Yan Boulanger, Jesus Pascual Puigdevall, Annie Claude Bélisle, Yves Bergeron, Marie-Hélène Brice, Dominic Cyr, Louis De Grandpré, Daniel Fortin, Sylvie Gauthier, Pierre Grondin, Guillemette Labadie, Mathieu Leblond, Maryse Marchand, Tadeusz Bartek Splawinski, Martin-Hugues St-Laurent, Évelyne Thiffault, Junior Tremblay, Stephen Yamasaki. A regional integrated assessment of the impacts of climate change and of the potential adaptation avenues for Quebec’s forests. 2023. Can. J. For. Res. Online first
DOI : 10.1139/cjfr-2022-0282
Regional analyses assessing the vulnerabilities of forest ecosystems and the forest sector to climate change are key to consider the heterogeneity of climate change impacts but also the fact that risks, opportunities and adaptation capacities might differ regionally. Here we provide the Regional Integrated Assessment of climate change on Quebec’s forests, a work that involved several research teams and that focused on climate change impacts on Quebec’s commercial forests and on potential adaptation solutions. Our work showed that climate change will alter several ecological processes within Quebec’s forests. These changes will result in important modifications in forest landscapes. Harvest will cumulate with climate change effects to further alter future forest landscapes which will also have consequences on wildlife habitat (including woodland caribou habitat), avian biodiversity, carbon budget and a variety of forest landscape values for Indigenous peoples. The adaptation of the forest sector, will be crucial to mitigate the impacts of climate change on forest ecosystem goods and services and improve their resilience. Moving forward, a broad range of adaptation measures, notably through reducing harvest levels, should be explored to help strike a balance among social, ecological and economic values. We conclude that without climate adaptation strong negative economical and ecological impacts will likely affect Quebec’s forests.
Raphaël Chavardes, Lorena Balducci, Yves Bergeron, Véronique Poirier, Pierre Grondin, Hubert Morin, Fabio Gennaretti. Greater tree species diversity and lower intraspecific
competition attenuate impacts from temperature
increases and insect epidemics in boreal forests of
western Quebec, Canada. 2022. Can. J. For. Res. 53(12):48-59
DOI : 10.1139/cjfr-2022-0114
We investigated how the surrounding environment influences the growth of dominant trees and their responses to temperature and insect epidemics in boreal forests of eastern Canada. We focused on 82 black spruce and jack pine focal trees in stands spanning a double gradient of species diversity and soil texture within a 36 km2 area of western Québec. For these trees, we compared their diameter at breast height, growth rates, temperature-growth relations, and growth during insect defoliator epidemics. We used linear models to study how surrounding tree attributes and soil properties affected the growth of focal trees. Models showed that tree growth responses and responses to temperature and insect epidemics were generally negative with higher intraspecific competition and positive with greater tree species diversity. Growth of both species benefitted from lower soil sand content. Our research offers novel insights on the potential role of the surrounding environment, notably tree competition and species diversity, in mitigating the vulnerability of eastern Canada’s boreal trees to anthropogenic climate change and insect epidemics.
Fougère Augustin, Martin-Philippe Girardin, Aurélie Terrier, Pierre Grondin, Marie-Claude Lambert, Alain Leduc, Yves Bergeron. Projected changes in fire activity and severity feedback in the spruce–Feather moss forest of western Quebec, Canada. 2022. Trees, Forests and People 8:100229
DOI : 10.1016/j.tfp.2022.100229
As a result of extreme weather conditions associated with anthropogenic climate change, fire regimes are expected to continue to change in the boreal forest over the 21st century and beyond. Consequently, changes in ecological attributes like stand composition, tree density and forest carbon stock can be expected. In the present study, we used an adjusted version of the CanFIRE model to project long-term (1971–2100) changes in burn rates, fire severity and fire-induced shifts in vegetation composition in response to anticipated scenarios of climate change, in the black spruce-feather moss subdomain of Western Quebec. The model provides decadal-scale estimates of the immediate physical effects of fire on forest communities by computing expected fire behavior and the resulting ecological effects. Changes in species composition of the forest is also computed based on mechanisms of succession in natural forest communities and fire-mediated vegetation transitions. Projections suggest an increase in potential burn rates across the study area under future weather conditions and also an overall reduction in percent tree mortality and total fuel consumption. This reduction is caused by negative feedback from vegetation composition that shifts to less-fire prone states. Although common forest communities will remain the same in the studied subdomain until 2100 (recurrence dynamics), significant losses of productive area (LPA) are projected, particularly in forest management units rich in forest communities dominated by black spruce or jack pine, as a result of regeneration failure due to very short intervals between successive fires. While remaining similar under moderate (RCP4.5) and high-end (RCP8.5) warming scenarios in all forest management units, LPA will vary from 25 to 36% of the percent cover by 2100 compared to 1970. These results provide insights to policy makers and land managers, and they attract attention to the pressing need to adjust management practices in the context of climate change.
