Matching Items (8)
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- All Subjects: Urbanization
- Creators: School of Mathematical and Natural Sciences
- Creators: Wu, Jianguo
Description
Desert ecosystems are one of the fastest urbanizing areas on the planet. This rapid shift has the potential to alter the abundances and species richness of herbivore and plant communities. Herbivores, for example, are expected to be more abundant in urban desert remnant parks located within cities due to anthropogenic activities that concentrate food resources and reduce native predator populations. Despite this assumption, previous research conducted around Phoenix has shown that top-down herbivory led to equally reduced plant biomass. It is unclear if this insignificant difference in herbivory at rural and urban sites is due to unaltered desert herbivore populations or altered activity levels that counteract abundance differences. Vertebrate herbivore populations were surveyed at four sites inside and four sites outside of the core of Phoenix during fall 2014 and spring 2015 in order to determine whether abundances and richness differ significantly between urban and rural sites. In order to survey species composition and abundance at these sites, 100 Sherman traps and 8 larger wire traps that are designed to attract and capture small vertebrates such as mice, rats, and squirrels, were set at each site for two consecutive trap nights. Results suggest that the commonly assumed effect of urbanization on herbivore abundances does not apply to small rodent herbivore populations in a desert city, as overall small rodent abundances were statistically similar regardless of location. Though a significant difference was not found for species richness, a significant difference between small rodent genera richness at these sites was observed.
ContributorsAlvarez Guevara, Jessica Noemi (Co-author) / Ball, Becky A. (Co-author, Thesis director) / Hall, Sharon J. (Co-author) / Bateman, Heather (Committee member) / School of Sustainability (Contributor) / School of Mathematical and Natural Sciences (Contributor) / Barrett, The Honors College (Contributor)
Created2016-05
Description
In recent years, ecologists have begun to study the effects of urbanization on species diversity. While urban areas generally suffer decreased biodiversity, some species, termed “urban exploiters”, not only live in the city but depend on urban resources to thrive. It is hypothesized that urban exploiters may succeed in part due to phenotypic plasticity, in which organisms rapidly adjust their physiology or behavior to adapt to novel environmental contexts. In the city, it may be adaptive to display thermal plasticity, as the urban heat island effect caused by concrete and asphalt infrastructure prevents cooling at night. In this study, we observed the decorated cricket Gryllodes sigillatus, an invasive urban exploiter found in metropolitan Phoenix, in two separate experiments. We hypothesized that heat tolerance and activity are both plastic traits in this species. In Experiment 1, we predicted that knock-down time, a measure of heat tolerance, would be negatively affected by acclimation to a laboratory environment. Our results suggest that heat tolerance is affected by recent thermal regimes and that laboratory acclimation decreases knock-down time. In Experiment 2, we predicted that activity would increase with temperature until a point of extreme heat, at which point activity would decline. Statistical analysis for the second experiment reveals that activity decreases at 33°C, a natural urban extreme. This suggests either that 33°C is a thermal limit to physiology or that G. sigillatus is able to alter its behavior to exploit local thermal heterogeneity.
ContributorsVannan, Annika (Author) / Johnson, James Chadwick (Thesis director) / Angilletta, Michael (Committee member) / Barrett, The Honors College (Contributor) / School of Mathematical and Natural Sciences (Contributor) / School of Social and Behavioral Sciences (Contributor)
Created2015-05
Description
The spread of urbanization leads to habitat fragmentation and deterioration and changes the composition of ecosystems for species all over the world. Different groups of organisms are impacted differently, and insects have experienced loss in diversity and abundance due to changing environmental factors. Here, I collected seed beetles across 12 urban and rural sites in Phoenix, Arizona, to analyze the effects of urbanization and habitat variation on beetle diversity and abundance. I found that urbanization, host tree origin, and environmental factors such as tree diversity and density had no impact on overall beetle diversity and abundance. Beetles were found to have higher density on hosts with a higher density of pods. In assessing individual beetle species, some beetles exhibited higher density in rural sites with native trees, and some were found more commonly on nonnative tree species. The observed differences in beetle density demonstrate the range of effects urbanization and environmental features can have on insect species. By studying ecosystem interactions alongside changing environments, we can better predict the role urbanization and human development can have on different organisms.
