贵州喀斯特地区土壤石漠化的本质特征研究

CHARACTERISTICS OF SOIL ROCKY DESERTIFICATION IN THE KARST REGION OF GUIZHOU PROVINCE

喀斯特土壤石漠化是我国西南喀斯特地区诱发重要地质灾害的生态环境问题,是制约区域社会经济发展的关键因素。通过分析贵州喀斯特地区土壤的机械组成、物质成分、理化性质和微生物特性,探讨了土壤石漠化的本质。结果表明:土壤侵蚀,细粒物质减少,表层土壤消失,岩土界面缺少风化母质的过渡层,或者被裸露基岩取代;土壤质地出现砂化,颗粒变粗;土壤有机质及养分含量减少,保水保肥性能减弱;土壤微生物功能多样性降低;超载的社会经济压力等是导致喀斯特地区土壤石漠化最重要的驱动力。

Karst soil rocky desertification is not only a geo-ecological disaster induced by Karst geomorphy, but also a critical factor restraining social and economic development of Southwest China. Soil mechanical composition, physical features, chemical properties, microbial feature and chemical composition of soils were measured for studying the Karst rocky desertification. The results indicate that fine soil particles decrease propressively with soil erosion, leading to disappearance of surface soil layer and replacement of a sand layer. The absence of weathering parent material between soil and rocks makes calcareous soil unstable. Soil erosion at the rock-soil interface is a distinct character. Soil texture tends to be desertified. As a result, soil organic matter and nutrients in the surface soil layer reduce progressively and so do the soil's nutrient and moisture retention and functional diversity of the soil microbial communities.Soil formation is at the stage of chemical erosion and sand deposition. It could be concluded that rocky desertification is the final result of a vicious cycle of social economic stress and environmental deterioration.