Open Access. Powered by Scholars. Published by Universities.®

Life Sciences Commons

Open Access. Powered by Scholars. Published by Universities.®

Articles 1 - 30 of 391

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 ...


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 ...


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 ...


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 ...


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 ...


Watershed Planning In Central Iowa: An Integrated Assessment Of The Squaw Creek Watershed For Prioritization Of Conservation Practice Establishment, Ashley Anne Wendt Jan 2007

Watershed Planning In Central Iowa: An Integrated Assessment Of The Squaw Creek Watershed For Prioritization Of Conservation Practice Establishment, Ashley Anne Wendt

Retrospective Theses and Dissertations

Non-point source pollutants are a dominant threat to aquatic ecosystems in agriculturally dominated watersheds of the Midwest. Erosion and run-off from crop fields not only lowers the productivity of the field, but also transports sediment and attached nutrients or other agri-chemicals to receiving waters. In-field and edge-of-field best management practices (BMPs) have long been recognized as efficient ways to alleviate sediment impacts; however, prioritizing placement of these BMPs is critical to efficiently utilize allocated resources. A watershed assessment, utilizing the Iowa Department of Natural Resources (IDNR) Watershed Project Planning Protocol (WPPP) framework, was conducted on the Squaw Creek Watershed (SCW ...


Indications Of Environmental Literacy: Using A New Survey Instrument To Measure Awareness, Knowledge, And Attitudes Of University-Aged Students, Susan Roberta Mello O'Brien Jan 2007

Indications Of Environmental Literacy: Using A New Survey Instrument To Measure Awareness, Knowledge, And Attitudes Of University-Aged Students, Susan Roberta Mello O'Brien

Retrospective Theses and Dissertations

The role of environmental education has received enough attention with applied environmental literacy research completed at the level of elementary and secondary schools curricula, as well as assessments on adults' environmental literacy at state, national, and even international levels. However, few studies have focused on university-level assessments as means for increasing people's environmental knowledge. The reported research examines the levels of environmental knowledge and attitudes of Iowa State University (ISU) undergraduate and graduate students registered for the 2007 spring semester. A new survey instrument was developed specifically for this study, accounting for local (Midwestern) and global environmental issues. Students ...


Diversifying Midwestern Agriculture With Perennial Forages: A Review Of The Benefits And Barriers To Forages In Iowa, And A Genetic Study Of Biofuel Potential For Reed Canarygrass, Julia Olmstead Jan 2007

Diversifying Midwestern Agriculture With Perennial Forages: A Review Of The Benefits And Barriers To Forages In Iowa, And A Genetic Study Of Biofuel Potential For Reed Canarygrass, Julia Olmstead

Retrospective Theses and Dissertations

This thesis addresses first the socio-political, economic, and ecological consequences and causes of decreased forage production in Iowa, and then focuses on a breeding study related to the biofuel potential of reed canarygrass. In the first paper I review the agronomic, ecological, and economic benefits of forage incorporation into corn and soybeans rotations and then attempt to explain the socio-political reasons why forages are not grown on more Iowa farms. The second paper details an evaluation of reed canarygrass germplasm for biofuel traits. We evaluated the entire reed canarygrass germplasm collection available in the US for biomass and quality traits ...


Soil Respiration And Plant Growth Across A Chronosequence Of Tallgrass Prairie Reconstructions, Ryan Matthew Maher Jan 2007

Soil Respiration And Plant Growth Across A Chronosequence Of Tallgrass Prairie Reconstructions, Ryan Matthew Maher

Retrospective Theses and Dissertations

An understanding of changes in soil respiration (Rs) and plant growth in tallgrass prairies planted into formerly cultivated land is critical if we are to predict the effects of grassland reconstructions on belowground carbon cycling. In addition, predicting changes in the ecosystem carbon balance in grassland reconstructions will require identifying the climatic and biological controls on Rs across a landscape of cultivated and reconstructed grassland ecosystems. This study used a 12 yr chronosequence of tallgrass prairie reconstructions in central Iowa, including a no-till soybean field (age 0), to quantify the relationship between tallgrass prairie age, R s, root biomass, root ...


Grazing Management Effects On Sediment And Phosphorus Losses From Streambanks, Shelly Lee Nellesen Jan 2007

Grazing Management Effects On Sediment And Phosphorus Losses From Streambanks, Shelly Lee Nellesen

Retrospective Theses and Dissertations

Agricultural lands are the leading cause of nonpoint-source pollution in the United States. Previous studies indicate that grazed lands can have more impact on sediment and phosphorus (P) losses to surface waters than cropland or other agricultural lands. The purpose of this research was to determine the effects of different grazing managements on streambank erosion and potential P losses. In 2004, three treatments, including rotational stocking, continuous stocking with limited stream access, and continuous stocking with full stream access were established in six adjacent pastures along Willow Creek at a research farm in Marshall County, Iowa. Erosion measurements were taken ...