ContributorsPaduano, Gabrielle (Author) / Savalli, Udo (Thesis director) / Sweat, Ken (Committee member) / Division of Teacher Preparation (Contributor) / School of Mathematical and Natural Sciences (Contributor) / Barrett, The Honors College (Contributor)
Created2018-05
Description
Context – Urbanization can have negative effects on bat habitat use through the loss and isolation of habitat even for volant bats. Yet, how bats respond to the changing landscape composition and configuration of urban environments remains poorly understood.
Objective – This study examines the relationship between bat habitat use and landscape pattern across multiple scales in the Phoenix metropolitan region. My research explores how landscape composition and configuration affects bat activity, foraging activity, and species richness (response variables), and the distinct habitats that they use.
Methods – I used a multi-scale landscape approach and acoustic monitoring data to create predictive models that identified the key predictor variables across multiple scales within the study area. I selected three scales with the intent of capturing the landscape, home range, and site scales, which may all be relevant for understanding bat habitat use.
Results – Overall, class-level metrics and configuration metrics best explained bat habitat use for bat species associated with this urban setting. The extent and extensiveness of water (corresponding to small water bodies and watercourses) were the most important predictor variables across all response variables. Bat activity was predicted to be high in native vegetation remnants, and low in native vegetation at the city periphery. Foraging activity was predicted to be high in fine-scale land cover heterogeneity. Species richness was predicted to be high in golf courses, and low in commercial areas. Bat habitat use was affected by urban landscape pattern mainly at the landscape and site scale.
Conclusions – My results suggested in hot arid urban landscapes water is a limiting factor for bats, even in urban landscapes where the availability of water may be greater than in outlying native desert habitat. Golf courses had the highest species richness, and included the detection of the uncommon pocketed free-tailed bat (Nyctinomops femorosaccus). Water cover types had the second highest species richness. Golf courses may serve as important stop-overs or refuges for rare or elusive bats. Urban waterways and golf courses are novel urban cover types that can serve as compliments to urban preserves, and other green spaces for bat conservation.
Objective – This study examines the relationship between bat habitat use and landscape pattern across multiple scales in the Phoenix metropolitan region. My research explores how landscape composition and configuration affects bat activity, foraging activity, and species richness (response variables), and the distinct habitats that they use.
Methods – I used a multi-scale landscape approach and acoustic monitoring data to create predictive models that identified the key predictor variables across multiple scales within the study area. I selected three scales with the intent of capturing the landscape, home range, and site scales, which may all be relevant for understanding bat habitat use.
Results – Overall, class-level metrics and configuration metrics best explained bat habitat use for bat species associated with this urban setting. The extent and extensiveness of water (corresponding to small water bodies and watercourses) were the most important predictor variables across all response variables. Bat activity was predicted to be high in native vegetation remnants, and low in native vegetation at the city periphery. Foraging activity was predicted to be high in fine-scale land cover heterogeneity. Species richness was predicted to be high in golf courses, and low in commercial areas. Bat habitat use was affected by urban landscape pattern mainly at the landscape and site scale.
Conclusions – My results suggested in hot arid urban landscapes water is a limiting factor for bats, even in urban landscapes where the availability of water may be greater than in outlying native desert habitat. Golf courses had the highest species richness, and included the detection of the uncommon pocketed free-tailed bat (Nyctinomops femorosaccus). Water cover types had the second highest species richness. Golf courses may serve as important stop-overs or refuges for rare or elusive bats. Urban waterways and golf courses are novel urban cover types that can serve as compliments to urban preserves, and other green spaces for bat conservation.