Raphaël Chavardes, Fabio Gennaretti, Xavier Cavard, Pierre Grondin, Hubert Morin, Yves Bergeron. Role of Mixed-Species Stands in Attenuating the Vulnerability of Boreal Forests to Climate Change and Insect Epidemics. 2021. Frontiers in Plant Science 12:658880
DOI : 10.3389/fpls.2021.658880
We investigated whether stand species mixture can attenuate the vulnerability of eastern Canada’s boreal forests to climate change and insect epidemics. For this, we focused on two dominant boreal species, black spruce [Picea mariana (Mill.) BSP] and trembling aspen (Populus tremuloides Michx.), in stands dominated by black spruce or trembling aspen (“pure stands”), and mixed stands (M) composed of both species within a 36 km2 study area in the Nord-du-Québec region. For each species in each stand composition type, we tested climate-growth relations and assessed the impacts on growth by recorded insect epidemics of a black spruce defoliator, the spruce budworm (SBW) [Choristoneura fumiferana (Clem.)], and a trembling aspen defoliator, the forest tent caterpillar (FTC; Malacosoma disstria Hübn.). We implemented linear models in a Bayesian framework to explain baseline and long-term trends in tree growth for each species according to stand composition type and to differentiate the influences of climate and insect epidemics on tree growth. Overall, we found climate vulnerability was lower for black spruce in mixed stands than in pure stands, while trembling aspen was less sensitive to climate than spruce, and aspen did not present differences in responses based on stand mixture. We did not find any reduction of vulnerability for mixed stands to insect epidemics in the host species, but the non-host species in mixed stands could respond positively to epidemics affecting the host species, thus contributing to stabilize ecosystem-scale growth over time. Our findings partially support boreal forest management strategies including stand species mixture to foster forests that are resilient to climate change and insect epidemics.
Maxence Martin, Pierre Grondin, Marie-Claude Lambert, Yves Bergeron, Hubert Morin. Compared to Wildfire, Management Practices Reduced Old-Growth Forest Diversity and Functionality in Primary Boreal Landscapes of Eastern Canada. 2021. Frontiers in forests and global change 4:15
DOI : 10.3389/ffgc.2021.639397
Large primary forest residuals can still be found in boreal landscapes. Their areas are however shrinking rapidly due to anthropogenic activities, in particular industrial-scale forestry. The impacts of logging activities on primary boreal forests may also strongly differ from those of wildfires, the dominant stand-replacing natural disturbance in these forests. Since industrial-scale forestry is driven by economic motives, there is a risk that stands of higher economic value will be primarily harvested, thus threatening habitats, and functions related to these forests. Hence, the objective of this study was to identify the main attributes differentiating burned and logged stands prior to disturbance in boreal forests. The study territory lies in the coniferous and closed-canopy boreal forest in Québec, Canada, where industrial-scale logging and wildfire are the two main stand-replacing disturbances. Based on Québec government inventories of primary forests, we identified 427 transects containing about 5.5 circular field plots/transect that were burned or logged shortly after being surveyed, between 1985 and 2016. Comparative analysis of the main structural and environmental attributes of these transects highlighted the strong divergence in the impact of fire and harvesting on primary boreal forests. Overall, logging activities mainly harvested forests with the highest economic value, while most burned stands were low to moderately productive or recently disturbed. These results raise concerns about the resistance and resilience of remnant primary forests within managed areas, particularly in a context of disturbance amplification due to climate change. Moreover, the majority of the stands studied were old-growth forests, characterized by a high ecological value but also highly threatened by anthropogenic disturbances. A loss in the diversity and functionality of primary forests, and particularly the old-growth forests, therefore adds to the current issues related to these ecosystems. Since 2013, the study area is under ecosystem-based management, which implies that there have been marked changes in forestry practices. Complementary research will be necessary to assess the capacity of ecosystem-based management to address the challenges identified in our study.
