Life Sciences Commons^™

Linking Microbial Community Assembly In Flowers With Function Under Diverse Environmental Conditions: A Case Study Involving Erwinia Amylovora, Christopher Skylar Mcdaniel

All Graduate Theses and Dissertations, Fall 2023 to Present

Fire blight, a devastating disease of pome fruit trees caused by the bacterium Erwinia amylovora, can cause millions of dollars in losses for producers each year around the globe. Management approaches that involve use of antibiotics, such as streptomycin, can be effective; although concerns exist over pollinator and crop health when using them regularly. Recently, there have been developments that allow for biological agents such as microbes to curtail fire blight infection. These agents work by competing with Erwinia for resources or space, producing antibacterial compounds, or even killing Erwinia cells on contact. Unfortunately, these agents do not yet …

The Effects Of Recent Climate Change On Spring Phenology, With A Special Focus On Patterns Of Bee Foraging, Michael Stemkovski

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

The date on which plants flower and on which bees begin to pollinate varies year-to-year depending on differences in weather. This seasonal timing is known as phenology, and it is already clear that climate change has pushed the spring phenology of many species earlier by increasing temperatures. This is particularly clear in flowering plants, but studying how and why the phenology of pollinators is shifting is more difficult. Most flowering plants rely on pollinators such as bees for their reproduction, and most bees rely on flowers for their sustenance, so bee and flower phenology has to overlap for the crucial …

Local And Regional Landscape Characteristics Driving Habitat Selection By Greater Sage-Grouse Along A Fragmented Range Margin, Aidan T. Beers

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

In response to ongoing landscape change, wildlife species are likely to respond in varied ways. By studying habitat specialists, we are able to better understand the most likely ways in which the denizens of threatened ecosystems will react to those changes. Among the most threatened ecosystem types in North America are sagebrush ecosystems of the Intermountain West, where one of its most well-known residents, greater sage grouse (hereafter, “sage-grouse), have lost more than 50% of their habitat due to fire, invasive species, climate change, encroachment by coniferous forests and avian predators using it, and human-caused landscape conversion. Sage-grouse rely on …

Responses Of Extreme Discharge To Changes In Surface-Air And Dewpoint Temperatures In Utah: Seasonality And Mechanisms, Timothy E. Wright, Jacob Stuivenvolt-Allen, Grace Affram, Nahid A. Hasan, Cody Ratterman, Wei Zhang

Plants, Soils, and Climate Faculty Publications

The changes in stream discharge extremes due to temperature and seasonality are key metrics in assessing the effects of climate change on the hydrological cycle. While scaling is commonly applied to temperature and precipitation due to the physical connections between temperature and moisture (i.e., Clausius–Clapeyron), the scaling rate of stream discharge extremes to air and dewpoint temperatures has not been evaluated. To address this challenge, we assess the scaling rates between stream discharge and air temperature and between stream discharge and dewpoint temperature in Utah using a well-designed statistical framework. While there are deviations from the Clausius–Clapeyron (CC) relationship in …

Sea-Ice Conditions Predict Polar Bear Land Use Around Military Installations In Alaska, Eric V. Regehr, Kristin L. Laidre, Todd C. Atwood, Harry L. Stern, Benjamin Cohen

Human–Wildlife Interactions

Polar bears (Ursus maritimus) are threatened by sea-ice loss due to climate change, which is concurrently opening the Arctic to natural resource extraction and a broader scope of national security responsibilities. Mitigating the risk of human–bear conflicts is an emerging challenge as many polar bears spend longer ice-free summers on land where they have limited access to food and come into more frequent contact with people. We investigated a suite of physical and ecological variables that influence the timing of polar bear arrival on, and departure from, land using remote-sensing data on sea-ice extent and satellite telemetry data …

Editorial: Mammalian Responses To Climate Change: From Organisms To Communities, Johan T. Du Toit, Robyn S. Hetem, M. Denise Dearing

Wildland Resources Faculty Publications

Mammals have displayed spectacular evolutionary success ever since an asteroid impact caused the Cretaceous-Tertiary extinction event ~66 million years ago, when the non-avian dinosaurs disappeared. Now another mass extinction event is underway because of another major planetary disturbance, but this time it is directly caused by just one over-achieving species among all those mammals: Homo sapiens.

