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Articles 1 - 13 of 13

Full-Text Articles in Life Sciences

Analysis Of Fish Communities In Illinois Lakes , Douglas J. Austen Jan 1992

Analysis Of Fish Communities In Illinois Lakes , Douglas J. Austen

Retrospective Theses and Dissertations

Fish community structure and the main environmental factors influencing community structure were studied using a database of fish population surveys and limnological information describing 144 Illinois lakes. Data were collected by Illinois Department of Conservation fisheries biologists in a standardized manner using electrofishing and gill nets. Population survey data were adjusted using equations estimating efficiency of the gears under varying conditions resulting in estimates of biomass and number of fish per hectare;Guild systems were used to describe the communities and to simplify the analysis of fish community data thus allowing for comparison of community structure between lakes of varying ...


Export Performance And Export Demand Of Indonesian Forest Products , Komara Djaja Jan 1992

Export Performance And Export Demand Of Indonesian Forest Products , Komara Djaja

Retrospective Theses and Dissertations

Indonesian forest product exports have been growing significantly from a yearly average of U.S. 0.4 billion in 1970/74 to U.S. \2.4 billion in 1985/89. Using the constant market share (CMS) model, the results indicate that the impressive growth of Indonesian forest product exports over the period 1970/74-1985/89 attributed to the world trade effect and to the competitiveness effect was 50 and 82 percent, respectively. The commodity composition effect and market distribution effect were somewhat unfavorable; it was -29 and 1 percent, respectively. The CMS results suggest that, to obtain more benefit from ...


Survival And Movements Of Pheasant Chicks In Northern Iowa On Differing Agricultural Landscapes, Dean Edward Ewing Jan 1992

Survival And Movements Of Pheasant Chicks In Northern Iowa On Differing Agricultural Landscapes, Dean Edward Ewing

Retrospective Theses and Dissertations

No abstract provided.


Measurement And Simulation Of Water Table Management Effects On Groundwater Quality , Prasanta Kumar Kalita Jan 1992

Measurement And Simulation Of Water Table Management Effects On Groundwater Quality , Prasanta Kumar Kalita

Retrospective Theses and Dissertations

The goal of this study was to investigate the effect of various water-table management (WTM) practices on corn growth and yield and agricultural chemical concentrations in shallow groundwater. Field experiments were conducted for three years (1989-91) at the research sites near Ames and Ankeny. Water-table depths of 0.3, 0.6, and 0.9 m were maintained in field lysimeters at the Ames site, and variable water-table depths were maintained in a subirrigation field at the Ankeny site;Photosynthesis measurements were made regularly during the growing season, and yield data were collected at harvest. In 1989, a relatively dry year ...


Comparative Ecology Of Two South American Foxes, Dusicyon Griseus And D Culpaeus , Warren E. Johnson Jan 1992

Comparative Ecology Of Two South American Foxes, Dusicyon Griseus And D Culpaeus , Warren E. Johnson

Retrospective Theses and Dissertations

Culpeo (Dusicyon culpaeus) and South American grey fox (D. griseus) have comparable ranges, but the factors determining local and geographic distribution are unknown. I first review the best documented cases of sympatry in canids, and discuss the implications this analysis has on canid conservation. I then compare the behavioral ecology of grey and culpeo fox in Torres del Paine National Park, Chile and review hypothetical factors that determine their distribution when sympatric;The number of sympatric canids per area seems to be determined by a combination of biogeographical history, human intervention, and environmental diversity and productivity. Sympatric canid species either ...


Business Planning For Marketing Low-Quality Hardwoods , Curtis Lawrence Krambeer Jan 1992

Business Planning For Marketing Low-Quality Hardwoods , Curtis Lawrence Krambeer

Retrospective Theses and Dissertations

Increased utilization of low-quality hardwoods would aid in the management options of hardwood stands. With market development, materials of poor quality could be moved to productive uses while allowing higher quality stock more growing room. A description of a concentration and marketing center is offered that is designed to provide a simple selling opportunity for land owners and timber improvement contractors;This study develops a financial spreadsheet template to aid in feasibility analysis and business planning for potential marketing center scenarios. The spreadsheet and its accompanying documentation identify input data requirements. By identifying input needs for the spreadsheet, this study ...


