Topsoil carbon-selective transport in an eroding soil landscape with vegetation restoration

Water erosion affects soil carbon (C) loss and C enrichment in deposited sediment. To better understand the dynamics of water erosion and topsoil C loss with sediments after vegetation restoration, we studied the sediment yield from each rainfall event over two growing seasons (June through October) in four runoff plots with different vegetation covers (Robinia pseudoacacia, Spiraea salicifolia, Stipa bungeana, and bare soil) in an eroding soil landscape on the Chinese Loess Plateau in 2016 and 2017. The results showed that the C loss in the deposited sediments was reduced by 99.0 +/- 0.5% when the soil was vegetated compared to bare soil. Decreased organic C enrichment ratios were shown under the vegetation cover (2.14 +/- 0.68 for tree cover, 1.34 +/- 0.20 for shrub cover, and 1.63 +/- 0.26 for grass cover) compared to bare soil (2.65 +/- 0.99). The decreasing organic C enrichment ratios were affected by the fractional vegetation coverage and soil organic C concentration. During organic C enrichment in the bare soil, the additional particulate organic C or mineral-associated organic C were based on the C enrichment ratio. The results can improve our understanding of C enrichment processes under different vegetation covers and help predict the C enrichment ratio in a vegetation restoration area.