Index Catalog // ScholarsArchive@OSU

Competition release and climate change effects on a moisture-demanding tree species in a dry system

Creator:: Seager, S. Trent
Abstract:: Climate change and the increase in meteorological drought have generated global concern over the persistence of ecosystems already in decline from decreased moisture. Evidence suggests dryland ecosystems have been more impacted by drought because of their tightly coupled growth-water relationships and high sensitivity to environmental shift. Removal of competing vegetation...
Resource Type:: Dissertation

Associations Between Crested Wheatgrass and Native Vegetation in Southeastern Oregon : An Investigation of Co-establishment, Environment, Seeding History, and Livestock management

Creator:: Nafus, Aleta M.
Abstract:: Crested wheatgrass (Agropyron cristatum [L] Gaertm), an introduced bunchgrass, has been seeded on over 5 million hectares of degraded rangeland in western North America because it establishes more readily than native bunchgrasses. Because crested wheatgrass stands are associated with native species displacement and low biological diversity, there is substantial interest...
Resource Type:: Dissertation

Farmer perspectives on success and challenges : a study of small farms in Oregon's Willamette Valley

Creator:: Pool, Kristin E.
Abstract:: This thesis investigates the success of and challenges facing small farmers operating direct marketing farm businesses in Oregon's Willamette Valley. This qualitative study utilizes participatory methods to gain the unique perspectives of small farmers regarding their success and challenges. Small farms are important players in local food systems and ensuring...
Resource Type:: Masters Thesis

Geographic variation in distribution and cover of principle native and non-native plant species along gradients of topography, climate, and disturbance in protected-area sagebrush steppe communities of the Columbia Plateau

Creator:: Esposito, Daniel M.
Abstract:: The sagebrush steppe ecosystem of the Columbia Plateau has become degraded by a long history of alternative land use and associated perturbations. Protection of remnant stands of intact sagebrush steppe currently relies upon their preservation within the nation's network of parks and protected-areas. The John Day Fossil Beds National Monument,...
Resource Type:: Masters Thesis

Optimal spatial-dynamic resource allocation facing uncertainty : integrating economics and ecology for invasive species policy

Creator:: Hall, Kim M.
Abstract:: The spatial and temporal behavior of invasive species spread implies that optimal management strategies involve decisions over space and time. Dispersal and propagule pressure are two primary drivers of the spatial-temporal ecological process of species invasion. In the case of riparian communities, stream flow drives the dispersal of vegetation propagules....
Resource Type:: Dissertation

Role of propagule pressure and priority effects on plant establishment during restoration of invaded shrub-steppe

Creator:: Schantz, Merilynn C.
Abstract:: Biological plant invasions are diminishing the ecological integrity and function of ecosystems worldwide. A primary example of this is in the Great Basin of the United States, where invasive annual grasses, like cheatgrass (Bromus tectorum L.) and medusahead (Taeniatherum caput-medusae L. Nevski), are dominating many sagebrush-steppe ecosystems. In these invaded...
Resource Type:: Dissertation

An evaluation of biological control of Linaria dalmatica with Mecinus janthinus in Oregon

Creator:: Park, Alexander
Abstract:: Dalmatian toadflax (Linaria dalmatica) has become a prolific invasive plant of rangelands in Oregon since its arrival in the early 20th century. In 2001, the Oregon Department of Agriculture initiated a release program promoting the distribution of the stem-boring weevil, Mecinus janthinus as classical biological control agent to reduce densities...
Resource Type:: Masters Thesis

Characterization of Triticum turgidum ssp. carthlicum (Nevski) Löve et Löve by discriminant analysis

Creator:: Vieira, Luiz Gonzaga E.
Abstract:: Forty-six morphological characters were used in a study of Triticum turgidum ssp. carthlicum (2n = 28) and specimens of carthlicum-like forms of Triticum aestivum ssp. vulgare (2n = 42). The morphological variation patterns within these groups were examined using stepwise discriminant analysis. These results indicate that specimens studied could be...
Resource Type:: Masters Thesis

