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

Life Sciences Commons

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

Retrospective Theses and Dissertations

Environmental Sciences

Botany

Articles 1 - 13 of 13

Full-Text Articles in Life Sciences

Floristic Analysis Of Central Iowa Woodlands, And Comparison Of Reproduction And Regeneration In Common And Restricted Herbaceous Species , Catherine Mary Mabry Jan 2000

Floristic Analysis Of Central Iowa Woodlands, And Comparison Of Reproduction And Regeneration In Common And Restricted Herbaceous Species , Catherine Mary Mabry

Retrospective Theses and Dissertations

I studied the distribution and abundance of the plant species of forests in central Iowa, emphasizing the effect of cattle grazing on the vegetation. I used traits to identify groups of species that may function as guilds, and to address whether species' frequency was related to traits. To understand the difference between species that were common compared to those relatively less common (restricted species), I examined whether the two groups differed in reproductive output and allocation, seed viability, and seedling emergence;Understory species and canopy trees were generally distributed along the same environmental gradients. These were landform, soil phosphorous and ...


Nitrate Removal Capacity Of Constructed Wetlands , Richard Gregory Phipps Jan 1997

Nitrate Removal Capacity Of Constructed Wetlands , Richard Gregory Phipps

Retrospective Theses and Dissertations

Constructed wetlands at the Des Plaines Wetland Demonstration Project in Wadsworth, Illinois were examined for their capacity to remove nonpoint source loads of nitrate from an agricultural watershed. Three flow through wetlands received different loading rates of pumped river water with seasonably variable loads of nitrate and organic nitrogen. The nitrogen removal capacities of the wetlands were estimated using mass balance and sediment-water microcosms for the 1991 and 1992 field seasons. Concentrations of nitrogen and flow volumes were monitored at inlets and outlets and mass balances of nitrogen loads were calculated. The wetlands received two different loading rates in 1991 ...


The Role Of Arbuscular Mycorrhizal Fungi In Prairie Wetlands , Paul Robert Wetzel Jan 1996

The Role Of Arbuscular Mycorrhizal Fungi In Prairie Wetlands , Paul Robert Wetzel

Retrospective Theses and Dissertations

Research on arbuscular mycorrhizal fungi (AMF) suggests that their effect on plant growth is a continuum that changes from positive to negative along environmental gradients as conditions for plant growth improve. Prairie wetlands were used to test this mycorrhizal continuum model. First, three saline and three freshwater wetlands were surveyed for AMF, to investigate the hypothesis that AMF colonization would be greater in wetlands with high soil salinity, lower nutrient levels, and during periods of drought. Second, a greenhouse experiment on Carex stricta and Calamagrostis canadensis tested whether AMF improved plant growth and nutrient uptake under five hydrologic regimes. Third ...


Effects Of Emergent Vegetation On Wetland Microbial Processes , Charles Lee Rose Jan 1996

Effects Of Emergent Vegetation On Wetland Microbial Processes , Charles Lee Rose

Retrospective Theses and Dissertations

Wetland areas with varying amounts of emergent and free-floating vegetation may have very different microbial carbon and energy processing rates and and pathways. In Goose Lake Marsh, a natural prairie pothole wetland in central Iowa, transect measurements, continuous monitoring, and synoptic surveys were used to examine patterns light availability, temperature, dissolved O2 concentrations, dissolved CH4 concentrations, plant densities, litter densities, and CH4 flux due to diffusion and ebuliation within and outside emergent vegetation zones. Water column light availability was less than 2% of ambient light in emergent vegetated areas due to canopy cover, small floating plants (lemnids), and plant litter ...


A Natural Area Inventory Of Ames, Iowa , William Russell Norris Jan 1995

A Natural Area Inventory Of Ames, Iowa , William Russell Norris

Retrospective Theses and Dissertations

Perhaps no state in the Union has suffered such widespread degradation of its natural vegetation as Iowa. Tallgrass prairie (including wet prairie communities, often considered to be wetlands) once covered at least 85% of this state's land area, but more than 99.9% of Iowa's original grasslands have fallen victim to the plow (Smith 1990). Wetlands once covered 11.1% of Iowa's landscape (Dahl 1990), but virtually all of these have been drained to make way for rowcrops (wetlands now cover only 1.2% of Iowa's landscape). Roughly 12 to 20% of the state was covered ...


