). The water con- Fig. 63. Records of Ansellia africana (0), and Graphorchis lurida (e) in West Africa.

59 52 Dick Johansson Fig. 64. Medinilla mannii. Collected from a Drynaria laurentii - Asplenium megalura epiphyte community. Nimba Range 700 m. tent is determined as the difference in weight between the fresh weight and the dry weight (24 hrs in 1 05 C) expressed as percentage of the fresh weight. The figures presented refer to the mean of five separate investigations of the species concerned. In the root system Some epiphytes with a large root system compared to the stem and leaves, e.g. Medinilla mannii (Fig. 64) naturally hold a major part of the water in the roots. Orchids with a proportionally large volume of the water supply in the roots are e.g. Plectrelminthus caudatus and Tridactyle armeniaca (Table 1 0). Table 10. Water content in different parts of some orchids as a percentage of the total water content in the plant. Mean of five samples. Root Stem Leaves Fig. 65. Begonia rubro-marginata exemplifies stem succulence among the epiphytes. Grassfield, december Bulb-like tubers occur on Medinilla mannii and Remusatia vivipara. Small bulbs are frequently found on the roots of Nephrolepis undulata; their function is unknown. In the stem As a rule the stem and rhizomes of most epiphytic orchids are woody and hold only minor amounts of the water supply. Ansellia africana, with its spindleshaped stem is an exception. Begonia rubromarginata (Fig. 65) and Rhipsalis baccifera are good examples of stem succulence. The rhizome of certain ferns is utilized for water storage, e.g. Drynaria laurentii which holds 85.4 % of the total water content in the roots + rhizome (7.4 % and 7.2 % respectively in the fertile and sterile leaves). Calyptrochilum christyanum 29.9 Plectrelminthus caudatus 72.0 Tridactyle armeniaca In the leaves The Bulbophyllum orchids have a part of the leaf developed into a pseudobulb which is built up by

60 Ecology of vascular epiphytes in West African rain fo rest 53 Table 11. Water content in different parts of some Bulbophyllum species as a percentage of the total water content in the plant. Mean of five samples. Root + Leaf Pseudorhizome proper bulb Bulbophyllum cocoinum Bulbophyllum congolanum Bulbophyllum winkleri water holding tissues. The proportions between the water in the anatomical leaf (leaf proper + pseudobulb) and the rest of the plant were roughly 9: 1 for three species examined (Table 11). The fleshy leaves of Calyptrochilum christyanum hold approximately 60 % of the total water content of this spec.ies (Table I 0). The Peperomias have fleshy leaves, particularly Peperomia rotundifolia (Fig. 59). Due to a poorly developed root system and a thin trailing stem the plant appears to consist mainly of the discoid leaves. Expenditure of water The transpiration of epiphytic orchids was found to be low by Kamerling ( 1912). It was for some time thereafter assumed that this was a typical feature for epiphytic plants. Later, Spanner (1939) showed that certain epiphytes, e.g. Myrmecodia, have high transpiration rates, and the opinion was established that the epiphytes, as most other ecological groups, provide examples of great variation in transpiration rates. Short period transpiration tests by Coutinho in a virgin forest in Brazil, quoted from W alter (1971: ), gave very low transpiration rates for orchids and bromeliads. Coutinho ( 1964) also observed the 'De Saussure effect', i.e. the absorption of atmospheric C02 dpring the night and its assimilation in daylight, in epiphytic bromeliads and orchids. Similar observations in fleshy orchid leaves have been reported by Arditti & Dueker ( :866). The 'true' transpiration value is rather difficult to obtain and this requires extensive instrumentation. When the aim is to establish transpiration differences between various species simpler methods can be used. In this study the detached leaf method, or quick weigh technique, was used (Iwanoff 1928, Stocker 1929, Willis & Jefferies 1963, Swanson & Lee 1966, Rutter et al. 1963). This method is based upon the observation that a leaf will temporarily continue its transpiration after it has been detached. This transpiration is noticed as a decrease in weight. Loss in weight of plant material is often regarded as a measure of water loss, since changes in water content involve greater weight changes in the plant Table 12. Transpiration rates and some records of stomata numbers in the detached leaves of some epiphytes. The transpiration rates are given as the loss of weight per hour in percentage of the fresh weight. All figures refer to the mean of five samples. Species Polystachya dalzielii Graphorchis lurida Polystachya puberula Asplenium geppii Polystachya leonensis Begonia rubro-marginata Medinilla mannii Preussiella chevalieri Arthropteris orientalis Ancistrochilus rothschildianus Brachycorythis kalbreyeri Polystachya affinis Drynaria laurentii (fertile leao Nephrolepis undulata Tridactyle tridactylites Elaphoglossum isabelense Phymatodes scolopendria Plectrelminthus caudatus Polystachya rhodoptera Oleandra distenta Angraecum subulatum Microsorium punctatum Aerangis laurentii Angraecum distichum Polystachya laxiflora Habenaria leonensis Rhipsalis baccifera (stem) Listrostachys pertusa Cyrtorchis arcuata Angraecum podochiloides Diaphananthe pellucida Diaphananthe bidens Tridactyle anthomaniaca Bulbophyllum linderi Bulbophyllum winkleri Bulbophyllum saltatorium Bulbophyllum bufo Bolusiella talbotii Chamaeangis vesicata Nephrangis filiformis Calyptrochilum christyanum No. of stomata per sq. mm Transpi- Upper Lower ration epidermis epidermis rates

61 54 Dick Johansson than do changes in the content of any other substances present. The transpiration rate at the time of cutting the leaf may be obtained by extrapolation from the values in weight decrease during the first three minutes. The effects of abscission and placing the leaf in a different environment for the weighing make the accuracy of the result questionable (Iwanoff 1928, Rufelt 1963, Willis et al. 1963). But to the extent that these effects are similar for different species, the method is valuable as an indexing technique (Kochenderfer & Lee 1973: 177). Since the transpiration rate is influenced by the temperature, relative humidity and even time of day ' all results given refer to a vapour pressure deficit (V.P.D.) of mb. The experiments were carried out in daylight in the afternoon ( ). After detachment the scar at the base of the leaf was sealed with nail-varnish. The leaf was then placed on a torsion balance (sensitive to 0. 1 mg) and the decrease in weight during the first three minutes was recorded. The values given refer to extrapolations of these recordings. The water loss may be given as the rate of transpiration compared to the weight of the leaf (Table 12). Three species of orchids (Polystachya dalzie/ii, Graphorchis lurida and Polystachya puberula) showed a loss of more than 10 % of their fresh weight per hour. During the dry season with non-existent rainfall and the substrate drying up, it is impossible to maintain such a rate of transpiration and these three species are all deciduous. Polystachya da/zielii which showed the highest rate of transpiration grow on the highest, cool and mist-swept parts of the range, an environment that helps to keep the transpiration low. It is more dif!tcult to understand how Graphorchis lurida is able to replace the heavy water losses, since it occurs in very exposed habitats, mostly on bark, which naturally can only supply a very limited amount of water. The special root system, previously discussed, may well be the answer to the ability of this species to aintain its water balance. Table 13. Transpiration rates in the detached leaves of some orchids. Given as the loss of weight per hour in percentage of the fresh weight, and in absolute figures (g/dm2/hr). Species Graphorchis lurida Bulbophyllum linderi Bulbophyllum winkleri Calyptrochilum emarginatum Diaphananthe pellucida Cyrtorchis arcuata Transpiration (water loss) %of fresh weight/hr g/dm2/hr The high transpiration rates of Polystachya puberula that occurs on more humid substrates is less surprising. The leaves are very thin and lack visible adaptations towards desiccation. Ferns from humid environments could naturally be expected to have high transpiration rates, as found for Asplenium geppii. Three orchid species showed rates of 5-10 %. Polystachya /eonensis occurs at the same altitudes as P. dalzielii, while the two others, Brachycorythis kalbreyeri and Ancistrochilus rothschildianus, belong to moist, drought-protected habitat. Begonia rubro-marginata, Preussiella cheva/ieri and Medinilla mannii also belong to this group. All these species are deciduous. Transpiration rates below 1.0 % have only been found among the orchids, even if Rhipsa/is baccifera is close (1.0 %). Particularly the orchids with a monopodia} growth, i.e. that keep their leaves during the dry season, exhibit low transpiration values, e.g. Bo/usiella ta/botii, Calyptrochilum christyanum, Chamaeangis vesicata and Nephrangis filiformis. Transpiration can also be given in absolute figures, e.g. as g/dm2/hr (Table 13). This method also results in the lowest transpiration rates for the xeromorphic types of monopodia! orchids, e.g. Cyrtorchis arcuata, Diaphananthe pellucida, and Calyptrochilum emarginatum.

62 IV. The occurrence of epiphytes Epiphytes on forest trees The occurrence of epiphytes in a particular region has been expressed in several ways: 1. Total number of epiphytic species in the region as documented from floras or extensive collections. 2. The quotient between the number of epiphytes and the number of other vascular plants. 3. Percentage of trees of a certain minimum height carrying epiphytes. 4. Highest total number of epiphytic species on one tree. 5. Number of individuals ('stands') of epiphytic species on one tree. Combinations between these methods have often been used. I. Total number of epiphytic species known In the area investigated a total of 101 epiphytic orchid species were recorded. From Nimba Range outside Liberia Schnell (1952: ) recorded 27 species of epiphytic orchids which probably represent less than 25 % of the total number. It is significant that Schnell only observed four Bulbophyllum species (versus 32 in this study). Most members of this genus are concealed in the crowns of the tallest trees and are not likely to be found, except when specifically sought for. One of the few reports of this kind from Africa refers to the Budongo rain forest in Uganda (Eggeling 1947:55-56): "Excluding hemiepiphytic figs nearly one hundred species of vascular epiphytes have been collected from Budongo." This method is reliable only in regions where the flora is very well-known. With rare exceptions it is not useful in the tropics. 2. Quotient epiphytes/other vascular plants The presence of epiphytes may also be expressed as a comparison to the non-epiphytic plants. Hosokawa (1943, 1950) has introduced this method, called the Epiphyte quotient (Ep.Q.), which is simply the quotient between the number of species of 'Epiphyta typica' (Table 1) and the number of species of all vascular plants. A similar quotient called 'l'indice epiphytique' has been used by Schnell (1952:338). In the Nimba Mts outside Liberia the figures from the mountain forest ( foret montagnardes) are given as compared to for the forests at the base of the mountains (forets inferieurs). The results received with this method are dependent on knowledge of the entire flora in a certain area. As stated earlier the epiphytic flora tends to be underestimated, which limits the credibility of this method. 3. Percentage of tall trees carrying epiphytes High fo rest In the Nimba area the percentage of trees in high forest that carried epiphytes was investigated in three sample plots (clear-felling plots according to Richards' terminology, 1939:19). Each plot was 50 m long and 15 m wide. To simplify the recording, trees smaller than ten meters were excluded since they seldom carry epiphytes. The plots were surveyed in advance, involving the limitation, marking and numbering of the trees. Each of the trees 10 m or higher was drawn on a sketch figure at its proper place along the profile (Figs. 66, 67, 68). The crowns have been drawn as if they were compact. This is seldom the case. After the trees had been felled the size of the trunk and the crown were recorded with a measuring tape. In these three plots the felling of the trees was done for other purposes than vegetation studies. This meant that once the felling operation started, it continued with high speed and therefore limited the time available for the examination of the phorophytes. The marking of the trees is very important since in all three cases trees outside the sample strips were also felled. The trees fell in various directions, knocking down parts of branches from one another and often ending up on top of each other on the ground.

63 56 Dick Johansson 50 Fig. 66. Sample plot I. (See text.) Profile diagram representing a 50 m long and 15 m wide strip of the forest. Trees < 1 0 m are excluded _, -'--LIIDI._.!!...L-'---'-'-.I...l-..-''----»LL...L.\-L-..>.L...-l.-'---1.''"----'-'-"-L...Ll.. -'-----'-'-' '-'..L----'WlL...L..._,...J...JJ...:.L..J.l...L so m The figures refer to Table 14. Table 14. Occurence of epiphytes on the trees (10 m or taller) in sample plot 1. The number mark the position of the tree in the profile diagram (Fig. 66). No. Height (m) No. of species Species of tree Pteridophytes Orchids Others Tot ai. Piptadeniastrum africanum Chlorophora regia 2 17 Chlorophora regia 3 17 Lophira alata Heritiera utilis Piptadeniastrum africanum 6 13 Lophira alata Heritiera utilis Mitragyna ciliata Piptadeniastrum africanum Parinari excelsa Parinari excelsa Nauclea diderrichii Calpocalyx aubrevillei Erythrophleum ivorense Piptadeniastrum africanum Lophira alata Calpocalyx aubrevillei Calpocalyx aubrevillei Erythrophleum ivorense Chidlowia sanguinea Parinari excelsa U apaca guineensis Heritiera utilis Chlorophora regia Parinari excelsa Chidlowia sanguinea Calpocalyx aubrevillei Parkia bicolor Total

64 Ecology of vascular epiphytes in West African rain fo rest Fig. 67. Sample plot 11. (See text.) Profile diagram representing a 50 m long and 15 m wide strip of the forest. Trees < 1 0 m are excluded. The figures refer to Table m Table 15. Occurrence of epiphytes on the trees (10 m or taller) in sample plot ll. The number mark the position of the tree in the profile diagram (Fig. 67). Species of tree No. Height (m) No. of species Pteridophytes Orchids Others Total Anthocleista nobilis 12 Pycnanthus angolensis 2 19 Anthocleista nobilis 3 12 Parinari excelsa Parinari excelsa 5 16 Chidlowia sanguinea 6 12 Heritiera utilis Chidlowia sanguinea Heritiera utilis Lophira alata Terminalia ivorensis Fagara tessmannii Klainedoxa gabonensis Terminalia ivorensis Lophira alata Calpocalyx aubrevillei Piptadeniastrum africanum Lophira alata Parinari glabra Heritiera utilis Alstonia boonei Calpocalyx aubrevillei Parkia bicolor Fagara tessmannii 24 Elaeis guineensis Lophira alata Lophira alata Elaeis guineensis Anthocleista nobilis Chlorophora regia Antiaris toxicaria Anthonotha fr agrans Elaeis guineensis Chlorophora regia Chlorophora regia Total

65 58 Dick Johansson Fig. 68. Sample plot Ill. (See text.) Profile diagram representing a 50 m long and 15 m wide strip of the forest. Trees < 10 m are excluded. The figures refer to Table 16. Table 16. Occurrence of epiphytes on the trees (1 0 m or more) in sample plot lll. The number mark the position of the tree in the profile diagram (Fig. 68). Species of tree No. Height (m) No. of species Pteridophytes Orchids Others Total Cryptosepalum tetraphyllum Albizia zygia 2 11 Cryptosepalum tetraphyllum Terminalia ivorensis 4 15 Triplochiton scleroxylon Piptadeniastrum africanum Anthocleista nobilis 7 16 Elaeis guineensis Anthocleista nobilis 9 12 Elaeis guineensis Lophira alata Lophira alata Terminalia ivorensis Pentadesma butyracea 14 Lophira alata Parinari excelsa Calpocalyx aubrevillei z 2 Terminalia ivorensis Piptadeniastrum africanum Lophira alata Cryptosepalum tetraphyllum Coula edulis Heritiera utilis Lophira alata Canarium schweinfurthii Piptadeniastrum africanum Cryptosepalum tetraphyllum Cryptosepalum tetraphyllum Cryptosepalum tetraphyllum Cryptosepalum tetraphyllum Parinari excelsa Parinari excelsa Total

66 Ecology of vascular epiphytes in West African rain fo rest 59 The plots were situated on level ground and on well-drained soils. It is doubtful if any of these forests are so called primary, i.e. untouched by human activities. However, they represent the highest and oldest sections of forest at this level. In any case the dominance of Piptadeniastrum africanum, Lophira alata, Parinari excelsa and Heritiera utilis in the plots corresponds very well with their presence in well-drained forest in the whole area investigated. Almost no terrestrial herbs occurred in any of the plots. The trees and shrubs below 10 m height consisted of straight poles with small, thinly foliated crowns. The first plot (Fig. 66) was located 5.5 km SW of Grassfield at approximately 500 m altitude. This plot is close to the areas surveyed by Ad am (I 969) and Gorgla ( 1969) (see chapter I). The plot examined went through a section of high and dense forest that was surrounded by patches of forest of lesser height. The second plot (Fig. 67) was situated 1 km east of the water purification plant in Yekepa, not far from the river Y ah, at approximately 600 m altitude. This section of the forest was rather rich in oil palms (Elaeis guineensis) and Terminalias. The presence of several trees common to secondary forest, e.g. Pycnanthus angolensis and Fagara tessmannii, might suggest recent human influence. The third plot (Fig. 68) was located 3 km NW of Zulowie in the foothills of Mt Tokadeh at roughly 500 m altitude. This forest was not as dense as the two others. More light penetrated through the canopy and small-sized shrubs and trees were more numerous. On the average every second tree ten m or higher carried epiphytes (Tables 14-17). Secondary fo rest A survey by telescope (distance observation) was undertaken in a secondary forest, east of the Grassfield airstrip in Nimba. A total of twenty-seven trees in sizes from m were studied. The presence of a high number of pteridophytes compared to the number of orchid species was observed. The quotient between pteridophytes and orchids was 3:1 as compared to 1:2 in the high forest (Table 17). There are few remarks in the literature on epiphytes in secondary or degraded forests. Eggeling (1947:56) gives some interesting figures from Uganda. In a colonizing, secondary forest (Maeopsis) 11.7 % of the trees bore epiphytes of 14 species. In Table 17. Occurrence of epiphytes on phorophytes (10 m or taller) in high and secondary forest. (High forest figures from Tables 14, 15 and 16.) Forest No.of Trees with No. of epiphyte species type trees epiph. % Pterid. Orch. Others Total High Total Secondary an older secondary forest ('mixed') 16.3 % of the trees. carried epiphytes of 25 species, while in. a primary or climatic climax 'Iron wood' forest, 22.7 % of the trees were colonized by epiphytes of 35 species. In this steady rise of both the occurrence and the number of species from the colonizing forest to the climatic climax forest, some interesting details can be noticed. Nearly the whole increase in the number of epiphytic species between the 'mixed' and the 'lronwood' forests can be traced back to the increase of the orchid species in the latter. In the mixed forest there were 15 species of orchids constituting 60 % of the epiphytic flora, while in the climax forest there were 24 species (68 %). There were even fewer species of ferns in the Ironwood forest than in the mixed forest, seven compared to eight. Results from the use of this method, either as an indication of the occurrence of epiphytes or as a characterization of the vegetation, are available from several places (Table 18). The method is an approximate one that preferably can be used when the determination of species is difficult, or there is a shortage of time. It may refer to investigations made on felled trees, or in more open and low-growing forest types to trees standing. The accuracy is in the latter case naturally somewhat lower. It must be observed that the minimum of height of the trees that are included in the study is of utmost importance. The smaller the trees included in the study the lower will be the percentage of trees with epiphytes observed. The minimum height must be adapted to the structure of the forest investigated, a fact that makes comparisons between different areas hard to achieve (Grub b et al :59 2 ). 4. Highest number of epipbytic species on one tree The highest number of epiphytes on one tree in the

67 60 Dick Johansson Table 18. Aspects on the presence and abundance of epiphytes as reported from various parts of the world. Country and Min. height of Total no. of % of trees with Max. no. of ep. Total no. of author trees being trees being vase. epiphytes on any one tree ep. in the area considered considered (est.) Nigeria. (Richards, 1939) 15 ft Nigeria. (Richards, 1939) 15 ft Uganda. (Eggeling, 194 7) 15 ft Sarawak. (Richards, 1932) 25 ft Sarawak. (Richards, 1932) 25 ft British Guiana. (Davies & Richards, 1933, 1934) 5m British Guiana. (Davies & Richards, 1933, 1934) 14 m Ecuador, Lowland. (Grubb et al., 1963) 20 ft Ecuador, Mountain (Grubb et al., 1963) 20 ft Liberia, Rain forest. (This publication.) to m Liberia, Rain forest. (This publication) to m Liberia, Rain forest. (This publication) to m Tanzania, Riparian forest. (This publication) 5m Tanzania, Wooded grassland. (This publication) 5m Tanzania. Wooded grassland. (This publication) 4m three (sample) plots was 22 (9 ferns, 8 orchids, 5 other epiphytes) observed on a 43 m high Parinari excelsa, but a higher number of epiphytic species on certain trees has been bserved (Table 19). During a brief visit to the Usambara Mts in Tanzania, I was able to count 25 species of epiphytes on a Parinari excelsa (Table 27). Eggeling (1947:55) reports from the Budongo rain forest in Uganda: "... In these plots the maximum number of species of epiphytes on a single tree is twenty-six but elsewhere in the forest I have collected between forty and forty-five species from an especially suitable host." Richards (1964: 1 13) probably underestimates the richness of epiphytes on certain trees: "The number of species of epiphytes on a single tree is seldom very large even in rich districts. The largest number of species recorded by the Table 19. Highest number of epiphytic species recorded (close ohs.) on single individuals of some phorophytes common in the Nimba area. Phorophyte Height Number of epiphyte species (m) Pterid. Ore h. Others Total Heritiera utilis I 30 Mitragyna ciliata Chlorophora regia I 27 Parinari excelsa Lophira alata Piptadeniastrum africanum

68 Ecology of vascular epiphytes in West African rain fo rest 61 No of epiphytic species C!XD <OOXi> <ixd <D <D <D Size of Phorophyte so m Fig. 69. Correlation between the size of the phorophyte and the occurrence of epiphytes in sample plots (Tables 14-16). Figures in circles indicate the number of trees in each size class that were devoid of epiphytes. Table 20. Number of epiphyte 'stands' (a) and their distribution (b) on a 43 m tall Heritiera utilis. Seka Valley 700 m. The distribution is given as a percentage of the total number of 'stands'. (a) Species Bulbophyllum oreonastes Bulbophyllum linderi Listrostachys pertusa Tridactyle armeniaca Elaphoglossum salicifolium Bulbophyllum saltatorium Elaphoglossum isabelense Tridactyle anthomaniaca Rangaeris muscicola Cyrtorchis arcuata Polystachya polychaete Bulbophyllum schinzianum Polystachya saccata Nephrolepis undulata Asplenium megalura Bulbophyllum barbigerum Begonia rubro-marginata Raphidophora africana Polystachya tessallata Drynaria laurentii Begonia mannii Graphorchis lurida Remusatia vivipara Total (b) Section Distribution of the 'stands' 'Stands' ll Ill IV V author is about fifteen in British Guiana and about 13 in Nigeria." From Brazil 53 species of epiphytes on one tree has been reported (Focke 1893). In the clear-felling plots the number of species of epiphytes on each phorophyte correlated to the height of the p orophyte is shown in Fig. 69. The age, species and environment of the. trees investigated naturally exert a strong influence on the number of species of epiphytes that will be present. Thorold (1952), however, found no appreciable change in epiphyte rating (see enumeration methods) between cocoa trees, 15 respectively 60 years of age, while Richards (1939:30) states "epiphytes occur chiefly on the largest individuals of each species of tree". The usefulness of this method as an instrument for comparison of the epiphyte flora in various regions is limited. Comparison must be performed on the same species and sizes of phorophytes due to the strong correlation between epiphyte flora and the phorophyte. For instance in the first plot a Parinari excelsa (no. 26) carried 62 % of the total number of epiphytic species (that also occurred on other phorophytes) in that plot. Similar results are found in the tẉo other strips. A Lophira alata (no. 18) in the second plot and Parinari excels a (no. 31) in the third carried 40.5 % and 40.9 % respectively of the species in their plots. 5. Number of epiphytic specimens or 'stands' on one tree In the Nimba area it was observed that certain species of trees may harbour a very high number of epiphytic individuals. A total of 1857 individuals ('stands') were counted on a Heritiera utilis (Table 20), and on a Parinari excelsa.with one large branch excluded, individuals ('stands') were recorded. Enumeration of the total number of individuals ('stands') of epiphytic species that occur on a tree is made difficult due to the inaccessibility and the growth habits of many epiphytes. Richards (1964: 1 13) states: "No information is available as to the number of individuals of epiphytes for the tropics, but in New South Wales, Turner quoted by Longman & White (1917:64) counted over 200 individuals of epiphytic orchids on one tree." The number of epiphytes in this sense is not very useful in determining their occurrence in a particular geographical region because of the same reasons as presented in the previous method. Grubb et al.

69 62 Dick Johansson (1963:592) notices this in Ecuador: "Amongst twenty-five trees bearing vascular epiphytes on the lowland plot three trees bore 40 % of the total number." However, records of this nature are valuable when analyzing the correlation between the phorophyte and its epiphytic flora. Epiphytes on other substrates On cultivated trees Trees, many of them of exotic origin, that are kept in cultivation in and around the villages seem to be of varying suitability as phorophytes. The common mango tree, Mangifera indica, has a very poor or non-existent epiphyte flora. Citrus trees (grapefruit, orange and tangerine) seem to carry epiphytes only occasionally, their bark, however, is covered with white crustaceous lichens to such a degree that it often gives a whitish impression. Coffee trees may be observed with a substantial number of epiphytes. Table 21. Epiphytes recorded on Hevea brasiliensis in Firestone plantations at Barbel, Liberia. Pteridophytes Bulbophyllum cochleatum Arthropteris monocarpa Bulbophyllum cocoinum Arthropteris orientalis Bulbophyllum congolanum Asplenium megalura Bulbophyllum falcatum Davallia chaerophylloides Bulbophyllum intertextum Drynaria laurentii Bulbophyllum linderi Elaphoglossum barteri Bulbophyllum nigritianum Elaphoglossum salicifolium Bulbophyllum oreonastes Lomariopsis guineensis Bulbophyllum pavimentatum Loxogramme lanceolata Bulbophyllum recurvum Lycopodium warneckei Calyptrochilum emarginatum Microgramma owariensis Cyrtorchis arcuata Microsorium punctatum Cyrtorchis monteiroae Nephrolepis biserrata Diaphananthe bidens Nephrolepis undulata Graphorchis lurida Oleandra distenta Listrostachys pertusa Phymatodes scolopendria Polystachya tessallata Platycerium stemaria Tridactyle anthomaniaca Vittaria guineensis Tridactyle armeniaca Orchids Other vascular epiphytes Aerangis biloba Begonia polygonoides Ancistrorhynchus cephalotes Peperomia sp. Angraecum distichum Preussiella chevalieri Bulbophyllum bufo Rhipsalis baccifera Fig. 70. Epiphytes on a rubber tree (Hevea brasiliensis). Firestone Rubber Plantation, Harbel, Liberia. (A) Microgramma owariensis, (B) Graphorchis lurida, (C) Bulbophyllum fa lcatum, (D) Drynaria laurentii. The cocoa trees in the Nimba area seem to offer a rather good environment for epiphytes. A total of 13 species of epiphytes have been observed on this phorophyte. Thorold (1952) reported 32 species on cocoa trees in Nigeria. The cola tree that is found outside almost every village shows a striking richness in epiphytes. Not less than 21 species of ferns, 39 species of orchids and 5 species of other vascular epiphytes have been recorded on this small tree. Ornamental trees, e.g. Delonix regia (the flamboyant tree), Jacaranda sp., Terminalia catappa, and Sphatodea campanulata P. Beauv., all seem to offer a poor milieu for epiphytes. This may be a local effect since, in Douala, Cameroon, the flamboyant trees that line the streets are overgrown with epiphytes, Microgramma owaroides and Polystachya odorata Lindl. among others. The rather young rubber trees in the plantations in

70 Ecology of vascular epiphytes in West African rain fo rest 63 Fig. 71. Epiphytes on an oil palm (Elaeis guineensis). Yekepa 600 m. (A) Phymatodes scolopendria, (B) Vittaria guineensis, (C) Asplenium megalura, (D) Lycopodium warneckei, (E) 0/eandra distenta, (F) Nephrolepis undulata, (G) Microsorium punctatum. the Nimba area hold very few epiphytes, but old trees in thefirestone rubber plantation at Harbel are very rich in eiphytes (Table 21) (Fig. 70). A total of 45 species were observed. When the forest is cut for farming the oil palms are spared for their economic value and the_y are generally able to survive the farm-burning. Thus in clearings and secondary bush the palms are conspicuously numerous. As the older fronds die, the persistent woody bases remain adherent to the trunk, covering its length with horny stubs sharply angled upwards, so that large quantities of dead plant material are collected. In these humus deposits many epiphytic pteridophytes are growing (Fig. 71 ). Only one epiphytic orchid, Habenaria procera, was observed on the oil palm. Several species of other vascular plants, both "true" epiphytes and occasional or ephemeral (facultative) ones, utilize this habitat (cf. Van Oye 1921, Vanderyst 1922). Fig. 72. Cyathea manniana. Iti river valley. Nimba Range 800 m. On tree-ferns Two species of tree-ferns are present in the Liberian Nimba, Cyathea camerooniana Hook. and C. manniana Hook. Cyathea camerooniana is found in deep shade, in gullies often near streams, or close to small swamps from 500 m to 1200 m altitude. It has a short stem usually between 1-2 m high. The fronds reach up to four meters in length. No epiphytic vascular plants have been noticed growing on these stems. Cyathea manniana forms veritable 'forests' in suitable places along the streams (Fig. 72). This treefern is rather common, particularly at higher altitudes. It is like a slender oil palm in shape. The stem may reach a length of 10 m with a diameter of only 5-6 cm. The stem is built up by persistent leafbases and matted adventitious roots which form an excellent substrate for the roots of the epiphytic plants. As a matter of fact the stem from tree-ferns is considered by professional orchid growers to be one of the best potting media for epiphytic orchids.

