Effects of past and present land use on vegetation cover and regeneration in a tropical dryland forest

Abstract

Brazilian Caatinga is one of the most diverse dryland ecosystem of the world and is threatened by strong land use pressure and poor protection. In this study, we investigate the effects of past and present land use on plant community richness and structure. We used satellite information to identify 55 Caatinga forest plots with and without past vegetation clearing. We also quantified current land use, i.e. grazing by domestic animals, and selective logging. Caatinga vegetation structure, measured as vegetation cover, vegetation height, basal area and woody plant density, as well as recruitment, measured as woody plant seedling density and species richness, were negatively affected by both past and current land use. Past clear-cut not only had strong effects on most vegetation measures, but also increased current grazing which further negatively affected vegetation structure. Selective logging had little measurable effects but increased recruitment in plots previously clear-cut. Increasing time since the last clear-cut increased negative effects on vegetation, presumably because of a prolonged negative effect of grazing. Our results suggest that grazing needs to be prevented in areas degraded by clear-cut to allow vegetation restoration through natural succession and avoid further degradation and desertification.