Annie Claude Bélisle, Sylvie Gauthier, Hugo Asselin. Integrating Indigenous and scientific perspectives on environmental changes: Insights from boreal landscapes. 2022. People and Nature 4(6):1513-1535
DOI : 10.1002/pan3.10399
- Major environmental changes affect the health and capacity of ecosystems to sustain Indigenous people's well-being in boreal landscapes. Collaboration between Indigenous communities and researchers could help assessing and mitigating the consequences of environmental changes.
- We used Driver Pressure State Impact (DPSI) conceptual models to compare the perspectives of Indigenous and scientific communities on environmental changes in boreal landscapes of Quebec, Canada.
- The Indigenous DPSI model emerged from interviews with local land-use experts from two Indigenous communities. The scientific model was informed by the publication topics of expert researchers.
- We compared the Indigenous and scientific models and exposed convergences and divergences between perspectives. Forestry was identified as a major driver of change in both models. Most issues related to mining, hydro-power and forest road development were specific to the Indigenous model. Climate change and wildfires were of greater interest in the scientific model.
- Convergences between the perspectives of Indigenous and scientific communities are conducive to collaborative research. Divergences could be addressed through reciprocal knowledge transfer activities, which would lead to research that better aligns with the concerns and needs of Indigenous communities.
Tadeusz Splawinski, Yan Boucher, David M. Green, Sylvie Gauthier, Mathieu Bouchard, Isabelle Auger, Luc Sirois, Yves Bergeron, Osvaldo Valeria. Factors influencing black spruce reproductive potential in the northern boreal forest of Quebec. 2022. Can. J. For. Res. 52(12):1499-1512
DOI : 10.1139/cjfr-2022-0092
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.
Raphaël Chavardes, Victor Danneyrolles, Jeanne Portier, Martin-Philippe Girardin, Dorian Gaboriau, Sylvie Gauthier, Igor Drobyshev, Tuomo Wallenius, Dominic Cyr, Yves Bergeron. Converging and diverging burn rates in North American boreal forests from the Little Ice Age to the present 2022. International Journal of Wildland Fire 31(12):1184-1193
DOI : 10.1071/WF22090
Warning: This article contains terms, descriptions, and opinions used for historical context that may be culturally sensitive for some readers.Background: Understanding drivers of boreal forest dynamics supports adaptation strategies in the context of climate change.Aims: We aimed to understand how burn rates varied since the early 1700s in North American boreal forests.Methods: We used 16 fire-history study sites distributed across such forests and investigated variation in burn rates for the historical period spanning 1700-1990. These were benchmarked against recent burn rates estimated for the modern period spanning 1980-2020 using various data sources.Key results: Burn rates during the historical period for most sites showed a declining trend, particularly during the early to mid 1900s. Compared to the historical period, the modern period showed less variable and lower burn rates across sites. Mean burn rates during the modern period presented divergent trends among eastern versus northwestern sites, with increasing trends in mean burn rates in most northwestern North American sites.Conclusions: The synchronicity of trends suggests that large spatial patterns of atmospheric conditions drove burn rates in addition to regional changes in land use like fire exclusion and suppression.Implications: Low burn rates in eastern Canadian boreal forests may continue unless climate change overrides the capacity to suppress fire.
Dominic Cyr, Jesus Pascual Puigdevall, Yves Bergeron, Sylvie Gauthier, Nelson Thiffault, Alain Leduc, Tadeusz Splawinski, Osvaldo Valeria. Mitigating post-fire regeneration failure in boreal landscapes with reforestation and variable retention harvesting: At what cost? 2022. Can. J. For. Res. 52(4):568-581
DOI : 10.1139/cjfr-2021-0180
Successive disturbances such as fire can affect post-disturbance regeneration density, with documented adverse effects on subsequent stand productivity. We conducted a simulation study to assess the potential of reactive (reforestation) and proactive (variable retention harvesting) post-fire regeneration failure mitigation strategies in a 1.37 Mha fire-prone boreal landscape dominated by black spruce (Picea mariana (Mill.) B.S.P.) and jack pine (Pinus banksiana Lamb.). We quantified their respective capacity to maintain landscape productivity and post-fire resilience, as well as their associated financial returns under current and projected (RCP 8.5) fire regimes. While post-fire reforestation with jack pine revealed to be the most effective strategy to maintain potential production, associated costs quickly became prohibitive when applied over extensive areas. Proactive strategies such as an extensive use of variable retention harvesting, combined with replanting of fire-adapted jack pine only in easily accessible areas, appeared as a more promising approach. Despite this, our results suggest an inevitable erosion of forest productivity due to post-fire regeneration failure events, highlighting the importance of integrating fire a priori in strategic forest management planning as well as its effects on long-term regeneration dynamics.
