Quantitative and qualitative characteristics of Arasbaran Forest Protected Area in slope gradient classes

Knowledge on forest stands is crucial for forest ecosystem management. This study aims at investigating some quantitative and qualitative characteristics of Arasbaran Forest Protected Area in different slope gradient classes. For this purpose¡ circular plots of 400 square meters at 50-meter elevation intervals were established along three to five altitudinal transects¡ 100 meters apart from each other¡ from the lowermost altitude (1¡100 m a.s.l.) to the uppermost (1¡725 m a.s.l.) forest limit. In each sample plot¡ the physiographic conditions¡ including slope gradient¡ altitude and geographic coordinates were determined. Woody plant taxa were identified at species level and the diameter of all trees (above 7.5 cm diameter at breast height)¡ the height of the thickest tree and the closest tree to the center of each plot¡ the origin¡ the health status¡ the number of stems¡ and the tree leaning were measured. The frequency of regeneration of each species taller than 1.30 m in three diameter classes (0-2.5¡ 2.5-5 and 5-7.5 cm dbh) and shorter than 1.3 m in three height classes (0-10¡ 10-50 and 50-130 cm) were examined within 100 m2 (10 x 10 meter) sample plots inside the main plots as well. Our results showed that common hornbeam (Carpinus betulus) oak species (Quercus petraea and Q. macranthera)¡ and field maple (Acer campestre) played the most important role in terms of abundance (i.e. 93.3%) in forest composition in the area. The average number of stems¡ basal area¡ number per hectare of regeneration¡ and percentage of seed-origin regenerations were highest at medium slope gradient class (36-50%).