University of the Witwatersrand Animal, Plant and Environmental Sciences Fire Regimes in Southern Africa-

ii The spatial and temporal patterns of fire in Africa south of the equator are described and investigated to test hypotheses on the main drivers of fire. In particular, the relative importance of climate, vegetation, and human activities are assessed and related to current theory on savanna fire regimes and their response to global change. This thesis makes use of newly-released burned area and fire radiative power data derived from satellite imagery. This information was integrated with data on climate, vegetation, and human activities, as well as long-term field data on fire, to test hypothe-ses about savanna fire regimes. Regression tree techniques and mixed effects models were used to determine the main drivers of spatial and temporal variability in fire, and feedbacks between fire and tree cover were explored at a range of spatial scales. New datasets on fire size and fire number were also developed to test theories on the effect of human activities on ignition probability and fire spread. The results show that fire in these grassy ecosystems is very responsive to climati