East African Mountains Research Articles

Food security versus biodiversity protection: an example of land-sharing from East Africa

The recent controversial debate on land-sharing versus land-sparing is clearly exemplified in the East African mountains, one of the most diverse biodiversity hotspots on our planet. In these areas, species richness is particularly concentrated in the mountain cloud forests which are surrounded by a sea of dry lowland savannas heavily encroached on by local communities. Sustainable land use practices in the lowlands, however, are necessary to safeguard the natural capital at higher elevations. The interdependence between sustainable land-use and conservation of biodiversity hotspots was underlined during a workshop held in the rural areas of Kenya, East Africa, early spring 2013. It was concluded that close links between livelihoods, natural capital and poverty remains a fundamental challenge in East Africa’s forest conservation efforts.

The genus Aerotegmina (Orthoptera, Tettigoniidae, Hexacentrinae): chromosomes, morphological relations, phylogeographical patterns and description of a new species

The genus Aerotegmina Hemp is common on East African mountains. Two species are known and a third, A. taitensis n. sp., is described in this paper. A. kilimandjarica Hemp is widespread while A. shengenae Hemp is endemic to the South Pare Mountains and A. taitensis n. sp. is known only from the Taita Hills. Morphologically, and from their song, A. shengenae and A. taitensis n. sp. are closely related. In chromosome number A. kilimandjarica (2n = 33) differs clearly from A. shengenae (2n = 27). Data presented on other flightless Orthoptera suggest that the South Pare Mountains and the Taita Hills, both belonging to the geologically old mountain chain of the Eastern Arc, show a faunistic similarity not shared by any other mountain range in the area. The mechanisms that led to this phylogeographic pattern in flightless Orthoptera in the Eastern Arc Mountains of northern Tanzania and southern Kenya and the inland volcanoes are discussed. A key to the three Aerotegmina species is presented, as well as bioacoustical data of all species compared to the phaneropterine species Euryastes jagoi.

The role of temperature on treeline migration for an eastern African mountain during the Last Glacial Maximum

Paleo-data suggest that East African mountain treelines underwent an altitudinal shift during the Last Glacial Maximum (LGM). Understanding the ecological and physiological processes underlying treeline response to such past climate change will help to improve forecasts of treeline change under future global warming. In spite of significant improvements in paleoclimatic reconstruction, the climatic conditions explaining this migration are still debated and important factors such as atmospheric CO2 concentration, the impact of lapse rate decreasing temperature along altitudinal gradients and rainfall modifications due to elevation have often been neglected or simplified. Here, we assess the effects of these different factors and estimate the influence of the most dominant factors controlling changes in past treeline position using a multi-proxy approach based on simulations from BIOME4, a coupled biogeography and biogeochemistry model, modified to account for the effect of elevation on vegetation, compared with pollen, and isotopic data. The results indicate a shift in mountain vegetation at the LGM was controlled by low pCO2 and low temperatures promoting species morphologically and physiologically better adapted to LGM conditions than many trees composing the forest belt limit. Our estimate that the LGM climate was cooler than today’s by −4.5 °C (range: −4.3 to −4.6 °C) at the upper limit of the treeline, whereas at 831 m it was cooler by −1.4 °C (range: −2.6 to −0.6 °C), suggests that a possible lapse rate modification strongly constrained the upper limit of treeline, which may limit its potential extension under future global warming.

The historical biogeography of Scabiosa (Dipsacaceae): implications for Old World plant disjunctions

