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Quick clays of eastern Canada

Quick clays of eastern Canada

Quick clays of eastern Canada Crawford, C. B. https://publications-cnrc.canada.ca/fra/droits L’accès à ce site Web et l’utilisation de son contenu sont assujettis aux conditions présentées dans le site LISEZ CES CONDITIONS ATTENTIVEMENT AVANT D’UTILISER CE SITE WEB.

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Application of ensemble-based systems for snow-mapping using NOAA-AVHRR data over Eastern Canada.

Application of ensemble-based systems for snow-mapping using NOAA-AVHRR data over Eastern Canada.

Ensemble-based systems allow combination of multiple classifier results to reach a final decision that is presumably the most informed one [3]. Decision-making systems are composed of (1) algorithms for generating the individual components of the ensemble system - the most popular ones being bagging, boosting, Adaboost, stack generalization, and hierarchical mixture-of-experts - and (2) a set of combination rules, including algebraic combination of outputs or voting-based techniques. In this study, bagging and majority voting have been implemented in the snow- mapping procedure we developed over Eastern Canada.
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An illustrated key to the mandibles of small mammals of eastern Canada

An illustrated key to the mandibles of small mammals of eastern Canada

Results and Discussion We found that 55 of the 60 small mammal species of eastern Canada could be identified from their man - dibles. the White-footed Mouse (Peromyscus leuco- pus) and the Deer Mouse (P. maniculatus) could not be identified to the species level, because their mandibles are identical. Although both Peromyscus species may be differentiated using several skull measurements, biochemical and genetic markers are probably the only reliable methods to date (Aquadro and patton 1980; rich et al. 1996). Similarly, three species of lagomorphs (i.e., Lepus arcticus, L. europaeus, and L. townsendii) could not be distinguished using the mandibles alone. Consulting species’ distribution may facilitate iden- tification of small mammals (banfield 1974; Desrosiers et al. 2002; naughton 2012). For example, Sciurus
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Three billion years of crustal evolution in eastern Canada: Constraints from receiver functions

Three billion years of crustal evolution in eastern Canada: Constraints from receiver functions

3. Data and Seismograph Networks Our data come from broadband seismograph stations located across SE Canada (Figure 1). Earthquakes at epi- central distances >30∘ from the study region, with magnitudes M > 5.5, were recorded mostly between 2010 and 2013 (although some station data from as far back as 2005 are used). A number of different data sources are available in this region, including both permanent (Canadian National Seismograph Network, CNSN, 14 stations and Lamont-Doherty Cooperative Seismograph Network, LD, 2 stations) and temporary (PO: POLARIS [Eaton et al., 2005], 23 stations, and USArray Transportable Array, TA, 20 stations) seismograph networks. In addition, a new seismic network, the X8 QM-III EarthScope FlexArray (Québec-Maine Across Three Sutures), was installed in eastern Canada and the NE U.S. during the summers of 2012 and 2013. This project forms part of the EarthScope FlexArray program and is a collaboration between Rutgers University, Lamont-Doherty Earth Observatory, Université du Québec à Montréal, and Imperial College London. A quasi-linear profile stretches from central Québec to the Maine coast, and a distributed 2-D network is emplaced across the Canadian Maritime region. The eight “backbone” stations of the QM-III network were used in this study.
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Exploring pathways to late Holocene increased surface wetness in subarctic peatlands of eastern Canada

Exploring pathways to late Holocene increased surface wetness in subarctic peatlands of eastern Canada

