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  • Effects of wildfire burn severity on soil microbial communitiesand invasive plant species in the Cascade Range of Oregon

    Creator:
    Hebel, Cassie L.
    Abstract:
    Fire suppression in the last several decades has resulted in unprecedented accumulations of organic matter on the landscape, leading to an increase in large, intense wildfires. This study investigated the soil microbial community (using phospholipid fatty acid analysis) across recently burned forests on the eastern slope of the Cascade Range...
    Resource Type:
    Masters Thesis
    Full Text:
    Invasive Plant Species in the Cascade Range of Oregon. by Cassie Lenae Hebel A THESIS

  • 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:
    - severity fire within the mixed-severity matrix created large canopy gaps (>30 m in diameter) in which

  • Strategies for machine harvesting of mature coffee (Coffea arabica L.) fruits

    Creator:
    Tongumpai, Peeradet
    Abstract:
    Greenhouse and field grown coffee plants were used to study the synchronization of flowering and fruiting. The purpose of these studies was to develop methods of improving the selective harvesting of mature coffee fruits by machine. The studies were divided into 4 parts: 1) Synchronization of flowering, 2) Synchronization of...
    Resource Type:
    Dissertation
    Full Text:
    of Doctor of Philosophy in Horticulture presented on September 30. 19 93. Title: Strategies for

  • Rubus spp. seed germination and morphology

    Creator:
    Peacock, Derek N.
    Abstract:
    Rubus spp. seeds have a thick protective endocarp and testa (seedcoat) that can restrict germination even under favorable conditions. The effect of pregermination treatments were studied in Rubus chamaemorus L., R. eustephanos Focke ex Diels, R. idaeus 'Amber' L., R. leucodermis Douglas ex Torrey & A. Gray, R. multibracteatus A....
    Resource Type:
    Masters Thesis
    Full Text:
    Master of Science in Horticulture presented on August 30, 1995. Title: Rubus spp. Seed Germination and

  • 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
    Full Text:
    average July temperature is 21.1°C. Extreme temperatures range from -20°C to 41°C. Plant Materials

  • 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
    Full Text:
    plant- environment interactions in range systems. I was fortunate to have more than a grad-rep in Dr

  • The effects of defoliation on Bromus tectorum seed production and growth

    Creator:
    Mayer, Kara Hempy
    Abstract:
    Cheatgrass (Bromus tectorum L.) is a widespread exotic weed in the Intermountain sagebrush steppe. An annual grass, it is highly prolific and very competitive with native perennial grass seedlings. A clipping experiment carried out at two cheatgrass-dominated sites (Lincoln Bench and Succor Creek) in eastern Oregon analyzed effects of defoliation...
    Resource Type:
    Masters Thesis
    Full Text:
    Hempy Mayer for the degree of Master of Science in Botany and Plant Pathology presented on July 15

  • Directing ecological succession : the role of competition in restoring semi-arid grasslands dominated by invasive plants

    Creator:
    Mangla, Seema
    Abstract:
    Successful ecosystem restoration requires an understanding of the ecological processes directing succession. One of the challenges in the semi-arid grasslands of western United States is replacement of native species by invasive annual grasses. Solutions to this problem require identifying and manipulating ecological processes that direct succession to favor desired vegetation....
    Resource Type:
    Dissertation
    Full Text:
    United States. Plant competition is considered to be the primary ecological process limiting

  • Plant community recovery after high severity wildfire and post-fire management in the Klamath Region

    Creator:
    Lopez Ortiz, Maria Jose
    Abstract:
    Disturbance and microclimate interact to play a central role influencing the composition and structure of plant communities. In this thesis, I examined plant community composition and structure twenty years after high severity wildfires with and without post-fire management (salvage logging, fuel treatment, tree planting, and shrub release) under contrasting microclimatic...
    Resource Type:
    Masters Thesis
    Full Text:
    sampling was 88 m (range 20-250 m). We used a 12x40 m plot comprised of 30 cells of 4x4 m. Plot level

  • 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
    Full Text:
    . Title: Role of Propagule Pressure and Priority Effects on Plant Establishment during Restoration of