Matching Items (12)
Description
The relationship between biodiversity and ecosystem functioning (BEF) is a central issue in ecology, and a number of recent field experimental studies have greatly improved our understanding of this relationship. Spatial heterogeneity is a ubiquitous characterization of ecosystem processes, and has played a significant role in shaping BEF relationships. The first step towards understanding the effects of spatial heterogeneity on the BEF relationships is to quantify spatial heterogeneity characteristics of key variables of biodiversity and ecosystem functioning, and identify the spatial relationships among these variables. The goal of our research was to address the following research questions based on data collected in 2005 (corresponding to the year when the initial site background information was conducted) and in 2008 (corresponding to the year when removal treatments were conducted) from the Inner Mongolia Grassland Removal Experiment (IMGRE) located in northern China: 1) What are the spatial patterns of soil nutrients, plant biodiversity, and aboveground biomass in a natural grassland community of Inner Mongolia, China? How are they related spatially? and 2) How do removal treatments affect the spatial patterns of soil nutrients, plant biodiversity, and aboveground biomass? Is there any change for their spatial correlations after removal treatments? Our results showed that variables of biodiversity and ecosystem functioning in the natural grassland community would present different spatial patterns, and they would be spatially correlated to each other closely. Removal treatments had a significant effect on spatial structures and spatial correlations of variables, compared to those prior to the removal treatments. The differences in spatial pattern of plant and soil variables and their correlations before and after the biodiversity manipulation may not imply that the results from BEF experiments like IMGRE are invalid. However, they do suggest that the possible effects of spatial heterogeneity on the BEF relationships should be critically evaluated in future studies.
ContributorsYuan, Fei (Author) / Wu, Jianguo (Thesis advisor) / Smith, Andrew T. (Committee member) / Rowe, Helen I (Committee member) / Arizona State University (Publisher)
Created2011
Description
As much as 40% of the world's human population relies on rivers which originate on the Qinghai-Tibetan Plateau (QTP) (Xu et al. 2009, Immerzeel et al. 2010). However, the high alpine grasslands where these rivers emanate are at a crossroads. Fed by seasonal monsoon rains and glacial runoff, these rivers' frequent flooding contributes to massive losses of life and property downstream (Varis et al. 2012). Additionally, upstream grasslands, which regulate the flow of these rivers, are considered to be deteriorating (Harris 2010). This thesis examines the regional vulnerability of these rivers and highlights the impacts of several policy responses, finding that both climate change and grassland degradation pose significant challenges to Asia's water security. Additionally, I suggest that many of the responses elicited by policy makers to meet these challenges have failed. One of these policies has been the poisoning of a small, endemic, burrowing mammal and keystone species, the plateau pika (Ochotona curzoniae) (Smith and Foggin 1999). Contrary to their putative classification as a pest (Fan et al. 1999), I show that the plateau pika is instead an ecosystem engineer that actively increases the infiltration rate of water on the QTP with concomitant benefits to both local ecosystems and downstream hydrological processes.
ContributorsWilson, Maxwell (Author) / Smith, Andrew T. (Thesis advisor) / Wu, Jiangou (Committee member) / Hall, Sharon J. (Committee member) / Arizona State University (Publisher)
Created2012
Description
The purpose of my thesis is to illustrate the story of the black-footed ferret's conservation, and to provide my own suggestions for how to eventually get the species removed from the Endangered Species List, marking a successful rebound in population numbers. I highlight my personal experience working at the Phoenix Zoo's black-footed ferret breeding center. In the first chapter, I present the species by describing its morphology, diet, reproduction, behaviors, range, and habitat. In the second chapter, I recount the chronological history of the conservation of the species, starting with its rediscovery following its putative "extinction", and ending with its present status. In the third chapter, I discuss the threats that have led to the species' overall decline and continue to affect its persistence today. In the fourth and final chapter, I conclude by making recommendations regarding what needs to occur in order to eventually get the species delisted.
