Abderrahmane Ameray, Xavier Cavard, Dominic Cyr, Osvaldo Valeria, Miguel Montoro Girona, Yves Bergeron. One century of carbon dynamics in the eastern Canadian boreal forest under various management strategies and climate change projections 2024. Ecological Modelling 110894
DOI : https://doi.org/10.1016/j.ecolmodel.2024.110894
Partial cutting has lower canopy removal intensities than clearcutting and has been proposed as an alternative harvesting approach to enhance ecosystem services, including carbon sequestration and storage. However, the ideal partial cutting/clearcutting proportion that should be applied to managed areas of the eastern Canadian boreal forest to enhance long-term carbon sequestration and storage at the landscape scale remains uncertain. Our study projected carbon dynamics over 100 years (2010–2110) under a portfolio of management strategies and future climate scenarios within three boreal forest management units in Quebec, Canada, distributed along an east–west gradient. To model future carbon dynamics, we used LANDIS-II, its Forest Carbon Succession extension, and several extensions that account for natural disturbances in the boreal forest (wind, fire, spruce budworm). We simulated the effects of several management strategies on carbon dynamics, including a business-as-usual strategy (clearcutting applied to more than 95 % of the annually managed area), and compared these projections against a no-harvest natural dynamics scenario. We projected an overall increase in total ecosystem carbon storage, mostly because of increased productivity and broadleaf presence under limited climate change. The drier Western region under climate scenario RCP8.5 was an exception, as stocks decreased after 2090 because of the direct negative effects of extreme climate change on coniferous species’ productivity. Under the natural dynamic scenario, our simulations suggest that the Quebec Forest in the Central and Western regions may act as a carbon sink, despite high fire-related carbon emissions, particularly under RCP4.5 and RCP8.5 Conversely, the eastern region periodically switched from carbon sink to source following SBW outbreaks, thus being a weak sink over the simulation period. Applying partial cutting to over 50 % of the managed forest area effectively mitigated the negative impacts of climate change on carbon balance, reducing differences in stand composition and carbon storage between naturally dynamic forests and those managed for timber. In contrast, clearcutting-based scenarios, including the business-as-usual approach, substantially reduced total ecosystem carbon storage— by approximately double (10 tC ha−1 yr−1) compared to partial cutting scenarios (<5 tC ha−1 yr−1). Clearcutting led to higher heterotrophic respiration due to the proliferation of fast-decomposing broadleaves, resulting in lower carbon accumulation compared to partial cuts. Our findings underscore the importance of balancing canopy removal intensities to increase carbon sequestration and storage while preserving other ecosystem qualities under climate change.
Abderrahmane Ameray, Yves Bergeron, Xavier Cavard. Modelling the potential of forest management to mitigate climate change in Eastern Canadian forests 2023. Scientific Reports 14506
DOI : 10.1038/s41598-023-41790-2
Climate change poses a serious risk to sustainable forest management, particularly in boreal forests where natural disturbances have been projected to become more severe. In three Quebec boreal forest management units, biomass carbon storage under various climate change and management scenarios was projected over 300 years (2010–2310) with a process-based dynamic landscape model (PnET-succession for Landis-II). Several strategies varying in their use of partial cuts and clear cuts, including business as usual (BAU) (clear-cut applied on more than 95% of the managed area), were tested and compared to conservation scenarios (no-harvest). Based on simulation results at the landscape scale, the clearcut-based scenarios such as BAU could result in a decrease of biomass carbon stock by 10 tC ha−1 yr−1 compared to the natural scenario. However, this reduction in carbon stock could be offset in the long term through changes in composition, as clearcut systems promote the expansion of trembling aspen and white birch. In contrast, the use of strategies based on partial cuts on more than 75% or 50% of the managed area was closer to or better than the natural scenario and resulted in greater coniferous cover retention. These strategies seemed to be the best to maximize and stabilize biomass carbon storage and ensure wood supply under different climate change scenarios, yet they would require further access and appropriate infrastructure. Furthermore, these strategies could maintain species compositions and age structures similar to natural scenarios, and thus may consequently help achieve forest ecosystem-based management targets. This study presents promising strategies to guide sustainable forest management in Eastern Canada in the context of climate change.
