Soil Microbial Community Structure And Functional Diversity Marked By PLFA In Forestland

In hilly loess region of Jixian in Shanxi Province, loess deposition is very serious, the ecological environment is extremely fragile, and the soil quality is low. In recent years, the artificial forest restoration and other work have made the ecological environment in the region improved, soil quality has been greatly improved. This study was to evaluate the ecological restoration effect of different tree species in terms of microbial structural diversity, and to select the suitable artificial tree species and vegetation configuration mode for the technological support in ecological restoration of Hilly and gully region of Loess Plateau. The soil microbial PLFA content and community structure diversity of soil surface (0-10cm),10-20cm,20-40cm and 40-60cm in 4different plots——natural secondary forest,Robinia pseudoacacia and Pinus tabulaeformis forest and grassland as control were analyzed by provide Phospholipid Fatty Acid (PLFA) biomarkers. The conclusions of the study are as follows:(1)Soil microbial PLFA content and distribution in different restoration plots were different, and 27 common species of PLFA were measured. For total PLFA content,the natural secondary forest>Robinia pseudoacacia> Pinus tabulaeformis> grassland. The total PLFA percentage distribution unified, three PLFA-16:0,18:1ω9c 和 18:1ω9t in 4 kinds of plots were the highest. Microbial strains were different in all plots:for secondary forest, bacterial and fungal PLFA content was bigger than that of Robinia pseudoacacia, Pinus tabulaeformis forest and grassland; but the proportion of fungi in natural secondary forest decreases. Difference was found in Bacterial PLFA and fungal PLFA content, bacterial PLFA content have significant differences in the 4 kinds of samples; fungi PLFA in Pinus tabulaeformis forest and Robinia pseudoacacia forest was similar, and obviously different with natural secondary forest and grassland. In two artificial forest, fungi proportion significantly reduced; gram-positive bacteria and gram-negative bacteria g showed the same trend.(2)The soil microbial PLFA content in different restoration vegetation had obvious vertical distribution law. The study found that the microbial content showed a downward trend with soil depth increase, surface soil and 10-20cm soil concentrated more than 70% of soil microbes, and below 20cm the content of soil microbial biomass tends to be stable, microbial content decreased most slowly below 20cm in secondary forest.(3) The soil microbial community structure has significant difference under different plots, microbial communities was the most abundant and the evenness was the greatest in secondary forest soil, closed to Robinia pseudoacacia. Microbial communities differed significantly in two artificial forest. microbial diversity indexes were the lowest and obviously different with the 3 kinds of forestry.(4) Correlation coefficients between soil nutrient factors and soil bacteria, fungi, gram-positive bacteria/gram-negative bacteria (G+/G-) and bacteria/fungi (B/F) were different in all four soil layers, key factors that limiting microbial community and structure in all soil layers were different.