School of Geosciences, University of Edinburgh, Crew Building, Kings Buildings, Edinburgh, EH9 3FF, UK.
Smithsonian Tropical Research Institute, Apartado, 0843-03092, Balboa, Ancon, Republic of Panama.
Ecol Lett. 2019 Nov;22(11):1889-1899. doi: 10.1111/ele.13379. Epub 2019 Sep 6.
Tropical soils contain huge carbon stocks, which climate warming is projected to reduce by stimulating organic matter decomposition, creating a positive feedback that will promote further warming. Models predict that the loss of carbon from warming soils will be mediated by microbial physiology, but no empirical data are available on the response of soil carbon and microbial physiology to warming in tropical forests, which dominate the terrestrial carbon cycle. Here we show that warming caused a considerable loss of soil carbon that was enhanced by associated changes in microbial physiology. By translocating soils across a 3000 m elevation gradient in tropical forest, equivalent to a temperature change of ± 15 °C, we found that soil carbon declined over 5 years by 4% in response to each 1 °C increase in temperature. The total loss of carbon was related to its original quantity and lability, and was enhanced by changes in microbial physiology including increased microbial carbon-use-efficiency, shifts in community composition towards microbial taxa associated with warmer temperatures, and increased activity of hydrolytic enzymes. These findings suggest that microbial feedbacks will cause considerable loss of carbon from tropical forest soils in response to predicted climatic warming this century.
热带土壤中蕴藏着巨大的碳储量，预计气候变暖将通过刺激有机质分解来减少这些储量，从而产生一种促进进一步变暖的正反馈。模型预测，土壤变暖导致的碳损失将受到微生物生理学的调节，但目前还没有关于热带森林土壤碳和微生物生理学对变暖响应的经验数据，而热带森林主导着陆地碳循环。在这里，我们表明，变暖导致了相当大的土壤碳损失，而微生物生理学的相关变化加剧了这一损失。通过在热带森林中跨越 3000 米的海拔梯度进行土壤迁移，相当于温度变化±15°C，我们发现，土壤碳在 5 年内每升高 1°C 就会减少 4%。碳的总损失与它的原始数量和不稳定性有关，并受到微生物生理学变化的增强，包括微生物碳利用效率的增加、与较高温度相关的微生物类群组成的变化以及水解酶活性的增加。这些发现表明，微生物反馈将导致本世纪热带森林土壤中大量的碳损失，以应对预测的气候变暖。
