62 research outputs found
Cycle des feux, vieilles forĂȘts et amĂ©nagement en forĂȘt borĂ©ale de l'est du Canada
Les feux de forĂȘts constituent l'un des processus les plus importants de la forĂȘt borĂ©ale en Ă©tablissant les fondements d'une mosaĂŻque dynamique de peuplements forestiers Ă l'intĂ©rieur de laquelle une multitude d'autres processus interagissent. En initiant une succession secondaire, ils dĂ©terminent en partie la composition, la structure et la rĂ©partition spatiale des diffĂ©rents types d'habitats rencontrĂ©s en forĂȘt borĂ©ale. VoilĂ pourquoi il est souvent suggĂ©rĂ© que les impacts des perturbations anthropiques (e.g. coupes) sur les paysages amĂ©nagĂ©s seront attĂ©nuĂ©s si celles-ci Ă©mulent le mieux possible les patrons et processus normalement gĂ©nĂ©rĂ©s par les perturbations naturelles (e.g. feux de forĂȘt). Le cycle des feux, dĂ©fini comme le temps nĂ©cessaire Ă ce qu'une superficie cumulĂ©e Ă©gale au territoire Ă l'Ă©tude ait brĂ»lĂ© de nouveau, est un paramĂštre important du rĂ©gime des feux puisqu'il dĂ©termine la proportion des classes d'Ăąge Ă l'Ă©chelle du paysage. Or, les cycles des feux relativement longs documentĂ©s dans l'est du Canada suggĂ©raient que les paysages forestiers produits au terme de la premiĂšre rotation forestiĂšre industrielle seraient amputĂ©s d'une portion importante de la variĂ©tĂ© d'habitats qui caractĂ©risent les paysages produits par les perturbations naturelles. L'objectif principal de cette thĂšse Ă©tait donc de documenter le cycle des feux sur la CĂŽte-Nord, une rĂ©gion caractĂ©risĂ©e par une prĂ©sence particuliĂšrement importante de vieilles forĂȘts, ainsi que ses rĂ©percussions sur la dynamique successionelle des principales espĂšces d'arbres et les implications sur l'amĂ©nagement forestier en forĂȘt borĂ©ale de l'est du Canada. Dans un premier chapitre, nous avons Ă©valuĂ© le cycle des feux sur la CĂŽte-Nord ainsi que l'incertitude qui lui est associĂ©e Ă l'aide d'une approche par modĂ©lisation. Nous y comparons aussi trois mĂ©thodes d'analyses de survie pouvant ĂȘtre utilisĂ©es pour estimer le cycle des feux. Il s'est avĂ©rĂ© que l'approche non-paramĂ©trique, la rĂ©gression de Cox, permet l'obtention d'une estimation plus robuste aux variations temporelles de l'activitĂ© des feux, la source de biais potentiel la plus importante. Ă l'aide de cette mĂ©thode, nous avons pu estimer Ă environ 227 ans le cycle des feux rĂ©cent dans le territoire Ă l'Ă©tude, une valeur Ă laquelle est toutefois associĂ©e un intervalle de confiance Ă 95% de ±60 Ă 70 ans. Dans un second chapitre, nous avons isolĂ© les facteurs responsables d'une hĂ©tĂ©rogĂ©nĂ©itĂ© spatiale de la frĂ©quence des feux sur la CĂŽte-Nord, qui se sont avĂ©rĂ©s dĂ©pendre fortement de l'Ă©chelle spatiale Ă laquelle ils sont dĂ©crits en raison du caractĂšre contagieux des feux de forĂȘt. Il s'est avĂ©rĂ© qu'au sein d'un mĂȘme paysage, certaines grandes zones dominĂ©es par des versants exposĂ©s au sud Ă©taient 2 Ă 6 fois plus susceptibles que d'autres, affectant ainsi la rĂ©partition de peuplements forestiers distincts au niveau de la composition et/ou de la structure. Nous avons ensuite testĂ© l'influence de cette hĂ©tĂ©rogĂ©nĂ©itĂ© sur la dynamique des peuplements au moyen d'analyses multivariĂ©es des communautĂ©s vĂ©gĂ©tales. Nous avons ainsi tentĂ© d'isoler l'influence du temps depuis le dernier feu en tant que tel de l'appartenance Ă un contexte oĂč les feux sont plus ou moins frĂ©quents. De façon gĂ©nĂ©rale, c'est seulement dans les zones Ă faible frĂ©quence des feux que le principal spĂ©cialiste de fin de succession, le sapin baumier, arrive Ă supplanter l'espĂšce globalement la plus abondante en forĂȘt borĂ©ale de l'est du Canada, l'Ă©pinette noire, en raison du temps depuis le dernier feu gĂ©nĂ©ralement plus long. Nos rĂ©sultats suggĂšrent aussi que la succession de P. mariana vers A. balsamea peut se produire longtemps aprĂšs ce qui est gĂ©nĂ©ralement couvert par les reconstitutions dendroĂ©cologiques de l'historique des feux dans ce type de paysages borĂ©aux (>200-300 ans). En dernier lieu, nous nous sommes intĂ©ressĂ©s Ă un autre paysage forestier borĂ©al, situĂ©s Ă l'extrĂȘme ouest du QuĂ©bec en partie sur la portion nord de l'Abitibi et au sud de la JamĂ©sie. Nous avons examinĂ© la variabilitĂ© Ă plus long terme (6800 ans) de l'activitĂ© des feux au moyen d'une reconstitution palĂ©oĂ©cologique basĂ©e sur les fragments de charbon enfouis dans les sĂ©diments de lac stratifiĂ©s. Cette analyse nous a permis de dĂ©crire ce que nous soutenons ĂȘtre une plage de variabilitĂ© naturelle pertinente pour l'Ă©tablissement de cibles d'amĂ©nagement, qui fut comparĂ©e Ă l'Ă©tat actuel du paysage Ă©tudiĂ©. Nos rĂ©sultats confirment les apprĂ©hensions selon lesquels l'amĂ©nagement nĂ©glige une importante proportion des paysages borĂ©aux naturels, i.e. les vieilles forĂȘts, puisque celles-ci semblent avoir occupĂ© une portion importante de ce paysage au cours de l'ensemble de son histoire post-glaciaire, une rĂ©alitĂ© qui a rapidement Ă©tĂ© altĂ©rĂ©e au cours des trois derniĂšres dĂ©cennies de rĂ©colte extensive. \ud
