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Les psychoéducateurs constituent un groupe de plus de 5000 professionnels québécois qui interviennent auprès de personnes aux prises avec des difficultés d’adaptation se manifestant sur le plan comportemental dans leurs différents milieux de vie. Cette expertise s’appuie notamment sur une formation initiale universitaire de 1er et de 2e cycle. Dans une visée rétrospective et prospective, cet article retrace d’abord l’évolution de la formation des psychoéducateurs au cours des soixante dernières années, de ses origines dans les internats pour jeunes en difficulté d’adaptation jusqu’au développement de programmes doctoraux en psychoéducation. L’arrivée de l’ordre professionnel, en 2000, est ensuite présentée comme un jalon important de cette histoire avec l’encadrement des programmes donnant accès au permis d’exercice. Enfin, un regard est posé sur les défis que cette formation devra relever au cours de la prochaine décennie., Psychoeducators constitute a group of more than 5,000 Quebec professionals who work with people having adjustment difficulties which manifest themselves on the behavioral level in their different living environments. Their expertise is based in particular on initial undergraduate and graduate university programs. With a retrospective and prospective approach, this article first traces psychoeducational training over the past sixty years, beginning with its origins in boarding schools for youth in difficulty to the development of doctoral programs in psychoeducation. The creation of the professional Order in 2000 is then presented as an important milestone in this history. With it came the management of programs allowing access to the license to practice the profession. Finally, we look at the challenges that this training will face over the next decade.

On March 11, 2020, COVID-19 was declared a pandemic. Soon after, the first studies began documenting the impacts of the pandemic on children's adaptation in Europe and Asia. In Quebec, Canada, few published studies, to date, report on the adaptation of children living in the context of a pandemic. This studies' objectives are to: (a) describe the level of exposure to the pandemic;(b) present a portrait of the psychosocial adaptation and the mental health of children aged 6 to 17;(c) assess whether the experience of the pandemic influences their adaptation;and (d) evaluate whether children with mental health vulnerabilities are doing worse than those without such vulnerabilities in this particular life context. Statistical analyses reveal that the majority of children do not present difficulties in terms of overall adaptation in the context of the pandemic (65.8%). During confinement, boys present more attentional difficulties and aggressive behaviors than girls. Furthermore, the advancing age of children is positively associated with the presence of withdrawal/depression symptoms. Children who are more knowledgeable about the pandemic have more internalized behaviors. Finally, children who had mental health vulnerabilities prior to the pandemic present more difficulties in overall coping during the pandemic than other youth. Although the results are consistent with other studies and reveal that youth can cope adequately, the fact remains that some children are experiencing difficulties that need to be addressed.

Studies in dendroisotope chemistry suggested that latewood cellulose contains better climatic records than whole-ring cellulose. However, this approach has never been tested on northeastern Canadian spruce trees. This study compares dendroisotopic series of cellulose from late and whole ring, and analyses their statistical relationships with hydro-climatic variables with the aim of selecting the best suited protocol for future hydro-climatic reconstruction in the downstream sector of Churchill River basin of Labrador, Canada. To this end, δ13C and δ18O series from latewood (LW) and whole ring (WR) α-cellulose of black spruce trees (Picea mariana [Mill.] B.S.P.) were produced for the 1940–2010 period. The results show strong correlations between LW and WR isotopic series suggesting that there are no important variation in the isotopic ratios during the growing year and that black spruce trees use photosynthates of the current growing season to form their earlywood. Moreover, LW and WR δ13C and δ18O show similar relationships with both maximum temperature (Tmax) and Churchill River discharge. Correlations are higher when combining δ13C and δ18O for LW and WR. Overall, those correlations support the indirect relationship between tree-ring isotopic series and river discharge, as they are integrators of several climatic variables and derived parameters (Tmax, relative humidity, evapotranspiration, etc.). The LW and WR isotopic series give similar statistical relationships with hydro-climatic variables, and the WR treatment is faster (separation easier compared to LW). Thus, for black spruce the use of combined isotopic series in WR can be favored over LW for hydro-climatic reconstruction in the study region.

