Thesis (Ph. D.)--University of Nevada, Reno, 2008. / "May, 2008." Includes bibliographical references). Online version available on the World Wide Web.

Thesis (M.S.)--Oregon State University, 2001. / Typescript (photocopy). Includes bibliographical references (leaves 57-62). Also available on the World Wide Web.

Thesis (Ph. D.)--University of Idaho, 2005. / Also available online in PDF format. Abstract. "May 2005." Includes bibliographical references.

Throughout the Intermountain West there has been a substantial reduction in both the quantity and quality of sagebrush ecosystems. To ass ist current range management objectives, numerous efforts have been made to classify and map sagebrush communities using remotely sensed data. However, the amount of deta il provided by these broad-scale mapping projects is often limited. This research evaluated the ability of a suite of airborne and satellite imagery to detect sagebrush community structural attributes, specifically percent canopy cover, live cover, density, size-vigor, and spatial arrangement of shrubs. Field data was collected at Camp Williams National Guard Training Facility near Bluffdale, Utah, within a Wyoming big sagebrush community. High-resolution color infrared (CIR) aerial photography, panchromatic, and multi-spectral satellite imagery, including data from Orb image, IKO OS, and Landsat ETM+, were used. Comparisons were made based on the inherent spatial and spectral properties of each image. In addition to the traditional pixel-based method for classifying imagery, a relatively new object-oriented approach to measure sagebrush cover was also explored. Results indicate that the quantification of sagebrush cover can be done fairly accurately in mid-level canopy cover areas regardless of the imagery used. Confidence in the cover estimates did diminish slightly in areas where sagebrush cover was relatively sparse or extremely dense. Not all structural variables were quantifiable using the coarser imagery, due to constraints of spat ial resolution. In these instances the 0.3-meter CIR imagery was exemplified. The object-oriented approach enabled an automatic delineation of the range of variability within sagebrush stands and provided an interesting alternative to measuring sagebrush community structural attributes when compared with the more traditional pixel-based approach. This research was intended to provide a resource for anyone working wi thin sagebrush ecosystems, including rangeland managers, wildlife biologists, or other remote sensors, specifically when decisions related to the appropriate selection of remotely sensed data for some intended management application is necessary. The evaluation of wildlife habitat for sagebrush-obligate species, the direction of fire management strategies and restoration efforts, and the ident ification of appropriate grazing areas are only a few of the potential applications of this work

I investigated how shrub-induced spatial heterogeneity influenced and was manifested by a representative ground-story plant species at a sagebrush-steppe site in southwestern Wyoming. The dispersion of cheatgrass (Bromus tectorum) reflected differences between undershrub (higher plant densities) and interspace (between shrubs, supporting lower densities) microenvironments, hence the population ecology of this annual species served as a biological probe of shrub-associated patch structure in this community. Since cheatgrass is an annual, factors affecting the seed portion of its life cycle were of special interest. First, attributes of the above- and below-ground seed pool were characterized. The environment-wide seed depositional pattern was assessed using seed traps of several designs, and the legacy of seed incorporation into the soil was examined by separating seeds from soil samples. For both components of the seed pool, annuals' seeds predominated. Seeds at the surface were subject to substantial redistribution, moving readilythrough interspace, and their deposition was related to both the interaction of wind and shrub canopies and the presence of litter. More annuals' seeds were encountered in undershrub than in interspace soils; seeds of cheatgrass were restricted to the soil surface. Second, a manipulative experiment tested effects of granivoryfherbivory and presence/absence of a replicate shrub's canopy upon success of cheatgrass plants arising from known numbers of seeds introduced into undershrub versus interspace microenvironments. While biomass of plants in treatments accessible to herbivores was less than that of protected plants, consumers did not affect plant densities, and herbivore effects were not microenvironment-specific . Shrub canopy removal had no effect on plant success, and, contrary to expectations based on the dispersion of indigenous plants, interspace plants fared better than undershrub counterparts. Finally, demographic fates of individually marked seeds were observed, to disentangle effects of microenvironment from effects of microenvironment-specific surface types on determining safe sites. Littered microsites were strongly associated with undershrub microenvironments, and on these surfaces, cheatgrass seeds were less likely to move and to suffer depredation, and more likely to become favorably positioned for subsequent germination and establishment, than on bare ground surfaces typifying interspace. \

