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Full-Text Articles in Life Sciences

Characteristics, Motivation, And Management Practices Of Nonindustrial Private Forest Landowners In Iowa , Jeffrey A. Regula Jan 1991

Characteristics, Motivation, And Management Practices Of Nonindustrial Private Forest Landowners In Iowa , Jeffrey A. Regula

Retrospective Theses and Dissertations

Two forestland owner surveys were conducted during 1985 and 1986 to examine the characteristics, attitudes, and motivations of nonindustrial private forest landowners in Iowa. The first part of this paper examines the effect of response order bias in telephone surveys. Unlike previous studies that found little effect from response order bias in other types of surveys, response order bias was shown to have a significant influence on response patterns. In the second part, a measure for assessing attitudes toward land stewardship is proposed. A model of land stewardship is also proposed and tested using factor analysis. The factor analysis of ...


Histological And Ultrastructural Studies Of Larval And Juvenile Lampsilis (Bivalvia) From The Upper Mississippi River , Becky Ann Lasee Jan 1991

Histological And Ultrastructural Studies Of Larval And Juvenile Lampsilis (Bivalvia) From The Upper Mississippi River , Becky Ann Lasee

Retrospective Theses and Dissertations

Histological and ultrastructural studies describing early life history stages of freshwater unionid bivalves and studies evaluating impacts of chemical contaminants on early growth are lacking. This study examined larval and juvenile shell ultrastructure of Lampsilis ventricosa using scanning electron microscopy (with observations of Pleurobema cordatum), described morphology of internal organs of laboratory-reared L. ventricosa and evaluated effects of cadmium on juvenile survival, growth and development. Postmetamorphic (juvenile) shell was added to peripheral edges of the larval shell. Initial juvenile shell growth was rapid and coincided with shell deposition into larval shell pores. Glochidia metamorphosed while encapsulated on gills of fish ...


Experimental Evaluation Of The Effectiveness Of A Computer-Assisted Instructional Unit On Sustainable Agriculture , Gaylan George Scofield Jan 1991

Experimental Evaluation Of The Effectiveness Of A Computer-Assisted Instructional Unit On Sustainable Agriculture , Gaylan George Scofield

Retrospective Theses and Dissertations

The central purpose of this study was to evaluate the effectiveness of an instructional unit on sustainable agriculture using a computer program as a tool to increase environmental awareness, enhance understanding of environmental problems, and promote the resolution of environmental issues in educational settings. The effectiveness of the unit was measured in students' knowledge of sustainable agriculture and both students' and teachers' ratings of the materials contained within the instructional unit;An experimental pretest-posttest design was used in this study. Sixteen Iowa schools (172 students) with agriculture departments who had expressed an interest in field testing the instructional unit were ...


The Role Of Climate And Mowing On Dickcissel (Spiza Americana) Movements, Distribution And Abundance, Lawrence D. Igl Jan 1991

The Role Of Climate And Mowing On Dickcissel (Spiza Americana) Movements, Distribution And Abundance, Lawrence D. Igl

Retrospective Theses and Dissertations

The Dickcissel (Spiza americana) is well known for its erratic, annual shifts in distribution and abundance and irruptive behavior on the breeding grounds. Annual fluctuations in the species' breeding range have been purported to be related to fluctuations in precipitation and its influence on annual vegetation growth (e.g., Roth 1979). A recent hypothesis suggests that mowing of hay fields in the center of the species' range also may contribute to opportunistic, drought-related movements to extralimital portions of the species' range (Mulvihi111989). Mowing seems to loosen or disrupt the between-year site faithfulness that characterizes relatively stable habitats. Low reproductive success ...


In Vitro Culture Systems Of Hybrid Aspen As Tools For Tree Improvement Programs And Commercial Applications , Sung Ho Son Jan 1991

In Vitro Culture Systems Of Hybrid Aspen As Tools For Tree Improvement Programs And Commercial Applications , Sung Ho Son

Retrospective Theses and Dissertations

Tree improvement programs have two important components: (1) induction of desirable types of genetic variation by breeding, and (2) selection and maintenance of the traits by sexual or asexual propagation methods. By combining tissue culture systems and morden DNA technology with conventional breeding methods, both aspects of tree improvement will benfit. New tissue culture systems are also important to the development of commercial applications of improved trees;Therefore, several new approaches to the in vitro culture of hybrid aspen (Populus alba L. x P. grandidentata Michx. 'Crandon') were studied. To investigate multiple shoot regeneration capacity of different cells, tissues, and ...


