Qualitative indicators such as soil condition or plant vigority used in some range condition assessment methods decrease their accuracy results.. This study aimed to introduce a quantitative approach to assess rangeland condition using indicator species of grazing pressure impacts. Frequency data of plant species from 31 range sites located in Feridan rangelands- Isfahan with relatively homogeneous ecological condition but different prolonged grazing histories (Low, moderate and high grazing pressure) were collected. Detrended Correspondence Analysis (DCA) was used to identify homogeneous groups in the data set using ISPD analytical package. Some edaphic factors including soil texture, PH, Caco3, gravel percentage, sand components, soil saturation percentage and electrical conductivity of soil samples from two depths of 0 to 15 and more than 15 centimeter from the soil surface of all sites were determined. The correlations of various measured environmental variables against the first axes of Centered Principal Component Analysis (CPCA) were evaluated by Canoco. Once it was confirmed that the place of sites against the first axes of CPCA ordination plot shows a grazing gradient, Gaussian curves were then fitted between the frequencies of plant species with this axes. The species with D- static value of more than 0.5 and R2 of more than 0.3 were identified as grazing indicator species. According to the results, six out of 34 plant species were identified as grazing indicator species. Agropyron trichophorum was identified as a decreaser species and Acanthophyllum microcephalum، Hordeum bulbosum and Veronica arvensis as increaser species and Astragalus verus and Cousinia bachtiarica as invaders. The frequencies of these indicator species determine the range condition justify; LINE-HEIGHT: 80%; MARGIN: 0cm 0cm 10pt; unicode-bidi: embed; DIRECTION: ltr" dir=ltr Key word: Indicator species, Ordination, Index of agreement, Decision Support System, Condition, Semi steppe, Feridan, Isfahan province.