Inspired by Nurture Groups, Kangaroo Class (KC) programmes have been gradually expanding in francophone schools throughout the Canadian Province of Quebec. These classes are designed for primary students with social, emotional and behavioural difficulties (SEBDs) and aim to provide children with a nurturing and predictable environment. To date, KC research data show only moderate improvements in attendees’ behaviour. The aim of this study is to differentiate the characteristics of children with a positive behavioural trajectory from those with a negative behavioural trajectory after 2 years of attending KC by examining the sample group in light of their prior educational history, family-specific factors and types of SEBDs. Results indicate that the primary school children whose behaviour improved after 2 years attending KC had entered the programme displaying higher levels of adjustment difficulties and a greater incidence of internalising behaviours in contrast to those whose behaviour deteriorat...

Cet article présente les résultats d’une recherche portant sur l’évaluation d’un programme d’accompagnement collaboratif des enseignants du secondaire afin de faciliter l’inclusion scolaire d’élèves présentant des troubles du comportement, en particulier les perceptions des acteurs concernant les conditions d’efficacité du programme. Des entretiens semi-dirigés ont été réalisés auprès de 42 enseignants ayant été accompagnés, onze accompagnateurs et huit directions d’école. Selon l’analyse qualitative des résultats, le programme peut facilement être mis en place auprès des enseignants qui oeuvrent dans les écoles secondaires afin de faciliter l’intégration des élèves présentant des troubles du comportement. L’élément clé du programme semble être les activités de résolution de problème basées sur une évaluation fonctionnelle des comportements problématiques., This article presents some results of the evaluative research that was conducted on a collaborative school consulting program to facilitate integration of adolescents with behavior disorders in mainstream classes of secondary schools. It examines particularly the stakeholders’ perceptions regarding the conditions of program effectiveness. Semi-structured interviews were conducted with teachers (N = 42), resource persons accompanying individuals or groups (N = 11) and school managers (N = 8). According to qualitative analysis of the interviews, the program should be easily implemented with secondary teachers in order to facilitate the integration of EBD students. The problem solving process seems the core element of the program., Este artículo presenta los resultados de una investigación sobre la evaluación de un programa de acompañamiento colaborativo de maestros de secundaria, con el objetivo de facilitar la inclusión escolar de alumnos con problemas de comportamiento y, en particular, sobre las percepciones de los actores en lo que se refiere a las condiciones de eficacia del programa. Se llevaron a cabo entrevistas semi-dirigidas con 42 maestros que habían sido acompañados, once acompañantes y ocho direcciones de escuela. Según el análisis cualitativo de los resultados, el programa puede desarrollarse fácilmente con maestros que trabajan en escuelas secundarias, de forma que se facilite la integración de los alumnos con problemas de comportamiento. El elemento clave del programa parece ser las actividades de resolución de problemas basadas en una evaluación funcional de los comportamientos problemáticos.

