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In the context of global change, a better understanding of the dynamics of wood degradation, and how they relate to tree attributes and climatic conditions, is necessary to improve broad-scale assessments of the contributions of deadwood to various ecological processes and ultimately for the development of adaptive post-disturbance management strategies. This post is a summary of the scientific article "Broad-scale wood dynamics in the face of climate change: a meta-analysis" by Catherine Chagnon, Guillaume Moreau, Christine-Bombardier-Cauffope, Julie Barrette, Filip Havreljuk and Alexis Achim, published in GCB Bioenergy, Volume 14, Issue 9, p 941-958 (https://onlinelibrary.wiley.com/doi/10.1111/gcbb.12951), and has been approved by the corresponding author. A harmonized classification system for visual criteria of deadwood of both standing dead and downed wood debris A harmonized three-class system was created to describe the state of decomposition of both downed and standing woody debris (Fig 1) to simplify data collected within the meta-analysis. This classification is then useful for its use to facilitate comparison with future studies. Both climatic conditions and tree-level variables are important indicators of time since death (TSD) of woody debris Using climatic conditions and tree-level variables obtained using a meta-analysis, linear regression models showed that TSD was best explained using interactions between decay class and the following four variables: Maximum summer temperature; higher temperatures decreased TSD Total annual precipitation; greater precipitation increased TSD Wood density; greater wood density increased TSD Tree phylogeny; TSD was 4.4 years higher in softwoods compared to hardwoods The above four variables accounted for 84% of the variance between observations, which were classified into three main clusters using a PCA-analysis. A decay-class transition rate model was included to account for mean residence time of 75% of the trees being 'out of the system' and classified beyond DC #3 (Fig. 2). Projected warming is likely to accelerate wood decomposition and decrease residence time in the decay stages Using baseline climate data across Europe, mean TSD of deadwood in the first decay class was, on average, ~10 years. Lower values were observed around the Mediterranean and higher values in the Alps, Scotland and southwestern coast of Norway (Fig. 3). Future climate projections show that mean TSD could decrease from 10 years to 6 and 4 years by 2100, according to SSP2-4.5 and SSP5-8.5 scenarios, respectively (Fig. 3). A shorter residence time will change deadwood dynamics, thereby impacting diversity and salvage logging practices Saproxylic biodiversity may be altered due a reduced availability of deadwood of different decomposition stages over time, reducing the amount of available of habitat. This is likely to worsen with rising temperatures. Shorter residence times of deadwood suggests a reduced "shelf life" of dead trees that are used as value-added products. This is especially true for hardwoods in warmer regions where salvage harvesting needs to occur in a shorter period after a disturbance. Climate change and faster decaying wood is likely to affect the carbon footprint, sequestration rate, timing and quantity emissions related to the decomposition of dead trees. A copy of this blog post is available as an Extension Note in PDF format, available in English and French. Corresponding author of article: Catherine Chagnon, M.Sc. Summary and design by Amy Wotherspoon, PhD.

Pour la troisième semaine consécutive, nous rattrapons notre personnel de haute qualité (PHQ) pour un mis à jours des projets de recherche sous le thème 'Adapt'! Dans le cadre d’ADAPTER, la recherche des traitements sylvicoles novateurs et des stratégies de gestion forestière adaptées à la nouvelle réalité socio-environnementale, afin d’assurer la durabilité de l’approvisionnement en fibres partout au Canada. Le mardi 29 novembre, nous avons entendu les PHQ suivants avec des projets sous le thème ADAPT : Cliquez sur un nom pour lire leur résumé Si vous êtes membre de l’équipe Silva21 et vous souhaitez recevoir une copie de toutes les diapositives, veuillez contacter notre coordinateur scientifique(amy.wotherspoon@ubc.ca) Nos prochaines réunions de mise à jour auront lieu au printemps 2023! Restez à l'affût de toutes les nouvelles Silva21 en vous abonnant à notre infolettre au bas de cette page.

Pour suivre les réunions thématiques de novembre, cette semaine nous avons rencontré les PHQ sous le thème « Anticiper »! Dans ANTICIPATER, la recherche vise à améliorer les modèles de croissance et les méthodes de prédictions pour tenir compte de la réalité climatique et synthétiser les risques de perturbation auxquels les forêts sont confrontées Le mercredi 23 novembre, nous avons entendu les PHQ suivants avec des projets sous le thème Anticiper : Cliquez sur un nom pour lire leur résumé: If you are a member of the Silva21 team and would like to receive a copy of all slides, please email our scientific coordinator (amy.wotherspoon@ubc.ca) Our ADAPT meeting takes place next week, so we'll be sure to post summary reports of that as well! Stay tuned!

Chaque 3 à 4 mois, Silva21 se réunit pour présenter les mises à jour de notre personnel hautement qualifié (PHQ). L’an dernier, nous avons organisé ces rencontres par 'hub' pour souligner la recherche qui se fait à proximité géographique. Cette fois-ci, nous avons organisé ces rencontres selon les trois thèmes de recherche de Silva21 : Observer, Anticiper, Adapter. Dans OBSERVER, nous recueillons des données à l’aide d’outils innovants pour évaluer la croissance et la vigueur des arbres pour permettre ainsi des stratégies de gestion plus flexibles et adaptatives face aux stress et aux perturbations climatiques Le mardi 15 novembre, nous avons entendu nos PHQ suivants avec des projets sous le thème Observer : Rangée du haut au bas: Liam Irwin (MSc candidate, UBC), Sarah Smith-Tripp (PhD student, UBC), Gabrielle Thibault (MSc candidate, ULaval), Alexandre Morin-Bernard (PhD candidate, ULaval), Chris Mulverhill (Postdoctoral Fellow, UBC), José Riofrio (Postdoctoral Fellow, UBC). Si vous êtes membre du Silva21 et souhaitez recevoir une copie, veuillez envoyer un courriel à notre coordonnatrice scientifique (amy.wotherspoon@ubc.ca) Nos réunions ANTICIPER et ADAPTER auront lieu plus tard en novembre, alors nous nous assurerons de publier également des rapports summaires.

