1,843 results
Search Results
2. Genetic variation in growth and leaf traits associated with local adaptation to climate in yellow birch (Betula alleghaniensis Britton).
- Author
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Maloney, A., Dang, Q.L., Godakanda, P.M., and Thomson, A.
- Subjects
CLIMATE change adaptation ,BIRCH ,LEAF growth ,GENETIC variation ,CARBON isotopes - Abstract
Understanding patterns of variation in functional traits of hardwood trees is crucial for conserving and managing North American temperate forests under climate change. This study examined provenance variation of yellow birch (Betula alleghaniensis Britton) in growth, biomass allocation, leaf morphology, and stable carbon isotope composition. Trees were grown from 10 seed sources originating from across Canada and the northern USA. Height and diameter were not significantly related to climate at seed origin, suggesting that variation may be better explained by site factors, such as soil pH and soil moisture. In contrast, carbon isotope composition and leaf morphological traits were significantly correlated to climate variables including temperature, precipitation, and solar radiation. Provenances from warmer, drier localities tended to have higher stable carbon isotope ratio (δ
13 C), greater specific leaf area, and narrower leaf width than their counterparts from cooler, wetter climates. Thus, variation in leaf morphological traits appears to be involved in adaptation of yellow birch to variation in temperature and moisture availability across the species' range. Our results suggest that there may exist potential for selection and breeding of drought-resistant yellow birch genotypes to aid in reforestation under climate change. [ABSTRACT FROM AUTHOR]- Published
- 2024
- Full Text
- View/download PDF
3. Field testing of a physical impact mill in the Canadian Prairies.
- Author
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Tidemann, Breanne D., Harker, K. Neil, Beckie, Hugh J., Kubota, Hiroshi, Zuidhof, Jennifer, and Reid, Patty
- Subjects
HERBICIDE resistance ,WEED control ,SEED harvesting ,WEED seeds ,PRAIRIES ,WEEDS - Abstract
Herbicide resistance in western Canada has increased interest in alternative weed management strategies. Physical impact mills, a form of harvest weed seed control, have been identified as a strategy that may be well suited for Canadian use. The efficacy of the Harrington Seed Destructor, a physical impact mill, was evaluated in 20 producer fields in Alberta on a wide spectrum of weed species over 3 years. Significant differences in weed densities between the physical impact mill treatment and the regular harvest densities were few; however, some population density reductions were observed. Measurable reductions in weed densities may have been limited by the short timeframe of the experiment, the high initial densities of the weeds, or the targeted weed species having dormancy or longer term seedbanks. Additionally, identified knowledge gaps on how best to optimize physical impact mill efficacy may have reduced the efficacy of the physical impact mill in this study. This study showed no conclusive evidence for the efficacy of a physical impact mill on tested weed species under field conditions. However, it did provide a number of important considerations for future studies. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
4. Revisiting the origins of glyphosate-resistant giant ragweed (Ambrosia trifida L.) in Canada.
- Author
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Page, Eric R., Martin, Sara, Meloche, Sydney, Thibodeau, Alyssa, Nurse, Robert E., Sikkema, Peter H., Tardif, François J., Cowbrough, Michael J., and Laforest, Martin
- Subjects
RAGWEEDS ,AMBROSIA artemisiifolia ,GLYPHOSATE ,PROLINE - Abstract
Glyphosate-resistant giant ragweed (Ambrosia trifida L.) was first identified in Canada in 2008. Although early studies attributed resistance in this species solely to non-target site mechanisms, the presence of a proline (P) to serine (S) mutation at position 106 of EPSPS2 in common and giant ragweed has recently been reported. The objective of this research was (i) to determine whether a P106S mutation is present in historical samples of giant ragweed seed collected from the site of the first report of glyphosate resistance, and (ii) to determine the frequency and distribution of P106S in resistant and susceptible biotypes collected as part of historical surveys throughout southwestern Ontario. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
5. Tillage effects on growing season nitrous oxide emissions in Canadian cropland soils.
- Author
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Pelster, David E., Matteau, Jean-Pascal, Farrell, Richard, and Hernandez Ramirez, Guillermo
- Subjects
GREENHOUSE gases ,GROWING season ,NITROUS oxide ,TILLAGE ,GREENHOUSE gas mitigation ,TUNDRAS - Abstract
Minimizing tillage has been promoted as an agricultural practice that may mitigate greenhouse gas emissions through carbon sequestration. However, there is some ambiguity regarding the effect of minimum tillage (MT) on emissions of other greenhouse gases, in particular soil nitrous oxide (N
2 O) emissions. To determine how effective MT could be in helping Canada mitigate greenhouse gas emissions, we used a meta-analysis to compare growing season N2 O emissions from MT versus conventional tillage (CT). Overall, MT had 12% lower N2 O emissions compared to CT (P = 0.03). However, there was high variability due to soil texture and growing season precipitation (GSP), with MT tending to emit more N2 O than CT in climates where GSP exceeded 600 mm, particularly for soils with sand content less than 60%. Therefore, unless long-term tillage trials, which are urgently needed in eastern Canada, show a reduction in N2 O emissions over time, MT should be used as a greenhouse gas mitigation measure only in dry climates or on sandy soils. [ABSTRACT FROM AUTHOR]- Published
- 2024
- Full Text
- View/download PDF
6. An economic review of conservation tillage practices: select case studies from the eastern Prairies of Canada.
- Author
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Khakbazan, M., Carew, R., Crittenden, S., Mohr, R.M., and Biswas, D.K.
- Subjects
NO-tillage ,CONSERVATION tillage ,CANOLA ,CLAY loam soils ,SOIL conservation ,WHEAT ,LOAM soils - Abstract
This study reviewed the literature on soil conservation practices and analyzed four case studies in different soil zones and diverse cropping systems of Manitoba (MB), western Canada, to show the potential impacts of no-till/reduced tillage practices on field crop economic performance. Primary and secondary data, such as tillage type, input cost, crop price, crop yield, and net revenue (NR), were used to assess the tillage practices in each of the case studies. Based on crop economic analysis, over 9 years (1998–2006) in southern Manitoba, cereal-based (spring wheat (Triticum aestivum L.) and barley (Hordeum vulgareL.)) cropping systems were more profitable under conservation tillage than conventional tillage practices, whereas the opposite was true for oilseed crops (e.g., canola, Brassica napus L.). In plot-scale studies at Portage, MB, low intensity tillage increased NR for soybean (Glycine max L.) in 1 of 3 years when compared to high intensity tillage, and there appeared to be lower NRs for canola as tillage intensity increased. However, in studies near Brandon, MB, NRs for a 4-year wheat-pea (Pisum sativum L.) rotation were lower in low disturbance seeding than high disturbance seeding systems for a clay loam soil but similar for a loam soil. While no single tillage system was found to consistently provide the highest NR based on these case studies, these findings provide insights into some of the factors behind decisions surrounding tillage management and the rationale for the continued use of a combination of conventional, reduced, and zero-till systems in the eastern Prairies of Canada. [ABSTRACT FROM AUTHOR]
- Published
- 2024
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7. Crop yields under no-till in Canada: implications for soil organic carbon change.
- Author
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VandenBygaart, A.J. and Liang, B.C.
- Subjects
NO-tillage ,CROP yields ,GREENHOUSE gases ,CARBON in soils ,SOIL classification ,SOIL texture - Abstract
Crop yields directly affect carbon (C) inputs into soils. Tillage management can influence crop performance, and as such should be considered when quantifying soil organic carbon (SOC) change, and thus net greenhouse gas emissions from croplands for national greenhouse gas inventory reporting. We conducted a meta-analysis of the effects of no-tillage (NT) and conventional tillage (CT) on crop yields for multiple crop species, soil types, and climatic regions of Canada. Yield response to NT varied between western and eastern Canada. Regardless of crop type, experiment duration, soil texture, and residue management, experiments in eastern Canada showed an average of 6% lower yields (p ≤ 0.005) under NT compared to CT. In western Canada, crop type had an important effect on yields between NT and CT with wheat, canola, and legumes exhibiting 10% (p ≤ 0.001), 7% (p ≤ 0.05), and 9% (p ≤ 0.05) higher yields on average under NT compared to CT, respectively. In western Canada, higher yields would be reflected in a similar scale of higher C inputs to NT systems. A recent meta-analysis of the effects of tillage management on SOC in Canada showed an 8% higher storage of SOC under NT systems compared to CT, a difference limited to western Canadian soils. Incorporating the effect of tillage on C inputs will lead to improvements in the accuracy of the effects of tillage management on SOC change in Canadian cropland. The activity data can be improved by applying weightings to the yield data by site-specific assessment of tillage practices across Canada. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
8. Assessing future climate trends and implications for managed forests across Canadian ecozones.
- Author
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Wotherspoon, A.R., Achim, A., and Coops, N.C.