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MOTS-CLĂS DE LâAUTEUR : Feux de forĂȘt, CĂŽte-Nord, Abitibi, QuĂ©bec, AmĂ©nagement forestier Ă©cosystĂ©mique, Ăpinette noire, Cycle des feux, FrĂ©quence des feux, PalĂ©oĂ©cologie, Analyses de survie
Captation des particules fines par les arbres : cas des grands parcs montréalais
La matiĂšre particulaire est un agent nocif pour la santĂ© humaine et la rĂ©duction de sa concentration atmosphĂ©rique est nĂ©cessaire dans une approche de santĂ© publique. Lâatteinte de cet objectif passe par, entre autres, la captation des particules par la vĂ©gĂ©tation. La question que nous nous sommes posĂ©s est: quel est le potentiel de captation des arbres publics dans la ville de MontrĂ©al. Comme site Ă lâĂ©tude, nous avons choisi les grands parcs, car leur vĂ©gĂ©tation arborescente couvre un pourcentage important de leur surface. Le modĂšle de captation de la matiĂšre particulaire du logiciel i-Tree a Ă©tĂ© utilisĂ© pour dĂ©finir la capacitĂ© de purification de lâair selon les caractĂ©ristiques spĂ©cifiques de chaque parc. Ces caractĂ©ristiques comprennent lâindice de surface foliaire des arbres (LAI) et lâĂ©tendue des canopĂ©es, les conditions mĂ©tĂ©orologiques ainsi que les concentrations des particules dans lâair. Plusieurs mĂ©thodes et techniques de calcul de ces paramĂštres ont Ă©tĂ© testĂ©s et les plus appropriĂ©es retenues pour le calcul des intrants. Les calculs ont Ă©tĂ© faits sur une base journaliĂšre pour lâensemble de lâannĂ©e 2017. Les rĂ©sultats montrent que le total des particules captĂ©es pendant lâannĂ©e 2017 sâĂ©lĂšve Ă un peu plus que 3.5 tonnes pour les quatorze parcs Ă©valuĂ©s. Selon nos calculs, la majeure partie de ces particules a Ă©tĂ© lessivĂ©e au sol par les pluies et un faible pourcentage a Ă©tĂ© remis en circulation. Un test de validation des rĂ©sultats in situ nâa pas Ă©tĂ© concluant. Il nâen demeure pas moins que les rĂ©sultats sont similaires aux rĂ©sultats des recherches effectuĂ©es dans dâautres villes Nord-AmĂ©ricaines avec le modĂšle dâi-Tree. Ces rĂ©sultats montrent que le rĂŽle des arbres pour la purification de lâair est important tout au moins localement. Les possibilitĂ©s dâamĂ©liorer les mĂ©thodes de calcul des intrants du modĂšle de captation sont Ă©galement discutĂ©es.Particulate matter is an agent harmful to human health and reducing its atmospheric concentration is necessary from a public health approach. Achieving this objective requires, among other things, the capture of particles by vegetation. Our research question was what is the potential of public trees in the city of Montreal for capturing such particles. We chose large parks as our study site, because trees cover a significant percentage of their surface. The particulate matter capture model of the i-Tree software was used to define the air purification capacity according to the specific characteristics of each park. These characteristics include tree leaf area index (LAI) and canopy extent, weather conditions, and particulate matter concentrations in the air. Several methods and techniques for calculating these parameters were tested and the most appropriate ones used for the calculation of inputs to the model. Calculations were made on a daily basis for the whole of 2017. The results show that just over 3.5 tonnes of particles were captured for the fourteen parks evaluated over this period. According to our calculations, most of these particles were leached to the ground by rain and a small percentage were put back into circulation. A validation test of the results in situ was inconclusive. The fact remains that the results are similar to those of research carried out in other North American cities with the i-Tree model. These results show that the role of trees for air purification is important at least locally. Possibilities for improving the methods of calculating the inputs for the capture model are also discussed
Implementation of a Parenting Coordination Pilot Project in Montreal, Canada: What Did We Learn?
