Adaptation of Silvicultural Practices to Climate Change

In 2023, the Direction de la recherche forestière (Forest Research Branch) of the Ministère des Ressources naturelles et des Forêts du Québec (Quebec’s Ministry of Natural Resources and Forests) began testing silviculture adaptation strategies in three regions of Quebec to address an increasing risk of drought, longer growing season, increasing average temperatures, more freeze-thaw events, and changes to peak-flows throughout Quebec’s forestry sector. Quebec’s forest is considered an important ecosystem for its economic impact in the province and because it provides habitat for many animal species. Quebec is divided into two big climatic zones: temperate, which includes mixed and broadleaf trees, and a boreal zone mainly composed of black spruce, jack pine and balsam fir. Most of Quebec’s land is Crown land (91%) which is publicly owned. It also forms a significant industrial sector, providing roughly 60,000 jobs, half of which are in the wood products sector, and one third in the paper industry. With funding through the Government of Quebec’s Plan pour une économie verte 2030, the Direction de la recherche forestière launched three projects that follows the Resistance, Resilience, Transition framework commonly used in forestry adaptation work. The Resistance Project, focused in the Outaouais region, aims to enhance the resistance of white spruce and jack pine plantations to water stress in the context of climate change. The Resilience Project (Chibougamau region) investigates the use of mixed-species plantations to reduce the risk of losing silvicultural investments in high-fire-risk regions of the Boreal Forest. Finally, the Transition Project (Gaspésie region) explores the management of tree species composition through enrichment planting and mixed species planting via assisted migration following partial harvests. Silviculture is the art and science of controlling the establishment, growth, composition, health, and quality of forest and woodlands to meet the diverse needs and values of landowners and society on a sustainable basis. The forestry sector is recognized as a mitigation actor through its contribution to carbon sequestration in forest ecosystems, in wood products, and by using wood products to replace products with a higher carbon footprint. The forestry sector’s ability to contribute to mitigation will be impacted by climate change itself. Therefore, there is an urgent need to adapt forestry practices that will ensure consistency with mitigation measures being implemented. Without adaptation, mitigation measures will not succeed as they are interconnected. Results of this work will help to orient the types of silvicultural interventions used in practice that are related to characteristics of the forest and will contribute to ensuring its sustainability for the benefit of all Quebecers.

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Understanding and Assessing Impacts

Climate change impacts on the forest ecosystem are diverse, and Quebec is already observing changes in the form of rising temperatures that are affecting the distribution and health of tree species, increased rainfall leading to soil erosion and flooding, droughts causing stress and damage to trees, more frequent and severe forest fires due to prolonged dry periods, and more frequent freeze-thaw events. The Outaouais region which contains parts of the Boreal Forest, for example, has experienced more drought events in the spring, and in the fall, leading to an increased risk of wildfires. To identify climate risks to each region, an expert team from the Ministère des Ressources naturelles et des Forêts du Québec conducted a vulnerability assessment, which combined climate data models and habitat models, and was supported by a literature review. In collaboration with Ouranos, the team used data from Climate Portraits – a regional portal of climate-related information that offers spatialized information across Quebec to visualize climate normals, historic observations and the changes projected by climate models. The portal uses Climate Model Intercomparison Project Phase 5 and Phase 6 (CMIP5/CMIP6) simulations for the 2050 time period, under Representative Concentration Pathways (RCP 4.5 and RCP 8.5) scenarios.

The results of the vulnerability assessment showed that for the 2050 time period, there may be an increased risk of drought, longer growing season, increased average temperature, more freeze-thaw events and an increase in peak-flows. These changes can impact forest productivity, stand composition, area burned by wildfires, the frequency of regeneration failures, the duration and severity of insect infestations, the emergence and spread of invasive exotic species, and land access (integrity of infrastructure and multi-purpose roads). Maximum temperatures are expected to increase, while precipitation will likely remain the same. The expected increase in the number of heat waves will have a significant effect on water and tree species. Even modest climate change is expected to lead to major transitions in Boreal forests, for example.

Identifying Actions

The research program involves collaboration with various partners and stakeholders (University of Montreal, Université du Québec à Chicoutimi, Université du Québec à Rimouski, Université du Québec en Abitibi-Témiscamingue, and Quebec’s Ministry of Natural Resources and Forests) and is guided by the principles of enhancing forest resilience, managing climate risks, and adapting silviculture practices to the changing environment. The project follows the Resistance, Resilience, Transition framework that is used in forestry adaptation work. It is essentially a portfolio of adaptation options forest managers can use to maintain management goals, specifically to favour ecosystem persistence and to manage change. Resistance refers to increasing the ecosystems defenses against change to keep the ecosystem intact and to defend the ecosystem from disturbances, or to give more time for the ecosystem to adapt. Resilience is the capacity of the ecosystem to tolerate disturbance and return to a similar state. Transition is an adaptation option, which is aimed at facilitating the modification of the ecosystem by manipulating specific composition to better adapt the ecosystem to the new climate. This option aims to decrease the time it takes for natural transition to occur and to stabilize the industry’s economic structure by securing the supply of selective species in a specific region. The planning time horizon goes from short (Resistance) to long (Transition). Based on this framework, the researchers decided to tailor the research project with those options in Phase 1 of the research project on adaptation of silviculture at Quebec’s Ministry of Natural Resources and Forests. In 2020, workshops were held in three pilot regions to assess risks associated with climate change, including Gaspésie (Iles de la Madeleine), Nord-du-Québec and Outaouais. The workshops brought researchers together from the Ministry’s research branch, forestry professionals from various ministry directions in Québec city and forestry professionals located in each pilot region. Each workshop began with a presentation from the researchers and the forestry professionals from Quebec regions on the various risks associated with climate change. Then, the forestry professionals from the pilot regions provided a portrait of their silviculture scenarios currently in use in their regions. Finally, a discussion with all the participants was done to see what silviculture scenarios were at risk and what were the options to cope with climate change. The outcome of those workshops is the research program that was in place in 2022.

