NAFEW 2022

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Monday Tuesday Wednesday Thursday Friday

Melanie Wheatley (melanie.wheatley@mail.utoronto.ca), University of Toronto
B. Mike Wotton (mike.wotton@utoronto.ca), University of Toronto
Douglas G. Woolford (dwoolfor@uwo.ca), Western University
David L. Martell (david.martell@utoronto.ca), University of Toronto
Joshua M. Johnston (joshua.johnston@NRCan-RNCan.gc.ca), Canadian Forest Service - Natural Resources Canada

Wildland fire management agencies suppress unwanted fires to reduce their detrimental impacts on people and values. Aerial suppression (or air attack), including suppression by waterbombers and helicopters, is used on initial attack (IA) to suppress these unwanted fires quickly and contain them before they grow large. Fire management agencies will often use the rapid containment of fires at a small size as a metric of suppression effectiveness, known as IA success. We used historical fire records to examine factors associated with air attack effectiveness in the province of Ontario and developed three statistical models to estimate the probability of IA success on fires actioned by air attack using information available at different stages during the fire response process. The factors considered included the information available to the fire management agency at the time of fire report (e.g., fire-weather indices), at the time IA began (e.g., fire behaviour observations), and at the end of IA suppression of the fire (e.g., amount of suppression applied). We found that the inclusion of situational information about a fire acquired during the IA process in our models produced better estimates of the probability of IA success on an independent test data set used for validation. This improvement was evident in an increase in overall model predictive accuracy and the area under the receiver operating characteristic curve compared with a model based only on information available at the time a fire is reported. Our results can inform and enhance fire response planning and decision-making concerning suppression resource allocation, particularly decision-making concerning the redeployment of airtankers on existing fires and their dispatch to new fires reported later during the day on days during which many new IA fires are expected to be reported.

Kendriah Pearse (kendriah.pearse@mail.utoronto.ca), University of Toronto
B. Mike Wotton (mike.wotton@daniels.utoronto.ca), University of Toronto
Xianli Wang (xianli.wang@nrcan-rncan.gc.ca), Northern Forestry Centre, Canadian Forest Service, Natural Resources Canada,
Dan Johnston (dan.johnston@ontario.ca), Ontario Ministry of Northern Development, Mines, Natural Resources and Forestry
Mike Flannigan (mike.flannigan@ualberta.ca), Thompson Rivers University, Department of Natural Resource Science

Wildfires are a beneficial natural ecological process, however, when fires approach areas which people inhabit, wildfires can pose a threat. In extreme cases, evacuations can occur due to either smoke from forest fires or a direct threat of fire impingent. The recommendation to evacuate a community due to the threat of wildfire in Ontario is made based on several factors, one of which is forecasted fire weather and behaviour potential, estimated from a range of metrics from the Canadian Forest Fire Danger Rating System (CFFDRS). These metrics use daily weather observations (and forecasts) to create indicators of relative fire spread, fuel consumption, and overall fire danger and intensity. Using wildfire evacuation data from Ontario, we examined the differences between the conditions associated with fires (including fire weather, danger and other situational metrics) which caused wildfire evacuations and those that did not. Two separate analyses were conducted: one for smoke and one for direct threat evacuations. The maximum Initial Spread Index (a relative index of how fast the fire is moving), the number of spread days and the number of fires burning one week prior to a fire start are associated with a fire causing a threat evacuation. However, we found the distance of a fire to a community and the maximum Build-Up Index, which is an indicator of potential fuel consumption on the forest floor, are significantly associated with a fire causing both a smoke or threat evacuation. Our research uses outputs from the CFFDRS system which is used operationally in Ontario to explore and provide evidence-based information on the environmental and fire-related conditions associated with fires that lead to evacuations. These results can inform, challenge or support the pre-existing mental models of fire management decision makers with respect to the conditions associated with evacuations.

Claudia I. Bartlick (cbartlic@mtu.edu), Michigan Technological University
Julia I. Burton (jiburton@mtu.edu), Michigan Technological University
Christopher R. Webster (cwebster@mtu.edu), Michigan Technological University
Robert E. Froese (refroese@ualberta.ca), University of Alberta
Stefan F. Hupperts (stefan.hupperts@slu.se), Swedish University of Agricultural Sciences
Yvette L. Dickinson (yvette.dickinson@scionresearch.com), Scion

Tip-up mounds can provide important sites for tree seedling establishment as germination on mounds can provide a variety of advantages, e.g. increased amount of bare mineral soil, reduced litter depth, and reduced competition. Naturally created mounds are often lacking in managed and second-growth forests, which may reduce opportunities for regeneration of some disturbance-adapted species. In the context of ecological silviculture, the creation of artificial mounds has been proposed to emulate wind-induced uprooting and provide more seedbed variation for tree regeneration. However, only limited data investigating the effects of artificial mounds on regeneration are available. We investigated the near-term effects of artificial tip-up mounds on tree regeneration in a hardwood forest in northern Michigan. We created artificial mounds over a gradient of four different harvest regimes: clear-cut, shelterwood (30% and 60% residual canopy), and single tree selection. Mounds were created by uprooting trees during winter harvesting with a logging processor. Tree seedlings (< 30 cm tall) and environmental factors were monitored during the second, third, and fourth growing seasons following treatment on 61 artificial mounds and 35 reference plots (no mound creation). We observed significant differences in seedling composition associated with mound creation (MRPP, p = 0.001). Non-metric multidimensional scaling ordination results suggested that disturbance-adapted species including birch species (Betula spp.), and black cherry (Prunus serotina) were associated with artificial mounds. Maples (Acer saccharum and Acer rubrum) were more strongly associated with reference plots. Differences in species composition became more distinct over time. Our findings suggest that tip-up mounds created during winter harvesting, where soil disturbance is often minimal, may provide opportunities for regeneration of some soil disturbance-adapted species. Continued monitoring over the next decade is needed to determine if these seedlings remain competitive and recruit into larger size classes.

Mary Ann Fajvan (Maryann.Fajvan1@usda.gov), U.S. Department of Agriculture Forest Service
Andrea Hille (andrea.hille@usda.gov), USDA Forest Service, Allegheny National Forest

Hemlock woolly adelgid (Adelges tsugae) (HWA), an invasive insect to North America, threatens the existence of eastern hemlock- (Tsuga canadensis (L.) Carr.) dominated ecosystems. Both anecdotal observations and experimental findings suggest that ambient light environments influence HWA densities and tree carbon balance. Decreases in hemlock radial growth are correlated with high levels of HWA infestation, crown size and canopy position. Hemlock's high shade tolerance creates dense, multi-layered canopies, which perpetuates the abundance and spread of HWA. We propose that increasing canopy light exposure via silvicultural thinning can reduce hemlock's vulnerability to HWA when combined with biological and chemical controls. Three, 24-ha, Allegheny hardwood stands on the Allegheny National Forest in Pennsylvania, USA were selected for thinning. Stands had > 30% hemlock basal area, were overstocked (39 to 46 m2 ha-1 basal area) and without HWA infestation. Each stand was divided into six, 4-ha treatment blocks: three blocks for thinning and three for reference. In each block, ten, 0.04-ha circular plots were established surrounding a hemlock tree (subject tree) targeted for crown release. Similar criteria were used to identify 10 hemlocks in the untreated blocks. Commercial thinnings, conducted from winter 2007-2008, reduced relative stand density 30-40%. We used repeated-measures analysis to evaluate 186 subject trees pre-thinning, and 5 and 10 years post thinning; diameter, total height, live crown ratio and crown area were measured with residual stand basal area as a covariate. Temporal changes in diameter were not significant between thinned and control treatments but subject trees in thinned plots averaged about 5 cm larger after 10 years. Live crown ratio was maintained in thinned stands and significantly decreased after year 5 in controls. Crown area significantly increased in thinned plots and decreased in controls. Residual basal area significantly influenced all variables with some differences among stands.

Olivia Rianhard (rianho@mail.ubc.ca), University of British Columbia Okanagan
Marty Kranabetter (Marty.Kranabetter@gov.bc.ca), BC Ministry of Forests
Daniel Durall (daniel.durall@ubc.ca), University of British Columbia, Okanagan campus
Jason Pither (jason.pither@ubc.ca), University of British Columbia, Okanagan campus
Melanie Jones (melanie.jones@ubc.ca), University of British Columbia, Okanagan

Due to the relatively recent expansion of forestry into high elevation areas, the response of high elevation soil fungi to logging is understudied. Furthermore, studies of ectomycorrhizal fungal (EMF) communities after logging often focus on the cutblocks without examining the adjacent uncut forests. This study investigated EMF communities on Engelmann spruce and Subalpine fir roots in and surrounding 26-year-old clearcuts. Studies conducted at this site (Sicamous Creek Silvicultural Systems Trial, BC) three seasons after logging found reductions of EMF richness and diversity on dying roots of cut trees and on roots of young seedlings planted at >16 m in clearcuts. Additionally, EMF communities in clearcuts remained different from those in the uncut forests 15 years after logging. Because these studies did not look at the roots of mature trees in the forest, much of the EMF diversity in the forest may be unknown. In our study, roots and foliage of ectomycorrhizal trees were sampled in July-September 2021 along transects at Sicamous Creek. The transects were centered on the clearcut-forest edges of nine 1 ha clearcuts and spanned 45 m into both the clearcuts and forests. Pacific Biosciences sequencing was conducted; mixed effects models will be used to model EMF community composition across the clearcut-forest edge. We hypothesize the following: 1) forest influence on EMF richness and community composition has not progressed further into the clearcuts since last studied due to persisting environmental heterogeneity between the clearcuts and forests and 2) there is an effect of proximity to clearcut on the EMF richness, community composition, or dominant species in the forests. In addition to clarifying the medium-term effects of logging on EMF communities in clearcuts and surrounding forests, results from this research will also help to clarify the EMF community composition in the forest at Sicamous Creek.

Martín Alcalá (alcm01@uqat.ca), IRF - Université du Québec en Abitibi-Témiscamingue (UQAT)
Miguel Montoro Girona (miguel.montoro@uqat.ca), MRC Abitibi Ecology Research Group (GREMA), Forest Research Institute (IRF), Université du Québec en Abitibi-Témiscamingue, Amos, QC, Canada. Department of Wildlife, Fish and Environmental Studies, Swedish University of Agricultural Sciences, SE-901 83 Umeå, Sweden.
Annie DesRochers (annie.desrochers@uqat.ca), MRC Abitibi Ecology Research Group (GREMA), Forest Research Institute (IRF), Université du Québec en Abitibi-Témiscamingue, Amos, QC, Canada.

Increasing concern regarding the impacts of traditional even-aged management practices are leading to a diversification in the silvicultural practices to implement ecosystem-based management. Consequently, the development of partial cut treatments has been a priority during the last two decades. Although important advances have been made, the effects of these treatments in terms in tree growth and mortality are not well understood. This thesis will study the influence of several harvest intenisty partial cuts on (i) the edge effect, (ii) the after-harvest growth shock, and (iii) tree mortality 10 years after harvesting in the esker forests and in forests located over clayey soils of the Abitibi-Témiscamingue region (Quebec, Canada). Black spruce and jack pine forests will be selected on both soil types. Two partial cut treatments in addition with uncut (control) stands will be evaluated in each forest type in order to stablish a harvest intensity gradient. A total of four replicates per treatment will be selected and one 600 m² experimental plot will be installed in each replicate to study radial grwoth, using a dendrological approach by extracting cores and analyzing tree-ring series. Around 35 trees will be sampled in each replicate extracting a total of around 1.680 cores. Tree mortality and root grafting will be studied in 50 m² permanent plots to evaluate the relationship among both phenomena. Dead trees will be classified as snags, broken, or uprooted. In addition, a high-pressure water spray from a water pump will be used to excavate, expose, and extract the grafted root systems for their following analysis. Results of this research will be essential to provide silvicultural prescriptions for the implementation of partial cuts in the Canadian boreal forest. Moreover, this thesis will be pioneer in the evaluation of the effects of partial cuts in the esker ecosystems and the complex relationship between root grafting and tree mortality.

Keywords: radial growth, root grafting, windthrow, silviculture, dendrochronology, sustainable forest management.

Samuel Robin (Samuel.Robin@uqat.ca), Groupe de recherche en écologie de la MRC Abitibi (GREMA), Université du Québec en Abitibi-Témiscamingue (IRF-UQAT)
Miguel Montoro Girona (miguel.montoro@uqat.ca), IRF - Université du Québec en Abitibi-Témiscamingue (UQAT)
Annie DesRochers (annie.desrochers@uqat.ca), CEF - IRF - Université du Québec en Abitibi-Témiscamingue (UQAT)
Sergio Rossi (sergio_rossi@uqac.ca), University of Quebec in Chicoutimi (UQAC)

Climate change is altering the structure and function of forest ecosystems worldwide. In the boreal forests, an increase of temperature from 4°C to 11°C is projected for the next century. These future conditions will alter the physiological processes of boreal trees, where their adaptation will struggle to keep pace with climate change. For this reason, studies to better understand the regeneration process of boreal species under a warming climate become relevant to adapt our forest management strategies in the future. This project aimed to assess the effects of predicted temperatures for the next century on the germination and establishment of Canadian boreal species trees. Our experimental design consisted of four germination (14°C, 18°C, 22°C, and 26°C) and three establishment (16°C, 22°C, and 28°C) temperatures scenarios. The experience was conducted in growth chambers to isolate the effects of temperatures on the trees. We measured germination rate, seed viability, germination speed, and biomass of the produced seedlings of eight boreal species: Pinus banksiana, Betula papyrifera, Populus tremuloides, Abies balsamea, Picea glauca, Picea mariana, Larix laricina and Thuja occidentalis. We expected that high germination temperatures would produce seedlings better adapted to high temperatures during their initial growth than seedlings resulting from cooler germination temperatures, leading to more biomass. We observed that germination rate decreased for Populus tremuloides, Larix laricina and Abies balsamea with temperature increases, while it was the opposite for the other species. This knowledge will be essential to better estimate the vulnerability and resilience of our forests to climate change in the coming years.

Sanghyun Kim (sanghyun.kim@uqat.ca), IRF - Université du Québec en Abitibi-Témiscamingue (UQAT)
Miguel Montoro Girona (miguel.montoro@uqat.ca), IRF - Université du Québec en Abitibi-Témiscamingue (UQAT)
Patricia Raymond (patricia.raymond@mffp.gouv.qc.ca), Direction de la recherche forestière, Ministère des Forêts, de la Faune et des Parcs du Québec
Annie DesRochers (annie.desrochers@uqat.ca), CEF - IRF - Université du Québec en Abitibi-Témiscamingue (UQAT)
Hubert Morin (hubert_morin@uqac.ca), University of Quebec in Chicoutimi (UQAC)
Yves Bergeron (Yves.Bergeron@uqat.ca), IRF - Université du Québec en Abitibi-Témiscamingue (UQAT)

In Canada, clearcutting has been the dominant forest management practices, causing biodiversity loss, vulnerability of regeneration to natural disturbances and depletion of forest sources in ecosystems not adapted to intensive disturbances such as wildfire. Thus, partial harvest is considered as a promising alternative to clearcutting system to integrate ecological, economical, and social objectives into silvicultural planning. However, partial harvest has not been widely adapted to the Canadian boreal forest yet and needs further evaluation for multidisciplinary research to adopt it to achieve sustainable management goals. The aim of this study is to evaluate the effects of partial harvests on conifer regeneration in natural even-aged black spruce (Picea mariana (Mill.) B.S.P.) stands 18 years after silvicultural intervention. An experimental design with six sites (three densely younger and three sparsely older stands) and silvicultural treatments (clearcut: 100% of basal area removal, seed-tree: 75%, three variants of shelterwood: 50%, unmanaged) was established by Canadian Forest Service in Monts-Valin and North Shore regions of Quebec. First, we will count and categorize all seedlings by species and height class in each micro-plot and assess a dominant seedling for the growth features (age, height, diameter, reproduction type) and environment (solar radiation, rooting substrate, soil properties). Second, we will evaluate water use efficiency of two conifer seedlings (P. mariana, Abies balsamea) by analyzing stable carbon isotope ratio (δ13C) in one-year-old 5 cm branch cuttings. We expect that uniform shelterwood systems will be silvicultural alternatives to clearcutting for conifer regeneration by providing appropriate seedbed and intermediate level of disturbances in black spruce boreal forests. This knowledge will be useful to better understand the dynamics and driving factors of regeneration of Canadian boreal forests after partial harvest to build decision making tools to reach the sustainable forest management goals.

Jonathan Cazabonne (jonathan.cazabonne@uqat.ca), Groupe de recherche en écologie de la MRC Abitibi (GREMA), Université du Québec en Abitibi-Témiscamingue (IRF-UQAT)
Miguel Montoro Girona (miguel.montoro@uqat.ca), IRF - Université du Québec en Abitibi-Témiscamingue (UQAT)
Annie DesRochers (annie.desrochers@uqat.ca), CEF - IRF - Université du Québec en Abitibi-Témiscamingue (UQAT)

Eskers are fluvioglacial geological formations providing many natural resources important for the economy and the population. These ecosystems, and the associated fungi, seem unique in the world and have never been investigated to date. They also remain vulnerable as they are highly sought over for wood, sand, and gravel. Our study aims to characterize the diversity, composition, and structure of soil fungal communities of esker forests, as well as evaluate their distribution across podzol horizons, from functional and taxonomic levels, and evaluate its environmental driving factors. Esker podzols represent stressed environments in terms of low nutrient and water availability. As a result, plant species require symbiotic associations with fungi to thrive in such harsh edaphic conditions. Our hypothesis is that pedology mainly contributes to the presence of soil fungal diversity typical of esker forests. In addition, the vertical differences in fungal composition within the same podzol profile would be related to the magnitude of differences in soil chemistry, oxygen content, as well as the presence and depth of root systems. Then, differences in fungal composition at the inter-soil scale would be related to pedology, local climatic conditions, and plant community composition. Our study will be held in the Abitibi region. For the intra-soil scale, a global horizon sampling campaign will be carried out. For the inter-soil scale, soil fungi from esker and clay podzols, as well as from sites with a differential vegetation composition will be characterized using DNA metabarcoding. We expect soil fungal communities to show a relationship between soil chemistry and phytobiota on both scales. This project is the first molecular-based study to assess the unique soil fungal diversity of esker forests. It will help us better understand the key role of soil fungi in the functioning of esker forests and provide arguments toward a more fungi-focused forest management perspective.

Michel Guimond (Michel.Guimond@uqat.ca), IRF - Université du Québec en Abitibi-Témiscamingue (UQAT)
Miguel Montoro Girona (miguel.montoro@uqat.ca), IRF - Université du Québec en Abitibi-Témiscamingue (UQAT)
Guillaume Grosbois (guillaume.grosbois@uqat.ca), IRF - Université du Québec en Abitibi-Témiscamingue (UQAT)
Kaysandra Waldron (kaysandra.waldron@canada.ca), Canadian Forest Service - Natural Resources Canada

Forest harvesting can have major impacts on aquatic ecosystems. Nevertheless, the unique preventive silviculture tool used (in Quebec) to reduce those impacts is the 20m riparian buffer. Despite its wide application in Canadian boreal forest management, there is a lack of knowledge on the optimal width usage for this sylviculture tool and its long-term impact on the post-harvested forest stands and aquatic ecosystem. This research aims to evaluate the boreal riparian buffer's resistance to windthrow, its plant biodiversity and finally, its efficiency as a silvicultural practice able to minimize the impacts of forest harvesting on aquatic ecosystems. Our experimental design is composed by 52 sites located in harvested stands (15-20 years ago) including: 20 riparian buffers in harvested stands (20m wide), 20 riparian buffers in naturals (unharvested) stands (20m) and 12 harvested larger riparian buffers (20-40m, 40-60m and 60m+). The study sites were selected on the two most common soil types (clay and sand) in the study area and two different stand types commonly harvested, black spruce (Picea mariana) and jack pine (Pinus banksiana). Our methodology includes several forest inventory data (DBH, spatial position, age, mortality, height, wound level), characterisation of substrate (depth, soil perturbation, undergrowth vegetation cover and diversity, solar radiation) and finally characterisation of windthrow (coverage of windthrow and wood debris). Forest fieldwork was carried out in summer 2021. An aquatic fieldwork will be done in summer 2022 regarding the effects of the riparian buffer on the physicochemical properties of water (dissolved organic/inorganic carbon, pH, temperature, dissolved oxygen, conductivity, phosphorus and nitrogen concentration, chlorophyll concentration). This study will lead to new knowledge on the riparian buffer in the boreal region, to better integrate water ecosystem in sustainable forest management strategies.

Sandy Erni (sandy.erni@nrcan-rncan.gc.ca), Canadian Forest Service - Natural Resources Canada
Xianli Wang (xianli.wang@NRCan-RNCan.gc.ca), Northern Forestry Centre, Canadian Forest Service, Natural Resources Canada,
Tom Swystun (tom.swystun@canada.ca), Canadian Forest Service - Natural Resources Canada
Steve Taylor (steve.taylor@NRCan-RNCan.gc.ca), Canadian Forest Service - Natural Resources Canada
Marc-André Parisien (marc-andre.parisien@NRCan-RNCan.gc.ca), Canadian Forest Service - Natural Resources Canada
François Robinne (francois.robinne@NRCan-RNCan.gc.ca), Canadian Forest Service - Natural Resources Canada
Brian Eddy (briang.eddy@NRCan-RNCan.gc.ca), Canadian Forest Service - Natural Resources Canada
Brad Armitage (ember@emberresearch.com), Ember research
Mike Flannigan (mike.flannigan@ualberta.ca), University of Alberta

Wildfire disasters leading to the loss of human lives and livelihoods have been piling up over the last decade, affecting the safety and the security of many communities in Canada. Disastrous events such as Fort McMurray in 2016, the British Columbia fires in 2017-2018, and the near complete destruction of the community of Lytton, BC during summer 2021, have created urgency among fire researchers, fire management agencies, municipalities, and industry, to spatially quantify fire risk across the country to help identify high-risk zones and anticipate, and hopefully reduce, the impacts of fire. In Canada, however, there is currently no standardized procedure for mapping wildfire risk at a national scale, unlike in other fire-prone countries such as the United States and Australia. The concept of risk itself is blurred: representations of wildfire risk in the literature are manifold and often combine multiple concepts and elements of vocabulary pertaining to risk science. We present here (1) a definitive system for fire risk assessment in Canada; (2) a standardized methodology for developing the spatial components of risk, namely wildfire hazard and vulnerability to fire; (3) a spatial overview of wildfire risk for Canadian communities through maps and summary statistics. We also address the specific situations that remote Indigenous reserves face in terms of fire exposure. Considering increasing population growth and inherent encroachment into forested landscapes for residential and industrial purposes, combined with the increasing pressure of climate change on local fire regimes, we can expect that wildfire disasters will become more frequent, but also more dramatic, causing more fatalities, social disruptions, and physical and ecological losses. The proposed procedure and resulting outputs are essential basis pieces for supporting fire management agencies and communities in the development of decision support systems that will help identify and prioritize areas in need of risk reduction measures.

