Greenhouse gas fluxes response to autumn freeze-thaw period in continuous permafrost region of Daxing'an Mountains, Northeast China.

Abstract

Autumn freeze-thaw period significantly influenced the soil temperature, moisture, nutrients, and then affected the structure and diversity of soil microbial community. In this paper, three types of wetlands in the permafrost region of Daxing'an Mountains were selected to investigate the greenhouse gas fluxes during the autumn freeze-thaw period. CO2, CH4, and N2O fluxes during the autumn freeze-thaw period ranged from 24.76 to 124.06mgm-2h-1, - 249.10 to 968.87μgm-2h-1, and - 4.21 to 12.86μgm-2h-1. CO2 fluxes were mainly influenced by soil temperature and moisture. CH4 fluxes were mainly influenced by temperature and soil moisture. And N2O fluxes were significantly affected by temperature, soil moisture, ammonia nitrogen, and nitrate nitrogen. Environmental factors could explain 64-73.2%, 51-85.4%, and 60.3-93.3% of temporal variation of CO2, CH4, and N2O fluxes, respectively. Comparing different wetlands, the soil temperature was the significant factor to affect the CH4 flux. The global warming potentials during the autumn freeze-thaw period ranged from 717.83 to 775.57kg CO2-eq hm-2.