Northern hardwood forests occupy millions of hectares in the eastern United States and Canada, representing one of the most economically important and ecologically diverse forests in eastern North America. Northern hardwood silviculture is diverse and complex as well, and has been the focus of extensive research for over 80 years. Today, managers continue to seek innovative sustainable management solutions to address the expanding challenges facing this forest type, including serious threats such as invasive species, inadequate tree regeneration and shifts in composition, degraded timber quality, herbivory, climate change, nitrogen deposition, and forest fragmentation. The Northern Hardwood Conference (NHC) will give researchers, academia, and forest managers from across the range of northern hardwoods a forum to learn, share, and discuss cutting-edge science and innovative management practices to sustain healthy and productive northern hardwood forests.
Gap Dynamics or More Than That? Long-term Development of Mixed Hardwood Forests
It is not unreasonable to think that sustainable management of Northern Hardwood Forests would be partly informed by long-term data on forest dynamics. Most measures and observations of forest dynamics are set by grants (3-5 years), the careers of scientists and managers (20-40 years), or, less frequently, long-term plots approaching 100 years or so in age. While these data and observations are incredible and useful, they represent only a fraction in the lifetime of most trees and far less than what I’d estimate the length of forest generation to be. We have analyzed tree-ring records from local to subcontinental scales that cover the three to five centuries in mixed hardwood forests. In no way do these analyses supersede the great data mentioned above. They do color in the natural and understandable gaps in knowledge of forest processes and dynamics. We have identified climate as one potential synchronizer of forest dynamics over subregional scales that, together with gap dynamics and many other types of drivers, helped to create today's old-growth forests. Put another way, while the classical theory on the cyclical nature of Beech-Birch-Maple gap dynamics in Northern Hardwood Forests are likely a very real phenomenon, other drivers at longer time scales and broader scales might suddenly push the trajectory of these forests at various points in time into new structures or compositions.
Past, Present, and Future of the Hardwood Forest in New Brunswick
New Brunswick’s forest cover 85% of the landbase and half of the area in publicly owned (Crown Lands). Since its existence, the Northern Hardwoods Research Institute has aligned its research and development operations to address current challenges of the entire forest products sector in the province. During the second part of the conference plenary session, we will present the NHRI and highlight its workplan that is aligned with the challenges the sector is facing as presented by the Department of Natural Resources and Energy Development of New Brunswick discussed during the first part of the plenary session.
Northern Hardwoods Research Institute's Silviculture Prescription System Workshop
The Northern Hardwoods Research Institute (NHRI) has developed a simple framework that synthesises its body of knowledge and that of others so that practitioners can consider recommendations for harvest-based silviculture in mixed and hardwood stands. The Silviculture Prescription System (SPS) applies to stands in the Northeast that contain less than 30% softwoods. The NHRI’s Silviculture Prescription System is a 5-step process that starts with the description of a stand and ultimately recommends very specific treatments in forests that are dominated by hardwoods. It has a relatively narrow scope and is applicable mostly where a forest landowner choses to increase the monetary value of the woodlands through the production of timber. The NHRI Silviculture Prescription System was introduced in 2015 and its implementation was gradually undertaken in various stands of all tenure types in New Brunswick. From these trials, several improvements were recommended and led to the re-design of the SPS. Version 2.0 of the SPS was completed in January 2020. Improvements brought to our original SPS include: a simplified framework, anew nomenclature of silviculture systems to minimize confusion on two-aged/extensive systems (formerly called “Irregular Shelterwoods”),a more robust logic for treatment determination and, more information and tools for implementation. During the workshop, we will provide an overview of the SPS and illustrate its applicability using actual sample stands.
A review of challenges and research priorities for northern hardwood forests.