Victoria M. Donovan (vdonovan2@unl.edu), Department of Agronomy & Horticulture, University of Nebraska-Lincoln, Lincoln, Nebraska 66583-0915
Caleb Roberts (cr065@uark.edu), U.S. Geological Survey, Arkansas Fish and Wildlife Cooperative Research Unit, University of Arkansas, SCEN 522, Fayetteville, AR, 72701, USA
Dillon Fogarty (dillon.fogarty@huskers.unl.edu ), Department of Agronomy & Horticulture, University of Nebraska-Lincoln, Lincoln, Nebraska 66583-0915
David Wedin (dwedin1@unl.edu), School of Natural Resources, University of Nebraska-Lincoln, Lincoln, Nebraska 68583-0961
Dirac Twidwell (dirac.twidwell@unl.edu), Department of Agronomy & Horticulture, University of Nebraska-Lincoln, Lincoln, Nebraska 66583-0915

Increasing wildfire activity has spurred ecological resilience-based management that aims to reduce the vulnerability of forest stands to wildfire by reducing the probability of crown fire. Targeted grazing is increasingly being used to build forest resilience to wildfire, either on its own or in combination with treatments like mechanical thinning; however, it is unclear how effective this method is at altering the probability of crown fire in forest stands. We use crown fire simulation models to quantify to what extent targeted grazing, mechanical thinning targeting the vertical fuel stratum, and a combination of both treatments alter eastern ponderosa pine savanna stand resilience to wildfire by modelling their relative impacts on fuel stratum gap and subsequent crown fire occurrence under six different wildfire risk scenarios. We then model changes in the probability of crown fire occurrence resulting from treatments across 75 field-sampled sites in the Pine Ridge region of Nebraska relative to predicted crown fire occurrence when sites are left untreated. We find that mechanical (vertical) thinning has the potential to alter the probability of crown fire in ponderosa pine stands to a much greater extent than targeted grazing. Across 75 sample sites, targeted grazing was only predicted to prevented crown fire occurrence at 2 sites expected to experience crown fire under observed stand conditions across all six of our wildfire risk scenarios. In contrast, targeted grazing combined with mechanical thinning was predicted to prevent crown fire at approximately half of the sites expected to experience crown fire under mild and moderate wildfire risk scenarios. No combination of targeted grazing or mechanical thinning was able to alter the probability of crown fire under wildfire risk scenarios most conducive wildfire, confirming that relying solely on vertical thinning and targeted grazing is unlikely to sufficiently enhance forest stand resilience to future wildfire conditions.

Kurt Johnsen (kurt.johnsen@usda.gov), UDSA Forest Service Southern Research Station
Jerre Creighton (jerre.Creighton@dof.virginia.gov), Virginia Department of Forestry
Chris Maier (christopher.maier@usda.gov), USDA Forest Service Southern Research Station
John Butnor (john.butnor@usda.gov), USDA Forest Service Southern Research Station
Gary Hawley (gary.hawley@uvm.edu), University of Vermont
Paul Schaberg (paul.schaberg@usda.gov), USDA Forest Service Northern Research Station

Lon ost lack of variation in cold tolerance among surviving trees from all the seed sources. We will also discuss the implications of our results on planting southern sources in Virginia to increase genetic variation as well as considerations for artificial migration to contend with increasing temperatures that will occur with climate change. gleaf pine (Pinus palustris Mill.) is a majestic species that once dominated the southeastern United States. Longleaf pine is the keystone species in longleaf pine savannah ecosystems harboring many threatened and endangered species. Due to extreme exploitation, it now occupies five percent of its pre-Northern European settlement extant. Here we report on 10-year results from a provenance test established in Virginia, the northern edge of its natural range. Tests were established on three sites using seed sources from Alabama, Florida, Georgia, Mississippi, South Carolina, North Carolina (one natural collection and the other from a seed orchard) and native Virginia trees where only 200 mature trees still exist. Two years after planting the Virginia seed source had grown out of the "grass stage" faster than all the other sources. By year 10, both tree growth and paricularily survival were highest in the Virginia seed source and dropped mostly steady with seed source climate averages. At age five, foliage was collected for analyses of 13C, a proxy for water-use efficiency (WUE). The Virginia seed source had remarkably higher and consistent WUE than all other seed sources at all three test sites. At age 10 foliage was collected three times from autumn through the winter from surviving trees and tested for cold hardiness using the electrolyte leakage method. There were no differences in cold hardiness among the surviving seed source trees except for on one date and one test site. We will discuss possible reasons for the high WUE of Virginia trees as well as the almost lack of variation in cold tolerance among surviving trees from all the seed sources. We will also discuss the implications of our results on planting southern sources in Virginia to increase genetic variation as well as considerations for artificial migration to contend with increasing temperatures that will occur with climate change.

Sergio Leonel Simental Rodriguez (sergioleonelsimental@hotmail.com), Programa Institucional de Doctorado en Ciencias Agropecuarias y Forestales
José Ciro Hernández-Díaz (jciroh@ujed.mx), Instituto de Silvicultura e Industria de la Madera. Universidad Juárez del Estado de Durango, Constitución 404 sur. Zona centro. C.P. 34000. Durango, Dgo. México.
Javier Hernández-Velasco (javier.hernandez@ujed.mx), Programa Institucional de Doctorado en Ciencias Agropecuarias y Forestales, Universidad Juárez del Estado de Durango, Constitución 404 sur. Zona centro. C.P. 34000. Durango, Dgo. México
Ilga Porth (ilga.porth@sbf.ulaval.ca), Institute for System and Integrated Biology (IBIS), Université Laval, Charles-Eugène-Marchand Pavilion, 1030 Avenue de la Médecine, Quebec City, Quebec G1V 0A6, Québec, Canada
Roos Goessen (roosje.goessen.1@ulaval.ca ), Institute for System and Integrated Biology (IBIS), Université Laval, Charles-Eugène-Marchand Pavilion, 1030 Avenue de la Médecine, Quebec City, Quebec G1V 0A6, Québec, Canada
M. Socorro González-Elizondo (herbario_ciidir@yahoo.com.mx ), Instituto Politécnico Nacional, CIIDIR Unidad Durango, Sigma 119 Fracc. 20 de Noviembre II, 34220 Durango, Durango, México
Matthias Fladung (matthias.fladung@thuenen.de), Thünen-Institute of Forest Genetics, Sieker Landstr. 2, D-22927 Grosshansdorf, Germany
Katrin Groppe (katrin.groppe@thuenen.de), Thünen-Institute of Forest Genetics, Sieker Landstr. 2, D-22927 Grosshansdorf, Germany
Juan P. Jaramillo-Correa (jaramillo@ecologia.unam.mx), Instituto de Ecología, Universidad Nacional Autónoma de México
Jesús Miguel Olivas-García (jolivas@live.com.mx ), Universidad Autónoma de Chihuahua, Facultad de Ciencias Agrícolas y Forestales, Km 2.5 Carretera Delicias-Rosales, Delicias, Chih. C.P. 33000, Mexico
David S. Gernandt (dgernandt@ib.unam.mx ), Departamento de Botánica, Instituto de Biología, Universidad Nacional Autónoma de México. Apartado postal 70-367, 04510 México, D. F., México
José Guadalupe Martínez-Ávalos (jmartin@uat.edu.mx ), Instituto de Ecología Aplicada, Universidad Autónoma de Tamaulipas, División del Golfo 356, Col. Libertad, Ciudad Victoria 87019, Mexico
Artemio Carrillo-Parra (tecnologia.madera.fcf@gmail.com ), Instituto de Silvicultura e Industria de la Madera. Universidad Juárez del Estado de Durango, Constitución 404 sur. Zona centro. C.P. 34000. Durango, Dgo. México
Carlos Antonio Lopez-Sanchez (lopezscarlos@uniovi.es ), Department of Biology of Organisms and Systems, Mieres Polytechnic School, University of Oviedo, Campus Universitario de Mieres, C/Gonzalo Gutiérrez Quirós S/N, 33600 Mieres, Spain
Eduardo Mendoza-Maya (eduardo.mendoza@ujed.mx), Programa Institucional de Doctorado en Ciencias Agropecuarias y Forestales, Universidad Juárez del Estado de Durango, Constitución 404 sur. Zona centro. C.P. 34000. Durango, Dgo. México.
Cuauhtémoc Sáenz-Romero (csaenzromero@gmail.com ), Instituto de Investigaciones sobre los Recursos Naturales (INIRENA), Universidad Michoacana de San Nicolás de Hidalgo (UMSNH). Av. San Juanito Itzícuaro s/n, Col. Nueva Esperanza. Morelia Michoacán 58337, México
Arnulfo Blanco-García (arnulfoblanco@yahoo.com.mx ), Facultad de Biología, Universidad Michoacana de San Nicolás de Hidalgo (UMSNH). Av. J. Mújica s/n, Ciudad Universitaria, Morelia, Michoacán C.P. 58030, México
Gustavo Ibrahim Giles-Pérez (tavo455@hotmail.com), Instituto de Ecología, Universidad Nacional Autónoma de México
Christian Wehenkel (wehenkel@ujed.mx), Instituto de Silvicultura e Industria de la Madera - Universidad Juárez del Estado de Durango

Provenance region is an area within trees can be moved with little risk of maladaptation, because of the low environmental variation. Since trees may become maladapted under climate change, understanding current patterns of adaptive variation in species has become crucial to enlighten and guide climate resilient afforestation. Populus tremuloides is the most broadly distributed forest tree in North America, distributed over an 6,000 km North-South gradient. In a genome-wide association study (GWAS), we located, delimited and maped Mexican Populus tremuloides Michx provenances for recent climatic conditions and a projection for 2030 (Representative Concentration Pathway of ~4.5 Wm−2). We expect to observe: (i) associations between origins and local climate, soil, geographical and topographical factors, and (ii) a latitudinal change of origins, along with a contraction of species distribution for the period 2030. After sequencing, 1.5 Mill. unfiltered SNPs from 96 populations of P. tremuloides across its entire distribution in Mexico were detected. After filtering with MAC = 2, MAF = 0.025, 0.05 and 0.2 and MAS = 2 and max-missing 0.85 and 20% missing data using the VCFtools and R program, we found 13340 filtered SNPs and 32 adaptive SNPs. Several SNP outliers were significantly associated with climate and soil variables (up to R2 =0.44). According to the scenario for 2030, the estimated distributions for Populus tremuloides populations and provenances changed in size and position. Our provenance modeling could help to understand local adaptation in Populus tremuloides

Nelson Thiffault (nelson.thiffault@nrcan-rncan.gc.ca), Natural Resources Canada
Kaysandra Waldron (kaysandra.waldron@nrcan-rncan.gc.ca), Canadian Forest Service - Natural Resources Canada
Fidèle Bognounou (fidele.bognounou@nrcan-rncan.gc.ca), Canadian Forest Service - Natural Resources Canada
Dominique Boucher (dominique.boucher@nrcan-rncan.gc.ca), Natural Resources Canada
Elizabeth Campbell (elizabeth.campbell@nrcan-rncan.gc.ca), Natural Resources Canada
Lisa Venier (lisa.venier@nrcan-rncan.gc.ca), Great Lakes Forestry Centre - Canadian Forest Service - Natural Resources Canada
Ellen Whitman (ellen.whitman@nrcan-rncan.gc.ca), Natural Resources Canada
Lucas Brehaut (lucas.brehaut@nrcan-rncan.gc.ca), Natural Resources Canada
Sylvie Gauthier (sylvie.gauthier@nrcan-rncan.gc.ca), Natural Resources Canada

Information about post-disturbance regeneration success and successional dynamics is critical to predict forest ecosystem resistance and resilience to disturbances and climate change. Understanding post-disturbance recovery dynamics across Canadian biomes is needed to inform adaptive silviculture and management strategies based on emulation of natural disturbance. Our objective was to review post-disturbance research in Canada to provide guidance on future research needs to improve our understanding of post-disturbance recovery in a Canadian context. This is a critical area of forest ecology research needed to improve our ability to regenerate forests and forecast long-term impacts of disturbances on forest distribution, composition, structure and functions. To achieve our objective, we first conceived a conceptual model of post-disturbance recovery, with a focus on early succession as impacted by natural and anthropogenic disturbance frequency and severity. We then used literature produced by the Canadian Forest Service (CFS), a national research organization distributed across the country, as a representative subset of Canadian research to evaluate the topics and geographic distribution of post-disturbance recovery studies conducted in Canada over the last two decades. To do so, we searched peer-reviewed literature published in French and English between 1998 and 2020. Using appropriate Boolean search strings, we identified articles whose subjects cover forest and recovery, describe studies conducted in Canada, for which at least one author is affiliated with CFS, address natural or anthropogenic disturbances such as wildfires, insect outbreaks, diseases, windthrows, harvesting (including clearcutting, partial cutting and salvage logging), or seismic lines, and that study processes related to biodiversity, regeneration, succession, forest dynamics or growth. Our results will enable providing a spatially explicit overview of CFS research on post-disturbance recovery in Canada, identifying knowledge gaps and future key topics to advance post-disturbance research.

Ricardo Silas Sánchez (rick.silas96@gmail.com), Juárez University Durango Mexico
Carmen Zulema Quiñones-Pérez (zule_qp@hotmail.com), Instituto Tecnológico del Valle del Guadiana
José Ciro Hernández-Díaz (jciroh@ujed.mx ), Universidad Juárez del Estado de Durango
José Ángel Prieto-Ruíz (jprieto@ujed.mx), Universidad Juárez del Estado de Durango
Christian Wehenkel (wehenkel@ujed.mx), Instituto de Silvicultura e Industria de la Madera - Universidad Juárez del Estado de Durango

Natural hybridization is a very common phenomenon in plants. There is a high variability in terms of viability, fertility and vigor among hybrid individuals of two different species, some of them having lower, equal or higher values when compared to their parents. Pinus engelmannii Carr., P. arizonica Engelm. and P. durangensis Martínez, P. leiophylla var. leiophylla and P. teocote are among the most important timber species in the Sierra Madre Occidental and it has recently been discovered that these species are hybridizing with each other. The aim of this research was to compare the growth of hybrid and pure species individuals of these species, in two reciprocal trials in the Sierra Madre Occidental of Santiago Papasquiaro, Durango, Mexico. As well as to determine the density of stomata, and its variability between hybrid and pure individuals of these species, in addition, we will determine the correlation between stomatal density and growth variables in the field trials, since the characteristics of the stomata are key components that affect growth. The individuals were planted in two reciprocal trials in the Sierra Madre Occidental and were remeasured 27 months later. The basal diameter, height to the apical bud, maximum height reached by the needles and survival of 534 hybrids and 450 pure species individuals were measured. Only significant differences were found between the survival of P. durangensis (p=0.01) and P. arizonica (p=0.002) hybrids over pure individuals. The overall analysis of hybrid and pure species individuals showed that hybrids have greater mean in regard to the height to the apical bud. The density of stomata did not show significant differences between mean hybrid and pure individuals and species. Significant correlations were detected between the density of stomata, basal diameter and their heights.

Chelene Hanes (chelene.hanes@nrcan-rncan.gc.ca), Unversity of Toronto & Natural Resources Canada
B. Mike Wotton (mike.wotton@daniels.utoronto.ca), University of Toronto / Natural Resources Canada
Douglas G. Woolford (dwoolfor@uwo.ca), Western University
Laura Bourgeau-Chavez (lchavez@mtu.edu), Michigan Tech Research Institute
Stéphané Belair (stephane.belair@ec.gc.ca), Environment and Climate Change Canada
David Martell (david.martell@utoronto.ca), University of Toronto
Mike Flannigan (mflannigan@tru.ca), Thomson Rivers University

Canadian fire management agencies track drought conditions using the Drought Code (DC). The DC is one of three fuel moisture codes in the Canadian Forest Fire Danger Rating System. It represents the moisture of deep organic layers (15-18 cm nominal depth) and is used to assess potential lightning ignition holdover, persistent deep smoldering, and mop-up problems. As the climate changes and drought conditions arise more frequently, our understanding of drought and how to measure it become more important. What the DC means in areas without deep organic soils is a common operational question. Recent studies have indicated that more sophisticated models (e.g. the Canadian Land Data Assimilation System - CaLDAS) may provide added intelligence about the fire environment and drought conditions, something that has not been explored in Canada. To shed light on these questions we carried out field studies in the provinces of Alberta and Ontario. We installed 8-12 water content reflectometry (WCR) probes at two different depths in seven forest plots; from the surface through the organic layers, and in some cases, into the mineral soil. Overall, our results indicated that the simple DC model predicted the moisture content of the deeper organic layers (10-18 cm depths) well, even compared to the more sophisticated CaLDAS model. The WCR probes at these depths, exhibited good agreement with how the DC model estimated moisture changes. The DC may therefore be representative of changes in moisture content in a wide range of depths and soil horizons. Issues with model inputs, particularly missed precipitation events and incorrect DC spring starting values, had a greater influence on DC model fit than other factors. Calibration and validation of the CaLDAS model to mineral soils may be the cause of its consistent under prediction of organic layer moisture.

Seung-Il Lee (seungil1@ualberta.ca), Dept. of Renewable Resources, University of Alberta
Ellen Macdonald (emacdona@ualberta.ca), Dept. of Renewable Resources, University of Alberta
Anne CS McIntosh (amcintos@ualberta.ca), Science Dept, Augustana Campus, University of Alberta, Camrose, Alberta, T4V 2R3, Dept of Renewable Resources, University of Alberta, Edmonton, Alberta, T6G 2H1
Samuel Bartels (samuel.bartels@unbc.ca), Ecosystem Science and Management, University of Northern British Columbia, Prince George, British Columbia, V2N 4Z9
Jaime Pinzon (jaime.pinzon@canada.ca), Northern Forestry Center - Canada Forest Service - Natural Resources Canada
Linhao Wu (linhao1@ualberta.ca), Northern Forestry Center - Canada Forest Service - Natural Resources Canada
Sonya Odsen (sonya@fuseconsulting.ca), Fuse Consulting Ltd., Spruce Grove, Alberta, T7X 0Y5
David Langor (david.langor@canada.ca), Northern Forestry Center - Canada Forest Service - Natural Resources Canada
John Spence (jspence@ualberta.ca), Dept. of Renewable Resources, University of Alberta
Selena Schut (sschut@ualberta.ca), Dept. of Renewable Resources, University of Alberta

Forest retention harvesting is often promoted as an alternative to intensive timber harvesting (i.e., clear-cutting) as it contributes to the maintenance of biodiversity, among other ecological benefits. However, the level and intensity of retention harvests that facilitate biodiversity recovery remain unclear. To address this, we investigated biodiversity recovery trends for a range of taxonomic groups (staphylinid beetles, carabid beetles, spiders, songbirds, vascular plants, and bryophytes) using long-term data from the EMEND (Ecosystem Management Emulating Natural Disturbances) experiment, located in northern Alberta, Canada. Specifically, we compared changes in species composition over a period of 15-17 years following harvest between a broad range of dispersed retention treatments (2% [clear- cut], 10%, 20%, 50% and 75% retention) and unharvested stands, in four forest cover types (deciduous-dominated, deciduous-dominated with conifer understory, mixed of broadleaf and conifer, and conifer-dominated). We developed biodiversity recovery curves for each taxon based on the dissimilarity (Chao-Jaccard index) in species composition between each harvest treatment and the unharvested control, and evaluated recovery over time using a Generalized Additive Model. Preliminary results indicate different recovery trajectories among taxa with varying harvest intensity. For example, staphylinid beetles, songbirds, vascular plants and bryophytes showed faster recovery over time, but carabid beetles and spiders showed a relatively weak negative trend towards the unharvested control. Stand type was also an important factor that influenced recovery, with most taxa recovering much faster in deciduous-than in conifer-dominated stands. The results found thus far indicate promise in the use of variable retention harvest for the rapid recovery of biodiversity at the stand level. However, we also note that there is a need for continued and long-term research for taxa that have experienced negative recovery trends, primarily in conifer-dominated stands.

Kennedy Korkola (kennedy.korkola@mail.utoronto.ca), University of Toronto
Patrick M.A. James (patrick.james@utoronto.ca), University of Toronto
Jennifer L. Beverly (jen.beverly@ualberta.ca), University of Alberta

Climate change is affecting boreal forest disturbance regimes in terms of their frequency, severity, and extent with uncertain consequences for ecosystem functioning. In Ontario's boreal forest, the two main disturbances directly affected by these changes are periodic insect outbreaks and stand-replacing forest fires. The eastern spruce budworm (Choristoneura fumiferana; SBW) is a native insect that defoliates balsam fir (Abies balsamea) and spruce (Picea spp.) trees. Defoliation alters fuel structure both temporally and spatially which has been shown to affect fire behaviour. However, there is limited knowledge on how the timing and location of the spatial legacies left by a SBW outbreak affect suppression effectiveness in the boreal forest. Fire suppression effectiveness is evaluated by the success of Initial attack (IA) efforts, or the action taken immediately to contain a fire before it increases in size. An escaped fire is typically a fire that is not successfully contained despite IA efforts. Using historical fire data, we used a machine learning method to model how the probability of an IA escape varies as a function of lagged cumulative SBW defoliation data, weather, fire season, ignition, size at IA, and ecoregion. We found that fire size at IA was most strongly associated with fire escape and the inclusion of cumulative SBW data did not significantly improve overall model accuracy. However, it is likely that SBW defoliation affects the size at IA and should be investigated further to better understand the role of SBW defoliation on fire escape. These results contribute to our understanding of disturbance interactions in Canada's boreal forest and can be applied to improve resource management and initial attack planning efforts. Further work remains necessary to investigate the relationship between fire size at IA and forest fuel complexes, as well as the effects of time since SBW outbreak on fire escape.

Carlos Adrian Vásquez-Berumen (carlos_lobo_16@hotmail.com), Programa Institucional de Doctorado en Ciencias Agropecuarias y Forestales (UJED)
José Ángel Prieto-Ruiz (jprieto@ujed.mx), Facultad de Ciencias Forestales (UJED)
José Ciro Hernández-Díaz (jciroh@ujed.mx), Instituto de Silvicultura e Industria de la Madera (UJED)
Artemio Carrillo-Parra (acarrilloparra@ujed.mx), Instituto de Silvicultura e Industria de la Madera (UJED)
Christian Wehenkel (wehenkel@ujed.mx), Instituto de Silvicultura e Industria de la Madera - Universidad Juárez del Estado de Durango

Natural hybridization is a response that populations can present in order to evolve or to adapt to site conditions. This process can show genetic traits that facilitate speciation and differentiation and give rise to novel phenotypic, biochemical, and morphological components. However, sometimes problems like poor adaptation, non-viability and hybrid sterility occur in hybrid individuals. We placed 2552 pure species seedlings and natural hybrids of Pinus arizonica, P. durangensis, P. engelmannii, P. leiophylla and P. teocote, from twenty provenances, in two trial sites in the state of Durango, Mexico. The study aims were determining the association of parent tree’s environmental conditions, with the growth of mean diameter and height of pure species seedlings and their hybrids. The results indicated that these growths and variables correlate differently between these two types of seedlings. The mean diameter of hybrid and pure individuals was shown to be strongly related to the minimum temperature in the coldest month (MMIN) and to pH, while the mean height growth showed a strong relationship with winter precipitation, potassium and phosphorus percentage in the soil. Therefore, hybrids may be significantly adapted to different environmental gradients than pure species seedlings. It can also be observed that on average the hybrids were better adapted to environmental conditions than pure species seedlings. These results could help to increase the success of future reforestation programs.

Key words: Natural hybridization, site conditions, provenance studies, adaptation, reforestation.

