Study On The Soil Microbial Diversity Along A Chronosequence Of Caragana Microphylla Plantations

The purpose of this study was to determine how Caragana microphylla plantations with an age sequence affected the microbial diversity of a sandy soil, with9-,16-and26-year C. microphylla plantations in Horqin Sandy Land being selected as the objects, moving sandy-dune and natural communities as controls. The diversities of carbon metabolic function, community structure, and gene of soil microbe of those treatments were study with the methods of Biolog microplate culture, PLFA analysis and DGGE techniques adopted respectively.Biolog microplate culture showed that, in Horqin Sandy Land, carbon metabolism diversity and evenness of soil microbe increased with the C. microphylla plantation age. Soil microbe in moving sand dune mainly constitute by amines, amino acids, aromatic and carboxylic carbon sources metabolize flora, and in sand-fixation communities by acids, amino acids, polymer and carbohydrate metabolize flora. With the increase of plantation age, the carbon source soil microorganism can metabolize showed an increasing trend, and soil microbe in26-year-old C. microphylla have gradually approached a carbon source metabolic model close to the natural communities.PLFA studies showed that, there were changes not only in species number but also in community sructure, and more over, sand-fixation plantions made a contribution to the diversification development of the structure of soil microorganism community. Characteristic fatty acids of bacteria, fungi, Gram-positive bacteria, Gram-negative bacteria and total characteristic fatty acids showed an increasing trend in content the increase of plantation age.By PCR-DGGE, an comparison between16S rDNA V3of siol microbial in different age C. microphylla plantions in Horqin Sandy Land was conducted, and the outcome showed that the microbial genetic diversity went down when plantions age grown up. Moving sand had an highest evenness of bacterial species within all soil samples, but, soil bacteria’s amount in natural C. microphylla community was the highest, with lowest richness and evenness on the contrary. Cloning and sequencing after DGGE gel band-cut showed that, Horqin Sandy Land and C. microphylla sand-fixation communities had Sphingomonas sp., Gemmatimonas sp., Pseudomonadales, Xanthomonadaceae, alpha proteobacterium, Gemmatimonadetes, Sphingobacteria, beta proteobacterium and other uncurcurable bacteria in the soil.