Life Sciences Commons^™

The Future Of Maine's Forests Under Alternative Socioeconomic, Climate And Conservation Pathways, Jianheng Zhao

Electronic Theses and Dissertations

Maine is a historically important timber supply region in North America and understanding the potential change in forestlands and their product industries affected by climate change and various socio-economic conditions can better improve the forest healthy and sustain a sustainable product industry. A statistical harvest choice model for the state of Maine was developed in chapter 1. It was estimated using a multinomial logit model of two products, under varying management intensities, and ownership classifications across varying market conditions. Results indicate that stumpage prices have a significant effect on forest landowners' harvest decisions and that the expansion of conservation land …

A Crisis Of Kelp, Rachel L. Sherman

Capstones

Along with insects and lab-grown meat, for years seaweed has been lauded as a sustainable “food of the future” by the U.N. Food and Agricultural Organization. As the world increasingly turns to alternative foods in pursuit of a healthier Earth, seaweed has all the makings of an ecological savior. It’s plentiful — seaweeds and ocean algae make up roughly nine tenths of all the plant life on Earth — it’s cheap to harvest and get to market, packed with nutrition, and keeps oceans clean, absorbing more carbon dioxide and releasing more oxygen than the world’s rainforests.

But outside of Japanese …

Climate Change, Increased Wildfire Frequency, And Rodent-Exclusion Create Opportunities For Exotic Grass Invasion And Alter The Timing And Availability Of Soil Water, Joshua Clark Gilman

Theses and Dissertations

In deserts, global environmental changes, plant community structure, and soil water availability form a complex relationship characterized by direct and indirect relationships and feedbacks. Plant community structure is affected by the establishment and spread of invasive grasses, which form a positive feedback with wildfire. Plant community structure is also controlled by top-down trophic interactions by small-mammals and climate change, which alters the timing and amount of soil water. In deserts, soil water availability mediates the effects of global environmental changes and trophic interactions on plant community structure because it is the limiting resource for plant growth. In order to predict …

Drivers Of Decadal Vegetation Change In Northern Alaska, Jacob Allen Harris

Masters Theses

The Arctic is experiencing rapid climate change. This research documents vegetation change near Atqasuk and Utqiaġvik, Alaska. At each location, 30 plots distributed in a matrix across the landscape, were sampled annually from 2010 to 2019 using a point frame. For every encounter we recorded the height and classified it into eight broad functional groups (deciduous shrubs, evergreen shrubs, forbs, graminoids, bryophytes, lichens, litter and standing dead vegetation); for vascular plants we also identified the species. We found a consistent increase in plant stature and cover over time which was dramatic at Atqasuk. Graminoid cover and height increased at both …

Phenotypic Responses Of Sagebrush To The Southwestern North America Megadrought: A Genotype-By-Environment (Gxe) Approach, Kara A. Navock

Boise State University Theses and Dissertations

The Southwestern North America megadrought is an extreme climate event. Artemisia tridentata (big sagebrush) is the dominant, keystone species of sagebrush-steppe ecosystems in arid and semi-arid habitats of western North America. I conducted a genotype-by-environment (GxE) experiment on two putative genotypes (drought-tolerant, G1 and drought-sensitive, G2) and two cytotypes, diploid (2x) and tetraploid (4x), to determine the phenotypic responses of big sagebrush seedlings to drought. For three chlorophyll fluorescence parameters, my results indicate a complex set of factors influence sagebrush responses to drought, including canalization, adaptive phenotypic plasticity, cryptic genetic diversity, and GxE interactions. Variation in leaf temperature profiles of …

Effects Of Long-Term Variation In Temperature On Reproductive Phenology In A Population Of Eastern Bluebirds (Sialia Sialis), Paul Pleiman

