Life Sciences Commons^™

Assisted Migration Is Plausible For A Boreal Tree Species Under Climate Change: A Quantitative And Population Genetics Study Of Trembling Aspen (Populus Tremuloides Michx.) In Western Canada, Chen Ding, Jean S. Brouard

Aspen Bibliography

A novel method was tested for improving tree breeding strategies that integrate quantitative and population genetics based on range-wide reciprocal transplant experiments. Five reciprocal common garden tests of Populus tremuloides were investigated including 6450 trees across western Canada focusing on adaptation traits and growth. Both genetic parameters and home-site transplant models were evaluated. We found a genetic trade-off between growth and early spring leaf flush and late fall senescence. Coefficients of phenotypic variation (CVp) of cell lysis (CL), a measure of freezing injury, shrank from 0.28 to 0.10 during acclimation in the fall, and the CVp slope versus …

Pando's Pulse: Vital Signs Signal Need For Course Correction At World-Renowned Aspen Forest, Paul C. Rogers

Aspen Bibliography

Upland aspen (Populus spp.) forests contribute significantly to biodiversity in their circumboreal role as keystone species. As aspen ecosystems flourish or diminish, myriad dependent species follow suit. The 43-hectare Pando aspen (Populus tremuloides Michx.) clone in Utah, USA, is thought to be the largest living organism on earth, but is faltering due to chronic herbivory. Long-term resilience in aspen communities, including Pando, rests on successful recruitment of vegetative suckers that are nutritiously desirable to browsing ungulates. Here, I evaluate aspen reproduction alongside numerous vital indicators of Pando's status in the first trend assessment of this embattled iconic forest. …

Ungulate Herbivores As Drivers Of Aspen Recruitment And Understory Composition Throughout Arid Montane Landscapes, Elizabeth S. Reikowski, Tyler Refsland, J. Hall Cushman

Aspen Bibliography

Herbivory by wild and domestic ungulates can influence tree recruitment and understory forest communities throughout the world. Herbivore-driven declines in tree recruitment have been observed for quaking aspen (Populus tremuloides), a foundation species whose health and management is recognized as a critical priority throughout much of its range. Livestock fencing is commonly used to promote aspen regeneration, but its effectiveness is rarely assessed, especially across large spatial scales. Using a livestock-reduction experiment, we evaluated the effects of ungulate herbivory on aspen in the Great Basin and southern Cascades, an expansive and environmentally heterogeneous region where aspen faces the …

Quantification Of Hydrologic Response To Forest Disturbance In Western U.S. Watersheds, Sara A. Goeking

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Forested watersheds produce more than half of the water supply in the United States. Forests affect how precipitation is partitioned into available water versus evapotranspiration. This dissertation investigated how water yield and snowpack responded to forest disturbance following recent disturbances in western U.S. forests during the period 2000-2019.

Chapter 2 systematically reviewed 78 recent studies that examined how water yield or snowpack changed after forest disturbances. Water yield and snowpack often increased after disturbance, but decreased in some circumstances. Decreased water yield was most likely to occur following disturbances that did not remove the entire forest canopy. It was also …

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 …

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) …

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 …

Data For Dancing, Joseph D. Birch, James A. Lutz, Justine Karst

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Fungal communities can influence the productivity, composition, and survival of trees through cycling nutrients, providing resources, and altering pathogens. Thus, shifts in fungal communities could impact forests by altering interactions between trees and their environments. Fungal community composition may be shaped by stochastic and deterministic processes such as dispersal-limitation, environmental filtering, and partner specificity between trees and fungi. For tree species with large geographic ranges, we expect fungal assembly processes to change with environmental variation across the range of the tree partner. Due to specificity between trees and symbiotic fungi, we expect deterministic to outweigh stochastic processes in root compared …

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 …

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 …

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 …

Partnerships Create Success For The Devil’S Garden Wild Horses, Laura K. Snell

Human–Wildlife Interactions

Many wild horse (Equus ferus caballus) populations that inhabit designated federal land in the United States currently exceed management objectives. Overabundant wild horse populations can adversely impact the ecosystem, native wildlife, and other land uses. Unfortunately, there is not a universal solution, as each impacted area may differ ecologically, economically, socially, and politically. Wild horse management is not just a 1-time project but a long-term program where buy-in is needed from the federal and state agencies, local governments, and private partners. Local county governments and private partners can have important insights and significant influence on the development and …

