Global pattern of temperature sensitivity of soil heterotrophic respiration (Q10) and its implications for carbon‐climate feedback
Global pattern of temperature sensitivity of soil heterotrophic respiration (Q10) and its implications for carbon‐climate feedback
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DOI：
10.1029/2008jg000850
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发表时间：
2009-06
影响因子：
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通讯作者：
Tao Zhou;P. Shi;D. Hui;Yiqi Luo
中科院分区：
文献类型：
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作者：
Tao Zhou;P. Shi;D. Hui;Yiqi Luo
土壤呼吸温度敏感性（Q10）是模拟全球变暖对生态系统碳释放影响的重要参数。土壤呼吸的实验研究普遍表明，辅酶Q10具有较高的空间异质性。然而，大多数生物地球化学模式在预测未来气候变化时仍然使用全球恒定的Q10，部分原因是没有推导出Q10值的空间格局。在这项研究中，我们通过将土壤有机碳数据同化到一个基于过程的陆地碳模型（Carnegie-Ames-Stanford Approach模型）中，以1°× 1°的空间分辨率进行了逆分析，以检索空间异质性Q10值的全球格局。然后，将Q10的估计值纳入土壤呼吸模型，以评估其对土壤（即总土壤呼吸等于微生物和根呼吸）和微生物分解（即异养呼吸）的全球呼吸性碳释放的影响。结果表明，优化后的辅酶10值具有空间异质性，且随环境因子的变化而变化。总体上，高纬地区Q10值偏高。不同生物群系的Q10平均值为1.43 ~ 2.03，冻土带最高，沙漠最低。将空间异质性Q10值纳入全球土壤呼吸模型时，模拟土壤呼吸对气候变暖的反馈强度为3.21 Pg C°C−1，比全球不变Q10值高约40%。模拟的异养呼吸的反馈强度为2.26 Pg C°C−1，比全局不变的Q10值高约25%。总体而言，土壤碳释放对气候变暖的反馈强度不仅取决于全球Q10平均值的大小，还取决于它们的空间变异性。
[1] Temperature sensitivity of soil respiration (Q10) is an important parameter in modeling effects of global warming on ecosystem carbon release. Experimental studies of soil respiration have ubiquitously indicated that Q10 has high spatial heterogeneity. However, most biogeochemical models still use a globally constant Q10 in projecting future climate change, partly because no spatial pattern of Q10 values has been derived. In this study, we conducted an inverse analysis to retrieve a global pattern of spatially heterogeneous Q10 values by assimilating data of soil organic carbon into a process-based terrestrial carbon model (Carnegie-Ames-Stanford Approach model) at spatial resolution of 1° by 1°. The estimated Q10 values were, in turn, incorporated into soil respiration models to evaluate their impacts on global respiratory carbon release from soil (i.e., total soil respiration is equal to microbial and root respiration) and from microbial decomposition (i.e., heterotrophic respiration). Our results show that the optimized Q10 values are spatially heterogeneous and vary with environmental factors. In general, Q10 value tends to be high in the high-latitudinal regions. The mean Q10 values for different biomes range from 1.43 to 2.03, with the highest value in tundra and the lowest value in deserts. When spatially heterogeneous Q10 values were incorporated into global soil respiration models, simulated soil respiration has a feedback intensity of 3.21 Pg C °C−1 to climate warming, which is approximately 40% higher than that with a globally invariant Q10 value. The modeled heterotrophic respiration has a feedback intensity of 2.26 Pg C °C−1, about 25% higher than that derived from a globally invariant Q10 value. Overall, the feedback intensity of soil carbon release to climate warming depends not only on the magnitude of a global mean of Q10 values but also their spatial variability.