Island ecosystems are particularly susceptible to the impacts of invasive species. Many rare and endangered species that are endemic to islands are negatively affected by invasions. Past studies have shown that the establishment of non-native species on islands is related to native plant richness, habitat heterogeneity, island age, human activity, and climate. However, it is unclear whether the factors promoting establishment (i.e. the formation of self-sustaining populations) also promote subsequent invasion (i.e. spread and negative impacts). Using data from 4308 non-native plant species across 46 islands and archipelagos globally, we examined which biogeographic characteristics influence established and invasive plant richness using generalized linear models nested within piecewise structural equation models. Our results indicate that anthropogenic land use (i.e. human modification) is strongly associated with establishment but not invasion, that climate (maximum monthly temperature) is strongly associated with invasion but not establishment, and that habitat heterogeneity (represented by maximum elevation and island area) is strongly associated with both establishment and invasion. Island isolation explains native plant richness well, but is not associated with established and invasive plant richness, likely due to anthropogenic introductions. We conclude that anthropogenic land use on islands is likely to be a proxy for the number of introductions (i.e. propagule pressure), which is more important for establishment than invasion. Conversely, islands with more diverse habitats and favorable (warm) climate conditions are likely to contain more available niche space (i.e. ‘vacant niches') which create opportunities for both establishment and invasion. By evaluating multiple stages of the invasion process, we differentiate between the biogeographic characteristics that influence plant establishment (which does not necessarily lead to ecological impacts) versus those that influence subsequent plant invasion (which does lead to negative impacts).

中文翻译：

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人类活动推动了非本地植物在岛屿上的建立，而不是入侵


岛屿生态系统特别容易受到入侵物种的影响。许多岛屿特有的稀有和濒危物种都受到入侵的负面影响。过去的研究表明，岛上非本地物种的建立与本地植物的丰富性、栖息地异质性、岛屿年龄、人类活动和气候有关。然而，目前尚不清楚促进建立的因素（即形成自我维持的种群）是否也促进了随后的入侵（即传播和负面影响）。使用来自全球 46 个岛屿和群岛的 4308 种非本地植物物种的数据，我们使用嵌套在分段结构方程模型中的广义线性模型研究了哪些生物地理特征会影响已建立和入侵植物的丰富度。我们的结果表明，人为土地利用（即人类改造）与建立密切相关，但与入侵无关，气候（每月最高温度）与入侵密切相关，但与建立无关，栖息地异质性（以最大海拔和岛屿面积为代表）与建立和入侵密切相关。岛屿孤立很好地解释了本地植物的丰富性，但与已建立的和入侵的植物丰富性无关，这可能是由于人为引入。我们得出结论，岛屿上的人为土地利用可能是引入次数（即繁殖压力）的代表，这对于建立比入侵更重要。相反，具有更多样化栖息地和有利（温暖）气候条件的岛屿可能包含更多可用的生态位空间（即“空置生态位”），这为建立和入侵创造了机会。 通过评估入侵过程的多个阶段，我们区分了影响植物建立的生物地理特征（不一定导致生态影响）和影响随后植物入侵的生物地理特征（确实导致负面影响）。