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Articles 1 - 12 of 12

Full-Text Articles in Life Sciences

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 ...


A Comparative Agroecosystems Analysis Of Soil Water And Root Dynamics Under Six Different Vegetative Cover Types , Greg William Shepherd Jan 2006

A Comparative Agroecosystems Analysis Of Soil Water And Root Dynamics Under Six Different Vegetative Cover Types , Greg William Shepherd

Retrospective Theses and Dissertations

Anthropogenic activities have impacted land management in the Midwest by transforming perennial grasslands and savannas into annual croplands. Agriculturalists presently have a considerable impact on the ecological balance of expansive amounts of land. This study investigates soil water and root dynamics under six different annual and perennial vegetative cover types. Measurement of growing season surface soil moisture showed no significant differences between annual compared to perennial sites. Depth of water uptake determination indicated that buckbrush and oak acquired moisture from deeper depths (5-10 cm to groundwater) than corn and soybean (5-10 to 10-20 cm). Depth of water uptake for sedge ...


Forest Dynamics In Mesic Northern Hardwoods Following Windthrow And Salvage Logging , Katharyn Dianne Derr Jan 2006

Forest Dynamics In Mesic Northern Hardwoods Following Windthrow And Salvage Logging , Katharyn Dianne Derr

Retrospective Theses and Dissertations

Post-disturbance, or salvage, logging is a highly debated topic within natural resource science and management as its effects on forest recovery are not well understood. We examine a 25-year forest response to a 1977 severe wind disturbance on the Flambeau River State Forest in Wisconsin, USA, some of which was salvage logged. Our results show salvage logging affects the rate of vegetation recovery, microtopography, and soil composition within this mixed broad-leaved deciduous and conifer forest. Although salvaged and unsalvaged areas are similar in tree species composition, tree biomass is higher and forest microtopography is more pronounced within the unsalvaged area ...


The Importance Of Host Fish In Long Range Transport Of Unionids In Large Rivers , Daelyn Adele Woolnough Jan 2006

The Importance Of Host Fish In Long Range Transport Of Unionids In Large Rivers , Daelyn Adele Woolnough

Retrospective Theses and Dissertations

Freshwater mussels (Family: Unionidae) are the most imperiled faunal group in North America, yet little is known about factors that influence their distribution in rivers and lakes---especially over large geographic areas. They have a unique life cycle that includes an obligate parasite stage on fish. Throughout their life spans, long range or upstream transport is principally accomplished during the parasitic stage. This brief parasitic phase has lasting effects on adult mussel ecology---particularly in influencing their distribution. The movement of host fish occurs on large scales (e.g., >100m) and both their distribution and abundance likely contribute to the spatial patterns ...


Behaviorally-Induced Periodic Cooling Of Avian Embryos , Christopher Robin Olson Jan 2006

Behaviorally-Induced Periodic Cooling Of Avian Embryos , Christopher Robin Olson

Retrospective Theses and Dissertations

For many bird embryos, periodic cooling occurs when the incubating adult leaves the nest to forage, but the effects of periodic cooling on embryo growth, yolk use and metabolism are poorly known. To address this question I conducted incubation experiments on eggs of zebra finches (Taeniopygia guttata ) that were frequently cooled and then rewarmed or were allowed to develop at a constant temperature. After 12 days of incubation, embryo mass and yolk reserves were less in eggs that experienced periodic cooling, compared to controls incubated constantly at 37.5°C. Embryos that regularly cooled to 20°C had higher mass-specific ...


Weedy Setaria Species-Group Seed Heteroblasty Blueprints Seedling Recruitment , Kari Ann Jovaag Jan 2006

Weedy Setaria Species-Group Seed Heteroblasty Blueprints Seedling Recruitment , Kari Ann Jovaag

Retrospective Theses and Dissertations

The relationship between weedy Setaria seed dormancy and subsequent behaviors in the soil culminating in seedling recruitment is elucidated. Weedy Setaria seed dormancy capacity heterogeneity (heteroblasty) at the time of dispersal was characterized for 45 locally adapted Setaria populations, as influenced by parental genotype (species, time of embryogenesis) and environment (year, location). Taken together, the 45 responses represented Setaria's "seed dormancy phenotype space". The fate of heteroblastic seed entering the soil post-abscission was studied in four of the populations. When dispersed, heteroblastic Setaria seeds introduced into the soil form long-lived pools with varying cycles of dormancy, germination and death ...


Anuran Community Structure And Wetland Occupancy Along An Urban-Rural Gradient In Central Iowa, Usa , Finn Cooper Pillsbury Jan 2006

Anuran Community Structure And Wetland Occupancy Along An Urban-Rural Gradient In Central Iowa, Usa , Finn Cooper Pillsbury

Retrospective Theses and Dissertations

Urbanization has been cited as an important factor in worldwide amphibian declines. Although recent work has illustrated the influence of broad-scale ecological patterns and processes on amphibian populations, little is known about the relative importance of wetland habitat and landscape context on the distribution, abundance, and diversity of anurans in urban landscapes. We therefore examined patterns of anuran community structure and wetland occupancy along an urban-rural gradient in central Iowa, USA. Landscape fragmentation had the strongest influence on anuran community structure, influencing most the abundance of species that use upland habitats outside the breeding season. Urban habitat loss and fragmentation ...


Diversity And Efficacy Of Arbuscular Mycorrhizal (Am) Fungi Isolated From Soils Of Soybean Fields , Zahra Ifnou Troeh Jan 2006

Diversity And Efficacy Of Arbuscular Mycorrhizal (Am) Fungi Isolated From Soils Of Soybean Fields , Zahra Ifnou Troeh

Retrospective Theses and Dissertations

A field survey evaluated the population composition of AM fungal species in Clarion (a well drained fine-loamy, mixed, mesic Typic Hapludoll) and Webster (a poorly drained fine-loamy, mixed, mesic Typic Endoaquoll) soils of four Iowa soybean (Glycine max, L.) fields. Spores from six species of Glomus and from the genera Acaulospora, Gigaspora , and Paragomus were found in the original field soils. G. claroideum, G. etunicatum, G. mosseae, G. viscosum, and Paraglomus occultum-like spores were prevalent in both Clarion and Webster soils of all four fields. Minor species included G. geosporum and G. intraradices. Trap cultures led to detection of several ...