Matching Items (20)
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- All Subjects: Ecology
- Creators: Wu, Jianguo
- Creators: Bateman, Heather
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
Over the past century in the southwestern United States human actions have altered hydrological processes that shape riparian ecosystems. One change, release of treated wastewater into waterways, has created perennial base flows and increased nutrient availability in ephemeral or intermittent channels. While there are benefits to utilizing treated wastewater for environmental flows, there are numerous unresolved ecohydrological issues regarding the efficacy of effluent to sustain groundwater-dependent riparian ecosystems. This research examined how nutrient-rich effluent, released into waterways with varying depths to groundwater, influences riparian plant community development. Statewide analysis of spatial and temporal patterns of effluent generation and release revealed that hydrogeomorphic setting significantly influences downstream riparian response. Approximately 70% of effluent released is into deep groundwater systems, which produced the lowest riparian development. A greenhouse study assessed how varying concentrations of nitrogen and phosphorus, emulating levels in effluent, influenced plant community response. With increasing nitrogen concentrations, vegetation emerging from riparian seed banks had greater biomass, reduced species richness, and greater abundance of nitrophilic species. The effluent-dominated Santa Cruz River in southern Arizona, with a shallow groundwater upper reach and deep groundwater lower reach, served as a study river while the San Pedro River provided a control. Analysis revealed that woody species richness and composition were similar between the two systems. Hydric pioneers (Populus fremontii, Salix gooddingii) were dominant at perennial sites on both rivers. Nitrophilic species (Conium maculatum, Polygonum lapathifolium) dominated herbaceous plant communities and plant heights were greatest in effluent-dominated reaches. Riparian vegetation declined with increasing downstream distance in the upper Santa Cruz, while patterns in the lower Santa Cruz were confounded by additional downstream agricultural input and a channelized floodplain. There were distinct longitudinal and lateral shifts toward more xeric species with increasing downstream distance and increasing lateral distance from the low-flow channel. Patterns in the upper and lower Santa Cruz reaches indicate that water availability drives riparian vegetation outcomes below treatment facilities. Ultimately, this research informs decision processes and increases adaptive capacity for water resources policy and management through the integration of ecological data in decision frameworks regarding the release of effluent for environmental flows.
ContributorsWhite, Margaret Susan (Author) / Stromberg, Juliet C. (Thesis advisor) / Fisher, Stuart G. (Committee member) / White, Dave (Committee member) / Holway, James (Committee member) / Wu, Jianguo (Committee member) / Arizona State University (Publisher)
Created2011
Description
Human recreation on rangelands may negatively impact wildlife populations. Among those activities, off-road vehicle (ORV) recreation carries the potential for broad ecological consequences. A study was undertaken to assess the impacts of ORV on rodents in Arizona Uplands Sonoran Desert. Between the months of February and September 2010, rodents were trapped at 6 ORV and 6 non-ORV sites in Tonto National Forest, AZ. I hypothesized that rodent abundance and species richness are negatively affected by ORV use. Rodent abundances were estimated using capture-mark-recapture methodology. Species richness was not correlated with ORV use. Although abundance of Peromyscus eremicus and Neotoma albigula declined as ORV use increased, abundance of Dipodomys merriami increased. Abundance of Chaetodipus baileyi was not correlated with ORV use. Other factors measured were percent ground cover, percent shrub cover, and species-specific shrub cover percentages. Total shrub cover, Opuntia spp., and Parkinsonia microphylla each decreased as ORV use increased. Results suggest that ORV use negatively affects rodent habitats in Arizona Uplands Sonoran Desert, leading to declining abundance in some species. Management strategies should mitigate ORV related habitat destruction to protect vulnerable populations.
ContributorsReid, John Simon (Author) / Brady, Ward (Thesis advisor) / Miller, William (Committee member) / Bateman, Heather (Committee member) / Arizona State University (Publisher)
Created2012
Description
The effects of biocontrol and the potential risks associated with them are of interest to many researchers. In the Virgin River area of Nevada, natural resource managers have done studies of various removal techniques on the non-native Tamarix spp. strands. One such area of focus is the use of biocontrol in the form of the tamarisk leaf beetle (Diorhabda spp.), and the resulting changes in the environment from the defoliation of the trees. Previous studies have shown that removal of the plants can potentially be beneficial to lizards. But do changes in the environment change the amount of food available? We were interested to see if the amount of arthropod biomass from these areas had a relationship with the lizard abundance. Taking arthropod collection data from the Virgin River, we compared it with arthropod data over several years, before and after Diorhabda was introduced in 2010. Arthropod biomass data was obtained by taking the collected arthropods and drying them in an oven and weighing them. Results show that there is no correlation between the arthropod numbers or biomass with the amount of lizards in the area, that biomass was greatest after biocontrol introduction, and biomass was highest in mixed Tamarix and native tree strands versus just Tamarix strands. In conclusion, arthropod numbers and biomass have shown to be a poor indicator of lizard abundance, and factors such as temperature changes in the environment might be a better indicator of the changing abundance of lizards.