Provenance Variation And Genotype X Environment Interaction In Sesbania Sesban (L) Merill , Risper Nyagoy Nyong'o Jan 1991

Provenance Variation And Genotype X Environment Interaction In Sesbania Sesban (L) Merill , Risper Nyagoy Nyong'o

Retrospective Theses and Dissertations

Studies involving several accessions of Sesbania sesban were undertaken in the laboratory, nursery and field. The laboratory study was carried out at Iowa State University to determine the best pretreatment methods for sesban's seeds, based on four provenances. There were varying responses among the provenances to the different pretreatment methods. A 1-hour soak in hot water of an initial 100°C was recommended because it had the best general effect;At the Moi University Nursery, Eldoret, Kenya, an inoculation study was undertaken to determine symbiotic effectiveness among 12 accessions of S. sesban. Effects were measured in height growth, leaf ...


A Comparison Of The Bird And Aquatic Macroinvertebrate Communities Between Restored And 'Natural' Iowa Prairie Wetlands , Philip J. Delphey Jan 1991

A Comparison Of The Bird And Aquatic Macroinvertebrate Communities Between Restored And 'Natural' Iowa Prairie Wetlands , Philip J. Delphey

Retrospective Theses and Dissertations

The glaciated prairie region of north-central and northwestern Iowa once contained a 3-million-ha prairie-marsh complex, but since settlement, 95% of the area's wetlands has been lost (Bishop 1981). Wetland loss has also been great elsewhere in the Prairie Pothole Region, contributing to regional declines of breeding populations of ducks (Batt et al. 1989) and other water bird species (U.S. Fish Wildl. Serv. 1987). To recover some of this lost habitat, federal and state agencies, and private organizations have been restoring large numbers of drained basins since the middle 1980's, mostly on private agricultural land (e.g., Madsen ...


Species Richness And Nest Productivity Of Marsh Birds On Restored Prairie Potholes In Northern Iowa , Lisa Marie Hemesath Jan 1991

Species Richness And Nest Productivity Of Marsh Birds On Restored Prairie Potholes In Northern Iowa , Lisa Marie Hemesath

Retrospective Theses and Dissertations

Since the mid 1800s the number of wetlands in Iowa has decreased by 95% (Bishop 1981). Wetland drainage and the conversion of native grasslands into croplands have been primary causes of this loss. Because of this habitat loss, several wetland species have been extirpated from the state, and others have small populations (Weller 1979, Dinsmore 1981). The 1985 Farm Bill and the North American Waterfowl Management Plan provided the stimulus for wetland restoration on many of these drained basins. My objectives were to 1) determine if certain wetland characteristics affected bird colonization on restored wetlands and 2) assess the habitat ...


Ecology And Management Of Mahogany (Swietenia Macrophylla King) Regeneration In Quintana Roo, Mexico , Patricia Negreros-Castillo Jan 1991

Ecology And Management Of Mahogany (Swietenia Macrophylla King) Regeneration In Quintana Roo, Mexico , Patricia Negreros-Castillo

Retrospective Theses and Dissertations

Six aspects of the ecology and management of mahogany (Swietenia macrophylla King) regeneration in Quintana Roo, Mexico, were studied: (1) the effect of partial overstory removal on natural regeneration; (2) the development of a thinning simulation program, "ThinSim"; (3) a comparison of four methods to kill trees for partial overstory removal; (4) the survival of mahogany seedlings one year after a partial overstory removal; (5) the growth of some tropical trees species three years after a partial overstory removal; and (6) the sprouting capability of seventeen tropical tree species;Natural regeneration of commercially valuable species in tropical forests represents a ...


Efficient Herbicide Application To Reduce Environmental Losses , Steven Kent Mickelson Jan 1991

Efficient Herbicide Application To Reduce Environmental Losses , Steven Kent Mickelson

Retrospective Theses and Dissertations

A point-injection system has successfully been designed to inject and incorporate herbicides applied with water into the soil profile in a band. This point-injection cylinder (PIC) can incorporate herbicides in a single pass through the field while leaving the soil surface virtually undisturbed. The PIC functions effectively on both bare soil surfaces and soil surface covered with crop residue;The relative persistence of banded herbicides (alachlor, atrazine, and propachlor) using the PIC and a band sprayer was compared in a field study. A bare soil surface and a soil covered with an average of 79 percent corn residue were used ...


