Predicting the range expansion of invasive alien grasses under climate change in the Neotropics

A diverse group of invasive grasses from tropical and subtropical Africa and Asia has spread throughout the Neotropics over the last decades. Despite their strong ecological impact, current and future distribution patterns of these grasses in the region according to climate change is poorly investigated. We chose ten high potential invasive grass species and used ecological niche modeling to project their geographic distribution within the Neotropics under four climate change scenarios (current, SSP1-2.6, SSP3-7.0 and SSP5-8.5 for 2100). Current climatically suitable areas for these invasive species were estimated to account for 51.3% of the Neotropics. Projections of future climatically suitable areas ranged between 47.0% and 57.6%, depending on the climate scenario. Range retractions are projected for Melinis repens and Urochloa decumbens regardless of the SSP scenario, while Arundo donax, Hyparrhenia rufa and Melinis minutiflora are expected to expand their range in all SSP scenarios. Currently, these ten invasive species have suitable areas that greatly overlap in dry regions of the Neotropics, mainly in the savannas of Central Brazil and Central America. However, a reduction in species overlap and a geographical expansion towards wetter regions is expected under the SSP1 and SSP3 scenarios, and towards drier regions under the SSP5 scenario.