For parents who experience high conflict following their separation or divorce, the various psychosocial and legal services provided by the government of Quebec or in the private sector have proven to be inadequate, resulting in an over-dependence on the court system and child protective services to provide solutions. In response to this social dilemma, the Quebec Ministry of Justice agreed in 2012 to fund a pilot project to determine if parenting coordination could provide some relief to the families and to the judicial system. A research team also had the mandate to evaluate the extent to which parenting coordination could eventually be integrated with other services being offered in both the public and private sectors. Between 2012 and 2014, ten families were followed by two parenting coordinators for a period ranging from six to 18 months. This article will present the interdisciplinary model put forward in the implementation of a parental coordination project, some highlights of the results of this pilot project and the recommendations that ensued.
Forest management is driving the eastern North American boreal forest outside its natural range of variability
Fire is fundamental to the natural dynamics of the North American boreal forest. It is therefore often suggested that the impacts of anthropogenic disturbances (eg logging) on a managed landscape are attenuated if the patterns and processes created by these events resemble those of natural disturbances (eg fire). To provide forest management guidelines, we investigate the long-term variability in the mean fire interval (MFI) of a boreal landscape in eastern North America, as reconstructed from lacustrine (lake-associated) sedimentary charcoal. We translate the natural variability in MFI into a range of landscape age structures, using a simple modeling approach. Although using the array of possible forest age structures provides managers with some flexibility, an assessment of the current state of the landscape suggests that logging has already caused a shift in the age-class distribution toward a stronger representation of young stands with a concurrent decrease in old-growth stands. Logging is indeed quickly forcing the studied landscape outside of its long-term natural range of variability, implying that substantial changes in management practices are required, if we collectively decide to maintain these fundamental attributes of the boreal forest
Earnings Management in the Charitable Sector: A Canadian Study
This article examines whether charitable organizations use discretionary accruals to manage their surplus or deficit. Linear regression was used to analyze the financial data of a broad sample of Canadian charitable organizations. Results showed that discretionary accruals were used to manage these income figures. This approach is compounded by the magnitude of grants, public benefit, and leverage. The results hold whether the charity anticipates a surplus or a deficit, but not if it displays a high level of public benefit. In that case, charities with an anticipated surplus increase their use of discretionary accruals to decrease earnings, whereas charities that anticipate a deficit are not inclined to manage their deficit toward zero. This study complements prior literature on nonprofits and shows that even though tax laws differ among countries, charity managers in various contexts are motivated to manage earnings and are influenced by various factors in doing so
Converging and diverging burn rates in North American boreal forests from the Little Ice Age to the present
Warning. This article contains terms, descriptions, and opinions used for historical context that may be culturally sensitive for some readers. Background. Understanding drivers of boreal forest dynamics supports adaptation strategies in the context of climate change. Aims. We aimed to understand how burn rates varied since the early 1700s in North American boreal forests. Methods. We used 16 fire-history study sites distributed across such forests and investigated variation in burn rates for the historical period spanning 1700-1990. These were benchmarked against recent burn rates estimated for the modern period spanning 1980-2020 using various data sources. Key results. Burn rates during the historical period for most sites showed a declining trend, particularly during the early to mid 1900s. Compared to the historical period, the modern period showed less variable and lower burn rates across sites. Mean burn rates during the modern period presented divergent trends among eastern versus northwestern sites, with increasing trends in mean burn rates in most northwestern North American sites. Conclusions. The synchronicity of trends suggests that large spatial patterns of atmospheric conditions drove burn rates in addition to regional changes in land use like fire exclusion and suppression. Implications. Low burn rates in eastern Canadian boreal forests may continue unless climate change overrides the capacity to suppress fire.Peer reviewe