- Subjects
ECOLOGICAL zones ,FORESTS & forestry ,FOREST dynamics ,TREE growth ,BIOMES ,COASTAL forests ,LANDSLIDES - Abstract
Climate change interacts with ecological processes leading to changes in tree and forest growth rate, biome shifts and species composition, all of which are influenced by disturbances. This study explores future overarching climate trends of eight of Canada's ecozones containing managed forests. For the 2071 to 2100 period, climate projections indicate a warming trend of up to an additional 5.5 °C and an overall increase in annual precipitation. Future trends suggest marked contrast between coastal and interior forests and polarization between western and eastern forests. Warmer temperatures, accumulating degree-days above 5 °C and frost-free days suggest longer and drier growing seasons and greater risk of drought particularly in moisture-limited areas such as montane cordillera, taiga shield and boreal shield ecozones. Warmer temperatures and rising precipitation combined with less snow suggest shorter and wetter future winters. This indicates greater risk of rain-on-snow and freeze-thaw events, flooding and landslides particularly in coastal ecozones. We discuss how these projections are likely to result in shifts in dominant species and abundance, which when coupled with the cumulative effects of future disturbances, is likely to alter future forest dynamics and impact harvestable wood volumes for Canada's forestry industry. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
9. Sugar maple sap, soil, and foliar chemistry in response to non-industrial wood ash fertilizer in Muskoka, Ontario.
- Author
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Conquer, Shelby M., Yan, Norman D., and Watmough, Shaun A.
- Subjects
WOOD ash ,SUGAR maple ,MAPLE syrup ,FOREST soils ,SOIL horizons - Abstract
Non-industrial wood ash may be an effective forest soil nutrient supplement but its use in Canada is largely restricted because of unknown concentrations of trace metal contaminants. Sugar maple (Acer saccharum Marshall) is particularly sensitive to low soil calcium (Ca) levels, and though maple syrup is of great economic importance in Canada, it is unknown how wood ash could affect sap chemistry. Non-industrial wood ash (NIWA; 6 Mg·ha
−1 ) applied to experimental plots in Muskoka, Ontario was rich in Ca (27%), while metal concentrations were well below provincial regulatory limits. One-year post-application, significant increases were observed in the treated plots in the soil pH and base cations (Ca, K, and Mg) in the surface soil horizons, and metal concentrations in the litter. Sap yield in the control plots was significantly lower in the first-year post-application than in the second year, but no other differences were found. In both tapping years, sap sweetness remained similar and differences in nutrient and metal concentrations between treatments were generally small and inconsistent. Foliar chemistry remained largely unchanged 1 year following application, except for K that was twice as high in the treated plots. Ultimately, NIWA is unlikely to significantly alter sugar maple sap chemistry, indicating that it is a viable nutrient supplement that can enhance soil fertility in sugar bushes with no impact on sap sweetness. [ABSTRACT FROM AUTHOR]- Published
- 2024
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10. Icing and aufeis in cold regions II: consequences and mitigation.
- Author
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Turcotte, B., Dubnick, A., and McKillop, R.
- Subjects
- *
HYDRAULIC structures , *WATER table , *SPRING , *INFRASTRUCTURE (Economics) , *ICE ,COLD regions - Abstract
The process of icing and the resulting layered ice masses, called aufeis, are caused by the freezing of overflow originating from groundwater or surface water. Aufeis can directly impact infrastructure and property, most commonly through winter ice formation and spring flooding within, against, and on the surface of hydraulic structures and transportation infrastructure. They also represent a safety concern for drivers. This geohazard often needs to be managed proactively and efficiently to mitigate associated risks. This paper provides an overview of the consequences of aufeis in northwestern Canada. A total of 50 existing and novel icing and aufeis mitigation approaches are described and classified. The context of applicability for each approach is identified, considering the source of water, the type of infrastructure, and its role in the formation of aufeis. Finally, future research avenues to support the development or improvement of aufeis risk reduction techniques are presented. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
11. Updating the Foodbot Factory serious game with new interactive engaging features and enhanced educational content.
- Author
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Franco-Arellano, Beatriz, Brown, Jacqueline Marie, Daggett, Quinn, Lockhart, Courtney, Kapralos, Bill, LeSage, Ann, and Arcand, JoAnne
- Subjects
- *
HEALTH education , *OBESITY , *DEEP learning , *AESTHETICS , *AUGMENTED reality , *BEHAVIOR , *COGNITION , *HEALTH literacy , *RESEARCH funding , *DESCRIPTIVE statistics , *CHILDREN'S health , *GAMIFICATION , *VIDEO games , *NUTRITIONAL status , *DIFFUSION of innovations , *EDUCATION , *CHILDREN - Abstract
Serious games (i.e., digital games designed for educational purposes) can foster positive learning attitudes and are increasingly used as educational tools. Foodbot Factory is a serious game application (app) that helps children learn about healthy eating based on Canada's Food Guide principles and has demonstrated to increase nutrition knowledge among this group. This paper describes the process followed to expand Foodbot Factory's educational content and integrate immersive technologies and innovative features into the app. The revision process, which was guided by the Obesity-Related Behavioral Intervention Trials model, included the following phases: first, an interdisciplinary team of nutrition scientists, education experts, and computer scientists analyzed data from the original pilot study, recently published literature, and feedback from stakeholders to define areas to improve Foodbot Factory. The five original Foodbot Factory modules were evaluated by the team during weekly meetings, where the educational content, interactive features, and other elements that required updates (e.g., aesthetics and accessibility) were identified. Second, prototypes were created and refined until a final version of Foodbot Factory was approved. Nineteen children tested the updated Foodbot Factory and found it "easy to use" (89%) and "fun" (95%). The new version of Foodbot Factory contains 19 learning objectives, including 13 original and six new objectives. Interactive engagement features in the updated Foodbot Factory included augmented reality incorporated into two learning modules; new mini-games were created, including a memory game; an overhaul of the aesthetics; (e.g., new food images); and accessibility features were included to support users with cognitive and vision disabilities. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
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12. PbIso: an R package and web app for calculating and plotting Pb isotope data.
- Author
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Armistead, Sheree E., Eglington, Bruce M., and Pehrsson, Sally J.
- Subjects
- *
WEB-based user interfaces , *ISOTOPES , *RADIOISOTOPES , *CANADIAN provinces - Abstract
The package PbIso is a free and open R toolbox for commonly used calculations and plots of Pb–Pb isotope data and for generating Pb evolution models. In this paper, we review Pb isotope systematics and the calculations that are commonly used, such as model age, model source μ (238U/204Pb), time-integrated κ (232Th/238U), and initial Pb isotope ratios. These equations are implemented into R functions in the package PbIso. In addition, functions are provided for generating Pb evolution models, paleoisochrons, and isochrons. This allows users to apply calculations to their data in a straightforward way while providing transparency and flexibility of the calculations used. We have implemented some basic features of the PbIso package into an online shiny R application (see https://shereearmistead.github.io/software/pbiso), which makes it easy for users without any R experience to use these calculations with their own data and to generate plots. We have provided a case study from the Superior Province in Canada, showing how different Pb evolution models can be generated in PbIso and compared to Pb isotope data. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
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13. Picea × darwyniana Björk & Goward: an invalid taxonomic name.
