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By knowing and taking good care of highland mountainous ecosystems, one can better protect the natural habitats, biodiversity, soil and water of these susceptible areas. In this regard, it is necessary to understand and be aware of the effects of interaction between ecological biotic and a biotic factors on plants as efficient tools in planning and management.
The present research was carried out in Hezarjarib estival rangelands, Zarem rood of Tajan sub- watershed in (Alborz mountains) based on polar ordination (Berry & Curtis) and using Sorenson index in order to figure out the similarities between plant communities of the area which was determined by the floristic-physiognomic method. For better interpretation and understanding of plant distribution pattern, in addition to using isohyetal, height with respect to sea level and aspect maps, at least three soil profiles were studied in the direction of dominant slope to characterize the physico-chemical properties of soil.
In this research, six plant communities were recognized. The above communities were among three groups of shrub land deciduous scrub Carpinus, woodland evergreen Juniperus and cushio grasses formation, based on the ordination. The analysis of the effects of ecological factors showed that with a reduction in rainfall, the Carpinus community was replaced by Juniperus communities and then by cushion-grasses formation ones. Also, this research showed that the ecological niche of the Juniperus communities had steeper slopes, low-depth soils with low amount of organic matter and high sand, gravel and lime percentages. However, the Carpinus community was distributed in deep soils with more organic matter and low percentages of sand, gravel and lime. The cushion-grasses formation communities were located on low and relatively flat slopes. The changes in Ec and pH of the soil were insignificant.