Graduate Theses and Dissertations

This study investigates the relationship between multiple temperature variables, to include annual and pre-lay date temperatures with first-egg and mean first-egg lay dates of the eastern bluebird at the Warner Parks in Nashville, Tennessee, USA. Data is collected by citizen scientists for the Eastern Bluebird Nesting Box Project while visiting artificial nest boxes throughout the park and recording observations made during the breeding season. Temperature data is retrieved from the Northwest Alliance for Computational Science and Engineering’s Parameter-elevation Regressions on Independent Slopes Model (PRISM) Climate Group, based at Oregon State University. The analyses showed no correlation between annual or pre-lay …

Not Too Hot, Not Too Cold, But Moderately Variable: The Influence Of Environmental Variability On Coral Thermal Tolerance, Courtney Nicole Klepac

Biological Sciences Theses & Dissertations

Anthropogenic climate change is causing an increase in the frequency and severity of marine heat waves, resulting in declining health of coral reef ecosystems worldwide. Coral bleaching events – the breakdown in symbiosis between the coral host and their intracellular photosynthetic algae – are increasingly common in recent years and contribute to widespread losses in coral cover. However, bleaching and heat stress responses vary across spatial scales both within and among coral species. Coral populations native to highly variable environments can have greater bleaching resistance than corals from more stable habitats and corals transplanted into these variable reef sites can …

Inoculum Potential Of Pinus Edulis-Associated Ectomycorrhizal Fungi Across A Forest Extirpation Chronosequence, Annie M. Montes

Biology ETDs

Few studies have examined inoculum potential of ectomycorrhizal fungi (EMF) in the absence of plant hosts, yet persistence of these fungi may be paramount to resilience of Pinus edulis and other mycorrhizal plant species. We conducted a study in which seven sites were selected in northwestern New Mexico with known dates of P. edulis extirpation and a lack of regeneration. Age classes included: two sites extirpated 10-20 years ago, two extirpated 55-65 years ago, two extirpated 500+ years ago, and one extirpated 11,000+ years ago. At each site, two plots were paired: an extirpated plot and the nearest live adult …

Floral Traits And Carbon Dynamics Of Cucumber In Response To Climate Change, Sarah Josina Mcdonald

Electronic Thesis and Dissertation Repository

Pollination by animals is an important ecosystem service that contributes to the reproduction of many angiosperms. Climate change may alter this mutualism by affecting floral traits that are important to pollinators. Using Cucumis sativus, I tested the effects of experimentally elevated temperature and CO₂ concentration on flowering onset, flower number, flower size, and floral rewards. Additionally, to better understand plant carbon balance and investment in reproduction, I measured biomass partitioning and leaf carbon fluxes of plants under their growth conditions. Carbon dynamics were similar across treatments, and plants grown under high [CO₂] and temperature showed similar …

Harmful Algal Blooms: Dominance In Lakes And Risk For Cyanotoxin Exposure In Food Crops, Austin D. Bartos

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Climate change and human activities are promoting the dominance of a photosynthetic family of aquatic bacteria, cyanobacteria. Blooms of cyanobacteria are not only a visual nuisance but can produce a variety of cyanotoxins than can harm the liver, skin, and nervous system of animals and humans. We analyzed lakes in the contiguous United States and found that between 2007 and 2012, the number of lakes that produced measurable quantities of cyanotoxins increased from 33% to 45%. Nitrogen and phosphorus pollution were the main drivers of cyanobacteria blooms and toxin production between these years. Many of these lakes and reservoirs are …

Interacting Effects Of Climate And Biotic Factors On Mesocarnivore Distribution And Snowshoe Hare Demography Along The Boreal-Temperate Ecotone, Alexej P. Siren

Doctoral Dissertations

The motivation of my dissertation research was to understand the influence of climate and biotic factors on range limits with a focus on winter-adapted species, including the Canada lynx (Lynx canadensis), American marten (Martes americana), and snowshoe hare (Lepus americanus). I investigated range dynamics along the boreal-temperate ecotone of the northeastern US. Through an integrative literature review, I developed a theoretical framework building from existing thinking on range limits and ecological theory. I used this theory for my second chapter to evaluate direct and indirect causes of carnivore range limits in the northeastern US, …

