The effect of warming is stronger in arctic and sub-arctic latitudes than in temperate and tropical zones. We studied soil metabolomes along two soil-warming gradients (0 to +15 °C). One temperature gradient has been present for at least 50 years and possibly even centuries (long-term treatment), while the second gradient was created after a shallow crustal earthquake in 2008 (short-term treatment). Soil metabolomes at the two sites responded differently to warming. At the short-term warmed site, warming of ≤+3 °C already shifted soil metabolomic profiles relative to the controls, whereas at the long-term warmed site the soil metabolome only shifted at temperatures ≥+5 °C. Saccharides and amino acids, primary metabolites involved in protective mechanisms against heat, were the main compounds accumulated at the highest soil warming levels. Some secondary metabolites associated with a broad spectrum of stressors, like phenolic acids and terpenes, were also up-regulated. Across the IPCC scenario's, most climate models predict a substantial rise in mean annual temperature of up to 8 °C in the Arctic region by the end of the 21st century. Our results suggest that temperature increases of ≥+5 °C would permanently alter soil metabolomic profile, whereas smaller temperature increases of (≤+3 °C) would affect soil metabolome profile transiently, not permanently.

在北极和亚北极地区，变暖的影响要比在温带和热带地区强。我们研究了沿两个土壤升温梯度（0至+15°C）的土壤代谢组。一个温度梯度已经存在了至少50年，甚至可能是几个世纪（长期处理），而第二个温度梯度是在2008年的浅层地壳地震（短期处理）之后产生的。两个地点的土壤代谢组对变暖的反应不同。在短期变暖的地点，相对于对照，≤+ 3°C的变暖已经改变了土壤代谢组学特征，而在长期变暖的地点，土壤代谢组仅在≥+ 5°C的温度下才发生变化。糖和氨基酸是参与热保护机制的主要代谢产物，是在最高土壤升温水平下积累的主要化合物。与广泛的应激源相关的一些次生代谢产物，如酚酸和萜烯，也被上调。在IPCC情景中，大多数气候模型都预测，到21世纪末，北极地区的年平均气温将大幅上升，最高可达8°C。我们的结果表明，≥+ 5°C的温度升高会永久改变土壤代谢组学特征，而较小的温度升高（≤+ 3°C）会暂时而非永久性地影响土壤代谢组学特征。