School of Forestry and Environmental Studies, Yale University, New Haven, CT, USA.
Department of Plant and Soil Science, University of Kentucky, Lexington, KY, USA.
Nat Ecol Evol. 2019 Jan 14;3(2):223-231. doi: 10.1038/s41559-018-0771-4.
Climate warming may stimulate microbial metabolism of soil carbon, causing a carbon-cycle-climate feedback whereby carbon is redistributed from the soil to atmospheric CO. The magnitude of this feedback is uncertain, in part because warming-induced shifts in microbial physiology and/or community composition could retard or accelerate soil carbon losses. Here, we measure microbial respiration rates for soils collected from 22 sites in each of 3 years, at locations spanning boreal to tropical climates. Respiration was measured in the laboratory with standard temperatures, moisture and excess carbon substrate, to allow physiological and community effects to be detected independent of the influence of these abiotic controls. Patterns in respiration for soils collected across the climate gradient are consistent with evolutionary theory on physiological responses that compensate for positive effects of temperature on metabolism. Respiration rates per unit microbial biomass were as much as 2.6 times higher for soils sampled from sites with a mean annual temperature of -2.0 versus 21.7 °C. Subsequent 100-d incubations suggested differences in the plasticity of the thermal response among microbial communities, with communities sampled from sites with higher mean annual temperature having a more plastic response. Our findings are consistent with adaptive metabolic responses to contrasting thermal regimes that are also observed in plants and animals. These results may help build confidence in soil-carbon-climate feedback projections by improving understanding of microbial processes represented in biogeochemical models.
气候变暖可能会刺激土壤碳的微生物代谢，导致碳循环-气候反馈，从而将碳从土壤重新分配到大气 CO 中。这种反馈的幅度是不确定的，部分原因是变暖引起的微生物生理学和/或群落组成的变化可能会减缓或加速土壤碳损失。在这里，我们在 3 年内从每个地点的 22 个地点收集土壤，并在跨越北方到热带气候的位置进行测量。在实验室中使用标准温度、湿度和过量的碳底物来测量微生物呼吸率，以使生理和群落效应能够独立于这些非生物控制的影响而被检测到。在气候梯度上收集的土壤的呼吸模式与生理反应的进化理论一致，该理论补偿了温度对新陈代谢的积极影响。与平均年气温为-2.0 摄氏度与 21.7°C 的地点采集的土壤相比，单位微生物生物量的呼吸率高 2.6 倍。随后的 100 天培养表明，微生物群落之间的热响应的可塑性存在差异，年平均温度较高的地点采集的群落具有更具可塑性的响应。我们的发现与植物和动物中观察到的对比热区的适应性代谢反应一致。这些结果可能有助于通过提高对生物地球化学模型中微生物过程的理解来增强对土壤碳-气候反馈预测的信心。
