Luo Y, Wan S, Hui D, Wallace L L
Department of Botany and Microbiology, University of Oklahoma, Norman, Oklahoma 73019, USA.
Nature. 2001 Oct 11;413(6856):622-5. doi: 10.1038/35098065.
The latest report by the Intergovernmental Panel on Climate Change (IPCC) predicts a 1.4-5.8 degrees C average increase in the global surface temperature over the period 1990 to 2100 (ref. 1). These estimates of future warming are greater than earlier projections, which is partly due to incorporation of a positive feedback. This feedback results from further release of greenhouse gases from terrestrial ecosystems in response to climatic warming. The feedback mechanism is usually based on the assumption that observed sensitivity of soil respiration to temperature under current climate conditions would hold in a warmer climate. However, this assumption has not been carefully examined. We have therefore conducted an experiment in a tall grass prairie ecosystem in the US Great Plains to study the response of soil respiration (the sum of root and heterotrophic respiration) to artificial warming of about 2 degrees C. Our observations indicate that the temperature sensitivity of soil respiration decreases--or acclimatizes--under warming and that the acclimatization is greater at high temperatures. This acclimatization of soil respiration to warming may therefore weaken the positive feedback between the terrestrial carbon cycle and climate.
政府间气候变化专门委员会（IPCC）的最新报告预测，在1990年至2100年期间，全球地表温度将平均升高1.4 - 5.8摄氏度（参考文献1）。这些对未来变暖的估计高于早期预测，部分原因是纳入了一种正反馈。这种反馈源于陆地生态系统因气候变暖而进一步释放温室气体。反馈机制通常基于这样的假设：在当前气候条件下观察到的土壤呼吸对温度的敏感性在气候变暖时依然成立。然而，这一假设尚未得到仔细检验。因此，我们在美国大平原的一个高草草原生态系统中进行了一项实验，以研究土壤呼吸（根系呼吸和异养呼吸之和）对约2摄氏度的人工升温的响应。我们的观察结果表明，土壤呼吸的温度敏感性在变暖时会降低——或者说适应——并且在高温下这种适应更为明显。因此，土壤呼吸对变暖的这种适应可能会削弱陆地碳循环与气候之间的正反馈。
