NRSM Dissertations

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Remote sensing for regional assessment and analysis of Minnesota lake and river water quality
(2012-05) Olmanson, Leif Gordon
Beginning soon after the launch of the first Landsat satellite, researchers began investigating the use of Landsat imagery to monitor the water quality of our lakes and coastlines. The earliest use of Landsat imagery was for simple qualitative observations which included locating and mapping pollution and pollution plumes. Shortly thereafter, field measurements of water quality were correlated with Landsat data and later these correlations were used for quantitative assessment of water quality (e.g., turbidity, chlorophyll and water clarity). This dissertation expands on this earlier work and describes results of research to develop and use remote sensing tools for regional water quality assessment to improve the understanding and management of Minnesota's lakes and rivers. It includes four major components. First, a 20-year, 1985-2005, comprehensive water clarity database for more than 10,500 lakes at approximately five-year intervals for the time period 1985-2005, which includes almost 100,000 individual estimates of lake water clarity, was compiled and evaluated. Second, the results of a statistical analysis of the Landsat database for geospatial and temporal trends of water clarity over the 20-year period, as well as trends related to land cover/use and lake morphometry, are reported. Third, the advantages of improved spectral and temporal resolution and disadvantages of the lower spatial resolution of the global MODIS and MERIS systems are evaluated for regional-scale measurements of lake water clarity and chlorophyll of large lakes in Minnesota and compared with Landsat. Finally, aerial hyperspectral spectrometers were used to collect imagery with high spatial and spectral resolution for use in identifying, measuring and mapping optically related water quality characteristics of major rivers in Minnesota for three time periods that represent different water quality and flow regimes.
Tree regeneration dynamics and drivers across the temperate-boreal transition zone.
(2012-03) Fisichelli, Nicholas Anthony
The upper Great Lakes region in central North America contains a forest transition zone where temperate and boreal tree species reach their northern and southern range limits, respectively. It is only within this narrow latitudinal band (~3 degrees), that relatively warm-adapted temperate and cold-adapted boreal tree species are found growing together in upland mesic sites. If climate is a main driver of forest dynamics within this region, recent and predicted climate change should result in major forest shifts, including the expansion of temperate species and range contraction of boreal species. Such changes should first be manifest in growth and abundance trends of tree species in the understory regeneration layers. In addition to climate, numerous other factors such as overstory composition, understory abiotic environment, competition with shrub and herbaceous layers, and browse pressure drive tree regeneration trends. Interrelationships and interactions among these drivers will ultimately determine the direction and rate of forest change. We explored these research topics through field studies of naturally established seedlings and saplings at 124 upland mesic forest sites across a three state (Minnesota, Wisconsin, and Michigan U.S.A) 170,000 km2 area of the temperate-boreal transition zone. Chapter 1 examined relative abundance shifts of temperate and boreal tree regeneration at two spatial scales: local ecotonal boundaries between temperate and boreal dominated stands and across the regional temperate-boreal transition zone. Because we compared understory performance across locally changing overstory composition, we calculated species regeneration success as the difference in relative abundance between the understory and overstory layers. At the local scale, both shade-tolerant temperate and boreal species exhibited positive tree regeneration success across ecotonal boundaries. However, across the region, regeneration performance varied with mean summer temperature and to a lesser extent mean annual precipitation. Changes in regeneration success were generally greatest at the warm end of the transition zone, with temperate broadleaf Acer saccharum, Fraxinus nigra, and Ostrya virginiana responding positively and boreal Abies balsamea showing significantly reduced performance. For the most frequent temperate species, Acer rubrum, regeneration success was greatest in boreal neighborhoods and at cool and dry sites. Other species did not exhibit detectable shifts in regeneration success, potentially due to traits such as shade-tolerance, palatability, and mode of reproduction. Overall we found that numerous tree species growing across the temperate-boreal transition zone are likely sensitive to climate at early stages of development, with observed shifts in regeneration success concomitant with the direction predicted in response to climate change. Chapter 2 assessed the relative importance of and interrelationships among explanatory variable sets in explaining the composition of the tree regeneration layer. We used redundancy analysis (RDA) and variation partitioning to quantify the unique, shared, and total explanatory power of four sets of drivers: climate, understory abiotic environment, overstory composition, and understory biota. The results showed that all four driver sets individually explained a significant portion of tree regeneration compositional variation and additionally that there were strong relationships among explanatory variables. Overstory composition, which directly influences seed availability and also was found to be closely associated with understory environmental conditions and biota, had approximately twice the explanatory power of any of the other three driver sets. Some of the strongest individual drivers were overstory Acer saccharum and Populus tremuloides, soil pH, mean summer temperature, and mean annual precipitation. Suites of associated drivers included cool, moist, sandy, and acidic conditions; overstory boreal broadleaf species, light availability, shrub abundance, and forb cover; and warm temperatures and graminoid cover. Due to the strong interrelationships among drivers, the direction and rate of forest change will likely depend on how the importance of drivers shifts with climate and, for the biotic drivers, on the rate and magnitude of their own responses to climate change. Chapter 3 investigated sapling height and radial growth rates of five temperate and boreal species. This study included over 1700 stems of naturally established, competing saplings growing at 14 sites across the temperate-boreal transition zone. Top performing linear mixed-effects models typically included two-way interactions among mean summer temperature, browse pressure, understory light levels, and initial sapling size. As hypothesized, temperate sapling growth increased and boreal growth decreased with increasing temperatures. However, the relative performance of competing species shifted depending on the level of browse pressure. Positive temperate growth responses to temperature were eliminated by heavy browse pressure, tilting growth rates in favor of less palatable boreal conifers at all but the warmest sites. Spatial variations in browse pressure levels across the region suggest that temperate expansion may proceed most rapidly in areas where browsing is least intense. Growth responses to temperature also varied with sapling size and, for the least shade-tolerant species in the study, Quercus rubra, light availability. Enhanced growth by temperate species in response to warmer temperatures was most detectable under favorable conditions including low browse pressure and high understory light availability, suggesting that any efforts to facilitate forest compositional changes will need to take into account these trends.
