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

Abstract

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

Popular Abstract

Determining distribution and status of species in the context of climate change allow conservationists to assess contemporary and future ranges for plant species in the protected areas. Climate change data are important predictor variables for determining plant species habitat, but is rarely used in Tanzania when modelling current and future distribution of plant species.

Prunus africana is a tree that is important for its pharmaceutical uses. In this study, I used species distribution modelling techniques to construct species distribution maps for Prunus africana. The goal of this was to determine relative contribution of Prunus africana and the effects of climate change on its distribution based on Inter-governmental Panel on Climate Change scenarios (Business as usual and Green economy scenarios). For the modelling, presence records for Prunus africana, were used as a dependent variable, while climate, soil, and topographic data which determines the growth of this species were used as predictor variables.

I found that the geographical distribution of Prunus africana is highly affected by climatic variables such as maximum temperature warmest month and rainfall driest month followed by elevation and soils. Current distribution maps show that areas with high elevations in the study area are the ones with suitable habitat for Prunus africana. Future distribution maps show both habitat gains and losses for Prunus africana under both the business as usual, and green economy scenarios in the study area. The business as usual scenario records larger loss of suitable habitat for Prunus africana compared to green economy scenario in the Mid-century and Late-century. Therefore, under changing climate, some species like Prunus africana might expand or contract their suitable habitats, which will have implications on management and conservation of such species in Tanzania.

Advisor: Dr. Genesis T. Yengoh
Master degree project 30 credits in Geographical Information Sciences, 2018
Original title: Effects of Climate Change on Potential Geographical Distribution of Prunus africana (African cherry) in the Eastern Arc Mountain Forests of Tanzania
Department of Physical Geography and Ecosystems Sciences, Lund University.
LUMA-GIS thesis nr 89

• author: Giliba, Richard
• supervisor: Yengoh Genesis Tambang
• organization: Dept of Physical Geography and Ecosystem Science
• course: GISM01 20181
• year: 2018
• type: H2 - Master's Degree (Two Years)
• subject: Earth and Environmental Sciences
• keywords: cchange, species distribution, range shift, suitable habitats
• publication/series: Master Thesis in Geographical Information Science
• report number: 89
• language: English
• id: 8956077
• date added to LUP: 2018-08-19 15:08:31
• date last changed: 2018-08-19 15:08:31