Gabriel Magnan, Eloïse LeStum-Boivin, Pierre Grondin, Maxime Asselin, Michelle Garneau, Yves Bergeron, Martin Lavoie. Comprendre l'évolution des tourbières de la pessière à mousses de l'Ouest. 2020. Avis de recherche forestière no 150.
Les tourbières abondent dans le sous-domaine bioclimatique de la pessière à mousses de l’Ouest et certaines d’entre elles sont recouvertes de forêts productives justifiant une récolte de matière ligneuse. Les études paléoécologiques révèlent que l’évolution millénaire de cet écosystème est issue d’interactions complexes entre les feux, la topographie et le climat. Dans le contexte des changements climatiques, il est probable que les tourbières s’assècheront et seront colonisées davantage par les conifères. Elles pourraient donc devenir plus vulnérables aux feux, et ainsi transformer ces grands réservoirs de carbone en une importante source de gaz à effet de serre. Ces nouvelles connaissances permettront d’améliorer les pratiques sylvicoles, notamment en considérant la fonction de séquestration de carbone dans ces milieux.
Julie C. Aleman, Andy Hennebelle, Yves Bergeron, Adam Ali, Christopher Carcaillet, Josianne Landry, Olivier Blarquez, Pierre Grondin. The reconstruction of burned area
and fire severity using charcoal
from boreal lake sediments. 2020. Holocene 30(10):1400-1409
DOI : 10.1177/0959683620932979
Although lacustrine sedimentary charcoal has long been used to infer paleofires, their quantitative reconstructions require improvements of the calibration of their links with fire regimes (i.e. occurrence, area, and severity) and the taphonomic processes that affect charcoal particles between the production and the deposition in lake sediments. Charcoal particles >150?µm were monitored yearly from 2011 to 2016 using traps submerged in seven head lakes situated in flat-to-rolling boreal forest landscapes in eastern Canada. The burned area was measured, and the above-ground fire severity was assessed using the differentiated normalized burn ratio (dNBR) index, derived from LANDSAT images, and measurements taken within zones radiating 3, 15, and 30?km from the lakes. In order to evaluate potential lag effects in the charcoal record, fire metrics were assessed for the year of recorded charcoal recording (lag 0) and up to 5?years before charcoal deposition (lag 5). A total of 92 variables were generated and sorted using a Random Forest-based methodology. The most explanatory variables for annual charcoal particle presence, expressed as the median surface area, were selected. Results show that, temporally, sedimentary charcoal accurately recorded fire events without a temporal lag; spatially, fires were recorded up to 30?km from the lakes. Selected variables highlighted the importance of burned area and fire severity in explaining lacustrine charcoal. The charcoal influx was thus driven by fire area and severity during the production process. The dispersion process of particles resulted mostly of wind transportation within the regional (<30?km) source area. Overall, charcoal median surface area represents a reliable proxy for reconstructing past burned areas and fire severities.
