Landscape and Urban Planning 100 (2011) 251–267
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Landscape and Urban Planning
journal homepage: www.elsevier.com/locate/landurbplan
Alien plant species dominate the vegetation in a city of Sub-Saharan Africa
Joseph Bigirimana a,b,∗ , Jan Bogaert a , Charles De Canniere a , Jean Lejoly a , Ingrid Parmentier c
a
Université Libre de Bruxelles, Research group of Landscape Ecology and Plant production Systems CP 169, 50 Av. F. Roosevelt, 1050 Brussels, Belgium
Ecole Normale Supérieure du Burundi, Département des Sciences Naturelles, BP 6983 Bujumbura, Burundi
c
Université Libre de Bruxelles, Evolutionary Biology & Ecology, CP 160/12, 50 Av. F. Roosevelt, 1050 Brussels, Belgium
b
a r t i c l e
i n f o
Article history:
Received 27 April 2010
Received in revised form
17 December 2010
Accepted 23 December 2010
Keywords:
Biological homogenisation
Bujumbura
Burundi
Invasive plants
Urban ecology
Urbanization
a b s t r a c t
Although many African cities are confronted to an important population growth, there are almost no
studies describing their vegetation and how it is affected by the urbanization process. We present here
the description of the spontaneous vegetation of the capital city of Burundi, Bujumbura, through the
analysis of 437 vegetation plots. Ruderal plant assemblages dominate in the most urbanized areas while
in the outskirts of the city, the vegetation shows similarities to natural plant assemblages in the region.
The variability of the plant assemblages is further influenced by the degree of shade, the presence of a
permanent source of humidity and trampling by humans and cattle. Over the 404 species recorded in the
plots, 57% are native and 43% are introduced. Sixty percent of the 173 introduced species originate from
tropical America. It is very likely that in the future, if no biodiversity conservation measures are taken,
the urbanization process will lead to the homogenisation of the vegetation in favour of ruderal plant
assemblages and introduced species. Similarly to what is done in temperate countries, urban planners in
African cities should take measures to preserve the last patches of semi-natural vegetation, not only for
their conservation value, but also for the diversity of services they offer to the population.
© 2011 Elsevier B.V. All rights reserved.
1. Introduction
Urbanization is a major driver of landscape transformation,
leading to the conversion of land from wild and agricultural uses to
urban and suburban occupancy (Pickett et al., 2001). The urbanization process has many consequences on ecosystems such as habitat
fragmentation, air, water and soil pollution, disruption of hydrological systems, alteration of energy flow and of nutrient cycling
(Williams et al., 2009). This impacts the biodiversity and raises
several questions such as how the city influences adjacent ecosystems, how to maximize biodiversity within the urban ecosystem
and how to manage undesirable species (Savard et al., 2000). Unexpectedly, most cities are richer in species than surrounding areas
(Araújo, 2003). As an example, Brussels, the capital city of Belgium,
counts 671 angiosperm species, which is half the number of species
present in the country (Godefroid, 2001; Ricotta et al., 2010). This is
due to both deliberate and accidental introductions of non-native
species, but also to natural factors because most cities were build
∗ Corresponding author at: Université Libre de Bruxelles, Research group of Landscape Ecology and Plant production Systems, CP 169, 50 Av. F. Roosevelt, 1050
Brussels, Belgium. Tel.: +32 2 650 21 32; fax: +32 2 650 21 25.
E-mail addresses: jbigirim@ulb.ac.be, bigjos5@yahoo.fr (J. Bigirimana),
Jan.Bogaert@ulb.ac.be (J. Bogaert), cdecanni@ulb.ac.be (C. De Canniere),
jlejoly@ulb.ac.be (J. Lejoly), inparmen@ulb.ac.be (I. Parmentier).
0169-2046/$ – see front matter © 2011 Elsevier B.V. All rights reserved.
doi:10.1016/j.landurbplan.2010.12.012
up in areas of natural heterogeneity which supports natural biodiversity (Fjeldsa and Burgess, 2008; Kuhn et al., 2004). However,
it is crucial to determine whether plant species are indigenous or
not. Indeed, urbanization reduces the diversity and abundance of
indigenous species, because of the homogenisation of the habitat (McKinney, 2006). Along a gradient from the city outskirts to
the centre, native species are replaced by widespread “weedy”
non-native species (some of which are invasive) well adapted to
anthropized habitats (Kowarik, 1995; Kuhn and Klotz, 2006). This
biodiversity loss is often accompanied by a negative economical impact (Williamson, 1996). However, the species richness and
abundances of plants along an urban to rural gradient cannot be
explained by a simple distance-related succession of native and
non-native species (Brunzel et al., 2009; Kinzig et al., 2005). Indeed,
this distance is a surrogate for other causal mechanisms, such as
disturbances and dispersal, which are varying according to the
socioeconomic and cultural characteristics of the residential areas
(e.g. human mobility patterns, traditional gardening practices . . .).
Studies about invasive and introduced species have been
numerous in the fields of biogeography and conservation ecology
these two last decennia, but with an under-representation of studies from Asia and Africa (Pyšek et al., 2008). Cilliers and Bredenkamp
(2000) studied the roadside vegetation along an urbanization gradient in South Africa. Plant assemblages varied according to the
degree of humidity, soil types, the use of adjacent areas, the level
of perturbations, the use of herbicide, trampling and the time since
252
J. Bigirimana et al. / Landscape and Urban Planning 100 (2011) 251–267
Fig. 1. Distribution of the four main plant assemblages in the vegetation of Bujumbura (TF1, TF2, TF3, TF4, see Table 1) (a) in relation with soil types according to Kabeya
(1992) and (b) urbanization degree according to Sindayihebura (2003). Soil types: sand (1), swamps with swelling clay (2), clay (3), clay + sand (4), clay + sand + silt (5),
clay + silt (6), alterites and limonite material (7), no data (8).
the road was constructed. They counted 26% of introduced species,
mainly from South America but also from Europe and Asia. In Kenya,
Stadler et al. (2000) analyzed the distribution of native and introduced species in 20 ecogeographical zones. The regions richest in
species were also those with most introduced species. The area
around the capital city Nairobi had the highest overall species richness and also the highest number of introduced species, originating
mainly from Europe and America. In central Africa, to our knowledge, the only existing study is the 1982 PhD thesis by Mutabana
Nyakabwa on the plant assemblages of the urban ecosystem of
Kisangani (D. R. Congo). The author describes 60 plant assemblages
and lists 1338 species. This large number of species can be explained
by the diversity of biotopes in the city. Most of these species were
largely distributed within the tropical regions of the world.
We present here the first detailed analysis of the urban vegetation in Burundi. This country has a high population density (354
hab./km2 ) and a growing population (growth rate 3.6% in 2010).
Although the population density in Burundi is less than that of its
neighbour Rwanda (420 hab./km2 ), it is much higher than that in
most other countries in Sub-Saharan Africa (Tanzania: 44 hab./km2 ,
D. R. Congo: 30 hab./km2 , CIA, 2010). Already 10% of the population
in Burundi is urban and the rate of urbanization (2005–2010) is 6.8%
(CIA, 2010).
So far, no description of Bujumbura’s flora and vegetation exists,
although it is essential to foreseen the effects of the urbanization
process on the urban ecosystem and its surroundings and to take
appropriate management measures. Specifically, we will answer
the following questions:
(a) Which are the different plant assemblages in the vegetation of
Bujumbura? Is their variability determined by natural ecological factors and/or by human induced factors?
(b) What are the ecology and the geographical distribution of the
species composing these plant assemblages? What is the proportion of introduced species in the vegetation and what is the
geographical origin of these species?
(c) What is the conservation value of the vegetation of Bujumbura?
2. Materials and methods
2.1. Study area
Bujumbura is the capital city of Burundi (Fig. 1). It is located in
the western part of the country (29◦ 36′ E 3◦ 40′ S) on the shore of
Lake Tanganyika. The city’s extent was around 146 km2 in 2003
(Sindayihebura, 2003). The latest population census, realized in
2008, indicates that 478 155 people live permanently in the city
(Présidence de la Répubique du Burundi, 2009). Altitude varies from
777 m at the lake shore to 1100 m in the eastern part of the city,
at the foot of the Miwa Mounts. Climate is tropical with one dry
season (May–September) and one rainy season (October–April).
Mean annual temperature varies between 23 and 25 ◦ C and mean
annual precipitation between 800 and 1300 mm. During 4 months
(June–September), mean monthly precipitation is below 50 mm.
Natural vegetation in the region (excluding wetlands) has almost
disappeared and is only maintained in the Rusizi National Park. It
includes savannah, miombo and sclerophyllous forests (Reekmans,
1980). Elsewhere, natural vegetation has mostly been replaced by
fields and fallows. This is a rather recent evolution: in 1950 the
Rusizi Plain still had a very natural character (Reekmans, 1980).
Vegetation covers half of the territory of Bujumbura, mostly in the
suburb. But even inside the more densely urbanized part of the city,
there are unconstructed areas covered by spontaneous vegetation.
J. Bigirimana et al. / Landscape and Urban Planning 100 (2011) 251–267
Soils in Bujumbura originate from sediments deposited by the
rivers or by the Tanganyika Lake and piedmont colluvial deposits
from the Mirwa Mountain. This results in a mosaic of different soil
types (Fig. 1a). The northern section of river Ntahangwa and its surroundings is characterized by a dominance of clay, its southern section by a mix of sand and clay. The shore of Lake Tanganyika is composed of sandy soils and sand dunes. At the foot of the Miwa Mounts,
soils are mainly composed of alterites and colluvial deposits.
According to the phytogeographical classification of White (1983),
Bujumbura belongs to the Lake Victoria Regional Mosaic. It is
located at the intersection of several phytochoria and consequently,
most species are also distributed in the adjacent regions.
2.2. Data collection
Field data was collected from 2005 to 2007, between February and June in unconstructed land inside the city limits, in the
terra firme vegetation. Plots were established within homogeneous
patches of vegetation. In each plot, all angiosperm and pteridophyte species were listed. The investigated area was increased until
almost no new species could be added, or until the entire continuous patch was investigated. Plot area is therefore variable (average
surface 42 ± 32 m2 , min = 4 m2 , max = 150 m2 ). Species abundances
were scored in the plot using the Braun-Blanquet scale (BraunBlanquet et al., 1932). At least one specimen of each species that
could not be identified with certainty on the field was deposited in
the herbarium of the Université Libre de Bruxelles (BRLU) and in
that of the Université du Burundi (UB). There are 1255 herbarium
samples in this reference collection. The Angiosperms nomenclature follows African Plants Database (2009) and the Tropicos.org.
(2009). Family names are those of the Angiosperm Phylogeny
Group II classification (Stevens, 2003). For each plot, the habitat
type (agricultural fallow, savannah, ruderal habitat), the degree of
trampling by man and/or cattle (low, medium of high), the presence of shade (yes/no), and the existence of a permanent source of
humidity (yes/no) were noted.
The geographical coordinates of the plot have been projected
on a soil map (Kabeya, 1992) and on an urbanization map
(Sindayihebura, 2003).
2.3. Data analyses
The main floristic gradients were identified with a Detrended
Correspondence Analysis of the vegetation plots (DCA, Jongman
et al., 1995). The environmental variables measured on the field
were added as passive variables to this analysis. DCA was preferred
to CA because of a strong arch effect. To test the relative influence of
human induced factors and natural ecological factors on the plant
assemblages, we realized a variance partitioning (Borcard et al.,
1992), using partial canonical correspondence analysis (CCA, Ter
Braak, 1986). The ordinations (DCA, CCA and partial CCA) were realized with Canoco for Windows 4.5 (Ter Braak and Smilauer, 2002).
