بررسي فلور، ساختار رويشي و كورولوژي عناصر گياهي اجتماعات توس در سنكده ساري

Study on vegetation structure, floristic composition and chorology of silver birch communities at Sangdeh,forest of Hyrcanian region

The sangdeh rocky forest where is located at southern part of Sari city ( center of Mazandaran province) is one of the special ecosystems of the high altitude forests of Caspian region due to its special ecological characteristics and its unique vegetation type such as Betula pendula Roth. communities. The plant diversity at this ecosystem, creates a unique biological environment and feature on the north slopes of Alborz mountain chains. The vegetation was studied to identify and introduce the flora, determine chorologically the plant elements and define their structure. As a result, 181 species, 129 genera and 52 families were determined. The most important families were Rosaceae, Asteraceae, Poaceae, lamiaceae and caryophyllaceae wich contain 41 percent of the total species Hemicryptophytes, Phanerophytes and Cryptophytes were the most important structure groups of the local biological spectrum according to Raunkiaer Method, whereas according to Suzuki and Arakane Method caespitose Hemicryptophytes, Rhizom-Geophytes and broad leaved decidous shrubs were the most important life forms. The chorological study and identifying the chorotypes according to Zohary Method, showed that in that part of the Caspian (Hyrcanian) forests, most of the species belonged to Hyrcanian phytogeographical region whereas the least species belonged to phytogeographical Regions= Irano-Turanian and Irano turanian-Hyrcanian. Only 33 species were endemic of Iran which contain 1.9 percent of the total endemic species of the country’s flora.