The importance of climatic, topographic and edaphic variables in the distribution of yew species (Taxus baccata L.) and prioritization of areas for conservation and restoration in the north of Iran

Taxus baccata is an indigenous and valuable species of Hyrcanian Forests. According to recent studies, the presence of this species in the areas where distribution is declining; therefore, preserving and restoring this valuable species is essential. One of the most strategies for conservation and rehabilitation of valuable species is identification of its potential distribution and prioritization of areas with potential of presence of species using species distribution models. The purpose of this study was to prioritize desirable habitats for preservation and restoration of yew in Hyrcanian forest. In this study, the Boosted Regression Tree (BRT) algorithm was used to model the distribution of yew species in relation to climatic, edaphic, and topographic variables and identification of the most important variables affecting the distribution of yew. The results showed that the model constructed with climate variables in terms of model evaluation criteria by average of TSS (0.83) and AUC (0.97), has better performance in comparison to edaphic and topographic models. Also, among the climate variables, mean temperature of driest quarter and precipitation of warmest quarter has the most effect on the distribution of yew species. Soil organic carbon, sand percent, cation exchange capacity, altitude, and slope percent were also other important factors affecting the distribution of yew species. Finally, by combining the suitability maps of climatic, topographic, and edaphic models, a map of the priority of conservation and restoration of yew species was prepared, which is very valuable in planning for restoration of this species in Hyrcanian Forests.