Natural Resources Science & Management, Graduate Studies Program
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The University of Minnesota graduate program in Natural Resources Science and Management is offered through the College of Food, Agricultural and Natural Resource Sciences (CFANS), in conjunction with the Graduate School.
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Item Self-assembling multienzyme systems at oil-water interface for biphasic biotransformations(2008-11) Narayanan, RavindrabharathiLiving 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.Item Spatial vegetation-environment relationships and distributional changes in the presettlement Minnesota prairie-forest boundary.(2009-02) Danz, Nicholas PThe 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.Item Quality connections: recreation , property ownership, place attachment, and conservation of Minnesota Lakes.(2009-05) Schroeder, Susan ArleneRecently, 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.Item Land use and terrestrial carbon storage in Western North Carolina from 1850-2030: a historical reconstruction and simulation study.(2009-07) Kirk, Ryan WilliamThe 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.Item Integrating social considerations into managing white-tailed deer in Minnesota.(2009-11) Cornicelli, Louis JamesIn 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.Item Intensified biocatalysis for production of fuel and chemicals from lipids.(2010-03) Zhao, XueyanTriglycerides 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.Item Soil moisture and soil frost regimes under annual, perennial and agroforestry Crops in Waseca, Minnesota.(2010-03) Byrne, Marin Johanna.The potential for agroforestry and other perennial crops to provide hydrologic benefits is of interest in the Minnesota River Basin, where the landscape is dominated by annual row crops and the river is plagued by water quality and quantity issues. Perennial herbaceous and woody crops are thought to have higher annual consumptive use of water than annual corn-soybean crops, influencing antecedent water status, creating more water storage, potentially decreasing discharge, and reducing the duration of soil frost and prevalence of concrete soil frost in the early spring. Quantification of potential hydrologic benefits is needed to provide support for more sustainable agroforestry and other alternative cropping practices in the basin. To this end, in the summers of 2004 and 2005, biweekly measurements of soil moisture under one annual crop (corn/soybean rotation), two perennial herbaceous crops (perennial flax and Illinois bundleflower) and two woody crops (hybrid hazelnuts and hybrid willow) were taken on replicated experimental plots at the University of Minnesota’s Southern Research and Outreach Center in Waseca, Minnesota. Similar measurements were taken in a stand of mature hybrid poplar and a field planted in a corn/soybean rotation. Likewise, soil frost depth, duration, and type were measured under the same crop types during the intervening winter. Analysis of soil moisture data showed few significant differences in soil moisture between the various crop types on the experimental plots, perhaps due to a combination of the perennial and agroforestry crops being in the establishment phase and unusually wet weather. The mature poplar stand had consistently drier soils than the cornfield during the 2004 season, although these differences disappeared during the course of the 2005 season, likely due to a change in management of understory plant cover in the poplar stand. During the winter, no significant differences in soil frost duration or type were observed, likely due to uniformly wet fall soil conditions, a lack of snow during the coldest part of the winter and rapid spring warm up. Thus, agroforestry and herbaceous perennial crops appear to provide little hydrologic benefit during the establishment phase or in winters with low snowfall, but when mature or in winters with heavier snowfall, could have the potential to provide such benefits.Item Post-stratified estimation of Coarse Woody debris Volume using the down woody materials sample of forest inventory and analysis.(2010-05) Hatfield, Mark A.The Forest Inventory and Analysis (FIA) program of the USDA Forest Service conducts a nation wide survey of America’s forests. FIA field crews collect data on tree size, condition, and species, as well as data on the conditions in which they grow from a network of permanent ground plots known as Phase two plots (P2). FIA crews also collect more detailed forest health indicators, including data on Coarse Woody Materials (CWD), on a 1 16 subset of the P2 sample. This subset is known as the Phase 3 (P3) sample. FIA regularly publishes reports on the quantity and quality of America’s forests using data from the P2 sample. A post-stratified estimation technique is used increase the precision of the estimates without increasing the sample size. Currently, research on how to best apply the post-stratified estimator to produce estimates of the P3 forest health indicators has been lacking. This thesis will address this gap by testing 18 candidate geospatial layers (both categorical and continuous) as stratification layers to produce estimates of CWD volume in the Lake-states region of Minnesota, Wisconsin, and Michigan. Continuous geospatial layers will be broken into two to five strata using an optimization algorithm. A simulation experiment is used estimate the long term effectiveness of successful geospatial layers. The simulation experiment is performed to compare the conditional and unconditional variance estimators of the post-stratified estimators. Successful geospatial layers are then applied to sub-populations of varying sizes to determine the effect of spatial extent on the post-stratification method. Stratification layers derived from remote sensing products provided the best results. Using two or three strata is recommended because further partition of the population simply produces ineffective sliver strata. No difference was detected between the two competing variance estimators. The effect