Data and Code for "Naturalized tree species in the Anthropocene: Climate surpasses geography in shaping beta diversity"

Aim: Assessing to what degree the spread of naturalized alien tree species has changed their taxonomic and phylogenetic beta diversities globally, and whether the factors driving those diversity patterns have shifted. Location: Globe. Time period: From the 15th century to the present time. Major taxa studied: Tree. Methods: For 1,844 naturalized tree species, we compiled data on their native and naturalized ranges and assessed the magnitude of changes in taxonomic and phylogenetic beta diversity resulting from the global spread of these alien species. Additionally, we examined the relative contributions of climatic factors, geographic distance, and trade to their beta diversity before and after human-mediated spread. Results: The spread of naturalized tree species has reduced their beta diversity of the 50 subcontinental TDWG-2 regions globally, i.e., causing substantial biotic homogenization in naturalized tree floras. Notably, we found that distant regions have become more similar in species composition than regions that are adjacent to or share a boundary with each other. Although a positive relationship between taxonomic and phylogenetic similarities was observed, taxonomic similarity showed a tendency for stronger changes. Geographic distance was the most influential factor in shaping both taxonomic similarity before naturalization, while temperature became dominant after naturalization. Contrary to expectations, trade intensity had only a marginal effect on both taxonomic and phylogenetic similarity after naturalization. Main conclusions: Our study highlights the widespread expansion of naturalized tree species and their contribution to global biotic homogenization in naturalized tree floras. The results emphasize the diminished role of geographic distance and the growing influence of temperature in shaping species similarities after naturalization. Projections of intensifying human activities and ongoing climate change suggest that the composition of naturalized tree species is likely to undergo further reshuffling in the future, potentially reshaping the fundamental spatial structure of the biosphere.研究目标：评估全球归化外来树木物种的扩散在多大程度上改变了其分类学和系统发育β多样性，以及驱动这些多样性格局的因素是否发生了变化。 研究区域：全球范围。 研究时段：15世纪至今。 研究类群：树木（Tree）。 研究方法：针对1844种归化树木物种，我们整理了其原生分布区与归化分布区的数据，并评估了这些外来物种全球扩散所引发的分类学与系统发育β多样性变化幅度。此外，我们还分析了气候因子、地理距离与贸易活动在人类介导扩散前后对其β多样性的相对贡献。 研究结果：全球范围内，归化树木物种的扩散已使50个次大陆级TDWG-2分区的β多样性降低，即归化树木区系发生了显著的生物均质化现象。值得注意的是，我们发现遥远区域的物种组成相似性，相较于彼此邻近或共享边界的区域，反而出现了更显著的提升。尽管分类学相似性与系统发育相似性呈正相关关系，但分类学相似性的变化幅度更强。在归化前，地理距离是塑造分类学相似性的最主要影响因子；而在归化后，温度成为主导因素。与预期相悖的是，贸易强度在归化后对分类学与系统发育相似性仅存在微弱影响。 主要结论：本研究凸显了归化树木物种的全球扩张及其对归化树木区系全球生物均质化的贡献。研究结果强调，在归化后，地理距离的塑造作用减弱，而温度对物种相似性的影响日益增强。随着人类活动加剧与气候变化持续，预测显示未来归化树木物种的组成或将进一步重塑，进而可能改变生物圈的基本空间结构。