Benjamin Lee (LeeB@carnegieMNH.org), Carnegie Museum of Natural History
Tara Miller (tkingmil@bu.edu), Boston University
Christoph Rosche (christoph.rosche@botanik.uni-halle.de), German Centre for Integrative Biodiversity Research (iDiv), Halle-Jena-Leipzig, Germany
Yong Yang (yangyong@njfu.edu.cn), Co-Innovation Center for Sustainable Forestry in Southern China, College of Biology and the Environment, Nanjing Forestry University
Mason Heberling (heberlingm@carnegiemnh.org), Carnegie Museum of Natural History
Sara Kuebbing (sara.kuebbing@yale.edu), Yale University
Richard B Primack (primack@bu.edu), Boston University

Understory forest plants are strongly limited by access to light throughout the growing season, and many species in deciduous forests have evolved strategies to make use of ephemeral, seasonally-dynamic light availability. Anthropogenic climate change is fundamentally changing the forest light regimes to which native species have adapted and the length of this spring light window has been projected to decrease with warming springs. However, studies in this area have been largely limited to studies at local scales, and it remains unknown how light window duration will change across broad geographic extents. Here, we scored wildflower and canopy tree herbarium specimens from temperate forests in North America, Europe, and Asia in an effort to identify if phenological sensitivity to spring temperature differs between the understory wildflowers and canopy trees and if these relationships vary among continents. We found that wildflowers and canopy trees were significantly sensitive to average spring temperatures across all three continents, but that sensitivity did not differ significantly either within or among continents. We found virtually identical sensitivities in North America whereas wildflowers were more sensitive than trees in both Europe and Asia, contrary to previous findings. These results suggest that light window duration will remain relatively constant in North America and increase on the other two continents by the end of this century. Importantly, we found that the inclusion of spatial autocorrelation in our models, a relatively new approach in herbarium phenology studies, significantly improved model performance while also changing posterior parameter estimates and overall interpretation of our findings. It suggests that there are spatial patterns of phenology that are not captured by drivers that are traditionally included in such analyses (temperature, latitude, precipitation, etc.). Overall, our results suggest that North American understories are not as vulnerable to climate-related reductions in light access as previously thought.

Brian Palik (brian.palik@usda.gov), USDA Forest Service-Northern Research Station
Anthony D'Amato (anthony.damato@uvm.edu), University of Vermont

Ecological silviculture is a transformative approach for managing forests to better position them to adapt to novel drivers. Ecological silvicultural systems are based on emulation of the natural developmental model, with a goal of sustaining a board suite of ecosystem services. Key tenets of ecological systems include continuity of pre-disturbance components, complexity of structure and diversity of species, ecologically-based recovery periods, and the landscape context of stand-level actions. While there has been much written on the concept of ecological silviculture, there has been less attention given to formalizing actual ecological silvicultural systems. This session will present examples of ecological silvicultural systems that are based on understanding a natural developmental model for several temperate and boreal ecosystems.

One example is silviculture for the Great Lakes mixed-pine ecosystem. This is a once wide-spread woodland ecosystem characterized by complex structure and mixed-species composition, developing in response to mixed-severity disturbances. It has been widely replaced by plantations of red pine, or semi-natural-origin forests that are greatly simplified in composition and structure. Even-aged regeneration systems, with high density planting of red pine, is the primary silvicultural system.

Emulation of the natural development model for the mixed-pine ecosystem includes: i) harvesting that is often less than stand-replacing, with continuity of legacies an important consideration; ii) inclusion of a pre-forest stage of variable length across a landscape (context); iii) delaying rapid establishment of regeneration with lower density regeneration goals; iv) maintaining species mixtures—e.g., enrichment planting to promote diversity; v) allowing ecologically-based recovery periods to determine size distributions and structural complexity, including abundant large deadwood. This example, and others in the session, highlight progress being made to realign silvicultural systems with natural models of development and to move ecological silviculture from concept to implementation.

Teresita M. Porter (terriporter@gmail.com), Great Lakes Forestry Centre - Canadian Forest Service - Natural Resources Canada
Emily Smenderovac (emily.smenderovac@NRCan-RNCan.gc.ca), Great Lakes Forestry Centre - Canadian Forest Service - Natural Resources Canada
Dave M. Morris (Dave.M.Morris@ontario.ca), Ontario Ministry of Northern Development, Mines Natural Resources and Forestry
Lisa Venier (lisa.venier@nrcan-rncan.gc.ca), Great Lakes Forestry Centre - Canadian Forest Service - Natural Resources Canada

Wildfire is a natural stand-replacing disturbance in boreal systems affecting forest dynamics, biodiversity, and terrestrial carbon stocks. As such, it has been proposed that wildfires can be a model for sustainable forest management by emulating a natural disturbance paradigm. Because harvest-disturbance does not exactly replicate fire-disturbance, information from both wildfire and harvest-origin sites is needed to describe post-disturbance soil biota colonization and longer-term community convergence (or not) over time. This study uses multi-marker soil metabarcoding across an 80-year chronosequence spanning 5 stand development stages of recovery after disturbance in jack pine-dominated boreal forest ecosites. Our study objectives were to: 1) establish a post-wildfire baseline; 2) check for community convergence between harvest- and fire-origin stands; and 3) assess the impact of salvage disturbance relative to full-tree clearcut harvest and natural wildfire. Fire-origin sites undergo dynamic changes in terms of taxonomic and functional diversity during recovery, especially for fungi. When these changes are compared to recovery following harvest, it appears to take as long as 60 years before richness and beta diversity converge, and even at this stage of stand development, the underlying community composition remains distinct with respect to stand origin. Salvage harvest following a natural wildfire had an even greater influence on the bacterial, fungal, and arthropod communities than did the full-tree clearcut harvest. While wildfire and harvest communities begin to converge, salvage sites remain distinct after 20 years of recovery. We examine the factors that explain this variation across three major groups of organisms and disturbance types as well as illustrate how these indicators can inform forest management practice.

Laura Boisvert-Marsh (laura.boisvert-marsh@nrcan-rncan.gc.ca), Great Lakes Forestry Centre - Canadian Forest Service - Natural Resources Canada
John Pedlar (john.pedlar@nrcan-rncan.gc.ca), Great Lakes Forestry Centre - Canadian Forest Service - Natural Resources Canada
Samuel Royer-Tardif (sroyertardif@cerfo.qc.ca), Great Lakes Forestry Centre - Canada Forest Service - Natural Resources Canada & Centre d'enseignement et de recherche en foresterie de Sainte-Foy
Dan W. McKenney (dan.mckenney@nrcan-rncan.gc.ca), Great Lakes Forestry Centre - Canadian Forest Service - Natural Resources Canada
Isabelle Aubin (isabelle.aubin@nrcan-rncan.gc.ca), Great Lakes Forestry Centre - Canadian Forest Service - Natural Resources Canada

Climatically suitable habitat of tree species in the temperate and boreal forests of eastern North America are projected to change considerably over the next century. Not all species will react equally in the face of rapid environmental change, making it critical to assess the relative ability of forest species to cope with these changes. Until recently, forest vulnerability assessments have been based mainly on climatic variables and rarely incorporate species sensitivity in response to climate stressors. Despite recent advances in understanding tree species sensitivities, ecological knowledge on different species remains scattered across disparate sources. As such, practitioners feel that there are few readily available tools to adequately inform climate adaptation decisions in a forest management context. Building upon the work of a multidisciplinary working group over recent years, we have developed a suite of tools as a step towards better integration of ecological information on Canadian tree species into forest vulnerability assessments. We simulated migration ability of 10 species in Eastern Canada using empirical observations of tree traits, life history and observed range shifts to quantify the difference between shifts in simulated range limits and projected changes in species' climatically suitable area through 2100. We also developed relative sensitivity indices for 26 tree species by breaking down species' response to three climate stressors, capturing the various ways a species can cope. Throughout this work, we identified knowledge gaps that should be addressed in order to develop robust indicators of species' sensitivity. These tools can guide climate adaptation actions, by identifying species that may require specific management considerations or rethinking those species that may become economically non-viable in some regions.

W. Henry McNab (William.mcnab@usda.gov), U.S. Forest Service
Cathryn H. Greenberg (cathryn.greenberg@usda.gov), U.S. Forest Service
Tara L. Keyser (tara.keyser@usda.gov), USDA Forest Service, Southern Research Station

The long absence of wildland fire in the southern Appalachian Mountains has allowed the thin-barked seedlings of eastern white pine (Pinus strobus) (EWP) to become a native invasive species in many mixed-oak stands on dry sites - beyond its historic occurrence on mesic and other areas where natural fires are low-intensity and infrequent. National forest land management plans propose increased prescribed burning for restoration of natural communities, which could facilitate control of off-site EWP regeneration. The response of EWP regeneration to prescribed fire has not been widely reported, thereby hindering resource managers from developing burn prescriptions of desired intensity to cause seedling mortality. Our primary objective was to evaluate the response of EWP regeneration to dormant season prescribed fires and develop a model for pre-burn application to predict mortality associated with the likely fire intensity resulting from the fuel and weather conditions on burn day. A replicated study was installed across all positions of a 47-ha southerly-facing slope where the 100-year-old oak-pine stand had no evidence of fire. Preburn overstory basal area averaged 20.5 m2/ha (EWP = 10.8%); advance regeneration (seedlings and saplings <10 cm diameter breast height (dbh)) averaged 6,900 stems/ha. The three replications were burned the same day in March 2014. Aluminum tags marked with heat sensitive paint indicated maximum fire temperatures. Logistic regression revealed first-year mortality was significantly associated with dbh (p<0.001). Mortality of EWP <=10 cm dbh was 94%; most trees >15 cm dbh survived. Crown scorch was associated with EWP delayed mortality the second year. Inventory eight years post-burn revealed a mean of 37.4 new EWP seedlings/ha had become established. Study results provide a guide for managers to determine the frequency and intensity needed for follow-up prescribed fires to control new EWP regeneration.

Kara Webster (kara.webster@nrcan-rncan.gc.ca), Canadian Forest Service - Natural Resources Canada
Paul W Hazlett (paul.hazlett@nrcan-rncan.gc.ca), Canadian Forest Service - Natural Resources Canada
Jason A Leach (jason.leach@nrcan-rncan.gc.ca), Canadian Forest Service - Natural Resources Canada
Erik J.S. Emilson (erik.emilson@nrcan-rncan.gc.ca), Canadian Forest Service - Natural Resources Canada
James M Buttle (jbuttle@trentu.ca), Trent University
Irena F Creed (irena.creed@utoronto.ca), University of Toronto Scarborough

Studies of harvest impacts on stream chemistry from deciduous forests with seasonal snow cover have shown variable responses and recovery times, and the interactive effects of harvests with regional and global environmental changes are largely unknown. We studied the response of stream solute concentrations under clearcut, selection, and shelterwood harvesting using a before-after control-impact experimental approach. The experiment was conducted at the Turkey Lakes Watershed, a shade-tolerant sugar maple forest within the Boreal Shield Ecozone, over a 36 year period (15 year pre-harvest and 21 year post-harvest) in which climate change and acidification recovery have been occurring. We found that harvest impacts on stream chemistry were greatest in the clearcut, moderate in the selection cut, and least in the shelterwood cut. The largest impacts on stream solutes typically lasted from 1 to 6 years following harvest, although some solutes were impacted the entire 21 year post-harvest period. Different patterns in solute response were observed including: Initial deviations (higher or lower) then returning to pre-harvest levels within 2-4 years (Na+, Ca2+, Mg2+, conductivity), initially increased but then decreasing but still not recovered (K+), initially higher than but then below pre-harvest levels (NO3-, Na+, Cl-), sustained higher levels (DOC, DIC, alkalinity, SiO2), and; little or noisy response (TP, SO42-, pH). The different patterns are consistent with expected changes in nutrient demand, sources (production and mobility), and hillslope-stream hydrologic connectivity. Comparing harvesting effects to long-term climate change and acidification recovery show that for some solutes harvesting had antagonistic (opposite) effects to environmental changes (e.g., cations), while for other solutes (e.g., DOC) harvesting had agonistic (additive) effects to environmental changes. These results emphasize the need for long-term monitoring to accurately interpret the consequences of forest harvesting practices on the resilience of forests experiencing environmental change

Samuel Powers Reed (reed0632@umn.edu), University of Minnesota
Dustin R. Bronson (dustin.bronson@usda.gov), US Forest Service Northern Research Station
Jodi A. Forrester (jodi_forrester@ncsu.edu), North Carolina State University
Leah M. Prudent (lprudent13@gmail.com), SUNY ESF
Peter B. Reich (pbreich@umn.edu), University of Minnesota
Lee E. Frelich (freli001@umn.edu), University of Minnesota

Canopy gaps, uncontrolled deer populations, and invasive European earthworms are three of the most common drivers of change in North American temperate forests, each influencing species composition and ecological function. Although these disturbances co-occur on the landscape, they are often studied separately. This presents a gap in our understanding of forest dynamics, as these disturbances may be linked and have unforeseen ecological consequences. There is some evidence that deer can facilitate earthworm invasion and that canopy gaps can influence earthworm populations. However, these relationships lack evidence and have not been considered in tandem. Our objective was to determine whether individual and combined deer and canopy gap treatments influence invasive earthworm biomass, density, and species assemblages by using two long-term multi-disturbance experiments in northern Wisconsin. We found that both deer and a closed canopy tend to increase earthworm invasion. Mean earthworm biomass was 26% greater outside of fencing than inside (p = 0.02), indicating that deer can facilitate earthworm invasion. Species in the genus Aporrectodea were particularly influenced by deer presence, showing a 35% increase outside of fencing (p < 0.01). Earthworms also tended to increase in biomass and density under a closed canopy (p < 0.01), with Lumbricus species showing the strongest preference for an intact canopy (p = 0.02). Our results show that there are surprising linkages among some of the most common disturbances in temperate forests and provide new insight regarding aboveground-belowground interactions. From a management perspective, this work also indicates that earthworm invasion could potentially be slowed by reducing deer populations and strategically harvesting trees in heavily infested soils.

Jack Goldman (jack.goldman@mail.utoronto.ca), University of Toronto
Marie-Josée Fortin (mariejosee.fortin@utoronto.ca), University of Toronto
Patrick M.A. James (patrick.james@utoronto.ca), University of Toronto

Increases in wildfire severity are expected to reduce forest ecosystem resilience as fire-adapted species are not necessarily adapted to high severity burning events. Climate warming is expected to increase the frequency of high severity fire and trends in boreal forest burn severity may diverge relative to historic range of variability. Since climatic conditions and fuel complexes can change at short timescales from hours to months or years relative to evolutionary timescales (decades to centuries), burn severity has the potential to change at a faster rate than species ability to adapt to burn severity. In Ontario, increasing seasonal and year-to year variability in moisture availability is heavily linked to fire activity and is expected to increase the occurrence of more high severity burning events. To date, it is not known at what temporal scale moisture availability has the greatest influence on the occurrence of high severity burning events. We examined trends in burn severity across the western boreal shield ecozone of Ontario to estimate the effects of both intra-annual and interannual moisture availability, and the additive effects of moisture availability and year of fire on the occurrence of high severity burning events and their extremes. Using remotely sensed burn severity maps generated in Google Earth Engine and historical climate data from 1986-2020, we quantified the effects of moisture availability (Climate Moisture Index; CMI) on trends in burn severity for 1227 fires (> 40 ha) that burned in the western boreal shield of Ontario. The occurrence of high severity burning events and of extremes within high severity burning events are best described by the additive effects of moisture availability and fire year. Burn severity extremes are impacted by both intra-annual and interannual moisture variability, whereas the occurrence of high severity events is not. Characterizing drivers of high severity burning events over time is important because of the broad and persisting ecological impacts of burn severity on ecological succession, biodiversity, and forest management.

Patricia Raymond (patricia.raymond@mffp.gouv.qc.ca), Direction de la recherche forestière, Ministère des Forêts, de la Faune et des Parcs du Québec
Daniel Dumais (daniel.dumais@mffp.gouv.qc.ca), Direction de la recherche forestière, Ministère des Forêts, de la Faune et des Parcs du Québec

Also known as the temperate mixedwood forest, this ecotone marks the transition between temperate and boreal forests in Eastern Canada. Its proximity to inhabited areas has made it an important supply of varied high-quality forest products over the two last centuries, but also a preferred place for recreational activities. Sustainable management of this forest requires a balance of socio-economic and ecological needs to sustain wood production and ecosystem services. First trials of timber-oriented mixedwood management in the 1990's were tailored for either conifer or northern hardwood stands. They proved to be poorly adapted to mixedwood stands, especially because they did not emulate natural dynamics. With the interdiction of pesticide use in public forests, a silviculture approach better adapted to mixedwood stands was needed. Early beginnings of mixedwood silviculture in the province of Québec found inspiration in the Stratégie de protection des forêts, published in 1992. This report recommended a closer emulation of natural dynamics to limit problems with interspecific competition, to rely on natural regeneration whenever possible, and to manage for species diversity to increase resistance to pests and productivity. Later, ecosystem management considerations highlighted the importance of retaining biological legacies when managing late-successional forests. This talk will present the natural developmental model for yellow birch-conifer ecosystems and their associated ecological silviculture. Since natural dynamics for mixedwood ecosystems result in an increase of conifers, late-successional species, and structural complexity over time, an ecological silvicultural system should aim at enhancing these attributes. In young stands, the goal is to facilitate natural development by increasing the proportion of conifers and late-successional species. In mature and old-growth stands, actions will aim at promoting diversity and structural complexity by ensuring the establishment of a regenerating cohort at each entry and by retainining biological legacies.

Marion Noualhaguet (marion.noualhaguet@uqat.ca), IRF - Université du Québec en Abitibi-Témiscamingue (UQAT)
Maxence Soubeyrand (maxencemarian.soubeyrand@uqat.ca), IRF - Université du Québec en Abitibi-Témiscamingue (UQAT)
Timothy T. Work (work.timothy@uqam.ca), CEF - Université du Québec à Montréal (UQAM)
Nicole Fenton (nicole.fenton@uqat.ca), IRF - Université du Québec en Abitibi-Témiscamingue (UQAT)

Sustainable forest management relies on a diversity of harvesting practices to conserve different variety of stand structures and compositions found in natural forests. While clear cuts remove all the canopy and damage the forest floor and pre-existing downed woody debris, partial cuts maintain more standing overstory and conserve some biological legacies like large live trees as well as standing and downed dead wood and thus should better conserve biodiversity. However, given the large number of species potentially affected by harvest operations, optimizing harvesting and conservation requires clear understanding of habitat requirements and maintained species post-harvest. We examined the effects, 20 years after increasing harvest intensities with 33%, 40%, 66% and 100% stems removal on bryophyte communities across three stand types common in the succession of Eastern boreal mixedwood forests that were dominated by trembling aspen, mixedwood and conifers. Harvesting in mixedwood stands had more pronounced effects on bryophyte communities than harvesting in predominantly hardwood stands, showing that bryophyte species in hardwood stands were able to better tolerate fluctuations in seasonal conditions. In coniferous stands, a spruce budworm outbreak occurred 30 years ago and disrupted the classic evolution expected for bryophyte communities. Many generalist species, considered as good colonizing and perennial species, were shared between all levels of harvesting, among the three forest types. In contrast, for more specialized and sensitive species like liverworts, more differences between communities from control and clear-cut stands than between control and partial cut stands were found. These results highlight the importance of harvesting level and forest stands types where cuts are practiced for maintaining bryophytes in managed forests. Implementation of conservation strategies for bryophytes in managed boreal forests requires regular monitoring over time to understand species diversity, not only at local scales but also differences among entire forest stands

Ellen Macdonald (ellen.macdonald@ualberta.ca), Dept. of Renewable Resources, University of Alberta
Phil Comeau (phil.comeau@ualberta.ca), Dept. of Renewable Resources, University of Alberta
Brad Pinno (bpinno@ualberta.ca), Dept. of Renewable Resources, University of Alberta
Charles Nock (nock@ualberta.ca), Dept. of Renewable Resources, University of Alberta

Mixedwood boreal forests in western Canada are characterized by varying dominance by broadleaf (primarily trembling aspen) and conifer (primarily white spruce). Reflecting prior disturbance history and complex patterns of stand dynamics, these forests are often multi-storied and can be uneven-aged. Clearcutting followed by site preparation and planting of spruce has been the dominant practice for the past four decades. Increasing utilization of aspen for pulp and oriented strand board, and greater interest in ecological approaches, has precipitated a need for approaches to manage these forests as mixtures. Ecological silviculture needs to recognize the range of variation in dominance by broadleaf versus conifers, that stands naturally transition among these over time, and might switch between states due to a disturbance event. Regulations governing public forests should, therefore, be flexible enough to allow for such variation. Increased reliance on natural regeneration of white spruce could be an option if sufficient seed trees are left and some variability in conifer stocking is permitted. For broadleaf-dominated stands with a conifer understory, understory protection harvesting can be used, and will facilitate a transition to a multi-aged or irregular mixture. For conifer-dominated or broadleaf-dominated stands where both species are merchantable, retention harvesting followed by natural regeneration of both species could lead to a mixed stand that was suitable for later understory protection to transition it back towards conifer-dominance. Underplanting of spruce can be used to create a mixture for later understory protection. In recent decades, changes in moisture regimes have resulted in forest die-back and loss in drought prone areas. However, in appropriate regions and sites, mixedwood regimes could facilitate establishment of white spruce, with aspen serving to reduce injury to spruce resulting from climatic extremes. Such mixtures may also confer greater resilience to impacts of aspen and spruce defoliators.

Maitane Erdozain (maitane.erdozain@gmail.com), University of New Brunswick
Karen Kidd (karenkidd@mcmaster.ca), McMaster University
Erik J.S. Emilson (erik.emilson@nrcan-rncan.gc.ca), Canadian Forest Service - Natural Resources Canada
Michelle Gray (mgray1@unb.ca), University of New Brunswick
Lauren Negrazis (negrazla@mcmaster.ca), McMaster University
Dave Kreutzweiser (davek.636@gmail.com), Canadian Forest Service - Natural Resources Canada

Though effects of forest management on small streams are well documented and include changes in water quality, sediment inputs and biodiversity, little is known about the cumulative effects in downstream systems. To elucidate such effects, over two years we investigated whether several abiotic and biotic indicators changed from smaller to larger downstream sites (n=6) within three river basins that had different intensities of forest management (all types of harvesting plus silviculture), with total catchment disturbances of 7.3%, 12.7%, and 23.0% in New Brunswick (Canada). Longitudinal trends for some endpoints differed across basins and indicated cumulative or dissipative effects of forest management. For the former, inorganic sediment deposition increased longitudinally in the basin with moderate disturbance, but not in the other two. In the basin with minimal disturbance, the proportion of algae in the diet of some aquatic insects increased longitudinally; however, this increase was not observed within the moderately disturbed basin and was weaker within the most disturbed one, also suggesting cumulative effects. Conversely, differences among basins decreased longitudinally for other indicators, suggesting dissipative effects of forest management. For example, water temperature in the minimally disturbed basin increased in downstream sites, but this trend was weaker in the most disturbed basin and absent in the basin with moderate disturbance. This pattern was also observed for mercury concentrations in some aquatic species and their food sources. The impacts of forest management on streams were generally greatest in the basin with higher areas of clearcutting and no tree regeneration and moderate total disturbance, suggesting that greater overall intensity of forestry does not necessarily translate into greater environmental impacts when more sustainable practices are applied (e.g., partial vs. clearcut harvest). Modified management practices within the extensive basin may reduce some of the cumulative downstream effects described herein.

