Browsing by Subject "Natural resources science and management"

Now showing 1 - 20 of 21

Assessment of techniques to evaluate American woodcock population response to best management practices applied at the demonstration-area scale
(2014-09) Daly, Kyle O'keefe
American woodcock (Scolopax minot; hereafter, woodcock) have experienced long-term population declines across their breeding range based on the American woodcock Singing-ground Survey. Wing-collection surveys have also indicated a decline in woodcock recruitment across their range, especially in the Central Management Region. These declines have been widely attributed to loss or alteration of young forest cover types that support woodcock reproduction across their breeding range. In response to these apparent declines in woodcock abundance and recruitment, a system of woodcock habitat demonstration areas is being developed throughout the woodcock breeding range where specific Best Management Practices (BMPs) are applied with the goal to stabilize and ultimately increase populations. Application of BMPs at a demonstration-area scale (~200-800 ha) is designed to positively influence woodcock population growth by improving habitat quality and abundance at a landscape scale. However, how woodcock vital rates are influenced by BMPs applied at a landscape scale is not fully understood, and techniques used to evaluate woodcock populations at the demonstration-area scale have not been assessed. The objectives of our research were to (1) estimate survival of adult females, nests, and juveniles using radio telemetry and assess relationships between survival and vegetation structure resulting from BMPs, life history traits, and weather, (2) directly estimate a measure of woodcock recruitment (juveniles/adult female during late summer) at a landscape scale by using survival estimates in a population model, and use direct estimates of recruitment to evaluate the accuracy and usefulness of indirect estimates of recruitment based on less costly and effort-intensive methods (specifically mist netting and night lighting on summer roosting fields), and (3) test for effects of radio transmitters on juvenile woodcock survival. In 2011 and 2012, we radio-marked and tracked 41 adult female and 73 juvenile woodcock, and monitored 51 broods and 48 nests. Breeding season cumulative survival for adult females was consistent between years, whereas nest and juvenile survival were related to year. Juvenile survival was also positively related to age, minimum temperature, and stem density, and negatively related to precipitation. We found no effects of radio-marking juvenile woodcock. In July of 2011 and 2012, we captured 204 woodcock using mist nets during crepuscular movements from diurnal feeding cover to roosting fields and 69 woodcock via night-lighting on roosting fields. Our recruitment estimates (juveniles/adult female) derived from our demographic model were higher in 2012 than 2011 due to higher nest and juvenile survival rates during that year, suggesting that nest and juvenile survival, and factors related to nest and juvenile survival, may be key to understanding woodcock population ecology. Our assessment of indirect methods to estimate woodcock recruitment at a landscape scale indicated that the indirect methods we considered of estimating woodcock recruitment at a landscape scale are likely not reliable proxies for estimating recruitment directly.
Building urban and community forestry capacity through manipulative social and physical infrastructure changes
(2014-10) Dierich, Andrea
Funding and staffing for urban and community forestry (U&CF) has decreased significantly over the last decade. This strain has hampered programs and affects the health of the urban forest. As our globalized market increases, invasive species become a growing threat that U&CF programs struggle with in their debilitating state. The invasive species, emerald ash borer, has the ability to cause catastrophic harm to Minnesota communities due to the high percentage of ash on public owned property. In an effort to provide assistance, and build capacity for dealing with emerald ash borer, the Emerald Ash Borer: Rapid Response project was developed. This project utilized volunteers and community gravel beds to build U&CF infrastructure to increase the ability of a community to manage not just emerald ash borer, but develop a successful and sustaining U&CF program. The intensive and direct assistance method used in the project provides new ways for states and other organizations to consider building and tracking U&CF capacity in communities.
