Preserving Ecosystem Services on Indigenous Territory through Restoration and Management of a Cultural Keystone Species

Eastern white pine (Pinus strobus L.) is a cultural keystone tree species in the forests of eastern North America, providing numerous ecosystem services to Indigenous people. White pine abundance in the landscape has considerably decreased over the last few centuries due to overharvesting, suppression of surface fires, extensive management, and plantation failure. The Kitcisakik Algonquin community of western Quebec is calling for restoration and sustainable management of white pine on its ancestral territory, to ensure provision of associated ecosystem services. We present five white pine restoration and management scenarios taking into account community needs and ecological types: (1) natural regeneration of scattered white pines to produce individuals of different sizes and ages used as medicinal plants; (2) protection of supercanopy white pines used as landmarks and for providing habitat for flagship wildlife species, and younger individuals left as regeneration and future canopy trees; (3) the uniform shelterwood system to create white pine-dominated stands that provide habitat for flagship wildlife species and support cultural activities; (4) under-canopy plantations to yield mature white pine stands for timber production; (5) mixed plantations to produce forests with aesthetic qualities that provide wildlife habitat and protect biodiversity

Synthèse de fréquences optiques

Tableau d’honneur de la Faculté des études supérieures et postdoctorales, 2015-2016Le présent mémoire traite de la génération de radiation électromagnétique périodique dans le proche infrarouge. La fréquence d’oscillation optique de cette radiation est référencée à un ou plusieurs standards de temps-fréquence et peut être changée à volonté. L’instrument remplissant ces fonctions est appelé synthétiseur de fréquences optiques. Cet instrument serait très utile dans les applications nécessitant de la lumière à une fréquence bien connue, comme la spectroscopie, la calibration de sources optiques et d’autres applications en métrologie. Pour cette raison, un intérêt pour la synthèse de fréquences optiques est déjà présent dans la communauté scientifique. Ici, un tel instrument est présenté. Ce dernier est basé sur l’usage d’un laser accordable et d’une ou plusieurs sources de référence. Un peigne de fréquences optiques est utilisé pour faire le pont entre ces différentes sources. Plus spécifiquement, le présent mémoire contient une discussion des difficultés que présente la construction d’un tel instrument. Ces difficultés sont principalement liées à la mesure de la fréquence relative entre les sources utilisées et le peigne de fréquences. Plusieurs solutions à ces difficultés sont ensuite proposées. Le tout est suivi par les détails d’une démonstration expérimentale d’un véritable synthétiseur de fréquences optiques.This work is about the generation of periodic near-infrared electromagnetic radiation whose oscillation frequency can be changed at will while being linked to time and frequency standards. The instrument enabling these functions is called an optical frequency synthesiser. Such an instrument would be tremendously useful in applications requiring very precise optical frequencies, including spectroscopy, calibration of sources and many other applications in metrology. For this reason, the scientific community has already shown interest. Here, an optical frequency synthesiser is presented. The instrument is based on the combination of a tunable laser, one or many reference sources and an optical frequency comb, the latter being used to link the sources together. In this work, difficulties associated with the implementation of such an instrument are discussed. These difficulties are mostly related to the measurement of the relative frequencies between the sources and the frequency comb. Many solutions to these difficulties are given, followed by the implementation and performance details of an actual optical frequency synthesiser

Environmental controls of the northern distribution limit of yellow birch in eastern Canada

To evaluate environmental controls of yellow birch (Betula alleghaniensis Britton) distribution at its northern distribution limit in eastern Canada, we analyzed abundance, age structure, biomass accumulation rate, and growth sensitivity to climate of this species at 14 sites along a 200 km latitudinal gradient spanning three bioclimatic domains and reaching frontier populations of this species in western Quebec. We observed a large variability in seedling density across domains and presence of sites with abundant yellow birch regeneration within all three bioclimatic domains. Seedling density was positively correlated to mean age and abundance of yellow birch trees in the canopy, while sapling density was positively associated with dryer habitats. Growth patterns of canopy trees showed no effect of declining temperatures along the south-north gradient. Environmental controls of birch distribution at its northern limit were realized through factors affecting birch regeneration and not growth of canopy trees. At the stand scale, regeneration density was strongly controlled by local site conditions and not by differences in climate among sites. At the regional scale, climate variability could be an indirect driver of yellow birch distribution, affecting disturbance rates and, subsequently, availability of suitable sites for regeneration

Contribution of traditional knowledge to ecological restoration : practices and applications