ContributorsGeer, Emily Maren (Author) / Smith, Andrew T. (Thesis director) / Minteer, Ben (Committee member) / Wells, Stuart (Committee member) / Barrett, The Honors College (Contributor) / School of Life Sciences (Contributor)
Created2014-05
Description
China’s South–North Water Transfer Project (SNWTP) has the potential to transfer as much as 44.8 km3 year-1 of water from the Yangtze River basin to the Yellow River basin. However, the SNWTP has not been assessed from a sustainability perspective. Thus, in this study we evaluated the SNWTP’s economic, social, and environmental impacts by reviewing the English literature published in journals that are part of the Web of Science database. We then synthesized this literature using a Triple Bottom Line framework of sustainability assessment. Our study has led to three main findings: (1) whether the SNWTP is economically beneficial depends largely on model assumptions, meaning that economic gains at the regional and national level are uncertain; (2) the SNWTP requires the resettlement of hundreds of thousands of people and challenges existing water management institutions, suggesting possible social concerns beyond the short term; and (3) evidently large environmental costs in water-providing areas and uncertain environmental benefits in water-receiving areas together point to an uncertain environmental future for the geographic regions involved. Thus, the overall sustainability of SNWTP is seriously questionable. Although much work has been done studying individual aspects of SNWTP’s sustainability, few studies have utilized the multi-scale, transdisciplinary approaches that such a project demands. To minimize environmental risks, ensure social equity, and sustain economic benefits, we suggest that the project be continuously monitored in all three dimensions, and that integrated sustainability assessments and policy improvements be carried out periodically.
ContributorsWilson, Maxwell (Author) / Li, Xiao-Yan (Author) / Ma, Yu-Jun (Author) / Smith, Andrew (Author) / Wu, Jianguo (Author) / College of Liberal Arts and Sciences (Contributor)
Created2017-08-22
Description
The highly-social plateau pika (Lagomorpha: Ochotona curzoniae) excavates vast burrow complexes in alpine meadows on the Tibetan Plateau. Colonies of over 300 individuals/ha have been reported. As an ecosystem engineer, their burrowing may positively impact ecosystem health by increasing plant species diversity, enhancing soil mixing, and boosting water infiltration. However, pikas are commonly regarded as pests, and are heavily poisoned throughout their range. The underlying assumption of eradication programs is that eliminating pikas will improve rangeland quality and decrease soil erosion. This dissertation explores the link between plateau pikas and the alpine meadow ecosystem in Qinghai Province, PRC. This research uses both comparative field studies and theoretical modeling to clarify the role of pika disturbance. Specifically, these studies quantify the impact of pikas on nutrient cycling (via nutrient concentrations of vegetation and soil), hydrology (via water infiltration), local landscape properties (via spatial pattern description), and vascular plant communities (via species richness and composition). The competitive relationship between livestock and pikas is examined with a mathematical model. Results of this research indicate that pika colonies have both local and community level effects on water infiltration and plant species richness. A major contribution of pika disturbance is increased spatial heterogeneity, which likely underlies differences in the plant community. These findings suggest that the positive impact of plateau pikas on rangeland resources has been undervalued. In concurrence with other studies, this work concludes that plateau pikas provide valuable ecosystem services on the Tibetan Plateau.
