Matching Items (67)
Description
Phosphorus (P), an essential element for life, is becoming increasingly scarce, and its global management presents a serious challenge. As urban environments dominate the landscape, we need to elucidate how P cycles in urban ecosystems to better understand how cities contribute to — and provide opportunities to solve — problems of P management. The goal of my research was to increase our understanding of urban P cycling in the context of urban resource management through analysis of existing ecological and socio-economic data supplemented with expert interviews in order to facilitate a transition to sustainable P management. Study objectives were to: I) Quantify and map P stocks and flows in the Phoenix metropolitan area and analyze the drivers of spatial distribution and dynamics of P flows; II) examine changes in P-flow dynamics at the urban agricultural interface (UAI), and the drivers of those changes, between 1978 and 2008; III) compare the UAI's average annual P budget to the global agricultural P budget; and IV) explore opportunities for more sustainable P management in Phoenix. Results showed that Phoenix is a sink for P, and that agriculture played a primary role in the dynamics of P cycling. Internal P dynamics at the UAI shifted over the 30-year study period, with alfalfa replacing cotton as the main locus of agricultural P cycling. Results also suggest that the extent of P recycling in Phoenix is proportionally larger than comparable estimates available at the global scale due to the biophysical characteristics of the region and the proximity of various land uses. Uncertainty remains about the effectiveness of current recycling strategies and about best management strategies for the future because we do not have sufficient data to use as basis for evaluation and decision-making. By working in collaboration with practitioners, researchers can overcome some of these data limitations to develop a deeper understanding of the complexities of P dynamics and the range of options available to sustainably manage P. There is also a need to better connect P management with that of other resources, notably water and other nutrients, in order to sustainably manage cities.
ContributorsMetson, Genevieve (Author) / Childers, Daniel (Thesis advisor) / Aggarwal, Rimjhim (Thesis advisor) / Redman, Charles (Committee member) / Arizona State University (Publisher)
Created2011
Description
City managers and policy makers are increasing looking to environmental systems to provide beneficial services for urban systems. Constructed wetland systems (CWS), highly managed and designed wetland ecosystems, are being utilized to remove pollution, particularly excess nitrogen (N), from treated wastewater. Various wetland process remove N from effluent, such as denitrification, direct plant uptake, and soil accumulation. Emergent macrophytes provide direct uptake of N and improve conditions for microbially-mediated N processing. The role of different macrophytes species, however, is less understood and has primarily been examined in mesocosm and microcosm experiments and in mesic environments. I examined the effects of community composition on N removal and processing at the whole ecosystem scale in an aridland, constructed wetland (42 ha) through: 1) quantifying above- and belowground biomass and community composition from July 2011 \u2014 November 2012 using a non-destructive allometric technique, and; 2) quantifying macrophyte N content and direct macrophyte N uptake over the 2012 growing season. Average peak biomass in July 2011 & 2012 was 2,930 g dw/m2 and 2,340 g dw/m2, respectively. Typha spp. (Typha domingensis and Typha latifolia) comprised the majority (approximately 2/3) of live aboveground biomass throughout the sampling period. No statistically significant differences were observed in macrophyte N content among the six species present, with an overall average of 1.68% N in aboveground tissues and 1.29% N in belowground tissues. Per unit area of wetland, Typha spp. retained the most N (22 g/m2); total N retained by all species was 34 g/m2. System-wide direct plant N uptake was markedly lower than N input to the system and thus represented a small portion of system N processing. Soil accumulation of N also played a minor role, leaving denitrification as the likely process responsible for the majority of system N processing. Based on a literature review, macrophyte species composition likely influences denitrification through oxygen diffusion into soils and through the quality and quantity of carbon in leaf litter. While this study and the literature indicates Typha spp. may be the best species to promote wetland N processing, other considerations (e.g., bird habitat) and conditions (e.g., type of wastewater being treated) likely make mixed stands of macrophytes preferable in many applications. Additionally, this study demonstrated the importance of urban wetlands as scientific laboratories for scientists of all ages and as excellent stepping-off points for experiments of science-policy discourse.
