Carbon respiration from subsurface peat accelerated by climate warming in the subarctic
Carbon respiration from subsurface peat accelerated by climate warming in the subarctic
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DOI：
10.1038/nature08216
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发表时间：
2009-07-30
期刊：
影响因子：
64.8
通讯作者：
Aerts, Rien
中科院分区：
文献类型：
--
作者：
Dorrepaal, Ellen;Toet, Sylvia;Aerts, Rien
目前对未来气候预测的最大不确定性之一是陆地碳循环和气候之间的反馈（1）。北方泥炭地含有世界土壤有机碳的三分之一，相当于大气中碳含量的一半以上（2）。气候变暖通过数百年至数千年的厚泥炭沉积物的呼吸作用增强而导致二氧化碳（CO（2））排放加速，这可能形成一个强有力的正碳循环-气候反馈。然而，泥炭地碳的长期温度敏感性，特别是在深度，仍然是不确定的，因为实地研究的持续时间短或相关性（3-5），以及与地面以下原位或实验室培养期间呼吸测量相关的干扰（6，7）。在这里，我们结合联合收割机的非干扰原位测量的CO（2）呼吸速率和同位素（13）C）组成的呼吸CO（2）在两个全生态系统的气候操纵实验在亚北极泥炭地。我们发现，大约1摄氏度的变暖使总的生态系统呼吸速率在春季平均增加了60%，在夏季增加了52%，这种影响至少持续了8年。虽然变暖刺激短期（植物相关）和长期（泥炭土相关）的碳呼吸过程，我们发现，至少69%的呼吸速率的增加来自泥炭中的碳对底部（25-50厘米）的活动层以上的冻土。因此，气候变暖加速了泥炭地广泛的地下碳库的呼吸作用，其程度比以前认为的要大得多（6，7）。假设我们从一个单一的网站的数据是直接响应全球范围内的北方泥炭地土壤变暖的指示，我们估计，气候变暖约1摄氏度，在未来几十年内可能会导致每年38-100兆吨C的异养呼吸全球增加。我们的研究结果表明，储存在北方泥炭地的碳对全球气候系统有着巨大的、持久的正反馈作用。
Among the largest uncertainties in current projections of future climate is the feedback between the terrestrial carbon cycle and climate(1). Northern peatlands contain one-third of the world's soil organic carbon, equivalent to more than half the amount of carbon in the atmosphere(2). Climate-warming-induced acceleration of carbon dioxide (CO(2)) emissions through enhanced respiration of thick peat deposits, centuries to millennia old, may form a strong positive carbon cycle-climate feedback. The long-term temperature sensitivity of carbon in peatlands, especially at depth, remains uncertain, however, because of the short duration or correlative nature of field studies(3-5) and the disturbance associated with respiration measurements below the surface in situ or during laboratory incubations(6,7). Here we combine non-disturbing in situ measurements of CO(2) respiration rates and isotopic ((13)C) composition of respired CO(2) in two whole-ecosystem climate-manipulation experiments in a subarctic peatland. We show that approximately 1 degrees C warming accelerated total ecosystem respiration rates on average by 60% in spring and by 52% in summer and that this effect was sustained for at least eight years. While warming stimulated both short-term (plant-related) and longer-term (peat soil-related) carbon respiration processes, we find that at least 69% of the increase in respiration rate originated from carbon in peat towards the bottom (25-50 cm) of the active layer above the permafrost. Climate warming therefore accelerates respiration of the extensive, subsurface carbon reservoirs in peatlands to a much larger extent than was previously thought(6,7). Assuming that our data from a single site are indicative of the direct response to warming of northern peatland soils on a global scale, we estimate that climate warming of about 1 degrees C over the next few decades could induce a global increase in heterotrophic respiration of 38-100 megatonnes of C per year. Our findings suggest a large, long-lasting, positive feedback of carbon stored in northern peatlands to the global climate system.