Soil Microbial Abundance in Picea Crassifolia Forests with Different Damage Degrees in Jiuzhaigou Earthquake-stricken Areas

In order to explore the effects of earthquake on forest soil microorganisms, which is the most sensitive biological index to environmental change and more reliable than soil organic matter, the soils of damaged Picea crassifolia forests were taken as the research object in Jiuzhaigou county, Sichuan province. The seasonal dynamic characteristics of soil microbial abundance of different damaged Picea crassifolia forests were compared by real-time fluorescence quantitative PCR. The results showed that, compared with the control, the abundance of soil bacteria and fungi decreased but not significantly in Picea Crassifolia forests with different damage degrees by the earthquake. The abundance of bacterial 16S rDNA gene copy number in damaged forest soil ranged from 4.39×10⁸ to 9.58×10⁸ copies/g dry soil, and the abundance of fungal 18S rDNA ranged from 1.58×10⁶ to 2.09×10⁶ copies/g dry soil. Meanwhile, the abundance of soil microorganisms in each damaged forest plots fluctuated greatly with time, showing obviously seasonal variation characteristics. The abundance of bacterial 16S rDNA gene copy number increased significantly from spring to summer, reaching the highest value in the whole year, and then decreased significantly from summer to winter. While the abundance of soil fungal 18S rDNA decreased slightly from spring to summer, and gradually increased from summer to winter. Correlation analysis showed that the soil microbial abundance of each damaged forest plot was deeply affected by soil pH, soil total porosity, soil total nitrogen and soil bulk density. The results can provide scientific basis for the restoration, reconstruction and coordination of forest soil ecosystems after earthquake.