Land use changes pose major threats to biodiversity. In this study, we analysed the impacts of urbanization and agricultural legacy on plant communities of isolated wetlands (Laval, Québec, Canada). We sampled 35 marshes and 32 swamps. We used multi-factor analysis of variance to compare taxonomic richness and functional diversity between wetland types, urbanization levels and former agricultural use. We calculated beta diversity as between-site similarities in composition, and differences were evaluated using tests for homogeneity in multivariate dispersions. We also analysed the effect of exotic species on beta diversity. We found that urbanization and former agricultural use had no effect on taxonomic richness, functional diversity or beta diversity. However, exotics tended to be more abundant in urban and previously cultivated wetlands than in more natural ones. Furthermore, despite the absence of difference in beta diversity in response to present and past human disturbances when analysing the total species pool, we found that exotic species tend to favor homogenization. We also found that species composition differed in response to urbanization in marshes, while in swamps it differed according to former agricultural uses. This contrasting result was likely due to the fact that marshes are dominated by herbaceous species and swamps by woody species (short vs. long regeneration time). Our study highlights the importance of looking at different types of habitats within the same urban context and considering land use legacy to understand the response of ecosystems to urbanization, especially due to the time lag between disturbances and vegetation responses.

中文翻译：

---

城市化和农业遗产对偏远湿地生物分类和功能多样性的影响

土地利用变化对生物多样性构成重大威胁。在这项研究中，我们分析了城市化和农业遗留对偏远湿地（加拿大魁北克省拉瓦尔）植物群落的影响。我们采样了35个沼泽和32个沼泽。我们使用方差的多因素分析来比较湿地类型，城市化水平和以前的农业用途之间的分类学丰富度和功能多样性。我们将β多样性计算为组成之间的站点间相似性，并使用多元分散体中的同质性测试评估差异。我们还分析了外来物种对β多样性的影响。我们发现，城市化和以前的农业使用对分类学丰富度，功能多样性或Beta多样性没有影响。然而，与更自然的湿地相比，城市湿地和以前耕种的湿地往往具有更多的外来物种。此外，尽管在分析总物种库时，由于响应当前和过去的人类干扰，β多样性不存在差异，但我们发现外来物种倾向于倾向于同质化。我们还发现，沼泽地对城市化的响应对物种组成有所不同，而在沼泽中，其物种根据以前的农业用途而有所不同。这种对比结果可能是由于这样一个事实，即沼泽以草本种为主，沼泽以木本种为主（再生时间长，再生时间长）。我们的研究强调了在相同的城市环境中研究不同类型的栖息地并考虑土地使用遗留以了解生态系统对城市化的反应的重要性，