Contesting risk: science, governance and the future of plant genetic engineering
(2014-10) Kokotovich, Adam Eli
As a process to synthesize science and characterize potential ecological risks to inform decision making, ecological risk assessment (ERA) influences how the potential for harm is studied and is foundational to national and international decision making on genetically modified organisms and other technologies. Existing literature has argued that ERA is built on values-based judgments that should be subject to critical scrutiny, and that conflicts about risk are influenced by competing understandings of what constitutes ecological harm, beneficial technology, desirable scientific research. However, there has been a lack of empirical work that explores the implications of these insights. As a contribution to this work, I use interviews, document analysis and participant observation to explore three case studies involving plant genetic engineering and the contestation of risk. The first case study examines the differences between two competing ERA guidelines for assessing the impacts of genetically modified plants on non-target organisms. Findings include that the guidelines proposed consequentially different processes for the study of potential risks as a result of divergent judgments about hazard identification, substantial equivalence, species selection, and indirect effects. The second case study explores how expert stakeholders envision future environmental regulation for plants produced by novel, targeted genetic modification techniques. Their views varied based on different underlying assumptions associated with what constitutes environmental risk and the adequacy of existing regulations. For the third case study, I participated in and studied a collaborative committee that, in response to issues concerning wild rice and the potential for its genetic engineering, is engaged in an anticipatory process to influence scientific research policy at the University of Minnesota. I found that the committee pursued the inclusion of Native American worldviews into wild rice scientific research by using a conceptual framework of "bridging worldviews" that made explicit how wild rice research is based upon contestable assumptions about risk, science, and the desired state of the environment. Across three diverse case studies, this research demonstrates the importance of interrogating the values-based judgments and assumptions that underlie ERA and decision making processes for genetically modified plants and environmental issues more broadly.
Development of high biomass content hot-melt pressure-sensitive adhesives
(2014-08) Gu, Cheng
A new approach was introduced for incorporating renewable biomass into existing commercial pressure-sensitive adhesive (PSA) polymers in the form of acrylated macromonomers (MM). MM were prepared with L-lactide and caprolactone via a bulk ring-opening polymerization initiated by N-hydroxyethyl acrylamide (HEAA). Acrylic adhesive copolymers were synthesized by free-radical solution polymerization in presence of 2-ethylhexyl acrylate (EHA), acrylamide and macromonomers. This approach was achieved without sacrificing adhesive performance. Incorporation of the MM into the polymers was confirmed via proton NMR. Properties and adhesive performance of the new polymer were compared with its 100% acrylic commercial version. When synthesized using the same approach, the biomass-containing PSA had a lower molecular weight, higher glass transition temperature (Tg) and lower melt viscosity. Introduction of MM had little impact of tack force, shear time and shear adhesion failure temperature and peel strength increased substantially. Influence of HEAA capped L-lactide/caprolactone MM composition on acrylic hot-melts was also reviewed. A series of MMs, synthesized using catalyzed ring-opening polymerizations, were produced containing a broad range of lactic acid and caprolactone repeat units. Results indicate that the properties and performance of adhesive polymers are strongly dependent on lactide composition. In general, increasing lactide content increases polymer hardness enhancing cohesive strength, while reducing it (i.e., increasing caprolactone content) softens the polymer. Optimal adhesion is found to require a balance between these tendencies as indicated by the existence of a clear maximum in both tack and peel data. The results demonstrate that a broad range of properties is achievable through relatively minor modifications to MM composition. It is expected that these hybrid materials can be optimized for a variety of self-adhesive applications.