ABSTRACT The poor fens of the Laforge region, northeastern Canada, have developed under subarctic conditions. They are characterized by a microtopography of large pools and low, narrow strings. Paleorecords suggest some of these systems were once ombrotrophic and relatively dry. Taking account of their current ecoclimatic position, we aimed to explore the possible pathways towards the current wet state, a process referred to as ‘aqualysis’. We combined paleoecological methods applied to a peat core with conceptual modelling to identify factors that might plausibly explain aqualysis. Reconstructions showed the Abeille peatland became minerotrophic with high water tables between 2400 and 2100 cal yr BP. Conceptual modelling, supported by simulations using the numerical DigiBog model, allowed us to identify the effects of cooling and increased precipitation on productivity, decay, peat hydraulic conductivity and vertical peat accumulation. Both cooling and increased precipitation were required for aqualysis to occur and for wet surface conditions to persist to the present day. Increased recharge from the catchment, which also restricted drainage from the peatland center laterally, was likely critical for the development of minerotrophic conditions. The scenario of cooling and wetting in these peatlands is supported by available paleoclimate records for eastern Canada.
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Structural diversity and dynamics of boreal old-growth forests case study in Eastern Canada

Structural diversity and dynamics of boreal old-growth forests case study in Eastern Canada

Consequently, true boreal old-growth forests in Eastern Canada present a variety of structures and compositions, mainly determined by topography and secondary disturbance dynamics. Eastern white cedar (Thuja occidentalis L.) and white spruce (Picea glauca (Moench) Voss), the two other late-successional species in Eastern Canada (Harvey et al. 2002), are almost absent in our study territory. In addition, Eastern Canada is not a totally homogeneous territory, presenting particular geomorphologic properties, such as the Clay-Belt region dominated by clay soils rather than tills (Harper et al. 2003; Lecomte and Bergeron 2005; Bergeron and Harper 2009), or particular climatic conditions, such as the moist maritime climates at the eastern edge of Canada (Bouchard and Pothier 2011; Kneeshaw et al. 2011). The identified structures are consequently unlikely to represent all the structural diversity of Eastern Canadian boreal old-growth forests but represent a regional subset of the whole. At a larger scale, these structures cannot be generalized to territories defined by other climatic conditions, disturbance dynamics and species traits (Shorohova et al. 2008; Kneeshaw et al. 2011; Shorohova et al. 2011). Despite this, black spruce dominated stands or black spruce – balsam fir mixtures are the main late- successional forest formations in Eastern Canadian boreal forest (De Grandpré et al. 2000; Bouchard et al. 2008; Gauthier et al. 2010), and our work therefore provides a pertinent analysis of the boreal old-growth diversity and internal dynamics in Eastern Canada. Furthermore, our study underlines the importance in identifying the structural richness of boreal old-growth forests at a fine scale, as these complex ecosystems should not be considered as a uniform entity, even in a seemingly homogeneous landscape.
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Parental care by Black-backed Woodpeckers in burned and unburned habitats of eastern Canada

Parental care by Black-backed Woodpeckers in burned and unburned habitats of eastern Canada

Junior A. Tremblay, Jacques Ibarzabal, Marie-Christine Saulnier & Scott Wilson 2016. Parental care by Black-backed Woodpeckers in burned and unburned habitats of eastern Canada. – Or- nis Hungarica 24(1): 69–80. Abstract Nest care is an important parental contribution to offspring. In woodpeckers, males often have an equal or greater contribution to parental care, including nest sanitation. The Black-backed Wood- pecker (Picoides arcticus) is a North American boreal woodpecker for which both parents are highly involved in parental care. By modifying their territory size in optimal and suboptimal habitat (e.g. burned vs unburned ha- bitats), this species seems to have a large tolerance to variation in prey abundance at a landscape scale, and could provide a useful biological model to investigate the adaptability of parent care, particularly to relative contribu- tion of each sex. We investigated sex- and habitat-specific parental care behaviour of Black-backed Woodpeckers at 9 nests by daily monitoring during the nestling period. Specifically, we examined two different aspects of pa- rental care: 1) time spent at the nest, and 2) food delivery. We also compared relative contribution between sexes to nest sanitation. Despite our small sample sizes, our results show that males are more involved in nest sanitation and spend longer at the nest, and both sexes exhibit higher food delivery rates and spend less time at the nest in burned habitat. This latter result may suggest that greater effort is needed to provision Black-backed Wood pecker nestlings in unburned habitat compared to burned habitat.
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Variability and origin of seismic anisotropy across eastern Canada: Evidence from shear wave splitting measurements