- Author
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Strong, W.L
- Subjects
WHITE spruce ,TWIGS - Abstract
Picea × darwyniana Björk & Goward was recently proposed to replace Picea albertiana S. Brown as the representative taxon for the hybrid offspring of Picea glauca (Moench) Voss and Picea engelmannii Parry ex Engelm., but should be considered invalid for three reasons. First, the proponents failed to document in any way that the P. albertiana isotypes were Picea glauca × mariana Little & Pauley hybrids, as they claimed. Secondly, the P. albertiana isotypes lacked pubescent twigs, purple markings on their seed cones, and denticulate cone-scale margins, which are characteristics of P. glauca × mariana. This indicates a misinterpretation of the P. albertiana parentage. Lastly, P. × darwyniana appears to be an example of P. albertiana ssp. ogilviei Strong & Hills. As the latter is an earlier and validly published name, P. × darwyniana is an illegitimate replacement for plants within the P. glauca × engelmannii (=P.a. ssp. albertiana) and P. engelmannii × glauca (=P.a. ssp. ogilviei) circumscriptions based on naming priority. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
14. Slope risk management in light of uncertainty and environmental variability—2021 Canadian Geotechnical Colloquium.
- Author
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Macciotta, Renato
- Subjects
- *
ROCKFALL , *LANDSLIDES , *CONFERENCES & conventions , *CLIMATE change , *GEOTECHNICAL engineering , *WEATHER - Abstract
Landslides are common across Canada and they pose hazards to human safety, economic activities, and the environment. Robust risk management strategies are necessary for sustainable development. A slope risk management framework has been adopted by the geotechnical community for approximately four decades allowing a systematic, consistent and transparent framework for managing risks. Implementing this framework is associated with uncertainties embedded in our estimates of risk. This paper presents a brief summary of the sources and categories of uncertainty in geotechnical slope engineering and focuses on two topics: (1) estimates of uncertainty in risk calculations and (2) temporal changes in landslide likelihood as a function of weather and steps towards estimating landslide risk changes with climate change. The paper argues that a quantitative risk assessment should not focus on the final risk calculation, but the overall knowledge gained. This allows comprehensive documentation of sources of uncertainty and how they impact geotechnical and risk assessments. Furthermore, the paper outlines approaches to define quantitative correlations between rock fall occurrences and weather, which can be leveraged to estimate changes in rock fall risk with climate change. The paper corresponds to, and expands on, the 2021 Canadian Geotechnical Colloquium. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
15. Productivity, nutritive value, and profitability of high-digestibility alfalfa cultivars harvested at two stages of development in eastern Canada.
- Author
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Boucher, Marie-Soleil, Tremblay, Gaëtan F., Seguin, Philippe, Thériault, Mireille, Charbonneau, Édith, Laroche, Jean-Philippe, Bertrand, Annick, Claessens, Annie, Bélanger, Gilles, and Halde, Caroline
- Subjects
ALFALFA ,CULTIVARS ,FEED analysis ,VALUE (Economics) ,HARVESTING ,DAIRY cattle - Abstract
Alfalfa (Medicago sativa L.) cultivars developed for improved digestibility by conventional breeding or genetic modification have not been evaluated in eastern Canada. This study compared yield, nutritive value, and profitability of two reduced-lignin genetically modified (GM) cultivars, three conventionally selected for low lignin or high pectin, and one population with improved stem degradability, with two commercially adapted cultivars as controls. Alfalfa was harvested at the early bud (intensive management) or early flower (extensive management) stage of development during the first post-seeding year at three sites and the second post-seeding year at one site. All cultivars/populations had similar annual dry matter (DM) yields, except for the lower DM yield (−20%) of the improved stem degradability population. Conventionally selected cultivars for improved digestibility did not differ from control cultivars for in vitro DM digestibility (IVTD) and neutral detergent fiber digestibility (NDFd). Reduced-lignin GM cultivars, however, had a greater IVTD and NDFd (+10%) and less lignin (−10%) than control cultivars at the same stage of development. Reduced-lignin GM cultivars under extensive management had similar NDFd and greater annual DM yield (+1 to 2 Mg DM ha
−1 ), but reduced total digestible nutrients (−41 to 44 g kg−1 DM), in comparison to control cultivars under intensive management. Using partial budget analysis, the comparison of more digestible GM cultivars to the control cultivars resulted in an increase in annual farm net profits ranging from CAD$7.40 to $79.60 cow−1 year−1 depending on stage of development at harvest. Further investigations are needed to quantify the performance of dairy cows fed cultivars with improved digestibility. [ABSTRACT FROM AUTHOR]- Published
- 2023
- Full Text
- View/download PDF
16. A science and management partnership to restore coregonine diversity to the Laurentian Great Lakes.
- Author
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Bunnell, David B., Ackiss, Amanda S., Alofs, Karen M., Brant, Cory O., Bronte, Charles R., Claramunt, Randall M., Dettmers, John M., Honsey, Andrew E., Mandrak, Nicholas E., Muir, Andrew M., Santucci Jr, Victor J., Smith, David R., Strach, Russell M., Sweka, John A., Weidel, Brian C., Mattes, William P., and Newman, Kurt R.
- Subjects
- *
MANAGEMENT science , *ADAPTIVE natural resource management , *FISHERY management , *BIOLOGICAL extinction , *LAKES , *INDIGENOUS fishes , *FRESHWATER biodiversity , *FRESHWATER habitats - Abstract
Similar to many freshwater ecosystems, the Laurentian Great Lakes of North America have undergone numerous anthropogenic stressors resulting in considerable loss of biodiversity and habitat. Among Great Lakes fishes, the coregonine sub-family has endured the most extensive declines, including extinction of several species (Coregonus johannae, C. alpenae, and C. kiyi orientalis) and at least 10 instances of local extirpations of other species (C. nigripinnis, C. reighardi, C. zenithicus, C. hoyi, and C. artedi) across all 5 lakes, much of which occurred prior to the 1960s owing to overfishing, interactions with non-indigenous species, and habitat loss. Despite these declines, no federal-, provincial-, or state-mandated actions were ever implemented to conserve coregonine diversity, potentially because so much of the coregonine declines occurred prior to the enactment of federal conservation legislation. Possible explanations for inaction since enactment of that legislation include insufficient data on biological vulnerability or threats, unresolved taxonomy, and limited support from the fishery management agencies and their stakeholders prior to the 2000s. In recent decades, however, several fishery management agencies have undertaken efforts to re-introduce coregonine diversity. These efforts helped lead to development of a science-based framework to restore coregonines that was universally endorsed by fishery managers representing eight U.S. states, four U.S. tribal organizations, and the province of ON, Canada, in May 2018. The basin-wide framework is based on principles of conservation biology and adaptive management. We describe details of its key steps, including planning, restoring, and evaluating, while also describing recent implementation efforts to develop methods, improve available resources, and enhance coordination across the basin. Although our paper describes a regional effort to restore native coregonines, our adaptive-management approach could be used by other multi-agency stakeholders seeking to conserve or restore native fishes. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
17. Improvement of tailings impoundment seismic and post-seismic stability using densification and waste rock inclusions.
- Author
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Contreras, Carlos Andrés, Yniesta, Samuel, and Aubertin, Michel
- Subjects
- *
TAILINGS dams , *SURFACE fault ruptures , *METAL tailings , *GROUND motion , *EARTHQUAKES , *NUMERICAL analysis - Abstract
Tailings impoundments are often prone to failure due to various causes related to complex loading conditions. For instance, tailings impoundments can fail during or after a seismic event, mainly because of the liquefaction of loose, cohesionless tailings. To improve the seismic stability of impoundments, the density of the tailings can be increased or waste rock inclusions (WRI) can be added in the impoundment. This paper presents the results of numerical analyses of the impoundments loaded with a variety of ground motions with different frequencies, scaled at two different levels of intensity representative of two mining regions of Eastern Canada. The results show that the conventional impoundments are subjected to medium to high displacements at the end of shaking; these show a high probability of rupture during the earthquake or in the post-seismic phase. Tailings densification can decrease the volume of liquefied tailings and displacements during the seismic phase but does not significantly reduce the probability of post-seismic failure. WRI can slightly reduce the volume of liquefied tailings, depending on the intensity of the motions, but the reinforcement reduces significantly the lateral displacements; impoundments with WRI show even better performances during the post-seismic phase. The use of WRI is deemed a good approach to ensure the seismic stability of tailings impoundments and reduce the risk of seismically induced failure. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
18. A pan-Canadian assessment of empirical research on post-disturbance recovery in the Canadian Forest Service.
- Author
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Waldron, Kaysandra, Thiffault, Nelson, Venier, Lisa, Bognounou, Fidèle, Boucher, Dominique, Campbell, Elizabeth, Whitman, Ellen, Brehaut, Lucas, and Gauthier, Sylvie
- Subjects
FOREST management ,FOREST resilience ,FOREST fire management ,LOGGING ,FOREST regeneration - Abstract
Information about post-disturbance regeneration success and successional dynamics is critical to predict forest ecosystem resistance and resilience to disturbances and climate change. Our objective was to identify and classify post-disturbance empirical research conducted by the Canadian Forest Service (CFS) of Natural Resources Canada and their collaborators to provide guidance on future research needs, improving our understanding of post-disturbance recovery in a Canadian context. To achieve our objective, we collected and classified peer-reviewed and non-published literature produced by the CFS between 1998 and 2020 that concerned post-disturbance ecology. We focused on research addressing natural or anthropogenic disturbances, such as wildfires, pest outbreaks, windthrows, forest management, seismic lines, and those that studied processes related to soil, vegetation, fauna, hydrology, and microbial communities. We found that forest harvesting was the disturbance most studied by CFS between 1998 and 2020, followed by fire. Despite the fact that large, forested areas are affected annually by pests, studies on recovery after pest outbreaks were scarce. Other disturbances, such as mining and seismic lines or other abiotic disturbances were rare in CFS literature. Most studies (70%) examined changes in vegetation related to forest management and fire and they were mainly focussed on post-disturbance tree regeneration success. Post-disturbance changes in understory species diversity were also well-studied. Our results provide a geographic overview of CFS research on post-disturbance recovery in Canada and enable the identification of key knowledge gaps. Notably, research focusing on recovery after natural disturbances was underrepresented in the assessed literature compared to studies centered around harvesting. Long-term research sites, chronosequences that substitute space for time, and studies focused on consecutive disturbances are especially important to maintain and establish sustainable forest management strategies in the face of climate change. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
19. Developing a machine learning-based approach for predicting road surface friction using dash camera images—a City of Edmonton, Canada, case study.
