Anticipated impacts in habitat of diagnostic species of potential natural vegetations due to climate change at the ecotone between temperate and boreal forests
Potential natural vegetations are crucial for forest research, management, and monitoring, especially considering their evolution amidst climate change. In Quebec (Canada), these vegetations were defined in the 2000s but haven't been updated since then. Originally, stability in their composition and dynamics relied on unchanged climate, soil characteristics, and disturbance regimes. However, in the southwestern part of Quebec forests, we have enhanced the description of potential natural vegetations using diagnostic species, based on their indicator values and relative abundance. This improvement prompts a reevaluation of these vegetations, particularly at the transition between temperate and boreal forests, considering climate change. Our study, using tree habitat suitability models, reveals that even under a moderately warming scenario (2041–2070 RCP 4.5 W m−2), diagnostic coniferous and boreal hardwood species face habitat suitability declines but the current classification remains adequate. However, a more severe warming scenario (2071–2100 RCP 8.5 W m−2) results in significant habitat unsuitability for these diagnostic species, questioning the relevance of the current classification at the ecotone. Given the crucial tool of potential natural vegetations in forest management, updating their classification becomes imperative to guide forestry practices' adaptation to climate change.
Factors influencing black spruce reproductive potential in the northern boreal forest of Quebec.
The reproductive ecology of the semi-serotinous species black spruce (Picea mariana (Mill.) BSP) in northern boreal forests remains poorly understood. There is a general lack of data on cone/seed production and viability as a function of biotic tree-level characteristics and abiotic variables. No studies currently exist to quantify these differences over a large gradient in temperature, elevation, and precipitation. Extensive physical, ecological, dendrometric, and reproductive data were collected from young to very old black spruce stands in northern Quebec. ANOVA and general linear mixed models were used to examine interannual cone production, and the relative importance of the biotic and abiotic explanatory factors in determining total cone production; length of the cone-bearing zone; filled seeds per cone; proportion of filled seeds; and seed viability. The results illustrate that the reproductive ecology of black spruce in northern cold forests is mainly explained by biotic variables such as age and diameter at breast height, and by abiotic variables related to temperature such as elevation, length of the growing season, and growing degree-days. Black spruce exhibits a lower reproductive potential in northern cold forests, making it possibly less resilient to increased fire frequency, particularly in unproductive and very young or very old stands.
Forest Structure and Composition Diverge Following Harvesting Compared to a Spruce Budworm Choristoneura fumiferana (Clem.) Outbreak
Balsam fir (Abies balsamea) is the most vulnerable species to the spruce budworm (Choristoneura fumiferana), one of the most devastating defoliators in the world. For decades, pest managers have advocated for reducing its abundance in the landscape to minimize losses to the spruce budworm (SBW). Although reduction of fir occurred during the endemic phase of the SBW cycle, there is little information about the extent to which this general principle (reduction of fir) was applied during an outbreak and whether it occurs at both stand and landscape levels. The objective of this paper is to compare the effect of insect and harvest disturbances on forest structure during the 1970–80s outbreak in Québec. We evaluate whether, (i) forest management activities targeted fir forests and whether patch size of host species influences management or SBW disturbance, (ii) SBW outbreaks and logging have similar or divergent effects on forest composition. Although data are from an earlier outbreak, they are at a scale rarely studied and will be useful in guiding decisions made at larger scales in the current and future outbreaks. Our results show that spruce was targeted preferentially by harvesting (up to 69% of plots) during the outbreak period, while it represented less than one third of plots defoliated by the SBW. On the other hand, fir stands represented up to 75% of plots that were defoliated by the SBW but less than 35% of plots that underwent harvesting. Harvesting targeted large blocks of spruce forest more than large blocks of fir-dominated forest while the opposite was observed for the SBW. In terms of regeneration, SBW tends to reduce fir and favor spruce recruitment, along with non-host species, whereas the opposite tendency was observed following harvesting. In terms of spatial organization of stands, our results support the suggestion that small stands of fir and large stands of spruce undergo the least SBW damage. Thus, in order to attenuate SBW impacts in the future, efforts should be made to ensure that spruce recruitment is favored and that its abundance increases at both the stand and landscape scale.