Julien Beguin, Benjamin Andrieux, Yves Bergeron, David Paré, Pierre Grondin. Boreal-forest soil chemistry drives soil organic carbon bioreactivity along a 314-year fire chronosequence 2020. SOIL 6:195-213
DOI : 10.5194/soil-6-195-2020
Following a wildfire, organic carbon (C) accumulates in boreal-forest soils. The long-term patterns of accumulation as well as the mechanisms responsible for continuous soil C stabilization or sequestration are poorly known. We evaluated post-fire C stock changes in functional reservoirs (bioreactive and recalcitrant) using the proportion of C mineralized in CO2 by microbes in a long-term lab incubation, as well as the proportion of C resistant to acid hydrolysis. We found that all soil C pools increased linearly with the time since fire. The bioreactive and acid-insoluble soil C pools increased at a rate of 0.02 and 0.12?MgC?ha?1?yr?1, respectively, and their proportions relative to total soil C stock remained constant with the time since fire (8?% and 46?%, respectively). We quantified direct and indirect causal relationships among variables and C bioreactivity to disentangle the relative contribution of climate, moss dominance, soil particle size distribution and soil chemical properties (pH, exchangeable manganese and aluminum, and metal oxides) to the variation structure of in vitro soil C bioreactivity. Our analyses showed that the chemical properties of podzolic soils that characterize the study area were the best predictors of soil C bioreactivity. For the O layer, pH and exchangeable manganese were the most important (model-averaged estimator for both of 0.34) factors directly related to soil organic C bioreactivity, followed by the time since fire (0.24), moss dominance (0.08), and climate and texture (0 for both). For the mineral soil, exchangeable aluminum was the most important factor (model-averaged estimator of ?0.32), followed by metal oxide (?0.27), pH (?0.25), the time since fire (0.05), climate and texture (?0 for both). Of the four climate factors examined in this study (i.e., mean annual temperature, growing degree-days above 5??C, mean annual precipitation and water balance) only those related to water availability – and not to temperature – had an indirect effect (O layer) or a marginal indirect effect (mineral soil) on soil C bioreactivity. Given that predictions of the impact of climate change on soil C balance are strongly linked to the size and the bioreactivity of soil C pools, our study stresses the need to include the direct effects of soil chemistry and the indirect effects of climate and soil texture on soil organic matter decomposition in Earth system models to forecast the response of boreal soils to global warming.
Gabriel Magnan, Eloïse LeStum-Boivin, Michelle Garneau, Yves Bergeron, Pierre Grondin. Long-Term Carbon Sequestration
in Boreal Forested Peatlands
in Eastern Canada 2020. Ecosystems
DOI : 10.1007/s10021-020-00483-x
Forested peatlands are widespread in the boreal landscape, but their role as carbon (C) pools remains poorly documented. In this study, we investigated the long-term C sequestration function of boreal forested bogs in relation to fires in eastern Canada. Results show that the forested peatlands comprise substantial peat C mass reaching values similar to open peatlands. At the six studied peatland sites, the amount of C stored in peat (62–172 kg C m?2) exceeds substantially the aboveground tree biomass C (1.5–5.3 kg C m?2). The C locked up in live conifers on the peatlands corresponds only to a small fraction of the C stored in peat (1–6%). In comparison, the shallow organic layer (??30 cm) in the adjacent paludifying stands store 10.8 kg C m?2 on average, which is about twice as much C as the live conifers. Long-term apparent C accumulation rates are relatively low in the studied forested bogs (mean: 15.9 g C m?2 y?1), suggesting that these ecosystems have lower C sequestration potential than non-forested bogs over millennia. The charcoal data suggest that past local fires reduced C sequestration rates, but these peatlands burn much less frequently than upland forests and are thus more efficient long-term C stores. This study highlights the importance of boreal forested peatlands as C reservoirs and helps understanding how fires, logging and climate change can affect their C sequestration function. These findings have important implications for ecosystem management that aims at maximizing C sequestration at the landscape level to mitigate climate change.