71 64 Dick Johansson Table 22. Epiphytes recorded on 25 Cyathea manniana, (2 m or taller). Nimba Range 700 m. The figures refer to the percentage of the total number of tree ferns that carried each species of epiphyte. Species Arthropteris monocarpa Asplenium dregeanum Asplenium barteri Raphidophora africana lmpatiens sp. Begonia oxyloba Peperomia sp. Asplenium variable var. paucij. Nephrolepis biserrata Nephrolepis undulata Tectaria angelicifolia % of tree ferns carrying each sp. of epiphyte The translucent crowns of these gigantic ferns permit a certain amount of light to penetrate to the ground creating an almost uniform light intensity. On a sunny day the light intensity at ground level is around three times greater in a tree fern forest than in a high forest. Twenty-five tree ferns (C. manniana), 2 m or higher growing in a stream-bed at 700 m alt., were examined as to the presence of epiphytes on their stems (Table 22). No orchids were recorded or ever observed on Cyathea manniana, but the presence of pteridophytes and other vascular epiphytes was striking. 84 % of the tree ferns examined carried at least one species of epiphyte. On 'herbs' No epiphytes have been observed growing on herbs in the Nimba area. Guillaumet (1967:57) reports that the curious looking Afrotrilepis pi/os a (Bock.) J. Raynal., (Cyperaceae), which has stems covered with closely packed persistent old leaf sheets, may support an epiphyte flora. Eleven species of epiphytic orchids are reported to occur on old Trilepis pilosa 'trunks' on the slopes of Carter Peak in Nigeria (RiChards 1957:568). One of these is Polystachya odorata Lindl. var. trilepidis Summerh., which is known only as an epiphyte on Trilepis (Richards 1957:568). The stems of Vellozia splendens Rend., (Velloziaceae), are covered in the same manner as described for Afrotrilepis. Epiphytic orchids very frequently occur on Vellozia splendens in Malawi (Morris 1968, 1970:13) Table 23. The epiphytic flora on eleven dead trees. Yekepa 500 m. Group Species 'Stands'. Total no. % Total no. % Pteridophytes Orchids Other vase. plants Total Both these perennial herbs occur among rocks in areas that for one reason or another are more or less devoid of trees. In this milieu they simply act as a substitute for trees. On dead trees The epiphytic flora of eleven dead trees was studied (close or distance observation) (Table 23). The trees had no humus deposits, and in some cases even the bark had slipped off forcing the epiphytes to grow directly on the wood. Since there was no foliage the plants were subject to full sunlight. The ratio between the species of pteridophytes and orchids was nearly 1:5 (8 :38). The number of individuals shows more clearly the effect of the extreme environmental conditions on the epiphytic fern flora. Only 4.2 % of the total number of individuals ('stands') of the epiphytes were pteridophytes. Some species occur in large numbers. On a 14 m high tree 416 epiphytic individuals were found, with the dominance of two species, Polystachya puberula (181) and P. paniculata (121) (Table 24). Table 24. Number of epiphyte 'stands' on a 14 m tall dead tree. Yekepa 500 m. Species 'Stands' Bolusiella talbotii 7 Bulbophyllum maximum 19 Bulbophyllum oreonastes 17 Chamaeangis vesicata 31 Diaphananthe rutila 4 Plectrelminthus caudatus 16 Polystachya adansoniae 7 Polystachya obanensis 3 Polystachya paniculata 121 Polystachya puberula 181 Polystachya tessallata 5 Rangaeris rhipsalisocia 5 Total 416

72 Ecology of vascular epiphytes in West African rain forest 65 Some species of phorophytes that have a sparse epiphytic flora such as Terminalia ivorensis have frequently been observed to carry a larger number of epiphytes when dead. Similar observations are also reported from Uganda: "Smooth barked species e.g. Cynometra rarely carry epiphytes until they are so old that the branches have begun to die back, when they too may be fairly heavily colonized." (Eggeling 1947:56.) Fig. 73. Epiphytes on a small dead tree. A total of 17 species were recorded (2 pteridophytes and 15 orchids). (A) Drynaria laurentii, (B) Graphorchis lurida, (C) Chamaeangis vesicata, (D) Polystachya tessallata and Phymatodes scolopendria, (E) Polystachya puberula, (F) Rangae'ris rhipsalisocia, (G) Ancistrorhynchus cephalotes. The rich epiphyte flora that frequently can be found on recently dead trees has mostly established itself several years earlier when the tree was alive. During the dying process of trees many epiphytes take advantage of the increased light intensities, (caused by the falling of the leaves) but probably also by a beginning decomposition of the bark (Went 1940:9 1). When the trees are dead the epiphytes will flourish during the first rainy season. The very exposed habitat will rapidly exert a strong influence on the species composition of the epiphyte flora favouring the drought resistant orchids (Fig. 73). In a few years the altered environmental conditions combined with an exhaustion of the substrate will result in an impoverished epiphyte flora, even if certain species will occur in a very large number of individuals. On rocks and soil In the Nimba area several species of epiphytes occur on sloping rock surfaces and bare soil patches at m altitude on Mt Gbahm. This habitat. is created by human activities (road construction) and sooner or later the ground will be colonized by terrestrial plants with Dissotis spp. (Melastomataceae) as pioneers. Presently (1970) a large number of epiphytes are thriving there. The most common are Polystachya dalzielii, P. leonensis, P. laxiflora and Bulbophyllum oreonastes, which can all be seen by the hundreds. Less frequent are Lycopodium warneckei, Angraecum birrimense, A. distichum, Bulbophyllum magnibracteatum, B. scariosum, Graphorchis lurida, Polystachya paniculata, P. pobeguinii, P. rhodoptera, P. saccata, P. tessallata, Rangae'ris muscicola, Tridactyle armeniana, and T. anthomaniaca. It is well known that epiphytic species under special circumstances will grow on rocks or on the ground (Oliver 1930:2, Polack 1933:26, Richards 1936:32, 1964:122, Jaeger & Adam 1972). This behavior is natural in areas devoid of suitable phorophytes and where the microclimate fits the requirements of the epiphytes. It is in relatively dry areas that one will find epiphytes on the ground due to lack of trees and weak competition from other terrestrial plants. In humid areas the opposite effect appears, i.e. habitually terrestrial plants grow as facultative epiphytes. From the Loma Mts in Northern Sierra Leone, J aeger et al. ( 1968) report no fewer than 34 species of epiphytes of which 13 also were found growing on rocks, e.g. Polystachya dalzielii, Bulbophyllum scariosum and B. bifarium. Four species of epiphytes are reported occurring on granite boulders in the southern Ivory Coast (Guillaumet 1967:5 7). From Kenya1Piers (1968 a:158) gives an example of a healthy establishment of an Ansellia gigantea (Rchb. f.) var. nilotica (Baker) Summerh.: "An ex-

73 66 Dick Johansson ceptional specimen plant, a gigant covering some 20 square metres and growing intermingled with Aloes, Euphorbias and other xerophytic terrestrials, grows near the shores of Lake Elmenteita in the Rift V alley in soil which is almost pure volcanic ash." Rangaeris muscicola which in dry areas of East Africa occurs on rocks is often connected to the presence of lichens as judged by notes on herbarium sheets: "On lic ens on the huge granite boulders at the bottom of Njombe river cascade, Tanzania" Lynes (K), "Covering rocks in a mass. Clinging to rock surface with lichens" Zambia, Abercorn Distr. H.M. Richards 8404 (K), "on lichen-covered rocks" Malawi, Mlanje, Morris 91 (K), "Epiphytic or lithophytic orchid, always in association with grey lichens" N. Rhodesia, Ika Hills, Morze 1961 (K). One might speculate that the lichens with their water-absorbing and water-holding capacity could create a suitable microclimate for the germination of orchid seeds. The microclimate could also be of major importance in the possibilities for the young orchid plants to survive dry periods. The epiphytic orchids, with their slow growth and small leaf surface, combined with a root system adapted to superficial growth, appear suitable for this kind of habitat. Distribution of epiphytes on the phorophytes The first impression one gets, when looking at the distribution of epiphytic plants within a tropical rain forest, is the lack of order. It seems that the epiphytes are able to grow at any place on the trees. There are many reasons that help to create this impression. One of these is the limited sector of the trees that can be obser.ved from the ground, another that many observations are done in areas where human activities have disturbed the original stratification, i.e. bright light may penetrate to the lowest level of the forest. In such cases one often finds species normally belonging to the topmost layer of the forest growing close to the ground. Many other influences may contribute towards an impression of randomness in the distribution of the epiphytes. A regular pattern emerges first when one has the possibility of examining a substantial number of trees in an undisturbed environment from the outermost branches in the crown down to the base of the stem. Such a pattern has been observed by several authors. Schimper (1903) states that the epiphytic plants on a tree in a virgin forest are not the same from its base to its topmost branches but exhibit a well-marked differentiation. Moreau (1943 :8): "A few small species e.g. Angraecum viride are found always on twigs rather than branches." Holtum ( 1960) observed that some small epiphytes grow only on the smaller branches of trees or shrubs. Richards (1964:118): "Large epiphytic ferns such as Asplenium nidus and A. africanum tend to prefer the trunks to the branches, but many epiphytes show the opposite preference." Morris (1970:5): "On all trees there is a pronounced stratification of the epiphytic flora." But where an existence of some distribution patterns has been documented no actual investigation has previously been done to describe or analyze them. Ecological subdivision of the phorophyte Previous schemes To make it possible in a short time to record accurately the epiphytes it is necessary to use some kind of subdivision of the tree. Van Oye (1924 b) divides the oil palm (Elaeis guineensis) into five zones. This zonation is useful for the oil palms and other palms whose crowns are built up by large leaves. For the often extensive crowns of the large rain forest trees this zonation is less useful. In Europe Ochsner ( 1928) uses the same zonation as Van Oye, excluding the submedian zone. Richards (1939) in certain cases used the height above the ground, in others a more relative description, e.g. base of the first branch, in the records of the growing site of the epiphyte. Sometimes these two pieces of information are combined. The use of a large number of relative terms, without strict definition, is rather confusing. In 28 felled trees, recorded as bearing epiphytes, Richards used no less than eleven such relative 'localities'. Hosokawa (1954 a) divides the phorophyte into four sections. An arbitrary system of 15 ft (4.5 m) zones from the ground upwards has been used by Grubb et al. (1963 : ). Tixier ( 1966) works with three large sections, but uses 5 subunits within the 'base of the trunk section'. The study of epiphytic lichens and bryophytes in temperate climates has caused many subdivisions of the phorophytes. Barkman (1958:3 1-32) has made a valuable compilation of that terminology. The lower

74 Ecology of vascular epiphytes in West African rain fo rest 67 Fig. 74. Simplified drawing showing the distribution of epiphytes. Above: on a 12 m long branch of a Mitragyna ciliata. Yekepa 500 m. (A) Raphidophora africana, (B) Asplenium geppii, (C) Preussiel/a chevalieri, (D) 0/eandra distenta, (E) Angraecum birrimense, (F) Polystachya tessal/ata, (G) Bulbophyllum cocoinum, (H) Asplenium megalura, (I) Drynaria laurentii, (J) Rhipsalis baccifera, (K) Polystachya paniculata, (L) Tridactyle anthomaniaca, (M) Bulbophyllum oreonastes, (N) Bulbophyllum linderi, (0) Polystachya adansoniae, (P) Bolusiel/a talbotii. Right: on a branch of a 41 m high Lophira alata. Seka V alley 600 m. (A) Elaphoglossum isabelense, (B) Angraecum distichum, (C) Listrostachys pertusa, (D) Cyrtorchis arcuata, (E) Polystachya po/ychaete, (F) Angraecum birrimense, (G) Drynaria laurentii, (H) Rhipsalis baccifera, (I) Tridactyle anthomaniaca, (J) Bulbophyllum schinzianum, (K) Bulbophyllum linderi, (L) Nephrangis filiformis, (M) Bulbophyllum oreonastes. parts of the phorophytes have generally been subject to many subdivisions, while as a rule the whole crown has been regarded as one section. This can in many cases be traced back to poor knowledge of the epiphytes of the crown rather than being based upon real observations. A number of subdivisions used in studies of vascular epiphytes is presented in Table 25. Biotopes on the phorophytes in the Nimba area In the tropical rain forest there is a pronounced stratification of the vegetation. The crowns of the trees form one or more 'strata' and it is in the topmost of these 'strata' that the main part of the epiphytes appear. This stratification of the rain forest is by no means uniform, but rather large variations can be found (Foggie 1947, Newman 1954, Robbins 1959, Holdridge 1970). As a rule the crowns are rather small compared to the length and size of the trunks, but a few species of trees with the ramification close to the ground give rise to crowns of large dimensions. Usually the emergent (superstory; Odum 1970 a) trees have more flattened and expanding crowns than the trees in the lower 'strata' of the forest. The richness in biotopes which can be found in the crowns of the large trees is in sharp contrast to the more uniform environment in the lower 'strata' of the

75 68 Dick Johansson Fig. 75. Plank buttresses of Piptadeniastrum africanum (above) and stiltroots of Uapaca guineensis (below). Yekepa. Table 25. Subdivision of the phorophyte by some authors Author 'Trunk' 'Crown' Van Oye 1924 region basale, r. sous- region eomediane, r. mediane, r. ronaire sous-coronaire Ochsner 1928 basis-teil, mittelteil, kronenteil subkronenteil. Schnell 1950 strate epiphytique strate epiinferieure phytique superieure Hosokawa 1954a Trunk-bases, trunks Crown-bases, crowns Tixier 1966 Base de troncs, strate Cime fructescente forest. This fact is reflected in the zonation used in this study. Subdivision used in this study A subdivision must conform to the varying size and shape of the trees to make comparisons between various phorophytes meaningful. Any simple system of height zones will inevitably fail to correspond with natural 'zones' of environmental conditions, because of the uneven nature of the canopy as pointed out by Richards (1964: 116) and Grubb et al. (1963:592). Hosokawa (1954 a) noticed two zones on the branches, crown-bases and crowns. One also finds these two zones on the phorophytes in the Nimba area. However, there is very frequently in the middle

76 Ecology of vascular epiphytes in West African rain fo rest 69 Fig. 76. Subdivision of the phorophyte. Section: I The basal parts of the trunk (0-3 m) 11 The trunk from three m up to the first ramification Ill The basal part of the large branches (1/3 of the total length of the branch) IV The middle part of the large branches ( 1/3 of the total length of the branch) V The outer part of the large branches ( 1/3 of the total length of the branch) part of a branch an epiphytic flora of a different composition than the one occurring at the base of the branch, or in the outermost parts (Fig. 74). This irregular distribution of the epiphytes can be found on trees of varying sizes. The branches have therefore been divided into three sections of equal size. The trunk has been divided into a short section close to the ground, and a considerably longer section that includes the rest of the trunk up to the first ramification. This division is based upon the easily observed difference between the epiphytic flora at the base of the tree and the one occurring on the upper part of the trunk (Fig. 7 5). The division of the phorophytes into sections used in this study are summarized in Fig Recording and registration of epiphytes The very limited knowledge of the ecology of the epiphytic plants in the rain forest is, as previously mentioned, connected with the difficulties in studying them in the field (Fig. 77). As a matter of fact a large part of the epiphytes described from the rain forest are species naturally occurring on the lowest part of the trunks. Under ordinary circumstances it is from the ground level difficult to even get a limited view of the crowns of the highest trees. The shorter trees, together with lianas and other climbers, form a layer of varying thickness that can be looked through only here and there. This means that even if it is possible to study a certain part of the crown, the overall picture is not discernible. The possibility of a definite host specificity also greatly complicates any attempt of random sampling, as has been pointed out by Curtis (1952:551). One may of course study the epiphytes that occur on the trees along roads, at the edge of the high forest etc. In these cases one will find an epiphytic flora that is by no means representative for the high forest proper. To be able to compare the epiphytes from the high forest, observations have also been performed on phorophytes in other environments (e.g. around villages and in plantations). To enable the use of all possible information three different observation methods have been applied in the recording of the epiphytic flora. They may simply be called the close observation, distance observation and occasional observation methods. One separate record was produced for each phorophyte that was examined. Close observation This method means that the investigation has been performed on a tree lying on the ground. The access to felled trees was limited, but occasionally road construction, landscaping or forestry operations produced useful material. Trees knocked down by natural causes are very seldom found. The investigation of a felled tree must be carried out almost instantly, since many plants will either die or be favoured by the change in the environment. Commonly the orchids suffer from too low light intensities, while certain species of pteridophytes have an advantage with the higher relative humidity close to the ground. The practice of shifting cultivation

77 70 Dick Johansson Fig. 77. The concealment of the epiphytes by the foliage as illustrated by a Triplochiton scleroxylon. This tree is deciduous for a short period when the epiphytes are easily observed. Note the distribution of the large Platycerium ferns. might seem to offer an immense material. Unfortunately these farming activities are to the largest extent carried out in so-called secondary forests. Here the vegetation is after repeated destruction kept in various young secondary growth stages. When the tree is lying on the ground it is relatively simple, at least when one knows well enough the vegetative parts of the epiphytes to make determinations, to map the distribution and to study the ecology of the various species. Certain large branches can be used to illustrate the continuous changes in the epiphytic flora from the base to the outermost parts, so-called 'transects'. In the description of vegetative change along an environmental gradient the 'transects' are of a considerable importance. But since neither the trunks nor the branches represent straight lines a transect of traditional type is not easy to work with. Therefore a modified type of transect has been used. The method is simply to let a measuring tape follow the twistings and bends of the stretch to be examined. This stretch is later presented as if it was a straight line. Most of the monopodia] orchids grow out from the branches, and thus a very minute part of the plant, aside from the extensive root system, covers the sampling area. The scale constructed is therefore based on the actual number of plants rather than the area covered. The transects can preferably be drawn along the branches in the crown, since it is here that the most substantial changes occur in substrate, light and microclimate. From the point of ramification, where the branch is relatively broad, the transect as it runs aiong the branch, covers a smaller and smaller area. This fact should be considered when reading the transect results (Fig. 79). Distance observation Such investigations have been performed on a standing phorophyte on which it has been possible to investigate the trunk and at least one complete branch (or more seldom the whole phorophyte). This method, described by Went ( 1940), allows the recording of the epiphytic flora from the ground. With the aid of field glasses, or rather a telescope on a tripod,

78 Ecology of vascular epiphytes in West African rain forest 71 it is possible to identify the majority of epiphytes. An advanced knowledge of the vegetative parts of the plants is a prerequisite since you seldom find the plants in a flowering state. To acquire that knowledge a sample of almost every epiphyte was collected and kept alive. They thrived growing on substrate similar to the one they were collected from, (in small wooden boxes, 20 x 20 x 5 cm, with broad slots in the bottom). The boxes were kept on shelves in a specially constructed 'frame house'. Species difficult to classify were also kept in this manner until a safe determination could be made. From this collection of living epiphytes information was extracted which proved useful in the field work. Through a telescope at a magnification of 40x even small details can be observed, and epiphytes a few centimeters in size can be identified on the branches of the highest trees. As a rule characteristics, such as remaining floral parts pseudobulbs etc., are of great help in the determination process. (A description of the vegetative parts of the orchids has been presented in chapter 11.) However, for certain orchids, there are sometimes only small details in the flowers that separate two species from one another. In these cases the generic name only has been used in telescopic surveys. The pteridophytes were, for the most part, easier to separate from each other than the orchids. There are very few morphologically similar species that could cause problems in the identification. Among the other vascular epiphytes the Peperomia species are difficult to determine. There are certain disadvantages with this method. It is very time consuming. The plants growing in the most exposed places will easier be discovered than those in more obscure habitats. Large growing species will be spotted more often than minute plants. Many more objections can be raised. It is therefore important to separate the observations with the distance method from those performed in other ways. The distance recording served two purposes. Certain species of epiphytes were never observed in the studies of felled trees. The distribution on the phorophytes and habitat conditions for these species must therefore be based upon information from this type of investigation. Furthermore, the records obtained from the distance recordings, can be used to determine the accuracy of this method in comparison to the close investigation method. Occasional observation It is normally possible to study the epiphytic flora only on a limited part of the phorophyte. Such records that may refer to close as well as distance observations, are called occasional observations. From the lm.yest parts of the phorophytes a large number of observations may easily be obtained and parts of branches that have fallen down from the crowns also offer abundant material. For most species these records add little or nothing to the knowledge achieved from close and distance observations, but for certain species this is ± the only information about their distribution and general ecology that has been possible to obtain. The records from this latter group of species are listed under Occasional observations (Table 29). Registration The traditional way of determining the abundance or presence is not particularly useful for epiphyte rating. In most cases, the limited presence, and the stout and rather large size of many epiphytes, make it possible to count the individual plants, or groups of plants. The sympodial plants with their vegetative multiplication present a special problem. These plants often form dense 'mats' of rhizomes and stems mixed with immature plants. This makes it very difficult to determine the number of individual plants that are present. An arbitrary system of epiphyte rating, primarily qualitative and only quantitative in so far as importance is attached to the presence of one or more colonies has been used by Thorold (1952). Grubb et al. (1963 :591) works with the term 'an individual' for each clearly separated clump of plants. Sanford (1968b:56) has given an accurate description of the problems concerning the enumeration of epiphytic orchids: "Actual counting of orchid plants on a tree presents special difficulty. Many plants such as Bulbophyllum spp. forms mats of pseudobulbs connected by relatively long rhizomes. It is impossible to determine where one plant ends and another begins. Other species, such as those of the genus Calyptrochilum, form great masses of pendulous stems, and again determination of individuals is arbitrary. For this reason a special usage of 'stand' is used in these enumerations. A stand is taken to mean a collection of individual stems or/and plants spatially separated from another group of the same

79 72 Dick Johansson species either by an area on the tree devoid of orchids or occupied by another species. In the case where the same area is occupied by an intermingling of more than one species, one stand is counted for each species present." During the investigation the same unit (called 'group'), as described by Sanford, was used. In order not to cause confusion by adding one more name for the same thing, the term 'stand' sensu Sanford is adopted. Ecological observations In order to get a rough idea of the importance of certain environmental influences on the distribution of the epiphytes within the forest, attention has been paid to light and substrate. For each epiphyte that was recorded, the light intensity and type of substrate at its growing site were recorded in a threegraded scale. Light Light intensity was divided into three classes: heavy shade, open shade and full sun. The amount of light available varies of course with the time of the day and cloudiness of the sky, and also somewhat with the time of the year. Since the light intensity was only estimated, mistakes cannot be excluded. However, the main bulk of the observations are easy to group. Light intensities regarded as heavy shade normally appear in the lower strata of the rain forest. In exceptional cases this intensity can be found higher up in the trees due to dense foliage. In most cases there is no problem to separate heavy shade from open Table i6 _ The trees (10 m or taller) of the high forest included in the study. Trees with epiphytes are marked Close observation =D =i so..= ta=-on=ce"----"' ob"--' s'--" e"--- rv:..:: a:-=:lic::. on:..:. _ No. %with No. %with Phorophytes epiphytes Sizes epiphytes Sizes Albizia glaberrima A. zygia A Is tonia boonei Amphimas pterocarpoides Anthocleista nobi lis Anthonotha fragans Antiaris toxicaria Berlinia confusa Bombax buonop07.ense Bussea occidentalis Calpocalyx aubrevillei 13 Canarium schweinfurthii Ceiba pentandra Chidlowia sanguinea 14 Chlorophora regia Chrysophyllum perpulchrum Combretodendron macrocarpum Cou\a edulls Cryptosepalum tetraphyllum Daniellia ogea Distemonanthus benthamianus Entandrophragma utile Erythrophleum ivorense Fagara tessmannii Guarea cedrata Heritiera uti lis Khaya anthotheca Lophira alata Lovoa trichilioides Mammea africana Mitragyna ciliata Nauc\ea diderrichi i Parinari aubrevillei P. excelsa P. glabra Parkia bicolor Pentaclethra macrophylla Pentadesma butyracea Piptadeniastrum africanum Pycnanthus angolensis Rhodognaphalon brevicuspe Sacoglottis gabonensis Terminalia ivorensis T. superba Triplochiton scleroxylon Uapaca guineensis Vitex micrantha Total loo :;o. o 36,38, 38;40' 17;21 ;26; 12, 14, 17 ;21;25, 27 ;29;3o 11, 14, 14;34. 11, 14, 14, 15, 16;17 ; ;35' ,33;41 24, 30;41 21;22,26' 11.11,12, 12;14, 16, 1s;2o;23, 23, 25;26; ,14,21,29;38' 5 19; ,12, 12' 12; 13, 13,14,14 ;14; 15;15;16, 12 18, , 18, 28;39;42' 23;26;31, 31' 14,14;27;31 ' 16,26;30' 10, 21, 23; 24 ;zs;27 14, 16,19, 20, 26;34;37. 26; ;38;60' 15, 28;32;36. 29,31 ;32, 36, 38; 42 21,32;36' 13,16; 18; 26;32;35; ;36' 11,16, 39;39; 42; 43; 44. 1U,24,27 ;33;38' 14;16, ; 2;32;33 28;32;38. 21;23. 12,21 ;22;3s;42 19;20, 23;23. 21' 23, 26, 29, 29;30, , 22;27 ;34. 31;40 ' 12, 18, 34; 43; 49, , 20, 21, 23;24, ;27,32;35' 14,39' 14, 21, 31, 32, 3. 40, 40; 42, , 32, 33, 35; 41, 42, , 15, 22, 30;32; 41; ;zo;21 13, ]8 ld ,13, 18;21 ;24 ' , 15, 18, 19, 22;31' 50, 0 12, 16, 29; , 10, 11, 11, 12,12,13,13' 15, 15, 16; 19' , 15;16;2o;21;25; , 24;28, 29;30; , 17' , 18' , 23;26;34' , 25, 26; 29;30;34;36;37: 40; 40; 40; o 12, 12;13; 14, 16; 17,17; 1s;zo; 20; 21 ; , 23;25; 27 ;29, 29;30;39' ' , 12;14, 17;19;19;34' 75, 0 23 ; 25, 30; , 26;28, 28;2n; , 23;26; G loo HO , 40; ;14, 18;41 ' 14, 21,21,34,40,42 19;25' 17 ;22, 24;27 ;29;3o;3o;31 ;31 ;31 ;33;34;34;37 14;16, 19 12, 13,24;38' 3 6' 13, 20;27. 12; 14;26; zs;3o 24 12, 14, 14; 1s;zo, 21 ;zs;z5;23;33;34;35;35;36; 39;39;40;44. 11' 23, 25, 26, ;31;32, ;36' 1H;23 13,16, 20, 20;21;24, 26, 26;28, 28;32;34;35;38, 42; ; , 1. 24, 26, 30, ' 29;33;34; 40. 1n, 1H, 23, 30, 33, 40, 41, 41, 41 ' 17, 28,42;43,44 lo,ll,l!i, zo;3!j; 42; 45 12, 12;1H;z5;27 10;12;17;23 ' Acta phytogeogr. sue c. 59