Ange-Marie Bothroh, David Paré, Xavier Cavard, Nicole J. Fenton, Osvaldo Valeria, Philippe Marchand, Yves Bergeron. Nine-years effect of harvesting and mechanical site preparation on
bryophyte decomposition and carbon stocks in a boreal forested peatland, 2023. For. Ecol. Manage. 540:121020
DOI : 10.1016/j.foreco.2023.121020
The boreal forest holds the world's largest soil carbon (C) reservoir. A large portion of it is contained in a thick organic layer originating from the slow decay of bryophytes. Because a thick organic layer slows down tree growth, reduces forest productivity, and thereby reduces the potential wood supply, silvicultural treatments that aim to maintain or restore forest productivity after harvesting often involve mechanical site preparation. However, while these treatments can increase growth and C storage in trees, they can also lead to accelerated decomposition of the soil organic matter, reducing C storage. In this study, we assessed the nine-years effect of two silvicultural treatments on soil C dynamics in forested peatlands of northwestern Quebec, compared to unharvested controls: (1) cut with protection of regeneration and soils (CPRS; low soil disturbance, also called careful logging around advanced growth (CLAAG)), (2) CPRS followed by mechanical site preparation (CPRS + MSP, plowing; severe soil disturbance). The mass loss rate of three bryophytes (Pleurozium schreberi, Sphagnum capillifolium, and Sphagnum fuscum) was measured over two growing seasons together with soil organic carbon (SOC) stocks. We also studied the different effects of temperature, water table level, depth, and type of soil layer on mosses decomposition.We observed a significant influence of silvicultural treatments, bryophyte species, and soil layer type (fibric, mesic, humic and mineral) on bryophyte mass loss, which was higher in the CPRS + MSP treatment (21.6 ± 0.13 % standard error) than in control sites (9.5 ± 0.21 %); CPRS alone resulted in an intermediate mass loss of 11.6 ± 0.23 %, for Sphagnum mosses. Bryophyte mass loss was significantly higher in fibric than humic layer. SOC stocks in the uppermost organic soil layer (fibric) were lower in the CPRS + MSP group than in the control group, while the CPRS group was intermediate; however, differences were not statistically significant for the other soil layer and for total SOC. We conclude that while CPRS + MSP accelerates Sphagnum moss decomposition in the topsoil layer, it has limited impact on total soil C stocks that are detectable with stock change methods.
Abderrahmane Ameray, Xavier Cavard, Yves Bergeron. Climate change may increase Quebec boreal forest productivity in high latitudes by shifting its current composition 2023. Frontiers in forests and global change 6:1020305
DOI : 10.3389/ffgc.2023.1020305
Several recent studies point out that climate change is expected to influence boreal forest succession, disturbances, productivity, and mortality. However, the effect of climate change on those processes and their interactions is poorly understood. We used an ecophysiological-based mechanistic landscape model to study those processes and their interactions and predict the future productivity and composition under climate change scenarios (RCP) for 300 years (2010–2310). The effects of climate change and wildfires on forest composition, biomass carbon sequestration and storage, and mortality were assessed in three management units of Quebec boreal forest, distributed along a longitudinal gradient from west to east: North-of-Quebec (MU1), Saguenay–Lac-Saint-Jean (MU2), and Côte-Nord region (MU3). Coniferous mortality variation was explained by competitive exclusion and wildfires, which are related to climate change. In the studied MU, we found a decrease in coniferous pure occupancy at the landscape scale and an increase in mixed deciduous forests in MU1 and MU2, and an increase in mixed coniferous, mainly black spruce and balsam fir in MU3. On the other hand, for extreme scenarios (RCP4.5 and RCP8.5), in the absence of broadleaves dispersal, the open woodland occupancy could increase to more than 8, 22, and 10% in MU1, MU2, and MU3 respectively. Also, climate change might increase overall biomass carbon stock two times for RCP2.6 and RCP4.5 scenarios compared to the baseline this may be explained by the extension of the growing season and the reduction of potential cold-temperature injuries. Generally, western regions were more sensitive to climate changes than the eastern regions (MU3), in fact under RCP8.5 biomass carbon stock will be decreasing in the long-term for MU1 compared to the current climate. This study provides a good starting point to support future research on the multiple factors affecting forest C budget under global change.
Abderrahmane Ameray, Yves Bergeron, Osvaldo Valeria, Miguel Montoro Girona, Xavier Cavard. Forest Carbon Management: a Review of Silvicultural Practices and Management Strategies Across Boreal, Temperate and Tropical Forests 2021. Current Forestry Reports
DOI : 10.1007/s40725-021-00151-w
Carbon sequestration and storage in forest ecosystems is often promoted as a solution for reducing CO2 concentrations in the atmosphere. Yet, our understanding is lacking regarding how forest management strategies affect the net removal of greenhouse gases and contribute to climate change mitigation. Here, we present a review of carbon sequestration and stock dynamics, following three strategies that are widely used in boreal, temperate and tropical forests: extensive forest management, intensive forest management and old-growth forest conservation.