Traditional knowledge has become a topic of considerable interest within the research and development environment. The contribution of traditional knowledge to conservation and management is increasingly recognized, and implementation endeavours are underway in several countries. The current scale of ecosystem degradation underscores the need for restoration interventions. It is increasingly recognized that successful ecological restoration depends on effective coordination of science and traditional ecological knowledge. This paper synthesizes the literature to evaluate the present and potential contribution of traditional knowledge to ecological restoration. Despite a growing number of articles published on traditional knowledge, only a few have addressed its contributions to ecological restoration per se. The main contributions of traditional knowledge to ecological restoration are in construction of reference ecosystems, particularly when historical information is not available; species selection for restoration plantations; site selection for restoration; knowledge about historical land management practices; management of invasive species; and post-restoration monitoring. Traditional knowledge and science are complementary and should be used in conjunction in ecological restoration projects. Incorporation of traditional knowledge can contribute to build a strong partnership for the successful implementation of restoration projects and increase their social acceptability, economical feasibility, and ecological viability. L'intérêt du secteur de la recherche et développement pour les connaissances traditionnelles est considérable. La contribution des savoirs traditionnels à la conservation et à l'aménagement est de plus en plus reconnue et des expériences terrain en ce sens sont en cours dans plusieurs pays. Le niveau de dégradation des écosystèmes justifie le besoin d'interventions de restauration. Il est de plus en plus reconnu que l'intégration des connaissances scientifiques et traditionnelles est nécessaire au succès des efforts de restauration. Cette synthèse évalue les contributions actuelles et potentielles des savoirs traditionnels à la restauration écologique. Malgré qu'un nombre croissant d'articles soient publiés à propos des connaissances traditionnelles, peu concernent la contribution à la restauration écologique. Les principales contributions des connaissances traditionnelles à la restauration écologique sont l'identification d'écosystèmes de référence, en particulier lorsque les informations historiques ne sont pas disponibles; la sélection d'espèces pour les plantations; la sélection de sites pour la restauration; la connaissance de l'historique local des pratiques d'aménagement; la gestion des espèces envahissantes; et le suivi post-restauration. Les connaissances traditionnelles et scientifiques sont complémentaires et devraient être utilisées conjointement dans les projets de restauration écologique. L'inclusion des connaissances traditionnelles peut contribuer à construire un partenariat solide pour le succès de mise en œuvre de projets de restauration et pour en augmenter l'acceptabilité sociale, la faisabilité économique et la viabilité écologique

Holocene variations of wildfire occurrence as a guide for sustainable management of the northeastern Canadian boreal forest

Background Cumulative impacts of wildfires and forest harvesting can cause shifts from closed-crown forest to open woodland in boreal ecosystems. To lower the probability of occurrence of such catastrophic regime shifts, forest logging must decrease when fire frequency increases, so that the combined disturbance rate does not exceed the Holocene maximum. Knowing how climate warming will affect fire regimes is thus crucial to sustainably manage the forest. This study aimed to provide a guide to determine sustainable forest harvesting levels, by reconstructing the Holocene fire history at the northern limit of commercial forestry in Quebec using charcoal particles preserved in lake sediments. Methods Sediment cores were sampled from four lakes located close to the northern limit of commercial forestry in Quebec. The cores were sliced into consecutive 0.5 cm thick subsamples from which 1 cm3 was extracted to count and measure charcoal particles larger than 150 microns. Age-depth models were obtained for each core based on accelerator mass spectroscopy (AMS) radiocarbon dates. Holocene fire histories were reconstructed by combining charcoal counts and age-depth models to obtain charcoal accumulation rates and, after statistical treatment, long-term trends in fire occurrence (expressed as number of fires per 1000 years). Results Fire occurrence varied between the four studied sites, but fires generally occurred more often during warm and dry periods of the Holocene, especially during the Holocene Thermal Maximum (7000–3500 cal. BP), when fire occurrence was twice as high as at present. Conclusions The current fire regime in the study area is still within the natural range of variability observed over the Holocene. However, climatic conditions comparable to the Holocene Thermal Maximum could be reached within the next few decades, thus substantially reducing the amount of wood available to the forest industry

Infinite All-Layers Simple Foldability

We study the problem of deciding whether a crease pattern can be folded by simple folds (folding along one line at a time) under the infinite all-layers model introduced by [Akitaya et al., 2017], in which each simple fold is defined by an infinite line and must fold all layers of paper that intersect this line. This model is motivated by folding in manufacturing such as sheet-metal bending. We improve on [Arkin et al., 2004] by giving a deterministic $O(n)$-time algorithm to decide simple foldability of 1D crease patterns in the all-layers model. Then we extend this 1D result to 2D, showing that simple foldability in this model can be decided in linear time for unassigned axis-aligned orthogonal crease patterns on axis-aligned 2D orthogonal paper. On the other hand, we show that simple foldability is strongly NP-complete if a subset of the creases have a mountain-valley assignment, even for an axis-aligned rectangle of paper