- Author
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Xie, Qian and Kwon, Tae J.
- Subjects
- *
MACHINE learning , *PAVEMENTS , *STANDARD deviations , *FRICTION - Abstract
Although road surface friction is considered the most effective performance measure for maintenance operations, it is not commonly used due to the high cost of collection. As a result, most jurisdictions use subjective visual indicators that qualitatively describe the state of the road surface, even though they create measurement inconsistencies and offer less detailed maintenance tracking. For maintenance personnel to transition into using friction, the collection cost must be reduced. This paper attempts to do so by proposing a low-cost, machine learning-based method for predicting road surface friction using dash camera imagery and demonstrates its feasibility through a case study. The dataset used for this project was collected in the City of Edmonton, AB, Canada during its 2021/2022 winter season. Three models were developed using tree-based algorithms, where all three displayed high performance with an average root mean squared error of 0.0796 or 79.3% accuracy based on RMSPE. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
20. Crustal eduction and slab-failure magmatism in an Orosirian (2.05–1.80 Ga) postcollisional cratonic foredeep: geochronology of Seton volcanics and Compton laccoliths, Tu Cho (Great Slave Lake), NWT, Canada.
- Author
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Hoffman, Paul F., Macdonald, Francis A., Bowring, Samuel A., Ramezani, Jahandar, Buchwaldt, Robert, Hildebrand, Robert S., and Whalen, Joseph B.
- Subjects
VOLCANOLOGY ,GEOLOGICAL time scales ,THRUST belts (Geology) ,MAGMATISM ,OROGENIC belts ,VOLCANISM ,LAKES - Abstract
Three Orosirian basins and associated foreland thrust-fold belts are preserved on the margins of the Slave craton. All three are related to orogenic belts where oceans opened and later closed, uniting new crustal partners. The Great Slave basin differs from the Kilhigok and Coronation basins in ways that have defied explanation. It lacks a passive margin sequence and hosts two discrete igneous suites, separated by large-scale thrusting, that occurred well after the adjacent paleocean had closed. Here we report U–Pb zircon geochronology by chemical abrasion isotope dilution thermal ionization mass spectrometry for a member of each suite to constrain the age and origin of postcollisional thrusting. A widespread pulse of mainly phreatic alkaline volcanism, coeval with renewed foredeep flexure, occurred at 1889.0 ± 0.7 Ma (2σ internal error). A quartz-monzodiorite body, one of a belt-parallel chain of laccoliths that postdate thrusting, was emplaced at 1866.9 ± 0.9 Ma. These ages bracket renewed foredeep sedimentation and thrusting that telescoped major facies zones and was rooted within the basin. The older age is 70 and 30−60 Myr younger than collision in the Thelon and Taltson orogens, respectively. We attribute postcollisional thrusting and foredeep subsidence to "eduction"—the upward and outward ejection of partly subducted crust—and postulate that the top of the ejected wedge was a normal-sense detachment fault projecting beneath the Nonacho basin. We infer that eduction was triggered by slab failure, producing alkaline volcanism, and ended with delamination and laccolith emplacement. Eduction was facilitated by tradewind-driven erosion. Delamination was enabled by crustal transfer to the educted wedge, reducing footwall buoyancy. Slab failure and/or delamination removed the passive margin. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
21. Towards a management strategy for microplastic pollution in the Laurentian Great Lakes—ecological risk assessment and management (part 2).
- Author
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Hataley, Eden K., McIlwraith, Hayley K., Roy, Dimple, and Rochman, Chelsea M.
- Subjects
ECOLOGICAL risk assessment ,POLLUTION ,WATER quality ,LAKES ,WATERSHEDS ,SEDIMENT sampling - Abstract
Over the past decade, plastic pollution has been documented throughout the Laurentian Great Lakes basin. Here, we demonstrate the application of a published ecological risk assessment and management framework for microplastics in aquatic environments by comparing proposed thresholds for risk to monitoring data from the Great Lakes region. Our results suggest that there may be measurable risks from microplastics to aquatic communities in parts of the Great Lakes where current concentrations are relatively high. For example, 89% of surface water samples collected across the region exceed the proposed risk thresholds for food dilution toxicity. However, all sediment samples remain below the proposed risk thresholds. Accordingly, we suggest that an appropriate and necessary next step for management may include convening a working group of local experts to develop an ecological risk assessment and management framework for the region comprising thresholds of concern for microplastics in surface water and sediment. Ultimately, microplastic pollution should be addressed in the Great Lakes Water Quality Agreement to ensure coordinated and sustained efforts are taken by the governments of Canada and the United States to reduce their release and impact. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
22. Is scientific inquiry still incompatible with government information control? A quarter-century later.
- Author
-
Godwin, Sean C., Bateman, Andrew W., Mordecai, Gideon, Jones, Sean, and Hutchings, Jeffrey A.
- Subjects
SCIENTIFIC method ,GOVERNMENT information ,INFORMATION resources management ,SALMON farming ,MARINE resources ,FISHERY management - Abstract
Twenty-six years ago, in response to regionally devastating fisheries collapses in Canada, Hutchings et al. asked "Is scientific inquiry incompatible with government information control?" Now, a quarter-century later, we review how government science advice continues to be influenced by non-science interests, particularly those with a financial stake in the outcome of the advice. We use the example of salmon aquaculture in British Columbia, Canada, to demonstrate how science advice from Fisheries and Oceans Canada (DFO) can fail to be impartial, evidence-based, transparent, and independently reviewed—four widely implemented standards of robust science advice. Consequently, DFO's policies are not always supported by the best available science. These observations are particularly important in the context of DFO having struggled to sustainably manage Canada's marine resources, creating socio-economic uncertainty and putting the country's international reputation at risk as it lags behind its peers. We conclude by reiterating Hutchings et al.'s unheeded recommendation for a truly independent fisheries-science advisory body in Canada to be enshrined in the decision-making process. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
23. Impact of green manure and weeds on selected soil health indicators in an organic grain cropping system in Nova Scotia.
- Author
-
McNeil, Morgan O., Lynch, Derek H., Alam, Mohammed Z., Mills, Aaron, and Marshall, Carolyn B.
- Subjects
GREEN manure crops ,ORGANIC farming ,CROPPING systems ,SOILS ,WEEDS ,CROP rotation - Abstract
The green manure residual effect on soil health 2 years later in crop rotation is understudied. Little is known about weed biomass impact on soil microbial communities or their interactions. A Colchester County, NS, Canada, organic grain research trial during 2016-2017 comprised 2 or 3-year rotations with or without green manure crop prior to wheat, and then soybeans. Fall soil sampling was conducted both years. The soybean phase of the crop rotation was managed as weedy or non-weedy. Weedy soil showed significantly increased soil respiratory activity and fungal microbial biomass. Green manure treatments did not significantly influence soil health indicators. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
24. The physiological state of four commercially important bivalve species during a naturally occurring heatwave.
- Author
-
Talevi, Jasmine, Steeves, Laura, Coffin, Michael, Guyondet, Thomas, Sakamaki, Takashi, Comeau, Luc, and Filgueira, Ramón
- Subjects
MYA arenaria ,HEAT waves (Meteorology) ,BIVALVES ,NORTHERN quahog ,MARINE heatwaves ,AMERICAN oyster - Abstract
Shallow coastal environments are becoming more susceptible to marine heatwaves, particularly in Atlantic Canada, which is experiencing higher rates of ocean warming compared with the global average. Understanding bivalves' tolerance to heatwaves in Atlantic Canada is especially important, given the magnitude of bivalve aquaculture in this region. In this study, the physiological state of four commercially important bivalve species—blue mussel (Mytilus edulis Linnaeus, 1758), eastern oyster (Crassostrea virginica (Gmelin, 1791)), soft shell clam (Mya arenaria Linnaeus, 1758), and hard clam (Mercenaria mercenaria (Linnaeus, 1758))—was observed during a naturally occurring heatwave in Prince Edward Island, Canada. The metabolism, feeding physiology, and scope for growth of each species were compared. Results from this study, and comparisons with the literature, show interspecific variability in the metabolic rate and feeding physiology between species, but generally oysters, soft shell clams, and hard clams were less impacted during the heatwave compared with the blue mussels. Additionally, only the scope for growth of mussels declined throughout this experiment, which may be explained by cumulative heat stress, as temperatures experienced during this heatwave exceeded the thermal tolerance limits of mussels. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
25. The post-fire shift of temperate white pine-birch forest to boreal balsam fir forest in eastern Canada: climate-fire implications.
