Post-cutting Mortality Following Experimental Silvicultural Treatments in Unmanaged Boreal Forest Stands

Partial cutting has been recommended as an alternative harvesting method to ensure the sustainable management of boreal forests. The success of this approach is closely linked to the survival of residual trees as additional losses through mortality could affect post-cutting timber production at harvest. To better quantify post-cutting mortality in previously unmanaged boreal forests, we addressed two main questions: (1) what is the level of mortality 10 years after cutting? and (2) what ecological factors are involved in this phenomenon? Even-aged black spruce [Picea mariana (Mill.) B.S.P.] stands in the Canadian boreal forest were subjected to three experimental shelterwood treatments, a seed-tree treatment and an untreated control. Tree status (live/dead) was recorded prior to cutting and 10 years after cutting. Dead trees were classified as standing dead, overturned or broken. Ten years after experimental seed-tree treatment, 60% of residual trees were dead, compared to 30% for the shelterwood cuttings. Windthrow (overturned and broken trees) represented 80% of residual tree mortality; only the amount of overturning was influenced by treatment. Broken trees were associated with small-diameter trunks, stands having high growth prior to cutting, younger stands or forest plots located near to adjacent cuts (<200 m). Overturning was associated with a high harvesting intensity and large-diameter trees. Standing dead mortality was the most difficult to explain: it was related to untreated plots having suppressed and small-diameter trees. Based on these results, applying intermediate levels of harvest intensity could reduce post-cutting damage. Understanding tree mortality after cutting is essential to reduce economic losses, improve silvicultural planning and stand selection and ensure ultimately the sustainable harvest of North American boreal forests

Current learning strategies in fire evacuation for seniors and people with disabilities in private seniors’ residences and long-term care homes: a scoping review

Current strategies for teaching evacuation methods in private seniors’ residences (PSR) and long-term care (LTCH) homes may pose risks to people with disabilities (PWD) and seniors' physical and psychological health. This study aimed to address the following questions: (1) Which are the current fire evacuation learning strategies used with PWD or seniors? (2) What are the barriers and facilitators for PWD and seniors' during fire evacuation and learning strategies in PSR and LTCH? (3) What is the existing equipment that could be used with PWD seniors?. A scoping review of grey and scientific literature was done in six databases and Google scholar. Additional information was found on Québec government websites. This review identified 13 scientific papers and 22 documents. Twenty barriers (personal = 9, environmental = 11), and 14 facilitators (personal = 4, environmental = 10) were extracted. The current fire evacuation learning strategies currently used can be grouped into three categories: drills; training; promotion of a fire safety plan. Six types of evacuation equipment were found; however, their use has been scarcely documented. Safety for seniors during fire evacuation is still an important issue to be improved. Increasing awareness and creating new practices and tools that consider the strengths and difficulties of seniors seems to be a promising avenue for improving evacuation

The motion of trees in the wind: a data synthesis

Interactions between wind and trees control energy exchanges between the atmosphere and forest canopies. This energy exchange can lead to the widespread damage of trees, and wind is a key disturbance agent in many of the world\u27s forests. However, most research on this topic has focused on conifer plantations, where risk management is economically important, rather than broadleaf forests, which dominate the forest carbon cycle. This study brings together tree motion time-series data to systematically evaluate the factors influencing tree responses to wind loading, including data from both broadleaf and coniferous trees in forests and open environments. We found that the two most descriptive features of tree motion were (a) the fundamental frequency, which is a measure of the speed at which a tree sways and is strongly related to tree height, and (b) the slope of the power spectrum, which is related to the efficiency of energy transfer from wind to trees. Intriguingly, the slope of the power spectrum was found to remain constant from medium to high wind speeds for all trees in this study. This suggests that, contrary to some predictions, damping or amplification mechanisms do not change dramatically at high wind speeds, and therefore wind damage risk is related, relatively simply, to wind speed. Conifers from forests were distinct from broadleaves in terms of their response to wind loading. Specifically, the fundamental frequency of forest conifers was related to their size according to the cantilever beam model (i.e. vertically distributed mass), whereas broadleaves were better approximated by the simple pendulum model (i.e. dominated by the crown). Forest conifers also had a steeper slope of the power spectrum. We interpret these finding as being strongly related to tree architecture; i.e. conifers generally have a simple shape due to their apical dominance, whereas broadleaves exhibit a much wider range of architectures with more dominant crowns

