Studies On Soil Microbiological Characteristics Of Da Xinganling Mountains Burned Areas In Inner Mongolia

In this research, the burned areas in permafrost region of Da Xinganling Mountains in Inner Mongolia was used as plot, and soil samples of the burned area were studied from different burned years (2003,2008,2012) and different burned degree (light, heavy). The soil samples were collected in May、July、 October 2013 respectively. Soil microbiological characteristics were analyzed by common Microbiological analysis method and PCR-DGGE method. It will reveal variation characteristics of soil microbe from the burned area of Da Xinganling Mountains. And provide some basic academic evidences for the science management of forest ecosystem and forest regeneration.1.The quantity of bacteria, fungi and actinomycetes changed dynamically with the season in the same plot and showed July> October>May. There were different results that the influence of different degree fire on the number of the 3 types of microorganisms in different burned years. There were not significant difference between the different levels of burned area in 2003. There were significant difference in 2008 and 2012. The effect of different years to microbial number was reached significant difference (except individual).2. The activities of soil catalase, urease and invertase indicated the seasonal variation in the same burned area, which appeared July> October, May except a few. There were significant difference in the catalase and invertase activities of different months. But no significant difference in urease. It indicated that there were different effects on the different enzyme activities in different months. Different fire degree had significant influence on the activities of soil catalase, urease and invertase. There were significant difference in the catalase and invertase activities of different years, but no significant differences in urease.3.The soil microbial biomass carbon and nitrogen content showed seasonal changes in the same plots, which were July> October> May. There were significant differences in microbial biomass carbon and nitrogen in different months. Different fire degree had influences on both biomass carbon and nitrogen content. There were significant differences in microbial biomass carbon content at different fire degree, but no differences in biomass nitrogen. The influences of different years had significant differences on the soil microbial biomass carbon and nitrogen content.4.The analysis of soil bacterium 16S rDNA PCR-DGGE showed that seasonal changes happened in the soil bacterial diversity index (H), richness (S) in the same plots, July>October>May except individual. But the highest value of evenness (Eh) appeared in different months. There were significant difference in above 3 indexes in different months. The soil bacterial diversity index (H), evenness (Eh), richness (S) reached significant difference in different fire degree and different burned years. The results of DGGE Cluster analysis showed that the samples of light and heavy burned areas clustered together in same year, and the similarity reached 63%～80%. The burned areas and unburned areas did not gather into a cluster, and the similarity were 47%-69%. The effect of burned or unburned was greater than the degree of fire. The similarity of samples in different burned years was 47%～65%, which indicated that different burned years had an important influence on the bacterial community structure.