Modeling the potential distribution of Vitellaria paradoxa C.F. Gaertn (shea nut tree) in the Kidepo Critical Landscape in the face of climate change

Abstract

Contemporary climate change and human activities are increasingly linked with the extinction of several species globally. In semi-arid biomes, such pressures threaten the natural distribution and ecology of species. In the context of Vitellaria paradoxa, the threat from excessive deforestation for charcoal trade is well researched, yet the sensitivity to climate change remains barely known. Accordingly this study set out to assess the potential distribution of Vitellaria paradoxa under different climate change scenarios. Species distribution modelling was carefully used to determine the current potential distribution, the impact of climate change on the distribution, and the important variables in the growth of Vitellaria. The maximum entropy algorithm (MaxEnt) was used to achieve the aim through a species distribution modeling framework. A current distribution model was first developed using only current biophysical variables of soil type, temperature, precipitation, land use type, and elevation. This model was then projected onto two global warming scenarios (RCP 4.5 and RCP 8.5) for 2050 and 2070, using multimodel averages derived from three General Circulation Models (BCC-CSM, CSM4, and MIROC5). Results show disparities in current suitability across the study area, with Otuke and Kitgum districts having the most suitable area and Kotido and Kaabong having the least suitable area. Additionally, noticeable range shifts were observed under different climate change scenarios, with soil type being the most important predictor variable. These results draw useful implications for conservation of such a species in that they show how sensitive the species is to a changing climate as its natural range is mostly reduced. As such, these findings are very useful and can be particularly so for institutions interested in conservation of species like Vitellaria paradoxa. This is because these institutions can incorporate the current risks that climate change poses to the distribution and ecology of such species. It can thus be concluded that climate change is important in the distribution of Vitellaria paradoxa, with noticeable shifts in suitable area as climate changes. Therefore, relevant authorities should create sustainable use zones in areas of highest suitability.