- Author
-
Payette, Serge, Frégeau, Mathieu, Couillard, Pierre-Luc, and Laflamme, Jason
- Subjects
BALSAM fir ,TAIGAS ,PLANT identification ,WHITE pine ,CLIMATE change - Abstract
Copyright of Botany is the property of Canadian Science Publishing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)
- Published
- 2023
- Full Text
- View/download PDF
26. Comparison between MERRA-2 and CWEEDS for use in pavement mechanistic-empirical design in Canada.
- Author
-
Shafiee, Mohammad, Maadani, Omran, and Cobo, Juan Hiedra
- Subjects
- *
FLEXIBLE pavements , *PAVEMENTS , *PAVEMENT management , *RESILIENT design , *DATA quality - Abstract
To improve the climate resiliency of existing and new pavements, it is important to carry out pavement designs using continuous climate records at high temporal frequencies. Over the years, significant research efforts have been dedicated to obtain high-quality climatic data for pavement design including the latest adoption of the Modern-Era Retrospective analysis for Research and Applications, version 2 (MERRA-2). The purpose of this study is to assess how MERRA-2 performs when compared to the Canadian Weather Energy and Engineering Datasets (CWEEDS), which provides hourly meteorological data for many parts of the country from various periods. In the first part, climate parameters at nine locations were directly compared to determine the correlation between two data sets. In the second part, long-term performances were simulated for typical flexible pavement to assess the relative impact of each climate scenario. As detailed in this paper, observed differences between MERRA-2 and CWEEDS indicate the need for further improvement of climate data quality and availability for designing resilient pavements in Canada. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
27. Managing Canadian freshwater fisheries: persistent challenges and emerging opportunities.
- Author
-
Howarth, Andrew, Nguyen, Vivian M., and Cooke, Steven J.
- Subjects
FISHERIES ,FRESH water ,FRESHWATER biodiversity ,PROBLEM solving ,GEOGRAPHY - Abstract
Freshwater fisheries and biodiversity have substantial economic, socio-cultural, and ecological value, but face severe and mounting anthropogenic threats. Canada's freshwater fisheries are not exempt from this, and provide excellent opportunities to better understand these overlooked and undervalued systems. Using expert and chain-referral sampling, we surveyed practitioners from across Canada about the management of freshwater fisheries. We used a mixed methods approach to identify and describe in detail many important aspects of the above processes, including 10 persistent and innate challenges in (1) bureaucratic sprawl, (2) lack of priority, (3) scope, (4) competing interests, (5) political inconstancy, (6) socio-ecological complexity, (7) limited tools, (8) geographies and scale, (9) reactivity, and (10) intersectoral frictions. Many of these challenges defy conventional problem solving (e.g., advocacy, basic science), leading to chronic incapacity and triage management in some freshwater fisheries. We highlight opportunities to increase management capacity, using innovation where conventional solutions fall short (e.g., using novel technologies to increase management scope). Achieving sustainability in Canadian freshwater fisheries will require ingenuity and supportive contributions beyond those that currently exist. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
28. Short-term response of soil aggregate stability and labile carbon to contour tillage, diversion terrace, grassed waterway, and tile drainage implementation.
- Author
-
Driscoll, Bryan A., Krzica, Maja, Comeau, Louis-Pierre, Eskelson, Bianca N. I., and Sheng Li
- Subjects
SOIL structure ,TILLAGE ,SOIL degradation ,DRAINAGE ,SOIL stabilization - Abstract
Soil degradation has been of great concern for New Brunswick's potato farmers, especially on sloped land and shallow soils. In this study, we evaluated the initial response of labile soil carbon (C) fractions (permanganate oxidizable C (POXC) and particulate organic C (POC)) and aggregate stability to two integrated best management practices (BMPIs) composed of the following individual practices: diversion terraces (DT), grassed waterways (GW), and contour tillage (CT) (i.e., DTGW) and DT, GW, CT, and tile drainage (TD) (i.e., DTGW + TD), relative to CT that served as a control. The more water was regulated in the field, the greater the increase in labile C; where DTGW and DTGW + TD gained 19.8% and 50.6% of POXC, respectively, while CT lost 11.2% of POXC. There was an increase in mineral associated organic matter C in the terraced BMPIs, despite the high amount of tillage events that took place during potato cultivation. Two BMPIs had no effect on aggregate stability, most likely due to the short duration of this initial monitoring study that spanned just over two growing seasons. Even though there were no improvements in soil structure, our findings showed that some stabilization of soil C is possible even during the initial two seasons following BMPI implementation. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
29. A review of large-scale renewable energy partnerships with Indigenous communities and organizations in Canada.
- Author
-
Yalamala, Reddi Sekhara, Zurba, Melanie, Bullock, Ryan, and Diduck, Alan P.
- Subjects
- *
RENEWABLE energy sources , *CLEAN energy , *INDIGENOUS children , *ECONOMIC development projects , *BUSINESS skills , *ENVIRONMENTAL protection - Abstract
In this paper, a review of Indigenous engagement in renewable energy projects is conducted and the main elements of energy partnerships between stakeholders and Indigenous partners are discussed. In recent years, Canada has witnessed more significant Indigenous involvement in economic and energy development projects than ever before. For large-scale energy partnerships, the focus is on engagement, financial capital, community buy-in (readiness, and entrepreneurial and business skills), and benefits-sharing with community partners. Equity-ownership, reconciliation, and self-determination intersect with and impact the benefits and sustainability of energy projects, as they are interrelated in the framework of most energy partnerships. This paper illustrates policy disconnects in connection with partnership-making, social outcomes, and decision-making among Indigenous communities. Furthermore, findings from relevant literature explore the nuanced discourse on social implications and capacity challenges that interlink with climate adaptation and reconciliation when promoting large-scale renewable energy partnerships with Indigenous communities. Through a systematic review and a meta-analysis of the literature, we found 80 relevant studies during the screening process, of which 33 were selected for the synthesis. Findings demonstrate that the Crown, energy companies, and community partners need to coordinate and collaborate closely to achieve energy security and sustainable renewable energy. The review suggests that Indigenous engagement in energy partnerships supports positive outcomes for social development and environmental protection among Indigenous communities. The literature suggests that when government and industry mentor in the project implementation process, important positive impacts on energy transitions, and self-sufficiency can be realized. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
30. Review of nonlinear modelling parameters and acceptance criteria in ASCE 41 for seismic evaluation and upgrading of steel structures in Canada.