The northern hardwoods conference held in Fredericton, New Brunswick in 2023 was an excellent opportunity to review challenges and research priorities for stakeholders in northern hardwoods management. The northern hardwoods forest has been changing and continues to change. Forest management and silviculture practices must adapt. We are facing issues with regeneration of limited species, a decrease in tolerant hardwood vigor and quality, climate change and multiple conflicting objectives such as market demand, demand for increasing maple syrup production, and proposed increases in conservation land. Fortunately, the gathering of industry, business, and technology experts, researchers, and government at the Northern Hardwood Conference presents us with some opportunities and solutions. Since its existence, the Northern Hardwoods Research Institute has aligned its research and development operations to address current challenges of the entire forest products sector in the province of New Brunswick. In this report, we highlight the collective challenges in managing for tolerant hardwoods and we present NHRI’s existing and future solutions to those issues that will guide our research priorities going forward. We propose three major focus areas in which to do so: Silviculture of northern hardwood and mixedwood stands, climate smart silviculture / adaptive management, and technology-based solutions to precision forest inventory and digitalizing the forest value chain. These focus areas will each include training, collaboration, adaptive management, and building the tools and technology to help inform practitioners and policymakers to move toward a more valuable northern hardwood forest.
Indigenous Seed Collection Scientific Presentation
The National Tree Seed Centre (NTSC) maintains a dynamic living library of Canada’s forest genetic resources. The centre is located at the Canadian Forest Service’s Atlantic Forestry Centre in Fredericton, New Brunswick. It’s Indigenous Seed Collection Program supports Indigenous-led seed collections of species of medicinal, spiritual, cultural, and economic importance. By creating a network of Indigenous seed collectors from across Turtle Island, we can stay connected and forge reciprocal relationships with the land and each other. The goal is to combine traditional Indigenous ecological knowledge with Western scientific approaches and research to better preserve and protect species of interest to Indigenous communities for the future; particularly as climate change threatens ecosystems.
Priortizing crown dieback when tree marking increases value recovery as well as stand vigor.
In northern hardwood forests, tree markers select the trees to be harvested during logging operations using classification systems that assign harvest priorities based on the presence and severity of a wide range of individual defects. According to the most recent advances in our understanding of the impact of these defects on both tree vigour (reflecting the risk of dying or declining in growth) and quality (reflecting the potential for recovering valuable sawlogs), these systems would benefit from prioritizing the removal of trees with crown dieback and substantially reducing the number of stem defects included. In this study, we compared the potential advantages and disadvantages of such simplified tree marking system over those currently used in the province of Quebec, Canada. To do so, we conducted tree marking simulation and value recovery assessment in 14 managed stands distributed across the northern hardwood range. Our results confirmed that the simplified system not only facilitated stand improvement, but also significantly recovered more value (17 % on average) at the stand scale.
This presentation aims to create awareness about the future of forestry and the need to embrace digitalization to address upcoming challenges, optimize resource management and ensure sustainable practices. By covering forestry obstacles, available resources, the people gap, service management, the role of hardwood, and with a global perspective, the audience gains insights into the potential solutions and opportunities for the future of the forest industry.
SFI’s Climate Smart Forestry Objective in the Context of Northern Hardwoods
The effects of climate change represent a major threat to the planet’s ecological, social, and economic stability; effects that are now part of our lived experiences. With increasing warming, these are likely to increase in frequency and intensity. Proposed solutions to climate change often lack clarity, face daunting real-world constraints, and sometimes entail serious risk and costs. Sustainable forest management and the products that ensue represent pointed, effective, low-risk and cost-effective tools to combat these increasing threats. Altering management to improve the forests’ capacity to capture carbon and generate these benefits are key to our national and international climate-mitigation efforts. To be successful, management actions need to be quickly adapted to avoid the worst and most impactful negative effects to forest health and productivity. Increasingly, climate adaptation research suggests that northern hardwood systems and species may be more adaptable to future climate scenarios (e.g., temperature and moisture regimes), while also being more susceptible to some of the more severe negative effects, including increased ice storms, herbivory from invasive pests, and pathogens. Further, elements of hardwood silviculture (like direct seeding) may be more adaptable to changing conditions. Applied across SFI’s 150 million hectare (370 million acre) certified footprint, climate smart forestry will help mitigate negative effects in both hardwood and softwood forests in North America. The SFI Climate Smart Forestry objective helps ensure that certified organizations are both aware of the climate risks they face, and account for them in business and forest management planning. This presentation will focus on I) the new SFI Climate Smart forestry objective requirements in the context of hardwood systems, II) the challenges operators are facing, and III) the potential practices that will lead to climate change benefits.