The natural ecological factors included soil type, the humidity level
and the shade level and the human induced factors included the
degree of urbanization and the degree of trampling by humans or
cattle. Partial Monte Carlo permutation tests were used to assess
the statistical significance of each natural ecological factor and
human induced factors before introducing them in the ordination
model (forward selection, Ter Braak and Smilauer, 2002). To partition the variance, we realized four separate CCA using: (1) species
and natural ecological factors; (2) species and human induced
factors; (3) species and human induced factors with natural ecological data as covariables; and (4) species and natural ecological
factors with human induced factors as covariables. In this variance
partitioning analysis, we used the same number of statistically
significant natural ecological factors and human induced factors
253
to ensure the same degree of freedom for both classes of variables.
The plant assemblages were defined from the cluster analysis
of the matrix of the 437 terra firme plots and of the 246 species
that were at least present in four of these plots (UPGMA, BrayCurtis index, Legendre and Legendre, 2003). The indicator species of
each level or the hierarchical classification retained from the cluster analysis were defined with the indicator method of Dufrene and
Legendre (1997). This method calculates an indicator value (IV) for
each predefined group of plots: it is an integrated measure for the
relative mean abundance and the relative frequency of the species
in each group. Only species that have both a high mean abundance
and are present in the majority of the plots in a group will score a
high IV for that particular group. To test whether the observed IV
of a species in a group was higher than expected based on a random distribution of individuals over the locations, the observed IV
was compared with 999 randomly generated IVs (see Dufrene and
Legendre, 1997). A synoptic table was produced indicating the IV
value of the species, their frequency (10 frequency classes I–X, each
10% wide) and their mean cover in the plots of the plant assemblage.
The linear correlation between plot size and plot species richness
was investigated with Spearman correlations. This was done for all
plots as well as within each of the plant assemblages with more
than five plots. ANOVA tested for significant differences of plot size
between the four main plant assemblages.
Life form, phytogeographical and ecological spectra were
calculated for each plant assemblage. These were realized in
presence–absence and with abundance data (weighted by the sum
of the mean cover of the species in the plant assemblage). Pearson’s chi-square (2 ) tests were used to assess the significance of
differences in the spectra between the different plant assemblages.
Life forms follow the definitions of Raunkiær (1934): therophytes (Th), chamaephytes (Ch), geophytes (G), hemicryptophytes
(H) and phanerophytes (Ph). Ecological groups follow Schmitz
(1988): ruderal species (R), savanna species (S), psammophile
species (P), sclerophyllous forest species (SF), wetland species
(W), hygrophilous forest species (HF) and cultivated species (Cu).
The ecology and the geographical distribution of each species
were defined with the help of floras and online databases:
“Flore du Rwanda” (Troupin, 1988) “Flore graminéenne du
Burundi” (Ndabaneze, 1989), the African Plants Database (2009),
Tropicos.org. (2009), and the Royal Botanical Gardens Database
(2009). Additional information was found in the literature (Galinato
et al., 1999; Wester, 1992; Wet, 1977). We characterized the distribution of the species following the phytogeographical classification
of Lebrun (1956) and White (1983). We distinguished the origin of
species from its geographical distribution, the latter being dynamic
and, for many species, influenced by human activities. The following phytogeographical elements were considered:
- widespread species (WS): cosmopolitan (Cos), paleotropical (Pal),
pantropical (Pan) and Afro-Asian (Af-As),
- African species: Afro-Madagascarian (Af-Ma), African pluriregional (AP), Tropical African (T Af), East African (EA), East
and South African (EA-SA), Guineo-Congolian and Lake Victoria
Regional Mosaic (GC-V) and Afro-montane (Mo) species,
- Lake Victoria Regional Mosaic species (V),
- species endemic to the Western Graben District (E): this phytogeographic district was defined by Lebrun (1956) and designates
the Imbo plain (which includes the Ruzisi Plain and Bujumbura).
Introduced species (alien, exotic, non-native, non-indigenous)
are defined according to Weber (1997) and Pyšek et al. (2004)
as species that are not indigenous in a given geographical unit
(here Burundi). Their presence in the country is due to intentional
or unintentional human involvement, or they have arrived there
without the help of people from an area in which they were
J. Bigirimana et al. / Landscape and Urban Planning 100 (2011) 251–267
introduced. They include invasive plants: plants that produce
reproductive offsprings, often in very large numbers, at considerable distances from the parent plants, and thus have the potential
to spread over a large area. Introduced species are opposed to
native species: taxa that have originated in a given area without
human involvement or that have arrived there without intentional
or unintentional intervention of humans from an area in which
they are native. In this study, we consider as native the species
from the Lake Victoria Regional Mosaic, the species endemic to
the Western Graben District and the African species. The status
of widespread species is more complicated to establish. When
the species is distributed on several continents, its distribution
could be natural (long distance dispersal) or human induced. We
decided here to follow Thorne (1972) by considering Afro-Asian
distributions as potentially natural. For the other inter-continental
distributions, if the origin of the species is known, it can be
classified as native or not. If its origin is unknown, we classify it
according to Bean (2007); these species can also be considered as
native under the following conditions:
- if they are aquatic, semi-aquatic or littoral plants (long distance
dispersal by water),
- if they are terrestrial species with adhesive fruits (long distance
dispersal by birds),
- when they are only found in undisturbed habitats.
In conclusion, in this study, the number of native species
N = N1 + N2 (N1 : species with a continuous distribution including
Burundi and N2 : widespread species that might be considered as
indigenous according to Bean, 2007). The number of introduced
species I = I1 + I2 (I1 : introduced species with known origin and I2 :
widespread species that do not conform to the criteria for the native
according to Bean, 2007).
3. Results
3.1. Plant assemblages and their relationship to human induced
and natural ecological factors
A total of 404 species has been recorded in the 437 plots. These
species belong to 236 genera and 71 families. The five main families
are the Poaceae (18%), Fabaceae (14%), Cyperaceae (7%), Asteraceae
(6%) and Euphorbiaceae (5%). The most frequent species are annual
plants.
The main floristic gradient (DCA axis 1) was best correlated to
the urbanization degree, while the degree of trampling by humans
and cattle and the presence of a permanent source of humidity are
correlated to the two first DCA axes (Fig. 2). Soil types are weakly
correlated with these floristic gradients. The highly urbanized areas
are mainly covered by ruderal vegetation (TF1), while the fallow
vegetation and relict savannas (TF2) are mainly located in the less
urbanized areas (see Fig. 1).
Only 4.7% of the total floristic variance was correlated to the
two natural environmental factors (humidity and shade) and the
two human induced factors (degree of trampling and degree of
urbanization) selected for the variance partitioning analysis. These
4.7% were equally distributed between the two categories of factor
(50% each), there was no common effect (0%). Most of the floristic
variance is thus unexplained (95%).
Four main plant assemblages were defined from a dissimilarity
level of 0.93 in the dendrogram resulting from the cluster analysis.
Sub-assemblages were further defined within two of these plant
assemblages (Table 1). The mean plot size, mean species richness,
total number of species and the number of plots are given for each
plant assemblage. Note that the correlation of plot size and species
Trampling
Axis 2
254
Urbanisation
Shade
Humidity
Axis 1
Fig. 2. Detrended Correspondence Analysis (DCA) of 437 vegetation plots realized
in the terra firme vegetation of Bujumbura. Four main plant assemblages can be
distinguished (see Table 1 for more details): TF1 (crosses), TF2 (circles), TF3 (boxes),
TF4 (triangles) and black stars (soil types). Environmental variables were passive
in the analysis. Axes 1 and 2 represent respectively 2.8% and 2.2% of total floristic
variability.
richness is positive and significant (P < 0.001) for all plots and for
the plots of plant assemblage TF1 and TF2, but weak (R2 < 0.12). This
was not tested on TF3 (there are only four plots in this group) and
the correlation was not significant for TF4. As plot size varies significantly between the plant assemblages (ANOVA, P < 0.001), the mean
species richness of the plots from the different plant assemblages
given in Table 1 have only indicative values. The plant assemblages
are briefly described below (see Table 1 for more details).
3.1.1. Ruderal grasslands (TF1)
This plant assemblage is developing on different soil types
in habitats highly influenced by man such as roadsides, playing
grounds and abandoned ditches. It is composed of ruderal species,
including several nitrophytes like Ageratum conyzoides and Sida
acuta. Two sub-assemblages can be distinguished according to the
high (TF11) or medium (TF12) degree of trampling of the vegetation by man and/or cattle. TF11 is distinguished from TF12 by the
abundance of Sporobolus pyramidalis, a pantropical weed resistant
to trampling and to annual fires, disliked by livestock.
3.1.2. Fallow vegetation and relict savanna (TF2)
This plant assemblage is mainly present at the outskirts of the
city, in unconstructed land and agricultural fallows and in small
patches in the city centre. Most characteristic species are grasses
like Panicum maximum and Setaria pumila. Four sub-assemblages
can be distinguished:
TF21 are grasslands in young agricultural fallows and abandoned land on strong slopes. It is characterized by the abundance
of Tithonia diversifolia. This Asteraceae of Mexican origin is now
invasive in Burundi.
TF22 are grasslands in agricultural fallows on very poor soils.
These soils have been exhausted by over-cultivation and/or are
eroded because of strong slopes. This plant assemblage is characterized by Imperata cylindrica. In Bujumbura, it is mainly present
on the slopes above the Ntahangwa and Nyabagere rivers.
TF23 is the plant assemblage of old agricultural fallows and of
relict savannas. It is characterized by three grasses amonst which
Hyparrhenia madaropoda, a species endemic to the Lake Victoria
Table 1
Plant assemblages of the vegetation of Bujumbura city (excluding wetlands). IV: Indicator value of character species (only significant values are indicated). F: Frequency class (I–X each 10% wide) and C: mean cover of the species
within the plots of the plant assemblage. Invasive species are mentioned by ‘*’. Only the most representative species within each plant assemblage are listed.
TF11
TF12
TF21
TF22
TF23
TF24
TF3
TF4
Number of plots
Average surface of plots and standard deviation
Total mean cover and standard deviation
Number of species
Mean number of species per plot
Characteristic species of
IV
46
72 ± 31
81 ± 19
176
16
F
C
262
34 ± 28
61 ± 26
337
18
F
C
5
52 ± 32
67 ± 3
36
11
F
C
7
34 ± 24
63 ± 32
90
18
F
C
22
53 ± 36
54 ± 21
131
17
F
C
70
55 ± 34
48 ± 16
169
18
F
C
4
41 ± 20
78 ± 39
43
14
F
21
83 ± 39
34 ± 22
113
14
F
TF1: ruderal grasslands
Ageratum conyzoides L. *
Digitaria longiflora (Retz.) Pers. *
Sida acuta Burm. f. *
Synedrella nodiflora Gaertn. *
Acanthospermum hispidum DC. *
Cynodon nlemfuensis Vanderyst var. nlemfuensis
Eleusine indica (L.) Gaertn. subsp. indica *
39
35
33
31
30
30
25
III
III
V
III
II
VII
III
0.2
0.2
0.4
0.1
0.1
1.4
0.3
VI
V
V
IV
IV
IV
III
2.0
3.5
3.3
3.2
1.7
7.7
0.2
TF11: grasslands trampled by people or/and cattle
Sporobolus pyramidalis P. Beauv.
