Soil microorganisms are the major players controlling the soil carbon (C) and nutrient cycling, however the extent to which the functional properties of soil microorganisms will alter with climate change in mountain grasslands is still unclear. To simulate future climatic conditions (higher temperature and less precipitation), intact plant-soil mesocosms of three mountain grassland sites, Esterberg (1260 m a.s.l.), Graswang (860 m a.s.l.), and Fendt 550 m a.s.l.), were translocated to the lowest elevation Bayreuth (350 m a.s.l.). After two years of translocation to warmer and drier environments, specific growth rates of soil microorganisms were 25 % slower than those at higher elevations. This indicated a shift towards to slow-growing -strategists with increasing temperature and decreasing soil moisture, presumably attributed to the depletion of available C for microorganisms. Simultaneously, higher activity and faster substrate turnover time of C-acquiring enzymes in the warmer and drier soils implied a stronger C rather nutrient limitation. This was supported by the increased vector length, which was induced by decreased dissolved organic compounds at lower elevation. In contrast, microorganisms were limited by nitrogen (N) at higher elevation because of the stronger competition for N between plants and microorganisms. In short, translocated microorganisms increased their active fraction, enzymatic activity and altered enzyme systems but decreased specific growth rates. This indicated that soil microbial community adjusted to the changing climate resulting in faster substrate turnover, and in turn caused 15 % reduction in soil C content from Esterberg to Bayreuth. We therefore conclude that climate warming in combination with decreased precipitation increases microbial activity, leads to shifts in microbial life strategies and induces alterations in microbial nutrient limitation, i.e. shift from N- to C and P co-limitation with translocation to lower elevation sites. This in turn, is likely to result in C losses of mountain grassland soils under future climate change, which will amplify negative impacts on global warming.

中文翻译：

---

欧洲山地草原微生物生长和酶活性对气候变化的响应：易位研究

土壤微生物是控制土壤碳（C）和养分循环的主要参与者，但山地草原土壤微生物的功能特性将在多大程度上随气候变化而改变仍不清楚。为了模拟未来的气候条件（更高的温度和更少的降水），三个山地草原地点（Esterberg（1260 m asl）、Graswang（860 m asl）和 Fendt 550 m asl）的完整植物-土壤中生态系统被转移到最低点拜罗伊特海拔 (350 m asl)。在迁移到更温暖、更干燥的环境两年后，土壤微生物的特定生长速度比高海拔地区的土壤微生物的生长速度慢了 25%。这表明随着温度升高和土壤湿度降低，向缓慢生长的策略转变，这可能归因于微生物可用碳的耗尽。同时，在温暖和干燥的土壤中，碳获取酶的较高活性和更快的底物周转时间意味着更强的碳而不是养分限制。这得到了矢量长度增加的支持，这是由较低海拔处溶解的有机化合物减少引起的。相比之下，在较高海拔地区，由于植物和微生物之间对氮的竞争更加激烈，微生物受到氮（N）的限制。简而言之，移位的微生物增加了它们的活性分数、酶活性并改变了酶系统，但降低了比生长率。这表明土壤微生物群落适应了气候变化，导致基质周转更快，进而导致从埃斯特贝格到拜罗伊特的土壤碳含量减少了 15%。因此，我们得出的结论是，气候变暖与降水减少相结合，增加了微生物活动，导致微生物生活策略的转变，并引起微生物营养限制的改变，即从N-到C和P共同限制的转变，并易位到海拔较低的地点。这反过来很可能导致未来气候变化下山地草原土壤的碳损失，从而放大对全球变暖的负面影响。