Abstract: With the adjacent plots of fixed, semi-fixed, and moving sand dunes in west Horqin sandy land as test objects, this paper studied the change characteristics of soil microbial biomass, enzyme activities and nutrients as well as the relationships among the three indices in the process of desertification. The results showed that soil nutrient contents, microbial biomass, and enzyme activities all decreased gradually with increasing soil depth. In the process of desertification, soil nutrient contents had a heavy loss, and soil microbial biomass C , N and P as well as the activities of urease, protease, saccharase, phosphatase, dehydrogenase, polyphenol oxidase, nitrate reductase decreased significantly. Soil biological activity was very sensitive to desertification, and its decrease was the quickest in the phase from fixed to semi-fixed sand dune. There existed significant correlations among soil microbial biomass, enzyme activities and nutrient contents.

Key words: Gongbiela Basin, Wetland, Hydrochemical characteristics, Seasonal dynamics