Distribution, migration chronology, and survival rates of Eastern Population sandhill cranes
(2014-11) Fronczak, David Leonard
The Eastern Population (EP) of greater sandhill cranes (Grus canadensis tabida; hereafter, cranes) is rapidly expanding in size and geographic range. The core of their breeding range is in Wisconsin, Michigan, and southern Ontario, Canada. Little information exists regarding the geographic extent of breeding, migration, and wintering ranges of EP cranes, or migration chronology and use of staging areas. In addition, there are no published estimates of survival rates for EP sandhill cranes. To address these information needs we trapped and deployed solar Global Positioning System (GPS) Platform Transmitting Terminals (PTTs) on 29 sandhill cranes from December 2009 through September 2011, primarily in known fall and winter concentration areas, to assess movements throughout the year. This thesis explores EP sandhill crane distribution during the breeding season and winter, migratory routes, and migration chronology (Chapter 1) and also estimates survival rates during the study period (Chapter 2). EP cranes settled on summer areas beginning mid-March in Minnesota (11%), Wisconsin (36%), Michigan (29%), and Ontario (21%). On average, PTT-tagged cranes arrived at their winter terminus beginning mid-December in Indiana (29%), Kentucky (11%), Tennessee (79%), Georgia (11%), and Florida (32%). Twenty-three marked cranes returned to their summer area's calculated mean center after a second spring migration. The average linear distance between individual estimated mean activity centers for a summer area was 1.34 km (range: 0.01 - 7.82 km). EP cranes used fall and spring migration routes similar to those previously documented. Annual survival rates (from October through September) were estimated at 0.921 (2010-2011; SE = 0.058) and 0.913 (2011-2012; SE = 0.087) using the known fates platform in Program MARK (Chapter 2).
An exploration of conservation decision making by farmers of the Red River Basin, Minnesota: the role of values, identity, and perceived behavioral control
(2014-12) Perry, Vanessa Marie
This study explores the relationship between values, identity, and perceived behavioral control and their influence on agricultural conservation decision making. Twenty-four qualitative interviews were conducted with farmers and agricultural landowners in two Minnesota sub-watersheds of the Red River Basin. Study findings reveal participants hold values and identities consistent with natural resource conservation. However, they also perceive an inability to act in accordance with their values and identities. This research builds on other farmer behavior studies by investigating perceived control as a moderator of conservation behavior. A better understanding of farmer decision making will enable land managers, resource professionals, and policy makers to enhance conservation initiatives and interventions by addressing constraints to conservation action. Programs and policies more closely aligned with farmer values and identities and providing a greater sense of control will be better received by farmers and agricultural producers.
Exploring hydraulic residence in Minnesota's Sentinel Lakes: implications for management
(2014-08) Engel, Lee Charles
Lake systems present a challenge in determining how water associated solutes cycle with time. Lake hydraulic residence time is an important lake management variable dependent on several factors including: volume, watershed size, location within a watershed and climatic variability. The stable isotopes of hydrogen (Deuterium expressed as δD) and oxygen (δ18O) can provide some hydrologic insight to lake water quality management. Analyzing the stable isotopic composition of lake water δD and δ18O over time can aid in identifying source water input mixing and evaporative processes. Lake water δD and δ18O were compared to the isotopic composition of atmospheric water vapor which has a known isotopic concentration at specific latitudes and air temperatures (Burns and McDonnell, 1998; Dansgaard, 1964). Study lakes were sampled spring, summer, and fall over a three year period. Deviations in the amplitudes of fractionated lake water compared to water vapor was modeled to predict hydraulic residence time for twenty-four lakes throughout Minnesota. Results suggest hydraulic residence time was dynamic; variations occurred with annual source water contributions, watershed size and connectivity. Ranges of annual hydraulic residence time among individual lakes were as great as 18.8 years and as small as 0.4 years. δD and δ18O values were plotted in relation to the Meteoric Water Line (MWL) for all study lakes. A gradient of δD and δ18O values were found in relation to latitude. Lighter values ofδD and δ18O were found in northern Minnesota compared to southern Minnesota. Variations in seasonal δD and δ18O created annual amplitudes that provide insight into lake water budgets and residence times. The use of δD and δ18O offer water quality managers a tool to better understand, protect, and remediate lakes and their watersheds.
