More people, more trees in South Eastern Tanzania: local and global drivers of land-use/cover changes

摘要

Land degradation in South Eastern Tanzania, the country's major cashew producing area, has been attributed to deforestation. By comparing land-use/cover maps derived from aerial photographs of 1965 with maps derived from satellite images of 2002, we assessed how land-use changed in six villages, and relate these to local and global drivers. Land-use/cover changes are complex processes, which we analyzed by determining the relative net changes, losses, persistence and gains of each land-use/cover categories. Widespread planting of cashew trees only started in the 1960s; while the 'villagisation' program in the 1970s, altered settlement patterns as centrally planned villages were created. Population growth and rural development policies were major local drivers for land-use/cover change; international trade and technological innovations were principal global drivers. Though population increase led to a reduction of natural vegetation, the spread of cashew trees resulted in a case of 'more people, more trees.' How far the ensuing deforestation affected the biodiversity of the area and how sustainable the production of cashew nuts actually is, remains yet unresolved questions.