Piñon and juniper encroachment and infilling can alter ecosystem processes and decrease resilience and resistance in sagebrush grasslands. Land managers employ a variety of techniques to eliminate these trees and mitigate their negative effects. Mechanical mastication or shredding is an increasingly popular method of removing these trees in Utah. It is a versatile treatment that can reduce canopy fuels, increase infiltration, and reduced sediment loss. We compared vegetation cover for annual and perennial vegetation functional groups on shredded and adjacent unshredded areas across a range of sites. Our approach was to categorize sites by ecological site type (encroachment or tree) and subplots by treatment (untreated, shredded, and shredded-seeded) and initial tree cover. Mixed model analysis of covariance and the Tukey-Kramer test were used to determine significant differences among ecological site type and treatment combinations for each 5% increment of untreated or initial tree cover. Shrub cover was unaffected by treatment and decreased with increasing tree cover. In general, perennial herbaceous understory cover increased after shredding to equal or exceed initial encroachment and infilling levels. This held true for both ecological site types and treatments, even at high pretreatment tree cover percentages. Cheatgrass also increased in cover after tree shredding although this trend was dampened in the seeded treatments indicating some suppression of cheatgrass by seeding. Shredding when there is high cover of perennial herbaceous plants and shrubs or seeding in conjunction with shredding where initial tree cover exceeds 35-40% will help discourage dominance by weeds.

Parker Mountain, is located in south central Utah, it consists of 153 780 ha of high elevation rangelands dominated by black sagebrush (Artemisia nova A. Nelson), and mountain big sagebrush (Artemisia tridentata Nutt. subsp. vaseyana [Rybd.] Beetle) communities. Sagebrush obligate species including greater sage-grouse (Centrocercus urophasianus) depend on these vegetation communities throughout the year. Parker Mountain is owned and managed by Utah School and Institutional Trust Lands Administration, Bureau of Land Management, and the United States Forest Service. Land management on Parker Mountain include wildlife conservation and providing sustainable ecosystem services such as livestock grazing. My research described the species composition of the black sagebrush communities, evaluated the long-term vegetation responses to two mechanical (Dixie harrow/Lawson aerator) and one chemical treatment (tebuthiuron), and herbaceous biomass responses to tebuthiuron treatments in mountain big sagebrush communities on Parker Mountain. My results indicated when black sagebrush canopy cover was <20%, average grass canopy cover was highest (13%). When black sagebrush canopy cover exceeded 40%, grass canopy cover was lowest (8%). Forb canopy cover was relatively consistent (5%) across black sagebrush communities with >20% canopy cover. Communities with <20% black sagebrush canopy cover had the lowest forb canopy cover. Tebuthiuron reduced mountain big sagebrush percent canopy cover (>9 years), increased grass canopy cover, and increased forb canopy cover more than the two mechanical brush control methods. Tebuthiuron treatments shifted sites from xeric to more mesic plant communities, which resulted in increased percent forb cover required by greater sage-grouse during late-brooding. Herbaceous biomass increased under tebuthiuron treatments in mountain big sagebrush pastures. Tebuthiuron treatments also reduced live sagebrush canopy cover for at least 9 years.

