Abstract:

This study, carried out on vegetation of the Gisoum forest reserve with 171 hectares area located 14 km to Resvanshar city, Guilan province, was to examine the structure and composition of the forest vegetation. A first topographic map of the area with the scale of 1:10000 was prepared and the study area was delimited. Transect- quadrate method of sampling was used to record the floristic and phytosociological data necessary for the analysis in about 44 quadrates of 400 m2. Some vegetation parameters viz. density and diameter at breast height (DBH) for trees (over story vegetation) as well as cover-abundance for under story vegetation were recorded, respectively. The life form spectrum of Raunkiaer, the dominant vegetation type of the area, is based on importance value and vegetation structure based on frequency classes, also their chorology caring a central importance in vegetation description were determined. The study of the floristic list showed that 76 species belonging to 66 genera and 45 families existed in the area.The largest families were Asteraceae and Rosaceae with 5 species. Investigation of the geographical distribution of plant species indicated that 44 % belonged to the Europe – Siberian zone. Plant life forms by Raunkiaer method showed that phanerophytes with 35.5 % and hemicryptophytes with 27.6 % were the most frequent life forms. Dominant vegetation type based on importance value index was Buxus hyrcanus-Parrotia persica. Also the evaluation of vegetation structure based on frequency class revealed that abundance-distribution was irregular in under story and regular in upper story vegetation.

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