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ABSTRACT Various economically important tropical tree species are not well known biologically. We studied the floral and fruit biology of Allariblackia stuhlmannii (Clusiaceae), a dioecious tree species endemic to the Eastern Arc... more
ABSTRACT Various economically important tropical tree species are not well known biologically. We studied the floral and fruit biology of Allariblackia stuhlmannii (Clusiaceae), a dioecious tree species endemic to the Eastern Arc Mountains of Tanzania and Kenya that has become the subject of recent interest by the food industry because of the edible oil that can be extracted from the seeds. We characterised qualitative and quantitative similarities and differences between male and female flowers, the flowering and fruiting phenology, and examined the relationship between fruit crop production and tree size, seeds per fruit, and seed number as a function of fruit mass. There was no significant difference in sugar concentration of nectar between male and female flowers, but male flowers contained significantly more nectar than female flowers. Male trees had larger flowering displays with a tendency for the population to mast profusely between January and March, which coincided with the peak fruiting period. The fruiting period was pronounced from January to March, which appeared to be preceded by a smaller peak in October. Fruit crop was strongly related to tree size, with mean seed number per fruit being 38. Seed quantity per fruit showed a trend to increase with fruit mass, but this relationship was not significant. General physical resemblance of female flowers to male flowers, the latter of which offer multiple floral cues to attract pollinators, suggests a pollination-by-deceit strategy. Our results provide important insights on the natural history of this tree species and carry implications for its future use.
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Abstract Three new species and one new subspecies are described in Barleria sect. Somalia (Acanthaceae) from western Tanzania and their affinities are discussed. The conservation status of each species is evaluated.
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Reduction in flow of the Lower Kihansi River, Tanzania, caused by implementation of a hydropower project in May 2000 has the potential to lead to changes in vegetation composition of spray maintained wetlands. These wetlands are the only... more
Reduction in flow of the Lower Kihansi River, Tanzania, caused by implementation of a hydropower project in May 2000 has the potential to lead to changes in vegetation composition of spray maintained wetlands. These wetlands are the only known habitat for the Kihansi Spray Toad, Nectophrynoides asperginis. In this paper, change over time is assessed by comparing samples taken in
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ABSTRACT Fourteen microsatellite loci were isolated from Mesogyne insignis, a threatened, African understory tree. Alleles ranged between two and eight per locus, with expected heterozygosity ranging from 0.063 to 0.845 and observed... more
ABSTRACT Fourteen microsatellite loci were isolated from Mesogyne insignis, a threatened, African understory tree. Alleles ranged between two and eight per locus, with expected heterozygosity ranging from 0.063 to 0.845 and observed heterozygosity ranging from 0.000 to 0.733. One locus departed from Hardy–Weinberg equilibrium leaving 13 polymorphic loci that will be used to study the genetic variability of fragmented populations so as to enhance the species conservation efforts.
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Information on study area and focal tree species, with supplementary details on methods and results.
<p>Records of non-medicinal uses for African trees. The data come from a variety of published sources which are all referenced. There is a separate dataset for detailed medicinal uses.</p
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<p>This contains records of the growth form (habit) of African trees as described by various sources. The data come from a variety of published sources which are all referenced.</p
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Ongoing habitat loss and fragmentation alter the functional diversity of forests. Generalising the magnitude of change in functional diversity of fragmented landscapes and its drivers is challenging because of the multiple scales at which... more
Ongoing habitat loss and fragmentation alter the functional diversity of forests. Generalising the magnitude of change in functional diversity of fragmented landscapes and its drivers is challenging because of the multiple scales at which landscape fragmentation takes place. Here we propose a multi-scale approach to determine whether fragmentation processes at the local and landscape scales are reducing functional diversity of trees in the East Usambara Mountains, Tanzania. We employ a structural equation modelling approach using five key plant traits (seed length, dispersal mode, shade tolerance, maximum tree height, and wood density) to better understand the functional responses of trees to fragmentation at multiple scales. Our results suggest both direct and indirect effects of forest fragmentation on tree functional richness and evenness. A reduction in fragment area appears to exacerbate the negative effects resulting from an increased amount of edge habitat and loss of shape c...
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The breeding season diet and nesting characteristics of the Silvery-cheeked Hornbill Bycanistes brevis are poorly known. To further understand these aspects of the breeding biology of this hornbill species, 14 nests were studied in and... more
The breeding season diet and nesting characteristics of the Silvery-cheeked Hornbill Bycanistes brevis are poorly known. To further understand these aspects of the breeding biology of this hornbill species, 14 nests were studied in and around Amani Nature Reserve located in the East Usambara Mountains, Tanzania. Nesting tree species were identified and the diet composition of nesting hornbills was evaluated between July and November 2001. The ejecta from each nest were collected, inventoried, identified (as completely as possible) and enumerated. Food items were categorised as plant, vertebrate or invertebrate. Plants, represented largely by fruits, were the dominant food type (n = 861), followed by invertebrates (n = 306; mainly millipedes and beetles), and vertebrates (n = 15; mainly smaller birds and chameleons). A comparison of results from the current study to other nesting observations made approximately seven decades earlier in the same area suggest that (1) the invasive tree species Maesopsis eminii, which was the most common food type consumed (n = 4 539 seeds), has become a favoured new food source in the breeding season, and (2) the breeding season appears to have shifted to an earlier period, potentially due to the fruiting phenology and abundance of Maesopsis eminii.