Paspalum notatum Flüggé *
Chloris pycnothrix Trin.
Desmodium triflorum
Kyllinga bulbosa P.Beauv.
Gomphrena celosioides Mart. *
35
32
25
32
39
21
VII
IV
IV
VII
V
III
3.5
16.7
8.6
2.0
0.3
0.2
II
0.2
V
II
II
V
II
0.3
0.1
0.1
0.3
0.1
III
II
II
0.2
0.1
0.2
II
0.2
IV
II
II
II
II
8.8
11.3
8.3
7.3
3.2
TF12: grasslands not or weakly trampled
Same asTF1
TF2: fallow vegetation and relict savannah
Panicum maximum Jacq.
Setaria pumila (Poir.) Roem. & Schult. *
Aristida adscensionis L.
Hyperthelia dissoluta (Steud.) Clayton
Pennisetum polystachion (L.) Schult. subsp. polystachion
31
11
16
14
16
C
C
J. Bigirimana et al. / Landscape and Urban Planning 100 (2011) 251–267
Communities
255
256
Table 1 (Continued)
Communities
TF11
TF12
TF21
TF21: grasslands of young agricultural fallows and abandoned land on high slopes
Tithonia diversifolia (Hemsl.) A.Gray *
98
83
TF23: grasslands of old fallow and relict savannah
Hyparrhenia filipendula (Hochst.) Stapf
H. madaropoda Clayton
Heteropogon contortus (L.) R & Sch.
65
46
46
X
TF23
TF24
99
TF4: psammophile steppe
Ipomoea pes-caprae (L.) R.Br. subsp. brasiliensis (L.) Ooststr.
Crotalaria pallida var. obovata (G. Don) Polhill *
Eragrostis tremula Steud. *
Triumfetta rhomboidea Jacq. *
75
57
47
49
Ubiquitous species
Euphorbia hirta L. *
Tridax procumbens L. *
Bidens pilosa L. *
Desmodium tortuosum (Sw.) DC. *
Hyptis suaveolens Poir.*
Phyllanthus amarus Schumach. & Thonn.*
Asystasia schimperi T. Anderson
Cassia obtusifolia L. *
Cassia occidentalis L. *
Euphorbia heterophylla L. *
Dactyloctenium aegyptium (L.) Willd.*
Cyperus esculentus L. *
Corchorus olitorius L. *
Manihot esculenta Crantz *
Leonotis nepetifolia (L.) R.Br.
IX
67.4
VIII
V
V
39.1
16.1
30.9
VII
VI
V
V
12.6
13.1
12.2
0.5
X
IV
II
II
II
II
II
I
I
I
I
I
III
I
I
0.2
0.1
0.1
0.1
0.1
0.1
0.1
0.2
0.1
0.0
0.0
0.2
0.0
0.0
IV
IV
V
III
III
IV
IV
III
III
III
III
II
III
II
II
0.5
1.0
2.1
0.6
2.2
0.3
0.3
3.9
0.2
1.5
0.3
0.3
0.3
0.3
1.6
TF4
90.8
TF24: grasslands of agricultural fallows on slightly degraded soils
Melinis repens (Willd.) Zizka subsp. repens
39
B. decumbens var. ruziziensis (R. Germ. & Evrard) Ndab.
29
Aspilia kotschyi (Sch.Bip.) Oliv.
31
Crotalaria ochroleuca G.Don
30
TF3: ruderal grasslands on moist clay soils
Paspalum conjugatum P.J.Bergius *
TF3
II
0.2
IV
0.3
V
V
II
II
0.3
0.3
0.1
0.1
II
II
III
II
II
III
V
0.1
0.1
0.2
0.1
0.1
0.2
0.3
IV
IV
III
V
III
II
II
I
I
I
I
I
I
0.3
0.3
0.2
0.4
0.2
0.1
0.1
0.1
0.0
0.1
0.1
0.1
0.0
I
0.0
V
IV
III
V
V
III
II
II
II
I
II
II
III
II
I
0.4
0.4
0.2
0.4
0.4
0.2
0.2
0.2
0.1
0.1
0.2
0.2
0.2
1.0
0.1
V
III
III
91.4
0.3
0.2
0.2
VIII
VIII
V
I
24.6
22.2
9.8
8.2
II
V
0.3
3.4
I
III
I
I
II
IV
I
II
I
I
II
I
0.1
0.4
0.1
0.1
0.6
0.5
0.1
0.2
0.1
0.1
0.2
0.1
J. Bigirimana et al. / Landscape and Urban Planning 100 (2011) 251–267
TF22: grasslands of agricultural fallows on very poor soils
Imperata cylindrica (L.) Raeuschel *
TF22
J. Bigirimana et al. / Landscape and Urban Planning 100 (2011) 251–267
257
Table 2
Life form and phytogeographical spectra (% of species mean cover) of the species composing plant assemblages of Bujumbura. Life forms: therophytes (Th), chamaephytes
(Ch), geophytes (G), hemicrytophytes (H), phanerophytes (Ph). Distribution: widespread species (WS), African species (Af), Endemic to the Lake Victoria Regional Mosaic (V)
and Endemic to the Western Graben District (E). Origin status: Native species (N), Introduced species (I). Life form and origin status spectra differ between plant assemblages
(X 2 = 62.18 > 2df28, ˛5% = 41.34 and X 2 = 16.19 > 2df7, ˛5% = 14.07), but distribution spectra are not different (X 2 = 16.70 < 2df21, ˛5% = 32.67). For details about the plant
assemblages, see Table 1.
Plant assemblages
TF11
TF12
TF21
TF22
TF23
TF24
TF3
TF4
All plots
% of species mean cover
Life form
Th
Ch
G
H
Ph
21
63
4
12
0
49
41
3
5
2
2
95
2
0
1
16
7
72
2
3
8
3
1
87
1
33
17
2
47
1
3
95
1
0
1
22
65
12
0
1
45
44
3
7
1
Distribution
WS
Af
V
E
84
15
1
0
90
7
1
2
98
2
0
0
90
9
1
0
78
2
20
0
71
15
1
13
99
1
0
0
96
2
2
0
89
8
2
1
Origin status
I
N
57
43
65
35
97
3
82
18
5
95
19
81
97
3
55
45
65
35
176
337
36
90
131
169
43
113
404
Number of species
Regional Mosaic. This plant assemblage is very rare in Bujumbura,
subsisting mainly at the outskirts of the city.
TF24 are the young fallow grasslands characterized by Melinis repens and by Brachiaria decumbens var. ruziziensis, a species
endemic from the Western Graben District.
3.1.3. Ruderal grasslands on moist clay soils (TF3).
These grasslands are dominated by Paspalum conjugatum, a
Poaceae originating from tropical America. This plant assemblage
is located on the moist clay soils of the shore of Lake Tanganyika.
3.1.4. Psammophile steppe (TF4)
This plant assemblage is located on the sandy soils of the shore
of Lake Tanganyika. The most characteristic species is Ipomoea pescaprae subsp. Brasiliensis, a Convolvulaceae typical of dunes and
beaches in the tropics worldwide.
3.2. Ecology, life form, origin and distribution of the species
The list of the 404 species identified in the 437 vegetation plots is
provided in the supplementary material (Appendix A), with information about their ecology, life form and phytogeography. Ruderal
species are abundant in all plant assemblages (>90% of the total
vegetation cover, see Appendix B) except in TF23 and TF24 that are
dominated by savannah species.
Most species are therophytes (41%), chamaephytes (25%) and
geophytes (17%, see Appendix C). Phanerophytes are rare. Life form
spectra differ significantly between the eight plant assemblages
(Chi-square tests, Table 2). Chamaephytes dominate the ruderal
grasslands (TF11 and TF3), hemicryptophytes are most abundant
in old agricultural fallows and in relict savannas (TF23). The dominance of geophytes in young fallows on very poor soils (TF22) is
due to I. cylindrica.
The phytogeographical spectra of the eight plant assemblages
are given in Table 2 and in Appendix C. Appendix D gives the origin of the species as well as their actual geographical distribution
and origin status (native or introduced). Native species and introduced species constitute respectively 57% and 43% of the flora. Sixty
percent of the introduced species have their origin in tropical America, 24% in Asia and 6% in Africa (Table 4). The less anthropized
habitats (TF23 and TF24) show the largest dominance of native
species (95% and 81% respectively). The other plant assemblages
have more than 55% to 97% of their total vegetation cover composed
of introduced species (Table 2). The 231 native species belong to
42 families and the 173 introduced species to 48 families. In both
cases, the most important families are the Fabaceae and Poaceae
(Table 3). Thirty nine percent of the introduced species were introduced deliberately and 61% accidentally. Seventy-four percent of
these introduced species are invasive, mainly weeds. Four species
occupy large areas in the town: T. diversifolia, Mimosa invisa, Lantana camara, and I. cylindrica. Very dense stands of these species can
occupy areas about 1 ha or more. Plant assemblages dominated by
these species indicate the presence of degraded soils. L. camara is
the most invasive species in Bujumbura and likely also in the whole
Rusizi plain.
Most species are widely distributed in the tropics (67%, Table 2)
and widespread species dominate all plant assemblages (71–98%
of total vegetation cover). Nine percent of the species are endemic
to the Lake Victoria Regional Mosaic and two species are endemic
to the Western Graben District: B. decumbens var ruziziensis and
Portulaca centrali-africana.
4. Discussion
4.1. Influence of natural ecological factors and human induced
factors on the urban vegetation
Like in most urban ecosystems, plant diversity in Bujumbura
is linked both to natural ecological factors and to human induced
factors. In the most urbanized areas of the city, the human factor is predominant and the vegetation is ruderal, whatever the soil
types (Figs. 1 and 2). Variance partitioning between human induced
factors (degree of urbanization and trampling by humans and cattle) and natural ecological factors (humidity and shade) influencing
the floristic variability yielded similar percentages (50%) of variance explained and no common effect. Note however that these
two groups of factors are not easily separated in the city of Bujumbura, as permanent soil humidity and shade sometimes result from
sewage water and planted trees, and could then be regarded as
human induced factors. Only 4.7% of the total floristic variance was
correlated to the four factors introduced in the variance partitioning analysis. Most of the floristic variance is thus unexplained (95%).
This is due to the high stochastic variation associated to the very
large number of plots and species (typical for studies in tropical
J. Bigirimana et al. / Landscape and Urban Planning 100 (2011) 251–267
258
Table 3
Most important families and % of introduced and native species, comparaison between the flora of Bujumbura and that of the city of Chonju in South Korea (Zerbe et al.,
2004), the flora of Mexico (Villaseñor and Espinosa-Garcia, 2004) and the world’s flora (Pyšek, 1998).
Family
Fabaceae
Poaceae
Asteraceae
Amaranthaceae
Euphorbiacaea
Cyperaceae
Solancaeae
Malvaceae
Convolvulaceae
Nyctaginaceae
Bujumbura
Bujumbura
Chonju
Mexico
World
Native
20
22
6
3
3
8
1
6
3
0
Introduced
18
13
8
5
5
5
5
3
3
2
Introduced
11
5
22
3
2
–
–
–
6
–
Introduced
9
28
9
1
2
1
2
3
–
–
Introduced
9
15
14
2
2
1
3
2
1
0.3
regions!) and to the fact that there certainly are more factors that
influence the vegetation than those measured in this study.