Oak Forest Decline And Effects Of Two Invasive Shrubs In The Midwest Driftless Area: Current Status And Implications For The Future, Erik Charles Mottl Jan 2007

Oak Forest Decline And Effects Of Two Invasive Shrubs In The Midwest Driftless Area: Current Status And Implications For The Future, Erik Charles Mottl

Retrospective Theses and Dissertations

No abstract provided.


Plumbing Agricultural Landscapes For Water Quality Improvement: Coexistence Of Intensive Agriculture And Good Water Quality, Zsolt Gemesi Jan 2007

Plumbing Agricultural Landscapes For Water Quality Improvement: Coexistence Of Intensive Agriculture And Good Water Quality, Zsolt Gemesi

Retrospective Theses and Dissertations

Years of data collection at the bases of 130 lake watersheds in Iowa have enabled us to study the relationships between nutrient concentrations and land use/land cover, as well as to measure the fluxes of key nutrients through hydrologically-linked agroecosystems within the landscape. These ecosystems are dominated by cropland and intensively managed fields with high nutrient export coefficients. Satellite image-derived land cover maps, digital elevation maps and soil mapping units were interpreted and manipulated using geographic information software. We evaluated the relationships between landscape characteristics and lake water quality in Iowa (USA) by regressing four lake water quality responses ...


Modeling Phosphorus Transport Using The Wepp Model, Mario Perez-Bidegain Jan 2007

Modeling Phosphorus Transport Using The Wepp Model, Mario Perez-Bidegain

Retrospective Theses and Dissertations

The Water Erosion Prediction Project (WEPP) model has been widely tested for its ability to predict soil erosion, runoff, and sediment delivery over a very wide range of conditions and scales for both hillslopes and watersheds. However, WEPP has not been used to estimate nutrient loss, in particular phosphorus losses. It is well known that most of the phosphorus transported from cropland is attached to sediment; consequently management practices that reduce erosion and sediment transport could reduce phosphorus losses. Management practices like vegetative filter strips, grass barriers, and multispecies riparian buffers have been proposed to reduce the transport of sediment ...


Effects Of Restoration On Midwestern Oak Savanna Biodiversity, Structure, And Oak Regeneration, Lars Andrew Brudvig Jan 2007

Effects Of Restoration On Midwestern Oak Savanna Biodiversity, Structure, And Oak Regeneration, Lars Andrew Brudvig

Retrospective Theses and Dissertations

Over the last century, savannas throughout the world have been encroached by woody plants, altering over- and understory plant composition and distributions of understory resources. This dissertation investigates woody encroachment removal from Midwestern oak savannas, using a large-scale restoration experiment in Iowa. Four sites received a woody encroachment removal treatment (restoration) and four sites were retained as encroached controls. Chapter two details impacts on woody plant regeneration dynamics. Encroachment removal restored savanna canopy structure and overstory dominance by Querucs (oak) species; however, advanced regeneration was dominated by encroaching species within three years. I suggest that the encroached savannas represent an ...


Soil Management, Crop Rotations, And Biomass Removal Effects On Soil Organic Matter Content, Krisztina Eleki Jan 2007

Soil Management, Crop Rotations, And Biomass Removal Effects On Soil Organic Matter Content, Krisztina Eleki

Retrospective Theses and Dissertations

No abstract provided.


Associations Of Amphibians With Environmental Covariates And Estimation Of The Prevalence Of The Pathogen Batrachochytrium Dendrobatidis In North-Central Iowa Wetlands, Jennifer Loda Jan 2007

Associations Of Amphibians With Environmental Covariates And Estimation Of The Prevalence Of The Pathogen Batrachochytrium Dendrobatidis In North-Central Iowa Wetlands, Jennifer Loda

Retrospective Theses and Dissertations

Contaminants, habitat degradation, and the pathogen Batrachochytrium dendrobatidis (Bd) are among suspected culprits for worldwide amphibian declines, however; little field research has been done to examine these factors in the Midwestern US. In 2006 I conducted amphibian surveys at 29 wetlands in north-central Iowa, a region dominated by intensive row crop agriculture. I utilized three survey techniques to document amphibians and used the information-theoretic approach to choose models that best estimated relationships between successful reproduction and species richness, and the parameters: pesticides, nutrients, wetland density, proportion cropland in the landscape, and fish. I collected swab samples from Rana pipiens and ...


Development Of Methods To Assess The Fate And Effects Of Bacillus Thuringiensis (Bt) Cry1f And Cry3bb1 Proteins, Kelsey Renee Prihoda Jan 2007

Development Of Methods To Assess The Fate And Effects Of Bacillus Thuringiensis (Bt) Cry1f And Cry3bb1 Proteins, Kelsey Renee Prihoda

Retrospective Theses and Dissertations

No abstract provided.


