Procedures used for estimating the botanical composition of the range herbivore's diet include diet observation, utilization techniques, fistula sampling, and fecal analysis. Each of these procedures has important limitations. Direct observation requires minimal time and equipment inputs but accuracy and precision are a problem, particularly with wild animals. Utilization studies are generally unsuitable when plants are actively growing and more than one herbivore is using the area under study. Fistula methods are accurate but are difficult to use with wild animals. In addition they are costly and require considerable time. The esophageal

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Herbivory by wild and domestic ungulates is a chronic disturbance that can have dramatic effects on vegetation dynamics. Herbivory effects, however, are not easily predicted under different combinations of episodic disturbance such as fire, timber harvest, drought, and insect defoliation. This lack of predictability poses a substantial obstacle to effective management of ungulate herbivory. Traditional models of vegetation transition in forested ecosystems have ignored the influences of ungulate herbivory, while research on effects of herbivory have typically excluded other disturbances. Of the 82 contemporary studies on ungulate herbivory we examined, only 15 (18%) considered the interactions of herbivory with episodic disturbances. Moreover, only 26 (32%) evaluated vegetation response to ungulate herbivory beyond the simplistic treatment levels of herbivory versus no herbivory. Only 31 (38%) used a repeated‐measures design of sampling responses over 3 or more time periods. Finally, just 7 (9%) explicitly made inferences to large landscapes such as watersheds, which are often used for management planning. We contend that useful landscape research on herbivory must examine the interactions of ungulate grazing with other disturbance regimes at spatial extents of interest to forest and rangeland managers and under varying ungulate densities and species. We identify herbivory models that could accommodate such information for forested landscapes in western North America. Such models are essential for identifying knowledge gaps, designing future studies, and validating relations of ungulate herbivory on landscapes where episodic disturbances are common, such as those of western North America.

Special recognition is due the following people for their contributions to this study: to Dr. William C. Krueger, my friend and mentor, whose unflagging encouragement and support made graduate study a reality for me; to Dr. Martin Vavra, my thesis advisor, who shared rainy mornings and camp coffee, and gave untiring support to every phase of this research; to Dr. Steven H. Sharrow who shared his considerable knowledge of statistics and served on the thesis committee; to Dr. Edwin D. Strowbridge, who was a member of the thesis committee; to Dr. John C. Buckhouse, who graciously reviewed the manuscript and offered invaluable suggestions for its improvement; to

Impacts of a Iate season livestock grazhq strategy on streambank erosion, morphology, and undercutting were studied for 2 years along Catherine Creek in northeastern Oregon. Streambank loss, disturbance, and undercutting were compared between grazing treatments, vegetation type, and stream-meander position. No significant differences were found among vegetation types or stream-meander location. Significantly greater streambank erosion and disturbance occurred in graxed areas than in exclosed areas during the 1978 and 1979 graxhrg periods. Over-winter erosion was not significantly different among treatments. However, erosion reIated to livestock grazing and trampling was enough to create significantly greater annual streambank losses when com-p8red to ungraxed areas. Vegetation is an important component of the riparian/stream ecosystem (Campbell and Franklin 1979, Jahn 1978). The effects from livestock grazing in these ecosystems have been shown to vary greatly depending upon the nature of the stream studied. Behnke and Zarn (1976), Dehlem (1979), Duff (1979), Gunderson (1968), and Heede (1977) found livestock grazing and excessive trampling caused a decrease in bank undercuts, increases in channel widths, and a general degradation of fish habitat. Buckhouse et al. (1981), Hayes (1978), and Knight (1978) found that stream channel movement did not occur more frequently in grazed riparian ecosystems than in ungrazed riparian ecosystems. In 1978 a study was initiated to examine effects of late season cattle grazing in riparian ecosystems that are separated from upland communities. The objectives of this study were to compare streambank morphology, erosion, and undercutting between areas of streambanks that were grazed under a late season grazing strategy and areas of streambanks that were totally excluded from livestock grazing. Study Area The study area is located on the Hall Ranch, a unit of the Eastern Oregon Agriculture Research Center in the southwestern foothills of the Wallowa Mountains. The study area included a 3 km by 50-m section of Catherine Creek, a fourth order tributary of the Grande Rhonde River, which flows into the Snake River. Catherine Creek has an average discharge of 3.4 ms/ s (119 ftr/ s) (USGS 1981). Peak annual flows usually occur in late April, May, and early June. During the spring runoff period, discharges of over 14.2 ms/ s (500 ft3/ s) are common. Approximately one-half of the streambank has been excluded from grazing by the construction of 5 exclosures alternating with grazed portions of the creek. Prior to the establishment of exclosures, there was a total of 5,473 m of streambank on the study area with 3,492 m considered accessible to livestock use. Accessible streambank is defined as an area where livestock movement was not impaired by steep cliffs, fences, or dense woody vegetation. Stocking intensity before the construction of exclosures was approximately 48-50 m of accessible streambank (MAS) per Authors arc former graduate research assistant and professors, Department of Rangelan...