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.
Yves Bergeron, Xavier Cavard, Marie-Charlotte Nilsson, David A. Wardle, David Paré. Disentangling Effects of Time Since
Fire, Overstory Composition
and Organic Layer Thickness
on Nutrient Availability in Canadian
Boreal Forest. 2019. Ecosystems 22(1)33-48
DOI : 10.1007/s10021-018-0251-3
Wildfire is the primary abiotic disturbance in the boreal forest, and its long-term absence can lead to large changes in ecosystem properties, including the availability and cycling of nutrients. These effects are, however, often confounded with the effects of successional changes in vegetation toward nutrient-conservative species. We studied a system of boreal forested lake islands in eastern Canada, where time since last fire ranged from 50 to 1500 years, and where the relative abundance of the most nutrient-conservative tree species, black spruce, was largely independent of time since last fire. This allowed us to disentangle the effects of time since fire and the dominant vegetation on ecosystem properties, including nutrient stocks and concentrations. Effects of time since fire independent of vegetation composition mostly involved an increase in the thickness of the organic layer and in nitrogen concentration in both soil and leaves. Domination by black spruce had strong negative effects on nutrient concentrations and was associated with a shift toward more fungi and Gram-positive bacteria in the soil microbial community. Path modeling showed that phosphorus concentration was inversely related to organic layer thickness, which was in turn related to both time since fire and black spruce abundance, while nitrogen was more directly related to time since fire and the composition of the overstory. We conclude that discriminating between the effects of vegetation and time since fire is necessary for better understanding and predicting the long-term changes that occur in forest nutrient availability and ecosystem properties.
Brian Brassard, Yves Bergeron, Jérôme Laganière, Xavier Cavard, Han Chen, David Paré. The influence of boreal tree species mixtures on ecosystem carbon storage and fluxes. 2015. For. Ecol. Manage. 354:119-129
DOI : 10.1016/j.foreco.2015.06.029
Plant species mixtures are often seen as being able to achieve higher productivity and carbon (C) sequestration than their single-species counterparts, but it is unclear whether this is true in natural forests. Here, we investigated whether naturally-regenerated mixtures of common North American boreal tree species were more productive and stored more C than single-species stands. We also examined how closely the different C pools and fluxes were interrelated and whether these relationships varied with species composition. Single- and mixed-species stands of trembling aspen, black spruce and jack pine on mesic sites were selected in two regions of the Canadian boreal forest to assess aboveground and belowground productivity and C storage. Although previous studies conducted in these stands found synergistic effects of tree species mixtures on specific C pools and fluxes, such as higher organic layer C stocks and higher fine root productivity in some mixtures, no effects were detected on combined C pools or fluxes at the ecosystem level in the current study. Aspen abundance was linked with higher aboveground tree productivity, higher aboveground living biomass and higher soil heterotrophic respiration, indicating that aspen acts as a key driver of ecosystem C storage and fluxes in these natural forest ecosystems, more so than species richness. However, our results do not rule out the possibility of increased productivity and C storage in mixed stands under environmental conditions or stand developmental stages that are different from the ones studied here. Furthermore, when the entire forest ecosystem is considered (not only tree parts), synergistic effects of tree species mixtures may be more difficult to observe because the beneficial effect of species mixing on one specific C pool may be counterbalanced by a negative effect on another pool.
Jean-François Boucher, Yves Bergeron, Xavier Cavard. Vegetation and topography interact with weather to drive the spatial distribution of wildfires in the eastern boreal forest of Canada. 2015. International Journal of Wildland Fire 24(3):391-406
DOI : 10.1071/WF13128
It is crucial to better understand and predict how burnt areas in the boreal forest will evolve under a changing climate and landscape. The objective of the present study was to predict burnt areas at several spatial and temporal scales in the Quebec continuous boreal forest and to compare the influence of weather, vegetation and topographic variables by including them and their interactions in logistic regressions. At the largest spatial scale (350 km2), the best model explained 66% of the data variability and was able to predict burnt areas with reasonable accuracy for 11 years (r = 0.48). Weather and vegetation or topographic variables had an equivalent importance, though no single vegetation or topographic variable was mandatory to the model performance. Interactions between weather and non-weather variables largely improved the model, particularly when several weather indices were used, as the sign of the interaction with a non-weather variable could differ between weather indices. Vegetation and topography are therefore important predictors of fire susceptibility, but risk factors may vary between wind- and drought-driven fire weather. Including at least some vegetation and topographic variables in statistical models linking burnt areas to weather data can greatly improve their predictive power.