Angel Rolando Agramont (arendaraa@uaemex.mx), Universidad Autónoma del Estado de México
Alma Abigail Luna Gil (abi.lugi@gmail.com), Universidad Autónoma del Estado de México
Luis Antonio García Almaráz (antoniogarcia013@hotmail.com), Universidad Autónoma del Estado de México
Rebeca Dennise Varo Rodríguez (varodennise@gmail.com), Universidad Autónoma del Estado de México
Miriam Alejandra Rosas Sánchez (miriam_rosas25@outlook.es), Universidad Autónoma del Estado de México
José Jonathan Aguirre Zúñiga (latemtan@gmail.com), Universidad Autónoma del Estado de México
Luis Daniel Carbajal Romero (luis-dan18@hotmail.com), Universidad Autónoma del Estado de México
Rafael Calderón Contreras (rcalderoncontreras@yahoo.com), Universidad Autónoma Metropolitana

The effects of global environmental change are especially important in sensitive social-ecological systems, such as high mountain forests. Their provision of ecosystem services is vital for the subsistence of often distant places, such as urban settings. High mountain forests present ecological problems associated with climate change such as the altitudinal migration of species and extensive forest infestations. These effects are often linked with anthropogenic disturbances such as selective logging, land use change and wildfires. High mountain forests in Mexico (?3,500 masl) cover approximately 52,000 hectares, mainly established, around the tallest volcanic buildings in the country (Pico de Orizaba, Popocatepetl, Iztaccíhuatl, Nevado de Toluca, Monte Tláloc, Nevado de Colima, Cofre de Perote and La Malinche). This research is based on the analysis of 2,885 circular sampling sites (SS) (1,000m2 each) that were established in just over 31,000 hectares, using the contour lines as transects to access the forest, distributed every 100m in altitude, between 3,500 and 4,000 masl. The objective of the research was to determine the spatial distribution and infestation levels of the dwarf mistletoe (Arceuthobium spp) on Pinus hartwegii populations in Mexico. The results show that 37% of the sampled surface presents some level of attack by dwarf mistletoes, distributed in all diameter categories. These percentages are well above the natural limits of pathogen abundance and distribution. These areas and levels of infestation in high mountain pine forests can affect the establishment of natural regeneration and, in the medium term, increase mortality rates. The research analyzes the implications of the distribution of dwarf mistletoe while proposing management strategies aimed at reducing the levels of infestation found.

Tyler Refsland (refs016@gmail.com), Michigan State University
Bryce Adams (bryce.adams@usda.gov), U.S. Forest Service
Dustin Bronson (dustin.bronson@usda.gov), U.S. Forest Service
Christel Kern (christel.c.kern@usda.gov), Northern Research Station, USDA Forest Service
Paula Marquardt (marqua17@msu.edu), U.S. Forest Service
Amanda McGraw (amanda.mcgraw@wisconsin.gov), Wisconsin Department of Natural Resources
Alejandro Royo (alejandro.royodesedas@usda.gov), Northern Research Station, USDA Forest Service
Jessica Miesel (mieselje@msu.edu), Michigan State University

Many Eastern North American tree species are considered vulnerable to climate change because tree populations typically exhibit local adaptation to climate. The provisioning of critical forest ecosystem services may be threatened if tree populations are unable to migrate or adapt with changing climate, and therefore become increasingly maladapted with local conditions. This emerging mismatch underscores the need for adaptive management techniques like assisted migration (AM) to help mitigate the impacts of climate change. A key to the success of AM is understanding the abiotic and biotic constraints of tree establishment, including how trees affect and are in turn affected by the local soil environment and microbial community, referred to as plant-soil feedbacks (PSF). We assessed the current state of knowledge and synthesized the effects of PSF on tree growth and survival by conducting a meta-analysis of 25 published studies. Our goal was to synthesize the direction and size of PSF effects on temperate tree species and identify key hypotheses to test in future work. Our compiled database included 67 tree species and was composed primarily of short-term greenhouse experiments that studied PSF effects by manipulating soil biota in three ways: (1) soil was previously inoculated by a conspecific or heterospecific tree species (i.e., home versus away), (2) soil was live or sterilized, or (3) soil was untreated or treated with fungicide. We found that regardless of manipulation type, PSF had highly variable effects on tree survival. In contrast, tree growth was significantly affected by PSF. Specifically, arbuscular mycorrhizal tree species grown in live or home soils grew 13-33% less than those in sterile or away soils, while ectomycorrhizal tree species grew 11-44% more in live or home than sterile or away soils. Our synthesis of context-dependent effects of PSF on tree performance will help inform management decisions involving assisted migration.

Tara L. Keyser (tara.keyser@usda.gov), USDA Forest Service, Southern Research Station
Jodi A. Forrester (jodi_forrester@ncsu.edu), North Carolina State University
David Schnake (dkschnak@ncsu.edu), North Carolina State University

In the Southern Appalachians, most active forest management occurs in mid-elevation forests where mixed-oak forests dominate the landscape. Stand reconstruction studies suggest the structure and composition of these forests prior to Euro-American settlement were complex, with high levels of heterogeneity at both the stand and landscape level. These conditions were created from a suite of natural and anthropogenic disturbances including fire, small-scale gap dynamics, disease, and intermediate intensity disturbances. Land abandonment, exploitive logging, wildfires, and grazing in the mid to late 20th century combined to reshape the forests, reducing the structural complexity at both the stand and landscape level. Traditional silvicultural methods have had only moderate to poor success in regenerating oak or maintaining structural diversity. A moderate overstory or midstory disturbance is needed for mid-tolerant oak and hickory seedlings to develop into large advance reproduction capable of successfully competing with both shade tolerant and intolerant species after severe overstory disturbance. Observations following natural or silvicultural created gaps indicate that while competitors thrive in the canopy opening, oak seedlings display greater growth along the gap edge. Our work is exploring the interactions between edge and oak growth and survivorship as the basis for an expanding gap silvicultural approach for regenerating mixed-oak forests. This method expands the area created around initial gaps during each harvest entry as opposed to creating new, independent gaps, and is thus more similar to the process of natural gap dynamics in the region. The large advance reproduction that develops along the periphery of the created gap is released with subsequent entries. The method, proven successful in northern forests, is being customized and tested in a large, field experiment in Pisgah National Forest. We propose the approach will not only increase oak regeneration, but also structural and species diversity, and carbon sequestration and storage.

Patricia Raymond (patricia.raymond@mffp.gouv.qc.ca), Direction de la recherche forestière, Ministère des Forêts, de la Faune et des Parcs du Québec
Alejandro Royo (alejandro.royodesedas@usda.gov), Northern Research Station, USDA Forest Service
Christel Kern (christel.c.kern@usda.gov), Northern Research Station, USDA Forest Service
Emilie Champagne (emilie.champagne@mffp.gouv.qc.ca), Département des sciences du bois et de la forêt, Université Laval
Daniel Dumais (daniel.dumais@mffp.gouv.qc.ca), Direction de la recherche forestière, Ministère des Forêts, de la Faune et des Parcs du Québec
Catherine Périé (catherine.perie@mffp.gouv.qc.ca), Direction de la recherche forestière, Ministère des Forêts, de la Faune et des Parcs du Québec
Jean-Pierre Tremblay (jean-pierre.tremblay@bio.ulaval.ca), CEF - Université Laval
Alison Munson (alison.munson@sbf.ulaval.ca), CEF - Université Laval

Assisted migration, the deliberate displacement of tree species or populations to locations with suitable future climate conditions, is recommended to help forests coping with global change. However, more knowledge is required to make possible a large-scale application of this adaptation tool, namely regarding the effects of abiotic (e.g. microclimate) and biotic (e.g. browsing, competing vegetation) stressors and their interactions on seedling survival and growth. In 2018, we set an experiment in the temperate-boreal ecotone of the balsam fir (Abies balsamea)-yellow birch (Betula alleghaniensis) bioclimatic domain, 120 km northwest of Quebec City, Quebec, Canada. The goal was to test in operational conditions assisted migration mixedwood plantings composed of five conifers (Picea glauca, Picea rubens, Pinus strobus, Pinus resinosa, Thuya occidentalis) and four deciduous (Acer saccharum, Quercus rubra, Prunus serotina, Carya ovata) species. We used seedlings grown from seeds of locations associated to three climate analogues: current climate (Quebec City greater area), projected climates for 2050 (Eastern Townships) and 2080 (Nova Scotia and Northeastern USA). The factorial experimental design comprised canopy cover (clearcut vs partial cut), cervid exclusion (excluded vs non-excluded) and competing vegetation (removed vs non-removed) treatments. After 3 years, our results show that seedlings planted in open conditions grew generally better than those under partial cover. The latter option, however, could be helpful to acclimate southern species such as Quercus rubra, which suffered frost damage during the Spring 2020 and 2021, mostly in clearcuts. Conifers and Quercus also benefited of the competing vegetation control by mechanical release (brushing) applied in 2020. The high survival rate observed after 3 years (89%) indicate that the assisted migration of species and populations could be sound. Yet, this approach has limits since southern species appear more vulnerable to stress and those moved over greater distances tend to perform less well.

Tim Philpott (tim.philpott@gov.bc.ca), BC Ministry of Forests
Gabriel Danyagri (gabriel.danyagri@gov.bc.ca), BC Ministry of Forests
Brian Wallace (brian.wallace@gov.bc.ca), BC Ministry of Forests
Mae Frank (Mae_Frank@live.com), BC Ministry of Forests

Wildfire recovery, both from a carbon and timber perspective, are key management objectives for many fire-affected ecosystems across British Columbia. However, the impacts of wildfire on soil carbon storage, and on fungal communities that regulate soil carbon dynamics, are poorly characterized. Here, we examined the response of fungal communities and soil carbon storage across a range of fire severities in a Douglas-fir ecosystem. Fire severity strongly structured fungal communities, explaining 16% of variation in community composition. High and medium-severity wildfire dramatically reduced the abundance root-associated fungi in forest floor and mineral soils, while promoting opportunistic fungi and some saprotrophs. In both mineral soils and the forest floor, low-severity wildfire only marginally impacted fungi across a range of functional guilds. Likewise, bulk forest floor and mineral soil carbon stocks were resilient to low-severity wildfire. Total consumption of the forest floor under high-severity wildfire reduced carbon stocks by 16.4 Mg/ha relative to unburned stands. For mineral soils, most of the carbon stock (61-69%) was in the light fraction, which was most susceptible to carbon loss; between 20-40% of light fraction carbon was lost due to wildfire, and losses increased with fire severity. Mineral-associated carbon stocks were also reduced by wildfire, but only under low and medium fire severity. Wildfire increased the proportion of pyrogenic carbon by 3.8% and 3.1% for bulk soil and mineral-associated carbon, respectively, suggesting a post-fire increase in resistant soil carbon that may have associated with the mineral fraction. Overall, the impacts of low-severity wildfire on fungal communities and soil carbon storage were marginal relative to the dramatic effects seen in medium and high fire severity. Management activities such as prescribed burning or thinning that promote more frequent low-severity wildfire or prevent catastrophic wildfire may better protect soil carbon storage and maintain healthy fungal communities in the long term.

Kevin M. Potter (kpotter@ncsu.edu), North Carolina State University
Flint Hughes (flint.hughes@usda.gov ), USDA Forest Service, Institute of Pacific Islands Forestry
Christian Giardina (christian.p.giardina@usda.gov), USDA Forest Service, Institute of Pacific Islands Forestry
Susan Cordell (susan.cordell@usda.gov), USDA Forest Service, Institute of Pacific Islands Forestry
Olaf Kuegler (olaf.kuegler@usda.gov), USDA Forest Service, Pacific Northwest Research Station
Emma Yuen (emma.yuen@hawaii.gov ), Hawaii Division of Forestry and Wildlife, Native Ecosystems Protection and Management Program
Amy Koch (amy.koch@usda.gov), USDA Natural Resources Conservation Service, Pacific Islands Area

Hawaii is a global hotspot of species invasion, with non-natives severely threatening the biodiversity of its forests. We conducted the first comprehensive and field-based assessment of native and non-native forest plants from forest floor to canopy across Hawai'i, using data from a network of 238 standardized plots. Non-native species accounted for about a third of large tree stems and carbon, but two-thirds of sapling stems and carbon and seedling stems. Utilizing the statistical design of the plot network, we estimated that non-native species were present in 56% of Hawai'i's forest area and dominated 39%. In all forest types, non-native trees constituted a larger proportion of the understory than the overstory tree component. This lack of sufficient native regeneration may result in replacement of native canopy trees by non-native trees following tree mortality events. Low elevations on the oldest islands exhibited the highest degree of non-native species dominance while high elevations on the youngest islands had higher native species dominance. Forests on public lands, in conservation reserves, or in fenced areas managed as ungulate-free were less impacted by non-native trees and shrubs. For example, fenced plots were 75% less impacted by non-native plants than unfenced plots on average. These differences may reflect effective management and/or differences in initial conditions of those forests because fenced or designated core conservation areas are often located in high-quality forest. The study results are a concerning evaluation of the ecological integrity of Hawaiian native-dominated forests and have implications for monitoring and managing non-native plants across Pacific Island forests and beyond.

Justin Hart (hart013@ua.edu), University of Alabama
J. Davis Goode (jdgoode2@crimson.ua.edu), University of Alabama
Daniel Dey (daniel.c.dey@usda.gov), USDA Forest Service

In the southeastern US, pine (Pinus) and oak (Quercus) species may co-occur across a wide range of site types and exist in a diversity of assemblages. Pine-oak ecosystems (defined here as any stands that contain some mixture of pine and oak) can be quite variable in species richness, canopy cover, tree density, and basal area among other factors. This variability is attributed in part to the diversity of site conditions that can support pine-oak assemblages, land-use and management history of stands, and the range of species from these genera that may be dominant. In mixed pine-oak stands, oak species are generally more shade tolerant than co-occurring pines. However, these systems may include taxa that are more tolerant of shade than the oaks. Some of the classic research in plant succession was conducted in pine-oak stands in old fields of this region. Along this successional pathway, pine dominance gives way with time to more shade-tolerant and slower growing oak species. Initially in such systems, ecological memory of oak is absent (i.e., no oak root stocks) due to previous deforestation and later agricultural abandonment. In catastrophically disturbed pine-oak stands, the successional pathway may be different as oak and other hardwood species are able to sprout from existing root stocks. In older pine-oak systems, pines often exist as patches within what are largely oak-dominated stands. We hypothesize these pine patches are created and maintained by the combination of intermediate-severity canopy disturbances and low-intensity surface fires. Disturbance history reconstructions show the return interval of intermediate-severity disturbances in these systems is typically 20-50 years. Therefore, we propose a silvicultural system to create and maintain neighborhood-level pine dominance in oak stands by utilizing prescribed fire and canopy openings. This system acknowledges intra-stand spatial patterns of species composition and can be adapted to rely on natural or artificial pine regeneration depending on site conditions.

Amanda Lynn Schoonmaker (aschoonmaker@nait.ca), Northern Alberta Institute of Technology
Adam Mathison (amathison@nor-alta.com), University of Alberta
Derek Mackenzie (mdm7@ualberta.ca), University of Alberta

Native herbaceous plants such as fireweed (Chamerion angustifolium), goldenrod (Solidago canadensis) and asters (Aster spp.) are important components when re-vegetating industrial sites. They may provide protection for shade-tolerant woody species, create desirable native vegetation cover and may provide a barrier to invasion of weedy species by occupying physical space. Native forbs may be introduced on reclaimed industrial sites through broadcast seeding or natural ingress. Planting native forbs, utilizing similar procedures to conventional planting of tree or shrub species, is another approach though it is less common. As an alternative, incorporating or hitchhiking native forbs into the same nursery container as a shrub or tree is a potential means of efficiently establishing native forbs on a disturbed site. The objective of the present study was to test the principle of hitchhiker production (i.e., growing two species in the same container) of a tree species with native herbaceous species in recently reclaimed industrial sites. White spruce (Picea glauca) was chosen due to the depth of knowledge behind growing container stock of this species. Showy aster (Eurybia conspicua) and fireweed were chosen as hitchhikers for the study and are known to develop rapidly following disturbance. White spruce was sown in nursery containers of contrasting cavity sizes, followed by sowing one of the forb species at different time intervals, to produce hitchhiker stock with a range of root and shoot characteristics. In this presentation, we will answer the following questions: (1) Is it possible to produce a mixed species container stock that results in the growth and persistence of both species? (2) How critical are stock production considerations such as cavity size and timing of sowing, in developing hitchhiker stock? (3) Does the established forb impact vegetation dynamics (reduce competition) of other undesirable species in the immediate vicinity of the white spruce seedling?

Peter Clark (peter.clark@uvm.edu), University of Vermont
Anthony D'Amato (awdamato@uvm.edu), University of Vermont
Kevin Evans (Kevin.S.Evans@dartmouth.edu), Dartmouth College
Paul Schaberg (paul.schaberg@usda.gov#), USDA Forest Service Northern Research Station
Christopher Woodall (christopher.w.woodall@usda.gov), US Forest Service Northern Research Station

Species distribution models forecast climate-induced shifts in forest habitat, yet tree migration rates lag climate change, leading to potential misalignment of species with future climate conditions. As such, forest adaptation strategies have been broadly proposed to adjust species composition via assisted migration of climate-suitable species. Nevertheless, empirical evaluations are limited, particularly mixed-species adaptation plantings tested within the context of ecological memory or extreme climate events. Here, we present on the initial (3-year) response from over 5,000 future-climate-adapted seedling transplants from nine species within operational-scale silvicultural trials in northeastern US temperate forests, including the New England installation of the Adaptive Silviculture for Climate Change project (ASCC). Our results show the performance of seedling transplants is based on species (e.g., functional attributes), the strength of local competition (e.g., ecological memory) and assisted migration type (e.g., "population enrichment" vs. "assisted range expansion"), a proxy for source distance. Compared to locally adapted enrichment plantings, assisted range expansion species planted outside range limits had lower survival (59.0% ±2.0 vs. 49.0% ±2.6, p=0.007, respectively) and growth (relative growth rate in above-ground biomass: 2.5 ±0.03g g-1 yr1 vs. 2.0 ±0.05g g-1 yr1, p=0.01, respectively), suggesting maladaptation. These findings were regionally consistent but were altered based on site-specific conditions such as browse, climate misalignment (e.g., winter injury), and extreme climate events (e.g., drought, spring frost). Although this work demonstrates that managing for shifts in future forest composition represents a promising adaptation strategy for incorporating new species and functional traits into contemporary forests, important barriers remain for the establishment of climate-adapted forests that will most likely require management intervention. Nonetheless, the broader applicability of our findings demonstrates the potential for adaptation

Samuel F. Bartels (samuel.bartels@unbc.ca), University of Northern British Columbia
Chiara Chirico (chirico@unbc.ca), University of Northern British Columbia
Ellen Macdonald (ellen.macdonald@ualberta.ca), University of Alberta

Interactions between overstory and understory vegetation are a commonly described, but poorly understood, component of ecological dynamics in closed-canopy forests. Overstory trees exert strong controls on understory shrub and herbaceous layer species by limiting available light and growing space, but it is unclear the extent to which overstory removal, through harvesting, affects competitive and/or facilitative relationships among understory plants during the subsequent transition from open-to closed-canopy forests. We used plant species cover data from 108 permanent sample plots to test the direct and indirect effects of the hierarchical vertical interactions between tall statured understory shrubs and lower vegetation layers (low shrubs, forbs, graminoids, bryophytes) in mature boreal mixedwood forests in northwestern Alberta, Canada. We explored how these interactions change with varying intensity of harvesting (clear-cut, 10%, 20%, 50%, and 75% retention, unharvest control) and time since harvest (3 - 17 years post-harvest). The interactions between the understory layers across the harvesting treatments, including the reference, were characterized by a mix of direct and indirect positive and negative interactions, with the specifics varying with time since harvest. Across all treatments, many weak or non-significant positive interaction effects observed at 3- and 6-years post-harvest appeared to change to weak or strongly negative relationships by 11- and 17- years post-harvest in clear-cut and lower retention treatments. This largely suggested a shift from facilitative interactions immediately after harvesting, due to increased availability of light resources and growing space, to competitive interactions as resources become limited and the stand transitions to closed-canopy conditions. Our results confirm the existence of a dynamic relationship between forest understory plants that is moderated by overstory tree removal. Thus, harvesting may disrupt ecological interaction networks in the understory beyond the intended consequences.

Colin Bergeron (colin.bergeron@pc.gc.ca), Dept. of Renewable Resources, University of Alberta
Ellen Macdonald (ellen.macdonald@ualberta.ca), Dept. of Renewable Resources, University of Alberta
John Spence (john.spence@ualberta.ca), Dept. of Renewable Resources, University of Alberta

Partial harvesting has been promoted as an alternative to clearcut harvesting that could enhance carbon storage in managed forests. We examined carbon in response to variable retention harvesting (clearcut, 10,%, 20%, 50%, 75%, unharvested reference) in boreal mixedwood forests dominated by varying mixtures of broadleaf (mainly trembling aspen) and conifer (mainly white spruce). The research was conducted at the EMEND (Ecosystem Management Emulating Natural Disturbance) study in northwestern Alberta, Canada. We used data from 432 permanent sample plots, allometric equations, wood density measurements on deadwood, and nutrient analyses to calculate carbon for: above- and below-ground biomass of mature trees, regenerating trees and shrubs; dead downed woody debris; snags; stumps and roots of harvested trees. Total carbon storage pre-harvest was greater in conifer-dominated and mixedwood forests than in broadleaf-dominated forest types. This was largely attributable to the greater live tree above-ground biomass and, to a lesser extent, the biomass of downed woody material. Harvesting resulted in net loss of carbon in the short term and this scaled with harvesting intensity. Broadleaf forests, even with low levels of retention, were net carbon sinks shortly after harvest. This was attributed to tree growth and tree and shrub regeneration, but this could be offset by root decomposition. In contrast, mixedwoods were net sources of carbon up to 10 years post-harvest with retention levels of 20% or less. Conifer-dominated forests were net sources of carbon up to 10 years post-harvest with retention levels of 50% or less. This was attributable to the fact that tree growth and regeneration in lower retention levels were offset by mortality of conifer trees and root decomposition. Soil carbon varied less among forest types and harvesting treatments and was thus not a major factor in differences related to harvesting intensity.

Margaret Woodbridge (margaret.woodbridge@usda.gov), USDA Forest Service, Southern Research Station
Tara L. Keyser (tara.keyser@usda.gov), USDA Forest Service, Southern Research Station
Christopher Oswalt (christopher.oswalt@usda.gov), USDA Forest Service, Southern Research Station

There is a growing body of evidence that mesic tree species are increasing in importance across much of the eastern US. This increase is often observed in tandem with a decrease in the abundance and importance of species we often consider to be better adapted to disturbance and drier conditions (e.g., Quercus species). Concern over this transition is related to several factors, including the potential that this transition is self-reinforcing (termed 'mesophication'), will result in decreased resiliency of forests to a variety of disturbances, and may negatively impact ecosystem functioning, timber value, and wildlife habitat. Evidence for shifts in taxonomic and functional composition provide broad-scale support for mesophication, but we lack information on the fine-scale factors that drive this change. Understanding the variability of mesophication on this scale is particularly important as managers work to develop site- and condition- specific management practices to target stands or portions of the landscape most at risk to mesophication. To address this knowledge gap and identify forests that are most susceptible to mesophication, we used data from the USDA Forest Service Forest Inventory and Analysis program to determine (1) what fine-scale factors impact mesophication in eastern US forests and (2) which trait groups (e.g., shade, drought, and/or fire tolerance) are most strongly tied to the observed changes in composition. In many cases, we found that the effect of factors associated with site quality, such as soil and topographic characteristics, varied by trait group. For example, mesophication was generally more pronounced in wetter sites, but plots categorized as ‘hydric’ were highly variable and exhibited increased drought and fire tolerance through time. Mesophication was also greater in older stands and stands with greater variation in tree diameters. Our results provide evidence that stand-scale conditions impact current and potential future changes in trait conditions and composition.

