Biology subjects

Boulanger, Y.

Publications and source records attributed to Boulanger, Y..

6 recordsLinked to original sources

bioRxiv2025

Climate change has already reshaped North American forest pest dynamics: Insights from multidecadal process-based modelling

Ongoing anthropogenic climate change has the potential to modify the population dynamics of forest pest insects by shifting the distribution of suitable climate conditions for their development. We used processed-based temperature-driven physiological models to assess the impact of changing climate conditions between 1951 and 2022 across North America on eight important forest pest insects, namely western spruce budworm, eastern spruce budworm, spongy moth, hemlock woolly adelgid, mountain pine beetle, southern pine beetle, spruce beetle and emerald ash borer. Our analyses revealed substantial changes in climate suitability resulting in pronounced northward and elevational shifts for most pest species although the magnitude and spatial patterns of these shifts varied both geographically and among species. We also showed that shifts in highly suitable conditions were more important at the colder edge (either northern or upper elevation) than at the warmer boundaries for several species, either driven by the Arctic amplification or elevation-dependant warming. Our results indicated that both the total area and the host tree biomass exposed to highly suitable climate conditions have increased for many pest species over the last decades, further exposing ecosystems to elevated risk. Our analyses also identified areas (e.g., western Canada) that are increasingly exposed to overlapping, potentially cumulative and interacting, biological disturbances. We also showed that climate change has already contributed to increasing the climatic suitability and geographic spread of exotic forest pest species in North America. Changes in climate suitability over the past seven decades across North America likely represent early signals of continued and potentially accelerating shifts under ongoing anthropogenic climate forcing. In this context, efforts to limit the expansion of pest populations under future climate change scenarios will be key to mitigating their cultural, ecological and economic impacts.

physiology↗

bioRxiv2024

Recent climate change strongly impacted the population dynamic of a North American insect pest species

Climate change is redefining the dynamics of forest ecosystems globally, particularly through its impact on forest pest populations such as the spruce budworm (SBW, Choristoneura fumiferana [Clem.]), a major defoliator in North American boreal forests. This study investigates the shifts in the population dynamics of spruce budworm across its range in response to recent climate change. We used a process-based, temperature-dependent ecophysiological model combined with the ERA5 reanalysis to assess changes in SBW phenology, reproduction rate, winter survival and population growth rates from 1950 to 2022 across North America. Our findings demonstrate a pronounced northward expansion of suitable climate conditions for SBW, accompanied by earlier phenological events and increased reproduction rates in northern regions. Conversely, the southern parts of its range are experiencing increased winter mortality due to warmer temperatures. This study highlights the significant impact of elevated temperatures, particularly during critical developmental windows such as spring and summer, which are pivotal for spruce budworm survival and reproduction. Additionally, our results reveal that the observed shifts in pest dynamics are more strongly driven by climate change than by changes in landscape composition and structure. We estimated that suitable growth rates have shifted northward by over 68 km on average, but this shift reached more than 200 km in the easternmost portions of its range. Climate-induced shift in suitable conditions for SBW underscores the need for adaptive forest management strategies that consider the rapid ecological changes and the potential for increased forest vulnerability due to climatic and biotic stressors. This study provides vital insights that can inform adaptive management ensuring the sustainability of forest ecosystems in the face of ongoing climate change.

ecology↗

bioRxiv2024

The 2023 wildfire season in Quebec: an overview of extreme conditions, impacts, lessons learned and considerations for the future.

The 2023 wildfire season in Quebec set records due to extreme warm and dry conditions, burning 4.5 million hectares and indicating persistent and escalating impacts associated with climate change. The study reviews the unusual weather conditions that led to the fires, discussing their extensive impacts on the forest sector, fire management, boreal caribou habitats, and particularly the profound effects on First Nation communities. The wildfires led to significant declines in forest productivity and timber supply, overwhelming fire management resources, and necessitating widespread evacuations. First Nation territories were dramatically altered, facing severe air quality issues and disruptions. While caribou impacts were modest across the province, the broader ecological, economical, and social repercussions were considerable. To mitigate future extreme wildfire seasons, the study suggests changes in forest management practices to increase forest resilience and resistance, adapting industrial structures to new timber supplies, and enhancing fire suppression and risk management strategies. It calls for a comprehensive, unified approach to risk management that incorporates the lessons from the 2023 fire season and accounts for ongoing climate change. The study underscores the urgent need for detailed planning and proactive measures to reduce the growing risks and impacts of wildfires in a changing climate.

ecology↗

bioRxiv2022

Long-term effect of forest harvesting on boreal species assemblages under climate change