Incorporating climate change into strategic forest planning: A Gagetown case study using new yields and succession rules for the Acadian forest
Climate change has been identified as a major threat to forest ecosystems worldwide, with significant impacts on forest growth, mortality, and composition. To ensure the sustainability of forest resources, it is critical to incorporate these changes into strategic forest planning models. We have developed a novel method for parameterizing strategic planning models (Woodstock) using a spatially explicit individual tree-based model derived from PICUS. Our method allows to produce climate-sensitive yield curves and transition rules to project the forest inventory under several climate scenarios. We applied this approach to the Gagetown forest located in southern New Brunswick at the center of the Acadian forest biome. Our results show that climate change could lead to a deficit of 10-40% of the available volume after only 80 years without any forest harvesting activities. Balsam fir, black spruce, and trembling aspen are the three most vulnerable species in the Acadian forest, dropping in relative abundance from 56% combined to 14-8% almost entirely in favor of red maple. This approach enables us to integrate our best knowledge of the climate sensitivity of each species and assemblage into strategic forest planning models and thus provide a pathway for future climate-adaptive management plans.
How local markets shape silvicultural decisions in the field
There are many factors that affect the ability of Silviculturists to manage Northern Hardwoods including forest composition, topography, soils, and weather, but local and regional forest product markets also play a critical role in the decision-making process. The topic of this presentation is to better understand how local sawlog, bolt and pulp markets shape future stand composition and forest management outcomes. In the last two years, we have seen extreme supply/demand volatility for each of these product classes. This presentation will attempt to address how recent market forces and volatility affects forestry decision making in the field today along with long-term future implications and business economics.
Ecological Forestry and the Triad in Nova Scotia: Implications for Hardwood Management
A recent independent review of forest practices has led to several broad changes to Nova Scotia’s Forest sector. A cornerstone of the review’s recommendations is to implement ecological forestry on Crown land that prioritizes biodiversity and leverages the Triad model of functional zoning. The Triad has three zones for the forested land base. The conservation zone excludes all forestry activities and focuses on biodiversity only. The high production zone includes intensively managed softwood plantations with a focus on fibre production. The much larger and surrounding ecological matrix zone balances uneven-aged silviculture with biodiversity values. A corresponding Silvicultural Guide for the Ecological Matrix was published and is required in the ecological matrix. The guide heavily favours uneven-aged silvicultural treatments such as selection management, shelterwoods, and irregular shelterwoods with the long-term objective of ecosystem restoration. The guide’s strong emphasis on restoring long-lived, intermediate-to-tolerant species (e.g., sugar maple, yellow birch, white ash, red oak), as well as growing stock quality, has many implications for hardwood management. Opportunities and challenges for hardwood management are discussed in the context of these recent changes. This discussion is then empirically grounded with the findings of hardwood silvicultural research trials that have been conducted for over forty years. As a province in the Acadian Forest Region with a diversity of hardwood tree species and ecosystems, Nova Scotia has several opportunities for hardwood management that must be discussed in the context of both the changing sector and the changing climate.
Assessing vigor when tree marking: the importance of crown dieback
The silvicultural approaches generally used for uneven-aged northern hardwood stands mostly involve partial cuts. To facilitate the implementation of stand improvement in these cuts, several classification systems have been developed to help tree markers visually assess tree vigour based on the presence of individual defects. However, very few studies have tried to empirically validate such systems. We assessed tree vigour using repeated measurements collected as part of long-term silvicultural trials conducted in 615 permanent plots throughout the northern hardwood forest of Quebec, Canada. Our results confirmed that crown dieback is by far the best indicator of tree vigour. They also showed that the rate that vigorous trees develop defects increased with increasing diameter.
