Ongoing globalisation and climate change are causing plant species to invade new habitats and thereby alter biodiversity and ecosystem functioning. Since numbers of plant invasions continue to increase globally, it is crucial to investigate the effects of multiple co-occurring alien species on native communities. Furthermore, priority effects due to the earlier emergence of certain species affecting fitness of later arriving species can shape community structure and affect native species performance. We investigate in a common garden pot experiment the interactions among five alien-native species pairs. First we focus on the effect of growing with either one or two alien neighbour species on a native plant, second we alter the arrival time of the alien or native neighbour by 3 weeks. Generally, native species performance decreased when surrounded by two alien species compared to only one, although the magnitude of this effect varied depending on species, with one species even performing better with alien neighbours than in monoculture. Species performance greatly decreased when arriving second in the pot, for both native and alien species. In contrast, alien species tended to benefit more from arriving early. Given that we studied annual ruderal species, their potentially lower competitive ability might explain why we detected negative effects of late arrival. We highlight the need to further elucidate underlying mechanisms of small-scale invasion dynamics to achieve generalisations concerning the response of multiple alien and native plants given their species-specific differences in response to neighbour species and arrival time.

持续的全球化和气候变化正在导致植物物种侵入新的栖息地，从而改变生物多样性和生态系统功能。由于全球植物入侵的数量持续增加，因此研究多种同时出现的外来物种对本地社区的影响至关重要。此外，由于某些物种较早出现而影响后来到达物种的适应性，优先效应可以塑造群落结构并影响本地物种的表现。我们在一个普通的花盆实验中调查了五个外来物种对之间的相互作用。首先，我们关注与一种或两种外来邻居物种一起生长对本地植物的影响，其次，我们将外来或本地邻居的到达时间更改为 3 周。一般来说，与仅一种外来物种相比，当被两种外来物种包围时，本地物种的表现会下降，尽管这种影响的程度因物种而异，一种物种与外来邻居的表现甚至比单一栽培更好。对于本地和外来物种，当在锅中获得第二名时，物种的表现大大下降。相比之下，外来物种往往从早期到达中受益更多。鉴于我们研究了一年一度的粗野物种，它们潜在的较低竞争能力可能解释了为什么我们检测到迟到的负面影响。我们强调需要进一步阐明小规模入侵动态的潜在机制，以实现对多种外来和本地植物响应的概括，因为它们对邻近物种和到达时间的响应具有物种特异性差异。