- Author
-
Kim, Taeyong, Kwon, Oh-Sung, Acosta, Joaquín, Fathi-Fazl, Reza, Fazileh, Farrokh, and Cai, Zhen
- Subjects
- *
RETROFITTING of buildings , *STEEL framing - Abstract
The seismic resilience of structures can be quantified through rigorous seismic assessment. Because no detailed guideline is available for nonlinear modelling parameters and the corresponding acceptance criteria for the seismic evaluation and upgrading of steel structures in Canada, the structural commentary of the National Building Code of Canada suggests using ASCE 41, which has been adopted as a standard for seismic evaluation and retrofit of buildings in the United States (U.S.). However, because the steel design standards in Canada and the U.S. are different, their applicability to steel structures in Canada needs to be investigated. To this end, this paper critically reviews the nonlinear modelling parameters and acceptance criteria, and then recommends whether these values need to be revised or are adopted as is for the seismic evaluation and upgrading of steel structures in Canada. A numerical example of a steel moment-resisting frame is presented to demonstrate the recommended parameters being used for seismic evaluation. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
31. Microplastics in subsurface water and zooplankton from eight lakes in British Columbia.
- Author
-
Klasios, Natasha and Tseng, Michelle
- Subjects
PLASTIC marine debris ,MICROPLASTICS ,POLYESTER fibers ,ZOOPLANKTON ,LAKES ,ATMOSPHERIC deposition - Abstract
Microplastics are a global contaminant of concern, but we have little information on the characteristics and bioavailability of these pollutants in western Canadian lakes. Here, we quantify and characterize microplastics in subsurface water and zooplankton from eight lakes in BC, Canada. By sampling water and zooplankton, we provide insight into the fraction of microplastics entering the food web. We found 0.607 ± 0.153 microplastics per litre in subsurface water, 0.01 ± 0.011 microplastics per copepod, and 0.02 ± 0.014 microplastics per Daphnia. Microplastic pollution was similar in all lakes sampled and showed no relationship with local population density. Fibers were the dominant morphology observed in all lakes, and Raman spectroscopy identified polyester as the dominant polymer found both in lakes and within zooplankton. Zooplankton generally ingested microplastics that were shorter than their body length and that fell on the smaller end of the range of available microplastics. The prominence of polyester fibers and PET films and fragments suggests that the likely sources of microplastics to these lakes are recreational activities and atmospheric deposition. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
32. LRFD calibration for soil failure limit state using the Stiffness Method.
- Author
-
Bathurst, Richard J. and Allen, Tony M.
- Subjects
- *
LOAD factor design , *FAILED states , *BUILDING foundations , *ROAD construction , *BRIDGE design & construction , *BEARING capacity of soils - Abstract
The paper describes load and resistance factor design (LRFD) calibration for the resistance factor used in the Stiffness Method internal stability soil failure limit state for geogrid mechanically stabilized earth (MSE) walls. The Stiffness Method was recently adopted in the current American Association of State Highway and Transportation Officials LRFD Bridge Design Specifications in the US, and will appear in the next edition of the Canadian Highway Bridge Design Code. The paper describes the details of the calibration of the soil failure limit state which is unique to the Stiffness Method. Calibration outcomes include consideration of the concept of level of understanding in the selection of nominal load and resistance values which is unique to LRFD foundation engineering practice in Canada. A practical conclusion from these calculations is that if product line-specific creep test data are available to estimate the reinforcement secant creep stiffness used for design, then a resistance factor of 1.0 is reasonable for US practice. If only minimum average roll value tensile strength data are available, then a value of 0.95 is recommended for US practice. For Canadian practice, the corresponding values for typical level of understanding are 0.90 and 0.85, respectively. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
33. Environmental DNA (eDNA) applications in freshwater fisheries management and conservation in Canada: overview of current challenges and opportunities.
- Author
-
Bernos, Thaïs A., Yates, Matthew C., Docker, Margaret F., Fitzgerald, Amy, Hanner, Robert, Heath, Daniel, Imrit, Arshad, Livernois, John, Myler, Erika, Patel, Keta, Sharma, Sapna, Young, Robert, and Mandrak, Nicholas E.
- Subjects
FISHERY management ,FRESH water ,CULTURAL pluralism ,DNA ,FISH conservation ,RESEARCH personnel ,GEOGRAPHY - Abstract
Environmental DNA (eDNA) monitoring methods have played a significant role in improving fisheries management decisions. Yet, their impact to date has been rather limited in Canada, where eDNA sampling and analyses are only beginning to be used to inform management and conservation decisions, practices, and policies. Studies investigating hurdles to the incorporation of eDNA evidence into fisheries management decisions generally focus on technical challenges (i.e., risks of false-positive and false-negative detections). We set out to identify challenges that eDNA researchers and conservation practitioners must overcome to fully unlock the benefits of eDNA sampling for fish management in the Canadian context. We discuss aspects of the broad and heterogeneous geography, preponderance of regions located far from densely populated areas, complex political landscape, and cultural diversity of Canada that may complicate the design of reliable eDNA monitoring tools or restrict their use if not adequately addressed. To advocate for the wider use of eDNA sampling, we outline a number of action items that would facilitate the broad adoption of eDNA sampling as a monitoring tool at the Canadian scale. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
34. Comparing biomass yields of various willow cultivars in short-rotation coppice over six growing seasons across a broad climatic gradient in Eastern Canada.
- Author
-
Labrecque, Michel, Daigle, Stéphane, and Olishevska, Snizhana
- Subjects
COPPICE forests ,BIOMASS ,COLD regions ,BIOLOGICAL products ,CLIMATE change ,CULTIVARS - Abstract
Copyright of Canadian Journal of Forest Research is the property of Canadian Science Publishing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)
- Published
- 2023
- Full Text
- View/download PDF
35. Competition overwhelms environment and genetic effects on growth rates of endangered white sturgeon from a conservation aquaculture program.
- Author
-
Crossman, James A., Korman, Josh, McLellan, Jason G., Howell, Matthew D., and Miller, Andy L.
- Subjects
HABITATS ,STURGEONS ,AQUACULTURE ,WILDLIFE recovery ,ENDANGERED species ,ACIPENSER - Abstract
Improving the status of endangered species can be challenging because the efficacy of conservation actions is often uncertain. Conservation aquaculture has been the main recovery action for endangered white sturgeon (Acipenser transmontanus) in the Transboundary Reach of the upper Columbia River. Using long-term mark-recapture data (2002–2018), we predicted variation in growth rates due to genetic, environmental, and competition effects to evaluate the efficacy of the aquaculture program. Environmental conditions (by season and country) and competition had the greatest effects on growth. Growth, length-at-age, weight-at-age, and condition factor were higher for fish residing in reservoir habitats (US) compared to those in riverine habitat (Canada). Growth declined over the study period but growth in length for larger fish remained higher in the US as fish > 100 cm fork length in Canada were not growing. Small differences in growth among families indicate that differences in genetics among parents spawned in the hatchery had negligible effects on growth in the wild. Our estimate of substantive negative density-dependent growth in Canada is important for management of conservation aquaculture for sturgeons. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
36. Historic climate change trends and impacts on crop yields in key agricultural areas of the prairie provinces in Canada: a literature review.
- Author
-
Mapfumo, Emmanuel, Chanasyk, David S., Puurveen, Dick, Eltona, Shannon, and Acharya, Sachin
- Subjects
LITERATURE reviews ,CANADIAN provinces ,CROP yields ,AGRICULTURE ,CLIMATE change ,AGRICULTURAL technology ,SOIL freezing - Abstract
The objective of this literature review was to compile research findings on climate change and its impacts on crop production in Prairie Provinces of Canada. Our search strategy included finding primary literature articles from various databases. Seven articles reported increases in average and minimum air temperature over time in the Prairie Provinces of Canada. Increases in maximum air temperature were smaller than that forminimum air temperature. Growing degree days and corn heat units also increased over time, which has allowed for potential expansion of corn growth northwards. While overall increases in average annual precipitation and growing season precipitation have occurred in Canada between 1900 and 2021, western Canada showed increases in some regions but decreases in others. Off-season precipitation and snow cover duration in Canada have decreased since 1950. The number of frost-free days has increased across Canada, on the Prairies and southern Saskatchewan since 1900. Annual snowfall has decreased since 1950 and across Canada the annual maximum snow depth has also decreased. Overall, studies focusing on the Prairie Provinces in Canada have shown accelerated changes in several climate parameters over time, affecting cropping areas and crop yields. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
37. Rationalizing mottling and gleying in the characterization and classification of Canadian soils.
- Author
-
Heck, Richard J., Saurette, Daniel D., and Warren, C. James
- Subjects
SOIL horizons ,SOILS ,SOIL classification - Abstract
Mottling and gleying remain important characteristics for the classification of soils in Canada. The development of criteria for the morphological description of these redoximorphic soil features, for soil horizon nomenclature, for the taxonomy of gleysolic and gleyed soils, as well as for soil drainage classification, began in the mid-1940s and continued for the next four decades. Despite advancements elsewhere, notably with Soil Taxonomy and the World Reference Base, there have been minimal refinements made in Canada, during the past quarter century. Various issues are identified, including the need for more succinct and clearer definitions, a revision of standards for the field characterization of redoximorphic features, as well as more consistency in the application of concepts across existing taxa and systems. A taxonomic framework to more effectively reflect redoximorphic features, such as a new "Redoximorphic Phase" is also discussed. Ultimately, it is recommended that a special committee to be established to conduct a thorough study and present recommendations. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
38. Do cover crops on the Canadian prairies affect soil nitrogen cycling?
- Author
-
Otchere, O., Lawley, Y., and Congreves, K.A.