Samuel B. St. Clair, Yves Bergeron, Xavier Cavard. The role of facilitation and competition in the development and resilience of aspen forests. 2013. For. Ecol. Manage. 299:91-99
DOI : 10.1016/j.foreco.2013.02.026
Underlying the development and function of aspen forest communities are interactions between aspen and a broad suite of plant species. These plant–plant interactions can be facilitative or antagonistic in nature and their influence varies depending on multiple environmental factors that are changing with human activity. The purpose of this synthesis paper is to identify the patterns, mechanisms and consequences of facilitation and competition in aspen communities and how they vary based on environmental conditions and different aspen forest types.
Across its expansive range, aspen commonly associate with conifers to form mixed forests. There is increasing evidence that facilitation in early stand development alters competitive interactions between aspen and conifers in later stages of development. However, the influences of facilitation and competition vary depending on conifer species and aspen forest type. In drier, montane aspen forests of the western US, shade and higher moisture content at the base of aspen trees facilitate the germination and survival of young fir seedlings. This facilitation effect increases the proximity of aspen and fir which over time creates competitive interactions that favor conifer dominance. In the more mesic conditions of eastern Canada, aspen also promotes fir establishment but the facilitation effect occurs at the stand level and is most likely driven by increased light penetration and more optimal edaphic conditions rather than by mitigating moisture limitations. In the western and central boreal forest, successional transitions are primarily driven by competitive effects in which short fire cycles and competitive inhibition of spruce favors aspen dominance.
Positive and antagonistic interactions between aspen and associated plant species are influenced by environmental conditions that fluctuate according to nature processes and human perturbations. In this review we discuss the impact that plant invasions, global change factors, fire regimes and herbivory have on plant–plant interactions in aspen forest and how they modify successional outcomes. The literature suggests that aspen’s competitive ability is strongly influenced by rising CO2, temperatures, drought and ozone. Conditions resulting in longer fire cycles will tend to promote losses in aspen cover through competitive exclusion through conifer expansion. Finally, competition alters aspen susceptibility to herbivory which is a major threat to aspen resilience in some parts of its range. Identifying the environmental conditions that create the proper balance between facilitative and competitive interactions is paramount in formulating management approaches that promote resilient aspen forests.
voir la liste complète
Xavier Cavard Vie et mort du carbone forestier 17e colloque annuel du CEF, Université du Québec en Outaouais (2024-05-03)
Angana Kuri, Nicole J. Fenton, Mebarek Lamara, Xavier Cavard. Gradient-based assessment of ecosystem resilience: evaluating vegetation, soil microbiome diversity and carbon pools of outcrops in proximity to the Horne Smelter of Rouyn-Noranda 17e colloque annuel du CEF, Université du Québec en Outaouais (2024-05-02)
Bandana Subedi, Nicole J. Fenton, Xavier Cavard. The role of bryophytes in buffering the impacts of climate change-induced decline of snow cover on belowground forest carbon dynamics in boreal forest ecosystems 17e colloque annuel du CEF, Université du Québec en Outaouais (2024-05-02)
Xavier Cavard, Alejandro Vega Escobar, Osvaldo Valeria, Jean-François Boucher, François Girard. Quelles seraient les meilleures stratégies de gestion pour limiter l'influence directe et indirecte du réseau routier sur le bilan carbone ? 25e colloque de la Chaire AFD. Université du Québec en Abitibi-Témiscamingue, Rouyn-Noranda, Québec. (2023-11-28) youtube
Rachel Furaha Kasoro, Rock Ouimet, Xavier Cavard. Effets des coupes saisonnières sur la dynamique du carbone aérien et du sol dans une forêt dominée par les résineux 25e colloque de la Chaire AFD. Université du Québec en Abitibi-Témiscamingue, Rouyn-Noranda, Québec. (2023-11-28)