Chibuike Chigbo (chibuikec@nait.ca), NAIT-CBR
Stefan Schreiber (sschreib@ualberta.ca), Center for Boreal Research, NAIT
Arantxa Pino Persico (arantxap@nait.ca), Clean Technologies, NAIT
Paolo Mussone (pmussone@nait.ca), Clean Technologies, NAIT
Amanda Lynn Schoonmaker (aschoonmaker@nait.ca), Northern Alberta Institute of Technology

Resource exploration and extraction is often associated with the disturbance of forested lands. One of the key factors to achieve successful reforestation is the nutritional quality of the topsoil. Poor soils may be treated with inorganic fertilizers, but this practice can encourage the growth of highly competitive non-native species and significantly slow down natural succession of native species. Nutrient loading during nursery production with inorganic fertilizers is another technique, however, the positive effect following out-planting may not be as long-lasting. The objective of this study was to develop a solution rooted in circular economy principles to facilitate improved establishment on reclaimed industrial sites using organic amendments with the goal to provide multi-year benefit after outdoor planting. This project was articulated into two phases: (1) seedling production of Populus tremuloides (aspen) and Betula papyrifera (paper birch) with incorporation of four rates of raw alfalfa pellets and three rates of hydrochar (thermal hydrolysis) produced from alfalfa pellet feedstock, into growth substrate during nursery stock production and (2) planting of seedlings into 2L containers filled with soil from a recently disturbed mine site. Both phases were conducted under controlled greenhouse conditions. Results showed that alfalfa treated seedlings, but not hydrochar, significantly increased the leaf, stem, and root biomass of aspen and paper birch seedling stock. After out-planting, only alfalfa treated seedlings appeared to show superior stem and root growth compared to standard seedlings with aspen stem mass increasing from 1.74 g to ~ 3 g at the highest alfalfa application rate. This novel approach to nutrient-loading seedlings demonstrated promise in improving plant growth, however, future testing in field conditions, over multiple years is required to fully demonstrate the impact of this treatment. This study provides a platform from which to explore other sources of organic amendments, potentially from waste streams, thereby diverting materials from landfills and promoting a circular economy approach to nursery seedling production.

Melissa Boyd (boydamelissa@gmail.com), Northern Arizona University
Xanthe J. Walker (xanthe.walker@nau.edu), Northern Arizona University
Logan T. Berner (logan.berner@nau.edu), Northern Arizona University
Patricia Doak (pdoak@alaska.edu), University of Alaska Fairbanks
Scott J. Goetz (scott.goetz@nau.edu), Northern Arizona University
Brendan M. Rogers (brogers@woodwellclimate.org), Woodwell Climate Research Center
Diane Wagner (diane.wagner@alaska.edu), University of Alaska Fairbanks
Michelle C. Mack (michelle.mack@nau.edu), Northern Arizona University

Trembling aspen (Populus tremuloides), a dominant tree species across North America's boreal forests, is threatened by climate change-driven warming, drying, and persistent insect infestation. An outbreak of the aspen epidermal leaf miner (Phyllocnistis populiella Cham.; henceforth "leaf miner") that began in the late 1990s and continues today has resulted in widespread aspen damage across Interior Alaska. Leaf miner is an herbivorous moth native to North America whose larvae consume the epidermal cells of aspen leaves in the summer months. This negatively impacts tree water relations and results in reduced photosynthesis and early leaf abscission. Despite the otherwise primary impact of climate on aspen growth, we have shown that leaf mining can be the dominant driver of reduced aspen tree-ring width, effectively de-coupling a tree's growth from climate variations. However, in this region historical droughts decreased aspen ring width and vitality, predisposing this tree to mortality during the current leaf miner outbreak. This highlights the importance of compounding stressors on aspen vigor, and the need to consider the impacts of past events when addressing aspen vulnerability to dieback. Our work also reveals that the normalized difference vegetation index (NDVI), a remotely sensed index of vegetation productivity, captures aspen mortality but is more strongly related to growth, highlighting potential limitations of this index in detecting insect-driven aspen death. Here we discuss previous and current research addressing the fate of aspen in Alaskan boreal forests under continued climate change, and the impacts of this on boreal forest composition and function.

David M. Bell (david.bell@usda.gov), USDA Forest Service Pacific Northwest Research Station
Matthew Reilly (matthew.reilly@usda.gov), USDA Forest Service Pacific Northwest Research Station
Andrew N. Gray (andrew.gray@usda.gov), USDA Forest Service Pacific Northwest Research Station
Matthew Gregory (matt.gregory@oregonstate.edu), Oregon State University

The strength and direction of tree mortality responses to drivers like competition and water limitation likely vary both across species and with tree size. Therefore, managers need species- and size-specific, spatially-explicit assessments of potential tree mortality to help prioritize restoration and other management treatments. In this study, we propose a framework for integrating tree mortality models based on regional forest inventory data with 30-m mapped vegetation data to characterize spatial patterns in tree mortality vulnerability across the diverse landscapes of eastern Oregon and Washington. We developed a hierarchical Bayesian size- and species-dependent tree mortality model to relate forest inventory based tree morality observations with forest structure, topography, and climate. Small-diameter trees exhibited increases and large-diameter trees exhibited decreases in mortality in forests with high basal area or large trees. For two species - Douglas-fir and ponderosa pine - mortality was greatest at lower topographic positions. Large tree mortality often increased and small tree mortality often decreased with water deficit. Using the product of mapped tree densities and predicted mortality probabilities for each species and size-class (hereafter, mapped tree mortality vulnerability), we applied our modeling results to all forested lands in the study area based on existing maps of covariates (stand structure, topography, and climate) and tree species and size-class distributions. Mapped tree mortality vulnerability indicated both regional- and landscape-level mortality gradients associated with climate as well as stand-level patches of elevated or reduced mortality often related to stand structure and topography. Thus, the species- and size-dependent tree mortality sensitivities characterized by our statistical model, as filtered through the existing patterns of forest structure, forest composition, topography, and climate, indicated complex spatial patterns in tree mortality vulnerability at multiple scales.

Rebecca Montgomery (rebeccam@umn.edu), University of Minnesota
Leslie Brandt (leslie.brandt@usda.gov), USFS Northern Research Station
Auste Eigirdas (eigir001@umn.edu), UMN
Mary Hammes (mhammes@parkconnection.org), Mississippi Park Connection
Linda M Nagel (Linda.Nagel@colostate.edu), Colorado State University
Courtney Peterson (Courtney.Peterson@colostate.edu), Colorado State University
Marcella A. Windmuller-Campione (mwind@umn.edu), University of Minnesota

Natural resource managers grapple with how to adapt forest management practices to a changing climate. Currently, there is a paucity of information on practices to achieve desired vegetation conditions under changing climate, especially for urban forests. We introduce an urban installation of the Adaptive Silviculture for Climate Change (ASCC) project. ASCC represents a collaborative effort to establish silvicultural trials across a network of forest ecosystems in the U.S. Our site is in the Minneapolis-St. Paul metropolitan area in the floodplain of the Mississippi River. Climate change brings numerous impacts to floodplain forests including altered flooding regimes, patterns of carbon uptake, and species composition. Many issues are exacerbated by an urban setting. We ask: How can we support the urban floodplain forest to adapt to a changing climate and maintain ecosystem services?? We planted 13 species into gaps formed by tree death from emerald ash borer (Agrilus planipennis). Each gap was randomly assigned one of three treatments or a no-action control (24-1/10 acre plots, n=6 per treatment). Adaptation treatments included: resistance planted with current species (6 species) from nurseries in USDA plant hardiness zone 4; resilience increased diversity of species (8 species) from nurseries in zone 5; and transition included future adapted species and seed sources (7 species) from zone 6 nurseries. We collect continuous temperature; weekly phenology; annual growth; and seasonal survival and condition assessments. We highlight early scientific findings. First year survival was generally high (87%) across all treatments; the transition treatment had the lowest survival (68%) with red maple, river birch, and tulip poplar suffering the greater mortality likely due to poor nursery stock quality. In addition to the scientific findings from this study, additional outcomes include a highly engaged volunteer base and public outreach that includes the incorporation of Indigenous art and knowledge.

Caleb McKinney (caleb.mckinney@okstate.edu), Oklahoma State University
Rodney Will (rodney.will@okstate.edu), Oklahoma State University
Ronald Masters (ronald.e.masters@gmail.com), University of Wisconsin-Stevens Point, Stevens Point
Arjun Adhikari (arjun.adhikari@okstate.edu), Oklahoma State University
Omkar Joshi (omkar.joshi@okstate.edu), Oklahoma State University
Bijesh Mishra (bijesh.mishra@okstate.edu), Oklahoma State University
Chris Zou (chris.zou@okstate.edu), Oklahoma State University

Prescribed fire and thinning can be used to produce and maintain woodlands and savannas which provide important wildlife habitat by increasing the productivity of understory vegetation. To understand how forage quality and quantity changes among managed ecosystems ranging from closed-canopy shortleaf pine (Pinus echinata) and post oak (Quercus stellata) forest to savanna, we quantified crude protein concentration of eleven species of understory plants, measured aboveground net primary productivity (ANPP) of six different forage classes (e.g., grass, forb, legume, sedge, woody, cool-season grass), and tracked monthly changes in percent cover for these classes. We collected protein samples at three key times of the year for white-tailed deer (Odocoileus virginianus), early spring when forage quantity is the most limited, mid-summer when deer protein demand is highest, and mid-autumn when forage crude protein is lowest. This research was conducted at the Pushmataha Wildlife Management Area in Pushmataha County, Oklahoma where a series of replicated experimental plots established and maintained since 1984 test the effects of four different intervals of prescribed fire and various tree harvesting and thinning regimes. Our results indicate that crude protein concentration was higher in forested areas with longer fire return intervals, while higher ANPP and percent cover of forage plants occurred in open-canopy savanna and woodland sites. This has management implications for white-tailed deer as nutritional carrying capacity is a function of both forage quantity and quality, and simply focusing on maximum biomass production may come at the cost of lower quality forage.

Benjamin Spei (bspei@uidaho.edu), University of Idaho
Charles Goebel (cgoebel@uidaho.edu), University of Idaho

The future health and persistence of aspen in the western United States has been a subject of debate for several decades. Many have argued that fire suppression and land-use changes have resulted in an unsustainable environment for seral aspen stands that are being invaded by conifer and woody shrub species. More recently, stable aspen stands of the West have begun to decline in many areas as well and many theories suggest raising temperatures and specifically, increasing instances of acute drought brought on by changing climate may be the primary cause of this decline. In this study, we investigate the relationship between moisture limitations and aspen stand stability. We compare stand structure, regeneration, recruitment, and health of nine riparian aspen stands and nine paired upland non-riparian aspen stands to examine if more persistent moisture availability throughout the growing season increases the potential for stand stability in a semi-arid montane region. Our results suggest that riparian aspen stands have a higher variation in aspen stem size and age, and higher aspen regeneration densities relative to adjacent upland stands. While both the riparian and upland plant communities are dominated by aspen, the understory of riparian stands are dominated by a mixture of forbs, graminoids, and woody shrubs, while the upland stands have a lower herbaceous species density and are dominated by different woody shrub species. The compositional and structural complexity of riparian aspen stands may also provide more resistance to future environmental stressors resulting from drier and hotter conditions predicted for much of the interior West. Furthermore, the higher densities of aspen seedlings within riparian areas provide evidence of a higher likelihood of stand stability (i.e., not dependent on disturbance for persistence). Consequently, we suggest riparian areas could provide refugia for aspen in areas where increasing temperature and drought are expected.

Maurane Bourgouin (maurane.bourgouin@gmail.com), IRF - Université du Québec en Abitibi-Témiscamingue (UQAT)
Nicole Fenton (nicole.fenton@uqat.ca), IRF - Université du Québec en Abitibi-Témiscamingue (UQAT)
Osvaldo Valeria (osvaldo.valeria@uqat.ca), IRF - Université du Québec en Abitibi-Témiscamingue (UQAT)

Carefully determining trade-offs between nature conservation and forest management is crucial to maintain ecological services and processes in the context of forest management. Several tools, like airborne LiDAR point clouds, are useful in describing environmental characteristics of landscapes that in turn help us better understand the distribution of diversity and compositional variation in managed landscapes. To evaluate the impacts of forest management at the landscape scale on biodiversity, we used bryophytes as indicators as they respond to changes in stand age and area, light and humidity in forest stands, and substrate diversity, quality and quantity. We documented bryophyte diversity and compositional changes at the stand and at the landscape level along a forest management gradient in mature and old growth forests. We sampled stands in the managed Black Brook district and the unmanaged landscape of Mont Carleton Provincial Park for control in New-Brunswick. Preliminary results show an important natural and anthropogenic segregation of communities in the managed landscape due to both natural stand distribution, affected by soil type and topography, and to homogenization of stand distribution and tree composition due to management. Bryophyte composition in the unmanaged landscape (from Mont-Carleton) were similar than composition found in the managed landscape (Black Brook), but richness is higher (except when compared to the cedar stand). This reflects the higher number of rare and unique species i.e.: species found only in control landscape. Overall, connectivity between mesic stands (Cedar, Spruce-Fir and Riparian zones) remains high because of the distribution of those stands along water courses. There is no effect of landscape fragmentation and homogenization on overall bryophyte diversity because mean stand area is over the critical limit to compensate for the edge effect and because of the mitigating effect of humidity in mesic stand. Landscape fragmentation and homogenization has an influence on rare species occurrences.

Keenan J. Rivers (kriver10@syr.edu), SUNY College of Environmental Science and Forestry
John E. Drake (jedrake@esf.edu), SUNY College of Environmental Science and Forestry
Stacy A. McNulty (smcnulty@esf.edu), SUNY College of Environmental Science and Forestry
Julia I. Burton (jiburton@mtu.edu), Michigan Technological University

Beech bark disease (BBD) has ongoing impacts on forests in the northeastern United States and Canada. Stress and mortality of overstory American beech (Fagus americana) trees due to BBD stimulates the development of understory thickets of beech seedlings and saplings in aftermath forests. Pre-disease conditions, variability in susceptibility, and local climate can produce a wide variety of outcomes in aftermath forests with specific impacts that are largely unmeasured. Understanding how thicket structure and associated effects on the ground-layer varies within and among stands is critical to managing forests for both sustainable timber production and biodiversity. Using canopy and ground-layer inventory from 560 fixed plots between two forests and a combination of spatial statistics, cluster analysis, and ordination; we tested the hypothesis that patterns of aftermath beech thicket structure and effects on ground-layer plant communities vary between northern hardwood stands with high (Adirondacks) and low (Allegheny Plateau) relative abundances of American beech. Spatial patterns of ground-layer plants were patchier and autocorrelated at closer ranges in the Adirondacks where beech density was high than on the Allegheny Plateau (A difference of 35 meters). Ground-layer community composition varied with structural changes in beech thickets. Beech thicket effects were strongest among understory forbs and graminoids at both sites, with decreases in total cover of those species associated with increase beech density. Cover of trees and shrubs were positively associated with understory beech. Positive associations between beech thickets and other regenerating tree species suggest management of understory beech may disrupt regeneration of desirable tree species. These results can provide further understanding and scientific basis for developing specific targeted management techniques in these systems.

Erik J.S. Emilson (erik.emilson@nrcan-rncan.gc.ca), Canadian Forest Service - Natural Resources Canada
Emily Smenderovac (emily.smenderovac@nrcan-rncan.gc.ca), Great Lakes Forestry Centre - Canadian Forest Service - Natural Resources Canada
Maitane Erdozain (maitane.erdozain@gmail.com), University of New Brunswick
Michelle Gray (mgray@unb.ca), University of New Brunswick
Karen Kidd (karenkidd@mcmaster.ca), McMaster University
Dave Kreutzweiser (davek.636@gmail.com), Canadian Forest Service - Natural Resources Canada

Headwater and mid-reach streams play a disproportionately large role in the cycling of forest carbon, nutrient, and sediment runoff within the aquatic network. Despite widely-adopted management practices designed to ensure minimal impact, forest harvest practices still leave measurable influence on the structure and function of these important ecosystems. There is a need to further refine our management practices, but the considerable variation in the response of streams to these practices makes it difficult to prescribe refinements. A considerable challenge in the identification of commonalities in stream ecosystem responses to forest change is the varied nature of the management practices themselves. For example, in Canada alone, there is a wide range in the application of post-harvest silvicultural approaches designed to accelerate the recovery of forest biomass, and the role of these practices in either cumulating or mitigating the effects of forest harvest on aquatic ecosystems is not well understood. Here we make use of 18 watersheds spanning 3 regions of temporally and spatially variable management practices in New Brunswick, Canada, to explore the degree to which harvest and post-harvest silvicultural practices affect stream water quality and dissolved organic matter, with focus on impacts to stream microbial communities as indicators of ecosystem structure and function. We find that post-harvest planting and pre-commercial thinning both act to further cumulate the effects of clear cut harvest on water quality in stream ecosystems, but mitigate impacts on dissolved organic matter. Further, we find that the influence of these post-harvest silvicultural practices in particular are highly spatially and temporally dependent, with effects on dissolved organic matter greatest when near the stream or flowpaths. We also demonstrate that historic management context must be considered when attempting to identify relationships between forest change and stream ecosystems.

Christian Wehenkel (wehenkel@ujed.mx), Instituto de Silvicultura e Industria de la Madera - Universidad Juárez del Estado de Durango
José Ciro Hernández-Díaz (jciroh@ujed.mx), Universidad Juárez del Estado de Durango, Instituto de Silvicultura e Industria de la Madera
Javier Hernández-Velasco (javier.hernandez@ujed.mx), Universidad Juárez del Estado de Durango, Programa Institucional de Doctorado en Ciencias Agropecuarias y Forestales
Sergio Leonel Simental-Rodríguez (sergio.simental@ujed.mx), Universidad Juárez del Estado de Durango, Programa Institucional de Doctorado en Ciencias Agropecuarias y Forestales
Ilga Porth (ilga.porth@sbf.ulaval.ca), Université Laval. Institute for System and Integrated Biology (IBIS)
Roos Goessen (roosje.goessen.1@ulaval.ca), Université Laval. Institute for System and Integrated Biology (IBIS)
M. Socorro González-Elizondo (herbario_ciidir@yahoo.com.mx), Instituto Politécnico Nacional, CIIDIR Unidad Durango
Matthias Fladung (matthias.fladung@thuenen.de), Thünen-Institute of Forest Genetics
Katrin Groppe (katrin.groppe@thuenen.de), Thünen-Institute of Forest Genetics
Juan P. Jaramillo-Correa (jaramillo@ecologia.unam.mx), Universidad Nacional Autónoma de México, Instituto de Ecología
Jesús Miguel Olivas-García (jolivas@live.com.mx), Universidad Autónoma de Chihuahua, Facultad de Ciencias Agrícolas y Forestales
David S. Gernandt (dgernandt@ib.unam.mx), Universidad Nacional Autónoma de México, Departamento de Botánica, Instituto de Biología
José Guadalupe Martínez-Ávalos (jmartin@uat.edu.mx), Universidad Autónoma de Tamaulipas, Instituto de Ecología Aplicada
Artemio Carrillo-Parra (tecnologia.madera.fcf@gmail.com), Universidad Juárez del Estado de Durango, Instituto de Silvicultura e Industria de la Madera
Carlos Antonio Lopez-Sanchez (lopezscarlos@uniovi.es), University of Oviedo, Department of Biology of Organisms and Systems, Mieres Polytechnic School
Eduardo Mendoza-Maya (eduardo.mendoza@ujed.mx), Universidad Juárez del Estado de Durango, Programa Institucional de Doctorado en Ciencias Agropecuarias y Forestales
Cuauhtémoc Sáenz-Romero (csaenzromero@gmail.com), Universidad Michoacana de San Nicolás de Hidalgo, Instituto de Investigaciones sobre los Recursos Naturales
Arnulfo Blanco-García (arnulfoblanco@yahoo.com.mx), Universidad Michoacana de San Nicolás de Hidalgo, Facultad de Biología

The genetic structure of Mexican populations of Populus tremuloides is unknown. A study of this species along its total spatial range is important for disentangle its genetic signatures of adaptation to a variety of environments. This study was aimed at analyzing the genetic structure of 95 populations of P. tremuloides across its entire distribution in Mexico, using filtered SNPs. Methods: After sequencing, 1.5 Mill. unfiltered SNPs were detected. After filtering with MAC = 2, MAF = 0.025, 0.05 and 0.2 and MAS = 2 and max-missing 0.85 and 20% missing data using the VCFtools and R program, we found 828 - 36,810 filtered SNPs. The genetic structure was explored using observed heterozygosity (Ho), expected heterozygosity (He), and inbreeding coefficient (FIS). Results: The results unexpectedly show that the genetic diversity expressed by anticipated heterozygosity is much smaller than that of the US and Canadian populations. The inbreeding coefficient of populations was approximately between 0 and -1. Conclusions: The occurrence of partially asexual propagation in small populations, negatively affecting both the values of He and FIS (caused by heterozygote excess), can well explain the indirect positive relationship between He and FIS. However, negative assortative mating and progressive selection against homozygotes over the life cycle, may also create such unexpected and unique genetic relationships.

Barry Cooke (barryjamescooke1967@gmail.com), Natural Resources Canada
Brian R. Sturtevant (brian.r.sturtevant@usda.gov), Institute for Applied Ecosystem Studies, Northern Research Station, USDA Forest Service
Louis-Etienne Robert (robert.louisetienne@gmail.com), NRCan
Dan Kneeshaw (kneeshaw.daniel@uqam.ca), CEF - Université du Québec à Montréal (UQAM)
Bina Thapa (btha001@iastate.edu), Iowa State University

Both native and invasive defoliators can cause extensive damage in boreal and temperate forests of the world. As such, considerable effort has been invested to understand their population dynamics, in particular the role of forest species composition and landscape structure in shaping the intensity, duration, and frequency of periodic outbreaks. We report on the landscape-scale effect of forest configuration and composition on the intensity of outbreaks of the spruce budworm and forest tent caterpillar in a Laurentian mixedwood of northern Minnesota (USA) and adjacent Ontario (Canada), and how this is related to the degree of spatial synchrony in outbreak cycling. We find that real-world defoliator outbreak dynamics do not conform to behavior consistent with simple harmonic oscillations synchronized by spatially autocorrelated random perturbations. Nonetheless, we observed convergence in the response patterns of temporal and spatial complexity across insect systems. Specifically, synchrony varies temporally, amongst outbreak cycles, and in direct proportion to the cycle peak intensity. Cycle peak intensities are distributed bimodally in time for both systems. Spatially, the area where each pest species currently cycles with the greatest peak intensity and synchrony is where their preferred host trees are currently found in greatest proportion. Despite the overall synchrony, we found a persistent, highly robust negative spatial correlation amongst successive pulses and cycles of defoliation. The same response was observed in both defoliator systems. This implies a slow, persistent process continually modulating cycle peak intensity, possibly even the same regulating process in both systems. Our research demonstrates that outbreaks are less synchronous and of reduced intensity as the proportion of host decreases. From a management perspective, mixedwoods appear to be less prone to intense, synchronized defoliator attack than forests of pure hardwood or pure conifer.

