Water Erosion Control of Undisturbed Soil Cores by Near Soil Surface Factors after 5-Year Vegetation Restoration in Red Sandstone Area from Subtropical China

Vegetation restoration has long been recognized as a practical way to control soil erosion in the eroded inferior lands of subtropical China. However, limited knowledge is available about the effects of long-term vegetation restoration on soil erosion and erodibility of soils derived from red sandstone, especially in field conditions. In the present study, the impacts of Cynodon dactylon (C. dactylon) and Coreopsis basalis (C. basalis) after 5 years of growth on undisturbed soil slope erosion and the respective contributions of near soil surface components (canopies, roots, and biocrusts) were explored by simulated rainfall experiments. Five years after ecological restoration, treatments greatly increased the organic matter content and average weight diameter of topsoil (0–20 cm) and slightly reduced the bulk density (P < 0.05), increasing aggregate stability. Intact plants (C. dactylon or C. basalis) plus biocrusts reduced the sediment yield rates (SYR) by 98.9% and 98.1%, respectively. The contribution rates of biocrusts for reducing the SYR and apparent interrill erodibility (Ki) were the highest, while the canopies of both plants were significantly more effective in reducing the SYR and Ki than their roots on average (P < 0.05). The contribution rates of biocrusts to the reduction of soil erosion increased as the rainfall intensity increased, while those of canopies showed the opposite trend, regardless of plant species. This study highlights the significant roles of plants with dense canopies and fibrous root system and well-developed moss biocrusts in reducing the water erosion in red sandstone eroded inferior lands. The results may contribute to improving soil and water conservation efforts in red sandstone eroded inferior lands from subtropical regions.