模拟增温对土壤呼吸影响机制的研究进展与展望

Research and prospects for response mechanisms of soil respiration to experimental warming

土壤呼吸是土壤碳库向大气碳库输入的主要途径,而温度升高会影响土壤呼吸从而改变全球碳平衡.据预测在21世纪末,全球平均地表温度将升高0.3~4.8℃,因此野外自然条件下的模拟增温试验对土壤呼吸的影响是全球变化研究的热点之一.本文综述了不同时空格局下土壤呼吸对模拟增温的响应特征,指出短期增温能提高土壤呼吸,而长期增温下无统一规律,并且不同生态系统之间也存在差异;重点讨论了模拟增温对土壤呼吸的影响机制,指出增温能直接影响土壤呼吸,同时增温也能通过影响土壤水分、盐分、土壤理化性质等环境因子以及光合作用、凋落物等生物因子对土壤呼吸产生间接影响;另外,分析了土壤呼吸对增温产生适应性的形成机制,主要包括微生物、根、酶的温度适应性、水分限制、氮素过量以及呼吸底物限制.在此基础上对今后的研究方向加以展望：加强根际微生态系统的研究;重点研究不对称增温下土壤呼吸的特征及机制;关注典型物候期和不同季节典型天气土壤呼吸的测定;构建土壤呼吸响应模拟增温试验的研究网络,进行联网试验.

Soil respiration（Rs） is the main efflux of carbon pool from soil to atmosphere.Increasing Rscaused by rising temperature can result in significant change in the global carbon balance.Global mean land-surface temperature is predicted to rise by 0.3-4.8 ℃ by the end of 21 century.Therefore,how Rsresponds to simulated experimental warming in the natural field is one of the critical issues in global change research.Here,we reviewed the response characteristics of Rsto simulated warming under different temporal and spatial patterns.Experimental warming can increase Rsat the short time scale,but there was no uniform law in the long-term warming experiments,and there were differences among different ecosystems.This paper also reviewed the mechanism underlying the simulated warming response of Rs.Warming can directly affect Rs,and warming can also affect Rs indirectly by affecting the environmental factors（e.g.,soil water,soil salt,soil physical and chemical properties）,and the regulation of biological factors（e.g.,photosynthesis,litter decomposition）.Furthermore,we synthesized the formation mechanism of adaptability of Rsto warming,including adaptability of microbes,roots and enzymes to warming,water restriction,and regulation by excessive nitrogen and the substrate supply.Finally,the future research directions were proposed.The study of micro-ecosystem of rhizosphere,characteristics and mechanism of Rsunder asymmetric warming should be strengthened.Also,more attention should be paid to the measurement of Rsin typical phenological periods and typical weather in different seasons.The research network of Rsresponse to simulated warming should be constructed for networking test.