Ecology and Evolutionary Biology Commons^™

A Bayesian Hierarchical Approach For Modeling Virtual Species With Realistic Functional Trait Relationships, Sarah Bogen

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

Understanding the spatial and temporal dynamics of plant populations has important implications for the fields of ecology and conservation. A rich body of mathematical modeling approaches, including reaction-diffusion equations and integrodifference equations, have been developed to mechanistically model population spread based on species demography and seed dispersal characteristics. However, with over 390,000 plant species on Earth, it is not feasible to collect complete information on all species for the purpose of drawing generalized conclusions. One means of overcoming such a problem is through trait-based modeling, which seeks to represent realistic combinations of organismal traits rather than focusing on individual species. …

Evaluation Of Noninvasive Methods For Determining Pregnancy, Diet, Nutrition, And Stress Among Pronghorn Antelope: Implications For Population Monitoring, Cole Bleke

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

This study was conducted to increase our understanding of the influence of adult female pronghorn (Antilocapra americana) physiology on fawn summer survival. Pronghorn are a valued big game animal in Idaho, but are particularly sensitive to capture; therefore, we designed a noninvasive fecal sampling study to measure pregnancy (progesterone and estrogen), diet, nutrition (fecal nitrogen and DAPA), and stress (cortisol), during metabolically-demanding female life history stages (late gestation, early lactation, and breeding season). We also compared survey results between ground and aerial methods within mountain valley landscapes.

Pregnancy determination, via progesterone, is possible for pronghorn, but sample collection …

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 …

Conservation Genetics Of A Declining Bumble Bee In Western North America; The Influence Of Geography, Dispersal Limitation, And Anthopogenic Activity, Ashley T. Rohde

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Conservation biology addresses the problem of species loss by identifying species in need of protection. Conservation biology has subfields to address different aspects of biodiversity loss, including genetics and sociology. I used genetic approaches to assess the conservation status of western bumble bees, a bumble bee species of conservation concern.

The western bumble bee is a bumble bee species that ranges from Alaska to New Mexico and as far east as Wyoming and Colorado. This species is disappearing in some places. It may soon be listed as endangered in the United States and is already listed as endangered in parts …

Limited Effects Of Precipitation Manipulation On Soil Respiration And Inorganic N Concentrations Across Soil Drainage Classes In Northern Minnesota Aspen Forests, Anna B. Stockstad, Robert A. Slesak, Alan J. Toczydlowski, Charles R. Blinn, Randall K. Kolka, Stephen D. Sebestyen

Aspen Bibliography

It is critical to gain insight into the responses of forest soils to the changing climate. We simulated future climate conditions with growing season throughfall reduction (by 50%) and winter snow removal using a paired-plot design across a soil drainage class gradient at three upland, Populus-dominated forests in northern Minnesota, USA. In situ bulk soil respiration and concentrations of extractable soil N were measured during the summers of 2020–2021. Soil respiration and N concentrations were not affected by throughfall reduction and snow removal, which was largely attributed to the limited treatment effects on soil moisture content and soil temperature. …

Coping With Environmental Constraints: Geographically Divergent Adaptive Evolution And Germination Plasticity In The Transcontinental Populus Tremuloides, Roos Goessen, Nathalie Isabel, Christian Wehenkel, Nathalie Pavy, Lisa Tischenko, Lyne Touchette, Isabelle Giguère, Marie-Claude Gros-Louis, Jérôme Laroche, Brian Boyle, Raju Soolanayakanahally, Karen E. Mock, Javier Hernández-Velasco, Sergio Leonel Simental-Rodriguez, Jean Bousquet, Ilga M. Porth

Aspen Bibliography

Societal Impact Statement

Syntheses clearly show that global warming is affecting ecosystems and biodiversity around the world. New methods and measures are needed to predict the climate resilience of plant species critical to ecosystem stability, to improve ecological management and to support habitat restoration and human well-being. Widespread keystone species such as aspen are important targets in the study of resilience to future climate conditions because they play a crucial role in maintaining various ecosystem functions and may contain genetic material with untapped adaptive potential. Here, we present a new framework in support of climate-resilient revegetation based on comprehensively understood …