80 Ecology of vascular epiphytes in West African rain fo rest 7 3 shade intensities. The light in a tropical rain forest is not gradually increasing from the ground level up to the crowns of the emergent trees. It is rather discontinuous, as many author have pointed out, e.g. Richards (1939:30). In the crowns of the trees of the topmost stratum high light intensities are formed by open shade. The limit between full sun and open shade is also easy to observe, since only plants in very exposed posttlons receive light intensities regarded as full sun. In a study of the epiphytic societies in Java, Went ( 1940) used a relative scale to judge the light intensity at the growing sites of the epiphytes. He estimated the light intensity at the growing site in per cent of the light outside the forest. Substrate The substrate was divided into three classes: bark, e.g. bark without humus attached, minor humus deposits, e.g. bark with thin and scattered humus layer, and large humus deposits. Humus is here regarded as dead organic material in various stages Table 27a. Total number of records, according to.the close observation method, of pteridophytes and other vascular epiphytes in the high forest. No of Section of the Heavy Open Full observ. pho rophy tes shade shade sun II Ill IV V A B c A B c A B c Pteridophytes Antrophyum immersum A. mannianum Arthropteris monocarpa A. orientalis A. palisoti Asplenium aethiopicum A. africanum A. barteri A. dregeanum A. geppii !! !!. 2 A. hemitomum A. megalura B !J 23,1! 37. A. variable va r. paucijugum Daval\ia chaerophylloides Drynaria laurentii S, 6 Elaphoglossum barteri E. chevalieri , E. isabelense S. l 21.2 E. kuhnii E. salicifolium Lomariopsis guincensis , Loxogramme lanceolata Lycopodium mildbraedii L. warneckei Microgramma owa riensis Microsorium punctatum Nephrolepis biserrata G N. undulata 0\eandra distenta !) 1.1 Phymatodcs sco lopcndria , Platycerium P. stemaria angolense Pyrrosia mechowii Tectaria angelicifolia T. fernandensis Vitkuia guineensis , Xiphopteris oosora X. serru lata X. villosissima loo. 0 Total no. of observations 3000 Other vase. epiphytes 11 Ill IV V A B c A B c A B c Begonia mannii B. polygonoides B. rubro-marginata Calvoa monticola C. trochainii Medinilla mannii , Peperomia fernandopoiana , ,3 16, P. molleri P. rotundifolia Preussiella cheva\ieri P. kamerunensis Remusatia vivipara Rhipsalis baccifera loo , Total no. of observations 503 The distribution of the records between (1) the di fferent sections of the phorophytes and ( 2) the different light and substrate classes each refer to a percentage of the total number of records. A = Bark, B; Minor humus depos its, C ; Large humus deposits. _

81 Table 27 b. Total number of records, according to the close observation method, of orchius in the high forest. (Explanation in Table 27 a.) No. of Section o f llie Heavy Open Full observ. ph orophytes shade shade II Ill IV V A B c A B A n Orchids Al!rangis bi loba 27 A. laurentii 23 Ancistrochilus rothschildianus 53 Ancis trorhynchus capitatus 22 A. cepha lotes A. clandestinus A. recurvus Angraecopsis elliplica Angraecum bi rrimcnse A. chevalieri A. classensii A. disti chum A. podochi loides A. subulatum Ansellia africana Bo\usiella talbolii Brachycorylis kalbre_veri Bulbophyllum barbigerum B. bifarium n. bufo B. buntingii B. calamarium B. cochleatum B. cocoinum B. congolanum B. distans B. fa lcatum B. flavidum B. imbricalum B. inflatum B. inlerlexlum B. josephii B. lindert B. lucifugum B. lupulinum B. magnibracteatum B. maximum B. melanorrachis B. nigritianum B. oreonastes B. pavimentatum B. phaeopogon B. recurvum B. rhizophorac B. sallatorium 28 B. scariosum 199 B. schimperanum 45 B. schinzianum 86 B. w hleri H Calyptrochilum chris lyanum 33 C. cmarginatum Chamaeangi s vesicata Cyrtorchis arcuala C. aschcrsonii C. monleiroac Diaphananthc bidcns D. densiflora D. pellucida D. rutila Eurychone rothschi ldiana Genyorchis pumila Graphorchis lu rida Habenaria leonensis H. proce ra Liparis caillei L. nervosa Listrostachys pertusa Nephrangis filiformis Pleclrelminthus caudatus Podangis dactyloceras Polystachya adansoniae P. affinis P. dalzielii P. elastica P. galeata P. laxiflora P. leonensis P. microbambusa P. obanensis P. paniculata P. pobeguinii P. polychaete P. puberula P. ramulosa P. rhodopte ra P. saccata Polystachya subulala P. tenuissima P. tessallata Rangal!ris brachycerns R. muscicola !J I 42. n G ! ti. : ??? !1 loo H G G 44.D !) H. 9??, o ! o ,; G G.!l tl 15.tl H ; !)]. ti !J !J,!j 1 o !1. 4 :1. o o ! loo !l !1.4 2.! !) 4::! G!J. <I -3 D !l : ;; K G.7 l.j !1 1.0 loo. 0 1 :::1.2 l"'i. 11;. 4:),4 42.H ! J.n :J.o : !l , ;,o.o so. o I!I. U I o lli. 0 li o )?? lti !> ) H , !) G !i ! : :50,0 50. fi ! >. 8 H.!J loll R. rhipsa lisocia Rhipidoglossum paucifolium Stolzia repcns Tridac tyle anthomaniaca T. armeniaca !'iO.O O.!i li.6 1.!J T. bicaudata T. crassifolia T. tridacty\ites T. tridentata ti ?G G li 7. 5!JO. 1.!) Vanilla c renulata Total no. of observations 6940

82 Ecology of vascular epiphytes in West African rain forest 75 of decay. This subdivision of substrates was easy to work with during the recording. Each epiphyte or group of epiphytes has thus been recorded in one of the nine possible light-substrate classes. The idea was to provide a base for a quantitative judgment of each species' dependence of light and substrate. However, it should be emphasized that many other influences effect the presence and distribution of epiphytes. General distribution pattern The distribution pattern was recorded on 463 individual trees C> 10 m in height) of the high forest, representing 47 species of 21 genera. 222 trees were investigated according to the close observation method and 24 1 by distance observation (Table 26). The quantitative figures from this investigation for each species of epiphyte is presented in Tables 27, 28 and 29. It became evident that most species of epiphytes are ± restricted to one or two particular section(s) of the phorophyte, while a few occur more evenly in a number of sections (Fig. 78). An analysis of the results from this investigation will later be presented, correlated to certain environmental influences (Chapter VI). Table 28 a. Total number of records, according t.o the distance observation method, of pteridophytes and other vascular epiphytes in the high forest. Explanation in Table 27 a. ). No. of Section of the Heavy Open Full observ. ph orophytes shade shade sun II III IV V A B c A B c A B c Pteridophytes Antrophyum immersum A. mannianum A rthropteris monoca rpa A. orientalis A. palisoli Asplenium aelhiopicum A. africanum A. barteri '! A. dregeanum A. geppii A. hemitomum A. megalura A. variable v. paucijugum Davallia chaerophylloides t> Drynaria laurenlii Elaphoglossum barteri E. chevalieri E. isabelense E. kuhnii E. salicifolium Lomariopsis guineensis Loxogramme lanceolata Lycopodium mildbraedii L. warneckei Microgramma owariensis 47 t> Microsorium punctatum Nephrolepis biscrrala l! N. undulata Oleandra distenta Phymatodes scolopendria Platycerium angolense P. stemaria Pyrrosia mechowii Tectaria angelicifolia T. fernandensis Vittaria guineensis Xiphopteris oosora X. serrulata X. vilosissima Total no. of observations 3354 Other vase. epiphytes II Ill IV V A B c A B c A B c Begonia mannii B. polygonoides B. rubro-marginata Calvoa monlicola C. trochainii Medinilla mannii Pcperomia fernandopoiana P. molleri P. rotundifolia Prcussiella chevalieri P. kamerunensis Remusata vivipa ra Rhipsalis baccifera Total no. of observations 598

83 " Table 28 b. Total number of records, according to the distance observation method, of orchids in the hi h fores t. (Explanation in Table 27 a.\ No. of Section o f the Heavy Open Full observ. phorophytes shade shade I! lil IV V A B A B A B c Orchids A rangis bi loba 64 A. laurentii 19 Ancistrochilus rothschildianus 21 Ancistrorhynchus capitatus A. cephalotes A. clandestinus A. recurvus Angraecopsis e lliptica Angraecum birrimense A. chevalier\ A. c\assensii A. distichum A. podochiloides A. subulatum Ansellia africana Bolusiella Lalbotii Brachycorytis kalbreyeri Bulbophyllum barbigerum B. bi farium B. bufo B. buntingii B. calamarium B. cochleatum B. cocoinum B. congolanum B. distans B. fa\catum B. flavidum B. imbricatum B. inflatum B. intertextum B. josephii B. linderi B. \ucifugum B. \upulinum B. magnibracteatum B. maximum B. melanorrachis B. nigritianum B. oreonastes B. pavimentatum B. phaeopogon B. recurvum B. rhizophorae B. saltatorium B. scariosum B. schimperanum B. schinzianum 19 B. winkleri 15 Calyptrochi \urn christyanum 70 C. emarginatum Chamaeangis vcsicat Cyrtorchis arcuata 186 C. aschersonii 17 C. monleiroac Diaphananlhe bidens 24 D. densiflora D. pellucida 27 D. rutila Eurychone rothschildiana Genyorchis pumila Graphorchis lurida 2 57 Habenaria leonensis 2 H. procera Liparis caillei L. nervosa Llstrostachys pertusa Nephrangis filiformis Plectrelminthus caudatus Podangis dactyloceras Polystachya adansoniae P. affinis P. dalzielii I loo I I I I , ,0 41, ,0 8. ) !J.G , M. 2 loo l!'i. : (; _ , 84.2 l!'i o.o Gu.o!U !} ;). l:s 0. 2 :)3.;),., ) I 28. (i H.3..G IG G 5,!! 58. :S ll.ti :. n.:j 1. :) I D P. elastica P. galeata P. lru<iflora , P. leonensis P. microbambusa P. obanensis P. paniculata ' P. pobeguinii P. polychaete P. puberula P. ramulosa P. rhodoptera P. saccata Polystachya subulata P. tenuissima 33, P. tessallata Ranga ris brachyceras R. musctcola R. rhipsalisocia Rhipidoglossum paucifolium Sto lz ia re pens Tridactyle anthomaniaca T. armeniaca G.!l ;, 11.1 o.n G T. bicaudata T. crassifolia T. tridactylites T. tridentata , , Vanilla crenulata Total no. of observations 6551

84 Ecology of vascular epiphytes in West African rain forest 77 The distribution on the phorophytes of the various epiphyte species showed somewhat different results depending on observation method. Compared to the results from the close observation method many species showed a ± marked displacement towards the outer parts of the crown in the distance observation. This could be anticipated since the epiphytes in the distance_ observation are more easily noticed when growing on the outer parts of the branches. Large branches from several phorophytes were examined according to the transect technique previously described. A rather clear distribution pattern for most species of epiphytes was obtained (Fig. 79), no matter if there were few or many species present. The distribution pattern also seemed to be similar between various species of phorophytes. Thus, the transects along the large branches seem to represent a rather fast and informative way to get a good insight into the distribution pattern for the various species. This method may preferably be used when there is a limited number of phorophytes to be examined. Table 29. Total number of records, according to the occasional observation method, of some epiphytes i n the high forest. (Explanation in Table 27 a.) No. of Section of the Heavy Open Full observ. phorophytes shade shade sun I! III IV V A B c A B c A B c Pteridophytes Arthropteris monocnrpn A. pa li soti Asplenium acthiopicum H A. hemitomum A. variable v. paucijugum Elaphoglossum kuhnii Lomnriopsis guineensis Tectarin nngclicifoli: T. fcrnandcnsis Xiphoptcris scrrulnta X. \'ilosissima GD G. G G Orchids Ancis trorhynchus c landes tinus Angraecum clnssensii A. podochi!aides Ansellia africana Brachycorythis kalbreyeri Bulbophyllum bifarium B. calamarium B. falcatum B. imbricatum B. i nfla tum B. magnibrac tca tum B. melanorrachis S s B. nigrilianum B. pavimcntntum B. recurvum B. rhizophorae 10 Calyptrochi turn emarginntum Cyrtorchis montcirone Diaphananthc densinora D. rutila Eurychone rothschi ldiana Genyorchis pum i la Habcnaria leonensis H. procera Lipa ris cnillci !) L. nervosa Podangis dnctyloccras Polystachyn nffinis P. elastica P. micmbnmbusa P. pobeguinii P. ramulosa P. rhodoptcra P. subula ta P. Lt=1iuissima Rangallris brachycerns , Rhipidoglossum paucifolium !J " 8 Stolzia repens Tridactyle bicaudaw Va nilla crcnulatn Other vase. epiphytes Calvoa monticola C. Lrochai n i i Peperomia mollcri Rcmusali:t \' ivipara ti ' Total no. of observations 147

85 78 Dick Johansson Asplenium barteri Asplenium geppii Asplenium megalura Loxogramme lanceolata Epiphyte communities Polystachya Bulbophyllum Bolusiella ra mulosa bufo talbotii Calvoa Begonia Rhipsalis monticola rubro-marginata baccifera vl IV Ill 11 I, '1, Polystachya leonensis Peperomia sp. Fig. 78. Occurrence of some epiphytes on the phorophytes distributed among the different sections. (From Table 27, Polystachya ramulosa from Table 29.) Terminology The frequently observed aggregation of epiphytes ('arboreal gardens' according to Oliver 1930:2) in limited areas on the phorophyte is of interest not only because of the information they provide as to common environmental requirements for various species but also as a source in the analyses of the colonization and development of the epiphytic flora in general. The terminology that has been used in the classification of epiphyte communities is confusing. The terms 'epiphyte societies' (Oliver 1930: 16) and 'association' Went 1940:86) have been used. Epiphytic association and epiphytic sociation were proposed by Omura (1953). Hosokawa (1953, 1954 a, b, c, 1968) has created a new terminology for the community units of epiphytes. From the viewpoint of the ecosystem concept he does not. agree with the use of phytocoenosial units for classifying epiphyte communities. Instead he has suggested the terms epies, epilia and epido, for various types of epiphyte communities (Hosokawa 1968:483). Raphidophora africana - 10 'stands' Elaphoglossum isabelense 'stands' Vittaria guineense 'stands' Angraecum birrimense --- Calvoa trochainii Medinilla mannii Peperomia sp. Oleandra distenta - Bulbophyllum cocoinum - Bulbophyllum intertextum - Angraecopsis elliptica Phymatodes scolopendria - Angraecum distichum Polystachya tessallata Asplenium megalura Drynaria laurentii Tridactyle armeniaca Polystachya galeata Cyrtorchis arcuata Polystachya puberula R hipsalis baccifera Graphorchis lurida Bolusiella talbotii m Platy<:erium angolense - Asplenium megalura 1/ittaria guineensis Angraecum distichum Polystachya tessallata Rhipsalis baccifera = Drynaria laurentii Graphorchis lurida Oleandra distenta m Fig. 79. Number of epiphytes and their distribution along a branch of: Left: Parinaria excelsa, illustrated according to the 'transect' technique. Seka Valley 600 m. Right: Pip- tadeniastrun africanum, illustrated according to the 'transect' technique. Yekepa 500 m.

86 Ecology of vascular epiphytes in West African rain fo rest 79 To avoid adding to the already confusing terminology of epiphyte communities, they will here simply be called epiphyte communities (e.c.). To separate them from each other they are named by the dominant species ('cover') and the most frequently occurring species in the community. This unit hould be homologous to the term 'epilia' proposed by Hosokawa. Methods The technique used in the investigation and description of terrestrial plant communities is impossible to use under the circumstances of growth and occurrence which the epiphytic plants exhibit. The knowledge of the epiphytic plant communities is based on records from close and distance examinations. The interest has been concentrated on the presence of the various species rather than on their number. An epiphyte community is considered to exist when a group of three or more species form a unit, and when the distance from two of them does not exceed 0.5 m to the third. The root systems and the stems are often heavily intermixed, to such a degree that the plants often grow on top of each other. Epiphytes that colonize the vegetative parts of other epiphytes are called hyper-epiphytes by Tixier ( 1966) and 'secondary' epiphytes by Hosokawa. The delimitation of an epiphyte community in most cases is easy to do, since the grouping of plants is rather distinct (Fig. 79). There are some spectacular exceptions from this rule. Drynaria laurentii may often cover stretches of more than five meters length. This extended distribution will of course connect a larger number of plants to this particular epiphyte. However, most epiphyte communities occur in a limited area with no other plants nearby. This is the case particularly for certain communities formed by epiphytes that are attracted to humus deposits. Seven different epiphyte communities are recognized Table 30. The number, distribution on the phorophytes and species composition of the epiphyte communities examined. (The distribution is given as a percentage of the total number of communities and the species composition according to close and distance observations.) Epiphyte community No of Distribution on the phorophyte No. of species commun. Sections Pterid. Orchids Others Total Grand total ll Ill IV V Cl Di Cl Di Cl Di Cl Di Angraecum birrimense- Raphidophora africana Asplenium africanum- Peperomia sp Oleandra distenta- Tridactyle armeniaca Microsorium punctatum- Vittaria guineensis J Drynaria laurentii- Asplenium megalura Platycerium stemaria- Nephrolepis undulata Platycerium angolense- Nephrolepis undulata Asplenium dregeanum- Peperomia sp Tridactyle tridactylites- Medinilla mannii Bulbophyllum scariosum- Polystachya dalzielii

87 80 Dick Johansson below 1000 m alt. and three more above that altitude. The investigation includes a total of 666 'community aggregations'. Their distribution on the phorophyte and the total number of species recorded in the various communities are given in Table 30. The ten most frequently occurring species in each community are presented in Table 32. Abundance Like epiphytes. in general the epiphyte communities are more abundant in older trees. A total of 25 'community aggregations' were found on the 118 trees that were examined in the three sample plots (Tables 14, 15 and 16). In relation to the abundance of the dominant species most communities were scarce. 0/eandra distenta, however, was found just as frequent in a community formation as in a single state. As would be expected the most common number of species in the individual communities is three, which are the lowest possible according to the definition used (Table 31). There are, however, some exceptions. The 0/eandra distenta - Tridactyle armeniaca and Angraecum bidrimense - Raphidophora africana communities, built up by more than five species each, were more common than those with a lesser number of species. The possible explanation to this could be that a more or less simultaneous colonization by several species is taking place when the community forming species has created a suitable environment. Both these communities are found in the lower parts of the phorophyte, and could possibly catch seeds or seedlings washed down by heavy rainfall. Epiphyte communities at altitudes below 1000 m Angraecum birrimense-raphidophora africana e.c. This community is most common around the first ramification on trees which have a rich supply of light in that section. This means that the community will appear mostly in secondary forests or on trees bordering rivers or creeks, or along tracks or roads. Table 31. The number of species in the different epiphyte communities, expressed as a percentage of the total number of records. Community Method of No No. of species examination examined > 5 Angraecum birrimense - Close Raphidophora africana Distance Asplenium africanum - Close Peperomia sp. Distance Oleandra distenta - Close Tridactyle armeniaca Distance Microsorium punctatum - Close Vittaria guineensis Distance Drynaria laurentii - Close Asplenium megalura Distance Platycerium stemaria - Close Nephrolepis undulata Distance Platycerium angolense - Close Nephrolepis undulata Distance Asplenium dregeanum - Close Peperomia sp. Distance Tridactyle tridactylites - Close Medinilla mannii Distance Bulbophyllum scariosum - Close Polystachya dalzielii Distance

88 Ecology of vascular epiphytes in West African rain forest 81 Fig. 80. Oleandra distenta - Tridactyle armeniaca epiphyte community. Grassfield 550 m. It gives an impression of an irregular jumble of herbaceous climbers, lianas and trailing epiphytes. The community is delicately balanced. An increase in light and evaporation will change this community leaving only the Diaphanthe orchids, a decreasing light supply will lead to an overgrowth by the vigorous Raphidophora africana. Asplenium africanum - Peperomia sp. e.c. Asplenium africanum that is rather uncommon, forms an accumulation of humus around its attachment to the substrate in a similar way as Microsorium punctatum. Only 13 communities have been found and examined, 8 with telescope and 5 on felled trees. With so few observations it is of little use to make an analysis of the occurrence of the various species. Worth mentioning is the presence of Peperomia sp. in 69.2 % of the communities examined. Oleandra distenta - Tridactyle armeniaca e.c. The fern Oleandra distenta, that forms the base of this community, is common and easily recognized. It often starts to grow in or around the ramifications of the larger branches in the central part of the crown. It expands in all directions but is mainly found at the basal parts of the branches that are often completely overgrown by thick cushions of this fern and species associated with it. The slender rhizomes often hang down giving this community a characteristic appearance (Fig. 80). In the earlier stages of the development of this community certain orchids may grow between the rhizomes, but later as debris is accumulated they become fewer and fewer. This community is not subject to the extreme variation in microclimate that exists further out on the branches, and the light intensity is naturally lower. These conditions are also reflected in the composition of the species in the community. A high number of pteridophytes and other vascular epiphytes (non-orchids) are typical. Note that no orchid species except Tridactyle armeniaca is found among the 10 most common species (Table 32). This community is composed of a mixture of humuspreferring species and species tolerating different kinds of substrate. Orchids with preference for rich humus and open shade found in this community are, e.g. Brachycorythis kalbreyeri and Habenaria procera. The majority of orchid species that occasionally occur here normally belong to the central or outer parts of the branches. Also the pteridophytes in this community are a mixture of species of humid habitats such as filmy ferns and Nephrolepis undulata, as well as Drynaria laurentii and Microsorium punctatum of more sunny and drier sections of the crown. Begonia polygonoides, Remusatia vivipara, Peperomia sp. as well as more drought resistent species such as Rhipsalis baccifera and Begonia rubro-marginata are also frequent in this community. Microsorium punctatum - Vittaria guineensis e.c. This community has a very limited distribution and

89 82 Dick Johansson Table 32. The ten most common species in the different epiphyte communities. The occurrence is given as a percentage of the Close observation Distance observation total number of communities examined (Table 30). Plathycerium stemaria - Nephrolepis undulata e.c. Nephrolepis undulata 58.3 Nephrolepis undu1ata 66.7 Close observation Distance observation Polystachya tessallata 38.9 Begonia rubro-marginata 50.0 Peperomia sp Polystachya tessallata 38.8 Angraecum birrimense - Raphidophora africana e.c. Begonia rubro-marginata 27.8 Davallia chaerophylloides 38.8 Raphidophora africana 79.3 Raphidophora africana 83.3 Vittaria guineensis 22.2 Diaphananthe bidens 33.3 Vittaria guineensis 48.2 Elaphoglossum barteri 36.1 Lycopodium warneckei 19.4 Rhipsalis baccifera 33.3 Elaphoglossum barteri 34.5 Vittaria guineensis 33.3 Rhipsalis baccifera 16.7 Vittaria guineensis 27.8 Calvoa trochainii 34.5 Diaphananthe bidens 27.8 Polystachya galeata 13.9 Tridactyle anthomaniaca 22.2 Diaphananthe bidens Ancistrorhynchus capitatus 25.0 Asplenium megalura 11.1 Peperomida sp Microgramma owariensis20.7 Calvoa trochainii 25.0 Polystachya polychaete 11.1 Asplenium megalura 11.1 Nephrolepis undulata 20.7 Peperomia sp Habenaria procera 13.8 Microgramma owariensis: 13.9 Platycerium angolense - Nephrolepis undulata e.c. Ancistrorhynchus capitatus 6.9 Nephrolepis undulata 11.1 Nephrolepis undulata 47.5 Nephrolepis undulata 60.0 Rhipidoglossum paucifolium 6.9 Diaphananthe rutila 5.6 Polystachya tessallata 30.0 Polystachya tessallata 40.0 Peperomia sp Davallia chaerophylloides 30.0 Asplenium africanum - Peperomia sp. e.c. Davallia chaerophylloides 17.5 Begonia rubro-marginata 30.0 Peperomia sp Peperomia sp Begonia rubro-marginata 15.0 Diaphananthe bidens 30.0 Asplenium megalura 40.0 Preussiella sp Vittaria guineensis 15.0 Rhipsalis baccifera 30.0 Calvoa trochainii 40.0 Begonia mannii 25.0 Polystachya galeata 12.5 Tridactyle anthomaniaca 30.0 Elaphoglossum barteri 20.0 Arthropteris orientalis 25.0 Lycopodium warneckei 12.5 Vittaria guineensis 20.0 Nephrolepis undulata 20.0 Nephrolepis undulata 12.5 Nephrolepis biserrata 7.5 Chamaeangis vesicata 10.0 Begonia mannii 20.0 Asplenium megalura Polystachya tessallata Diaphananthe bidens 7.5 Lycopodium warneckei 10.0 Asplenium dregeanum - Peperomia sp. e.c. Oleandra distenta - Tridactyle armeniaca e.c. Peperomia sp Tridactyle armeniaca 53.8 Tridactyle armeniaca 41.7 Polystachya leonensis 28.6 Peperomia sp Drynaria laurentii 30.6 Elaphoglossum chevalieri 21.4 Nephrolepis undulata 34.6 Begonia polygonoides 27.8 Asplenium barteri 19.0 Phymatodes scolopendria 30.8 Rhipsalis baccifera 27.8 Medinilla mannii 16.7 Begonia polygonoides 26.9 Phymatodes scolopendria 25.0 Arthropteris monocarpa 14.3 Calvoa trochainii 23.1 Nephrolepis undulata 19.4 Polystachya laxiflora 14.3 Rhipsalis baccifera N ephrolepis biserrata 16.7 Asplenium aethiopicum 11.9 Preussiella chevalieri 19.2 Elaphoglossum isabelense 16.7 Begonia rubro-marginata 9.5 Asplenium megalura 15.4 Peperomia sp Bulbophyllum inflatum 7. 1 Microsorium punctatum 11.5 Asplenium megalura 12.5 Tridactyle tridactylites - Medinilla mannii e.c. Microsorium punctatum - Vittaria guineensis e.c. Medinilla mannii 58.8 Medinilla mannii 53.5 Vittaria guineensis 51.8 Vittaria guineensis Asplenium dregeanum 41.2 Polystachya laxiflora 27.9 Peperomia sp Davallia chaerophylloides 33.3 Polystachya leonensis 35.3 Lycopodium mildbraedii 25.6 Davallia chaerophylloides 37.0 Peperomia sp Vittaria guineensis 35.3 Peperomia sp Polystachya tessallata 29.6 Polystachya tessallata 27.8 Asplenium barteri 29.4 Polystachya leonensis 23.3 Diaphananthe bidens 25.9 Asplenium megalura 25.0 Polystachya laxiflora 23.5 Asplenium dregeanum 20.9 Begonia rubro-marginata 2:2.2 Medinilla mannii 25.0 Polystachya obanensis 23.5 Vittaria guineensis 18.6 Nephrolepis undulata 18.5 Diaphananthe bidens 19.4 Rangaeris muscicola 23.5 Cyrtorchis arcuata 13.9 Oleandra distenta 18.5 Graphorchis lurida 13.9 Peperomia sp Bulbophyllum scariosum 11.6 Medinilla mannii 14.8 Angraecum birrimense 13.9 Elaphoglossum barteri 17.6 Elaphoglossum salicifolium 11.6 Bulbophyllum cocoinum 14.8 Nephrolepis biserrata 11.1 Bulbophyllum scariosum - Polystachya dalzielii e.c. Drynaria laurentii- Asplenium megalura e.c. Xiphopteris oosora 42.9 Polystachya dalzielii 44.4 Asplenium megalura 53.2 Asplenium megalura 43.7 Polystachya dalzielii 42.9 Lycopodium mildbraedii 27.8 Tridactyle armeniaca 46.8 Rhipsalis baccifera 29.7 Elaphoglossum salicifolium 28.6 Asplenium megalura 22.2 Rhipsalis baccifera Tridactyle armeniaca 25.0 Bulbophyllum bifarium 28.6 Vittaria guineensis 22.2 Polystachya tessallata 32.3 Graphorchis lurida 25.0 Xiphopteris vilosissima 28.6 Tridactyle tridactylites 22.2 Bulbophyllum linderi 25.8 Bulbophyllum oreonastes 18.7 Arthropteris monocarpa 14.3 Elaphoglossum salicif Ficus kamerunensis 22.6 Angraecum distichum 17.2 Asplenium megalura 14.3 Asplenium geppii 11.1 Graphorchis lurida 22.6 Cyrtorchis arcuata Lycopodium mildbraedii 14.3 Arthropteris sp Polystachya galeata 16.1 Polystachya tessallata Polystachya pobeguinii 14.3 Podangis dactyloceras 11.1 Medinilla mannii 11.3 Phymatodes scolopendria 12.5 Vittaria guineensis 14.3 Asplenium aethiopicum 11.1 Nephrolepis undulata 9.6 Bulbophyllum linderi 11.7 Acta phytogeogr suec. 59

90 Ecology of vascular epiphytes in West African rain fo rest 83 Fig. 81. Simplified drawing of a Microsorium punctatum - Vittaria guineensis epiphyte community. (A) Microsorium punctatum, (B) Davallia chaerophylloides, (C) Asplenium megalura, (D) Polystachya tessallata, (E) Tridactyle anthomaniaca, (F) Peperomia rotundifolia, (G) Vittaria guineensis. serves as a small refuge for humus-demanding species, particularly if it grows on a smooth barked phorophytes (Fig. 81). Two plants that are often associated with this particular fern are Vittaria guineensis and Davallia chaerophylloides. Drynaria laurentii - Asplenium megalura e.c. The Drynaria fern is probably the most common species of epiphyte in the investigated area. It is found in sunny habitats mostly in the crowns. It easily gets a foothold on smooth surfaces; it can even be seen growing on vertical concrete walls. This highly specialized fern has two kinds of fronds (Fig. 26). The fertile fronds have long narrow finger-like pinnately arranged lobes. These lobes or segments are articulated from the midrib after maturity. Afterwards the midribs remain in an erect position for many years. The sterile fronds are thin and papery, somewhat resembling oak leaves, and are held upright and more or less parallel to the substratum. Between these sterile, mostly dead leaves and the substratum a niche is formed in which materials of various kinds are collected. The sterile leaves are persistent and remain in function as 'humus collectors'. When they get older and start to decay, the veins persist forming a delicate net. This species is a very hardy plant that is able to survive severe conditions. A colony that was placed on top of a flat aluminium roof, with no protection whatsoever, showed no sign of discomfort but continued to grow year after year. Fig. 82. Simplified drawing of a Drynaria laurentii - Asplenium megalura epiphyte community, 29 m above the ground, on a Piptadeniastrum africanum. Yekepa 530 m. (A) Drynaria laurentii, (B) Oleandra distenta, (C) Bulbophyllum lupulinum, (D) Bulbophyllum bufo, (E) Graphorchis lurida, (F) Bulbophyllum buntingii, (G) Asplenium megalura.