Philippe Nolet (philippe.nolet@uqo.ca), CEF - ISFORT - Université du Québec en Outaouais (UQO)
Pascal Rochon (pascal.p.rochon@gmail.com), CEF - ISFORT - Université du Québec en Outaouais (UQO)
Rebeca Cordero Montoya (rebeca.corderomontoya@isfort.ca), CEF - ISFORT - Université du Québec en Outaouais (UQO)

Expectations towards silviculturists in North America keep increasing as they are nowadays asked to consider climate change, biodiversity protection and public expectations, among others, in their silvicultural prescriptions. However, the tools available to silviculturists to describe forest stands has not followed the paste of these expectations. In the last decade, the use of terrestrial LiDAR scanners (mobile or not) has greatly increased in research to describe trees and forest stands, but the development of concrete tools for silviculturists remains slow. First, we briefly explain the greater potential of the mobile terrestrial LiDAR (MTL) over the static terrestrial LiDAR to describe forest stands. Second, we present a new approach to describe forest stand attributes from three-dimensional (3D) MTL point clouds; this approach is based on a detailed visual inspection of 3D point clouds to describe specific attributes of interest (e.g., trees, understory, woody debris). In line with this approach, we developed an open-access tool (under Python) that allows, all at the same time, to navigate into a forest stand 3D point cloud, choose a specific tree in the stand and select a transversal section of the tree at 1.3 m to estimate its DBH. We used the tool to analyse 42 forest stands; only 5% of the trees were unidentified, there was no false detection, and we obtained a respectable DBH estimation (R2= 0.81 when compared to field measures). We argue that a detailed visual inspection of 3D MTL point clouds is necessary before implementing automatic algorithms to describe forest attributes. Without such inspection, automatic algorithms will fail to provide robust estimations in varied ecosystems and will remain useless for silviculturists. We plan to add visual capabilities to our tool allowing detection of more forest attributes (e.g., dead trees) and to develop automatic algorithms in phase with the visual detection process.

Lauren Egli (egli.lauren@courrier.uqam.ca), CEF - Université du Québec à Montréal (UQAM)
Timothy T. Work (work.timothy@uqam.ca), CEF - Université du Québec à Montréal (UQAM)

In boreal mixedwood forests, management aimed at emulating natural disturbance dynamics have been proposed in the hope that they will increase structural and compositional heterogeneity as well as provide refuges for sensitive species which might otherwise be lost. We evaluated recovery and persistence of ground beetle biodiversity over 20 years following a diverse range of natural disturbance based harvesting strategies conducted as part of the SAFE (Sylviculture et aménagement forestier écosystémique) experiment in northwestern Québec. Sampling occurred in three forest ecosystems representing typical post-fire succession in this region (hardwood, mixedwood and softwood dominated). Experimental harvest treatments included increasing intensities of partial retention harvest and clear-cutting. In clear-cut stands, we also compared treatments where logging residues were further treated through prescribed burning, whole-tree harvest or left in situ. We analyzed catch rates of ground beetles (71,021 individuals from 74 species) collected in pitfall traps approximately 5, 10, 15 and 20 years post-harvest. We analyzed interactions between harvest treatments and forest type on both changes in community composition and individual species responses. For the first 10 years post-harvest, we observed significant changes in species composition related to clear-cutting in all forest ecosystems as well as partial retention harvesting in mixedwood stands. In contrast, recovery of biodiversity occurred within the initial 10 years following partial retention harvesting in hardwood stands. By 15 years post-harvest, composition of ground beetles recovered in softwood and hardwood clear-cuts and partial retention harvests, with the exception of those collected in prescribed burning or whole-tree harvests. By 20 years post-harvest all hardwood and softwood stands had recovered. Recovery had yet to occur in partial or clear-cut mixedwood stands. Therefore, maintaining greater retentions appears to be a more effective strategy to conserve biodiversity as compared to clear-cutting. Additionally, intensive management options which remove logging residues slows recovery of biodiversity.

Zaira Rosario Pérez Vazquez (zairpv@gmail.com), Posgrado en Ciencias Forestales. Colegio de Postgraduados
Gregorio Ángeles Pérez (gangeles@colpos.mx), Posgrado en Ciencias Forestales. Colegio de Postgraduados
Bruno Chávez Vergara (chavezvb@geologia.unam.mx), Instituto de Geología. Universidad Nacional Autónoma de México
Martha Elva Ramírez Guzmán (martharg@colpos.mx), Postgrado en Estadística. Colegio de Postgraduados
José Rene Váldez Lazalde (valdez@colpos.mx), Posgrado en Ciencias Forestales. Colegio de Postgraduados
Valentín Reyes Hernández (vreyes@colpos.mx), Colegio de Postgraduados

Vegetation and topographic characteristics are key factors that affect the spatial distribution of forest floor nutrients; however, their relationships in temperate managed forests remain to be elucidated. We used a Random Forest (RF) modelling approach to estimate the forest floor carbon and nitrogen stocks at the landscape scale as well as to spatially assess the C:N stoichiometry. The forest floor was evaluated into two layers (litter and fermentation layer) and was compared between 2013 and 2018. We used the information of ten predictor variables obtained for both years. We determined the variable importance, the model uncertainty and the model performance. The forest floor carbon (2013: 12.19 Mg ha-1; 2018: 5.76 Mg ha-1) and nitrogen (2013: 0.23 Mg ha-1; 2018: 0.14 Mg ha-1) stocks increased as a function of the layer decomposition stage. The C:N ratio estimates suggest an increase in decomposition rates between both years that caused a decrease in the C and N stocks in 2018. All evaluated variables showed a high spatial dependence (~ 30 m). Our results demonstrated that spatiotemporal variability of both nutrients is directly influenced by variables associated with forest management (stand age, basal area and tree cover). In contrast, the C:N ratio is affected by topographical variables (slope and altitude). Random Forest showed a high performance in predicting the spatial distribution of carbon (R2 > 0.65) and nitrogen stocks (R2 > 0.81), but the best modeling performance was obtained for the C:N ratio (R2 > 0.79). The forest floor potentially links environmental factors and forest management, and it serves as a critical component for soil C cycling and forest productivity. The storage potential and spatial distribution of carbon and nitrogen depends on the interactions between the stoichiometry of the organic material and the changes induced by silvicultural practices (harvesting, thinning, residue management).

Teodora Stoycheva (tstoyche@depaul.edu), DePaul University
Beth Lawrence (beth.lawrence@uconn.edu), University of Connecticut
Abigail C. Leeper (abigailleeper@gmail.com), DePaul University
Kyle J. Pearson (pearsonkj@ornl.gov), Oak Ridge National Lab
Jana R. Phillips (randolphjd1@ornl.gov), Oak Ridge National Lab
Paul J. Hanson (hansonpj@ornl.gov), Oak Ridge National Lab
Jalene LaMontagne (jlamont1@depaul.edu), DePaul University

The boreal forest is a region highly susceptible to climate change, and the impacts of climate change on tree reproduction may have strong consequences for future forests. While warming temperatures and elevated carbon dioxide (eCO2) independently alter tree reproduction, how these factors will interactively affect tree reproduction is unknown. Our objective is to test the impacts of the combined effects of elevated temperature and eCO2 on cone and seed characteristic of black spruce, a widespread boreal forest species. Our research was conducted at the Spruce and Peatland Response Under Changing Environments (SPRUCE) experiment, which combines five warming treatments (+0, +2.25, +4.5, +6.75, and +9°C) with ambient and eCO2 (~400 and ~900 ppm. respectively) in 10 open-top chambers (12m wide, 8m high). Cone characteristics (e.g., cone size, seed number, cone and seed mass) were quantified under all ten climate scenarios. We found nonlinear relationships and a temperature-CO2 treatment interaction as cone characteristics varied across treatments. For instance, cone size and seed number increased with increased warming until what appears to be an optimum at +4.5°C, then decline at +6.75°C only to increase again at +9°C. In the +9°C/eCO2 treatment, while fewer cones were produced than in other treatments, cones were larger and contained more seeds. There are also treatment effects on mean seed mass, with potential differences in germination success. Principal Components Analysis on cone morphology shows that PC1 was defined primarily by whole cone characteristics (dry cone mass, cone length cone with, total dry seed mass) accounting for 67% of the variation, while PC2 was related to seed number, cone scale number, and scale length, accounting for 12% of the variation. Our experimental findings show black spruce reproduction is sensitive to climate change through temperature-CO2 interactions.

Rob Fleming (rob.fleming@nrcan-rncan.gc.ca), Canadian Forest Service - Natural Resources Canada
Debbie Mossa (dmossa@bell.ca), Canadian Forest Service - Natural Resources Canada
Paul Hazlett (paul.hazlett@nrcan-rncan.gc.ca), Canadian Forest Service - Natural Resources Canada
Kara Webster (kara.webster@nrcan-rncan.gc.ca), Canadian Forest Service - Natural Resources Canada
Jason Leach (jason.leach@nrcan-rncan.gc.ca), Canadian Forest Service - Natural Resources Canada
Ken Baldwin (quercuskb@gmail.com), Canadian Forest Service - Natural Resources Canada

We examined decadal effects of harvest intensity, soil disturbance and aspect on seasonal microclimates and related trends in stand development, soil solution chemistry, soil respiration and N mineralization at the Turkey Lakes Watershed. We monitored microclimatic conditions and vegetation dynamics at 96 locations across combinations of harvest intensity/canopy opening, soil disturbance and aspect in this northern tolerant hardwood ecosystem. Root zone soil solutions were sampled at biweekly to monthly intervals using porous cup lysimeters, and analyzed for NO3, total N, Ca, Organic C, and total C. Concomitantly, soil respiration and nitrogen mineralization were determined at various locations within and adjacent to the harvest area. Annual patterns reflected four distinct periods: 1) snow cover (roughly December ?mid March); 2) snow melt (late March ? mid April); 3) leafless transition (pre-emergence (late April - May) and post senescence (October ? November)); and full canopy (June ? September). Snow-melt occurred earlier and the snow free period lasted longer on south than on north facing aspects and sometimes in clearcut than closed forest. Soil temperatures remained near 0°C across treatments during winter and snowmelt, were greater on south than north aspects during leafless transition, and in clearcut but not partially cut or uncut forests during full canopy. Soil disturbance increased spring and summer temperatures but often reduced fall transition values. Substantial reductions in soil moisture only occurred occasionally ? in dry years during the full canopy period, particularly under partial and full canopies. Soil respiration responded strongly to soil temperature but was reduced by organic layer removal. Compared to uncut forest, soil solution concentrations and N mineralization were increased substantively by clearcut but not partial harvest. There was some convergence in harvest effects on microclimate, soil respiration and soil solution chemistry with stand development, but treatment impacts remained evident over the first decade.

Lyndsay Cartwright (lyndsay.cartwright@trca.ca), Toronto and Region Conservation Authority
Sue Hayes (sue.hayes@trca.ca), Toronto and Region Conservation Authority
Brian Ford (brian.ford@trca.ca), Toronto and Region Conservation Authority
Rivka Shachak (rivka.shachak@trca.ca), Toronto and Region Conservation Authority
Paul Prior (paul.prior@trca.ca), Toronto and Region Conservation Authority
Dell Tune (dell.tune@trca.ca), Toronto and Region Conservation Authority
Gavin Miller (gavin.miller@trca.ca), Toronto and Region Conservation Authority
Natasha Gonsalves (natasha.gonsalves@trca.ca), Toronto and Region Conservation Authority

Toronto and Region Conservation Authority?s Regional Watershed Monitoring Program was developed to track changes in the health of ecosystems and biodiversity across the region. Forest vegetation and birds were monitored between 2011 and 2020 using standardized methods endorsed by the Ecological Monitoring and Assessment Network and the Ontario Forest Bird Monitoring Program. Both forest vegetation and forest bird communities responded to regional disturbances affecting forest ecosystems between 2011 and 2020 including both the December 2013 ice storm and the widespread destruction by Emerald Ash Borer (Agrilus planipennis; EAB). These large-scale disturbances led to changes in tree community composition, increased tree mortality, snag production, decreased crown vigour, increased regeneration of woody species, and an increased production of ash seedlings. The impacts of EAB on forest ecosystems also indirectly affected forest bird communities. There was a significant increase in the total number of bark foragers across all monitoring stations likely reflecting the increased abundance of EAB as a food source. Overall, these large-scale disturbance events elicited strong changes in forest ecosystems affecting forest structure, species composition, and had wider impacts on forest food webs. Given the predicted impacts of climate change with increased intensity of storms and spread of future invasive pests and disease, these results provide insight into how these disturbances may impact forest ecosystems in the future.

Clément Hardy (clem.hardy@pm.me), Department of Biological Sciences, Centre d'Étude de la Forêt (CEF), Université du Québec à Montréal, Canada (UQAM)
Christian Messier (christian.messier@uqo.ca), Department of Biological Sciences, Centre d'Étude de la Forêt (CEF), Université du Québec à Montréal, Canada (UQAM), Department of Natural Sciences, Institut des Sciences de la forêt tempérée (ISFORT), Université du Québec en Outaouais (UQO)
Yan Boulanger (yan.boulanger@canada.ca), Laurentian Forestry Centre - Canada Forest Service - Natural Resources Canada
Dominic Cyr (cyr.dominic@gmail.com), Sciences et Technology Branch, Environment and Climate Change Canada, Gatineau, QC, Canada
Élise Filotas (elise.filotas@teluq.ca), Department of Science and Technology, Université du Québec (TELUQ), Canada

Uneven-aged management is currently seen by many forest ecologists as an extensive management approach when compared to more traditional even-aged methods, offering interesting compromises between timber production and other important ecosystem services. But uncertainties remain concerning its impacts on longer time periods and broader spatial scales, where harvesting activities and forest roads construction can impact the composition and fragmentation of the landscape. Consequently, we explored the impacts of uneven-aged management at the landscape scale and on a planning horizon of 150 years by using the forest landscape model LANDIS-II, along with an extension allowing for the dynamic simulation of the forest road network. We simulated a landscape containing boreal forest in the Mauricie Region of Québec with 30 different management scenarios where we varied the use of uneven-aged management methods, the level of aggregation of the harvested areas, and the presence of pre-existing forest roads. Our results show that when compared with even-aged management, uneven-aged management increased both the quantity of forest roads and their operational costs, the fragmentation per se of the older forests of the landscape, and the quantity of forest with older tree cohorts. In addition, differences of fragmentation of the landscape between even-aged and uneven-aged management were lower in the northern region containing more boreal forest, as forest fires tended to fragment the old forests of the landscape in spite of any forest management. We conclude that selecting uneven-aged over even-aged management should be closely linked to how fragmentation and habitat are defined, to the patterns of fragmentation as a result of natural disturbances, and to the perceived effects of fragmentation per se in the landscape. We also conclude that aggregation of the harvested areas could help to reduce the negative impacts of uneven-aged management, but that they are unlikely to entirely compensate them.

Dave M. Morris (dave.m.morris@ontario.ca), Ontario Ministry of Northern Development, Mines, Natural Resources and Forestry
Lisa Venier (lisa.venier@nrcan-rncan.gc.ca), Great Lakes Forestry Centre - Canadian Forest Service - Natural Resources Canada
Martin Kwiaton (martin.kwiaton@ontario.ca), MNDMNRF-Centre for Northern Forest Ecosystem Research

Current forest management across the boreal forest often operates within the context of ecosystem management and the emulation of natural disturbance (i.e., large-scale, stand-replacing wildfires). Although spatial patterns may be comparable between natural versus anthropogenic disturbances, little work has been done to confirm that important belowground ecological patterns and processes are not being adversely affected. The objective of the current study was to compare post-disturbance temporal patterns in soil carbon and nutrient stocks as a function of disturbance type (i.e., wildfire, harvest, salvage) and stand development stage (regeneration to crown closure to self-thinning to mature forests). Using a chronosequence approach, a total of 84 sites were sampled between 2000 to 2017, with all study sites representing well-drained, outwash sands, with well-developed Orthic Humo-Ferric Podzolic profiles that support jack pine-dominated stands. We documented immediate declines in soil C, N, and K stocks following stand-replacing wildfire. However, recovery began soon after disturbance returning to pre-disturbance levels during the self-thinning stage. In comparison, soil pool declines were not observed following clearcut harvesting, presumably the result of retaining the forest floor and existing DWD. In contrast to wildfire or harvest, salvage logging resulted in substantial declines soil pools, with no evidence of recovery out to 20 years. From an SFM perspective, there is no evidence that clearcut harvesting results in any long-term declines in soil carbon or nutrient stocks, particularly when best management practices are employed to minimize soil disturbance in combination with green tree retention rule sets. Although post-wildfire salvage logging occurs on a relatively small amount of area across the managed forest area of Ontario, results would suggest a need for longer-term monitoring of this operational practice to better describe the full extent of post-salvage recovery patterns to ensure that soil carbon and nutrient stocks eventually recover to pre-disturbance levels.

Angeline Van Dongen (angeline.vandongen@nrcan-rncan.gc.ca), Natural Resources Canada
Caren Jones (caren.jones@nrcan-rncan.gc.ca), Natural Resources Canada
Amanda Lynn Schoonmaker (aschoonmaker@nait.ca), Northern Alberta Institute of Technology
Jill Harvey (jharvey@tru.ca), Natural Resources Canada
Dani Degenhardt (dani.degenhardt@nrcan-rncan.gc.ca), Natural Resources Canada

Alberta's forests are becoming increasingly disturbed and fragmented by the cumulative effects of anthropogenic disturbances exacerbated by the enduring footprint of conventional seismic lines on the landscape. Tree regeneration on seismic lines is generally considered to be a slow and inconsistent process leading to the persistence of these linear features which is an environmental and ecological concern. Forest harvesting and subsequent reforestation activities (e.g., site preparation, and tree planting) may facilitate tree growth on seismic lines when incorporating them into management areas, effectively erasing them from the landscape; however this hypothesis has not yet been investigated. In this study, forest regeneration was assessed along transects on and off seismic lines within four cutblocks in Northwestern Alberta. We measured tree, sapling, and shrub characteristics and collected tree cookies from a subset of Pinus contorta and Populus tremuloides to model height as a function of age on and off seismic lines. We found no difference between total tree, sapling, or shrub counts on and off seismic lines; however, growth curves showed that Pinus contorta and Populus tremuloides trees on seismic lines were growing at slightly slower rates (2 to 7 cm year per year) compared to the adjacent off-line areas within the cutblocks. Alnus viridis was taller and more abundant on seismic lines compared to the off-line areas. Higher numbers of Alnus viridis were also positively correlated with higher numbers of conifer saplings on seismic lines. Our results suggest that, despite some species-level differences, seismic lines on cutblocks in upland mixedwood boreal forests are regenerating similarly to the adjacent cutblock forest. These findings indicate that forest harvesting and reforestation could represent an important tool in conducting landscape-level restoration in areas where seismic lines have not naturally recovered.

Hiromitsu Sato (hiromitsu.sato@mail.utoronto.ca), Ontario Forest Research Institute - Ontario Ministry of Mining, Northern Development, Natural Resources, and Forestry
Stephen Mayor (stephen.mayor@ontario.ca), Ontario Ministry of Northern Development, Mines, Natural Resources, and Forestry
Emeline Chaste (emeline.chaste@gmail.com), AgroParisTech
Martin Girardin (martin.girardin@nrcan-rncan.gc.ca), Canadian Forest Service - Natural Resources Canada
Jean-Noel Candau (jean-noel.candau@nrcan-rncan.gc.ca), Canadian Forest Service - Natural Resources Canada
Jed Kaplan (jkaplan@hku.hk), University of Hong Kong

Eastern Spruce Budworm (ESBW) is a primary disturbance agent in the boreal forests of Eastern Canada. Cyclical outbreaks tend to occur roughly every 30 years, and lead to widespread defoliation and mortality of its preferred host trees, balsam fir and spruce species, which in turn can promote wildfire. Despite the ecological and economic impacts of defoliators such as ESBW, there has been little effort in building representation in important process-based Earth System models. Dynamic Global Vegetation Models (DGVMs), which simulate the large-scale spatiotemporal dynamics of vegetation, are central tools in estimating the impacts of climate change on terrestrial ecosystems.We present integration of an ESBW defoliation module within a DGVM, LPJ-LMfire, which simulates large-scale forest dynamics and biogeochemistry. Spatiotemporal patterns and interactions with fire were tested in simulations driven by climate data from 1959 to 2012 over Eastern Canada. We approached initial colonization through a bottom-up control, using host foliage density to trigger outbreak. The sensitivity of spatial distribution of ESBW outbreak was tested against a foliage density threshold parameter and compared to annual aerial survey data. Return intervals were controlled by the regrowth of fir and were found to be generally larger than observed values. A factorial experiment was performed to investigate the interactions of ESBW with wildfire, which was found to be enhanced after outbreaks up to 20 percent relative to control, due to increased fuel loads. Interactions between ESBW and fire were found to have a higher interaction strength in the drier Western region of the boreal forest. We suggest that biotic interactions, particularly of broad scale ecosystem engineers, should be better represented in DGVMs in order to elucidate the mechanisms and consequences of climate change effects on vegetation distributions and carbon dynamics.

Edward John Primka IV (eprimka@okstate.edu), Oklahoma State University
Thomas Adams (tsa3@psu.edu), The Pennsylvania State University
Alexandra Buck (lexie.orr@gmail.com), The Pennsylvania State University
David M. Eissenstat (dme9@psu.edu), The Pennsylvania State University

Many North American forests grow in regions with complex topography. Complex topography, or hills and valleys, generate unique environmental gradients that may impact fine root dynamics and consequently forest carbon dynamics. Despite this, little is understood about how belowground dynamics may or may not change along hillslopes, a feature common in complex topography. Hillslopes are known to influence water flow, nutrient storage, and sediment transfer in forested regions. Some hillslope regions within the midslope area tend to have concave regions, called swales, that tend to store more water and nutrients than the surrounding midslope regions. Swales and valley floor regions tend to be wetter, while midslope planar and ridgetop regions tend to be drier. Based on previous short-term studies of root behavior under conditions of either excessive or dearth of water on fine root dynamics, we hypothesized that soil water content would have a quadratic impact on fine root dynamics (fine root production, mortality, standing crop, and turnover). Moving from the driest region, ridgetop, to the wettest, valley floor, we predicted increased mortality and turnover at the two ends of the soil water continuum (valley floor and ridgetop regions) and decreased mortality and turnover in the center of the soil water continuum (midslope planar and swale regions). We expected the converse for fine root production and standing crop. To test these hypotheses, we collected and analyzed observations from 150 minirhizotron tubes within 50 macroplot sites established across the various topographic regions within a mixed mesic, temperate forest in central Pennsylvania. Fine root tips showed a wet-dry split in root turnover. Additionally, fine root standing crop length was higher in hillslope regions with wetter conditions (swales and valley floor). In combination, these two findings suggest differing strategies of fine roots established in wet versus dry regions across a landscape.

Angelo T. Filicetti (filicett@ualberta.ca), University of Alberta
Jesse D. Tigner (jesse@swampdonkeysolutions.ca), SwampDonkey
Scott E. Nielsen (scottn@ualberta.ca), University of Alberta

Linear disturbances have fragmented habitats worldwide and function as corridors and habitats for species resulting in winners and losers. Although their footprint may be small, their effects on biodiversity can be substantial. For example, linear disturbances in western Canada are detrimental for threatened woodland caribou (Rangifer tarandus caribou). Many linear disturbances were intended as temporary features, but persist decades past their expected lifespan. Persistence of linear disturbances in early seral vegetation is not only due to continual human use, but owing to the ecological sensitivity of certain landscapes and the manner in which these lines were created. Historically, lines were created with bulldozers scraping away vegetation and substrate to create flat surfaces for travel by other machinery. In recent decades, line creation intended for short-term and/or low impact projects have involved smaller and lighter machinery that rely on mulching. Here, we tested whether these newer 'low impact' linear disturbances improve tree regeneration and forest growth. Specifically, we examine the occurrence, density, and height of trees on linear disturbances (seismic lines 2 - 4.5 m wide) in treed peatlands of northeast British Columbia. Overall, low impact seismic lines had greater tree occurrence, density, and heights than historic seismic lines with comparable site characteristics. Three main factors influence the benefits of low impact seismic lines: (1) mulcher height (elevation of cutting drum), (2) distribution of mulch cover, and (3) shrub density. Specifically, tree occurrence was positively related to mulcher height, but negatively related to mulch cover, and shrub density. Tree density was also positively associated with mulcher height and negatively related to shrub density, while tree height increased with mulch cover. Low impact seismic lines demonstrated faster regeneration to a forested state. Further improvements may be possible by increasing mulcher heights, better use of mulch cover, and reducing shrub densities.

