The Research Center of Soil and Water Conservation and Ecological Environment, Chinese Academy of Sciences and Ministry of Education, Yangling 712100, Shaanxi, China.
Institute of Soil and Water Conservation, Chinese Academy of Sciences and Ministry of Water Resources, Yangling 712100, Shaanxi, China.
Ying Yong Sheng Tai Xue Bao. 2023 Jun;34(6):1555-1562. doi: 10.13287/j.1001-9332.202306.011.
Rainfall is critical to the regulation of slope runoff and soil water recharge. Grazing affects land cover and soil structure, with consequence on slope runoff generation and soil water recharge. Little attention has been paid to the effects of rainfall on soil water recharge caused by grazing. In this study, we examined land covers and soil water contents under different grazing intensities (G1-G5: 2.2, 3.0, 4.2, 6.7, 16.7 sheep·hm) and no grazing sites (NG), aiming to analyze soil water recharge under natural rainfall conditions after grazing. The results showed that grazing exerted significant effects on vegetation and biocrust coverage. The vegetation coverage was decreased by 8.3%-16.4% under G1-G5 grazing, while the biocrust coverage was increased by 106.9% under G2 grazing compared to NG. The soil surface roughness under G1-G5 grazing was increased by 53.1%-152.5%, and the thickness of biocrust was decreased by 24.1% under G5. Soil wetting front velocity decreased with increasing rainfall intensity, and that of 0-5 cm layer under the G2 grazing intensity decreased by 60.0% to 83.3% under rainfall between 18.0 mm and 70.3 mm compared to NG. The effect of grazing on soil wetting front velocity was significantly related to biocrust coverage and soil bulk density of 0-5 cm soil layer. Generally, grazing did not affect soil water recharge rates of the slope grassland on the Loess Plateau. G2 grazing may prolong the migration time of soil water in the surface layer by increasing the coverage of cyanobacteria biocrusts, which may be beneficial to the restoration of soil microenvironment. Our results provided scientific basis for water management in the enclosure grassland of the Loess Plateau in the "post-conversion era".
降雨对坡面径流水和土壤水分补给起着关键作用。放牧会影响土地覆盖和土壤结构，从而影响坡面径流量的产生和土壤水分补给。但是，很少有人关注放牧对土壤水分补给的影响。在这项研究中，我们研究了不同放牧强度（G1-G5：2.2、3.0、4.2、6.7、16.7 只羊·hm-2）和无放牧区（NG）下的土地覆盖和土壤水分含量，目的是分析放牧后在自然降雨条件下土壤水分的补给情况。结果表明，放牧对植被和生物结皮覆盖有显著影响。在 G1-G5 放牧下，植被覆盖率下降了 8.3%-16.4%，而在 G2 放牧下，生物结皮覆盖率增加了 106.9%，比 NG 区高。在 G1-G5 放牧下，土壤表面粗糙度增加了 53.1%-152.5%，在 G5 放牧下，生物结皮厚度减少了 24.1%。土壤湿润锋速度随降雨强度的增加而降低，在 18.0-70.3 mm 降雨条件下，G2 放牧强度下 0-5 cm 土层的土壤湿润锋速度比 NG 区下降了 60.0%-83.3%。放牧对土壤湿润锋速度的影响与生物结皮覆盖率和 0-5 cm 土壤层的土壤容重显著相关。总体而言，放牧对黄土高原坡面草地的土壤水分补给速率没有影响。G2 放牧可能通过增加蓝藻生物结皮的覆盖度来延长表层土壤水分的迁移时间，这可能有利于土壤微环境的恢复。我们的研究结果为黄土高原封育草地在“后转化时代”的水分管理提供了科学依据。