of spatial extent of the stratification was volatile. The use of large spatial extents is recommended. The conclusion of this thesis summarizes the lessons learned throughout as well as ideas for future research on the topic.Item The role of predator removal and density-dependence on mallard production in northeastern North Dakota(2010-05) Amundson, Courtney LindaDensity-dependence is a central tenet of wildlife population dynamics and harvest management, yet the pathways and mechanisms by which density-dependence operates remain unclear. In 1994, Delta Waterfowl Foundation began trapping meso-predators in northeastern North Dakota to determine if it was a viable technique for increasing waterfowl production. Subsequent research on replicated experimental sites found that trapping predators increased nest success by about 2-fold, and nest success was the most important factor regulating population growth in previous studies of midcontinent mallards. Given the philopatric nature of most waterfowl species, higher nest success on trapped sites was predicted to lead to 36% greater annual population growth on trapped sites versus controls, which should have led to doubling of pair densities approximately every two years. This backdrop provided me with the unique opportunity to examine the role of density-dependence on waterfowl production at a local scale in North Dakota. My dissertation focuses on the role of density-dependence and predator removal on mallard duckling survival, duckling body condition, and overall mallard productivity in northeastern North Dakota from 2006-2007. Contrary to predictions, predator removal had no beneficial effect on mallard duckling survival. Duckling density was weakly negatively associated with mallard duckling survival, but had no effect on duckling condition. Duckling survival, not nest success, was the most important factor influencing population growth and production and appeared to be functioning as the key limiting factor in our populations. Overall, predator removal did not lead to local population increases on trapped sites and added far fewer incremental ducks to the fall flight than originally predicted. The perils of duck hunting are great - especially for the duck. - Walter Cronkite.Item 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, KaitlinThe 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.Item Effects of site and climate characteristics on forest invasibility by non-native plants in the Midwest.(2010-07) Kurtz, Cassandra MarieNon-native invasive plant (NNIP) species can have significant effects on forest regeneration, structure, biodiversity, and wildlife habitat, costing billions of dollars annually. Understanding how NNIPs in the Midwest may spread in the future requires understanding their response to site and climate characteristics. Current research suggests climate change may influence invasive plant presence and spread. In this study, I modeled the relationship between invasive species presence, site characteristics (e.g. disturbance, live tree volume, city distance, edge distance, physiography, and type of water [e.g. streams] present on plot), and climate (annual average number of days the temperature is ≥ 90˚F and annual average number of days the temperature is ≤ 32˚F) for five non-native invasive plants (multiflora rose [Rosa multiflora], common buckthorn [Rhamnus cathartica], non-native bush honeysuckles [Lonicera spp.], garlic mustard [Alliaria petiolata], and reed canary grass [Phalaris arundinacea]) sampled by the USDA Forest Service’s Forest Inventory and Analysis program in seven Midwestern states for 2005-2006 Species’ response to site and temperature predictors varied due to trait differences such as shade tolerance and moisture affinity. For most species, presence was positively related to biotic disturbance (disease(s) and/or animal(s)) and mesic physiography and negatively related to distance from a city or a nonforest edge. The best predictor for the presence of NNIPs was annual average number of days the temperature is ≤ 32˚F, with all five species presence correlated with the annual average number of days the temperature is ≤ 32˚F. Understanding the effect of site characteristics and climate on NNIP distribution provides insights into important drivers of species presence at a regional scale and allows land managers, scientists, and concerned citizens to predict invasion risk and future ecosystem response.Item Development of geospatial analysis tools for inventory and mapping of soils of the Chongwe Region of Zambia.(2010-07) Shepande, ChizumbaDesigning 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.Item Resource assessment and analysis of aspen-dominated ecosystems in the Lake States.(2010-08) Domke, Grant MichaelUtilization 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.Item The influence of stand stocking level on the growth and structure of managed old-growth northern hardwoods.(2010-09) Gronewold, Christopher AlanSummary abstract not available.Item American Woodcock Singing-ground Surveys in the western Great Lakes region: assessment of woodcock counts, forest cover types along survey routes, and landscape cover type composition.(2010-10) Nelson, Matthew RoyOverview: Counts of American woodcock (Scolopax minor) on the annual Singing-ground Survey (SGS) have undergone long-term declines in both the Eastern and Central Management Regions. However, interpreting these trends is confounded by a lack of information regarding the relationship between counts and habitat. Therefore, I assessed the relationship between woodcock counts and land-cover composition along survey routes using an Information-Theoretic modeling framework. The amount of early successional forest, open space, and a landscape metric Interspersion and Juxtaposition Index (IJI) best explained counts in Wisconsin; in Minnesota, the amount of mature forest, water and models that included open space, wetlands, and early successional forest together best explained counts. These results are, in general, consistent with woodcock-habitat relations described in published literature, and suggest that woodcock counts along SGS survey routes in Minnesota and Wisconsin reflect the amount and composition of land cover along routes, especially the amount and juxtaposition of early successional forest and open space, which were the variables included in competing models for both states. Key Words: shorebird, American Woodcock, Scolopax minor, Central Management Region, Minnesota, Wisconsin, land cover.Item 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.Item Riparian plant composition, abundance, and structure responses to different harvesting approaches in riparian management zones nine years after treatment in Northern Minnesota, U.S.A.