Variability and origin of seismic anisotropy across eastern Canada: Evidence from shear wave splitting measurements

challenging beneath shields, whose thick (≥200 km) lithospheric roots may record a protracted history of deformation and strongly influence underlying mantle flow. Eastern Canada, where the geological record spans ∼3 Ga of Earth history, is an ideal region to address this issue. We use shear wave splitting measurements of core phases such as SKS to define upper mantle anisotropy using the orientation of the fast-polarization direction 𝜙 and delay time 𝛿t between fast and slow shear wave arrivals. Comparison with structural trends in surface geology and aeromagnetic data helps to determine the contribution of fossil lithospheric fabrics to the anisotropy. We also assess the influence of sublithospheric mantle flow via flow directions derived from global geodynamic models. Fast-polarization orientations are generally ENE-WSW to ESE-WNW across the region, but significant lateral variability in splitting parameters on a ≤100 km scale implies a lithospheric contribution to the results. Correlations with structural geologic and magnetic trends are not ubiquitous, however, nor are correlations with geodynamically predicted mantle flow directions. We therefore consider that the splitting parameters likely record a combination of the present-day mantle flow and older lithospheric fabrics. Consideration of both sources of anisotropy is critical in shield regions when interpreting splitting observations.
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Soil data for mapping paludification in black spruce forests of eastern Canada

Soil data for mapping paludification in black spruce forests of eastern Canada

Value of the data  In the boreal forests of eastern Canada, organic layer thickness (OLT) is used as a proxy of the paludi fication process [1] .  Paludi fication is defined as the accumulation of partially decomposed organic matter over satu- rated mineral soils, a process that reduces tree regeneration and forest growth.

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The carbon fraction in biomass and organic matter in boreal open woodlands of Eastern Canada

The carbon fraction in biomass and organic matter in boreal open woodlands of Eastern Canada

The carbon fraction in biomass and organic matter in boreal open woodlands of Eastern Canada Abstract: In Canada, boreal open woodlands (OWs) show interesting afforestation potential, but no detailed studies are available regarding the carbon fraction (CF) in dry matter – tonne of C per tonne of dry mass – of biomass and litter reservoirs. This study aims at providing the very first specific CF values of C reservoirs and compartments in OWs, with the main hypothesis that given the particular stand characteristics of OWs, more precise CF values than IPCC’s default values will significantly change the calculation of C stocks in OWs. Results indicate that even though the CF values measured in this study were significantly different among the different C reservoirs and compartments in OWs, they match the IPCC default CF values for biomass (0.50) and humus (0.37) reservoirs. Therefore, the main hypothesis of this study – that more precise CF values than IPCC’s default values will significantly change the calculation of C stocks in OWs – was not supported by the results obtained. Consequently, the IPCC default values of CF in the biomass and litter (humus) reservoirs can be used when estimating the C stocks in boreal OWs, for example, when using OWs as the baseline scenario in afforestation projects.
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Fire Regime along Latitudinal Gradients of Continuous to Discontinuous Coniferous Boreal Forests in Eastern Canada

Fire Regime along Latitudinal Gradients of Continuous to Discontinuous Coniferous Boreal Forests in Eastern Canada