91 84 Dick Johansson Fig. 84. Platycerium stemaria - Nephrolepis undulata epiphyte community. Nimba Range 700 m. Note the large Begonia rubro-marginata in the centre. Fig. 83. Drynaria volkensii and Rhipsa/is baccifera. Usambara Mts 900 m, Tanzania. The rhizome is thick and hard, covered with a dense insulating layer of scales. Sometimes it branches, particularly when it grows in a vertical direction. The Drynaria community has a wide distribution and passes through several stages in its development. During the colonization stages (Fig. 82) epiphytic orchids, e.g. Bulbophyllum oreonastes grow on the open bark surfaces between the rhizomes of the fern. The high total number of orchids, with not less than 38 species registered from this community, are mostly connected to this stage. As the fern grows and takes larger parts of the substrate in possession the orchids become less numerous. The humus is utilized by several plants. Rhipsalis baccifera and Peperomia sp. are among the first to settle in this environment (Fig. 83). Among the orchids Angraecum distichum and even Graphorchis lurida are still present during this stage in development. When more humus has been formed Asplenium megalura will be common. In roughly every second community examined this species was present. In the final stage a wide array of plants that are favoured by a rich supply of humus invade the thick densely overgrown accumulation. Now even terrestrial plants appear as facultative epiphytes. During this s age the Drynaria fern itself plays an inferior role, and is in many cases dead or dying. As a matter of fact the presence of rhizomes and old sterile leaves from Drynaria laurentii in the bottom parts of many rich accumulations indicate this process. From the Usambara Mts in Tanzania Moreau (1943) reports: "Somewhat contrary to the expectation orchids do not occur in association with the coarse epiphytic fern Asplenium nidus and Dryopteris laurentii (Drynaria laurentii) which would seem to offer favourable foothold, but orchids often have their roots closely interwoven with those of smaller ferns and naturally are often more or less embedded in moss and lichens." This is partly true, even if I myself on a brief visit in the same area dis-

92 Ecology of vascular epiphytes in West African rain fo rest 85 Fig. 85. Chamaeangis vesicata in a Platycerium angolense Nephrolepis undulata epiphyte community. Y ekepa 500 m. covered several ferns and one orchid, Cirrhopetalum umbellatum (Forst. f.) Hook. & Arn., associated with Drynaria volkensii. Moreau probably refers to the first stages when the Drynaria fern seldom has any other epiphytes associated with it. Platycerium stemaria - Nephrolepis undulata e.c. and Platycerium angolense - Nephrolepis undulata e.c. Two species of the genus Platycerium are common in the Nimba area, Platycerium angolense and P. stemaria can often be found together in non-limiting environments, but in open or more exposed habitats Platycerium angolense dominates. In other parts of Africa they also grow on rocks, e.g. in the Matombo region east of the Uluguru Mts in Tanzania. Both species are widespread in tropical Africa. They inhabit the outermost branches of trees in the primary forest, but in secondary forest or on scattered trees around villages and in farmland they can be found on any part of the tree. The fertile and sterile leaves are of a different shape (Figs 84, 85). This dimorphism is of a particular function in the life of the plant. The sterile leaves can be divided into two sections. The upper part is open towards the air on both sides, it is thin and pergameneous. Their function is to collect the falling debris to be used in the building of humus. The lower part of the sterile leaves is considerably thicker. This part of the leaf is a deposition area for the debris that has been trapped between the upper part of the leaf and the branch or trunk. The space between the sterile leaves is utilized by roots that clearly can be seen through the lower parts of the newly developed sterile leaves. The fertile leaves are long and pendulous. The rhizome is short. It is not creeping as in most other epiphytic ferns but is always growing at a 90 degree angle towards its point of attachment. The occurrence of the Platycerium communities in relation to the total presence of these ferns, is low. The low number of epiphytes associated with the Platycerium ferns is also surprising. Platycerium angolense had 17 species and P. stemaria 22 species totally. A look at the species compositions shows that the plants associated with the Platycerium ferns commonly appear in other epiphytic communities as well. Nephrolepis undulata is the species that most frequent takes advantage of the substrate or perhaps a favourable microclimate caused by the large Platycerium leaves. Boy er ( 1964) reports that Microgramma owariensis and Phymatodes scolopendria sometimes are associated with Platycerium ferns. She also mentions that small plants of cocoa trees and oil palms were found in accumulations of these ferns. Holtum (1960) states that: "Cymbidiella rhodochila in Madagascar is invariably found growing in association with a Platycerium. " The same observation appears in Encyclopedia of Cultivated Orchids (Hawkes 1965:139) with no reference to the source. Epiphyte communities at altitudes above l 000 m Asplenium dregeanum-peperomia sp. e.c. At the base of trunks (from the ground to roughly 4-5 m height) Asplenium dregeanum and Peperomia

93 86 Dick Johansson Fig. 86. Tridactyle tridactylites - Medinilla mannii epiphyte community. Mt Gbahm 1300 m. sp. dominate. They are so common that nearly every tree has at least one of them on its trunk. At these altitudes the filmy ferns are also common and particularly on the trunks, and thus are often associated with the species of this community.. The dominating fern, Asplenium dregeanum, multiplies by sending out modified stolon-like fronds which take root and produce a colony of daughter plants, expanding the community in many directions. Since this community occurs on the trunks relatively close to the ground no distance observations had to be performed. Tridactyle tridactylites - Medinilla mannii e.c. In the central part of the crown and especially around the larger ramifications the orchid Tridactyle tridactylites forms huge interwoven masses (Fig. 86). Here several plants occur, such as Polystachya laxiflora, P. leonensis and Asplenium dregeanum. Scattered groups of filmy ferns may occur but very dominant are the mosses that occupy the major part of the branches in ahd around this community. Bulbophyllum scariosum - Polystachya dalzielii e.c. This somewhat less clearly defined community is found in the central or outermost parts of the branches. It includes a number of small sized epiphytes, e.g. Xiphopteris villosissima, that are easily overlooked in a distance examination. Two species of orchids dominate this community: Bulbophyllum scariosum which is easily seen, while the more tiny Polystachya dalzielii is harder to observe when not in flower. In this section of the crown the lichens cover the branches or hang down ( Usnea sp.) from the finest twigs. General observations Ferns form the base in seven of the ten recognized communities. In all these communities it is the substrate-building capacity of the ferns that seem attractiv e to the other species. Interaction and antagonism between ferns and orchids, as well as between mosses and liverworths, have been reported by Tixier. He found that the 'stations' rich in orchids has generally no ferns and reciprocally. "Les Fougeres presentent une axemie assez forte vis-a-vis des Orchidees" (Tixier 1966:124). However, Drynaria rigidula was found to hold numerous epiphytes. This statement may seem to contradict the observations in the Nimba area, but the statement is more correct for the lower parts of the trunks (a section which was particularly carefully examined by Tixier). It is, however, hard to asess the amount of competition between ferns and orchids. In many cases it is probably the low light intensities close to the ground that limit the presence of orchids, and higher up in the trees the evaporating power of the air often limits the presence of ferns. Epiphyte succession As the phorophyte grows it will pass through several 'environmental stages', e.g. it's place in the forest alters, the size and the shape of the crown and the morphology of the bark changes. These are primary changes. Secondary changes, e.g. establishment of new species of epiphytes will effect the competition between the epiphytes. The epiphytic flora itself also participates in the successional processes through active or passive contributions to the formation of humus. Direct or indirect methods may be employed to estimate the changes. The best method would naturally be to map the epiphytic flora on a number of branches in the crowns of living trees. These branches could then be re-examined after certain time intervals, thus giving a correct picture of the development and eventually changes of the flora. This method would be similar to the 'permanent quadrate' technique used in terrestrial ecology, except for the changes in size of the branch caused by growth or broken off pieces. Unfortunately this method is for practical reasons very difficult to use. The inaccessibility of the tree crowns has previously been discussed. The slow development of many of the epiphytic plants, e.g. the orchids, would also

94 Ecology of vascular epiphytes in West African rain fo rest 87 make it necessary to continue the observations for a very long period of time. Thus the difficulties connected with a detailed study of the epiphytic flora on a phorophyte in situ make this kind of investigation less useful. There are, however, several indirect methods to use. Comparisons of the epiphytic flora between phorophytes in the primary forest and on phorophytes that have become more exposed through changes in their environment may give valuable information on the amount and direction of eventual changes. Analyses of humus deposits may also reveal traces of an earlier epiphytic flora. Epiphyte succession in Himalayan Quercus forest The sucessions of epiphytes has been studied by Dudgeon (1923) in a Quercus incana forest at Landour, Western Himalayas ( m). Since the earliest stages in the colonization of the branches are not dealt with in this study it might be of interest to give an account of his observations. Six separate stages are distinguished: 1. Crustose lichen stage; starting when the branch is three to four years old. 2. Foliose and fructicose lichen stage; starting almost as early as the crustose lichens, but begins to make a characteristic presence three to four years later. 3. Pioneer moss stage; pioneer mosses gain foothold in favourable spots. Other trailing and erect mosses gradually crowding out the lichens, probably by shading them. 4. Climax moss stage; starting when the thick continuous pads are developed. Under favourable conditions this stage is reached in about 20 years. 5. Fern stage; starts when epiphytic ferns gain footholds in the moss pads. The fern stems and roots collect and hold more dust, forming a soil bed that may attain a thickness of 10 cm. 6. Flowering plant stage; starts with the appearance of other vascular plants apart from the ferns. Dudgeon summarizes his observations: "Successions shown by epiphytes are considered to be unique, because of (1) the short time required for completion, (2) the unusual clearness of successive stages, (3) the small size of the plants involved, and ( 4) the adaption of the plants to repeated and prolonged desiccation." Although Dudgeon's investigation refers to a cooler environment than the rain forest in Nimba, the pattern described could with some exceptions be said to be valid for the rain forest in Nimba as well. orchids pteridophytes other vase. epiphytes [] 18'/, 10'1. orchids + other vase. pteridophytes + orchids pteridophytes epiphytes + other vase. epiphytes D 18'1. 10'1. pteridophytes + orchids + other vase. epiphytes 40'1. Colonization stages Initial Intermediate Final Fig. 87. 'Colonization stages'. The number of phorophytes in sample plots have been split into seven classes based on the presence of different epiphytes. The occurrence of the different classes is given as a percentage of the total number of phorophytes and is also illustrated in blocks proportional to each other. The moss stages (3 and 4) are non-existent in the rain forest below 1000 m altitude, but become increasingly important at higher altitudes. Succession indicated by floristic composition This analyse is built on the assumption that sooner of later species from all of the three major groups of epiphytes, (i.e. the pteridophytes, the orchids and the other vase. epiphytes), will be represented on the phorophyte. No phorophyte, except the oil palm, Elaeis guineensis, has given proof of being rejected by any particular group of epiphytes. Three stages in the colonization of the phorophytes are recognized, the initial, intermediate and final. stage. During the initial stage species from only one of the major groups of epiphytes are represented on the phorophyte. In the intermediate stage species from two groups are present, and in the final stage species of all groups are occurring on the phorophyte. From the three sample plots (Tables 14-16) the occurrence of phorophytes representing the three colonization stages are given in Fig. 87. The colonization seems to start with the pteridophytes or the other vascular epiphytes. This initial stage is succeded by the entry of the orchids. As time passes these phorophytes in the intermediate colonization stage will most likely be colonized by some species from the third group and enter the final stage. Succession traced by analysis of humus deposits This technique was used in the attempt to reconstruct the development of the humus deposits

95 88 Dick Johansson and the plants involved in this process. The nature of these deposits is very heterogeneous. They are built up of material in all stages of decomposition, mostly resembling peat. Occasionally the decomposition has gone so far that a mineralization has begun. Such soil-like deposits can be found at the basal parts on the large branches of old trees. More commonly deposits are built up by material that is partly decomposed. It is rather surprising that parts of dead plants incorporated in the accumulation several years earlier frequently can be identified. This shows either that the plants are very resistent towards decomposition, or that the micro-organisms that are responsible for the break -down process are restrained in their activities by the environment, which is regularly subjected to drought. Several cross-sections were cut through the accumulations at a right angle to the axis of the phorophyte, with a sharp broadblade knife. This gave a glimpse of the 'stratification' in situ. The content from the bottom layer was sifted through a sieve with a mesh of 10 x 10 mm. Remains of plants, such as old pseudobulbs and rhizomes, could then much easier be discovered. A total of 13 deposits of five different epiphyte communities were examined. Angraecum birrimense - Raphidophora africana e.c. Two communities, both occurring on the trunk 3-4 m above the ground on two tall trees, were examined. The humus layer was thin and held in a vertical position by a network of roots. Six species of epiphytes were present: Angraecum birrimense, Calvoa trochainii, Diaphananthe rutila, Nephrolepis undulata, Polystachya rhodoptera and Raphidophora africana, with the first and last species dominating. In the bottom layer in one of the communities 3 groups of pseudo bulbs from Polystachya affinis were discovered. Drynaria laurentii - Asplenium megalura e.c. Three humus deposits from this community were examined. Two came from the central part of the crown and one from the outermost part. In one of the deposits from the central part of the crown some old pseudobulbs probably produced by Bulbophyllum lupulinum and pseudobulbs and aerial roots of Graphorchis lurida were discovered. Microsorium punctatum - Peperomia sp. and Platycerium stemaria - Nephrolephis undulata e.c. In two accumulations each of a Microsorium punctatum and a Platycerium stemaria community no traces of an older epiphytic flora could be found. Oleandra distenta - Tridactyle armeniaca e.c. Accumulations from this community proved to be the most rewarding in the search for remains of an earlier flora. Four such accumulations were investigated, two of which held remains that could be identified. In one of them sterile leaves and rhizomes of Drynaria laurentii appeared in the bottom layer. The other accumulation was so rich in old plant remains that it will be presented in detail. This community was located at the basal part of a large branch I 7 m above the ground on a Lophira alata at 600 m altitude. The thickness of the humus layer was not less than 16 cm. In the bottom part of the accumulation the material was partly mineralized. The size of the investigated part was 0.2 x 4.0 m. The surface vegetation was a dense aggregation of Oleandra distenta with the rhizomes hanging down from the branch on both sides. Ten more species were present: Asplenium megalura, Arthropteris orienta/is, Begonia polygonoides, Bulbophyllum cocoinum, Brachycorythis kalbreyeri, Habenaria leonensis, Nephrolepis undulata, Medinilla mannii, Polystachya polychaete and Rhipsalis baccifera. The topmost 10 cm of this accumulation had a felt-like structure, and was composed of living and dead roots and rhizomes. Below this layer large quantities of partly decomposed plant material were found. Sterile leaves and rhizomes of Drynaria laurentii were accompanied by leaves and rhizomes from Phymatodes scolopendria and pseudobulbs of Graphorchis lurida and several unidentified Bulbophyllum spp. Traceable remains of an earlier epiphytic flora were found in 30.7 % of the accumulations examined. It is interesti. ng to note that the species that were overgrown were all able to colonize clean bark surfaces, so called pioneer epiphytes, e.g. Polystachya a finis, Drynaria laurentii, and several Bulbophyllum spp. The expansive growth of the Drynaria fern will regularly overgrow or surpress other plants of slower growth, e.g. the many Bulbophyllum spp. that frequently occur in the same habitat. In the 0/eandra distenta-tridactyle armeniaca community it looks like several other epiphytes also are active in the accumulation of humus, and that Olean-

96 Ecology of vascular epiphytes in West African rain fo rest 89 Table 33. Epiphytes recorded on three Lophira alata, A, B and C. (See text.) Fig. 88. Drynaria laurentii on a phorophyte in secondary forest. Mt Tokadeh 700 m. Epiphyte Phorophyte A B c Asplenium megalura + + Drynaria laurentii Elaphoglossum isabelense + + Elaphoglossum salicifolium + Oleandra distenta + Phymatodes scolopendria + Vittaria guineensis + Aerangis laurentii + Angraecum birrimense + Angraecum distichum + Angraecum subulatum + Bulbophyllum distans + + Bulbophyllum linderi Bulbophyllum maximum + Bulbophyllum oreonastes Bulbophyllum phaeopogon + Bulbophyllum saltatorium + Bulbophyllum schimperanum + Bulbophyllum schinzianum + Chamaeangis vesicata + Cyrtorchis arcuata + Graphorchis lurida + Listrostachys pertusa Plectrelminthus caudatus + Polystachya polychaete + + Polystachya saccata + + Tridactyle anthomaniaca Tridactyle armeniaca + + Tridactyle crassifolia + Medinilla mannii + + Peperomia rotundifolia + Rhipsalis baccifera + A B Total no. of species dra distenta under certain conditions can utilize this substrate. The fact that this community is restricted to the basal area of the crown indicates that a large accumulation of humus is not enough to promote a successful colonization by Oleandra distenta. c Fig. 89. Number of orchid species on three Lophira alata: A, B and C. (See text and Table 33.) The figures in the overlapping areas give the number of species in common. Effects of environmental changes The direction of the colonization process may be reversed or changed if the phorophyte is subjected to an environmental change. Such changes -occur frequently when the forest is affected by human activities. Here and there isolated trees will be left for one reason or another. A telescopic survey of twelve large isolated trees in Y ekepa revealed that the ratio between species of pteridophytes and orchids was roughly 1:3 (12:39),

97 90 Dick Johansson which may be compared to the ratio in the dense forest that was exactly 1 :2 (19 :38, Table 17). This is hardly surprising, since the higher light intensities will favour the orchids which also are able to withstand the much drier environment of more exposed trees. Drynaria laurentii is the only fern that can take advantages of these changes in the environment, and occurs here in sizes and numbers never found in the dense forest (Fig. 88). Rhipsalis cassytha is the only species of the other vascular epiphyte group that seems to thrive on these exposed phorophytes. Comparison of the epiphytic flora on three phorophytes of the same species (Lophira alata) of approximately the same sizes, from the same altitude but growing in three different habitats, may exemplify the effect of the environment in more detail. One phorophyte (A) was 42 m in size and grew in a high forest surrounded by several other trees of the same size. The second phorophyte (B) was 40 m and was left in a forest subjected to logging operations that had created a rather broken canopy. The third phorophyte (C) was 39 m and grew in a very exposed environment with several dead trees around it. A total of 3 2 species of epiphytes were recorded from these three phorophytes (Table 33). A more open environment seems mainly to limit the presence of non-orchid epiphytes. The number of orchid species was about the same on all of the phorophytes (12, 12 and 11), but it should be noticed that the phorophyte (C) in the most exposed environment had only four orchid species (36.3 %' in common with the phorophyte from the most protected environment (A) (Fig. 89). This may indicate that most of the orchids are adapted to rather narrow environmental conditions, which also could explain their richness in species. The study of the changes during a two years period in the epiphytic flora on a branch that had fallen down from a large tree may serve as an example of changes that occur when the environment becomes darker and more humid. The branch had fallen down over a small creek and was lying about 2 m above the small stream. A stretch of six meters was examined, in November 1967 and re-examined at the same time during the years 1968 and 1969 (Table 34). One must remember when analyzing the changes in the flora on this branch that it does not represent the same substrate as a living branch. The effect of the decomposition of the bark remains unknown. Anyway, the changes may give an idea of the tolerance or adaptability of the various species involved. The original species composition shows a number of sun-demanding orchids, pteridophytes and other vascular epiphytes. Only after some months the leaves of the orchids started to turn yellow. After one year the Bulbophyllum species were dead and so were the Angraecum distichum and Polystachya saccata specimens. After one year three species of Table 34. Changes in the epiphytic flora on a dead branch during a two years period. (See text.) 1967 Orchids Angraecum distichum Bulbophyllum intertextum Bulbophyllum oreonastes Graphorchis lurida Listrostachys pertusa Polystachya saccata Tridactyle armeniaca Pteridophytes Asplenium megalura Drynaria laurentii Lycopodium warneckei Nephrolepis undulata Vittaria guineensis Other vase. epiphytes Rhipsalis baccifera 1968 Orchids Graphorchis lurida Listrostachys pertusa Tridactyle armeniaca Pteridophytes Arthropteris monocarpa Asplenium megalura Nephrolepis undulata Oleandra distenta Other vase. epiphytes Begonia polygonoides Peperomia sp. Remusatia vivipara Raphidophora africana 1969 Orchids Brachycorythis kalbreyeri Tridactyle armeniaca Pteridophytes Arthropteris monocarpa Asplenium barteri Asplenium megalura Asplenium paucijugum Elaphoglossum kuhnii Oleandra distenta Vittaria guineensis Other vase. epiphytes Begonia mannii Begonia polygonoides Calvoa monticola Remusatia vivipara Raphidophora africana

98 Ecology of vascular epiphytes in West African rain forest 91 Fig. 90. Epiphytes on a dead branch (see text). (A) Remusatia vivipara, (B) Nephrolepis biserrata, (C) Oleandra distenta. orchids were still alive, but the Graphorchis lurida plants had developed very elongated leaves and the plant did not flower later in the season. The few Tridactyle armeniaca and Listrostachys pertusa specimens were also in poor shape. The Drynaria plants had been overgrown by Nephrolepis undulata, and Raphidophora africana seedlings could be seen in large numbers. After two years the branch was completely overgrown by epiphytes. Nephrolepis undulata and Raphidophora africana dominated the picture (Fig. 90). Only one species of the original group of orchids was still alive, but some small seedlings of Brachycorythis kalbreyeri were discovered. Effects of the epiphytes on the phorophytes According to the definition of an epiphyte, it should not affect the phorophyte in a direct way, e.g. draw water of nutrients from its living tissues. EARLIER OBSERVATIONS Indirect effects Epiphytes may affect the phorophyte in a more indirect way. There are many opinions concerning the effect of cryptogamic epiphytes on the phorophytes, as related by Barkman (1958:18-19) and Ruinen (19 53: 10 1). It has generally been recognized that epiphytic growth is richer on dead than on living trees, but without experimental proof it is difficult to say whether the epiphytes are the direct cause of death of the phorophyte, or only infest sick trees, eventually accelerating their death. The presence of a Fig. 91. Very extensive epiphytic growth on a tall tree. Nimba Range 800 m. rich moss or lichen flora may indirectly contribute to a higher humidity in the bark which would favour development of numerous fungi that saprophytically or parasitically could endanger the existence of the phorophyte. Bacteria and insects may also take advantage of the humid environment. The vascular epiphytes have generally been considered harmless and at most troublesome due to overgrowing (Fig. 91) and thus strangling the hosts on which they live, e.g. Richards (1964:110): "Through epiphytes are wholly dependent on other plants, they in their turn have little effect on their supports." Coffee growers in Java suspect that the common epiphyte Cyclophorus nummularifolius kills the coffee trees as reported by Went (1940:92). The latter thinks this is only an illusion since these epiphytes are most common on the upper dead branches and twigs. When the dead branches fall the roots and rhizomes keep them hanging around the

99 92 Dick Johansson tree instead of falling down to the ground. This creates the impression that the trees carrying this epiphyte have more dead branches than others. Direct effects Cook-Melville (1926) considers the epiphytic orchids to be parasites on citrus trees in Puerto Rico. The generally accepted belief that epiphytes as a whole are limited to a non-parasitic life has been carefully examined by Ruinen (1953), whose opinion and interesting results will be summarized here. She states that the typical epiphytes preferably develop on young, living tissue and that plants declining in health usually recover, if the epiphytes are removed. Contrary to Went, Ruinen confirms the observation by planters on Java that cleaning their coffee, tea and citrus trees from epiphytes causes the trees to become healthier subsequent to this treatment. The early symptoms of decline under epiphytic growth are difficult to define. They suggest a general deficiency, an aspect of ill-health, of failing. The leaves are no longer lush, still green but less so than usual, not as turgescent as the non-infested branches, but nevertheless not wilted. In this stage the developing buds are slightly smaller. The leaf fall is premature, therefore the vegetative period is shortened. The noxious effect is localized at first to the parts directly under the epiphyte, the other parts are only secondarily affected, viz. show the influence at a later date. The phenomenon, which is termed epiphytosis, may be described as a slow exhaustion of all partners of the biocoenosis one after the other (Ruinen 1953:108). As the epiphytes are known to be mycotrophic, the most simple form in which the biocoenosis in its relations and deterioration might be represented is illustrated in Fig. 92. epiphy te + fungus L s y mbiosis _j ( + support antibiosis J Fig. 92. Interactions between epiphyte, fungus and support. (From Ruinen ) The prompt recovery of the host plant when the epiphytes are removed was experimentally proved. Plants artificially infected with the fern Drymoglossum showed a rapid decline within a year. An anatomical investigation revealed that in the infested branches the vessels were partly blocked by gum and fungus and the cortex contained many hyphae. The resultant deficient nutrient and water supply would amply account for the inhibitory effect. The invading hyphae were traced microscopically to the place of exit from the epiphyte in which it formed a mycorrhiza. The inference drawn from this is that the mycorrhizal fungus of the epiphyte is potentially parasitic on the supporting trees. It depends on the constitutional conditions presented by the supporting tree, whether or not it will appear as such. It would seem hardly possible to speak of a symbiosis between epiphyte and supporting plant, were it not for the failures in cultivating some orchids, e.g. Taeniophyllum sp. on inorganic substrate and, moreover, for the marked preference shown by epiphytes for some definite phorophytes under otherwise identical environmental conditions. These conditions are undoubtedly inherent in the supporting plant itself, which obviously of(ers favourable symbiotic relations with the epiphytes, and therefore, from the point of the support the symbioses should be qualified as antagonistic. Ruinen concludes that the generally accepted belief that epiphytes as a whole are limited to a saprophytic habit, seems not only open to discussion but as such has been proved to be actually erroneous. (Cf. Harvais & Hadley 1967.) In a study of structural connections between epiphytes and host plants, Furman (1959:127) has made observations similar to those of Ruinen. In a Honduran cloud forest the interpenetration of root hairs or root mycelium with host tissues was examined. Vascular epiphytes, chiefly orchids, bromeliads and ferns, were found to penetrate living hosts' stem tissues with root hairs, or share a common fungus mycelium with them. Frequently the host tree stems had very thin, lightly suberized bark. Schimper (1935 :311) have earlier stressed the fact that many epiphytes belong to those families known for their mycorrhiza, e.g. Orchidaceae, Ericaceae, Melastomaceae and 'perhaps' even other ones and that the fu ngus might play an important role in the metabolism of the epiphyte.