Exploring N and P reduction in bioreactors
(2015-02) Zhang, Lu
The main goal of this study was to provide information on the nitrate and phosphorus removal efficiencies of woodchip, biochar, and corn cobs. Woodchip bioreactors have proven effective in removing nitrate-nitrogen (NO3-N) from agriculturally drained water in the Midwest USA region. Both nitrate and phosphorus can lead to hypoxia and algal blooms in the receiving surface waters and degrade the water quality. This study explored the effectiveness of bioreactor technology in removing NO3-N and orthophosphate, and the emission of N2O from different media. Three types of media were examined in a pilot-scale lab experiment: deciduous mixed hardwood chips, biochar chips (created from the same type of woodchip), and corn cobs. Chemically formulated water was fed through each system using a residence time of 24 hours, and later on, 8 hours. NO3-N reduction occurred in all three media, although biochar showed a relatively longer lag time. An average of 9.26g N/d/m3 NO3-N total loading reduction was observed from the 24 hours retention time when the total input was 588.82g. An average of 0.35g orthophosphate/d/m3 of the orthophosphate loading was reduced while the input phosphorus was 6.10g, with the biochar media providing the most reduction in outflow orthophosphate concentration. A lower reduction rate and higher nitrate output was observed from the 8 hours retention time. However, corn cobs showed the highest total nitrate removal rate of 22.40g N/d/m3 while the total input was 1156.70g. The orthophosphate reduction rates were not significantly different among the three media (ranging from 0.67g orthophosphate/d/m3 to 0.86g orthophosphate/d/m3) with a total input of 11.10g. Given the recent development of state-wide nutrient management plans to reduce nutrient concentrations in surface water, study results of these technologies will help the row-crop producer community manage nutrient export to surface water.
The foundations of community capacity: an exploration of the role of fairness, trust and legitimacy in sustainable watershed management
(2014-11) Sames, Amanda
Water resource managers and policymakers are increasingly turning to a watershed approach using hydrologic rather than political boundaries to address water resource problems. However, transboundary, interjurisdictional water resource management can be especially challenging for local government officials and citizens. This thesis examines community capacity for sustainable watershed management within two southeastern Minnesota mixed land use and multi-jurisdictional watersheds. Specific objectives were to describe and compare conditions and capacities that promote or constrain sustainable watershed management from the perspective of water resource professionals, government officials and active community members. Data were gathered though 49 key informant interviews conducted with resource professionals, community decision makers and active residents in 2011and 2012 and analyzed using grounded theory and comparative analysis. Findings indicate the importance of fairness, trust and legitimacy in relation to community capacity for sustainable watershed management. The emergence of fairness, trust and legitimacy in this study indicate a new aspect of community capacity: foundational conditions. As foundational conditions, they allow previously identified actionable capacities to be leveraged in response to community needs, in this case, sustainable watershed management. Implications for resource managers are discussed.
Growth and stand dynamics of Red maple-dominated forests in the Upper Great Lakes Region, USA
(2015-02) Pszwaro, Justin Luke
Red maple (Acer rubrum L.) was historically a common but not abundant tree species in North American temperate forests. Over the last several decades it has increased in abundance on upland sites throughout its range and today is perhaps the single most abundant tree species in eastern North America. Climate change and associated impacts on forest dynamics are expected to increase red maple relative importance in the Upper Lake States and New England. However, red maple lacks commercial importance and has thus received little attention in growth studies and little is known of the dynamics of red maple-dominated stands. The objectives of this thesis were to 1) quantify the effects of stocking level and stand age on overall patterns of red maple stand productivity, 2) evaluate how these relationships vary across different geographic locations and climatic conditions, and 3) describe the composition dynamics of pure red maple-dominated forest stands.
Landscape productivity and the ecology of brood division in Golden-winged Warblers in the Western Great Lakes Region
(2014-08) Peterson, Sean Michael
Using radio-telemetry of fledgling Golden-winged Warblers (Vermivora chrysoptera) in the western Great Lakes region from 2010-2012, I investigated the poorly understood behavior of brood division. Brood division occured when both males and females care for a brood after fledging. I observed female-reared subbroods traveling over twice as far from the natal patch and nest sites as male-reared subbroods. The difference in space use we observed was correlated with female-reared subbroods preferentially moving in similar directions for a three-day period in which male-reared subbroods maintained an area of use. Because parental strategies differ between sexes with regard to movement patterns, I suggest incorporating the differences in space use between sexes in future management plans for Golden-winged Warblers and other species that employ brood division. Specifically, management actions might be most effective when they are applied at spatial scales large enough to incorporate the habitat requirements of both sexes throughout the entire reproductive season. Additionally, I developed a method for estimating productivity of a breeding season based on landscape around any given point. I used logistic exposure models to identify the influence of landscape structure and composition on nest productivity and fledgling survival. I used those models to predict spatially-explicit, full-season productivity across my study sites to identify areas of low relative productivity that could be targeted for management. I then used my models of spatially-explicit, full-season productivity to simulate the impact of potential management actions on my study sites with the goal of increasing total population productivity. I concluded that spatially-explicit, full-season productivity models that incorporate data from both the nesting and post-fledging periods are useful for informing breeding habitat management plans for Golden-Winged Warblers and that similar models can benefit management planning for many other species of conservation concern.
