The Effect of Exclosure Grazing on the Distribution Pattern of Two Important Shrubs in the Central Steppe of Iran

As part of a program to improve management of rangeands, research is being undertaken on the effects of grazing intensity on vegetation communities, including the response of different plant species to long-term exclosure from grazing. Species dispersion patterns can be used as valid indicators for condition assessment of rangeland ecosystems. Landsberg et al. (2002) and Riginos and Hoffman (2003) found that excessive grazing changed the structure and composition of plant communities, increasing the abundance of some species and reducing the presence of others. Heavy grazing leads to the excessive defoliation of herbaceous plants, reducing their biomass, basal cover and plant species diversity (Bilotta et al. 2007). Understanding the response of plants to different grazing intensities is crucial to devising management strategies for arid and semi-arid area which conserve biodiversity and sustain their use (Hoshino et al. 2009). This paper describes the distribution of two important shrub components of local rangelands in Iran