ContributorsPicciano, Melanie Erin (Author) / Bateman, Heather (Thesis director) / Barnard, James (Committee member) / Barrett, The Honors College (Contributor) / School of Letters and Sciences (Contributor)
Created2014-05
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
My thesis/creative project is a series of videos, supplemented by a paper documenting all the research. The project focuses on domestic and feral cats through the viewpoint of the “warrior cats” book series. The use of a particular fandom as a vehicle for science communication is a unique platform for use as a thesis/creative project. The narrated videos are made with the intention of being presented on YouTube or a similar viewing platform to an audience that is already familiar with the book series. The videos would fit on the site as a form of educational film known as video essays. The videos cover a range of topics to relate this book series to real situations with domestic animals, particularly cats, and wildlife. Each video is around ten to twenty minutes long and presented as episodes in a series.
The objective of my thesis project is to help bridge the gap between entertainment and science. I grew up reading the warrior cats, and I assume I was similar to many other children and young teens who did not understand domestic cats or ecology enough to question anything in the books. I know that much of these books are fictional, but that does not mean that it can’t be analyzed and used as a tool for teaching. The goal is to reach common ground with those people who have an interest in the warrior cats series, and help them understand it in a new light, as well as the world around them. I aim for the takeaway of this series to encourage people to explore the concepts I discuss and consider expanding upon the ideas within the Warriors universe or with their own cats.
The objective of my thesis project is to help bridge the gap between entertainment and science. I grew up reading the warrior cats, and I assume I was similar to many other children and young teens who did not understand domestic cats or ecology enough to question anything in the books. I know that much of these books are fictional, but that does not mean that it can’t be analyzed and used as a tool for teaching. The goal is to reach common ground with those people who have an interest in the warrior cats series, and help them understand it in a new light, as well as the world around them. I aim for the takeaway of this series to encourage people to explore the concepts I discuss and consider expanding upon the ideas within the Warriors universe or with their own cats.
ContributorsGarcia, Johnny Nico (Author) / Bateman, Heather (Thesis director) / Meloy, Elizabeth (Committee member) / College of Integrative Sciences and Arts (Contributor, Contributor) / School of Art (Contributor) / Barrett, The Honors College (Contributor)
Created2020-05
Description
As white-nose syndrome (WNS) spreads across North America, generating baseline data on bats hibernating outside of the affected area is critical. To illustrate, despite the imminent arrival of Pseudogymnoascus destructans (Pd) to Arizona (AZ), little is known about bat hibernation in the Southwest. With the current amount of information, if Pd spreads throughout the state, detection of cases would be limited, and severity of disease and magnitude of mortality impossible to accurately estimate. Thus, my study monitored hibernating bats in AZ to increase knowledge and investigate potential WNS impacts on these populations. Utilizing passive acoustic monitoring, internal cave surveys, environmental monitoring, and thermal imaging, my study quantified microclimate preferences, hibernation lengths, hibernation behaviors, population dynamics, and species compositions of bats hibernating in three north-central AZ caves. Hibernation lasted between 104 and 162 days, from late October through mid- March, during which time bats (primarily Corynorhinus townsendii and Myotis species) roosted at locations with an average of 4.7oC (range = -0.2oC – 12.1oC), 59.6% relative humidity (range = 39.6% - 75.9%), and 0.4 kPa water vapor pressure deficit (range = 0.2 kPa – 0.8 kPa). A maximum of 40 individuals were observed in any hibernacula and clustering behavior occurred in only 4.1% of torpid bats. Bats selected cold and dry roost sites within caves. Results suggest Pd could proliferate on some bats hibernating in colder areas of AZ hibernacula, yet the range of observed roost humidities was lower than optimal for Pd growth. Hibernation length in north-central AZ is longer than predicted for Myotis species at similar latitudes and may be long enough to pose over- winter survival risks if WNS emerges in AZ populations. Yet, a natural tendency for mid-winter activity, which I observed by multiple species, may allow for foraging opportunities and water replenishment, and therefore promote survival in bats utilizing these arid and cold habitats in winter. Additionally, the relatively solitary behaviors I observed, including virtually no clustering activity and a maximum of 40 bats per hibernacula, may keep rates of Pd transmission low in these Southwest bat populations.
