Forest Sciences Commons^™

Wildfire And Fuel Treatments In Utah: A Practical Guide And Outcomes From An Oak-Maple Ecosystem, Annie E. Prescott

All Graduate Theses and Dissertations, Fall 2023 to Present

Wildfire is a natural part of Utah’s landscapes, but as wildfires become more extreme and communities continue to expand into wildland areas, it is increasingly important to understand how wildfires behave and how their negative effects can be mitigated. One way to reduce wildfire risks and protect life, property, and ecosystem services is through fuel treatments — actions that reduce the amount and arrangement of flammable vegetation through mechanical removal, wildland fire, or other methods.

Information on wildfire behavior and fuel treatments is abundant but often scattered, ecosystem-specific and difficult to access. In addition, most research in the Western U.S. …

Quaking Aspen On Cedar Mountain, Utah: Status And Update, Jaycee Cappaert, Larissa L. Yocom, Paul C. Rogers, Darren J. Mcavoy, R. Justin Derose

Wildland Resources Student Research

Quaking aspen forests are important communities in the western United States where they provide preferential food and habitat for animals, limit wildfires from spreading, and have favorable aesthetics, among other things. Their putative decline is an issue for ecology and management. We remeasured the aspen population on Cedar Mountain, Utah, to assess changes to its condition since it was originally measured in 2008 and laid the groundwork for continued aspen monitoring on Cedar Mountain. Our objectives were to compare current metrics of stand structure and composition, mortality, crown dieback, bole damage, regeneration, and recruitment, to those of the original inventory. …

Alternative Tree Species For Utah Syrup Production, Abigail Porter, Steven Price, Youping Sun, Darren Mcavoy

All Current Publications

When thinking about producing syrup from trees, most people's minds go straight to maple trees. However, a variety of other species in the Intermountain West can be tapped for sap, including other maple species, birch, sycamore, aspen, and walnut. This fact sheet reviews alternative tree species for syrup production in Utah.

Dusky Grouse Seasonal Resource Selection In The Great Basin Isolated Mountain Ranges Of Nevada, Usa, Stephanie Landry, Brian Smith, Erica Stuber, Shawn Espinosa, David Dahlgren

Aspen Bibliography

Dusky grouse Dendragapus obscurus are a montane forest grouse species with a paucity of information regarding their temporal and spatial resource use during critical times of high mortality and reproductive output. This lack of vital data may leave dusky grouse at risk of sub-optimal management in many areas of their distribution, especially in the isolated ‘sky island’ mountain ranges of the Great Basin, where high elevation habitats are surrounded by sagebrush and salt desert shrub land flats. Many of these high elevation habitats are being altered and lost rapidly from increasing disturbance events and effects of climate change. Our objective …

Flawed Analysis Invalidates Claim Of A Strong Yellowstone Trophic Cascade After Wolf Reintroduction: A Comment On Ripple Et Al. (2025), Dan R. Macnulty, David Cooper, Michael Procko, T.J. Clark-Wolf

Aspen Bibliography

Ripple et al. (2025) recently argued that large carnivore recovery in Yellowstone National Park triggered one of the world’s strongest trophic cascades, citing a ∼1500 % increase in willow crown volume derived from plant height data. In this comment, we show that their conclusion is invalid due to fundamental methodological flaws. These include use of a tautological volume model, violations of key modeling assumptions, comparisons across unmatched plots, and the misapplication of equilibrium-based metrics in a non-equilibrium system. Additionally, Ripple et al. rely on selectively framed photographic evidence and omit critical drivers such as human hunting in their causal attribution. …

Where The Buffalo Roam: Ungulate Influences On Quaking Aspen And Willow Communities In The Greater Yellowstone Ecosystem, J. Boone Kauffman, Dian L. Cummings, Robert L. Beschta, William J. Ripple

Aspen Bibliography

Quaking aspen (Populus tremuloides) and willows (Salix spp.) are keystone species of montane and shrub-steppe landscapes of the Western United States. Intact communities dominated by these species provide a wide range of ecosystem services, harboring an exceptional proportion of landscape biodiversity. Land use, especially overgrazing by large ungulates, is among the greatest threats to these ecosystems. To examine the effects of wild ungulates and levels of grazing at Yellowstone National Park (YNP) and the adjacent Gallatin National Forest, we sampled plant community composition and vegetation structure of aspen and willow communities both inside and outside of exclosures. …

