Projected effects of climate change on the potential environmental suitability of Vachellia seyal (Delile) P. J. H. Hurter in Sudan using MaxEnt species distribution modeling

Abstract

Climate change may substantially alter the environmental suitability of dryland tree species, with important implications for conservation and restoration. We modelled the current and future potential environmental suitability of Vachellia seyal (Delile) P.J.H.Hurter across Sudan using MaxEnt, based on 448 spatially thinned occurrence records and nine climatic, topographic, and edaphic predictors. Future suitability was projected using the ensemble mean of three CMIP6 global climate models under SSP2-4.5 and SSP5-8.5 for 2021–2040 and 2081–2100. Model discrimination was high (mean test AUC = 0.944; TSS = 0.838 ± 0.02). Isothermality (BIO3; 37.6% contribution), precipitation of the warmest quarter (BIO18; 24.7%), and precipitation seasonality (BIO15; 14.2%) were the principal predictors. Under baseline conditions, 380,890.63 km² (20.22% of Sudan) was classified as environmentally suitable. Under SSP2-4.5, projected suitable area decreased to 177,240.19 km² (9.41%) in 2021–2040 and reached 255,482.20 km² (13.56%) in 2081–2100, remaining below the baseline extent. Under SSP5-8.5, projected suitable area was 350,775.69 km² (18.62%) in 2021–2040 and 306,923.26 km² (16.29%) in 2081–2100. Blue Nile, Gedaref, Sennar, and parts of Kordofan retained comparatively extensive potential suitability, whereas northern Sudan remained predominantly unsuitable. These projections represent potential environmental suitability rather than realized future occupancy and should be interpreted in light of sampling, dispersal, land-use, and climate-model uncertainties. The results provide a spatial basis for prioritizing climate-informed monitoring, conservation, and restoration planning for V. seyal in Sudan.