Journal of Natural Sciences Research
ISSN 2224-3186 (Paper) ISSN 2225-0921 (Online)
Vol.4, No.9, 2014
www.iiste.org
Phytosociological Study of Nyungwe Montane Savannahs
Prof Elias Bizuru1, Protais Niyigaba2, Myriam Mujawamariya3
1: Head of Biology department, Ag. Director of Post Graduate Studies, Research and publications in the
University of Rwanda
2: Park Guide in RDB - Nyungwe National Park and Master’s Student in Biodiversity Conservation, University
of Rwanda
3: Assistant lecturer and Researcher in the University of Rwanda
Email: ebizuru@gmail.com, protang2002@yahoofr, mmujawamariya@gmail.com
Abstract
It is uncommon to find savannahs encompassed into tropical montane rainforests. The case of Nyungwe
savannahs is one of these particularities and until now no explanation on their origin, structure and dynamics was
given. This unprecedented research documented special floristic diversity of montane savannahs of Nyungwe,
described the structure of their plant communities to provide data for their sustainable conservation. In this paper
origin of these savannahs was discussed. The study was conducted in three sites harbouring five
savannahs:Karamba, Nyabitimbo and Muzimu. Eight plant communities (4 in savannah-forest contact zone and
other 4 in savannah) were identified with 198 species. Vascular species were distributed in 71 families.
Phytogeographic distribution analysis of species showed the predominance of afromontane species (Mo) in
sampled savannahs (31%), followed by East African montane species (Mo, EA) with 22% of all species.
Montane endemism proved the predominance of ‘relatively restricted endemic species’ identified in 2or3
montane systems (among Kivu-Ruwenzori, ImatongsUsambara, UluguruMlanje, and Ethiopia with 41.1%)
followed by ‘afromontane endemic wades’ identified in 4to7 systems representing 39.9%). ‘Local endemic
montane species’ represented 31% of all species. Thus, these savannahs are favourable to species coming from
almost seven African montane systems.
Keywords: Nyungwe, Plant communities, montane savannahs.
Introduction
Nyungwe National Park montane savannahs are high-altitude savannahs, located in a few spots throughout the
montane forest. From a general climatic point of view, and according to the terracing pattern of vegetation in
tropical mountains as highlighted by Schnell (1977) and cited by Bizuru (2005), these regions should be covered
by evergreen montane and submontane forests. The forest cover at some places in Nyungwe National Park
changes abruptly to savannah stretches which have long been viewed as anthropogenic artefacts neglected by
scientists and of no interest to conservation (Perrier de la Bâthie, 1936; Dalfelt et al., 1996 & Banerjee, 1995
cited in Bond and Parr, 2010).
The neglect of savannahs and grassy habitats by scientists and researchers is noticed by simply considering all
researches that, so far, have been carried out on the whole flora of Nyungwe. Although the savannahs are among
the five plant habitats recognized by Ewango (2001) following the 1999 Nyungwe plant inventory, there has
been no studies devoted exclusively to montane savannahs.
Savannahs, compared to the bigger part of closed forest, are easy targets for clearing for cropping. They are
easier to convert to crops and their degradation is not considered as a serious environmental attack compared to
the clearing of forests. They constitute a breach that facilitates illegal activities to access the forest; where for
example beekeepers prefer these places particularly for laying their hives. Savannahs have been often noticed to
be epicentres of different destructive bushfires that, along the history of Nyungwe, decimated large tracts of
other habitats such as the closed evergreen primary forest, the secondary forest and bamboo areas.
Nyungwe mosaics of forest and savannah vegetation occur in various corners, and the concern of this study was
to understand both ecosystem states in order to provide conservation measures for their floristic diversity
sustainability. This study is a good contribution that documents the special floristic diversity of montane
savannahs of Nyungwe, describing the structure of their plant communities in order to provide scientific data for
sustainable conservation of Nyungwe and particularly montane savannahs. The main ecological drivers that
created these savannas in these areas are outlined, and their future is predicted.
Materials and Methods
Study area
The study was carried out in Nyungwe National Park which is located on the edge of Lake Kivu in the South
West of Rwanda (2°15' – 2°55' S, 29°00'– 29°30' E). This region is located in the valleys of the Albertine Rift
eco-region (Plumptre et Al, 2002). Nyungwe National Park is the largest protected area of Rwanda (Appendix 1).
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ISSN 2224-3186 (Paper) ISSN 2225-0921 (Online)
Vol.4, No.9, 2014
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The mean annual rainfall of 1.744 mm (Sun et al., 1996 cited in Plumptre et al., 2002) is typical for an African
rainforest. A major dry season occurs between July and August and a minor dry season takes place between
December and January.
Specifically, the study was carried out in three chosen sites: Karamba with one savannah located between 1965m
and 1997m of elevation, Nyabitimbo with 3 savannahs (Ubunyovu bw’Abasozo with altitude varying between
1728m and 1771m, Ubunyovu bw’Imbaragasa I with altitude varying between 1750m and 1820m, Ubunyovu
bw’Imbaragasa II with altitude varying between 1768m and 1908m), and Muzimu with one savannah located
between 2770m and 2822m of altitude (Appendix 2).
