determination of indicator species of some soil characteristics by ordination method in kooh -e- namak rangelands, qom

with regard to the mutual relations between plant and soil as the main component of rangeland ecosystems, this research has been identified the indicator species in environmental conditions of dry regions as the most important tools in ecological management of these ecosystems. therefore the steppe and dry rangelands of kooh - e- namak in qom province was selected. sampling was done by plot in each land unit randomly after determination of equal land units. size and number of plots were determined by minimal area and statistical method respectively. after identifying the plants in each plot canopy cover percentage and topographic characteristics of these poits was recorded. then, soil samples were taken from two depths (0–20 and 20–50 cm) in each unit by digging of soil profile. ec, ph, caso4, caco3, sar and texture were determined in lab. finally, data analysis was done and relation between species and soil parameters was obtained by ordination techniques, dca and cca. the results showed that soil salinity and texture are the main limiter factors of plants growth in this region. only stipagrostis plumosa and tamarix aphylla had positive reaction to saline and sandy soils respectively. also, the species in degraded zones hadn’t distinct reaction to edaphic parameters and appeared as a separate ecological group.