How law matters to ecosystem restoration.
(2012-02) Enzler, Sherry Anne
The 2005 Millennium Ecosystem Assessment reported unprecedented degradation of ecosystems and the services they provide to human well being which, if allowed to continue, could adversely affect human health, security and welfare. Our environmental legal authorities and policies, however, are not well designed to protect the health of our nation's ecosystems focusing instead on clean air, clean land and clean water as single medium, often referred to as the silo approach to environmental protection. Protecting ecosystems requires that we move away from this silo approach to a multi systems approach to environment and ecosystem management in both policy and law. How can we motivate the necessary changes in our legal constructs and political systems? This is a question posed by a number of communities and states struggling with the concept of ecosystem protection. Applying a Modified Destabilization theory this research explores whether and under what conditions the strategic use of litigation by environmental social movements can destabilize established legal constructs to protect ecosystems. Using the Mono Lake and Everglades' restoration event histories the Modified Destabilization Model is used to examine the role law played in struggles to change the political and social systems necessary to protect, restore and rehabilitate ecosystems. This analysis increases our understanding of the elements necessary to move to change the political and social structures to achieve systems approach to ecosystem management and the ability of social movements to mobilize law and litigation to accomplish the political and social change necessary to protect ecosystem.
The role of harvest gaps in the plant diversity of a northern hardwood forest of Northern Wisconsin, USA
(2011-08) Kern, Christel
Recent losses of biodiversity in managed forests have invigorated the need for natural disturbance-based management that sustains the many goods and services expected from forests. Regionally, declines in species diversity of managed northern hardwood forests have prompted the need for alternative approaches to forest management. One approach to natural disturbance-based management is using harvest gaps to emulate natural gaps that result from canopy disturbances. In this dissertation, I examine harvest gaps and their influence on ground-layer plants in the context of canopy gap theory. With the help of others, I measured four planted tree species and ground-layer vegetation (woody and herbaceous) abundance within a field experiment located in a second-growth northern hardwood forest of northern Wisconsin. The experimental approach included a gap opening gradient (five gap sizes, 6, 10, 20, 30 and 46 m diameter, and undisturbed reference areas) and a temporal gradient (0, 2, 6, and 13 years after gap creation). Ground-layer plant community composition and functional traits differed among gap sizes supporting theory. Gaps of all sizes differed in composition from undisturbed areas and all pair-wise combinations of gap size also differed in composition, except the 6 m and 10 m gaps. Compositional differences in gap size were evident two years after gap creation and grew more pronounced over the 13 year period. Species' functional traits and micro-environments were related to variation in ground-layer composition. The correlation between gap size and ground-layer plant composition provides evidence for gap partitioning by the ground-layer community in this forest. In addition, medium gap sizes were more diverse than smaller or larger gaps, supporting the concept that intermediate disturbances maximize species diversity. Furthermore, survival and growth of planted yellow birch, white pine, red oak, and hemlock seedlings was lower than expected growth and survival based on prior empirical and theoretical results. Growth and survival responses to gap sizes are dampened by deer browsing and shrub competition. This dissertation argues that harvest gaps play a role in plant diversity at multiple scales and provides an ecological framework for management decisions regarding gap size and its relationship to the ground-layer plant community.
Water yield in the southern Appalachian Mountains.