Changes in shrubsteppe passerine bird habitat associations in response to disturbance were investigated at multiple temporal and spatial scales. Spatial measures incorporated the effects of area at different ecological scales (nest site, territory, and landscape) to include ecologically meaningful extents. Temporal measures included seasonal and annual effects, and were designed to detect lagged responses should they occur. Local-to-landscape scale effects of mechanical restoration treatments on local extirpation and abundances of nine species indicated most were insensitive to changes in habitat quality, while abundance models showed only broad declines. Changing the availability of nesting habitat on both the attractiveness and quality of an area at multiple extents confirmed the need for long-term study effects due to lagged responses in expressed preference and changes to nesting habitat quality. Time since treatment affected nest success in two of the four species, yet the changes in habitat quality did not forecast changes in habitat preference as expected. Non-adaptive mismatches seemingly occurred as habitat preferences indicated treatments may create benign-appearing 'sink' habitat for species that remained in the area. The umbrella species concept is misapplied at this scale: each species' response was consistent, but responses varied in scale, timing, and direction among species. Patterns of nest density and nest site descriptions demonstrated population-level movement in response to treatments, suggesting half the focal species moved nest sites to remaining habitat areas. Larger scale responsive movements were observed in the remaining species, both out of and into the nest plot. Descriptions of nesting habitat characteristics for the focal species tested if the selected nesting habitat was consistent between pre- and post-treatment, and determined which habitat characteristics, including distance to disturbance, were related to nest success. Descriptions of nesting habitat characteristics support previous work in terms of structural characteristics. Habitat selection was consistent even when the available habitat was not, implying these species choose sites and are not merely settling randomly. However, selected nesting habitat was not strongly tied to nest success at local scales and nest success was negatively related to landscape qualities that treatments were designed to enhance.

The pygmy rabbit (Brachylagus idahoensis) is a sagebrush (Artemisia sp.) obligate that depends on sagebrush habitats for food and cover throughout its life cycle. Invasive species, frequent fires, overgrazing, conversion of land to agriculture, energy development, and many other factors have contributed to recent declines in both quantity and quality of sagebrush-steppe habitats required by pygmy rabbits. Because of the many threats to these habitats and the believed decline of pygmy rabbit populations, there is a need to further understand habitat requirements for this species and how they respond to disturbance. This study evaluated habitat selection by pygmy rabbits in Utah and assessed response of this small lagomorph to construction of a large-scale pipeline (i.e. Ruby pipeline) in Utah. We collected habitat data across Utah at occupied sites (pygmy rabbit occupied burrows) and compared these data to similar measurements at unoccupied sites (random locations within sagebrush habitat where pygmy rabbits were not observed). Variables such as horizontal obscurity, elevation, percent understory composed of sagebrush and other shrubs, and sagebrush decadence best described between occupied (active burrow) and unoccupied (randomly selected) sites. Occupied sites had greater amounts of horizontal obscurity, were located at higher elevations, had greater percentage of understory comprised of sagebrush and shrubs, and had less decadent sagebrush. When considering habitat alterations or management these variables should be considered to enhance and protect existing habitat for pygmy rabbits. The Ruby pipeline was a large-scale pipeline project that required the removal of vegetation and the excavation of soil in a continuous linear path for the length of the pipeline. The area that was disturbed is referred to as the right of way (ROW). From our assessment of pygmy rabbit response to construction of the Ruby pipeline, we found evidence for habitat loss and fragmentation as a result of this disturbance. The size of pygmy rabbit space-use areas and home ranges decreased post construction, rabbits shifted core-use areas away from the ROW, and there were fewer movements of collared rabbits across the ROW. Mitigation efforts should consider any action which may reduce restoration time and facilitate movements of rabbits across disturbed areas.

This research examined the diets of angora goats on a sagebrush bunchgrass rangeland. Research objectives were to 1) determine the effects of a positive conditioning method on both mature and immature angora goats; and 2) to quantify plant selection and provide preliminary information as to the potential for using goats to rehabilitate degraded sagebrush rangelands. Goat diets were ascertained using focal - animal bite-count observations during five consecutive seasons, summer 1990 through summer 1991. Treatment group goats were conditioned for 8 months by including ever- increasing amounts of sagebrush (Artemisia tridentate subspp. wyomingensi) in their daily ration, up to 25% of their total intake. Conditioning effects were evaluated in a rangeland setting by comparing relative amounts of sagebrush consumption between groups. Our results indicate that while conditioning did not significantly impact sagebrush consumption, young animals consumed significantly more sagebrush than adults. Additionally, learning throughout the first year altered dietary selection by the second summer. Both does and kids were primarily gramnivorous, however there was strong seasonality in species preference and a significant age difference in diets selected. Age differences in the plant species selected persisted throughout the study until the summer of 1991 when kids were eighteen months old. / Graduation date: 1993