Biology subjects

Bergeron, Y.

Publications and source records attributed to Bergeron, Y..

4 recordsLinked to original sources

bioRxiv2025

Variation in bud phenology, frost tolerance and non-structural carbohydrates among white spruce seed sources on climate-contrasted test sites: implications for assisted migration

To assess the potential impacts of climate change on white spruce local adaptation, six seed sources were evaluated seven years after plantation on two test sites with contrasting growing conditions and latitude in Quebec. Bud set, frost tolerance and analysis of non-structural carbohydrates (NSC) content showed important effects of test sites, seed sources, and their interactions on bud set phenology and growth. The average bud set initiation occurred one week later in the southern site compared to the northern site, whereas the late stage of bud set was similar between sites. Significant differences were observed between seed sources for some phenological stages. Frost tolerance was significantly lower in the southern site and below -12 {degrees}C for all seed sources sampled at the beginning of October. The trend in fructose and glucose content was opposite between sites in September. It decreased from September to October in the southern site and increased in the northern site, while sucrose content showed an opposite pattern, with the southwestern seed source harboring the lowest sucrose content. NSC content was also correlated to frost tolerance. Our study highlighted the crucial role of NSC in cold hardiness to early fall frosts and local adaptation. Implications for assisted migration are discussed.

plant biology↗

bioRxiv2025

High-severity fires undermine resilience of black spruce-dominated boreal forests in eastern North America

Climate-induced fire regime shifts may reduce post-fire resilience of black spruce-dominated (BS; Picea mariana) North American boreal forests. While post-fire vulnerability of immature BS stands has been extensively studied, no study has evaluated simultaneous effects of fire severity and seasonality on the post-fire regeneration of mature (> 60-year-old) BS stands. This study aims to quantify post-fire regeneration levels of BS and co-occurring tree species to assess ecosystem recovery and possible loss of resilience due to regeneration failure. We analyzed effects of seed bank conditions, fire regime characteristics (fire severity and seasonality), and seedbed conditions on BS post-fire regeneration in mature forests in Quebec, Canada. Post-fire regeneration density was extensively surveyed across [~]50 400 km2 through a network of 536 plots that were distributed in 21 fires, which burned between 1995 and 2016. One-third of plots failed to regenerate (< 1750 conifer seedlings/ha) at levels adequate to produce closed-crown forest, whereas one-fifth experienced compositional changes, mainly towards jack pine (JP; Pinus banksiana) dominance. Pre-fire basal area of BS and living Sphagnum ground cover increased BS post-fire regeneration, whereas high-severity crown fires and spring fires reduced it. These findings suggest that mature BS-dominated forests may lose resilience in response to high-severity and spring fires. Given the projected increase in fire severity, and the extension towards an early-fire season in response to climate change, our study suggests that post-fire regeneration failure may become more frequent over the coming decades, with potential negative consequences on ecosystem services that are provided by BS-dominated boreal forests.

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

Dominance of coniferous and broadleaved trees drives bacterial associations with boreal feather mosses

The composition of ecologically important moss-associated bacterial communities seems to be mainly driven by host species, but may also be shaped by environmental conditions related with tree-canopy dominance. The moss phyllosphere has been studied in coniferous forests while broadleaf forests remain understudied. To determine if host species or environmental conditions defined by tree-canopy dominance drives the bacterial diversity in the moss phyllosphere, we used 16S rRNA gene amplicon sequencing to quantify changes in bacterial communities as a function of host species (Pleurozium schreberi and Ptilium crista-castrensis) and forest type (coniferous black spruce versus deciduous broadleaf trembling aspen) in eastern Canada. Forest type, not host species, was the main factor affecting moss phyllosphere bacterial community composition, though the interaction of both variables was significant. Bacterial -diversity was highest in spruce forests, while there was greater turnover ({beta}- diversity) and higher {gamma}-diversity in aspen forests. Unexpectedly, Cyanobacteria were much more relatively abundant in aspen than in spruce forests, with the bacterial family Nostocaceae (Cyanobacteria) differing the most between both forest types. Our results suggest that the increasing change in dominance from coniferous to broadleaf trees due to natural and anthropic disturbances is likely to affect the composition of moss-associated bacteria in boreal forests.

microbiology↗