Quantitative and qualitative characteristics of Persian oak along altitudinal gradation and gradient (Case study: Ilam province, Iran)

Quantitative and qualitative characteristics of Persian oak (Quercus persica) were studied in relation to altitude and slope variations in Ilam province. A total area of 1,500 m2 (30 × 50 m) was covered in five altitudinal classes ranging from 800 to 1,800 m a.s.l. Samples were taken based on a systematic random sampling method with 24 sample plots at each class. In total, 120 sample plots (in five classes) were collected covering four gradient categories ranging from < 20 to > 60%. An analysis of variance (ANOVA) was carried out to compare differences between group means in gradient categories and Duncan's post-hoc test was performed to reveal differences between the means of various quantitative characteristics (e.g. growing stock, basal area, diameter at breast height, tree height and regeneration) and the altitudinal classes. The Kruskal-Wallis test was used to examine the differences between the means of qualitative variables and different altitudes and slopes categories. The results indicated that variations with altitudes may have a higher impact than slopes on the quantitative characteristics of the oak stands in the region while the qualitative variables of the native species were influenced by both altitudes and slope variations.