Matching Items (142)
Grasshoppers Regulate N: P Stoichiometric Homeostasis by Changing Phosphorus Contents in Their Frass
Description
Nitrogen (N) and phosphorus (P) are important limiting nutrients for plant production and consumer performance in a variety of ecosystems. As a result, the N:P stoichiometry of herbivores has received increased attention in ecology. However, the mechanisms by which herbivores maintain N:P stoichiometric homeostasis are poorly understood. Here, using a field manipulation experiment we show that the grasshopper Oedaleus asiaticus maintains strong N:P stoichiometric homeostasis regardless of whether grasshoppers were reared at low or high density. Grasshoppers maintained homeostasis by increasing P excretion when eating plants with higher P contents. However, while grasshoppers also maintained constant body N contents, we found no changes in N excretion in response to changing plant N content over the range measured. These results suggest that O. asiaticus maintains P homeostasis primarily by changing P absorption and excretion rates, but that other mechanisms may be more important for regulating N homeostasis. Our findings improve our understanding of consumer-driven P recycling and may help in understanding the factors affecting plant-herbivore interactions and ecosystem processes in grasslands.
ContributorsZhang, Zijia (Author) / Elser, James (Author) / Cease, Arianne (Author) / Zhang, Ximei (Author) / Yu, Qiang (Author) / Han, Xingguo (Author) / Zhang, Guangming (Author) / College of Liberal Arts and Sciences (Contributor) / School of Life Sciences (Contributor) / Julie Ann Wrigley Global Institute of Sustainability (Contributor) / School of Sustainability (Contributor)
Created2014-08-04
Description
A large fraction of the world grasslands and savannas are undergoing a rapid shift from herbaceous to woody-plant dominance. This land-cover change is expected to lead to a loss in livestock production (LP), but the impacts of woody-plant encroachment on this crucial ecosystem service have not been assessed. We evaluate how tree cover (TC) has affected LP at large spatial scales in rangelands of contrasting social–economic characteristics in the United States and Argentina. Our models indicate that in areas of high productivity, a 1% increase in TC results in a reduction in LP ranging from 0.6 to 1.6 reproductive cows (Rc) per km[superscript 2]. Mean LP in the United States is 27 Rc per km[superscript 2], so a 1% increase in TC results in a 2.5% decrease in mean LP. This effect is large considering that woody-plant cover has been described as increasing at 0.5% to 2% per y. On the contrary, in areas of low productivity, increased TC had a positive effect on LP. Our results also show that ecological factors account for a larger fraction of LP variability in Argentinean than in US rangelands. Differences in the relative importance of ecological versus nonecological drivers of LP in Argentina and the United States suggest that the valuation of ecosystem services between these two rangelands might be different. Current management strategies in Argentina are likely designed to maximize LP for various reasons we are unable to explore in this effort, whereas land managers in the United States may be optimizing multiple ecosystem services, including conservation or recreation, alongside LP.
ContributorsAnadon, Jose Daniel (Author) / Sala, Osvaldo (Author) / Turner II, B. L. (Author) / Bennett, Elena M. (Author) / College of Liberal Arts and Sciences (Contributor) / School of Life Sciences (Contributor) / Julie Ann Wrigley Global Institute of Sustainability (Contributor) / School of Sustainability (Contributor) / School of Geographical Sciences and Urban Planning (Contributor)
Created2014-09-02
Description
We studied the microbial community structure of pilot two-stage membrane biofilm reactors (MBfRs) designed to reduce nitrate (NO[subscript 3]–) and perchlorate (ClO[subscript 4]–) in contaminated groundwater. The groundwater also contained oxygen (O[subscript 2]) and sulfate (SO[2 over 4]–), which became important electron sinks that affected the NO[subscript 3]– and ClO[subscript 4]– removal rates. Using pyrosequencing, we elucidated how important phylotypes of each “primary” microbial group, i.e., denitrifying bacteria (DB), perchlorate-reducing bacteria (PRB), and sulfate-reducing bacteria (SRB), responded to changes in electron-acceptor loading. UniFrac, principal coordinate analysis (PCoA), and diversity analyses documented that the microbial community of biofilms sampled when the MBfRs had a high acceptor loading were phylogenetically distant from and less diverse than the microbial community of biofilm samples with lower acceptor loadings. Diminished acceptor loading led to SO[2 over 4]– reduction in the lag MBfR, which allowed Desulfovibrionales (an SRB) and Thiothrichales (sulfur-oxidizers) to thrive through S cycling. As a result of this cooperative relationship, they competed effectively with DB/PRB phylotypes such as Xanthomonadales and Rhodobacterales. Thus, pyrosequencing illustrated that while DB, PRB, and SRB responded predictably to changes in acceptor loading, a decrease in total acceptor loading led to important shifts within the “primary” groups, the onset of other members (e.g., Thiothrichales), and overall greater diversity.
