CLIMATE CHANGE AND THE ROLE OF VEGETATION IN THE REDUCTION OF SOIL EROSION

Simulations of 21^st century climate change predict increased seasonal precipitation that may lead to widespread soil loss and reduced soil carbon stores by increasing surface runoff. Vegetation may counteract this increase through its response to climate change, possibly mitigating any impact on soil erosion. Here, we document for the first time the potential for vegetation to prevent widespread soil loss by surface-runoff mechanisms (i.e., rill and inter-rill erosion) by applying a process-based soil erosion model to British catchments with varying land-cover, topography, and soil characteristics. Our model results reveal that, even under a significantly wetter climate, warmer air temperatures can limit soil erosion across areas with permanent vegetation cover by enhancing primary productivity and in turn improving leaf interception, soil infiltration-capacity, and the erosive resistance of soil. Consequently, any increase in air temperature associated with climate change will increase the rainfall thresholds required to accelerate soil loss, and rates of soil erosion could decline by up to 50% from 2070-2099 compared to baseline values under the IPCC-defined medium-emissions scenario SRES A1B. We conclude that enhanced primary productivity due to climate change can introduce a negative-feedback mechanism that limits soil loss by surface runoff as vegetation-induced impacts on soil hydrology and erodibility to offset the effects of increased precipitation. The expansion of permanent vegetation cover over exposed ground could provide an adaptation strategy to reduce climate-driven soil loss.