Erosion and dispersal processes drive vegetation trajectories in a highly erosive badland catchment

Abstract. Badlands are among the most erosive places on earth, providing large sediments fluxes to rivers and oceans. In these environments, erosion is strongly controlled by vegetation, whose cover and composition both vary in space and time. Quantifying vegetation dynamics and their drivers is therefore essential to understand and predict badland erosion. Here, we use time series of high-resolution aerial and Landsat satellite imageries to reconstruct 40 years of vegetation change in a highly erosive badland catchment of French south-western Alps. Vegetation cover increased from 38.7 % to 46.2 % of the studied area), primarily through the colonization of bare surfaces by young pines. Spatial patterns of colonization and extinction are driven both by geomorphic factors, such as slope stability and local erosion rate, and by ecological factors, such as grain dispersal. Remotely sensed greening trends are correlated with climate, initial vegetation type and colonization intensity, suggesting that both climate changes and ecological succession are contributing to the greening of badlands. Quantifying these spatial and temporal trends reveals that vegetation dynamics are tightly coupled with erosion, as they both control and respond to erosion patterns.