AbstractAim To reconstruct the temporal and biogeographical history of Old World disjunctions in Scabiosa (Dipsacaceae) and the timing of diversification in the Mediterranean Basin, in order to evaluate the importance of biogeographical and climatological history (particularly the onset of a mediterranean climate) in shaping Scabiosa distributions.Location Europe and the Mediterranean Basin, southern Africa and eastern Asia.Methods This study uses maximum‐likelihood and Bayesian phylogenetic analyses of chloroplast DNA (atpB–rbcL, trnL–trnF, trnS–trnG, psbA–trnH) and nuclear ribosomal DNA [internal transcribed spacer (ITS) and external transcribed spacer (ETS)] from 24 out of c. 37 ingroup taxa, beast molecular dating, and the dispersal–extinction–cladogenesis method (Lagrange) to reconstruct ancestral geographical ranges and the timing of diversification of the major clades of Scabiosa.Results Biogeographical and divergence time reconstructions showed that Scabiosa originated during the Miocene and diversified in Europe, followed by independent movements into Asia and Africa. Several of the major clades were inferred to have radiated sometime between the late Miocene and early Pleistocene, a timeframe that encompasses the onset of the mediterranean climate in Europe. More recent middle–late Pleistocene radiations in the Mediterranean Basin and southern Africa have played a large role in Scabiosa diversification.Main conclusions Members of Scabiosa appear to have capitalized on adaptations to montane and/or dry conditions in order to colonize similar habitats in different biogeographical regions. The formation of the East African Rift mountains is potentially of great importance in explaining the southward migration of Scabiosa. The initial diversification of Scabiosa in Europe during the Miocene is not consistent with the initiation of the mediterranean climate, but may instead be associated with increased aridity and the retreat of subtropical lineages during this time. However, the radiation of some of the major subclades within Scabiosa may have been associated with an emerging mediterranean climate. More recent and rapid radiations in both the Mediterranean Basin and southern Africa highlight the probable importance of Pleistocene climate fluctuations in Scabiosa diversification.

De la terre patrimoine à la terre ressource : tensions entre structures foncières héritées et nouvelles perspectives des acteurs paysans en Afrique de l'Est. (From heritage land to resource land : tensions between inherited land structures and new perspectives of peasant stakeholders in Eastern Africa)

There are strong links between the external and internal dimensions of the land issue which, moreover, deals with many stakes : social, identity, political, economic and environmental. Interactions of scale, of time or space, add further to this complexity, giving rise to heterogeneous situations which are sources of conflicts. In East Africa, the agricultural modernization has been imposed on local systems following a process of territorial construction which has gradually developed into a rigid and heterogeneous framework ; the land tenure blockage gave it sometimes a dramatic dimension. Under this process redefining the territories of production and the local identities, rural-based societies are suffering from historical rigidities and are handicapped by the extreme fragmentation and compartmentalization of production units. The attempts made by the producers to be involved in promising markets or in often uncertain agricultural chains redefine a composite and unequal "area of resources", where access to land, to water, to credit, to infrastructures and to information networks is a new comparative advantage. The objective of this paper is to explore some new ideas from specific studies which has been carried out on East African mountains, on the assumption that the diversity and the heterogeneity of the new socio-economical and territorial logics are the sign of the search of a new horizon of expectation, which could better articulate the moral economy of local societies with a project which could offer access to a larger citizenship

A multi‐locus phylogeny of Euryops (Asteraceae, Senecioneae) augments support for the "Cape to Cairo" hypothesis of floral migrations in Africa

AbstractWith about 100 species, Euryops (Cass.) Cass. ranks among the most speciose genera of the tribe Senecioneae (Asteraceae). The genus has its greatest diversity in South Africa, and displays an interesting disjunct distribution with most of the taxa found in southern Africa and a group of eight endemic species confined to the mountains of tropical East Africa and northeastern Africa. Molecular phylogenetic analyses of DNA sequence data from three chloroplast fragments and the nuclear ITS region were used to reconstruct the evolutionary history of 41 Euryops species in order to unravel species relationships and to determine the origin of the disjunct Afromontane taxa. Our results show a lack of support and resolution in the internal structure of the trees, but also reveal strong incongruence between the ITS and cpDNA datasets as assessed by Bayes Factors. We hypothesise that this is a consequence of the isolation and divergence of many populations over a short time period at some point in the history of the genus. Molecular dating based on our phylogenetic tree suggests that the genus diversified in South Africa around four million years ago. The origin of the East African species, dated at 1.9 Ma, well after the uplift of the East African mountains, is consistent with a scenario of a single dispersal event from South Africa northwards into the tropical East African mountains where diversification occurred, creating a monophyletic group of regional Afromontane endemics.

