Increasing lateral transport of soil and carbon on the Tibetan Plateau

Abstract

<p>Soil erosion by water and loss of soil organic carbon (SOC) are two major contributors to global land degradation. However, the impact of soil erosion and its effect on SOC in the fragile, sensitive alpine ecosystem of the Tibetan Plateau, where climate change is amplified, is not well understood. We used the Universal Soil Loss Equation (USLE) ensemble model to analyse soil erosion, SOC loss, and their dynamics over the past 40 years (1981–2018) on the Tibetan Plateau. The mean soil erosion and SOC erosion rates were 5.91 ± 2.29 t ha−1 yr−1 and 0.374 ± 0.113 t C ha−1 yr−1, respectively, with significant increasing trends because of increased rainfall. Spatially, we identified areas prone to soil and SOC erosion across the plateau. SOC erosion rates rose by 19.0 %, from 0.34 ± 0.03 t C ha−1 yr−1 in the 1980s to 0.40 ± 0.02 t C ha−1 yr−1 in the 2010s. The increasing erosion rates after 1999 were weakened because of the slow increase in rainfall and rapid vegetation greening. Two distinct erosion mechanisms emerged concerning land use: rainfall-dominated and slope-dominated. Our findings underscore the extreme vulnerability of soil erosion and SOC loss on the Tibetan Plateau to climate change, providing helpful insights for sustainable land resource management in this ecologically fragile environment and enhancing our understanding of the incipient impact of soil erosion on the carbon cycle.</p>