Habitat Fragmentation And Range Margin Effects On Dispersal And Interactions Between Competitors, Rachel Roxann Harman

LSU Doctoral Dissertations

Dispersal is a fundamental process that affects local and regional dynamics, including population persistence, range expansion, and interspecific interactions, particularly as disturbance through habitat fragmentation and climate change. Here, my main objective was to ascertain how fragmentation affects dispersal and the interactions of competitors within the local patch and regional landscape. In my second chapter, I assessed dispersal through a literature review and population persistence model to examine the breadth and frequency of different density-emigration forms that occur in nature, including forms that are not prevalent in the literature. I conclude that these rare forms have important population dynamic consequences …

Understanding The Influence Of Changing Climate On Mycotoxin Contamination Of Food And Indoor Fungi-Mediated Respiratory Illness, Mayomi Helen Omebeyinje

Theses and Dissertations

Over the years, climate change has been a major core issue in public and environmental health. The World Health Organization (WHO) estimated that about 250,000 additional death per year would be attributed to climate change between 2030 and 2050 if this situation persists. Since our population depends on (but not limited to) the availability of clean water, good air quality, and exposure to environmental hazards/pathogens, the overall health impact caused by climate change is likely to be overwhelming in the nearest future. This dissertation explored the influence of climate change on fungi diseases and pathogenesis after severe weather conditions (hurricanes …

Investigating The Role Of Carbon Stress In The Mortality Of Tamarack Seedlings Under A Warming Environment, Bridget K. Murphy

Electronic Thesis and Dissertation Repository

Climate warming is increasing the frequency of climate-induced tree mortality events. While drought combined with heat is considered the primary cause of this tree mortality, little is known about whether high temperatures alone can induce mortality, or whether rising CO₂ will increase survival. I grew tamarack in two experiments combining warming (0-8 ˚C above ambient) and CO₂ (400-750 ppm) to investigate whether high growth temperatures led to carbon limitations and mortality. Using glasshouses, +8 ˚C warming with ambient CO₂ (8TAC) led to 40% mortality despite thermal acclimation of respiration. Dying 8TAC seedlings had lower needle carbon concentrations …

A Comparison Of Fuel Reduction Methods For Wildfire Risk Management And Climate Change Resiliency In Mixed Conifer Forests In The Sierra Nevada, Heather Navle

Master's Projects and Capstones

Wildfires in the mixed conifer forests of California’s Sierra Nevada have been a common and natural disturbance for thousands of years, historically occurring every 3 to 30 years. The flora and fauna of the mixed conifer forest have evolved to depend on low to moderate severity wildfires for reproduction, foraging, and habitat. However, the Sierra Nevada has experienced dramatic environmental changes over the past ~150 years as a result of three main factors: wildfire suppression, climate change, and habitat loss. Because of the threat wildfires pose to human lives, property and timber harvest, they have been suppressed to an extent …

Steady Heartbeat: Field And Laboratory Studies Indicate Unexpected Resilience To High Temperatures For The Ribbed Mussel Geukensia Demissa, Ashlyn N. Smith Ms.

Honors College Theses

Salt marshes are important ecosystems found along the coast of Georgia. Salt marshes are hosts to diverse organisms that interact with each other to promote many ecosystem services, such as storm buffering and flooding, and absorption of excess nutrients. Among these diverse organisms is the ribbed mussel, Geukensia demissa. Mussels are a foundation species in this intertidal landscape, and without them the whole salt marsh would be negatively affected. The purpose of this investigation was to explore the thermal stress response of G. demissa to rising temperatures. Mussels were collected from three locations that were landlocked, close to a …

Within-Reach Temperature Heterogeneity Is Limited In A Southern Appalachian Stream Network: Implications For Climate Change Refugia And Reach-Scale Temperature Mapping, Anna Kaz, Matthew Troia Dr., Xingli Giam Dr.