Boreal forests are experiencing climate change more rapidly than other biomes, which is likely to impact their future management. Understanding how tree growth responds to regional and seasonal variation in climate is essential to anticipate future management of boreal forests. By relating growth-climate relationships to temperature and precipitation, our meta-analysis allows readers to grasp the current growth response of black spruce to climate variation. When combined with climate projections, our results show forest managers the variation in growth response to climate at a given location or region of interest which can help implement adaptive silviculture measures in southern latitudes. Black spruce had greater radial annual growth with greater precipitation, except during the month of April Trees experienced greater radial growth with higher amounts of precipitation in previous years' summer (specifically June - August) and current summer (specifically May - July). On the contrary, precipitation in April was linked to reduced growth. Tree growth in response to previous and current temperature is much more variable (Figure 2). Climate-growth response showed a clear response to latitudinal trends (Figure 1). In southern sites (below 50°N), high temperatures in previous summers (June - August) are linked with lower radial tree growth. By comparison, in northern sites (50-54°N), temperature has a positive effect on growth. This effect switches back to negative above 54°N. Warmer springs also increased tree growth as you move from north to south. Greater precipitation in previous summer improved tree growth consistently across all latitudes. Between 48 and 54°N, greater April precipitation reduced tree growth, but at the start of the growing season (May-June), trees grew in response to more precipitation. This growth decreased as you move from south to north. Adaptive silviculture mitigating drought stress should be prioritized in southern boreal forests This study helps forest managers understand the variation in growth response to climate at a given location or across a region of interest. In southern regions, where further warming is likely to increase moisture limitation faster, there is accelerated risk of reduced boreal forest productivity. In these regions, managers could prioritize the implementation of adaptive silviculture measures such as stand density management and/or assisted migration in sites experiencing reduced growth reductions associated with, or likely to become at risk of, drought stress. This may be less of a priority in regions where annual precipitation is expected to increase, though the projected increase in frequency and severity of drought events may prevent such phenomenon Methodology: 11 dendroclimatology studies, which included 113 sites and 2,995 black spruce trees were used for climate-growth relationships between annual tree rings and precipitation (n=80 sites) and temperature (n=190 sites). A meta-analysis was used to investigate the effects of site conditions on climate-growth response with monthly temperature and precipitation. A copy of this blog post is available as an Extension Note in PDF format, available in English and French Summary based on scientific article: Chagnon, C., Wotherspoon, A.R., Achim, A. 2022. Deciphering the black spruce response to climate variation across eastern Canada using a meta-analysis approach. Forest Ecology and Management 520:120375. https://doi.org/10.1016/j.foreco.2022.120375. Corresponding author: Catherine Chagnon, M.Sc. Summary and design by Amy Wotherspoon, PhD.

Boreal forests are experiencing climate change more rapidly than other biomes, which is likely to impact their future management. Understanding how tree growth responds to regional and seasonal variation in climate is essential to anticipate future management of boreal forests. By relating growth-climate relationships to temperature and precipitation, our meta-analysis allows readers to grasp the current growth response of black spruce to climate variation. When combined with climate projections, our results show forest managers the variation in growth response to climate at a given location or region of interest which can help implement adaptive silviculture measures in southern latitudes. Black spruce had greater radial annual growth with greater precipitation, except during the month of April Trees experienced greater radial growth with higher amounts of precipitation in previous years' summer (specifically June - August) and current summer (specifically May - July). On the contrary, precipitation in April was linked to reduced growth. Tree growth in response to previous and current temperature is much more variable (Figure 2). Climate-growth response showed a clear response to latitudinal trends (Figure 1). In southern sites (below 50°N), high temperatures in previous summers (June - August) are linked with lower radial tree growth. By comparison, in northern sites (50-54°N), temperature has a positive effect on growth. This effect switches back to negative above 54°N. Warmer springs also increased tree growth as you move from north to south. Greater precipitation in previous summer improved tree growth consistently across all latitudes. Between 48 and 54°N, greater April precipitation reduced tree growth, but at the start of the growing season (May-June), trees grew in response to more precipitation. This growth decreased as you move from south to north. Adaptive silviculture mitigating drought stress should be prioritized in southern boreal forests This study helps forest managers understand the variation in growth response to climate at a given location or across a region of interest. In southern regions, where further warming is likely to increase moisture limitation faster, there is accelerated risk of reduced boreal forest productivity. In these regions, managers could prioritize the implementation of adaptive silviculture measures such as stand density management and/or assisted migration in sites experiencing reduced growth reductions associated with, or likely to become at risk of, drought stress. This may be less of a priority in regions where annual precipitation is expected to increase, though the projected increase in frequency and severity of drought events may prevent such phenomenon Methodology: 11 dendroclimatology studies, which included 113 sites and 2,995 black spruce trees were used for climate-growth relationships between annual tree rings and precipitation (n=80 sites) and temperature (n=190 sites). A meta-analysis was used to investigate the effects of site conditions on climate-growth response with monthly temperature and precipitation. A copy of this blog post is available as an Extension Note in PDF format, available in English and French Summary based on scientific article: Chagnon, C., Wotherspoon, A.R., Achim, A. 2022. Deciphering the black spruce response to climate variation across eastern Canada using a meta-analysis approach. Forest Ecology and Management 520:120375. https://doi.org/10.1016/j.foreco.2022.120375. Corresponding author: Catherine Chagnon, M.Sc. Summary and design by Amy Wotherspoon, PhD.