Abstract:

Through canonical correlation analysis the relationships between soil nutrients, soil microorganisms and soil enzyme activities were studied in vegetation restoration areas for soil degradation and erosion in the case of Nüerzhai watershed, northwest Hunan. The results showed that the key factors in soil nutrients, microorganisms and enzyme activities were N and P elements, bacterial number, soil microbial biomass carbon and nitrogen, and the activities of urease, polyphenol oxidase, phosphataese and invertease respectively. The activities of urease and polyphenol oxidase were related to the transformation of N and P elements which had important impact on the cumulation of soil microbial biomass carbon and nitrogen. Moreover, the activities of urease, polyphenol oxidase and phosphataese promoted microbial biomass carbon cumulation, however, invertease activities inhibited the cumulation of microbial biomass nitrogen. Urease activities were also beneficial to the N element content in soil and unfavorable for P element. There existed a negative relationship between the polyphenol oxidase activity and N element content. For every canonical variable group, the gathering tendencies of soil nutrients, microorganisms and enzyme activites in different soil layers in different vegetation restoration communities could offer some scientific basis for soil health diagnosis and site type dividision in the process of vegetation restoration.

Key words: vegetation restoration, soil nutrient, soil microorganism, soil enzyme activity, canonical correlation analysis (CCA)