Luláková Petra, Perez-Mon Carla, Šantrůčková Hana, Ruethi Joel, Frey Beat
Forest Soils and Biogeochemistry, Swiss Federal Institute for Forest, Snow and Landscape Research WSL, Birmensdorf, Switzerland.
Faculty of Science, University of South Bohemia, České Budějovice, Czechia.
Front Microbiol. 2019 Apr 3;10:668. doi: 10.3389/fmicb.2019.00668. eCollection 2019.
The response of microbial communities to the predicted rising temperatures in alpine regions might be an important part of the ability of these ecosystems to deal with climate change. Soil microbial communities might be significantly affected by elevated temperatures, which influence the functioning of soils within high-alpine ecosystems. To evaluate the potential of the permafrost microbiome to adapt to short-term moderate and extreme warming, we set up an incubation experiment with permafrost and active soil layers from northern and southern slopes of a high-alpine mountain ridge on Muot da Barba Peider in the Swiss Alps. Soils were acclimated to increasing temperatures (4-40°C) for 26 days before being exposed to a heat shock treatment of 40°C for 4 days. Alpha-diversity in all soils increased slightly under gradual warming, from 4 to 25°C, but then dropped considerably at 40°C. Similarly, heat shock induced strong changes in microbial community structures and functioning in the active layer of soils from both northern and southern slope aspects. In contrast, permafrost soils showed only minor changes in their microbial community structures and no changes in their functioning, except regarding specific respiration activity. Shifts in microbial community structures with increasing temperature were significantly more pronounced for bacteria than for fungi, regardless of the soil origin, suggesting higher resistance of high-alpine fungi to short-term warming. Firmicutes, mainly represented by and Alicyclobacillaceae OTUs, increased strongly at 40°C in active layer soils, reaching almost 50% of the total abundance. In contrast, Saccharibacteria decreased significantly with increasing temperature across all soil samples. Overall, our study highlights the divergent responses of fungal and bacterial communities to increased temperature. Fungi were highly resistant to increased temperatures compared to bacteria, and permafrost communities showed surprisingly low response to rising temperature. The unique responses were related to both site aspect and soil origin indicating that distinct differences within high-alpine soils may be driven by substrate limitation and legacy effects of soil temperatures at the field site.
微生物群落对高山地区预计上升温度的响应，可能是这些生态系统应对气候变化能力的重要组成部分。土壤微生物群落可能会受到温度升高的显著影响，而这会影响高海拔生态系统中土壤的功能。为了评估多年冻土微生物群落适应短期适度和极端变暖的潜力，我们在瑞士阿尔卑斯山穆特达巴尔巴佩德的一座高海拔山脊的北坡和南坡设置了一个包含多年冻土和活性土壤层的培养实验。土壤在温度逐渐升高（4 - 40°C）的条件下适应26天，然后接受40°C的热激处理4天。在逐渐升温至4至25°C的过程中，所有土壤中的α多样性略有增加，但在40°C时大幅下降。同样，热激导致北坡和南坡土壤活性层的微生物群落结构和功能发生强烈变化。相比之下，多年冻土土壤的微生物群落结构仅发生微小变化，其功能除特定呼吸活性外无变化。无论土壤来源如何，随着温度升高，细菌的微生物群落结构变化比真菌明显更显著，这表明高海拔真菌对短期变暖具有更高的抗性。厚壁菌门主要由芽孢杆菌属和嗜酸耐热芽孢杆菌科的操作分类单元代表，在活性层土壤中于40°C时强烈增加，几乎达到总丰度的50%。相反，在所有土壤样本中，糖细菌随着温度升高显著减少。总体而言，我们的研究突出了真菌和细菌群落对温度升高的不同响应。与细菌相比，真菌对温度升高具有高度抗性，并且多年冻土群落对温度升高的响应出人意料地低。这些独特的响应与坡向和土壤来源都有关，表明高海拔土壤内部的明显差异可能由底物限制和田间土壤温度的遗留效应驱动。