ContributorsWeller, Nicholas Anton (Author) / Daniel L., Childers (Thesis director) / Grimm, Nancy (Committee member) / Turnbull, Laura (Committee member) / Barrett, The Honors College (Contributor) / School of Sustainability (Contributor) / School of Public Affairs (Contributor) / Graduate College (Contributor)
Created2013-05
Description
Farmers' markets are a growing trend both in Arizona and the broader U.S., as many recognize them as desirable alternatives to the conventional food system. As icons of sustainability, farmers' markets are touted as providing many environmental, social, and economic benefits, but evidence is mounting that local food systems primarily serve the urban elite, with relatively few low-income or minority customers. However, the economic needs of the market and its vendors often conflict with those of consumers. While consumers require affordable food, farmers need to make a profit. How farmers' markets are designed and governed can significantly influence the extent to which they can meet these needs. However, very little research explores farmers' market design and governance, much less its capacity to influence financial success and participation for underprivileged consumers. The present study examined this research gap by addressing the following research question: How can farmers' markets be institutionally designed to increase the participation of underprivileged consumers while maintaining a financially viable market for local farmers? Through a comparative case study of six markets, this research explored the extent to which farmers' markets in Central Arizona currently serve the needs of farmer-vendors and underprivileged consumers. The findings suggest that while the markets serve as a substantial source of income for some vendors, participation by low-income and minority consumers remains low, and that much of this appears to be due to cultural barriers to access. Management structures, site characteristics, market layout, community programs, and staffing policies are key institutional design features, and the study explores how these can be leveraged to better meet the needs of the diverse participants while improving the markets' financial success.
ContributorsTaylor, Carissa (Author) / Aggarwal, Rimjhim (Thesis advisor) / York, Abigail (Committee member) / Wharton, Christopher (Christopher Mack), 1977- (Committee member) / Arizona State University (Publisher)
Created2013
Description
Hydrology and biogeochemistry are coupled in all systems. However, human decision-making regarding hydrology and biogeochemistry are often separate, even though decisions about hydrologic systems may have substantial impacts on biogeochemical patterns and processes. The overarching question of this dissertation was: How does hydrologic engineering interact with the effects of nutrient loading and climate to drive watershed nutrient yields? I conducted research in two study systems with contrasting spatial and temporal scales. Using a combination of data-mining and modeling approaches, I reconstructed nitrogen and phosphorus budgets for the northeastern US over the 20th century, including anthropogenic nutrient inputs and riverine fluxes, for ~200 watersheds at 5 year time intervals. Infrastructure systems, such as sewers, wastewater treatment plants, and reservoirs, strongly affected the spatial and temporal patterns of nutrient fluxes from northeastern watersheds. At a smaller scale, I investigated the effects of urban stormwater drainage infrastructure on water and nutrient delivery from urban watersheds in Phoenix, AZ. Using a combination of field monitoring and statistical modeling, I tested hypotheses about the importance of hydrologic and biogeochemical control of nutrient delivery. My research suggests that hydrology is the major driver of differences in nutrient fluxes from urban watersheds at the event scale, and that consideration of altered hydrologic networks is critical for understanding anthropogenic impacts on biogeochemical cycles. Overall, I found that human activities affect nutrient transport via multiple pathways. Anthropogenic nutrient additions increase the supply of nutrients available for transport, whereas hydrologic infrastructure controls the delivery of nutrients from watersheds. Incorporating the effects of hydrologic infrastructure is critical for understanding anthropogenic effects on biogeochemical fluxes across spatial and temporal scales.
