Fall 2023 updates: Disturbance and resistant-focused adaptation
- Amy Wotherspoon
- 11 oct. 2023
- 1 min de lecture
Dernière mise à jour : 24 oct. 2023
To continue our fall 2023 updates, the Silva21 community met on Wednesday, October 11th the Silva21 to discuss ongoing research projects under the theme of disturbance and resistant-focused adaptation. We heard from eight HQPs on multiple research projects! Check out summaries of their updates below.
Vulnerability of North American temperate and boreal tree species to acute climatic events- Sébastien Dumont, PhD student, ULaval
Forest ecosystems are undergoing unprecedented alterations as a result of climate change. In particular, the expected increase in the frequency and intensity of acute climatic events such as drought, late frost, and winter thaw events are likely to adversely affect forests productivity. However, the relationships between these climatic events and forest growth remain poorly understood, in part because they have never been studied on a large scale in North America.
The overall goal of this project is to characterize the vulnerability of Canada's major temperate and boreal forest species to acute climatic events. Specifically, in a first step, Sébastien will quantify on a large scale the effect of different climatic stresses on the growth of forest species according to their geographic distribution. The second step will be to identify site- and stand- level characteristics that enhance the resistance and resilience of species to different climatic stresses. The third chapter of the project will aim to provide a biological explanation for the vulnerability of species according to their leaf phenology at the seedling stage.
To address objectives 1 and 2, Sébastien will use a dendrochronological approach to analyze an unprecedented database of 54,896 tree cores collected on 22,378 sites across Canada and the United States, combined with high-resolution daily climate data. The third objective will be addressed by using foliar phenology as a complementary approach to understand the vulnerability of seedlings of the tree species studied in the TransX assisted migration trial.
Sébastien Dumont
PhD student
Université Laval
Supervisor: Alexis Achim
Continuous forest inventory framework - Chris Mulverhill, Postdoctoral Fellow, UBC
Enhanced forest inventories (EFIs) based on airborne lidar data form a fundamental component of forest management in the 21st century. However, due to high cost of both field and lidar data acquisition, EFIs are only updated on 5- or 10-year repeat intervals. A continuous forest inventory framework has been proposed in order to allow EFIs to be updated on a shorter repeat interval. The components of this framework include establishing the initial EFI, continuously monitoring for change using optical satellite data, updating the attributes of changed cells, and forecasting growth in unchanged cells. Manuscripts outlining the framework (1) and detecting changes using satellite data (2, 3) have been accepted in peer-reviewed publications.
Current work on this project is on updating EFI attributes in changed pixels. While numerous studies have temporally extrapolated forest attributes, they primarily use a single spectral value per year, thereby limiting the ability of sub-annual EFI update. In order to perform EFI update in a near-real time context, input variables derived which describe recent phenological trends for each pixel in the study area. Models are then developed to estimate forest attributes (such as basal area or canopy cover) as a function of spectral index values. Results suggest that attributes such as Lorey’s height have the highest estimation accuracy (r2 ≈ 0.8, 14% relative root mean square error; RMSE%), while attributes such as volume are less accurately predicted using optical data (r2 ≈ 0.78, 30% RMSE%). Future work will aim to apply these models and test their applications in a growth monitoring context of a continuous forest inventory.
Chris Mulverhill
Postdoctoral Fellow, UBC
Supervisor: Nicholas Coops
Project Page
New techniques to assess reestablishment after severe disturbance and prioritization for remediation measures - Sarah Smith-Tripp, PhD candidate, UBC
Satellite images give a broad understanding of forest regrowth after wildfires. However, these spectral observations from satellites do not capture structural forest measures - crucial for silviculture. Some of these key metrics include structural metrics like the proportion of bare ground and stem density. One method to bridge the structural/spectral disconnect between satellite data and ground measures is to compare spectral observations with 3D lidar data. In my research, I employ a spatial and temporal approach, fusing structure data taken in one year with areas that are 5, 8, 12, and 16 years post-fire.
