Program in Ecology and Evolutionary Biology, Department of BioSciences, Rice University, Houston, TX, 77005, USA.
School of Biological Sciences, University of Nebraska, Lincoln, NE, 68588, USA.
Ecol Lett. 2017 Nov;20(11):1374-1384. doi: 10.1111/ele.12833. Epub 2017 Sep 12.
Understanding the role of consumers in density-dependent plant population dynamics is a long-standing goal in ecology. However, the generality of herbivory effects across heterogeneous landscapes is poorly understood due to the pervasive influence of context-dependence. We tested effects of native insect herbivory on the population dynamics of an exotic thistle, Cirsium vulgare, in a field experiment replicated across eight sites in eastern Nebraska. Using hierarchical Bayesian analysis and density-dependent population models, we found potential for explosive low-density population growth (λ > 5) and complex density fluctuations under herbivore exclusion. However, herbivore access drove population decline (λ < 1), suppressing complex fluctuations. While plant-herbivore interaction outcomes are famously context-dependent, we demonstrated that herbivores suppress potentially invasive populations throughout our study region, and this qualitative outcome is insensitive to environmental context. Our novel use of Bayesian demographic modelling shows that native insect herbivores consistently prevent hard-to-predict fluctuations of weeds in environments otherwise susceptible to invasion.
理解消费者在密度依赖型植物种群动态中的作用是生态学中长期以来的目标。然而，由于背景依赖性的普遍影响，对于跨异质景观的食草作用的普遍性还了解甚少。我们在重复进行于内布拉斯加州东部的 8 个地点的野外实验中，测试了本地昆虫食草作用对一种外来蓟类植物 Cirsium vulgare 的种群动态的影响。使用分层贝叶斯分析和密度依赖型种群模型，我们发现，在食草动物被排除的情况下，种群可能会出现爆炸性的低密度增长（λ>5）和复杂的密度波动。然而，食草动物的进入导致了种群的下降（λ<1），抑制了复杂的波动。尽管植物-食草动物相互作用的结果是众所周知的背景依赖性，但我们证明，食草动物抑制了整个研究区域内潜在的入侵种群，而且这种定性结果对环境背景不敏感。我们使用贝叶斯人口模型的新方法表明，在容易受到入侵的环境中，本地昆虫食草动物始终可以防止杂草难以预测的波动。
