CO 2 , CH 4 and N 2 O flux changes in degraded grassland soil of Inner Mongolia, China

The main purpose of this study was to explore the dynamic changes of greenhouse gas (GHG) from grasslands under different degradation levels during the growing seasons of Inner Mongolia, China. Grassland degradation is associated with the dynamics of GHG fluxes, e.g., CO 2 , CH 4 and N 2 O fluxes. As one of the global ecological environmental problems, grassland degradation has changed the vegetation productivity as well as the accumulation and decomposition rates of soil organic matter and thus will influence the carbon and nitrogen cycles of ecosystems, which will affect the GHG fluxes between grassland ecosystems and the atmosphere. Therefore, it is necessary to explore how the exchanges of CO 2 , CH 4 and N 2 O fluxes between soil and atmosphere are influenced by the grassland degradation. We measured the fluxes of CO 2 , CH 4 and N 2 O in lightly degraded, moderately degraded and severely degraded grasslands in Inner Mongolia of China during the growing seasons from July to September in 2013 and 2014. The typical semi-arid grassland of Inner Mongolia plays a role as the source of atmospheric CO 2 and N 2 O and the sink for CH 4 . Compared with CO 2 fluxes, N 2 O and CH 4 fluxes were relatively low. The exchange of CO 2 , N 2 O and CH 4 fluxes between the grassland soil and the atmosphere may exclusively depend on the net exchange rate of CO 2 in semi-arid grasslands. The greenhouse gases showed a clear seasonal pattern, with the CO 2 fluxes of –33.63 –386.36 mg/(m•h), CH 4 uptake fluxes of 0.113–0.023 mg/(m•h) and N 2 O fluxes of –1.68 –19.90 μg/(m•h). Grassland degradation significantly influenced CH 4 uptake but had no significant influence on CO 2 and N 2 O emissions. Soil moisture and temperature were positively correlated with CO 2 emissions but had no significant effect on N 2 O fluxes. Soil moisture may be the primary driving factor for CH 4 uptake. The research results can be in help to better understand the impact of grassland degradation on the ecological environment.