Examining boreal forest resilience to temperature variability using bryophytes: forest type matters.
The capacity of individual species to tolerate environmental changes is a major driver of ecosystem resilience. This subject has been a hot topic in boreal forests due to the greater effect of climate change anticipated at northern latitudes. However, to date it has been mainly examined for trees, with comparatively little emphasis on other species groups. In this study, bryophytes were sampled in the boreal forest of Québec (Canada) using a stratified sampling design allowing us to separate the effect of dominant canopy composition (two types: coniferous and mixedwood) and of the spatial climatic gradient (relatively warm and relatively cold sites) on bryophyte community structure (species richness and composition). The results indicated that bryophyte composition was different between coniferous and mixedwood stands. The impacts of spatial variation in climate were more visible in mixedwood than coniferous stands, indicating an interaction between stand type and climate. Specifically, bryophytes from mixedwood stands, and particularly specialist communities associated with deadwood and live tree bases, were climate?sensitive and represent a potential target group to investigate the effects of climate change. In contrast, bryophyte communities from coniferous stands are stand structure?sensitive, with little response to climate, presumably partly because coniferous canopies buffer climatic variations. Since bryophyte community sensitivity to regional variations in climatic conditions depends on dominant canopy characteristics and microhabitat availability, we suggest that adapted forest management practices could play a role in attenuating climate change impacts on these organisms.
Incorporating Insect and Wind Disturbances in a Natural Disturbance-Based Management Framework for the Boreal Forest.
Natural disturbances are fundamental to forest ecosystem dynamics and have been used for two decades to improve forest management, notably in the boreal forest. Initially based on fire regimes, there is now a need to extend the concept to include other types of disturbances as they can greatly contribute to forest dynamics in some regions of the boreal zone. Here we review the main descriptors—that is, the severity, specificity, spatial and temporal descriptors and legacies, of windthrow and spruce bud worm outbreak disturbance regimes in boreal forests—in order to facilitate incorporating them into a natural disturbance-based forest management framework. We also describe the biological legacies that are generated by these disturbances. Temporal and spatial descriptors characterising both disturbance types are generally variable in time and space. This makes them difficult to reproduce in an ecosystem management framework. However, severity and specificity descriptors may provide a template upon which policies for maintaining post harvesting and salvage logging biological legacies can be based. In a context in which management mainly targets mature and old-growth stages, integrating insect and wind disturbances in a management framework is an important goal, as these disturbances contribute to creating heterogeneity in mature and old-growth forest characteristics.
Climate-induced range shifts in boreal forest pests: ecological, economic, and social consequences.
Climate change is causing northward shifts in species ranges. For mobile species such as insects, this will increase their access to forest ecosystems where in the past their presence and impact was limited. Range expansion and increases in outbreak severity of forest pests have been documented in Europe and North America (Jepsen et al. 2008; Bentz et al. 2010). Temperature-mediated phenological changes and trophic interactions among host trees, herbivorous insects, and their natural enemies are linked to the long-term effects of range expansion on boreal ecosystems. The degree to which temperate and boreal forest ecosystems are resilient to novel disturbance regimes will have direct consequences on the provisioning of goods and services from these forests and on long-term forest management planning. These concerns were the impetus for the organization of a workshop on climate-induced range shifts in boreal forest pests. Contributions to this special feature are selected papers from the International Union of Forest Research Organizations (IUFRO) workshop held in July 2016 in northeastern Quebec. The workshop was organized around five themes related to the consequences of range shifts of boreal forest insect pests: (1) plant–insect phenology, (2) species range expansions, (3) ecosystem response to changes in disturbance regimes, (4) interactions among disturbances, and (5) forest management and adaptation to change.
