East Usambaras

The East Usambaras are situated within 100 km of the Indian Ocean and consist of a steep escarpment rising from less than 300 m to an altitude of 900-1050 m, where there is a deeply dissected plateau. Up to 2000 mm of rain a year fall during two distinct rainy seasons (March-May and October-December).

The escarpments and the plateau were formerly covered with forest of which less than half persist to-day. Some stands of undisturbed forest remain containing trees as tall as 65 m and a number of endemic species. A permanent forest plot has been established in a portion of forest that was lightly harvested by pit-sawyers in the 1970s. Much of the forest has been cleared for commercial crops (e.g. tea), forestry plantations (Maesopsis eminii in the uplands and Tectona grandis in the lowlands) and agriculture. Since the 1960s the pace of deforestation has markedly increased mainly as a result of increased human pressure.

During the first decade of the century the German colonial power established a major research station at Amani which included a substantial botanic garden (over 300 ha and nearly 1000 exotic species were introduced). Amani has remained, throughout this century, a major centre for research. Since 1997 the botanic garden is part of the Amani Nature Reserve.

Until the early 1990s much of the forest reserves were logged. Although the Forest Reserves and the Nature Reserve are now free from logging, their integrity is seriously threatened by the spread of invasive plants. Many of these introduced species having been introduced to the botanic garden chiefly prior to World War I.