Growing Space Management In Boreal Mixedwood Forests: 22 Year Results, Richard Kabzems, George Harper, Che Elkin

Aspen Bibliography

Boreal mixed forests of trembling aspen (Populus tremuloides) and white spruce (Picea glauca) can provide higher outputs of many ecosystem goods and services, combined with resilience for changing environmental conditions. In this study, we examine the growth of white spruce and aspen over a range of stand compositions created by spot and broadcast treatments of broadleaves using manual and chemical means, aspen spacing, and untreated control. Twenty-two growing seasons postharvest, treatment responses created a range of broadleaf densities and spatial arrangements, reflected in significant differences in heights and diameters of the spruce mixedwood component. At this …

Recovery Of Trembling Aspen, Tamarack, And White Spruce Seedlings From Nacl Stress Following Winter Dormancy: Implications For Increased Foliar Potassium, Necrosis, And Sodium Management As Stress Resistance Mechanisms, Nathan T. Lauer

Aspen Bibliography

Revegetation of boreal forest lands disturbed by surface mining for bitumen can be challenging due to fluctuating levels of soil NaCl and harsh winter temperatures. These stressors may hinder the growth and survival of planted tree seedlings. Two experiments were carried out to examine the processes of recovery from NaCl stress and overwintering in trembling aspen, tamarack, and white spruce seedlings. In the recovery experiment, seedlings were treated with 0, 50, or 100 mM NaCl for 60 days and then allowed to recover for 60 days. Most of the examined physiological variables (total dry weight, chlorophyll concentration, photosynthesis, and transpiration) …

Compensatory Phenolic Induction Dynamics In Aspen After Aphid Infestation, Rajarshi Kumar Gaur, Ilka Nacif De Abreu, Benedicte Riber Albrectsen

Aspen Bibliography

Condensed tannins (CTs) are polyphenolics and part of the total phenolic (TP) pool that shape resistance in aspen (Populus tremula). CTs are negatively associated with pathogens, but their resistance properties against herbivores are less understood. CTs shape resistance to pathogens and chewing herbivores and could also shape resistance to aphids. Being chemical pools that are highly variable it can further be questioned whether CT-shaped resistance is better described by constitutive levels, by the induced response potential, or by both. Here, aspen genotypes were propagated and selected to represent a range of inherent abilities to produce and store foliar …

Young Forests And Fire: Using Lidar–Imagery Fusion To Explore Fuels And Burn Severity In A Subalpine Forest Reburn, Kristin H. Braziunas, Diane C. Abendroth, Monica G. Turner

Aspen Bibliography

Anticipating fire behavior as climate change and fire activity accelerate is an increasingly pressing management challenge in fire-prone landscapes. In subalpine forests adapted to infrequent, stand-replacing fire, self-limitation of burn severity in short-interval fire is incompletely understood. Spatially explicit fuels data can support assessments of landscape-scale fire risk and fuel feedbacks on burn severity. For a ~1450-km² largely forested landscape in the US Northern Rocky Mountains, we used airborne lidar and imagery to predict and map canopy and surface fuels. In a fire that burned mature (>125-year-old) and also reburned young (~30-year-old) subalpine forest, we then asked: (1) …

Evolution Of Floral Microbes And The Resulting Effects On Pollinator Preference, Hailey Hatch

Undergraduate Honors Capstone Projects

Floral microbes are an overlooked aspect of the extended floral phenotype. Through altering floral nectar chemistry, they can mediate interactions between flowers, pollinators, and other floral microbes, with significant implications for plant and pollinator health. Interactions between floral microbes and pollinators are critically important to understand, as pollinators provide important ecosystem services in both natural and agriculture systems. Here, I explored how floral nectar traits affected both evolution and competition within the floral yeast Metschnikowia reukaufii, the floral bacterium Bacillus subtilis, and other microbes isolated from Brassica rapa nectar, an important plant model system and oilseed crop. To …

