Effects of rangeland exclusion on plant cover and soil properties in a steppe rangeland of Southeastern Iran

The study was conducted in Taftan rangeland in Sistan and Baluchestan, Iran, to study the effects of grazing exclusion on reclamation of vegetation cover and soil properties. After a comprehensive assessment of the vegetation types, plant sampling was carried out in sampling stands (50 x 50 m). In each stand, vegetation properties were measured using simple transect lines (50 m) method within quadrats (5 x 5 m), with a systematically randomized method. Soil sampling (75 samples) was performed along transects from the surface layer (0-30 cm). Results showed that livestock exclusion significantly affected community characteristics. The species richness (14.32), diversity (2.97), and plant cover (65.14%) showed their maximum level in the 15-year exclusion. The soil nutrient content increased during exclusion. Organic carbon (4.20%), total nitrogen (1.12%), available potassium (393.33 mg kg(-1)), and available phosphorus content (17.13 mg kg(-1)) attained significantly greater values under the long-term exclusion. The soil pH level (8.93) was significantly higher in the overgrazed site compared to the grazing exclusion sites. The soil electrical conductivity was statistically similar under the three treatments. The amounts of silt (63.40%) and clay (14%) were greater in the long-term exclusion compared with overgrazed rangeland. The long-term exclusion showed the lowest amount of sand (22.50%). These results imply that livestock exclusion plays an important role in vegetation restoration and soil conservation of degraded ecosystems in arid regions. We suggest that more studies are required to investigate the effect of livestock exclusion on ecosystem process in the arid rangeland regeneration.