Effects Of Plant Functional Groups And Plant Species On Soil Microbial Composition In Typical Grasslands

Soil microorganisms are important compoents of grassland ecosystem, and closely relates with plants. The abundance and biodiversity of bacteria and fungi in bulk soils under different plant functional groups and in soils from the rhizosphere and nonrhizosphere of different grass species were analyzed using quantitative real-time PCR, automated ribosomal intergenic spacer analysis (ARISA), cloning and sequencing and Terminal Restriction Fragment Length Polymorphism (T-RFLP) under plant functional group removal treatments and degradation treatments, in order to study the effect of plant community composition and plant species on soil microbial communities in a typical Inner Mongolia grassland. The results are as follow.1. Under plant functional group removal treatments, our results indicated that changes in plant functional group affect bacterial abundance, but not fungal abundance or bacterial/fungal community structure in bulk soil.2. Under plant functional group removal treatments, the abundance of bacteria and fungi in the rhizosphere soil varied with plant species. Cluster analysis revealed that community structure of bacteria and fungi also varied among plant species in the rhizosphere soil but not in the bulk soil. which was more evident for bacteria. Our results point to the ways in which plant species can influence soil bacterial and fungal communities through the action of their roots.3. The results of degradation treatments proved effects of plant species on the abundance of bacteria and fungi in the rhizosphere and nonrhizosphere soil. Cluster analysis (ARISA) revealed that community structure of bacteria varied among plant species in the rhizosphere soil but not fungal community in the rhizosphere and bacterial community in the nonrhizosphere soil. In the analysis of T-RFLP, bacterial and fungi community did not vary among plant species in the rhizosphere and nonrhizosphere soil, but the community structure of bacteria in Achnatherum sibiricum rhizosphere soil can cluster in high similarity coefficient.4. The abundance of fungi in the rhizosphere soil is much more than that in the nonrhrizosphere soil. The analysis of T-RFLP showed that the community composition of soil fungi in the rhizosphere soil is different from that in the nonrhizosphere soil.