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 …

Refining, Testing, And Applying Thermal Species Distribution Models To Enhance Ecological Assessments, Donald J. Benkendorf

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

The temperature of streams and rivers is changing rapidly in response to a variety of human activities. This rapid change is concerning because the abundances and distributions of many aquatic species in streams and rivers are strongly associated with temperature. Linking observations of temperature effects on species distributions with observations of temperature effects on fitness is important for improving confidence that temperature (and not some other variable) is causing the distributions we observe. Furthermore, producing accurate models of temperature effects on species distributions may allow us to develop tools to diagnose whether or not thermal pollution has impaired aquatic life. …

Global Change Effects On Carbon Cycling In Terrestrial Ecosystems, Guopeng Liang

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Since terrestrial ecosystems store approximately 3 times more carbon (C) than the atmosphere, they have a significant effect on the atmospheric CO₂ concentration. Although many studies have been conducted to determine global change effects on C cycling in terrestrial ecosystems, the underlying mechanisms remain uncertain. To address this knowledge gap, I utilized meta-analysis, laboratory experiments, and soil microbial community analysis.

In chapter 2, I conducted a meta-analysis to examine whether effects of long-term N addition on plant productivity can shift over time. I found that 44% of studies showed a marked trend (increase or decrease) in the strength of …

Forecasting Fine Fuels In The Intermountain West Rangelands, Mira Ensley-Field

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

The objective of this thesis project was to develop a fine fuels forecast to help fire managers anticipate spatial variation in fuel loads before the start of the fire season. In Chapter 1 we compile and analyze the methodologies of the historical record of fine fuel loads reported to the Great Basin Coordination Center. Based on our data analysis, we developed a series of recommendations for improving the methods used to sample fine fuels in the future as well as more broad ideas for how land managers can use emerging technologies to more effectively monitor fine fuels. In Chapter 2, …

Oystershell Scale: An Invasive Threat To Aspen Conservation, Amanda M. Grady, Connor D. Crouch, Nicholas P. Wilhelmi, Richard W. Hofstetter, Kristen M. Waring

Aspen Bibliography

Aspen decline is an acute and chronic problem in Arizona, where high levels of overstory mortality and a lack of recruitment continue to be observed. Oystershell scale (Lepidosaphes ulmi; OSS), an invasive sapsucking insect, has recently become widespread in native aspen stands in the southwestern U.S., further contributing to aspen mortality. Damage is severe in lower elevation stands and within ungulate exclosures created to conserve aspen. Young recruiting aspen that are rare on the landscape incur high levels of OSS-caused mortality when infested (Fig. 1). OSS has only recently become a pest of concern in the Southwest and …

Carnivoran Frugivory And Its Effect On Seed Dispersal, Plant Community Composition, Migration, And Biotic Carbon Storage, John P. Draper

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Seed dispersal by animals is important for the ecology of plants. It is particularly important to understand which animals are involved and how they move seeds differently from one another. Some seed dispersers are understudied despite ample evidence they consume fruits and seeds. This includes animals commonly referred to as carnivores in the order Carnivora. The overall goal of my dissertation was to describe the extent and quality of seed dispersal by Carnivorans, estimate important aspects of seed dispersal for a specific Carnivoran, the coyote, and estimate how differences between a coyote and songbirds affect where plants …

Nutrient Uptake And Water Quality In Great Salt Lake Wetland Impoundments, Rachel L. Buck

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

The Great Salt Lake (GSL) is the largest inland body of water on the Pacific flyway, a major pathway for migratory birds in the Americas that extends from Alaska to Patagonia. The lake is surrounded by approximately 360,000 acres of wetlands, providing critical food, shelter, cover, nesting areas, and protection to between 4–6 million birds that visit each year. Impounded wetlands were created as part of the GSL ecosystem to support waterfowl habitat. These large, shallow, submergent wetlands are diked to control water levels to sustain aquatic plants which are an important food source. Besides providing critical habitat, these impoundments …