Contrasting responses of epiphytic and terricolous lichens to variations in forest characteristics in northern boreal ecosystems.
Les principaux facteurs qui déterminent la composition des communautés de lichens sont encore mal connus dans les écosystèmes boréaux nordiques. Cette étude compare les effets des caractéristiques (hauteur, couvert forestier et âge) des peuplements forestiers sur les communautés de lichens épiphytes fruticuleux et terricoles à travers une vaste région située à la limite ente les forêts boréales à couvert fermé et les forêts nordiques ouvertes dans la province de Québec (Canada). Le jeu de données est composé de 875 placettes réparties sur un territoire de 242?000 km2 qui s’étend entre les extrémités est et ouest de la province. La biomasse des lichens épiphytes fruticuleux (Alectoria, Bryoria, Evernia et Usnea) a été évaluée à l’échelle de la branche, de l’arbre et de la placette; le recouvrement de lichens terricoles (Cladonia spp.) a été évalué à l’échelle de la placette. Les résultats montrent que les lichens épiphytes et terricoles réagissent de façon significative mais différente aux variations des caractéristiques de la forêt. À l’échelle de la placette, la biomasse des lichens épiphytes était la plus élevée dans les plus vieux peuplements (>100 ans), et la plus faible dans les peuplements avec un faible couvert forestier (<25%) ou dans les peuplements dominés par des arbres de petite taille (<7 m). Par contre, le recouvrement de lichens terricoles était le plus élevé dans les peuplements dominés par des arbres de petite taille (<7 m) ou de taille intermédiaire (7–12 m) et le plus faible dans les peuplements avec un couvert forestier relativement important (>40 %) ou dans les peuplements d’âge intermédiaire (60–100 ans). La composition en espèces des communautés épiphytes a également été étudiée et certaines espèces ou genres étaient étroitement associés aux peuplements plus vieux (Alectoria sarmentosa (Ach.) Ach., Bryoria spp.), ou à des régions particulières le long du gradient est-ouest d’environ 1500 km (Evernia mesomorpha Nyl. à l’ouest, Bryoria spp. au centre et A. sarmentosa à l’est). En termes de conservation, ces résultats indiquent que les communautés de lichens épiphytes sont potentiellement sensibles à l’exploitation préférentielle des vieux peuplements. Les communautés de lichens épiphytes et terricoles sont aussi potentiellement sensibles aux effets appréhendés des changements climatiques tels que l’augmentation de la fréquence des feux ou l’augmentation de la croissance de la forêt.
Do forests treated by partial cutting provide growth conditions similar to old-growth forests for epiphytic lichens?
In boreal forests, partial cutting is increasingly proposed as a suitable alternative to the widespread use of clearcutting in order to conciliate forest management with habitat conservation for epiphytic species. We compared the growth of two epiphytic lichen species, Bryoria nadvornikiana and Evernia mesomorpha, in old forest stands recently treated by partial cutting and untreated controls, located in black spruce boreal forests of western Québec. Lichen growth rates were measured over a period of two years from transplants of the two species, and several environmental variables (e.g., canopy openness, thallus temperature, and thallus wetness) were also measured directly at the sampling sites. Despite important within-treatment variation in growth rates among transplants, we observed reduced growth rates in partial cuts for both species. Canopy openness measurements of more than 40% resulted in negative growth rates for B. nadvornikiana, a species typically associated with relatively closed canopies, and canopy openness over 70% resulted in negative growth rates for E. mesomorpha, a species that tends to be associated with open canopies. This negative growth response contrasts with what is generally reported in the literature about the effect of canopy opening creation on epiphytic lichen growth. As a function of the environmental parameters that were measured on site, we suggest that a reduction in the duration of hydration periods, and an increased risk of thallus fragmentation in partially cut stands, especially for B. nadvornikiana, could explain this result. Because this negative effect could be more likely to occur during dry periods, future trends in the response of epiphytic lichens to the creation of canopy openings could be influenced by climate change. This study suggest that even if partial cuts can be a good alternative to clearcutting for the conservation of epiphytic lichen species, they are more likely to succeed if dense clumps of residual trees (canopy cover > 70%) are retained in the treated stands.
