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Residual Dry Matter (RDM) is a standard used by land management agencies for assessing the level of grazing use on annual rangelands and associated savannas and woodlands (George et al. 1996). Residual dry matter is the old plant material left standing or on the ground at the beginning of a new growing season. It indicates the combined effects of the previous season’s forage production and its consumption by grazing animals of all types. The standard assumes that the amount of RDM remaining in the fall, subject to site conditions and variations in weather, will influence subsequent species composition and forage production. Properly managed RDM can be expected to provide a high degree of protection from soil erosion and nutrient losses. Applications of specific RDM standards based on a limited research base and experience have demonstrated the effectiveness of this approach to grazing management. Because of the limited amount of research information available, standards and score cards normally have to be developed based on local experience and general guidelines such as those that appear in this publication. Numerous agencies have successfully applied the RDM-based method for managing grazing intensity over the past 20 years. Some examples are the Bureau of Land Management and the Natural Resources Conservation Service (BLM 1999), the National Park Service (Shook 1990), the US Forest Service (USDA 1985), and the University of California’s San Joaquin Experimental Range (Frost et al. 1988). (source background)