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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
161

Long-term forest carbon storage and structural development as influenced by land-use history and reforestation approach

Urbano, Andrea Rose 01 January 2016 (has links)
Temperate forests are an important carbon sink, yet there is uncertainty regarding land-use history effects on biomass accumulation and carbon storage potential in secondary forests. Understanding long-term biomass dynamics is important for managing forests as carbon sinks and for co-benefits such as watershed protection and biodiversity. However there are many unanswered questions regarding these dynamics in northeastern U.S. forests: How have secondary forests of the U.S. Northeast recovered post nineteenth century agricultural abandonment? How has the region's extensive land-use history influenced long-term structural development and aboveground carbon storage? To answer these questions, we employed a longitudinal study based on twelve years of empirical data (2001-2013) from the Marsh-Billings-Rockefeller (MBR) National Historical Park in Woodstock, VT. MBR Park was the first parcel of land to actively be reforested in the eastern U.S., and as such, its diverse forest mosaic reflects a history of alternate reforestation approaches and varied successional trajectories indicative of secondary forest recovery occurring across the broader northeastern forest landscape. We also used 150 years of documentary data from park management records. This research evaluates the effects of reforestation approaches (planting vs. natural regeneration), management regimes (long-term low-to-intermediate harvest intensities at varied harvest frequencies), and stand development pathways on biomass outcomes. We generated biometrics representative of stand structural complexity, including the H' structural diversity index, and aboveground biomass (live trees, snags, and downed coarse woody debris pools) estimates. Multivariate analyses evaluated the predictive strength of reforestation approach, management history, and site characteristics relative to aboveground carbon pools and stand structural complexity. Classification and Regression Tree (CART) analysis ranked reforestation approach (plantation or natural regeneration) as the strongest predictor of long-term mean total aboveground carbon storage, while harvest frequency, and stand age were selected as secondary variables. CART ranked forest percent conifer (a metric closely associated with reforestation approach) as the strongest predictor of H' index, while harvest intensity, and harvest frequency were selected as secondary variables. Increases in harvest intensity can significantly reduce aboveground carbon storage. Our results suggest that a variety of long-term recovery pathways converge on high levels of aboveground carbon storage, including both conifer plantations and naturally regenerated hardwood stands, but choice of silvicultural management approach can dramatically alter those trajectories. Importantly, total aboveground biomass (i.e., carbon) co-varied with H' (r2 = 0.25), and thus, our dataset showed a positive relationship between forest carbon storage and structural complexity, supporting the concept of multifunctional forestry emphasizing late-successional habitats.
162

Phosphate Removal and Recovery from Wastewater by Natural Materials for Ecologically Engineered Wastewater Treatment Systems

Curran, Daniel Thomas 01 January 2015 (has links)
Eutrophication due to excess loading of phosphorus (P) is a leading cause of water quality degradation within the United States. The aim of this study was to investigate P removal and recovery with 12 materials (four calcite varieties, wollastonite, dolomite, hydroxylapatite, eggshells, coral sands, biochar, and activated carbon. This was accomplished through a series of batch experiments with synthetic wastewater solutions ranging from 10-100 mg PO₄-P/ L. The results of this study were used to establish large-scale, calcite-based column filter experiments located in the Rubenstein School of Environment and Natural Resources' Eco-Machine. Influent and effluent wastewater samples were routinely collected for 64 days. Measures of filter performance included changes in pH, percent reduction and mass adsorbed of P. After the columns reached saturation, filter media was analyzed for the mineralogical content by X-ray powder diffraction (XRD). In the batch experiments, P removal and recovery varied among the media and across treatments. The best performing minerals were calcite, wollastonite, and hydroxylapatite. Eggshells, activated carbon, and coral sands also reduced and adsorbed P. The remaining materials had the lowest reductions and adsorption of P. Results from batch experiments informed the design of large column filters within the Rubenstein School of the Environment and Natural Resources' Eco-Machine. Removal and adsorption rates of P by the three column filters were similar. The columns achieved an average P reduction of 12.53% (se = 0.98) and an average P adsorption of 0.649 mg PO₄-P/ kg media (se = 0.03) over a 4-h hydraulic retention time. Paired T-tests showed that P reductions were statistically significant (p-value < 0.05) on the majority of sampling dates until the columns reached saturation. Saturation was reached after 31 days for two of the columns and 36 days for the third column. The filter media consistently buffered the pH of the wastewater to approximately 6.0-7.0 with no indication of diminishing buffer capacity after saturation. XRD analysis was not able to detect any P species within the crystalline structure of the filter media. This research contributes to the understanding of how the selected media perform during P removal and recovery programs, while providing information on the performance of large column filters operating within advanced, ecologically engineered wastewater treatment systems.
163

