Predicting range shifts of three endangered endemic plants of the Khorassan-Kopet Dagh floristic province under global change

Khorassan-Kopet Dagh (KK) floristic province is an ecoregion that has rarely been studied. A total number of 2576 (356 endemic) vascular plants have been recorded from this area. Most of the endemic species of KK are rare and range-restricted. To assess the vulnerability of plant species under a rapidly changing climate, we can use species distribution modelling (SDM) to predict their potential present and future distribution. We used SDM to evaluate range size changes for three (critically) endangered endemic species to KK, namely Nepeta binaloudensis, Phlomoides binaludensis, and Euphorbia ferdowsiana. These plants represent KK endemic species that grow in the different elevation ranges of KK mountains. Using the HadGEM2-ES general circulation model and two Representative Concentration Pathways Scenarios (RCP), including RCP 2.6 (most optimistic) and RCP 8.5 (most pessimistic), we predicted the potential present and future (i.e., 2050 and 2070) distribution for each species. The ensemble model of nine different methods was used for this prediction. Our results showed that, except for P. binaludensis that will face range contraction, the other species would benefit from potential range expansion in the future. Euphorbia ferdowsiana will remain limited to a narrow range of KK. However, the other two plants will have suitable habitats in various mountains of KK. To conserve flora of KK, we urge using management efforts with a focus on providing elevational migration routes at the local scales in KK mountains. Additionally, assisted migration among different mountains of this region will be beneficial to conserve its endemic plants. For E. ferdowsiana genetic diversity storage employing seed banks and botanical garden preservation should be considered.