significantly reduced this bias and allowed for the calculation of realistic fire cycles. On a broad scale, other studies have shown the same gradient of increasing fire activity from south to north [24,48] and from east to west [21,24,48,51] in eastern Canada. On a narrower spatial scale, our fire cycle estimates are consistent with values calculated for similar regions over the same time period. In the southern zone of transect A, our fire cycle is consistent with previous estimates made in the commercial forest further south [51–53]. In the northern zone of the same transect, one of the most fire-prone regions of boreal Canada where very large fires occur at a high frequency [33,35], we estimated a fire cycle of five years. However, compared to the size of those fires, our transect zone is relatively small, meaning that individual fires can intersect a large fraction of the transect (Figure 2a). In this particular region where very large fires occur, thus regularly erasing marks of older fires, a method using TSF data over a relatively short transect in order to estimate fire cycles does not appear to be well suited. In this situation, the use of archive data to compute annual area burned, or a different sampling design covering a larger area better adapted to accounting for immense fires could be used instead. Based on fire interval data for the same transect zone, Héon et al. [33] estimated a fire cycle of 42 years for the time period 1910–2013. With such a short fire cycle, shifts of vegetation from black spruce- to jack pine- dominated stands can occur in this area [54,55]. Short fire intervals are also likely to limit stand regeneration and consequently lead to an opening of the forest [55,56], possibly into lichen-woodlands [55]. However, recent studies have shown that a negative feedback between fuel availability and fire activity has strongly limited the occurrence of these short intervals during the last two centuries [33,57]. The whole landscape could nonetheless burn regardless of the fuel continuity if either the number of ignition points or the frequency of extremely severe weather events are high enough. The northern zone of transect A thus constitutes a very interesting area to monitor in the future in order to better understand how strong the forest’s resilience to high fire activity is in this boreal ecosystem [35].
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A Merging Algorithm for Regional Snow Mapping over Eastern Canada from AVHRR and SSM/I Data.

A Merging Algorithm for Regional Snow Mapping over Eastern Canada from AVHRR and SSM/I Data.

Despite their fair performance in snow detection, these two algorithms suffer from limitations related to the two data types: the presence of clouds for AVHRR data and insufficient spatial resolution for SSM/I imagery. Several authors have shown the value of combining passive microwave and visible/infrared satellite data to map snow cover and monitor its evolution in time and space [1,4–6,17–21]. Romanov et al. [5] have shown that the multisensor technique is as precise as, or better than, IMS products, especially with respect to data consistency throughout the time series. This was confirmed by Simic et al. [1]. Moreover, Gao et al. [18] demonstrated that the combination of MODIS and AMSR-E removed all cloud and other contamination and dramatically increased snow map accuracy when compared to individual or combined Terra and Aqua MODIS snow products. They also suggested that the extension of such an approach to other optical and microwave sensors, such as AVHRR and SSM/I, would be of great interest, since it allows working with longer time series (1987–present instead of 2002–present). It should be noted that such an approach may face a major geographical limitation over mountainous areas, due to the topographical effects on (i) the optical radiometry and (ii) mainly on the low‐resolution passive data [22]. However, this is not the case for the landscape of rolling hills in Eastern Canada.
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Research Chair of CO2 geological sequestration in Québec, Eastern Canada: results after four years of research.

Research Chair of CO2 geological sequestration in Québec, Eastern Canada: results after four years of research.

Research chair on CO geological sequestration in Québec, Eastern Canada 2 Results after four years of research Félix-Antoine Comeau, Normand Tassé, Elena Konstantinovskaya, Tien Dung Tran Ngoc, Karine Bédard, Maxime Claprood, Franck Diedro, Jean-Christophe Aznar et Jean-Philibert Moutenet

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Regional analysis and modelling of water temperature metrics for atlantic salmon (Salmo salar) in Eastern Canada.

Regional analysis and modelling of water temperature metrics for atlantic salmon (Salmo salar) in Eastern Canada.

23 5 C ONC L US ION A first regional analysis of water temperature metrics was completed in Eastern Canada. Using water temperature monitoring stations with 5 or more years of data, two relatively homogenous thermal regions were defined for five different thermal metrics. The generalized additive model outperformed multiple linear regression as a tool to estimate the thermal metrics at ungauged sites within each region, as demonstrated by a leave-one-out validation procedure. Initial results are promising but further work is required to better define the thermally homogenous regions.
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Forest management has reduced the structural diversity of residual boreal old-growth forest landscapes in Eastern Canada

Forest management has reduced the structural diversity of residual boreal old-growth forest landscapes in Eastern Canada

(2020) Forest management has reduced the structural diversity of residual boreal old- growth forest landscapes in Eastern Canada. For Ecol Manage. dominant species, and height;[r]

