Small rodent population cycles characterise northern ecosystems, and the cause of these cycles has been a long-lasting central topic in ecology, with trophic interactions currently considered the most plausible cause. While some researchers have rejected plant–herbivore interactions as a cause of rodent cycles, others have continued to research their potential roles. Here, we present an overview of whether plants can cause rodent population cycles, dividing this idea into four different hypotheses with different pathways of plant impacts and related assumptions. Our systematic review of the existing literature identified 238 studies from 150 publications. This evidence base covered studies from the temperate biome to the tundra, but the studies were scattered across study systems and only a few specific topics were addressed in a replicated manner. Quantitative effects of rodents on vegetation was the best studied topic, and our evidence base suggests such that such effects may be most pronounced in winter. However, the regrowth of vegetation appears to take place too rapidly to maintain low rodent population densities over several years. The lack of studies prevented assessment of time lags in the qualitative responses of vegetation to rodent herbivory. We conclude that the literature is currently insufficient to discard with confidence any of the four potential hypotheses for plant–rodent cycles discussed herein. While new methods allow analyses of plant quality across more herbivore-relevant spatial scales than previously possible, we argue that the best way forward to rejecting any of the rodent–plant hypotheses is testing specific predictions of dietary variation. Indeed, all identified hypotheses make explicit assumptions on how rodent diet taxonomic composition and quality will change across the cycle. Passing this bottleneck could help pinpoint where, when, and how plant–herbivore interactions have – or do not have – plausible effects on rodent population dynamics.

中文翻译：

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小型啮齿动物种群周期和植物——70年后，我们将何去何从？

小型啮齿动物种群周期是北方生态系统的特征，这些周期的原因一直是生态学中长期存在的中心话题，目前认为营养相互作用是最可能的原因。虽然一些研究人员拒绝将植物与草食动物的相互作用视为啮齿动物周期的原因，但其他研究人员仍在继续研究它们的潜在作用。在这里，我们概述了植物是否会导致啮齿动物种群周期，并将这一想法分为四种不同的假设，以及不同的植物影响途径和相关假设。我们对现有文献进行系统回顾，从 150 份出版物中确定了 238 项研究。该证据基础涵盖了从温带生物群落到苔原的研究，但这些研究分散在各个研究系统中，并且只有少数特定主题以重复的方式得到解决。啮齿动物对植被的定量影响是研究最多的主题，我们的证据基础表明这种影响可能在冬季最为明显。然而，植被的再生似乎发生得太快，无法在几年内维持低啮齿动物种群密度。由于缺乏研究，无法评估植被对啮齿动物食草动物的定性反应的时间滞后。我们的结论是，目前的文献不足以有信心地放弃本文讨论的植物-啮齿动物循环的四种潜在假设中的任何一种。虽然新方法允许在比以前更多的与草食动物相关的空间尺度上分析植物质量，但我们认为拒绝任何啮齿动物-植物假设的最佳方法是测试饮食变化的具体预测。事实上，所有已确定的假设都对啮齿动物饮食分类组成和质量在整个周期中如何变化做出了明确的假设。克服这一瓶颈可能有助于查明植物与草食动物的相互作用在何时、何地以及如何对啮齿动物种群动态产生或不产生合理的影响。