Effects of site characteristics and management factors on vegetation distribution in Chadegan experimental range site, Isfahan province

Understanding the behavior of the species in relation with various ecological factors can assist range managers to select appropriate management practices. This study aimed to evaluate the effects of site characteristics and management factors on vegetation distribution in experimental range site near to Zayanderod dam in Chadegan- Isfahan. Some parts of the study area were experienced restricted grazing over the past 20 years. The study area was stratified based on the various management types (grazed and non-grazed) and aspects, and samples were collected randomly in each layer. Four perpendiculars transects with 500 meters length were established along the differences in site and grazing situations. Fifteen plots with size of 1 by 1.5 meters were established along each transect. The cover percentage and density of all perennial plant species were recorded in each plot. The management condition (grazed and un-grazed), slope percentage, aspect, elevation from sea level, and the hillside shapes of the all studied plots were also recorded. Soil samples were collected from 24 established plots randomly and some physical and chemical properties of the collected samples were measured. Canonical Correspondence Analysis (CCA) was used to evaluate the relationships between treatments with the species distribution. Cluster analysis was also used to group the studied plots. According to the results, the plant cover percentage and densities of perennial plant species were increased in the un-grazed sites significantly (α= 5 %). The canopy cover and density of perennial species in exclosure and grazed areas were 43/29 % and 12 plants/m2 and 24/24 % and 7 plants/m2 respectively. Some soil characteristics were modified considerably in the grazed sites in compare with the un-grazed sites. Calcium carbonate and phosphorus soil contents, soil texture, cation exchange capacity and grazing history were identified as the most important ecological and management factors to separate the identified plant species groups in the study area.