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Articles 1 - 7 of 7

Full-Text Articles in Life Sciences

The State, Resilience, And Potential Future Of Oak-Dominated Forests In The Driftless Area Of The Midwestern U.S., Tricia Gorby Knoot Jan 2008

The State, Resilience, And Potential Future Of Oak-Dominated Forests In The Driftless Area Of The Midwestern U.S., Tricia Gorby Knoot

Retrospective Theses and Dissertations

Forest surveys over the last several decades indicate a decline in oak regeneration in the midwestern United States with a high potential for future replacement by later successional forest types. The current state of oak systems may be nearing critical thresholds, which, if reached, their restoration could become markedly more challenging, if not impossible. Through a combination of qualitative and quantitative research methods, I evaluated the state, resilience, and potential future of oak forest ecosystems within the Driftless Area of the midwestern U.S., with the intention of providing information that can inform the design of timely and targeted oak-specific ...


Grassland Bird Abundance And Nesting In Short-Duration Rotationally Grazed Pastures In Southwest Iowa, Ryan David Marquardt Jan 2008

Grassland Bird Abundance And Nesting In Short-Duration Rotationally Grazed Pastures In Southwest Iowa, Ryan David Marquardt

Retrospective Theses and Dissertations

Grassland bird populations across the Midwest are experiencing declines due to loss of habitat, which could potentially be replaced with grazing systems. This study measured abundance, nesting, and derived conservation values for a rotational stocking grazing management unit where cool-season grass (CSG) paddocks were grazing in the spring and fall and rested in the summer, and warm-season grass (WSG) paddocks were grazed in the summer and rested in spring an fall. Adjacent ungrazed Conservation Reserve Program lands in CSG and WSG served as control treatments. Dickcissels (Spiza americana ) had bird densities in ungrazed WSG fields (3.8+/-0.29 birds ...


The Evaluation Of Maize Genotypes For Potential Use In Cellulosic Ethanol Production, Krystal Marie Kirkpatrick Jan 2008

The Evaluation Of Maize Genotypes For Potential Use In Cellulosic Ethanol Production, Krystal Marie Kirkpatrick

Retrospective Theses and Dissertations

Corn stover represents a potential lignocellulosic feedstock that may benefit the emerging cellulosic ethanol industry. This study was conducted to determine dry matter yield and quality characteristics of maize stover, cob, and husk plant fractions, and to make predictions of potential ethanol yields. Detergent fiber predictions were made for each plant fraction using near infrared reflectance spectroscopy (NIRS). Predicted values were used to determine ethanol potential using a modified version of the National Renewable Energy Lab (NREL) theoretical ethanol yield calculator. Although significant, not as much variation was present among genotypes and plant fractions for chemical composition as for dry ...


Terrestrial Arthropod Community And Indicators Of Biotic Integrity For Iowa Tallgrass Prairie, Jessica Marie Orlofske Jan 2008

Terrestrial Arthropod Community And Indicators Of Biotic Integrity For Iowa Tallgrass Prairie, Jessica Marie Orlofske

Retrospective Theses and Dissertations

The tallgrass prairie has become one of the most endangered ecosystems in North America. Thus, there have been attempts to restore and reconstruct native tallgrass prairie. Arthropods, the most diverse taxonomic group on the prairie, have not received adequate attention. A comprehensive arthropod survey in Iowa prairies has not been attempted since the 1930's, and therefore lacks information regarding recent prairie restoration efforts. Arthropods can also provide valuable information related to ecosystem function or biotic integrity when used as bioindicators. However, effective, reliable arthropod bioindicators have not been clearly identified. A survey of arthropods using sweep net transects was ...


Ecology Of Elk Parturition Across Winter Feeding Opportunities In The Brucellosis Endemic Area Of Wyoming, Andrea Ellen Barbknecht Jan 2008

Ecology Of Elk Parturition Across Winter Feeding Opportunities In The Brucellosis Endemic Area Of Wyoming, Andrea Ellen Barbknecht

Retrospective Theses and Dissertations

This study was initiated to examine parturition related behavior both from an ecological perspective and to investigate implications for brucellosis transmission risk among elk and between elk and cattle. These aspects were investigated for elk fed during the winter, elk using improved winter feedlines, and free-ranging elk. Brucellosis is a disease causing abortion in elk ( Cervus elaphus nelsoni), bison (Bos bison), and cattle (Bos spp.). The most common transmission route is through oral contact with aborted fetuses or parturition tissues/fluids and transmission risk is dependent on contact rates. Vaginal implant transmitters were deployed on winter free-ranging elk and elk ...


Nitrous Oxide And Methane Fluxes In Riparian Buffers And Adjacent Crop Fields, Dong-Gill Kim Jan 2008

Nitrous Oxide And Methane Fluxes In Riparian Buffers And Adjacent Crop Fields, Dong-Gill Kim

Retrospective Theses and Dissertations

Denitrification is recognized as the major mechanism for reducing nitrate (NO3-) in riparian buffers and thus diminishing non-point source pollution (NPS) of surface water bodies subject to high N loads. However, increasing denitrification rates in riparian buffers may be trading the problem of NPS pollution of surface waters for atmospheric deterioration and increased global warming potential because denitrification produces nitrous oxide (N2O), a greenhouse gas also involved in stratospheric ozone depletion. Also N2O produced in the denitrification process can be dissolved in groundwater and is eventually emitted into the air when groundwater flows into a stream or a river. Riparian ...


A Simulation Assessment Of The Boone River Watershed: Baseline Calibration/Validation Results And Issues, And Future Research Needs, Philip Walter Gassman Jan 2008

A Simulation Assessment Of The Boone River Watershed: Baseline Calibration/Validation Results And Issues, And Future Research Needs, Philip Walter Gassman

Retrospective Theses and Dissertations

A SWAT modeling framework has been constructed for the Boone River Watershed (BRW) in north central Iowa, to support further testing of SWAT and analyses of alternative management practice and/or cropping system scenarios. The BRW covers over 237,000 ha and is an intensively cropped region dominated by corn and soybean production. Nitrate losses are of particular concern in the BRW, especially through subsurface tiles that drain the predominantly flat landscapes that persist throughout the watershed. The modeling system features an intensive set of management, land use, and soil data developed at the Common Land Unit (CLU) level. The ...