Bandana Subedi, Nicole J. Fenton, Xavier Cavard. The role of bryophytes in buffering the impacts of climate change-induced loss of snow cover on belowground forest carbon dynamics. 25e colloque de la Chaire AFD. Université du Québec en Abitibi-Témiscamingue, Rouyn-Noranda, Québec. (2023-11-28)
Abderrahmane Ameray, Yves Bergeron, Xavier Cavard. Efficacité des stratégies d'aménagement forestier pour atténuer et s’adapter aux changements climatiques au Québec 24e colloque de la Chaire AFD. Université du Québec en Abitibi-Témiscamingue, Rouyn-Noranda, Québec. (2022-11-22)
Miray Andrianirinarimanana, Nelson Thiffault, Jean-François Boucher, Xavier Cavard. Comment les traitements sylvicoles affectent-ils les stocks de carbone des peuplements d'épinettes noires ? 24e colloque de la Chaire AFD. Université du Québec en Abitibi-Témiscamingue, Rouyn-Noranda, Québec. (2022-11-22)
Clémence Boivin, Nicole J. Fenton, Xavier Cavard, Mebarek Lamara. Est-ce possible de favoriser à la fois la biodiversité et la séquestration du carbone ? 24e colloque de la Chaire AFD. Université du Québec en Abitibi-Témiscamingue, Rouyn-Noranda, Québec. (2022-11-22)
Maya Disraëli Ratsimandresiarivo, Annie DesRochers, Xavier Cavard. Comment les traitements sylvicoles affectent-ils le carbone organique du sol dans les peuplements d’épinettes noires? 24e colloque de la Chaire AFD. Université du Québec en Abitibi-Témiscamingue, Rouyn-Noranda, Québec. (2022-11-22)
Mialintsoa Aroniaina Randriamananjara, Nicole J. Fenton, Xavier Cavard, Mélanie Jean, Annie DesRochers. Diversité végétale dans les plantations de peupliers hybrides en plantation pure et mixte 24e colloque de la Chaire AFD. Université du Québec en Abitibi-Témiscamingue, Rouyn-Noranda, Québec. (2022-11-22)
Mialintsoa Aroniaina Randriamananjara, Nicole J. Fenton, Xavier Cavard, Mélanie Jean, Annie DesRochers. Diversité végétale et fonctionnelle dans les plantations mixtes de peupliers hybrides et les monocultures 15e colloque annuel du CEF, Université de Sherbrooke, Québec (2022-09-29)
Axelle Favro , Xavier Cavard, Fabio Gennaretti, Jérôme Laganière. Effets des traitements sylvicoles sur les flux de carbone des épinettes noires (Picea Mariana (Mill.) B.S.P.) en réponse à la disponibilité en eau. 15e colloque annuel du CEF, Université de Sherbrooke, Québec (2022-09-28)
Clémence Boivin, Xavier Cavard, Nicole J. Fenton, Mebarek Lamara. Foresterie multifonctionnelle : est-il possible de favoriser à la fois la biodiversité et la séquestration du carbone ? 15e colloque annuel du CEF, Université de Sherbrooke, Québec (2022-09-28)
Miray Andrianirinarimanana, Xavier Cavard, Jean-François Boucher, Nelson Thiffault. Comment les traitements sylvicoles affectent les stocks de carbone aérien des pessières le long d'un gradient longitudinal ? 15e colloque annuel du CEF, Université de Sherbrooke, Québec (2022-09-28)
Clémence Boivin, Nicole J. Fenton, Xavier Cavard, Mebarek Lamara. Foresterie multifonctionnelle : est-il possible de favoriser à la fois la biodiversité et la séquestration du carbone ? Conférence annuelle de l’Association Botanique Canadienne. Université du Québec en Abitibi-Témiscamingue, Rouyn-Noranda, Québec. (2022-06-06)
Mialintsoa Aroniaina Randriamananjara, Annie DesRochers, Nicole J. Fenton, Xavier Cavard, Mélanie Jean. Impact de l'établissement des plantations à croissance rapide utilisant des espèces exotiques sur la biodiversité de la végétation de sous-bois Conférence annuelle de l’Association Botanique Canadienne. Université du Québec en Abitibi-Témiscamingue, Rouyn-Noranda, Québec. (2022-06-06)
Abderrahmane Ameray, Xavier Cavard. Un modèle comme Landis-II peut-il nous aider à comprendre comment les changements climatiques et l’aménagement forestier peuvent conjointement modifier la dynamique du carbone en forêt boréale? Les Rendez-vous de la connaissance en aménagement forestier durable MFFP - Séquestration du carbone (2021-04-20)
Xavier Cavard, Abderrahmane Ameray, Sylvie Tremblay, Évelyne Thiffault. Rendez-vous de la connaissance en aménagement forestier durable - Séquestration du carbone Les Rendez-vous de la connaissance en aménagement forestier durable (2021-04-20)
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)