Life Sciences Commons^™

Wood Decomposition In A Warmer World, Emily Elizabeth Austin

Doctoral Dissertations

Climatic warming is altering species distributions and ecosystem functions across the globe. Wood is an important carbon pool and the fungal communities in wood are relatively simple compared to those in soil. These factors make decomposing wood an ideal system for exploring the influence of decomposer community on the response of decomposition to warming. My research has focused on the effects of warming wood decomposition rates and wood decomposing communities. Using field and lab- based manipulative experiments and field observations I explore the influence of tree species, wood decomposition stage, geography and warming on fungal community structure and activity. In …

Assessing Growth Response To Climate Controls In A Great Basin Artemisia Tridentata Plant Community, Lorenzo F. Apodaca

UNLV Theses, Dissertations, Professional Papers, and Capstones

An assessment of the growth response of key vegetative species to climatic variability is vital to identifying possible local impacts on ecosystems faced with imminent climate change. With current climate projections in Nevada predicting a shift to an even more arid climate with greater year-to-year variability, the imperative exists to identify the effects of specific climatic controls on plant growth and to research methods to assess large-scale vegetative changes, especially in more remote areas where readily available data sets may be lacking. This study utilized annual growth ring indices constructed from big sagebrush (Artemisia tridentatassp.tridentata) stems collected in Spring Valley, …

Soil Freezing Effects On A Grass-Dominated Old Field Ecosystem Under Current And Future Rates Of Atmospheric Nitrogen Deposition, Mat Vankoughnett

Electronic Thesis and Dissertation Repository

Climate change is expected to alter the intensity and dynamics of soil freezing as a result of increased air temperatures and reduced snow cover. Soil freezing can influence ecosystem nitrogen (N) cycling by damaging plants and soil microorganisms, but little is known about how soil freezing effects on ecosystem N cycling may combine or interact with increased atmospheric N deposition, which is also expected to exert a strong influence on terrestrial ecosystems in the coming decades. The objective of my thesis was to examine the combined and possibly the interactive effects of climate induced changes in soil freezing and N …

Thermal Adaptation Of Life History Traits In The Drosophila Melanogaster Group, Christopher James Austin

Electronic Thesis and Dissertation Repository

Thermal adaptation is typically detected by examining the tolerance to extreme temperatures in a few populations within a single life stage. However, the extent to which adaptation occurs among many different populations might depend on the tolerance of multiple life stages and the average temperature range that the population experiences. Here, I examined adaptation to local temperature conditions in four species of fruit flies, including a cosmopolitan species, Drosophila melanogaster, and three species with geographically small-sized ranges, D. nepalensis, D. sechellia, and D. mauritiana. The cosmopolitan species showed adaptation to native temperatures during the larval and adult …

Quantifying Crop Yield, Bioenergy Production And Greenhouse Gas Emissions From Cropland And Marginal Land Using A Model-Data Fusion Approach, Zhangcai Qin

Open Access Dissertations

Bioenergy is becoming increasingly attractive to many countries, but has sparked an intensive debate regarding energy, economy, society and environment. Biofuels provide alternative energy to conventional fossil fuels. However, the environmental impact of producing and using biofuel is a major concern to our society. This study is dedicated to quantifying and evaluating biofuel production and potential climate change mitigation due to potential large-scale bioenergy expansion in the conterminous United States, using model-data fusion approaches.

Biofuel made from conventional (e.g., maize (Zea mays L.)) and cellulosic crops (e.g., switchgrass (Panicum virgatum L.) and Miscanthus (Miscanthus × giganteus)) …

Evidence For 20th Century Climate Warming And Wetland Drying In The North American Prairie Pothole Region, Brett A. Werner, W. Carter Johnson, Glenn R. Guntenspergen

Natural Resource Management Faculty Publications

The Prairie Pothole Region (PPR) of North America is a globally important resource that provides abundant and valuable ecosystem goods and services in the form of biodiversity, groundwater recharge, water purification, flood attenuation, and water and forage for agriculture. Numerous studies have found these wetlands, which number in the millions, to be highly sensitive to climate variability. Here, we compare wetland conditions between two 30-year periods (1946–1975; 1976–2005) using a hindcast simulation approach to determine if recent climate warming in the region has already resulted in changes in wetland condition. Simulations using the WETLANDSCAPE model show that 20th century climate …

Local Adaptation To Climate Change In A Calcareous Grassland System, Catherine Ravenscroft