Karamba is open grassland presenting some scattered trees and shrubs at some points. The soil is made of a very
thin layer of humus covering rocks and mainly quartz. At several points of this savannah, wide bare areas of
quartz are remarkable. The centre of Karamba savannah is a flat and often inundated place where soaked carpets
of species like Sphagnum sp. (characteristic of acidic wetlands) are met. This stagnation of water is due to the
impermeability of the quartz substrate. More distant areas (towards the periphery) are gentle, dry and more or
less bare slopes.
The site of Nyabitimbo has three aligned savannahs. Located from the East of the site is the Ubunyovu
bw’Abasozo, in the middle is Ubunyovu bw’Imbaragasa I, and at the eastern side of the site is Ubunyovu
bw’Imbaragasa II savannahs. These are familiar and ancient names given to these savannahs by local people; the
term ‘ubunyovu’ is equivalent to ‘savannah’.
All the three savannahs are commonly characterized by a thick (around 1m) carpet of old Eragrostis that makes
the walk too hard in these areas. They are almost mono-specific grasslands dominated by Eragrostis on slopes
with many areas occupied by protruding rocks. Their average slope is more or less than 45°. The soil is shallow
black humus on quartz rock. Some scattered places are dominated by Erica johnstonii and others by Protea
welwitschii.
Muzimu is among the highest mountains (2830m) in NNP after mount Bigugu (2950m). The savannah occupies
a big part of the top of mount Muzimu. The soil is shallow black humus which is sandy and/or stony. The eastern
part is drier and rockier with some protruding rocks.
Muzimu - among other studied savannahs - has the particularity of harbouring up to five different Ericaceous
species (Blaeria kiwuensis, Erica bequaertii, Erica benguellensis,Vaccinium stanleyi, and Agauria salicifolia).
This richness in Ericaceous species can be accounted for by the fuzzy state of the border between savannah and
the Ericaceous shrub. The ericaceous shrub is described by Fischer & Killmann(2008). The flora of Muzimu is
also characterized by important number of particular species distinguishing it from other savannahs studied such
as Blaeria kiwuensis, Isachne mauritiana, Struthiola thomsonii, Lobelia holstii and Hedythyrsus thamnoideus.
This particular flora of Muzimu can be explained by the difference in elevation and geographical distance. This
savannah solely ranges above 2000m of altitude (between 2770m and 2822m) whereas other savannahs are
located between altitude of 1728m and 1990m. Frequently, the savannah on top of Muzimu is blown by cold
winds, which constitute another important factor that induces particular ecological conditions. Muzimu is
geographically distant compared to the other two sites. Contrary to other savannahs, no inundated places were
encountered; the species like Sphagnum were not recorded.
The vegetation sampling was done according to Braun-Blanquet (1932) method using mixed sampling. Plant
species were inventoried in plots of (5mx5m) within the savannah and (5x10) in the savannah-forest contact zone.
Detrended Correspondence Analysis (DCA) with MVSP software was used to identify plant communities. In
total 174 plots were sampled, with 48% of the total surface located within the savannahs and the remaining 52%
in the savannah-forest contact zone.
Biological forms
Biological forms were determined using the methodology proposed by Raunkiaer (1932). According to this
methodology, biological forms are determined and distinguished on basis of various mechanisms used by plants
to protect their buds or their vegetative organs during unfavourable season.
Phanerophytes (Ph): plants that remain visible in all seasons of the year; their height above the ground is above
0.5 m; their vegetative apparatus holds persistent visible buds at a height of more than 40 m above the ground.
Chamaephytes (Ch): plants with a dwarf vegetative apparatus (less than 40 cm of height). Hemicryptophytes
(Hc) are characterized by an aerial vegetative apparatus which dries out during the unfavourable season.
Geophytes (Ge): plants with underground reserve organs from which they quickly propagate at the beginning of
the favourable season.
Therophytes (Th): annual plants that pass the unfavourable season in the form of seeds.
Phytogeographic distribution
Species were classified into Phytogeographic types according to their distribution. They include Cosmopolitans
(Cosm), Sub-cosmopolitans (Subcosm), Pantropicals (Pantr), Paleotropicals (Paleo), Montane paleotropicals
[Paleo (Mo)], Afro-Americans (Af-Am), Afro-Malagasy (Afro-Mal), Montane Afro-Malagasy [Afr-Mal (Mo)],
Multiregional africans (Pluri af), Afro tropical (Afr trop), Spieces with Sudano-zambezian distribution (S-Z),
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Species of Afro montane region (Mo) , East African (EA), Endemic species (End).
Vegetation analysis
The presence index was attributed to species according to Vander Bergen (1982) and the plant communities were
individualized using multivariate analysis of all the study sites data. A data matrix with two inputs was treated
using Correspondence Factorial Analysis for the identification of the existing plant communities.