4.2. Ecology, life form, origin and distribution of the species
Therophytes, chamaephytes and geophytes dominate all plant
assemblages and phanerophytes are less abundant than in the
natural vegetation of the Rusizi plain (savannah, miombo and sclerophyllous forest). It is well known that phanerophytes respond
negatively to perturbations (Grime, 2001) and that annual species
and short life pluri-annuals are more abundant in urbanized
habitats (Fanelli et al., 2006). Ruderal therophytes have a weak
competition capacity, but they produce a large quantity of seeds
that allows them to maintain populations in a frequently disturbed
environment (Simonová and Lososová, 2008). Chamaephytes are
stress-tolerant (Grime, 2001). Their proportion is particularly
important in the psammophile steppe plant assemblage TF4
(drought due to sandy soils), the grassland plant assemblage of
young agricultural fallows and abandoned land (TF21) and in
the ruderal grasslands plant assemblage trampled by human and
cattle (TF11). Our results are different from those obtained by
Mutabana Nyakabwa in Kisanagani (R. D. Congo), where the flora
is dominated by 50% phanérophytes, 17% therophytes and 15%
chamaephytes. Differences in the natural vegetation type (rain forest in Kinsangani versus miombo and savanna in Bujumbura) may
partly explain the greater number of phanerophytes in Kinsangani.
Our results indicate a striking regression of the species of the
Lake Victoria Regional Mosaic (9%) and a large dominance of
species present in the tropics worldwide (67%). Indeed, Germain
(1952) studied the flora of the Congolese section of the Rusizi Plain
and concluded that 43% of the species belonged to what was later
named the Lake Victoria Regional Mosaic element. Later, in his
study of the flora of Burundi between 800 and 1000 m altitude
(including Bujumbura), Lewalle (1972) quoted 36% of species
belonging to this element. The urbanization process in Bujumbura
resulted in the progressive elimination of natural vegetation
(mosaic of savannah, miombo and sclerophyllous forests) and its
replacement by grasslands dominated by ruderal species. This
is the well-known process of biological homogenisation: unique
native species become extinct and are replaced by species that
are widespread (Kuhn and Klotz, 2006; Lockwood and McKinney,
2001). This process could be explained by the fact that in the
urban environment, sites available to the colonization of plants
are fragmented and their vegetation is quite diverse. Introduced
species are better adapted to colonize such diverse and fragmented
environments than native species, notably because many of these
species are more efficient at using limited resource during short
times (Celesti-Grapow et al., 2006; Funk and Vitousek, 2007).
Two main factors are considered for the establishment of introduced species in a country: climatic similarities with the country of
origin and historical factors (Arévalo et al., 2005). Almost all plants
currently cultivated in Burundi have been introduced in the 17th
and 18th century and later (Manirakiza, 2008). These voluntary
introductions have been accompanied by the uncontrolled arrival
of weeds from several countries. Today, introduced species in the
flora of Bujumbura are mainly agricultural weeds. The origin of
introduced species in the flora of Bujumbura is compared to that
of the flora from other cities and countries in the world in Table 4.
Burundi was colonized by European countries (in 1890), but very
few introduced species come from that continent: most originate
Table 4
Geographical origin (in %) of the introduced species in the flora of Bujumbura compared to that of introduced species in other countries. Data from Chonju city in South Korea
(Zerbe et al., 2004), Brussels city in Belgium (Ricotta et al., 2010), 20 ecogeographical region in Kenya (Stadler et al., 2000), South Africa (Milton, 2004), 32 States of Mexico
(Villaseñor and Espinosa-Garcia, 2004) and the Kashmir Himalayan region (Khuroo et al., 2007). n = number of introduced species considered.
New world
Tropical America
North America
South America
Caribbean region
North and south America
Old world
Asia
Africa
Australia
Europe
Eurasia
Mediterranean region
Eurasia and Africa
Old world and new world
Bujumbura city
(n = 173)
Chonju city
(n = 88)
Brussels city
(n = 186)
Kenya (n = 181)
South Africa
(n = 113)
Mexico country
(n = 604)
Kashmir
Himalaya
region (n = 571)
62
60
2
–
–
–
32
24
6
1
0
0
1
0
6
41
6
32
3
0
0
59
30
–
–
19
–
–
10
0
16
0
16
0
0
0
84
34
16
0
34
–
–
0
0
44
–
–
–
–
–
51
5
8
2
23
13
–
–
5
20
20
–
–
–
–
60
0
0
0
0
0
60
–
20
14
–
2
10
1
1
85
–
–
–
–
–
–
–
1
18
0
10
8
0
0
82
27
15
2
38
0
0
0
0
J. Bigirimana et al. / Landscape and Urban Planning 100 (2011) 251–267
from tropical America. Dominant families in the introduced flora
are similar in Bujumbura as in other cities and countries in the
world (Table 3): Fabaceae, Poaceae and Asteraceae. These three
families also dominate the native flora.
4.3. Conservation value of the vegetation of Bujumbura
A total of 404 species were identified, which is roughly one
third of the number of species listed for the whole Ruzisi Plain by
Reekmans (1980). The total flora of the city is very likely to be more
important as wetland vegetation and gardens were not included
here. Within the 404 species listed in this study, 57% are indigenous
and 9% have their distribution limited to the Lake Victoria Regional
Mosaic. Consequently, there is still a potential for biodiversity conservation within the territory of Bujumbura. The vegetation of the
city also presents several socio-economical interests. Grasses like
B. decumbens var. ruziziensis, P. maximum and Hyparrhenia spp. are
grazed by livestock and are essential for the agro-pastoral activities.
In his inventory of medicinal plants, Niyongabo (1985) compiled a
list of 101 species present in Bujumbura. Even very invasive species
can prove to be useful. Like in many other parts of Africa, I. cylindrica causes many problems for the local agriculture (Chikoye and
Ekeleme, 2003). However, this species is used to cover the roof of
houses in peri-urban areas. T. diversifolia is used in other countries
to restore soil fertility (Jama et al., 2000), as forage plant (Roothaert
and Paterson, 1997), to produce fire wood or as fence to control erosion (Ng’inja et al., 1998). But these potential uses of T. diversifolia
are currently unknown from the population of Bujumbura.
5. Conclusion, perspectives and recommendations
Like in other cities in the world, the urbanization process in
Bujumbura reduces the diversity and abundance of indigenous
species. In the most urbanized areas, ruderal plant assemblages
with a high abundance of introduced species dominate the vegetation. In the city outskirts, plant assemblages vary according to soil
type, humidity and shade, and native species are more abundant.
This study will be completed with analyses of the city’s spontaneous wetland vegetation and of the flora in private gardens. We
will then get a better knowledge of the vegetation inside the city
and of its spatial organization. This could be a first step in monitoring the evolution of the vegetation with the expansion of the city.
259
Similarly to what is done in temperate countries, urban planners in
African cities should take measure to preserve the last patches of
semi-natural vegetation, not only for their conservation value, but
also for the diversity of services they offer to the population. Measures should be taken to avoid the propagation of alien invasive
plant as it is well established that it costs much less to act preventively than trying to control these plants when they are already well
established.
Acknowledgements
We thank the editor, Paul Gobster, and two anonymous reviewers who took the time to give useful comments and suggestions on
an earlier draft of this manuscript. Joseph Bigirimana has a research
grant from the Government of Burundi, the Université Libre de
Bruxelles and “Fonds David et Alice Van Buuren”. Ingrid Parmentier is a post-doctoral researcher of the FRS-FNRS. We thank the
botanists of the National Botanical Garden of Belgium who contributed to the determination of the herbarium plant specimens.
Appendix A.
Informations about the life form, ecology and phytogeography
of 404 species in the spontaneous flora of Bujumbura. Life forms
(LF): therophytes (Th), chamaephytes (Ch), geophytes (G), hemicrytophytes (H), phanerophytes (Ph). Geographical distribution (GD)
and origin (GO) of species: Cosmopolitan (Cos), Paleotropical (Pal),
Pantropical (Pan), Afro-Asian (Af-As), Afro-Madagascarian (Af-Ma),
African pluriregional (AP), Tropical African (T Af), East and South
African (EA-SA), East African (EA), Guineo-Congolian and Lake Victoria Regional Mosaic (GC-V), Afro-montane (Mo), Lake Victoria
Regional Mosaic (V), Endemic to the Western Graben District (E), As
(Asia), Aus (Australia), Equatorial Africa (Eq Af), Madagascar (Mad),
Mediterranean region (Med), North Africa (N Af), North America
(N Am), Tropical America (T Am) and West Africa (W Af). Origin
status (OS): native species with a continuous distribution including Burundi (N1 ), widespread species that might be considered as
native according to Bean (2007) (N2 ), introduced species, introduced species with known origin (I1 ) and widespread species not
considered native (I2 ). Ecological groups (EG): ruderal species (R),
ruderal species in wetland (RW ), savanna species (S), psammophile
species (P), sclerophyllous forest species (SF) wetland species (W),
hygrophilous forest species (HF) and cultivated species (Cu).
LF
GD
GO
OS
EG
Family
Species
Th
Ch
Th
Th
Ph
Ph
Ch
Th
Th
Ch
Th
Ch
Ch
Th
Ch
G
G
Th
Ph
Th
Th
T Af
Pan
Af-Ma
AP
T Af
V
V
Pal
V
T Af
Pan
Pan
Af-Ma
T Af
Af-Ma
Pan
Pan
Pan
Pan
T Af
T Af
T Af
AP
Af-Ma
AP
T Af
V
V
AP
V
T Af
T Am
AP
Af-Ma
T Af
Af-Ma
T Am
T Am
T Am
As
T Af
T Af
N1
N1
N1
N1
N1
N1
N1
N1
N1
N1
I1
N1
N1
N1
N1
I1
I1
I1
I1
N1
N1
R
SF
R
R
S
S
R
R
R
R
R
R
HF
W
W
Cu
Cu
R
Cu
S
R
Cyperaceae
Fabaceae
Malvaceae
Malvaceae
Fabaceae
Fabaceae
Euphorbiaceae
Euphorbiaceae
Euphorbiaceae
Euphorbiaceae
Asteraceae
Amaranthaceae
Asteraceae
Poaceae
Fabaceae
Agavaceae
Agavaceae
Asteraceae
Fabaceae
Orobanchaceae
Orobanchaceae
Abildgaardia hispidula (Vahl) Lye subsp. hispidula
Abrus precatorius subsp. africanus Verdc.
Abutilon angulatum (Guill. & Perr.) Mast.
Abutilon mauritianum (Jacq.) Medic.
Acacia hockii De Wild.
Acacia polyacantha subsp. campylacantha (Hochst. ex A. Rich.) Brenan
Acalypha bipartita Müll.Arg.
Acalypha brachystachya Hornem.
Acalypha ciliata Forssk.
Acalypha ornata Hochst. ex A.Rich.
Acanthospermum hispidum DC.
Achyranthes aspera L. var. aspera L.
Acmella caulirhiza Del.
Acroceras amplectens Stapf.
Aeschynomene schimperi A.Rich.
Agave americana L.
Agave sisalana (Engelm.) Perrine
Ageratum conyzoides L.
Albizia chinensis (Osbeck) Merr.
Alectra sessiliflora var. senegalensis (Benth.) Hepper
Alectra vogelii Benth.