Relaxation Of The Leaf Economics Spectrum Within And Across Quaking Aspen Populus Tremuloides Genotypes, Jolanta Rieksta, Bente J. Graae, Kenny Helsen, Rozália E. Kapás, Richard Strimbeck, Benjamin W. Blonder

Aspen Bibliography

Plant functional traits typically show strong covariation, e.g. as in the worldwide leaf economics spectrum (LES). Covariation is thought to arise from selective forces and physical constraints. However, processes shaping covariation at interspecific scales may differ from those at intraspecific scales. Potential sources of intraspecific trait variation include variation in genetics, abiotic environment, and biotic environment; any of these factors may cause divergence from interspecific patterns. Quaking aspen, Populus tremuloides (Salicaceae), is a widespread tree species ideal for assessing these processes' role in the intraspecific LES, due to its clonal growth along environmental gradients, intraspecific variation in cytotype (ploidy level), …

Northern Arizona Ecological Conservation: Assessing Quaking Aspen Health In Northern Arizona Using Earth Observations, Ikram Morso, Luke Collins, Margaret Cox, Melissa Schwan

Aspen Bibliography

Quaking aspen (Populus tremuloides) forests in Northern Arizona provide critical habitat for endangered bird species and support regional tourism and recreation. However, aspen populations are declining due to a combination of abiotic and biotic stressors. In response, land managers implemented strategies, such as ungulate exclusion fencing, prescribed burns, and stand thinning, but efforts are constrained by limited data on where and when to intervene. This project worked in collaboration with the U.S. Forest Service, the National Park Service, the Arizona Department of Forestry and Fire Management, and Northern Arizona University School of Forestry. The team utilized Earth observations …

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 …

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 …

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 …

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 …

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 …

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.

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 …

A Fire Deficit Persists Across Diverse North American Forests Despite Recent Increases In Area Burned, Sean A. Parks, Christopher H. Guiterman, Ellis Q. Margolis, Margaret Lonergan, Ellen Whitman, John T. Abatzoglou, Donald A. Falk, James D. Johnston, Lori D. Daniels, Charles W. Lafon, Rachel A. Loehman, Kurt F. Kipfmueller, Cameron E. Naficy, Marc-André Parisien, Jeanne Portier, Michael C. Stambaugh, A. Park Williams, Andreas P. Wion, Larissa L. Yocom

Wildland Resources Faculty Publications

Rapid increases in wildfire area burned across North American forests pose novel challenges for managers and society. Increasing area burned raises questions about whether, and to what degree, contemporary fire regimes (1984–2022) are still departed from historical fire regimes (pre-1880). We use the North American tree-ring fire-scar network (NAFSN), a multi-century record comprising > 1800 fire-scar sites spanning diverse forest types, and contemporary fire perimeters to ask whether there is a contemporary fire surplus or fire deficit, and whether recent fire years are unprecedented relative to historical fire regimes. Our results indicate, despite increasing area burned in recent decades, that a …

Tremblings, February 2025, Western Aspen Alliance

Tremblings

Bridging Conservation Science With Native Meaning

James Calabaza, Indigenous Lands Director; Trees, Water & People

Last fall, I had the privilege of collaborating with the Western Aspen Alliance and other partners to carry out a 3-day workshop focused on quaking aspen genetics, fire ecology, and co-stewardship. Held at Rocky Mountain Biological Laboratory (Gothic, Colorado), the workshop brought together academics, NGOs, federal agencies, and Tribal members to share diverse perspectives on aspen's significance and management futures.

Timber Harvesting Was The Most Important Factor Driving Changes In Vegetation Composition, As Compared To Climate And Fire Regime Shifts, In The Mixedwood Temperate Forests Of Temiscamingue Since Ad 1830, Daniela Robles, Yan Boulanger, Jesus Pascual, Victor Danneyrolles, Yves Bergeron, Igor Drobyshev

Aspen Bibliography

Context The vegetation composition of northeastern North American forests has significantly changed since pre-settlement times, with a marked reduction in conifer-dominated stands, taxonomic and functional diversity. These changes have been attributed to fire regime shifts, logging, and climate change.

Methods In this study, we disentangled the individual effects of these drivers on the forest composition in southwestern Quebec from 1830 to 2000 by conducting retrospective modelling using the LANDIS-II forest landscape model. The model was run based on pre-settlement forest composition and fire history reconstructions, historical timber harvest records, and climate reanalysis data. We compared counterfactual scenarios excluding individual factors …