Quantifying The Indirect Effect Of Wolves On Aspen In Northern Yellowstone National Park: Evidence For A Trophic Cascade?, Elaine M. Brice

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Yellowstone National Park is renowned for its incredible wildlife, and perhaps the most famous of these species is the gray wolf, which was reintroduced to the Park in the mid-1990s. After reintroduction, it was highly publicized by scientists, journalists, and environmentalists that the wolf both decreased elk density and changed elk behavior in a way that reduced elk effects on plants, a process known as a “trophic cascade.” Aspen, which is eaten by elk in winter, is one species at the forefront of Yellowstone trophic cascade research because it has been in decline across the Park for over a century. …

The Effects Of Seed Mix Composition, Sowing Density, And Seedling Survival On Plant Community Reassembly In Great Salt Lake Wetlands, Rae Robinson

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Wetlands are known for their valuable benefits (e.g., providing habitat, improving water quality, lessening the negative impacts of drought and flooding). Invasive wetland plant species are species that cause harm to ecosystems, the economy, or human health, and replace native wetland plant communities. The revegetation of native plants may be one way to improve wetlands that have been impacted by invasive species. In Great Salt Lake (Utah, USA) wetlands, the invasive, non-native grass Phragmites australis (common reed) reduces the quality and quantity of habitat for both wildlife and humans (e.g., birdwatchers, waterfowl hunters). Even when P. australisis greatly reduced, native …

Detecting Ecosystem Response To Restoration Efforts With Implications For Recovery Of The Threatened June Sucker (Chasmistes Liorus) In A Shallow, Eutrophic, Utah Lake, Ryan D. Dillingham

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Environmental damage associated with a growing human population will increase globally without active management. Restoration can promote ecosystem recovery, yet often fails to produce desired results and may require decades to achieve noticeable benefits. Detecting small, incremental change sis imperative in these difficult situations. Here, I demonstrate that restoration focused on fish removal triggers incremental responses in aquatic plants and animals. Removing common carp is expected to encourage recovery of aquatic plants, increasing animal habitat, resulting in more macroinvertebrates (e.g., aquatic insects, snails). Carp removal should also increase water clarity, improving visibility for fishes, thus increasing their ability to find …

Characterizing The Migratory Phenology And Routes Of The Lazuli Bunting (Passerina Amoena) In Northern Utah, Kim Savides

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Migratory species time their movements to follow changes in food and environmental resources throughout the year. Despite the ubiquity of migration in birds, little is still known about how birds select routes and time migrations. Recent advancements in miniaturized tracking devices now allow tracking of small birds throughout their annual life cycle, presenting opportunities for migratory ecology research at scales immeasurable in the past. Here we investigated the migratory ecology of a northern Utah, USA breeding population of Lazuli Bunting, a common songbird in western North America for which few migratory studies have been completed. We sought to compare breeding …

Efficacy Of Conservation Actions For Imperiled Colorado River Fishes In The Grand Canyon, Arizona, Brian D. Healy

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Many fishes are critically imperiled, particularly in their native rivers, due to human water use and dam construction, which can dramatically alter habitats and block fish migratory routes. The introduction of invasive sport-fishes that prey on native fish further threatens native species that maybe restricted to only a single river basin (i.e., “endemic”). To preserve native fishes in river systems with degraded habitats, managers need to understand the effects of conservation actions to ensure limited resources are applied effectively. Two commonly applied native fish conservation actions include removal of invasive fishes, and translocations of native fish from one place into …

Emulating Succession Of Boreal Mixedwood Forests In Alberta Using Understory Protection Harvesting, Ivan Bjelnanovic, Philip G. Comeau, Sharon Meredith, Brian Roth

