Drivers of water erosion-induced lateral soil carbon loss on the Tibetan Plateau

Abstract

The lateral transport of soil organic carbon (SOC) induced by soil loss has global significance for understanding the terrestrial carbon budget. On the Tibetan Plateau, this is regulated by a complex interplay of environmental factors including soil properties, terrain attributes, climate variables, and vegetation conditions. However, it remains unclear how water erosion-induced SOC detachment responds to ongoing environmental changes. In this study, we used remote sensing, ground observations, and grid datasets to investigate the spatial distribution of lateral SOC loss and its drivers across the Tibetan Plateau from 2001 to 2017. The potential mean annual soil carbon erosion rate of 208.97 kg C ha−1 yr−1 was equivalent to an annual potential SOC removal flux of 40.72 Tg C over the study period. Approximately 95% of lateral SOC loss occurred in grasslands and forests. Soil properties such as bulk density and pH accounted for 31% of the relative influence on lateral SOC transfer, followed by terrain attributes such as terrain ruggedness index and altitude (25%). Climate and vegetation accounted for 22% of the relative influence on lateral SOC transfer, respectively. However, the most influential environmental indicator was the annual mean temperature. The interconnections of soil, terrain, climate, and vegetation in determining lateral SOC loss were identified by a path analysis. There is a need to include environmental drivers when assessing soil carbon dynamics to better inform decision makers developing strategies for managing carbon budgets.