Cross-taxon analyses can explain patterns of interaction between taxa and their application in conservation studies can drive management actions. In a coastal sand dune system characterized by a high human pressure, we explored the co-occurrence patterns between vascular plants and bryophytes, with a focus on how the occurrence of invasive alien species (IAS) can affect those taxa and their relationships. Species congruences were evaluated at the community level considering taxonomic and functional diversities. Predictive co-correspondence analysis (Co-CA) was applied to quantify the strength of vascular plant communities in predicting bryophytes species composition. The relationship between the composition of vascular plants and bryophytes was significant, even if weak. Altitude and percentage of bare soil cover are the environmental variables exerting greater influence on the two taxa. The presence of IAS affects communities in an opposite way: for vascular plants, species richness increases with the presence of invasive alien species; for bryophytes, IAS’s presence has a low but significant negative influence, both on species richness and in terms of functional diversity. Results give elements for future studies on the effect of IAS on the bryophytes colonizing coastal sand dunes.

中文翻译：

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外来入侵物种对苔藓植物和维管植物物种共生模式的影响—以地中海受干扰的沙质海岸为例

跨分类群分析可以解释分类群之间的相互作用模式及其在保护研究中的应用，可以推动管理行动。在一个以高压为特征的沿海沙丘系统中，我们探索了维管植物与苔藓植物之间的共生模式，重点研究了外来入侵物种（IAS）的发生如何影响这些分类群及其关系。考虑到生物分类和功能多样性，在社区一级对物种的一致性进行了评估。预测性对应分析（Co-CA）用于量化维管植物群落预测苔藓植物种类组成的强度。维管植物的组成与苔藓植物之间的关系很明显，即使很弱。裸土覆盖的高度和百分比是对这两个分类群影响更大的环境变量。IAS的存在以相反的方式影响着社区：对于维管植物，物种的丰富度随着外来入侵物种的存在而增加；对于苔藓植物，IAS的存在对物种丰富度和功能多样性均具有较低但显着的负面影响。结果为IAS对定殖在沿海沙丘上的苔藓植物的影响提供了基础。