Responsable
Yves Bergeron
Collaborateurs
Olivier Blarquez, Francine Tremblay, Benoit Lafleur, Igor Drobyshev, Philippe Marchand, Jian-Guo Huang, Pierre Grondin, Rock Ouimet, Julie Godbout
Étudiants
Evick Mestre, Julia Cigana, Maxence Soubeyrand
Problématique
La réponse des espèces (migration vs adaptation) aux changements globaux (oscillations climatiques et régime des perturbations) est au centre des préoccupations scientifiques au niveau international. Le cadre conceptuel du projet s'articule autour de la capacité des peuplements marginaux fragmentés à répondre efficacement aux changements climatiques.
Objectifs
L';objectif général du projet est d’améliorer notre compréhension de l';influence relative du climat et des perturbations sur la dynamique des peuplements fragmentés à la transition entre les forêts tempérées et boréales et de caractériser leur réponse écologique et génétique face aux changements climatiques en cours.
Méthodologie
Nous travaillons sur l’érable à sucre et le cèdre blanc. Ces essences ont été sélectionnées car elles comportent des peuplements très fragmentés le long d’un gradient latitudinal. Le projet aborde la problématique selon trois questions complémentaires soit : i) à l’échelle de l’Holocène, depuis combien de temps les peuplements fragmentés sont-ils présents dans les zones d’étude ? ii) Comment se comparent la reproduction et la croissance des peuplements marginaux par rapport aux peuplements continus? Quels sont les facteurs qui limitent leur expansion? et iii) Modélisation du comportement des peuplements de feuillus tempérés dans une matrice coniférienne.
Retombées escomptées
Prédictions des effets des changements climatiques sur la composition de la forêt boréale. Recommandation quant aux objectifs de l’aménagement écosystémique dans le contexte des changements climatiques.
Applicabilité
Interface entre la forêt tempéré (érablière) et boréale (sapinière)
Livrables
Isabelle Visnadi, Johann Housset, Cécile Leroy, Christopher Carcaillet, Hugo Asselin, Yves Bergeron. Limited recruitment of eastern white cedar (Thuja occidentalis L.) under black spruce canopy at its northern distribution limit. 2019. Ecoscience 26(2):123-132
DOI : 10.1080/11956860.2018.1529725
In the boreal forest of eastern North America, the distribution of eastern white cedar (Thuja occidentalis) is characterized by a latitudinal fragmentation gradient from south to north. Marginal populations could be outposts allowing cedar to expand its presence in the north in response to climate change. This study aimed to characterize the spatio-temporal regeneration dynamics of 20 marginal cedar stands in order to evaluate their expansion capacity into adjacent black spruce stands. Cedar recruitment within marginal cedar stands was mainly by layering, which allowed the species to maintain for a long time in the landscape. However, the rate of expansion of marginal stands into adjacent black spruce stands through seed dispersal was very low (0.28 m.year?1) and it was negatively influenced by distance to seed trees. Substrate had no significant effect. Global warming could lead to increased seed production by cedar, which could favour the species’ expansion at its northern distribution limit. However, global warming could also increase the frequency and severity of wildfires, which would have a negative effect on cedar expansion capacity.
Huaitong Xu, Francine Tremblay, Yves Bergeron. Importance of landscape features and fire refuges on genetic diversity
of Thuya occidentalis L., in boreal fire dominated landscapes. 2018. Cons. Gen. 19(5):1231-1241
DOI : 10.1007/s10592-018-1091-6
The unburned forest remnants of boreal mixed-woods, also known as fire residuals, are essential in providing habitats for disturbance-sensitive species and function as the main source of recolonization of disturbed sites. Forest remnants have been identified as historical or potential reservoirs of genetic diversity in several tree species in fire-prone landscapes. In this study, we investigate the genetic diversity of eastern white cedar (EWC, Thuya occidentalis L.), in forest sites that were affected by different fire regimes. The study area is located in northwestern Quebec, in the Lake Duparquet Research and Teaching Forest (79°10?W–48°30?N). We used 18 polymorphic microsatellite loci to investigate the genetic diversity of eastern white cedar, in forest sites where the fire regime history has been reconstructed to examine the importance of the temporal and spatial continuity of the forest on the genetic diversity of EWC. Three types of landscapes, including; islands within a large lake, fragmented fire refuges (forest patches) and non-fragmented mainland forests were studied. Our results revealed a source-sink dynamic associated with a high level of gene flow. Two of the mainland sites served as the main source of migrants. The level of gene flow in island sites was sufficiently high to counteract the effect of isolation. The fire refuges showed the lowest allelic richness, the highest population differentiation and the fewest number of private alleles. The mean fire-free intervals are much longer in fire-refuges causing environmental isolation through time and higher genetic differentiation. The conservation of large mainland sites should be given careful attention because they maintained high genetic diversity and function as the main source of gene flow. Fire refuges have an intrinsic conservation value in landscapes that are affected by spatially heterogeneous fires because they are important for population persistence through disturbances.
Avancement
En cours
Organismes subventionnaires
FRQNT Équipe, FRQNT - Programme d'échanges à court terme Québec-Chine FRQNT-NSFC, Ouranos, MFFP, Coopérative, CRSNG-RDC, MITACS
Financement annuel
71 000 $
Durée
2018-2023
Dernière mise à jour :
2021-03-28 15:46:11