Effects Of Buried Wood On The Development Of Populus Tremuloides On Various Oil Sands Reclamation Soils, Kaitlyn E. Trepanier, Laura Manchola-Rojas, Bradley D. Pinno

Aspen Bibliography

Buried wood is an important but understudied component of reclamation soils. We examined the impacts of buried wood amounts and species on the growth of the common reclamation tree species trembling aspen (Populus tremuloides). In a greenhouse study, aspen seedlings were planted into four soil types, upland derived fine forest floor-mineral mix (fFFMM), coarse forest floor-mineral mix (cFFMM), and lowland derived peat and peat-mineral mix (PMM), that were mixed with either aspen or pine wood shavings at four concentrations (0%, 10%, 20% and 50% of total volume). Height and diameter growth, chlorophyll concentration, and leaf and stem biomass were measured. …

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 …

Sampling Bias Exaggerates A Textbook Example Of A Trophic Cascade, Elaine M. Brice, Eric J. Larsen, Daniel R. Macnulty

Aspen Bibliography

Understanding trophic cascades in terrestrial wildlife communities is a major challenge because these systems are difficult to sample properly. We show how a tradition of non-random sampling has confounded this understanding in a textbook system (Yellowstone National Park) where carnivore [Canis lupus (wolf)] recovery is associated with a trophic cascade involving changes in herbivore [Cervus canadensis (elk)] behaviour and density that promote plant regeneration. Long-term data indicate a practice of sampling only the tallest young plants overestimated regeneration of overstory aspen (Populus tremuloides) by a factor of 4–7 compared to random sampling because it favoured plants taller than the preferred …

Gambel Oak Care, Shawn Olsen, Debbie Amundsen, Shital Poudyal

All Current Publications

Gambel oak is commonly called scrub oak, but other common names are Rocky Mountain white oak and Utah white oak. The scientific name is Quercus gambelii, after William Gambel, an American naturalist. This fact sheet reviews Gambel oak's usability in the landscape, its care, growth requirements, diseases and pests, and maintenance.

Growth–Defense Trade-Offs Shape Population Genetic Composition In An Iconic Forest Tree Species, Olivia L. Cope, Ken Keefover-Ring, Eric L. Kruger, Richard L. Lindroth

Aspen Bibliography

All organisms experience fundamental conflicts between divergent metabolic processes. In plants, a pivotal conflict occurs between allocation to growth, which accelerates resource acquisition, and to defense, which protects existing tissue against herbivory. Trade-offs between growth and defense traits are not universally observed, and a central prediction of plant evolutionary ecology is that context-dependence of these trade-offs contributes to the maintenance of intraspecific variation in defense [Züst and Agrawal, Annu. Rev. Plant Biol., 68, 513–534 (2017)]. This prediction has rarely been tested, however, and the evolutionary consequences of growth–defense trade-offs in different environments are poorly understood, especially in long-lived species …

Determining The Novel Pathogen Neodothiora Populina As The Causal Agent Of The Aspen Running Canker Disease In Alaska, Loretta M. Winton, Gerard C. Adams, Roger W. Ruess

Aspen Bibliography

Neodothiora populina Crous, G.C. Adams & Winton was determined to be a new pathogen of trembling aspen (Populus tremuloides) growing in Alaska, based on completion of Koch’s Postulates in replicated forest and growth chamber inoculation trials. The pathogen is responsible for severe damage and widespread rapid mortality of sapling to mature aspen (≥ 80 years) in the boreal forests of interior Alaska, due to large diffuse annual (1–2 years) cankers. Isolation of the pathogen was challenging, and identification based on cultural characters was difficult. Fruiting bodies were not found on wild diseased trees, but erumpent pycnidia were found …

Household Perceptions And Patterns Of Crop Loss By Wild Pigs In North India, Bivash Pandav, Lakshminarayanan Natarajan, Ankit Kumar, Ajay A. Desai, Banteibor Lyngkhoi

