Ecology and Evolutionary Biology Commons^™

Assessing Long-Term Changes In Aspen Forest Cover In Northern Yellowstone National Park Before And After Carnivore Recovery, Nicholas J. Bergeron

All Graduate Theses and Dissertations, Fall 2023 to Present

The recovery of large carnivores (wolves, bears, cougars) in Yellowstone National Park and the subsequent decline of the area's elk herd have raised key questions about ecosystem restoration—particularly for species such as aspen, which are heavily browsed by elk. Following wolf reintroduction in the mid-1990s, scientists began tracking changes in browsing intensity and height of young aspen within sampling plots, assuming reduced browsing and taller stems were signs of population recovery. However, no studies have measured whether the total area covered by aspen stands actually increased, as would be expected with broader recovery. Moreover, the potential influence of climate change …

Changing Aspen Stand Structure Following Large Carnivore Restoration In Yellowstone, Luke E. Painter, Robert L. Beschta, William J. Ripple

Aspen Bibliography

Restoration of large carnivores in northern Yellowstone National Park in the late 20th century resulted in a sustained reduction of Rocky Mountain elk (Cervus canadensis) and their herbivory, facilitating new growth of quaking aspen (Populus tremuloides) saplings. In 2020–21, we examined 87 randomly selected, previously sampled aspen stands across northern Yellowstone, combining random plots with stand-wide observations. Forty-three percent of stands contained a new cohort of small trees (5–10 cm dbh), the first documented recruitment of overstory aspen trees in northern Yellowstone since the 1940s. Both aspen saplings ( ≥2 m tall) and small trees were …

Post-Wildfire Erosion And Sedimentation: An Escalating Threat For Utah Fisheries, Colton James, Kendall Becker, Scott Hotaling, Aish Chandrasekaran, Alex Fiedler, Timothy E. Walsworth, Patrick Belmont

All Current Publications

Wildfires are a natural part of the western U.S. landscape and provide numerous benefits, including enhanced nutrient cycling and habitat rejuvenation. Utah’s fish populations evolved with wildfire as a common disturbance. However, the increasing size and severity of wildfires, combined with Utah’s heavily engineered and fragmented stream networks, pose a contemporary risk to fish populations. This fact sheet reviews wildfire impacts on erosion and Utah's watersheds and fisheries. It outlines measures we can take to prevent post-wildfire fish die-offs.

Canopy Insect Communities Are Shaped By The Genes And Phenotypes Of Their Aspen Hosts, Clay J. Morrow, Jennifer Lind-Riehl, Christopher T. Cole, Kennedy Rubert-Nason, Cécile Ané, Richard L. Lindroth

Aspen Bibliography

1. Community genetics research aims to identify genetic and phenotypic mechanisms that shape communities as extended phenotypes. To date, most progress has been made identifying variation in herbivore communities associated with intraspecific variation in plants, with little focus on identifying specific genes or traits responsible for that variation. Here, we identify how extended phenotype variation of a foundation tree species, Populus tremuloides, arises from trait variation among individuals and specific genes. 2. We quantified heritability for 13 tree traits -- including phenology, defense chemistry, reproduction, and morphology -- and for 18 associated insect species (640,557 individuals). We performed genomic …

Aspen Impedes Wildfire Spread In Southwestern United States Landscapes, Matthew P. Harris, Jonathan D. Coop, Jared A. Balik, Jessika R. Mcfarland, Sean A. Parks, Camille S. Stevens-Rumann

Aspen Bibliography

Aspen (Populus tremuloides) forests are generally thought to impede fire spread, yet the extent of this effect is not well quantified in relation to other vegetation types. We examined the influence of aspen cover on interpolated daily fire spread rates, the relative abundance of aspen at fire perimeters versus burn interiors, and whether these relationships shifted under more fire-conducive atmospheric conditions. Our study incorporated 314 fires occurring between 2001 and 2020 in the southwestern United States and a suite of gridded vegetation, topography, and fire weather predictor variables. We found that aspen slows fire progression: as aspen cover …

