In order to explore how soil warming and precipitation exclusion influence soil N2O fluxes, we used related functional genes as markers, and four treatments were set up, i.e. , control (CT), soil warming (W, 5 ℃ above the ambient temperature of the control), 50% precipitation reduction (P), soil warming plus 50% precipitation reduction (WP). The results showed that precipitation exclusion reduced soil ammonium nitrogen concentration significantly. Soil warming decreased soil N2O flux and soil denitrification potential significantly. Soil microbial biomass nitrogen (MBN) in warming treatment (W) and precipitation exclusion treatment (P) was significantly lower than that in the control. The amoA gene abundance of AOA was negatively correlated with MBN and ammonium nitrogen contents, but neither soil nitrification potential nor soil N2O flux was correlated with the amoA gene abundance of AOA. Path analysis showed that the denitrification potential affected soil N2O flux directly, while microbial biomass phosphorus (MBP) and warming affected soil N2O flux indirectly through their direct effects on denitrification potential. Temperature might be the main driver of N2O flux in subtropical forest soils. Global warming would reduce N2O emissions from subtropical forest soils.
设置对照(CT)、增温5 ℃(W)、隔离50%降雨(P)和增温5 ℃+隔离50%降雨(WP)4种处理，以相关功能基因作为标志物，研究增温和隔离降雨影响亚热带森林生态系统土壤N2O通量变化的途径.结果表明： 隔离降雨显著降低了土壤铵态氮浓度；增温显著降低了土壤N2O通量和土壤反硝化势.增温处理(W)和降雨处理(P)的土壤微生物生物量氮(MBN)均显著低于对照(CT)，AOA amoA 基因丰度与MBN和铵态氮含量之间呈显著负相关，但与土壤硝化势和土壤N2O通量没有显著相关性.路径分析显示，反硝化势直接显著影响土壤N2O通量，而微生物生物量磷(MBP)和增温则通过直接影响反硝化势来间接影响土壤N2O通量.温度可能是影响亚热带森林土壤N2O通量的主要驱动因素，全球变暖可能会减少亚热带森林土壤的N2O排放.
Keywords: N2O flux; denitrification potential; precipitation exclusion; subtropics; warming.