Measuring warfare in wood: linking competition among wood-degrading fungi of northern forests to its ecological consequences
(2014-08) Song, Zewei
Competition between distinctive groups of fungi determines the pattern of wood decomposition in forests, but the outcome of these battles may shift in a changing climate. With more than 70% of Earth's biotic carbon stored in woody tissues, understanding the processes that unlock this carbon and release the greenhouse gas CO₂ is critical. For my thesis research, I am addressing several key questions about how fungi colonize and dominate wood on the forest floor. Quantitative PCR was developed to measure biomass of specific fungi from a community in Chapter one. This technique was coupled with ergosterol, dilute alkali solubility, pH and carbon component analysis to measure biotic and abiotic dynamic during wood decomposition. With these comprehensive tools, factors that may influence fungal competition and decomposition outcomes were studied in the following chapters. In Chapter two, wood type was shown not to influence the competition between a brown rot fungus and a white rot fungus. It is contrary to the observations on wood preferences in nature, but reflected different foraging strategies by fungi. This led to the study of Chapter three on priority effect. By increasing the inoculum potential either inside or outside wood substrate, I have shown evidence that a weak competitor fungus can outcompete its more aggressive opponents, thus achieving co-existence. Another two factors, temperature and endophytes, along with priority effect were studied in Chapter four. Endophytes showed a much larger effect in influencing wood decomposition than temperature, mostly through antagonisms against soil fungi. Studies on these factors reveals potential for a more comprehensive model for wood decomposition. Emphasis on the role of microbial components, especially the often neglected endophytic communities, is possible to explain the variability in wood decomposition that can not be explained by abiotic factors, alone.
The nexus of nongovernmental organization water projects, monitoring and evaluation, and Kenya's Water Law
(2014-08) Were, Valerie Leah Achieng
The goal of this research was to explore monitoring and evaluation (M&E) practices among non-governmental organizations (NGOs) in the Kenyan portion of the Lake Victoria Basin. The influence that NGOs have in international development, tales of development projects gone awry, and historically poor performance assessment practices among NGOs all raise questions about how NGO administrators assess their projects and understand the social impacts of their work. Monitoring and evaluation is one option for demonstrating project impacts and minimizing negative unintended consequences. Kenya is a particularly appropriate focal place to study NGOs because the country hosts many organizations.This research used a case study of three NGOs, to address three questions regarding development project M&E: (1) How do the NGOs monitor and evaluate their projects? (2) Which methods and approaches do NGOs use to engage the community in project M&E? and, (3) How do customary laws and gender roles in the community influence NGO projects? The study found that M&E approaches varied and that budgets and funder preferences appeared particularly influential in NGO's choices about their M&E activities. Results of the study also suggested that the NGOs favored projects where people from the community were actively involved. However, the degree to which M&E activities involved the local community appeared limited. Finally, results suggested that customary laws and traditional gender roles are still important considerations for NGOs as they implement projects.Also described in this research is the new role that NGOs can play in water management in Kenya. In 2002, the country undertook sweeping reforms to water management and moved to a more decentralized model. Water management in Kenya became even more complicated after the February 2013 general elections when a decentralized administrative governance structure also took effect. Despite all the transition in water law and administrative governance structures, Kenyans still need access to clean and safe water. NGOs can help by guiding citizens through the process of forming grassroots organizations known as water resources user associations that support water management and service delivery. The three NGOs from the case study provided examples of how NGOs could become involved.