The floristic diversity of different communities and sites was calculated according to Simpson’s diversity index
formula which takes into account both the species number and their cover-abundance dominance:
′
=1−
( )2
Where D’ = Simpson floristic diversity index
Pi = proportion of species in a community
1= Simpson’s ideal diversity index
The montane endemism was expressed by the distribution and representativeness of species in the seven regional
montane systems. These latter include: West African, Ethiopian, Kivu-Ruwenzori, Imatongs-Usambara,
Uluguru-Mlanje, Chimanimani and Drakensberg regional montane systems. Floristic similarity between
savannah areas was calculated using Sorensen’s coefficient. Similarity between communities and zones was
estimated according to the species number and their abundance using cluster analysis. Linkages were determined
using the method of unweighted pair-group (UPGMA), which uses arithmetic averages to evaluate the distances
between clusters.
Results
Plant species composition, diversity, and floristic similarity
A total of 174 plots were sampled, with 48% of the total surface located within the savannahs and the remaining
52% in the savannah-forest contact zone. A total number of 198 plant species in all the three sites were identified.
Also listed are 147 genera and 71 families only among vascular species.
Sixty one (61) plots were selected in the savannah-forest contact zone and 133 plots in the savannah zone. One
hundred sixty (160) species in the savannah-forest contact zone distributed in 129 genera and in 67 families were
identified. The inventory in the savannah zone was composed of 109 plant species, 95 genera and 43 families
(Appendix 3). The numbers above represent tracheophytes only. During fieldwork both tracheophytes and non
tracheophytes (lichens and bryophytes such as Sphagnum planifolium and mosses) were observed as whole
floristic diversity and ecology of NNP’s savannahs. However, due to the lack of enough equipment
(identification keys, reference herbarium specimens and other documents) for their identification, most of non
tracheophytes species were not fully identified.
The Comparison of floristic diversity between the savannahs and the savannah-forest contact zone (Appendix 3)
showed that according to species relative frequency, the most frequent species (appearing in most of the 174
sampled plots) were: Pycnostachys erici-rosenii (present in 62.6% of all the plots), Eragrostis olivacea (55.1%),
Virectaria major (48.2%), Scleria distans (47.7%), Panicum adenophorum (41.9%), Bothriocline nyungwensis
(38.5%), Microglossa pyrifolia ( 38.5%), Melinis tenuinervis (36.7%), Polygala ruwenzoriensis (34.4%), and
Anisopappus africanus (33.3%). It should be noted that the first and third species are generally characteristic to
disturbed areas.
In terms of cover-abundance, the most dominant species in the whole studied areas were Eragrostis olivacea
(22.4% of the total surface area) and Eragrostis boehmii (11%). The most represented families were Orchidaceae
(represented by 17 species, which is equivalent to 9.1% of the tracheophytes), Asteraceae (16 species i.e. 8.6%),
Poaceae (15 species i.e. 8.1%), Rubiaceae (15 species i.e. 8.1%), Cyperaceae (8 species i.e. 4.3%),
Euphorbiaceae (7 species i.e. 3.7%), Melastomataceae (7 species i.e. 3.7%) and Ericaceae (6 species i.e. 3.2%).
However, in terms of cover-abundance, the most abundant families are Poaceae (covering 42.5%), Asteraceae
(covering 7.8%), Dennstaedtiaceae (covering7.4% though represented by one species “Pteridium aquilinum”)
and Ericaceae (covering6.8%). Other families were Lamiaceae(6.6%) and Rubiaceae(4.7%).
In terms of frequency, Poaceae are found in 18% of all the plots, followed by Asteraceae (15%), Rubiaceae and
Lamiaceae(8%), Cyperaceae(5.7%), and Melastomataceae(4.1%). Phytogeographic distribution of species
showed the predominance of afromontane species (Mo) (31%), in all the sampled savannahs followed by the
East African montane species (Mo (EA)) with 22% of all species. Sclerochores or light non fleshy diaspores
were the most abundant and the most represented covering 59% of NNP montane savannahs. At the second
position were Ballochores covering 22% of the NNP montane savannas.
The cluster analysis of the three study sites showed the similarity between Karamba and Nyabitimbo rather than
with Muzimu(Appendix 4). In fact, the savannah on top of Muzimu is located between 2770m and 2822m of
altitude whereas the other two sites are located between 1728m and 1990 m of altitude. This difference in
elevation gives to Muzimu a particular high altitude flora that distinguishes it from the two other lower sites.
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Given Karamba’s highest species number, only 50% of its species are shared with Muzimu whereas 68.6% are
common between Karamba and Nyabitimbo.
