Predicting Impacts of Climate Change on the Distribution of Acacia mearnsii (Black wattle) in the Southern Africa Region.

Alien invasive species (IASs) are a threat to the ecological systems of southern Africa. Acacia mearnsii , a global top 100 invasive species has become a very invasive tree in the region, displacing native vegetation, altering fire regimes, and influencing water availability. In this study, Ecological Niche Modelling was used using the maximum entropy algorithm to predict the current and future distributions of A. mearnsii southern African underMIROC-6 climate models SSP2-4.5 and SSP5-8.5. Data used for modelling were collected from GBIF and 19 bioclimatic variables from Wordclim. The Model performance assessed with Area Under Cover-ROC metrics. The annual mean temperature, precipitation of the wettest month, and maximum temperature of the warmest month were the primary environmental drivers. Currently, highly suitable areas are concentrated in South Africa, Eswatini, and Lesotho. The projected future suitability suggests potential range expansion, particularly under SSP2-4.5, with highly suitable habitats increasing by 13.7%. However, under SSP5-8.5, extreme warming would lower habitat suitability in some regions with an increase (+ 646.21%). Climate change has a significant effect on A. mearnsii's threat of invasion, emphasizing the importance of early detection, risk identification, and tailored management of susceptible ecosystems.