ContributorsHutcherson, Hayden K (Author) / Bateman, Heather (Thesis advisor) / Moore, Marianne (Committee member) / Lewis, Jesse (Committee member) / Arizona State University (Publisher)
Created2023
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
Urban wetland ecosystems provide myriad ecosystem services and are shaped by diverse social and ecological factors. In rapidly urbanizing parts of the desert Southwest, wetlands are especially vital. Across less than 60 km as it enters the Phoenix area, the Salt River is dammed, diverted, re-filled, clear-cut, restored, and ignored. This study documents how animal and plant communities in three perennially inundated reaches of the river changed over a decade under different social-ecological pressures. One wetland in the urban core is restored, another formed accidentally by human infrastructure, and the last is managed on the urban periphery. Surveys conducted since 2012 used point-count surveys to assess bird communities and visual encounter surveys to assess reptiles and amphibians. Plant communities were surveyed in 2012 and 2022 using cover classes. Between 2012 and 2022, accidental and restored wetlands close to the urban core displayed an increase in plant abundance, largely consisting of introduced species. While all sites saw an increase in plant species considered invasive by land management groups, both urban wetlands saw an increase in regionally native species, including plants that are culturally significant to local Indigenous groups. Reptile communities declined in richness and abundance in both urban sites, but birds grew in abundance and richness at the urban restored site while not changing at the urban accidental wetland. The non-urban site saw stable populations of both birds and herpetofauna. These trends in biotic communities reveal ecological tradeoffs under different management strategies for urban wetlands. These findings also create a portrait of wetland communities along a rapidly urbanizing arid river. As the Salt River watershed becomes more urbanized, it is important to establish a more empathetic and informed relationship between its plant and animal—including human—residents. To this end, these data were incorporated in a series of handmade paper artworks, crafted from the most abundant wetland plant species found at the study sites, harvested alongside local land management efforts. These artworks examine the potential of four common cosmopolitan wetland plants for papermaking, revealing the potential to align ecosystem management efforts with both materials production and fine arts. By using relief printmaking to visualize long-term ecological data, I explored an alternative, more creative and embodied way to engage with and visualize urban wetland communities. This alternate mode of engagement can complement ecological management and research to diversify disciplines and participants engaged with understanding and living alongside urban wetlands.
ContributorsRamsey-Wiegmann, Luke Dawson (Author) / Childers, Daniel L (Thesis advisor) / Makings, Elizabeth (Committee member) / Bateman, Heather (Committee member) / Arizona State University (Publisher)
Created2023
Description
Terrestrial ecosystems are critical to human welfare and regulating Earth’s life support systems but many gaps in our knowledge remain regarding how terrestrial plant communities respond to changes in climate or human actions. I used field experiments distributed across three dryland ecosystems in North America to evaluate the consequences of changing precipitation and physical disturbance on plant community structure and function. Evidence from experiments and observational work exploring both plant community composition and ecological processes suggest that physical disturbance and precipitation reductions can reduce the diversity and function of these dryland ecosystems. Specifically, I found that aboveground net primary productivity could be reduced in an interactive manner when precipitation reductions and physical disturbance co-occur, and that within sites, this reduction in productivity was greater when growing-season precipitation was low. Further, I found that these dryland plant communities, commonly dominated by highly drought-resistant shrubs and perennial grasses, were not capable of compensating for the absence of these dominant shrubs and perennial grasses when they were removed by disturbance, and that precipitation reductions (as predicted to occur from anthropogenic climate change) exacerbate these gaps. Collectively, the results of the field experiment suggest that current management paradigms of maintaining cover and structure of native perennial plants in dryland systems are well founded and may be especially important as climate variability increases over time. Evaluating how these best management practices take place in the real world is an important extension of fundamental ecological research. To address the research-management gap in the context of dryland ecosystems in the western US, I used a set of environmental management plans and remotely sensed data to investigate how ecosystem services in drylands are accounted for, both as a supply from the land base and as a demand from stakeholders. Focusing on a less-investigated land base in the United States–areas owned and managed by the Department of Defense–I explored how ecosystem services are produced by this unique land management arrangement even if they are not explicitly managed for under current management schemes. My findings support a growing body of evidence that Department of Defense lands represent a valuable conservation opportunity, both for biodiversity and ecosystem services, if management regimes fully integrate the ecosystem services concept.
ContributorsJordan, Samuel (Author) / Grimm, Nancy (Thesis advisor) / Reed, Sasha (Committee member) / Wu, Jianguo (Committee member) / Throop, Heather (Committee member) / Arizona State University (Publisher)
Created2024