Climate projections and the future of invasive plants in the Caatinga

Abstract The increasing prevalence of invasive plants thriving under changing climates underscores a major ecological concern. While many studies address invasions at broad taxonomic scales, our approach emphasizes the simultaneous projection of multiple species grouped by functional traits. In addition to modeling their joint distribution, we evaluated the persistence and spatial overlap between functionally distinct invaders as a possible indicator of future ecological shifts. Ecosystems like the Brazilian Caatinga, a seasonally dry tropical forest spanning 833,000 km 2 , may be especially vulnerable to invasions and climate change due to widespread land degradation. We projected the future distribution of 11 invasive species under both optimistic and pessimistic climate scenarios, spanning 2021 to 2100. Potential distribution changes were assessed considering the joint invasion of all species, grouped into woody and non-woody categories. Areas with annual mean temperatures between 24 and 27 °C and higher precipitation were more prone to invasions. Non-woody species are projected to occupy the largest high-suitability areas throughout the century. Cenchrus ciliaris L. and Prosopis juliflora (Sw.) are examples of major invaders under both scenarios. One region in the Caatinga remained suitable for both woody and non-woody invaders, reflecting a localized zone of functional co-occurrence retention despite overall habitat contraction. Even with projected declines in suitable areas (−36.4% optimistic, −28.2% pessimistic), the continued presence of invasive species poses risks to native flora, which is generally more sensitive to environmental change. These results highlight the urgency of proactive management to safeguard biodiversity.