Fereidun Mohebbi - Assisstant professor, West Azarbaijan Agricultural and Natural Resources Research andEducation Center, Agricultural Research,Education and Extension Organization (AREEO), Urmia,Iran.
Behnam Hamzei - Associate professor, Research Institute of Forests and Rangelands, Agricultural Research,Education and Extension Organization (AREEO), Tehran, Iran
Farideh Attar - Professor, Central Herbarium of Tehran University, School of Biology, College of Science,University of Tehran.
Jalal Henareh - Assisstant professor, West Azarbaijan Agricultural and Natural Resources Research and EducationCenter, Agricultural Research,Education and Extension Organization (AREEO), Urmia, Iran.

The purpose of this study is to compare Sir Mountain vegetation in two time periods: ۱۹۹۶ and ۲۰۲۳. Sir Mountain was located southwest and close of Urmia city in ۴۵° ۵´ to ۴۵° ۵۸´ longititude and ۳۷° ۲۵´ to ۳۷° ۳۱´ latitude (northwest Iran). The surface area of Sir is about۵۰۰۰ ha. It’s altitude ranges from ۱۳۵۰ to ۲۳۱۰ m. The field study was carried out by physiognomic-ecological approach. The data were analyzed by Anaphyto. The method this package works is mainly based on the HAC (Hierarchi Acending Classification) and AFC (Analysis Factoryl Correspondance) ordination technics to compare, grouping and ordering of relvés with similar species. ۴۹ sample stands (relvés) were applied for analysis. The study area flora includes about ۳۰۱ species belonged to ۴۸ families and ۲۰۹ genera. We distinguished ۵ associations and a sub association in the area included Lagotetum stoloniferae, Salvieto-Thymetum kotschyani, Stachietosum inflate, Astragaleto- Thymetum kotschyani, Onobrycheto-Thymetum kotschyani and Thymetum kotschyani. The most important ecological factors that determine the plant associations in the area were slope, exposition, human impact and soil texture. Th. kotschyanus was a characteristic element in all ۵ associations determined in the region, but in the ۲۰۲۳ study it was disappeared from most of the area and restricted to small patches with high slopes or inaccessible valleys or large cliffs margins. This indicated the over collecting of Th. kotschyanus by local people who visited the mountain for climbing, tourismand entertainment.

Anaphyto, Thymus kotschyanus, associations, over collecting, Sir mountain