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Martin-Philippe Girardin, Jeanne Portier, Cécile Remy, Adam Ali, Jordan Paillard, Olivier Blarquez, Hugo Asselin, Sylvie Gauthier, Yves Bergeron, Pierre Grondin. Coherent signature of warming-induced extreme sub-continental boreal wildfire activity 4,800 and 1,100 years BP. 2019. Environmental Research Letters 14(12):124042
DOI : 10.1088/1748-9326/ab59c9
Climate changes are expected to progressively increase extreme wildfire frequency in forests. Finding past analogs for periods of extreme biomass burning would provide valuable insights regarding what the effects of warming might be for tree species distribution, ecosystem integrity, atmospheric greenhouse gas balance, and human safety. Here, we used a network of 42 lake-sediment charcoal records across a ~2000 km transect in eastern boreal North America to infer widespread periods of wildfire activity in association with past climate conditions. The reconstructed fluctuations in biomass burning are broadly consistent with variations in ethane concentration in Greenland polar ice cores. Biomass burning fluctuations also significantly co-varied with Greenland temperatures estimated from ice cores, at least for the past 6000 years. Our retrospective analysis of past fire activity allowed us to identify two fire periods centered around 4800 and 1100 BP, coinciding with large-scale warming in northern latitudes and having respectively affected an estimated ~71% and ~57% of the study area. These two periods co-occurred with widespread decreases in mean fire-return intervals. The two periods are likely the best analogs for what could be anticipated in terms of impacts of fire on ecosystem services provided by these forests in coming decades.
Pierre Grondin, Andréane Garant, Julien Beguin, Amira Fetouab , Maisa De Noronha, Dominique Arseneault. Forêts paludifiées, sols et changements climatiques Rendez-vous de la connaissance en aménagement forestier durable (2022-04-05)
Achraf Ammar, Ahmed Koubaa, Yves Bergeron, Dorra Gassara, Pierre Grondin. Potentiel de la tomographie acoustique pour la caractérisation non destructive de la proportion de la carie et son impact sur le module d’élasticité du bois de l’érable à sucres 23e colloque de la Chaire AFD. Université du Québec en Abitibi-Témiscamingue (2021-12-07)
Pierre Grondin Partenaire du MFFP 23e colloque de la Chaire AFD. Université du Québec en Abitibi-Témiscamingue (2021-12-07)
Pierre Grondin, Maxence Martin, Hubert Morin, Yan Boucher. La tordeuse des bourgeons de l’épinette : moteur de la dynamique des vieilles forêts boréales et source d’inspiration pour l’aménagement écosystémique? Les Rendez-vous de la connaissance en aménagement forestier durable MFFP - Les ravageurs forestiers (2021-05-18)
Julia Cigana, Guillaume de Lafontaine, Pierre Grondin, Yves Bergeron. Dynamique holocène et potentiel d’expansion de l’érablière à sucre la plus nordique en Abitibi-Témiscamingue 22e colloque de la Chaire AFD. Université du Québec en Abitibi-Témiscamingue, complètement virtuel (2020-12-02)
Raphaël Chavardes, Fabio Gennaretti, Xavier Cavard, Pierre Grondin, Lorena Balducci, Hubert Morin, Alain Leduc, Ari Kainelainen, Danielle Charron, T. Châtellier, Yves Bergeron. Le mélange des espèces dans le peuplement peut-il atténuer la vulnérabilité des forêts boréales aux changements climatiques et aux épidémies d’insectes ? 22e colloque de la Chaire AFD. Université du Québec en Abitibi-Témiscamingue, complètement virtuel (2020-12-02)
Evick Mestre, Yves Bergeron, Rock Ouimet, Pierre Grondin. Potentiel de migration des populations nordiques d’érable à sucre dans l’Ouest du Québec 21e colloque de la Chaire AFD. Université du Québec en Abitibi-Témiscamingue, Rouyn-Noranda, Québec. (2019-11-30)
Pierre Grondin Hétérogénéité paysagère contemporaine d'une portion de la forêt boréale québécoise et implications pour l'aménagement écosystémique. Soutenance thèse (2014-12-09)
Pierre Grondin La classification écologique et l'aménagement écosystémique : des liens à développer. La classification écologique et l'aménagement écos (2005-12-06)
Pierre Grondin The landscapes of the boreal forest are controlled by one or by a combination of variables ? 5thNorth American Forest Ecology Workshop, Aylmer, Québec, Canada.
Pierre Grondin Survol de quelques enjeux de composition forestière de la forêt mélangée et de la forêt résineuse 74ième congrès annuel de l’ACFAS, Colloque C-643 Définition des enjeux régionaux dans la mise en place de l’aménagement écosystemique des forêts du Québec. Université McGill, Montréal, Québec, Canada.