Floristic similarity among the three study sites is presented in Appendix 4.Tthe distribution and
representativeness of species according to White (1978)’s seven regional montane systems show that 31
species(i.e.19%) are local endemics, thus belonging exclusively to Kivu-Ruwenzori. Other 67 species(i.e.41.1%)
are ‘relatively restricted endemic species’ and are distributed in two or three regional montane systems. This
study also showed that 65 ‘Afromontane endemic wides’(i.e. 39.9%) are distributed at least in four of the seven
montane systems, thus corresponding to the largely distributed species. Among all the recorded species, 59.5%
are also found in Imatongs-Usambara, 52.14% in Uluguru–Mlanje, 41.71% in Ethiopian System, 35.58% in
West African System, 32.51% in Chimanimani, and 15% in Drakensberg montane System.
In general a big number is common between Kivu-Ruwenzori and East African montane Systems (ImatongsUsambara, Uluguru–Mlanje, and Ethiopian) (Appendix 7).
The cluster analysis shows affinity between Kivu-Ruwenzori and the East African montane systems (ImatongsUsambara, Ulugulu-Mlanje and the Ethiopian System) (Fig. 1). West African species are more represented than
species from Southern Africa (Fig. 1). Therefore, the West African System is closer to Kivu-Ruwenzori than
Southern Africa systems (Drakensberg and Chimanimani).
Fig.1: Floristic similarity among the seven montane systems. I: We-Af : West African System. II: Eth: Ethiopian
System. III: Ki-Ru : Kivu-Ruwenzori System. IV: Im-Us : Imatongs-Usambara System. V: Ul-Mu: Uluguru–
Mlanje System. VI: Chi : Chimanimani System. VII: Dra : Drakensberg System.
The Factorial Correspondence Analysis enabled the identification of the following eight plant communities:
individualization of plant communities in the savannah zone(Appendix 5) and individualization of plant
communities in the savannah-forest contact zone(Appendix 6)
The study of the plant communities’ proper values enabled the individualization of plant
communities(Appendices 5&6) by highlighting the statistical differences. The cumulative variances on the two
forth axes are more than 15% (i.e. 21.765% in the savannah-forest contact zone and 18.477% in the savannah)
and thus these values are high enough to enable the distinction and separation between plant communities in both
the savannah and ecotone zones. Savannah communities’ indices varied between 0.542 and 0.847 whereas the
savannah-forest contact zone indices vary between 0.840 and 0.941. In fact, savannahs comprise very few
species and thus appear as monospecific areas occupied mainly by Eragrostis and other few Poaceae species.
The savannah-forest contact zone, by contrast, is inhabited by both forest and savannah species, which makes its
flora even and diversified.
Discussion
For all the studied savannahs, the predominance of Poaceae as the most abundant family covering 42.5% of the
savannahs was noticed. Poaceae were followed by Asteraceae(7.8%), Dennstaedtiaceae(7.4% though represented
by one fern species Pteridium aquilinum), Ericaceae (6.8%), Lamiaceae(6.6%) and Rubiaceae(4.7%).
In general, the savannah–forest contact zone possesses a higher specific richness compared to the savannah
zone(Appendix 3). The former encompasses ecological conditions of both habitats (forest and savannah) and
thus allows, at the same time, the installation of savannah species and forest ones. As for the savannah zone, the
poor floristic diversity is due to stress undergone by species inhabiting these areas. Most of the savannah covered
areas in NNP are dry rocky slopes covered with a very shallow soil, which allows only the installation of drought
and poor soil tolerant species.
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Though Karamba is the smallest site, its varied ecological sub habitats allow the presence of various species. The
dry rocky slopes; the inundated flat areas, valleys, the presence of a trail that passes in the middle of the
savannah and the presence of a temporary stream are various ecological conditions that explain the highest
diversity index. As for Nyabitimbo, its three savannahs make it the widest site among the three study sites.
However, its poverty in species is visible even with simple observation. Its savannahs are old and almost
monospecifically dominated by Eragrostis which makes a thick carpet of grass matter and dead boles.
Throughout the studied savannahs, afromontane species were the most represented Phytogeographic types with
30.5% of all the species, covering 11.3% of the sampled area and present in 18.4% of the sampled plots. East
African montane species were also the most abundant, covering 12.5%, of the sampled area, representing 20.3%
of all the species and present in 9% of all the sampled plots. Afro-tropic species were in the third position,
followed by Afro-Malagasy species.
As far as diaspores are concerned, and according to their classification by Dansereau & Lems(1957) cited in
Habiyaremye(1995), Sclerochores or light non fleshy diaspores are the most abundant in NNP montane
savannahs. Sclerochores, due to their lightness are more likely to be dispersed by wind. The south-easterly trade
winds that blow in the Albertine Rift originating from the Indian Ocean play a big part in this long distance
dispersal which emphasises once more, the high representativeness of East African montane systems in NNP
montane savannas.
The cluster analysis of the three study sites showed the similarity between Karamba and Nyabitimbo rather than
with Muzimu.