Hidden Mechanisms Of Climate Impacts In Western Forests: Integrating Theory And Observation For Climate Adaptation, Sara J. Germain

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Fire, insects, and disease are necessary components of forest ecosystems. Yet, climate change is intensifying these tree stressors and creating new interactions that threaten forest survival. This dissertation combined field observations with statistical predictions of changing disturbances in western forests to identify 1) how conventional models may underestimate future forest loss, and 2) how positive relationships between trees may be exploited by managers to prevent forest loss.

In Chapter II, I tested whether increasingly extreme weather with climate change increases Pacific yew extinction risk. I found that conventional modeling methods underestimated local extinction risk because trees were adapted to a …

Impacts Of The Changing Pacific On North American Drought, Atmospheric Rivers, And Explosive Cyclones, Jacob Stuivenvolt-Allen

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

The impacts of specific weather events can vary greatly from year to year. Much of these impacts depend heavily on the frequency of impactful weather which is constrained by the state of the climate system each year. This research focuses largely on the impacts that climate oscillations from year-to-year or even from decade-to-decade have on the frequency of impactful weather. There are numerous examples of impactful weather that impact North America, but this work focuses on drought in the western United States, atmospheric rivers in Northern California and rapidly developing winter storms along the east coast. While seemingly disparate events, …

An Evaluation Of Landscape, Climate, And Management Impacts On Bumble Bees (Hymenoptera: Apidae: Bombus) In Agroecosystems, Morgan Elizabeth Christman

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Bumble bees play pivotal roles in pollinating wild and cultivated plant communities. Unfortunately, bumble bee populations are declining due to disturbances such as landscape conversion and climate change. Additionally, traps used to monitor pest insect populations often capture bumble bees, leading to a concern that trap captures increase bumble bee mortality. First, I studied bumble bee communities based on land cover and weather variables in agricultural fields in Utah. Bumble bee communities were more diverse in agricultural fields with more agricultural land in the surrounding area, low temperatures, and high humidity during the growing season, and less diverse in fields …

Effective Conservation Of Desert Riverscapes Requires Protection And Rehabilitation Of In-Stream Flows With Rehabilitation Approaches Tailored To Water Availability, Casey A. Pennock, Phaedra Budy, William W. Macfarlane

Watershed Sciences Faculty Publications

Desert riverscape rehabilitation practitioners must contend with compounding effects of increasing human water demand, persistent drought, non-native species establishment, and climate change, which further stress desert riverine ecosystems such as rivers in the Colorado River basin, United States. Herein, we provide our perspective on the importance of natural flows, large floods in particular, for successful conservation and rehabilitation of riverscapes. We present ideas developed from our experience with rehabilitation projects across multiple desert tributary rivers with varying levels of habitat degradation and water abstraction. We propose spatially extensive measures such as protection of in-stream flows, tailoring rehabilitation efforts to available …

The Impacts Of Increased Precipitation Intensity On Dryland Ecosystems In The Western United States, Martin C. Holdrege

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

As the atmosphere warms, precipitation events become larger, but less frequent. Such increases in precipitation intensity are expected regardless of changes in total annual precipitation. Despite strong evidence for increases in precipitation intensity, disagreement exists regarding how these changes will impact plants, and studies are lacking in many types of ecosystems. This dissertation addresses how increased precipitation intensity affects soil water availability, and how plants respond to any such changes. I address this question in the context of big sagebrush ecosystems and dryland winter wheat agriculture, which are both environments that can be sensitive to changes in water availability. Results …

Climate Effects On Black Spruce And Trembling Aspen Productivity In Natural Origin Mixed Stands, Mahadev Sharma

Aspen Bibliography

Forest managers need site productivity estimates for tree species growing in mixed stands. Models developed in the past are generally for pure stands and don’t factor in the effects of climate change on site productivity. Therefore, site index (SI) models were developed for black spruce (Picea mariana Mill. B.S.P.) and trembling aspen (Populus tremuloides Michx.) trees grown in natural origin mixed stands. For this, 186 trees (93 black spruce and trembling aspen each) were sampled from 31 even-aged natural mixed stands (sites) (3 trees/species/site) across Ontario, Canada. Stand height growth models were developed by incorporating climate variables during …

Wind And Fire: Rapid Shifts In Tree Community Composition Following Multiple Disturbances In The Southern Boreal Forest, Elias Anoszko, Lee E. Frelich, Roy L. Rich, Peter B. Reich

