Remote Sensing of Global Savanna Fire Occurrence, Extent, and Properties
Fire is a major determinant of the ecology and distribution of the world’s savanna and grassland systems (Higgins et al., 2000; Bond et al., 2005). A prolonged annual dry season combined with relatively rapid rates of fuel accumulation create conditions conducive to frequent vegetation fires in the world’s savannas. For a fire to occur, fine dead fuels such as grasses, twigs, and leaves must be present, and their moisture content must be low enough to sustain combustion. In addition, there must be a source of ignition. Humans have been using fire for the past 790,000 years, with remains in Kenya suggesting human exploitation of fire may be ancient (Alperson-Afil, 2008). Today, except in sparsely populated regions where late dry season and early wet season lightning fires predominate, most savanna fires are lit by people for numerous reasons including clearing land for cultivation, to provide nutrient rich ash for crops, to maintain and improve pasture and grasslands for livestock grazing and to attract game, to drive animals during hunting, to make fire breaks around fields and settlements, and due to accident or arson (Frost, 1999; Gill et al., 2009; Miranda et al., 2009).