Thesis (Ph. D.)--Colorado State University, 2004. / Includes bibliographical references.

Thesis submitted to the graduate faculty of Chadron State College in partial fulfillment of the requirements for the degree of Master of Arts in Education. / "October, 2008". Includes bibliographical references (p. 59-64). Also available in PDF via the World Wide Web.

Exotic annual weeds have transformed western North America, particularly in sagebrush-steppe systems. Restoration of these invaded sites has been met with low levels of success. Pre-emergent herbicide provides a means to control annual weeds, but typically, this treatment does not allow for the concurrent seeding of desired species. Seeding within a deep, U-shaped furrow following herbicide application may be a method to reduce pre-emergent herbicide effects by transferring the herbicide away from the seed at the time of planting. We tested this potential planting technique by spraying plots with or without the pre-emergent herbicide imazapic, and planting bunchgrass seeds either with or without a deep furrow. Treatments (i.e. spraying and furrowing) were applied using mechanical equipment within a single pass, at six sites. In plots without imazapic, we found that deep furrows generally had higher seedling emergence, density of juvenile plants, and above-ground biomass when compared to no furrows. For plots with imazapic, deep furrows also generally improved measured plant metrics for the seeded species compared to plots without furrows. For example, the density of juvenile plants in deep furrows ranged, by study site, between 62% – 97% and 41% – 89% higher than the no furrow treatment, for plots with and without imazapic, respectively. Plots with imazapic and deep furrows was not always as effective as plots without imazapic and deep furrows. Deep furrows also reduced exotic annual weeds in the first year after planting, but weed reduction was generally more effective when this treatment was applied with imazapic. Overall, this research provides evidence that in most instances, the use of deep furrows alone is sufficient to improve seeding success. However, in areas with high weed cover, the application of herbicide followed by the creation of deep furrows in a one-pass system should be considered.

The Bureau of Land Management (BLM) manages 9.3 million hectares of land in Utah and has implemented an Emergency Stabilization and Rehabilitation (ESR) Program to protect life and property, combat soil erosion, and reduce the invasion of exotic/noxious weeds following wildland fire. In highly vulnerable sites, seeding treatments may be applied to establish an interim landcover to stabilize the soil and competitively exclude weed invasions. Monitoring treatment effectiveness is mandated through ESR guidelines and necessary for the submission of annual Accomplishment Reports for the first three years following fire containment. Ground monitoring has been the traditional approach to fulfilling this ESR monitoring mandate. Ground monitoring of vegetation within a large burn can be complicated or rendered infeasible by the logistical constraints presented by size, topography, and remoteness. The inherent weaknesses of ground monitoring in large remote areas provide the impetus for augmenting these approaches with remotely sensed data. The Rattle Fire Complex (RFC) is a 2002 burn that demonstrates a need and an opportunity to develop a remote sensing-based monitoring tool. This project utilized high spatial resolution Quickbird imagery and ground data to monitor treatment effectiveness and vegetative recovery within the RFC ESR project area and shows that remote sensing and statistical modeling can significantly improve knowledge regarding ESR treatment effectiveness when combined with traditional ground monitoring methods. The image acquisition cost and labor investment may be prohibitive, making this approach feasible only on large, high priority projects. This methodology arguably represents the simplest approach from both a remote sensing and statistical modeling approach and was accomplished using software currently available within the Bureau of Land Management computer network. It is unlikely that current technology can provide a cheaper or simpler alternative. Testing of this methodology on other projects will provide better insight into its utility and transferability.

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. \

Thesis (M.S.)--Oregon State University, 2008-01-15. / Printout. Includes bibliographical references (leaves 31-36). Also available on the World Wide Web.

Thesis (Ph. D.)--Oregon State University, 2007. / Printout. Includes bibliographical references (leaves 95-100). Also available on the World Wide Web.

Graduation date: 2003

Invasive plants can have significant ecological effects. Cheatgrass (Bromus tectorum) is of particular concern in North America, where its competitive nature can seriously degrade natural grasslands. This study, conducted in the White Lake Basin region of British Columbia, investigated the impact of cheatgrass on native plant diversity and the relationship between diffuse knapweed (Centaurea diffusa) and introduced grass cover. The study also analysed the association of cheatgrass with other grass species to provide insight in selecting grass seed composition for seeding after habitat disturbance. Results indicated higher native grass diversity in plots without cheatgrass and in plots containing bluebunch wheatgrass (Pseudoregneria spicata). While diffuse knapweed decreased during the study period, due to biological control, invasive grasses increased. Native grass species positively associated with cheatgrass include needle and thread grass (Hesperostipa comata), Sandberg bluegrass (Poa secunda), and sixweeks fescue (Vulpia octoflora), indicating potential for seeding in disturbed areas prone to cheatgrass.

Thesis (M.S.)--University of Nevada, Reno, 2007. / "August, 2007." Includes bibliographical references. Online version available on the World Wide Web.