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A tale of two orogens: Crustal processes in the Proterozoic Trans-Hudson and Grenville Orogens, eastern Canada

A tale of two orogens: Crustal processes in the Proterozoic Trans-Hudson and Grenville Orogens, eastern Canada

1. Introduction Laurentia, the cratonic core of North America, is a collage of Archean terranes accreted during a series of Paleoproterozoic orogenies [Hoffman, 1988]. At its heart lies the Superior craton, Earth’s largest Archean crustal body. In northernmost Canada, smaller Archean fragments, the Rae and Hearne domains, comprise the so-called Churchill plate, which sutured to the Superior during the 1.8 billion-year old Trans Hudson Orogeny (THO: Figure 1). Structural and thermobarometric data indicate that the THO, with its high-grade metamorphism and double-indentor orogenic front, was similar in scale and nature to the present-day Himalayan-Karakoram-Tibetan orogen (HKTO) of Asia [e.g., St-Onge et al., 2006]. In southeast Canada, a >300 Ma period of Andean-style subduction accreted Proterozoic island arcs, continental fragments, and back-arc basins to the Laurentian margin [e.g., Rivers, 1997]. This was followed by the Grenville orogeny, a continent-continent collision that terminated ∼1 Ga ago during the final assembly of the supercontinent of Rodinia, which remained intact until the ∼620 Ma ago opening of the Iapetus Ocean. The closing of the Iape- tus Ocean 462–265 Ma ago then formed the majority of North America’s present-day coastal Appalachian terranes [e.g., Hatcher, 2005; van Staal, 2005]. SE Canada also experienced hot spot tectonism during Mesozoic times, some 190–110 Ma ago, during the passage of the Great Meteor hot spot [e.g., Heaman and Kjarsgaard, 2000]. The hot spot caused a progression of kimberlite and alkaline igneous intrusions that extend from NW James Bay through the White Mountains (NE U.S.), and offshore into the New England seamount chain [e.g., Heaman and Kjarsgaard, 2000]. The geological record of eastern Canada thus spans three quarters of Earth’s history, making it an ideal study locale for Precambrian crustal formation and evolutionary processes, includ- ing the ability of crust of variable ages to resist modification by hot spot tectonism. Of particular interest is the question of whether or not modern-style plate tectonic processes operated on the younger, hotter, more REVIEW ARTICLE
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Downward hydrocarbon migration predicted from numerical modeling of fluid overpressure in the Paleozoic Anticosti Basin, eastern Canada.

Downward hydrocarbon migration predicted from numerical modeling of fluid overpressure in the Paleozoic Anticosti Basin, eastern Canada.

1 Department of Geology, University of Regina, Regina, SK, Canada; 2 Geological Survey of Canada – Quebec Division, Quebec, QC, Canada; 3 INRS – ETE, Quebec, QC, Canada; 4 Department of Geology, Auburn University, Auburn, AL, USA ABSTRACT The Anticosti Basin is a large Paleozoic basin in eastern Canada where potential source and reservoir rocks have been identified but no economic hydrocarbon reservoirs have been found. Potential source rocks of the Upper Ordovician Macasty Formation overlie carbonates of the Middle Ordovician Mingan Formation, which are under- lain by dolostones of the Lower Ordovician Romaine Formation. These carbonates have been subjected to disso- lution and dolomitization and are potential hydrocarbon reservoirs. Numerical simulations of fluid-overpressure development related to sediment compaction and hydrocarbon generation were carried out to investigate whether hydrocarbons generated in the Macasty Formation could migrate downward into the underlying Mingan and Romaine formations. The modeling results indicate that, in the central part of the basin, maximum fluid over- pressures developed above the Macasty Formation due to rapid sedimentation. This overpressured core dissipated gradually with time, but the overpressure pattern (i.e. maximum overpressure above source rock) was maintained during the generation of oil and gas. The downward impelling force associated with fluid-overpressure gradients in the central part of the basin was stronger than the buoyancy force for oil, whereas the buoyancy force for gas and for oil generated in the later stage of the basin is stronger than the overpressure-related force. Based on these results, it is proposed that oil generated from the Macasty Formation in the central part of the basin first moved downward into the Mingan and Romaine formations, and then migrated laterally up-dip toward the basin margin, whereas gas throughout the basin and oil generated in the northern part of the basin generally moved upward. Consequently, gas reservoirs are predicted to occur in the upper part of the basin, whereas oil reservoirs are more likely to be found in the strata below the source rocks.
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GPS inferred velocity and strain rate fields in eastern Canada