Logging is the main human disturbance impacting biodiversity in forest ecosystems. However, the impact of forest harvesting on biodiversity is modulated by abiotic conditions through complex relationships that remain poorly documented. Therefore, the interplay between forest management and climate change can no longer be ignored. Our aim was to study the expected long-term variations in the assemblage of bird and beetle communities following modifications in forest management under different climate change scenarios. We developed species distribution models to predict the occurrence of 87 species of birds and beetles in eastern Canadian boreal forests over the next century. We simulated three climate scenarios (baseline, RCP4.5 and RCP8.5) under which we varied the level of harvesting. We also analyzed the regional assemblage dissimilarity by decomposing it into balanced variations in species occupancy and occupancy gradient. We predict that forest harvesting will alter the diversity by increasing assemblage dissimilarity under all the studied climate scenarios, mainly due to species turnover. Species turnover intensity was greater for ground-dwelling beetles, probably because they have lower dispersal capacity than flying beetles or birds. A good dispersal capacity allows species to travel more easily between ecosystems across the landscape when they search for suitable habitats after a disturbance. Regionally, an overall increase in the probability of occupancy is projected for bird species, whereas a decrease is predicted for beetles, a variation that could reflect differences in ecological traits between taxa. Our results further predict a decrease in the number of species that increase their occupancy after harvest under the most severe climatic scenario for both taxa. We anticipate that under severe climate change, increasing forest disturbance will be detrimental to beetles associated with old forests but also with young forests after disturbances.

ecology↗

bioRxiv2022

Effects of global change on animal biodiversity in boreal forest landscape: an assemblage dissimilarity analysis

Despite an increasing number of studies highlighting the impacts of climate change on boreal species, the main factors that will drive changes in species assemblages remain ambiguous. We quantify two climate-induced pathways based on direct and indirect effects on species occupancy and assemblage dis-similarity under different harvest management scenarios. The direct climate effects illustrate the impact of climate variables while the indirect effects are reflected through the changes in land cover composition. To understand the main causes in assemblage dissimilarity, we analyze the regional and the latitudinal species assemblage dissimilarity by decomposing it into balanced variation in species occupancy and occurrence and occupancy and occurrence gradient. We develop empirical models to predict the distribution of more than 100 bird and beetle species in the Cote-Nord region of Quebec over the next century. Our results show that the two pathways are complementary and alter biodiversity, mainly caused by balanced variation in species occupancy and occurrence. At the regional scale, both effects have an impact on decreasing the number of winning species. Yet, responses are much larger in magnitude under mixed climate effects (a mixture of direct and indirect effects). Regional assemblage dissimilarity reached 0.77 and 0.69 under mixed effects versus 0.09 and 0.10 under indirect effects for beetles and birds, respectively, between RCP8.5 and baseline climate scenarios when considering harvesting. Therefore, inclusion of climatic variables considers aspects other than just those related to forest landscapes, such as life cycles of animal species. Latitudinally, assemblage dissimilarity increased following the climate conditions pattern. Our analysis contributes to the understanding of how climate change alters biodiversity by reshaping community composition and highlights the importance of climate variables in biodiversity prediction.

ecology↗

bioRxiv2020

Boreal forests will be more severely affected by projected anthropogenic climate forcing than mixedwood and northern hardwood forests in eastern Canada

ContextIncreased anthropogenic climate forcing is projected to have tremendous impacts on global forest ecosystems, with northern biomes being more at risk. ObjectivesTo model the impacts of harvest and increased anthropogenic climate forcing on eastern Canadas forest landscapes and to assess the strong spatial heterogeneity in the severity, the nature and direction of the impacts expected within northern forest regions. MethodsWe used LANDIS-II to project species-specific aboveground biomass (AGB) between 2020 and 2150 under three climate (baseline, RCP 4.5 and RCP 8.5) and two harvest (baseline harvest, no harvest) scenarios within four forest regions (boreal west, boreal east, mixedwood and northern hardwood). ResultsClimate change impacts within the boreal forest regions would mainly result from increases in wildfires activity which will strongly alter total AGB. In the mixedwood and northern hardwood, changes will be less important and will result from climate-induced growth constraints that will alter species composition towards more thermophilous species. Climate-induced impacts were much more important and swifter under RCP 8.5 after 2080 suggesting that eastern Canadas forests might cross important tipping points under strong anthropogenic climate forcing. ConclusionsBoreal forest regions will be much less resilient than mixedwood or northern hardwoods to the projected changes in climate regimes. Current harvest strategies will interact with anthropogenic climate forcing to further modify forest landscapes, notably by accelerating thermophilous species AGB gain in southernmost regions. Major changes to harvest practices are strongly needed to preserve the long-term sustainability of wood supply in eastern Canada. Adaptation strategies should be region-specific.

ecology↗