ContributorsBazelman, Tracy C (Author) / Wu, Jianguo (Thesis advisor) / Chambers, Carol L. (Thesis advisor) / Smith, Andrew T. (Committee member) / Arizona State University (Publisher)
Created2016
Description
Urban Heat Island (UHI) is considered as one of the major problems in the 21st century posed to human beings as a result of urbanization and industrialization of human civilization. The large amount of heat generated from urban structures, as they consume and re-radiate solar radiations, and from the anthropogenic heat sources are the main causes of UHI. The two heat sources increase the temperatures of an urban area as compared to its surroundings, which is known as Urban Heat Island Intensity (UHII). The problem is even worse in cities or metropolises with large population and extensive economic activities. The estimated three billion people living in the urban areas in the world are directly exposed to the problem, which will be increased significantly in the near future. Due to the severity of the problem, vast research effort has been dedicated and a wide range of literature is available for the subject. The literature available in this area includes the latest research approaches, concepts, methodologies, latest investigation tools and mitigation measures. This study was carried out to review and summarize this research area through an investigation of the most important feature of UHI. It was concluded that the heat re-radiated by the urban structures plays the most important role which should be investigated in details to study urban heating especially the UHI. It was also concluded that the future research should be focused on design and planning parameters for reducing the effects of urban heat island and ultimately living in a better environment.
ContributorsRizwan, Ahmed Memon (Author) / Dennis, Leung Y.C. (Author) / Liu, Chunho (Author)
Created2007-09-27
Description
With a growing majority of humans living within cities and towns, urbanization is one of the most persistent drivers of change in global land use and challenges to sustainability and biodiversity conservation. The development of cities and towns can substantially shape local and regional environments in which wildlife communities persist. Although urbanization can negatively affect wildlife communities – through processes such as habitat fragmentation and non-native species introduction – cities can also provide resources to wildlife, such as through food, water, and space, creating potential opportunities for conservation. However, managing wildlife communities persisting in urbanizing landscapes requires better understanding of how urbanized landscapes influence the ability of wildlife to coexist with one another and with people at local and regional scales. In this dissertation, I addressed these research needs by evaluating the environmental and human factors driving dynamic wildlife community distributions and people’s attitudes towards wildlife. In my first two chapters,I used wildlife camera data collected from across the Phoenix Metropolitan Area, AZ to examine seasonal patterns of wildlife space use, species richness, and interspecific interactions across levels of urbanization with varying landscape characteristics, including plant productivity and spatial land use heterogeneity. Here I found that urbanization was a primary driver of wildlife community characteristics within the region, but that seasonal resource availability and landscape heterogeneity could have mediating influences that require further exploration. In my third chapter, I partnered
with wildlife researchers across North America to examine how relationships between urbanization and community composition vary among cities with distinct social-ecological characteristics, finding that effects of local urbanization were more negative in warmer, less vegetated, and more urbanized cities. In my fourth and final chapter, I explored the potential for human-wildlife coexistence by examining how various ideological, environmental, and sociodemographic factors influenced Phoenix area residents’ level of comfort living near different wildlife groups. Although I found that residents’ attitudes were primarily shaped by their relatively static wildlife values, comfort living near wildlife also depended on the characteristics of the neighboring environment, of the residents, and of the wildlife involved, indicating the potential for facilitating conditions for human-wildlife coexistence. Altogether, the findings of this dissertation suggest that the management of wildlife and their interactions with people within cities would benefit from more proactive and holistic consideration of the interacting environmental, wildlife, and human characteristics that influence the persistence of biodiversity within an increasingly urbanized world.