(2011-05) Kove, Katherine Marie
With over 55% forest cover, the southern Appalachians (SA) are a main water resource for the surrounding areas. These water resources are at risk due to changing climate and precipitation regimes as well as changes in forest cover. Understanding the implications of these risks will help to develop management strategies for an increasingly valuable resource. Evapotranspiration (ET), the combination of plant transpiration and surface evaporation, can vary across space and time, and is a significant component of the hydrological cycle in densely forested regions. Quantifying ET is critical to understanding the available water resource, especially in the SA. In the SA, ET averages 50% of annual precipitation in forested watersheds and can climb to 85%. However, ET is among the most difficult and complex component of the water cycle to measure and model. This dissertation addresses these complexities by investigating the ability of sap flow models to estimate ET and examining the impact of potential temperature and compositional shifts on water yield. We also examined sap flow input variables to determine the best methods for the SA including the spatial estimation of climatological variables, phenological dates, and leaf area index (LAI) estimates all of which would particularly enhance the development of our hydrological models.
The molecular weight effects of poly(acrylic acid) on calcium carbonate inhibition in the kraft pulping process.
(2011-05) Dubay, Matthew Richard
Calcium carbonate scale reduces process efficiency and control in kraft pulping operations. The formation of scale can be alleviated or at least reduced by the addition of antiscalant chemicals into the process line. A number of different antiscalants are commercially available but still little is known about their mechanism of inhibiting scale formation. This project focused on one class of antiscalants, the polymeric antiscalants, which are carboxylic acid containing copolymers, with the majority of their monomer residues being poly(acrylic acid). Scale inhibition performance at high pH and temperatures was characterized using a number of different experimental setups and the mechanisms involved were investigated. Performance tests yielded that the most influential characteristic of the polymeric antiscalants was the molecular weight (MW), and consequently, the molecular weight distribution (MWD) of the polymer species. Since commercial poly(acrylic acid) (PAA) samples have a broad MWD, atom transfer radical polymerization (ATRP) was utilized to create relatively monodisperse samples of PAA. These PAA samples synthesized via ATRP were used to investigate the effects of MW and MWD on antiscalant performance along with the mechanisms responsible for the observed optimal MW range of ~10,000 under laboratory kraft pulping conditions. The information presented here is useful both in identifying important properties of polymeric antiscalants and in understanding the mechanisms by which they inhibit the formation of calcium carbonate crystalline deposits in kraft pulping.
Survival and habitat use by post-fledging forest-nesting songbirds in managed mixed northern hardwood-coniferous forests.
(2010-10) Streby, Henry M.
Until recently, studies of breeding migratory songbirds have been primarily limited to the nesting season. Therefore, there is very little information about songbird survival and habitat use during the post-fledging period (i.e. the time between nesting and fall migration) available to those making management decisions. I expanded on the traditional nest-monitoring study and used radio telemetry to monitor survival and habitat use of fledgling songbirds in managed northern hardwood-coniferous forests of northern-Minnesota. In addition, I used mist-nets to sample use of early-successional forest stands (regenerating clearcuts) and forested wetlands by mature forest-nesting birds during the post-fledging period. I found that many assumptions of songbird nesting studies are unreliable, including the common assumption that the presence of a family group is confirmation of a successful nest in an occupied territory. In addition, I found that annual fledgling survival can vary considerably, and does not vary consistently with nest productivity, a finding with broad implications for models of songbird population growth. Furthermore, I found that habitat used by birds during the post-fledging period can be considerably different than that used for nesting, and that post-fledging habitat use can affect fledgling survival. In addition, I found that factors commonly affecting nest productivity (e.g. edge effects) can affect fledgling survival differently. From mist-netting, I found that many mature-forest birds used non-nesting cover types during the post-fledgling period, but most of that use was by only a few species, and hatch-year birds rarely used non-nesting cover types before independence from adult care. Models of capture rates in non-nesting cover types indicated that use of non-nesting cover types by mature-forest birds was primarily related to food availability and secondarily to cover in the form of relatively dense vegetation. My results indicated that nearly every conclusion made about breeding population ecology of mature-forest birds based only on nesting data was contradicted by data from the post-fledging period. My results clearly demonstrate that data from the entire breeding season (nesting and post-fledging) are necessary to understand songbird seasonal productivity and habitat associations.
When ripples becomes waves : exploring the role of policy in the creation and coordination of citizen participation in Minnesota‟s water governance landscape.
