降雨引起的干湿交替对土壤呼吸的影响:进展与展望

Soil respiration is an important part of the carbon cycle in terrestrial ecosystems. The changes of soil respiration caused by rainfall directly affect global carbon balance. Therefore, it is important to explore the mechanism underlying the effects of rainfall on soil respiration, which is necessary for understanding the carbon cycle and carbon budget of terrestrial ecosystems. Here, we summarized the research progress on the mechanism of drying-wetting cycle caused by rainfall on soil respiration. Soil respiration can be promoted at intermediate moisture conditions, but suppressed in both wetter and drier conditions. Dryingwetting cycles caused by rainfall affect soil respiration by changing soil moisture. On one hand, under the condition of drought, dryingwetting cycle caused by rainfall improve soil respiration rate by shortterm replacement of CO2 in soil, increases of soil microbial respiratory substrate, increases of microbial activity, and enhancement of litter decomposition. On the other hand, soils with high moisture could reach saturation more quickly or even be waterlogged after a short period of rainfall. Dryingwetting cycle caused by rainfall can significantly suppress soil respiration through restricting the entrance of O2 to the soil, forming an anaerobic environment, and inhibiting microbial and root respiration. In addition, dryingwetting cycle caused by rainfall could significantly inhibit root respiration by flooding part of the plant, reducing plant leaf area and photosynthetic products. In order to accurately estimate the interference of soil respiration on carbon budget of terrestrial ecosystems, future studies on the effects of rainfall on soil respiration should focus on three aspects: (1) microbiological response mechanisms underlying the effects of rainfall on soil respiration; (2) differentiating response mechanisms of soil autotrophic respiration and heterotrophic respiration to rainfall; and (3) modeling the effect of rainfall on soil respiration.