Abstract: Bio-crust is the initial stage of natural primary succession in  copper mine tailings. With the Yangshanchong and Tongguanshan copper mine tailings in Tongling City of Anhui Province as test objects, this paper studied the soil microbial biomass C and N and the activities of dehydrogenase, catalase,
alkaline phosphatase, and urease under different types of bio-crust. The bio-c
rusts improved the soil microbial biomass and enzyme activities in the upper lay
er of the tailings markedly. Algal crust had the best effect in improving soil m
icrobial biomass C and N, followed by moss-algal crust, and moss crust. Soil mi
croflora also varied with the type of bio-crust. No significant difference was
observed in the soil enzyme activities under the three types of bio-crust. Soil
 alkaline phosphatase activity was significantly positively correlated with soil
 microbial biomass and dehydrogenase and urease activities, but negatively corre
lated with soil pH. In addition, moss rhizoid could markedly enhance the soil mi
crobial biomass and enzyme activities in moss crust rhizoid.

Key words: copper mine tailings, primary succession, bio-crust, soil microbial biomass, soil enzyme activity, forest plantation, eddy covariance, carbon flux, carbon source.