ContributorsHale, Rebecca Leslie (Author) / Grimm, Nancy (Thesis advisor) / Childers, Daniel (Committee member) / Vivoni, Enrique (Committee member) / York, Abigail (Committee member) / Wu, Jianguo (Committee member) / Arizona State University (Publisher)
Created2013
Description
This research presents an analysis of the main institutions and economic incentives that drive farmers behaviors on water use in the Chancay-Lambayeque basin, located in Lambayeque (Peru), a semi arid area of great agricultural importance. I focus my research on identifying the underlying causes of non-collaborative behaviors in regard to water appropriation and infrastructure provisioning decision that generates violent conflicts between users. Since there is not an agreed and concrete criteria to assess "sustainability" I used economic efficiency as my evaluative criteria because, even though this is not a sufficient condition to achieve sustainability it is a necessary one, and thus achieving economic efficiency is moving towards sustainable outcomes. Water management in the basin is far from being economic efficient which means that there is some room for improving social welfare. Previous studies of the region have successfully described the symptoms of this problem; however, they did not focus their study on identifying the causes of the problem. In this study, I describe and analyze how different rules and norms (institutions) define farmers behaviors related to water use. For this, I use the Institutional Analysis and Development framework and a dynamic game theory model to analyze how biophysical attributes, community attributes and rules of the system combined with other factors, can affect farmers actions in regard to water use and affect the sustainability of water resources. Results show that water rights are the factor that is fundamental to the problem. Then, I present an outline for policy recommendation, which includes a revision of water rights and related rules and policies that could increase the social benefits with the use of compensation mechanisms to reach economic efficiency. Results also show that commonly proposed solutions, as switch to less water intensive and more added value crops, improvement in the agronomic and entrepreneurial knowledge, or increases in water tariffs, can mitigate or exacerbate the loss of benefits that come from the poor incentives in the system; but they do not change the nature of the outcome.
ContributorsRubinos, Cathy (Author) / Eakin, Hallie (Committee member) / Abbot, Joshua K (Committee member) / York, Abigail (Committee member) / Arizona State University (Publisher)
Created2013
Description
Over the last few decades, the western United States has experienced more extreme wildland fire events, remarkable for their size and severity. The frequency, intensity, and size of wildfires is projected to only increase, with severe consequences for biodiversity, ecosystem services, human property, and more broadly, the sustainability of western forests. These trends are the result of a complex suite of factors including, past land-use policies, fire suppression, climate change, and human development. To protect fire-adapted ecosystems from further damage, fuel reduction and fire reintroduction are required over large landscapes, necessitating government agencies, landowners, and other interests to work together. In response, collaborative fire restoration efforts are forming to carry out this much needed work. This research takes a multi-level approach to understanding these new models for fire management and restoration. Collaborative, landscape-level approaches to fire reintroduction are a direct response to a failure in past policies and approaches, which necessitates a discussion of why these policies allowed fires to grow worse and why management failed to effectively prevent this from happening. Thus, a historical analysis of wildland fire policy and management constitutes one layer in this analysis. Collaborative frameworks to wildland fire reintroduction are few and far between, which obliges a discussion of how collaboration works and why it may be necessary. An in-depth case study of FireScape, a collaborative effort in southeastern Arizona to restore wildfire completes this analysis and provides a discussion of the challenges, benefits, and implications of these new approaches. The context for this case study is southeastern Arizona's Sky Islands. The Sky Islands region spans the U.S. Mexico borderlands and is a biodiversity hotspot, making it an ideal place to explore the interactions between humans and natural systems. The more recent emphasis on collaboration in wildfire management has yet to be fully explored in other academic circles. Collaboration is essential in fire restoration and provides one pathway to solve complex natural resource management issues.
ContributorsRaymondi, Ann Marie (Author) / Hirt, Paul W (Thesis advisor) / York, Abigail (Thesis advisor) / Pyne, Stephen J (Committee member) / Arizona State University (Publisher)
Created2012
Description
The heterogeneous nature of urban systems is a documented phenomenon that can potentially cause widespread changes in soil characteristics across urban habitat type. These differences in soil characteristics may be linked to hot spots within the city of greenhouse gas (N2O, CO2, CH4) emissions, which have the potential to affect global climate. The purpose of this study was to take an in depth look at how soil characteristics (i.e. soil moisture, organic matter, and inorganic nitrogen) vary across the urban Phoenix landscape and how these differing landscape characteristics can potentially create hot spots of greenhouse gas emissions. We measured greenhouse gas emissions and soil characteristics from ten different landscape types during the summer and fall of 2013 and included a wetting experiment to simulate flooding events in the desert. Using statistical analyses we found that all soil characteristics varied significantly based on both season and land-use type. In addition, land-use types could be clustered into recognizable groups based on their soil characteristics, with the presence of irrigation being a strong deciding factor in how the groups were arranged. However, N2O emissions did not vary significantly based on season, land-use type, or the presence of a wetting experiment. Patterns reinforce the heterogeneous nature of the Phoenix urban area and suggest that N2O emissions may not relate to soil characteristics and habitat designations (i.e. human land use) in the way that we originally predicted.