J. Bigirimana et al. / Landscape and Urban Planning 100 (2011) 251–267
260
LF
GD
GO
OS
EG
Family
Species
Ch
Th
Th
Th
Th
Th
Th
Th
Th
Th
H
Ch
Ph
Th
G
Ch
Th
Th
H
Th
Th
Th
Th
Ch
Ch
Ph
Th
G
Th
Ph
Ph
Th
Th
Th
Th
Th
Ph
Ch
Ch
Th
Th
Ph
Ph
Ch
Ch
G
Ch
Ph
Ph
Th
Ch
Th
Ph
Th
Ph
Ch
Ch
Ph
Th
Ch
Ch
Ch
Th
Th
Th
Th
Th
Th
Ch
Ch
Ch
Th
Ph
Th
Th
Ph
Pan
Pan
Af-As
Pan
Pan
Cos
Cos
Cos
Cos
AP
Af-Ma
V
Pan
T Af
Pan
Pan
Cos
Pan
Pan
V
V
T Af
V
Pan
V
Af-As
T Af
Pan
Af-Ma
Pan
Pan
Pan
Cos
Pan
Pan
Pan
Pan
E
Af-As
V
T Af
V
Pan
Pan
Pan
Cos
Pan
Pan
Pan
Pan
Pan
Pan
Pan
Pan
Pan
Pan
Cos
Pan
Af-Ma
Af-As
Pan
Pan
Af-Ma
Cos
EA
Cos
Pan
Pan
T Af
AP
V
Pan
Cos
Cos
Pan
GC-V
T Am
As
Af-As
T Am
T Am
T Am
T Am
T Am
T Am
AP
Af-Ma
V
T Am
Eq Af
T Am
T Am
T Am
T Am
AP
V
V
T Af
V
Af-As
V
Af-As
T Af
As
Af-Ma
Mad
As
T Am
T Af
T Am
T Am
Af-As
T Am
E
T Af
V
T Af
V
T Am
As
T Am
T Am
T Am
T Am
T Am
T Am
As
T Am
As
T Am
T Am
AP
Mad
T Am
Af-Ma
AP
As
Pal
Mad
T Am
EA
T Af
AP
T Am
T Af
AP
V
AP
As
T Am
T Af
GC-V
I1
I1
N1
I1
I1
I1
I1
I1
I1
N1
N1
N1
I1
I1
I1
I1
I1
I1
N1
N1
N1
N1
N1
N1
N1
N1
N1
I1
N1
I1
I1
I1
N1
I1
I1
N1
I1
N1
N1
N1
N1
N1
I1
I1
I1
I1
I1
I1
I1
I1
I1
I1
I1
I1
I1
N1
I1
I1
N1
N1
I1
N2
I1
I1
N1
N1
N1
I1
N1
N1
N1
N1
I1
I1
N1
N1
R
Rw
R
R
R
R
R
R
R
W
R
R
Cu
R
Cu
R
Cu
R
S
S
R
S
HF
R
R
S
Rw
Cu
Rw
Cu
Cu
R
R
R
R
R
Cu
S
R
R
R
S
Cu
Cu
R
Cu
R
Cu
Cu
R
R
R
Cu
R
Cu
S
R
Cu
R
P
R
R
R
R
R
R
R
R
R
SF
SF
R
Cu
R
R
SF
Amaranthaceae
Amaranthaceae
Fabaceae
Amaranthaceae
Amaranthaceae
Amaranthaceae
Amaranthaceae
Amaranthaceae
Amaranthaceae
Lythraceae
Poaceae
Commelinaceae
Annonaceae
Poaceae
Araceae
Polygonaceae
Fabaceae
Papaveraceae
Poaceae
Aristolochaceae
Asteraceae
Asteraceae
Asteraceae
Acanthaceae
Acanthaceae
Salvadoraceae
Fabaceae
Poaceae
Lamiaceae
Fabaceae
Fabaceae
Asteraceae
Oxalidaceae
Nyctaginaceae
Nyctaginaceae
Poaceae
Nyctaginaceae
Poaceae
Poaceae
Poaceae
Poaceae
Capparaceae
Fabaceae
Fabaceae
Fabaceae
Cannaceae
Solanaceae
Caricaceae
Apocynaceae
Fabaceae
Fabaceae
Fabaceae
Fabaceae
Fabaceae
Fabaceae
Lauraceae
Apocynaceae
Meliaceae
Amaranthaceae
Poaceae
Apiaceae
Fabaceae
Fabaceae
Chenopodiaceae
Chenopodiaceae
Poaceae
Poaceae
Asteraceae
Poaceae
Menispermaceae
Vitaceae
Cucurbitaceae
Rutaceae
Capparaceae
Capparaceae
Verbenaceae
Alternanthera pungens Kunth
Alternanthera sessilis (L.) DC.
Alysicarpus glumaceus (Vahl) DC.
Amaranthus caudatus L.
Amaranthus dubius Mart. ex Thell.
Amaranthus graecizans L.
Amaranthus hybridus L.
Amaranthus spinosus L.
Amaranthus viridis L.
Ammannia prieuriana Guill. & Perr.
Andropogon eucomus Nees
Aneilema spekei C.B.Clarke
Annona muricata L.
Anthephora cristata (Döll) Hack. ex De Wild. & T.Durand
Anthurium andraeanum André
Antigonon leptopus Hook. & Arn.
Arachis hypogaea L.
Argemone mexicana L.
Aristida adscensionis L.
Aristolochia petersiana Klotzsch
Aspilia helianthoides (Schumach. & Thonn.) Oliv. & Hiern
Aspilia kotschyi (Sch.Bip.) Oliv.
Aspilia pluriseta Schweinf.
Asystasia gangetica (L.) T. Anders.
Asystasia schimperi T. Anderson
Azima tetracantha Lam.
Bakerophyton lateritium (Harms) Hutch. ex Maheshw.
Bambusa vulgaris Schrader
Basilicum polystachyon (L.) Moench
Bauhinia monandra Kurz
Bauhinia purpurea L.
Bidens pilosa L.
Biophytum petersianum Klotzsch
Boerhavia diffusa L.
Boerhavia erecta L.
Bothriochloa insculpta (Hochst. ex A.Rich.) A.Camus
Bougainvillea spectabilis Willd.
Brachiaria decumbens var. ruziziensis (R. Germ. & Evrard) Ndab.
Brachiaria deflexa (Schumach.) C.E.Hubb. ex Robyns
Brachiaria leersioides (Hochst.) Stapf
Brachiaria scalaris Pilg.
Cadaba farinosa subsp. adenotricha (Gilg & Gilg-Ben.) R.A. Graham
Caesalpinia pulcherrima (L.) Sw.
Cajanus cajan (L.) Millsp.
Calopogonium mucunoides Desv.
Canna indica L.
Capsicum frutescens L.
Carica papaya L.
Cascabela thevetia (L.) Lippold
Cassia hirsuta L.
Cassia obtusifolia L.
Cassia occidentalis L.
Cassia siamea Lam.
Cassia sophera L.
Cassia spectabilis DC.
Cassytha filiformis L.
Catharanthus roseus (L.) G.Don
Cedrela odorata L.
Celosia trigyna L.
Cenchrus biflorus Roxb.
Centella asiatica (L.) Urb.
Chamaecrista absus (L.) H.S.Irwin & Barneby
Chamaecrista pratensis (R.Vig.) Du Puy
Chenopodium ambrosioides L.
Chenopodium ugandae (Aellen) Aellen
Chloris pilosa Schum.
Chloris pycnothrix Trin.
Chrysanthellum indicum subsp. afroamericanum B.L. Turner
Chrysochloa hindsii C.E. Hubbard
Cissampelos mucronata A.Rich.
Cissus quadrangularis L.
Citrullus lanatus (Thunb.) Matsumara & Staples
Citrus limon (L.) Burm.f.
Cleome gynandra L.
Cleome rutidosperma DC
Clerodendrum schweinfurthii Gürke
J. Bigirimana et al. / Landscape and Urban Planning 100 (2011) 251–267
261
LF
GD
GO
OS
EG
Family
Species
Ch
Th
G
Ch
Ch
Ch
Ch
Ch
Ph
Th
Th
Th
Th
Ch
Th
Ch
Th
Th
Th
Ch
Th
Th
Ch
Th
Th
Ph
Ch
Ch
Ch
Th
G
G
Th
G
G
Th
G
G
G
G
G
Th
Th
Ch
Th
Th
Th
Ch
Ph
G
Th
Th
Th
Th
Th
Th
Ch
Ch
Th
Th
Th
Ph
Th
Th
Th
Th
Th
Th
Th
Ch
Th
H
Th
G
Ph
Ph
Th
Th
Cos
V
Pan
Af-As
EA-SA
Cos
Af-Ma
V
V
Pan
Cos
Mo
Pal
T Af
Pan
Pal
T Af
Pan
Af-Ma
Pan
Pan
AP
T Af
T Af
Cos
V
V
EA-SA
Af-As
Pan
GC-V
Pan
Cos
Pan
Af-Ma
Pan
Pan
Af-Ma
Af-Ma
Af-Ma
Cos
Pan
Cos
V
Pan
Cos
Pan
Pan
Pan
Pan
Pan
Pan
Pan
V
Af-Ma
Af-As
Pan
V
Pan
Pan
Pan
Pan
Cos
V
Pan
Af-Ma
EA
Pan
V
EA-SA
AP
Pan
Pan
Af-As
Af-Ma
Pal
Pan
Pan
EA
V
As
T Af
EA-SA
As
Af-Ma
V
V
T Am
As
Mo
Pal
T Af
T Af
Pal
T Af
T Af
T Af
T Am
T Am
AP
T Af
T Af
T Am
V
V
EA-SA
T Af
Pan
GC-V
Pan
Med
Pan
Af-Ma
Eur
T Am
Af-Ma
Af-Ma
Af-Ma
As
T Am
Cos
V
As
As
T Am
Pan
Pal
T Am
T Af
As
T Af
V
Af-Ma
AP
Pan
V
EA
T Am
T Am
Eq Af
As
V
Af-As
Af-Ma
EA
Pan
V
EA-SA
AP
Af-As
Af-As
Af-As
Af-Ma
Aus
T Am
T Am
N1
N1
I1
N1
N1
I1
N1
N1
N1
I1
I1
N1
N2
N1
N1
I2
N1
N1
N1
I1
I1
N1
N1
N1
I1
N1
N1
N1
N1
I2
N1
N2
I1
N2
N1
I1
I1
N1
N1
N1
I1
I1
I2
N1
I1
I1
I1
N2
N2
I1
N1
I1
N1
N1
N1
N1
N2
N1
N1
I1
I1
I1
I1
N1
N1
N1
N1
I2
N1
N1
N1
N1
N1
N1
N1
I1
I1
I1
R
R
Cu
R
R
Rw
R
R
S
R
R
R
R
S
R
R
S
R
R
R
R
R
R
R
Cu
S
R
S
R
R
R
W
Rw
R
W
R
W
W
R
W
R
R
Rw
SF
R
R
R
R
S
Cu
R
R
R
R
R
R
Rw
R
Rw
W
Rw
Cu
R
R
R
R
R
R
R
R
R
R
R
W
S
Cu
R
R
Fabaceae
Fabaceae
Araceae
Commelinaceae
Commelinaceae
Commelinaceae
Commelinaceae
Commelinaceae
Burseraceae
Asteraceae
Malvaceae
Asteraceae
Fabaceae
Fabaceae
Fabaceae
Fabaceae
Fabaceae
Fabaceae
Fabaceae
Fabaceae
Fabaceae
Fabaceae
Fabaceae
Cucurbitaceae
Cucurbitaceae
Araliaceae
Commelinaceae
Asclepiadaceae
Poaceae
Cyperaceae
Cyperaceae
Cyperaceae
Cyperaceae
Cyperaceae
Cyperaceae
Cyperaceae
Cyperaceae
Cyperaceae
Cyperaceae
Cyperaceae
Cyperaceae
Cyperaceae
Cyperaceae
Vitaceae
Poaceae
Solanaceae
Fabaceae
Fabaceae
Fabaceae
Agavaceae
Poaceae
Poaceae
Poaceae
Poaceae
Poaceae
Poaceae
Caryophulaceae
Acanthaceae
Poaceae
Poaceae
Asteraceae
Arecaceae
Poaceae
Asteraceae
Poaceae
Poaceae
Poaceae
Poaceae
Poaceae
Poaceae
Poaceae
Poaceae
Poaceae
Poaceae
Fabaceae
Myrtaceae
Euphorbiaceae
Euphorbiaceae
Clitoria ternatea L.
