Understanding the effects of gazing on vegetation structure and soil characteristics is important in managing rangeland ecosystems. This study aimed to investigate the plant crown cover and composition changes as well as soil characteristics along a grazing gradient in Kalahroud Steppe rangeland- Isfahan province. The study area was stratified into three sites with respect to distance from village and watering points, including heavily grazed sites (<1 km), moderately grazed sites (1 to 2 km) and slightly grazed sites (> 2 km). Six transects with 150 meters lengths were established in each site. Vegetation characteristics were studied in 15 plots (1×1.5 m²), placed along each transect. 25 soil samples were collected randomly from the placed plots and Caco₃, K, Na, saturated percentage, pH, electrical conductivity and organic carbon contents of samples were measured. Analysis of variance, cluster analysis and non-metric multidimensional scaling techniques were used to analyze the data and explore the relationships of soil and vegetation characteristics along the grazing gradient. According to the results, Artemisia sieberi percentage cover and frequency was decreased while these indices for Peganum harmala increased as grazing intensities increased in the study area. Anabasis aphylla indices were not differed significantly in all the various grazing intensities. Soil Na, Caco₃ and EC were higher significantly in sites under greater grazing intensity while K, SP and OC were lower (α = 5%). Results suggest that moderately grazed sites represent a transitional status in rangeland vegetation and soil dynamics and immediate management action is required to reverse unwanted and hazardous permanent changes. The result of present research can be especially applied to identify ecological thresholds in Steppe rangeland ecosystems.
 

Keywords: Vegetation cover, Soil characteristics, Grazing intensity, Cluster analysis, Isfahan

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