Land degradation and climate change lessened soil erodibility across a wide area of the southern Tibetan Plateau over the past 35–40 years

Abstract

The Tibetan Plateau's alpine ecosystem has been undergoing accelerated climate change and severe vegetation degradation in the past four decades, which has triggered a sharp increase in soil erosion hazards. However, the combined impacts of climate change and vegetation degradation on soil erodibility (K) across geographical and temporal scales remain unclear. Here, we present the first systematic investigation of spatio-temporal variations in K under different land uses across the southern Tibetan Plateau over the last 35–40 years, and identify the associated driving factors based on a paired resampling campaign conducted in the 1980s and 2020, covering 148 field sites. K-values derived for the majority of grassland (75.0%) and cropland (66.2%) sites, as well as for a substantial number of forest sites (46.7%) showed a decreasing tendency with time, with average decreases of 31%, 14%, and 5%, respectively. Changes in K were primarily (17.6%) attributed to soil erosion, but were exacerbated by climate change (8.2%). Interestingly, the declines in K resulted in significant decreases in (predicted) soil erosion rates as long as strong disturbances from climate change and human activities were absent. These findings confirm the existence of a negative feedback mechanism between soil erosion and K in most alpine ecosystems on the southern Tibetan Plateau. Our results reveal the extent to which the impact of vegetation degradation on the magnitude of K is enhanced by climate change, thereby providing new insights into the feedback between alpine ecosystems, climate change, and anthropogenic interference.