| As the driver of the material cycle and energy flow in the soil ecosystem, soil microbial community can be used to understand the soil ecological processes and their responses to changes in the aboveground vegetation. The content and proportion of soil carbon (C), nitrogen (N) and phosphorus (P) are vital indicators of the reaction within soil C, N and P cycling, and are important parameters to assess the soil nutrient balance. Furthermore, changes in the proportion of soil C, N and P can be used to evaluate the ecological responses to global change. Therefore, this study was to assess the response of soil microbial community structure and soil chemical properties to three important factors:1) aboveground vegetation,2) litter management,3) different land use. Three experiments were conducted:(1) a serials of forest types were selected in the Huangni River National Forest Conservation, which are in different vegetation development stage (birch sapling forest, birch forest, Betula platyphylla near mature forest, mature forest, young forest, Mongolia oak, Mongolia oak, Mongolia oak forest near mature forest, mature forest, Quercus Mongolia, young coniferous coniferous forest, different ground vegetation communities in the broad-leaved forest, near mature forest and the broad-leaved Pinus koraiensis forest), (2) A litter management experiment was conducted in a broad-leaved Korean pine forest in the Changbai Mountain, which involved litter removal, control and litter addition, (3) a land use experiment was conducted with three types of ecosystems, i. e., forest, grassland and farmland ecosystem. PH, the content and proportion of soil C and N, P, microbial biomass (SMB) and community structure were quantitatively determined.Results:1) in the first experiment, soil total C, total N and total P in Mongolia oak, birch forest, coniferous and broad-leaved mixed broadleaved Korean pine forest, changed with forest developmental stages without obvious regular trend; forests with different ground vegetation community composition has great influence on the chemical properties of soil; soil microbial biomass showed a inverted "Ⅴ" trend in different developmental stages of the birch forest, A tendency of "N" for SMB was observed in oak forests. There were significant differences in vegetation community composition, microbial biomass in the different forest types. There was a significant difference in soil PLFA among the forest types. The PLFAs that had a great contribution to soil PLFA are 18:lcω5c,18:1 ω9c,17:0 iso,17:ant,15:0 iso,16:0,18:0,18:1ω7c,18:0 10-methyl and16:0 10-methyl.2) In the litter manipulation experiment, litter removal had no significant effect on soil chemical properties and microbial biomass in the depth of 0-5 cm soil, litter addition treatment significantly increased the total C, N content and C/P ratio, had a significant impact on gram positive bacteria, increasing trend is obvious for 18:1ω5c,17:1 ω8c,18:1ω9c,15:0 iso,16:0 iso,16:0,18:1ω7c PLFA. Litter treatments increased soil C/N ratio in the depth of 5-10cm soil, it had no significant effect on the soil microbial biomass, the PLFAs that had a great contribution to soil PLFA are 16:1ω9c、16:1ω7c、18:0 iso、14:0 ant、 18:1ω7c.3) In the land use experiment, difference between chemical properties is very significant. Microbial biomass, microbial community structure of grassland and cropland showed significant differences; Grassland and farmland in addition to the gram-positive bacteria there was no significant difference on the microorganism amount. Farmland and grassland showed a similar microbial community structure,18:1ω9c,17:1 ω8c,16:1ω9c,16:0 iso,17:0 ant,14:0 ant,16:0,18:1ω7c,16:1ω5c, 18:2ω6cand 18:0 10-methyl contributed to soil PLFAs significantly. |
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