The effect of grazing on the richness and make-up of herbaceous plant species in Israel – an improvement or suppression?
Niv De Malach, The Department for Ecology, Evolution and Behavior, The Hebrew University in Jerusalem. firstname.lastname@example.org
Hila Segre, The Faculty for Architecture and Town Planning , the Technion, Haifa. email@example.com
Keywords: cereals, disturbance, annuals, nitrogen, species diversity, ruderal species, pasture, nutrients, richness of species, herbaceous, broad-leaved
This article summarizes the results of studies that examined the effect of grazing on the richness of herbaceous species in Israel. The studies were held in the Galilee, the Golan, the Carmel, the Judean Valley and the Negev, and included the effects of cattle grazing and sheep and goat grazing. The results demonstrate that the most important factor in determining the reaction of the plant species to grazing is its height. Grazing raises the relative incidence of short species, including geophytes and annual species (in particularof the Leguminaceae, Cruciferae, and Asteraceae families), and reduces the relative incidence of tall species. In most cases grazing increases the richness of species by preventing the competitive exclusion of short species, which means that grazing can serve as an important management tool for preserving the extensive biological diversity of plants in Israel. Nevertheless, under certain conditions, such as southern exposures, grazing does not raise the diversity of species, and in certain locations, such as enclosures and troughs, grazing leads to the domination of ruderal species, and thus reduces the richness of species. It is therefore important to take into account the conditions of the habitat when one lays down a management policy, and to match the extent and nature of the grazing and its pressures to the local conditions.