The response of soil microbial activity to climate warming has been predicted to have a large destabilising effect on the carbon cycle. However, the nature of this feedback remains poorly understood, especially in tropical ecosystems and across annual to decadal timescales. We studied the response of bacterial community growth to 2 and 11 years of altered temperature regimes, by translocating soil across an elevation gradient in the tropical Andes. Soil cores were reciprocally translocated among five sites across 3 km in elevation, where mean annual temperature (MAT) ranged from 26.4 to 6.5°C. The bacterial community growth response to temperature was estimated using a temperature Sensitivity Index (SI): the log-ratio of growth determined by leucine incorporation at 35°C: 4°C. Bacterial communities from soil translocated to their original site (controls) had a growth response assumed to be ‘adapted’ to the original MAT. Translocating soil downslope (warming) resulted in an increased SI relative to their original growth response, and vice versa under cooling, indicating community-level adaptation over the incubation period to the altered MAT. The average level of adaptation (i.e., the extent to which SI converged on the control values) was 77% after 2 years, and was complete after 11 years. The adaptive response was faster when soil was warmed rather than cooled: instances of complete adaptation of SI occurred in soils after 2 years when warmed, but only after 11 years when they were cooled. Taken together, our results show that the majority of the growth adaptation to warming by the bacterial community occurs rapidly, within 2 years, whilst growth adaptation to cooling occurs within a decade. Our analysis demonstrates rapid warm-adaptation of bacterial community growth, with potential consequences for the temperature sensitivity of soil carbon cycling in response to future climate warming.

据预测，土壤微生物活动对气候变暖的响应会对碳循环产生很大的破坏作用。但是，这种反馈的性质仍然知之甚少，尤其是在热带生态系统中以及跨年度到十年的时间尺度。我们通过使土壤跨过热带安第斯山脉的海拔梯度转移，研究了细菌群落生长对2年和11年温度变化的响应。土壤核心在海拔3 km的五个地点之间相互移位，平均年温度（MAT）范围为26.4至6.5°C。使用温度敏感性指数（SI）估算细菌群落对温度的生长响应：通过在35°C：4°C掺入亮氨酸确定的生长对数比。从土壤转移到原始地点（对照）的细菌群落的生长响应被认为是“适应”原始MAT的。相对于其原始生长响应，移位土壤下坡（变暖）导致SI增大，并且反之亦然在冷却条件下，表明潜伏期期间社区水平适应了改变的MAT。2年后的平均适应水平（即SI收敛于控制值的程度）为77％，而11年后才达到完全。当土壤加热而不是冷却时，适应性反应更快：SI完全适应的情况发生在土壤加热2年后，但仅在冷却11年后才发生。综上所述，我们的结果表明，细菌群落对变暖的大多数生长适应在2年内迅速发生，而对冷却的生长适应在10年内发生。我们的分析表明，细菌群落生长迅速变暖，