Regional fire occurrence in Southern Africa using BFAST iterative break detection in seasonal and trend components of a MODIS time series

Fire is an integral part of southern African savannas, but despite being well-studied, complex relationships among fire, humans, climate and ecological systems remain poorly understood across much of the region. Analyses that provide information on fire trends in diverse regional contexts are essential for informing fire management and monitoring change. Harmonic seasonal patterns, linear time-series trends and breakpoints in fire occurrence (BFAST) were analysed for 2001-2018 in Botswana using remotely sensed fire occurrence measurements. Regional classification schemes were organized by human land-use, annual precipitation zones and vegetation communities. At the regional scale, mean annual precipitation, land-use and vegetation type influenced fire occurrence magnitude. Seasonality and variability were most clearly organized according to mean annual precipitation. Variability in seasonal and long-term fire trends were observed across the different classification schemes apart from mean annual precipitation zones above 600 mm. The methodology used effectively identified key differences in fire variability across regional classification schemes. However, the spatial resolution and classification scheme may be less effective for human land use and small fires. Overall, MODIS fire data analysed with BFAST is a promising and accessible method for analysing regional savanna fire regimes.