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Adaptive Silviculture for Climate Change: Early Structural and Compositional Outcomes in northern New England Northern Hardwood Forests
Climate change introduces a suite of unknowns into conditions affecting forest growth, development, and health. Forest managers are in need of strategies for retaining forest integrity in the face of climate change that are regionally relevant and can be incorporated into current silvicultural planning processes. The Adaptive Silviculture for Climate Change project (ASCC) is an international network designed to examine adaptation strategies to address these changes through operational-scale treatments based on local expertise in forest management. ASCC involves four treatments: no action, resistance, resilience, and transition, representing a gradient of silvicultural approaches with increasing emphasis on adaptation to future climate conditions. We present five-year outcomes of these treatments at the northern hardwood ASCC site with emphasis on how structural complexity and compositional diversity change along the treatment gradient. We found that notable compositional changes were apparent primarily in the young regenerating class, while canopy composition remained similar across treatments. Structural diversity varied among treatments, with each treatment exhibiting unique spatial and canopy structural patterns with important linkages to future adaptation pathways. Our results suggest that management for increased adaptive capacity has immediate outcomes that can be described by forest structure and more long-term outcomes that will be realized by changing composition of regeneration. Co Authors: Jessica Wikle1, Anthony D’Amato1, Chris Woodall2, Kevin Evans3 1 University of Vermont, Rubenstein School for Environment and Natural Resources 2 USDA Forest Service, Northern Research Station 3 Dartmouth College Woodlands
Early changes in forest structure and deer use in a 140-site northern hardwoods alternative silviculture systems study.
Inadequate stocking of desirable stems in sapling classes of northern hardwood forest in some regions of Michigan inspired a 140-site evaluation of silvicultural alternatives to current management by selection silviculture. The study’s goal is to identify combinations of silvicultural treatments that increase the diversity and density of sapling recruits over forested landscapes where deer-browsing pressure and other limiting factors are at play. Here we summarize pre-harvest and early post-harvest (1-2 years) vegetation and deer use data. Pre-harvest data bolstered justification for the research; over most of the Michigan northern hardwood resource stands remain even-aged despite 3-4 partial harvests since the 1960s, with sapling classes often old (>70 yrs, understocked with desirable species, and dominated by American beech and ironwood. Deer use, high basal area, and lack of local seed sources were related to low regeneration density and diversity. Although insufficient to predict long-term outcomes, early post-harvest regeneration (50-137 cm tall (smaller) and >137 cm tall-< 11.4 cm DBH (larger)) densities differed among species and harvest treatments relative to pre-harvest; e.g., American beech declined in smaller and larger classes, especially in the most open treatment (i.e., seed tree harvest); sugar maple and ironwood declined in the larger class but increased in the smaller class, especially when protected from deer by tree tops; pin cherry and paper birch were near absent in pre-harvest forests, with post-harvest density highest in the seed tree harvest. Deer use varied spatially and increased following harvesting, especially in more intense harvest treatments. Browsing preferences varied regionally and among species; e.g., low: American beech, balsam fir, high: yellow birch, pin cherry, elm. We anticipate the combination of early regeneration responses to treatments, and interspecific and environmental differences in growth rates and filtering by deer browsing pressure will drive future canopy composition.
The Interaction of Site and Silviculture: Lessons Learned from Long-Term Studies in the Northeast United States
Integration of site features into silvicultural decision-making has been a tenant of hardwood management for over a century. In regions like the northeast United States, site-level silviculture is especially critical for systems that rely on natural regeneration. However, the hardwood forests of the northeast are nuanced and complex. Truly matching silvicultural practices with underlying site attributes to achieve consistent outcomes in composition and structure is difficult. To further understand the relationship between site and silviculture, and the influence of their interaction on natural regeneration dynamics, we utilized long-term (20+ years) forest inventory data from three silviculture studies across the region. We will synthesize results for management recommendations in the context of ongoing and evolving forest challenges, such as the proliferation of American beech and resilience to climate change.
Adaptive silviculture to save our sugar maple – with a focus on artificial regeneration. An NHRI workshop.
Time and again researchers, foresters, and landowners have tried and failed to grow sugar maple plantations anywhere except where maple had recently thrived. Sugar maple has always had problems establishing, from predator browsing, herbaceous competition, forest cover removal and issues with frost pockets. Now, with future climate increasing disturbance regimes, increasing temperatures, and changing snow cover we question whether our sugar maple will have time to adapt. Even natural regeneration is seeing issues due to beech bark disease suckering and sprouting in maple-beech stands, causing increased competition. Here lies the problem, what can we do if both natural regeneration and artificial regeneration have failed to re-establish and grow maple stands where they were once quite successful? And is there a way to restore maple stands where clearcutting or agriculture has reduced the site quality? And finally, is it worth the cost and effort to try? The short answer is maybe. My workshop will incorporate knowledge of adaptive silviculture and hardwood regeneration and apply them to decision keys and best management practices to help landowners make real decisions on how best to save our maple resource. I’ll also update on the current ARM project with the National Tree Seed Centre, Kingsclear Provincial Tree Nursery, and AV Group where we are attempting to produce hardwoods at an operational scale for the first time in New Brunswick.