Assessment Of The Interrelationships Between Fish Population Dynamics And Limnological Characteristics Of Iowa Lakes, Zachary Joseph Jackson Jan 2007

Assessment Of The Interrelationships Between Fish Population Dynamics And Limnological Characteristics Of Iowa Lakes, Zachary Joseph Jackson

Retrospective Theses and Dissertations

Lakes are important resources and understanding relationships between fish, humans, and environmental conditions is critical for guiding management activities. We examined fish populations, limnological conditions, lake basin morphology, and watershed characteristics in 129 Iowa lakes. Our purpose was to evaluate patterns in population characteristics of important fish species in relation to environmental conditions. Bluegill Lepomis macrochirus and largemouth bass Micropterus salmoides abundance was highest in systems with high water transparency and nutrients. Catch rates of bluegill, black crappie, and largemouth bass were generally low when omnivores (e.g., black bullhead Ameiurus melas, common carp Cyprinus carpio) were present. Body condition ...


Dynamic Soil Properties Across A Suburban Landscape, Ankeny, Iowa, Amy Elizabeth Norton Jan 2007

Dynamic Soil Properties Across A Suburban Landscape, Ankeny, Iowa, Amy Elizabeth Norton

Retrospective Theses and Dissertations

Humans influence soil properties through agriculture, urbanization, and many other activities. This study investigated the degree to which humans influence dynamic soil properties (including bulk density, organic carbon, and heavy metal concentrations) in a suburban landscape and assesses the variability of these soil properties with respect to the length of time that has passed since disturbance or construction activities. Aerial photos were used to delineate residential areas from different years and nine time periods of development were established. Ten homes from each time period of development were randomly selected and soil samples were collected from the center of the front ...


Environmental Studies On The Fate And Effects Of Pharma Proteins Produced In Transgenic Maize, Hirofumi Kosaki Jan 2007

Environmental Studies On The Fate And Effects Of Pharma Proteins Produced In Transgenic Maize, Hirofumi Kosaki

Retrospective Theses and Dissertations

The environmental fate and effects of a transgenic maize-expressed recombinant antigen, Escherichia coli heat-labile enterotoxin subunit B (LTB), was studied under laboratory conditions. The time for 50% dissipation (DT50) for the extractable fraction of maize-expressed LTB in soil was 35∼90 days, and both extractability and persistence were strongly affected by the soil types and environmental conditions. In addition to the environmental fate study, laboratory bioassays were conducted to investigate the sub-acute effects of maize-expressed LTB on two soil invertebrates. Both the 28-day springtail, Folsomia candida reproduction assay and earthworm, Eisenia fetida growth assay showed no adverse effects of LTB ...


The Endangered Species Act, Local Power And Contested Issues On The Rural-Urban Interface, Kristen Marie Corey Jan 2007

The Endangered Species Act, Local Power And Contested Issues On The Rural-Urban Interface, Kristen Marie Corey

Retrospective Theses and Dissertations

This research project examines some of the effects that implementing the Endangered Species Act has on a rapidly growing community. This case study focuses on the eastern Nebraska saline wetlands near Lincoln in the Little Salt Creek watershed - home to the endangered Salt Creek tiger beetle. With the listing of the Salt Creek tiger beetle on the Federal Endangered Species list in 2005, the beetle has emerged as the central figure in a debate dividing those who wish to develop and those who aspire to protect these rare saline wetlands. Ethnographic data are used to study this situation. In-person interviews ...


An Examination Of Contributing Factors To Land Use/Land Cover Change In Southern Belize And The Use Of Satellite Image Analysis To Track Changes, Marissa Lenée Moore Jan 2007

An Examination Of Contributing Factors To Land Use/Land Cover Change In Southern Belize And The Use Of Satellite Image Analysis To Track Changes, Marissa Lenée Moore

Retrospective Theses and Dissertations

Land use and land cover change analyses are important tools for planning and development decisions. Tropical deforestation has both local and global implications. One main reason for deforestation is the conversion of forest to agricultural land. This study explores influences and potential causes for agricultural expansion and deforestation within the Toledo District in southern Belize, Central America. Many factors play into the deforestation and degradation of tropical forests in this district, including social, cultural, political and economic issues, all of which need serious consideration if planners and politicians are to combat the problem. Understanding the reasons for deforestation goes hand ...