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Abstract Three new species and one new subspecies are described in Barleria sect. Somalia (Acanthaceae) from western Tanzania and their affinities are discussed. The conservation status of each species is evaluated.
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... Typus: Tanzania, Udzungwa Scarp Forest Reserve, Frimodt-Moller, Horlyck, JOker & Mikkelsen 120 (holotypus C; isotypi DSM, K). Dioecious understorey tree 3 - 10 m high, with more or less pendant branches; bole slender, up to 15 cm... more
... Typus: Tanzania, Udzungwa Scarp Forest Reserve, Frimodt-Moller, Horlyck, JOker & Mikkelsen 120 (holotypus C; isotypi DSM, K). Dioecious understorey tree 3 - 10 m high, with more or less pendant branches; bole slender, up to 15 cm in diameter at breast height, without ...
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ABSTRACT Fourteen microsatellite loci were isolated from Mesogyne insignis, a threatened, African understory tree. Alleles ranged between two and eight per locus, with expected heterozygosity ranging from 0.063 to 0.845 and observed... more
ABSTRACT Fourteen microsatellite loci were isolated from Mesogyne insignis, a threatened, African understory tree. Alleles ranged between two and eight per locus, with expected heterozygosity ranging from 0.063 to 0.845 and observed heterozygosity ranging from 0.000 to 0.733. One locus departed from Hardy–Weinberg equilibrium leaving 13 polymorphic loci that will be used to study the genetic variability of fragmented populations so as to enhance the species conservation efforts.
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Background/Question/Methods Harvest of non-timber forest products such as seeds requires assessment to determine if it is sustainable. Allanblackia stuhlmannii (Clusiaceae) is a rainforest tree with seeds that are harvested for an... more
Background/Question/Methods Harvest of non-timber forest products such as seeds requires assessment to determine if it is sustainable. Allanblackia stuhlmannii (Clusiaceae) is a rainforest tree with seeds that are harvested for an emerging commercial market. Seeds that are not collected by humans are mostly scatterhoarded by giant pouched rats (Cricetomys gambianus). Two simultaneous experiments were conducted in twelve 50x50m plots within the Amani Nature Reserve: a seed tagging experiment that followed fates of 1152 seeds (in two rounds of 576 seeds each), and a seed planting experiment that followed fates (until disappearance) for 960 seeds (in two rounds). We recorded fruit abundance in each plot throughout the fruiting season and followed seed fate for approximately one year. This presentation will address the goal of determining how seed removal and fate vary with background seed abundance for experimentally planted seeds. We use generalized additive models to investigate the ...
Various economically important tropical tree species are not well known biologically. We studied the floral and fruit biology of Allanblackia stuhlmannii (Clusiaceae), a dioecious tree species endemic to the Eastern Arc Mountains of... more
Various economically important tropical tree species are not well known biologically. We studied the floral and fruit biology of Allanblackia stuhlmannii (Clusiaceae), a dioecious tree species endemic to the Eastern Arc Mountains of Tanzania and Kenya that has become the subject of recent interest by the food industry because of the edible oil that can be extracted from the seeds. We characterised qualitative and quantitative similarities and differences between male and female flowers, the flowering and fruiting phenology, and examined the relationship between fruit crop production and tree size, seeds per fruit, and seed number as a function of fruit mass. There was no significant difference in sugar concentration of nectar between male and female flowers, but male flowers contained significantly more nectar than female flowers. Male trees had larger flowering displays with a tendency for the population to mast profusely between January and March, which coincided with the peak fru...
Background/Question/Methods An international market is emerging for oil-rich seeds from the African tree genus Allanblackia. Allanblackia stuhlmannii (Clusiaceae) is a canopy tree endemic to the Eastern Arc Mountains of Tanzania.... more
Background/Question/Methods An international market is emerging for oil-rich seeds from the African tree genus Allanblackia. Allanblackia stuhlmannii (Clusiaceae) is a canopy tree endemic to the Eastern Arc Mountains of Tanzania. Recently, humans have begun heavily collecting seeds throughout the Amani Nature Reserve (ANR) in spite of its prohibition, and there is concern that illegal seed harvest will diminish the regeneration of Allanblackia over the long term. The objective of this project was to determine how Allanblackia seed fate and dispersal varies under different levels of seed availability. Twelve 50 by 50 m plots containing at least 4 fruit-bearing trees were established in ANR. Seed addition within plots was recorded by counting the number of fresh fruits during each visit to the plot. Within each plot, removal trials were conducted at seed stations containing 16 seeds each. Each seed was weighed and marked with a wire, flag, and thread bobbin to aid in the post-dispersa...
