Possible extinction of Eversmannia subspinosa in Eastern Alborz by 2060 due to climate change: A MaxEnt study

Abstract Climate change has altered ecosystems by affecting the suitability of environments for different species. Species distribution models provide insights regarding these changes, which could be valuable in conservation planning. In this study, we model the current and projected future distribution of Eversmannia subspinosa, a shrub from the Fabaceae family, across the Eastern Alborz area. This plant is endangered in Iran and is only found in the study area.We used the Maximum Entropy (MaxEnt) method and trained the model with the least correlated and most important bioclimatic and topographic variables. CMCC-ESM2 and HadGEM3 climate models, in conjunction with IPCC Representative Concentration Pathways RCP2.6, RCP4.5, and RCP8.5, were used to predict the distribution of the species in 2040 and 2060. Our results suggest that the current habitats of E. subspinosa are mainly in southern parts of Eastern Alborz. Elevation (54.9%) and annual mean temperature (24.5%) were the main contributors to the model. CMCC-ESM2 model predicts significant habitat loss up to 2040 and almost complete disappearance of high probable habitats (0.5 ≤ probability of presence) up to 2060. It also suggests a distribution shift toward higher elevations in Northern and North-Eastern areas of the study area. The model trained by HadGEM3 predicts extinction of E. subspinosa across the study area up to 2040. Filling the gaps between protected areas and national parks and limiting road construction, which blocks its migration to higher elevations in response to global warming, could delay the extinction of this rare species in Iran.