The effect of large herbivores on plant community composition and structure

Do large herbivores only damage their habitat or can they facilitate plant communities?

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Will the effect of large herbivores be more or less severe with increased aridity?

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Do wild herbivores differ than domestic ones in their impact?

Plant communities in relatively dry regions, such as the Mediterranean basin and the desert region, are often composed of heterogeneous life forms including shrubs, perennial herbs and annuals. These regions are also considered important pasture areas for domestic grazing as well as the landscape in which wild herbivores roam. Since grazing animals tend to prefer herbaceous vegetation over woody ones, it is generally anticipated that the intense grazing will modify plant community structure, causing processes such as shrub encroachment and desertification. However, our previous work indicated that under extreme climatic conditions (e.g. drought), cattle grazing may have a much more complex effect on vegetation and may actually control the abundance of shrubby vegetation in Mediterranean rangelands. This effect is attributed to a climate-driven shift in positive vs. negative interactions between herbaceous and woody plants. We could also show that, in our region, shrubs are much more affected by neighbor interactions than by climate conditions,
Currently, we study whether the same theoretical findings fit the effect of a large wild herbivore in the hyper arid region. In this project we focus on the effect of the Wild Ass ( ), a relatively new reintroduced herbivore in our region, on the natural vegetation of the Negev Highlands.