ContributorsHaight, Jeffrey Douglas (Author) / Hall, Sharon J (Thesis advisor) / Lewis, Jesse S (Thesis advisor) / Larson, Kelli L (Committee member) / Wu, Jianguo (Committee member) / Arizona State University (Publisher)
Created2023
Description
With increasing urbanization, organisms face a myriad of novel ecological challenges. While the eco-evolutionary dynamics of urbanization are currently receiving a great deal of attention, the effect of urban disturbance on the microbiome of urban organisms is relatively unstudied. Indeed, studies of the microbiome may illuminate the mechanisms by which some species thrive after urbanization (pest implications), while other species go locally extinct (biodiversity implications). We investigated the gut microbiome of the Western black widow spider (Latrodectus hesperus). L. hesperus is an ideal model system as they are a pest species of medical importance in urban ecosystems, often forming dense urban infestations relative to the sparse populations found in their native Sonoran Desert. To gain insight into the composition of the microbiome in L. hesperus and its potential function, we sampled 4 urban, 4 desert, and 2 laboratory-reared spiders, and high-throughput sequencing of the 16S rRNA V4 region was used to investigate the diversity of gut microbiota. Dominant bacterial phyla across all samples were Firmicutes, Proteobacteria, and Actinobacteria. While desert widows showed more gut microbial diversity than urban widows, the difference was not statistically significant. The relative abundance of taxonomic classes Blastocatellia, Acidobacteriia, and Thermoleophilia detected in desert spiders was especially higher than those in urban and laboratory-reared spiders. However, urban spiders had a higher relative abundance of taxonomic class Actinomycetia. Differences in widow gut microbiome diversity improves our understanding of how features unique to a habitat, like prey diversity and soil microbes, may be shaping their microbiome. Additionally, this work further highlights the impact urbanization has on biodiversity loss, which indirectly develops a new biomarker for differentiating between urban and desert black widow spiders based on their gut microbiome.
ContributorsAsrari, Hasti (Author) / Johnson, Chad (Thesis director) / Sandrin, Todd (Committee member) / Barrett, The Honors College (Contributor) / School of Mathematical and Natural Sciences (Contributor) / School of Life Sciences (Contributor)
Created2022-12
Description
The science community has made efforts for over a half century to address sustainable development, which gave birth to sustainability science at the turn of the twenty-first century. Along with the development of sustainability science during the past two decades, a landscape sustainability science (LSS) perspective has been emerging. As interests in LSS continue to grow rapidly, scholars are wondering what LSS is about and how LSS fits into sustainability science, while practitioners are asking how LSS actually contributes to sustainability in the real world. To help address these questions, this dissertation research aims to explore the currently underused problem-driven, diagnostic approach to enhancing landscape sustainability through an empirical example of urbanization-associated farmland loss (UAFL). Based mainly on multimethod analysis of bibliographic information, the dissertation explores conceptual issues such as how sustainability science differs from conventional sustainable development research, and how the past, present, and future research needs of LSS evolve. It also includes two empirical studies diagnosing the issue of urban expansion and the related food security concern in the context of China, and proposes a different problem framing for farmland preservation such that stakeholders can be more effectively mobilized. The most important findings are: (1) Sustainability science is not “old wine in a new bottle,” and in particular, is featured by its complex human-environment systems perspective and value-laden transdisciplinary perspective. (2) LSS has become a vibrant emerging field since 2004-2006 with over three-decade’s intellectual accumulation deeply rooted in landscape ecology, yet LSS has to further embrace the two featured perspectives of sustainability science and to conduct more problem-driven, diagnostic studies of concrete landscape-relevant sustainability concerns. (3) Farmland preservationists’ existing problem framing of UAFL is inappropriate for its invalid causal attribution (i.e., urban expansion is responsible for farmland loss; farmland loss is responsible for decreasing grain production; and decreasing grain production instead of increasing grain demand is responsible for grain self-insufficiency); the real problem with UAFL is social injustice due to collective action dilemma in preserving farmland for regional and global food sufficiency. The present research provides broad implications for landscape scientists, the sustainability research community, and UAFL stakeholders.
ContributorsZhou, Bingbing (Author) / Wu, Jianguo (Thesis advisor) / Aggarwal, Rimjhim (Committee member) / Anderies, John Marty (Committee member) / Janssen, Marcus Alexander (Committee member) / Turner II, Billie Lee (Committee member) / Arizona State University (Publisher)
Created2020