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Individual tree diameter at breast height (DBH) distribution is an important information for forest management planning. Forest managers obtain the DBH data either by field measurements or estimations using predictive models. However, probability distribution models are still lacking or need improvement. Therefore, we aimed to construct and fit diameter distribution models that reflect forest structure and composition change. We evaluated gamma, log-normal, and Weibull probability distribution functions (PDFs) for two commercially important tree species, black spruce (Picea mariana (Mill) B.S.P.) and jack pine (Pinus banksiana Lamb), grown in natural stands across Ontario, Canada. We modelled the parameters of the distributions as a function of stand-level variables for these species. We used DBH data from 735 permanent sample plots. Our results showed that all three evaluated PDFs reflected observed DBH distribution. We demonstrated that the moment-based recovered parameters could represent the maximum likelihood-estimated parameters precisely, and parameters of the PDFs can be modelled as a function of stand-level dynamic covariates. The models unbiasedly predicted the PDF parameters DBH means and DBH classes. The R2 of the model fit ranged between 0.35 and 0.98 for the predicted parameters and 0.90 and 0.97 for the predicted DBH. [ABSTRACT FROM AUTHOR]

Historically, the constructs of inclusion, diversity, equity, and access (IDEA) have not been sufficiently considered or included in population health nutrition research and practice. Consequently, current nutrition assessment benchmarks and knowledge translation tools may not accurately or adequately reflect diversity in the Canadian population or produce meaningful dietary guidance. The purpose of this current opinion paper is to introduce the population health nutrition research and practice framework and explore the current application of IDEA within this framework. Recommendations are offered to incorporate the constructs of IDEA along the continuum of future nutrition research and services to improve population nutritional health., Competing Interests: The authors declare there are no competing interests.

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 (δ13C), 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]

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]

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]

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 (N2O) emissions. To determine how effective MT could be in helping Canada mitigate greenhouse gas emissions, we used a meta-analysis to compare growing season N2O emissions from MT versus conventional tillage (CT). Overall, MT had 12% lower N2O 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 N2O 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 N2O emissions over time, MT should be used as a greenhouse gas mitigation measure only in dry climates or on sandy soils. [ABSTRACT FROM AUTHOR]

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]

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]

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]

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]

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]

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]

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]

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]

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]

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]

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]

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]

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]

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]