ContributorsOntiveros-Valencia, Aura (Author) / Tang, Youneng (Author) / Zhao, Heping (Author) / Friese, David (Author) / Overstreet, Ryan (Author) / Smith, Jennifer (Author) / Evans, Patrick (Author) / Rittmann, Bruce (Author) / Krajmalnik-Brown, Rosa (Author) / Biodesign Institute (Contributor) / Swette Center for Environmental Biotechnology (Contributor) / Julie Ann Wrigley Global Institute of Sustainability (Contributor) / School of Sustainability (Contributor)
Created2014-07-01
Description
This thesis conducted an evaluation of the performance and return on investment of a 2 x 6m, simple design greenhouse, as a climate control technology. Specifically, differences in internal microclimate conditions between a greenhouse treatment plot, and sun and shaded control plots were assessed and related to observed differences in crop yields across these plots. Growing conditions and productivity of two crops, tomato and swiss chard, which were grown over summer and winter growing seasons, respectively, were compared. It was found that the greenhouse was associated with improved growth conditions (as measured by the R-Index) for both crops but resulted in higher productivity only for tomatoes. Return on investment and food security impacts from the scaling of greenhouse agriculture were also explored.
ContributorsKline, Jarod Neale (Author) / Aggarwal, Rimjhim (Thesis director) / Agusdinata, Datu Buyung (Committee member) / Vanos, Jennifer K. (Committee member) / School of Sustainability (Contributor) / Economics Program in CLAS (Contributor) / Barrett, The Honors College (Contributor)
Created2020-05
Description
The past decades have seen major changes with globalization, increased trade, digital technologies, and the increased threat of climate change consequences. These changes in trends have changed how the world communicates, travels, produces, manufactures, and develops. Yet despite having the most advanced technologies and the most connected world to date, other aspects of development and quality of life have not kept up the pace in adapting and changing based on these trends. Specifically in developing countries, while the outside environment may be changing, the systems, structures, and societal values in place have not fully adapted. These aspects of society are naturally slower to change which can be dangerous when dealing with the current issues the world faces, for example the proven increase in climate change consequences. The consequences of slow or no changes at all in systems, structures, and societal values fall disproportionately on women who are often now bearing more responsibility without the benefits due to outdated structures that were developed based on other environments and priorities. This gap between the formal structures and the rapidly changing environments and its effect on women can be seen through analyzing specific common trends in developing countries, such as the feminization of agriculture and climate change. Analyzing this gap from these specific trends can give insight into possible solutions to both speed up the closing of the gap and lessen the burdens for women in the meantime. The role of informal or community networks should be considered as a possible way to do this. The case of St. Lucia and its experience with both the feminization of agriculture and the threat of climate change will be analyzed to understand how informal or community networks could serve to help close the gap and lessen the burdens for women.
ContributorsDooley, Hanna Mary (Author) / Augustin-Behravesh, Shirley-Ann (Thesis director) / Aggarwal, Rimjhim (Committee member) / Dean, W.P. Carey School of Business (Contributor) / School of International Letters and Cultures (Contributor) / Department of Economics (Contributor) / School of Politics and Global Studies (Contributor) / Barrett, The Honors College (Contributor)
Created2020-05
Description
This thesis explores the framing of gender equity within International Development organizations and the design of projects to promote it. Using case studies of projects financed by United States Agency for International Development (a major donor agency), and Inter Pares (a Canadian NGO) as evidence, the thesis identifies what works and what does not work in different contexts within these projects.
ContributorsPetersen, Melia Bea (Author) / Aggarwal, Rimjhim (Thesis director) / Manuel-Navarette, David (Committee member) / School of Politics and Global Studies (Contributor) / School of International Letters and Cultures (Contributor) / School of Sustainability (Contributor) / Barrett, The Honors College (Contributor)
Created2018-05
Description
The objective of this study was to better understand promising pathways to realizing human rights norms in the context of rapidly developing cities, and the role that the courts play in this process. Scholars have already started to ask these larger questions of social transformation; however, there continues to be a need for further research since the answers are vast and context-dependent. In order to contribute to these larger conversations, this project examined a key social right in Delhi \u2014 the right to housing. This study relied on interviews with key actors in Delhi's housing sector as well as a review of housing rights cases in the Delhi High Court in order to understand what mechanisms various actors utilize in the context of Delhi to realize the human right to housing on the ground. These two types of data were compared and contrasted to past research on human rights scholarship, law and social literature, and studies on urbanization. Two frameworks from these bodies of knowledge, the MAPs framework developed by Haglund and Aggarwal (2011) and the triangular framework created by Gauri and Brinks (2008), were utilized in particular to analyze interview and court data. Overall, this study found that the courts in India are advocates for housing rights, but that their advocacy is often limited, cautious, and influenced by a pattern of bias against populations without legal title to land. This study also found that communities and their allies are often more successful in realizing the right to housing when they combine litigation with other non-legal social change mechanisms. Consequently, it appears that the role of the courts in realizing ESR in Delhi is both complicated and limited, which means that pathways toward ESR realization are more promising when they incorporate non-legal mechanisms alongside court action.
