Updating the Checklist of the Naturalized Flora in Taiwan

The species richness of naturalized flora in Taiwan has continued to increase over the past decade. To understand the recent dynamics of naturalization, we updated the checklist of naturalized plants and investigated their chronology, taxonomic distributions, life histories, origins, and invasive risks. One hundred thirty-five species were newly added, and 58 species were excluded owing to a lack of clear evidence of naturalization. The number of naturalized species per decade has gradually increased, peaking in the 2000s (144 species), and declining remarkably in the 2010s (63 species). Poaceae, Asteraceae, and Fabaceae were the most species-rich families, consistent with the global patterns of naturalized alien flora. These exotic species were primarily perennial herbs, followed by annual herbs and shrubs. America has been the most consistent source of naturalized species over the past 160 years. Although the naturalization rate has decreased in the last decade, a few potential invaders (i.e., species with extremely high risk scores) are still worthy of further monitoring and management.