Aspen Bibliography

Under a warming climate, the southern boreal forest of North America is expected to see a doubling in fire frequency and potential for increased wind disturbance over the next century. Although boreal forests are often considered fire-adapted, projected increases in disturbance frequency will likely result in novel combinations of disturbances with severities and impacts on community composition outside historic norms. Using a network of repeatedly measured vegetation monitoring plots, we followed changes in tree community composition in areas of the Boundary Waters Canoe Area Wilderness (BWCAW), in Minnesota, USA, experiencing disturbances ranging from severe windstorms or wildfires to areas affected …

Precipitation Is A Strong Predictor Of Airborne Ammonia Levels., Bridger Jorgensen, Casey Olson, Connor Snow

Research on Capitol Hill

USU senior Connor has lived in the Uintah Basin all his life and studies kinesiology. Senior Casey, a Cache Valley native, studies climate science and works at the Utah Climate Center. Junior Bridger, also of Cache Valley, studies nutrition science. They led and funded this project through a student grant. Casey was alarmed by the ammonia data he was collecting at the Climate Center. “I immediately began to wonder how this issue would evolve over the coming decades.” The three teamed up to take a look at how Logan’s record-breaking amount of ammonia in our air is impacting those who …

Bottom-Up Drivers Of Future Fire Regimes In Western Boreal North America, Adrianna C. Foster, Jacquelyn K. Shuman, Brendan M. Rogers, Xanthe J. Walker, Michelle C. Mack, Laura L. Bourgeau-Chavez, Sander Veraverbeke, Scott J. Goetz

Aspen Bibliography

Forest characteristics, structure, and dynamics within the North American boreal region are heavily influenced by wildfire intensity, severity, and frequency. Increasing temperatures are likely to result in drier conditions and longer fire seasons, potentially leading to more intense and frequent fires. However, an increase in deciduous forest cover is also predicted across the region, potentially decreasing flammability. In this study, we use an individual tree-based forest model to test bottom-up (i.e. fuels) vs top-down (i.e. climate) controls on fire activity and project future forest and wildfire dynamics. The University of Virginia Forest Model Enhanced is an individual tree-based forest model …

Identifying Conifer Tree Vs. Deciduous Shrub And Tree Regeneration Trajectories In A Space-For-Time Boreal Peatland Fire Chronosequence Using Multispectral Lidar, Humaira Enayetullah, Laura Chasmer, Christopher Hopkinson, Dan Thompson, Danielle Cobbaert

Aspen Bibliography

Wildland fires and anthropogenic disturbances can cause changes in vegetation species composition and structure in boreal peatlands. These could potentially alter regeneration trajectories following severe fire or through cumulative impacts of climate-mediated drying, fire, and/or anthropogenic disturbance. We used lidar-derived point cloud metrics, and site-specific locational attributes to assess trajectories of post-disturbance vegetation regeneration in boreal peatlands south of Fort McMurray, Alberta, Canada using a space-for-time-chronosequence. The objectives were to (a) develop methods to identify conifer trees vs. deciduous shrubs and trees using multi-spectral lidar data, (b) quantify the proportional coverage of shrubs and trees to determine environmental conditions driving …

New Research And Wild Horse And Burro Management, David Jenkins

Human–Wildlife Interactions

In the United States, the Wild Free-Roaming Horses and Burros Act (WFRHBA) gave the Bureau of Land Management (BLM) and the U.S. Forest Service the statutory obligation to manage and protect free-roaming equids (i.e., wild horses [Equus ferus] and burros [E. asinus]) on designated management areas on public land. The WFRHBA was intended to ensure that wild horses and burros on the public lands exist in self-sustaining herds in perpetuity, alongside other congressionally mandated, multiple uses of public lands. The BLM recently published a strategic research plan for their wild horse and burro program. The research …

Climate Change Impacts On Atmospheric Ammonia And Implications For Human Health, Casey Olson, Connor Snow, Bridger Jorgensen

Fall Student Research Symposium 2021

According to national data Cache Valley has the highest concentrations of atmospheric ammonia in the nation. This study aims to answer the questions of whether climate variables and events such as precipitation, averaged winds, geopotential height, and teleconnections can be used to predict the behavior of pollutants and how human biology is potentially affected. Data from the Utah Climate Center shows that the 3rd yearly quartile has the highest levels of airborne ammonia due to the high levels of fertilizer use and livestock emissions in the farming industry in Cache Valley. After data analysis, there seems to be a connection …

Understanding How Changes In Precipitation Intensity Will Affect Vegetation In The Western U.S., Cristina Chirvasa