Bite By Bite: How Ungulate Browsing Shapes North America's Forest Future, Darius Hardalau, Vladut Stefanescu, Mindaugas Bakševičius, Michael Manton, Charles Ruffner, Gediminas Brazaitis, Georgeta Ionescu, Ovidiu Ionescu

Aspen Bibliography

Ungulate browsing represents a contemporary issue for forest development, influencing forest regeneration, composition, and management practices across the world, especially in North America. This review synthesizes findings from 101 studies conducted between 1980 and 2025 to examine patterns of herbivory damage through browsing by moose, elk, white-tailed deer, black-tailed deer, and bison. Despite regional variation, high ungulate density consistently emerges as the primary factor driving browsing intensity and ecological and economic impact, leading to decreased social acceptance of coexistence with ungulates. This review highlights the selective suppression of palatable species such as balsam fir, red oak, and white cedar, leading …

Cutthroat Trout In Utah, Hope Northagen, Ethan Gilliam

All Current Publications

This fact sheet is intended to inform anglers, aquatic recreationalists, and backyard conservationists interested in learning about a Utah native species, current restoration steps, and how their actions can help professionals restore native cutthroat trout populations.

The Perfect Pairing: Early Stand Dynamics In Conventional Aspen And Mixedwood Forests In Northern Minnesota, Usa, Chelsea C. Semper, John M. Zobel, Sawyer S. Scherer, Michael R. Reinikainen, Matthew B. Russell, Tyler S. Gifford, Marcella A. Windmuller‑Campione

Aspen Bibliography

In North America, mixedwood management is being increasingly considered by natural resource managers as an alternative to single species management for a variety of ecological, economic, and cultural reasons. In northern Minnesota, USA, natural resource managers are increasingly using treatments to establish mixedwood forests in aspen (Populus tremuloides Michx, Populus grandientata Michx) dominated ecosystems by planting white spruce (Picea glauca (Moench). However, little quantitative information is known regarding differences between stand structure and composition in conventional aspen and aspen-white spruce during early stand development. To provide greater clarity for managers, we sampled 40 aspen stands across a chronosequence …

Influence Of Increasing Fires On Mixed Conifer Stand Dynamics In The U.S. Southwest, Simon D. Baker, Kristen M. Waring, David Auty, Nicholas Wilhelmi

Aspen Bibliography

(1) Stand-replacing fires may threaten the continued stability of mixed conifer forests in the U.S. Southwest. Increasing fire frequency and severity have made post-fire forest recovery trajectories uncertain for many coniferous species, potentially leading to long-term shifts in forest structure and composition. (2) The purpose of this study was to examine post-fire stand dynamics over a 10-year period, using a network of permanent plots established prior to wildfire events across Arizona and New Mexico. We assessed changes in over story composition, regeneration, and fuel loading across different fire severities. (3) High severity fire caused near-total over story mortality, with little …

Experiments To Enhance Post-Fire Aspen Seedling Survival And Growth, Larissa L. Yocom, Mark R. Kreider, Owen T. Burney, Tammy Parsons, Ryan T. Choi, Emily K. Liese, Karen E. Mock

Aspen Bibliography

Aspen forests provide wildlife, watershed, and aesthetic value, and the potential for reduced fire occurrence, behavior, and severity. There is interest in planting aspen to achieve various management objectives. However, few studies have investigated the optimal conditions for aspen seedlings in the western US. We conducted two experiments to address this knowledge gap. First, we tested the effects of shading structures (i.e., logs) and biochar on the survival and growth of 960 outplanted aspen seedlings in three exclosures in a recent fire footprint. Second, we tested whether experimentally placing logs near 120 naturally-occurring post-fire aspen seedlings affected survival or growth. …

Sexual And Vegetative Recruitment Of Trembling Aspen Following A High-Severity Boreal Wildfire, Denyse A. Dawe, Ellen Whitman, Michael Michaelian, Alan J. Tepley, Marc-André Parisien