Factors Affecting The Trophic State Of Iowa Lakes, Lorin Kent Hatch Jan 1992

Factors Affecting The Trophic State Of Iowa Lakes, Lorin Kent Hatch

Retrospective Theses and Dissertations

No abstract provided.


Modeling Spatial Variability And Transport Processes In A Glacial Till Soil , Binayak Prasad Mohanty Jan 1992

Modeling Spatial Variability And Transport Processes In A Glacial Till Soil , Binayak Prasad Mohanty

Retrospective Theses and Dissertations

The objective of this study was to investigate the spatial variability of different physical and chemical properties of soils, and their role on transport processes of chemicals to groundwater sources in a glacial till soil of central Iowa;Measurements were made to determine the in-situ saturated hydraulic conductivity (K[subscript] sat) of a glacial till soil at sixty six sites in a tillage established plot. One hundred thirty-two data points on K[subscript] sat collected at two soil depths along two bisecting perpendicular transects, were used to develop semivariogram models, in conjunction with split-window median polish approach. Nested structure with ...


Epidemiological Study Of Foliar Diseases With Strip Intercropping Rotation In Iowa , Kayimbi Mendha Tubajika Jan 1992

Epidemiological Study Of Foliar Diseases With Strip Intercropping Rotation In Iowa , Kayimbi Mendha Tubajika

Retrospective Theses and Dissertations

Diseases were assessed in maize, soybean, and oat, which were growing with narrow strip intercropping. Strip intercropping may nullify the disease control benefit of crop rotation because one edge of every strip is contiguous with the debris of the same crop left in the field from the prior year. Two multifactorial strip intercrop experiments at the McNay Research Center in South Central Iowa and two strip intercrop commercial fields in Northeastern Iowa were studied in 1990 and 1991. Two fields near Ames were also assessed in 1991;The major foliar diseases were: Septoria blight of oat (Septoria avenae), brown spot ...


Attitudes And Behaviors Of Iowa Farmers Toward Wildlife , James L. Pease Jan 1992

Attitudes And Behaviors Of Iowa Farmers Toward Wildlife , James L. Pease

Retrospective Theses and Dissertations

This research examines the attitudes and behaviors of Iowa farmers toward wildlife. Based on a 1991 statewide mailed survey of 822 farmers, it divides Iowa farmers into "wildlife-oriented" and "non-wildlife-oriented" groups for sampling and analysis. It identifies demographic and personal factors that are correlated with a wildlife orientation. Wildlife-oriented farmers in Iowa tend to be farmers with smaller acreages overall, with smaller gross farm incomes, with fewer acres devoted to row-crops, and with more diverse landscapes that more often include trees, streams, Conservation Reserve Program acres or other non-agricultural land than farmers who are not wildlife-oriented. Wildlife-oriented farmers also engage ...


Supply And Demand For Wood As A Source Of Energy In Zambia: An Econometric Analysis , Christopher Mupimpila Jan 1992

Supply And Demand For Wood As A Source Of Energy In Zambia: An Econometric Analysis , Christopher Mupimpila

Retrospective Theses and Dissertations

The significance of biomass energy in developing countries has increasingly attracted a great deal of attention. The basis of the interest in biomass energy is often considered to be the 1973 oil crisis, which, among other things, focused attention on renewable sources of energy. As a result of the crisis, it became apparent that traditional biomass fuels--firewood, charcoal, crop residuals, and cow dung--were the primary cooking and heating fuels for the majority of the population in developing countries, especially the rural and urban poor. The situation remains the same today, biomass fuels are the primary domestic fuels for the majority ...


Factors Affecting Adoption And Level Of Information Of Sustainable Agriculture Practices By Farmers In Central Iowa, Naomi Kay Harrold Jan 1992

Factors Affecting Adoption And Level Of Information Of Sustainable Agriculture Practices By Farmers In Central Iowa, Naomi Kay Harrold

Retrospective Theses and Dissertations

No abstract provided.


Fertilizer Fate Under Golf Course Conditions In The Midwestern Region, Steven Kent Starrett Jan 1992

Fertilizer Fate Under Golf Course Conditions In The Midwestern Region, Steven Kent Starrett

Retrospective Theses and Dissertations

No abstract provided.