Clitoria ternatea L. var. angustifolia Hochst. ex Baker f.
Colocasia esculenta (L.) Schott
Commelina africana L.
Commelina benghalensis L. var. benghalensis
Commelina diffusa Burm.f.
Commelina latifolia Hochst. ex A.Rich.
Commelina nigritana Benth.
Commiphora habessinica (O.Berg) Engl.
Conyza bonariensis (L.) Cronquist
Corchorus olitorius L.
Crassocephalum montuosum (S. Moore) Milne-Rendle
Crotalaria calycina Schrank
Crotalaria chrysochlora Baker f. ex Harms
Crotalaria goreensis Guill. & Perr.
Crotalaria laburnifolia L. subsp. laburnifolia
Crotalaria lachnophora A.Rich.
Crotalaria ochroleuca G.Don
Crotalaria ononoides Benth.
Crotalaria pallida var. obovata (G. Don) Polhill
Crotalaria retusa var. retusa
Crotalaria spartea Baker
Crotalaria spinosa Hochst. ex Benth.
Cucumis maderaspatanus L.
Cucurbita pepo L.
Cussonia arborea Hochst. ex A.Rich.
Cyanotis lanata Benth.
Cynanchum schistoglossum Schltr.
Cynodon nlemfuensis Vanderyst var. nlemfuensis
Cyperus amabilis Vahl
Cyperus angolensis Boeckeler
Cyperus articulatus L.
Cyperus difformis L.
Cyperus distans L.f.
Cyperus dives Del.
Cyperus esculentus L.
Cyperus haspan L.
Cyperus latifolius Poir.
Cyperus macrocarpus (Kunth) Boeckeler
Cyperus maculatus Boeckeler
Cyperus rotundus L.
Cyperus sphacelatus Rottb.
Cyperus squarrosus L.
Cyphostemma adenocaule (Steud. ex A.Rich.) Desc. ex Wild & R.B.Drumm.
Dactyloctenium aegyptium (L.) Willd.
Datura stramonium L.
Desmodium tortuosum (Sw.) DC.
Desmodium triflorum (L.) DC.
Desmodium velutinum (Willd.) DC.
Dieffenbachia seguine (Jacq.) Schott
Digitaria abyssinica (Hochst. ex A.Rich.) Stapf
Digitaria longiflora (Retz.) Pers.
Digitaria nuda Schumach.
Digitaria pearsonii Stapf
Digitaria perrottetii (Kunth) Stapf
Digitaria ternata (A.Rich.) Stapf
Drymaria cordata (L.) Willd. Ex Roem. & Schult.
Dyschoriste radicans Nees
Echinochloa colona (L.) Link
Echinochloa crus-pavonis (Kunth) Schult.
Eclipta prostrata (L.) L.
Elaeis guineensis Jacq.
Eleusine indica (L.) Gaertn. subsp. indica
Emilia caespitosa Oliv.
Eragrostis amabilis (L.) Wight & Arn.
Eragrostis aspera (Jacq.) Nees
Eragrostis caespitosa Chiov.
Eragrostis ciliaris (L.) R. Br.
Eragrostis exasperata Peter
Eragrostis heteromera Stapf
Eragrostis patens Oliv.
Eragrostis tenuifolia (A.Rich.) Steud.
Eragrostis tremula Steud.
Eriochloa fatmensis (Hochst. & Steud.) Clayton
Eriosema psoraloides (Lam.) G. Don
Eucalyptus globulus Labill.
Euphorbia heterophylla L.
Euphorbia hirta L.
J. Bigirimana et al. / Landscape and Urban Planning 100 (2011) 251–267
262
LF
GD
GO
OS
EG
Family
Species
Th
Th
Ch
Ph
Ch
Ph
Th
Ph
H
Th
G
Ch
Ch
Ch
Ph
Ph
Th
Th
Ch
H
Ch
Th
Ch
Th
Th
Ph
Th
G
H
H
H
H
Th
G
Th
Ch
Ch
Ch
Th
Th
Th
Th
Ch
G
G
G
Th
Ch
Ch
Ch
G
Ph
G
Th
Ch
Ch
G
G
G
Th
Th
Ch
Ch
Ch
Th
G
Th
H
Ph
Th
Ch
Ch
Ch
Th
Ch
Ph
G
G
Af-As
Pan
Pan
Pan
Pan
Pan
Pan
Pan
Pan
Cos
Pan
Pan
Pan
Pan
Pan
V
Pan
Af-As
T Af
Cos
Pan
Pan
Af-Ma
T Af
Pal
AP
V
T Af
Pal
V
Pan
Pan
Pan
Pan
V
Af-As
V
V
T Af
Pan
T Af
T Af
Pan
Pan
T Af
Pan
Pan
Pan
Pan
Pan
Pan
Pan
Pan
V
Pan
T Af
Af-As
Af-Ma
T Af
Pan
Af-Ma
GC-V
Af-Ma
Pan
Pan
Pan
Pan
Af-As
Pan
Af-Ma
Af-Ma
Af-Ma
T Af
Pan
Pan
Pan
Pan
Pan
Af-As
T Am
As
EA
T Am
Af-As
As
AP
Pan
T Am
Af-As
T Af
T Am
T Am
Aus
V
Pan
Af-Ma
T Af
Cos
Af-As
Pan
Af-Ma
T Af
Af-As
AP
V
T Af
Af-As
V
AP
T Af
T Am
T Am
V
Af-As
V
V
T Af
Pal
T Af
T Af
Af-As
T Am
T Af
As
Af-As
T Am
Pan
As
Pan
T Am
T Am
V
Mad
T Af
Af-As
Af-Ma
T Af
Pal
Af-Ma
GC-V
Af-Ma
T Am
T Af
Pan
T Af
Af-As
T Am
Af-Ma
Af-Am
Af-Ma
T Af
As
T Am
As
T Am
T Am
N1
I1
I1
N1
I1
N1
I1
N1
N2
I1
N1
N1
I1
I1
I1
N1
I2
N1
N1
N2
N1
N2
N1
N1
N1
N1
N1
N1
N1
N1
N1
N1
I1
I1
N1
N1
N1
N1
N1
N2
N1
N1
N1
I1
N1
I1
N1
I1
N2
I1
N2
I1
I1
N1
I1
N1
N1
N1
N1
N2
N1
N1
N1
I1
N1
N2
N1
N1
I1
N1
N1
N1
N1
I1
I1
I1
I1
I1
R
R
R
S
W
SF
W
S
W
R
SF
R
R
Cu
Cu
S
R
R
W
S
R
S
SF
R
R
SF
R
W
S
S
S
S
R
R
R
R
R
S
R
R
S
R
R
Cu
R
R
R
R
P
Cu
HF
Cu
Cu
R
R
R
R
Rw
W
R
R
SF
SF
R
R
W
R
S
Cu
R
W
W
W
R
R
Cu
Cu
Cu
Euphorbiaceae
Euphorbiaceae
Euphorbiaceae
Euphorbiaceae
Convolvulaceae
Moraceae
Cyperaceae
Euphorbiaceae
Cyperaceae
Asteraceae
Colchicaceae
Fabaceae
Amaranthaceae
Malvaceae
Proteaceae
Malvaceae
Poaceae
Boraginaceae
Poaceae
Poaceae
Convolvulaceae
Malvaceae
Malvaceae
Malvaceae
Malvaceae
Lamiaceae
Violaceae
Acanthaceae
Poaceae
Poaceae
Poaceae
Poaceae
Lamiaceae
Poaceae
Fabaceae
Fabaceae
Fabaceae
Fabaceae
Fabaceae
Fabaceae
Fabaceae
Fabaceae
Fabaceae
Convolvulaceae
Convolvulaceae
Convolvulaceae
Convolvulaceae
Convolvulaceae
Convolvulaceae
Convolvulaceae
Convolvulaceae
Bignoniaceae
Euphorbiaceae
Acanthaceae
Crassulaceae
Malvaceae
Cyperaceae
Cyperaceae
Cyperaceae
Cyperaceae
Asteraceae
Cucurbitaceae
Cucurbitaceae
Verbenaceae
Urticaceae
Poaceae
Lamiaceae
Poaceae
Fabaceae
Lamiaceae
Onagraceae
Onagraceae
Onagraceae
Cucurbitaceae
Fabaceae
Anacardiaceae
Euphorbiaceae
Euphorbiaceae
Euphorbia inaequilatera Sond.
Euphorbia prostrata Aiton
Euphorbia thymifolia L.
Euphorbia tirucalli L.
Evolvulus nummularius (L.) L.
Ficus exasperata Vahl
Fimbristylis dichotoma (L.) Vahl.
Flueggea virosa (Roxb. ex Willd.) Voigt
Fuirena umbellata Rottb.
Galinsoga parviflora Cav.
Gloriosa superba L.
Glycine javanica L.
Gomphrena celosioides Mart.
Gossypium hirsutum L.
Grevillea robusta A.Cunn. ex R.Br.
Grewia similis K.Schum.
Hackelochloa granularis (L.) Kuntze
Heliotropium ovalifolium Forssk.
Hemarthria natans Stapf
Heteropogon contortus (L.) R & Sch.
Hewittia malabarica (L.) Suresh
Hibiscus cannabinus L.
Hibiscus diversifolius Jacq. subsp. diversifolius
Hibiscus mechowii Garcke
Hibiscus surattensis L.
Hoslundia opposita Vahl
Hybanthus enneaspermus (L.) F.Muell. var. enneaspermus
Hygrophila auriculata (Schumash.) Heine
Hyparrhenia filipendula (Hochst.) Stapf
Hyparrhenia madaropoda Clayton
Hyparrhenia rufa (Nees) Stapf
Hyperthelia dissoluta (Steud.) Clayton
Hyptis suaveolens Poir.
Imperata cylindrica (L.) Raeuschel
Indigofera ambelacensis Schweinf.
Indigofera arrecta Hochts. Ex A. Rich.
Indigofera colutea (Burm.f.) Merr. var. colutea
Indigofera drepanocarpa Taub.
Indigofera fulvopilosa Brenan
Indigofera hirsuta L.
Indigofera secundiflora Poir.
Indigofera simplicifolia Lam.
Indigofera spicata Forssk.
Ipomoea batatas Poir
Ipomoea blepharophylla Hallier f.
Ipomoea cairica (L.) Sweet
Ipomoea eriocarpa R. Br.
Ipomoea hederifolia L.
Ipomoea pes-caprae (L.) R.Br. subsp. brasiliensis (L.) Ooststr.
Ipomoea quamoclit L.
Ipomoea rubens Choisy
Jacaranda mimosifolia D.Don
Jatropha curcas L.