The motion of trees in the wind : a data synthesis

Interactions between wind and trees control energy exchanges between the atmosphere and forest canopies. This energy exchange can lead to the widespread damage of trees, and wind is a key disturbance agent in many of the world’s forests. However, most research on this topic has focused on conifer plantations, where risk management is economically important, rather than broadleaf forests, which dominate the forest carbon cycle. This study brings together tree motion time-series data to systematically evaluate the factors influencing tree responses to wind loading, including data from both broadleaf and coniferous trees in forests and open environments. Wefoundthatthetwomostdescriptive features of tree motion were (a) the fundamental frequency, which is a measure of the speed at which a tree sways and is strongly related to tree height, and (b) the slope of the power spectrum, which is related to the efficiency of energy transfer from wind to trees. Intriguingly, the slope of the power spectrum was found to remain constant from medium to high wind speeds for all trees in this study. This suggests that, contrary to some predictions, damping or amplification mechanisms do not change dramatically at high wind speeds, and therefore wind damage risk is related, relatively simply, to wind speed. Conifers from forests were distinct from broadleaves in terms of their response to wind loading. Specifically, the fundamental frequency of forest conifers was related to their size according to the cantilever beam model (i.e. vertically distributed mass), whereas broadleaves were better approximated by the simple pendulum model (i.e. dominated by the crown). Forest conifers also had a steeper slope of the power spectrum. We interpret these finding as being strongly related to tree architecture; i.e. conifers generally have a simple shape due to their apical dominance, whereas broadleaves exhibit a much wider range of architectures with more dominant crowns

Vérification d'une méthode d'inventaire écologique de la frange urbaine : application aux sites forestiers de l'Étang du Moulin, à Beauport

Afin de répondre aux besoins des aménagistes du milieu forestier périurbain (Bélanger et Pineau, 1983), Bélanger et al. (1984) proposent une méthode d'inventaire écologique qui tente d'intégrer le facteur humain dans la description du milieu. Cette méthode utilise quatre niveaux de perception écologique de l'espace: la région écologique, le sous-système écologique, le type écologique et la phase écologique. Le présent travail consiste à vérifier cette méthode en l'appliquant à un territoire précis : les environs de l’Étang du Moulin, à Beauport. Avant de procéder à la description écologique du milieu étudié, il a fallu procéder à quelques études préliminaires, notamment pour permettre de définir des groupements végétaux forestiers. Six cas types ont été retenus pour un examen plus poussé : l'évaluation du potentiel récréatif de la zone étudiée, l'expansion du développement résidentiel du secteur Courville, l'aménagement du boisé de l’Étang du Moulin et du parc linéaire des Marches Naturelles, la gestion du camping municipal de Beauport, ainsi que la réhabilitation d'une sablière désaffectée située en face du cimetière de Villeneuve. L'examen de ces cas types a permis de répondre à une bonne part des besoins d'information identifiés. Des améliorations sont proposées, toutefois, pour augmenter l'efficacité de la méthode. C'est ainsi que sont proposées une redéfinition de la phase écologique de façon à définir l'occupation par l'utilisation et l'état actuels du site, l'introduction au sein du type écologique d'un critère de discrimination supplémentaire, la perturbation du sol, ainsi que l'identification d'un niveau plus fin de perception écologique, dénommé provisoirement la sous-phase écologique

Development of Northern White-Cedar Regeneration Following Partial Cutting, with and without Deer Browsing

Northern white-cedar (Thuja occidentalis L.) is an important commercial species with a high wildlife value, both as a food source and habitat for many bird and mammal species. Concerns have been expressed about its decreasing abundance across its range, and especially in mixedwood stands, where it has to compete with several other species and can suffer from heavy browsing. In this study, we quantified the development of natural northern white-cedar seedlings and saplings under various partial cutting regimes, with and without white-tailed deer (Odocoileus virgianus Zimmerman) browsing, in three selected sites in Quebec (Canada) and in Maine (USA). Our data show that northern white-cedar regeneration was present in all studied stands, but that only a few stems were taller than 30 cm on the two sites with high densities of deer. In the absence of heavy browsing, stems reached a height of 30 cm in 11 years, and 130 cm in 28 years. Height growth of northern white-cedar regeneration increased with canopy light transmittance, while ground-level diameter increment increased after partial cutting. This suggests that partial cutting can be used in mixedwood stands to release natural northern white-cedar regeneration, but also that the recruitment of northern white-cedar seedlings to larger size classes constitutes a major challenge in stands subject to heavy deer browsing

Influence of Stand Density on Ring Width and Wood Density at Different Sampling Heights in Black Spruce (Picea Mariana (Mill.) B.S.P.)