Aspen Bibliography

Understory protection harvesting is a form of partial cutting that can be used in aspen (Populus tremuloides Michx.)-dominated stands that have understories of white spruce (Picea glauca (Moench) Voss). This practice involves removing 75% to 85% of the merchantable aspen while minimizing damage to the advance spruce regeneration, in addition to leaving 15% to 25% of the aspen standing to reduce potential windthrow of the spruce understory. In this paper, we summarize results from 18 stands measured 10 to 12 years after understory protection harvest. Diameter growth of spruce increased during the first five years after harvest while …

Plant-Soil Feedbacks Help Explain Plant Community Productivity, Andrew Kulmatiski, Jeanette Norton, Leslie E. Forero, Josephine Grenzer

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Plant community productivity tends to increase as species richness increases, but the mechanisms behind this biodiversity-productivity relationship are not fully understood. Plant-soil feedbacks (PSF) are a compelling potential mechanism of the biodiversity-productivity relationship because they can explain patterns of both underyielding and overyielding in diverse plant communities. To test the role of plant-soil feedbacks in the biodiversity-productivity relationship we measured all possible plant-soil feedbacks for sixteen species, and used the measured plant-soil feedbacks to predict plant community biomass production. We compared the predicted plant community biomass production to observed biomass production in a paired biodiversity-productivity experiment.

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 …

Facilitation Differentially Affects Competitive Responses Of Aspen And Subalpine Fir Through Stages Of Stand Development, Rebecca Lee Molinari, Matthew F. Bekker, Benjamin D. St. Clair, Jason Bartholomew, R. Justin Derose, Stanley G. Kitchen, Samuel B. St. Clair

Aspen Bibliography

Spatial interactions between trees influence forest community succession. The objective of this study was to investigate how shifts in forest composition and proximity between tree species affect stand development over time in mixed forest systems. At six locations across the Fishlake National Forest, Utah, USA, in stands where facilitation has been documented previously, tree-ring samples were collected from aspen and subalpine fir trees. Basal area increment was calculated to characterize the effects of the proximity of overstory trees on multidecadal growth responses of aspen and subalpine fir in aspen-dominant and mixed aspen–conifer stands. Subalpine fir seedlings were established next to …

Sex-Related Differences In Aging Rate Are Associated With Sex Chromosome System In Amphibians, Hugo Cayuela, Jean-François Lemaître, Jean-Paul Léna, Victor Ronget, Iñigo Martínez-Solano, Erin Muths, David S. Pilliod, Benedikt R. Schmidt, Gregorio Sánchez-Montes, Jorge Gutiérrez-Rodríguez, Graham Pyke, Kurt Grossenbacher, Omar Lenzi, Jaime Bosch, Karen H. Beard, Lawrence L. Woolbright, Brad A. Lambert, David M. Green, Nathalie Jreidini, Justin M. Garwood, Robert N. Fisher, Kathleen Matthews, David Dudgeon, Anthony Lau, Jeroen Speybroeck, Rebecca Homan, Robert Jehle, Eyup Başkale, Emiliano Mori, Jan W. Arntzen, Pierre Joly, Rochelle M. Stiles, Michael J. Lannoo, John C. Maerz, Winsor H. Lowe, Andrés Valenzuela-Sánchez, Ditte G. Christiansen, Claudio Angelini, Jean-Marc Thirion, Juha Merilä, Guarino R. Colli, Mariana M. Vasconcellos, Taissa C.V. Boas, Ísis Da C. Arantes, Pauline Levionnois, Beth A. Reinke, Cristina Vieira, Gabriel A.B. Marais, Jean-Michel Gaillard, David A.W. Miller

Wildland Resources Faculty Publications

Sex‐related differences in mortality are widespread in the animal kingdom. Although studies have shown that sex determination systems might drive lifespan evolution, sex chromosome influence on aging rates have not been investigated so far, likely due to an apparent lack of demographic data from clades including both XY (with heterogametic males) and ZW (heterogametic females) systems. Taking advantage of a unique collection of capture–recapture datasets in amphibians, a vertebrate group where XY and ZW systems have repeatedly evolved over the past 200 million years, we examined whether sex heterogamy can predict sex differences in aging rates and lifespans. We showed …

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 …