Justicia matammensis Oliv.
Kalanchoe pinnata (Lam.) Pers.
Kosteletzkya grantii (Mast.) Garcke
Kyllinga bulbosa P.Beauv.
Kyllinga erecta Schumach
Kyllinga sphaerocephala Boeckeler
Kyllinga squamulata Thonn. ex Vahl
Lactuca inermis Forssk.
Lagenaria rufa (Gilg) C.Jeffrey
Lagenaria sphaerica (Sond.) Naudin
Lantana camara L.
Laportea aestuans (L.) Chew.
Leersia hexandra Sw.
Leonotis nepetifolia (L.) R.Br.
Leptochloa obtusiflora Hochst.
Leucaena leucocephala (Lam.) De Wit.
Leucas martinicensis (Jacq.) R.Br.
Ludwigia abyssinica A. Rich.
Ludwigia leptocarpa (Nutt.) Hara
Ludwigia stenorraphe (Branan) Hara
Luffa cylidrica (L.) Roem.
Macroptilium atropurpureum (DC.) Urb.
Mangifera indica L.
Manihot esculenta Crantz
Manihot glaziovii Müll.Arg.
J. Bigirimana et al. / Landscape and Urban Planning 100 (2011) 251–267
263
LF
GD
GO
OS
EG
Family
Species
G
G
H
G
Ch
H
Th
Ch
Ch
Ch
Ph
Ch
Ch
Th
Th
Ph
Ch
Th
G
G
Th
Th
Ch
Th
Ch
Th
Th
Ch
Th
Ch
G
Th
Th
H
G
H
G
Ch
Ch
G
Ch
Ch
H
H
H
Ch
Th
Th
Ph
Th
Th
G
Ch
Th
Th
Ch
Ch
Ph
Ph
Ph
Ch
Ph
Th
Th
G
G
Ch
Ch
Th
Th
Ch
Ph
Th
Ch
Ph
G
G
Th
T Af
Af-As
GC-V
Af-As
V
Pan
Pan
V
Pan
Pan
Pan
Pan
Cos
Pan
Pan
Pal
T Af
Pan
Pan
Pan
Pan
Pan
Pan
Cos
Pal
Pan
Af-As
Pan
Pan
Cos
Pan
AP
Af-As
Pan
Pan
T Af
Pan
Pan
Pan
Pan
Pan
Pan
Pan
Pan
Mo
EA-SA
Pan
Af-Ma
Pan
Pan
T Af
Af-Ma
Pan
Pan
Af-As
Cos
Pan
Pan
Af-As
Af-As
Af-As
Pan
V
T Af
Af-As
T Af
E
Cos
Cos
Cos
Af-Ma
Af-Ma
Pan
V
Pan
Pan
Cos
V
T Af
Af-As
GC-V
Af-As
V
Af
Pan
V
As
T Am
T Am
T Am
T Am
T Am
Pan
As
T Af
As
As
As
T Am
T Am
As
As
Af-As
Af-As
Af-As
Pan
As
As
T Am
AP
Af-As
Af-Ma
T Am
T Af
T Am
T Am
T Am
T Am
T Am
As
Af-Ma
T Af
Mo
EA-SA
Af-As
Af-Ma
T Am
T Am
T Af
Af-Ma
T Am
T Am
Af-Ma
T Am
T Am
T Am
AP
V
Af-As
T Am
V
T Af
Af-As
T Af
E
T Am
T Am
T Am
Af-Ma
Af-Ma
Pan
V
T Am
Pan
Cos
V
N1
N1
N1
N1
N1
N1
I2
N1
I1
I1
I1
I1
I1
I1
I2
I1
N1
I1
I1
I1
I1
I1
I1
I1
N1
N1
N1
I2
I1
I1
I1
N1
N1
N1
I1
N1
I1
I1
I1
I1
I1
I1
N1
N1
N1
N1
N1
N1
I1
I1
N1
N1
I1
I1
N1
I1
I1
I1
N1
N1
N1
I1
N1
N1
N1
N1
N1
I1
I1
I1
N1
N1
I2
N1
I1
N2
N2
N1
R
R
R
R
R
S
R
R
R
R
HF
R
R
R
R
Cu
SF
R
Cu
Cu
R
Cu
R
R
R
R
R
R
Cu
R
R
R
R
S
Rw
Rw
W
R
R
W
R
Cu
S
Rw
S
S
Rw
R
Cu
Cu
SF
W
P
R
R
R
Cu
Cu
W
W
W
Cu
R
R
R
W
R
R
R
R
R
W
R
S
Cu
SF
W
S
Cyperaceae
Cyperaceae
Cyperaceae
Cyperaceae
Malvaceae
Poaceae
Malvaceae
Convolvulaceae
Fabaceae
Fabaceae
Fabaceae
Fabaceae
Nyctaginaceae
Rubiaceae
Molluginaceae
Moringaceae
Fabaceae
Fabaceae
Musaceae
Musaceae
Solanaceae
Solanaceae
Lamiaceae
Lamiaceae
Rubiaceae
Rubiaceae
Rubiaceae
Poaceae
Poaceae
Oxalidaceae
Oxalidaceae
Polygonaceae
Poaceae
Poaceae
Poaceae
Poaceae
Poaceae
Poaceae
Poaceae
Poaceae
Passifloraceae
Euphorbiaceae
Poaceae
Poaceae
Poaceae
Asclepiadaceae
Rubiaceae
Poaceae
Lauraceae
Fabaceae
Acanthaceae
Poaceae
Verbenaceae
Phyllanthaceae
Phyllanthaceae
Solanaceae
Solanaceae
Fabaceae
Asteraceae
Asteraceae
Asteraceae
Apocynaceae
Polygalaceae
Polygalaceae
Polygalaceae
Polygonaceae
Portulacaceae
Portulacaceae
Portulacaceae
Portulacaceae
Urticaceae
Fabaceae
Asteraceae
Fabaceae
Myrtaceae
Pteridaceae
Poaceae
Fabaceae
Mariscus cylindrystachyus Steud.
Mariscus dubius (Rottb.) Kük. ex C.E.C.Fisch. subsp. coloratus (Vahl) Lye
Mariscus dubius (Rottb.) Kük. var. macrocephalus (C.B.Clarke) Chiov.
Mariscus maderaspatanus (Willd.) Napper
Melhania velutina Forssk.
Melinis repens (Willd.) Zizka subsp. repens
Melochia corchorifolia L.
Merremia tridentata (L.) Hallier f. var. angustifolia (Jacq.) Ooststr.
Mimosa diplotricha var. inermis (Adelb.) Verdc.
Mimosa invisa Mart. ex Colla
Mimosa pigra L.
Mimosa pudica L.
Mirabilis jalapa L.
Mitracarpus hirtus (L.) DC.
Mollugo nudicaulis Lam.
Moringa oleifera Lam.
Mucuna poggei Taub.
Mucuna pruriens (L.) DC. var.pruriens
Musa acuminata Colla
Musa paradisiaca L.
Nicandra physalodes (L.) Gaertn.
Nicotiana tabacum L.
Ocimum americanum L.
Ocimum basilicum L.
Oldenlandia affinis (Roem. & Schult.) DC.
Oldenlandia corymbosa var. corymbosa.
Oldenlandia herbacea (L.) Roxb.
Oplismenus burmannii (Retz.) P.Beauv.
Oryza sativa L.
Oxalis corniculata L.
Oxalis latifolia Kunth
Oxygonum sinuatum (Hochst. & Steud. ex Meisn.) Dammer
Panicum atrosanguineum Hochst. ex A.Rich.
Panicum maximum Jacq.
Panicum repens L.
Panicum trichocladum K.Schum.
Paspalidium geminatum (Forssk.) Stapf
Paspalum conjugatum P.J.Bergius
Paspalum notatum Flüggé
Paspalum scrobiculatum L.
Passiflora foetida L.
Pedilanthus tithymaloides (L.) A.Poit.
Pennisetum polystachion (L.) Schult. subsp. polystachion
Pennisetum purpureum Schumach.
Pennisetum trachyphyllum Pilg.
Pentarrhinum insipidum E.Mey.
Pentodon pentandrus (Schum. & Thonn.) Vatke
Perotis patens Gand.
Persea americana Mill
Phaseolus vulgaris L.
Phaulopsis imbricata (Forssk.) Sweet
Phragmites mauritianus Kunth
Phyla nodiflora (L.) Greene
Phyllanthus amarus Schumach. & Thonn.
Phyllanthus nummulariifolius Poir.
Physalis lagascae Roem. & Schult.
Physalis peruviana L.
Pithecellobium dulce (Roxb.) Benth.
Pluchea dioscoridis (L.) DC.
Pluchea ovalis (Pers.) DC.
Pluchea sordida Oliv. & Harms
Plumeria rubra L.
Polygala albida Schinz
Polygala arenaria Willd.
Polygala erioptera DC.
Polygonum pulchrum Blume
Portulaca centrali-africana R.E.Fr.
Portulaca grandiflora Hook.
Portulaca oleracea L.
Portulaca quadrifida L.
Pouzolzia guineensis Benth.
Pseudarthria hookeri Wight & Arn.
Pseudoconyza viscosa (Mill.) D’Arcy
Pseudoeriosema borianii subsp. borianii
Psidium guajava L.
Pteris vittata L.