Productivity, recovery, diversity, and function of aspen-dominated forests vary in response to biomass harvest severity
(2014-08) Curzon, Miranda Thomas
Given uncertainty surrounding future climate and disturbance regimes, balancing objectives that include continuing to provide current forest products, meeting future resource demands, and maintaining ecosystem services presents a formidable challenge to forest managers. This research explored the short- and medium-term impacts of removing harvest residues for bioenergy feedstocks on aspen-dominated forests of the Lake States region. On sandy soils the removal of residues reduced standing biomass compared with stem-only harvest (SOH) 15 years after treatment, but no negative effect on aboveground biomass was observed following whole-tree harvest (WTH) on clayey or silty loam soils. Maximum diameter and the density of stems (> 5 cm diameter at breast height) declined on silty loam and sandy soils in response to increased severity in compaction and organic matter removal, respectively, indicating that structural development may be slowed. Although three species diversity measures and four functional diversity measures were used to assess community response to harvest disturbance, only indicator species analysis detected a functionally-relevant shift in community composition and structure that followed the most severe treatment combination on silty loam. This result highlighted the importance of employing multiple measures of diversity and composition to assess harvest impacts. Observations 2 years following bioenergy harvest with retention of aggregated overstory reserve trees indicate that both residue removal and overstory retention influence understory community composition. However, species diversity measures differed only between controls and disturbed areas (aggregates, SOH, WTH). Herbaceous plants considered interior forest obligates, such as Trientalis borealis, occurred in the aggregate understory, suggesting potential for small aggregates (0.1 ha) to serve as refugia for some species, at least in the short-term. Aspen sucker densities 0-5 m from the aggregate in the adjacent harvested areas were indistinguishable from densities 20 m from the aggregate edge, indicating ecological objectives might be achieved through aggregate retention without a trade-off in initial regeneration densities. Overall, results indicate that responses to the level of disturbance associated with harvest residue removal differ among sites, even when dominated by the same overstory species, but there is potential for severe disturbance to reduce standing biomass, shift community composition, and alter function and structure.
The relationship between water availability and forest dynamics in Northern Minnesota
(2014-12) Dymond, Salli Fae
Forested ecosystems play a major role in global and local water budgets, returning approximately 40% of total annual precipitation back to the atmosphere in the form of evapotranspiration. In the contiguous U.S., forested watersheds generate about 50% of runoff and management decisions include both afforestation and deforestation to create desired water yields. Since climate change is expected to increase watershed exports (in the form of increased evapotranspiration), understanding the intricate role of forested watersheds in the utilization, storage, and supply of water is necessary. For instance, some northern forest species exploit deeper water, but few studies have focused on niche diversification and differential exploitation of soil water in northern forests, in which root activity, depth, and lateral extent vary among species to partition soil moisture. Given that many northern forest landscapes experience a summer moisture deficit, particularly near the western biome boundary, this niche diversification may be key in sustaining some species and may affect overall forest water use and productivity. This dissertation sought to utilize a unique, 45-year in situ network of soil moisture measurements from the Marcell Experimental Forest (MEF) in northern Minnesota in order to investigate the relationship between plant available water and tree growth in the northern forests.
