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:
Amy Wotherspoon - AN1b: future climate envelopes
Consistent, fine-scale and spatially explicit climate projections were created for Canada’s forested ecozones and managed forests. ClimateNA was used to generate future climate projections using ClimateNA and a 13-global circulation model ensemble under the SSP3-7.0 scenario for 1971-2100.
Across Canada, forests are heading towards a warmer and drier environment with more frequent disturbances. Western Canada is projected to experience warmer summer temperatures (greatest increase of maximum temperatures) with greater relative drying, while Eastern Canada is projected to experience warmer winter temperatures (greatest increase of minimum temperature) and wetter annual conditions in the northeast boreal and Acadia regions.
Future hot and dry summers are a result of increase in degree days above 5°C and fewer number of frost-free days which will result in longer growing seasons. This increases drought-risk in regions that are already experiencing (or projected to experience) limited moisture availability. This will increase the frequency and intensity of forest fires, particularly in dry inland, boreal and Acadian forests. Warmer and wetter winders are a result of fewer frost-free days and an increase in precipitation falling as snow (the result of greater winter precipitation but warmer minimum temperatures). This increases the risk of rain-on-snow events and freeze-thaw cycles, as well as the perpetuation of forest pests.
Following in this direction suggests Canada’s managed forests will see a loss of harvestable wood volume due to drought-induced mortality that will outweigh any benefits gained from greater stand productivity. Canada’s forests are also likely to see a shift towards drought- and disturbance-tolerant species, as well as younger stands composed of early successional species. Therefore, adaptive forest management will need to prepare for shorter harvest seasons with more difficult operations, density management to mitigate drought stress, the promotion of mixedwood stands to increase resistance and resilience to disturbance, the inclusion of no-regret adaptation logging in fire-prone regions (including fire-smart landscapes and salvage logging), as well as potential shifts in commercially important tree species.
Postdoctoral Fellow, UBC
Catherine Chagnon - AN1a: climatic drivers of tree growth
Understanding future climate dynamics is critically important to understand how adaptive management approaches can be developed and applied. However, adjusting growth projections to the new climate reality first requires identification of the key climatic variables that alter tree growth. A first step in this project was to summarize the existing literature on climate-growth relationships, which led to the publication of a meta-analysis on black spruce growth response to climate. As a second step, Catherine Chagnon will be using a dendrochronology approach on existing tree core databases, collected across Canadian forests, as well as new core information from Hub sites with the objective to identify the climatic events and conditions most susceptible to alter tree growth.
Until now, more than 130 000 tree core data and samples representing multiple species have been gathered from different sources. Over 3000 cores from Ontario and Nova Scotia are currently being measured at Université Laval. In the meantime, Catherine is combining the different datasets to create an integrated database that will allow a further investigation of climate-growth relationships across Canada. Two research questions have been identified: 1) what is the influence of climate anomalies (including extreme events like drought, thaw-freeze or winter thaws) on the indexed growth of the dominant species of boreal and temperate forests in Canada; and 2) how does the raw tree growth relate to climate and site characteristics.
Research Associate, ULaval
Christina Howard - AN3a: integration of climate drivers into growth modeling (Quebec focus)
In order to evaluate and implement forest management strategies, we need accurate and reliable climate-sensitive forecasts of where particular trees grow. However, current operational growth models are not fully climate-sensitive or only consider a limited number of species. My overall objective is to fill this information gap by finishing an in-progress tree-growth model focused on Quebec, being developed by Mathieu Fortin, by first modelling tree mortality rates. The first step of my research is to determine the mortality rate of 33 individual species/species groups in Southern Quebec, using permanent sample plot data.
Mortality is a binary variable, and most studies have used the logit link function to model mortality. For this study, at the recommendation of my committee, we are using a complementary log-log link function, which adds flexibility to the models. We have started by creating models with tree-level and plot-level variables, including, but not limited to: dbh, total basal area, species basal area, basal area in larger trees, time since last measured, plot density, and species density. We have accomplished building these simple models for all 33 species/species groups, and are now moving on to adding disturbance and harvest variables into the models. Once this has been accomplished, we will add climate variables into the models, and compare these more complex models to the simpler models to determine the effect of including climate on mortality.
PhD student, UBC
Jamie Ring - AN3b: integration of climate drivers into growth modeling (Acadia focus)
To support climate-sensitive growth and yield modelling in the Acadian Forest Region, an evaluation of two existing tree-list growth and yield models developed for use in the Acadian Forest Region are being evaluated. The results from this evaluation will then be used to inform what model components are a priority (diameter increment, height increment, mortality, ingrowth) for incorporating climate sensitivity. The model evaluations are underway, and a comprehensive summary is being created with model projections from a small subset of Nova Scotia’s permanent sample plot dataset before scaling up to the entire dataset.
