Horizontal and Vertical Structure of Northern Zagros Forests in Relation to Traditional Forestry System (Case study: Havare- Khol Forests)

Forest structure, as measured by the physical arrangement of trees and their crowns, is a fundamental attribute of forest ecosystems that its measurement can serve as indicators in ecosystem management. In this research, the horizontal and vertical structure of a part of the northern Zagros forests was studied. For this purpose, conventional region forests of Havare-khol village in Baneh city was selected and sixty 20×20 m2 plots in a grid of 200×300 m2 by randomized-systematic method were established in an area of about 345 ha. In each plot, diameter at breast height of all trees and coppices thicker than 1 cm, height of trees and coppices, two crown diameters, crown height and spatial locations of all trees and coppices were measured. SVS software was used to display the horizontal and vertical structure of the forest, and stand statistical indices were analyzed using SPSS software. Distribution of trees and coppices in the height classes showed a two-three storied forest structure in Havare-Khol with the highest abundance in the middle story and the lower abundance in the overstory. The highest distribution of trees and coppices in Havare-Khol forest were within 2-4 m height class and more than 84% of stems had less than 4 m height. Most trees and coppices were less than 10 cm in diameter, indicating a young forest for Havare-Khol with a low diameter distribution range, and a low abundance of thick and old stands in the forest. The horizontal structure of the forest showed large vacant patches and discontinuities of the canopy in the nearest villages that the amount of these empty spots is gradually diminishing as they approach the conventional region border. Also, the vertical structure of the forest shows that in the areas closer to the center of the village the trees and coppice shoots are more concentrated in the middle story and understory, and the greater the distance from the center of the village, the higher the presence of trees in the overstory. Overall, drawing the forest structure showed that with increasing distance from the center of the village, the diameter at breast height, height and area of canopy cover and coppice shoots increased.