ContributorsHogan, Brigitte Wieshofer (Author) / Smith, Andrew T. (Thesis advisor) / Anderies, J. Marty (Committee member) / Briggs, John M. (Committee member) / Stromberg, Juliet C. (Committee member) / Wu, Jianguo (Committee member) / Arizona State University (Publisher)
Created2010
Description
Epidemiological theory normally does not predict host extinction from infectious disease because of a host density threshold below which pathogens cannot persist. However, host extinction can occur when a biotic or abiotic pathogen reservoir allows for density-independent transmission. Amphibians are facing global population decline and extinction from the emerging infectious disease chytridiomycosis, caused by the fungus Batrachochytrium dentrobatidis (Bd). I use the model species Eleutherodactylus coqui to assess the impact of Bd on terrestrial direct-developing frog species, a common life history in the tropics. I tested the importance of two key factors that might influence this impact and then used laboratory experiments and published field data to model population-level impacts of Bd on E. coqui. First, I assessed the ontogenetic susceptibility of E. coqui by exposing juvenile and adult frogs to the same pathogen strain and dose. Juveniles exposed to Bd had significantly lower survival rates compared with control juveniles, while adult frogs often cleared infection. Second, I conducted experiments to determine whether E. coqui can become infected with Bd indirectly from contact with zoospores shed onto vegetation by an infected frog and from direct exposure to an infected frog. Both types of transmission were observed, making this the first demonstration that amphibians can become infected indirectly in non-aquatic habitats. Third, I tested the hypothesis that artificially-maintained cultures of Bd attenuate in pathogenicity, an effect known for other fungal pathogens. Comparing two cultures of the same Bd strain with different passage histories revealed reduced zoospore production and disease-induced mortality rates for a susceptible frog species (Atelopus zeteki) but not for the less-susceptible E. coqui. Finally, I used a mathematical model to project the population-level impacts of chytridiomycosis on E. coqui. Model analysis showed that indirect transmission, combined with either a high rate of zoospore production or low rate of zoospore mortality, is required for Bd to drive E. coqui populations below an extinction threshold. High rates of transmission plus frequent re-infection could lead to poor recruitment of infected juveniles and population decline. My research adds further insight into how emerging infectious disease is contributing to the loss of amphibian biodiversity.
ContributorsLanghammer, Penny F. (Author) / Collins, James P. (Thesis advisor) / Brooks, Thomas M (Committee member) / Burrowes, Patricia A. (Committee member) / Anderies, John M (Committee member) / Escalante, Ananias A (Committee member) / Smith, Andrew T. (Committee member) / Arizona State University (Publisher)
Created2013
Description
The Great Bustard (Otis tarda) is an iconic species of the temperate grasslands of Europe and Asia, a habitat that is among the least protected ecosystems in the world. A distinct subspecies, the Asian Great Bustard (O. t. dybowskii), is poorly understood due to its wary nature and remote range in Siberia, Mongolia, and northern China. This subspecies is now endangered by rapid development.
Using satellite telemetry and remote sensing, I investigated three aspects of the Asian Great Bustard’s ecology critical to its conservation: migratory routes, migratory cues, and habitat use patterns. I found that Asian Great Bustards spent one-third of the year on a 2000 km migratory pathway, a distance twice as far as has previously been recorded for the species. Tracked individuals moved nomadically over large winter territories and did not repeat migratory stopovers, complicating conservation planning. Migratory timing was variable and migratory movements were significantly correlated with weather cues. Specifically, bustards migrated on days when wind support was favorable and temperature presaged warmer temperatures on the breeding grounds (spring) or advancing winter weather (fall). On the breeding grounds, Asian Great Bustards used both steppe and wheat agriculture habitat. All recorded reproductive attempts failed, regardless of habitat in which the nest was placed. Agricultural practices are likely to intensify in the coming decade, which would present further challenges to reproduction. The distinct migratory behavior and habitat use patterns of the Asian Great Bustard are likely adaptations to the climate and ecology of Inner Asia and underscore the importance of conserving these unique populations.
My research indicates that conservation of the Asian Great Bustard will require a landscape-level approach. This approach should incorporate measures at the breeding grounds to raise reproductive success, alongside actions on the migratory pathway to ensure appropriate habitat and reduce adult mortality. To secure international cooperation, I proposed that an increased level of protection should be directed toward the Great Bustard under the Convention on Migratory Species (CMS). That proposal, accepted by the Eleventh Conference of Parties to CMS, provides recommendations for conservation action and illustrates the transdisciplinary approach I have taken in this research.