As far as the distribution in the seven regional montane systems is concerned, an uneven representativeness of
species was noticed. Among the recorded species, 59.5% are also found in Imatongs-Usambara, 52.14% in
Ulugulu-Mlanje; 41.71% in Ethiopian System, 35.58% in West African; 32.51% in Chimanimani and 15% in
Drakensberg system. The cluster analysis shows a high similarity between the East African montane Systems
(UL-Mu, Im-Us, and then Ethiopian System) which, at the same time, exhibits an explicit affinity with KivuRuwenzori system (Fig. 1).
Hedberg(1966) cited in Bizuru(2005), indicated that the floristic affinity noticed among East African systems
can be explained by direct and indirect contacts among afromontane vegetation facilitated by geographic
distance. The author further emphasized that direct contacts including the lowering of the afromontane region, a
phenomenon that brought about mixture and breeding among the flora of East African Mountains during the
Quaternary glaciations. The low similarity between Kivu-Ruwenzori and the South African montane Systems
(Chi. and Dra.) on one hand, and its higher affinity with Ethiopian System on the other hand, show that the data
are in accordance with Moreau’s north corridor theory.
Moreau(1966) cited in Bizuru(2005) believes the existence of a certain ‘north corridor’ that connects Mt.
Cameroon to Ethiopia, passing at Mt. Jebel Marra in Sudan which is halfway between Cameroon and Ethiopia.
However, White(1981) cited in Bizuru(2005), on basis of 40 tree and smaller plant species, stated that the
connection between Mt. Cameroon and East African mountains passes though the ‘south corridor’.
Using Simpson’s diversity index, it was noticed that savannah communities are less floristically diversified than
savannah-forest contact zone ones. The most diversified of all was the community comprised of Clerodendrum
johnstonii and Virectaria major (Simpson’s index equals to 0.941) which constitute some spots contouring
Karamba and Nyabitimbo. This followed by the community of Pteridium aquilinum and Pycnostachys ericirosenii (0.941) also constituting the contour of Karamba and Nyabitimbo.
The general abundance of Therophytes in the savannah zone communities are a sign or a trace marking the aftereffects of ancient disturbance. Savannahs are epicentres of devastating bushfires that cleared large tracts of
Nyungwe forest along its history. The abundance of Phanerophytes in the savannah-forest contact zone
communities is an indicator of woody species predominance which proves the encroachment of the forest on
savannahs. Moreover, the prevalence of species like Pteridium aquilinum is a sign of the forest invasion at the
expense of savannahs.
Climate change, conservation, origin and the future of NNP montane savannahs
Maley(1991) showed that Quaternary glaciations corresponded to the global scale coldest periods as well as the
maximum fragmentation of tropical forests. Pollen analyses carried out on upper Quaternary deposits from
African lakes showed that during the last world glacial maximum (which peaked 18 000 years before present)
the climate was dry and cold and forest much reduced and fragmented. The extent of forest must have oscillated
greatly. These glacial periods characterized by extreme colds and rare precipitations correspond to the maximum
extension of savannas replacing tropical forests. As it happened to other tropical rain forests, some tracts of
Nyungwe forest must have been converted into savannas during the Quaternary glaciations period. When the
climate was normalized again, some savannah parts were restored to their former rainforest state and others were
maintained as savannas by various parameters namely natural and human induced bushfires and dry and/or poor
substrate (soil). Nyungwe montane savannas are characterized by shallow humus that covers quartz substrate and
by a common presence of protruding rocks visible on most of the slopes.
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The abundance of Therophytes in the savannas is an after-effect of ancient disturbance especially bushfires. With
the current forest protection measures, these savannas are unlikely to undergo frequent fires as it used to be;
which means that the only remaining maintaining factor of Nyungwe montane savannas is the substrate nature.
The progressive accumulation of litter falling from the neighbouring forest and the progressive decomposition of
grass matter will - step by step- favour the installation of forest species at the expense of savannah ones.
Bond & Parr (2010) suggested that forest expansion in forest/grassland mosaics is likely to be a major threat in
protected areas where different mechanisms are put in place in order to thwart fire spread. Fire exclusion
experiments in Africa and the USA showed that high rainfall savannas can be replaced by forest in as little as
20–30 years.
Conclusion
The current phytosociological study covered five Nyungwe montane savannahs where both the savannah and its
contouring savannah-forest contact zone were explored. Angiosperms cover the biggest part of the total flora;
Pteridophytes come at the second place followed by Bryophytes whereas Lichens cover an insignificant part of
the entire inventoried flora. Therophytes are abundant in the four communities of the savannah zone whereas
Phanerophytes are abundant in the other four communities of the forest-savannah contact zone. These biological
forms proportions show the persistence of ancient disturbance after-effects.
NNP montane savannahs are dominated by afro-montane and East African species which corroborates with the
similarity highlighted by the montane endemism analysis. The similarity between Ki-Ru and East African
montane systems confirms that there is a relationship with the floristic composition of East African savannahs
located in the Lake Victoria basin mosaic. Though these Acacia dominated savannahs differ physiognomically
from NNP montane savannahs, the strong similarity in floristic composition is confirmed by both
Phytogeographic distribution and the montane endemism analysis. Sclerochores or light non fleshy diaspores
constitute the most abundant type of diaspores, which predicts wind as another way of contact between NNP
montane savannahs and East African diaspores.
