Frontiers of Biogeography

The marula tree, Sclerocarya birrea (S. birrea) (A. Rich.) Horchst, is native to Africa, used to restore drylands, and introduced outside Africa as a pilot towards commercial cultivation due to its economic potential. However, there is a global paucity of information regarding where subspecies can survive beyond Africa. We aimed to predict and quantify global-scale suitable areas for S. birrea and its subspecies beyond their native ranges under the current environmental conditions and future warming climates. The areas were predicted by using MaxEnt algorithm using occurrence data from Africa and, climatic and topographical environmental variables and, the Max Planck Institute for Meteorology and Hadley Climate Center’s global Earth Systems Models under shared socio-economic pathways (SSPs) greenhouse gas concentrations, SSP3-7.0, for the year 2050 and 2080. The results show that the models’ predictive power was robust, with the Receiver Operating Characteristic’s Area under the Curve (AUCs) ranging from 0.90-0.98. Currently, suitable areas exist in all continents except Europe and Antarctica and, occupy 3,751,057 km2 to 24,632,452 km2 of Earth’s terrestrial area scattered in 54 to 107 countries predominantly in global biomes with climatic conditions ranging from desert tropical to temperate humid. Under future climates, the areas will retract by 64-100%, shifting to high latitudes and being limited to global biomes with tropical desert-to-desert temperate, Mediterranean warm conditions, and some regions of Eastern Europe will become suitable areas. Suitable areas for S. birrea and its subspecies exist beyond Africa, and they will retract and migrate to high latitudes under future warming climates.