Aspen Bibliography

Background High-severity fire is rare in trembling aspen-dominated forests of the boreal region. The post-fire recruitment strategy of aspen, by either vegetative suckering or sexually (i.e., by seed), has considerable implications for subsequent forest structure, genetic diversity, and ecological resilience to shifting climatic and disturbance regimes. In this study, we take advantage of the unique opportunity provided by the Chuckegg Creek Wildfire Fire (310,000 ha) in northern Alberta, Canada, which burned at high severity through aspen stands before and after spring green-up, to document how phenology, fire severity, and stand characteristics affect recruitment one year following the fire.

Results We …

Factors Impacting The Variability Of Post-Fire Forest Regeneration In Central European Pine Plantations, Florent Jouy, Maren Schüle, Yojana Adhikari, Anja Binder, Danica Clerc, Werner Gerwin, Thilo Heinken, Thomas Raab, Frank Repmann, Susanne Rönnefarth, Marina Schirrmacher, Marie-Therese Schmehl, Jens Schröder, Pierre L. Ibisch

Aspen Bibliography

Fire is increasingly posing a risk to forests and plantations, even in the temperate latitudes of central Europe. Little is known about fire ecology in this region, and therefore, appropriate approaches for the management and reforestation of burned sites are mostly lacking. In a Scots pine plantation region in Brandenburg (northeast Germany), the early tree regeneration of two nearby areas that burned 1 year apart was investigated. We observed that 3 years after the fire events, the forest in one study area showed a relatively high regeneration with a mean density of 7765 saplings/ha, clearly dominated by European aspen (93%); …

Causes Of Heterozygosity Excess: The Case Of Mexican Populations Of Populus Tremuloides, Javier Hernández-Velasco, José Ciro Hernández-Díaz, Sergio Leonel Simental-Rodríguez, Juan P. Jaramillo-Correa, David S. Gernandt, José Jesús Vargas-Hernández, Ilga Porth, Roos Goessen, M. Socorro Gonzáles-Elizondo, Matthias Fladung, Cuauhtémoc Sáenz-Romero, José Guadalupe Martínez-Ávalos, Artemio Carrillo-Parra, Eduardo Mendoza-Maya, Arnulfo Blanco-García, Christian Wehenkel

Aspen Bibliography

The presence of heterozygous individuals in a population is crucial for maintaining genetic diversity, which can positively affect fitness and adaptability to environmental changes. While inbreeding generally reduces the proportion of heterozygous individuals in a population, polyploidy tends to increase the proportion. North American Populus tremuloides is one of the most widely distributed and ecologically important tree species in the Northern Hemisphere. However, genetic variation in Mexican populations of P. tremuloides, including the genetic signatures of their adaptation to a variety of environments, remains largely uncharacterized. The aim of this study was to analyze how inbreeding coefficient (F …

Gone With The Flow: Flow Reduction Coincides With Reduced Metabolism And Standing Stock Of Benthic Algae And Macroinvertebrates In Desert Rivers, Chloe E. Lyles

All Graduate Theses and Dissertations, Fall 2023 to Present

River metabolism, the measure of energy flow in a river, is driven by hydrological and physicochemical regimes (e.g., temperature, turbidity, and nutrients). However, these regimes are increasingly altered by human water demand and climate change-driven drought. These stressors alter the magnitude, timing, and duration of critical spring-snowmelt floods with poorly understood consequences on ecosystem function, particularly in desert rivers. To investigate the linkages between flow reduction, river metabolism, and basal food resource productivity (i.e., algae and aquatic invertebrates), we measured metabolism and basal resource availability in seven desert tributaries with varying degrees of flow reduction during low-flow conditions in 2023 …

Maximizing Dryland Seed-Based Restoration Success Via Retrospective Analyses Of Species-Use Patterns And Field Testing Of Seed Mix Composition, Spencer J. Good