Mathilde Pau, Raphaël Chavardes, Yves Bergeron, William Marchand, Martin-Philippe Girardin, Sylvie Gauthier. Site index as a predictor of the effect of climate warming on
boreal tree growth. 2021. Global Change Biology 28(5):1903-1918
DOI : 10.1111/gcb.16030
The boreal forest represents the terrestrial biome most heavily affected by climate change. However, no consensus exists regarding the impacts of these changes on the growth of tree species therein. Moreover, assessments of young tree responses in metrics transposable to forest management remain scarce. Here, we assessed the impacts of climate change on black spruce (Picea mariana [Miller] BSP) and jack pine (Pinus banksiana Lambert) growth, two dominant tree species in boreal forests of North America. Starting with a retrospective analysis including data from 2591 black spruces and 890 jack pines, we forecasted trends in 30-year height growth at the transitions from closed to open boreal coniferous forests in Québec, Canada. We considered three variables: (1) height growth, rarely used, but better-reflecting site potential than other growth proxies, (2) climate normals corresponding to the growth period of each stem, and (3) site type (as a function of texture, stoniness, and drainage), which can modify the effects of climate on tree growth. We found a positive effect of vapor pressure deficit on the growth of both species, although the effect on black spruce leveled off. For black spruce, temperatures had a positive effect on the height at 30 years, which was attenuated when and where climatic conditions became drier. Conversely, drought had a positive effect on height under cold conditions and a negative effect under warm conditions. Spruce growth was also better on mesic than on rocky and sub-hydric sites. For portions of the study areas with projected future climate within the calibration range, median height-change varied from 10 to 31% for black spruce and from 5 to 31% for jack pine, depending on the period and climate scenario. As projected increases are relatively small, they may not be sufficient to compensate for potential increases in future disturbances like forest fires.
Victor Danneyrolles, Dominic Cyr, Yves Bergeron, Martin-Philippe Girardin, Sylvie Gauthier, Hugo Asselin. Influences of climate fluctuations on northeastern North America’s burned areas largely outweigh those of European settlement since AD 1850. 2021. Environmental Research Letters 6(11):114007
DOI : 10.1088/1748-9326/ac2ce7
There is a pressing need for a better understanding of changing forest fire regimes worldwide, especially to separate the relative effects of potential drivers that control burned areas. Here we present a meta-analysis of the impacts of climate fluctuation and Euro-Canadian settlement on burned areas from 1850 to 1990 in a large zone (>100 000 km2) in northern temperate and boreal forests of eastern Canada. Using Cox regression models, we tested for potential statistical relationships between historical burned areas in 12 large landscapes (reconstructed with dendrochronological data) with climate reconstructions, changes in the Euro-Canadian population, and active suppression (all reconstructed at the decadal scale). Our results revealed a dominant impact of climate fluctuations on forest burned areas, with the driest decades showing fire hazards between 5 to 15 times higher than the average decades. Comparatively, the Euro-Canadian settlement had a much weaker effect, having increased burned areas significantly only during less fire-prone climate conditions. During periods of fire-prone climate, burned areas were maximum independent of fluctuations in Euro-Canadian populations. Moreover, the development of active fire suppression did not appear to reduce burned areas. These results suggest that a potential increase in climate moisture deficit and drought may trigger unprecedented burned areas and extreme fire events no matter the effects of anthropogenic ignition or suppression.
