Climate change is reducing the depth and duration of winter snowpack, leading to dramatic changes in the soil environment with potentially important ecological consequences. Previous experiments in the Intermountain West of North America indicated that loss of snowpack increases survival and population growth rates of the invasive annual grass Bromus tectorum; however, the underlying mechanism is unknown. We hypothesized that reduced snowpack might promote B. tectorum population growth by decreasing damage from snow molds, a group of subnivean fungal pathogens. To test this hypothesis, we conducted greenhouse and field experiments to investigate the interaction between early snowmelt and either fungicide addition or snow mold infection of B. tectorum. The greenhouse experiment confirmed that the snow mold Microdochium nivale can cause mortality of B. tectorum seedlings. In the field experiment, early snowmelt and fungicide application both increased B. tectorum survival, but their effects did not interact, and snow mold inoculation had no effect on survival. We did find interactive effects of snowmelt and fungal treatments on B. tectorum seed production: with ambient snowpack, M. nivale inoculation reduced seed production and fungicide increased it, whereas in the early snowmelt treatment seed production was high regardless of fungal treatment. However, treatment effects on seed production did not translate directly to overall population growth, which did not respond to the snow melt by fungal treatment interaction. Based on our mixed results, the hypothesis that reduced snowpack may increase B. tectorum fitness by limiting the effects of plant pathogens deserves further investigation.

中文翻译：

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气候变化，积雪和霉菌入侵布鲁姆斯：寒冷天气病原体释放的混合证据。

气候变化正在减少冬季积雪的深度和持续时间，导致土壤环境发生巨大变化，并可能带来重要的生态后果。先前在北美西部山间地区进行的实验表明，积雪的减少增加了入侵性一年生禾草Bromus tectorum的存活率和种群增长率。但是，其潜在机制尚不清楚。我们假设减少积雪可以通过减少来自雪霉菌（一种亚潜伏性真菌病原体）的损害来促进胸腺双歧杆菌种群的增长。为了验证该假设，我们进行了温室和田间试验，以研究早期融雪与杀真菌剂鹤望兰的杀菌剂添加或雪霉感染之间的相互作用。温室实验证实，积雪的霉菌小雪蛤可以导致硬顶牛的幼苗死亡。在田间试验中，早期融雪和杀真菌剂的使用均增加了鹤望兰的存活，但是它们的作用没有相互作用，接种雪霉菌对存活没有影响。我们的确发现了融雪和真菌处理对牛油菌种子产生的交互作用：在环境积雪堆中，新孢子虫接种减少了种子的产生，而杀菌剂增加了它，而在融雪早期，无论采用何种真菌处理，种子的产量都很高。但是，处理对种子产量的影响并未直接转化为总体种群的增长，而真菌的相互作用并未对融雪做出反应。根据我们的混合结果，