Biology - Dissertations

Annual manipulations of temperature and rainfall have been maintained in intact calcareous grassland since 1993 at the Buxton Climate Change Impacts Laboratory (BCCIL) in northern England (UK). Here I investigated the role of local adaptation as mechanism of the apparent resistance of species' to long-term climate manipulations at BCCIL using a common forb, Plantago lanceolata. Plantago lanceolata is a rosette-forming, perennial herb of wide-ranging distribution, and one of the more common forbs in calcareous grasslands, including BCCIL. In the first study I used a common garden approach to test for evidence of selection for different suites of functional traits in …

Warming Winters And Changing Habitats: Interactive Effects On Raptor Populations And Implications For Conservation, Neil A. Paprocki

Boise State University Theses and Dissertations

Studies across multiple spatial and temporal scales will improve understanding of the drivers of global change including habitat degradation, invasive species, and climate change. How global drivers affect the ecology of wintering raptors in western North America and the Great Basin may have important implications for changes in distribution and abundance, and consequently population persistence. I examined the winter distributions of six western North America raptor species using Christmas Bird Count data from 1975-2011 to assess range shifts over time and in relation to temperature. Also, I considered whether population patterns within Bird Conservation Regions (BCR) were best explained by …

Projecting Terrestrial Carbon Sequestration Of The Southeastern United States In The 21st Century, Xia Song, Hanqin Tian, Xiaofeng Xu, Dafeng Hui, Guangsheng Chen, Greg Sommers, Luke Marzen, Mingliang Liu

Biology Faculty Research

How terrestrial ecosystems respond to future environmental change in the 21st century is critically important for understanding the feedbacks of terrestrial ecosystems to global climate change. The southeastern United States (SEUS) has been one of the major regions acting as a carbon sink over the past century; yet it is unclear how its terrestrial ecosystems will respond to global environmental change in the 21st century. Applying a process-based ecosystem model (Dynamic Land Ecosystem Model, DLEM) in combination with three projected climate change scenarios (A1B, A2, and B1 from the IPCC report) and changes in atmospheric carbon dioxide, nitrogen deposition, and …

Marine Invertebrates: Communities At Risk, Jennifer A. Mather

Ecological Impacts of Climate Change Collection

Our definition of the word ‘animal’ centers on vertebrates, yet 99% of the animals on the planet are invertebrates, about which we know little. In addition, although the Census of Marine Life (COML.org) has recently conducted an extensive audit of marine ecosystems, we still do not understand much about the animals of the seas. Surveys of the best-known ecosystems, in which invertebrate populations often play a key role, show that the invertebrate populations are affected by human impact. Coral animals are the foundation of coral reef systems, which are estimated to contain 30% of the species in the ocean. Physical …

Ant Community Dynamics And The Effects Of Global Warming, Katharine Lisa Stuble

Doctoral Dissertations

This dissertation seeks to provide an understanding of how species coexist and, further, how climate change may alter communities by acting on the mechanisms that promote coexistence. Specifically, I examined coexistence among ant species in eastern deciduous forests and the effects that warming may have on foraging activity. Through a series of field observations, I sought evidence for the importance of four of the most commonly cited mechanisms for coexistence among ant species: the dominance – discovery tradeoff, the dominance – thermal tolerance tradeoff, spatial segregation, and niche partitioning. In this system, I did not find evidence for any of …

Climate Change Extension: Presenting The Science Is Necessary But Insufficient, Paul C. Vincelli, Rebecca L. Mcculley

Plant Pathology Presentations

Why Should We Consider How to Present Scientific Information?

To engage a wide spectrum of agricultural producers in the discussion of human-induced climate change and its mitigation.

What Did We Do?

Our initial Extension efforts on climate change in Kentucky were based on an information-deficit model, which assumes that citizens fail to accept climate change because they don’t understand the science. However, social science research indicates that this topic has cultural significance for many agricultural producers, suggesting that presentation of sound scientific information alone is likely to be unpersuasive. Based on social science research, we redesigned our outreach efforts to …

What To Eat Now? Shifts In Polar Bear Diet During The Ice-Free Season In Western Hudson Bay, Linda J. Gormezano, Robert F. Rockwell

Publications and Research

Under current climate trends, spring ice breakup in Hudson Bay is advancing rapidly, leaving polar bears (Ursus maritimus) less time to hunt seals during the spring when they accumulate the majority of their annual fat reserves. For this reason, foods that polar bears consume during the ice-free season may become increasingly important in alleviating nutritional stress from lost seal hunting opportunities. Defining how the terrestrial diet might have changed since the onset of rapid climate change is an important step in understanding how polar bears may be reacting to climate change. We characterized the current terrestrial diet of polar bears …