Henrik Hartmann, Mathieu Lévesque, Yves Bergeron, William Marchand, Martin-Philippe Girardin, Sylvie Gauthier. Contrasting life-history traits of black spruce and jack pine influence their physiological response to drought and growth recovery in northeastern boreal Canada. 2021. Science of the Total Environment 794:148514
DOI : 10.1016/j.scitotenv.2021.148514
An increase in frequency, intensity and duration of drought events affects forested ecosystems. Trees react to these changes by adjusting stomatal conductance to maximize the trade-off between carbon gains and water losses. A better understanding of the consequences of these drought-induced physiological adjustments for tree growth could help inferring future productivity potentials of boreal forests. Here, we used samples from a forest inventory network in Canada where a decline in growth rates of black spruce (Picea mariana (Mill.) B.S.P.) and jack pine (Pinus banksiana Lamb.) occurred in 1988–1992, an exceptionally dry period, to verify if this growth decline resulted from physiological adjustments of trees to drought. We measured carbon and oxygen isotope ratios in growth rings of 95 spruces and 49 pines spanning 1985–1993. We used 13C discrimination (Δ13C) and 18O enrichment (Δ18O) as proxies for intrinsic water use efficiency and stomatal conductance, respectively. We studied how inter-annual variability in isotopic signals was linked to climate moisture index, vapor pressure deficit and annual snowfall amount. We found significantly lower Δ13C values over 1988–1990, and significantly higher Δ18O values in 1988–1989 and 1991 compared to the 1985–1993 averages. We also observed that a low climatic water balance and a high vapor pressure deficit were linked with low Δ13C and high Δ18O in the two study species, in parallel with low growth rates. The latter effect persisted into the year following drought for black spruce, but not for jack pine. These findings highlight that small differences in physiological parameters between species could translate into large differences in post-drought recovery. The stronger and longer lasting impact on black spruce compared to jack pine suggests a less efficient carbon use and a lower acclimation potential to future warmer and drier climate conditions.
Alexis Schab, Jesus Pascual Puigdevall, Yves Bergeron, Sylvie Gauthier, Frédérick Raulier , Osvaldo Valeria. Modeling paludification and fire impacts on the forest productivity of a managed landscape using valuable indicators: the example of the Clay Belt 2021. Can. J. For. Res. 51(9):1347–1356
DOI : 10.1139/cjfr-2020-0386
In areas sensitive to forest management, paludification and successive disturbances in boreal forest can affect forest regeneration negatively, sometimes resulting in stand opening. As these negative effects on forest productivity are not fully considered in strategic management planning, a new landscape dynamics model integrating fire, paludification, forest harvesting, and regeneration failure was used to assess these impacts in a large forest management unit (10,828 km2) of northwestern Québec. Two reforestation scenarios, one based on the accessibility of the areas to be treated and the other aimed at restoring all burned and paludified areas to production were compared to one with no intervention. The success of the scenarios was evaluated using the predicted volume harvested, the proportion of closed or opened stands areas, an indicator of productivity; the cost of reforestation and the royalties associated with harvesting. Harvesting the paludified areas without reforesting would lead to a sharp increase in open stands areas (+17.3%). The strategy of reforesting accessible areas is the most promising for achieving sustainable forest management targets. The monitoring of maximum potential volume (MPV) and the closed forest area as indicators of landscape productivity provides the ability to anticipate problems earlier than with the conventional forest planning indicators.