The Impact of Engagement With Community Supported Agriculture on Human Attitude Towards the Sustainable Food Movement

Cano, Ariana Margarita 01 January 2015 (has links)
With a total of 164 community supported agriculture programs (CSA), Vermont is leading the "locavore" movement in the United States, ranked number one in the country with the most CSAs and Food Hubs per capita. ("Locavore Index," 2013) CSAs have a large positive impact on reducing carbon emissions, advancing local economic growth, and promoting healthy lifestyles of consumers. The purpose of this study is to explore the overall experience of individuals in comparison to their current social norm, individual attitudes, identity, and intentions of change, and understand any change overtime in their individual attitude and behavior. Attitude change was measured by conducting pre and post surveys of the Intervale Food Hub UVM student members, as well as regression analysis to understand any possible indicators of chance. The data analysis provided understanding of the impact of the Intervale Food Hub's CSA membership on individuals' attitudes, norms, and identity. Survey questions, based on the theory of planned behavior, inquired about individuals' preferences, skills, and behavioral intentions. Because of the complexity of food and human relations, this data was be supplemented by collecting qualitative data to more richly understand the relationship between individuals and their Intervale Food Hub food shares. The conclusion of this study will advance understanding of one form of community supported-agriculture and its impact on human attitudes. Study findings will also aid the staff of the Intervale Food Hub in understanding their customers and implementing more efficient practices.
164

Coastal Land Loss and Collaborative Resource Governance: The Case of Plaquemines Parish, Louisiana

Seth, Nandini 18 December 2014 (has links)
The research, presented here, is about the collaborative governance and adaptive management in coastal planning efforts of Louisiana. Fundamental conflict, between the idea of environmental conservation and developmental growth, has always existed in the coastal regions. The presence of the large number of environmental laws, at various levels of government and their different management objectives for utilization of coastal resources, requires study of intergovernmental relationship. Taking Plaquemines Parish as a case in point, this thesis will, therefore, review the critical restoration plans for intergovernmental coordination and conflicts. It will also provide recommendations, for elected representatives and policy makers, with an aim to promote collaborative governance and improve adaptive management of coastal resources.
165

Estimating Heat-Related Mortality in the U.S. and In China Using Downscaled Climate Projections

Li, Ying, Zhang, Wei 07 April 2017 (has links)
Public health effects associated with rising temperatures resulted from global climate change are expected to increase significantly in this century. Projecting future heat-related mortality is challenging due to some considerable uncertainties, and national-level impacts under the latest greenhouse gas emission scenarios remain unexplored. This study investigates future excess heat-related mortality in two large countries: The United States and China in 2050s under the latest Representative Concentration Pathways (RCPs) emission scenarios. Using model-simulated future and present climate variables that were dynamically downscaled, we quantify the potential increase in heat-related mortality during the warm season. We study the entire continental U.S. and 51 largest urban areas in China, which roughly account for one third of population in China. We derive heat mortality risk estimates and adaptation assumptions from a comprehensive review of current literature of temperature-mortality relationships in both countries. We incorporate the latest population projection in both countries, and also investigate geographical variations in heat mortality risk and sources of uncertainty including population adaptation. Our findings suggest that future heat mortality risk attributable to elevated warm season temperature is likely to be significant in both countries studied, with substantial geographic variations, highlighting the significance of climate mitigation and local-level heat risk management.
166

