Abstract: To investigate soil microbial properties and their correlation with soil nutrients under different tropical vegetation types in Shiwan Dashan Mountain, Guangxi, China, the soil physicochemical properties, microbial quantity and microbial biomass carbon, nitrogen and phosphorus of secondary broadleaved forest, masson pine forest, shrubgrassland and abandoned land were comparatively analyzed. The results indicated that the number of total microbes in the same soil layer followed the order of secondary broadleaved forest > masson pine forest > shrubgrassland > abandoned land, and it decreased with the increasing soil depth. Soil microbial biomass carbon, nitrogen and phosphorus decreased with the increasing soil depth, and significant differences existed among the different vegetation types. Soil microbial biomass showed significant relationships with soil nutrients in secondary broadleaved forest, masson pine forest and shrubgrassland. Such relationships in the abandoned land were obviously lower than in the other three vegetation types. Moreover, soil microbial biomass phosphorus had no correlation with total nitrogen, available nitrogen and potassium in the abandoned land. Therefore, the number of soil microbes and soil microbial biomass can be used as indicators to evaluate soil fertility of forest ecosystem in Shiwan Mountain, Guangxi. Revegetation should be adopted to facilitate the development of soil microbial communities and improve soil characteristics, so as to promote the rehabilitation of the degraded ecosystems.

Key words: land-bridge island, ground dwelling beetles, species diversity, mainland study site, habitat fragmentation