(2010-11) Martin, Michelle AmberI compared riparian plant responses to different harvesting approaches over nine years in Riparian Management Zones (RMZ) in Northern Minnesota. In Chapter 1, I found that tree regeneration in RMZs is greater in partially harvested treatments (60% BA removal) than in unharvested treatments. This was especially true of intolerant tree species, although the shade tolerant species are becoming important in lower strata at year nine post-treatment. In Chapter 2, I found that understory plant community composition and abundance change somewhat over time in partially harvested treatments in comparison to unharvested treatments. This was especially true of woody understory layers, however, less so for the herbaceous layer. In general, the understory plant community shifted toward more shade intolerant and disturbance indicating species. As of nine years post-treatment, partially harvested RMZs balance timber and non-timber management objectives as they increase tree regeneration and do not dramatically alter understory plant communities.Item Renewable energy deployment in the electricity sector: three essays on policy design, scope, and outcomes(2010-11) Fischlein, Miriam LydiaDue 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.Item All cellulose composites prepared in an ionic liquid.(2010-12) Zhou, LiliThe overall goal of this project was to investigate all-cellulose composites prepared in a “green” solvent – ionic liquid. The approach was to partially dissolve cellulose and subsequently convert it into a matrix domain embedding the reinforcement domain – the undissolved cellulose. Microcrystalline cellulose (MCC) was partially dissolved in 1-N-Butyl-3-methylimidazolium chloride (BMIMCl) ionic liquid. The dissolved portion of cellulose was precipitated by adding water, and the gels obtained were washed, dried, and pressed into films. The all-cellulose composite films were structurally characterized using x-ray diffraction (XRD) and scanning electron microscopy (SEM), while their properties were determined using tensile tests and dynamic vapor sorption (DVS) studies. XRD results verified that the crystallinity index and weight fraction of cellulose I in the composites can be controlled by controlling the soaking time and cellulose concentrations. The tensile test data revealed that the all-cellulose composite produced in this study had mean elastic moduli and strength of up to 4.4 GPa and 49 MPa, respectively, which are in the range of a randomly oriented biofiber-reinforced polymer composites. The tensile properties increased as a response to the composite density, which was found to increase as more cellulose II matrix (from increased dissolution) was present to presumably better fill the voids. This presumption was supported by SEM images of cryo-fractured surfaces. The sorption isotherms obtained from DVS studies showed a non-sigmoidal behavior at low relative humidity levels (<44%), while the equilibrium moisture content values at higher humidity levels closely correlated to the cellulose I crystallinity index of the composites. Overall, this study verified that dissolution of cellulose in ionic liquid can be controlled to control the properties of all-cellulose composites.Item The influence of natural disturbance-based silviculture treatments on northern hardwood forests in Northeastern Minnesota, USA.(2010-12) Bolton, Nicholas WilliamNatural disturbance-based silviculture (NDBS) has been suggested as an approach for promoting late-successional forest characteristics and maintaining native biodiversity in managed forests. Harvest gaps based on the natural disturbance patterns found in the upper Great Lakes (46 study gaps) were created throughout northern hardwood forests in northeastern Minnesota, USA, during the winters of 2002 and 2003. Gaps were measured 6- and 7-years post-treatment and subsequent analysis of these measurements was used to evaluate the success of these treatments at meeting structural and compositional objectives. Results indicated that these gaps have done little to increase tree diversity, including the recruitment of shade mid-tolerant species; however, the richness of herbaceous understory vegetation has responded positively to larger gap sizes. Herbaceous species increasing in harvest gaps included Actaea spp. L. (baneberry), Botrychium virginianum L. (rattlesnake fern), Mertensia paniculata Aiton (Northern bluebell), Rubus idaeus L. (red raspberry), Sanguinaria canadensis L. (bloodroot) and Cirsium arvense L. (Canada thistle). Results also indicated that subtle patterns were found among species spatial establishment within gaps (e.g., gap edge and gap center) and species that expressed no preference between the intact forest and harvest gaps. Levels of downed coarse woody debris (CWD) differed among gap size and all gaps had lower levels of CWD compared to the surrounding intact forest. Due to the historical importance of Betula alleghaniensis in these systems, the factors affecting the recruitment of this species were also investigated. Based on these investigations, it was found that B. alleghaniensis establishment was strongly related to highly decayed, large coniferous pieces of CWD with little recruitment occurring on the undisturbed forest floor. As such, providing appropriate seedbed conditions for shade mid-tolerant species and utilizing natural canopy gap sizes would improve the success of maintaining this species on the landscape.
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