(2010-07) Steiger-Meister, Kaitlin
The term "environmental governance" is used to describe the increasingly collaborative nature of environmental natural resource policy creation and implementation that incorporates a diversity of third party actors ranging from government agencies to the profit sector, nonprofit sector, and civic society. Though the definition of environmental governance emphasizes collaborative efforts that include citizen participants, there is still a lack of information examining what the citizen perspective and experience is in collaborative natural resource management activities. Moving away from an emphasis on the components of successful citizen groups, this project reframes the issue of creating and coordinating citizen participation as a function of the institutional arrangements in which they are situated. Specifically, this project examines how local governmental units created out of statutory law to address local fresh water resource management issues interact with federal, state, and county agencies working in the field of fresh water conservation. Special attention is given to Minnesota's Lake Improvement District program, one of the state's lesser known citizen-driven water resource management initiatives, to highlight barriers to citizen participation from a grassroots perspective. Using a qualitative case study approach that includes in-depth interviews with citizens, government officials, and agency representatives, this project seeks to develop environmental policies that better coordinate water management activities across varying spatial scales (local, regional, national). Project findings offer insight to policymakers regarding the potential institutional hurdles that may appear when attempting to implement citizen participation practices into a previously established water governance system.
Renewable energy deployment in the electricity sector: three essays on policy design, scope, and outcomes
(2010-11) Fischlein, Miriam Lydia
Due to the large environmental impact of the electric energy sector, evaluating the policy instruments employed in this arena is a particularly pressing issue. In the United States, state policy is a major driver of sustainable energy development and provides a unique opportunity to conduct comparative policy research. Thirty-two states have implemented a renewable portfolio standard (RPS), a policy instrument that mandates renewable resource use. Although similar on the surface, these policies present staggering variation in the design elements they incorporate. This dissertation investigates patterns of policy design, scope and outcomes of RPS, contributing to the literature on policy design and effectiveness, and expanding the empirical knowledge of state sustainable energy policies. The first essay presents an in-depth state-by-state analysis of RPS design elements, complemented by the development of a policy classification scheme. Examining RPS design under the angle of stringency of goals, discretion in means, and strength of the enforcement regime introduces a measure of comparability. It highlights that a rigid focus on singular measures of policy strength and broad policy types detracts from understanding the impact of individual design features. The second essay underlines this argument, relating RPS design characteristics quantitatively to policy response. The results show that both more stringent goals and, to some extent, increased discretion in means are associated with higher policy response. The research design used is innovative, in that it accounts for the full complexity of RPS, while measuring outcomes at the level the policy targets (retail sales). The final essay concentrates on a single design attribute, policy scope. Focusing on a sector currently excluded from most state sustainable energy policies - consumer-owned utilities - it assesses future policy scenarios for their inclusion. To remediate the complete lack of emissions data on consumer-owned utilities, it develops for the first time a method to estimate the carbon intensity of electricity sales from this sector. Based on these estimates, future carbon management scenarios are developed for the inclusion of consumer-owned utilities in renewable policies, including interaction with energy efficiency policies.
Resource assessment and analysis of aspen-dominated ecosystems in the Lake States.
(2010-08) Domke, Grant Michael
Utilization of renewable resources for energy in the United States has increased substantially over the past decade. These increases have been driven by energy policy aimed at reducing dependence on foreign oil, boosting economic development, and curbing fossil fuel emissions. In recent years, state governments have passed laws mandating further reductions in energy consumption and greenhouse gas emissions, and increases in energy conservation and use of renewables. Such legislation and pending federal action has led to renewed interest in the use of forest-derived biomass for energy production. There are a variety of sources of forest-derived biomass in the Lake States and much debate over the carbon costs or benefits associated with the utilization of this material for energy. The aspen forest type is dominated by the most commercially utilized tree species in the region (Populus tremuloides and to a much lesser extent, P. grandidentata and P. balsamifera) and occupies more than 10 million acres of timberland in Michigan, Minnesota, and Wisconsin. Aspen is a short-lived, fast-growing tree species, which typically regenerates from adventitious suckers following harvest or stand-replacing disturbance, making it ideally suited for biomass production. This dissertation describes: 1) the status and trends of aspen-dominated ecosystems in the Lake States, 2) an analysis of biomass production potential in native and hybrid aspen communities in northern Minnesota, 3) a model framework for the estimation of carbon flows associated with the procurement and utilization of harvest residues for energy, and 4) the development of a spreadsheet-based model for rapid estimation of biomass availability.
Development of geospatial analysis tools for inventory and mapping of soils of the Chongwe Region of Zambia.
