عنوان مقاله [English]
نویسندگان [English]چکیده [English]
Identification of effective environmental factors in distribution and establishment of plant species plays an important role in rangeland ecosystems management. The purpose of this study was investigation of reasons for plant species distribution and relationship between index species in Khorramabad rangelands and physical and chemical properties of soil. At preliminary inspection, vegetation types were separated and the key area of each type was recognized. Four vegetation types were identified as follows: Agropyron libanoticum-Acantholimon bromifolium ،Hordeum glaucum-Taeniatherum crinitum، Astragalus adscendens-Agropyron trichophorum andAstragalus adscendens-Daphne mucronata. The size and number of sampling plots were calculated to be 4 square meters with minimal area method, and 160 based on the statistical formula, respectively. Sampling method in each vegetation type was randomize-systematic, so that, in each plot, vegetation factors were measured, then at the beginning and end of each transect a profile was dug and some physical and chemical properties of soil were measured. Vegetation ordination was done by CCA method and results showed that organic matter, nitrogen, phosphorus, potassium and pH were the most important factors affecting Daphne mucronata distribution. The distribution of Agropyron libanoticum and Acantholimon bromifolium were affected by potassium, soil texture, and EC. As well, soil texture and lime had a decisive role in distribution of Taeniatherum crinitum, Hordeum glaucum, Astragalus adscendens and Agropyron trichophorum.