Soil salinity drives vegetation changes by grazing exclusion in semiarid regions

Understanding the responses of vegetation to grazing exclusion along a salinity gradient is useful for the management of grasslands. We studied the responses of vegetation to grazing removal (ungrazed areas) in three semiarid regions with different soil salinity levels: non-saline, moderately saline and hyper-saline. The results showed that Bray-Curtis dissimilarity between grazed and ungrazed areas were highest in the non-saline region. In the hyper-saline region, the grazing removal had no significant effect on any of the diversity indices, while in the non-saline regions, vegetation changes were occurred by grazing exclusion at the highest magnitude. Generally, the magnitude of vegetation changes by livestock grazing exclusion was decreased along the soil salinity gradient. This research could help to understand how disturbances and stresses interactively influence grasslands dynamics in semiarid regions and to understand the effects of grazing on grassland dynamics and sustainability in deserts in the context of salinization.