Climate warming is altering the diversity of plant communities but it remains unknown which species will be lost or gained under warming, especially considering interactions with other factors such as herbivory and nutrient availability. Here, we experimentally test effects of warming, mammalian herbivory and fertilization on tundra species richness and investigate how plant functional traits affect losses and gains. We show that herbivory reverses the impact of warming on diversity: in the presence of herbivores warming increases species richness through higher species gains and lower losses, while in the absence of herbivores warming causes higher species losses and thus decreases species richness. Herbivores promote gains of short-statured species under warming, while herbivore removal and fertilization increase losses of short-statured and resource-conservative species through light limitation. Our results demonstrate that both rarity and traits forecast species losses and gains, and mammalian herbivores are essential for preventing trait-dependent extinctions and mitigate diversity loss under warming and eutrophication.Warming can reduce plant diversity but it is unclear which species will be lost or gained under interacting global changes. Kaarlejärvi et al. manipulate temperature, herbivory and nutrients in a tundra system and find that herbivory maintains diversity under warming by reducing species losses and promoting gains.

中文翻译：

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草食动物通过调节性状相关物种的损失和获取来拯救变暖的苔原中的多样性。

气候变暖正在改变植物群落的多样性，但目前尚不清楚哪种变种会在变暖下丧失或获得，特别是考虑到与其他因素（如食草和养分供应）的相互作用。在这里，我们实验性地测试了变暖，哺乳动物食草和施肥对苔原物种丰富度的影响，并研究了植物功能性状如何影响损失和收益。我们表明，食草动物逆转了变暖对多样性的影响：在存在食草动物的情况下，变暖通过增加物种获得和减少损失而增加了物种丰富度，而在没有食草动物的情况下，变暖导致了物种损失增加，从而降低了物种丰富度。食草动物在变暖的情况下促进短期生长的物种的生长，而食草动物的去除和施肥则通过光限制增加了短命和资源保守物种的损失。我们的研究结果表明，稀有性和性状都可以预测物种的丧失和增加，而哺乳动物食草动物对于防止因性状而导致的物种灭绝和减轻变暖和富营养化下的多样性丧失至关重要。在相互作用的全球变化中。Kaarlejärvi等。在苔原系统中控制温度，草食和养分，发现草食能在变暖下通过减少物种损失和促进收益来维持多样性。暖食可以减少植物的多样性，但尚不清楚在相互作用的全球变化下哪些物种将会丧失或获得，尚不清楚哺乳动物和食草动物对于防止依赖于特征的物种灭绝和减轻物种在变暖和富营养化下的丧失至关重要。Kaarlejärvi等。在苔原系统中控制温度，草食和养分，发现草食能在变暖下通过减少物种损失和促进收益来维持多样性。暖食可以减少植物的多样性，但尚不清楚在相互作用的全球变化下哪些物种将会丧失或获得，尚不清楚哺乳动物和食草动物对于防止依赖于特征的物种灭绝和减轻物种在变暖和富营养化下的丧失至关重要。Kaarlejärvi等。在苔原系统中控制温度，草食和养分，发现草食能在变暖下通过减少物种损失和促进收益来维持多样性。