- Subjects
COVER crops ,PRAIRIES ,NITROGEN cycle ,NITROGEN in soils ,CROP rotation ,AGRICULTURAL productivity ,RED clover - Abstract
For one of Canada's most important regions of crop production—the prairies—it's uncertain if cover crops can be successfully integrated into rotations; if so, will soil nitrogen (N) cycling be influenced to benefit main crops? To address these gaps, we compared a crop rotation with cover crops (CC) vs. without cover crops (LR) from 2018 to 2021 in Saskatoon, SK. The main crops were grown in sequence of wheat–canola–potato–pea; the cover crops included red clover, berseem clover/oat mix, fall rye, and a brassica cover. Yield and aboveground biomass were collected each year and analyzed to determine crop yield and N use efficiency (NUE). Soil N availability was monitored in various ways, that is, by assessing pre-plant soil nitrate, soil inorganic N (SIN) supply rate, and potentially mineralizable N (PMN). We found that the influence on soil N dynamics was restricted to the non-growing season where cover crops reduced SIN supply rate and nitrate content compared to the conventional practice without cover crops. Yet, rotations with vs. without cover crop did not differ in crop NUEs, yields, or in-season N dynamics. We found some evidence that diversifying rotations with cover crops may help the system to function more like perennial systems in terms of regulating N in the long run; but had limited impact during the three years studied. To ensure that cover crops are effective and functional on the prairies, innovative design approaches are needed to adapt cover crops to reach soil health goals under prairie conditions. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
39. Ratio of non-growing season to growing season N2O emissions in Canadian croplands: an update to national inventory methodology.
- Author
-
Pelster, David E., Thiagarajan, Arumugam, Liang, Chang, Chantigny, Martin H., Wagner-Riddle, Claudia, Congreves, Kate, Lemke, Reynald, Glenn, Aaron, Tenuta, Mario, Hernandez-Ramirez, Guillermo, Bittman, Shabtai, Hunt, Derek, Owens, Jennifer, and MacDonald, Douglas
- Subjects
GROWING season ,FARMS ,CORRECTION factors ,COLD regions ,AGRICULTURE - Abstract
National inventory reporting of agricultural nitrous oxide (N
2 O) emissions in Canada is based primarily on measurements obtained using static chambers. In regions with cold winters and an accumulated snowpack (including Canada), these measurements tend to focus on the growing season (typically May–October). However, research has shown that emissions continue throughout the non-growing season (NGS) and that these account for a significant proportion of annual emissions. In the Canadian National Inventory NGS emissions currently are assumed to be adequately captured in western Canada, while they are accounted for in eastern Canada by multiplying the growing season emissions by a correction factor of 1.4, a value that was derived based on a limited number of measurements. Here we use recent Canadian studies to validate this correction factor. We collected data from available Canadian studies that measured soil N2 O emissions from agricultural systems for the entire year and determined the proportion of these emissions that occurred during the NGS. The proportion of annual N2 O emissions that occurred during the NGS varied widely, ranging from −4% to 119% with a mean of 35.5%, compared to the previous estimate of 30%. Due to high variability, few differences were observed between means associated with climatic, soil, and management variables. To correct for NGS N2 O emissions from Canadian agricultural soils, we suggest that the current correction factor for converting growing season to total annual emissions be changed from 1.4 to 1.55 and that this be used for all agricultural soils in Canada rather than just eastern Canada. [ABSTRACT FROM AUTHOR]- Published
- 2023
- Full Text
- View/download PDF
40. Development of quick seismic evaluation procedure for existing buildings in Canada.
- Author
-
Fathi-Fazl, Reza, Fazileh, Farrokh, Cai, Zhen, and Cortés-Puentes, W. Leonardo
- Subjects
- *
PILOT projects - Abstract
The National Research Council Canada (NRC) is currently developing seismic evaluation and upgrading guidelines for existing buildings in Canada. The seismic evaluation guidelines consist of three tiers of seismic evaluation procedures, that is, Tier 1 Quick Evaluation, Tier 2 Deficiency-Based Evaluation, and Tier 3 Detailed Evaluation. This paper presents the Tier 1 Quick Evaluation procedure, which aims to update the initial quick evaluation procedure in the existing seismic evaluation guidelines developed by the NRC in early 1990s. The proposed procedure covers seismic assessment of both structural and non-structural elements, and requires the review of construction documents, on-site inspection, and calculations. A set of checklists are contained to uncover potential key seismic deficiencies of the building under evaluation. The checklists are in the form of evaluation statements that relate to potential seismic deficiencies in the structural systems and non-structural components. The proposed procedure is demonstrated by conducting the seismic evaluation of an existing building that is part of a pilot study. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
41. Geomorphic diversity of the Newfoundland and Labrador Shelves Bioregion.
- Author
-
Shaw, John, Li, M.Z., and Kostylev, V.E.
- Subjects
CONTINENTAL slopes ,CONTINENTAL shelf ,SEDIMENT transport ,SEDIMENT analysis ,MULTIBEAM mapping - Abstract
The Newfoundland and Labrador Shelves Bioregion, located on the glaciated continental shelf and adjacent continental slope of eastern Canada, is classified into units that reflect its great physiographic diversity. There are ten shelf units: bedrock zone, fjord systems, major inlet, shelf-crossing troughs, four types of offshore banks, basin, and disturbed (glaciotectonic) terrain. There are three units on the continental slope: channelized areas, trough-mouth areas, and large sedimentary drifts. A series of vignettes illustrates both the distinguishing characteristics of the principal geomorphic units and the morphologic diversity within them. A sediment mobility analysis reveals that wave- and current-generated disturbances are dominant and largely depth-controlled within the shelf units, while the south-flowing Labrador Current impacts sediment transport and mobility along the continental slope. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
42. Marine and freshwater centrohelid heliozoans (Haptista: Centroplasthelida) in Canada, including taxonomic revisions and descriptions of 22 new species and subspecies.
- Author
-
Nicholls, Kenneth H.
- Subjects
SUBSPECIES ,TERRITORIAL waters ,FRESH water ,FRESHWATER habitats ,SPECIES - Abstract
Canadian coastal waters of the Pacific Ocean and the Atlantic Ocean as well as inland freshwater habitats in Ontario were sampled for centrohelid heliozoans (free-living heterotrophic single-celled organisms) over a period of nearly five decades. More than 60 species and subspecies were revealed, including 1 Triangulopteris, 1 Raphidocystis, 2 Pseudoraphidocystis, 3 Raineriophrys, 4 Pseudoraphidiophrys, 12 Choanocystis, 15 Pterocystis, and 25 Acanthocystis taxa. Of these, 22 were officially named and described as new to science based primarily on the morphology of the siliceous scales that cover the cell. New species were compared with images and/or descriptions of close "relatives" to validate their new species assignments. New data on five species of Acanthocystis and one species of Choanocystis required revisions of their descriptive taxonomy that in some cases resulted in the splitting off of separate species or subspecies. Very little can be concluded about global distribution of centrohelid heliozoans, owing to the paucity of records. For many of the taxa reported here, previous records consist of just one or two findings from other parts of the world. One example is Choanocystis antarctica Tikhonenkov and Mylnikov, 2011 that was previously known only from Antarctic seawater, but is reported here from an Ontario softwater lake. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
43. Canadian Nutrition Society 2023 Scientific Abstracts: Canadian Nutrition Society Annual Conference.
- Subjects
NUTRITION ,CONFERENCES & conventions ,DIETETICS - Published
- 2023
- Full Text
- View/download PDF
44. Susceptibility of endangered Cornus florida (eastern flowering dogwood) to the introduced fungal pathogen Discula destructiva (dogwood anthracnose) in the Canadian Carolinian forest: insights from environmental, ecological, and population genetics assessments
- Author
-
Mitchell, Emily, Fleming, Sage, Dorken, Marcel, and Freeland, Joanna
- Subjects
POPULATION genetics ,DOGWOODS ,GENETIC variation ,FRAGMENTED landscapes ,GENE flow ,HABITATS ,PLANT dispersal - Abstract
Forest fragmentation and introduced pathogens are negatively impacting trees and forests globally, including the Carolinian forest of southern Ontario, Canada. Multiple species at risk live in this threatened but biodiverse forest, including the endangered Cornus florida (eastern flowering dogwood), which is now limited to fragmented woodlots, and has been decimated by the introduced fungal pathogen Discula destructiva (dogwood anthracnose). Ongoing management of C. florida in Canada is challenged by multiple knowledge gaps, two of which we aimed to address in this study. We first evaluated the association between anthracnose disease prevalence and a suite of ecological and environmental variables across 21 sites. Across our sites, larger trees tended to have the highest disease incidence, and trees on shallow slopes had the most crown dieback. We then quantified genetic diversity and gene flow, and found that genetic structure has not been substantially impacted by habitat fragmentation, although dispersal typically covers short distances. However, genetic diversity is relatively low in smaller populations and in younger trees. Localized dispersal and eroding genetic diversity may limit future adaptation and hence exacerbate population declines. We recommend that managers prioritize plantings in small populations, avoid shallow slopes, and track younger trees to evaluate age-related mortality. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
45. Calibration of resistance factors for design of shallow foundations against sliding.
- Author
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He, Pengpeng and Fenton, Gordon A.
