Widespread homogenization of plant communities in the Anthropocene

Native biodiversity decline and non-native species spread are major features of the Anthropocene. Both processes can drive biotic homogenization by reducing trait and phylogenetic differences in species assemblages between regions, thus diminishing the regional distinctiveness of biotas and likely have negative impacts on key ecosystem functions. However, a global assessment of this phenomenon is lacking. Here, using a dataset of >200,000 plant species, we demonstrate widespread and temporal decreases in species and phylogenetic turnover across grain sizes and spatial extents. The extent of homogenization within major biomes is pronounced and is overwhelmingly explained by non-native species naturalizations. Asia and North America are major sources of non-native species; however, the species they export tend to be phylogenetically close to recipient floras. Australia, the Pacific and Europe, in contrast, contribute fewer species to the global pool of non-natives, but represent a disproportionate amount of phylogenetic diversity. The timeline of most naturalisations coincides with widespread human migration within the last -500 years, and demonstrates the profound influence humans exert on regional biotas beyond changes in species richness.

Automated summary

The study reveals a widespread and temporal decrease in species and phylogenetic turnover, leading to increased biotic homogenization at different scales and spatial extents. The homogenization within major biomes is largely driven by non-native species introductions, with Asia and North America being major sources. However, Australia, the Pacific and Europe contribute disproportionately to phylogenetic diversity in the global pool of non-native species.