Hyparrhenia filipendula (Hochst.) Stapf
Rhynchosia micrantha Harms
J. Bigirimana et al. / Landscape and Urban Planning 100 (2011) 251–267
264
LF
GD
GO
OS
EG
Family
Species
Th
Ch
Th
Ph
Th
G
Ph
Th
Th
Ph
Ch
Th
Th
Th
Ch
Ch
Ch
Ch
Ch
Ch
Th
Ch
Ch
Th
Th
Ch
H
H
H
Ph
Th
Th
Th
H
H
Ch
Th
Ch
Th
Ch
Ch
Th
Th
Th
Ch
Ph
Ph
Ph
Ch
Ch
Th
Th
Th
Th
Ch
Ch
G
Ch
Ph
Th
Th
Ch
Ch
Ch
Ch
Th
Ch
Th
Ch
Th
G
Th
Ch
Pan
AP
Pan
Cos
Pan
Pan
Pan
V
Af-As
Pan
AP
AP
Cos
Cos
Pan
Pan
Pan
Pan
Pan
Pan
Af-As
Af-Ma
Af-As
Cos
Cos
Mo
Pan
Pan
AP
GC-V
Af-As
EA-SA
Pan
AP
Pan
Pan
Pan
Af-As
Pan
Pan
Cos
Af-Ma
Pal
AP
Pan
Pan
Pan
Pan
Pan
V
Cos
Cos
Pal
Pan
Pan
V
Pan
Pan
AP
Pan
V
Pan
Af-Ma
Af-Ma
Pan
T Af
Pan
T Af
AP
Cos
Pan
Cos
Af-As
T Am
AP
T Am
N Af
As
As
T Am
V
T Af
Pal
AP
AP
As
Med
T Am
T Am
Pan
T Am
Af-As
Pan
AP
Af-Ma
AP
T Am
As
Mo
AP
AP
AP
GC-V
Af-As
EA-SA
As
AP
Af-As
T Am
Af-As
As
T Am
Af-As
T Am
Af-Ma
T Af
AP
As
As
Mad
W Af
T Am
V
N Am
AP
Pal
T Am
T Am
V
Pan
T Af
AP
As
V
Pan
T Af
Af-Ma
AP
Eq Af
Pan
T Af
AP
N Am
T Am
T Am
Af-As
I1
N1
I1
I1
I1
I1
I1
N1
N1
N2
N1
N1
I1
I1
I1
I1
N2
I1
N1
N2
N1
N1
N1
I1
I1
N1
N1
N1
N1
N1
N1
N1
I1
N1
N1
I1
N1
I1
I1
N1
I1
N1
N1
N1
I1
I1
I1
I1
I1
N1
I1
N1
I2
I1
I1
N1
N2
N1
N1
I1
N1
N2
N1
N1
N1
I1
N2
N1
N1
I1
I1
I1
N1
R
R
R
R
R
Cu
Cu
R
R
HF
R
R
S
R
Cu
R
R
R
R
R
R
R
R
Cu
R
R
S
Cu
R
Cu
R
R
Rw
R
R
R
R
R
R
R
R
R
R
R
R
Cu
Cu
Cu
R
SF
R
R
R
R
R
SF
W
R
SF
R
R
W
R
R
R
Cu
SF
R
R
R
Cu
Cu
R
Fabaceae
Fabaceae
Rubiaceae
Euphorbiaceae
Poaceae
Poaceae
Sapindaceae
Pedaliaceae
Fabaceae
Fabaceae
Poaceae
Poaceae
Poaceae
Poaceae
Commelinaceae
Malvaceae
Malvaceae
Malvaceae
Malvaceae
Malvaceae
Solanaceae
Solanaceae
Solanaceae
Solanaceae
Solanaceae
Asteraceae
Poaceae
Poaceae
Poaceae
Bignoniaceae
Rubiaceae
Rubiaceae
Sphenocleaceae
Poaceae
Poaceae
Verbenaceae
Orobanchaceae
Fabaceae
Asteraceae
Portulacaceae
Portulacaceae
Fabaceae
Fabaceae
Fabaceae
Fabaceae
Combretaceae
Combretaceae
Combretaceae
Asteraceae
Euphorbiaceae
Aizoaceae
Zygophyllaceae
Boraginaceae
Asteraceae
Malvaceae
Fabaceae
Typhaceae
Malvaceae
Asteraceae
Asteraceae
Asteraceae
Fabaceae
Fabaceae
Fabaceae
Fabaceae
Fabaceae
Fabaceae
Fabaceae
Malvaceae
Asteraceae
Araceae
Poaceae
Cucurbitaceae
Rhynchosia minima (L.) DC.
Rhynchosia sublobata (Schumach. & Thonn.) Meikle
Richardia scabra L.
Ricinus communis L.
Rottboellia cochinchinensis (Lour.) Clayton
Saccharum officinarum L.
Sapindus saponaria L.
Sesamum angustifolium (Oliv.) Engl.
Sesbania macrantha Welw. ex E.Phillips & Hutch.
Sesbania sesban (L.) Merr.
Setaria homonyma (Steud.) Chiov.
Setaria incrassata (Hochst.) Hack.
Setaria pumila (Poir.) Roem. & Schult.
Setaria verticillata (L.) P. Beauv.
Setcreasea purpurea Boom
Sida acuta Burm. f.
Sida alba L.
Sida cordifolia L.
Sida rhombifolia L.
Sida urens L.
Solanum campylacanthum Dunal
Solanum dasyphyllum Schumach. & Thonn.
Solanum incanum L.
Solanum lycopersicum L.
Solanum nigrum L.
Sonchus luxurians (R.E.Fr.) C.Jeffrey
Sorghum arundinaceum (Desv.) Stapf
Sorghum bicolor (L.) Moench
Sorghum versicolor Andersson
Spathodea campanulata subsp. nilotica (Seem.) Bidgood
Spermacoce pusilla Wall.
Spermacoce senensis (Klotzsch) Hiern
Sphenoclea zeylanica Gaertn
Sporobolus molleri Hack.
Sporobolus pyramidalis P. Beauv.
Stachytarpheta indica (L.) Vahl
Striga gesnerioides (Willd.) Vatke
Stylosanthes fruticosa (Retz.) Alston
Synedrella nodiflora Gaertn.
Talinum portulacifolium (Forsk.) Ascher. ex Schw.
Talinum triangulare (Jacq.) Willd.
Tephrosia linearis (Willd.) Pers.
Tephrosia nana Kotschy ex Schweinf.
Tephrosia pumila (Lam.) Pers.
Tephrosia purpurea (L.) Pers.
Terminalia catappa L.
Terminalia mantaly H.Perrier
Terminalia superba Engl. & Diels
Tithonia diversifolia (Hemsl.) A.Gray
Tragia brevipes Pax
Trianthema portulacastrum L.
Tribulus terrestris L.
Trichodesma zeylanicum (Burm.f.) R.Br
Tridax procumbens L.
Triumfetta rhomboidea Jacq.
Tylosema fassoglensis (Schweinf.) Torre & Hillc.
Typha domingensis (Pers.) Steud.
Urena lobata L.
Vernonia amygdalina Delile
Vernonia cinerea (L.) Less.
Vernonia melanocoma C.Jeffrey
Vigna luteola (Jacq.) Benth.
Vigna oblongifolia A.Rich. var. parviflora (Baker) Verdc.
Vigna parkeri Baker
Vigna unguiculata (L.) Walp. var. unguiculata
Vigna unguiculata subsp. sesquipedalis (L.) Verdc.
Vigna vexillata (L.) A. Rich.
Vigna vexillata (L.) A.Rich. var. angustifolia (Schumach. & Thonn.) Baker
Wissadula rostrata (Schumach.) Hook.f.
Xanthium strumarium L.
Xanthosoma sagittifolium (L.) Schott
Zea mays L.
Zehneria scabra (L.f.) Sond.
J. Bigirimana et al. / Landscape and Urban Planning 100 (2011) 251–267
Plant assemblages
TF11
Ecological group
% of species
R
S
P
SF
HF
W
Cu
Ecological group
R
S
P
SF
HF
W
Cu
Number of species
75
5
1
1
2
8
8
TF12
64
8
1
4
1
7
15
TF21
83
5
0
6
0
3
3
FT22
66
11
0
4
1
9
9
72
19
0
2
2
2
3
TF24
74
12
0
4
1
1
8
TF3
79
0
0
5
0
7
9
TF4
71
7
3
3
4
9
3
All species
62
9
1
5
1
8
14
% of species mean cover
96
3
0
0
0
1
0
94
3
0
0
0
2
1
98
1
0
0
0
1
0
91
2
0
1
0
5
1
11
88
0
1
0
0
0
20
79
0
0
0
0
1
98
0
0
0
0
1
1
71
1
25
0
1
2
0
92
5
1
0
0
1
1
176
337
36
90
131
169
43
113
404
the
Appendix B.
8.62 < 2df42, ˛5% = 58.1). For details about the plant assemblages (TF11, TF12, TF21, TF22, TF23, TF24, TF3, TF4), see
Table 1.
(X 2 = 3.56 < 2df28, ˛5% = 41.34, X 2 =
Geographical distribution (GD), geographical origin and origin
status of 404 species of the vegetation of Bujumbura (number of
species). Cosmopolitan (Cos), Paleotropical (Pal), Pantropical (Pan),
Afro-Asian (Af-As), Afro-Madagascarian (Af-Ma), African pluriregional (AP), Tropical African (T Af), East and South African (EA-SA),
East African (EA), Guineo-Congolian and Lake Victoria Regional
Mosaic (GC-V), Afromontane (Mo), Lake Victoria Regional Mosaic
(V) and Endemic to Western graben district (E). Native species (N):
with a continuous distribution including Burundi (N1 ), widespread
species that might be considered as native (N2 ). Introduced species
(I): with known origin (I1 ) and widespread species with unknown
origin not considered native (I2 ).
Life form and phytogeographical spectra of the species composing the plant assemblages in Bujumbura. Life forms: therophytes
(Th), chamaephytes (Ch), geophytes (G), hemicrytophytes (H),
phanerophytes (Ph). Distribution: widespread species (WS),
African species (Af), Endemic to the Lake Victoria Regional
Mosaic (V) and Endemic to Western Graben District (E). Origin status: Native species (N), Introduced species (I). Life form,
distribution and origin status spectra are not different between
TF12
assemblages
Appendix D.
Appendix C.
TF11
plant
2.23 < 2df21, ˛5% = 32.67 and X 2 = 1.07 < 2df7, ˛5% = 14.07
respectively). For details about the plant assemblages, see
Table 1.
Ecological spectra of the species composing plant assemblages
of Bujumbura (% of species and % of species mean cover): ruderal
species (R), savanna species (S), psammophile species (P), sclerophyllous forest species (SF), wetland species (W), hygrophilous
forest species (HF) and cultivated species (Cu). Percentages
of species mean cover differ between plant assemblages(X 2 =
91.17 > 2df42, ˛5% = 58.1), but % of species are not diffent (X 2 =
Plant assemblages
FT23
265
TF21
TF22
TF23
TF24
TF3
TF4
All plots
% of species
Life form
Th
Ch
G
H
Ph
44
29
13
5
9
42
30
11
6
11
33
45
6
6
6
36
28
11
13
12
47
28
6
8
11
50
26
6
8
10
32
42
12
0
14
44
35
8
5
8
41
29
12
6
12
Distribution
WS
Af
V
E
71
21
7
1
69
22
8
1
83
14
0
3
72
20
8
0
66
18
15
1
72
18
9
1
86
12
2
0
71
17
12
0
67
24
9
0
Origin status
I
N
48
52
47
53
61
39
41
59
37
63
44
56
58
42
44
56
43
57
Number of species
48
337
36
90
131
169
43
113
404
J. Bigirimana et al. / Landscape and Urban Planning 100 (2011) 251–267
266
Geographical origin
Origin status
GD
I1
Cos
Pan
Pal
Af-As
Af-Ma
AP
T Af
Mo
EA-SA
GC-V
EA
V
E
Total
Cos
Pan
Pal
Af-As
Af-Ma
AP
T Af
Mo
EA-SA
EA
GC-V
V
E
34
123
2
1
1
–
2
–
–
–
–
–
–
3
–
–
–
–
–
–
–
–
–
–
–
–
–
23
–
–
–
–
–
–
–
–
–
–
–
–
5
3
–
–
–
–
–
–
–
–
–
–
–
15
3
15
–
–
–
–
–
–
–
–
–
–
2
–
2
28
–
–
–
–
–
–
–
–
1
12
1
4
–
16
–
–
–
–
–
–
–
2
11
1
4
2
–
31
–
–
–
–
–
–
–
–
–
–
–
–
–
3
–
–
–
–
–
–
–
–
–
–
–
–
–
5
–
–
–
–
–
–
–
–
–
–
–
–
–
–
5
–
–
Total
%
163
40
3
1
23
6
8
2
33
8
32
8
34
8
51
13
3
1
5
1
5
1
%
I
1
1
–
–
–
–
–
–
–
2
–
–
–
–
–
–
–
–
–
–
–
–
–
–
38
–
–
–
–
–
–
–
–
–
–
–
–
–
2
40
192
10
26
33
34
53
3
5
4
5
38
2
10
48
2
7
8
8
13
1
1
1
1
9
0
34
123
2
1
1
–
2
–
–
–
–
–
–
1
7
2
–
–
–
–
–
–
–
–
–
–
–
–
–
33
32
34
51
3
5
4
5
38
2
2
16
6
–
–
–
–
–
–
–
–
–
–
4
1
38
9
2
0
404
100
163
40
10
3
207
51
24
6
I1
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