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  • 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
    Full Text:
    : ______________________________________________________ Douglas E. Johnson Dalmatian toadflax (Linaria dalmatica) has become a prolific invasive

  • Small broomrape (Orobanche minor) management using wheat (Triticum aestivum) as a false host

    Creator:
    Al-thahabi, Salam A.
    Abstract:
    Small broomrape (Orobanche minor) is an obligate, chlorophyll-lacking parasite that parasitizes red clover (Trifolium pratense) roots. This study was conducted to develop and implement an integrated, biologically based control program for small broomrape by using wheat as a false host to reduce the soil seed bank. The relationship between temperature...
    Resource Type:
    Dissertation
    Full Text:
    graduate committee of Dr. Thomas Chastain, Dr. Kenneth Johnson, and Dr. Paul Doescher for serving on my

  • 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
    Full Text:
    lliff for his support and encouragement, Dr. Douglas Johnson. I enjoyed working with you Dr. Johnson

  • Spatial and age class analysis of managed western juniper (Juniperus occidentalis) woodlands in central Oregon

    Creator:
    Zophy, Kelley T.
    Abstract:
    Juniper is a native species to Oregon and confers ecological benefits to wildlife when it is at savannah and transitional densities. Its range and extent have fluctuated with climatic change, but the current range expansion is unprecedented in its extent. The range expansion has been associated with the degradation of...
    Resource Type:
    Masters Thesis
    Full Text:
    , and parts of southern Washington (Miller and Rose 1995, Miller et al. 2005). Western juniper

  • Quaking aspen persistence in three Oregon landscapes

    Creator:
    Seager, S. Trent
    Abstract:
    Quaking aspen (Populus tremuloides) is an important tree species in the western United States and there has been much concern about its persistence. In this thesis, I report on aspen in a portion of its range that has not been previously evaluated: the eastern and western slopes of the Central...
    Resource Type:
    Masters Thesis
    Full Text:
    ecoregions (Miller and Rose, 1995; ODFW, 2006). However, aspen occurs in many parts of the state

  • Persistence of western juniper resource islands following canopy removal

    Creator:
    Miwa, Christopher
    Abstract:
    Western juniper (Juniperus occidentalis) cover has more than doubled within the last century and currently occupies over 9 million acres in the Intermountain West. Encroachment has altered the spatial distribution of soil nutrients and plants in these systems, forming nutrient enriched 'resource islands,' under tree canopies. The purpose of this...
    Resource Type:
    Masters Thesis
    Full Text:
    Wigand, 1994; Miller and Rose, 1995; Knapp and Soulé, 1998). Currently western juniper occupies 3.5

  • 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
    Full Text:
    project. Dave Ganskopp, Ruben Cruz, Rick Miller, and Jeff Rose helped in the tree cutting portion of the

  • An Investigation of soil, vegetation and mycorrhizal characteristics associated with native grass re-esablishment in crested wheatgrass seedings

    Creator:
    Raven, Karen A.
    Abstract:
    Since the 1930's, many fields on the Crooked River National grasslands have been seeded to crested wheatgrass (Agropyron desertorum). While some of these fields remain dominated by crested wheatgrass others had a greater presence of deep rooted native perennial grasses such as bluebunch wheatgrass (Pseudoroegneria spicata). Twenty eight fields previously...
    Resource Type:
    Masters Thesis
    Full Text:
    Doctors Doug Johnson and Mounir Louhaichi for their tireless help in understanding the details and

  • Climate-growth relationships of western juniper and ponderosa pine at the pine-woodland ecotone in southern Oregon

    Creator:
    Knutson, Kevin C.
    Abstract:
    Pinyon-juniper woodlands throughout the western U.S. have expanded rapidly following European settlement during the late 19th century. In central and eastern Oregon, western juniper (Juniperus occidentalis var. occidentalis Hook.) encroachment has been previously documented in the sagebrush steppe and upper elevation aspen communities. While these vegetation changes and dynamics have...
    Resource Type:
    Masters Thesis
    Full Text:
    Oregon (Miller and Wigand 1994, Miller and Rose 1995, Soule and Knapp 1999). This expansion has

  • Disturbance and dynamics of riparian forests in southwestern Oregon

    Creator:
    Messier, Michael S.
    Abstract:
    Fire exclusion has been associated with structural and compositional changes in many upland forests of the western United States, but little is known about the impacts on riparian forests, portions of the landscape protected for habitat and water quality. For this study, I characterized the historic disturbance and tree recruitment...
    Resource Type:
    Masters Thesis
    Full Text:
    recorded the species and DBH of each tree, its location in the long plot (x,y), and collected one