(2010-07) Shepande, Chizumba
Designing a methodology for mapping and studying soils in a quick and inexpensive way is critical especially in developing countries which lack detailed soil surveys. The main aim of this research was to explore the potential of Landsat ETM data combined with various forms of ancillary data in mapping soils in Chongwe, a semi arid region in Zambia. The study also examines how spectral maps produced by digital analysis of Landsat ETM data compare with field observation data. The study area, covering 54 000 ha, is located about 45 km to the east of the capital city, Lusaka, Zambia. It encompasses five main landscapes: hilland, piedmont, plateau, alluvial plain and valley dambos (seasonally waterlogged depressions). Geospatial tools were applied in four related chapters, (1) a review and discussion on the application of geospatial tools to aid soil mapping, (2) identification and characterization of soils in different landscapes in the Chongwe region of Zambia, (3) digital analysis of Landsat ETM data and its application to soil mapping, and (4) summary of the results, conclusions and suggestions for future research. This research has shown that visual interpretation and digital analysis of Landsat images have the capacity to map soils with reasonable accuracy. It demonstrates the utility of Landsat data to delineate soil patterns, especially when acquired during the dry season when there are long periods of cloud free skies, low soil moisture and minimal vegetation cover. When the accuracy of the Landsat ETM image was tested the agreement between Landsat ETM data and field reference data was 72%, indicating a definite relationship between Landsat imagery and soils types. Furthermore, the study revealed that overall, upland areas have a better agreement with Landsat spectral data compared to lowland areas, probably due to diverse origin of sediments and low spatial extent of most geomorphic units in lowland areas. In terms of soilscape boundary delineation, the Landsat derived map was better than the conventional soil map. Landsat data delineated more areas within the conventional soil map polygons. Examining the spectral responses in different bands, it was found that spectral bands, 3, 5, and 7 provide images of optimum contrast for the delineation of soilscapes.
Intensified biocatalysis for production of fuel and chemicals from lipids.
(2010-03) Zhao, Xueyan
Triglycerides are abundant biorenewable resources found in vegetable oils and fats. The effective utilization of triglycerides is one of the key interests in developing renewable fuels and products. However, triglycerides are difficult and inefficient to be used as fuels directly in regular combustion engines. The area of biodiesel synthesis concerns reactions converting triglycerides to methyl or ethyl monoesters for better fuel properties. This process releases glycerol as byproduct. This thesis aims at developing novel biocatalytic conversion of triglycerides and glycerol for the production of fuels and chemicals. One key challenge in realizing efficient biocatalytic synthesis of biodiesel is to improve reaction velocity and catalyst efficiency. This research explored a unique approach by developing organic-soluble lipase for a one-pot synthesis-and-use strategy. The productivities of the modified lipase in a water-free reaction system were found to be over two orders of magnitude higher than previously reported results. Whereas native lipases showed no activity in the absence of water, the organic soluble lipase demonstrated reaction rates of up to 33 g-product/g-enzyme-h. As for the byproduct (glycerol) from biodiesel synthesis, current research has mostly focused on derivation of value-added chemicals instead of being used as a simple additive in processing of food and personal care products. Key issues centered on how to produce the desired products most efficiently and selectively from glycerol. Enzymatic conversion of glycerol can produce 1,3-dihydroxyacetone (DHA), a unique and versatile chemical with a broad range of application potentials, by selective oxidizing the hydroxyl group(s) of glycerol. The price of DHA is more than 200 times higher than that of glycerol. In this work, DHA production was tackled through a novel biocatalytic process. Focus was placed on several aspects in understanding and optimizing the process including selection and improvement of biocatalyst, development of novel carbon electrode materials for cofactor regeneration, and reactor design. One potential advantage of using bioelectrochemical method for cofactor regeneration is the possibility to integrate the biochemical process with biofuel cells for simultaneous chemical production and power generation. Toward that, this thesis explored the necessary fundamental issues, including the construction and study of a model glucose/oxygen biofuel cell.
Integrating social considerations into managing white-tailed deer in Minnesota.
(2009-11) Cornicelli, Louis James
In Minnesota, 500,000 deer hunters annually harvest in excess of 200,000 deer and recent population size can be described as historically high. Integrating social carrying capacity with biological population objectives is a new concept for agency professionals who have historically managed white-tailed deer populations primarily for hunting interests. To manage overall population size, the Minnesota Department of Natural Resources (DNR) sets harvest objectives to determine the number of deer that should be taken in a given area. However, those objectives were set with no clearly defined deer population objective or long-term strategy for managing over-abundant populations, nor was there a mechanism to address situations where harvest opportunity was exhausted. To that end, I developed a method to identify statewide deer population objectives using a public participatory process. Concurrently, I evaluated the attitudes of deer hunters towards regulatory change and implemented a choice methodology to force selection of a management strategy that might achieve a population objective. Over a 3-year period, I also evaluated the attitudes and motivations of hunters participating in experimental regulations to determine factors that contribute to future hunt participation.
Quality connections: recreation , property ownership, place attachment, and conservation of Minnesota Lakes.