100 Ecology of vascular epiphytes in West African rain fo rest 93 AUTHOR'S OBSERVATIONS Any direct effect by the epiphytes on their phorophytes has not been noticed. However, certain species of phorophytes, e.g. Mitragyna ciliata and Parinari excelsa (Fig. 18) with a rich epiphytic flora often give the impression of suffering from 'epiphytosis' as described by Ruinen. The 'preference' of certain epiphytes for a substrate of young bark or living tissues, as reported by R uinen and Furman, should be reflected in the distribution pattern. Species with such preferences would have their main location in the outermost parts of the crown, on the youngest branches and twigs. Only one species, Bolusiella talbotii, shows such a distribution pattern (Fig. 78). There are, however, certain species of orchids that seldom appear on the tall trees, but seem to prefer younger ones and even shrubs. Such habitats are found around creeks and small rivers, or in 'farmlands'. Five species are ±restricted to these habitats: Angraecum classensii, Diaphananthe densiflora, D. rutila, Eurychone rothschildiana and Rhipidoglossum paucifolium. The leafless orchids Brief observations of the leafless orchid Microcoelia exilis Lindl., (Fig. 93), in Tanzania may contribute to the picture of the relationship between epiphyte and phorophyte. Along the Great Ruaha river in the vicinity of Kidatu at 400 m altitude the Microcoelia plants were very common on certain trees in the riverine forest. They generally occurred on the topmost branches in very exposed positions, and on twigs or branches of Fig. 93. Microcoelia exilis. The young roots grow horizontally and freely probably to increase photosynthesis and water uptake. Kidatu 400 m, Tanzania. Fig. 94. Microcoelia exilis (see arrow) in a typical habitat. Kidatu 400 m, Tanzania. small trees (Fig. 94). Very frequently the section of the branch on which the orchid occurred was dead or dying. Morris ( 1970:88) reports that Microcoelia exilis occurs "mainly on smooth barked trees and... mainly on the outer branches". Several species of Microcoelia are reported to grow on the outermost twigs or thin branches of large trees, or amongst bushes and young trees (Stew art 1973 : ). Leafless orchids of the genus Taeniophyllum were observed to cause deficiency symptoms in the phorophyte (Ruinen 1953: 105) and were.preferably attached to the living epidermis of the younger branches, twigs or stems. Taeniophyllum shows optimum growth at surprisingly low light intensities; 1/8-1/5 of the outside light (Wiesner 1897). This may indicate that it is not primarily the need of light that is responsible for its occurrence in the outermost

101 94 Dick Johansson Fig. 95. Records of Microcoelia species in West Africa. (From F.W.T.A. 3 (1) 1968.) parts of the branches. It has generally been assumed that the photosynthesis taking place in the roots of the leafless orchids is sufficient for the needs of the plant (Dycus & Knudson 1957). However, there seems to be no experimental proof of this assumption. The rate of photosynthesis in roots of orchids with green leaves (Erickson 1957, Dycus & Knudson 19 57) clearly shows that these roots do not even produce material that can support their own respiration. Difficulties for leafless orchids growing on dead substrate (Kerr 1972:307) (Teuscher 1972:497) or when transplanted (Stewart, 1970:90, 1973:803) can be used as argument that these orchids to a certain extent are dependent on living tissues. The reduction of leaves that occur in several genera of orchids throughout the world has generally been considered to be an adaptation for preventing water losses through the leaves (Kerr 1972:307, Teuscher 1972:497). If one looks upon the distribution of the species among e.g. the West African leafless orchid genus Microcoelia Lindl., they all appear in areas with considerable amounts of rain and with such minor climatic disadvantages for epiphytes that a very large number of leaf carrying epiphytic orchids with green leaves occur in the very same area (Fig. 9 5). The possibility that the leaves have become obsolete due to a partly parasitic life, should be carefully examined. A eta phytogeogr. suec. 59

102 V. Environmental influence Environmental influences can be referred to three main groups: climatic factors, substrate and biotic factors. Although environmental influences result from a combination of these factors, they will be examined separately. Their possible combined effect will be considered later (Chapter VI). Climate Macroclimate The large altitudinal differences that exist in the investigated area will naturally give rise to a number of different macroclimates. For reasons of simplicity the epiphyte flora of the highest parts ( m) will be compared with the one occurring at lower altitudes ( ). Comparisons will also be made with the epiphytic flora at altitudes higher than those in the investigated area, as observed on the high mountains in East Africa. From Tanzania, the epiphytic flora in dry environments will exemplify climatic influences not represented in the investigated area. Nimba Mountains The epiphytic flora in the highest parts of the Nimba Mountains has few similarities to the one at lower altitudes. The abundance of mosses, lichens, and pteridophytes is very obvious (Fig. 96). Several species of pteridophytes and orchids are ± restricted to the higher altitudes e.g.: Elaphoglossum chevalieri, Lycopodium mildbraedii, Xiphopteris oosora and X. villosissima, Bulbophyllum bifarium, B. inflatum, B. scariosum, Podangis dactyloceras, Polystachya dalzielii, P. leonensis, Rangae"ris brachyceras and Tridactyle tridactylites. Few species from lower altitudes are present, exceptions being Asplenium dregeanum and Medinilla mannii. The proportion between the number of species of epiphytic pteridophytes and orchids respectively is also altered with altitude (Table 35). East African Mountains During a brief study tour to several of the high East African mountains similar changes were observed in the composition of the epiphytic flora. On Mount Kenya, the trees near the forest boundary (at approximately 3200 m) were devoid of orchids but ex- Table 35. Number of epiphytic pteridophyte and orchid species in the foothills ( m) and at the crest ( m) of the Nimba Range. Altitude (m) Pterido Orchids Pteridophytes: phytes orchids Fig. 96. Parinari excelsa densely overgrown by epiphytes. Nimba Range, 1350 m :3 1:1

103 96 Dick Johansson Table 36. Epiphytes recorded in the Kiwira forest, Mt Rungwe 2200 m, Tanzania. Pteridophytes Arthropteris monocarpa Asplenium aethiopicum Asplenium barteri Asplenium geppii Asplenium monanthes L. Mant. Asplenium rutifolium (Berg.) Kunze var. bipinnatum (Forsk.) Schelpe Asplenium theciferum (Kunth) Mett. var. concinnum (Schrad.) Schelpe Asplenium erectum Bory var. usambarense (Hieron.) Schelpe Drynaria volkensii Hieron. Loxogramme lanceolata Lycopodium ophioglossoides Lam. Oleandra distenta Pleopeltis excavata (Bory) Sledge Pleopeltis macrocarpa (Bory) Kaulf. Orchids Bulbophyllum stolzii Schltr. Polystachya zambesiaca Rolfe Stolzia nyassana Schltr. Other vascular epiphytes Peperomia tetraphylla (Forst.) Hook. & Am. Fig. 97. Moss-covered branches of Hagenia abyssinica (Bruce) J.F. Gmel. (Rosaceae). Mt Kenya 3100 m, Kenya. hibited a few pteridophytes, e.g.: Asplenium kassnerii Hieron., Xiphopteris flabelliformis (Poir.) Schelpe and Pleopeltis excavata (Bory) Sledge (Fig. 97). Pteridophyte nomenclature follow Schelpe At 3000 m in the bamboo zone a small Polystachya sp. (probably P. campyloglossa Rolfe), was observed, and at m several species of orchids were present such as Tridactyle scottelii (Rendle) Schltr., Polystachya cultriformis (Thou.) "Spreng., and P. campyloglossa. On the eastern slope of Mount Meru in Tanzania, at m altitude, only one orchid, Polystachya campyloglossa, was observed. However, several pteridophytes, e.g. Asplenium aethiopicum, A. friesiorum C. Chr. and A. loxoscapoides Bak. were abundant. At 2500 m the pteridophytes were very abundant, e.g. Asplenium aethiopicum, Pleopeltis macrocarpa (Willd.) Kaulf., and Elaphoglossum acrostichoides (Hook. & Grev.) Schelpe. Only two orchid species were observed: Polystachya nigresce_ns Rendle and Ypsilopus sp. At 1950 m several orchids were common, e.g. Bulbophyllum spp., Polystachya campyloglossa, P. cultriformis, Tridactyle spp. Among the pteridophytes Drynaria volkensii Hieron. and Pleopeltis macrocarpa (Bory) Kaulf. were noticed. At 2250 m altitude in the Kiwira forest, at Mount Rungwe in southern Tanzania, the ratio between the species of orchids and pteridophytes was roughly one to five (Table 36). At lower altitudes as in the Usambara Mountains in Tanzania the number of orchid species outnumber the pteridophytes. At Amani, 950 m, 14 species of orchids and 12 species of pteridophytes were counted on one Parinari tree (Table 3 7). On another tree at the same place 11 orchids and 6 pteridophytes were observed. Epiphytes disappear, according to Tixier ( 1966:21) in tropical humid montane forests, at 3500 m in the Himalayas and Africa, and at 4000 m in the Columbian Andees and maybe in New Guinea. From Tanzania Moreau (1943:8) reports: "On the whole, epiphytic orchids seem most plentiful, in both individuals and species, between 3000 ft and 5000 ft

104 Ecology of vascular epiphytes in West African rain fo rest 97 Table 37. Occurrence of epiphytes in different sections of a 32 m tall Parinari excelsa, Amani 950 m, Usambara Mts, Tanzania. I No epiphytes ll Asplenium nidus L. Ill Pteridophytes Asplenium pellucidum Lam. subsp. pseudoporrectium (Hieron.) Schelpe Asplenium megalura Drynaria volkensii Elaphoglossum acrostichoides (Hook. & Grev.) Schelpe Elaphoglossum lastii (Bak.) C. Chr. Lycopodium warneckei Microgramma owariensis Oleandra distenta Vittaria ensiformis Swartz Fig. 98. Simplified drawing showing the epiphytes utilizing the humus held by the root system of Asplenium theciferum on a Nuxia congesta R.Br. (Loganiaceae). Ngong Hills 2400 m, Kenya. (A) Asplenium theciferum, (B) Elaphoglossum macrocarpum, (C) Polystachya campyloglossa, (D) Stolzia repens, (E) Peperomia sthulmannii. in rain forest... Above 5000 ft in Usambara, species became less numerous again with the genus Polystachya predominating." Possible influences of altitude The effect of the altitude on the epiphytes has been compared with either the water balance, e.g. drought correlated to low temperatures (Went 1940:94, Tixier 1966 :36) or the temperature. The lower the temperature (Table 2) the higher the relative humidity (Fig. 9) and the presence of local cloud systems or mist, at the highest parts of the Nimba Range (Fig. 11), will naturally influence the evapotranspiration and favour less drought resistant species such as filmy ferns, and certain pteridophytes. Mosses and lichens are also favoured by the higher light intensities that exist at all levels in the more open forest type at the crest of the range. Orchids Ancistrorhynchus refractus Kraenzl. Bulbophyllum plathyrachis Schltr. Cirrhopetalum umbellatum (Forst.f.) Hook. & Arn. Oberonia disticha (Lam.) Schltr. Polystachya adansoniae Rangaeris muscicola Tridactyle anthomaniaca Tridactyle bicaudata IV Pteridophytes Drynaria volkensii Microgramma owariensis Orchids Ancistrorhynchus refractus Kraenzl. Bulbophyllum bequaertii De Wild Bulbophyllum encephalodes Summerh. Bulbophyllum plathyrachis Diaphananthe subsimplex Summerh. Polystachya adansoniae Tridactyle teretifolia Schltr. Other vascular epiphytes Rhipsalis baccifera V Orchids Bolusiella iridifolia (Rolfe) Schltr. Tridactyle anthomaniaca Temperature influence on the occurrence of orchids has been stressed by Rupp (1969: 1): "The epiphytes reach their greatest development in the tropics, decreasing in numbers towards cooler Acta phytogeogr. SUfi?C. 59

105 98 Dick Johansson regions. This fact is well illustrated in Eastern Australia, where Queensland has approximately 100 known species of epiphytes, New South Wales 52, Victoria 5, and Tasmania 2." There are diverging opinions about the ability of orchids to survive frost. Piers ( 1968 :5) states that epiphytic orchids can not survive frost, while Stewart (1970:54) reports that Bo/usiella iridifolia "may even withstand frost on the coldest nights of the year". Generally speaking, it is hard to believe that the pteridophytes, which as a group are poorly adapted to desiccation, would dominate over the epiphytic orchids with their advanced technique to survive dry periods, if drought was a main limiting factor on the occurrence of epiphytes at higher altitudes. Kidatu A thorough study of the epiphytes in the Kidatu area (1 40' S, 36 59' E) in Tanzania was performed in April-June The slopes of the Great Ruaha River Valley, east of Kidatu, are covered with patches of forest. The annual rainfall is around mm (Atlas of Tanzania 1967:6), with a long dry season of 4-5 months. Close to the stream bed a riverine forest occur with a rather large number of tree-forming species, e.g. Burkea africana Hook., Cassia sp., Combretum sp., Dip/orynchus condy/ocarpon (Miill. Arg.) Pichon, Ficus sycomorus L., Lonchocarpus bussei Harms, Markhamia obtusifolia (Baker) Sprague, Milletia bussei Harms, Piliostigma thonningii (Schumach.) Milne-Redhead, Pterocarpus sp., Stereospermum kunthianum Cham., Sterculia quinqueloba Schum., Xeroderris stuhlmannii (Taub.) Medonca & E.P. Sousa, Vitex doniana Sweet. A total of eight species of epiphytes were recorded in the riverine forest: Aiirangis flabellifolia Rchb. f., Ai/rangis kotschyana (Rchb. f.) Schltr., Bu/bophyllum sp., Ansel/ia gigantea Rchb. f. var. nilotica (Baker) Summerh., Cyrtorchis arcuata subsp. variabilis and C. arcuata subsp. whytei (Rolfe) Summerh., Microcoe/ia exilis Lindl., Polystachya tessallata. The only epiphytic fern was Phymatodes sco/opendria (one 'stand'), which was partly growing on some wet rocks in a shady habitat. Trees along two parallel strips 50 m long and 10 m wide were examined ('distance' method) (Table 38). The first strip was situated in the riparian forest Table 38. Occurrence of epiphytes in two different forest types. (Trees < 5 m are excluded). Great Ruaha River 400 m, Kidatu, Tanzania. Habitat Riparian fo rest Wooded grassland No. of trees %of trees Max. no. of examined with epiphytes species on a single tree 10 m from the shore of the Great Ruaha River, parallel to the river. The second strip was 50 m away from the river 10 m higher on the slope in a grassland with scattered trees (wooded grassland). The two species that occurred in the riparian forest were Cyrtorchis arcuata subsp. variabilis and Microcoelia exilis, which were also the only two common species in this area. In the wooded m 2 o Aerangis flabellifolia Microcoelia exilis l Evaporation Fig. 99. Simplified drawing showing the distribution of epiphytes on a Combretum tree close to the Great Ruaha River. Kidatu 390 m, Tanzania.

106 Ecology of vascular epiphytes in West African rain fo rest 99 Fig Brachystegia woodland ('Miombo'). Makumbako 1900 m, Tanzania. grassland Aiirangis flabellifolia was the only species with a total of three 'stands'. The relative 'richness' of epiphytes in the riparian forest can probably be correlated to a favourable climatic effect which was also indicated by a kind of 'reversed' distribution pattern of the epiphytes on several phorophytes (Fig. 99). Growing sites close to water are according to Teuscher (1972:497) a general habitat for leafless orchids. Stewart (1973), however, has pointed out that a number of Microcoelia species are adapted to different habitats. Makumbako In the Southern Highland, near Makumbako (8"0 56' S, 34 52' E) at approximately 1900 m altitude, large areas are covered with a Brachystegia woodland (so-called 'Miombo', Fig. 100). The yearly rainfall is mm (Atlas of Tanzania 1967:6), and the dry season lasts for 5-6 months. Fifty trees selected at random, four meters or higher, were examined for epiphytes. Two orchid species were observed, Tridactyle tricuspis (Bolus) Schltr. (Fig. 101), and a Polystachya sp. of which only the old inflorescences Table 39. Occurrence and abundance of epiphytes on 50 trees in a Brachystegia woodland ('miombo'). (Trees < 4 m are excluded.) Classes of abundance explained in the text. Makumbako 1900 m, Tanzania. Species % of trees Abundance Tridactyle sp. + Polystachya sp. I 00.0 Tridactyle tricuspis (alone) 98.0 Polystachya sp. (alone) 98.0 with epiph Fig. I 0 I. Tridactyle tricuspis. Makumbako I900 m, Tanzania. and pseudobulbs remained. The occurrence and total number of each species were estimated (Table 39). Three frequences of abundance were used: (1) less than five 'stands', (2) 5-25 'stands', (3) more than 25 'stands'. The Polystachya species were very hard to discover when the old inflorescences were absent. The leafless pseudobulbs were more or less covered with lichens. Therefore, the frequence of the Polystachya species are probably too low in this estimation. Every tree examined had at least one species of epiphyte. Also surprising is the very high number of individuals, particularly Tridactyle tricuspis. Sixtyfour per cent of the trees had 5-25 'stands' of this species. The presence of such a large number of individuals indicates that they are well adapted to this environment. The climatic influence in these two areas in Tanzania obviously limits the number of epiphytic species although the abundance of certain species is surprising. Brief observations in even drier areas of Tanzania in the Iringa and Dodoma districts ( mm yearly rainfall) revealed that Ansellia gigantea var. nilotica (Fig. 102) was locally rather common, often on Adansonia digitata L. and Hyphaene thebacia (L.) Mart. In those very dry areas two species of the

107 100 Dick Johansson Fig A nsellia gigantea. A large orchid of rather dry areas in East Africa. Kidatu 400 m. family Crassulaceae, Kalanchoe /anceo/ata (Forsk.) Pers., and K. pilosa Bak., occur as epiphytes. The latter species has also been recorded (J.B. Gillett, K) as an epiphyte in the Marsabit area, Kenya (780 mm yearly rainfall). Rainfall importance The rainfall may not only be of importance for the water economy of the epiphytes but also serve as a source of nutrients. It has been clearly shown that rainfall nutrients play an important part in the nutrient cycle of ecosystems on oligotropic sites (AUen et al. 1968:497). Analyses of the nutritional content of rainwater are available from two countries in West Africa (Table 40). Jones (1960:432) remarks that his nitrogen, potassium and sodium figures are the highest so far recorded in rainwater. The origin of the nutrients in rainwater has been subject to various explanations. Commenting on his Table 40. Annual total nutrients (kg/ha) in rain according to records from West Africa (from Gore 1968). Location Rainfall lnorg. p Na K Ca Mg (mm) N N. Nigeria (Jones, 1960) Gambia (Thornton, 1965) Yundum Jenoi Yoroberi K figures, Jones states: "generally the figures to date point to the ocean as the main source of rainwater nutrients" since "the low nitrate figures eliminate the possibility of large contributions from dust and electric storms". In Uganda, Visser (1964:35) observed that the heavier the shower the more nitrate-n was precipitated, and therefore states that storms preceding heavy rains take a lot of dust into the atmosphere from which NO) and other nutrients are later washed. A similar view is presented by Thornton ( 1965: I 025) who found in Gambia that the highest values for potassium and calcium were obtained at the beginning of the rains which indicate that the elements are either washed from or fall in the form of dust present in the atmosphere. No matter what origin the nutrients in the rainwater should represent, a valuable addition to the nutrients of the substrate is made. Microclimate The microclimate in a rain forest is of course dependent on the structure and density of the vegetation and is thus very complex. There is a ±continuous vertical climatic gradient from the ground to the highest treetops. Since none of the strata are uniform in density there are also variations in microclimate from place to place at the same horizontal level. Furthermore, the microclimate in the crowns will vary according to the species and age of the tree. In a study like this the largest interest is connected with the variation of the microclimate in various strata of the forest, but no such investigation has been possible to perform. For reasons easy to understand there are in fact few and limited reports of the microclimate in the higher strata of the rain forest. From the Shasha Forest Reserve in Southern Nigeria Evans (1939) has published results of investigations at the ground level and at 24 m level. A more detailed study has been carried out in the lowland rain forest at Banco in the Southern Ivory Coast by Cachan (1963). By help of a 46 m high tower, recordings from four different levels were obtained. The results from these investigations quoted here cannot be simply transferred to the Nimba area. However, some of the general observations can probably also be applied to the situation within the forests in Nimba.

108 Ecology of vascular epiphytes in West African rain fo rest 101 Table 41. Humidity of the air during dry and wet seasons at..... /'',,,_ / \ I \ /. \ \\,, D m " &-11 " " two levels in an Ivory Coast rain forest (from Cachan 1963). Level Dry period Wet period Minimum relative humidity 46 m % % 1 m % % Saturation deficit 46 m mm 6-12 mm 1 m 6-10 mm 0-4 mm - - :-:':'::. 700 goo oo oo Hours with rei. humidity 46 m hrs 8-12 hrs less than 95 % 1m hrs 0-2hrs Fig Daily temperature differences between different levels in a tropical rain forest (from Cachan 1963). Temperature Evans found that the temperature showed a smaller range of variation in the undergrowth than at the upper levels of the forest. In the dry season the maximum temperature is about the same. In the wet season the differences are much more accentuated and the minimum temperatures in the undergrowth are in every case from one to two degrees higher than in the treetops. The vertical temperature gradient shows, in the middle of the day, a fairly steady decrease from the canopy down to the undergrowth. The temperature is 2-3 degrees higher at 24 m than at ground level. At nighttime the undergrowth at 0. 7 m was always warmer than the air 24 m above the ground. Cachan noted a similar temperature pattern in the Ivory Coast. The daily variations of the differences between the temperature at four levels is shown in Fig Humidity The humidity of the air can be expressed in three ways : relative humidity, saturation deficit and vapour pressure. In general, the minimum relative humidity and the maximum temperature are simultaneous, the daily variation of these elements are in versed. The variation of the saturation deficit is in versed to that of the relative humidity, while the vapour pressure shows a double, daily oscillation with a maximum in the morning and also in the afternoon (Cachan 1963:152). The humidity of the air determined from the relative humidity, the saturation deficit, and the duration of periods with a relative humidity of less than 95 %, are usually identical between the 46 m level on a humid day and the 1 m level on a dry day (Cachan 1963: 152). The following characteristics were observed for a dry resp. a wet period (Table 41). The rate of evaporation at various levels in a rain forest, given as a percentage of the value obtained at 46 m level (above the canopy), showed a steady decrease from the canopy level towards the ground. At 26 m the value was 58 %, at 11 m 35 %, and at 1 m 21 % of that at 46 m (Cachan 1963: 149). Light intensities In the undergrowth The instrument used was a photoelectric cell of unknown spectral range. The cell itself was connected to a galvanometer with a 3 m long cable. The light cell was placed on top of a 1.3 m high stick, that was pushed into the ground during the recordings. Lower down on the stick two waterlevel instruments were attached to ensure that the stick and the light cell were held in an absolute vertical position at each measuring point. The recording was done along three parallel strips at 5 m distance from each other, at every 5 m of the 100 m long strips. Three recordings during one minute at each recording spot were taken and the median value chosen. The investigation was done at noon on a sunny day at two plots, one at 600 m (Nov. 2, 1969) and another at 1300 m (Nov. 12, 1969) Table 42. The samples from 600 m were Table 42. Light intensities in the undergrowth at two different altitudes, given as a percentage of the light in the open. Altitude 600 m 1300 m No. of records Max Light intensity Min Mean

109 102 Dick Johansson taken in a high forest with the canopy around 40 m above the ground in the Seka Valley. Common species of trees in this forest were: Parinari excelsa, Heritiera uti/is, Calpocalyx aubrevillei and Chidlowia sanguinea. The ground was covered with dead leaves and the herb flora was sparsely represented, e.g.: Selaginella vogelii Spring and Selaginella versicolor Spring. On the lower parts of the trunks a few ferns were noticed, Hymenophyllum kuhnii and Asplenium barteri. At 1300 m the samples were taken at the crest of the main ridge 300 m SW of the point where the borders of Liberia, Guinea and the Ivory Coast meet. The forest in this locality almost exclusively consisted of Parinari excelsa with a somewhat broken canopy at m level above the ground which was irregularly covered with herbs. The high light intensities in the montane forest is remarkable, but judging from the abundance of plants on the ground it was not totally unexpected. In a montane forest in Ecuador, Whitmore (1968 :238) found that the canopy was more transparent than in a lowland forest. Particular interest has been paid to the illumination of the undergrowth and the effect of the sunflecks on the forest floor, e.g. Evans (1939) in Nigeria, Gusinde & Lauscher (1941) in Congo, Eidmann (1941) on Fernando Po, Evans et al and Cachan (1963) in the Ivory Coast. The shade illumination was found by all of them to be 1 % or less of the outside light. The light intensity in the sunflecks in British Guiana varied between 10.4 and 72 % (Carter 1934). The spectral composition of the light reaching the forest floor as examined by Evans (1939) showed approximately 40 % portion of the wave-lengths above 7000 A (infra-red light). Similar observations have been reported from Puerto Rico (Johnson & Atwood 1970). This indicates a considerable increase in the transmission of the forest canopy just beyond the red end of the visible spectrum. The effect of this portion of light on the plants is unknown but it can probably not be used in the photosynthesis, since it is outside the range of chlorophyll's absorption. As the forest became denser a decrease in the proportion of blue light was also noticed. At the growing sites of the epiphytes The same photoelectric cell as described earlier was used. The recording equipment stood on the ground and was managed by an assistant. The recording was performed by holding the cell at the growing site of the plant to be investigated. To reach the plants growing in more inaccessible places, the light cell was attached to a four m long aluminium pipe. At the end of the pipe, where the light cell was attached at a 90-degree angle towards the pipe, a V -shaped metal piece was connected to a ball bearing on the pipe. When the metal piece with its open end was held against the substrate, the whole pipe could be turned around on its axis, and thus moving the light cell at the same time. By placing the light cell at the actual growing site of the epiphyte, and then turning it, the maximum light intensity was found. The tree chosen was a Parinari excelsa growing in a typical section of the forest that covers the narrow crest of the main ridge at 1300 m altitude from the mark of the three national borders down to the mining area. The canopy in this single dominant Parinari forest was at m above the ground and partly open. There were a few trees and shrubs of smaller dimensions. e.g. Ochna membranacea Oliv., reaching up to the lower parts of the crowns of the emergent trees. The tree investigated had a size of 23 m and a circumference of the trunk at breastheight of 162 cm and was heavily branched, with the first ramification starting 3.5 m above the ground. The foliage was concentrated to the outermost branches which made movements easier in the central part of the crown. At the basal part of the trunk the cover of epiphytic mosses and filmy ferns was 100 %. Higher up on the trunk (1-3.5 m) the epiphytes were more or less concentrated to one side (S), with the plants appearing in small patches with clean bark surface in betwe(;!n. In the basal parts of the crown Tridactyle tridactylites formed dense, untidy 'stands'. In the central part of the branches the mosses e.g. Porothamnion hildebrandtii (C.M.) Fleisch, were very abundant, forming large cushions. In the apical part of the branches the lichen cover was pronounced especially on the twigs, where an Usnea sp. with hanging growth habit was noticed. Bulbophyllum scariosum and Polystachya dalzielii were also abundant. A total of 15 species of epiphytes were growing on the tree, 7 pteridophytes, 5 orchids and 3 other vascular epiphytes. Thus the pteridophyte/orchid ratio was 1.4 :1. A total of 119 recordings, which were estimated to cover 80 % of the plants present, were performed during a 3 hours period in the mid-