The global distribution of frugivory in birds

ABSTRACTAim To examine patterns of avian frugivory across clades, geography and environments.Location Global, including all six major biogeographical realms (Afrotropics, Australasia, Indo‐Malaya, Nearctic, Neotropics and Palaearctic).Methods First, we examine the taxonomic distribution of avian frugivory within orders and families. Second we evaluate, with traditional and spatial regression approaches, the geographical patterns of frugivore species richness and proportion. Third, we test the potential of contemporary climate (water–energy, productivity, seasonality), habitat heterogeneity (topography, habitat diversity) and biogeographical history (captured by realm membership) to explain geographical patterns of avian frugivory.Results Most frugivorous birds (50%) are found within the perching birds (Passeriformes), but the woodpeckers and allies (Piciformes), parrots (Psittaciformes) and pigeons (Columbiformes) also contain a significant number of frugivorous species (9–15%). Frugivore richness is highest in the Neotropics, but peaks in overall bird diversity in the Himalayan foothills, the East African mountains and in some areas of Brazil and Bolivia are not reflected by frugivores. Current climate explains more variance in species richness and proportion of frugivores than of non‐frugivores whereas it is the opposite for habitat heterogeneity. Actual evapotranspiration (AET) emerges as the best single climatic predictor variable of avian frugivory. Significant differences in frugivore richness and proportion between select biogeographical regions remain after differences in environment (i.e. AET) are accounted for.Main conclusions We present evidence that both environmental and historical constraints influence global patterns of avian frugivory. Whereas water–energy dynamics possibly constrain frugivore distribution via indirect effects on food plants, regional differences in avian frugivory most likely reflect historical contingencies related to the evolutionary history of fleshy fruited plant taxa, niche conservatism and past climate change. Overall our results support an important role of co‐diversification and environmental constraints on regional assembly over macroevolutionary time‐scales.

Climatic change as an engine for speciation in flightless Orthoptera species inhabiting African mountains

Many East African mountains are characterized by an exceptionally high biodiversity. Here we assess the hypothesis that climatic fluctuations during the Plio-Pleistocene led to ecological fragmentation with subsequent genetic isolation and speciation in forest habitats in East Africa. Hypotheses on speciation in savannah lineages are also investigated. To do this, mitochondrial DNA sequences from a group of bush crickets consisting of both forest and savannah inhabiting taxa were analysed in relation to Plio-Pleistocene range fragmentations indicated by palaeoclimatic studies. Coalescent modelling and mismatch distributions were used to distinguish between alternative biogeographical scenarios. The results indicate two radiations: the earliest one overlaps in time with the global spread of C4 grasslands and only grassland inhabiting lineages originated in this radiation. Climatically induced retraction of forest to higher altitudes about 0.8 million years ago, promoting vicariant speciation in species inhabiting the montane zone, can explain the second radiation. Although much of the biodiversity in East Africa is presently threatened by climate change, past climatic fluctuations appear to have contributed to the species richness observed in the East African hot spots. Perceiving forests as centres of speciation reinforces the importance of conserving the remaining forest patches in the region.

Magnitude of soil erosion on the northern slope of the Uluguru Mountains, Tanzania: Interrill and rill erosion