Human–Wildlife Interactions

Loss to cultivated crops by wild pigs (Sus scrofa) is widespread and can jeopardize low-income farmers. In India, although there is lot of political interest in the problem, efforts to understand the patterns, correlates, and underlying reasons for wild pig conflict continue to be minimal. We quantified loss of wheat (Triticum aestivum) to wild pigs and assessed the spatial patterns of damage in a forest settlement of Van Gujjar (Haridwar, India), which is a dairy-based pastoralist community. We chose a 4-km² cultivated area comprising 400 farmlands (each measuring 0.8 ha and belonging to a family) and …

Intensive Hunting Pressure Changes Local Distribution Of Wild Boar, Jakub Drimaj, Jiří Kamler, Radim Plhal, Přemysl Janata, Zdeněk Adamec, Miloslav Homolka

Human–Wildlife Interactions

Wild boar (Sus scrofa) is now an important species of wild ungulates in Central Europe. Next to conflicts of wild boar with agriculture, the main threat of wild boar presence lies in the expansion of African swine fever across Europe. The regulation of the wild boar population is complicated by the high reproduction rate and intelligent behavior of the species, which limits hunting effectiveness. We analyzed the spatial behavior of wild boar in an environment with a lack of natural food resources. The study area consisted of a forest complex (1,283 ha) with 2 areas. In the “risk” …

Evaluation Of Damage To Forest Tree Plantations By Wild Boar In The Czech Republic, Vlastimil Skoták, Jakub Drimaj, Jiří Kamler

Human–Wildlife Interactions

Wild boar (Sus scrofa) populations in Central Europe have been growing long-term, and damages to crops and forests where boars damage freshly planted tree seedlings are growing too. In addition to having a significant economic impact, these damages worsen the prospect of successful restoration of bare land. This study presents an analysis of damage to tree seedling plantations caused by wild boar in the Czech Republic. We used data from an extensive questionnaire survey among forest owners, our own survey of the extent of damage in model areas, and experiments in locations with a large boar population. Damage …

What Is Biochar And How Is It Used?, Marion Murray

All Current Publications

Biochar is a charcoal-like product that contains no petroleum. It is made by heating biomass such as herbaceous or woody crop residues, non-salvageable timber, and slash, or animal manure, in a contained system. There are many potential uses for biochar including water treatment, land reclamation, and carbon sequestration. Biochar may also be used as a soil amendment for two purposes – to improve plant health and to store carbon.

Availability And Structure Of Coarse Woody Debris In Hemiboreal Mature To Old-Growth Aspen Stands And Its Implications For Forest Carbon Pool, Silva Šēnhofa, Guntars Šnepsts, Kārlis Bičkovskis, Ieva Jaunslaviete, Līga Liepa, Inga Straupe, Āris Jansons

Aspen Bibliography

European aspen deadwood is extensively studied as a habitat for saproxylic species, while less is known of its dynamics and role in carbon sequestration. We studied unmanaged mature (41–60 years), moderately overmature (61–80 years), overmature (81–100 years), and old-growth (101–140 years) and managed mature and moderately overmature aspen stands on fertile mineral soils. In unmanaged stands, marginal mean CWD volume was from 67.3 ± 12.1 m³ ha⁻¹ in moderately overmature to 92.4 ± 5.1 m³ ha⁻¹ in old-growth stands, with corresponding marginal mean CWD carbon pool 8.2 ± 1.6 t ha⁻¹ and 12.5 ± 0.7 …

Coarse Woody Debris Decomposition Assessment Tool: Model Validation And Application, Zhaohua Dai, Carl C. Trettin, Andrew J. Burton, Martin F. Jurgensen, Deborah S. Page-Dumroese, Brian T. Forschler, Jonathan S. Schilling, Daniel L. Lindner

Aspen Bibliography

Coarse woody debris (CWD) is a significant component of the forest biomass pool; hence a model is warranted to predict CWD decomposition and its role in forest carbon (C) and nutrient cycling under varying management and climatic conditions. A process-based model, CWDDAT (Coarse Woody Debris Decomposition Assessment Tool) was calibrated and validated using data from the FACE (Free Air Carbon Dioxide Enrichment) Wood Decomposition Experiment utilizing pine (Pinus taeda), aspen (Populous tremuloides) and birch (Betula papyrifera) on nine Experimental Forests (EF) covering a range of climate, hydrology, and soil conditions across the continental USA. …