Matching Items (71)
Description
Land management practices such as domestic animal grazing can alter plant communities via changes in soil structure and chemistry, species composition, and plant nutrient content. These changes can affect the abundance and quality of plants consumed by insect herbivores with consequent changes in population dynamics. These population changes can translate to massive crop damage and pest control costs. My dissertation focused on Oedaleus asiaticus, a dominant Asian locust, and had three main objectives. First, I identified morphological, physiological, and behavioral characteristics of the migratory ("brown") and non-migratory ("green") phenotypes. I found that brown morphs had longer wings, larger thoraxes and higher metabolic rates compared to green morphs, suggesting that developmental plasticity allows greater migratory capacity in the brown morph of this locust. Second, I tested the hypothesis of a causal link between livestock overgrazing and an increase in migratory swarms of O. asiaticus. Current paradigms generally assume that increased plant nitrogen (N) should enhance herbivore performance by relieving protein-limitation, increasing herbivorous insect populations. I showed, in contrast to this scenario, that host plant N-enrichment and high protein artificial diets decreased the size and viability of O. asiaticus. Plant N content was lowest and locust abundance highest in heavily livestock-grazed fields where soils were N-depleted, likely due to enhanced erosion and leaching. These results suggest that heavy livestock grazing promotes outbreaks of this locust by reducing plant protein content. Third, I tested for the influence of dietary imbalance, in conjunction with high population density, on migratory plasticity. While high population density has clearly been shown to induce the migratory morph in several locusts, the effect of diet has been unclear. I found that locusts reared at high population density and fed unfertilized plants (i.e. high quality plants for O. asiaticus) had the greatest migratory capacity, and maintained a high percent of brown locusts. These results did not support the hypothesis that poor-quality resources increased expression of migratory phenotypes. This highlights a need to develop new theoretical frameworks for predicting how environmental factors will regulate migratory plasticity in locusts and perhaps other insects.
ContributorsCease, Arianne (Author) / Harrison, Jon (Thesis advisor) / Elser, James (Thesis advisor) / DeNardo, Dale (Committee member) / Quinlan, Michael (Committee member) / Sabo, John (Committee member) / Arizona State University (Publisher)
Created2012
Description
Habitat fragmentation, the loss of habitat in the landscape and spatial isolation of remaining habitat patches, has long been considered a serious threat to biodiversity. However, the study of habitat fragmentation is fraught with definitional and conceptual challenges. Specifically, a multi-scale perspective is needed to address apparent disagreements between landscape- and patch-based studies that have caused significant uncertainty concerning fragmentation’s effects on biological communities. Here I tested the hypothesis that habitat fragmentation alters biological communities by creating hierarchically nested selective pressures across plot-, patch-, and landscape-scales using woody plant community datasets from Thousand Island Lake, China. In this archipelago edge-effects had little impact on species-diversity. However, the amount of habitat in the surrounding landscape had a positive effect on species richness at the patch-scale and sets of small islands accumulated species faster than sets of large islands of equal total size at the landscape-scale. In contrast, at the functional-level edge-effects decreased the proportion of shade-tolerant trees, island-effects increased the proportion of shade- intolerant trees, and these two processes interacted to alter the functional composition of the regional pool when the total amount of habitat in the landscape was low. By observing interdependent fragmentation-mediated effects at each scale, I found support for the hypothesis that habitat fragmentation’s effects are hierarchically structured.
ContributorsWilson, Maxwell (Author) / Wu, Jianguo (Thesis advisor) / Smith, Andrew (Committee member) / Hall, Sharon (Committee member) / Jiang, Lin (Committee member) / Cease, Arianne (Committee member) / Arizona State University (Publisher)
Created2018
Description
This research examines the communicative processes of resilience in the organizational context of public education. The research utilizes one-on-one interviews to elicit descriptions of resilience and well-being and collect stories of success and overcoming challenges. The study purpose is two-fold: (1) to understand the ways in which organizational members construct and enact resilience individually and collectively through their talk and stories, and (2) to extend the communication theory of resilience through an empirical investigation of resilience in an organizational context. An iterative, thematic analysis of interview data revealed that resilience, as lived, is a socially constructed, collective process. Findings show resilience in this context is (1) socially constructed through past and present experiences informing the ways organizational members perceive challenges and opportunities for action, (2) contextual in that most challenges are perceived positively as a way to contribute to individual and organizational goals and as part of a “bigger purpose” to students, (3) interactional in that it is constructed and enacted collaboratively through social processes, (4) reciprocal in that working through challenges leads to experience, confidence, and building a repertoire of opportunities for action that become a shared experience between educators and is further reciprocated with students, and (5) is enacted through positive and growth mindsets. This study offers theoretical contributions by extending the communication theory of resilience and illuminating intersections to sensemaking, flow, and implicit person theory. I offer five primary practical applications, discuss limitations, and present future directions highlighting community development and strengths-based approaches.
