Winter temperatures are projected to increase in Central Europe. Subsequently, snow cover will decrease, leading to increased soil temperature variability, with potentially different consequences for soil frost depending on e.g. altitude. Here, we experimentally evaluated the effects of increased winter soil temperature variability on the root associated mycobiome of two plant species (Calluna vulgaris and Holcus lanatus) at two sites in Germany; a colder and wetter upland site with high snow accumulation and a warmer and drier lowland site, with low snow accumulation. Mesocosm monocultures were set-up in spring 2010 at both sites (with soil and plants originating from the lowland site). In the following winter, an experimental warming pulse treatment was initiated by overhead infrared heaters and warming wires at the soil surface for half of the mesocosms at both sites. At the lowland site, the warming treatment resulted in a reduced number of days with soil frost as well as increased the average daily temperature amplitude. Contrary, the treatment caused no changes in these parameters at the upland site, which was in general a much more frost affected site. Soil and plant roots were sampled before and after the following growing season (spring and autumn 2011). High-throughput sequencing was used for profiling of the root-associated fungal (ITS marker) community (mycobiome). Site was found to have a profound effect on the composition of the mycobiome, which at the upland site was dominated by fast growing saprotrophs (Mortierellomycota), and at the lowland site by plant species-specific symbionts (e.g. Rhizoscyphus ericae and Microdochium bolleyi for C. vulgaris and H. lanatus respectively). The transplantation to the colder upland site and the temperature treatment at the warmer lowland site had comparable consequences for the mycobiome, implying that winter climate change resulting in higher temperature variability has large consequences for mycobiome structures regardless of absolute temperature of a given site.

预计中欧冬季气温将升高。随后，积雪将减少，导致土壤温度变异性增加，根据海拔等不同，土壤霜冻可能产生不同的后果。在这里，我们通过实验评估了冬季土壤温度变化增加对两种植物（Calluna vulgaris和Holcus lanatus ）根系相关真菌群落的影响。) 在德国的两个地点；一个寒冷潮湿的高地积雪高，一个温暖干燥的低地积雪少。2010 年春季在两个地点建立了中宇宙单一栽培（土壤和植物来自低地）。在接下来的冬天，在两个地点的一半中宇宙中，通过架空红外加热器和土壤表面的加温线启动了实验性的加温脉冲处理。在低地，变暖处理导致土壤霜冻天数减少，同时日平均温度幅度增加。相反，处理导致高地站点的这些参数没有变化，这通常是一个受霜冻影响更大的站点。在下一个生长季节（2011 年春季和秋季）之前和之后对土壤和植物根系进行采样。高通量测序用于分析根相关真菌（ITS 标记）群落（mycobiome）。发现地点对真菌生物群落的组成有深远的影响，在高地地点以快速生长的腐生菌（Mortierellomycota）为主，在低地地点以植物物种特异性共生体为主（例如分别用于C. vulgaris和H. lanatus的Rhizoscyphus ericae和Microdochium bolleyi )。移植到较冷的高地和在较暖的低地进行温度处理对真菌群落产生了类似的影响，这意味着无论给定地点的绝对温度如何，导致较高温度变化的冬季气候变化都会对真菌群落结构产生重大影响。