Alien plant species invasiveness and impact on diversity (i.e. species richness and composition) can be driven by the altered competitive interactions experienced by the invader in its invaded range compared to its native range. Trait-based competition effects on invasiveness can be mediated through size-asymmetric competition, i.e. a trait suit of the invader that drives competitive dominance, and through ‘niche differences', i.e. trait differentiation and thus minimized competition between invader and the invaded community. In terms of invasion impact, size-asymmetric competition is expected to result in competitive exclusion of co-occurring subordinate species, whereas ‘niche differences' might result in competitive exclusion of the most functionally similar co-occurring species. Although observational work does not allow the full disentanglement of both trait-based effects, it does allow to verify the occurrence of expected theoretical trait patters. In this study, we explored the trait-based competition effects on invasiveness and diversity impact for Rosa rugosa in both its invaded range in Belgium and its native range in Japan, based on seven functional traits across 100 vegetation plots. Following the predictions for enhanced invasiveness, we found much lower functional overlap between R. rugosa and the co-occurring species in the invaded range compared to the native range. This likely also explains the absence of diversity impact in its native range. Despite the absence of changes in species richness in the invaded range, the invader did strongly impact species composition of invaded communities. This impact occurred through strong shade tolerance responses, suggesting size-asymmetric competition effects and cover loss of co-occurring dominant species, next to exclusion of co-occurring species most functionally similar to the invader; suggesting niche difference effects. In conclusion, this case-study illustrates how exploring functional trait patterns across a species native and invaded range can help in understanding how trait-based competition processes can affect invasiveness and community impact.

中文翻译：

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一种跨越本地和入侵范围的基于特征的方法，以了解植物入侵和社区影响

外来植物物种的侵入性和对多样性的影响（即物种丰富度和组成）可以由入侵者与其原生范围相比在其入侵范围内经历的竞争性相互作用发生改变。基于特征的竞争对入侵的影响可以通过大小不对称竞争（即驱动竞争优势的入侵者的特征套装）和“利基差异”（即特征差异）来调节，从而最小化入侵者与被入侵社区之间的竞争。在入侵影响方面，预计大小不对称竞争会导致共生从属物种的竞争排斥，而“利基差异”可能会导致功能最相似的共存物种的竞争排斥。尽管观察工作不允许完全解开基于特征的两种影响，但它确实允许验证预期的理论特征模式的发生。在这项研究中，我们探讨了基于特征的竞争对入侵性和多样性影响的影响Rosa rugosa在比利时的入侵范围和日本的原生范围内，基于 100 个植被地块的七个功能特征。根据对侵袭性增强的预测，我们发现R. rugosa之间的功能重叠要低得多以及与本地范围相比，入侵范围内的共生物种。这也可能解释了在其原生范围内没有多样性影响。尽管入侵范围内的物种丰富度没有变化，但入侵者确实强烈影响了入侵群落的物种组成。这种影响是通过强烈的耐阴反应发生的，这表明大小不对称的竞争效应和共存优势物种的覆盖损失，接下来排除了与入侵者在功能上最相似的共存物种；暗示利基差异效应。总之，本案例研究说明了探索本地和入侵物种范围内的功能特征模式如何有助于了解基于特征的竞争过程如何影响入侵和社区影响。