(2009-05) Schroeder, Susan Arlene
Recently, people have expressed concerns about how declining outdoor recreation participation and increasing housing development in high-amenity areas may affect conservation attitudes and behaviors as well as environmental quality. Recreation participation and property ownership have been identified as antecedents to place attachment. However, limited research has examined how people develop attachments to specific places and how these attachments relate to management preferences and support for conservation of specific areas. This study used data from two 2004 surveys addressing the management of lakes and aquatic plants in Minnesota. One study was conducted with a sample of Minnesota residents and the other with a sample of lakeshore landowners on "fisheries lakes" in the state. Data were analyzed to examine relationships among recreation participation, lakeshore property ownership, place attachment, and intentions to conserve lakes. Four clusters of recreationists were identified: all-around, appreciative, consumptive, and less-involved. Respondents were also segmented based on their ownership of lakeshore property, and whether property was used as a primary or second home. This study contributed to research on how participation in outdoor recreation relates to environmental attitudes and behavioral intentions. Results suggested that recreation participation relates to attitudes and behavioral intentions for lake protection. Among members of the general public, less-involved participants in lake-based recreation reported significantly lower intentions to take political or philanthropic action to protect lakes. Appreciative recreationists from the general public sample were more likely to take political action, while all-around and consumptive recreationists were somewhat more likely to donate time and money to protect lakes. Among lakeshore property owners, less-involved recreation participants reported lower personal responsibility for protecting their lake generally and a lower rating of personal norms for protecting native aquatic plants. However, all-around recreationists from the lakeshore property owner sample reported significantly higher behavioral intentions to remove native aquatic plants compared to appreciative, consumptive, and less-involved recreationists. The study advanced research on place attachment by: (a) examining visitors' and residents' attachment to Minnesota lakes and (b) how place attachment relates to conservation attitudes and behavioral intentions. Stronger place attachment was associated with property ownership and frequency of recreation participation. The study developed a scale to measure family connections to a lake, which was introduced in this dissertation as normative place attachment. Results supported previous research that has suggested: (a) a positive relationship between outdoor recreation and environmental attitudes, and (b) differences based on the type of recreation participation. Study findings suggested the importance of recreation participation to protection of Minnesota lakes. Participation in lake-based outdoor recreation was related to place attachment, personal responsibility, and behavioral intentions related to lakes. In particular, less-involved recreation participants reported lower levels of attitudinal and normative place attachment to lakes, expressed less personal responsibility for protecting lakes, and had the lowest intentions of taking philanthropic or political action to protect lakes. However, a substantial amount of unexplained variance remained in models of attitudes and behavioral intentions related to the protection of lakes and aquatic plants. Future studies of recreation, property ownership, place attachment, and conservation, could incorporate more comprehensive measures of recreation participation, place attachment, "insidedness" to a place, and environmental attitudes, and behavioral intentions. In addition, future research could examine the influence of place meanings, environmental values, social capital, sense of community, political ideology, educational background, and length of association with a place on environmental attitudes, behavioral intentions, and actual behaviors.
Land use and terrestrial carbon storage in Western North Carolina from 1850-2030: a historical reconstruction and simulation study.
(2009-07) Kirk, Ryan William
The Southern Appalachian Mountains have experienced large and dynamic land-use changes since arrival of Euro-American settlers in the late 18th and early 19th centuries. Following transfer of the land from Native American societies, successive waves of immigration, development, resource extraction, and abandonment have driven land use over the past 200 years. There are large uncertainties regarding the timing and magnitude of these changes, and as a result, there are large uncertainties on the effects these land use legacies have on ecological processes and services. This dissertation addresses these uncertainties by quantifying and spatializing land use in the region since 1850, forecasting land use through 2030, and evaluating the effects of land-use change on the storage of carbon in terrestrial forest ecosystems. The study area is the 21-county region of Western North Carolina that is part of the Blue Ridge physiographic province. Macon County, NC, and four watersheds within Macon County are used as detailed case studies. Decadal land use patterns were reconstructed using sparse spatial data derived from historic maps, aerial photographs, and satellite imagery, more frequent tabular estimates of land use from census data, and terrain-based geospatial models. Carbon accrual in aboveground woody biomass was estimated from yield models and applied across the landscape using terrain-based estimates of site quality. Within Macon County, timber harvest and agriculture area peaked during 1900-1910, and following recovery, total forest area peaked from 1960-1980. Since 1950, the total development footprint has tripled, with over 2/3 of new houses expanding into areas that were predominantly forested. Across the region, total agriculture and forest area are forecasted to decline 12% and 5%, respectively, by 2030 as development expands. Carbon in aboveground woody biomass decreased an estimated 80% between 1850 and 1930, from an average of 201 Mg ha-1 in 1850 to a low of 40 Mg ha-1 in 1930, with 84% of this loss due to industrial logging and 16% due to agriculture expansion. Since 1930, the forests have been aggrading carbon at a decreasing rate of 24% per decade in 1940 to 5% per decade since 1990. Although total forest area will decrease 4%, carbon storage is forecasted to increase 10% by 2030 assuming no large disturbance.