By comparing data from different post-fire years with historical spectral observations, we can better understand how structural trends in forest recovery can be identified from satellite imagery. My research focuses on the Sub-Boreal Spruce region following high-severity stand-replacing fire events from 1984- 2022. In these environments, I found that structural trends are identifiable with spectral data. Importantly, some trends could be classified as 'alert areas', where satellite observations suggest there is or will be a low level of coniferous regrowth sixteen years after the disturbance event.
The ability to identify these alert areas helps target regions that might require more intensive silvicultural interventions to bolster forest recovery. This method of analyzing recovery goes beyond what satellites can provide, offering more detailed insight that can significantly inform and improve forest management practices.
Sarah Smith-Tripp
PhD candidate
UBC
Supervisor: Nicholas Coops
sarahsmith.tripp@alumni.ubc.ca
Thinning as a tool to increase resistance to stressors - Sergio Alonso Sanchez, MSc student, UBC
Forests in the interior of British Columbia are being challenged with unprecedented disturbances, such as insect outbreaks and fires, that compromise the long-term stability of forest stands and resulted in a reduced potential of harvested wood. Therefore, there is a need to identify stands structures with characteristics that can resist to different stressors and there is also evidence that commercial thinning (CT) is a one tool to achieve this objective (Moreau et al., 2022).
Despite being a common silvicultural treatment in many types of forests around the globe, in BC, we still have insufficient operational knowledge and experience to implement CT at a broad scale.
This project aims to, first, study current CT practices in BC, through detailed time studies of CT operations, machine data, LiDAR, and forest inventory and harvesting data. This data helps to understand why machine operators can harvest more or less wood per unit of time, for a particular set of stand conditions. Subsequent analysis will identify the main factors that explain the productivity of the operations.
In the second part, we will implement cutting-edge CT technologies and innovative harvesting layouts in BC while bring know-how from other jurisdictions that have successfully implemented CT for decades. Further, the impacts of the operations on the residual stand can be assessed by measuring conditions of fuels, soils, tree growth response, and different associated ecosystem services and values.
The results of this study could be used to relate over time how the treated stands will respond to different stressors and align with the results of other studies and to boost the successful implementation of CT treatments in BC.
Sergio Alonso Sanchez
MSc student
University of British Columbia
Supervisor: Dominik Roeser
Targeted assisted migration; from theory to implementation - Joao Paulo Czarnecki de Liz, PhD student, ULaval
Climate change poses uncertainties and challenges for forestry practices, necessitating adaptive measures to protect forests and their services. Assisted migration (AM) has emerged as a potential adaptation strategy to conserve ecosystems and maintain forest production. Implementation of AM requires a comprehensive analysis considering various factors. Spatial distribution models (SDMs) incorporating multivariate approaches and topographical factors have become increasingly important in assessing habitat suitability and planning species management. High-resolution terrain data derived from LiDAR facilitates the characterization of terrain microrelief, aspect, slope, and other topographical indexes, enabling a finer-scale representation of ecological processes. While previous research efforts have aimed to support the implementation of AM at an operational scale through various studies and experiments, a more comprehensive characterization of potential sites at the stand level is essential to mitigate risks of failure.
This study focuses on the sugar maple (Acer saccharum), a commercially valuable species in North America expected to shift its range northwards in response to climate change. The objective of this work was to examine the extent to which topographical factors can enhance SM distribution modeling and the degree to which these factors determine sites that are suitable for SM under different future climate scenarios. By examining the responses of sugar maple to biotic and abiotic factors, particularly in its northernmost range, we aim to gain insights into its ecological requirements and develop effective management strategies for its survival and growth.
