Habitat fragmentation, tree species diversity and land cover dynamics in a resettlement area in Chimanimani district of Zimbabwe : a spatio-temporal approach

Abstract

Agricultural expansion into forests leads to habitat fragmentation and the creation of habitat patches that can only support a limited amount of biodiversity. Adopting theoretical frameworks which seek to understand biodiversity variations in agricultural landscapes currently undergoing rapid land cover changes mainly due to agricultural expansion into forests is important for promoting biodiversity-agriculture coexistence. The main objective of this thesis was to test whether the area-diversity prediction of the island biogeography theory can successfully be used to explain differences in tree species diversity among different woodland patch sizes in Nyabamba resettlement area of south-eastern Zimbabwe. We also tested whether cropland expansion drives land cover change in resettled landscapes of Zimbabwe. The area-diversity prediction of the island biogeography theory was used to explore whether woodland patches of different sizes had significant differences in tree species diversity. We also used remotely sensed data in a GIS-Markov chain modelling framework to determine historic as well as future predictions of land cover dynamics in the study area. Our results show that larger woodland patches had significantly higher species diversity than smaller woodland patches, indicating that the island biogeography theory can be used to explain tree species diversity differences in agriculturally fragmented woodlands. Results of historic land cover modelling and futuristic spatial predictions showed increases in cropland and wooded grassland accompanied by decreases in plantation and woodland. We also found that soil types and distance from rivers significantly influence land cover conversions. Results of this thesis imply that habitat fragmentation has a significant effect on tree species diversity and that cropland expansion is a major driver of land cover conversions in newly resettled agricultural landscapes.