Astragalus gossypinus habitat suitability assessment with ENFA model in middle Taleghan Rangelands

Astragalus gossypinus is one of the most important plants covers the mountainous rangelands of Taleghan, Iran. This study provides habitat suitability map for Astragalus gossypinus using ecological niche factor analysis (ENFA) at the middle Taleghan rangelands. For the study, species presence map (120 points) plus a map of environmental variables were prepared. The last map included layers such as gravel, pH, lime, organic matter, N, K, P, sand, clay, silt, slope, aspect and height. Geostatistical methods were used to depict the soil variables maps. The accuracy of the model was 92.3% using the Boyce index. Therefore, the accuracy of the model results is high. Kappa coefficient obtained 0.69 by matching the prediction map with ground truth. This indicated that the ability of ENFA model was good in preparation of the A. gossypinus habitat suitability map. The results of this study showed that A. gossypinus tends to be more distributed with increasing height, depth and organic matter. The species also has a positive response to variables such as lime, slope and north aspect. Value of the marginality, specialization and tolerance obtained 1.708, 2.763 and 0.362 respectively. It can be concluded that the A. gossypinus widespread species which has a good tolerance to environmental variables in the study area. The results of this study can provide arrangements for conservation and restoration of habitats with current or potential distribution of A. gossypinus and help to properly rangeland management.