Using satellite telemetry and remote sensing, I investigated three aspects of the Asian Great Bustard’s ecology critical to its conservation: migratory routes, migratory cues, and habitat use patterns. I found that Asian Great Bustards spent one-third of the year on a 2000 km migratory pathway, a distance twice as far as has previously been recorded for the species. Tracked individuals moved nomadically over large winter territories and did not repeat migratory stopovers, complicating conservation planning. Migratory timing was variable and migratory movements were significantly correlated with weather cues. Specifically, bustards migrated on days when wind support was favorable and temperature presaged warmer temperatures on the breeding grounds (spring) or advancing winter weather (fall). On the breeding grounds, Asian Great Bustards used both steppe and wheat agriculture habitat. All recorded reproductive attempts failed, regardless of habitat in which the nest was placed. Agricultural practices are likely to intensify in the coming decade, which would present further challenges to reproduction. The distinct migratory behavior and habitat use patterns of the Asian Great Bustard are likely adaptations to the climate and ecology of Inner Asia and underscore the importance of conserving these unique populations.
My research indicates that conservation of the Asian Great Bustard will require a landscape-level approach. This approach should incorporate measures at the breeding grounds to raise reproductive success, alongside actions on the migratory pathway to ensure appropriate habitat and reduce adult mortality. To secure international cooperation, I proposed that an increased level of protection should be directed toward the Great Bustard under the Convention on Migratory Species (CMS). That proposal, accepted by the Eleventh Conference of Parties to CMS, provides recommendations for conservation action and illustrates the transdisciplinary approach I have taken in this research.
ContributorsKessler, Aimee (Author) / Smith, Andrew T. (Thesis advisor) / Brown, David (Committee member) / Franklin, Janet (Committee member) / McGraw, Kevin (Committee member) / Wu, Jianguo (Committee member) / Arizona State University (Publisher)
Created2015
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
Balancing conservation goals and needs of local residents is always challenging. While some believe protected areas are a safe paradise for wildlife, others suggest that it is shortsighted to ignore the social and economic challenges faced by people who live adjacent to protected areas when addressing conservation objectives. This dissertation explores the link between biodiversity conservation and environmental education programs (EEPs) administered to residents of buffer zones adjacent to three protected areas in the Terai Arc Landscape, Nepal. Using surveys and interviews, this study examined 1) the influence of EEPs on attitudes of local people toward biodiversity conservation; 2) the influence of EEPs on conservation behavior; 3) the responses toward biodiversity conservation of local people residing in buffer zones who have received different levels of EEPs; and 4) the effect of EEPs on wildlife populations within adjacent protected areas. Local people who had participated in EEPs and attended school were more likely to express a positive attitude toward conservation goals than participants who had not participated in EEPs or had the opportunity to attend school. Participation in EEPs and level of education favored expressed behavior toward conservation goals, such as making contributions for conservation or supporting anti-poaching patrols. However, EEP participants and non-participants were equally likely to engage in activities that were at odds with positive conservation behavior, such as collecting fuel wood or killing wildlife to protect their farm or feed their families. A direct comparison of EEPs given by schools versus non-government organizations showed that EEPs were largely ineffective in promoting positive conservation attitudes and behaviors. Despite heavy poaching of charismatic species such as the greater one-horned rhinoceros or tiger over past decades, Nepal recently celebrated ‘zero poaching years’ in 2011 and 2013, largely due to increased anti-poaching enforcement. The relationship between EEPs and the decline in poaching is unclear, although local officials all claimed that EEPs played an important role. These results indicate that current administration of EEPs in Terai buffer zone communities is inadequate, while also providing evidence that properly administrated EEPs may become a valuable investment for these protected areas to achieve long-term success.
ContributorsShrestha, Samridhi (Author) / Smith, Andrew T. (Thesis advisor) / Minteer, Ben (Committee member) / Pearson, David (Committee member) / Nyaupane, Gyan (Committee member) / Budruk, Megha (Committee member) / Arizona State University (Publisher)
Created2015
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