Effect of landform and edaphic characteristics on the presence and vegetative traits of Rhamnus pallasii in Andabil forest, Khalkhal region

Rhamnus pallasii is one of 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 in this forest reserve. For this purpose, from 1030 to 2540 m.a.s.l, 48 sample plots of circular shape with an area of 500 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 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 was surveyed by principal component analysis. The results showed that the distribution range of Rowan 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. Soil texture in Rowan habitats is loam to clay- loam with pH (7.4 to 8.1), EC (0.21 to 0.33 ds/m), N% (0.09 to 0.15), OC% (1.14 to 2.25) and Caco3% (14.3 to 23.1) were measured. The PCA analysis showed that the presence of this species in ridge sites with pH, N%, Silt and Caco3 and in slope sites with OC% and silt % was more correlated. In general, Rhamnus pallasii habitats in the southern aspects in the forms of slope and valley with light soil texture have more favorable conditions in term of quantitative characteristics for the growth of this species.