Effects of livestock grazing on plant community composition and diversity in steppic rangelands of Boroujen

The aim of this study was to investigate the effects of animal grazing on plant community composition and diversity. Some diversity indices in three grazing treatments (exclosure, moderate grazing and high grazing pressure were compared in steppic rangelands of Borojen, Chaharmahal & Bakhtiari province. Random-systematic sampling method was used and plant species cover were estimated. The α, β, Chanon and Simpson indices of all studied sites were calculated and then compared using one-way analysis of variance. Moreover, the Non metric-multidimensional scaling and Multi-Response Permutation Procedures were used to reveal changes occurred by animal grazing treatments in plant community composition. The results revealed that, although livestock grazing decreased the numerical values of Chanon, Simpson and α diversity, β diversity increased under heavy grazing. A higher β diversity in heavy grazing may be interpreted as providing favorable condition for unpalatable plant species growth which provides more heterogeneity for plant community. Furthermore, results showed that grazing was the main factor responsible for changes in plant community composition. The results indicated that though the exclosure may be an ideal management option, the short-time exclosure (moderate grazing pressure) is also likely to restore plant community composition and diversity.