Expansion risk of invasive plants in regions of high plant diversity: A global assessment using 36 species

Invasive plant species (IPS) have a high potential for expanding within biodiversity hotspots and threatening global plant diversity. Hence, it is urgent to assess the expansion risk of IPS in regions of high plant diversity and their potentially negative effects throughout the world. We used the world's 36 worst IPS as focal study species and applied species distribution modeling to project the suitable habitat distributions of these IPS in centers of plant diversity at the global scale. Subsequently, we assessed the expansion risk of IPS based on habitat suitability across biomes and nature reserves. We found that IPS, particularly Chromolaena odorata, Eichhornia crassipes, Leucaena leucocephala, and Mimosa pigra, have high expansion potential in Tropical & Subtropical Moist Broadleaf Forests, Tropical & Subtropical Dry Broadleaf Forests, and Mangroves within global regions of high plant diversity. Furthermore, IPS such as Imperata cylindrica and L. leucocephala may expand dramatically into Vulnerable and Critical or Endangered biome areas, including nature reserves across Tropical & Subtropical Moist Broadleaf Forests and Tropical & Subtropical Coniferous Forests. We suggest that effective conservation management should be enhanced in order to reduce the expansion risk of IPS in the Vulnerable and Critical or Endangered biome areas, that temperature changes should be carefully monitored, and that conservation policies of nature reserves should be reviewed, particularly regarding IPS with high potential to naturally disperse into the nature reserves.