Aliens in the Norwegian flora: Effects on spatial patterns of diversity

Non-native species form an expanding part of vascular plant communities, increasingly spreading from urban centres to inland areas and influencing biodiversity patterns. To investigate the spatial patterns and drivers of these communities in Norway, we analysed a combined assemblage of 1,105 native and 1,001 non-native species. We constructed a multi-locus phylogeny, sampled and compiled functional trait data for all species, and combined these data with publicly available occurrence records and calculated three diversity metrics: species richness, functional richness, and phylogenetic diversity. Our results revealed little difference across all three diversity metrics. Species richness, functional richness, and phylogenetic diversity all increased with temperature, precipitation, and net primary productivity, while decreasing with higher human footprints and greater proportions of non-native species. However, when randomised we did not find a pattern for non-native species. These findings show that while anthropogenic impact facilitate the spread of non-natives and influence diversity patterns, their impact is relatively low at the national scale. Despite the presence of non-natives and increasing anthropogenic pressures, Norwegian floral communities are still largely intact.