Ibrahim Djerboua, Yves Bergeron, Sylvie Gauthier, Victor Danneyrolles, Osvaldo Valeria. How Initial Forest Cover, Site Characteristics and Fire
Severity Drive the Dynamics of the Southern
Boreal Forest. 2020. Remote sensing 12(23):3957
DOI : 10.3390/rs12233957
Forest fires are a key driver of boreal landscape dynamics and are expected to increase with climate change in the coming decades. A profound understanding of the effects of fire upon boreal forest dynamics is thus critically needed for our ability to manage these ecosystems and conserve their services. In the present study, we investigate the long-term post-fire forest dynamics in the southern boreal forests of western Quebec using historical aerial photographs from the 1930s, alongside with modern aerial photographs from the 1990s. We quantify the changes in forest cover classes (i.e., conifers, mixed and broadleaved) for 16 study sites that were burned between 1940 and 1970. We then analyzed how interactions between pre-fire forest composition, site characteristics and a fire severity weather index (FSWI) affected the probability of changes in forest cover. In the 1930s, half of the cover of sampled sites were coniferous while the other half were broadleaved or mixed. Between the 1930s and the 1990s, 41% of the areas maintained their initial cover while 59% changed. The lowest probability of changes was found with initial coniferous cover and well drained till deposits. Moreover, an important proportion of 1930s broadleaved/mixed cover transitioned to conifers in the 1990s, which was mainly associated with high FSWI and well-drained deposits. Overall, our results highlight a relatively high resistance and resilience of southern boreal coniferous forests to fire, which suggest that future increase in fire frequency may not necessarily result in a drastic loss of conifers. View Full-Text
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Claire Depardieu, Sylvie Gauthier, William Marchand, Nathalie Isabel, Étienne Boucher, Yves Bergeron, Henrik Hartmann, Martin-Philippe Girardin. Strong overestimation of water-use efficiency responses to
rising CO2 in tree-ring studies. 2020. Global Change Biology 26(8):4538-4558
DOI : 10.1111/gcb.15166
The carbon isotope ratio (?13C) in tree rings is commonly used to derive estimates of the assimilation?to?stomatal conductance rate of trees, that is, intrinsic water?use efficiency (iWUE). Recent studies have observed increased iWUE in response to rising atmospheric CO2 concentrations (C a), in many different species, genera and biomes. However, increasing rates of iWUE vary widely from one study to another, likely because numerous covarying factors are involved. Here, we quantified changes in iWUE of two widely distributed boreal conifers using tree samples from a forest inventory network that were collected across a wide range of growing conditions (assessed using the site index, SI), developmental stages and stand histories. Using tree?ring isotopes analysis, we assessed the magnitude of increase in iWUE after accounting for the effects of tree size, stand age, nitrogen deposition, climate and SI. We also estimated how growth conditions have modulated tree physiological responses to rising C a. We found that increases in tree size and stand age greatly influenced iWUE. The effect of C a on iWUE was strongly reduced after accounting for these two variables. iWUE increased in response to C a, mostly in trees growing on fertile stands, whereas iWUE remained almost unchanged on poor sites. Our results suggest that past studies could have overestimated the CO2 effect on iWUE, potentially leading to biased inferences about the future net carbon balance of the boreal forest. We also observed that this CO2 effect is weakening, which could affect the future capacity of trees to resist and recover from drought episodes.
Martin-Hugues St-Laurent, Yan Boulanger, Dominic Cyr, Francis Manka, Pierre Drapeau, Sylvie Gauthier. Abaisser le taux de couper pour atténuer les impacts des changements climatiques sur la qualité d'habitat du caribou forestier au Québec 15e colloque annuel du CEF, Université de Sherbrooke, Québec (2022-09-29)