GPS inferred velocity and strain rate fields in eastern Canada

whole region to seismic hazard, particularly in the large urban centers of Quebec City, Montreal and Ottawa. The earth’s surface deformation of eastern Canada has been already studied by some re- searchers using GPS data. Among them, Mazzotti et al. (2005) studied the seismic region of the Lower Saint Lawrence River valley (SLRV) using [episodic] observations of 16 GPS stations from the Canadian base network (CBN). George et al. (2011) have quantified the GIA in eastern Canada using observations of 39 CGPS stations. Tiampo et al. (2012) con- strained the pattern and magnitude of the regional crustal deformation using a subset of 43 CGPS stations. Despite other regions like Southern California and Southern Nevada (Langbein, 2008; Tiampo et al., 2004; Wdowinski et al., 1997; Zhang et al., 1997), Fennos- candia, and Central Europe (Bergstrand et al., 2007; Johansson et al., 2002; Kenyeres and Bruyninx, 2009), to the best of our knowledge, there is neither a study about noise behavior of CGPS stations in eastern Canada nor about physical stability of their monuments. This is of special importance because, (a) the intraplate tectonic signal, which is the main cause of deformation, has a very low rate, and (b) many CGPS stations are not principally construct- ed for geodynamic studies, in this region. In other words, no CGPS network has been estab- lished in the area with the primary goal of monitoring intraplate tectonic activities like BIFROST network in Fennoscandia (Lidberg et al., 2010). Therefore, it is very important to identify instable CGPS stations and exclude them from further studies on deformation such as strain analysis [in Chapter 7].
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Seismic Deformations of Taller Reinforced Concrete Shear Walls Located in Eastern Canada

Seismic Deformations of Taller Reinforced Concrete Shear Walls Located in Eastern Canada

seismic demand in Vancouver, BC. The results of this study served as the basis to propose upper and lower bound limits for the effective stiffness of slender shear walls, later integrated in 2004 edition of CSA A.23.3. In Canada, the most recent and major experimental test has been performed by Ghorbanirenani et al (2010) at Polytechnique de Montreal. In this test, the dynamic response of an eight-storey (20.97m) shear wall was studied by performing shake table tests on two reduced scale shear wall specimens (1:2.33) subjected to seismic ground motions representative of the seismic hazard in eastern Canada. The length and thickness of the scaled specimens were respectively 1400 mm and 60mm. The ground motion records were applied to the walls in increments. The ground motions applied to the first specimen varied between 40% to 120% of the design level and to another specimen the ground motion records were incremented in the range between 100% to 200% of the design levels. The results showed a significant impact of the higher modes on the response of the tested shear walls. The response of the shear walls at the design level of earthquake was predominantly elastic and the rotation at the base of the shear wall did not significantly surpass the yield rotation. The test showed signs of inelastic behaviour at levels above the plastic hinge indicating a potential for the formation of the second plastic hinge in upper levels of the shear walls. It was noted that before entering the inelastic domain, the concrete shear resistance of the wall’s cross-section significantly contributed to the overall shear capacity of the wall’s cross- section.
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Confirmation of an incident of diarrhetic shellfish poisoning in Eastern Canada

Confirmation of an incident of diarrhetic shellfish poisoning in Eastern Canada

NRC Publications Archive Archives des publications du CNRC Access and use of this website and the material on it are subject to the Terms and Conditions set forth at Confirmation of an incident of diarrhetic shellfish poisoning in Eastern Canada

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