Relationships among behavior, habitat, and population density in a cyclic population of ruffed grouse
(2014-10) Berkeley, Lorelle Ivana
Understanding how patterns of habitat use by animals vary in relation to population density is of major interest to ecologists and wildlife managers. For decades, biologists have linked high populations of ruffed grouse (Bonasa umbellus) with aspen (Populus spp.) forests in the northern part of their range. However, male ruffed grouse in northern populations also select territories in conifer forests, even when apparently suitable aspen forests nearby remain vacant. This selection of cover types that are presumed to be of lower quality presents a conundrum to biologists: why would males select inferior cover types when better cover types are available? To address this conundrum, I investigated the behavior, habitat, and population dynamics of a population of male ruffed grouse to evaluate relationships among these factors and elucidate mechanisms of their cover type selections. Little is known about the mechanisms underlying habitat selection in most species. Studying the behavior of individuals within a population is one technique used to evaluate these mechanisms. Ruffed grouse are an ideal species in which to study behavior, habitat, and population dynamics because the males are easily counted, they are territorial, their territories are relatively easy to locate, and many populations are cyclic. I conducted my study at the Cloquet Forestry Center in northern Minnesota and used data collected over the course of one complete 10-year ruffed grouse population cycle (2002-2011) during which time the population reached both a high and low point in the numbers of territorial males counted each year. The grouse population was declining when the study begin in 2002 and did not begin its cyclic increase until 2006. I used repeated auditory surveys to locate the territories of drumming males and estimate the population density of territorial male grouse. I assessed behavior questions by using automated video systems to record the activities of a stratified (by aspen and conifer cover types) random sample of 23 male ruffed grouse from all of the males detected on my surveys. The number of breeding males on my 1,419-ha study area varied from a low of 47 in 2005 to a high of 134 in 2010. I assumed that rates of male ruffed grouse display were indicative of their interactions with conspecifics. I developed a priori models that described the relationships among male display rates and environmental attributes, structured these models as generalized linear models, and used information theoretic model selection to evaluate these models. The null model (i.e., intercept only model) was the top-ranked model (received the lowest AIC_c score). I used generalized linear models with random effects and information theoretic model selection to evaluate a priori models that described relationships among male ruffed grouse densities per cover type and environmental variables associated with their territory locations. Aspen-dominated cover types contained the highest densities of male ruffed grouse during all years (0.09 to 0.24 males/ha during 2002-11) except 2006 and 2011, when density was highest in northern hardwoods-dominated cover types (0.12 and 0.13 males/ha in 2006 and 2011, respectively) followed by aspen-dominated cover types (0.10 and 0.12 males/ha in 2006 and 2011, respectively). The density of males in conifer-dominated cover types was always less than the density of males in aspen-dominated cover types (0.02 to 0.08 males/ha during 2002-11). In addition to consistently higher densities of males in aspen- versus conifer-dominated cover types, densities of males in aspen-dominated cover types exhibited a higher intrinsic rate of increase than in conifer-dominated cover types during all years. However, the consistent occupancy of conifer-dominated cover types by males throughout the study also suggested that males perceived conifer-dominated cover types as suitable sites for territories and display behavior. At the cover type scale, the top-ranked model related to male grouse population density included an interaction of cover type and year variables. The mean density of male ruffed grouse within landscapes during all years ranged from 0.04 to 0.10 males/ha with minimum and maximum densities of 0 and 0.16 males/ha, respectively, during the entire study. At this landscape scale, an interaction of the estimate of the relative evenness of cover types (Shannon's Evenness Index) within landscapes and year comprised the top-ranked model explaining male ruffed grouse densities. Based on my study, if there is a difference in quality of conifer and aspen cover types, it manifests itself either in the specific stand structure used for male breeding displays or some life stage or seasonal habitat need of the ruffed grouse other than male breeding display cover. My results show that grouse populations achieve their highest densities in heterogeneous landscapes when aspen-dominated cover types, composed of multiple age classes, are the key cover types on landscapes. Landscapes that are less heterogeneous and where the majority of cover types are not dominated by aspen also harbor grouse, but at lower densities than heterogeneous aspen-dominated landscapes. Traditionally, managers have focused on the distribution and abundance of aspen-dominated cover types to enhance ruffed grouse habitat. However, my findings suggest that managers should focus on managing the spatial complexity of cover types on landscapes, even when aspen-dominated stands are in low abundance.