Sylvie Gauthier Accident de régénération: importance pour le maintien de la productivité des forêts et stratégies pour pallier leurs impacts. Colloques du SCF-CFL (2021-01-27)
Tadeusz Splawinski, Dominic Cyr, Sylvie Gauthier, Jesus Pascual Puigdevall, Alain Leduc, Nelson Thiffault, Yves Bergeron. Modéliser le potentiel des pratiques sylvicoles pour limiter l'impacts des accidents de régénération sur la productivité forestière 22e colloque de la Chaire AFD. Université du Québec en Abitibi-Témiscamingue, complètement virtuel (2020-12-02)
Mathilde Pau, Sylvie Gauthier, Raphaël Chavardes, Martin-Philippe Girardin, William Marchand, Yves Bergeron. Une nouvelle approche suggère que le réchauffement climatique pourrait augmenter la croissance des arbres en forêt boréale 22e colloque de la Chaire AFD. Université du Québec en Abitibi-Témiscamingue, complètement virtuel (2020-12-02)
Henrik Hartmann, William Marchand, Martin-Philippe Girardin, Yves Bergeron, Nathalie Isabel, Claire Depardieu, Sylvie Gauthier, Étienne Boucher. Effet des changements climatiques sur l’efficience d’utilisation de l’eau de l’épinette noire et du pin gris 21e colloque de la Chaire AFD. Université du Québec en Abitibi-Témiscamingue, Rouyn-Noranda, Québec. (2019-11-30)
Marin Seto, Jean-Pierre Jetté, Alexis Schab, Tadeusz Splawinski, Dominic Cyr, Sonia Légaré, Véronique Christophe, Alexis Leroux, Mathieu Bouchard, Yan Boucher, Jean-Pierre Saucier, Alain Leduc, Osvaldo Valeria, Sylvie Gauthier, Yves Bergeron. La gestion du risque intégrée à la prise de décision en aménagement forestier: le cas des zones sensibles de la forêt boréale. Carrefour Forêts (2019-04-04)
Tadeusz Splawinski, Yves Bergeron, Sylvie Gauthier. Analyse du risque d’accidents de régénération en forêt boréale aménagée 19e colloque de la Chaire AFD. Université du Québec en Abitibi-Témiscamingue, Ste-Germaine-Boulé, Québec. (2017-11-30)
Jeanne Portier, Sylvie Gauthier, Yves Bergeron, Alain Leduc, Dominique Arseneault. Le régime des feux diffère-t-il de part et d'autre de la limite nordique des forêts attribuables du Québec ? 17e colloque de la Chaire AFD. Université du Québec en Abitibi-Témiscamingue, Rouyn-Noranda, Québec. (2015-12-02)
Sylvie Gauthier Les régimes de perturbations et la dynamique des
forêts comme base à l’aménagement durable des
forêts : exemple de l’est du Canada. PIF: (2007-02-08)
Sylvie Gauthier Régime des feux au Québec Colloque sur l’aménagement forestier et le feu, Chicoutimi, Québec, Canada. (2002-04-09)
Daniel Lesieur, Sylvie Gauthier, Yves Bergeron. Historique des feux et dynamique forestière du centre-sud de la forêt boréale du Québec, Canada Colloque sur l’aménagement forestier et le feu, Chicoutimi, Québec, Canada. (2002-04-09)
Sylvie Gauthier Les bases écologiques pour varier les traitements sylvicoles en forêt boréale (Partie 1) Atelier sur les coupes partielles, Chaire industrielle CRSNG-UQAT-UQAM en Aménagement Forestier Durable, Rouyn-Noranda
Sylvie Gauthier Les bases écologiques pour varier les traitements sylvicoles en forêt boréale (Partie 2) Atelier sur les coupes partielles, Chaire industrielle CRSNG-UQAT-UQAM en Aménagement Forestier Durable, Rouyn-Noranda
Dominique Boucher, Sylvie Gauthier. Structural changes in coniferous stands along a chronosequence in the northeastern boreal forest of Quebec 5th international Workshop on Disturbance Dynamics in Boreal forests, Dubna, Russie.
Josée Noël, David F. Greene, Yves Bergeron, Sylvie Gauthier. Recruitment of trees with aerial seedbanks after fire 3rd International Workshop on 3rd International Workshop on Disturbance dynamics in boreal forests. Kuhmo, Finland.
Josée Noël, Sylvie Gauthier, Yves Bergeron. Régénération forestière après feu : composition des peuplements avant incendie et résilience des espèces 68ième congrès annuel de l’ACFAS. Université de Montréal, Québec, Canada.
Daniel Lesieur, Alain Leduc, Karen Harper, Sylvie Gauthier, Yves Bergeron. Calibration des matrices de succession à l'aide des PEP 70ième congrès annuel de l’ACFAS. Université Laval, Québec, Québec, Canada.
Sylvie Gauthier Régime de perturbation, dynamique forestière et aménagement écosystémique sur la Côte Nord 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.