Well-being of Canadian Veterans during the COVID-19 pandemic:cross-sectional results from the COVID-19 Veteran well-being study
Background: The impacts of the COVID-19 pandemic have disproportionally affected different population groups. Veterans are more likely to have pre-existing mental health conditions compared to the general Canadian population, experience compounded stressors resulting from disruptions to familial, social, and occupational domains, and were faced with changes in health-care delivery (e.g. telehealth). The objectives of this study are to assess (a) the mental health impact of COVID-19 and related life changes on the well-being of Veterans and (b) perceptions of and satisfaction with changes in health-care treatments and delivery during the pandemic. Methods: A total of 1136 Canadian Veterans participated in an online survey. Participants completed questions pertaining to their mental health and well-being, lifestyle changes, and concerns relating to the COVID-19 pandemic, as well as experiences and satisfaction with health-care treatments during the pandemic. Results: Results showed that 55.9% of respondents reported worse mental health functioning compared to before the pandemic. The frequency of probable posttraumatic stress disorder, major depressive disorder, generalized anxiety disorder, alcohol use disorder, and suicidal ideation were 34.2%, 35.3%, 26.8%, 13.0%, and 22.0%, respectively. Between 38.6% and 53.1% of respondents attributed their symptoms as either directly related to or exacerbated by the pandemic. Approximately 18% of respondents reported using telehealth for mental health services during the pandemic, and among those, 72.8% indicated a choice to use telehealth even after the pandemic. Conclusions: This study found that Veterans experienced worsening mental health as a result of the COVID-19 pandemic. The use of telehealth services was widely endorsed by mental health treatment-seeking Veterans who transitioned to virtual care during the pandemic. Our findings have important clinical and programmeadministrator implications, emphasizing the need to reach out to support veterans, especially those with pre-existing mental health conditions and to enhance and maintain virtual care even post-pandemic.</p
Well-being of Canadian Veterans during the COVID-19 pandemic: cross-sectional results from the COVID-19 Veteran well-being study
Background: The impacts of the COVID-19 pandemic have disproportionally affected different population groups. Veterans are more likely to have pre-existing mental health conditions compared to the general Canadian population, experience compounded stressors resulting from disruptions to familial, social, and occupational domains, and were faced with changes in health-care delivery (e.g. telehealth). The objectives of this study are to assess (a) the mental health impact of COVID-19 and related life changes on the well-being of Veterans and (b) perceptions of and satisfaction with changes in health-care treatments and delivery during the pandemic. Methods: A total of 1136 Canadian Veterans participated in an online survey. Participants completed questions pertaining to their mental health and well-being, lifestyle changes, and concerns relating to the COVID-19 pandemic, as well as experiences and satisfaction with health-care treatments during the pandemic. Results: Results showed that 55.9% of respondents reported worse mental health functioning compared to before the pandemic. The frequency of probable posttraumatic stress disorder, major depressive disorder, generalized anxiety disorder, alcohol use disorder, and suicidal ideation were 34.2%, 35.3%, 26.8%, 13.0%, and 22.0%, respectively. Between 38.6% and 53.1% of respondents attributed their symptoms as either directly related to or exacerbated by the pandemic. Approximately 18% of respondents reported using telehealth for mental health services during the pandemic, and among those, 72.8% indicated a choice to use telehealth even after the pandemic. Conclusions: This study found that Veterans experienced worsening mental health as a result of the COVID-19 pandemic. The use of telehealth services was widely endorsed by mental health treatment-seeking Veterans who transitioned to virtual care during the pandemic. Our findings have important clinical and programmeadministrator implications, emphasizing the need to reach out to support veterans, especially those with pre-existing mental health conditions and to enhance and maintain virtual care even post-pandemic
Well-being of Canadian Veterans during the COVID-19 pandemic:cross-sectional results from the COVID-19 Veteran well-being study
