Eastern Arc Mountains and Coastal Forests of Tanzania and Kenya ...

T H E A R C J O U R N A L I S S U E 1 6New conservation investment into the Eastern ArcMountains and Eastern African Coastal Forestsbiodiversity “Hotspot”Neil Burgess, WWF-USA Conservation Science Program, 1250 24th Street NW, Washington DC, USAThe term biodiversity ‘Hotspot’ was first applied in 1988when an English Professor (Norman Myers) wrote apaper that identified regions in the world where at least0.5% of all the worlds plants are concentrated,including the Tanzanian Eastern Arc Mountains. The‘Hotspots’ idea captured the interest of manyconservationists - if they could identify those areaswhere endemic species were concentrated and thenundertake effective work in the same areas - then muchof the biodiversity of the world could be saved atrealistic expense and within relatively small amounts ofthe worlds land.The ‘Hotspots’ concept was further refined between1996 and 1998 when the USA-based conservationNGO ‘Conservation International’ completed ac o m p rehensive global re-analysis of global plantBiodiversity Hotspots. In order to qualify eachproposed area had to have at least 1,500 plants whollyendemic to it (approximately 0.5% of the worlds totalknown species of plants), and at least 75% of theoriginal habitat needed to have been destro y e d .Through this process, twenty-five plant hotspots wereidentified around the world. Together these contain133,399 endemic plant species (44% of the knownworld total) and 9,681 endemic animals (35% of thetotal known). These Hotspots cover an area of 2.1million km2, or about 1.4 % of the land area of theglobe.Five of the 25 hotspots are found on mainland Africaand one covers Madagascar and nearby islands. InTanzania there is a single plant Hotspot, which is partlyshared with Kenya – the Eastern Arc and easternAfrican Coastal Forests Hotspot (Figure 1). Over thepast year efforts have been made to identify prioritiesfor conservation investment into this Hotspot and $7million has now been made available for conservationin the area by the Critical Ecosystem Partnership Fund(CEPF), which is a collaboration between ConservationI n t e rnational, the World Bank, the MacArt h u rFoundation, the Global Environment Facility and theJapanese Government (see cepf.net). During therecent CEPF assessment, updated information wascompiled on a number of diff e rent measures ofbiodiversity value in the Hotspot, especially habitatarea, and the distribution of endemic and globallythreatened species.Habitats. The hotspot is estimated to have originallysupported around 23,000 km 2 of forest, of which around15,000 km 2 was left in 1900, and a maximum of 5,340km 2 remained by the mid 1990s. These forestedhabitats were embedded within much larger areas ofhigh altitude grasslands and low altitude savannawoodlands and bushlands. Forest area has declinedprimarily due to clearance for agricultural use, but alsodue to logging, clearance to make charcoal and due to13the spread of wildfires. Most remaining forest patchesare found in areas protected by the Government,principally as Forest Reserves. There is no accuratedata on the current status of the habitats of the Hotspot,but information from all sources indicates a continuedand sometimes serious decline, especially of forest andmontane grassland habitats.Endemic species. Current data show that the hotspotis home to at least 1,400 endemic plant species, 16endemic mammals, 22 endemic birds, 50 endemicreptiles and 33 endemic amphibians (Table 1). Theextremely dense packing of endemics in the small areaof remaining habitat of this Hotspot makes many of theplants and animals in this hotspot threatened withglobal extinction. The level of extinction risk is used asa core part of the CEPF process to identify conservationpriorities in the Hotspot.Globally threatened species. All species listed asglobally threatened by IUCN that are found in theEastern Arc Mountains and Coastal Forests of Tanzaniaand Kenya have been identified and their distributionsmapped. The globally threatened fauna (based onIUCN classifications) in the hotspot are represented by29 mammal species, 28 bird species, 33 amphibianspecies, and 7 gastropods. The globally threatenedflora contains 237 plant species, which is regarded asa great underestimate. In total, 334 globally threatenedspecies are found, with 110 species in Kenya and 310in Tanzania (see cepf.net). The degree of threat toreptiles, freshwater fish, and almost all groups ofinvertebrates has not been assessed and hence thesespecies could not be used in this exercise.Sites. The CEPF process used the number of globallyt h reatened species to identify critical sites forconservation investment. A number of sites in thisHotspot have very high numbers of threatened species.These include: East Usambara Mountains, UluguruMountains, Udzungwa Mountains, West UsambaraMountains, Shimba Hills, Lindi District Coastal Forests,Nguru Mountains, Taita Hills, South Pare Mountains,and Kisarawe District Coastal Forests. These are thekey areas for conservation efforts seeking to preventextinction within the hotspot.Landscapes and corridors. The Eastern Arc mountainblocks are naturally isolated due to their topographyand cooler and moister climates. They are surroundedby a ‘sea’ of hot and dry savanna that prevents themovement of species between different blocks. In thelowland coastal forests, it might appear that forestcover could have been almost continuous in the distantpast (and therefore cover a vast area). However thedistribution patterns of species in these forests indicateparts of this forest have also been isolated for a longtime. These ancient patterns of forest isolation have