Shu Cheng-Bo, Shen Ying-Li, Liu Gang, Zhang Qiong, Xu Jing-Hua, Guo Zhen
State Key Laboratory of Soil Erosion and Dryland Agriculture, Institute of Soil and Water Conservation, Northwest Agricultural and Forestry University, Yangling 712100, Shaanxi, China.
Research Center of Soil and Water Conservation and Ecological Environment, Chinese Academy of Sciences and Ministry of Education, Yangling 712100, Shaanxi, China.
Ying Yong Sheng Tai Xue Bao. 2023 Apr;34(4):1015-1023. doi: 10.13287/j.1001-9332.202304.021.
Unreasonable exploitation of artificial forest causes severe soil erosion in the mountainous areas of sou-thern China. The spatial-temporal variations of soil erosion in typical small watershed with artificial forest has signifi-cant implications for artificial forest exploitation and sustainable development of mountainous ecological environment. In this study, we used revised universal soil loss equation (RUSLE) and geographic information system (GIS) to evaluate the spatial and temporal variations of soil erosion and its key drivers of Dadingshan watershed in mountainous area of western Guangdong. The results showed that the erosion modulus was 1948.1 t·km·a (belonging to light erosion) in the Dadingshan watershed. However, the spatial variation of soil erosion was substantial, with variation coefficient of 5.12. The maximal soil erosion modulus was 191127 t·km·a. Slight erosion (<500 t·km·a) accounted for 80.6% of the total watershed area. The moderate erosion and above (>2500 t·km·a) were mainly distributed in young forest area with less than 30% of the vegetation coverage, which contributed nearly 75.7% of total soil erosion. During 2014-2019, the interannual variations of mean erosion of Dadingshan catchment was modest, but the spatial variation of soil erosion was large. Vegetation cover, slope, and rainfall were key drivers of such variation. The destruction of natural vegetation resulted by plantation exploitation was the primary cause of soil erosion in afforestation areas. Soil erosion significantly increased with the increases of slope gradient in the young forest area, which was aggravated by extreme rainfall. However, soil erosion gradually decreased with the increases of the age of plantation. Therefore, the hot spot of soil erosion was young forest areas of plantation with slope >25°, and the key period for soil erosion control was the first 2-3 years after planting. We suggested that reasonable afforestation measures should be used in area with >25° slopes, and that the destruction of natural vegetation should be avoided on hillslope with >35° slope gradient. The road construction standards and forest management should be further improved to address the challenge of extreme rainfalls.
人工林的不合理开发导致中国南方山区严重的水土流失。人工林典型小流域土壤侵蚀的时空变化对人工林开发和山区生态环境的可持续发展具有重要意义。本研究利用修正的通用土壤流失方程（RUSLE）和地理信息系统（GIS），对粤西山区大顶山水流域土壤侵蚀的时空变化及其关键驱动因素进行了评估。结果表明，大顶山水流域侵蚀模数为1948.1 t·km·a（属于轻度侵蚀）。然而，土壤侵蚀的空间变异较大，变异系数为5.12。最大土壤侵蚀模数为191127 t·km·a。轻度侵蚀（<500 t·km·a）占流域总面积的80.6%。中度及以上侵蚀（>2500 t·km·a）主要分布在植被覆盖率小于30%的幼龄林区，其土壤侵蚀量占总侵蚀量的近75.7%。2014—2019年，大顶山集水区平均侵蚀量的年际变化较小，但土壤侵蚀的空间变异较大。植被覆盖度、坡度和降雨是这种变化的关键驱动因素。人工林开发导致的天然植被破坏是造林区土壤侵蚀的主要原因。幼龄林区土壤侵蚀随坡度增加而显著增加，极端降雨加剧了这种情况。然而，随着人工林年龄的增加，土壤侵蚀逐渐减少。因此，土壤侵蚀的热点区域是坡度大于(25°)的人工林幼龄区，土壤侵蚀控制的关键时期是造林后的前2—3年。我们建议，在坡度大于(25°)的区域应采取合理的造林措施，在坡度大于(35°)的山坡应避免破坏天然植被。应进一步提高道路建设标准和森林管理水平，以应对极端降雨的挑战。