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Mathieu Bouchard L’aménagement forestier dans un contexte de changements climatiques – comment la recherche peut-elle contribuer? Colloques du SCF-CFL (2025-03-06)
Mathieu Bouchard Prendre en compte de l'effet des changements climatiques dans la planification forestière 17e colloque annuel du CEF, Université du Québec en Outaouais (2024-05-03)
Catherine Périé, Nelson Thiffault, Mathieu Bouchard. Effets du statut hydrique du sol et de la température sur le succès de germination d'arbres 17e colloque annuel du CEF, Université du Québec en Outaouais (2024-05-03)
Rindra Fanomezana Ranaivomanana, Élise Filotas, Mathieu Bouchard. Évaluation de la vulnérabilité des paysages forestiers à la tordeuse des bourgeons de l'épinette à l'aide d'algorithmes d'apprentissage automatique 17e colloque annuel du CEF, Université du Québec en Outaouais (2024-05-03)
Jonathan Boucher, Mathieu Bouchard. Réduction des délais d'intervention des équipes héliportées sur les feux de forêt au Québec 17e colloque annuel du CEF, Université du Québec en Outaouais (2024-05-03)
Mathieu Bouchard Comment les communautés du bois mort sont-elles façonnées par le climat dans les forêts du Québec? 17e colloque annuel du CEF, Université du Québec en Outaouais (2024-05-02)
François Girard, Mathieu Bouchard, Marie-Hélène Brice. The impact of climate, soil and disturbance type on forest succession at Quebec's boreal-temperate ecotone 17e colloque annuel du CEF, Université du Québec en Outaouais (2024-05-02)
Justine Gillis, Jonathan Boucher, Miguel Montoro Girona, Mathieu Bouchard. Impact des traitements de BTK contre la tordeuse des bourgeons de l'épinette sur les risques de feu dans un peuplement. 25e colloque de la Chaire AFD. Université du Québec en Abitibi-Témiscamingue, Rouyn-Noranda, Québec. (2023-11-28)
Annie Belleau, Osvaldo Valeria, Daniela Mazo Calle, Vincent Nadeau, Mathieu Bouchard. L’utilisation du benchmarking pour guider les meilleures pratiques d’organisation spatiale de la récolte forestière Les Rendez-vous de la connaissance en aménagement forestier durable MFFP - Aménagement et récolte en forêt boréale (2021-06-01)
Annie Belleau, Daniela Mazo Calle, Osvaldo Valeria, Mathieu Bouchard, Pierre Couture. Comparaison de l'effet d’organisation spatiale de la récolte forestière sur la performance financière en utilisant l'Analyse d'enveloppement des données (DEA) 21e colloque de la Chaire AFD. Université du Québec en Abitibi-Témiscamingue, Rouyn-Noranda, Québec. (2019-11-30)
Mathieu Bouchard Reconstruction du développement spatial des épidémies de tordeuse récentes à l'aide de la dendrochronologie 12e colloque annuel du CEF, Université Laval (2018-04-30)
Mathieu Bouchard Modélisation des perturbations naturelles et marges de variabilité pour les forêts du Québec Midi-foresterie (2014-03-11)
Mathieu Bouchard Dynamique des forêts surannées du Nord du Témiscamingue. Soutenance thèse (2005-09-02)
Mathieu Bouchard, Daniel Kneeshaw, Yves Bergeron. Natural dynamics following successive spruce budworm outbreaks in mixed forests of western Quebec (Canada) 5th international Workshop on Disturbance Dynamics in Boreal forests, Dubna, Russie.
Mathieu Bouchard Forest landscape composition and structure after successive spruce budworm outbreaks 5thNorth American Forest Ecology Workshop, Aylmer, Québec, Canada.
