Ecology of Iranian Forest

Extended Abstract
Background: Forest management achieves its goals by considering the natural state of the forest and possessing sufficient knowledge regarding the ecological characteristics of forest species, as well as the current state of forest structure and monitoring changes resulting from management activities. This research was conducted to assess the existing structural conditions in the Tang Dalab forest area, focusing on two aspects: northern and southern.
Methods: In the center of the northern and southern sites, a square sample plot of one hectare (dimensions 100 x 100 meters) was permanently established. All trees and coppice shoots within this area were numbered and recorded, and the structural variables of all the trees in the sample plot were measured. To compare the averages of the investigated variables in both sites, we conducted a t-test after testing for the homogeneity of variances and the normality of the distribution of the variables.
Results: The results indicated that the southern stand, with a density of 72 Persian oak trees (Quercus brantii Lindl) per hectare, was entirely composed of seedlings, classifying its forest type as Quercus brantii Lindl. In contrast, the northern stand had a density of 57 trees per hectare, with 82% of them being seedlings, and its forest type was identified as Q. brantii - C. azarolus. The results of the t-test revealed significant differences in all studied variables between the southern and northern stands at a 1% probability level. The average diameter at root collar (DRC), diameter at 0.5 m height, and diameter at breast height (DBH) of trees in the southern stand were greater than those in the northern stand. The distribution of trees across diameter classes in the southern stand indicated an irregularly even-aged structure. The diameter distribution chart for this stand showed a lack of regeneration in recent years in the northern stand. In addition to coppice and young Persian oak trees in the lower diameter classes, several young trees of other species with small diameters were also observed. The height distribution diagram of trees in the southern stand demonstrated that the largest number of trees fell within the height classes of 5 to 11 meters. Conversely, the northern stand primarily featured coppice trees in the lower height classes (less than 3 meters), while over 80% of seedling trees in the southern stand had heights between 6 and 11 meters. The investigation of the basal area at 0.5 m height for trees in both stands revealed that this variable in the southern stand (26.41 square meters) was more than three times greater than that of the northern stand (7.48 square meters), attributed to the presence of seedlings and higher density.
Conclusion: The superiority of the southern group over the northern group demonstrates that aspect plays a significant role in influencing vegetation and forest structure. In sustainable forest management planning, it is crucial to monitor the structure of forest stands over time—ideally, at least every ten years—while paying special attention to the varying conditions of aspect. This approach is essential for preserving, revitalizing, and developing these forests effectively.