Responses of Invertebrates to Human-Caused Disturbances in East African Tropical Rainforests

Abstract

East African rain forest biotope is one of the most diverse habitat types on the planet (Lovett and Wasser 1993, Struhsaker 1997, Burgess et al. 1998, Mittermier et al. 1998, Myers et al. 2000, Newmark 2002). The Eastern Arc Mountains form a large part of rainforest habitats in East Africa. These mountains extend from southeast Kenya through south central Tanzania and are globally known for their high rates of endemism and species richness (Burgess et al. 1998, Newmark 2002). Locally, they support the livelihood of millions of people in the mountains and their surroundings. Despite its importance biological diversity in East African rainforests are currently being lost at an unprecedented rate due to various human-caused disturbances (Nsolomo and Chamshama 1990, Struhsaker 1997, MNRT 1998, Burgess et al. 1998, Poynton et al. 1998, Wood et al. 2000, Fimbel et al. 2001). Deforestation is the major threat to the sustainability of biodiversity in East Africa (Nsolomo and Chamshama 1990, Martens 1995, Lulandala 1998, Newmark 1998, Burgess et al. 1998). For instance, over 17600 km 2 or 77 % of the original forests in the Eastern Arc Mountains have been lost (Newmark 1998). Based upon species-area relationships (Whitmore 1997) a loss of 77 % of the original forest in the Eastern Arc Mountains suggests that approximately 31 % of species in the Eastern Arc Mountains have become extinct or are in danger of extinction (Newmark, 2002). However, according to Newmark (1998) the figure could be much higher, if factors like small size of the remaining forest patches, the restricted geographic distribution of many species and the reluctance of many taxa to cross forest gaps are considered. Deforestation has also reduced ecosystem diversity (Newmark 2002) and affected many ecological systems (Lundgren 1980).