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ABSTRACT Various economically important tropical tree species are not well known biologically. We studied the floral and fruit biology of Allariblackia stuhlmannii (Clusiaceae), a dioecious tree species endemic to the Eastern Arc... more
ABSTRACT Various economically important tropical tree species are not well known biologically. We studied the floral and fruit biology of Allariblackia stuhlmannii (Clusiaceae), a dioecious tree species endemic to the Eastern Arc Mountains of Tanzania and Kenya that has become the subject of recent interest by the food industry because of the edible oil that can be extracted from the seeds. We characterised qualitative and quantitative similarities and differences between male and female flowers, the flowering and fruiting phenology, and examined the relationship between fruit crop production and tree size, seeds per fruit, and seed number as a function of fruit mass. There was no significant difference in sugar concentration of nectar between male and female flowers, but male flowers contained significantly more nectar than female flowers. Male trees had larger flowering displays with a tendency for the population to mast profusely between January and March, which coincided with the peak fruiting period. The fruiting period was pronounced from January to March, which appeared to be preceded by a smaller peak in October. Fruit crop was strongly related to tree size, with mean seed number per fruit being 38. Seed quantity per fruit showed a trend to increase with fruit mass, but this relationship was not significant. General physical resemblance of female flowers to male flowers, the latter of which offer multiple floral cues to attract pollinators, suggests a pollination-by-deceit strategy. Our results provide important insights on the natural history of this tree species and carry implications for its future use.
Research Interests: Biology and Pollination
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Research Interests: Environmental Science, Africa, Carbon Dioxide, Carbon, Biomass, and 15 moreMedicine, Multidisciplinary, Nature, Global change, Atmosphere, Tropical forest, Carbon Storage, Trees, Carbon Stock, Long Term Monitoring, Tropical Climate, Atmospheric Carbon Dioxide, Carbon Sink, Resource Availability, and Confidence Interval
We isolated 20 trinucleotide microsatellites from two African tree species: Sorindeia madagascariensis (nine microsatellites) and Leptonychia usambarensis (11 microsatellites). Number of alleles ranged from three to seven in Sorindeia and... more
We isolated 20 trinucleotide microsatellites from two African tree species: Sorindeia madagascariensis (nine microsatellites) and Leptonychia usambarensis (11 microsatellites). Number of alleles ranged from three to seven in Sorindeia and two to 10 in Leptonychia. Observed heterozygosity ranged from 0.025 to 0.829 for Sorindeia and from 0.226 to 0.933 for Leptonychia. Two loci from each species departed from Hardy-Weinberg equilibrium. These microsatellite markers will be used to study how forest fragmentation affects pollination and seed dispersal processes of these tree species.
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We isolated 20 trinucleotide microsatellites from two African tree species: Sorindeia madagascariensis (nine microsatellites) and Leptonychia usambarensis (11 microsatellites). Number of alleles ranged from three to seven in Sorindeia and... more
We isolated 20 trinucleotide microsatellites from two African tree species: Sorindeia madagascariensis (nine microsatellites) and Leptonychia usambarensis (11 microsatellites). Number of alleles ranged from three to seven in Sorindeia and two to 10 in Leptonychia. Observed heterozygosity ranged from 0.025 to 0.829 for Sorindeia and from 0.226 to 0.933 for Leptonychia. Two loci from each species departed from Hardy-Weinberg equilibrium. These microsatellite markers will be used to study how forest fragmentation affects pollination and seed dispersal processes of these tree species.
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Three new naphthylisoquinoline alkaloids, the... more
Three new naphthylisoquinoline alkaloids, the 7,3&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;#39;-coupled ancistrotanzanine C (6), the 5,1&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;#39;-coupled O-methylancistrocladinine (7), and the likewise 5,1&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;#39;-coupled O,N-dimethylancistrocladine (8, previously known only as a partial-synthetic compound), have been isolated from the highland liana Ancistrocladus tanzaniensis, along with the two known 7,3&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;#39;-coupled naphthylisoquinoline alkaloids ancistrocladidine (4) and ancistrotectorine (5). All of the compounds are S-configured at C-3 and bear an oxygen at C-6, and thus belong to the so-called Ancistrocladaceae type, similar to 1-3 previously isolated from this newly discovered plant species. The structural elucidation was achieved by chemical, spectroscopic, and chiroptical methods. The biological activities of the alkaloids against the pathogens causing malaria tropica, leishmaniasis, Chagas&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;#39; disease, and African sleeping sickness were evaluated.