Research Of Soil Microbial Biomass In Five Kinds Of Urban Greening Communities In Shanghai

Soil microbial biomass is the pool of soil nutrients and an important source of plant growth repository available nutrients in vegetation and soil system, which has important theoretical significance to improve soil fertility and maintain the ecological balance of natural soil. Microbial biomass carbon (MBC) and nitrogen (MBN) is often used as indicators of soil quality evaluation and reflects the state of microbial communities. In this study, we made three communities of single dominant species (Cinnamomum camphora community, Metasequoia glyptostroboides community, Platanus community) and two mixed communities (Cinnamomum camphora and Metasequoia glyptostroboides mixed community, Cinnamomum camphora and Platanus mixed community) as the object, focusing on soil microbial biomass carbon and nitrogen, to find the differences, temporal and spatial variation of soil microbial biomass in different community types, investigating the response law of soil microbes to different vegetation. And we wanted to find the main factors to regulate microbial biomass combining the soil properties, which provided the basis for the protection of urban community and evaluation of urban ecosystem health. The results are as follows:1. MBC and MBN content are decreased with soil depth under all the studied community types, and the content of 0-5cm soil layer was significantly higher than the other three soil layers. In all community types, except MBC content of Platanus community were higher in winter and summer than in spring and autumn, MBN were higher in summer and autumn than in spring and winter, microbial biomass carbon and nitrogen content of the rest community types are highest in autumn. In all kinds of community, MBC showed a significant seasonal dynamics, the seasonal variation of MBN in Platanus and Metasequoia Camphor mixed community were not significant, other community types were more obvious.2. On MBC, Camphor community and Metasequoia Camphor mixed community were higher than Metasequoia community; Camphor community and Camphor Platanus mixed community were overall higher than Platanus community. These indicated that Camphor was mixed with Metasequoia or Platanus can effectively improve the content of soil microbial biomass carbon of Metasequoia community or Platanus community. On MBN, Metasequoia community MBN were in higher levels in the three community types; Platanus and Camphor Platanus mixed community MBN were higher than Camphor community. Combined with the differences of soil microbial biomass carbon, it indicated the number and structure of microbial community in different communities were different.3. Camphor community MBC were affected in order of importance by soil pH, the organic matter content and temperature; Metasequoia community MBC were affected by soil bulk density, temperature and the soil organic matter; Platanus community MBC were affected by soil pH, the organic matter and total phosphorus content; Metasequoia Camphor mixed community MBC were affected by soil bulk density, the organic matter and total phosphorus content; Camphor Platanus mixed community MBC were suspended by bulk density. Camphor community MBN were affected by soil organic matter content; Metasequoia community MBN were affected by temperature and nitrogen content; Platanus community MBN were affected by soil organic matter and soil water content; Metasequoia Camphor mixed community MBN were affected by bulk density, total nitrogen content, water content and temperature; Camphor Platanus mixed community MBN were suspended by bulk density.