A trial was conducted May 1 to September 4, 1989 at the Eastern Oregon Agricultural Research Center (EOARC) Burns, OR to examine the effects of strip or continuous grazing management on the diet and performance of steers grazing native flood meadows. The objective was to determine if strip grazing would be a more efficient means of grazing management than continuous grazing. The experiment was designed to test diet quality, botanical composition of the diet, daily dry matter (DM) intake and performance of yearling steers. Eighty yearling steers weighing 253±17 kg were selected from cattle at the Squaw Butte Experiment Station. The experimental design was a randomized complete block, with blocking based on past forage production. Treatments were continuous or strip grazing. A representative meadow of approximately 22.4 ha was divided into four equal pastures. Continuous grazing steers had access to 5.6 ha pastures for the duration of the study. Animals on strip grazing were confined to an area that was estimated to provide 5-7 days of forage using New Zealand portable electric fencing. Strip sizes were predetermined based on standing forage crop. Steers were not allowed to graze more than 7 days in any one strip. Diet quality was estimated from bi-weekly esophageal samples. Extrusa was collected from 4 esophageal fistulated steers per treatment on two consecutive days. Collections were timed to coincide with the mid point of the strip being currently grazed. Samples were pooled by collection dates and analyzed for CP and IVOMD. Dietary OM intake was estimated from biweekly, 24 hr total fecal collections starting the day following esophageal collections. Total DM fecal output from 6 fecal collection steers per treatment was corrected with the %IVOMD to predict actual DM intake. Diet botanical composition was estimated by microhistological examination of fecal sub-samples. Animal weight gains were recorded bi-weekly. Experimental animals grazed together at all times during the trial. Initial stocking densities were 2.0 AU/ha in each treatment pasture. Steers were counted as .56 AU with 20 steers grazing 5.6 ha pastures. The average strip size over the trial was .46 ha; and depending upon standing crop of forage, ranged from .23-1.15 ha. Record moisture from snowmelt and rainfall resulted in greater than expected standing crop of forage. This growth resulted in under stocking of both treatment pastures. A 1.08 ha block was removed as hay from the higher forage producing strip treatment block to adjust for over abundant forage. This resulted in a total mean strip grazed area of 4.37 ha or 22% less than continuous grazing. Actual grazing density means over the summer were 2.6 AU/ha for continuous and 3.15 AU/ha for the strip treatment. Available forage was determined from clipped plots on a DM basis and expressed as herbage allowance at a given point in time. Herbage allowance for steers in continuous grazed pastures ranged from 405-1153 kg/AU when measured at bi-weekly intervals and 68-186 kg/AU for strip grazed steers when estimated at the beginning of each strip. Grazing pressure was higher for strip grazed steers (.10 AU/kg) compared to continuous (.02 AU/kg). Diet quality declined significantly over the summer (P<.01). Analysis for CP in steer diets provided values of 13.9 vs 10.9% for continuous and strip treatments, respectively. However, this difference was not significant (P=.14). Digestibility analysis suggested that forage in continuous diets tended (P=.07) to have higher IVOMD than strip diets (64.6 vs 60.7%), respectively. Daily herbage intake was similar (P=.42) for both treatments when expressed as a percentage of body weight. Diet botanical composition was positively affected by the type of management system. The amount of the major grass species, meadow foxtail (Alopecurus pratensjs), was increased (P=.05) 39% in the diet of strip grazing steers. Differences were noted in the amounts of other, less frequently occurring grass species. The total amount of grass tended (P=.06) to be higher in strip diets (49% vs 35% for continuous). Rushes (Juncus spp.) and sedges (Carex spp.) contributed a similar percentage to the diets of both treatments. Forbs comprised less than .5% of the overall diet of both strip and continuous steers. Individual animal performance tended (P=.09) to be higher under continuous grazing management. The ADG was 1.16 and .77 kg for steers in continuous and strip grazing, respectively. However, total animal production per hectare grazed area (26.14 vs 22.13 kg/hd) was not considered different (P=.17). / Graduation date: 1991