Species And Functional Diversity Effects On Productivity And Nutrient Uptake: Implications For Designing Sustainable Agricultural Systems In The Midwest, Melissa Renee Cheatham Jan 2007

Species And Functional Diversity Effects On Productivity And Nutrient Uptake: Implications For Designing Sustainable Agricultural Systems In The Midwest, Melissa Renee Cheatham

Retrospective Theses and Dissertations

Temporal data on aboveground biomass and nutrient uptake by species and functionally diverse native perennial plant species and communities is needed to enhance the performance of in-field buffer conservation practices. Comparisons on the performance of monocultures and polycultures of four native perennial prairie species having different functional traits (e.g., forb, grass, nitrogen-fixer) relative to monocultures of corn soybean, brome, and switchgrass were conducted in terms of aboveground biomass production and N & P uptake at peak performance, at the beginning and end of the growing season, and over the course of the whole year. Data collection occurred in 2006, a ...


Reconstructing Quaternary Landscapes And Hydrology From Soil Survey Maps, Bradley A. Miller Jan 2006

Reconstructing Quaternary Landscapes And Hydrology From Soil Survey Maps, Bradley A. Miller

Retrospective Theses and Dissertations

This study was done to investigate the pre-settlement condition of the southern Des Moines Lobe landscape, with particular interest in the hydrological function of depressional wetlands. Soil survey maps were used to identify the soil formation environment from soil properties observed today. Understanding the factors of soil formation and geomorphology allows historical reconstructions of the landscape, hydrology, wildlife habitat, and potentially other areas of interest. This study interpreted and managed soil survey data to efficiently create a Quaternary geologic map, identify the extents of historical depressional wetlands, deduce information about the water budget of these wetlands, and estimate the region ...


Integration Of Remote Sensing And Crop Growth Modeling For Nitrogen Management Decision Support In Corn , Kelly Robert Thorp Jan 2006

Integration Of Remote Sensing And Crop Growth Modeling For Nitrogen Management Decision Support In Corn , Kelly Robert Thorp

Retrospective Theses and Dissertations

This dissertation describes efforts to move toward a completely integrated remote sensing and crop growth modeling tool for developing precision nitrogen management recommendations for corn. Aerial hyperspectral remote sensing imagery collected throughout the 2004 growing season was used to estimate corn plant stand density, and a machine vision system was used to map corn population on the ground. Multiple linear regression analysis was used to assess the ability of all combinations of three reflectance bands to estimate corn plant population at resolutions of 2 m, 6 m, and 10 m. Coefficients of multiple determination of up to 0.82 were ...


Riparian Land-Use Impacts On Stream Bank Soil And Phosphorus Losses From Grazed Pastures , Mustafa Tufekcioglu Jan 2006

Riparian Land-Use Impacts On Stream Bank Soil And Phosphorus Losses From Grazed Pastures , Mustafa Tufekcioglu

Retrospective Theses and Dissertations

An emerging challenge in watershed-scale research is to quantify the extent of sediment contributed to receiving waters from stream banks versus overland flow from critical source areas, and to develop management strategies to reduce stream bank erosion. The objective of this research was to compare the amounts of sediment and phosphorus loss from critical stream bank source areas to receiving waters via overland flow and stream bank erosion from riparian grazed pasture under different stocking densities (cow-calf pair ha -1). Rainfall simulations were used to calculate sediment and P loads from overland flow from stream-side livestock loafing and access points ...


Use Of Precision Agriculture Technologies In Studying The Relationships Among Soil Ph, Calcium Carbonate Equivalent, Soybean Cyst Nematode Population Density, And Soybean Yield , Natalia Rogovska Jan 2006

Use Of Precision Agriculture Technologies In Studying The Relationships Among Soil Ph, Calcium Carbonate Equivalent, Soybean Cyst Nematode Population Density, And Soybean Yield , Natalia Rogovska

Retrospective Theses and Dissertations

Iron deficiency chlorosis (IDC) and soybean cyst nematode (SCN; Heterodera glycines) infestation are major factors that contribute to soybean (Glycine max Merr.) yield reduction in the Midwest. The IDC is often associated with soybean grown on high pH, calcareous soils. In addition, it was documented that SCN population density is higher in high pH soils. The objectives of this paper were to assess the proportion of within-field soybean yield and SCN variability that could be explained by soil pH, calcium carbonate equivalent (CCE), and a previously defined alkalinity stress index (ASI). Aerial images from 21 fields planted to SCN-resistant or ...


An Analysis Of The Iowan Angler's Fishing License Renewal Decision, Ryan R. French Jan 2006

An Analysis Of The Iowan Angler's Fishing License Renewal Decision, Ryan R. French

Retrospective Theses and Dissertations

The number of annual fishing licenses sold in Iowa has been in decline for two decades and has limited the amount of funds available to the Iowa Department of Natural Resources for fisheries management. The Iowa DNR is focused on reversing this trend through targeted marketing and efficient management of fishing resources. An analysis of Iowa anglers is performed with these goals in mind using past surveys and current customer data. The product of this analysis is a model which predicts whether a past customer will renew their license in the upcoming year. A logit model is developed using license ...