Michael J Mahoney (mjmahone@esf.edu), SUNY College of Environmental Science and Forestry
Lucas K Johnson (ljohns11@esf.edu), SUNY College of Environmental Science and Forestry
Eddie Bevilacqua (ebevilacqua@esf.edu), SUNY College of Environmental Science and Forestry
Colin M Beier (cbeier@esf.edu), SUNY College of Environmental Science and Forestry

Airborne LiDAR has become an essential data source for large-scale, high-resolution modeling of forest biomass and carbon stocks, enabling predictions with much higher resolution and accuracy than can be achieved using optical imagery alone. Ground noise filtering -- that is, excluding returns from LiDAR point clouds based on simple height thresholds -- is a common practice meant to improve the "signal" content of LiDAR returns by preventing ground returns from masking useful information about tree size and condition contained within canopy returns. Although this procedure originated in LiDAR-based estimation of mean tree and canopy height, ground noise filtering has remained prevalent in LiDAR pre-processing, even as modelers have shifted focus to forest aboveground biomass (AGB) and related characteristics for which ground returns may actually contain useful information about stand density and openness. In particular, ground returns may be helpful for making accurate biomass predictions in heterogeneous landscapes that include a patchy mosaic of vegetation heights and land cover types. In this paper, we applied several ground noise filtering thresholds in making LIDAR-derived AGB predictions across 19 study areas ranging from 196 to 10,345 km2 in area and collectively covering over 100,000 km2 of New York State. We observed that removing ground noise via any height threshold systematically biased many of the LiDAR-derived variables used in AGB modeling. By fitting random forest models to each of these predictor sets, we found that ground noise filtering yielded models of forest AGB with lower accuracy than models trained using predictors derived from unfiltered point clouds. Loss of model accuracy was greater in mixed-use and highly fragmented study areas. Our results suggest that ground filtering of LIDAR returns should be avoided when mapping biomass, especially in heterogeneous landscapes, where ground returns may represent useful "signal" as opposed to extraneous "noise".

Morgane Henry (morgane.henry2@mail.mcgill.ca), McGill University
Patrick M.A. James (patrick.james@utoronto.ca), University of Toronto
Brian Leung (brian.leung2@mcgill.ca), McGill University

The spruce budworm (Choristoneura fumiferana) is among the most destructive forest disturbance in Eastern Canada. Its periodic outbreaks cover several million hectares and cause extensive damage to economically important tree species, such as balsam fir (Abies balsamea) and spruce (Picea spp.). Because of their impacts, spruce budworm outbreaks are heavily monitored. The most commonly used method to study outbreak dynamics is aerial surveying of tree defoliation. However, defoliation is only a proxy of insect populations. While essential for studies of large-scale outbreak patterns, defoliation data are not ideal to study population dynamics during low-density endemic periods, or in regions at low densities during an outbreak. Long term surveys of early instar larvae (L2) conducted annually in Québec are better suited to study population dynamics, and can help us understand how the start of an outbreak is triggered. Although we know that the transition from endemic to epidemic densities is of prime importance, the temporal dynamics of spruce budworm populations before an outbreak and during its rising phase have never been examined at a provincial scale using population data. To address this gap, we analysed more than 1000 time-series of L2 counts collected across Québec between 2001 and 2018. This dataset includes counts in both the in-between outbreaks (pre-2006) and the ongoing outbreak (post-2006). We modelled the temporal dynamics of L2s throughout the outbreak extent and investigated population trends. Preliminary results showed differences in population trends (e.g., growth-rate) depending on the location in the outbreak range. Following analyses will investigate the potential effects of environmental conditions on locational differences. Early forecasts of increasing budworm populations - before defoliation is noticeable - are essential to take proactive measures. To provide adequate forecasts, a detailed understanding of the population dynamics between low and rising phases is necessary.

Akib Hasan (akib.hasan@uqat.ca), Groupe de recherche en écologie de la MRC Abitibi (GREMA), Université du Québec en Abitibi-Témiscamingue (IRF-UQAT)
Miguel Montoro Girona (miguel.montoro@uqat.ca), IRF - Université du Québec en Abitibi-Témiscamingue (UQAT)
Louis Imbeau (louis.imbeau@uqat.ca), Groupe de recherche en écologie de la MRC Abitibi (GREMA), Université du Québec en Abitibi-Témiscamingue (IRF-UQAT)
Jennifer Lento (jlento@unb.ca), Department of Biology, Canadian Rivers Institute, University of New Brunswick, Fredericton, NB, Canada.
Anouschka R Hof (anouschka.hof@wur.nl), Resource Ecology Group, Wageningen University, 6708 PB Wageningen, The Netherlands.
Guillaume Grosbois (guillaume.grosbois@uqat.ca), IRF - Université du Québec en Abitibi-Témiscamingue (UQAT)

Eskers are complex geological formation that provide crucial resources in northern countries such as drinking water, sand/gravel, outdoor recreational sites, and productive forests. However, there is a huge knowledge gap about the biodiversity and functioning of eskers. Esker lakes are different from other boreal lakes as they are mainly fed by groundwaters and precipitations and are not connected to other aquatic ecosystems. Thus, esker lakes should have reduced or absent fish communities, which promotes a unique diversity and abundance of aquatic invertebrates. This research aims to characterize the waterbird communities associated to esker lakes, identify ecological factors and characterize the resources such as fish and aquatic macroinvertebrate diversity that determine waterbird presence, abundance, richness, and diversity using a food web approach. Fifty lakes were sampled including lakes situated on eskers and lakes on the clay belt in Abitibi. We found higher Shannon diversity index for waterbirds in clay lakes (mean = 0.45) compared to esker lakes (mean = 0.31). It can be explained by the available macroinvertebrate resources, which is higher in clay lakes (mean = 1.29), compared to esker lakes (mean = 1.23). For fish, the index value in clay lakes (0.76) was higher than lakes on esker (0.10), it could be explained by the isolation of esker lakes into the aquatic ecosystem. Additionally, nutrients, conductivity and macrophyte cover in clay lakes were higher than in esker lakes, however, dissolved oxygen was higher in esker lakes. The result suggests, the diversity of esker lakes is lower in all trophic level of the food web but provide habitat to few rare and important communities. This project represents the first characterization of biodiversity associated to esker lakes; therefore, it will provide the baseline ecological information to establish conservation strategies and the sustainable management of this vulnerable ecosystem.

Christopher Hawkins (chris@srgroundworks.ca), Association of Peace River Woodlots
Christopher Maundrell (chris@adlardenvironmental.ca), Association of Peace River Woodlots
Jeffrey Beale (jdbeale81@icloud.com), Association of Peace River Woodlots

Current post-logging, management of northeast British Columbia's conifer-broadleaf boreal forest (54°-60° N latitude, 120°-123° W longitude, 10+ M ha) results in pure, even-aged conifer stands. The rationale is to enhance growth of more valuable conifers with broadleaf removal. However, this reduces species and structural diversity, habitat value, carbon storage and overall resilience. Regional climate projections suggest a different future by 2050: increased mean annual temperature, precipitation, and frost-free days. Given decreased managed stand diversity and projected changing climate, trials were initiated across the region in five to 18-year-old post-logging stands where broadleaf species had not been removed. A single crop tree in a 10 m2 plot with various levels of broadleaf competition were systematically allocated in a grid across the block. The objective was to investigate the impact of broadleaf (aspen (Populus tremuloides) or paper birch (Betula papyrifera) competition on crop tree (white spruce (Picea glauca) growth at three widely separated (150+ km) sites. At establishment, more than a decade ago, except at extreme broadleaf densities (>7000 SPH), spruce growth was not impacted. After fall 2019 remeasurements, total stand productivity and carbon storage potential in the mixedwoods was greater than TIPSY projected for a pure conifer stand of the same age and density. Mean spruce tree DBH was as great or greater than predicted in the projections. No single competition index at establishment (SPH, SDI, Lorimer Index) predicted future growth on all sites, however, indices were predictive on individual sites. The findings suggest current management in northeast BC has a low return on investment (broadleaf removal), reduces stand diversity and total productivity. Perhaps, retaining broadleaves would better meet First Nations' environmental vision, and licensee economic criteria while enhancing ecological values and long-term productivity, carbon storage, resilience and help acclimate to a changing climate without significantly affecting spruce growth.

Che Elkin (che.elkin@unbc.ca), UNBC
Luiz Terezan (terezan@unbc.ca), University of Northern British Columbia
Colin Chisholm (colin.chisholm@unbc.ca), University of Northern British Columbia
Pamela Dykstra (Pamela.Dykstra@gov.bc.ca), BC FLNRORD

The long-term sustainable of forestry can be enhanced by improving our understanding of the biological constraints on tree growth, and by better aligning our forestry objectives and management actions with our natural landscapes. In order to improve where, when and how we do forestry, a key need is accurate forest yield information and how forest growth potential is distributed across the landscape. Remote sensing techniques have been demonstrated to be efficient tools for producing reliable and accurate information regarding forest inventory. Airborne laser scanning (ALS) can be used to develop Predictive Ecosystem Maps (PEM) based on Digital Elevation Model (DEM) derived layers. These PEM models, and the variables that they are based on may be used to generate reliable information to forest growth potential using an age-independent approach. We evaluated the efficacy of using ALS-derived attributes to model growth potential (Site Index (SI)) in three ecologically disparate regions of British Columbia. Growth potential was empirically assessed in 30-year-old plantations, and compared with Biogeoclimatic Ecosystem Classification (BEC) site index estimates. We used a machine learning approach and Random Forest techniques to develop an age-independent SI model (SI_pem) incorporating DEM-derived topographic layers. The resulting site index model produces accurate SI estimates at a fine grain across the different forest ecosystems. The model performed significantly better when compared to Site Index estimations based on Biogeoclimatic Ecosystem Classification site series (SIBEC) derived models. Microclimate variables associated with water process, such as Topographic Positioning Index, Diurnal Anisotropic Heating, Positive Openness and Overland Flow Distance were universally critical for modelling SI, even though the case study regions differed with regard to annual precipitation and topographic complexity.

Léa Darquié (lea.darquie@uqat.ca), IRF - Université du Québec en Abitibi-Témiscamingue (UQAT)
Annie DesRochers (annie.desrochers@uqat.ca), CEF - IRF - Université du Québec en Abitibi-Témiscamingue (UQAT)
Patricia Raymond (patricia.raymond@mffp.gouv.qc.ca), Direction de la recherche forestière, Ministère des Forêts, de la Faune et des Parcs du Québec
Vincent Poirier (vincent.poirier@uqat.ca), Université du Québec en Abitibi-Témiscamingue

Mixed stands containing aspens (Populus tremuloides or P. grandidentata) often convert to hardwood-dominated stands after harvesting due to the aggressive natural regeneration of aspen root suckers, even if the sites are quickly replanted with conifer seedlings. Without the use of herbicides, this problem is usually dealt with several passes of manual release of overtopped seedlings. The aim of this study was to develop a new kind of manual release (reversed diameter-limit) based on aspen's autoecology and to compare it against two traditional ones (systematic [100% removal of aspen] or crop tree release [removal of competing vegetation 60 to 90 cm around planted spruce]) and an un-treated control. The reverse diameter limit release left the 20% larger aspen stems in place, in order that they continue exerting apical dominance on smaller suckers and limit suckering of the treated plots. We also anticipated that preserving the largest aspen stems would maintain soil carbon stocks of treated stands. Growth of planted spruce seedlings (Picea mariana) and aspen suckers, as well as soil carbon stocks at 15 cm depth in 5 cm increments were measured two growing seasons following treatments. Results showed that the reverse diameter limit release responded similarly to the crop tree release treatment, by reducing the number of new suckers by 91% compared to the systematic treatment. Spruce growth and density did not change between the release treatments. Soil carbon stocks increased in both the reverse diameter limit and systematic treatments compared to the control (+21% and +35% respectively). In the longer term, we anticipate that root sucker density produced in the reversed diameter-limit treatment will naturally decrease as the larger stems will exert a greater competitive pressure on new suckers than in the systematic treatment.

Kathryn C. Baer (kathryn.baer@usda.gov), USDA Forest Service
Andrew N. Gray (andrew.gray@usda.gov), USDA Forest Service Pacific Northwest Research Station

Invasions by non-native plants threaten forest health and sustainability. The ability to predict areas susceptible to invasion is essential for monitoring and management of invasive species. Species distribution models (SDMs) are often used to identify environmental correlates of a species' occurrence and predict geographic areas that may be suitable for its presence and are commonly constructed using solely abiotic predictors. However, mounting evidence suggests that not including biotic predictors in SDMs may yield less accurate results at some resolutions typical of landscape-scale models, although this possibility has rarely been evaluated in invasive plants. In this study, we determined whether including descriptors of the biotic environment improved the accuracy of SDMs built at five decreasing spatial resolutions for five common invasive plants in forests of California, Oregon, and Washington, USA and described environmental correlates of each species' presence. Predictors of habitat suitability often echoed those identified in previous studies, indicating that our models accurately identified important environmental contributors to occurrence of the focal species. Including biotic predictors in the SDMs consistently improved model accuracy only at the highest resolution examined, which may be due to the spatial scale at which biotic interactions primarily act upon species' distributions, the particular predictors we used in our models, or correlations between attributes of the abiotic and biotic environment. Our findings suggest that building SDMs using solely abiotic predictors may generally yield models whose accuracy does not differ substantially from those that include biotic predictors, the effects of biotic interactions on the distribution of invasive plants in forests may be detectable at larger scales than previously recognized. This finding supports monitoring and management strategies for invasive species by highlighting potentially important biotic predictors of their occurrence and improving models to identify areas at risk to invasion.

Matthew Garcia (matt.e.garcia@gmail.com), University of Wisconsin - Madison
Jacques Régnière (jacques.regniere@nrcan-rncan.gc.ca ), Canadian Forest Service - Natural Resources Canada
Brian R. Sturtevant (brian.r.sturtevant@usda.gov ), U.S. Forest Service, Northern Research Station
Yan Boulanger (yan.boulanger@nrcan-rncan.gc.ca ), Canadian Forest Service - Natural Resources Canada

In recent work exploring the weather-driven dispersal of adult spruce budworms (SBW: Choristoneura fumiferana Clemens) during the current outbreak in eastern North American boreal and sub-boreal forests, we described an individual-based numerical model of that process and demonstrated that SBW males and females exhibited different patterns of dispersal in simulations of two flight events in July 2013 (https://doi.org/10.1016/j.agrformet.2022.108815). Those differences arose from physiological variations between SBW males, who are generally smaller and carry less mass, and females who carry greater mass due to egg loads through much of their adulthood. Combined with the temperature-driven aspects of SBW flight physiology, these differences led to generally higher and longer flights for males and generally earlier, lower, and shorter flights for females. The SBW males and females thus carry on their contributions to SBW reproduction, either by alleviating mating failure in existing populations or by oviposition, respectively, in different locations. Here we review our modeling results and analyses, including variability in estimated landing locations. We then extend that work to estimate potential effects on the development and spread of an SBW outbreak to new locations using a highly simplified, but spatially explicit, model of SBW population dynamics including dispersal events. Idealized simulations demonstrate the effects of male immigrants on the existing SBW population in some locations and the effects of egg-laying female immigrants in others where SBW may or may not already exist. We discuss conclusions regarding the roles of sex differences in dispersal during an SBW outbreak, especially the varied contributions of that process to overcoming Allee effects (mating failure) and the establishment of new population hotspots, and their effects on an outbreak's regional trajectory (population densities and areal coverage) over space and time.

Graham S. Frank (graham.frank@oregonstate.edu), Oregon State University
Meg A. Krawchuk (meg.krawchuk@oregonstate.edu), Oregon State University

In several North American forest ecosystems, early seral forests generated by stand-replacing disturbances can be the most biologically diverse stage of development and provide habitat for many taxa of conservation concern. Some early seral associated taxa are supported by timber harvesting, but these anthropogenic forms of early seral forest can differ in structure, composition, and temporal characteristics from those generated by natural disturbances. In the Pacific Northwest, research on early seral bird assemblages has focused on the effects of management decisions in intensively managed plantations. However, it is unclear to what degree post-harvest early seral forests support the biodiversity associated with their closest natural counterpart: stand-replacing wildfire. As part of a multi-taxa study across public and private ownerships in southwest Oregon, USA, we conducted breeding season point counts to compare bird assemblages across a 2--20-year chronosequence of young forest development following either clearcutting with intensive management or high-severity wildfire. We also sampled across a shorter 6--8-year chronosequence following post-fire salvage logging. Preliminary results from a multispecies occupancy model suggest that intensively managed clearcuts initially support fewer bird species than recent burns. However, richness increased with post-harvest stand development, and older clearcut stands may support as many or more species than older burns. We found similar trends for richness of leaf-gleaning insectivores, a guild of conservation concern, likely tracking differences in vegetation development. Overall, differences in community composition between disturbances were greatest for the most recently disturbed stands but diminished with stand age, reinforcing the idea that management alters the temporal characteristics of early seral wildlife assemblages. Bird assemblages in salvage logged stands were distinct from both unlogged burns and from intensively managed clearcuts of the same age. Understanding variability in early seral forest habitat will inform coarse-scale conservation planning, as well as tradeoffs between conservation and production goals.

Amanda Catherine Diochon (adiochon@lakeheadu.ca), Department of Geology, Lakehead University
Dave M. Morris (dave.m.morris@ontario.ca ), Ontario Ministry of Northern Development, Mines Natural Resources and Forestry
Ethan Brand (ewbrand@lakeheadu.ca), Department of Geology, Lakehead University
Robin Couch (rlsevean@lakeheadu.ca ), Faculty of Natural Resources, Lakehead University
Nancy Luckai (nluckai@lakeheadu.ca), Faculty of Natural Resources, Lakehead University

Wood ash produced from burning biomass for energy is typically landfilled but could be applied as a soil amendment to ameliorate acidity and mitigate nutrient losses associated with biomass harvesting. These soil improvements may enhance tree growth and foliar nutrition and may lead to increases in soil organic carbon stores. In 2012 we applied low and high carbon wood derived ash at rates of 0, 1000 and 10000 kg ha-1 to soils planted with Picea mariana (Mill.) B.S.P. and Picea glauca (Moench) Voss in a replicated factorial design. Initial measurements prior to and 4 mo after application showed that ash application increased soil pH, EC, and Ca and Zn concentrations and decreased soil Fe and Mn concentrations. Low carbon ash, applied at the highest rate, had the greatest effect on soil properties. Microbial respiration increased with ash application and microbial biomass decreased but there were no differences in carbon concentrations. As assessment of soil carbon fractions three years after application showed no effects of ash application on any of the measured fractions. Seven years after ash application CEC, Ca, Cu, Ca, and Mn were significantly higher in the soils receiving the low carbon ash at the high loading rate than all other treatments and there was no effect on soil carbon. In 2019, we re-applied the ashes at the same rates as in 2012 and measured soil properties in the two years following application. Soil pH, EC, and concentrations of Ca, Cu, S, K, Mg, Mn and Zn were all affected by ash application. Effects were again greatest for the low carbon ash applied at the highest rate. Soil carbon was significantly higher in soils receiving 10 000 kg ha-1 ash in 2019 but only for the high carbon ash under white spruce in 2020.

Eliot McIntire (eliot.mcintire@NRCan-RNCan.gc.ca), Canadian Forest Service - Natural Resources Canada

Forest management is challenged to meet many different - sometimes opposing - needs. For many of these needs, such as timber values, conservation values, public safety, and sustainability, science has a long history of contributing knowledge that has proven helpful. Forecasting forest values under changing fire, pest, disease, flooding and drought conditions that we are facing under the current and future conditions is becoming complicated. Furthermore, the role of First Nations in forest and land management is evolving and may have different objectives than the governments who have historically created forest practices. Unfortunately, the existing tools are being stretched beyond what they were often designed for. The open data revolution has begun in science, with ever increasing benefits to a diversity of users. But, data without understanding and insight are not a panacea. Today, I will present the beginnings of how open science and open models are leading to new open tools, new conversations and new relationships. I will present several case studies showing some early examples of these tools in action that are assisting forest management and decision making. I will show examples of caribou conservation, First Nations, forestry planning, wildfire under climate change, protected areas management and how these are interacting with the best available science and with diverse participation. One of the key features of these new tools is that they embrace nimbleness. This allows new data and new models to immediately flow into decision support tools; it allows the project to produce a "final" output at the start and data and knowledge holes can be identified at the start; and it allows for science to adjust quickly as new issues arise. While these open approaches are still in their infancy, they are being tried across Canada, from the forests of BC, the Ring of Fire regional assessment in Ontario, across the territories where mining claims are active, to name a few. They are creating new conversations between different areas of science, decision making approaches, and new levels of participation in the processes of land management.

J. Davis Goode (jdgoode2@crimson.ua.edu), University of Alabama
Anuska Narayanan (anarayanan1@crimson.ua.edu), University of Alabama
David Phillips (dlphillips1@crimson.ua.edu), University of Alabama
Justin Hart (hart013@ua.edu), University of Alabama
Daniel Dey (daniel.c.dey@usda.gov), USDA Forest Service

Mixed oak-pine stands are increasingly desired by forest managers to achieve a range of objectives, including biodiversity enhancement and resilience to global change. To create and perpetuate desired mixed oak-pine stand composition and structure, information on natural disturbance impacts on stand development and succession is necessary. Wind is the most prolific natural canopy disturbance in eastern North America, and impacts vary in severity and spatiotemporal scales. Intermediate-severity disturbance is hypothesized to be an important driver of mixed oak-pine stand composition and structure. Our overarching goal was to quantify impacts of intermediate-severity wind disturbance in a mixed oak-shortleaf pine stand on the Cumberland Plateau in Tennessee. Our objectives were to 1) infer the drivers of individual tree mortality, 2) quantify the spatial patterns of pre-disturbance trees and post-disturbance residual trees, and 3) determine the stand-scale frequency, size, and distribution of canopy openings. We inventoried plots in shortleaf pine-dominated, disturbance-impacted portions of the stand. To infer individual tree and site characteristics that influenced survival probability, we applied a random forest classification algorithm. To document changes in tree spatial distribution before and after disturbance, we used spatial point pattern analysis. To characterize stand-scale disturbance patterns, we classified canopy gaps from high-resolution satellite imagery. The most important predictors of survival were taxonomic group, basal area, and distance to nearest neighbor. Pre-disturbance trees and residuals were spatially randomly distributed. Most detected gaps were 50-150 m2, and the gap size frequency distribution exhibited a reverse J-shape. Gaps were spatially clustered within the stand at distances < 200 m. Results indicated canopy disturbance alone is likely insufficient to promote desired species assemblages. Our results provide recommendations on the frequency, size, and distribution of silvicultural entries patterned after natural disturbance.