Given the shallowness of humus that covers a quartz substrate and the common presence of protruding rocks in
most of the savannah slopes, NNP savannahs can be qualified as ancient savannas maintained by edaphic
conditions. The lack or insufficiency of humus combined with the rocky substrate unable to retain water
constitutes the major explanation of the persistence of savannahs in a place expected to be occupied by a rain
forest.
Savannah-forest contact zone harbours communities where species like Pteridium aquilinum are abundant,
which indicates the initial phase of forest installation. Nyungwe montane savannahs are being progressively
encroached on by their matrix. The accumulation of litter which falls from the surrounding trees increases the
thickness of humus and thus gives way to the invasion of forest species which are shade tolerant at the expense
of savannah ones which are shade avoiders.
In general, NNP montane savannahs’ specific diversity is low where an average of one species is estimated to
inhabit one plot. However, these grassy spots distributed in different corners of NNP are home to a big number
of savannah typical species which cannot be found elsewhere in the forest.
With reference to the conclusions above, researchers should document the full list of Nyungwe montane
savannahs, survey the speed at which forest is encroaching on the savannahs so as to take appropriate
conservation measures. Nyungwe managing authorities should also avoid practicing assisted forest regeneration
in these savannah natural habitats. Instead, they should strengthen the protection and increase patrols around
savannah areas because they are easy targets of illegal activities due to their easy accessibility.
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www.iiste.org
Germany: Series Biogeographical Monographs, Koblenz Geographical Colloquia, 771p.
Habiyaremye, M. K. (F.X) ,1995. Etude phytocoenologique du dorsal oriental du lac Kivu (Rwanda). Thèse
présentée pour l’obtention du grade de Docteur en Sciences. Bruxelles : Faculté des Sciences, université de
Bruxelles.
Maley, J., 1991. The African rainforest vegetation and palaeoenvironnments during late Quaternary.
Netherlands : Kluwer Academic Publishers. Climatic change 19:79-98, 1991
Marchant, R., (2010). Understanding complexity in savannas: climate, biodiversity and people, Curr Opin
Environ Sustain (2010), doi:10.1016/j.cosust.2010.03.001
Plumptre, A., J., Masozera, M., Fashing, P. J., McNeilage A., Ewango C., Kaplin, B., A. & Liengola I., (2002).
Biodiversity Surveys of the Nyungwe Forest Reserve in S.W. Rwanda. WCS Working Paper Series, pp. 96.
Scholes, R.J. & Archer, S.R., 1997. Tree – grass interactions in savannas. Annual Review of Ecology and
Systematics 28, pp.517–544.
Troupin, G., (1978). Flore du Rwanda, Spermatophytes, Volume I. Tervuren :Musée Royal de l’Afrique Centrale,
413 p.
Troupin, G. (1982). Flore des plantes ligneuses du Rwanda. Tervuren : Musée Royal de l’Afrique Centrale, 747p.
Troupin, G. (1983). Flore du Rwanda, Spermatophytes, Volume II. Musée Royal de l’Afrique Centrale, Belgique
Troupin, G., (1971). Syllabus de la flore du Rwanda, Spermatophytes. Tervuren: Musée Royal de l’Afrique
Centrale, 143 p.
White, F., 1978. The Afromontane Region. Dr.W. Junk b.v. Publishers The Hague. Biogeography and Ecology of
Southern Africa, pp.465-510
Appendices
Appendix 1: Map of the location of Nyungwe National Park (NNP) in relation to other protected areas in
Rwanda (ORTPN, 2005).
N
N y u n g w e N a tio n a l P a r c
C y a m u d o n g o F o re s t
73
Journal of Natural Sciences Research
ISSN 2224-3186 (Paper) ISSN 2225-0921
0921 (Online)
(On
Vol.4, No.9, 2014
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Appendix 2: Savannas
as in NNP
NN and localization of the study sites (Source: WCS/PCFN,
WCS/PC
edited)
Appendix 3: Comparison
on of floristic diversity between the savannahs and the savannah
avannah-forest contact zone
180
160
Number of Taxa
140
120
100
80
Savannah-forest
forest contact
c
zone
60
Savannah zone
40
20
0
Families
Genera
Species
Taxa distribution
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Appendix 4: Floristic similarity among the three study sites
UPGMA
Muzimu
Nyabitimbo
Karamba
0.28
0.4
0.52 0.64 0.76 0.88
1
Sorensen's Coefficient
Appendix 5: Individualization of plant communities in the savannah zone
I: Eragrostis boehmii and Sphagnum planifolium community
II: Eragrostis boehmii and Exotheca abyssinica community
III: Eragrostis olivacea and Eragrostis boehmii community
IV: Erica bequaertii and Eragrostis olivacea community
Appendix 6: Individualization of plant communities in the savannah-forest contact zone
V: Clerodendrum johnstonii and Virectaria major community
VI: Pteridium aquilinum and Pycnostachys erici-rosenii community
VII: Dichaetanthera corymbosa and Nephrolepis undulata community
VIII: Hedythyrsus thamnoideus and Hypericum revolutum community
75
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Appendix 7: Phytogeographic distribution of afromontane species in Nyungwe montane savannas.