ContributorsKamrath, Jessica K (Author) / Tracy, Sarah J. (Thesis advisor) / Adame, Elissa A. (Committee member) / Cloutier, Scott (Committee member) / Waldron, Vincent R. (Committee member) / Arizona State University (Publisher)
Created2018
Description
Institutions of higher learning can be centers of meaning-making and learning and are expected to play a pivotal role in a global shift toward sustainability. Despite recent innovations, much sustainability education today is still delivered using traditional pedagogies common across higher education. Therefore, students and facilitators should continue innovating along pedagogical themes consistent with the goals of sustainability: transformation and emancipation. Yet, more clarity is needed about pedagogical approaches that will transform and emancipate students, allowing them to become innovators that change existing structures and systems. My dissertation attempts to address this need using three approaches. First, I present a framework combining four interacting (i.e., complementary) pedagogies (transmissive, transformative, instrumental, and emancipatory) for sustainability education, helping to reify pedagogical concepts, rebel against outdated curricula, and orient facilitators/learners on their journey toward transformative and emancipatory learning. Second, I use a descriptive case study of a sustainability education course set outside of the traditional higher education context to highlight pedagogical techniques that led to transformative and emancipatory outcomes for learners partaking in the course. Third, I employ the method of autoethnography to explore my own phenomenological experience as a sustainability student and classroom facilitator, helping others to identify the disenchanting paradoxes of sustainability education and integrate the lessons they hold. All three approaches of the dissertation maintain a vision of sustainability education that incorporates contemplative practices as essential methods in a field in need of cultivating hope, resilience, and emergence.
ContributorsPapenfuss, Jason (Author) / Merritt, Eileen (Thesis advisor) / Manuel-Navarrete, David (Thesis advisor) / Eckard, Bonnie (Committee member) / Cloutier, Scott (Committee member) / Arizona State University (Publisher)
Created2019
Description
Aboveground net primary production (ANPP) is an important ecosystem process that, in drylands, is most frequently limited by water availability. Water availability for plants is in part controlled by the water holding capacity of soils. Available water holding capacity (AWHC) of soils is strongly influenced by soil texture and depth. This study drew upon localized rain gauge data and four data-sets of cover-line and biomass data to estimate ANPP and to determine annual precipitation (PPT). I measured soil depth to caliche and texture by layer of 112 plots across the four landscape units for which estimation of ANPP were available. A pedotransfer function was used to estimate AWHC from soil depth increments to depth of caliche measurements and texture analysis. These data were analyzed using simple and multivariate regression to test the effect of annual precipitation and available water holding capacity on aboveground net primary production. Soil texture remained constant among all plots (sandy loam) and depth to caliche varied from 15.16 cm to 189 cm. AWHC and the interaction term (PPT*AWHC) were insignificant (p=0.142, p=0.838) and annual PPT accounted for 18.4% of the variation in ANPP. The y-intercept was significantly different for ANPP ~ annual PPT when considering AWHC values either above or below 3 cm. Shrub ANPP was insensitive to precipitation regardless of AWHC (R2=-0.012, R2=0.014). Results from this study indicate that a model incorporating annual PPT and AWHC may not serve as a good predictor for ANPP at a site level where there is little variation in soil texture.
ContributorsWagner, Svenja K (Author) / Sala, Osvaldo E. (Thesis advisor) / Cease, Arianne (Committee member) / Hall, Sharon (Committee member) / Peters, Debra (Committee member) / Arizona State University (Publisher)
Created2019
Description
The United Nations projects that 68% of the world population will live in urban areas by 2050. As urban areas continue to grow, it is critical to consider how cities will be redesigned and reimagined to ensure that they are healthy and beneficial places that can properly support their residents. In addition, college students have been identified as a vulnerable population in regards to overall wellness. In Downtown Phoenix, one the biggest elements of concern will be the built environment and its influence on wellbeing as the city itself and Arizona State University’s Downtown campus populations continue to expand. Given this, the purpose of this study is two-fold. I applied Social-Cognitive Theory as a framework to first, understand student perceptions of the built and social environment and second, explore how perceptions of the built and social environment influence student wellbeing. I used semi-structured interviews and participant-driven photo elicitation to answer these questions. The study took place at Taylor Place Mall on Arizona State University’s Downtown Campus and participants were students who attend classes on the ASU Downtown Campus. Findings displayed the need for design considerations to focus on the safety of students, creating places to gather for social connection, and overall a desire for design to focus on place making and place meaning, as well as other themes. Understanding more clearly how the built and social environment guides behaviors and social opportunities can help urban designers, landscape architects, and community developers better plan healthier environments that foster productive behaviors, create meaningful spaces, and prove to be sustainable in future years.
