土壤异养呼吸对气候变暖的反馈

土壤异养呼吸对气候变暖的反馈是影响陆地生态系统C预算的重要机制.绝大多数研究表明,土壤异养呼吸与未来气候变暖将构成危险的正反馈环.由于土壤有机C分解的温度敏感性问题,学术界仍有争议,对正反馈强度的准确量化尚需一个过程.少量研究表明,土壤异养呼吸对气候变暖的反馈不明显.诸多研究还发现土壤异养呼吸对气候变暖的适应现象,主要有水分限制假说、微生物适应假说和底物限制假说来解释适应现象;这种适应性将降低正反馈的影响强度.未来应重点开展以下4方面的研究:(1)加强惰性土壤有机C温度敏感性的研究;(2)深入探讨微生物对气候变暖的适应性;(3)量化土壤异养呼吸对气候变暖的反馈强度;(4)加强对多因子交互影响的研究.

Feedbacks of Soil Heterotrophic Respiration to Global Warming

The acceleration of global warming due to soil heterotrophic respiration(SHR)feedbacks may he potentially important mechanisms which have significant effects on global carbon budgets.Most of studies suggest that SHR rates exponentially increase with increasing temperature,thus providing a dangerous posi- tive feedback to global warming.However,it is difficult to estimate how strong the positive feedback is be- cause there is no consensus on the temperature sensitivity of decomposition of different soil organic matter fractions now.Moreover,SHR could acclimate to high temperature,which may mitigate the positive feed- back effects.By now,it has involved three hypotheses including the soil water constraint hypothesis,the mi- croorganism acclimation hypothesis and the respiratory substrate constraint hypothesis to explain the phe- nomena of acclimation.Finally,four research priorities are provided to enhance the understanding of feed- backs of SHR to global warming.