The effects of exclosure on vegetation and soil chemical properties in sisab rangelands, bojnord, Iran

Overgrazing and overall utilization of rangelands have caused vegetation and soil degradation in the most of rangelands of Iran. Exclosure is one of the rangelands rehabilitation methods, which is effective in renovation of rangelands. In order to evaluate the effect of exclosure on vegetation and some soil chemical properties, the present study was carried out at Sisab Research Station in semiarid rangelands of north Khorasn province. The Station had been exclosured for 22 year and was compared with grazed neighbor area. The vegetation cover data was collected from 30 1m 2 quadrates in each area along 3 100m transects through random-systematic method. The soil data was sampled from two depths 0-15, 15-30 cm and five composite samples was collected (each sample was a mixture of six samples) from each depth in each area. Some factors such as the organic carbon, the percentage of soil organic matters, total nitrogen, absorbable phosphorus, pH and EC were measured. The results showed that carbon, nitrogen, soil organic matters and EC decreased by grazing, but pH was increased Also phosphorus and C/N were not significantly different (P<0.05). The results of vegetation cover data showed that total canopy cover in exclosure was more than that of outside (P<0.05). Also forbs and decreasers plauts had the most vegetation cover in exclosure.