金沙江下游地区人类活动对土壤侵蚀的影响

Impacts of Human Activities on Soil Erosion in the Lower Jinsha River Basin

土壤侵蚀发生发展过程受自然因素和社会经济因素的共同作用。社会经济因素通过驱动人类活动间接作用于侵蚀过程,已成为土壤侵蚀的主要因素。作为长江流域土壤侵蚀最为严重的地区,金沙江下游独特的自然环境条件是造成其土壤侵蚀严重的基本条件,而不合理的人类活动加剧了这一过程。通过分析金沙江下游地区植被破坏、农业耕作、工程建设这三方面的人类活动对该地区的土壤侵蚀的影响,以及针对不合理人类活动所实施的恢复措施和政策,总结目前对人类活动影响土壤侵蚀过程认识的局限以及未来研究的方向。分析认为,争取认识金沙江下游干热气候的形成机制以及对人工生态系统的全面、系统、宏观评价,是建立正确的植被恢复策略的知识基础;农业耕作方面则应转换目前的研究重心,不应把过多精力集中在技术的改进和创新上,对于政策和市场经济对当地农民行为的驱动作用应予以相当的重视,并寻求改变山区农民顺坡陡坡耕作习惯的新思路和新方法;而工程建设方面则应加强监测与基础研究,特别是公路建设引发的土壤侵蚀情况。

Occurrence and development process of soil erosion is affected by both natural and socio-economic fac- tors. It is recognized that focusing exclusively on physical process only offers a partial interpretation of the causes of soil erosion. Socio-economic factors and human activities play an important role in causing and reducing soil erosion and should be fully incorporated in related research and extension programs. The lower Jinsha River Basin is char- acterized by the highest soil erosion rate in the Yangtze Basin. Determined by its unique biophysical conditions, the lower Jinsha River Basin is vulnerable to serious soil erosion, an environment problem recognized to be considerably severe in this area. Human activities have caused more intensive soil erosion in the region. Vegetation destruction, agricultural activities on sloping cropland and infrastructure construction have been recognized as the main contribu- ting factors. Gaps in knowledge and research are identified. The conclusion was made that more efforts should be made on the formation mechanism and evolution of physical environment condition, appropriate assessment of eco- logical restoration projects, feedback mechanism of farmer activities and policy, and impact of infrastructure con- struction on soil erosion.