110 Ecology of vascular epiphytes in West African rain fo rest 103 Table 43. Light intensities as a percentage of the light in the open at the growing sites of epiphytes on a Parinari excelsa. Nimba Ridge, 1300 m. Epiphytes No. of Light intensity between maximum and minimum intensities should be noted with caution, since sun-flecks with a very short duration may be responsible for the high figures. I+ 11 Asplenium dregeanum Begonia rubro-marginata Bulbophyllum inflatum Elaphoglossum chevalieri Medinilla mannii Peperomia sp. Polystachya leonensis Ill Asplenium dregeanum Lycopodium mildbraedii Medinilla mannii Peperomia sp. Tridactyle tridactylites IV Asplenium aethiopicum Asplenium megalura Bulbophyllum scariosum Begonia rubro-marginata Elaphoglossum isabelense Polystachya dalzielii Tridactyle tridactylites Xiphopteris vilosissima V Bulbophyllum scariosum Polystachya dalzielii Usnea sp. records Mean Max. - Min At various levels above the ground The general knowledge of light conditions in the crowns of the trees in the tropics is very scanty. The need for the erection of large structures to reach the upper parts of, or preferably above, the canopy has naturally been difficult to overcome. There are actually only a few such investigations (Allee 1926, Dirmhirn 1961 and Cachan 1963). The decrease in the light intensity from the canopy towards the ground is by no means a gradual process, but rather abrupt changes occurring at various levels, depending on the structure of the forest (Richards 1939:30). Cachan (1963:93) reports on the vertical variation of the light intensity from a tropical rain forest in the Ivory Coast. The emergent trees in this forest reach a height of little more than 40 m, e.g. Combretodendron africanum, Piptadeniastrum africanum, Guarea thomsonii Sprague & Hutch. and Turraeanthus africanus (Welw. ex DC.) Pellegr. The light intensity above the canopy varies continuously, since the sky is more or less hazy. Values above 1 OOJ,OOO Lux were exceeded during rather short periods. The daily variation in the light intensity at 44 m and 33 m above the ground, is presented in Fig. I 04. Wide variation in the light intensity occurs in the middle of the day at 46 m, where the daily die of the day. An additional 7 recordings of the light intensities at the more exposed positions of the typical Usnea lichens were also included for comparison (Table 43). It is interesting to note that the arbitrary division of the trees into 5 sections that has been used throughout this study, was in this tree not correlated to the light intensities (Table 44). No marked difference in the light intensities could be found between the basal and middle parts of the branches. The very wide variation in the values Table 44. Light intensities in the five sections of a Parinari excelsa at 1300 m. Based on the mean light intensity in each section (Table 43) LUX I J 33rn (\ \ Section Light intensity I + ll 14.9 Ill IV V goo IJOO Fig Variations in daily light intensity above the canopy (46 m above the ground) and at 33 m in a tropical rain forest in the Ivory Coast (from Cachan 1963). 1700

111 104 Dick Johansson Fig Daily variation of light intensity measured by a light cell at the growing site of a Diaphananthe pellucida four meters above the ground (see text). average was 38,000 Lux. The average light intensity at 33 m level is less than 10% ( ,000 Lux) of the intensity above the canopy. Observe that in such a short vertical distance as 11 m a 90 % reduction of the light intensity has already taken place. At ground level, the light intensity never reached above 1 % of the light above the canopy. Daily variations in light intensity Through a special 'writing unit' the daily continuous changes in light intensity were recorded. The same light cell as previously described was simply connected to the 'writing unit' through a cable. The light cell was placed at the growing site of the epiphyte to be investigated pointing in the direction of the supposed main light influx, which in most cases meant a vertical direction (Fig. 1 05). The graphs obtained with this equipment should only be compared with each other, since the spectral range of the light cell was unknown. No extra instruments that could be used for simultaneous recordings in the open were available. Therefore, all the curves shown are from different days, which of course include a source of error. To reduce the error the comparisons shown are all taken from cloudfree days. The seasonal effects must also be considered, since the recordings are from different times of the year with different solstices. The aim of these recordings was to find out if there were differences between various species of epiphytes in their light climates over a longer period, and to get an idea of the frequence and duration of direct light (sun-flecks). The light intensities of three species of epiphytes, Diaphananthe pellucida, Vanilla crenulata, A rthropteris monocarpa, from the lowest parts of a high forest (Seka Valley 600 m) compared with the light outside the forest is given in Fig The Diaphananthe specimen was growing on a liana, four meters above the ground (Fig. I 05), and the Vanilla vine on the rotten stump of a large tree at about 1.5 meters height, while the Arthropteris monocarpa specimen occupied the basal part of the trunk of a large tree. The daily variation of the light intensity in the open on a clear day shows a fairly even rise and decline with the maximum in the middle of the day. 1 In the open 2 Diaphananthe pellucida 3 Vanilla crenulata 4 Arthropteris monocarpa 06.oo 12.oo 18_00 Fig Daily variations in light intensity at the growing site of a Bulbophyllum inflatum. Nimba Range 1300 m.

112 Ecology of vascular epiphytes in West African rain fo rest Fig Daily variations in light intensity at the growing site of a Bulbophyllum injlatum. Nimba Range 1300 m The minor variations that can be observed throughout the day are probably caused by haze. The more gentle peaks in the curve for Diaphananthe pellucida probably indicate that this species recieves a more indirect type of light. The series of distinct peaks with a very short duration that occur between on the Vanilla curve is a result of direct sunlight that has been able to penetrate down to this level. In denser shade closer to the ground the penetration of direct light is less likely. The light level tends to be more uniform throughout the day as can be seen for Arthropteris monocarpa. In the montane forest the light regularly penetrates the lower parts of the vegetation. The curves for oo Bulbophyllum inflatum, growing on a trunk I.5 m above the ground at 1300 m altitude, give the variation in light intensities for the orchid which grows in the most shady habitat of all the orchids in the Nimba area (Fig. I 07). These two curves can also serve as an example of the 'micro light climate' that probably is of great importance for the epiphytes. Note the similarity between the two curves of March 18 and 20, 1970 (March 19 was a cloudy and rainy day) when the light that was registered reached the plant between For many plants that live in a superficially dark environment these short periods of higher light intensities may be of critical importance in their survival. It may also influence the occurrence of small groups of several species that com- 1 Asplenium mega lura 2 Asplenium africanum 3 Asplenium barteri oo 18.oo 1 Polystachya pa niculata 2 Polystachya laxiflora 3 Polystachya ramulosa Fig Daily variations in light intensity at the growing sites of three pteridophyte species, (B) three orchid species. Nimba Range 600 m. (A) 06.oo 12.oo 18.00

113 106 Dick Johansson monly are found in patches of small and restricted range. To find out if there are any correlation between the observed stratification of the epiphytes and the light -intensities, three species in each of the genera Asplenium and Polystachya were chosen for study. One species in each genera represented a specific level in the rain forest. The lowest level (section I) was represented by Asplenium barteri and Polystachya ramulosa, the intermediate level (11) of Asplenium africanum and Polystachya laxiflora, and the crown stratum (Ill + IV) of Asplenium megalura and Polystachya paniculata. Two 'different phorophytes that each carried these three plants of the same genus were selected for the study. The light cell was then applied in the same way as earlier described. The result is presented in Fig The differences in light intensities as observed for certain species with the aid of recording instruments (short or long period recordings) seem to confirm the estimations made in the field. A limitation to one or rarely two of the particular light groups that are recognized was common among the species in all major groups of epiphytes (Fig. 109). The majority of pteridophytes, however, occur in diffuse light while the orchids are more evenly divided between habitats with diffuse or bright light (Table 46). 100'/o 50 Asplenium barteri i Brachyc orythis ka l breyerii Calvoa monticola Oleandra distenta J. Polystachya laxiflora Begonia rubromarginata Platycerium angolense Bolusiella ta lbotii Rhipsalis baccife ra Substrate PROPERTIES OF THE SUBSTRATE AND THEIR INFLUENCE ON THE EPIPHYTES The bark The properties of the bark affect the epiphytes in several ways, e.g. through (I) relief and growth habit (2) structure or porosity, and (3) chemical composition. When comparing the relief of bark between various species of trees one must remember that the bark by no means is uniform over the entire tree but varies with age. (I) The importance of the bark's relief can be suspected to be connected with the establishment of the seedlings. A deeply fissured bark could provide both a suitable microclimate for the germination of seeds and spores, and also more easily prevent the young seedlings from being washed away. In the Nimba area a clear correlation has been established between the size of the tree (which in most Fig Records of epiphytes distributed between the different light classes (from Table 27, Brachycorythis kalbreyeri from Table 29). (A) heavy shade, (B) open shade, (C) full sun. cases is proportional to the age and roughness of the bark) and the number of epiphytic species (Fig. 69). On trees m in size, e.g. Lophira a lata, Triplochiton scleroxylon, Ceiba pentandra, there are seldom any epiphytes, although these species when older are very rich in epiphytes. This refers to trees of the primary forest as well as those in more open environments. However, several species of epiphytes seem to have a marked 'preference' for smooth bark surfaces, e.g. Ancistrorhynchus cephalotes (Fig. 1 10), Angraecum podochiloides, and Polystachya affinis. From other parts of the world observations of a rich epiphytic flora on trees with rough bark are frequent (Oliver 1930:14, Eggeling 1947:56). Went ( 1940:9 5) observed that phorophytes with a poor

114 Ecology of vascular epiphytes in West African rain fo rest 107 palms they readily attach themselves and seem to thrive. Sulit (1950:8) even states that the 'palm trees' are especially suitable for growing orchids on. Fig Ancistrorhynchus cephalotes (lower down) and Graphorchis lurida (above) are two epiphytes which often occur on bark without humus deposits. Seka Valley 700 m. epiphytic flora frequently were found among species with smooth or hard bark, and fast growing species. Boyer (1964) concluded that it probably was the smooth nature of the bark that was the cause of the absence of Platycerium ferns on Musanga Smithii. In the Nimba area trees with a defoliating b,ark (e.g. Distemonanthus benthamianus), seem to be very difficult for the epiphytes to colonize. This has also been observed elsewhere (Dudgeon 1923, Pessin 1925:34, Oliver 1930:14, Went 1940:95, Rupp 1969 :XI). Voorhoeve (1965 :200), however, states that colonization of flaking bark does occur, and in some cases the epiphytes even prevent the shedding of the bark, e.g. on Gilbertiodendron preussii. The absence of epiphytlc orchids on the oil palm is hard to correlate to any morphological characteristics of the phorophyte, but may possible be attributed to germination difficulties of the orchid seeds. When full-grown epiphytic orchids are transplanted on oil (2) The structure or porosity of the bark will naturally effect its water capacity. The absorbation ability of the bark varies naturally from tree to tree, depending on age, species and inclination (Freise 1936:303, Voth 1939). The subsequent water content of the bark is also dependent on the amount and type of rainfall, and the rate of evaporation, and thus varies with weather conditions and the season. Another fact to consider is that water does not flow evenly over the bark surface but is concentrated into so-called rain tracks or drainage channels (Richards 1964: 118, Yarranton 1967}. The water content of the bark is thus dependent on a large number of variable factors. Measurements must therefore be carried out during a long period and involve samples from different sections of the trees. This study does not include measurements of the water capacity or the water content of the bark. Water capacity of bark have been investigated in various parts of the world with different methods. The results, however, show large variation between trees of the same species (Bar km an 19 58: ). (3) No analyses of the chemical composition of bark have been undertaken, but ph measurements of bark samples in water suspension were performed. Bark ph and the epiphytic flora The samples were taken from representative areas in the vicinity of epiphytes in various sections of the phorophyte. They were all taken from trees felled the same day, except for a living Parinari excelsa tree at 1300 m altitude which was climbed. The bark pieces used in the survey had a size of 6-10 cm2 They were pulverized and dried in 24 hrs in 55 % relative humidity. Distilled water twice the dry weight of the sample was added. The measurements were performed 24 hrs later on an electric ph-instrument. The sampling procedure, e.g. cutting a piece of bark, involves a great deal of subjectivity, since the actual choice of bark pieces may influence the result. It was found that dead, corky pieces gave higher ph values than living bark, a fact that is well known. There are also difficulties in utilizing a completely identical method of sampling due to the variation in the bark morphology. Some species have a thick easily

115 108 Dick Johansson Fagara tessmannii I 11 Ill IV V Heritiera I 11 Ill.... uti lis IV V Lophira a lata Mitragyna ciliata Parinari excel sa I 11 Ill IV V I 11 Ill IV V I 11 Ill IV V Parinari Ill I excel sa m IV Piptadeniastrum africanum I V I 11 Ill IV V :... 4 I I ph.. :.I.... I.... I.. I.. 11 :i I 6 : 1: I I : I Fig ph in water extracts of bark from different phorophytes. Yekepa. detachable bark while others have a thin flaky, corky or deeply fissured one. Differences in ph value for samples of large and small pieces of bark have also been reported (Sjogren 1961: 1 02). The ph values exhibit a ± significant pattern within the phorophytes (Fig. 111). The lowest values were obtained from the upper part of the main trunk and the outer branches. The ph of the bark has been studied by many authors using various methods. It has been observed that the ph values decrease from the bases of the trees and upward, probably due to decreasing dust content. The ph has also been found to vary according to the time of day (Pessin 1925 :34). Du Rietz ( 1945 : ) distinguishes three groups of bark based on the ph values, 'rikbark' (rich bark) ph 5-7, 'overgimgs-fattigbark' (intermediate bark) ph 4-5 and 'extrem fattigbark' (extremely poor bark) ph <4. When trying to evaluate the influence of the ph value of the bark on the epiphytic flora one should remember that the ph value might have changed since the time when the seedlings were established. The long span from germination to a fully developed plant exemplified by the orchids emphasizes this problem. The epiphytes themselves influence, in a complex and imperfectly known way, the acidity in their environment. This can be done by collecting dust and forming humus, through photosynthesis, by release of lichen acids and exchange of ions (Kolkwitz , Skye 1968: I 07). The acidity also regulates the nitrification since this process is strongly ph depen- 7 dent (Barkman 1958:103). The acidity may influence the germination of spores and seeds, or affect the growth of established plants. Pessin ( 1925 :24 ), however, remarks: "It appears that the acidity or alkalinity of the substratum does not influence the occurrence and distribution of Polypodium polypodioides." Exudates "Orchids seem to dislike trees which exude a latex juice such as most Ficus species and tree Euphorbias." (Piers 1968:4). In the Nimba area several species of phorophytes which exude a latex juice have a rather rich epiphyte flora, e.g. Chlorophora regia, Uapaca guineensis and even the rubber tree, Hevea brasiliensis, while others show an opposite tendency, e.g. the figs. The toxic effect of certain exudates must also be considered. Barkman (1958:134) suspects the 'robin' in the bark of the Robinia tree to be the cause of the poverty of non-vascular epiphytes of this tree. Large differences in the presence of orchids between various species of trees of the genus Quercus were observed by Frei (1973a: ) in a cloud forest in Mexico. Two species in the genus had only a few species of orchids, two. others carried many orchids, and one was never observed with any orchids whatsoever. When analyzed, the bark from the species with many orchids showed no presence of inhibitory substances. The bark from the phorophytes devoid of orchids, contained gallic and egallic acids, which are known to be growth inhibitory substances (hydrolyzable tannins). (See also Frei 1973b: ) Bark from several tropical species of trees e.g. Ficus pumila contain strong growth inhibitors (Bovey & Diaz-Colon 1959:256). The importance of the leaching of growthregulating substances from the vegetation has also been stressed by Tukey Jr (1970:160). Went (1940:90) assumed that the rich epiphytic flora on Castanopsis argentea could be connected to the high amounts of tannin in the water on the bark surface. The excretion of water-soluble substances by the bark or the leaves has seldom been measured. Schweitzer (quoted from Ruinen 1953:151).found that a total leaf surface area of one sq. m of coffea leaves, leached in distilled water during one hour, yielded mg mineral substances, Erythrina

116 Ecology of vascular epiphytes in West African rain fo rest mg, Hevea 55 mg. In many instances sugar could be detected in rainwater dripping from the leaves. Rain wash in a mature forest in Ghana carried the following amounts of nutrients out of the vegetation, in lb/acre: N 11, P 3, K 196, Ca 26, Mg 16 (Greendale & Nye 1964:248). See also Eaton et al. (1973). Ruinen (1953: 151 ) states that germination and settlement of the epiphytes are possible even in a milieu with minimal nutrient value, because of the rich substrate offered by the living tissues and their excretions. An efficient adaptation to intercept leachates from the overhead canopy is shown by certain bromeliads. It has been shown experimentally that metabolites fall in the well (formed by the diverging leaf bases) from which they are absorbed and utilized in growth (Tukey Jr 1970: ). I bris from tr.e phorophyte L J IMtrl transported from the ground by ants and termites L Rainwater Excreta fr:jm a n imals Humus deposits Origin and composition The accumulation of humus starts with the decomposition of the outer layers of the bark. The bark is continuously renewed from within, so that it automatically provides a steady supply of new material for decomposition. This is mainly carried out by fungi, which in many cases are connected to the roots of the epiphytes. To the material from the bark external material is added. Dead leaves, twigs, small branches, etc., from the phorophyte itself can be assumed to form the bulk of the deposits. In this more or less accidental process the growth habit of the phorophyte and structure of its bark are of importance. The root systems of the epiphytes also help to catch debris in the many niches they form. Certain epiphytes play a more active role in the catching of falling debris. Usually a niche between the plant itself and the substrate is formed in which debris from above can be caught, e.g. Drynaria laurentii, Platycerium spp. (Fig. 1 12). The term 'sole epiphytique' has been used by Boyer (I 964) for the humus collected by Platycerium ferns. She is of the opinion that these accumulations of organic material can hardly be compared to the soil in its proper sense. These accumulations have attracted the interest of several authors, e.g. Miehe (I 911), Paulian (1945) and Klinge (I 963). In the Ivory Coast Boy er (1964) found that in the humus of the 'leaf basket' of Platycerium angolense and P. stemaria % of the dry weight was Fig Origin of substrate and nutrients of importance for the epiphytic flora. organic in origin. This can be compared to the soil under the trees containing % of organic matter. I 0-23 % of the material belonged to a fraction less than 2 mm in diam. The rest consisted of living, or dead and more or less decomposed parts of leaves and roots. The accumulation of organic material through wind, animals, and water running along branches and stem amounted to 5- l 0 % of the total weight. The bulk of the organic material was derived from the tissues of the fern itself. The addition of organic material from sources outside the fern was considered to play a minor role in the nutritional supply for this epiphyte. The formation of the humus was slow. It was estimated that it takes 10 years to form a layer of I 0 cm thickness. It was also noticed that the material that was incorporated was only slowly decomposed despite the rich microflora. The external contribution to the assemblage of humus may be small in volume but important in its nutritional effect on the epiphytic flora. Dust carried by the winds may be Jf considerable importance in certain areas. Every year in the winter months the Harmattan winds fill the air with a fine dust in vast regions of West Africa. It is easily observed that trees close to dusty roads often show a

117 110 Dick Jo hansson '/, A A a c Dryna ria laurentii Microsorium punctatum Plathycerium angolense Cs DAYS Fig Water holding capacity of humus from different epiphyte communities, in o/o of the wet weight. luxuriant growth of epiphytes (Thorold 1952:139, Richards 1964: 1 14 ). Ants and termites carry material of inorganic as well as organic origin up into the trees. Termite nests built from earth, and the earth-covered tracks of these insects are common on the trees. Richards ( 1964: Ill) states that the roots of flowering epiphytic plants and ferns are one of the chief nesting places for arboreal ants. Adamson (1943) suggested that certain epiphytes in the rain forest of Trinidad may be at least partly dependent on soil carried up into the trees by termites. In an analysis of the mineral content in the humus from a Platycerium fern in the Nimba Mountains Schnell (1952:58) found that 38 % of the mineral content had a granular size of gritty sand and 68 o/o was of lesser sizes. The mineral particles appeared as grains of quartz, hematite, and loam. Schnell did not elaborate on the origin of the larger sized particles that can hardly be transported by the wind, but it can be mentioned that the earth in this particular region is very rich in hematite. Water holding capacity Pieces of humus of roughly the same volume (1.5 dm3) (100 x 100 x 150 mm) were cut out from a humus deposit in a Drynaria laurentii, a Microsorium punctatum and a Platycerium angolense epiphyte community. Four samples from each type of humus were taken. The pieces were placed in baskets of 'chicken wire' and then saturated with water for 3 hours. The water was allowed to drip off, and when no more water was given off, the weight of the twelve samples were taken. The samples were divided in two groups, one was placed in an air-conditioned room at 55 % relative humidity, the other placed outdoors but prevented from contact with rainwater. The weight of the samples were taken every second day during a 30-day-period. The water holding capacity for the humus is shown in Fig It is obvious that the humus deposits may serve as a water reservoir. The ability of rapid water absorption during a shorter rainfall and the slow release of it is naturally of great importance for the epiphytes. ph of humus deposits Thirteen different humus deposits utilized by epiphytes were examined. The methods used in these determinations are the same as described in the investigation of the bark, i.e. the bark piece has simply been replaced by a piece of humus (50 g dry weight). Rather high ph values were obtained, considerably higher than those of the bark, Table 45. Schnell (1952:58-59) gives the ph in the humus of a Bulbophyllum sp. as 4.8 and for a Listrostachys sp. to 5.7. Boyer (1964) reports the ph of humus from Platycerium stemaria as (6.0 for P. angolense). Correlation between substrate and epiphytic flora Many epiphytes show a high frequence in the recor- Table 45. ph in water extracts from humus deposits with growing epiphytes. Median value of five samples. Phorophyte Section ph Epiph. utilizing the humus Heritiera utilis IV 6.6 Drynaria laurentii Nephrolepis undulata Heritiera utilis V 6.0 Drynaria laurentii Nephrolepis undulata Lophira alata Ill 5.8 Vittaria guineensis Lophira alata IV 7.0 Oleandra distenta fridactyle armeniaca Lophira alata V 6.8 Drynaria laurentii Polystachya polychaete: Parinari excelsa lii 6.0 Oleandra distenta Arthropteris orientalis Parinari excelsa IV 5.6 Drynaria laurentii Microsorium punctatum Parinari excelsa Ill 6.8 Asplenium megalura Peperomia sp. Parinari excelsa IV 6.1 Asplenium dregeanum Polystachya leonensis Piptadeniastrum Ill 6.2 Asplenium geppii africanum Begonia polygonoides Piptadeniastrum IV 6.3 Oleandra distenta africanum Microsorium punctatum Triplochiton scleroxylon IV 5.5 Platycerium angolense Triplochiton scleroxylon IV 4.8 Platycerium stemaria

118 Ecology of vascular epiphytes in West African rain fo rest 111 Drynaria laurentii Pyrrosia mechowii Asplenium mega lura Oleandra distenta Table 46. Most frequent light-substrate class at the growing sites of each epiphyte species. Given as a percentage of the total number of species in each of the three groups. Based on Table 27 a and b, for species with 10 records or more. For species with less records the sum of records from Table 27 a and b, and Table 28 a and b are used if it reach 10 or more. For the remaining species the sum of records from Tables 27 a and b, 28 a and b and 29 are used. Bulbophyllum Bulbophyllum Bulbophyl lum Polystachya bunti ngii bufo cocoi nu m tessa!lata Substrate Light Total, Heavy Open Full shade shade sun substrate The Pteridophytes (39 spp.) Large humus deposits Q 10 0'/, Rhipsa lis baccifera Medinilla mannii Remusatia vivipara Peperomia sp. Minor humus deposits Bark Total, light Fig Records of epiphytes distributed between the different humus classes (from Table 27). (a) bark, (b) minor humus deposits, (c) large humus deposits. The orchids (101 spp.) Large humus deposits 1.0 Minor humus deposits Bark Total, light dings from only one substrate class (of the three that are recognized), as can be assessed from Tables Less frequently an even distribution between the substrate classes is observed. This 'preference' for a particular type of substrate occurs among all the major groups of epiphytes (Fig. 114). Most pteridophyte species (5 1 %) grow in minor humus deposits. The orchid species occurred on bark (50 %). The other vascular epiphytes were found in large humus deposits (54 %) (Table 46). Regarding the interrelationship between epiphytes and phorophytes three case may be distinguished in the area studied (denoted A, B and C below). A. Phorophytes with an abundance of epiphytes In the Nimba area a 'preference' by epiphytes for colonizing certain species of phorophytes is easily observed, but somewhat more difficult to express. The abundance can be expressed as previously described, either by the number of species of epiphytes on a certain species of phorophyte' or the number of 'stands' of epiphytes on the individual phorophyte. Since the results from these two methods correlate for the most part, the first method The other vascular epiphytes (13 spp.) Large humus deposits Minor humus deposits Bark 7.7 Total, light will be used (Table 4 7). Phorophytes with a high number of species of epiphytes are : Amphimas pterocarpoides Antho_notha fragans Calpocalyx aubrevillei Canarium schweinfurthii Ceiba pentandra Chlorophora regia Combretodendron macrocarpum Coula edulis 7.7 Cryptosepalum tetraphyllum Entandrophragma utile Heritiera uti/is Lophira alata Mitragyna ciliata Parinari excelsa Piptadeniastrum africanum Triplochiton scleroxylon An often striking difference in the abundance and floristic composition of the epiphyte vegetation depending on the species of phorophyte is well documented from various parts of the world. In the Phillippines the 'preference' for certain phorophytes that the orchids exemplify, has even led

119 112 Dick Johansson Table 47 a. Records of pteridophytes and other vascular epiphytes growing on different phorophytes in the Nimba area. Pteridophytes Antrophyum immersum A. n1anntanun1 Arthropteris monoca rpa A. orientalis A. palisoti Asplenium :lethiopicum A. nfricanum A. barteri A. drege:mum A. geppii A. hemitomum A. megalura A. variable var. paucijugum Da va Ilia chaerophy \loides Drynaria \aurentii Elaphoglossum burteri E. cheva lieri E. isabelense E. kuhnii E. salicifolium Lomariops;s guinecnsis Loxogramme lanceolata Lycopodium mi ldbraecli i L. warneckei Microgramma owa riensis Microsorium punctatum Nephrolepis bi serrata N. undulata 0\eandra dislenta Phymatodes scolopendria Plat.vceriom angolense P. slemari::t Pyrrosia mcchowii Tectaria angelicifolia T. fernandensis Vi ttaria guineensis Xit:.hopteris oosora X. serrulata X. villosissima Total no. of pteridoph.vtc spp. Other vase. epiphytes Begonia mannii B. polygonoides B. rubro-marginat..'l Cnlvoa monticola C. trochainii Medinilla mannii Peperomia fernandopoiana P. molleri P. rotundifolia Preussiella chevalier[ P. kamerunensis Remusatia vivipara Rhipsalis baccifera Total no. of other vase. epiphyte spp. + X + + X + X + X " 0 0 " + o x + X x x X X 0 + x x + x x + o + X 0 + X 0 X 0 0 x x + x x o + X X + X + X I X " X 0 + " 23 4 X X x x x + x x x o x x x x x x 0 X X X X X X X X X + X X X X X X X + + X X ' + + X ' ' ' ' x + o + + o x + x o + o + o o x x x x + x x x o x + o + o o x X 0 x x + x x x x x o + + X X + X + 0 o o o x x o x -t o o + + X X x x x o o o o o + x x x + o + + u x x x t x x o x o x x x x o o x x x x o o x x + x x x x x x x x x x x x X 0 + X X + X 0 ' X X 0 X X t o x x x + x + + x o o x x x x x + x x x x x 'l: x x x x x o x x 10 X 4 X X X X 30 X X 0 X 38 + x x o + x x x x x o x X + X X X X + 34 x o x o + + x + X + 0 X 0 X -t o x + x + x x x x + x x x x + + x + x x x x + x ' X X X ' + X ' X X + 30 X + X X X 0 9 N ffi M O M m N N N M 9 - ffi M m - M m 9 M..-( 1"""1!"""'.-1 1"""1 1"""1 M...-! C\1 J""-4,...;,...,...; 1'""""4 r-t...-t C\l.--t C'? N...-!...-t C'.J M C\1.--t C'\1 1"""1... M CO 1'""" CO N CO 1"""1,...; M t--... C\1... X X X () 0 0 o o + o x x x x + + x x o + o o x X + X + + x + + x + x o + x x o o + o x x + o o + x x o o o x I + 0 X 0. x x x o o x x o x x + x + x l X X X + 24 X D S G lt) <f) "' H.s.s::: bl) :;:; "'.s::: "' "0 ] - 3.g E o _g 0.. C.) U r r ,...,..., M ':"l :"I L::' 7'1,...; I :2 3 - s x = close observalion, o = disl1.n<"e observation, + o occasional observation. Only one kind of record is given, i.e. when a close observation record occu r, dislance and occasional observations are excluded. If a distance observation is given no close record ex ist and onlv when close and distance records are lacking, occasional records are shown.

