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The response of English yew (Taxus baccata L.) to climate change in the Caspian Hyrcanian Mixed Forest ecoregion

Alavi, Seyed Jalil, Ahmadi, Kourosh, Hosseini, Seyed Mohsen, Tabari, Masoud, Nouri, Zahra
Regional environmental change 2019 v.19 no.5 pp. 1495-1506
Taxus baccata, algorithms, climate change, climate models, climatic factors, coasts, ecoregions, endangered species, geographical distribution, habitats, mixed forests, trees, uncertainty, Caspian Sea, Iran
The Hyrcanian climate in the northern parts of Iran has warmed over the past 50 years, but the impacts on plant species are unknown. As the longest-lived tree in the Hyrcanian forest, English yew, Taxus baccata L., is a rare and endangered species in the forests along the Iranian coasts of the Caspian Sea, which is likely affected by climate change. This paper explores the current and future distribution of this species, using four species distribution models. In order to project the effect of climate change on the distribution of English yew by 2050 and 2070, output from the HadGEM2-ES climate model was used for two RCPs scenarios (2.6 and 8.5). The results showed a good accuracy of all the models for the distribution of this species with a mean area under the receiver operating curve (AUC) of 0.92. Using ensemble forecasting as an algorithm for reducing the uncertainty in species distribution modeling shows that the suitable habitats for this species is about 6000 km² for the current climate conditions in the study area. Range size analysis indicates that in 2050, in the most optimistic scenario (RCP 2.6), only 17% of the habitats will retain their suitability, while in the most pessimistic scenario (RCP 8.5), this amount will decrease to 2%. In 2070, in the most optimistic scenario, only 10% of the currently suitable habitats will retain their suitability, while in the RCP 8.5, no stable suitable habitats will be left. It is strongly recommended that the impacts of climate change on English yew should be considered in the management decisions and conservation plans in the Hyrcanian forests.