An Investigation on the mutual effects of grazing pressure and topography interactions on plant forms, range condition and trend changes (case study: Vezvar rangelands of Galougah)

Abstract Due to the importance that the knowledge of the relationship between vegetation and environmental factors bears in range management, this research has been dedicated to the investigation of the effect of two factors, namely grazing pressure and topography on some vegetative characteristics in the Vezvar rangelands of Galougah. To this end, the information layers of slope, aspect, altitude and lithology were firstly provided using Geographic Information System (GIS). Then, geomorphological land units were determined by intersecting the overlaid data layers. For sampling, land units with similar lithology and altitudes but with different slopes and aspects were selected. The areas under normal and intensive grazing were obtained in each unit and sampling was done using 30 random 1 m2 plots per land unit. Vegetative and topographic characteristics were then recorded in each plot. Finally, data analysis was carried out through variance analysis and the Duncan test using SAS 9.1. The results revealed that grasses had a high response to intensive grazing and forbs and woody plants to topography. Overall, the effect of intensive grazing on vegetation was the same in all of the topographic conditions. On the other hand, slope and aspect acted as limiting factors and had a more distinguished effect on rangeland trend and condition.