Chancellor’s Honors Program Projects

No abstract provided.

Investigating The Effects Of Sea-Level Rise And Increasing Salinity On Procambarus Lunzi Of Sapelo Island, Georgia, Samuel Long

Biology Theses

Barrier islands have great ecological and economical importance and face a threat from increasing sea-level due to climate change. Erosion of existing freshwater lens and ocean inundation could greatly change freshwater availability on the island. This could have significant impacts on freshwater crayfish like Procambarus lunzi, which are complexly intertwined into the trophic food web of the island. This study’s goal was to investigate the salinity tolerance of this crayfish on Sapelo Island, Georgia, in an attempt to predict the possible effects and response to sea-level rise by this crayfish. Crayfish were wild-caught from the island in March, June, and …

Sea Level Rise Vulnerability Analysis Of Mangrove Ecosystems Using Gis, Kayla Caldwell

HCNSO Student Theses and Dissertations

Climate change is accelerating beyond what is natural due to excessive emissions from human activities. The sea level has been rising for many years and is currently at a rate of 3.6 mm/yr. Mangroves are known to only keep pace with a sea level rate of less than 1.2 mm/yr. Mangroves are particularly vulnerable to rising sea levels if they are not able to keep pace through vertical sediment accretion or inland migration. To test the vulnerability of the south Florida mangrove ecosystems to sea level rise, this study analyzed changes in the mangrove forest coverage of the Oleta River …

Natural Variation And Evolutionary Responses To Climate Change Stressors In Marine Invertebrates, Joanna Sarah Griffiths

LSU Doctoral Dissertations

Our rapidly changing climate is putting many species at risk of extinction and there is an urgent need to understand how species will respond to these changes. In this dissertation, I evaluate how three species of marine invertebrates (corals, oysters, and copepods) respond to stressful conditions in their current environments and how plasticity and evolutionary adaptation could alter their response to future climate change stressors. I first employed a space for time study to elucidate population differences in the response of cold-water corals, Balanophyllia elegans, to future ocean acidification. I found evidence that upwelling history (natural low pH exposure) influences …

Higher Temperatures Have Contrasting Effects On Different Components Of Forage Quality For Caribou In Northern Alaska, Heidi Becker

Electronic Theses and Dissertations

Rising temperatures in the Arctic may affect vegetation, which in turn can affect herbivores, such as caribou, that rely on these plants for forage. Several plant traits contribute to forage quality, including digestibility, nitrogen content, and antiherbivory secondary compounds, but the effect of temperature on these traits individually and combined is unclear. I conducted a three-component study on the effect of higher temperatures on the forage quality of graminoids, deciduous shrubs, and evergreen dwarf shrubs on the North Slope of Alaska. The components included: 1) short and long-term experimental warming, 2) natural temperature variation between south and north-facing slopes, and …

The Ability Of Fragmented Kelp Forests To Mitigate Ocean Acidification And The Effects Of Seasonal Upwelling On Kelp-Purple Sea Urchin Interactions, Kindall A. Murie

Cal Poly Humboldt theses and projects

Bull kelp (Nereocystis leutkeana) forests along the coast for northern California have decreased dramatically as a result of a ‘perfect storm’ of multiple environmental stressors. The disappearance of a predatory sea star and subsequent increase in purple sea urchins (Strongylocentrotus purpuratus) and the recurrence of marine heat waves have caused these once diverse ecosystems to be rapidly converted into relative species-depauperate urchin barrens. By examining the interactive effects of both a rapidly changing abiotic environment and the increase in urchin grazing pressure that is affecting this vital ecosystem, we can better understand its ultimate fate and …

A Troop, A Raft, A Bed, Hanna Jane Guendel

Senior Projects Spring 2020

A Troop, a Raft, a Bed tells the interwoven fictional stories of three major animals (the mountain gorilla, the Adélie penguin, and the American eel) and four transitional animals (the white stork, the humpback whale, the common octopus, and the great white shark). The stories are told from the animals' perspectives, and are written with language that considers each animal's unique intelligence, mind, and behavior. These stories seek to communicate how animals around the world may be experiencing the various effects of climate change and global warming.