ContributorsHale, Nicole (Author) / Haglund, LaDawn (Thesis director) / Aggarwal, Rimjhim (Committee member) / Barrett, The Honors College (Contributor)
Created2016-05
Description
During the months from June to November 2012, the city of Bangalore was faced with a serious solid waste management (SWM) crisis. In the wake of the upheaval, the state court declared source segregation to be mandatory. Yet, while the legislation was clear, the pathway towards a course of action for the transition was not clear and hence, Bangalore was stuck in a state of limbo. The objectives for this thesis spiraled organically from this crisis. The first objective was to examine the gaps in Bangalore's transition to a more sustainable SWM system. Six particular gaps were identified, which in essence, were opportunities to re-shape the system. The gaps identified included: conflicting political agendas, the exclusion of some key actors, and lack of adequate attention to cultural aspects, provision of appropriate incentives, protection of livelihoods and promotion of innovation. Opportunities were found in better incentivization of sustainable SWM goals, protecting livelihoods that depend on waste, enhancing innovation and endorsing local, context based SWM solutions. Building on this understanding of gaps, the second objective was to explore an innovative, local, bottom-up waste-management model called the Vellore Zero Waste Model, and assess its applicability to Bangalore. The adaptability of the model depended on several factors such as, willingness of actors to redefine their roles and change functions, ability of the municipality to assure quality and oversight, willingness of citizen to source segregate, and most importantly, the political will and collective action needed to ensure and sustain the transition. The role of communication as a vital component to facilitate productive stakeholder engagement and to promote role change was evident. Therefore, the third objective of the study was to explore how interpersonal competencies and communication strategies could be used as a tool to facilitate stakeholder engagement and encourage collective action. In addressing these objectives, India was compared with Austria because Austria is often cited as having some of the best SWM practices in the world and has high recycling rates to show for its reputation.
ContributorsRengarajan, Nivedita (Author) / Aggarwal, Rimjhim (Thesis advisor) / Chhetri, Nalini (Committee member) / Manuel-Navarrete, David (Committee member) / Arizona State University (Publisher)
Created2013
Description
The City of Phoenix Street Transportation Department partnered with the Rob and Melani Walton Sustainability Solutions Service at Arizona State University (ASU) and researchers from various ASU schools to evaluate the effectiveness, performance, and community perception of the new pavement coating. The data collection and analysis occurred across multiple neighborhoods and at varying times across days and/or months over the course of one year (July 15, 2020–July 14, 2021), allowing the team to study the impacts of the surface treatment under various weather conditions.
ContributorsMiddel, Ariane (Author) / Vanos, Jennifer K. (Author) / Hondula, David M. (Author) / Kaloush, Kamil (Author) / Sailor, David (Author) / Medina, Jose R. (Jose Roberto) (Author) / Schneider, Florian (Author) / Ortiz, Johny Cordova (Author) / Campbell, Bill (Author) / Epel, Erin (Contributor) / Rice, Brendan (Contributor) / Garcia, Ruth (Contributor) / Phoenix (Ariz.). Street Transportation Department (Contributor) / City of Phoenix (Funder) / Industrial Development Authority of the County of Maricopa (Funder) / Julie Ann Wrigley Global Institute of Sustainability (Funder) / Arizona State University. Healthy Urban Environments Program (Contributor)
Created2021-09
Description
Food waste is one of the most significant food system inefficiencies with environmental, financial, and social consequences. This waste, which occurs more at the consumer stage in high income countries, is often attributed to consumers’ behavior. While behavior is a contributing factor, the role of other contextual factors in influencing this behavior has not been systematically analyzed. Understanding contextual drivers of consumer food waste behavior is important, as behavior sits in a matrix of technology, infrastructures, institutions and social structure. Hence designing effective interventions will require a systems perceptive of the problem. In paper 1, I used Socio-ecological framing to understand how personal, interpersonal, socio-cultural, built, and institutional environments contribute to food waste at the consumer stage. In paper 2, I explored the perception of stakeholders in Phoenix on the effectiveness and feasibility of possible interventions that could be used to tackle consumer food waste. In paper 3, I examined the impact of knowledge and awareness of the environmental consequence of food waste in terms of embedded water and energy on the cognitive factors responsible for consumer food waste behavior. Across these three papers, I have identified three findings. First, the most influential factor responsible for consumer food waste is meal planning, as many decisions about food management depend on it. However, there are many contextual factors that discourage meal planning. Other factors identified include the wide gap between food producers and consumers, the low price of food, and marketing strategies used by retailers to encourage food purchases. Systems level interventions will be required to address these drivers that provide an enabling environment for behavioral change. Second stakeholders in the city overwhelmingly support and agree that education will be the most effective and feasible intervention to address consumer food waste, 3) there is need to carefully craft education materials to inform consumers about other resources, such as water and energy, embedded in food waste to stimulate a personal norm that motivates change in behavior. In this study, I emphasize the need to understand the root causes of consumer food waste and exploration of systems level interventions, in combination with education and information interventions that are being commonly used.
ContributorsOpejin, Adenike Kafayat (Author) / Aggarwal, Rimjhim (Thesis advisor) / White, Dave (Thesis advisor) / Garcia, Margret (Committee member) / Merrigan, Kathleen (Committee member) / Arizona State University (Publisher)
Created2022