ContributorsSampson, Marena Elizabeth (Author) / Grimm, Nancy (Thesis director) / Pollard, Lindsey (Committee member) / Palta, Monica (Committee member) / Barrett, The Honors College (Contributor) / School of Life Sciences (Contributor)
Created2015-05
Description
This project examines a complex issue in urban ecology: the impact of biodiversity on ecosystem services, and considers how this varies across cities. Data were gathered on multiple economic and ecological parameters for a selection of seven cities around the world and analyzed via multiple linear regression in order to assess any relationships that may be at play. Significance values were then calculated to further define the relationships between the data. Analysis found that both biophysical and socioeconomic factors affected ecosystem services, although not all hypotheses regarding these relationships were met. Conclusions indicate that this model was fairly effective in describing physical drivers of ecosystem services, but were not as clear regarding social drivers. Further study regarding social parameters' effect on ecosystem services is recommended.
ContributorsMcDannald, Lindsay JoAnne (Author) / Perrings, Charles (Thesis director) / Kinzig, Ann (Committee member) / Grimm, Nancy (Committee member) / Barrett, The Honors College (Contributor) / School of Life Sciences (Contributor) / School of Sustainability (Contributor)
Created2014-05
Description
During the current excavations at Calixtlahuaca, many aspects of its urban landscape have been uncovered. By using these details, my objective is to determine the political environment of the site. However, in Mesoamerican archaeology, there has been little evaluation of the politics in smaller city-states as compared to larger ones such as Tenochtitlan. In order to solve this dilemma, I compared Calixtlahuaca to two groups of Mesoamerican capital cities: (1) city-state centers such as Cholula, Tlaxcallan, various Aztec city-states; and (2) hillside sites similar to Calixtlahuaca in topographic placement. The importance of certain elements in these sites is more heavily considered than others and sites that have pre-existing knowledge about their political systems took precedence. By comparing urban aspects of these sites including location, population, density, urban layout, and urban architecture, I have created a model that relates urban form to political organization. I applied this model to infer the political organization of Calixtlahuaca. This model can later be applied throughout Mesoamerica and eventually to sites at other regions.
ContributorsSmigielski, Ryan Michael (Author) / Smith, Michael E. (Thesis director) / Nelson, Ben (Committee member) / York, Abigail (Committee member) / Barrett, The Honors College (Contributor) / School of Politics and Global Studies (Contributor) / School of Human Evolution and Social Change (Contributor) / School of Life Sciences (Contributor)
Created2013-05
Description
This project aims to provide a contextualized history of the Sky Harbor Neighborhood Association‟s community collective action efforts. The Sky Harbor Neighborhood (SHN) of East Phoenix is bounded on the West by 24th St., on the East by 32nd St., on the North by Roosevelt St., and the South by Washington Street. SHN is a majority Latino, low-income, working class community (U.S. Census Bureau, 2010) that faces a variety of challenges including low walkability due to inadequate pedestrian infrastructure, low tree coverage, and crime. East Van Buren St., which has a reputation for being one of Phoenix‟s red-light districts, splits the neighborhood in two. In addition, the SHN lacks some key amenities such as grocery stores and is partly considered a food desert by the United States Department of Agriculture (USDA Economic Research Service, 2012).
ContributorsPearson, Kimberly (Author) / Golub, Aaron (Thesis director) / Wiek, Arnim (Committee member) / York, Abigail (Committee member) / Barrett, The Honors College (Contributor) / College of Liberal Arts and Sciences (Contributor) / School of Sustainability (Contributor)
Created2012-12