Assessment of Site and Soil Demands of Carpinus betulus L. in Different Elevation Layers of Arasbaran Forests

Understanding the site and soil demands of the species of Carpinus is of special priority due to the necessity of applying management according to the site conditions and preserving its biodiversity. The purpose of this study is to investigate the site and soil demands of Carpinus as the dominant species and to evaluate the quantitative and qualitative characteristics of its mature and young stands. In this study, 5 circular samples were randomly taken in the four main directions at 700-1000 m, 1000-1500 m, and 1500-2000 m. Soil physical and chemical factors including bulk density, soil pH, EC, CaCO3, organic carbon, soil texture, total soil nitrogen, available phosphorus, available potassium, porosity, saturation percentage and C/N ratio were measured. In each sample plot, all the trees with a diameter of breast height (DBH) of more than 6 cm were measured and their origin and quality were recorded. In the altitude class of 700-1000 m, in the eastern, southern and western slopes, no mature stands were identified. The results showed that there is a significant difference between the average DBH of the trees and the average diameter of the crown of bordering trees in different height classes (α=5%). The most tress with quality grade a (good quality) were observed in the north direction and the least in the southern slopes. The most important soil demands of the suitable site of Carpinus stands were including loam to sandy loam soil texture, high soil carbon, neutral to weak acidic soil pH, available content of nitrogen, phosphorus and potassium nutrients and the C/N ratio of the soil about 10. The amount of soil organic carbon and nitrogen in upper altitude layers (<1500) was higher compared to low altitude levels. The highest average regeneration is in the western slope and the lowest is related to the southern slope. According to the surveys conducted in different altitude classes, the largest DBH in the northern slope is related to the altitude class of 700-1000 m. Also, the largest DBH in the eastern and southern slopes belonged to the altitude class of 1000-1500 m and in the western slope to the altitude class of 1500-2000 m. Furthermore, the highest average number of regenerations was observed in the altitude class of 1500-2000m. It can be concluded that Carpinus in the sites of the northern slopes with an altitude of 700-1000 m, in soils rich in organic matter with loam to sandy loam texture and with high availability of soil phosphorus and potassium has a higher growth and productivity potential.