Exotic plant invasion under increased environmental variability

植物入侵是全球变化最重要的驱动力之一，并造成重大的经济和生态破坏。最近的研究表明，新的气候条件，如平均温度和降水量的变化，可以促进入侵植物的传播。然而，气候变化的一个方面仍然没有得到充分的研究，那就是环境变异性的变化。在一项试点实验中，我表明，增加营养供应的可变性，这是气候变化的常见后果，可以有力地促进入侵节藻的入侵成功，节节草是世界上最有害的入侵物种之一。现在重要的是测试这种现象有多普遍，它在现场条件下有多大的相关性，以及它的潜在机制是什么。在这里，我提出了一个项目，该项目将彻底探索以营养波动形式出现的环境变异性变化与植物入侵之间的关系。我的项目有四个目标：(1)通过比较不同幅度和频率的营养波动的影响，确定哪种类型的变异性最能促进植物入侵；(2)测试变异性增加对竞争优势的积极影响是否是一个普遍现象，跨越(A)不同的入侵节肢植物分类群，(B)其他高度入侵的植物物种，或(C)被认为是良好的资源竞争对手的本土物种；(3)通过稳定的同位素分析，检查入侵者在高环境变异性条件下的成功是否与他们优越的吸收和投资资源的能力有关，(4)测试田间条件下养分波动对植物入侵的影响。我的项目将增加我们对植物入侵潜在机制的总体理解，以及入侵与其他环境变化驱动因素之间的相互作用。此外，它将有助于预测哪些栖息地将受到特别威胁，从而最终防止和管理植物入侵。

Plant invasions are amongst the most important drivers of global change, and cause substantial economic and ecological damage. Recent studies indicate that novel climatic conditions, such as changes in mean temperature and precipitation, can promote the spread of invasive plants. One dimension of climate change, however, which remains understudied, is changes in environmental variability. In a pilot experiment I showed that increased variability of nutrient supply, a common consequence of climatic variability, can strongly promote the invasion success of invasive knotweed, one of the worlds most noxious invasive species. It is now important to test how general this phenomenon is, how relevant it is under field conditions, and what its underlying mechanisms are. Here I propose a project that will thoroughly explore the relationships between changes in environmental variability, in the form of nutrient fluctuations, and plant invasion. My project has four aims: (1) to determine which types of variability promote plant invasion most by comparing the effects of nutrient fluctuations of different magnitudes and frequencies, (2) to test whether positive effects of increased variability on competitive dominance are a general phenomenon across (a) different invasive knotweed taxa, (b) other highly invasive plant species, or (c) also native species that are considered to be good resource competitors, (3) to examine, through stable isotope analyses, whether the success of invaders at high environmental variability is linked to their superior ability to take up and invest resources, and (4) to test the impact of nutrient fluctuations on plant invasion under field conditions. My project will increase our general understanding of the mechanisms underlying plant invasion, and of the interactions between invasion and other drivers of environmental change. Moreover, it will help to predict which habitats will be particularly threatened and thus, ultimately, to prevent and manage plant invasions.