Effect of landform and edaphic characteristics on the presence and vegetative traits of Buckthorn (Rhamnus pallasii) in Andabil forest, Khalkhal region using PCA analysis

Rhamnus pallasii is one of the most important and valuable species in Khalkhal forest area. This study aimed to determine the relationship between vegetation properties of Rhamnus pallasii with soil and physiographic factors using PCA analysis in this forest reserve. In so doing, from 1030 to 2250 m.a.s.l, 48 sample plots of square shape with an area of 400 m2, in three land forms (ridge, valley and slope) in four aspects (north, south, east and west) were selectively determined and quantitative characteristics of Rhamnus pallasii such as total height, collar diameter, crown diameter, shoot and regeneration were measured. In addition, in each sample plot, a mixture soil samples were collected from 0 to 30 cm and some of its physical and chemical properties were measured in the laboratory. In order to study the relationship between Rhamnus pallasii distribution and soil characteristics, a survey was done by principal component analysis. The results showed that the distribution range of Buckthorn varies from 1030 to 2250 m.a.s.l. In general, hillsides and valley forms with south -facing hillsides are suitable sites for this species. The highest mean of height (1.74 m), collar diameter (5.65 cm) and crown diameter (1.75 m) on slope land form and number of regeneration in sample plots (7.4) were observed on valley land form. Results from PCA analysis revealed that in the altitude range of 1030 to 2250 m.a.s.l, the soil texture, especially sand% and silt%, OC% and N% were more suitable conditions for the presence and growth of this species in valley and slope forms in the southern aspects area provided. The results of this study can be used to describe ecosystem sustainability as well as conservation and reforestations such as planting with this species and modifying the structure of deforested forests in the studied areas.