Effects of environmental factors on forage production of Steppe and semi Steppe rangelads in western part of Isfahan province

This study aimed to evaluate the effects of environmental factors on plant species production in some range sites in Isfahan province. Systematic randomized sampling was performed during 10 years (1377-1387). Four and six parallel transects with 400 and 200 meters lengths were established in each of Steppe and semi Steppe sites respectively. Fifteen 1 by 2 meters plots and ten plots with size of 1 by 1 meter were established along each transect in Steppe and semi Steppe regions respectively. The production of plant species were recorded in each plot using double sampling method. Grid layers of bioclimatic and topographic variables were prepared in ArcGIS 10.1 and values for each range site were extracted. Soil samples were collected from range sites and some physical and chemical properties of the collected samples were measured. Canonical Correspondence Analysis (CCA) was used to evaluate the relationships between environmental factors with the plant species production. Cluster analysis was also used to group the studied range sites based on environmental factors. According to the results, minimum temperature of coldest month, annual mean temperature, electrical conductivity, calcium carbonate and sand percentage in steppe region and precipitation of wettest month, annual precipitation, elevation, organic matter and potassium in semi Steppe region were identified as the most important ecological factors affecting plant species production. Maximum of mean plant species production in Steppe was 64.4kg/ha and semi Steppe 144.1kg/ha. Sixty Steppe was from shrub species while grasses composed 56 percent of production in semi Steppe region.