Journal of Rangeland

In order to identify the most important ecological factors affecting distribution of Daphne mucronata, some sites dominated with this species, including Dezli, Naran and Morvarid saddle were selected in Kurdistan province. Systematic random sampling method was used to collect vegetation data. Coverage percentage, density, height and diameter of each plant individual was studied using nested quadrates (15 × 15 square-meters plots to collect D. mucronata data and 1 m² plots to study understory species) Three soil samples were collected at depth of 50 cm in each 15× 15 plot from below (understory) and between (interspace) shrub canopies. Clay, silt, sand, gypsum, lime, electrical conductivity, pH, phosophorus, calcium, magnesium, percentage of stones, nitrogen, carbon and potassium contents of soil samples were measured in laboratory. Analysis of variance and multivariate regression technique were used to analyze the data. According to the results, soil organic carbon, potassium, pH, magnesium, phosphorus, calcium, lime, nitrogen, clay, sand, average annual rainfall, canopy cover and plant density were different significantly in the identified habitats (&alpha= 1%). Soil silt contents were different in various identified habitats (&alpha =5%) but no significant difference were observed in soil gypsum and electrical conductivity of the identified habitats. Results indicated that D. mucronata preferred northern and western directions and its highest density and cover percentage were found in these directions. According to the regression analysis, 59 percent of the variation in Daphne densities (from 400 to 1600 individuals per a hectare) could be justified by lime percentage (ranged from 9.5 to 32.5 in different habitats). A positive correlation between Daphne vegetation cover with soil nitrogen content was found (r= 0.58).