Effects of Livestock Grazing on Vegetation Composition and Soil Moisture Properties in Grazed and Non-Grazed Range Site

Abstract

"Studies of vegetation and soil dynamics on grazed and non-grazed rangelands are important prerequisites for improving range management. For this reason, the effects of excluding grazing animals for 26 years were studied on vegetation and soil dynamics at two rangeland condition sites (enclosure and exclosure) in Isfahan province, Iran. The vegetation cover and edaphic characteristics were studied simultaneously in both grazed and non-grazed range sites. In this study vegetation characteristics, as well as vegetation floristic, canopy cover, plant density, botanical composition, plant biodiversity and soil moisture infiltration were recorded during the grazing seasons of 2006 to 2007. Vegetation characteristics, in particular vegetation cover and plant density, differed significantly between the non-grazed (enclosed) and grazed sites and increased significantly in the non-grazed range site. The vegetation cover in the non-grazed site consisted mainly of class I and II plants while class III plants predominated in the grazed site. There was no significant difference in the botanical composition of the two areas. There was a significant increase in Gramineae in the enclosure site compared to the surrounding grazed site, but there was a considerable decrease in forb species. We also observed a significant decrease in soil infiltration rates in the grazed range site compared to the enclosed range site. Litter content was higher inside and exposed bare soil greater outside the enclosure. Infiltration rates were higher in the enclosed area than in the grazed exclosure area throughout the grazing season. A comparison of vegetation and soil infiltration within the enclosure showed that vegetation condition and soil infiltration were good and that removal of grazing animals, as in the enclosure, causes an improvement in rangeland condition in this region."