Moderate topsoil erosion rates constrain the magnitude of the erosion-induced carbon sink and agricultural productivity losses on the Chinese Loess Plateau

摘要

Despite a multitude of studies, overall erosion rates as well as the contribution of different erosion processes on Chinese Loess Plateau (CLP) remain uncertain, which hampers a correct assessment of the impact of soil erosion on carbon and nutrient cycling as well as on crop productivity. In this paper we used a novel approach, based on field evidence, to reassess erosion rates on the CLP before and after conservation measures were implemented (1950 vs. 2005). We found that current average topsoil erosion rates are 3 to 9 times lower than earlier estimates suggested. Under 2005 conditions, more sediment was produced by nontopsoil erosion (gully erosion (0.23 +/- 0.28 Gt yr(-1)) and landsliding (0.28 +/- 0.23 Gt yr(-1)) combined) than by topsoil erosion (ca. 0.30 +/- 0.08 Gt yr(-1)). Overall, these erosion processes mobilized ca. 4.77 +/- 1.96 Tg yr(-1) of soil organic carbon (SOC): the latter number sets the maximum magnitude of the erosion-induced carbon sink, which is ca. 4 times lower than one other recent estimate suggests.