All Graduate Theses and Dissertations, Fall 2023 to Present

Due to harsh and variable environmental conditions, successful plant establishment in "dryland" ecosystems – areas with scarce precipitation – is a major challenge for restoration. One of the most important decisions influencing restoration outcomes is choosing which species to plant (i.e., species selection). Here I explored two opportunities to improve restoration success related to species selection. First, I examined recent restoration projects across Utah, USA to understand species selection patterns by site conditions (e.g., precipitation, elevation) and seed costs, and to identify tools for matching species to sites. Second, I tested how commonly used non-native species – those not originally …

Agrichemical Surfactant And Pathogen Impacts On The Blue Orchard Bee (Osmia Lignaria Say, Hymenoptera: Megachilidae), Mary-Kate F. Williams

All Graduate Theses and Dissertations, Fall 2023 to Present

Pathogens that infect commercially reared bee species, such as honey bees and bumble bees, have been extensively studied within the last several years, and studies that explore pathogen impacts on solitary bee health are significantly fewer. Consistent pesticide exposure methods are limited to honey bees and do not outline exposure routes to solitary bees, including how to test chemical impacts on immature stages. My research investigated blue orchard bee survival, development, and immune response following pathogen exposure while simultaneously studying organosilicone surfactant (OSS) exposure and possible synergisms between these two stressors. In my first research chapter (Chapter 2), I define …

Potamogeton Crispus Invasion: Impacts On Native Aquatic Plants And Associated Faunal Habitat, Meghan-Grace Slocombe

All Graduate Theses and Dissertations, Fall 2023 to Present

Aquatic invasive plants are non-native plants that invade a water body and displace native aquatic plants. Invasion depletes the native plant community's ability to provide ecosystem services, including improved water quality, decreased problematic algae, and increased animal habitat. The loss of these ecosystem services reduces the value of fishing, boating, and swimming opportunities in aquatic ecosystems. The potential changes in plant communities and services are particularly important at sites targeted for restoration because project goals typically include increasing ecosystem services, including wildlife habitat. Curly-leaf pondweed (Potamogeton crispus L.) is a problematic invasive species in North America. To better manage …

Below-Ground Carbon Gradients Surrounding Saskatchewan's Native Agricultural Copses, Andrea V. Cline, Colin P. Laroque

Aspen Bibliography

As carbon markets develop, understanding the carbon storage capabilities of agricultural land is imperative to maximizing carbon storage. Ecosystems store two-thirds of their carbon below ground. Shrubland and shelterbelt carbon storage have been well documented in agricultural settings, yet little is known about the carbon stored under the native woody vegetation scattered across the Prairies. This study aims to be the first to quantify the below-ground carbon under and around these native trembling aspen (Populus tremuloides) copses in the Canadian Prairies. For this study, the leaf, fibric, humic layer (LFH) and soil samples up to 60cm were collected …

Avian Detection Data And Environmental Covariates For Utah, Usa Over The Years 2017-2021, Amanda L. Hayes-Puttfarcken

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Integrated Monitoring in Bird Conservation Regions (IMBCR) detection data for the state of Utah, USA, and LANDFIRE uncharacteristic exotic Departure Score data over Utah during our study period, as well as additional environmental covariates used to make the model more ecologically accurate. Environmental covariates include average May precipitation, average June temperature, distance to the nearest road, percent canopy cover, and the percent of three habitat types as defined by LANDFIRE; open tree canopy, herbaceous, and shrubland.

Effectiveness Of Silvicultural Options In Renewal Of Trembling Aspen–Jack Pine Mixedwood Stands, 21 Years After Treatment, Rongzhou Man

Aspen Bibliography

Regenerating conifers after harvest through planting and postharvest broadcast application of herbicide is effective in ensuring the survival and growth of seedlings, but faces challenges in meeting broad social and ecological objectives of forest management. This study reports the effectiveness of alternative options in regenerating jack pine (Pinus banksiana Lamb.), 21 years after harvest of trembling aspen (Populus tremuloides Michx.)-dominated boreal mixedwood stands. The treatment options included (i) preharvest spray—aerial broadcast spray prior to harvest, (ii) postharvest partial spray—ground herbicide application in strips, (iii) partial harvest in strips, (iv) postharvest aerial broadcast, and (v) uncut reference. Twenty-one years …

Drivers Of Recruitment For A Population Of Cutthroat Trout In Northern Utah, Abbigail Lane, Austin Garner

Student Research Symposium

• Understanding recruitment dynamics informs effective management of sensitive populations (Camp et al. 2020).

