- Herbivory is a major activity in rangelands and is the basis for cultures, profit making and conservation. Governments, conservation groups and managers are concerned about keeping grazing pressure within certain limits. Identifying when these limits may be exceeded remains a challenge for researchers and managers. New knowledge of plant-animal interactions, practice of managing total grazing pressure and methods for integrating systems involving different herbivore species will be explored in order to identify limits to sustainable grazing pressure. 2003 Taylor & Francis Group, LLC.