Anoj Subedi (Anoj.Subedi@uqat.ca), Groupe de recherche en écologie de la MRC Abitibi (GREMA), Université du Québec en Abitibi-Témiscamingue (IRF-UQAT)
Miguel Montoro Girona (Miguel.Montoro@uqat.ca), IRF - Université du Québec en Abitibi-Témiscamingue (UQAT)
Philippe Marchand (Philippe.Marchand@uqat.ca), IRF - Université du Québec en Abitibi-Témiscamingue (UQAT)
Yves Bergeron (Yves.Bergeron@uqat.ca), IRF - Université du Québec en Abitibi-Témiscamingue (UQAT)
Hubert Morin (Hubert_Morin@uqac.ca), University of Quebec in Chicoutimi (UQAC)

Spruce budworm (Choristoneura fumiferana) (SBW) outbreaks are a major disturbance in Canadian boreal forests with three distinct outbreak periods (1905-1930, 1935-1965 & 1968-1988) in the last century; the late century outbreak affected over 50 million hectares. The cumulative defoliation of host species by SBW over 4-5 years results in a decrease in growth and mortality, which has affected the forest productivity and the dynamics of the boreal forests. With the changing global scenario, the frequency, and severity of SBW outbreaks are changing and consequences are becoming more serious. But, how the growth of boreal tree species like black spruce (Picea mariana) was influenced by the climate during the outbreak period? We aim to evaluate the impact of climatic factors and SBW-defoliation on black spruce growth during the last outbreak of the 20th century in Quebec. For this, we compiled dendrochronological (2277 trees), defoliation and climate data for 164 sites distributed approximately over 900,000 km2. After having site-specific growth indices, cumulative defoliation over 5 years, and climatic parameters, we used the linear mixed-effects model to determine the interaction effects on the growth. Our results revealed that during severe defoliation (71-100%) over a year in a site, the average growth is reduced by 3.3% whilst other associated effects are constant. During the defoliation period, when SBW larva is feeding on black spruce, one standard deviation increase in June temperature (C) and June Climate Moisture Index (CMI, mm) increases the defoliation effect by 3.3% and 2.1% respectively. This result suggests that the positive response of black spruce growth to an increase in temperature might be limited by its coincidence with the larval emergence period of SBW. This research will contribute to improving our understanding of SBW-climate and growth interactions, which is essential to establishing forest management strategies in the face of climate change.

Kymberly Draeger (kymi.draeger@gmail.com), University of Wisconsin - Madison and US Forest Service - Center for Forest Mycology Research
Deborah S. Page-Dumroese (debbie.dumroese@usda.gov), USDA Forest Service
Mark Banik (mark.t.banik@usda.gov), USDA Forest Service
Glen Stanosz (gstanosz@wisc.edu), University of Wisconsin - Madison
Karen Nakasone (karen.nakasone@usda.gov), USDA Forest Service
Mark Coleman (mcoleman@uidaho.edu), University of Idaho - Moscow
Michelle Jusino (michelle.jusino@usda.gov), USDA Forest Service
Thea Whitman (twhitman@wisc.edu), University of Wisconsin - Madison
Daniel Lindner (daniel.l.lindner@usda.gov), USDA Forest Service

Forest ecosystems evolved with a range of fungal communities, above and below-ground. This research utilized two different methods of fungal community sampling (collection of above-ground fruiting bodies vs. DNA-based methods) to assess the effects of biomass harvesting (four thinning levels) and compensatory soil amendments (+/- fertilizer, biochar) in a western conifer forest (400-m2 plots). Fruiting bodies (e.g. mushrooms, crusts, etc.) of wood-inhabiting fungi were sampled over 3 years, in the fall. Over 1,000 wood-inhabiting fungal fruiting bodies, comprising 129 species, were collected and identified over 3 years ? including pathogens and decomposers. Biomass harvesting significantly influenced the fungal community composition in the first and third years of sampling (p < 0.04). Soil amendments moderately influenced the fungal community composition in the second year of sampling (p = 0.064), with fertilization being the primary driver of dispersion differences (p < 0.02). DNA-based surveys were conducted by affixing wood stakes to the soil surface and within the mineral layer, and retrieving them annually for three years. The stakes were drilled to produce wood shavings that were used for extraction of fungal DNA. Over 2,000 different operational taxonomic units (OTUs), of mostly microscopic ascomycete species were identified. Fungal community composition in the surface stakes was influenced by biomass treatments all three years (p < 0.04), and soil amendments significantly influenced the fungal community composition in the first and third years (p < 0.04). Fertilization was initially associated with the lowest OTU richness; but after three years, the surface stakes of fertilized plots had the greatest fungal OTU richness. Different sampling methods revealed different fungal communities. Fungal fruiting body surveys sampled a range of substrates, identified important forest pathogens (indicating the trajectory of the future forest and carbon sequestration), whereas sequencing did not. DNA-based methods are more sensitive to treatments.

Emily Smenderovac (emily.smenderovac@nrcan-rncan.gc.ca), Great Lakes Forestry Centre - Canadian Forest Service - Natural Resources Canada
Caroline Emilson (caroline.emilson@nrcan-rncan.gc.ca), Great Lakes Forestry Centre - Canadian Forest Service - Natural Resources Canada
Teresita Porter (terrimporter@gmail.com), Great Lakes Forestry Centre - Canadian Forest Service - Natural Resources Canada
Dave M. Morris (Dave.M.Morris@ontario.ca), Ontario Ministry of Northern Development, Mines Natural Resources and Forestry
Paul Hazlett (paul.hazlett@nrcan-rncan.gc.ca), Great Lakes Forestry Centre - Canadian Forest Service - Natural Resources Canada
Amanda Diochon (adiochon@lakeheadu.ca), Department of Geology, Lakehead University
Nathan Basiliko (nbasiliko@laurentian.ca), Laurentian University, Sudbury, Canada
Nicolas Bélanger (nicolas.belanger@teluq.ca), Université TELUQ
John Markham (John.Markham@umanitoba.ca), University of Manitoba, Manitoba, Canada
P. Michael Rutherford (Mike.Rutherford@unbc.ca), University of Northern British Columbia, Prince George, Canada
Ken van Rees (ken.vanrees@usask.ca), University of Saskatchewan, Saskatoon, Canada
Trevor Jones (trevor.jones@nrcan-rncan.gc.ca), Great Lakes Forestry Centre - Canadian Forest Service - Natural Resources Canada
Lisa Venier (lisa.venier@nrcan-rncan.gc.ca), Great Lakes Forestry Centre - Canadian Forest Service - Natural Resources Canada

There is interest in utilizing wood ash as an amendment in forestry operations as a mechanism to return nutrients to soils that are removed during harvesting, with the added benefit of diverting this bioenergy waste material from landfill sites. AQ1Existing studies have not arrived at a consensus on what the effects of wood ash amendments are on soil biota. We collected forest soil samples from studies in managed forests across Canada that were amended with wood ash to evaluate the effects on arthropod, bacterial and fungal communities using metabarcoding of F230, 16S, 18S and ITS2 sequences as well as enzyme analyses to assess its effects on soil biotic function. Ash amendment did not result in consistent effects across sites, and those effects that were detected were small. Overall, this study suggests that ash amendment applied to managed forest systems in amounts (up to 20 Mg ha1) applied across the 8 study sties had little to no detectable effects on soil biotic community structure or function. When effects were detected, they were small, and site-specific. These non-results support the application of wood ash to harvested forest sites to replace macronutrients (e.g., calcium) removed by logging operations, thereby diverting it from landfill sites, and potentially increasing stand productivity.

Fidèle Bognounou (fidele.bognounou@nrcan-rncan.gc.ca), Canadian Forest Service - Natural Resources Canada
David Paré (david.pare@canada.ca), Canadian Forest Service - Natural Resources Canada
Jérôme Laganière (jerome.laganiere@nrcan-rncan.gc.ca), Canadian Forest Service - Natural Resources Canada

A combination of global changes (e.g. soil acidification, invasive species, forest management, climate) impacts the regeneration dynamics of sugar maple?dominated stands in northeastern North America. More specifically, there are concerns about the regeneration of sugar maple and other high-value species due to the expansion of American beech and its bark disease killing mature trees, compromising fiber supply and other ecosystem services. Here, we set up a field trial to study the effect of soil treatments (scarification, nitrogen fertilization, liming and wood ash amendments) on species recruitment following selection cutting in a beech-invaded sugar maple stand to promote the regeneration of high-value species, to control American beech expansion, and help reduce the impacts of beech bark disease on stand development. After 3 years of monitoring, we found that there is a high and significant dissimilarity among species recruitment based on environmental variables (soil and residual vegetation characteristics). The recruitment of pin cherry and yellow birch was associated with soil scarification, American beech was associated with ash and lime amendments to non-scarified soils and pin cherry was associated with fertilizer application to non-scarified soils. The main drivers determining species recruitment differed among species. The soil treatments had a high influence on the recruitment of American beech, pin cherry and yellow birch, while they had a moderate influence on red and sugar maple regeneration. The soil treatments had significant effects (positive or negative) on species recruitment and the strength and direction of the effects varied among species and over time. On non-scarified soils, fertilizer and lime applications reduced significantly American beech recruitment while ash amendment had the opposite effect. Overall, our results suggest that a combination of soil scarification and amendments could help fine-tune early forest composition and dominance in high-value northern hardwood forests

Timothy T. Work (work.timothy@uqam.ca), CEF - Université du Québec à Montréal (UQAM)
Dave M. Morris (Dave.M.Morris@ontario.ca), Ontario Ministry of Northern Development, Mines Natural Resources and Forestry
Lisa Venier (lisa.venier@nrcan-rncan.gc.ca), Great Lakes Forestry Centre - Canadian Forest Service - Natural Resources Canada

Post-harvest removal of residual forest biomass may provide additional sources of renewable energy but may also pose substantial risks to resident biodiversity. We evaluated changes in ground beetle, rove beetle and spider assemblages 7-8 years post-harvest in clearcut jack pine stands where 1) residual branches and tops were left on site (stem-only), 2) boles and branches were removed (whole-tree), 3) boles, branches and stumps were removed (stumped) and 4) all woody material and soil organic layer were removed (bladed). We also compared effects of subsequent applications of glyphosate within harvested plots. Arthropod assemblages in harvested plots were further compared to assemblages in older jack pine stands that had originated from wildfire, younger jack pine stands that had originated following clearcutting and a recent, severely burned jack pine plantation. We collected 50 ground beetle species (7258 individuals), 108 rove beetle species (3218 individuals) and 166 spider species (10854 individuals) during this re-sampling period. We compared arthropod assemblages separately using multivariate regression trees. For all three groups, composition differed among old, young and burned stands, but ground beetle composition in burned stands was more similar to old and young stands whereas rove beetle and spiders collected from burns were more similar to harvested stands. For all three groups, composition differed between bladed plots and less-intensive biomass removal treatments. For ground beetles, glyphosate caused further compositional differences among stem-only, full-tree and stump removal treatments. For spiders, glyphosate eliminated compositional differences between stem-only, whole-tree and stump removal treatments. Glyphosate had no effect on rove beetle composition. Thus, severe impacts on forest floor conditions from biomass removal are further affected by glyphosate depending on the taxa. Nevertheless, there is little indication that arthropod composition in biomass removal plots is recovering almost a decade following harvest.

Amanda Diochon (adiochon@lakeheadu.ca), Department of Geology, Lakehead University
Rutht Joseph (rjoseph3@lakeheadu.ca), Department of Geology, Lakehead University
Dave M. Morris (dave.m.morris@ontario.ca), Ontario Ministry of Northern Development, Mines, Natural Resources and Forestry
Lisa Venier (lisa.venier@nrcan-rncan.gc.ca ), Great Lakes Forestry Centre - Canadian Forest Service - Natural Resources Canada
Caroline Emilson (caroline.emilson@nrcan-rncan.gc.ca), Great Lakes Forestry Centre - Canadian Forest Service - Natural Resources Canada
Nathan Basiliko (nbasiliko@laurentian.ca), Laurentian University, Department of Biology and the Vale Living with Lakes Centre
Nicolas Bélanger (nicolas.belanger@teluq.ca ), Université TÉLUQ, Département Science et Technologie
Trevor Jones (trevor.jones@nrcan-rncan.gc.ca ), Natural Resources Canada - Canadian Wood Fibre Centre
John Markham (John.Markham@umanitoba.ca ), University of Manitoba, Department of Biological Sciences
Michael Rutherford (Mike.Rutherford@unbc.ca ), University of Northern British Columbia
Ken Van Rees (ken.vanrees@usask.ca), Department of Soil Science, University of Saskatchewan
Emily Smenderovac (emily.smenderovac@canada.ca), Great Lakes Forestry Centre - Canadian Forest Service - Natural Resources Canada
Paul Hazlett (paul.hazlett@canada.ca), Great Lakes Forestry Centre - Canadian Forest Service - Natural Resources Canada

In Canada, the combustion of forest biomass for bioenergy production has been increasing with an associated increase in residual wood ash. Wood ash is typically landfilled as waste but there is growing interest in applying wood ash to the soils of commercial forests. Ideally, wood ash supplies nutrients that may have been removed through biomass harvesting, increases soil pH which improves nutrient availability, and potentially improves site productivity but there is also potential for detrimental effects, such as toxicity, that impair soil functions. The objective of this study was to investigate the effects of wood ash application on soil organic matter attributes at eight experimental sites across Canada that are examining the effects of wood ash application on site fertility, productivity, and soil biodiversity. Wood ash application had an effect on total carbon (TC) and total nitrogen (TN), microbial biomass carbon (MBC), hot water extractable carbon (HWEC), mineralizable C, sand size C, and HWEC and MBC normalized to TC but changes were typically restricted to single sites or differed in their direction, i.e. positive or negative. Based on the limited and inconsistent effects of ash on established indictors of soil quality measured in this study, there does not appear to be any advantageous or detrimental effects of adding wood ash to forest soil quality.

Room ALGOMA

Opening Remarks

11:00 - Lisa Venier

Conference Opening & Welcome
Abstract

Keynote 1: Dr. Matthew Betts
moderator: Lisa Venier

11:15 - Matthew Betts

Producing wood at least cost to biodiversity
Abstract

Room ROBERTA BONDAR

Does a novel world need novel silviculture?
moderator: Austin Himes

12:30 - Anthony D'Amato

Can stand-level outcomes of ecological silviculture address novel dynamics?
Abstract
12:45 - Marie-Josée Fortin

Combining network theory and tree functional traits to improve forest resilience to global change
Abstract
13:00 - Austin Himes

Silviculture for multiple ecosystem services and values
Abstract
13:15 - Maria Janowiak

No Single Answer: Crafting Management Opportunities in Response to Climate Change
Abstract
13:30 - Kristen M Waring

Forest health through silviculture: strategies for an uncertain, complex future
Abstract
13:45 - Marcella A. Windmuller-Campione

Opportunities for Critical Thinking in Silviculture Education
Abstract

Sustainable Forest Management 1
moderator: Trevor Jones

14:40 - Emily Peters

Minnesota DNR's approach for managing old growth forests
Abstract
14:55 - Clément Hardy

Uneven-aged management is no ecological panacea for large spatiotemporal scales in unmanaged boreal landscapes
Abstract
15:10 - Ajay Sharma

Is uneven-aged silviculture a good management option for southern pines?
Abstract
15:25 - Catherine Rose Henry

Tree regeneration of key forest types in the Northwoods: implications for conservation and management
Abstract
15:40 - Léa Darquié

Effect of manual release on regeneration and carbon stocks in mixed trembling aspen and black spruce stands
Abstract
Related poster : Abishek Poudel

Using UAV Multi-Spectral Imagery for Forest Regeneration Assessment
Theme: Sustainable Forest Management
Abstract
Related poster : Hengyi Bai

Impact of forest harvesting on the functioning of boreal forest lakes
Theme: Sustainable Forest Management
Abstract

Room SUPERIOR

Partial cutting as a strategy to reduce carbon emissions from the forest sector
moderator: Jodi Axelson

12:30 - Suzanne Winette Simard

Group retention protects carbon stocks in Douglas-fir forests
Abstract
12:45 - Michelle Venter

Reducing logging intensity in north temperate rainforests for climate change mitigation
Abstract
13:00 - Alana Clason

Modelling partial harvesting effects on carbon using SORTIE-ND
Abstract
13:15 - James Steenberg

Carbon and the Triad: Implications of Triad Functional Zoning in Forest Management in Nova Scotia, Canada
Abstract
13:30 - Ellen Macdonald

Carbon dynamics as affected by varying levels of retention harvesting in boreal mixedwood forests
Abstract

Insect Disturbance
moderator: Amanda Roe

14:40 - Barry Cooke

Complexity to convergence: Landscape-scale effect of forest structure on cycle intensity and synchrony in two contrasting defoliator systems
Abstract
14:55 - Hiromitsu Sato

Dynamic Simulation of Insect Disturbance with a Climate-Vegetation-Fire Model
Abstract
15:10 - Morgane Henry

Temporal dynamics of spruce budworm (Choristoneura fumiferana) during the rising phase of an outbreak
Abstract
15:25 - Franck Gandiaga

Quantifying long-distance dispersal of outbreaking insect species by combining phenological models with empirical data.
Abstract
15:40 - Matthew Garcia

Differences in weather-driven dispersal patterns between spruce budworm males and females and their potential effects on nearby populations
Abstract
15:55 - Anoj Subedi

How does climate affect the growth during spruce budworm outbreaks period? A story after the 1950's
Abstract
16:10 - Clara Risk

Improving eastern spruce budworm outbreak sketch maps affected by survey flight paths in north-central Ontario using Landsat time series analysis
Abstract
16:25 - Jalene LaMontagne

Variation in eastern spruce budworm defoliation across trees within forest stands
Abstract
Related poster : Suzanne Bethers Marchetti

Successful Reduction of a Mountain Pine Beetle Outbreak in the Southern Rocky Mountains
Theme: Insect disturbance
Abstract
Related poster : Sophie Wilkinson

The Impact of Mountain Pine Beetle on Wildfire Behaviour: A Scoping Review
Theme: Insect disturbance
Abstract
Related poster : Ana Sofia Rivera

Ticks & tick-borne disease dynamics across contiguous united states
Theme: Insect disturbance
Abstract

Room HURON

Climate Change 1
moderator: Stephen Mayor

12:30 - Benjamin Lee

Tree-wildflower phenological mismatch differs across continents in response to spring warming
Abstract
12:45 - Rongzhou Man

Spring phenology and phenological responses to climate warming
Abstract
13:00 - Angel Rolando Agramont

Dwarf mistletoe infestation in high mountain forests of Mexico
Abstract
13:15 - Andrew N. Gray

Annual variation in carbon sequestration and disturbance impacts in west coast forests
Abstract
13:30 - Margaret Woodbridge

Fine-scale variability in the mesophication of eastern US forests
Abstract
Related poster : Samuel Robin

Simulating the future to discover the impact of climate change on the germination and establishment of boreal seedlings
Theme: Climate Change
Abstract

Wildlife/Biodiversity
moderator: Timothy T. Work

14:40 - Lauren Egli

Substantial recovery of ground beetle communities over 20-years following conventional clear-cutting and partial retention harvesting in boreal mixedwoods
Abstract
14:55 - Urszula Deregowski

Long-Term Effects of High and Low Intensity Partial Cutting on Saproxylic Beetle Communities In Aspen-Dominated Stands of the Eastern Boreal Mixedwood Forest
Abstract
15:10 - Akib Hasan

Discovering a Unique Biodiversity: The Esker Project
Abstract
15:25 - Alison Ochs

Response of terrestrial salamanders to the decade following timber harvest in hardwood forests
Abstract
15:40 - Graham S. Frank

Does forest harvest emulate natural wildfire disturbance for early seral bird assemblages in the Pacific Northwest?
Abstract
15:55 - Jessica H. Barton

Local to continental-scale small mammal population dynamics in North America
Abstract
16:10 - Jaime Pinzon

Spider responses to peatland fragmentation from oil and gas exploration in Alberta, Canada
Abstract
16:25 - Timothy T. Work

Persistent effects of biomass removal on ground beetles, rove beetles and spiders are further affected by glyphosate applications in jack pine forests in Ontario, Canada.
Abstract
Related poster : David Hohl

Changes over time in tree characteristics and tree cavities across habitats in a highly urban area
Theme: Wildlife/Biodiversity
Abstract
Related poster : Jonathan Cazabonne

Unravelling the unique fungal diversity hidden in podzol from Abitibi esker forests.
Theme: Wildlife/Biodiversity
Abstract

Room BATCHAWANA

Poster Viewing

Kendriah Pearse

The wildland fire environmental characteristics associated with historical wildfire evacuations in the province of Ontario, Canada
Theme: Fire Response
Abstract
Melanie Wheatley

Modelling airtanker suppression on successful fire containment in Ontario
Theme: Fire Response
Abstract
Marin Chambers

1 year post-fire tree germination following four 2020 Colorado Wildfires across multiple vegetation types
Theme: Fire Response
Abstract
Sophie Wilkinson

The Impact of Mountain Pine Beetle on Wildfire Behaviour: A Scoping Review
Theme: Insect disturbance
Abstract
Suzanne Bethers Marchetti

Successful Reduction of a Mountain Pine Beetle Outbreak in the Southern Rocky Mountains
Theme: Insect disturbance
Abstract
Ana Sofia Rivera

Ticks & tick-borne disease dynamics across contiguous united states
Theme: Insect disturbance
Abstract
Michel Guimond

Riparian buffer: an efficient tool or a long-term problem in Canadian boreal forest?
Theme: Silviculture
Abstract
Sanghyun Kim

Managing Innovative Silvicultural Alternatives (MISA) for Conifer Regeneration in Eastern Canadian Boreal Forests
Theme: Silviculture
Abstract
Martín Alcalá

Edge effect, growth shock, and mortality following partial cuts on esker and Clay Belt forests.
Theme: Silviculture
Abstract
Olivia Rianhard

Edge influences and fragmentation on ectomycorrhizal fungal communities in and surrounding 26-year-old clearcuts in an Engelmann spruce - Subalpine fir forest
Theme: Silviculture
Abstract
Mary Ann Fajvan

Integrating Silviculture with Hemlock Woolly Adelgid Mitigation: Crown Dynamics of Tsuga canadensis 10-years after thinning
Theme: Silviculture
Abstract
Claudia I. Bartlick

Over the Hump: Effect of Artificial Tip-Up Mounds on Tree Seedling Composition in a Managed Northern Hardwood Forest
Theme: Silviculture
Abstract
Benjamin Rhodes

Evaluating Restoration Outcomes: Red Spruce Reforestation in the West Virginia Highlands
Theme: Silviculture
Abstract
Pamela Jeanne Pelletier

Deconstructing Smokey: unraveling the wildfire campaign in America
Theme: Social Science and Policy
Abstract
Hengyi Bai

Impact of forest harvesting on the functioning of boreal forest lakes
Theme: Sustainable Forest Management
Abstract
Abishek Poudel

Using UAV Multi-Spectral Imagery for Forest Regeneration Assessment
Theme: Sustainable Forest Management
Abstract
Victoria Shveytser

Evaporation and transpiration from multiple proximal forests and wetlands
Theme: Vegetation
Abstract
Jonathan Cazabonne

Unravelling the unique fungal diversity hidden in podzol from Abitibi esker forests.
Theme: Wildlife/Biodiversity
Abstract
David Hohl

Changes over time in tree characteristics and tree cavities across habitats in a highly urban area
Theme: Wildlife/Biodiversity
Abstract
Samuel Robin

Simulating the future to discover the impact of climate change on the germination and establishment of boreal seedlings
Theme: Climate Change
Abstract

Room WHITE PINES

Yoga, Pilates, Meditation, Brought to you by Fit Bodies Fit Minds

00:00 - Fit Bodies Fit Minds

Yoga, Pilates & More!
Abstract