Preliminary assessment of the distribution, status and biological importance of coastal forests in Tanzania

Abstract

The lowland forests of coastal Tanzania comprise small and geographically isolated remnants of evergreen or semi-evergreen forest vegetation of the Zanzibar-Inhambane regional mosaic—undifferentiated forest type. Most of these ‘coastal forests’ are located at less than 600 m altitude and within 50 km of the coast. They have been isolated from other forest-blocks in Africa for perhaps the past 30 million years and have considerable biological importance, with high levels of endemism. This paper presents a preliminary assessment of the distribution, status and biological importance of those Tanzanian coastal forests over 2 km 2 in extent. Twenty-four definite and 17 probable forests are identified. The largest are located on the Matumbi Massif to the southeast of Utete ( c. 25 km 2), Zaraninge Plateau to the east of Sadaani ( c. 20 km 2), Gendagenda to the west of Pangani ( c. 26 km 2), Pugu Kazimzumbwi ( c. 30 km 2) and inland from Kilwa (up to 100 km 2). However, individual forests generally occupy less than 20 km 2, and the total area of forest remaining may be under 400 km 2. Collectively these forests support many rare and poorly known plant species, including around 50 believed to be endemic to a single forest, seven bird species and subspecies of global conservation significance, several rare mammals, reptiles and amphibians, and an invertebrate fauna with many rare and undescribed species. All Tanzanian coastal forests are being destroyed by unsustainable human actions generally following the sequence (a) logging for timber and fuel; (b) polecutting to build houses; (c) wholesale burning for charcoal; (d) wholesale conversion to agriculture. At the present rate of destruction the Tanzanian coastal forests and their globally important flora and fauna may be completely removed.