Application of irregular shelterwood systems as an approach to achieve multi-species management in temperate forests
Managing for species mixtures with contrasted ecological requirements can be highly desirable from an economic and ecological perspectives. However, they are challenging to achieve in practice. Based on the premise that a variety of ecological niches can promote a diversity of species, the application of irregular shelterwood systems (ISS) offers a good potential to achieve multi-species management in temperate mixedwood forests. This talk will first review the three main variants of irregular shelterwood systems used in North America (extended ISS, continuous cover ISS and expanding-gap ISS). Then, results from an experiment implemented in irregular spruce-fir-yellow birch forest in Québec (Canada) will be presented. This study assesses irregular shelterwood scenarios (extended and continuous cover ISS), inspired by spruce budworm (Choristoneura fumiferana)-driven natural dynamics, as alternative to clearcutting and regular shelterwood cutting. As expected, shelterwood scenarios diversified light and seedbed conditions compared to the uncut control, but only the continuous cover ISS successfully established a new cohort made of the three target species (Picea rubens, Abies balsamea and Betula alleghaniensis) after 5 years. This result is mainly explained by a lower harvest intensity (37%) that could promote spruce and fir regeneration, while maintaining hardwood and shrub competition at an acceptable level. Conifers poorly regenerated in clearcuts because of heavy competition. Overall, continuous cover ISS could achieve the best compositional and structural objectives.
Sapling based recruitment model for sugar maple-dominated stands of Quebec.
Over the last few decades, compositional changes have been observed in the sugar maple-dominated (Acer saccharum) stands of southern Quebec. American beech (Fagus grandifolia) increases its presence and abundance to the detriment of the sugar maple. Recent works have shown that the ability of the growth models currently used for forest management to predict these transitions are limited. To improve the performance of the models, a new recruitment module was developed based on the sapling cohort characteristics. The module considers the number and size of saplings from the main tree species to predict the recruitment of new merchantable size trees. The new recruitment module improves the prevision accuracy of merchantable stem recruitment, and consequently, improves the prediction of future composition for sugar ample stands.
Development of algorithms to automatically identify and spatialize all the trees in complex one-hectare 3D point cloud stands.
The development of the mobile LiDAR technology for mapping forest ecosystems is rapidly advancing and has great potential in many ways. However, to date, the use of this technology remains marginal both in conducting inventories and in research in forest ecology. This is probably due to the difficulty of translating LiDAR point clouds into usable information. While the identification and spatialization of trees is certainly one of the most important pieces of information to provide, the algorithms for this identification remain poorly performing, especially in complex structured stands. In this study, we developed a series of algorithms adapted to complex data clouds. We then used these algorithms in 10 stands (1 ha) showing a dense shrub layer. Our results show that nearly 95% of trees over 10 cm DBH are automatically identified by our algorithms; a fast visual inspection subsequently allows us to identify missed trees. Our algorithms also allow us to identify trees less than 10 cm in DBH, but some of these may have been missed by the LiDAR due to the obstruction created by the foliage. These algorithms, along with the extremely accurate algorithm developed for estimating DBH (Nolet et al, under revision), represent an important step in deploying the mobile LiDAR technology on a larger scale.
