Predicting the distribution of critically endangered tree species Karomia gigas under climate change in Tanzania

Abstract

Global climate change and anthropogenic pressure are increasingly adding stress to critically endangered plant species. Unfortunately, the responses of these species are largely unknown in the African tropics to a great extent partly because of limited research. To implement sustainable conservation or adaptation strategy, it is necessary to understand the impacts of climate change on both the ecosystems and species. Here we present an assessment of the current and future habitat suitability distribution of Karomia gigas (Faden) Verdc (Lamiaceae), a critically endangered tree species by using a maximum entropy (MaxEnt) species distribution model. The future predictions of Karomi gigas were done for the years 2050 (RCP 2.6 and 8.5) and 2070 (RCP 2.6 and 8.5). Future and current predictions are made using bioclimatic variables with a spatial resolution of 30 s. This study was carried out in Litipo and Mitundumbea forest reserves found in the coastal forests of Lindi, Tanzania. The area under receiver operating curve (AUC) value confirmed a predictive accuracy based on 45 occurrence points. The Jackknife test was used to assess the contribution of environmental variables in the model. The temperature annual range (Bio7) showed the highest predictive contribution and useful information to predict the current and future potential distributions of K. gigas in the forest reserves. In conclusion, the study shows that the habitat suitability distribution for K. gigas in Tanzania will increase significantly between 2050 and 2070. Therefore, this study showed that modeling outputs using MaxEnt can be helpful for habitat conservation and species restoration in East African coastal forests.