Effects of grazing on chemical soil properties and vegetation cover (case study: Kojour rangelands, Noushahr, Islamic Republic of Iran).

This research is conducted to study the effects of grazing on chemical soil properties and vegetation cover in three areas separated as the key, reference and critical areas. The study area is located at the river basin of Kojour in the Southwestern of Noushahr (in the North of IR-Iran). Sampling and collecting the soil and vegetation cover data from the site areas are accomplished in the first step of the research. The vegetation cover data was collected in 20 sample plots of 1 m2 in each area. The data was collected through a random- systematic method in the early grazing season. The soil data was collected out of two layers (0-10, 10-30 cm), in two time intervals before and after grazing. Five samples were selected per layer. Some edaphical factors such as organic carbon, percentage of soil organic matters, total nitrogen, absorbable phosphorus and potassium, pH and EC were measured. The results revealed that there is an inverse relationship between the grazing intensity and amount of carbon, nitrogen, soil organic matter and EC. However, a direct relation exists between the grazing intensity and amount of soil potassium, phosphorus, pH and the ratio of carbon to nitrogen. Vegetation in class 1 and 2 which were cereals and forbs had greatest percentage in the reference area. Furthermore, the percentage forage cover increases with the grazing intensity. The more unpalatable vegetation of class 3 forms the prevailing coverage in the critical area. The conclusion of this study shows that overgrazing is considered as a threat for the nutritional elements of soil and vegetation cover.