Investigating The Effects Of Climate Co-Stressors On Surf Smelt Energy Demands, Megan Russell

WWU Graduate School Collection

Surf smelt (Hypomesus pretiosus) are ecologically and economically important to the Pacific Northwest. They play a critical role in the food web and support numerous commercially important species and are an economically important baitfish. Surf smelt interact closely with the nearshore environment, utilizing approximately 10% of Puget Sound coastlines for spawning throughout the year. Surf smelt spawn at high tide and adhere fertilized eggs to beach sediment, causing their embryos to be exposed to air and seawater throughout embryonic development. Because of this unique life history, surf smelt may be susceptible to anthropogenic stressors including coastal development and …

Effects Of Multiple Stressors: Hydroperiod, Introduced Bullfrogs, And Food Limitation On Northern Red-Legged Frogs (Rana Aurora), Lindsey L. Gordon

Cal Poly Humboldt theses and projects

As human activities reach every corner of the globe, climate change, invasive species, habitat destruction, and other stressors causing species’ declines no longer act alone. Climate change has the potential to exacerbate (or mitigate) other stressors (e.g. invasive species or pathogens) affecting amphibian populations. I assessed the combined effects of increased pond drying rates (potential impact of climate change), invasive bullfrogs (Lithobates catesbeianus) presence, and food availability on northern red-legged frog (Rana aurora) survival and body size after metamorphosis by rearing tadpoles under incrementally shortened hydroperiods with and without the presence of invasive bullfrog tadpoles in …

Physiological Ecology Of Overwintering And Cold-Adapted Arthropods, Leslie Jean Potts

Theses and Dissertations--Entomology

Given their abundance and diversity, arthropods are an excellent system to investigate biological responses to winter. Winter conditions are being majorly impacted by climate change, and therefore understanding the overwintering biology of arthropods is critical for predicting ecological responses to climate change. In Chapters 2 and 3, I investigate the winter biology of a winter-active wolf spider. I show that winter-active spiders can take advantage of periodic prey resources and grown in the winter, which may allow them to get a jumpstart on spring reproduction. I also investigate spiders’ ability to track changes in their environment by quantifying low temperature …

The Impact Of Climate Change On The Migration Phenology Of New England’S Anadromous River Herring And American Shad, Charles K. Cobb

Honors Theses

Anadromous fish play important roles in food webs and nutrient cycling in both aquatic and marine ecosystems. As a result of climate change however, anadromous fish’s migration timing has begun to change, with potentially deleterious consequences to both anadromous fish, and the species that depend on them. Western coastal US studies have linked earlier anadromous fish returns to warming marine temperatures and changes in river flow regimes, but the exact temperatures thresholds that anadromous fish respond to, and the relative importance of temperatures and river flows, remain somewhat unknown. Additionally, there has been relatively little research on anadromous fish phenology …

Heat For The Masses: Thermal Ecology Of The Western Tent Caterpillar, Victoria Dahlhoff

Graduate Student Theses, Dissertations, & Professional Papers

A unique feature of some gregarious, colonial insects is their ability to create external structures that alter environmental conditions for the entire (often family) group. A combination of physical alteration of local microhabitats and behavioral thermoregulation allows many of these animals to actively control their body temperatures, which allows them to regulate energy use and metabolism in variable thermal environments. Here I describe mechanisms of microhabitat modification and thermal regulation in the western tent caterpillar, Malacosoma californicum pluviale. Tent caterpillars build communal silk tents, whose temperatures can rise substantially above ambient air temperature. I experimentally manipulated colony sizes and examined …