Determining the potential habitat of Astragalus gossypinus Fischer in west region of Isfahan, using ecological niche factor analysis

Astragalus gossypinus Fischer is one of the most important range plants in west region of Isfahan، which is very critical for soil conservation and people''s economic life. Nevertheless، the grazing pressure and overuses cause habitat destruction. This study has been done for determination of its potential habitat in Lenjan and Flavarjan parishes of Isfahan province. To achieve this purpose، spatial data of this specie''s presence used as suitable places for its growth and the environmental condition (Climate، Soil & Physiographic) used for recognition of its habitat''s necessities. Soil data turned to soil maps using antecedent studies and interpolating soil profile points. Climatic and physiographical data have been prepared as well and got ready to be imported to the ultimate model. By importing the information layers in ENFA model and using harmonic mean analysis in Biomapper software; the map of Astragalus gossypinus potential habitat has been created. The results show that gravel percentage، soil potassium، saturated moisture، electrical conductivity and annual precipitation are the most important factors in habitat choosing by Astragalus gossypinus in study area. 25300 hectares of the study site are potential habitat of Astragalus gossypinus which is 16 percent of the study site. To evaluate the verity of this model، Boyce''s index has been used and model rectitude in this test was determined 85. 2 percent.