Soil Microbial Characteristics In Wet Meadows Of Zhalong Wetlands

In this paper, the typical wet meadow in zhalong wetland was taken for the experimental object. The soil microbial characteristics, the spatial distribution of soil nutrients and its major impact factors under different salinization were investigated to reveal the driving mechanism of wetland degeneration process and provide the theory basis for the ecological restoration of the degraded natural wetland in china. Wetland soil total nutrient evaluation model and microbiology prediction model were also constructed in this study for the first time. Additionally, the seasonal dynamics and vertical changes along soil profiles of soil microbial biomass carbon (MBC) and nitrogen (MBN) under different human interference intensities in typical wet meadows were also studied for discussing their major influencing factors and the response mechanism to human disturbance and providing important reference for carbon and nitrogen biological geochemical cycles in this special habitat. The conduct of this study will provide the theoretical basis and technical support for the protection and management of wetlands. The results as follows:1. In wet meadows under different degradation degree in zhalong wetland, the number of the bacteria was dominant, actinomycetes followed, and fungi was least in soil microorganism community structure, the proportions are 73.73%-91.64%,0.32%-16.90% and 0.01%-0.33% respectively.2. Under different degradation (salinization), the quantities of microbial community, the microbial biomass carbon and nitrogen and soil nutrients in the seasonal wet meadow had the obvious characteristics of vertical distribution, but there were some differences in spatial distribution. It generally showed that the soil nutrients and the microbial activities were decreased with the increase of soil degradation (salinization); the soil enzyme activity and its spatial distribution were complicated which were affected by many factors.3. Under different levels of degradation in wet meadow in Zhalong wetland, there was closely relationship between soil nutrients and soil microbial properties, it embodied that:each of the activities of beta glucosidase, urease and phosphatase was significantly positively correlated to soil microbial biomass carbon and nitrogen (P<0.05), soil organic C to the quantities of actinomycetes and the activity of catalase(P<0.05), available K to the amount of bacteria (P<0.05), total N to the amount of actinomyce (P<0.05), alkali-hydrolyzable N to the activity of beta glucosidase(P<0.05) and C/N ratio to MBN (P<0.05); whereas total P as well as pH was not significantly correlated with soil microbial activity (P>0.05).4. In addition, total soil nutrient evaluation model and microbiology prediction model were also constructed by principal component analysis in this study for the first time. Namely: (1) The comprehensive evaluation model of total soil nutrient Y=0.3116x1+0.2438x2+0.2659x3+0.2770x4+0.2012x5+0.3116x6+0.1913x7Where:Y1, Y2, Y are the values of total soil nutrient; x1 for the content of organic matter; x2 for the total N; x3 for the total P; x4 for the Alkali-hytrolyzabel N; x5 for Available K; x6 for organic C; x7 for the C/N.(2) The soil nutrient prediction models in microbiology for predicting future trend Y=0.0952x1+0.1146x2-0.0363x3+0.1085x4+0.1288x5+0.2039x6+0.1681x7+0.1758x8+0.1747x9 +0.1361x10+0.1410x11+0.1935x12Where:Y for the total soil microbial activity; x1 for the urease activity; x2 for the acid phosphatase activity; x3 for the alkaline phosphatase activity; x4 for the phlyphenol oxidase activity; x5 for the catalase activity; x6 for theβ-glucosidase activity; x7 for microbial biomass carbon (MBC); x8for microbial biomass nitrogen (MBN); x9 for the number of bacteria; x10for the number of fungi; x11for the number of actinomycete; x12 for the total count of microorganism.5. Both MBC and MBN decreased significantly with the depth increasing of the soil in all study sites in different function areas, and the trial plot and buffer area were significantly greater than the core area. The difference between distributions of soil microbial biomass in the same depth of every study sites was obvious. Moreover, the distributional difference of soil MBN was significantly less than MBC in all study sites.6. The season dynamic of soil MBC and MBN were more regularly, and their change patterns were all significantly "W" types. But the seasonal dynamics of soil microbial biomass was complicated because soil environmental as well as the human interference intensities in every site was different and the main factors were changed in each period.7. Correlation analysis indicated that both MBC and MBN were significant positively correlated with soil organic carbon content, available phosphorus content (P<0.05), most significantly correlated with the soil water content (P<0.01).The main soil factors that contributed to the spatio-temporal patterns of the soil microbial biomass in different function areas were different. In addition, Human influences also impacted soil microbial biomass significantly, which mainly affected the spatial and temporal distribution of soil microbial by changing the characteristics of the water, types of wetland and the vegetation communities, and so on.