Evaluating the efficacy of high-stumping as a mechanical treatment to control ironwood (Ostrya virginiana)
Ironwood (Ostrya virginiana) is becoming increasingly common in the midstory and understory of northern hardwood forests in Wisconsin, particularly in degraded stands and areas subject to significant deer browse. The shade and competition caused by dense layers of ironwood saplings interfere with regeneration of other valuable northern hardwood species. Wisconsin Department of Natural Resources is testing a non-chemical method of ironwood control in northern and southern Wisconsin. High-stumping is a non-chemical control method for ironwood where stems are cut above a standard stump height to increase stress on the plant and reduce vigorous stump resprouting. This study cut ironwood during the growing season at several stump heights (30cm, 60cm and 91cm) and varied diameters to monitor sprouting and longevity of treated trees. Ironwood stumps have so far been monitored for three years after treatment. Preliminary results indicate that overall mortality was low (Median = 15.5%; Range = 1% - 36%) in the first year after treatment. However, overall mortality increased significantly in the second year post-treatment (Median = 23.5%, Range = 3% - 40%) and again in the third year of post-treatment monitoring (Median = 78.5%; Range = 22% - 95%). High-stumping may be a promising, viable non-chemical means of ironwood control in the understory of northern hardwood stands; offering an option on lands where chemical control methods are not preferred or allowed.
Seeing the Forests through the Deer: A Regional Assessment of White-tailed Deer Browsing Preferences and the Impact on Forest Regeneration
As the widest ranging and most populous mammalian herbivore in North America, white-tailed deer (Odocoileus virginianus; hereafter deer) and their browsing impacts have been of interest to natural resources professionals for nearly a century. Despite the myriad of research projects devoted specifically to deer browsing on forests, most of these studies are spatially and temporally limited. Any landscape-level impacts tend to be inferred from syntheses of many localized studies that often represent a snapshot in time of browsing. The spatial and temporal limitations of such collections of local studies represents a real management challenge because they fail to adequately capture the inherent heterogeneity and interdependence in forest understory plant communities and deer densities within and among forest stands and types. In Wisconsin, a unique empirical dataset is being built that spans the entire forested area of the state (46%; ca. 6,500,000 ha) and will continue to grow in the long-term as sample sites are re-visited and new sites are added to the program. The Forest Regeneration Metric (FRM) is a monitoring tool used to quickly assess seedling and sapling regeneration and browsing severity on a three-year rotation from post-harvest until stems exceed the reach of deer. Additionally, the Big Data Mapping & Analytics Platform (BIGMAP) is a new tool developed by the US Forest Service Forest Inventory & Analysis (FIA)program, which combines remotely sensed data and ancillary ecological attributes with field-measured plot data to produce wall-to-wall, fine scale maps of woody understory composition and abundance. For our study, we are integrating preference data (i.e., FRM) with BIGMAP seedling and sapling data layers to develop a regional-scale map of deer browsing preferences for Wisconsin. Our goal is to map tree species risk by ecological landscape according to their preference values to get a better understanding of the spatial variability of browsing pressure. Preliminary results from this ongoing study indicate a high degree of variability among preferred species and ecological landscapes. The most preferred tree species in northern hardwoods forests of Wisconsin was different across all ecological landscapes. For example, deer preferred bigtooth aspen (Populus grandidentata) in the Northern Highlands and yellow birch (Betula alleghaniensus) in the Western Coulees and Ridges, while in the Northeast Sands and North Central Forest ecological landscapes deer most preferred white oak (Quercus alba) and swamp white oak (Quercus bicolor), respectively. As one example of our proposed risk assessment we also found that the white oak species listed above are thus at highest risk of over-browsing by deer across 24% of those two ecological landscapes and ca. 4% of the entire forested landscape of Wisconsin. Contributors: 1Amanda M. McGraw, 2Deahn DonnerWright, 3Alex Royo, 4Emilie Champagne, 2John Hak, 1Teresa Pearson, 1Meg Sanders 1 Wisconsin Dept. of Natural Resources, Division of Forestry, Rhinelander, WI 2 US Forest Service, Northern Research Station, Rhinelander, WI 3 US Forest Service, Northern Research Station, Irvine, PA 4 Direction de la recherche forestière, Ministère des Ressources naturelles et des Forêts, Québec, Qc, Canada
The influence of winter aggregations of moose on browsing in the Acadian Forest
Moose population density in northwestern New Brunswick is the highest in the province, and moose browsing damage have been detected. In this study, we assessed the influence of the number of moose estimated during winter at the landscape scale on browsing of both commercial and non-commercial tree. Mean number of moose estimated during winter in a 3 km radius buffer is associated with both a greater occurrence and a higher intensity of moose browsing on the regeneration stratum. We recommend avoiding the aggregation of cutblocks to decrease attraction by moose during winter, and thus decreasing browsing pressure both locally and in the surrounding landscape.