Abstract The magnitude of interrill and rill erosion was determined on the northern slopes of the Uluguru Mountains, Tanzania which is representative for larger areas of East African Arch Mountains, where population pressure is high and land degradation is severe. The aim of the study was to develop a database to support soil conservation in the area. The study was done on two distinct geomorphic units with respect to altitude and hence rainfall distribution pattern: mountain ridges with an altitude ranging from 1000 to 1500 masl and mean annual rainfall of 2300 mm and mountain foothills whose altitude and mean annual rainfall are 550 to 900 masl and 900 mm, respectively. Total soil loss was measured on 36 individual bounded plots measuring 1.2 m × 20 m using Gerlarch troughs on each day with rain from July 2000 to June 2001. The plots were located on six different geopedologic units, nine on mountain ridges and the rest on the mountain foothills. The slope gradient on the terrain ranged from 30% to 70%. The plots were put under maize cultivation as the main crop. Soil loss through rill erosion was estimated by volumetric measurements of rills on each soil erosion plot. The soil loss due to interrill erosion was obtained by subtracting soil loss through rill erosion from the total soil loss measured in the Gerlarch troughs. The results indicate that soil loss due to both interrill and rill erosion was very high with mean soil loss of 69 and 163 t/ha/year, respectively. Rill erosion accounted for about 58% of the total soil loss while interrill erosion contributed to the remaining 42%. Both interrill and rill erosion were higher in the mountain ridges with mean soil loss of 88 t/ha/year and 210 t/ha/year compared to 49 and 116 t/ha/year in the mountain foothills, respectively. Rill erosion was significantly higher ( P ≤ 0.001) in all geopedologic units with slope gradient above 40% (mean soil loss ranged between 91 and 258 t/ha/year) compared to interrill erosion with mean soil loss varying from 41 to 115 t/ha/year. In geopedologic units with slope gradient above 60% both interrill and rill erosion were highly active while in geopedologic units with slope gradient below 40% the two processes were less active. The results demonstrate that rill erosion is more important than interrill erosion in the study area particularly where the slope gradient exceeds 40%. The results further show that the major part of the studied area has moderate interrill erosion (10–50 t/ha/year) and severe to very severe (> 100 t/ha/year) rill erosion. This study clarifies the magnitude of interrill and rill erosion which is important for designing soil conservation on agricultural fields.

New Combinations in Lychnis (Caryophyllaceae) from Africa

New combinations in Lychnis L. (Caryophyllaceae) are proposed for the names of seven taxa occurring in the East and West African mountains. The taxa have previously been placed in Uebelinia Hochstetter, but recent molecular studies placed the group within Lychnis. The new combinations are: L. crassifolia (T. C. E. Fries) M. Popp, L. kigesiensis (R. D. Good) M. Popp, L. kigesiensis subsp. ragazziana (S. Ousted) M. Popp, L. kiwuensis (T. C. E. Fries) M. Popp, L. kiwuensis subsp. erlangeriana (S. Ousted) M. Popp, L. rotundifolia (Oliver) M. Popp, and L. scottii (Turrill) M. Popp.

Phytolith indices as proxies of grass subfamilies on East African tropical mountains

The main objective of this paper is to provide researchers that investigate fossil phytolith assemblages and model/data comparisons a new tool for estimating C 3/C 4 grass composition over time. We tested the reliability of modern soil phytolith assemblages and phytolith indices for tracing the dominance of different grass subfamilies and tree cover density. We analyzed modern soil phytolith assemblages from sites over elevation gradients on Mount Kenya (Kenya), Mount Rungwe and around Lake Masoko (southern Tanzania). These data were compared with available botanical data. A phytolith index named Ic, proved to be an effective proxy of the proportions of Pooideae, Arundinoideae and Bambusoideae grasses (mainly C 3 grasses) versus Panicoideae grasses (mainly C 4 grasses), increasing with elevation in East-Africa. When tropical mountains are covered by open habitats (e.g . grasses and shrublands), Ic should be a reliable proxy of the C 3/C 4 grass composition. These results highlight the value of the phytolith index Ic, when interpreting paleo-environmental records from tropical mountains, to: 1) better understand past local and regional C 3/C 4 grass distributions and associated climatic changes and 2) increase the set of C 3/C 4 data available for model/data comparisons.

