Soil-carbon response to warming dependent on microbial physiology
Soil-carbon response to warming dependent on microbial physiology
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DOI：
10.1038/ngeo846
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发表时间：
2010-05-01
影响因子：
18.3
通讯作者：
Bradford, Mark A.
中科院分区：
文献类型：
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作者：
Allison, Steven D.;Wallenstein, Matthew D.;Bradford, Mark A.
大多数生态系统模型预测，气候变暖将刺激土壤碳的微生物分解，对全球气温上升产生正反馈(1,2)。尽管现场实验记录了气候变暖导致土壤中二氧化碳损失的最初增加，但与这些预测一致，土壤中二氧化碳的损失往往会在几年内下降到控制水平(3-5)。这种衰减反应可能是由于微生物生理特性随温度升高而发生的变化造成的，例如分配给生长的同化碳比例的下降，称为碳利用效率(6)。在这里，我们使用微生物酶模型来探索这些机制，以模拟土壤碳对变暖 5 摄氏度的反应。我们发现，微生物生物量和降解酶的下降可以解释观察到的土壤碳排放因变暖而减少的现象。具体来说，碳利用效率的降低限制了微生物分解者的生物量，并减少了土壤碳的损失。然而，微生物的适应或微生物群落的变化可能导致碳利用效率的向上调整，抵消微生物生物量的下降并加速土壤碳流失。我们的结论是，土壤碳对气候变暖的响应取决于土壤微生物利用碳的效率。
Most ecosystem models predict that climate warming will stimulate microbial decomposition of soil carbon, producing a positive feedback to rising global temperatures(1,2). Although field experiments document an initial increase in the loss of CO2 from soils in response to warming, in line with these predictions, the carbon dioxide loss from soils tends to decline to control levels within a few years(3-5). This attenuation response could result from changes in microbial physiological properties with increasing temperature, such as a decline in the fraction of assimilated carbon that is allocated to growth, termed carbon-use efficiency(6). Here we explore these mechanisms using a microbial-enzyme model to simulate the responses of soil carbon to warming by 5 degrees C. We find that declines in microbial biomass and degradative enzymes can explain the observed attenuation of soil-carbon emissions in response to warming. Specifically, reduced carbon-use efficiency limits the biomass of microbial decomposers and mitigates the loss of soil carbon. However, microbial adaptation or a change in microbial communities could lead to an upward adjustment of the efficiency of carbon use, counteracting the decline in microbial biomass and accelerating soil-carbon loss. We conclude that the soil-carbon response to climate warming depends on the efficiency of soil microbes in using carbon.