Background: The impacts of the COVID-19 pandemic have disproportionally affected different population groups. Veterans are more likely to have pre-existing mental health conditions compared to the general Canadian population, experience compounded stressors resulting from disruptions to familial, social, and occupational domains, and were faced with changes in health-care delivery (e.g. telehealth). The objectives of this study are to assess (a) the mental health impact of COVID-19 and related life changes on the well-being of Veterans and (b) perceptions of and satisfaction with changes in health-care treatments and delivery during the pandemic. Methods: A total of 1136 Canadian Veterans participated in an online survey. Participants completed questions pertaining to their mental health and well-being, lifestyle changes, and concerns relating to the COVID-19 pandemic, as well as experiences and satisfaction with health-care treatments during the pandemic. Results: Results showed that 55.9% of respondents reported worse mental health functioning compared to before the pandemic. The frequency of probable posttraumatic stress disorder, major depressive disorder, generalized anxiety disorder, alcohol use disorder, and suicidal ideation were 34.2%, 35.3%, 26.8%, 13.0%, and 22.0%, respectively. Between 38.6% and 53.1% of respondents attributed their symptoms as either directly related to or exacerbated by the pandemic. Approximately 18% of respondents reported using telehealth for mental health services during the pandemic, and among those, 72.8% indicated a choice to use telehealth even after the pandemic. Conclusions: This study found that Veterans experienced worsening mental health as a result of the COVID-19 pandemic. The use of telehealth services was widely endorsed by mental health treatment-seeking Veterans who transitioned to virtual care during the pandemic. Our findings have important clinical and programmeadministrator implications, emphasizing the need to reach out to support veterans, especially those with pre-existing mental health conditions and to enhance and maintain virtual care even post-pandemic.</p
Well-being of Canadian Armed Forces Veterans and Spouses of Veterans during the COVID-19 Pandemic: Protocol for a Prospective Longitudinal Survey
Background: The COVID-19 pandemic has resulted in significant changes to everyday life, including social distancing mandates, changes to health care, and a heightened risk of infection. Previous research has shown that Canadian Armed Forces (CAF) veterans are at higher risk of developing mental and physical health conditions. Veterans and their families may face unique social challenges that can compound with pandemic-related disruptions to negatively impact well-being. Objective: This study aims to longitudinally characterize the mental health of CAF veterans and spouses of CAF veterans throughout the pandemic and to understand the dynamic influences of pandemic-related stressors on psychological health over time. Methods: We employed a prospective longitudinal panel design using an online data collection platform. Study participation was open to all CAF veterans and spouses of CAF veterans residing in Canada. Participants were asked to complete a comprehensive battery of assessments representing psychological well-being, chronic pain, health care access patterns, physical environment, employment, social integration, and adjustment to pandemic-related lifestyle changes. Follow-up assessments were conducted every 3 months over an 18-month period. This study was approved by the Western University Health Sciences and Lawson Health Research Institute Research Ethics Boards. Results: Baseline data were collected between July 2020 and February 2021. There were 3 population segments that participated in the study: 1047 veterans, 366 spouses of veterans, and 125 veterans who are also spouses of veterans completed baseline data collection. As of November 2021, data collection is ongoing, with participants completing the 9-or 12-month follow-up surveys depending on their date of self-enrollment. Data collection across all time points will be complete in September 2022. Conclusions: This longitudinal survey is unique in its comprehensive assessment of domains relevant to veterans and spouses of veterans during the COVID-19 pandemic, ranging from occupational, demographic, social, mental, and physical domains, to perceptions and experiences with health care treatments and access. The results of this study will be used to inform policy for veteran and veteran family support, and to best prepare for similar emergencies should they occur in the future
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