Evaluation of Climate Change Impacts on the Potential Distribution of Styrax sumatrana in North Sumatra, Indonesia

Abstract

This study aims to assess the impact of climate change on the distribution of Styrax sumatrana in North Sumatra by applying the maximum entropy (MaxEnt) model with biophysical factors (elevation, slope, aspect, and soil), climatic factors (19 bioclimate data sets for 2050 and 2070), and anthropogenic factors (land use land cover (LULC) changes in 2050 and 2070). The future climate data retrieved and used are the output of four climate models from Coupled Model Intercomparison Project Phase 5 (CMIP5), namely, the CCSM4, CNRM-CM5, MIROC5, and MRI-CGCM3 models, under the Representative Concentration Pathways (RCPs) 4.5 and 8.5 scenarios. The MaxEnt modelling results showed the importance of the mean temperature of the coldest quarter and the LULC variables. Styrax sumatrana rely on environmental conditions with air temperatures ranging from 13 to 19 °C. The potentially suitable land types for Styrax sumatrana are shrubs, gardens, and forests. The future predictions show that the suitable habitat for Styrax sumatrana is predicted to decrease to 3.87% in 2050 and to 3.54% in 2070 under the RCP4.5 scenario. Under the RCP8.5 scenario, the suitable area is predicted to decrease to 3.04% in 2050 and to 1.36% in 2070, respectively. The degradation of the suitable area is mainly due to increasing temperature and deforestation in future predictions. The modelling results illustrate that the suitable habitats of Styrax sumatrana are likely to be reduced under future climate change scenarios or lost in 2070 under the RCP8.5 scenario. The potential future extinction of this species should alert authorities to formulate conservation strategies. Results also demonstrated key variables that should be used for formulating ex situ conservation strategies.