Nutritional value of several Opuntia species

Creator:: Ben-Thlija, Abdellaziz
Abstract:: Little is known about cactus nutrients, their proportions in different species and the variability of these proportions with season. In the scant literature available on Opuntia species, no systematic survey has been published to document and compare the nutritional qualities of different species. Also, no studies have been done to...
Resource Type:: Masters Thesis

Influence of silvicultural treatments, overstory, and understory vegetation on quaking aspen (Populus tremuloides) regeneration in southeastern Idaho

Creator:: Muñoz, Bethany L.
Abstract:: Quaking aspen (Populus tremuloides Michx.) is known to be a widely distributed, shade-intolerant and short-lived hardwood found in both seral, even-aged and stable, uneven aged stands. There have been reports of extensive aspen mortality, crown thinning, and branch dieback across North America that have been linked to the occurrence of...
Resource Type:: Masters Thesis

Experimental reintroduction of northern wormwood (Artemisia campestris var. wormskioldii), a rare species of dynamic cobble bar environments on the Columbia River

Creator:: Brickner, Alexis H.
Abstract:: Rare plant reintroductions that result in additional or more viable wild populations are important conservation tools for maintaining biodiverse ecosystems. Ideally, such projects are best designed as experiments, to improve biological and ecological knowledge of the selected species and monitoring long-term results. Northern wormwood (Artemisia campestris var. wormskioldii: Asteraceae), a...
Resource Type:: Masters Thesis

Models of a four-species annual weed community : growth, competition, and community dynamics

Creator:: Roush, Mary Lynn
Abstract:: Models of weed communities aid in the development of weed management strategies and elucidate the processes and mechanisms that regulate plant populations and communities. A conceptual weed community model was developed to organize key regulatory life-history processes. Specific investigations focused on the processes of plant growth and competition, and relationships...
Resource Type:: Dissertation

Growth characteristics and site potentials of perennial grass species

Creator:: Borman, Michael M.
Abstract:: In this study I assessed the potentials of selected, established perennial grasses to maintain site occupancy in the foothills ecosystem of the Rogue River Valley of southwest Oregon which is currently dominated by a variety of annual plants. The first evaluation compared growth curves of the perennial grasses and contrasted...
Resource Type:: Dissertation

Growth responses of Douglas-fir (Pseudotsuga menziesii [Mirb.] Franco) to defoliation

Creator:: Osman, Khalid Amir
Abstract:: The effect of defoliation intensity and season on Douglas-fir growth were studied in three replications in the Siuslaw National Forest during 1988-1990. Four intensities of defoliation were applied once in either spring or summer 1988. Stem diameter and canopy area were linearly inversely proportional to the level of defoliation. Defoliation...
Resource Type:: Dissertation

The feasibility of using diploid by tetraploid crosses to obtain triploid hops (Humulus lupulus L.)

Creator:: DeNoma, Jeanine Streeter
Abstract:: The hop (Humulus lupulus L.) is a dioecious, diploid (2n=2x=20) species. Triploid hops (2n=3x=30) are easily obtained from tetraploid by diploid crosses and are preferred because of their natural seedlessness and increased vigor. The female inflorescence is used for flavoring beer. Because brewers require product consistency, the brewing characteristics of...
Resource Type:: Masters Thesis

Demography of medusahead on two soil types : potential for invasion into intact native communities

Creator:: Miller, Heather C.
Resource Type:: Masters Thesis

Understory vegetation response and nitrogen cycling following cutting of western juniper

Creator:: Bates, Jonathan D.
Abstract:: Since the late 1880's western juniper has expanded in range and increased in density in sagebrush-bunchgrass, riparian, and forested plant communities of the Pacific Northwest. Succession to western juniper woodland has been shown to reduce the productivity and diversity of the understory component, result in concentration of soil nutrients beneath...
Resource Type:: Dissertation

Spatial patterns of tree effects on pasture production in open canopied agroforests

Creator:: Harris, Norman Rex
Resource Type:: Masters Thesis

Effects of prescribed fire on Wyoming big sagebrush communities : implications for ecological restoration of sage grouse habitat

Creator:: Wrobleski, David W.
Resource Type:: Masters Thesis

Intercropping trees in a vegetable production systems : a holistic inquiry

Creator:: Seiter, Stefan
Resource Type:: Dissertation

Search Constraints

Search Results

Limit your search