I:We-Af : West African System, II: Eth: Ethiopian System, III:Ki-Ru : Kivu-Ruwenzori System, IV: ImUs :Imatongs-Usambara System, V: Ul-Mu: Uluguru–Mlanje System, VI: Chi : Chimanimani System, VII: Dra :
Drakensberg System.
SPECIES
Begonia meyeri-johannis Engl.
Blaeria kiwuensis (Engl.) Alm. & Th.Fries
Bothriocline nyungwensis WECHUYSEN
Bothriocline ruwenzoriensis (S.Moore)C.Jeffrey
Cincinnobotrys oreophila Gilg
Cissus sp.near oliveri(Engl)GILG.
Clutia paxii Knauf
Coleus edulis VATKE
Cyperus denudatus L.f
Cyperus dichrostachyus HOCHST
Entandrophragma excelsum (Dawe & Sprague) Sprague
Harungana montana Spirlet
Impatiens purpureo-violacea Gilg.
Isodon ramosissimus (Hook.f.) Codd
Lobelia holstii Engl.
Ocimum basilicum L.
Pentas longiflora Oliv.
Plectranthus serrulatus (Robyns) Troupin & Ayobangira
Polygala engleri CHODAT
Polystachya adansoniae RCHB.var. elongata SUMMERH
Polystachya pachychila (SUMMERH)
Polystachya woosnamii RENDLE
Pycnostachys erici-rosenii ROB.E.FRIES
Rhipidoglossum ovale (Summerh.) Garay
Schefflera myriantha (Baker) Drake
Senecio mariettae Muschl.
Senecio nyungwensis Macquet
Tristemma leiocalyx Cogn.
Utricularia troupinii P.TAYLOR
Vaccimium stanleyi Schweinf.
Vernonia scaettae Humbert & Staner
Agauria salicifolia (Commers.ex Lam.)Hook.f.ex Oliv.
Agelanthus brunneus(Engl.)Balle & Hallé
Alchornea hirtella BENTH
Alectra sessiliflora (Vahl) Kuntze
Andropogon diimeri STAPF
Anisopappus africanus (Hook.f.) OLIV. et HIERN.
Carex echinochloe KUNZE
Conyza hochstetterii Schultz-Bip.
Conyza sumatrensis (RETZ) E. K. WALKE
Crassocephallum paludum C.Jeffrey
Cynorkis kassneriana Kraenzlin
Dodoneya viscosa Jacq.
Erica benguellensis Welwitsch. ex. Engl.) E.G.H.Oliv.
Erica bequaertii De Wild.
Erica johnstonii (SHWEINF.ex Engl.)Dorr
Faurea saligna Harvey
Habenaria macrostele Summerh.
Habenaria malacophylla Rchb.f.
Harungana madagascariensis Poir.
Hibiscus noldeae Bak.f.
Keetia gueinzii (Sond.)BRIDSON
Laurembergia tetrandra (SCHOTT ex.SPRENG.)KANITZ
Lindernia subracemosa De Wild.
Lipocarpha chinensis (Osbeck) Kern
Maytenus acuminata (L.f.) Loes.
Microglossa pyrifolia (Lam.) O.KUNTZE
Mimulopsis arborescens C.B.Clarke
Otiophora pauciflora BAK. ssp. burtii (Milne-Redh.) Verdc.
Panicum adenophorum SCHUMANN
Phyllantus odontadenius Muell.Arg.
Polygala ruwenzoriensis CHODAT
III:KIRu
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
76
IV:I
mUs
V:ULMu
II:Eth
VI:C
hi
VII:D
ra
I:OuAf
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
Journal of Natural Sciences Research
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Vol.4, No.9, 2014
SPECIES
Sapium ellipticum (Hochst. Ex Krauss) Pax
Tabernaemontana stapfina Britten
Tapinanthus constrictiflorus (Engl.) Danser
Triumfetta cordifolia A. Rich.
Albizia gummifera (J. Gmelin) C.A.Smith
Brachiaria scalaris PILGER
Bulbophyllum burtii SUMM
Bulbophyllum vulcanicum Kraenzl.
Clausena anisata (Willd.) Benth.
Cyathea maniana Hook.
Dissotis ruandensis Engl.
Eragrostis boehmii (Hack)
Eragrostis olivacea SCHUMANN
Geranium arabicum Forssk.
Hedythyrsus thamnoideus (K.Schum.) Bremek.
Hypoxis kilimanjarica Baker
Ipomoea involucrata Beauv.