Implementation

Using the results of the vulnerability assessment and stakeholder workshops, the research team designed a research program for each of the three regions and will test one adaptation option per region. The first initiative focuses on enhancing “Resistance” in the Outaouais region, situated near Ottawa. This project revolves around the implementation of commercial thinning practices aimed at bolstering water stress resilience in forest plantations, especially in the context of climate change. The primary objective is to assess the effectiveness of various thinning intensities in mitigating water stress among plantation trees facing drought conditions. In 2023, Jack Pine will be the subject of investigation. In 2024, White Spruce will be included, along with the installation of various measuring instruments to facilitate comprehensive analysis. Notably, White Spruce is the primary tree species planted in Quebec, and this project represents a significant step in genetic enhancement research. The preference for White Spruce research is due to the limited genetic work conducted with Jack Pine, primarily because the planting of Jack Pine in the boreal forest, where growth rates are comparatively slower, has been less common.

The second project, known as the “Resilience” initiative, is situated near Chibougamau within the expansive Boreal Forest, located in the northern reaches of the province. This undertaking delves into the concept of employing mixed-species plantations as a strategic measure to reduce the likelihood of losing silvicultural investments, particularly in regions with elevated fire risk. Led by a dedicated doctoral student from Italy, this project has already commenced, with all experimental sites having undergone harvesting in 2022. Initially, there was a desire to conduct experiments in former wildfire-affected areas, but these locations were not readily available. However, the opportunity presented itself when the forests experienced wildfires in the summer of 2023. Considering this, the decision was made to carry out the experiment in these recently burned sites. Anticipations for the first year include an outwash of nutrients into the soil, and the research will investigate the physiological responses of both tree species involved. The experiment will test the combination of Jack Pine and Black Spruce, alongside Tamarack, a tree species known for its rapid growth. Interestingly, the wildfires have inadvertently benefited this experiment, shedding light on the forest’s regenerative abilities. While prescribed burning is not a common practice, particularly in Quebec, it is more recommended in Sweden.

The third project, based in Gaspésie, is set to focus on the critical theme of “Transition.” It will address the management of tree species composition in both plantations and natural stands by employing enrichment planting and mixed species planting strategies. These approaches, carried out in the context of assisted migration, will follow partial harvests. This multifaceted project encompasses three distinct experiments. The first experiment is centered around the facilitated migration of Red Oak, with an emphasis on rigorously testing various seed sources. Implementation is scheduled for 2025, and this endeavor is conducted in close collaboration with the Cégep de Sainte-Foy, underscoring its academic and practical significance. A grant application through the Natural Sciences and Engineering Research Council of Canada (NSERC) has also been initiated to support this initiative. The second experiment of the project pertains to enrichment planting. It involves introducing a carefully selected range of three to four broadleaf species and five conifer species into the designated sites. Concurrently, mixed-species planting will be undertaken, although the specific species to be included will be determined at a later stage. Site preparation is set to commence in 2024, with plantation activities scheduled for 2025. This dynamic approach will provide valuable insights into how forest ecosystems respond to increased species diversity. The third experiment in this project revolves around testing mixed species following clear-cutting, encompassing broadleaf and conifer species. This testing initiative aims to validate models predicting the northward migration of species in response to changing climate conditions. The project seeks to bridge the gap between theoretical models and real-world results, thereby contributing to a deeper understanding of forest ecosystem dynamics in the face of climate change.

Outcomes and Monitoring Progress

This project received funding through the “Plan pour une économie verte 2030” by the Government of Quebec until 2027, with the expectation of fund renewal thereafter. The three projects received a combined total of $2.5 million over five years. The funding played a significant role in the design of the project. Without it, the scale of the projects would have been smaller and sought funding from other sources.

Next Steps

The project lead intends to eventually expand the projects to other regions of Quebec. Phase 2 will focus on implementation.

The project team is currently developing a separate project proposal that will focus on managing the borders of towns for fire breaks, especially considering recent wildfire events. Various experiments in different towns are planned that test hybrid Poplars as an alternative to clear-cutting to protect existing ecosystems.

The next steps involve planning for planting next year and establishing a long-term monitoring plan that extends for over two decades. This extensive monitoring will provide valuable insights into the project’s long-term outcomes and the forest’s response to mixed-species plantations in fire-prone areas.

Resources

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