M.Sc student, UBC
Florence Leduc - AN1c: impact of climate change on growth of commercial forest species in NS.
My masters project aims to assess the impact of climate change on growth of common tree species in the temperate forests of Nova Scotia, using dendroclimatology. The main objectives are 1) to identify climate factors that influence tree growth, 2) to explore the temporal stability of climate–growth relationships identified, 3) to identify species that benefit from climate change and species that are vulnerable to climate change, and 4) to identify site and stand characteristics that favor a positive growth response to climate change in order to guide silvicultural decisions. The biggest knowledge gap in dendroclimatology is that climate-growth relationships are mostly studied in boreal forests and studies usually focus on one or few species. Nova Scotia presents a great opportunity to study climate because of its large temperature and precipitation gradient. The province also has a variety of ecodistricts and vegetation types, which will be great for comparing trees of the same species growing in different sites and location on the climate gradient. The project will involve dendrochronological analysis of over 2000 trees of 11 species in 740 plots across Nova Scotia. The climate factors that I wish to investigate are mean monthly temperature and precipitation, water availability, growing season length and extreme events such as drought and late spring frost. The next step is to measure all the cores!
MSc student, ULaval
João Paulo Czarnecki de Liz - AN5: targeted assisted migration
At the AGM in Quesnel, we presented the main objectives of this Ph.D. project. We now seek to update the objectives considering the literature review. We also seek contributions to the new arrangement adopted considering our updated hypotheses and that the Ph.D. proposal is being finished.
Previously, the first chapter sought to develop a methodology for weighing several criteria to select species candidates to migrate. After reviewing the literature, we found a robust methodology for that (see in Parks et al., 2018). Finally, we reorganized the chapters to first characterize northern sites and model the distribution of sugar maple. Secondly, to determine suitable habitats for sugar maple, and lastly, to simulate silvicultural prescriptions to favour targeted assisted migration implementation.
We believe that using LiDAR-derived variables will allow refining scale in spatial and climate modeling revealing crucial information regarding sugar maple establishment as well as permitting the production of spatially explicit recommendations tat the stand level to facilitate assisted migration implementation.
João Paulo Czarnecki de Liz
PhD Student, ULaval
Sergio Alonso Sanchez - AN6a: thinning as a tool to increase resistance to stressor
Forests in the interior of British Columbia are being disrupted by unprecedented disturbances that challenge the fiber supply for the industry. In this context, a silvicultural tool that that has awakened great interest is Commercial Thinning (CT) however we have insufficient operational knowledge in BC.
At this moment, we are studying current practices in BC evaluating the productivity and costs of CT operations, the impacts on stand quality, fuels, soils and different ecosystem services and values associated.
In future work, we will look at how can we implement in BC cutting-edge CT technologies and transfer the know-how from other jurisdictions, compare the results and evaluate the implications again on productivity, stand quality and ecosystem services and values. We intend to use a combination of data from the machine on-board-computers with LiDAR and field forest inventories to precisely measure the productivity of the operations and identify the main factors that influence productivity.
Sergio Alonso Sanchez
MSc Student, UBC
Marilou Yarneau - AN7: tree-level response to thinning
In Quebec, the eastern portion of the boreal forest has a wetter climate than the rest of the biome, making the return of fires infrequent. Stands in this area are more likely to be under a gap disturbance regime, creating uneven-aged stands. Most of the harvesting in this area is clearcut harvesting with protection of regeneration and soils. This silviculture is ill-adapted to the natural disturbance regime in place. The result is a homogenization of the structure, age, and composition. This results in a scarcity of old growth stands and a significant loss of biodiversity and associated ecological functions, which are key attributes for our forest to adapt to the changing climate. The primary objective of the study is to determine if partial cuts with harvest rates between 25% and 40% are best suited to the eastern boreal forest by allowing the restoration and maintenance of regeneration, structure, and compositional attributes of nature stands. Results suggest that all partial cutting treatments maintain the stand structure after cutting, which clear cutting does not allow before at least 50 years. Results also suggest that partial cut with harvest rate of 40% allows a greater number of seedlings in the regeneration. However, there’s no effects of the treatments on the complexity of the regeneration composition. The latter seems rather to be explained by other factors such as the composition of the substrate. It is important to mention that light certainly has a predominant effect in explaining the regeneration, but it is not taken into account for the moment due to data collection issue. Silviculture based on partial cutting could contribute to the maintenance of old-growth attributes more than a silviculture based on clearcutting for Quebec’s eastern boreal forest. Other analysis are still necessary before understanding the involvement of biotic and abiotic factors in the explanation of regeneration.
M.Sc. Student, ULaval
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