Demographic Responses Of Raccoons To Varying Exploitation Rates , James J. Hasbrouck Jan 1991

Demographic Responses Of Raccoons To Varying Exploitation Rates , James J. Hasbrouck

Retrospective Theses and Dissertations

The Cox's proportional hazards model indicated higher harvest levels significantly increased mortality of birth-year (BY) raccoons but not of animals ≥1 year old (ABY). Mortality of ABY males was significantly greater than that of ABY females. Hunters had a marginally significant (P = 0.10) effect on harvest mortality of BY raccoons but neither hunters nor trappers contributed significantly to harvest mortality rate of ABY raccoons. Activity and behavior patterns may contribute to greater harvest mortality of BY raccoons and ABY male raccoons;Monte Carlo simulations were done to investigate bias, efficiency and confidence interval coverage of the Kaplan-Meier (KM ...


An Economic Analysis Of Agroforestry Farming Systems In Zambia: Application Of Risk Programming And Risk-Free Modelling Techniques , Leyeka Charles Lufumpa Jan 1991

An Economic Analysis Of Agroforestry Farming Systems In Zambia: Application Of Risk Programming And Risk-Free Modelling Techniques , Leyeka Charles Lufumpa

Retrospective Theses and Dissertations

Declining soil fertility is one of the many problems facing Zambian agriculture today. The increase in permanent cultivation practices, combined with reduced forest fallow have contributed to the decline in soil fertility. In response to this state of affairs, farmers continue to increase the use of chemical fertilizers as a way of maintaining soil productivity;However, although production and productivity in the agricultural sector has increased over the years, small-scale farmers continue to register low productivity levels. Increases in agricultural production in the small-scale farm sector are mainly achieved by increasing land area under cultivation. For Zambia this means that ...


Metallothionein And Bioaccumulation Of Cadmium In Juvenile Bluegills Exposed To Aqueous And Sediment-Associated Cadmium , William Gregory Cope Jan 1991

Metallothionein And Bioaccumulation Of Cadmium In Juvenile Bluegills Exposed To Aqueous And Sediment-Associated Cadmium , William Gregory Cope

Retrospective Theses and Dissertations

I evaluated metallothionein (MT), free (unbound) hepatic cadmium and whole body cadmium as indicators of cadmium exposure in juvenile bluegills Lepomis macrochirus in laboratory tests. Two types of cadmium exposure were tested; aqueous and sediment-associated. In the aqueous tests, fish were exposed to cadmium (0.0 to 32.3 [mu]g/L) in an intermittent-flow diluter. The experimental design for the aqueous exposure was completely randomized and included two replicates in each of eight treatments (seven cadmium exposures and one water control). In the sediment-associated cadmium test, fish were exposed to resuspended river sediment containing 1.3 to 21.4 ...


Influence Of Root System Morphology And Site Characteristics On Development Of Transplanted Northern Red Oak (Quercus Rubra L.) Seedlings , Janette R. Thompson Jan 1991

Influence Of Root System Morphology And Site Characteristics On Development Of Transplanted Northern Red Oak (Quercus Rubra L.) Seedlings , Janette R. Thompson

Retrospective Theses and Dissertations

The purpose of this study was to evaluate the performance of one-year-old red oak seedlings with graded root systems on different sites, to determine if initial root system morphology would influence seedling survival and growth, and to determine whether differences in root system quality would be important over time regardless of outplanting site characteristics. Nursery-run bare-root northern red oak seedlings from the Iowa Department of Natural Resources State Forest Nursery in Ames were graded according to numbers of large first-order lateral roots and outplanted in spring, 1987, on nine plots distributed among three sites in central Iowa;Annual counts of ...


Behavior And Ecology Of Post-Fledging American Kestrels , Daniel E. Varland Jan 1991