Genetic consequences of Pleistocene range shifts: contrast between the Arctic, the Alps and the East African mountains

In wide-ranging species, the genetic consequences of range shifts in response to climate change during the Pleistocene can be predicted to differ among different parts of the distribution area. We used amplified fragment length polymorphism data to compare the genetic structure of Arabis alpina, a widespread arctic-alpine and afro-alpine plant, in three distinct parts of its range: the North Atlantic region, which was recolonized after the last ice age, the European Alps, where range shifts were probably primarily altitudinal, and the high mountains of East Africa, where the contemporary mountain top populations result from range contraction. Genetic structure was inferred using clustering analyses and estimates of genetic diversity within and between populations. There was virtually no diversity in the vast North Atlantic region, which was probably recolonized from a single refugial population, possibly located between the Alps and the northern ice sheets. In the European mountains, genetic diversity was high and distinct genetic groups had a patchy and sometimes disjunct distribution. In the African mountains, genetic diversity was high, clearly structured and partially in accordance with a previous chloroplast phylogeography. The fragmented structure in the European and African mountains indicated that A. alpina disperses little among established populations. Occasional long-distance dispersal events were, however, suggested in all regions. The lack of genetic diversity in the north may be explained by leading-edge colonization by this pioneer plant in glacier forelands, closely following the retracting glaciers. Overall, the genetic structure observed corresponded to the expectations based on the environmental history of the different regions.

BUILD-UP OF THE HIMALAYAN AVIFAUNA THROUGH IMMIGRATION: A BIOGEOGRAPHICAL ANALYSIS OF THEPHYLLOSCOPUSANDSEICERCUSWARBLERS

The Himalayan mountain range is one of the most species-rich areas in the world, harboring about 8% of the world's bird species. In this study, we compare the relative importance of immigration versus in situ speciation to the build-up of the Himalayan avifauna, by evaluating the biogeographic history of the Phylloscopus/Seicercus warblers, a speciose clade that is well represented in Himalayan forests. We use a comprehensive, multigene phylogeny in conjunction with dispersal-vicariance analysis to discern patterns of speciation and dispersal within this clade. The results indicate that virtually no speciation has occurred within the Himalayas. Instead, several speciation events are attributed to dispersal into the Himalayas followed by vicariance between the Himalayas and China/Southeast Asia. Most, perhaps all, of these events appear to be pre-Pleistocene. The apparent lack of speciation within the Himalayas stands in contrast to the mountain-driven Pleistocene speciation suggested for the Andes and the East African mountains.

Phylogeography and conservation genetics of a giant lobelia (Lobelia giberroa) in Ethiopian and Tropical East African mountains

Lobelia giberroa is a giant rosette plant growing in the afro-montane belt of the afro-alpine environment, a unique and little-studied ecosystem occupying the high mountains of eastern Africa. We analysed amplified fragment length polymorphisms (AFLPs) from 11 mountain systems in Ethiopia and Tropical East Africa to infer the phylogeographical history of the species. A total of 191 individuals were investigated from 25 populations. Principal coordinate analysis and population structure analyses revealed three major phylogeographical groups: the Ethiopian mountains and one group on each side of the Rift Valley in Tropical East Africa, respectively: Elgon-Cherangani and Kenya-Aberdare-Kilimanjaro-Meru. Analysis of Molecular Variance showed 55.7% variance among the three groups, suggesting an old divergence. Together with a clear geographical substructure within the main groups, this pattern indicates gradual expansion and supports the montane forest bridge hypothesis, stating that the area occupied by forest was larger and more continuous in previous interglacials and earlier in the present interglacial. Genetic diversity was lower in Ethiopia than in the other two main groups, possibly due to an ancient founder effect when Ethiopia was colonized from the south.

