Endemic cushions of the Khorassan-Kopet Dagh floristic province show differential responses to future climate change

Climate change negatively affects mountainous plants and leads to their range contraction or extinction. Cushion plants are the essential components of mountainous ecosystems. Although cushions represent the dominant vegetation form of the mountains of the Irano-Anatolian Biodiversity Hotspot, the impacts of climate change on these plants have been merely studied. The present study investigates the effects of climate change on the distribution of endemic cushion species in the Khorassan-Kopet Dagh (KK) floristic province, the eastern-most part of the Irano-Anatolian Biodiversity Hotspot. We predicted the current and future range of 19 cushions in 2040 and 2100, using 19 bioclimatic layers along with two different SSPs and an ensemble of 12 modeling algorithms. These species belong to Acantholimon, Acanthophyllum, Astragalus, Jurinea, and Thymus genera. Our findings revealed that approximately all studied species will face range contraction. On the other hand, Jurinea antunowi, Acantholimon restiaceum, and Acanthophyllum speciosum will show negligible responses to climate change effects. Moreover, all analyzed species would shift upward in their altitudinal distribution range. The predicted range size contraction of the surveyed genera will vary between 36 to 91 percent, where Acanthophyllum and Thymus will show the least and the most contraction, respectively. Based on our findings, we have provided recommendations for conservation of vulnerable species and sustainable mountainous habitats restorations.