Behavior And Ecology Of Post-Fledging American Kestrels , Daniel E. Varland

Retrospective Theses and Dissertations

I studied the behavior, habitat and perch use, causes of mortality, and time to dispersal of post-fledging American Kestrels (Falco sparverius) during spring and summer 1988-1990 in central Iowa. To monitor kestrel activity, I attached radio-transmitters to 64 birds in 50 nests. All young in the study fledged from nest boxes, most of which (N = 47) were attached to the backs of highway signs along the Interstate-35 (I-35) right-of-way;During the first week after fledging, kestrels spent <1% of their time foraging or flying; the remainder was spent in inactive behavior. Kestrels fledging from nests along the interstate were observed at this time primarily in cropland and along the interstate right-of-way, where they frequently perched on the ground;All but 1 of the 16 kestrels found dead died during the first week after fledging, before flying skills had developed. Mammalian predation accounted for six deaths and was the main cause of mortality. Only 2 of 61 radio-marked kestrels that fledged from nest boxes along the interstate died because of a collision with a vehicle;As kestrels grew older, perch resting decreased whereas perch hunting increased. Post-fledging kestrels fed almost exclusively on invertebrates, and mean hunting success did not exceed 55%;In 1988-1989, I observed social hunting among siblings, families, and also among unrelated kestrels. Social hunting occurred during both perch hunting and ground hunting. Social foraging in these kestrels was imitative rather than cooperative;In 1990 I observed experimentally adjusted broods of two and five post-fledging American Kestrels to test two hypotheses: (1) imitative social foraging increases foraging efficiency, and (2) individuals in large broods will disperse sooner than individuals in small broods. No differences in foraging efficiency or in dispersal time were detected, but sample sizes were small because of high mortality or signal failure among radio-marked birds;Kestrels fledging from nest boxes along the interstate hunted extensively along secondary roads. Mean time until the initiation of dispersal of kestrels along the interstate was 22.7 d after fledging. Band recoveries provided little evidence of natal philopatry.


Leaf Age Heterogeneity Among Selected Populus Clones: 1 Influences On Feeding And Oviposition Preferences Of Adult Chrysomela Scripta F (Coleoptera: Chrysomelidae): 2 Correlations Of Preferences With Foliar Phenolic Glycoside Profiles , Barbara Ruth Bingaman Jan 1991

Leaf Age Heterogeneity Among Selected Populus Clones: 1 Influences On Feeding And Oviposition Preferences Of Adult Chrysomela Scripta F (Coleoptera: Chrysomelidae): 2 Correlations Of Preferences With Foliar Phenolic Glycoside Profiles , Barbara Ruth Bingaman

Retrospective Theses and Dissertations

The cottonwood leaf beetle, Chrysomela scripta F., (Coleoptera: Chrysomelidae), is considered to be one of the more serious defoliators of plantation Populus in North America. This research was undertaken to examine the effects of leaf age and plant chemicals on the feeding and oviposition behaviors of adult beetles. The most preferred leaf age class was established for both behaviors and the composition and concentration of selected phenolic glycosides were analyzed for the most and least preferred leaf age classes. Correlations were then made between the phenolic glycoside profiles of the leaves and the host preferences of the beetles for both ...


The Economics Of Food Safety: An Experimental Approach , Seung Youll Shin Jan 1991

The Economics Of Food Safety: An Experimental Approach , Seung Youll Shin

Retrospective Theses and Dissertations

Food safety issues have received increased attention from scientific and consumer groups alike in recent years. Pathogenic microbiological agents have been shown to be a major contributor to food-borne illnesses in the United States. The presence and cost of these pathogens has become a major issue for policy makers, consumers, and producers;Estimated economic losses to society attributable to food-borne diseases have been large. These estimated losses usually have been based on direct consumer losses and likely represent an underestimation of the true economic costs. Morbidity costs, such as consumers' willingness to pay (WTP) to reduce their chance of becoming ...


Using The Land Evaluation And Site Assessment (Lesa) Technique In The Rural-Urban Fringe: A Case Study Of Dallas County, Iowa, Brian Ray Schoon Jan 1991

Using The Land Evaluation And Site Assessment (Lesa) Technique In The Rural-Urban Fringe: A Case Study Of Dallas County, Iowa, Brian Ray Schoon

Retrospective Theses and Dissertations

No abstract provided.


Application Of The Creams Model To Simulate Performance Of Riparian Tree Buffer Strips: Implications For Buffer Strip Design, Matthew Forrest Christian Jan 1991

Application Of The Creams Model To Simulate Performance Of Riparian Tree Buffer Strips: Implications For Buffer Strip Design, Matthew Forrest Christian

Retrospective Theses and Dissertations

No abstract provided.


The Perceptions Of Iowa Farmers Toward Integrated Pest Management, And, Beauveria Bassiana (Balsamo) Vuillemin In The Corn Ecosystem: Its Effect On Coleomegilla Maculata Degeer, Randall Lee Pingel Jan 1991

The Perceptions Of Iowa Farmers Toward Integrated Pest Management, And, Beauveria Bassiana (Balsamo) Vuillemin In The Corn Ecosystem: Its Effect On Coleomegilla Maculata Degeer, Randall Lee Pingel

Retrospective Theses and Dissertations

No abstract provided.