Establishing the future forest through collaborative research and management: DREAM
Forested assisted migration (AM) is a climate-adaptation strategy entailing the deliberate movement of individuals or genetic material from native source populations to locations either within or beyond their current ranges. Managers use this strategy to establish forests today that can thrive and sustain goods and services in expected future climate conditions. Although several AM trials are underway, implementing AM operationally is limited by major knowledge gaps and decision support tools. These shortcomings represent a critical problem because establishment of potentially maladapted selections and/or inappropriate silvicultural strategies creates major risk to management timeframes and financial resources. The Desired Regeneration through Assisted Migration (DREAM) project is an international collaboration of research and managers that seeks to specifically address these knowledge gaps and necessary tools to successfully plan and execute FAM plantings. DREAM experiments are underway in northern hardwood and temperate forests of Wisconsin and Quebec.
Strategies for Managing Compositionally Degraded Mixedwood Stands
Many forests of the northern U.S. and southern Canada consist of northern hardwood (deciduous) and softwood (coniferous) species in mixture, i.e., temperate mixedwoods. In some cases, these compositions result from site and natural disturbance regime, while others result from past land use such as agriculture or repeated harvesting. Where harvesting occurred without sufficient attention to residual stand condition, component species may be lost or diminished. Stands which have been degraded in this way may be less likely to provide the benefits desired from species mixtures, e.g., reduced susceptibility to insects and diseases, wildlife habitat diversity, and increased market flexibility, carbon sequestration, and climate resiliency. Strategies for managing compositionally degraded mixedwoods, include identifying limiting species and complicating factors, maintaining seed sources, manipulating regeneration substrate and microclimate, and controlling merchantable and submerchantable competition. With thoughtful management, northern hardwood and softwood mixtures can be maintained for both production and ecological outcomes. Co-authors: John Kabrick (U.S. Forest Service), Patricia Raymond (Quebec Ministry of Forests, Wildlife, and Parks), Benjamin Knapp (University of Missouri), Lance Vickers (University of Kentucky), Nicole Rogers (University of Maine), and Christel Kern (U.S. Forest Service).
Predicting log grade volumes in sugar maple and yellow birch trees in Quebec’s hardwood stands
Models were developed for sugar maple (Acer saccharum Marshall) and yellow birch (Betula alleghaniensis Britton) to estimate log grade occurrence and volume in northern hardwood stands in southern Quebec, Canada. For each species, we used data from more than 2,000 trees that had been harvested and bucked into logs at 30 sites across Quebec’s hardwood forests since the early 2000s. Separate models were developed for each species by adding site predictors, such as climate and ecological variables, to tree-level variables, such as tree diameter at breast height and tree quality class. For both species, the best results were obtained by adding the ecological region as an explanatory variable. For sugar maple, the observed proportion of sawlog volumes in the ecological regions of the balsam fir–yellow birch bioclimatic domain was significantly lower than in the sugar maple–yellow birch bioclimatic domain (i.e., Quebec’s southernmost regions for hardwood stands). For yellow birch, sawlog volume was variable among ecological regions, although lower values were observed in eastern Quebec. Our results suggest that site and growth conditions should be considered when assessing potential products for hardwoods.
TransX – A new network of provenance trials across eastern Canada and the US to test the warming vulnerability of northeastern tree species and their assisted migration potential.
The Transborder climate gradient experiment is a network of 12+ tree common gardens (provenance trials) ranging from North Carolina to Quebec, where we will plant young trees composed of carefully selected natural and improved genotypes of key northeastern tree species including sugar maple, red maple, yellow birch, white birch and northern red oak. The main focus of TransX is on the response of trees to future warming, focusing on leaf and growth phenology, health and survival across species and populations. We have two specific objectives: 1) move local species and populations south to evaluate their response to warmer temperatures, and 2) move southern populations north to assess their potential for assisted migration.
