Effects of degradation level and vegetation recovery age on soil erodibility of alpine grasslands on the Qinghai-Tibetan Plateau

PurposeThe study of soil erodibility is an important step in understanding the mechanism of soil erosion, and is crucial to the sustainable development of grassland ecosystems. However, few studies have investigated the potential effects of different degradation levels and restoration ages on soil erodibility on the Qinghai-Tibetan Plateau where many alpine grasslands suffering from severe degradation have been restored for different years.Materials and methodsIn order to quantify the impact of alpine grassland degradation and restoration on soil erodibility, we selected different degradation levels (non-degraded, lightly degraded, moderately degraded, and heavily degraded) and restored ages (3, 8, 13, and 19 years) on the Qinghai-Tibet Plateau. Soil sampling was carried out at different depths, and the microaggregate fractal dimension (D-v), multifractal theory (D-m) and erodibility factor (K) were measured and calculated to quantify the soil changes in erodibility.Results and discussionWith the degree of degradation increased, the K value in the surface soil changed little, but the D-v value increased significantly. On the grassland recovery sequence, the K value showed a trend of increasing first and then decreasing, and the K factor and D-m of 19-y restored grasslands was reverted to the same level as that of the non-degraded site. Furthermore, the K value and D-v value increased with the increase in soil depth. Our result also shows that root biomass, microorganisms, and soil physicochemical properties including SOC, TN, TP, PSD, and MSD were all significantly correlated with K value.ConclusionsOur research proves that restoration of alpine grassland on the Qinghai-Tibet Plateau helps reduce soil erodibility, and reveals that plant roots, soil physical and chemical properties, and microorganisms play an important role in reducing soil erodibility, further deepening the influence on soil erodibility. This understanding can provide a certain theoretical basis for the sustainable development of grassland ecosystems.