Primary Succession Of Microflora Along Glacier Forefield Of Urumqi Glacier No. 1.

The global climate has warmed progressively since the'little Ice Age'. Glacier as one of sensitive indicators of global warming receded in vast area on the earth, resulting in newly exposed land known as glacier forefields, where primary succession occured, accompanying with organic matter accumulation, biogeochemical cycle,and soil formation. Microorganisms played important roles in soil formation and facilated later successional organisms to colonize on the glacier foreland, however, comparing to plants, little attention had been payed to microorganisms. Glacier foreland represented physical, chemical and biological chronosequence, thus we can empoy space-for-time substitution method to investigate primary succession of microflora on the glacier forefield. It will help us understand shifts in microbial community structure and function in primary succession, and provide some evidences to ascertain their ecology function finally.This study aimed at different successional age soils on Urumqi Glacier No.1 glacier foreland , by T-RFLP, Biolog microplate and measurement of soil enzyme activity as well as microbial biomass to investigate microbial community strucrure , ecological characterization and functional diversity. The results are as follows:1. In order to clarify ecological characterization and effect factors of soil microflora in primary succession across glacier forefield ,we collected soil samples along six different successional ages (0, 4, 15, 31, 43-year-old and reference), beginning at the terminal moraine levees, a site with well-developed soils immediately outside the glacier forefield served as reference,soil enzyme activities, microbial nitrogen mineralization , deamination and microbial biomass were measured. The results suggested that soil urease, protease, acid phosphatase, arylsulphatase, sucrosease, microbial nitrogen mineralization and deamination increased along the chronosequence, microbial biomass carbon and nitrogen were variable, with no clear pattern over the chronosequence; soil enzyme activities and microbial biomass had a significantly positive correlation with soil organic matter(P was less than 0.01). Soil microflora diversity index of Glacier NO.1 foreland increased along successional ages, and do not reach stability at present.2. We use Biolog ECO plates to study shifts in functional diversity. The results suggested that functional diversity of 15-y soil was different from other successional ages(P was less than 0.05)significantly. Average well color development (AWCD) and diversity indices(Shannon index and McIntosh index) of 15-y soil was significant lower than others . Both Principal component analysis and Cluster analysis results showed level and style of source substrate utilization between 15-y and other successional age soils was different . Amino acids and amines were utilized by most of organisms.3. We investigeted shifts in soil Archael community at different successional age by T-RFLP analysis, the results suggested Archael community structure changes along primary successional gradients, the highest diversity was found in 0-y soil , but there was a tendency of decling diversity in late succession. Canonical Correspondence Analysis(CCA) results suggested that total phosphorus and total salt affected Archael community diversity.4. We investigeted shifts in Ammonia oxidizing bacteria community at different successional age soil by T-RFLP analysis. The results showed reference soil reached the highest diversity. Cluster Analysis suggested 0-y and reference soil clustered in one group. Canonical Correspondence Analysis(CCA) showed Ammoniac Nitrogen, total salt and pH were main factors affected Ammonia oxidizing bacterial diversity.