The hydrological legacy of deforestation on global wetlands

Abstract

Catchment erosion and increased nutrient loading are commonly recognised impacts of deforestation on global wetlands. Forest clearance can increase water availability in wetland catchments, but globally, the hydrological effect of deforestation has received little attention. We provide the first unequivocal evidence that historic and prehistoric forest clearance in dryland areas in Australasia increased catchment water yield; creating new wetlands and converting existing wetlands into shallow lakes. We developed a hydrological model to predict the location of global wetland catchments that are susceptible to this effect and demonstrate that hydrological alteration of wetland catchments is a previously overlooked dimension of the cultural landscape. We used a meta-analysis of published papers to demonstrate that the effect is widespread but under-appreciated in the literature. We conclude that artificially enhanced wetlands may be common even in regions with short histories of human settlement. Restoring them to their pre-human impact state may be difficult or even undesirable if we want to protect biodiversity and wetland ecosystem services.