Role of leafing phenology in the invasion of forest ecosystems by Rhamnus cathartica
(2015-04) Pretorius, Andrew
Buckthorn breaks bud earlier in the spring and holds leaves later in the fall compared to co-occurring native understory species and the forest canopy. This phenology may allow buckthorn to take advantage of high light levels prior to canopy closure in spring and after leaf drop in fall. We hypothesized that this unique phenology is one mechanism that facilitates invasion of the forest interior by buckthorn. To test our hypothesis, we experimentally shaded buckthorn seedlings, reducing high light levels in the spring and fall to simulate intact canopy conditions. We measured spring and fall leafing phenology, light availability and seedling survival and growth. After a year and half of shading little mortality was observed but individuals receiving shading treatments had significantly decreased growth. Supporting our hypothesis that access to phenology-induced high light levels in the spring and autumn is one mechanism for buckthorn success in closed canopy forests.
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.
Structure, dynamics, and climate sensitivity of range-margin jack pine forests in central Minnesota
(2014-12) Gill, Kyle Gregory
Species' ranges are expected to shift in response to changes in climate and disturbance regimes. Individuals and populations along the edge of their range are expected to be most affected because of their proximity to climatically limiting factors and the unique dynamics relative to non-marginal portions of their range. However, limited empirical knowledge exists concerning the historic range of ecological variability in range-margin populations and systems.Jack pine (Pinus banksiana) reaches its southwestern range limit in central Minnesota where it displays traits, including low-levels of cone serotiny, that differ from other portions of its range. However, the stand dynamics (establishment, age structures, and disturbance regimes) and linkages with climate have never been documented for these populations. Our aim was to quantify the natural range of variability of stand dynamics and climate relationships to establish reference conditions for monitoring future climate impacts, informing refinement of forest ecosystem models, and assisting in the development of management decisions for conservation.Our results indicate that jack pine stands in this region are structurally complex even and un-even aged systems that follow a variety of developmental pathways. These patterns are attributed to the non-serotinous cones of jack pine in this region, which allow for both episodic and extended recruitment patterns over time. Annual growth and recruitment were both significantly sensitive to moisture and temperature variables, especially during the winter-to-spring transition, yet the directionality of associations displayed much seasonal variation. Our results suggest that management and modeling practices should be broadened to account for the variety of structural conditions and developmental pathways that historically characterized these range-margin jack pine forests. Such changes will help to conserve jack pine forests for the short-term while promoting the propensity for long-term resilience and adaptability.
A study of herbaceous vegetation in Chequamegon - Nicolet National Forest: relationship of earthworms, white-tailed deer browsing and Carex pensylvanica Lam
(2014-12) Ojanen, Paul Thomas
Invasive earthworms alter multiple forest components. By accelerating litter decomposition, they alter nutrient flows, soil composition and vegetative communities. White -tailed Deer (Odocoileus virginianus) are known to alter vegetative communities by selective browsing; severity varies with population density and affects plant community population and composition. Both factors are associated with reduced vegetative community richness and dominance by graminoids. In this study, 101 randomly selected Northern Mesic Hardwood Sugar Maple sites in the Chequamegon - Nicolet National Forest were sampled for vegetation, earthworm occurrence and browsing intensity. Over three years, eighty-two percent of sites were positive for earthworms; in two non-drought years, ninety percent of sites were positive. Non-metric Multi-dimensional Scaling (NMDS) and Multiple Response Permutation Procedure (MRPP) found divergent communities; a Carex pensylvanica Lam dominated community associated with earthworm invasion and strongly linked to Lumbricus rubellus presence, and remaining Acer saccharum seedling stands associated with reduced earthworm impacts. Additionally Carex pensylvanica was strongly linked to Lumbricus rubellus presence by Indicator Species Analysis. Lumbricus rubellus invaded sites had both reduced species richness and vegetative cover. White-tailed deer (Odocoileus virginianus) browsing was found to be heavy and extensive throughout both forests, impacting Acer saccharum regeneration and further driving graminoid dominance. The results indicate earthworm invasion is geographically extensive and a principal driver of Carex pensylvanica understory dominance and reduced Acer saccharum regeneration.

University Digital Conservancy

Browse by Subject

Browsing by Subject "Natural resources science and management"