Effects of ant nesting on seasonal dynamics of soil N2O emission in a secondary tropical forest.

ABSTRACT

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.