Effects of climate change on potential geographical distribution of Prunus africana (African cherry) in the Eastern Arc Mountain Forests of Tanzania

Sammanfattning: The aim of this study was to model the impacts of climate change on potential geographical distribution of Prunus africana in the Eastern Arc Mountains of Tanzania. Maximum Entropy modelling was used to construct species distribution maps for P. africana to determine relative contribution, and effects of climate change on the potential geographical distribution of P. africana based on climatic scenarios. Species presence data were used as a dependent variable, while climate, soil, and topographic data were used as predictor variables. The current distribution model was evaluated with the Area Under the Curve (AUC) analysis. The results indicate that the distribution of P. africana could be modelled with a test AUC that is significantly better than random. The average test AUC value was 0.97. This indicates high performance of the model. Results of the contribution of predictor variables reveal that the current distribution of P. africana was highly affected by climatic variables. Environmental variables show the highest prediction contribution include maximum temperature warmest month (27.2%), elevation (11.4%) and rainfall driest month (11.3%). Results for potential geographical distribution based on current climatic conditions reveal that there is suitable habitats for P. africana almost in all Eastern Arc Mount (EAM) forests. Moreover, current distribution maps depict areas with high elevations as having very high potential habitat suitability values. Future distribution maps depict both gains and losses in range for P. africana under all climate scenarios. Representative Concentration Pathways (RCP) 8.5 scenario records larger loss in range for P. Africana compared to RCP 4.5 in the Mid-century 2041-2070 (2055) and Late-century 2071-2100 (2085) in the EAM forests. Among the EAM forests Udzungwa, Rubeho, West Usambara, Ukagaru, Uluguru and Ukagaru forests will lose much more suitable habitats for P. africana. This implies that most of the areas currently predicted in EAM forests as suitable will not be suitable in the future. Therefore, under changing climate, P. africana might expand or contract their suitable habitats, which will have implications on management and conservation of this species within the EAM forests. Advisor: Dr. Genesis T. Yengoh Master degree project 30 credits in Geographical Information Sciences, 2018 Department of Physical Geography and Ecosystems Sciences, Lund University. LUMA-GIS thesis nr 89