120 :r...;,. :;;;.:::: :r. = J g == 7 =. 20 u ::.- ')') ig fa !. g :J -!.) 5 =. 24 i7 3 9 [ 5 f':l 0 26 a. i i ; 0 o lh = c;; 23 [ 13 g :- 1:.:! ('tl f':l ''0. ::: i4 Q.g- 47 ;;: ::: g 0 5., ;g!) g ::,:1 t.l 2:1 g! 3!) 5 10 :n I ;; i " X t 7. c - '1:l ::' "' I 1! "" d'!!i lf - Z t"' 2-g 3 a; t"' ;. i 2-:T.' :r.. "' Cl 7. n r: "' "' c "' l i -;: 0 "' c c: c 0 i ll - 0 /. +. > > l -:;, - w!...: X,:': t _. 1..;. -1 _. t' W ;: -1 :.Jl ::':.;; :::,_. _.,_.,_. 0),_. '.ZJ I'<J ;:.,.;.,, 1..;. I'<J 1..:1-1 :j =": ;,_. -=;.l::o. -; ::; :-: - ::;:: _. I ::; t.;. 1...;1 ':.1. t.;.,; 1.l::o. J. ::,_. :.a C': ;: ;:; _. :.;1 =t; o;..;:.t:.. :,.,) ::: 1 C: ::-: I - 1..: c..;..::0 1 i - c ;: Phoroph\ tcs of the high fo rest t\lbi7.i:."t glaberrim:1 Albizia 7.. \ gia A ls toni:l boonei Amphimas pleroc:tl'poidt':-; Anthocleista nobi lis A nthonnth:l fl':tgans AnLiaris toxic<l l'i;j l3el'linia confus:1 Bomba:x buonopozense llusse:1 occidcntalis Calpocal.\'X aubre\ illci Can;trium schweinlurlhii CC'ib:l pentandra C' hitllowia sanguinca I Chlor ophora regi:l Chr'vsoph_, llum perpulchrum Comh rctodendron macroca rpum Coula cdulis Cr,, ptns( p:llum '..C li'aph, llum Uaniellin ogea Distcmonantbus benlh:rmianus Entand l'ophr agma utile Et _vthrophleum ivorcnse F:t a r:r tcssmanni i Gua 1 ea ced rata HeJ"iticra utilis Khav:1 anthotheca Lophira :.1law Lo\'oa trichilioidcs!\'jammca africana Mi t rag.vna ciliat:l N:IUclca didc rrichii P:ninari :1uhrevillei Purin:lri excclsa Pa rina ri glabra Parki;I bicolor Pent.a c lethra macruphvll:l Pentatlesm;1 blltytacca PipL;tdcni:tsu um a!'ric:rm1m P\Tnanthus angolcnsis Rhodognaphalon brevicus Sacogloltis gaboncnsis Tcrminalia i\ ot ensis Termin:tlia supe rba Triplochiton sclct ox\'lon l':. paca guincens i s Vilex micrantha w 1.:.. rv <x :::t. 1..; l Total no. of phorophv1c spp Phoroph,Yles oulsitlc the high fo1 es1. Col:t nilida Cussonia bu rteri Hevea brasilien3is Musanga cecwpioidc!:i Dead Lrces El:1cis guineensis 'l'otal no, of phoroph_vte spp " % '"' 'L 3 g-

121 114 Dick Johansson to the construction of a list of favourite 'host trees' for certain popular orchids, for aiding the collector in field-work (Sulit 1950:6-8). Morris (1970:5) uses the term 'orchid-prone' for trees that are attractive to epiphytic orchids. The following species of phorophytes have been reported to carry an abundance of epiphytes: Liberia: Cola nitida (Harley 1955:71), Mitragyna ciliata (Voorhoeve 1965:324), Parinari excelsa (Voorhoeve 1965 :3 19) West Africa: Parinari excelsa (Jaeger et al. 1968:270, Schnell 1970:309) Malawi: Brachystegia spiciformis, Bridelia micranta, /lex mitis, Parinari mobola, Podocarpus milanjuanus, Syzygium cordatum, Uapaca kiekiana (Morris 1970:5) Java: Castanea argentea, C. javanica (Went 1940) West Borneo: Vitex sp. (Schuitem ker, in Went 1940:95) Florida, U.S.A.: Annona glabra L., Taxodium distichum L. (Frei 1973b:701) Haiti: Eugenia jambos L. (Curtis 1946),.Euphorbia lactera Haw. (Curtis 1947) S. America: Crescentia cujete (Schimper 1888:95) B. Phorophytes with fe w epiphytes In the Nimba area epiphytes are poorly represented on a number of species of phorophytes (Table 4 7), in particular on Fagara tessmannii, Terminalia ivorensis, T. superba and Musanga cecropioides, considering the abundance of full-grown individuals of these phorophytes. Less frequent phorophytes with a sparse epiphytic flora are e.g. Albizia glaberrima, A. zygia. The absence of epiphytic orchids on the trunks of Elaeis guineensis is obvious. However, they support a rich pteridophyte flora (Fig. 71). Only two epiphytic orchid species have been observed on this palm: Graphorchis lurida and Habenaria procera. (The Kew Herbarium. has 26 collections of the latter species. The growth habitat is given for fifteen of them. Eighty per cent of these were epiphytes, all of them on Elaeis guineensis.) In a study of the epiphytes on Elaeis guineensis in the former Belgian Congo (Zaire), Van Oye (1924) did not mention any orchids, but several pteridophytes and figs. In the Philippines it is even stated that "Orchids will choose any other tree in the wild than the palm" (Sulit 1950:8). Ruinen (1953:102) has suggested the term 'axeny' for this condition of general inhospitality of trees which never or only occasionally bear epiphytes. Trees belonging to this group have been reported from all over the world. Piers (1968:4) reports that Acacia and Ficus trees are avoided by most epiphytic orchids. The same applies to tree Euphorbias, exotic conifers and Eucalyptys trees. Moreau (1943 :8), however, remarks that conifers such as Juniperus bermudiana are colonized by orchids with a surprising frequency. From Australia Rupp (1969:XI) confirms that Eucalyptys trees are usually barren of orchids. The absence of epiphytes on figs has been observed by several authors. Schnell (1970:309) mentions that Ficus mucuso lacks epiphytes and Went ( 1940) notes that humus epiphytes are lacking on Ficus involucrata Bl. C. Spe ific relationships between phorophyte and epiphyte In the Nimba area, no specific relationship between phorophyte and epiphyte has been observed, even if the total dominance of Parinari excelsa at the highest parts of the mountains has resulted in a nearly absolute correlation between this tree and some epiphytes naturally occurring at these altitudes (Table 47). There are several reports of a relationship between a particular species of phorophyte and a particular species of epiphyte. Piers (1968:4) states: "Some epiphytes have marked idiosyncrasies regarding their host tree, e.g. Ansellia nilotica has a strong preference for the Doum Palm (Hyphaene thebaica), the Baobab tree (A dansonia digitata) is the typical host of Angraecum dives and Polystachya adansoniae, while Aiirangis thomsonii attaches itself almost exclusively to the rugged stems of the gigant ceder (Juniperus procera) of the Kenya highlands." Rupp (1969 :XI) gives a similar observation :"one or two of the ironbark eucalypts are favoured by Dendrobium aemulum, which for this reason is often callen 'Ironbark Orchid' ". More examples of this kind are listed by Richards (1964: 119). Morris (19 70 :5) found few specific host/ orchid relationship in Malawi, but observed: "There are however a few orchids which would appear to associate with specific hosts... Bulbophyllum intertextum on Newtonia buchananii, Polystachyajohnstonii on Vellozia spendens come to mind." Moreau ( 1943 :8) is a little more hesitant : "there is little evidence of specific relation between orchid and tree host, except that certain aberrant Polystachyas that are otherwise terrestrial also grow on the curios-

122 Ecology of vascular epiphytes in West African rain fo rest 115 ly looking fibrous stem of Vellozias, but no other host." (See also Richards 1957:568.) Boyer (1964) states that the occurrence of the epiphytic ferns Platycerium stemaria and P. angloense on various phorophytes in the Ivory Coast, does not permit any conclusions regarding their preference for particular species of phorophytes. Whether a relation between a certain species of phorophyte and epiphyte really exist is doubtful. In many cases the epiphytes have for various reasons a very limited choice of host trees. Given the opportunity, many of these epiphytes now occurring on a specific host tree, might very well thrive on other trees. Another fact that favours the theory of a specific relation between host and epiphyte is the poor knowledge of the presence of the epiphytes. Increasing information on the ecology and presence of the epiphytes will probably decrease the number of 'specific relationships'. Biotic factors Several of the biotic factors have already been presented and discussed in Chapter Ill. Human influence The human influence on the rain forest effects the epiphytes indirectly. In the Nimba area patches of scattered trees that remain after forest destructions are the particular growing sites of several orchid species. These are species of the deciduous forest, e.g. Ansellia africana, Plectrelminthus caudatus, Polystachya paniculata, P. puberula and Rangaeris rhipsalisocia. Animal influence Direct effects, as judged by signs of being eaten or used by animals, on the epiphytes is. very seldom observed. Some species, however, show signs of frequently being eaten (probably by insects), e.g. Pyrrosia mechowii, Ancistrochilus rothschildianus, A ngraecopsis elliptica and Polystachya ramulosa. Effects on the leaves by herbivores or other agents, as can be judged by holes in the falling leaves, seem to be of minor importance for the rain forest species in general (Odum 1970 b). Voute (1946, 1964) states that insect outbreaks do not occur in tropical forests because of the stability of checks and buffers that act on any species that becomes overabundant. Nutritional importance of animals and microorganisms The presence of a rich fauna in the crown of the rain forest trees naturally influences the nutritional supply of the epiphytes through excreta from mammals, birds, snakes, lizards, frogs and insects. The effect of bird excreta was early recognized. Sernander ( 1912) coined the term 'ornithocoprophily' for such plants that were favoured by bird excrement (or rather their nitrogen content). Du Rietz (1932) showed that bird excrements also increased the ph of the substrate. Trees with nesting birds, edible berries, as well as those used as sleeping trees and observation posts, are known to attract nitrophytic lichens. It is impossible to even try to estimate the total effect of nutrition provided by the animals in the diversified rain forest. It should at least be kept in mind during the analysing process. The role of the microorganisms in the nutritional balance is unknown, but Ruinen (1956) found bacteria of the genus Beijerincka on leaves on nearly all trees and shrubs tested in Java and Sumatra. These nitrogen-fixing bacteria obtain their minerals and some organic material from substances excreted by the leaves. Blue -green algae of several kinds are always abundant on the bark of trees in the wet tropics but their nitrogen-fixing capacity is unknown. (cf. Ruinen 1961). Bond ( 1959) reports: "There are also nitrogenfixing micro-organisms present on leaves and branches of trees, which doubtless adds to the nitrogen available to the roots of epiphytes, as similar microorganisms do in the soil." The high amounts of nitrogen in the humus from Poly podium polypodioides puzzled Pes sin (1925:32): "It is indeed remarkable that the nitrogen of the humus on the bark of the tree is frequently as high and at times even higher than that of the most fertile soils."

123 VI. Distr ibution on the phorophytes General pattern At the same time as it is possible to recognize a distribution pattern on the phorophyte according to the occurrence of a particular species of epiphyte, one can also distinguish a pattern for whole groups of epiphytes (Table 48). Although lichens, climbers, filmy ferns and mosses were not consistently recorded, their presence was noted. Generally speaking, each of the five zones of the phorophyte are characterized by a particular group or groups of epiphytes (Fig. 115). Specific patterns Species seldom observed on tall phorophytes Certain species of orchids are very rarely observed on tall phorophytes, instead they frequently occur on smaller trees and even shrubs that often border small rivers and streams, or are found along tracks in the forest. A ngraecum classensii, Diaphananthe densiflora, D. rutila, Eurychone rothschildiana and Rhipidoglossum paucifolium exhibit this pattern. 116), Tectaria angelicifolia and T. fe rnandensis are frequent. The orchids are represented by Polystachya ramulosa and P. rhodoptera which are almost exclusively located in this section. Also Brachycorythis kalbreyeri, Habenaria procera, Liparis nervosa and Vanilla crenulata belong to this section, being epiphytes which grow in large humus deposits. The group of other vascular epiphytes is represented by Calvoa monticola and more seldom C. trochainii. Species normally located on the main trunk Several species may appear in this section, e.g. Ancistrorhynchus cephalotes, Asplenium africanum, Diaphananthe bidens, D. pellucida. However, there are rather few species that are restricted to this vertical section, which is mostly devoid of humus Species normally restricted to the basal part of the trunk This section of the tall phorophytes is occupied by a number of species very rarely found in any other section. Among the pteridophytes Asplenium barteri is the most common, but several others e.g. Elaphoglossum kuhnii, Lomariopsis guineensis (Fig. Lichens pteridophytes + other vascular ep. Table 48. General distribution pattern (section) on the phorophyte of the pteridophytes, the orchids and the other vascular epiphytes. Based on the most frequent growing site (section) of each spe ies (Tables 27 a + b, 28 a + b, 29). The result is presented as a percentage of the total number of species in each group. Climbers V Filmy ferns 4.0 Fig General distribution of epiphytes on tall phorophytes.

124 Ecology of vascular epiphytes in West African rain forest 117 Fig Lomariopsis guineensis normally occurs on the lowest parts of the trunks. Nimba Range 700 m. deposits. Two species of ferns and two orchids can be considered to have the center of their distribution in this section: Antrophyum immersum, Elaphoglossum chevalieri, Polystachya saccata and Tridactyle crassifolia. Two species with a climbing habit, Culcasia angolense and Raphidophora africana (Fig. 11 7), which are included among the facultative epiphytes, play an important role through their substrate holding capacity. Species of the crowns In this analysis the results from the close observations for species with at least 20 separate records from the crowns have been used. For species with fewer observations the results from the distance observations are added and then used, if the total sum is at least 20 observations. It might seem hazardous to use such a low number of observations as a base for a detailed distribution pattern. However, in most cases the information obtained with these rather accurate methods are checked against the more numerous but ecologically not as welldocumented, so-called occasional observations. When there are uncertainties in the distribution pattern, e.g. differences in the results betweep the various observation methods used, the discrepancies are discussed in the text. Since the absolute majority of the records of species belonging to this group are located in the crown, the records from other sections of the phorophyte have simply been omitted in this analysis. The distribution pattern of the individual species can be divided into six major patterns (A-F). The first three, A, B and C are represented by species that are ± restricted to only one section of the branches, (A, for species in section Ill, B, for species in section IV and C, for species in section V). The Fig Raphidophora africana and Culcasia angolense are common climbers on the trunks of tall trees. Y ekepa. fourth and fifth pattern, D and E, are formed by species that occur in almost equal numbers in two sections with very few individuals in the third, (D, for species in sections Ill + IV and E for species in sections IV + V). The last pattern, F, is formed by species that occur more or less evenly in the various sections of the large branches (Ill + IV + V). Species exhibiting the various distribution patterns are: A (Ill) A ncistrorhynchus capitatus Asplenium africanum A. dregeanum A. geppii A rthropteris monocarpa A. orientalis Elaphoglossum salicifo!ium Microgramma owariensis Nephrolepis biserrata N. undulata Vittaria guineensis Xiphopteris oosora A ncistrochilus rothschildianus Angraecum chevalieri Bulbophyllum bufo B. fa lcatum B. josephii B. saltatorium B. winkleri Calyptrochilum christyanum Diaphananthe pellucida Polystachya laxiflora Begonia mannii B. polygonoides A eta phytogeogr. suec. 59

125 118 Dick Johansson B. (IV) Asplenium megalura Elaphoglossum isabelense Lycopodium mildbraedii L. warneckei Platycerium angolense Cyrtorchis aschersonii Diaphananthe bidens Graphorchis lurida Nephrangis filiformis Polystachya galeata P. stemaria P. paniculata Ancistrorhynchus clandestinus Angraecum distichum P. puberula Rangae'ris muscicola Bulbophyllum barbigerum R. rhipsalisocia B. buntingii B. intertextum B. maximum B. oreonastes B. schinzianum B. schimperanum Chamaeangis vesicata Tridactyle anthomaniaca T. crassifolia T. tridentata Medinilla mannii Peperomia rotundifolia R hips a/is baccifera C(V) Only one species exhibits this pattern, Bolusiella talbotii (Fig. 118). D (Ill + IV) Dl'ynaria laurentii Microsorium punctatum Phymatodes scolopendria Aerangis biloba Angraecopsis elliptica Angraecum birrimense Bulbophyllum cochleatum B. cocoinum B. distans B. linderi B. lucifugum Cyrtorchis arcuata subsp. variabilis Polystachya leonensis P. polychaete P. tessallata B. rubro-marginata Bulbophyllum linderi exhibit an A-pattern in the distance examinations. Aerangis biloba shows a C-pattern in the distance observations and in the occasional records it appears in all sections of the phorophytes. E (IV + V) Only orchid species exhibit this distribution pattern: Bulbophyllum scariosum, Polystachya adansoniae, P. dalzielii. F (Ill + IV + V) Species representing this pattern are very rare, a fact that suggest that each of the epiphytic species is confined to restricted habitats. Aerangis lauren- Fig Bolusiella talbotii normally occurs on the outer parts of large branches among lichens. A small Rhipsalis baccifera has also established itself. tii and Tridactyle tridactylites seem to follow this pattern, but it should be noted that these two species deviate from this distribution in the distance observations where A. laurentii shows an E- and T. tridactylites and A-pattern. Species distribution and environment gradients along large branches In the absence of data about the most important environmental factors concerning the changes along the branches a theoretical discussion may throw some light on this problem. The environmental changes that occur are listed here in two main groups, i.e. factors that decrease respectively increase towards the outer parts of the branches. In the first group the roughness of the substrate, humus deposits, nutritional content of the substrate, humidity of the substrate and the relative humidity of the air can be mentioned. In the second group the temperature, light intensity and wind velocity are important. In Fig. 119, the decreasing and increasing factors are each represented by a straight line. The steepness and irregularities of these gradients are naturally dependent on a number of variable factors, e.g. species of phorophyte and the physiognomy of the forest. The distribution pattern of six species of epiphytes, each representing one of the major patterns that previously were described, are also illustrated with the decreasing and increasing factors shown as dotted lines. A. This pattern follows the decreasing gradient. The proportionally large number of pteridophytes, but also some orchids that belong to this group, seem to be primarily limited in their distribution by the decreasing factors. B. This pattern seems to arise from the interaction of the increasing and decreasing gradients. In the basal parts of the branch the increasing gradient, and in the outer parts the decreasing gradient limit the presence of epiphytes. A large number of orchids exhibit this pattern which probably can simply be described as a delicate balance between the need of light and the influence of evapotranspiration. C. This pattern follows the increasing gradient. It is probably the higher light intensities that favour the only species that exemplifies this pattern. D. This is a modified A-pattern where the influence of the increasing gradient effects the pattern in the basal parts of the branch.

126 Ecology of vascular epiphytes in West African rain fo rest '1. 50 A B Basal part Middle part Outer part Bulbophyllum oreo n astes _ E. This is a modified C-pattern. The effect of the decreasing gradient is noticed at the outer part of the branch. Only three orchids show this pattern. The evapotranspiration in these more exposed parts of branches represents a severe drawback for the survival of epiphytes. Therefore it is interesting to note that two of the orchid species, Bulbophyllum scariosum and Polystachya dalzielii, only occur in high altitudes where low temperatures and mist surpress the evapotranspiration. The third species, Polystachya adansoniae, is adapted to dry environments with a geogr phical distribution in rather dry areas over large parts of Africa. F. This pattern is the average of the increasing and decreasing gradients, suggesting a wide tolerance towards environmental influence. However, Aerangis laurentii and Tridactyle tridactylites, both show a different pattern in the records from the distance observations which may indicate that this pattern is less distinct than the others. c D E F Bolusiella ta l botii Bulbophyllum linderi Polystachya adansoniae Aerangis laurenti i _...! -:.: Fig 119. A theoretical model presenting a possible explanation for the different distribution patterns of epiphytes on the large branches (see text). The importance of any single factor in the total environment is naturally very hard to estimate. In a detailed study of the epiphytic fern Polypodium polypodioides the following statement was presented: "It is safe to conclude from the results obtained that neither the light, the relative humidity of the air, the temperature of the air nor the substratum temperature exert any direct influence on the occurrence and distribution of Polypodium polypodioides nor on the epiphytes associated with it. It is the sum of the total of the effects of the first three conditions on the evaporating power of the air, in the immediate vicinity of each station on the tree, which is responsible for the particular epiphytic flora at the given station" (Pessin 1925 :31). The evaporating power normally increases from the base of the large branches towards the outer part through influences previously described. Most pteridophytes in the area investigated show a distribution pattern on the branches that is reversed compare? to a possible increase in evaporating power. For most of the orchids the distribution pattern seems to be a result of a need for high light intensities and the tolerance of the evaporating power of the air, while the composition of the substrate can be considered of secondary importance. To make the distribution solely dependent on the evaporating power of the air without any considera-

127 120 Dick Johansson tion of light intensity and substrate composition is not accurate for the majority of epiphytes. This investigation showed that the different epiphytes often have a marked preference for a certain kind of substrate and light intensity. The almost total absence of epiphytes from the crowns of the trees in the lower strata of the forest cannot be satisfactorily explained with differences in the evaporating power of the air. It is more probable that low light intensities are the limiting factor since substrates of similar composition and evaporating power of the air equal to the conditions in the crowns also exist at various places in the lower parts of the forest.

128 Resume Ecologie des epiphytes vasculaires dans la foret dense humide d' Afrique occidentale La superficie examinee Cette etude est centree sur l'ecologie des epiphytes vasculaires dans la partie liberienne des Monts Nimba et superficies adjacentes (Fig. 2). La flore d'ensemble de cette meme region a ete decrite par Schnell (I 952) et Adam (1971). Dans l'aire examinee, la haute foret (dont la strate arborescente superieure est a 30 m ou plus au-dessus du sol) occupe de petites surfaces. Ce sont les forets a differents etages de regeneration et les surfaces agraires qui dominent le paysage. La partie la plus haute de la region est couverte d'une foret vierge Parinari excelsa. Composition de la flare epiphytique L'etude porte sur 153 especes au total (39 pteridophytes, I 0 I orchidees et 13 autres epiphytes vasculaires). Des enregistrements additionnels ont considerablement augmente la zone de distribution de quelques especes (Fig ) et 32 especes sont nouvelles au Liberia: Elaplwglossum isabelense E. salicifolium Lycopodium mildbraedii Pyrrosia mechowii Xiphopteris oosora Ancistrochilus recurvus A ngraecopsis elliptica Angraecum classensii Bulbophyllum bifarium B. josephii B. lucifugum B. lupulinum B. magnibracteatum B. pavimentatum B. phaeopogon B. rhizophorae B. saltatorium B. schimperanum Cyrtorchis aschersonii Diaphananthe densiflora Eurychone rotschildiana Podangis dactyloceras Polystachya saccata P. subulata P. tenuissima Rangae'ris brachyceras R hipidoglossum paucifolium Stolzia repens Tridactyle crassifolia T. tridactylites T. tridentata Begonia rubro-marginata La tlore epiphytique comprend des elements de la foret dense humide de basse et moyenne altitudes par exemple les Cyrtorchis monteiroae et Angraecum birrimense (Fig. 19), de la foret decidue dans la mosaique foret-savane par exemple les Ansellia africana et Rangae'ris rhipsalisocia (Fig. 20) et des communautes de montagne par exemple les Polystachya dalzielii et P. leonensis (Fig. 21). Biologie de quelques ep iphytes Les orchidees peuvent fleurir chaque mois de l'annee mais on remarque deux pointes de floraison (Fig. 49). Le genre Bulbophyllum a une pointe de floraison a la fin de la saison pluvieuse tandis que le genre Polystachya presente une pointe correspondante au debut de la saison seche ou de la saison pluvieuse. Parmi les insectes frequentant les fleurs d'orchidees on a pu observer trois especes avec pollinies adherente : Polistes marginalis (Tab.) et Polybiodes tabida (Tab.) de Bublophyllum schinzianum et Euchromia lethe (F.) (Fig. 52) de Diaphananthe pellucida. Formes de vie et hydrometrie La resistance des epiphytes a la secheresse se reflechit dans differentes adaptations xeromorphiques (Fig. 59). Les epiphytes peuvent etre divisees en plantes tolerantes a la secheresse et plantes evitant la secheresse. Ce dernier groupe est decidu et evite ainsi que l'eau ne se perde par la transpiration des feuilles durant la saison seche tres rigoureuse. Les feuilles des plantes tolerant la secheresse persistent pendant la saison seche. Oes.valeurs tres elevees de transpiration ont ete obtenues pour un certain nombre de plantes evitant la secheresse par ex. Polystachya leonensis et Polystachya dalzielii, provenant des parties les plus hautes et les plus humides de la zone, et Graphorchis lurida et Polystachya puberula d'altitudes plus basses. Des valeurs elevees ont ete ainsi obtenues pour Asplenium geppii et Begonia rubro-marginata (Tableau 12). C'est parmi les orchidees que l'on a obtenu les valeurs les plus faibles de transpiration, spe_cialement parmi celles qui ont une croissance monopidiale par ex. Bolusiella talbotii, Calyptrochilum christyanum, Chamaeangis vesicata et Neprhangis filiformis (Tableau I3). Repartition des epiphytes sur les arbres Methodes. Sur 463 phorophytes (arbres hotes) la

129 122 Dick Johansson repartition des epiphytes a ete enregistree. Pour simplifier l'enregistrement le phorophyte a ete divise en cinq sections (Fig. 76). On a applique trois methodes differentes de denombrement : les observations proches, les observations a distance et les observations occasionnelles. L'observation proche implique des investigations sur des arbres abattus,!'observation a distance est une etude du tronc et d'une branche complete ( ou plus rarement un arbre entier) d'un arbre sur pied a l'aide de jumelles ou d'un telescope sur trepied. L'observation occasionnelle est reduite aux investigations obtenues a partir seulement d'une partie limitee du phorophyte. Les resultats de cette derniere methode ne sont utilises que pour completer ceux des deux autres. On a egalement examine le substrat et l'eclairement au lieu de croissance de!'epiphyte individuelle. Le substrat a ete divise en trois classes : ecorce, ecorce avec depots faibles d'humus, et depots importants d'humus. La lumiere a aussi ete divisee en trois classes : plein soleil, demi-obscurite et obscurite. Occurence des epiphytes Dans la haute foret 50,4 % des arbres hauts de dix metres ou plus portaient des epiphytes, par contre dans une foret "secondaire" on descendait a 14,8 %. Il etait done evident que particulierement les orchidees etaient rares dans une foret "secondaire". Certaines especes d'arbres peuvent abriter un grand nombre d'especes d'epiphytes par ex. Heritiera uti/is (30 spp.) Mitragyna ciliata (28 spp.) (Tableau 42). Aussi le nombre des individus ("stands") d'epiphytes sur certains arbres etait-il tres grand, par exemple un seul H eritiera uti/is ne portait pas moins de epiphytes et un Parinari excelsa Groupements ep iphytiques On dit qu'il y a groupement epiphytique quand trois especes au minimum d'epiphytes forment une unite et quand la distance entre deux de ces epiphytes et la troisieme ne depasse pas 0,5 m. On distingue sept groupements epiphytiques differents au-dessous de 1000 m et trois autres de plus a des altitudes superieures (Tableau 30). Les fougeres forment la base de sept des dix groupements. Il semble que ce soit leur capacite de formation de substrat qui attire les autres epiphytes. Colonisation et effe ts sur les phorophytes Les differentes methodes indiquent que ce sont particulierement les phorophytes les plus grands qui sont de preference colonises par les epiphytes. Les pteridophytes semblent etre les epiphytes pionniers tandis que les orchidees sont les dernieres a s'etablir (Fig. 87). Certains arbres ay ant une riche flore epiphytique par exemple Mitragyna ciliata et Parinari excelsa, souffrent apparemment "d'epiphytosis" (Ruinen 1953). Les effets des orchidees sans feuille sur les phorophytes peuvent aussi indiquer un parasitisme partiel. Influences de l'environnement sur les epiphytes Climat. Le rapport pteridophytes epiphytiques/orchidees se modifie avec!'altitude. A la base de la zone ( m) la proportion pteridophytes/orchidees est approximativement de 1 :3 mais, a m, elle est de 1:1. Des variations similaires ont egalement ete observees sur les hautes montagnes d' Afrique orientale. Dans les milieux secs, ainsi qu'on l'a observe en Tanzanie, le nombre des epiphytes decroit rapidement (specialement les pteridophytes) mais l'abondance de certaines orchidees epiphytiques peut surprendre. Dans les montagnes meridionales de Tanzanie on a observe que tous les arbres ( 4 m) cvune terre boisee Brachystegia portaient l'orohidee I Tridactyle tricuspis. Substrat. La valeur ph d'echantillons d'ecorce provenant du meme phorophyte presentait d'assez grandes variations. C'est dans les parties exterieures des grandes branches et la partie superieure du tronc principal que l'on trouvait les valeurs les plus basses. On n'a cependant pas pu trouvef de corrclation pertinente entre la valeur ph de l'ecorce et la flore epiphytique. Les valeurs ph des depots d'humus etaient beaucoup plus elevees que celles de l'ecorce. La majorite de l'espece pteridophyte "preferait" les depots mineurs d'humus tandis que les orchidees poussaient surtout sur l'ecorce et les autres epiphytes vasculaires dans les grands depots d'humus. Correlation entre l'abondance d'epiphytes et l'espece de phorophyte Les grands specimens d' Heritiera uti/is, Lophira alata, Mitragyna ciliata et Parinari excelsa sont riches en epiphytes tandis que par exemple A nthocleista nobilis Fagara tessmannii, Terminalia

130 Ecology of vascular epiphytes in West African rain fo rest 123 ivorensis et T. superba sont frequemment plus ou moins depourvus d'epiphytes. On n'a pas observe de correlation specifique entre }'epiphyte et le phorophyte. Lumiere. L'intensite de la lumiere au sol dans une haute foret a la base de la zone etait de 0,36 % de la lumiere exterieure mais dans une foret Parinari a 1300 m d'altitude elle etait de 6,65 % (Tableau 42). Dans les parties de base et les parties centrales des grandes branches d'un arbre Parinari excelsa a 1300 m la lumiere etait reduite de % par rapport a celle de la demi-obscurite (Tableau 43). La variation quotidienne dans l'intensite de la lumiere au lieu de croissance de certains epiphytes a revele des differences tres significatives entre les differentes especes (Fig. I ). En general, on trouve les pteridophytes dans la demi-obscurite tandis que les orchidees sont plus egalement reparties entre!'habitat en demi-obscurite et )'habitat en plein soleil. La distribution des epiphytes dans le phorophyte Chacune des cinq sections du phorophyte est dominee par un groupe d'epiphytes (Fig. 115). La plupart des especes d'epiphytes ont une distribution plutot limitee sur le phorophyte, c'est-a-dire dans une ou deux sections. La majorite des especes poussent dans la couronne. On distingue six modeles differents de distribution sur les grandes branches (Fig. 119). La distribution des epiphytes ne depend pas seulement de!'evaporation (Pessin 1925) mais elle est egalement influencee par la preference marquee d'une certaine sorte de substrat et d'eclairement. Les pteridophytes presentent une distribution qui va a l'encontre d'un accroissement possible de!'evaporation. La distribution des orchidees semble toutefois etre le resultat d'un equilibre entre le desir d'une grande intensite de lumiere et la capacite de resister a une plus grande evaporation d'air qui s'ensuivrait.

