Impact of Overgrazing on Agricultural and Rangelands
Herbivory is the consumption of living plant tissues by herbivores and the term includes grazing, browsing, defloration, seed predation, parasitism and disease (Louda et a/., 1990). Grazing is used in the same sense as herbivory in popular literature but is usually restricted to consumption of living herbage by ruminant livestock. The present report deals with the relationship between the grazing animals and their environment. Practically all vegetation types have grazing animals in them but what matters is the concentration of animals and the corresponding intensity of grazing. The suitability of the vegetation type for providing readily accessible forage and climatic and other related constraints, including landuse economics and pests affect animal abundance. Generally, forest vegetation unless specially converted is not suitable as grazing land and could be more profitably used for cultivation. Most grazing lands are for the above reasons concentrated in subhumid, semi-arid and arid ecologies especially in the tropics. Such lands are also referred to as ragelands and at times in a restricted sense, pastures.