模拟氮沉降和隔离降雨对杉木林土壤微生物功能基因丰度的影响

Global environmental change，such as nitrogen（N）deposition and drought，profoundly affect biodiversity and ecological functionality in forest ecosystems，however，the combined effects of N addition and drought on the abundance of microbial functional genes in forest soils remain largely unclear. The current study was conducted in a Chinese fir plantation in subtropical regions，utilizing Soil samples collected from an experiment with four treatments：control，nitrogen addition（N，40 kg·hm^-2·a^-1），precipitation exclusion（PE，50% precipitation was excluded），and combined N and PE（PEN）. The abundances of microbial functional genes involving in carbon，nitrogen and phosphorus cycling in forest soils were examined using quantitative PCR. We found that although both N addition and PE had no significant effect on the abundance of microbial functional genes，seasonal change had significant effects on the abundance of these genes，with generally higher abundance detecting in winter than in summer，except for nitrification functional genes. Moreover，correlation analysis showed that the abundance of denitrification genes was significantly and positively correlated with soil total phosphorus（TP）. In contrast，the abundances of most other C，N and P cycling functional genes were negatively correlated to soil TP，underscring the vital role of soil TP in influencing potential microbial functionality in subtropical forest soils. This study provide a comprehensive evaluation of the interactive effects of N addition and precipitation exclusion on the abundance of soil C，N，P cycling associated microbial functional genes，which would have critical implications for the sustainable management of Chinese fir plantations in subtropical regions under future global change scenarios.