Water Management Efficiency in the Food and Beverage Industry

Reyes Torres, Maria Del C 01 January 2016 (has links)
Water is critical for food production, food security, and health. Water quality management influences freshwater sustainability, land, and energy administration. Global agriculture accounts for more than 70% of all water consumption; the fertilizer, manure, and pesticide overspills are chief sources of water pollution worldwide. On a global scale, food-related waste directly impacts local food production and water resource management. The purpose of this multiple-case study on the food and beverage (FB) industry in the State of Georgia was to identify successful strategies for improving water management efficiency. The concepts of systems thinking, adaptive resource management, and integrated water resource management provided the conceptual framework for the study. Data were collected via personal interviews with 2 global supply chain leaders in the FB industry and 1 water expert in the public water utility system in Georgia. The findings showed 10 themes: sustainability; mission-driven culture; ethical responsibility; water quality and governance; food safety and sanitation; water conservation and climatic trends; waste management; nutrition and the freeze drying method; knowledge sharing and collaboration; and water detention and retention systems. The study results are intended to contribute to social change by providing information to global supply chain leaders, policy makers, entrepreneurs, and sustainability leaders to implement sustainability beyond the environmental value; these findings will also help achieve a positive posture on resource overconsumption and waste management for efficient and complex decision making within a worldwide spectrum.
167

EVALUATION OF A SEQUENTIAL POND SYSTEM FOR DETENTION AND TREATMENT OF RUNOFF AT SKYPARK, SANTA'S VILLAGE

Caporuscio, Elizabeth 01 December 2018 (has links)
Understanding the extent to which human activities impact surface water resources has become increasingly important as both human population growth and related landscape changes impact water quality and quantity across varying geographical scales. Skypark, Santa’s Village is a 233.76-acre tourism-based outdoor recreation area located in Skyforest, California residing within the San Bernardino National Forest. The park is situated at Hooks Creek, the headwaters of the Mojave River Watershed, and is characterized by a diverse landscape that includes forest cover and human development, including impervious surfaces, a restored meadow, and recreational trails. In 2016, Hencks Meadow was considered degraded by human activity and restored by the Natural Resources Conservation Services (NRCS) using best management practices (BMPs) to manage stormwater runoff and mitigate pollutants entering recreational downstream surface water. Three BMP detention basins were constructed to store and improve water quality from stormwater runoff. The purpose of this study is to observe the extent to which the engineered BMP detention basins design were effective in mitigating stormwater pollution from entering Hooks Creek. Over a six to eight month period (January to August), ponds were tested in situ bi-weekly for temperature (ºC), dissolved oxygen (mg/L), pH, turbidity (NTU), conductivity (µS/cm), nitrate (mg/L), and ammonium (mg/L), with additional laboratory tests for total suspended solids (mg/L), total dissolved solids (mg/L), chemical oxygen demand (mg/L), total coliform (MPN/100mL), Escherichia coli (MPN/100mL), and trace metals (µg/L). The results of this study support that the BMP design is improving surface stormwater runoff from impervious surfaces before it enters Hooks Creek. Findings could also promote the design and implementation of stormwater BMP detention basins at other site locations where water degradation is evident. Furthermore, this research can be used to promote the necessary improvement of water quality and quantity on a widespread geographical scale.
168

Environmental Gradients, Community Boundaries, and Disturbance the Darlingtonia Fens of Southwestern Oregon

Tolman, Deborah A. 01 January 2004 (has links)
The Darlingtonia fens, found on serpentine soils in southern Oregon, are distinct communities that frequently undergo dramatic changes in size and shape in response to a wide array of environmental factors. Since few systems demonstrate a balance among high water tables, shallow soils, the presence of heavy metals, and limited nutrients, conservative efforts have been made to preserve them. This dissertation investigates the role of fire on nutrient cycling and succession in three separate fens, each a different time since fire. I specifically analyze the spatial distributions of soil properties, the physical and ecological characteristics of ecotones between Jeffrey pine savanna and Darlingtonia fens, and the vegetation structure of fire-disturbed systems. Soil, water, and vegetation sampling were conducted along an array of transects, oriented perpendicular to community boundaries and main environmental gradients, at each of the three fens. Abrupt changes in vegetation, across communities, were consistently identified at each of the three sites, although statistical analysis did not always identify distinct mid-canopy communities. Below-ground variables were likewise distinguished at the fen and savanna boundary for two of the three sites. At the third site, discontinuities did not align with the fen boundaries, but followed fluctuations in soil NH4. My results suggest that below-ground discontinuities may be more important than fire at preserving these uniquely-adapted systems, while vegetation undergoes postfire succession from fen to mid-canopy to savanna after approximately 100 years since fire. Although restoration of ecosystem structure and processes was not the primary focus of this study, my data suggest that time since fire may drive ecosystem processes in a trajectory away from the normal succession cycle. Moreover, time since fire may decrease overall vigor of Darlingtonia populations.
169

