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.
Yves Bergeron, Brian Brassard, Jérôme Laganière, David Paré, Han Chen, Xavier Cavard. Stability of Soil Carbon Stocks Varies with Forest Composition in the Canadian Boreal Biome. 2013. Ecosystems
DOI : 10.1007/s10021-013-9658-z
Changes in forest composition as a result of forest management, natural disturbances, and climate change may affect the accumulation of soil organic carbon (SOC). We examined the influence of common boreal tree species (trembling aspen, black spruce, and jack pine), either in pure stands or in conifer-broadleaf mixtures, on the amount, distribution, and quality of SOC in two regions of the Canadian boreal biome. Long-term laboratory incubations were used to assess SOC quality by quantifying proportions of fast carbon (C) (that is, proportion of total C released during the first 100 days of incubation) and active C (that is, modeled proportion of total C that can be potentially released). Total amounts of SOC did not differ between stand types, but the effects of stand type on SOC stocks and quality differed with soil depth. Among stand types, aspen stands had the greatest relative proportion of total SOC in deeper mineral layers and the lowest amount of active C in the organic layer. For these reasons, the SOC stock that developed under aspen was more stable than in the other stand types. Although black spruce stands allowed a greater accumulation of SOC in surface layers, these stocks, however, might become more vulnerable to extra losses if environmental conditions are to become more favorable to decomposition in the future. Our work highlights that boreal forest composition influences the stability of SOC stocks and how climate change could alter this large C pool.
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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)
Xavier Cavard Présentation de la chaire UQAT-MFFP en gestion du carbone forestier (GCaF) 21e colloque de la Chaire AFD. Université du Québec en Abitibi-Témiscamingue, Rouyn-Noranda, Québec. (2019-11-30)
Abderrahmane Ameray, Yves Bergeron, Xavier Cavard. Modélisation des réponses du bilan de carbone de la forêt boréale aux changements climatiques et aux perturbations naturelles et anthropiques 21e colloque de la Chaire AFD. Université du Québec en Abitibi-Témiscamingue, Rouyn-Noranda, Québec. (2019-11-30)
Xavier Cavard L'âge après feu est-il en soi un facteur de déclin ? Cas des îles du lac Duparquet. Midi-foresterie (2016-02-23)
Xavier Cavard Peut-on utiliser l'aménagement mixte pour maximiser la séquestration du carbone en forêt boréale de l'Est Canadien? 13ème atelier annuel de la Chaire industrielle CRSNG-UQAT-UQAM en aménagement forestier durable : Le carbone en zone boréale à l'heure des bilans (2012-04-25)
Xavier Cavard Interactions entre les essences forestières de la forêt boréale de l’Est du Canada, et conséquences pour la séquestration du carbone dans les peuplements mixtes. Soutenance thèse (2010-11-25)
Xavier Cavard Productivité du mélange épinette noire – peuplier faux-tremble 11e colloque de la Chaire AFD. Université du Québec en Abitibi-Témiscamingue, Rouyn-Noranda, Québec. (2009-12-09)