- Subjects
- *
SHALLOW foundations , *LOAD factor design , *SLIDING mode control , *BEARING capacity of soils , *MONTE Carlo method , *WIND pressure - Abstract
The design of shallow foundations typically proceeds by using the load and resistance factor design (LRFD) methodology to avoid various limit states with some probability. This paper looks at the sliding limit state of shallow foundations, and the sliding resistance factors required for the LRFD approach are estimated using reliability analyses of surface strip foundations. Cohesive and frictional soils are separately studied under wind loading conditions. Monte Carlo simulations are used to estimate the sliding failure probability of foundation designs on cohesive soils, and an analytical method is developed for frictional soils. The results indicate the existence of a "worst case" correlation length for cohesive soils, and the sliding resistance factor required to achieve target maximum lifetime failure probabilities is around 0.4–0.65 for moderate soil variability. For frictional soils, the required sliding resistance factor is about 0.5–0.85 for νϕ′ = 0.15. Overall, the sliding resistance factors recommended here agree well with the resistance factors of ϕgu = 0.6 for cohesive soils and ϕgu = 0.8 for frictional soils stipulated by geotechnical LRFD code provisions in Canada. The analyses can be used to estimate the reliability of current designs and can also aid the calibration of geotechnical design codes. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
46. Preliminary investigations of ground failures triggered during the mid-November 2021 atmospheric river event along the southwestern British Columbia highway corridors.
- Author
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Sepúlveda, Sergio A., Ward, Brent C., Cosman, Scott B., and Jacobs, Rachel
- Subjects
ATMOSPHERIC rivers ,TRANSPORTATION corridors ,LANDSLIDES ,CLIMATE extremes ,RIPARIAN areas ,ROADS ,CLIMATE change - Abstract
An unusually intense atmospheric river affected the southern coastal region of British Columbia in mid-November 2021. Flooding and several ground failures such as landslides and riverbank erosion caused significant damage and interrupted the main transportation corridors, including major highways and railroads, severing land connectivity between Metro Vancouver and the rest of Canada. In this short note, we summarize and describe slope and riverbank ground failures in the Lower Mainland and connecting corridors to the interior such as the Fraser Canyon and the Coquihalla Valley, with focus on those that produced damage on highways. Field observations are discussed in the context of potential future similar disasters in the region due to more frequent extreme climatic events associated with climate change. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
47. An update on the seismic categorization for seismic risk assessment of existing Canadian buildings.
- Author
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Motazedian, Dariush, Fathi-Fazl, Reza, Cai, Zhen, and Fazileh, Farrokh
- Subjects
RISK assessment ,SPECTRAL sensitivity ,TALL buildings - Abstract
An investigation has been done to update key input parameters in the recent seismic-risk-screening tools developed by the National Research Council Canada for the six seismic categories. In this study, the seismic categorization system in the recent seismic-risk-screening tools of the National Research Council Canada is extended to include Canadian buildings abroad by including threshold peak ground acceleration values, a more global set of modified Mercalli intensity, peak ground acceleration, and spectral response acceleration and peak ground acceleration relationships. The relationships among spectral response acceleration, peak ground acceleration, and peak ground velocity values have been derived using least-squares regression analyses to obtain the threshold values of both peak values associated with various modified Mercalli intensity values for each seismic category. Based on the updated relationships, the seismic categorization system is applied to 679 locations in Canada and 226 locations outside Canada. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
48. U–Pb geochronology: its development and importance in Canada.
- Author
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Davis, Donald W.
- Subjects
LASER ablation inductively coupled plasma mass spectrometry ,SECONDARY ion mass spectrometry ,GEOLOGY ,GEOLOGICAL time scales - Abstract
This article presents a history of the development of U–Pb geochronology with emphasis on the role of Canadian researchers and some of its applications to Canadian geology. Modern U–Pb dating is the result of work by many individuals over the past 60 years, but the most important was Tom Krogh, who established methods that allowed determination of precise ages (<0.1% errors) on zircon using isotope dilution thermal ionization mass spectrometry. This was followed by the introduction of new analytical approaches by others, notably secondary ion mass spectrometry and laser ablation inductively coupled plasma mass spectrometry that allow intracrystal domains to be dated. U–Pb geochronology is now an indispensable tool for understanding the Earth. In collaboration with field mapping, it has vastly improved our understanding of the geological history of Canada as well as important geological events such as mass extinctions, secular changes in geological processes, and the birth of the solar system. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
49. Drivers of Atlantic herring decline and evidence basis for fisheries closures and rebuilding plans.
- Author
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Calder, Ryan S.D., McDermid, Jenni L., and Boudreau, Stephanie A.
- Subjects
ATLANTIC herring ,FISHERY closures ,PRECAUTIONARY principle ,FISHERIES ,MACKERELS ,CONCEPTUAL models - Abstract
Atlantic herring (Clupea harengus) are economically and ecologically significant but have been in decline in Atlantic Canada due to an uncertain combination of environmental recruitment controls, predation, and fishing (commercial fishery and poorly documented bait removals). Fisheries and Oceans Canada partially closed Atlantic mackerel (Scomber scombrus) and herring fisheries in March 2022 amid controversy and disagreement. Here, we develop a conceptual model for natural and anthropogenic controls on herring abundance centered on the southern Gulf of St. Lawrence (sGSL) and evaluate the likely importance of each. We provide the first estimates of the magnitude of bait fishery withdrawals in the sGSL. The decline in sGSL herring is likely driven by natural predation exacerbated by fishing. Bait fishery removals were 182 tonnes in 2021, suggesting that previous estimates for removals of spring-spawning herring were ∼30% too low. Fisheries closure is consistent with a precautionary approach given uncertainties and irreversibility of stock collapse. Ecosystemic models are needed but will be difficult to develop given the incomplete understanding of prey substitutability and net effect of interacting environmental processes. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
50. Climate conditions in the near-term, mid-term and distant future for growing soybeans in Canada.
- Author
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Qian, Budong, Smith, Ward, Jing, Qi, Kim, Yong Min, Jégo, Guillaume, Grant, Brian, Duguid, Scott, Hester, Ken, and Nelson, Alison
- Subjects
CLIMATE change models ,COMMODITY futures ,CLIMATE extremes ,DROUGHTS ,GLOBAL warming ,SOYBEAN industry ,SOYBEAN - Abstract
The soybean industry in Canada aimed to extensively expand soybean production to benefit from new early-maturing varieties and the warming climate. However, setbacks in the soybean industry since 2017 demonstrated the impacts of climate risk and global market uncertainty. Therefore, a better understanding of future climate conditions that will impact soybean growth in Canada is needed for decision-making in the sector, such as prioritizing regions for expansion and developing climate change adaptation strategies through either agronomic management practices or breeding new cultivars. Based on climate projections from a set of global climate models, we analyzed climate conditions for growing soybeans, including growing season start, crop heat units, precipitation, precipitation deficits and climate extremes, in the near-term (2030s), the mid-term (2050s) and the distant future (2070s). We found that a future warmer climate with an increase of 1.6, 2.8 and 4.1 °C in the growing season (May–September) mean temperature averaged over Canada's land area in the near-term, mid-term and distant future under SSP3-7.0 would favour the expansion of soybean production further north and west. However, an increase of approximately 200 mm in precipitation deficits on the semiarid Canadian Prairies in the mid-term would constrain soybean production unless irrigation could be introduced. Heat- and drought-tolerant cultivars should be developed to adapt soybean production to a changing climate, in addition to the adoption of late-maturing cultivars that would benefit from the lengthened growing season and increased crop heat units. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
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