Soil and plant attributes under grazing exclusion in semi-steppic semi-arid rangelands, Iran

The aim of this study was to investigate the effect of exclusion (20 years) on the attributes of soil and vegetation in northwest of Iran. Three sites in grazed and three sites in exclusion areas were selected. At each site, three 100 m transects were established for sampling purposes. Soil attributes, including electrical conductivity, pH, calcium carbonate, organic carbon, nitrogen, phosphorus, potassium, clay, silt, calcium, magnesium, and bicarbonate were measured in the lab. Additionally, the primary and secondary attributes of vegetation including density, canopy cover, aboveground net primary production (ANPP) of plant functional types (PFTs), diversity, richness and evenness indices were recorded. The findings of our study indicate that the exclusion site exhibited significantly higher levels of soil organic carbon (1.91%), total nitrogen (0.95%), available phosphorus (1.75 ppm), and soluble potassium (163.52 ppm) compared to the grazed site. However, no significant differences were observed in other soil characteristics between the two sites. Density, canopy cover percentage, ANPP of PFTs (p < .01), diversity (1.92), and richness index (9.64), were higher in the exclusion area (p < .05), while, evenness showed no significant difference. The total species density and canopy cover within the exclusion area were also found to be higher than in grazed areas. Results suggest that exclusion in semi-arid semi-steppes plays an important role in rangeland management.