Thirty-six black spruce sample trees were collected from an 80-year-old stand to examine the influence of stand density on selected wood quality attributes and their variation with sampling height. The stand, naturally regenerated from fire in 1906, was located in Chibougamau, 400 km north of Québec. Each tree was assigned a local stand density ranging from 1390 to 3590 stems/ha, calculated from the number of neighboring trees. The trees were grouped into three stand density categories (1790, 2700, and 3400 stems/ha). Each sample tree was analyzed by X-ray densitometry, and various ring features including ring width and wood density were measured for each ring from pith to bark, at three heights (2.4, 5.1, and 7.8m) and ring area and earlywood proportion were computed. For all features studied, the variation due to sampling height was larger than that due to stand density. The longitudinal variations for ring density and earlywood density depend largely upon the wood type (juvenile wood or mature wood). A variation of ring density with sampling height in the stem from 425 to 458 kg/m3 was observed in juvenile wood, but variations with stand density in all the growth ring features studied were small. Notably, it was observed that stand density had more influence on ring width features than on ring density features

A multi-scale analysis of the effects of alternative silvicultural treatments on windthrow within balsam fir dominated stands

Boreal ecosystem functioning is largely controlled by disturbance dynamics. There have been efforts at adapting forest management approaches to emulate natural disturbance effects as this is expected to maintain ecosystem resilience. In many instances, this involves resorting to partial cutting strategies that are likely to increase windthrow losses. The objective of this study was to determine the effects of alternative silvicultural practices on windthrow damage and how these effects vary with the scale of treatment. The study was conducted in the Quebec north shore region (Canada), an area dominated by balsam fir (Abies balsamea (L.) Mill.) accompanied by black spruce (Picea mariana (Mill) B.S.P.). Four different silvicultural treatments (overstory removal, heavy partial cutting, and two patterns of selection cutting) and control areas were implemented in 2004 and 2005. The experiment used a nested approach where treatment at the plot level was independent and yet nested within block- level treatment. At the block level, treatments were applied over 10-20 ha units, leaving a small portion of the block for a smaller application of each treatment (2500 m2, plot scale). Inventory was carried out before harvesting and monitoring was done yearly after harvesting, with the aim to better understand the plot- and block-level factors that drive windthrow damage levels and the effects of alternative silvicultural treatments. Results after 6-7 years show that, basal area proportion windthrown differs substantially between treatments as well as when treated sites were compared to control sites. Windthrow levels were higher under heavy cuts relative to selection cuts and also increased with balsam fir proportion. Windthrow proportions were better correlated to block-level treatment than plot-level treatment showing that the environment surrounding the treated plot can have an important effect on windthrow losses. Overall, selection cutting system particularly SC2, retains most green-tree basal area and thus best meets the management objective of retaining old-growth attributes. A simple empirical model was calibrated which could aid in hazard rating.The accepted manuscript in pdf format is listed with the files at the bottom of this page. The presentation of the authors' names and (or) special characters in the title of the manuscript may differ slightly between what is listed on this page and what is listed in the pdf file of the accepted manuscript; that in the pdf file of the accepted manuscript is what was submitted by the author

Variations in Northern white-cedar (Thuja occidentalis) regeneration following operational selection cutting in mixedwood stands of western Quebec.

Poorly adapted silvicultural practices and an increase in white-tailed deer (Odocoileus virginianus Zimmerman) populations have most likely contributed to a decline of northern white-cedar (Thuja occidentalis L.) in many regions of eastern North America. Suggestions have been made to use selection cutting in order to regenerate cedar in mixedwood stands but the approach has not yet been validated in an operational framework. The objective of this study was then to determine how local variations in stand condition and treatment application influence white-cedar regeneration at an operational scale in mixedwood stands. Seventy treated/control permanent plots, having at least 10% of basal area in cedar, were selected. A regeneration inventory was conducted in 2014, 15 to 20 years after harvesting activities. Results indicate that the selection cutting allows the establishment of white-cedar when deer densities are low, which was the case on the study sites. The abundance of seed trees, harvesting intensity, competition and the availability of establishment microsites influence the abundance, growth, and recruitment of white-cedar seedlings and saplings in the residual stand.The accepted manuscript in pdf format is listed with the files at the bottom of this page. The presentation of the authors' names and (or) special characters in the title of the manuscript may differ slightly between what is listed on this page and what is listed in the pdf file of the accepted manuscript; that in the pdf file of the accepted manuscript is what was submitted by the author