From the Introduction...'Ecologic and economic benefits of prescribed burning have been documented for many rangeland ecosystems. However, increased attempts to use fire have been accompanied by an increased number of failures. Failures are fires that fail to carry, or fires that are of insufficient intensity to satisfy burning objectives. For example, some fires do not generate enough heat to ignite and consume chained woody debris, and other fires do not produce sufficiently long flames to kill elevated buds on shrubs or trees. Further, fires that fail are expensive because fireline preparation, usually the largest direct cost of burning, is completed before the failure of a fire. Failures also disrupt management plans, and delay implementation of alternate treatments. Fires may fail for several reasons. First, an improper combination of weather factors may have been used such as high relative humidity with low wind speed. Second, an insufficient, or unsatisfactorily arranged, fuel load may have been present. Third, the fire may not have corresponded with the proper stage of plant phenological development, resulting in an attempt to burn with excessive green material in the fuel bed array. These problems have been largely ignored for grasslands. Much of the published literature on fires in grassland fuels deals with wildfire behavior. Wildfires, however, often occur with weather and fuel conditions that are beyond safety limits for conducting prescribed fires. Grasslands with 340 kg/ha of fine fuel may burn readily under wildfire conditions but are difficult to burn safely under prescribed conditions. Thus, to conduct satisfactory prescribed fires in grasslands, information is needed on (1) the threshold weather and fuel conditions that allow fire to carry, (2) how fires that are successful behave, and (3) simple, field-oriented methods for practitioners to predict success or failure, and fireline intensity, so that the fire will safely fulfill objectives of burning.'