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Articles 1 - 5 of 5
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Decreasing Emissions Of Methane From Rice Agriculture, M. A. K. Khalil, Martha J. Shearer
Decreasing Emissions Of Methane From Rice Agriculture, M. A. K. Khalil, Martha J. Shearer
Environmental Science and Management Faculty Publications and Presentations
Methane emissions from rice fields are controlled by several key factors. The most important are the application of organic soil amendments and water management: whether the fields are flooded intermittently or continuously. The total annual emissions from any country or the world are thus affected by the area of rice harvested, and a composite emission factor that takes into account how the various agricultural practices are distributed in terms of fertilizer use and water management, as well as other less important variables. Over decades the area of rice harvested changes but so does the composite emission factor. The product therefore, …
Hydrodynamic Mediation Of Density-Dependent Growth And Adult-Juvenile Interactions Of A Spionid Polychaete, Brent T. Hentschel, Amy A. Larson
Hydrodynamic Mediation Of Density-Dependent Growth And Adult-Juvenile Interactions Of A Spionid Polychaete, Brent T. Hentschel, Amy A. Larson
Environmental Science and Management Faculty Publications and Presentations
Abstract We performed an experiment to test the effects of adult density on the growth rates of juvenile Polydora cornuta. Our experiment was performed in three identical counter-rotating annular flumes, each set to one of three different flow speeds for a period of 3 d (U 5mm = 3, 6, or 12 cm s-1 , where U5mm = velocity measured 5 mm above bottom). We implanted replicate vials containing a premeasured juvenile P. cornuta and either 0, 2, or 5 adults into a 2-cm layer of sediment in the flume. The relative growth rates of the juveniles …
Changes In Riparian Vegetation Buffers In Response To Development In Three Oregon Cities, J. Alan Yeakley, Connie P. Ozawa, A. M. Hook
Changes In Riparian Vegetation Buffers In Response To Development In Three Oregon Cities, J. Alan Yeakley, Connie P. Ozawa, A. M. Hook
Environmental Science and Management Faculty Publications and Presentations
Riparian vegetation buffer loss was investigated for three cities with contrasting local regulatory controls in urbanizing northwest Oregon. The cities examined were Hillsboro, Oregon City and Portland, all having experienced high rates of population increase in the 1990s. All cities are covered under Oregon’s land use law that provides goals for the protection of open space and natural resources. On the municipality level, regulatory controls in Portland included a system of environmental zoning for riparian area protection, while regulatory controls on development in riparian areas in Hillsboro and Oregon City were less stringent. Digital aerial photographs covering buffer areas within …
Variation In The Response Of Crustacean Zooplankton Species Richness And Composition To The Invasive Predator Bythotrephes Longimanus, Angela L. Strecker, Shelley E. Arnott, Norman D. Yan, Robert Girard
Variation In The Response Of Crustacean Zooplankton Species Richness And Composition To The Invasive Predator Bythotrephes Longimanus, Angela L. Strecker, Shelley E. Arnott, Norman D. Yan, Robert Girard
Environmental Science and Management Faculty Publications and Presentations
The predacious invertebrate Bythotrephes longimanus has invaded >90 freshwater lakes in North America. There is some evidence that B. longimanus has a negative effect on summer zooplankton species richness; however, no study has examined the effect of B. longimanus throughout the ice-free season in more than one lake. We visited 10 invaded and 4 reference lakes every 2 weeks from May to September, collecting B. longimanus, crustacean zooplankton, and water chemistry samples. Composite samples were pooled across the study season for each lake. Bythotrephes longimanus significantly reduced cladoceran species richness, diversity, and abundance, and the total zooplankton community also exhibited …
Using Student Generated Qualitative Ecological Models, J. Scott Blackwood, Marion Dresner, Hang-Kwang Luh
Using Student Generated Qualitative Ecological Models, J. Scott Blackwood, Marion Dresner, Hang-Kwang Luh
Environmental Science and Management Faculty Publications and Presentations
In this activity, students construct qualitative models of an ecosystem and use the models to gain a better understanding of direct and indirect ecological interactions. Qualitative modeling is described for use in two procedures, each with different educational goals and student backgrounds in mind. Part 1 is designed with the non-major or beginning ecology student in mind, and is intended both to improve student understanding of the ecosystem of interest and to provide a framework for the instructor to assess student learning. Part 2 is designed for more advanced students of ecology and involves the use of modeling software (POWERPLAY) …