Structural characteristics of Juniperus excelsa in the mountainous forests of Alborz south facing slope (Case study: Atashgah, Karaj)

According to the few basic and applied research related to the structure characteristics of Juniper (Juniperus excelsa)stands in the Irano-Turanian forests and the need for early recognition and proper management of these forests, the present study was carried out to evaluate the structural characteristics of J. excelsa forests located on south facing slope of Alborz mountain chain, Atashgah area, Karaj. For this purpose, systematic network with dimensions of 50×50 m was laid out and coordinates of all trees were determined by distance-azimuth techniques. Canopy diameter was measured in an area about 15.9 hectare in this stand. In order to study the structural characteristics of the stand, nearest neighbors distance index (density of trees), Clark and Evans index and uniform angle index (a variety of location), Mingling index (species diversity), size differentiation index (variety of trees), crown competition factor (competition of canopy trees) between J. excelsa and S index were used in this stand. The results showed that spatial pattern and arrangement of trees were regularly together and variety of trees, was found to be pure without any mixture. The crown competition index was 0.48 (non-unit) representing low crown competition in this stand. Three different aspects of the S index (diversity of spatial pattern, species diversity, and size variety) were 0.227 indicating low levels of tree diversity. The results of this study can be usefully employed for management, preservation, restoration, and development of sensitive and fragile J. excelsa forest ecosystems.