Effects of land form and soil properties on growth Characteristics of Caucasian whortleberry (Vaccinium arctostaphylos) in Fandoglou forest of Ardabil (Case study: Soha forest)

Caucasian whortleberry (Vaccinium arctostaphylos) is one of the most valuable medicinal shrubs in beech Forests. This study aimed at determining the relationship between vegetation properties of whortleberry with soil and landform index in Soha forest. Sample plots, each 500 m2, were selectively established in three land forms (ridge, valley and hillside) and in four geographical directions (north, south, east and west) from lower to higher distribution areas. Overall, 24 sample plots were used to measure the vegetative characteristics. Soil characteristics including soil texture (clay, silt and sand), pH, Ec, total nitrogen, soil organic carbon and calcium carbonate were also studied in 12 sample plots. The results showed that Caucasian whortleberry distribution varies from 1570 to 1940 meter above sea level. In general, hillsides and ridge forms with south and west-facing hillsides are suitable sites for this species. The highest mean of height (2.19 m), collar diameter (8.7 cm) and crown diameter (1.92 m) were observed on slope land form.  The soil of whortleberry habitats is deep to semi-shallow with pH (5.32 to 6.01), electrical conductivity (0.481 to 0.809 ds/m) and with soil texture loam to sandy- loam. The PCA analysis showed that the physical properties of soil (sand, clay and silt), pH, and soil organic carbon content have important impacts on the presence of this species. From the results of this study, it can be concluded that habitats of Caucasian whortleberry in land forms valley and hillside, and aspects of north and east with light soil texture have created favorable conditions for the growth of this species in the study area.