Fall Student Research Symposium 2021

Precipitation events are becoming more intense as the atmosphere warms, but it remains unclear how precipitation intensification will affect plant growth in arid and semiarid ecosystems. There is conflicting evidence suggesting that larger precipitation events may either increase or decrease plant growth. Here, we report the growth responses of herbaceous and woody plants to experimental manipulations of precipitation intensity in a cold, semi-arid ecosystem in Utah, USA. In this experiment, precipitation was collected and redeposited as fewer, larger events with total annual precipitation kept constant across treatments. Results from the first two growing seasons revealed that more intense events ‘pushed’ …

Digitization Of Entomological Collections At Usu, Eastern Using Scan (Symbiota Collections Of Arthropods Network) Data Portal And Seek! Inaturalist App, Alexandra Cartwright

Fall Student Research Symposium 2021

Pollinators, including bees, provide valuable ecosystem services for native plants and agricultural species. Phenology, or the timing of biological events such as flowering of plants, is changing as a result of climate change. The digitization of specimens allows for insights into species distributions, seasonality, and phenology in 60-70-year-old collections. The entomological collection at Utah State University, Eastern houses approximately 3,000 individual specimens and over 100 bees. The oldest specimens date from 1953, many from the 1960s, 70s, & 80s and the majority of specimens are from Carbon and Emery Counties. Digitization of entomological collections can provide: species distributions: Which species …

Log Proximity And Moss As Indicators Of Conifer Seedling Abundance In Old-Growth Douglas-Fir/ Hemlock Forests, Isabella Wetzler

Fall Student Research Symposium 2021

It is increasingly essential to develop a comprehensive understanding of forest processes so that we may better conserve and maintain our old-growth forests in the face of climate change. In the Pacific Northwest, logs might elevate and remove conifer seedlings from light competition with moss and herbs, but seedlings growing on the forest floor may benefit from log shade. Moss can retain moisture which may result in higher water availability for seedlings, but in droughty conditions the desiccated moss might leave seedlings ‘high and dry’. Logs increase mircrosite heterogeneity, providing cool, moist microclimates for seedlings and protecting them from droughty …

Understanding The Effects Of Climate Change Via Disturbance On Pristine Arctic Lakes—Multitrophic Level Response And Recovery To A 12-Yr, Low-Level Fertilization Experiment, Phaedra Budy, Casey A. Pennock, Anne E. Giblin, Chris Luecke, Daniel L. White, George W. Kling

Watershed Sciences Student Research

Effects of climate change-driven disturbance on lake ecosystems can be subtle; indirect effects include increased nutrient loading that could impact ecosystem function. We designed a low-level fertilization experiment to mimic persistent, climate change-driven disturbances (deeper thaw, greater weathering, or thermokarst failure) delivering nutrients to arctic lakes. We measured responses of pelagic trophic levels over 12 yr in a fertilized deep lake with fish and a shallow fishless lake, compared to paired reference lakes, and monitored recovery for 6 yr. Relative to prefertilization in the deep lake, we observed a maximum pelagic response in chl a (+201%), dissolved oxygen (DO, −43%), …

Understanding Climate Change Impacts And Adaptation Potentials At Utah Ski Resorts, Rachel Hager

All Graduate Plan B and other Reports, Spring 1920 to Spring 2023

Increasing temperature and shifting precipitation regimes due to climate change are a significant threat to winter recreation. Some businesses such as high-elevation ski resorts are especially vulnerable to the impacts of climate change. However, ski resorts may be able mitigate the impacts of climate change by proactively implementing adaptation strategies. The overall goal of this study was to investigate the impact of climate change on Utah ski resorts, and to understand adaptation perception, barriers, and strategies for different resorts across the state.