Ecological Restoration And Ecosystem Memory Of Wildlife Forage And Understory Diversity In A Young Pine Monoculture Plantation In Central-Interior British Columbia, Julia Claire Bizon

Aspen Bibliography

Ecological restoration has recently taken center stage in the rehabilitation of degraded forest ecosystems to improve multifunctionality, biodiversity, and wildlife habitat conservation. The research summarized herein assessed the efficacy of variable stand density thinning (200, 400, and 600 stems/ha) and artificial canopy gaps (0.2, 0.5, 1.0, 2.0 ha in size) as potential restoration treatments to enhance wildlife forage and native biodiversity in a young lodgepole pine (Pinus contorta var. latifolia Engelm. ex S. Wats.) forest in central-interior British Columbia. Field data collection was conducted from May-August, 2023 to assess the early response (1-3 years post-treatment) of the forest …

Aspen Health On National Forests In The Northern Rocky Mountain Region (2008/2009 To 2024), James T. Blodgett, Kurt K. Allen, Megan Wilson, Bradley Lalande

Aspen Bibliography

Quaking aspen (Populus tremuloides) is a widely distributed species in the western United States, but in the northern Rocky Mountain Region it is a rare forest component. In national forests (NF) of the northern Rocky Mountain Region this species comprises only 1% of the Bighorn, 3% of the Black Hills, and 1% of the Shoshone cover types (DeBlander 2002, Menlove 2008, Witt 2008). Since aspen forests provide increased species richness, support wildlife, are an important component of watersheds, and have aesthetic value, there are concerns regarding the health of this relatively rare forest cover type.

Contrasting Effects Of Climate Warming On Hosts And Parasitoids: Insights From Rocky Mountain Aspen Leaf Miners And Their Parasitoids, Alisha A. Shah, Emily Hamant, Juan G. Rubalcaba, Beau Larkin, Andrew A. Forbes, H. Arthur Woods

Aspen Bibliography

Because temperature has pervasive effects on biological rates, climate warming may alter the outcomes of interactions between insect hosts and their parasitoids, which, for many host species, constitute the single largest source of mortality. Despite growing interest in parasitoid-host responses due to climate change, there are few empirical tests of thermal tolerance differences between non-model lepidopteran hosts and their parasitoids and almost none from mountain ecosystems where warming is occurring more rapidly. We examined the thermal ecology of a host–parasitoid interaction in the Rocky Mountains using the wild populations of the aspen leaf miner (Phyllocnistis populiella) and a …

Draft Genome Data Including Functional Annotation Of An Emerging Fungal Pathogen (Neodothiora Populina) Causing A Canker Disease Of Trembling Aspen In Interior Alaska, Ursel M. E. Schütte, Mace Wages, Aaron Buechlein, Jorda P. Kovash, Danielle C. Wrenn, Tereza Smrhova, Andrea Zubrova, Doug B. Rusch, Loretta M. Winton, Gerard C. Adams, Roger W. Ruess, Mary Beth Leigh, Devin M. Drown

Aspen Bibliography

Neodothiora populina is a black yeast-like fungus in the family Dothioraceae. It causes an aggressive canker disease of trembling aspen that results in widespread mortality of aspen across the boreal forest of Interior Alaska. Here we report a high-quality draft genome including functional annotation of this emerging fungal pathogen based on Oxford Nanopore Technologies long-read sequences. Our initial genome assembly totaled 23,960,169 bp and contained 18 contigs, and we identified 7,343 genes. This resource announcement provides new genomic data that are useful long term for improving our understanding of forest health in Alaska.

