Using GIS and remote sensing to explore the influence of physical environmental factors and historical land use on bushland structure

Bushland is a vegetation type with a dense cover of woody plants of low stature and a grass understory. We explored the influence of environmental factors (precipitation, topography, geology, hydrology and waterhole density) and historical land use in the Tsavo ecosystem bushland. We mapped vegetation patterns in the region using remote sensing, GIS and field data and tested relationships with physical factors. We used regression analysis to explore the interaction of physical factors and human influence by including a protected and a nonprotected area, representing contrasting historical land use policies, as factors in the regression model. Bushland vegetation had the largest proportion in the region as a whole, but its proportion was notably greater in the nonprotected area. Precipitation, elevation, geology and historical land use were significant predictors of vegetation patterns in the regression models. Higher precipitation and elevation make woody plants superior competitors over grasses, resulting in predominance of bushland in such areas. Geologically, marine deposits result in shallow calcareous soils that favour grasses over trees, hence, absence of bushland. Wildlife management policies such as providing water for wildlife, protective boundaries and controlling wildfires influence distribution of wildlife and result in conditions that prevent regeneration and recruitment of trees.