The Research Of Soil Microbial Diversity In The Shennongjia Natural Reserve

Abstract:There are abundant microorganism sources and various microbial communities in different soil ecosystem. Soil microbes play a crucial role in driving the cycling of the matter and energy and have a significant impact in maintaining ecosystem function and biogeochemical cycling processes with the stabilization of the whole terrestrial ecosystem. So learning about microbial diversity contributes to us in the knowledge of the spatial patterns and mechanism involved in soil microbial distribution in further to develop sound management strategies of the terrestrial ecosystems. With the rapid development of molecular techniques, more and more researchers come to pay close attention to the microbial diversity and other related study.Shennongjia Natural Reserve standing in northwestern Hubei Province is located in the transition area between China’s subtropical and temperate zones, called the roof ridge of central China. Shennongjia Mountain (Mt. Shennongjia) presents an ideal location, the unique climate, landform, fertile brown soil and vegetation, and complex ecological environment breeds all kinds of vegetation types. This thesis discussed five typical vegetation types, subalpine bush (GM), subalpine coniferous forest (LS), mixed coniferous and deciduous forest (HJ), the deciduous broadleaved forest (JH, LK) and evergreen broadleaved forest (JC) along the altitude from1000m to2800m. In this study, we attach important to discuss soil microbial diversity in the Shennongjia Natural Reserve by using GeoChip-based and pyrosequencing-based metagenomic approaches. The main results were as follows:(1) Using the conventional plant diversity investigation method, our research was conducted into the plant diversity of different vegetation types and environmental impact factors. As the results shown, species richness and flora differentiation degree, Shannon diversity index and E.Pielou evenness index presented "the single-peak" distribution pattern on plant community along with the rising of altitude. DCA shaft analysis expressed that this distribution of vegetation pattern was influenced by the altitude gradient to a large extent. CCA analysis indicated that soil and terrain factors in general would reach53.35%explanation in terms of plant diversity variation pattern. These factors such as soil temperature, soil organic carbon, soil total nitrogen and soil pH, had a dominating impact on plant diversity distribution pattern.(2) We studied the distribution patterns and formation mechansim of soil microbial diversity along the altitude by16S rRNA pyrosequencing technique. The results showed that24695OTUs, one known archaeal phylum and18known bacterial phyla as well as unclassified phylotypes were detected. Shannon index analysis showed an obvious monotonous decrease (p<0.001) trend of microbes at whole community level and plants of trees and shrubs were found with the elevational increasing, and the bacterial compositional similarity at whole community level significantly decreased (p<0.001) with elevational distance by Bata diversity (Jaccard index and Bray index). VPA analysis showed that a total of48.31%of the variation was significantly explained by soil chemical factors, soil temperature and plant diversity. The different plant diversity types formed along elevation gradients and soil pH are significantly correlated (p<0.001) with the soil microbial diversity.(3) We selected two typical natural secondary forest succession stages of deciduous broadleaf forest, JH and LK (the natural mid-adult and mature secondary forest), and analyzed the succession of soil microbial community structure and metabolic activity involved in carbon and nitrogen cycling by using GeoChip-based and pyrosequencing-based metagenomic approaches. Pyrosequencing-based data showed that the microbial succession of community structure is significant altered at phylum level, but the responses of different phyla are difference with the time of succession. The phyla of Acidobacteria, Verrucomicrobia and Planctomycetes are three of most abundant soil bacteria in our study sites and significantly (p<0.05) increased with the time of forest succession. GeoChip-based data showed that functional genes involved in carbon and nitrogen cycle were more abundant in LK than in JH. Mantel test showed a significant relationship (p<0.05) between soil organic carbon and genes involved in carbon cycling. VPA analysis showed that81.58%of the variation of microbial community structure was explained by soil chemical factors, temperature and plant diversity.