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135 128 Dick Johansson Rupp, H.M.R The orchids of New South Wales. - National herb., Sydney. Rutter, A.J. & Whitehead, F.H. (ed.) The water relations of plants. - British Ecological Soc. Symp. Ill. Blackwell, Oxford and Edinburgh. Sanford, W.W Orchids of West Africa. - Amer. Orch. Soc. Bull. 36: a - The Genus Aerangis. -Ibid. 37: b - Distribution of epiphytic orchids in semideciduous tropical forest in Southern Nigeria. - J. Ecol. 56: The distribution of epiphytic orchids in Nigeria in relation to each other and to geographic location and climate, type of vegetation and tree species. - Bioi. J. Linn. Soc. 1: The flowering time of West African orchids. - Bot. J. Linn. Soc. 64: Epiphytic orchids as characterizers of vegetation in West Africa. - A paper presented at the World Orchid Conference at Mendelin, Colombia Sanford, W.W. & Adanlawo, I Velamen and exodermis characters of West African epiphytic orchids in relation to taxonomic grouping and habitat tolerance. - Bot. J. Linn. Soc. 66: Scaetta, H La genese climatique des sots montagnards de 1' Afrique Centrale. Les formations vegetates qui en caracterisent les stades de degradation. - Inst. Roy. Colonial Beige, Bruxelles. Schelpe, E.A.C.L.E Pteridophyta. - In Exell, A.W. & Launert, E. (ed.) Schimper, A.F.W Die epiphytische Vegetation Amerikas. - Bot. Mitt. Trop Plant geography upon a physiological basis. Oxford Pflantzengeographie auf Physiologischen Grundlage. - Revised by Faber, A.F., Jena. Schnell, R La foret dense. - Lechevalier, Paris VI Vegetation et flore de la region montagneuse du Nimba. - Mem. I.F.A.N. 22, Dakar Phytogeographie des payes tropicaux. I Gauthier-Vitlars, Paris. Sernander, R Studier ofver lafvarnes biologi. I. Nitrofila lafvar. - Syensk Bot. Tidskr. 6: Sharp, A.J Vascular epiphytes in the Great Smoky mountains. - Ecology 38: Sjogren, E Epiphytische Moosvegetation in Laubwaldern der Insel Oland (Schweden). - Acta Phytogeogr. Suec. 44. Uppsala. Skye, E Lichens and air pollution. - Ibid. 52. Smith, J.J Ephemeral orchids. - Ann. Jard. Bot. Buitenz. 35: Spanner, L Untersuchungen iiber den Warme und Wasserhaushalt von Myrmecodia und Hydnophytum. - Jahrb. Wiss. Bot. 88: Steenis, C.G.J.J., van Recent progress and prospects in the study of the Malaysian flora. - Chron. Bot. 4: Stewart, J More about Microcoelias. - Amer. Orch. Soc. Bull. 42: Stewart, J. & Campbell, B Orchids of tropical Africa. - Allen & Co., London. Stacker, Eine Feldmethode zur Bestimmung der momentanen Transpirations- und Evaporationsgrosse. I, Il. - Ber. Deutsch. Bot. Gesell. 47: , & Sulit, M.D Field observations on trees hosts of orchids in the Philippines. - Philip. Orch. Rev. 3 :3-8. Summerhayes, V.S Orchidaceae, Part 1. - In Milne-Redhead, E. & Polhill, R.M. (ed.) Swanson, R.H. & Lee, R Measurement of water movement from and through shrubs and trees. - J. Forest. 64 : Teuscher, H Microcoelia guyoniana and other leafless epiphytic orchids. - Amer. Orch. Soc. Bull. 41: Thornton, I Nutrient content of rainwater in the Gambia. - Nature 205 :1025. Thorold, C.A The epiphytes of Theobroma cacao in Nigeria in relation to the incidence of Black Pod diseases (Phytophthora palmivora). - J. Ecol. 40 : Tixier, P Flore et vegetation orophiles de l'asie tropicale. - Soc. d'edition d'enseignement superieur, Paris. Tournay, R Orchidaceae africanae. 1. Les orchidees congolaises: caracteres vegetatifs et floraux, types biologiques, clef de determination des genres sympodiaux, apen;u les genres. - Bull. Soc. Roy. Bot. Belg. 87: Tukey, H.G., Jr Leaching of rnetablites from foliage and its implication. - In Odum, H.T. & Pigeon, R.F. (ed.) 1970, Chapter H 11. Vanderyst, R.P.H Nouvelle contribution a!'etude des Ficus epiphytes sur l'elaeis. - Rev. Zool. Afric. 10(2). Wallach, A Beitrage zur Kenntnis der Wasseraufnahme durch die Luftwurzeln tropischer Orchideen. - Zeitschr. f. Bot. 33: Waiter, H Ecology of tropical and subtropical vegetation. - Oliver & Boyd, Edinburgh. Visser, S.A Origin of nitrates in tropical rainwater. - Nature 20 1:35. Voorhoeve, A.G Liberian high forest trees. - Pudoc, W ageningen. Voth, P.H Conduction of rainfall by plant stem in a tropical rain forest. - Bot. Gaz. 101 : Voute, A.D Regulation of the density of the insect populations in virgin-forests and cultivated woods. - Arch. Neerl. Zool. 7: Harmonious control of forest insects. - In Romberger, J.A. & Mikola, P. Vol. I 1964: Went, F.A.F.C Ueber Haft- und Nahrwurzeln bei Kletterpflanzen und Epiphyten. - Ann. Jard. Bot. Buitenz. 12:1-72. Went, F.W Over de sociologie der Epiphyten. Handel. 6 Ned. Ind. Naturw. Congr. : Bandoeng Soziologie der Epiphyten eines tropischen Urwaldes. - Ann. J ard. Bot. Buitenz. 50:1-98.

136 Ecology of vascular epiphytes in West African rain fo rest 129 Whitmore, T.C A study of light conditions in forests in Ecuador with some suggestions for further studies in tropical forests. - In Bainbridge et al. (ed.) 1968: Wiesner, J Zur Physiologie von Taeniophyllum Zollingeri. - S.B. Akad. Wiss. Wien, Math.-Naturw. Cl. 106: Willis, A.J. & Jetferies, R.L. (1963) - Investigations of the water relations of sand-dune plants under natural conditions. - In Rutter, A. & Whitehead, F. (ed.) Willis, J.A., Yemm, E.W. & Balasubramaniam, S Transpiration phenomena in detached leaves. - Nature 199 : WiJlis, J. C A dictionary of flowering plants & ferns. - Seventh ed., revised by Airy Shaw, H.K., Cambridge Univ. Press, London. Withner, C.L. (ed.) The orchids, a scientific survey. - Ronald Press, New York Orchid physiology. - In Withner (ed.) 1959: Yarranton, G.A An instrument for measuring the microrelief of the bark. - Can. J. Bot. 45 (8): Literature not cited in the text but related to the subject Briscoe, M.S The relation of insects and insectborne diseases to the vegetation and environment in Liberia. - Ecology 33: Bryant, M.T Some of our palms. - The Liberian naturalist 4( I ):9-13. Monrovia. (Stencil) Trees roadsidp.s. - Ibid. 4(2):9-20. Hopkins, B Forest and savanna. - Heinemann, London. Harrison, E.R Epiphytic orchids of Southern Africa. - The Natal branch of the Wildlife Preserv. and Conserv. Soc. of South Africa. Durban. Jaeger, P. & Summerhayes, V.S Note sur quelques Orchidees recoltees dans les Monts Loma (Sierra Leone) et les contrees limitrophes. - Kew. Bull. 3: Kloppers, J Die Suid-afrikaanse epifiete. - S. African Orch. J. March 1971: Koopowitz, H Aerangis- an extrapolation from ecology to cultivation. - Amer. Orch. Soc. Bull. 33: Kunkel, G Die einfliisse von Kultur und Siedlung auf das Waldbild Liberias. - Zeitschrift fiir Wirtschaftsgeogr. 7: Leakey, C.L.A a - The orchids of Uganda. - Amer. Orch. Soc. Bull. 37: b - The orchids of Uganda. The major angraecoid genera. - Ibid. 37: c - The orchids of Uganda. Various species of horticultural merit. - Ibid. 3 7: Morton, J.K West african lilies and orchids. - Longmans, Green & Co... London. Onochie, C.F.A The use of field characters in the tree identification. - Comptes Rendus, IV Reunion pleniere A.E.T.F.A.T Lisboa. Piers, F Orchids of Africa. Angraecum distichum and A. aporoides. - Amer. Orch. Soc. Bull. 37: Richards, P.W Ecological notes on West African vegetation. - J. Ecol. 45 : Ecological notes on West African vegetation. Ill. The upland forest of Cameroon Mountain. - J. Ecol. 51 : Sanford, W.W a - Plectrelminthus caudatus. - Amer. Orch. Soc. Bull. 39: b - Practical conservation of orchids in Nigeria. - Nig. J. Se. 4: c -Orchids of the Bamboutos and Manengouba highlands in East Cameroun. - Amer. Orch. Soc. Bull. 39: d - A selection of West African orchids. - Ibid. 39: The orchid flora of Equatorial Guinea in relation to that of West Africa. - Mitt. Bot. 10: Schelpe, E.A.C.L.E An introduction of the South African orchids. - MacDonald, London. Strong, R.H. (ed.) The African Republic of Liberia and the Belgian Congo. I, Cambridge, Mass. Warner, R Vegetation and agriculture of Liberia and adjacent West Africa. - Iowa A cad. Sci. 52:

137 ACTA PHYTOGEOGRAPHIC A SUECICA 1. E. Almquist, Upplands vegetation och flora. (Vegetation and flora of Uppland.) :- (27:-). ISBN X. 2. S. Thunmark, Der See Fiolen und seine Vegetation :- (14 :-). ISBN G.E. Du Rietz, Life-forms of terrestrial flowering plants. I. i :- (I 0:-). ISBN B. Lindquist, Om den vildvaxande skogsalmens raser och deras utbredning i Nordvasteuropa. (Summary : The races of spontaneous Ulmus glabra Huds. and their distribution in NW. Europe.) :- (8:-). ISBN H. Osvald, Vegetation of the Pacific coast bogs of North America :- (8:-). ISBN G. Samuelsson, Die Verbreitung der hoheren Wasserpflanzen in Nordeuropa :- ( 14:-). ISBN G. Degelius, Das ozeanische Element der Strauchund Laubflechtenflora von Skandinavien : (24:-). ISBN R. Sernander, Granskar och Fiby urskog. En studie over stormluckornas och marbuskarnas betydelse i den svenska granskogens regeneration. (Summary : The primitive forests of Granskar and Fiby. A study of the part played by storm-gaps and dwarf trees in the regeneration of the Swedish spruce forest.) : (14:-). ISBN R. Sterner, Flora der Insel Gland. Die Areale der Gefasspflanzen Glands nebst Bemerkungen zu ihrer Oekologie und Soziologie :- (14:-). ISBN B. Lindquist, Dalby Soderskog. En sklmsk lovskog i forntid och nutid. (Zusammenf. : Ein Laubwald in Schonen in der Vergangenheit und Gegenwart.) :- (18:-). ISBN N. Stalberg, Lake Vattern. Outlines of its natural history, especially its vegetation :- (8:-). ISBN G.E. Du Rietz, A.G. Hannerz, G. Lohammar, R.. Santesson & M. Wcern, Zur Kenntnis der Vegetation des Sees Takern :- (8:-). ISBN Viixtgeografiska studier tilliignade Car! Skoltsberg pa sextioarsdagen 1/ ( Geobotanical studies dedicated to C. Skottsberg.) :- (24:-). ISBN N. Hy lander, De svenska formerna av Mentha gentilis L. coli. (Zusammenf. : Die schwedischen Formen der Mentha gentilis L. sensu cot!.) :- (8:-). ISBN T. E. Hasselrot, Till kannedomen om nagra nordiska umbilicariaceers utbredning. (Zusammenf. : Zur Kenntnis der Verbreitung einiger U mbilicariaceen in Fennoscandia.) :- (8:-). ISBN X. 16. G. Samuelsson, Die Verbreitung der Alchemilla-Arten aus der Vulgaris-Gruppe in Nordeuropa : (12:-). ISBN I 7. Th. A rwidsson, Studien iiber die Gefasspflanzen in den Hochgebirgen der Pite Lappmark : (18:-). ISBN N. Dahlbeck, Strandwiesen am siidostlichen Gresund. (Summary : Salt marshes on the S.E. coast of Gresund.) :- (12:-). ISBN E. von Krusenstjerna, Bladmossvegetation och bladmossflora i Uppsalatrakten. (Summary : Moss flora and moss vegetation in the neighbourhood of Uppsala.) :- (18:-). ISBN N. Albertson, Gsterplana hed. Ett alvaromrade pa Ki nnekulle. (Zusammenf. : Gsterplana hed. Ein Alvargebiet auf dem Kinnekulle.) :- (18 :-). ISBN H. Sjdrs, Myrvegetation i Bergslagen. (Summary : Mire vegetation in Bergslagen, Sweden.) : (24:-). ISBN S. A hlner, Utbredningstyper bland nordiska barrtradslavar. (Zusammenf. : Verbreitungstypen unter fennoskandischen N adelbaumflechten.) : (20:-). ISBN E. Julin, Vessers udde. Mark och vegetation i en igenvaxande lovang vid Bj arka-saby. (Zusammenf.: Vessers udde. Boden und Vegetation in einer verwachsenden Laubwiese bei Bj arka-saby in Gstergotland, Siidschweden.) :-(1 4:-). ISBN M. Fries, Den nordiska utbredningen av Lactuca alpina, Aconitum septentrionale, Ranunculus platanifolius och Polygonatum verticillatum. (Zusammenf. : Die nordische Verbreitung von Lactuca alpina...) :- (10:-). ISBN Gjcerevoll, Sn0leievegetasjonen i Oviksfjellene.,(Summary : The snow-bed vegetation of Mts Oviksf] allen, Jamtland, Sweden.) :- (12:-). ISBN H. Osvald, Notes on the vegetation of British and Irish mosses :- (8:-). ISBN S. Selander, Floristic phytogeography of South Western Lule Lappmark (Swedish Lapland) I :- (14 :-). ISBN S. Selander, Floristic phytogeography of South Western Lule Lappmark (Swedish Lapland) 11. Karlvaxtfloran i sydvastra Lule Lappmark. (Summary : Vascular flora.) :- (12:-). ISBN M. Fries, Pollenanalytiska vittnesbord o m senkvartar vegetationsutveckling, sarskilt skogshistoria, i nordvastra Gotaland. (Zusammenf.: Pollenanalytische Zeugnisse der spatquartaren Vegetationsentwicklung, hauptsachlich der Waldgeschichte, im nordwestlichen Gotaland, Siidschweden.) :- (14:-). ISBN X. 30. M. Wcern, Rocky-shore algae in the Gregrund Archipelago :- (22:-). ISBN Rune, Plant life on serpentines and rel ted rocks in the North of Sweden :- (12:-). ISBN I I. 32. P. Kaaret, Wasservegetation der Seen Orlangen und Trehorningen :- (8:-). ISBN X. 33. T. E. Hasselrot, Nordliga lavar i Syd- och Mellansverige. (Nordliche Flechten in Siid- und Mittelschweden.) :- (14:-). ISBN H. Sjdrs, Slatterangar i Grangiirde finnmark. (Summary : Meadows in Grangarde Finnmark, SW. Dalarna, Sweden.) :- (12:-). ISBN S. Ki/ander, Karlvaxternas ovre granser pa fj all i sydvastra J amtland samt an grans an de delar av Harj edalen och Norge. [Summary : Upper limits of vascular plants on mountains in Southwestern Jamtland and adjacent parts of Harjedalen (Sweden) and Norway.] :- (14:-). ISBN

138 Distributor: Svenska Viixtgeografiska Siillskapet, Box 559, S Uppsala, Sweden 36. N. Quennerstedt, Diatomeerna i Limgans sjovegetation. (Summary : Diatoms in the lake vegetation of the Langan drainage area, Jiimtland, Sweden.) :- (14 :-). ISBN M.-B. Florin, Plankton of fresh and brackish waters in the Sodertiilje area :- (14:-). ISBN : 38. M.-B. Flo rin, lnsjostudier i Mellansverige. Mikrovegetation och pollenregn i vikar av Gstersjobiickenet och insjoar fran preboreal tid till nutid. (Summary : Lake studies in Central Sweden. Microvegetation and pollen rain in inlets of the Baltic basin and in lakes from Preboreal time to the present day.) : (6 :-). ISBN M. Fries, Vegetationsutveckling och odlingshistoria i V arnhemstrakten. En pollenan alytisk undersokning i V iistergotland. [Z usammenf. : V egetationsentwicklung und Siedlungsgeschichte im Gebiet von Varnhem. Eine pollenanalytische Untersuchung aus Viistergotland (Slidschweden).] :- (10:-). ISBN Bengt Pettersson, Dynamik och konstans i Gotlands flora och vegetation. (Resume: Dynamik und Konstanz in der Flora und Vegetation von Gotland, Schweden.) :- (27:-). ISBN E. Uggla, Skogsbrandfiilt i Muddus nationalpark. (Summary : Forest fire areas in Muddus National Park, Northern Sweden.) :- (14:-). ISBN K. Thomas son, N ahuel Huapi. Plankton of some lakes in an Argentine National Park, with notes on terrestrial vegetation :- (14:-). ISBN V. Gillner, Vegetations- und Standortsuntersuchungen in den Strandwiesen der schwedischen Westkliste :- (22:-). ISBN E. Sjogren, Epiphytische Moosvegetation in Laubwiildern der Insel Gland, Schweden. (Summary : Epiphytic moss communities in deciduous woods on the island of Gland, Sweden.) :- (16:-). ISBN (ISBN ). 45. G. Wistrand, Studier i Pite Lappmarks kiirlviixtflora, med siirskild hiinsyn till skogslandet och de isolerade fj iillen. (Z usammenf.: Studien U ber die Gefiisspflanzenflora der Pite Lappmark mit besonderer Berlicksichtigung des Waldlandes und der isolierten niederen Fjelde.) :- (24 :-). ISBN (ISBN ). 46. R. Ivarsson, Lovvegetationen i Mollosunds sock en. (Zusammenf.: Die Laubvegetation im Kirchspiel Mollosund, Bohusliin, Schweden.) :- (20:-). ISBN X (ISBN ) K. Thomasson, Araucanian Lakes. Plankton studtes in North Patagonia, with notes on terrestrial vegetation :- (24 :-). ISBN E. Sjogren, Epilithische und ej?igiiische Moosvegetation in Laubwiildern der Insel Oland, Schweden. (Summary : Epilithic and epigeic moss vegetation in deciduous woods on the island of Gland, Sweden.) :- (27:-). ISBN (ISBN ) Hedberg, Features of afroalpine plant ecology. Resume franc;ais :- (24 :-). ISBN (ISBN X). 50. The Plant Cover of Sweden. A study dedicated to G. Einar Du Rietz on his 70th birthday by his pupils :- (48:-). ISBN I. T. Flensburg, Desmids and other benthic algae of Lake Kiivsjon and Store Mosse, SW Sweden : (26:-). ISBN (ISBN ). 52. E. Skye, Lichens and air pollution. A study of cryptogamic epiphytes and environment in the Stockholm region :- (28 : -). ISBN (ISBN X). 53. Jim Lundqvist, Plant cover and environment of steep hill-sides in Pite Lappmark. (Resume: La couverture vegeta!e et!'habitat des flancs escarpes des collines de Pite Lappmark.) :- (32:-). ISBN (ISBN ). 54. Conservation of Vegetatioil in Africa South of the Sahara. Proc. of sixth plen. meeting of AETF AT. Ed. by Inga and Olov Hedberg :- ( 40:-), cloth 70:- (47:-). ISBN (ISBN ). 55. L.-K. Ko1 (gsson, The Holocene history of the Great Alvar of Oland :- (36:-). ISBN (ISBN ). 56. H.P. Hallberg, Vegetation auf den Schalenablagerungen in Bohusliin, Schweden. (Summary : Vegetation on shell deposits in Bohusliin, Sweden.) : (3 2:-). ISBN (ISBN ). 57. S. Fransson, Myrvegetation i sydviistra Viirmland. (Summary : Mire vegetation in south-western Viirmland, Sweden.) :- (28:-). ISBN (ISBN ). 58. G. Wa!lin, Lovskogsvegetation i Sjuhiiradsbygden. (Summary : Deciduous woodlands in Sjuhiiradsbygden, V iistergotland, south-western Sweden.) :--(28:-) ISBN (ISBN ). 59. D. Johansson, Ecology of vascular epiphytes in West African rain forest. (Resume: Ecologie des epiphytes vasculaires dans la foret dense humide d'afrique occidentale.) :-. ISBN (ISBN ). Limited numbers of cloth-bound copies of Acta 44, 45, 46, 48, 49, 51, 52, 53, 55, 56, 57, 58, 59 are available through the Society at an additional cost of 10:- per copy. ISBN nos. in brackets refer to cloth-bound copies. V AXTEKOLOGISKA STUDIER 1. S. Brakenhielm & T. fngeldg, Vegetationen i Kungshamn-Morga naturreservat med fo rslag till skotselplan. (Summary : Vegetation and proposed management in the Kungshamn-Morga Nature Reserve sout of Uppsala.) :-. ISBN T. Ingelog & M. Risling, Kronparken vid Uppsala, hi storik och bestandsanalys av en 300-arig tallskog. (Summary : Kronparken, history and analysis of a 300- year-old pinewood near Uppsala, Sweden.) :-. ISBN H. Sjors och medarb., Skyddsvarda myrar i Kopparbergs!an. (Summary : Mires considered for protection in Kopparberg County (Prov. Dalarna, Central Sweden.) :-. ISBN L. Karlsson, Autecology of cliff and scree plants in Sarek National Park, northern Sweden :-. ISBN

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141 SVENSKA V AXTGEOGRAFISKA SALLSKAPET SOCIETAS PHYTOGEOGRAPHICA SUECANA A dress: Vaxtbiologiska institutionen, Box 559, S Uppsala, Sweden Sallskapet bar till andamru att vacka och underhrula intresse for vaxtgeografien i vidstracktaste mening, att framja utforskandet av flora och vegetation i Sverige och andra lander och att havda geobotanikens praktiska och vetenskapliga betydelse. Sallskapet anordnar sammankomster och exkursioner samt utger tva publikationsserier. Medlemskap kan erhallas efter anmalan hos sekreteraren. Foreningar, bibliotek, laroanstalter och andra institutioner kan inga som abonnenter. Arsavgift 24 kr (18 :- for studerande); standigt medlemskap 400 kr. Sa.IIskapet utger arligen Acta Phytogeographica Suecica. Medlemmar och abonnenter erhaller arets Acta mot postforskott pa arsavgiften jamte porta och expeditionskostnader. De kan ocksa forvarva aldre publikationer tili nedsatt pris (parentespriset i Acta-listan). Vissa ar utges extraband av Acta, som erhalls mot en tillaggsavgift. Sallskapet utger ocksa den ickeperiodiska serien Vaxtekologiska studier. Den kan f6rvarvas efter bestallning eller genom staende abonnemang hos Sallskapet. Bada serierna kan ocksa erhrulas i byte mot andra publikationer efter hanvandelse till Vaxtbiologiska institutionens bibliotek. The object of the Society is to promote investigation in flora and vegetation,. their history and their ecological background. Through publication of monographs, and other activities, the Society tries to stimulate geobotanical research and its application to practical and scientific problems. Membership is open to all who have a personal interest in the advancement of phytogeography. Individu members and subscribers (societies, institutes, libraries, etc.) receive the Acta Phytogeographica Suecica for annual dues of 24 Skr plus postage. There are additional fees in years when more than one volume are issued. Permanent membership. 400 Skr. For membership ple se apply to the Secretary. Back volumes may be obtained by members and subscribers at reduced cost (see list of publications, prices in brackets). The Society also issues Viixtekologiska studier, which appear irregularly and are available upon request or standing order. Both series can be received by exchange for other scientific publications. Please apply to the Institute Library (address as above). ISBN