Investigating the Effect of Animal Grazing Management on Composition and Spatial Diversity Indices (Case Study: Broujen Rangelands, Charmahal and Bakhtiari)

Livestock grazing management is one of the main manifestations of integrated watershed management. Lack of awareness of the effects of livestock grazing on biodiversity makes sustainable watershed management impossible. Therefore, awareness of the variation in plant diversity and composition under natural disturbances such as livestock grazing is important for optimal ecosystem management. This study aims to investigate the effects of different grazing intensity (low, moderate, and high) on spatial diversity components (α-diversity, β-diversity and γ-diversity), turnover and nestedness components of β-diversity and species composition in semi-steppe Broujen rangelands in Chaharmahal and Bakhtiari Province. Vegetation sampling was conducted based on a random-systematic sampling design using 60 plots of 2*2m in three grazing intensities including low, moderate and high. Statistical analysis was performed in R software using “vegan” and “betapart” packages. The results showed that an increase in grazing intensity could significantly (P-value < 0.01) decrease α-, β- and γ-diversity indices, which, in low grazing intensity, were 11.77, 7.22, and 19, respectively, while in high grazing intensity they were 3.44, 3.55, and 7, respectively. In addition, an increase in grazing intensity could significantly (P-value < 0.05) increase the turnover component of β-diversity due to species replacement, while there was no significant effect for nestedness components of β-diversity. The NMDS analysis results showed that different animal grazing could drive a significant deviation in plant community composition. The results of this study suggest that the light grazing intensity could be used as a suitable management tool in order to maintain and improve plant biodiversity.