Projecting shifts in the distribution of Vachellia tortilis subsp. raddiana in Africa under climate change: a MaxEnt modeling and GIS analysis.

Vachellia tortilis (Forssk.) Hayne subsp. raddiana (Savi) Brenan, a drought-resistant tree native to arid and semi-arid regions of Africa and the Middle East, plays a crucial ecological and socioeconomic role by providing shade, forage, fuelwood, and contributing to soil stabilization and desertification control. To support scientific site selection for artificial planting and assess its current and potential distribution, we used the MaxEnt model combined with ArcGIS to evaluate climatic suitability across Africa based on occurrence records and environmental variables. After ten iterations, the model achieved high predictive accuracy with training and test AUC values of 0.942. Eight key bioclimatic factors shaped the distribution, with Mean Temperature of the Coldest Quarter (32.1%) and Isothermality (28.6%) exerting the greatest influence. Present-day highly suitable habitats (496.69 × 104 km2) are concentrated in northern and southeastern Africa, notably in Libya, Egypt, Ethiopia, Kenya, Namibia, and Botswana, while moderate- and low-suitability zones cover 662.83 × 104 km2 and 695.81 × 104 km2, respectively. Future projections indicate an upward shift in suitable areas, with limited changes expected by the 2030s but substantial declines from the 2050s onward. Under the SSP585 scenario by the 2090s, highly suitable habitats are predicted to shrink by 80% to only 98.91 × 104 km2, becoming fragmented and primarily confined to Western Sahara, Kenya, Libya, Egypt, and Ethiopia. The model developed by MaxEnt was applicable to explore the environmental suitability of Vachellia tortilis.