Spatial vegetation-environment relationships and distributional changes in the presettlement Minnesota prairie-forest boundary.
(2009-02) Danz, Nicholas P
The prairie-forest boundary region in Minnesota spans 650 km along a northwest-southeast axis and is often considered one of the most abrupt grassland-forest transitions in the world. Historically, this region separated tallgrass prairie vegetation to the south and west from forest vegetation to the north and east, while land conversion since presettlement has eliminated over 95% of original prairie and continues to convert and fragment forested lands. Ecological boundaries such as the prairie-forest transition are considered critical landscape elements that control the fluxes of organisms, materials, and energy between ecosystems. While the significance and characteristics of ecological boundaries has been often discussed in scientific literature, there are few studies that provide empirical support for boundary concepts. In particular, studies are lacking that evaluate vegetation-environment relationships across boundaries. In this thesis, I use the presettlement prairie-forest boundary as an example of an ecological boundary to address the following issues: 1) the influence of spatial scale and spatial heterogeneity in the controls of vegetation, 2) the spatial nature of a vegetation-climate relationship across the boundary, and 3) range distributional shifts since presettlement in tree taxa common to the boundary region.
Self-assembling multienzyme systems at oil-water interface for biphasic biotransformations
(2008-11) Narayanan, Ravindrabharathi
Living cells are highly organized with many functional units or organelles separated by membranes. The membrane is comprised of specific proteins and lipid components that enable it to perform its unique roles for that cell or organelle. At cellular membranes, lipid bilayers are stabilized laterally with the help of integral proteins. This stability is provided through a clustering of the hydrophobic core of both the lipid bilayer and the integral protein. Surface and interfacial phenomenon involving the activities of enzymes are wide spread in cellular systems and occur within the interfacial constraints of substrate accessibility, distribution and partitioning. Similar mechanisms can be used to enhance productivity of industrial biotransformations at oilwater interface. Detailed study and manipulation of interfacial enzyme catalysis is of great interest for biotechnology, chemical technology, biology, and offers new opportunities in protein and polymer chemistry, separation science, bio-renewable products, environmental science and waste minimization. Herein, novel self-assembling enzyme systems were developed by manipulation of microenvironment of the enzymes for interfacial biotransformations at oil-water interface. The enzyme molecules were modified to self-assemble at oil-water interface by conjugation with hydrophobic moieties like polymers. The present work focused on (i) characterization of enzyme assembly morphology, (ii) stabilizing the enzymes at the interface, (iii) broadening the scope of interfacial biocatalysis with multienzyme-cofactor system and developing method to assemble cofactors at the interface, (iv) investigating the kinetic parameters of the interfacial reaction, (v) improving the activity of interfacial iii enzyme by interfacial mobility enhancement and (vi) extending the hydrophobic manipulation of enzyme’s microenvironment for development of biosensors based on nanofibers containing organic soluble enzymes. Four sets of model reactions system, a single enzyme system and three multiple enzyme system was employed for interfacial biocatalysis study and oxidation of glucose by glucose oxidase was chosen as a model system for biosensor development. In a previous study, it was demonstrated that interface-assembled enzymes improved the reaction rate by two orders of magnitude. As a part of the present work, the important role of mobility and the assembly morphology of the interface-assembled enzyme on regulating the enzymatic liquid membrane fluidity at the interface were investigated. To characterize the surface assembly morphology of the interfaceassembled enzyme by surface pressure analysis, Langmuir film balance was used. The resulting surface pressure isotherm exhibited monolayer assembly, with intramolecular rearrangement of the interface-assembled enzymes. The mobility of the novel interfaceassembled enzymes was evaluated by using fluorescence recovery after photobleaching technique that gave the diffusion coefficient of 6.7×10-10 cm2/sec, three orders of magnitude less than that of native enzymes in aqueous solution, due to localization of the modified enzyme at the interface. Though modification of enzymes with polymer for interfacial assembly reduced its mobility, the conjugation of polymer to enzyme stabilized the enzymes against interfacial denaturation. The polymer stabilizes the three dimensional structure of enzymes and prevent it from unfolding at hydrophobic interfaces. Apart from the iv interfacial stabilization of interface-assembled enzyme by polymer, the localization of enzymes at the interface offered a unique opportunity to enhance the stability of the enzymes against the deactivation effect of compounds in bulk phase. Chloroperoxidase (CPO) was chosen as a model enzyme to explore the factors that determine the stability of interface-assembled enzymes. Although the interface-assembled CPO showed improved stability as compared to native CPO, enzyme deactivation by peroxide reactants like hydrogen peroxide (H2O2) in the bulk phase, still limited the overall productivity of the enzyme. Two approaches to further improve the stability of interfaceassembled CPO were examined in this work. In one approach, several chemical