Mechanism of greenhouse gases fluxes from soil and its controlling factors: A review

Soil is a major source of greenhouse gases (GHG), such as carbon dioxide (CO2), methane (CH4) and nitrous oxide (N2O), which are mainly resulted from root respiration, microbial respiration and soil fauna respiration. Study on the mechanism of GHG generation and influencing factors is one of the major concerns on global carbon and nitrogen cycle. A number of factors, including soil temperature, soil water content (SWC), soil organic matter (SOM), pH, Soil redox potential (Eh), soil texture, etc. contribute a lot to GHG fluxes by influencing soil microbial biomass, physiological and biochemical processes. Among these, soil temperature, SWC and SOM are identified as the main parameters in relation to soil GHG emission. Furthermore, local climate situation, soil management, land-use changes and vegetation cover also play a role in GHG emission by affecting microbial activity and substrate quality. The review highlights recent work on the mechanism of GHG fluxes, key factors, diurnal and seasonal variation. We suggest that future research should focus on dynamics of GHG fluxes within micro-environment, efflux modeling and its scaling-up, carbon sequestration and carbon mitigation in terrestrial ecosystem and coastal ecosystem, especially for plantation and farmland in China.