We assessed the seasonal dynamics of N2O emission in ant nests soils in secondary tropical Millettia leptobotrya forest of Xishuangbanna by using the static chamber-gas chromatography method, and determined the lin-kages between ant-mediated changes in soil properties (e.g., carbon pool, nitrogen pool, and temperature and humidity) and N2O emission. The results showed that ant nesting significantly affected soil N2O emission. The ave-rage soil N2O emission (0.67 mg·m-2·h-1) in ant nests was 40.2% higher than that in the control (0.48 mg·m-2·h-1). N2O emission in ant nests and the control showed substantial seasonal variation, with higher rate in June (0.90 and 0.83 mg·m-2·h-1, respectively) than that in March (0.38 and 0.19 mg·m-2·h-1, respectively). Ant nesting significantly increased the values (7.1%-74.1%) of moisture, temperature, organic carbon, total nitrogen, hydrolytic nitrogen, ammonium nitrogen, nitrate nitrogen, and microbial biomass carbon, but decreased pH (9.9%) compared with the control. Results of structural equation model showed that soil N2O emission was promoted by soil C and N pool, temperature, and humidity, but was inhibited by soil pH. The explained extents of soil nitrogen pool, carbon pool, temperature and humidity, and pH for N2O emission changes were 37.2%, 27.7%, 22.9% and 9.4%, respectively. Therefore, ant nesting regulated N2O emission dynamics by changing nitrification and denitrification substrates (e.g., nitrate and ammoniacal nitrogen), carbon pool, and micro-habitat (temperature and moisture) of soil in the secondary tropical forest.
采用静态箱-气相色谱法,对西双版纳热带次生林崖豆藤群落中的蚁巢土壤N2O排放通量的季节动态进行定位研究,分析蚂蚁筑巢引起土壤碳氮库及温湿度等土壤性质变化对N2O排放的影响特征。结果表明: 蚂蚁筑巢显著影响热带森林土壤N2O排放,蚁巢土壤N2O排放通量(0.67 mg·m-2·h-1)显著高于非蚁巢土壤(0.48 mg·m-2·h-1),较非蚁巢土壤增加了40.2%;蚁巢与非蚁巢土壤N2O排放通量具有显著的季节变化,6月分别为0.90 和0.83 mg·m-2·h-1,显著高于3月(分别为0.38 和0.19 mg·m-2·h-1);蚂蚁筑巢显著增加了土壤含水率、温度、有机碳、全氮、水解氮、铵态氮、硝态氮和微生物生物量碳,相较于非蚁巢增加了7.1%～74.1%,蚁巢土壤pH相较于非蚁巢土壤降低了9.9%。结构方程结果表明,土壤氮库、碳库和温湿度均对N2O排放通量具有显著促进作用,土壤pH则表现为显著的抑制作用;土壤氮库、碳库、温湿度和pH对N2O排放通量变化的解释量分别为37.2%、27.7%、22.9%和9.4%。蚂蚁筑巢主要通过改变热带次生林土壤硝化与反硝化底物(硝态氮、铵态氮)、碳库含量及微生境(如温湿度)而调控N2O排放动态。.
Keywords: N 2 O emission; Xishuangbanna; ant nesting; soil physicochemical property; tropical forest.