Tree selection based on the financial maturity of northern hardwoods
Northern hardwood forests are managed to achieve a variety of objectives, including generating revenue by harvesting trees and creating conditions for future value growth by retaining other trees. Decision about tree selection for harvesting and retention are typically guided by parameters such as residual basal area, q-ratio, and maximum diameter. Whereas residual basal area and q-ratio are biological concepts related to the stocking level of forests, maximum diameter is an inherently economic concept that identifies the point of financial maturity. Previous assessments of maximum diameter of northern hardwoods focus on the rate at which trees increase in value due to growth and product development, but few also considered the risk of a tree declining, decaying, or dying between harvests. By considering the rate that trees increase in value as well as the risk of retaining trees between harvests, our analysis of long-term datasets provides a new operational perspective on maximum diameter, and therefore financial maturity, among northern hardwoods.
Hedging bets against change: silvicultural alternatives for managing the adaptive capacity of northern hardwood forests
Changes in the global climate, increases in ungulate densities, and invasive species all interact to threaten the ability of northern hardwood forest ecosystems to continue to provide desirable ecosystem functions and services. Silvicultural approaches that increase species, structural, and functional diversity allow managers to address these concerns by hedging their bets against these threats. Here I will synthesize lessons learned from the Northern Hardwood Silviculture Experiment for Enhancing Diversity (NH SEED) – an experiment designed to identify processes limiting species diversity using a range of nested overstory and understory manipulations. Additionally, I will describe ongoing work on functional traits, and linking functional diversity to carbon dynamics in one of the longest-running silvicultural trials at the Dukes Experimental Forest. Finally, I will introduce Adaptive Capacity Through Silviculture (ACTS), a new network of experiments designed to test alternative approaches to climate change adaptation in northern hardwoods of the northeastern US and Lake States. Together these studies highlight a range of options for managing vulnerabilities at multiple scales. Authors: Julia I. Burton, Claudia Bartlick, Yvette L. Dickinson, John E. Drake, Garrett R. Evans, Robert Froese, René H. Germain, Stefan F. Hupperts, Maria Janowiak, Mickey Jarvi, Christel C. Kern, Carsten Külheim, Keenan Rivers, Christopher R. Webster, Andrew L. Vander Yacht
Natural and artificial regeneration in northern hardwood stands in relation to harvest, browsing, and competition.
To this day among northern hardwood stands of Quebec, Canada, natural regeneration has typically been the main way of renewing forest stands following partial harvest. However, important challenges will affect these stands in the near future, given that the main target tree, sugar maple, does not regenerate as easily as it did in the past. This is likely a multifactorial phenomenon: increasing presence of American beech in the understory, high levels of deer browsing, decreasing soil fertility, etc. In parallel, climate change and other global shifts (e.g. invasive species) might lead to resilience issues that will require a higher diversity of regenerating species, potentially through enrichment planting. We will present results from both experimental studies and operational-scale data in order to discuss the current state and potential future of the regeneration of hardwood forests.
Improving hardwood bucking techniques in cut-to-length harvesting operations in Acadian forests of New Brunswick
One of the most complex working steps during harvesting operations is bucking. It is particularly demanding in trees with complex architecture, which is often the case with hardwoods. As bucking is crucial for generating products and highly influences the value yield, astute bucking decisions are essential to reach an efficient use of the wood resource, while ensuring profitable operations. To make informed decisions, a comprehensive knowledge of factors influencing product recovery of hardwoods is mandatory. Therefore, a characterization of Acadian forests in New Brunswick has been done based on tree inventories made between 2012 and 2021. More than 250,000 trees were analyzed for this purpose. Variables considered were tree species, DBH, tree height, form and risk classes as well as different plot-related variables, a stand density index or whether the plot was dominated by hardwoods or softwoods. The characterization was based on ANOVAs and multinomial logistic regressions. In a second characterization step, attributes influencing product recovery were analyzed for tree, plot, and site attributes. These analyses were done using factor analysis of mixed data (FAMD). Having characterized the Acadian forests of New Brunswick and knowing which factors drive the product recovery in hardwoods, an evaluation of actual bucking performed in the province was conducted. Pre-harvest inventories were linked to tree-dependent product measurements performed after harvest in order to evaluate the product basket. First results of the bucking evaluation will be presented to formulate enhanced bucking solutions, based on an increase of monetary value at the tree level, while maintaining a satisfactory harvesting productivity. The evaluation of bucking is conducted through the reconstruction of stems and the use of a bucking optimizer.