Elevated Extinction Risk In Over One-Fifth Of Native North American Pollinators, Tara Cornelisse, David W. Inouye, Rebecca E. Irwin, Sarina Jepsen, Jonathan R. Mawdsley, Margaret Ormes, Jaret Daniels, Diane M. Debinski, Terry Griswold, John Klymko, Michael C. Orr, Leif Richardson, Nicole Sears, Dale Schweitzer, Bruce E. Young

Biology Faculty Publications

Pollinators are critical for food production and ecosystem function. Although native pollinators are thought to be declining, the evidence is limited. This first, taxonomically diverse assessment for mainland North America north of Mexico reveals that 22.6% (20.6 to 29.6%) of the 1,579 species in the best-studied vertebrate and insect pollinator groups have elevated risk of extinction. All three pollinating bat species are at risk and bees are the insect group most at risk (best estimate, 34.7% of 472 species assessed, range 30.3 to 43.0%). Substantial numbers of butterflies (19.5% of 632 species, range 19.1 to 21.0%) and moths (16.1% of …

Bryce Canyon Aspen: Recent Trends, Future Actions, Paul C. Rogers

Aspen Bibliography

In cooperation with Bryce Canyon National Park, we undertook a survey of quaking aspen (Populus tremuloides Michx.) conditions throughout the Park with the intention of better understanding conditions and prescribing corrective measures where needed. There are clear disparities within the Park between sustainable aspen conditions and failing stands. Based on condition of mature trees, but most importantly regeneration and recruitment of juvenile stems, most aspen forests within Bryce Canyon are in poor condition. Aspen recruitment—generally sapling-sized trees that have survived browsing ungulates—is the most important metric of future stand resilience and here we found 83% of all aspen sample …

Changing Fire Regimes In The Great Basin Usa, Eva K. Strand, Kori Blankenship, Corey Gucker, Mark Brunson, Eugénie Montblanc

Aspen Bibliography

Wildfire is a natural disturbance in landscapes of the Western United States, but the effects and extents of fire are changing. Differences between historical and contemporary fire regimes can help identify reasons for observed changes in landscape composition. People living and working in the Great Basin, USA, are observing altered fire conditions, but spatial information about the degree and direction of change and departure from historical fire regimes is lacking. This study estimates how fire regimes have changed in the major Great Basin vegetation types over the past 60 years with comparisons to historical (pre-1900) fire regimes. We explore potential …

Drought Resilience And Legacy Effects In Two Forest Tree Species On Loess Plateau Of China: Growth And Water-Use Efficiency Under Different Drought Conditions, Lu Han, J. Julio Camarero, Guodong Jia, Zhiqiang Zhang, Lixin Chen

Aspen Bibliography

As droughts become more frequent and severer, understanding tree resilience and its role in mediating drought legacy effects (LEs) is critical for predicting forest ecosystem responses to future droughts and informing forest management. Both Pinus tabuliformis and Populus davidiana are widely distributed in the Loess Plateau region of western China and play important roles in provision of ecosystem services. In this study we quantified the LEs and resilience, including resistance (Rt) and recovery (Rc), of radial growth (BAI, basal area increment) and intrinsic water use efficiency (iWUE) of the two species, determined the external and internal factors influencing Rt and …

Lake Powell Fish Sampling: Glen Canyon Dam Forebay Area, 2022 And 2023, Phaedra Budy, Casey Pennock

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Native fishes face imperilment due to habitat loss and fragmentation, megadrought, invasive species, and synergies amongst threats. These threats coalesce at Glen Canyon Dam (GCD), which impounds the Colorado River to create Lake Powell, a reservoir inhabited by a suite of nonnative fishes. Water level in Lake Powell has declined precipitously due to water overallocation and megadrought, increasing the risk of nonnative fish entrainment through the dam, as the penstocks draw water from the epilimnion. Our goal was to characterize the distribution and abundance of nonnative fishes in the vicinity of GCD and identify environmental conditions that may increase entrainment. …