The Effects of Urbanization and Human Disturbance Upon Plant Community Structure and Bird Species Richness, Diversity, and Abundance in a Natural Forested Area (Forest Park) in Portland, Oregon

Broshot, Nancy Ellen 01 January 1999 (has links)
The effects of urbanization and continual human disturbance on the plant and avian communities of Forest Park and forested lands surrounding Portland, Oregon, were studied. I examined characteristics of plant and avian communities at 25 sites, 24 which were in Forest Park and surrounding areas and one which was in the Ancient Forest Preserve (old-growth stand) northwest of Forest Park. Data were analyzed using multiple regression, ANOV A, and Bonferonni/Dunn. Seven variables were selected representing different urbanization gradients. An additional covariable coded for the old-growth stand, allowing it to be used as a control. Many tree variables, especially those related to shade-tolerant species, were positively correlated with both the distance from downtown Portland and the number of houses in the surrounding area, and negatively correlated with the distance from the nearest forest edge; however, many shrub and herbaceous variables were negatively correlated with the distance from downtown Portland. Species diversity for herbaceous and shrub species was greater at more urban sites, but diversity of trees was lower at more urban sites. There were significantly more non-native species of plants in the city section. I found significantly fewer saplings and small trees, especially shade-tolerant species, in the section of Forest Park closest to downtown Portland, although tree mortality was positively correlated with distance from Portland. Summer bird data revealed significant increases in the abundances of urban and edge species at more urban sites, with concomitant reductions in forest species. There were significantly more ground gleaning birds and short distance migratory species. I also found a significantly greater abundance of birds in the old-growth stand during the winter. This increase was positively correlated with the depth of snow in the nearby Cascade Mountains. My results indicate that Forest Park is apparently progressing in a normal successional pattern with the exception of the city section. The reduction in shade tolerant saplings and small trees in the city section suggest that rate of succession has been slower at more urban sites. Avian data suggest that urbanization affects bird species abundance and guild composition in the more urban areas.
170

Relationship Between Corporate Social Responsibility, Environmental Management, and Profitability

Valentin, Dr. Daisy 01 January 2018 (has links)
The U.S. hospitality industry's profitability has been shifting to environmental management and corporate social responsibility (CSR) practices. Hospitality industries accounted for 5% of the global market in 2015 and are expected to increase by 130% in 2035. Grounded in stakeholder theory, this correlation study examined the relationship between corporate sustainability officer (CSO) CSR, CSO environmental management, and hospitality business profitability. Secondary data were collected from 97 hotel websites of the Minneapolis-St. Paul, Minnesota area from 2014 to 2016. The multiple linear regression combinations of CSR and environmental management (EM) measured significantly related to the profitability index, F(3, 93) = 4.67, p < .001, adj. R2 = .13. The sample multiple correlation coefficients were .36, indicating approximately 13% of the variance of the profitability index. The multiple linear regression combinations of CSR measures significantly related to the profitability index, F(2,94) = 6.05, p < .001, adjusted R2 = .11. The sample multiple correlation coefficients were .34, indicating approximately 11% of the variance of the profitability index. The linear combination of EM measures were not significantly related to the profitability index, F(2,94) = 2.91, p < .001, adjusted R2 = .06. The sample multiple correlation coefficients were .24, indicating approximately 6% of the variance of the profitability index. The implications for positive social change include the potential to identify hospitality industry leaders involved in environmental management who have a CSR to promote social change in their communities.

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