Reforesting harvested lands in southwestern Oregon has been difficult because of low rainfall, high evaporative demand, and competitive understory vegetation. Herbicides have been a preferred method to control competing vegetation but herbicide use on federal lands was curtailed in 1984. As a result, interest in livestock grazing as a vegetation control method has increased. I used prescribed cattle grazing from 1986-1990 to assess effects on reforestation. Treatments were established on a low-elevation (670 m) site to evaluate seedling survival and growth of Douglas-fir (Pseudotsuga menziesii (Mirbel) Franco.) and ponderosa pine (Pinus ponderosa Dougl.). Treatments were: a) seeding of palatable forage species (SU); b) seeding with grazing (SG); c) no seeding with grazing (NG); and d) no seeding or grazing, with paper mulch applied on Douglas-fir only (PM/C). Year 5 mortality among treatments ranged from 57 to 87% for Douglas-fir and 11 to 25% for ponderosa pine. Porcupine girdling and late-spring frost were major causal factors in ponderosa pine and Douglas-fir mortality, respectively. Competition from understory vegetation, browsing, and trampling were only minor causal factors in seedling mortality. Cumulative growth of both species was best in NG. Severe browsing by cattle in year 2 on SG resulted in reduced year 3 relative growth for ponderosa pine. However, year 2 browsing did not reduce long-term relative growth. By year 5, relative growth for ponderosa pine was greatest in SG and lowest in SU. During years 1-3, soil moisture availability was not enhanced on the grazed vs. ungrazed treatments. However, by year 4, xylem potentials and soil moisture indicated seedlings in SG were less water-stressed than those in SU. Reduced water stress probably resulted from reductions in roots of orchardgrass (Dactylis glomerate L.) because of defoliation. Sampling with a root periscope indicated roots were reduced for defoliated (SG) plants compared with undefoliated (SU) plants. Leaf area and root growth reductions were apparent mechanisms permitting increased soil moisture availability. These results suggested that prescribed cattle grazing can facilitate reforestation. / Graduation date: 1992

Two studies were conducted to determine the factors influencing distribution of cattle on northeastern Oregon mixed-conifer forested rangelands. The objective of the first study was the quantification of differences in distribution of cattle of different ages. Beginning in 1991, and continuing through 2001, radio telemetry collars were placed on a minimum of 30 cattle per year, prior to turnout. Cattle graze the forest from approximately 15 Jun until 15 Oct each year, and were grouped into four age classes: two and three year old cattle (group 1), four and five year old cattle (group 2), six and seven year old cattle (group 3), and cattle eight years of age and older (group 4). The objective of the second study was to determine differences in landscape thermal regimes between riparian and upland areas. Ambient and "black body" thermal probes were placed in a grid pattern in riparian and upland areas at a height of one meter (mid height of a cow), to encompass the entire pasture. For study 1, all groups of cattle preferred areas with shallow slopes (P<0.05), westerly aspects (P<0.05). All age classes of cattle also preferred areas farther from water than the mean distance to water in the pasture (P<0.05) as well as areas with higher quantities of forage (kg/ha) than the mean value of forage production for the pasture (P<0.05). Cattle in age classes two, three and four selected areas with lower percent canopy closure of trees greater than 12 cm diameter, breast height (dbh), than the mean value for the pasture (P<0.05) Cattle in age class one selected for areas of lower elevation and slightly steeper slopes than cattle in age class four (P<0.05). Cattle in age class two were not affected by slope or elevation in their distribution (P<0.05). Cattle in age class three were not influenced by elevation in their distribution, but selected areas of the pasture with shallower slopes (P<0.05). For the second study, the trial was conducted from 5 Aug to 25 Sep in 2001, and from 15 Jul to 1 Sep in 2002. Year was found to be significant (P<0.0001), therefore results from each year were analyzed separately. Each six week grazing period was divided into three-week intervals, and deemed early and late season for each year. Season was found to be highly significant (P<0.0001), and therefore analyzed separately within each year. Least significant means were utilized to determine differences in temperatures. Differences were considered significant at the P<0.05 level for all analysis. Thermal probes were divided into two types within two areas; ambient and blackball, within riparian and upland areas. Analysis conducted examined the differences between riparian and upland ambient and blackball thermal probes. Area and type of probe were both highly significant (P<0.0001) for all classifications, however, there was not an area by type interaction. / Graduation date: 2004