ContributorsRood, Sydney Kirsten (Author) / Budruk, Megha (Thesis advisor) / Jordan, Evan (Committee member) / Cloutier, Scott (Committee member) / Arizona State University (Publisher)
Created2019
Description
Aquatic macroinvertebrates can be key contributors to nitrogen (N) and phosphorus (P) cycling in streams. Though they exhibit intense control via trophic interactions and nutrient conversion, they may be influenced by other environmental factors that can determine total excretion-derived N, P, and N:P. Garden Canyon and Ramsey Canyon, two streams in the Huachuca Mountain Range in Southern Arizona, USA, host similar insect communities, but only Garden Canyon experiences a seasonal P limitation due to the co-precipitation of phosphate with calcium carbonate (CaCO3) in its benthic substrate (Corman et al. 2015). I performed an analysis of excretion rates of aquatic insects living in these streams to test if the P limitation is reflected in rates that insects recycle nutrients. A lower mean N:P of all insect excretion rates in Garden provides evidence for an ecosystem-scale effect, though the differences in N:P of excretion rates by individual taxa between streams did not support the hypothesis. Attributing excretion rates to actual insect densities in three years reveals that natural-occurring fluctuations in excretion rates can operate on the same magnitude as fluctuations in abundances and causes steep differences in nutrient conversion between streams. Lastly, I found that since these streams support immense insect diversity, they receive excretion-derived N and P from taxa in many different functional feeding groups, which illustrates ecosystem resilience and uniqueness.
ContributorsSanders, Ashley Marie (Author) / Sabo, John (Thesis director) / Cease, Arianne (Committee member) / School of Life Sciences (Contributor) / Barrett, The Honors College (Contributor)
Created2016-05
Description
This proposal lays out the business case for Isagenix International to adopt circular packaging that is compatible with the circular economy. I first give a brief background on plastic packaging and the environmental risks that go along with it. After explaining how a linear economy is unsustainable, I introduce the concept of a circular economy. I then explain the competitive advantages that Isagenix can gain over its competitors from pursuing circular or sustainable packaging, and provide a benchmarking analysis of other companies’ sustainable packaging goals. After establishing the reasons that Isagenix should pursue this initiative, I go into an explanation of how Isagenix should design packaging for circularity and educate consumers on how to recycle their packaging products. Lastly, I propose my three recommendations for action that Isagenix should start with to begin transitioning all of their packaging to be circular.
ContributorsPatel, Tanvi (Author) / Dooley, Kevin (Thesis director) / Cloutier, Scott (Committee member) / Department of Supply Chain Management (Contributor) / School of Sustainability (Contributor) / Barrett, The Honors College (Contributor)
Created2019-05
Description
Locusts are a major crop pest in many parts of the world and different species are endemic to different countries. In Latin America, the South American Locust (Schistocerca cancellata) is the predominant species found mostly in Argentina, Chile, Bolivia, Paraguay, and southern Brazil with Argentina being the most affected. Several control and management practices, including biological control, have been implemented in these countries in the past to control the locusts and reduce their impact on crop and vegetation, however, effective long-term control and management practices will require a detail understanding of how the predominant locust species in this region responds to resource variation. Research has shown that there is strong evidence that locusts, and many other organisms, will actively balance dietary macronutrients (protein, carbohydrates, and lipids) to optimize growth, survival, and/or reproduction. A study by Cease et. al, 2017, on the dietary preferences of the Mongolian locust (Oedaleus asiaticus) showed that it prefers diets that are high in carbohydrates over diets that are high in protein, in this case locusts self-selected a 1:2 ratio of protein:carbohydrate. This and many other studies provide vital insight into the nutritional and feeding preferences of these locust species but the effects that this difference in protein: carbohydrate preferences has on growth, egg production, flight potential, and survival has yet to be fully explored, hence, this study investigates the effects that nitrogen fertilization of wheatgrass will have on the growth, egg production, survival, and flight muscle mass of the South American locust in a controlled, laboratory environment.
ContributorsManneh, Balanding (Author) / Cease, Arianne (Thesis director) / Overson, Rick (Committee member) / School of Sustainability (Contributor) / School of Life Sciences (Contributor) / Barrett, The Honors College (Contributor)
Created2018-05
Description
Modern American environmental social movements have strived for a better world for nearly fifty years, pushing a philosophy of careful resource use and limited consumption as an alternative to the pollution and degradation that has so far accompanied global industrialization. The reach of these movements is broad and the topic they cover is one that aligns with the values and beliefs of many; it is thus quite confusing that they've been so unsuccessful. This thesis was a response to that apparent contradiction, exploring why movements have not been as successful as both they and the public initially desired. It began by defining what social movements are and how they emerge or find success, then provided a brief history of environmentalism in America, and the different successes and failures that occurred before and after the first Earth day in 1970. Finally, it explored some of the reasons environmentalism was unsuccessful, and found that while structural barriers like politics and business interests played a role in movement outcomes, the tactics of different groups were at least partially to blame. Once this was concluded, the author used the perspectives of different activists to propose ways to enhance the quality of current movements and allow them to continue to make progress well into the future. In order to expand the audience of this thesis, the author is also working on a children;s book that illustrates many of the important themes that he hopes to convey to the public. Though drafted, the book is incomplete as of the date that documents are due for Barrett review.
ContributorsGuy, Joel D (Author) / Cloutier, Scott (Thesis director) / Josh, MacFayden (Committee member) / Department of English (Contributor) / School of Sustainability (Contributor) / School of Geographical Sciences and Urban Planning (Contributor) / Department of Management and Entrepreneurship (Contributor) / Barrett, The Honors College (Contributor)
Created2016-12