Progress in the Effects of Warming on Soil N2O and CH4 Emission and the Underlying Microbial Mechanisms

Global warming has received widespread concern. The increasing concentration of greenhouse gases (GHG) is one of the major factors contributing to global warming. Soil is a major source of GHG. Global warming could feed back on soil GHG emission. Warming influences the growth of plants, animals, microbes and their interactions, as well as the cycling of soil matters (especially nitrogen and carbon). Consequently, warming has the potential to affect soil GHG emission. We summarized the effects of warming on soil N2O, and CH4 emissions and the underlying mechanisms. In general, warming increased the emission of these two greenhouse gases, which are mainly related to the effects of temperature on the abundance and composition of ammonia oxidizing bacteria, denitrification functional genes, methane-producing bacteria and methane-oxidizing bacteria. Soil GHG emissions are affected by plant species characteristics, nutrient uptake and community composition, as well as soil nutrient element content, water content, pH and other physical and chemical properties. Further studies are needed to elucidate the microbial mechanisms of GHG emission. In addition, various warming patterns should be considered in the study of GHG emissions, and more attention should be paid on the interactive effects between warming and other environmental factors. It will provide solid theoretical basis for the prediction of global climate change and GHG emissions.