Riparian zones provide habitat for breeding birds in the semiarid western United States; however, there are few data available that address the effects of livestock grazing strategies on riparian habitats and avian communities. Documenting avian community composition in different riparian vegetation communities and relating vegetation communities to livestock grazing strategies may identify management alternatives that are sustainable from a wildlife habitat perspective, and may permit constructive coalitions between agricultural industry and environmental groups. I compared diurnal breeding bird abundance, individual species abundance, and species richness, and vegetation composition and structure among 12 streamside riparian areas of Bear and Silvies valleys in eastern Oregon during 1993 and 1994. Bird and vegetation data were collected along four replicate transects within each of three riparian vegetation communities characterized by vegetation structure: herbaceous, discontinuous willow (Salix spp.), and continuous willow. These riparian vegetation communities were grazed under summer season-long, summer short-duration, and fall short-duration livestock grazing strategies, respectively, >5 years before the study. Differences in riparian vegetation among communities were primarily related to shrub structure by experimental design. The continuous willow community had more shrub cover overall (P<0.001) and within each 1-m height interval from 0-4 m (P<0.013) than the herbaceous and discontinuous willow communities. The herbaceous community had no shrub cover >1 m in height. Willows extended farther (P=0.031) from the steam edge in the continuous willow community than in the discontinuous willow community. No willows were detected in the herbaceous community. I detected 4,016 birds representing 56 species along the transects. Total bird abundance was greater (P<0.001) in the continuous willow community than in the herbaceous and discontinuous willow communities. Species richness was inconsistent (P=0.034) between years within communities; it was greatest (P<0.037) in the continuous and discontinuous willow communities in 1993, and greatest (P<0.003) in the continuous willow community in 1994. Total bird abundance and species richness in 1994 increased with willow volume (r��>0.707, P<0.001). Of 23 bird species with >20 individual detections over both years, 13 species were most abundant in one or two vegetation communities (P<0.088). Seven species (yellow warbler [Dendroica petechia], song sparrow [Melospiza melodia], willow flycatcher [Empidonax traillii], American robin [Turdus migratorius], common snipe [Gallinago gallinago], bobolink [Dolichonyx oryzivorus], and Vaux's swift [Chaetura vauxi]) were most abundant in the continuous willow community. Three species (savannah sparrow [Passerculus sandwichensis], black tern [Chlidonias niger], and American wigeon [Anas americana]) were most abundant in the herbaceous community. Willets (Catoptrophorus semipalmatus) were most abundant in the herbaceous and discontinuous willow communities whereas cinnamon teal (A. cyanoptera) were most abundant in the herbaceous and continuous willow communities. Red-winged blackbirds (Ageliaus phoeniceus) were inconsistent (P=0.032) between years within communities: they were most abundant in the continuous willow community in 1993, and most abundant in the continuous willow and herbaceous communities in 1994. Hydrophytic woody vegetation within semiarid rangeland environments increases structural complexity and is associated with avian abundance and diversity. Yellow warblers, willow flycatchers, and song sparrows, which depend on hydrophytic shrubs for nesting almost exclusively in the semiarid West, are especially threatened by the elimination or simplification of woody riparian vegetation. I suggest that riparian vegetation structure and composition, which is associated with avian abundance, species richness, riparian associate bird species, and landscape-level biological diversity, be maintained where possible. Seasonal light (<30% use) fall short-duration grazing seemed to be compatible with the maintenance of woody riparian vegetation whereas summer season-long and summer short-duration grazing is likely incompatible. / Graduation date: 1995

Graduation date: 2002