Kotschya aeschynomenoides (Baker) De Wit.& Duvign.
Lobelia gibberoa Hemsl.
Lobelia mildbraedii Engl.
Macaranga Kilimandscharica Pax
Maesa lanceolata Forssk.
Musanga leo-errerae (Hauman & J. Léonard
Ocotea usambarensis Engl.
Pentadesma reyndersii Spirlet
Pentas zanzibarica (Klotzsch) Vatke
Pseudosabicea arborea (K.SCHUM) HALLE ssp bequaertii
(DEWILD) VERDC.
Psychotria mahonii C.H.WRIGHT
Rubus pinnatus WILLD
Rubus runssorensis Engl.
Rubus steudeneri Schweinf.
Rumex abyssinicum JACQ
Rutidea orientalis BRIDSON
Senecio maranguensis O.HOFFM
Spermacoce princeae(K.Schum.)Verdc.
Urera hypselodendron (Hochst. ex A. Rich.) Wedd.
Anthocleista grandiflora Gilg
Bersama abyssinica FRESEN
Biophytum helenae Buscal. & Muschler
Bridelia brideliifolia (Pax) Fedde
Dalbergia lactea Vatke
Dichaetanthera corymbosa (Cogn.) Jacq.-Felix
Digitaria longiflora (RETZ) PERS.
Dissotis brazae Cogn.
Gouania longispicata ENGL
Hagenia abyssinica (Bruce) J.F.Gmelin
Hallea stipulosa (DC.)Leroy
Impatiens niamniamensis Gilg
Ixora burundiensis Bridson
Lagenaria sphaerica (Sond.) Naud.
Mimulopsis solmsii SCHWEINF
Polyscias fulva (Hiern) Harms
Polystachya bifida Lindl.
Polystachya lindblomii Schltr.
Struthiola thomsonii Oliv.
Urera trinervis (Hocst.) Friis & Immelmann
Carapa grandiflora SPRAGUE
Clematis simensis Fresen.
Clutia abyssinica Jaub.& Spach
Eriosema montanum BAK.f.var.montanum
Hymenodictyon floribundum (Hochst.& Steud.) Robbr.
Impatiens burtonii Hok.f.
Kyllinga stenophylla K.Schum. ex C.B. Clarke
Myrianthus holstii Engl.
Podocarpus falcatus (Thunb.) R.Br. ex Mirb.
SPECIES
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III:KIRu
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
III:KI-
77
IV:I
mUs
V:ULMu
II:Eth
VI:C
hi
VII:D
ra
I:OuAf
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
IV:I
x
x
x
x
x
x
x
x
x
V:UL-
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
II:Eth
x
x
x
x
x
x
x
x
x
VI:C
VII:D
x
I:Ou-
Journal of Natural Sciences Research
ISSN 2224-3186 (Paper) ISSN 2225-0921 (Online)
Vol.4, No.9, 2014
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Ru
Protea welwitschii ENGL ssp.adolphi-friderici(Engl.)BEARD
Pycreus nigricans (Steud.)C.B.Clarke
Sericostachys scandens Gilg & Lopr.
Aframomum mala (K.Schum.) K.Schum.
Clerodendrum johnstonii OLIV.
Cyanotis barbata D.Don.
Cynorkis anacamptoides Kraenzl.
Embelia schimperi Vatke
Exotheca abyssinica(HOCHTS.ex A.RICH) ANDERSON
Helichrysum forskahlii (J.F.GMEL) HILLARD
Helichrysum helvorum Moeser
Helichrysum panduratum O. HOFFM
Helichrysum schimperi (SCHULTZ-BIP) MOESER.
Isachne mauritiana Kunth
Liparis bowkeri HARV
Lycopodium clavatum L.
Melastomastrum capitatum (Vahl) A. & R.Fernandes
Paspalum scrobiculatum L.
Satyrium trinerve Lindl.
Secamone racemosa (Schltr.)Liede
Virectaria major (K.Shwum.)Verdc.
Xyris capensis THUNB.
Eulophia horsfalii (Batemann) Summerh.
Floscopa glomerata (Willd. & Schult. Ex Schult.f.) Hassk.
Hypericum revolutum Vahl.
Melinis tenuissima STAPF
Myrsine melanophloeos (L.) R.Br
Prunus africana (Hook.f.) Kalkm.
Rhytachne rottboelioides DESF
Rubus apetalus Poir.
Scleria distans Poir.
Setaria megaphylla (Steud.) Th.Dur. & Schinz
Smilax anceps Willd.
Syzigium guineense (Willd.)D.C.ssp. parvifolium (Engl.)F.White
Themeda trianda FORSK
Tristemma mauritianum J.Gmelin
Total
%
Simpson's diversity index
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
163
100
0.994
78
mUs
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
97
59.5
0.99
Mu
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
hi
ra
x
x
Af
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
85
52
0.988
68
41.7
0.985
53
32.5
0.981
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
25
15.3
0.96
58
35.5
0.983
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