stabilizers were used to prevent highly reactive intermediates from oxidizing the porphyrin ring active site of CPO; polyethylene glycol (PEG) was found exceptional in that it increased both the operational and storage stability of CPO with a productivity increase of 57%, an operational stability improvement by almost 2 folds and a storage stability of 60% activity retention after 24 hours incubation in 1 mM H2O2. On the other hand, glucose enhanced the operational stability by 2 folds, but exhibited no significant effect on storage stability. While in a second approach, in situ generation of hydrogen peroxide (H2O2) by using glucose oxidase (GOx) to keep H2O2 concentration low was applied. It was found that the combined effect of presence of glucose and lowered concentration of H2O2, extended operational lifetime to 60 minutes for CPO with in situ generation of H2O2 by GOx. To expand the scope of interfacial enzyme catalysis, multienzyme oxidoreductases-cofactor systems were employed. The structure of cofactors involves unique combination of functional groups that are required by oxidoreductases enzymes to carry out biotransformations and any modification to cofactor for interfacial assembly should not affect the enzyme-cofactor interaction. The challenge of modifying cofactors to assemble at the interface was overcome by structural manipulation of the adenine group of nicotinamide cofactor. The synthesis of interface-assembled cofactor gave a process yield of 67%, the modified cofactor was highly stable with a continuous operation of 2150 hours and turnover number of 2617 for a biphasic reaction involving reduction of acetophenone in organic phase and oxidation of glucose in aqueous phase. The Damkohler number that gives the ratio between reaction rate and mass transfer rate was obtained to be 0.12 with interface assembled cofactor, compared to 87.5 with native enzymes and free cofactor, indicating mass transfer limitations with interface assembled cofactor. The kinetic analysis of interface-assembled cofactor gave the binding resistance of enzyme to cofactor at the interface, Kc, as 0.18 mM compared to 0.03 mM of native enzyme and free cofactor, which indicated that limited interfacial interaction between molecules and two-dimensional mobility of the enzymes contributed significant resistance towards interfacial reaction. A novel mechanism of nanostirring was developed to improve the twodimensional mobility of interface-assembled enzymes. Iron oxide (Fe3O4) superparamagnetic nanoparticles were coupled with polymer conjugated enzymes for interfacial assembling and applied to improve the mobility of the interface-assembled enzyme under external electromagnetic field. The enhanced mobility of the interfaceassembled enzymes was quantified through fluorescent microscopic visualization, and enabled over 600% of improvement in the observed reaction rate for both single enzyme and multienzyme systems as compared to reactions in the absence of the magnetic field. The combination of slow reactions and denaturation of dehydrogenase enzymes due to stirring posed a major constraint for realizing reactions with configuration of both cofactor and enzymes assembled at the interface. This limitation was overcome by development of a unique interfacial biotransformation with interface assembled cofactor and interface-assembled multiple enzymes was realized by employing relatively shear resistant dehydrogenase, ADH RS1, coupled with GluDH for faster NADH turnover. A maximum NADH turnover of 13 was achieved by optimizing the reaction conditions enzyme ratio, organic phase and aqueous phase substrates concentrations, and polymer modifier concentration added during modification of enzymes. In another effort, the manipulation of microenvironment of enzymes for enhanced hydrophobicity was extended to develop completely organic-soluble enzymes. The organic soluble enzymes were utilized in the development of polymer-enzyme composite nanofibers for biosensing applications. Polyurethane nanofibers of diameters of 100-140 nm containing up to 20% (w/w) protein were prepared via electrospinning. The enzyme, glucose oxidase (GOx), was complexed with an ionic surfactant and was thus transformed into organic soluble prior to electrospinning. When examined for biosensor applications, such prepared nanofibers showed a sensitivity of up to 66 A M-1 mgenzyme- 1 (or 0.39 A M-1 cm-2), 100 times improvement from previous studies. The high enzyme loading coupled with the high specific surface area of the nanofibers enhanced the reaction kinetics and thus enabled strong responses for small changes in glucose concentration. The confinement of the enzyme within the body of nanofibers also stabilized the enzyme, such that the biosensor retained 80% of its sensitivity after 70 days. The interface-assembled enzymes with their improved interfacial stability can substitute soluble enzymes that are presently used for many industrial applications with biphasic systems. Also, Interface-assembled enzymes offer simultaneous access to reactants in both the bulk phases across the interface and thus improve the overall efficiency for the biotransformations between immiscible chemicals. The novel polymerenzyme conjugates and functional materials that were developed through this research with their unique structural, magnetic and mechanical properties can be used in broad range of applications like sensors, membrane technology, generate alternative strategies for encapsulation and delivery of therapeutic agents, and will enable minimum downstream processing for specialty chemical synthesis. The present work is of great interest in the search for production of different important industrial chemicals including bio-renewable products and for sustainable environmental quality.

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