Sorption Kinetics Of Atrazine And Hydroxyatrazine In Freshwater Wetlands, Michael Patrick Matter Jan 1993

Sorption Kinetics Of Atrazine And Hydroxyatrazine In Freshwater Wetlands, Michael Patrick Matter

Retrospective Theses and Dissertations

No abstract provided.


Qualitative Characterization Of The Endogenous Cytokinins In Red Pine And Aspects Of Their Influence On Seedling Development , Richard Meilan Jan 1990

Qualitative Characterization Of The Endogenous Cytokinins In Red Pine And Aspects Of Their Influence On Seedling Development , Richard Meilan

Retrospective Theses and Dissertations

Red pine seedlings alternate between root and shoot production in a periodic fashion. This habit is referred to as episodic growth and is assumed to be controlled by endogenous plant growth regulators. This project was concerned with the role played by cytokinins in the control of episodic growth;After confirming the existence of episodic growth in red pine seedlings, a carrier solution was optimized and a series of exogenous application trials was conducted. Only those solutions containing a surfactant and N[superscript]6-benzylaminopurine (BAP) produced an observable response. Foliar applications of BAP induced the formation of an apical cluster of ...


Restoration Of Remnant, Native Warm-Season Grasses On Southern Iowa Pastureland, Thomas Robert Rosburg Jan 1990

Restoration Of Remnant, Native Warm-Season Grasses On Southern Iowa Pastureland, Thomas Robert Rosburg

Retrospective Theses and Dissertations

No abstract provided.


Abundance, Distribution, And Diversity Of Buried Seed Populations In The Delta Marsh, Manitoba, Canada , Roger Lynn Pederson Jan 1983

Abundance, Distribution, And Diversity Of Buried Seed Populations In The Delta Marsh, Manitoba, Canada , Roger Lynn Pederson

Retrospective Theses and Dissertations

Several plant communities in the Delta Marsh were analyzed with respect to the distribution, abundance, diversity, and temporal variation in buried seed populations and annual seed rain. Numbers of germinable seeds were measured by placing substrate and seed trap soil samples under two simulated environmental conditions (drawdown and shallow-flooded) in an outdoor shelter;From the seed bank, four times as many seedlings and twice as many species occurred in substrate samples under the drawdown treatment as compared to samples under the shallow-flooded treatment. Many of the common species in the seed bank (Scirpus validus), (Scripus maritimus), Rumex maritimus, Aster brachyactis ...


The Vegetation Of Ledges State Park, Boone County, Iowa, Cindy Lee Johnson-Groh Jan 1983

The Vegetation Of Ledges State Park, Boone County, Iowa, Cindy Lee Johnson-Groh

Retrospective Theses and Dissertations

No abstract provided.


Effects Of Varying Concentrations Of Certain Major And Minor Nutrients On The Interaction Between A Blue-Green Alga And A Diatom, Howard David Markus Jan 1979

Effects Of Varying Concentrations Of Certain Major And Minor Nutrients On The Interaction Between A Blue-Green Alga And A Diatom, Howard David Markus

Retrospective Theses and Dissertations

No abstract provided.


Competitive Ability Of Five Populations Of Amaranthus Retroflexus L. , Terry Charles Heiner Jan 1970

Competitive Ability Of Five Populations Of Amaranthus Retroflexus L. , Terry Charles Heiner

Retrospective Theses and Dissertations

No abstract provided.


Prairie Flora On The Missouri River Bluffs Of Western Iowa , John Barstow Morrill Jr. Jan 1953

Prairie Flora On The Missouri River Bluffs Of Western Iowa , John Barstow Morrill Jr.

Retrospective Theses and Dissertations

In western Iowa, from Sioux City south to Hamburg, the Missouri River flood plain is bordered by a series of abrupt loess bluffs. Because of the wide variability in exposure, because of the characteristic wind-deposited loess and because of the accessability to river migration routes, the bluffs possess a diverse, albeit characteristic flora. Investigations of localized or specialized ecological niches frequently yield not only floristic data but insight into historical development and migration movements of both individual species and floristic units. For instance, McLaughlin (1932) in his study of the sand barren flora of northwest Wisconsin was able to show ...