SYSTEMATICS OF THE AFRO-MACARONESIAN SPIDER GENUS SANCUS (ARANEAE, TETRAGNATHIDAE)

Abstract We review the systematics of the tetragnathid spider genus Sancus Tullgren, hitherto known from a single species from Kilimanjaro. The type species Sancus bilineatus Tullgren is redescribed and diagnosed from the only other known species, S. acoreensis (Wunderlich) new combination. Leucognatha Wunderlich is a junior synonym of Sancus, which thus eliminates two monotypic tetragnathid genera. A phylogenetic analysis of 15 tetragnathid and eight outgroup genera confirms the monophyly of Sancus and places it precisely in Tetragnathidae. We discuss the phylogenetic relationships among tetragnathid genera and the peculiar biogeography of Sancus, now known from east African mountains (Kilimanjaro and Mt. Kenya) and from the Azores in the northeastern Atlantic.

Three times out of Asia Minor: the phylogeography of Arabis alpina L. (Brassicaceae)

Arabis alpina is a characteristic plant in arctic-alpine habitats and serves as a classical example to demonstrate biology, ecology and biogeography of arctic-alpine disjuncts. It has a wider distribution than most other arctic-alpine plants, covering all European mountain systems, the Canary Islands, North Africa, the high mountains of East Africa and Ethiopia, the Arabian Peninsula and mountain ranges of Central Asia in Iran and Iraq. Additionally it is found in the northern amphi-Atlantic area including northeastern North America, Greenland, Iceland, Svalbard and northwestern Europe. We used markers from the nuclear (internal transcribed spacer of ribosomal DNA) and chloroplast genome (trnL-F region) to reconstruct its phylogeographic history. Both markers revealed clear phylogeographic structure. We suggest that A. alpina originated in Asia Minor less than 2 million years ago based on synonymous mutation rates of different genes (plastidic matK, nuclear adh and chs). From the Asian ancestral stock one group migrated via the Arabian Peninsula to the East African high mountains. A second group gave rise to all European and northern populations, and also served as source for the northwest African populations. A third group, which is still centred in Asia, migrated independently southwards and came into secondary contact with the East African lineage in Ethiopia, resulting in high genetic diversity in this area. In the Mediterranean regions, the genetic diversity was relatively high with numerous unique haplotypes, but almost without geographic structure. In contrast, the populations in the northern amphi-Atlantic area were extremely depauperate, suggesting very recent (postglacial) expansion into this vast area from the south.

Review of the Hylomyscus denniae complex (Rodentia: Muridae) in Tanzania, with a description of a new species

ABSTRACT Based on morphological and morphometric comparisons, a new species of Hylomyscus, H. arcimontensis (Muridae: Murinae), is identified from Mount Rungwe and the Eastern Arc Mountains of central and eastern Tanzania. The new species is confined to wet montane forests of these mountains and represents another vertebrate endemic to the Tanganyika-Nyasa Montane Forest biotic region (sensu Moreau 1966). It is most closely related to H. anselli, a form described from mountains in northern Zambia as a subspecies of H. denniae and here elevated to species rank. Morphological evidence supports the view that the nominal species H. denniae is a composite of several species whose interrelationships and differentiation patterns indicate two species complexes: the H. denniae group centered in Central East African mountains (Burundi, Kenya, Rwanda, Uganda, Zaire) and the H. anselli group distributed across more southern mountains (Angola, Malawi, Tanzania, Zambia).

