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Factors hzfluencing distribution of free-roaming cattle were studied on shortgrass steppe in northeastern Colorado. Spatial units selected for grazing were plant communities (soil-plant associations) and a stock-watering area. Regression models of grazing patterns were derived for growing-and dormant-season grazing patterns. Seasonal-grazing distribution was correlated with proximity to water (l/distance) and site-quality indicators. Internal validation of seasonal-grazing models indicated a good flt of predicted to observed patterns. Because ad hoe regression models lack wide applicability, relationships between spatial preference and vegetation properties were investigated. Combined relative measures of forage quality and quantity were good predictors of community preference. Measures of relative biomass or frequencies of forage species were poor predictors of spatlal preference. The high correlation between preference and properties of plants composing the bulk of the diet suggests an interaction between diet selection and selection of grazing areas. The highest correlation occurred between relative community preference and relative aboveground standing nitrogen (crude protein). Animal distribution is considered an important component of livestock management. We have only generalities, no quantitative, predictive knowledge about what factors influence grazing-animal distribution, how those factors change over time, or how distribution is related to nutrition. Systematic investigation of mechanisms behind distribution of range livestock is lacking. Because distribution is traditionally described in terms of use of predetermined zones, areas actually selected by animals for grazing are often not known. Predicting livestock distribution requires precise quantification of behavior and contributing environmental variables. This paper describes a study of spatial patterns of cattle grazing on shortgrass steppe. The objectives of this research were to determine (1) which spatial components of the landscape are selected as grazing habitat by cattle, (2) what factors influence spatial patterns of seasonal or

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Grazing is more than just defoliation of plants. The impact of herbivory affects ecosystem structure and function, both above and below ground. Ultimately, effects of herbivory are expressed to varying degrees at many levels of the ecosystem. Herbivory has been shown to affect plant physiology, morphology, and genetics. Plants have evolved many ways to avoid or tolerate herbivory. Whether plant overcompensate, equally compensate, or undercompensate to herbivory depends on pre- and post-harvest conditions of the plants and their environment. To be important to the manager, the magnitude of compensation must be greater than the inherent "noise" in the system. Natural resources managers use scientific information about herbivory to reduce ambiguity in decision-making in an environment of uncertainty. If an ecological response like compensation is to have practical application for the manager, the meaningful effects must occur on time and spatial scales that the manager can respond to with available resources.