Our findings suggest that topographical position and aspect are the most significant topographical variables with the potential to enhance sugar maple distribution modeling and explain its presence in the study region. Furthermore, when evaluating climate projections, our results suggest that the species is likely to migrate downslope occupying the valleys through relatively small increases in annual averages of temperature and precipitation. The study area would shift from a small percentage of suitable areas to a small percentage of unsuitable only within the first 30 years of changes under the most optimistic climate scenario (SSP126). These results can support the implementation of AM at stand level scale and with the spatially explicated representations it can provide practical references for practitioners to guide their actions in the field.
The results also highlight that certain changes in specific areas are likely to occur more rapidly than expected, necessitating swift responses to three main questions: To what extent does Sugar Maple align with these habitats' physical, chemical, and biological soil characteristics? Does the existing tree species composition provide sufficient conditions for establishing Sugar Maple in the context of assisted migration, considering competitive and facilitation relationships? And finally, instead of focusing solely on a single-species approach, is the implementation of "Ecosystem Assisted Migration" a plausible paradigm?
Joao Paulo Czarnecki de Liz
PhD student
Université Laval
Supervisor: Alexis Achim
joao-paulo.czarnecki-de-liz.1@ulaval.ca
Supplying assisted migration; from theory to application - Jacob Ravn, PhD student, UNB
As the climate warms, there has been a growing interest in adaptive silvicultural strategies to mitigate the effects of climate change on Canada’s forests. Operational assisted migration (AM), a key reforestation strategy for reducing forest maladaptation to climate change, proposes planting future-adapted populations (typically southern, drier adapted seed sources) of trees further north to improve forest health and performance. While there may be limited knowledge or operational distrust regarding safe seed transfer distances for some species, there are far more practical hurdles impeding this process. One of the biggest is a rapidly growing concern surrounding the simple acquisition of quality seed and seedling stock necessary for large-scale AM programs in North America.
From a research standpoint, recent eastern North American AM research experiments such as TransX and ASCC have both experienced trouble in acquiring relatively small amounts of range-wide, genetically representative seed for common native tree species. This issue scales with size, as large- and small-scale US and Canadian nurseries alike have expressed concerns regarding their capacity to scale-up nursery output of native seed and seedling stock under a status-quo scenario. Genetic diversity and physiological quality are also a concern, with recent surveys and research papers demonstrating a significant homogeneity of seed sources provided by nurseries, with most nurseries providing seed and seedling stock from a very few, select locations. This low portfolio of procurement options can impede the effectiveness of AM projects and research, by lowering acquisition-potential of seed from the best-performing genetic populations for the target management region.
There are many causes of these pervasive issues, and many of these are well-dispersed throughout the seed acquisition-distribution pipeline. Intensive 2022-2023 survey responses from both countries exhibit common trends, all centered on lacking personnel and infrastructure. Many suppliers expressed concerns involving: (i) the quantity of available well-trained seed collectors, growers, and tree planters; and (ii) the capacity for seedling production and space for refrigerated seed storage. US respondents cited an additional barrier of unpredictable demand from government and industry.
Solutions to these problems exist, and many have been proposed. The consistent supply of quality, representative seed could be improved through: (i) increasing pay and standardized training programs for seed collectors; (ii) expanding international collaborative networks and knowledge sharing among governmental, industrial, university, private, and non-profit organizations; (iii) greater infrastructure investment opportunities for the processing and storage of seed; and (iv) identifying collection zones and establishing common sourcing locations within. Additionally, the quantity of seedling stock could improve with: (i) the establishment of stable contracts that reduce risk for growers; and (ii) investment programs for the expansion of nursery infrastructure.
An adequate supply of native, regional seed and seedlings is imperative for the implementation of robust AM research and climate-smart forest management in North America. Under the current and patchy acquisition-distribution framework, scientists and reforestation programs will be severely limited in scale and effectiveness. A concerted, collaborative effort to strengthen this supply, and to sooner involve those planning research funding, is urgently required to actively mitigate the influence of climate change on our forests.
Jacob Ravn
PhD student
University of New Brunswick
Supervisor: Loic D'Orangeville
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