Bird–flower interactions in the Macaronesian islands

AbstractAims Several bird‐pollinated or ornithophilous flowers are present on the Macaronesian archipelagos, the Canary Islands and Madeira, but absent from nearby NW Africa and Europe. In Macaronesia, no specialist nectar‐feeding birds are found, but several generalist passerine bird species visit flowers for nectar. Two hypotheses attempt to explain the origin and evolution of ornithophily in the Macaronesian flora. According to ‘the island de novo hypothesis’, bird‐flowers evolved from mainland insect‐pollinated ancestors after island colonization. Alternatively, ancestors of the ornithophilous Macaronesian plant species evolved bird‐flowers before reaching the islands (‘the relict hypothesis’). In this study we first compile information of Macaronesian bird–flower interactions from the literature and our own field observations. Secondly, we discuss the two hypotheses of origin of ornithophily in the light of evidence from recent molecular plant phylogenies, palaeontology, historical biogeography of the African avifauna and flora, and present‐day ecological patterns.Location Madeira and Canary Islands.Results At least eleven endemic Macaronesian plant species from six genera have typical ornithophilous floral traits. These genera are: Canarina and Musschia (Campanulaceae), Isoplexis (Scrophulariaceae), Echium (Boraginaceae), Lotus (Fabaceae) and Lavatera (Malvaceae). These lineages have clear affinities to the Mediterranean region, except for Canarina whose closest relatives grow in East African mountains. Six generalist passerine bird species of Sylvia, Phylloscopus (Sylviidae), Serinus (Fringillidae) and Parus (Paridae) visit this flora for nectar.Main conclusion We suggest that the origin and evolution of ornithophilous traits in these plant species took place mostly in mainland areas prior to island colonization. In Canarina and Lavatera, it is well supported that ornithophily is a relict condition, which originated in mainland areas possibly in association with specialist nectar‐feeding birds. For the remaining plant species except Echium wildpretii bird floral traits probably also are a relict condition. These species may be derived from ancestors, which were visited by specialist nectar‐feeding birds during geological periods when the Mediterranean and the Ethiopian vegetation were intermingled in mainland Africa. Probably, these mainland ancestors went extinct due to severe climatic fluctuations, while their Macaronesian descendants survived in ‘refuge’ on the islands. Finally, the island de novo hypothesis may explain the evolution of a mixed bird/insect‐pollination system in the neo‐endemic red‐flowered Echium wildpretii.

Fire‐induced reproduction ofFestuca pilgeriin the subalpine zone of Mount Kenya

Plant species in fire-dominated habitats are characterizedby a variety of evolutionary adaptations to fire (reviewed inGill, 1981; Bond & van Wilgen, 1996). These include thickbark, the ability to coppice, and protected meristems, suchas those in tussock grasses. The reproductive opportunitiescreated by fire favour adaptations such as fire-inducedreproduction (Gill & Ingwersen, 1976; Le Maitre & Brown,1992; Verboom, Stock & Linder, 2002) and dormancy thatis broken by smoke (Keely, 1993) or intense heat.Fire appears to be common in the sub-alpine shrublandsand grasslands of the tropics (Hedberg, 1964; Beck,Scheibe & Schulze, 1986; Laegaard, 1992; Young, 1996).On East African mountains, as elsewhere in the tropics, thesub-alpine zone is characterized by ericaceous vegetationfloristically and physiognomically similar to fire-pronechaparral biomes (Young, 1991, 1996; Safford, 2001).The woody species there readily coppice after fire(T. Young, pers. obs.; Hemp & Beck, 2001). The ericaceouszone of Mount Kenya burned several times between 1970and 1990 at different sites (Young, 1996; Phil Snyder, BillWoodley & Bongo Woodley, pers. comm.). Each of thesefires covered several hundred hectares. As yet we haveno data on return intervals but many of these fires aresuspected to be human-caused by honey hunters (PhilSnyder & Bill Woodley, pers. comm.).Festuca pilgeri St-Yves is the dominant grass in the alpinezone of Mount Kenya, forming nearly monospecific standsin some areas (Hedberg, 1964, Young & Peacock 1992). Itforms dense tussocks up to 50 cm in diameter. It occurs inboth reproductive and mostly sterile populations on MountKenya, with the latter predominating at lower elevationsin the subalpine zone (Young & Peacock, 1992).

Mountains in East Africa: the missing Commonwealth dimension

Mountains play a vital ro˘le in the global ecosystem and economy. They are a source of most of the world's fresh water and many mountain regions possess key sites of biodiversity, while forested areas are both economically and ecologically important. While international agencies variously highlight mountain issues, there is virtually no direct involvement of Commonwealth-based activities, despite the fact that the Commonwealth contains some of the world's most significant mountain areas. In the wake of the 2002 International Year of the Mountains, the author draws on 15 years of studies of the East African Mountains to examine the successes and failures of government policies and international interventions.