To meet that goal, we used a mixed-methods approach including examining temperature shifts at all Utah ski resorts …

Susceptibility Of High-Elevation Forests To Mountain Pine Beetle (Dendroctonus Ponderosae Hopkins) Under Climate Change, David N. Soderberg

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Across western North America, pine forests are important for timber, wildlife habitat, and at high elevations are important for water retention and yield from rain and snowmelt. The mountain pine beetle (MPB) is one of the most significant disturbance agents shaping pine forests, and like all insects, temperature is a major driver of its population success and the dynamics of the landscapes that they inhabit. Changing temperature regimes can therefore directly influence MPB population persistence at a particular location, in addition to potential shifts in the range boundaries that they inhabit. MPB is currently expanding its range northward in British …

Comparative Study Of The Microbiome Of The Native Plant Ceanothus Velutinus (Snowbrush) From Different Locations And Greenhouse Studies, Jyothsna Ganesh

Student Research Symposium

Climatic change is one of the biggest threats to the ecosystem and biodiversity by enhancing environmental stresses. Environmental stresses such as biotic and abiotic stresses affect plant health and reduce crop production. The rhizosphere microbiome of a plant plays a significant role in a plant's defense against various biotic and abiotic stresses. In this study, we are investigating the microbiome diversity of bulk soil, rhizosphere, and endosphere of Ceanothus velutinus, snowbrush. Ceanothus is an evergreen native plant that is usually found in dry areas and thrives well in harsh conditions. The snowbrush samples were collected from different locations 1920m, 1950m, …

Pheonolgy And Climate Change In The Tw Daniel Experimental Forest Meadow, Elise Riley

Student Research Symposium

As the earth’s climate warms many plant species are experiencing phenological stages (the timing of their seasonal life cycle events) earlier than they previously have. Dangers of phenological stages occurring earlier in the year include a greater risk of frost kill and the possibility of the speciation of already small populations, both of which could make species more susceptible to extinction. This research focused on determining if meadow forb species within Utah State University’s TW Daniel Experimental Forest (TWDEF) have experienced earlier phenology -specifically, earlier flowering dates- over the past 52 years. Historical phenological data was obtained from journals kept …

Climate Change's Destabilizing Impacts On Nigerian Economy Leaves Room For Boko Haram Expansion, Ellie Willard

Student Research Symposium

The impacts of climate change in Nigeria are extending beyond changes in the weather, leading to huge changes in the lives of individual Nigerians, the Nigerian Government and Boko Haram, a terrorist organization. The reduction of the agricultural industry and the oil industry are going to create a welcoming environment for Boko Haram to grow. Unless changes are made to the Nigerian economic sector, the immediate impacts of climate change is likely to increase Boko Haram recruits. Presentation Time: Thursday, 11 a.m.-12 p.m.Zoom link: https://usu-edu.zoom.us/j/84125172996?pwd=aDlRb3dhU3AyUzR2eXNMRytZWmF3dz09

Human-Accelerated Biodiversity Loss During Climate Change Threatens Human Health & Food Security, Miles Robertson

Student Research Symposium

Humans have been the single most impactful species to the biosphere for the past few thousand years. Usually, consequences of human-caused ecological changes come about on a time scale larger than our normal cause-and-effect perception allows. However, with the onset of climate change, the effects of human-accelerated biodiversity loss are set to expose vulnerabilities in human health and food security. My research explores three arenas in which climate change is set to exacerbate the effects of biodiversity loss: zoonotic disease, US corn crops, and the Chinese fishing industry. Presentation Time: Wednesday, 1-2 p.m. Zoom link: https://usu-edu.zoom.us/j/87892002075?pwd=Ym1Tcy9NOVhaaGZWczZWY1JCL3owUT09

Space Solar Power Mitigates Climate Change, Tests Global Energy Markets And Space Policies, Sierra Kline

Student Research Symposium

The harnessing of space solar power (SSP) has dynamic and disruptive potential in three connected threat categories: energy security (both from insecure sources and from depleting resources,) climate change, and the erosion of US space dominance and related reduction in international space security. GHG levels require a drastic shift from fossil fuels to renewables, yet current renewable systems (hydro, wind, solar,) are not capable of supporting the projected increases in energy needs going into the mid 21st century. SSP would provide a solution to the lack of stable energy sources that are proving disastrous in many parts of the world …

Functional Complementation Of The Ppgcn4 And Ppnhx2 Genes In Arabidopsis Thaliana To Study Salt Tolerance, Amanda Moravek

Student Research Symposium

Climate change induces unexpected weather and causes abiotic and biotic stresses in plants. These stresses negatively affect crop growth and production. Additionally, a steady increase in the world population has been leading to higher food demand. Therefore, the development of more stress-resilient crops is essential to combat these problems. One such stress is a salinity that affects crop production. Almond is a salt-sensitive crop, so there is a need to identify salt-tolerant almond rootstocks. AtGCN4 is a novel gene that was identified in Arabidopsis thaliana to play a significant role in host-pathogen interaction and drought tolerance when overexpressed. The preliminary …