Dynamic land use and land cover changes and their effect on forest resources in a coastal village of Matemwe, Zanzibar, Tanzania

Recent land cover change estimates show overall decline of tropical forests at the regional and global scales caused by multiple social, cultural and economic factors. There is an overall concern on the prevailing land use practices, such as shifting cultivation and extraction of forest materials as agents of forests losses, but also new, emerging land uses are threatening tropical forests. Understanding of the long-term development and driving forces of forest changes are needed, especially at local levels where many decisions on forest policies and land uses are made. This paper addresses the importance of such information for improved estimates of forest dynamics by studying local level land cover and land use changes during the last 50–70 years in the Eastern African tropical island of Zanzibar, Tanzania. The paper discusses the role of traditional and new land uses mainly subsistence farming, tourism and government interference through tree planting, in the long-term development of the forests at the village level. The material for the study is gathered from the interpretation of archival maps and aerial photographs combined with contemporary digital aerial photographs. The analyses are based on the mapping, spatial sampling and spatio-temporal change trajectory analysis (LCTA) of forest land cover, forest land uses and settlement patterns with GIS and statistics. Six distinct forest land cover change trajectories were identified and these illustrate dynamic and heterogeneous nature of the forests. Closed forest cover has dominated throughout due to cyclical land use patterns, but over 70% of the land area has been continuously transforming between closed, semi-open and open land cover conditions. Land use turnover rates indicate that hardly any forest areas are left untouched from the forces, which remove and re-establish forest vegetation in the long run. Land cover and land use change trajectories are spatially fragmented in the studied landscape. Majority of forest loss-gain dynamics is caused by shifting cultivation, while forest losses are most dramatic along the coast, where traditional and new land uses meet and land uses pressures are highest. The study suggests that landscape change trajectory analyses, where contemporary and historical information on land uses and land cover changes are spatially linked, can provide valuable aspects into local level forest land use planning and management strategies. For the case study, the findings suggest