Changes In Net Ecosystem Production Over The Past 40 Years In Arctic Tundra Ponds Near Barrow, Alaska: Application Of Historic And Modern Techniques, Nickole Ann Miller

Open Access Theses & Dissertations

Arctic environments have gained interest recently due to their sensitivity to climate change. As warming has created longer growing seasons, extended ice-free periods as well as permafrost thaw, the production in freshwater ecosystems has the potential to be greatly impacted. It is hypothesized that as climate change and warming occurs, increases in primary production will occur and ponds will become carbon sinks. Net ecosystem production (NEP) was determined using phytoplankton and periphyton samples collected weekly during the growing season (June - August) from arctic tundra ponds near Barrow, Alaska. Enrichment with 14C was used to determine both weekly photosynthetic rates …

Ecological Interactions Influencing Avicennia Germinans Propagule Dispersal And Seedling Establishment At Mangrove-Saltmarsh Boundaries, Jennifer Mcclain Peterson

USF Tampa Graduate Theses and Dissertations

Mangroves and saltmarshes are ecologically important coastal ecosystems; unfortunately, these low-lying coastal ecosystems are vulnerable to global climate change. As sea-levels rise, mangroves are expected to shift their distribution landward towards higher elevation sites that are occupied by other plants, including saltmarsh taxa. Therefore, mangrove recruits at the leading edge of expansion may interact with diverse assemblages of saltmarsh plants, and these interactions could influence the success of mangrove encroachment into higher tidal-elevation areas. The purpose of the research presented here was to investigate empirically the ecological interactions that may influence the recruitment of the black mangrove, Avicennia germinans, …

A History Of Place: Using Phytolith Analysis To Discern Holocene Vegetation Change On Sanak Island, Western Gulf Of Alaska, Cricket C. Wilbur

Antioch University Full-Text Dissertations & Theses

This study investigated a terrestrial climate proxy, phytoliths, as a complimentary approach to documenting the dynamics of present and past vegetation on Sanak Island, the largest island in a small island group in the eastern Aleutian archipelago, and as a new basis by which to interpret Holocene environmental variability in Alaska. A phytolith reference collection was established from 59 selected plant species of maritime tundra belonging to 27 families. The grass species and a sedge species produced abundant phytolith forms whereas the majority of dicotyledons in this study were trace producers of phytoliths. A paleoenvironmental reconstruction from fossil phytoliths recovered …

Modeling The Ecological Niche Of The Nigeria-Cameroon Chimpanzee Under Climate Change, Paul Ryan Sesink Clee

Legacy Theses & Dissertations (2009 - 2024)

Ecological niche theory states that a set of environmental conditions exists that a species relies upon in order to survive and reproduce. Collectively, these variables define a species' niche, which includes a species' dispersal abilities and its range. Ecological niche modeling predicts the distributions of species by using information from environmental variables across geographic space, making it a valuable tool for studying how environment affects population dynamics. With accurate species presence data and geospatial information that describe its known habitat, ENMs can effectively map a species' realized niche across geographical space, and for closely related taxa, be used to understand …

Evaluating Habitat Vulnerability And Sustainability Of Urban Seagrass Resources To Sea Level Rise, Cynthia A. Meyer

USF Tampa Graduate Theses and Dissertations

The seagrass resource provides essential ecosystem functions for many marine species. This research evaluated the vulnerability and sustainability of the seagrass resource in an urbanized area to the effects of sea level rise. The assessment required analysis of information regarding the biogeography of the seagrass resource, and developing a method to model the spatial extent of the suitable habitat for seagrass, and applying the model to predict the implications of simulated sea level rise scenarios on the seagrass resource.

Examining the biogeography of the seagrass resource required the development of a seagrass monitoring and assessment field survey and a comprehensive …

Ecophysiological Responses Of Tall Fescue Genotypes To Endophyte Infection And Climate Change, Marie Bourguignon

Theses and Dissertations--Plant and Soil Sciences

Tall fescue is a widely used forage grass in the eastern USA and can form a symbiosis with a fungal endophyte, which can be beneficial for the plant but can cause livestock health issues. Little is known regarding the symbiotic response to predicted climate change. To address this knowledge gap, I analyzed tall fescue variety trial data collected throughout the U.S., exploring relationships between climate variables and yield for two different fescue cultivars that were either endophyte-free or infected. This study showed no endophyte or cultivar effect on fescue yield, but identified temperature, precipitation and location as significant predictors of …