Si plusieurs études rapportent que les problèmes de comportements constituent une source importante de stress, peu d’entre elles portent sur le stress spécifiquement lié à la présence en classe ordinaire d’élèves présentant des troubles du comportement (PTC). Cet article expose les résultats d’une étude exploratoire sur le stress des enseignants du secondaire à l’égard de l’intégration des élèves PTC dans leurs classes. L’échantillon se compose de 231 enseignants d’écoles secondaires du Québec. Les enseignants ont rempli un questionnaire de renseignements sociodémographiques ainsi que la partie B de l’Index of Teaching Stress (ITS) (Greene, Abidin et Kmetz, 1997). L’impact des élèves sur le processus d’enseignement ainsi que la perte de satisfaction par rapport à l’enseignement constituent les sources les plus importantes de stress. Le stress vécu semble être influencé par les cours reçus sur les troubles du comportement au moment de la formation initiale, par l’expérience relative aux troubles du comportement, par le niveau scolaire où enseignent principalement les enseignants et par le milieu où se situe l’école. Aucune différence n’est observée selon le genre des enseignants ni selon leur niveau de scolarité. Plus de 70 % des enseignants jugent qu’une formation additionnelle sur les troubles du comportement serait absolument nécessaire., Although several studies report that behavioral problems are a major source of stress, few relate to the stress specifically linked to the presence of students with behavioral problems (BP) in the regular classroom. This article presents the results of an exploratory study on the stress experienced by secondary school teachers in relation to the integration of BP students in their classes. The sample is composed of 231 teachers from Quebec secondary schools. The teachers filled out a questionnaire on sociodemographic information and part B of the Index of Teaching Stress (ITS) (Greene, Abidin and Kmetz, 1997). The impact of students on the teaching process and the loss of satisfaction in relation to teaching are the biggest sources of stress. The stress experienced seems to be influenced by courses received on behavioural problems during initial training, experience with behavioural problems, the school where the teachers mainly teach and the environment in which the school is located. No difference was observed related to the gender of the teachers or their level of education. Over 70% of teachers believe that additional training on behavioural problems is absolutely necessary., Aunque varios estudios reportan que los problemas de comportamiento constituyen una fuente importante de estrés, muy pocos abordan el estrés específicamente ligado a la presencia de alumnos que presentan problemas de comportamiento (PCT) en clase. Este artículo expone los resultados de un estudio exploratorio sobre el estrés de los maestros de secundaria con respecto a la integración de alumnos PTC en sus clases. El muestreo estuvo compuesto por 231 maestros provenientes de escuelas secundarias de Quebec. Los maestros respondieron a un cuestionario de informaciones socio-demográficas así como a la parte B del l’Index of Teaching Stress (ITS) (Greene, Abidin y Kmetz, 1997). El impacto de los alumnos sobre el proceso de enseñanza así como la pérdida de la satisfacción con respecto a la enseñanza constituyen las fuentes más importantes de estrés. El estrés vivido parece estar influenciado por los cursos recibidos sobre los problemas de comportamiento durante la formación inicial, por la experiencia con los problemas de comportamiento, por el nivel escolar en el que enseña los maestros y por el medio en el cual se sitúa la escuela. No se observo ninguna influencia del género o de nivel de escolaridad de los maestros sobre los resultados. Más de 70% de los maestros juzgan que sería absolutamente necesaria una formación adicional sobre los problemas de comportamiento.

International audience; The Regional Curve Standardization (RCS) is one of the most employed standardization methods to remove biological signals in long tree ring chronologies. The approach assumes that an overall age-related growth trend typify all tree ring series to be included in a standardized tree ring chronology. Although several potential problems of the method have been examined, the influence of varying the sampling height along tree stems has not been evaluated. Considering that age-related growth trends may vary with stem height, biases may arise when combining samples from unknown or variable sampling heights, a frequent situation with subfossil logs. In this study we perform a detailed stem analysis of 15 lakeshore black spruce (Picea mariana Mill. B.S.P.) trees in the taiga of eastern Canada to describe how the age-related growth trend varies with stem height and evaluate associated biases in RCS chronologies built from living and subfossil trees. Results show that the age-related growth trends vary markedly and systematically along stems, potentially generating large methodological biases in RCS chronologies, especially near the recent chronology end. These biases may lead to erroneous reconstructions of recent climatic trends and cause false divergence between tree ring and climate series. We have developed a correction procedure that appears efficient in removing these biases from chronologies built with the lakeshore trees and associated subfossil logs.

Climate reconstructions using stable isotopes (δ18O and δ13C values) in tree rings are based on relationships between present climatic conditions and isotopic series. This widely used approach relies on the assumption that correlations between stable isotopes and climatic conditions are steady over time. In this paper, we evaluate the strength of the correlations between δ18O and δ13C series with several climatic parameters on fourteen black spruce trees coming from three different sites, in northeastern Canada. We applied a 21-year moving window on the r Pearson calculated between stable isotopes and March–May and June–August precipitation, June–August and April–June maximal temperatures. Our results indicate that despite the large distance and differences in stand conditions between the sites, the three sites responded in the same way over time. We show that because the climatic ambiance has changed during the 1980–1990 period due to a positive North Atlantic Oscillation index the δ13C values are not controlled anymore by spring precipitation or summer maximal temperature in the following two decades. As opposed to δ13C series, the relationship between summer maximal temperature and δ18O values was stable over time, and decreased only in the last decade. All these results attest of a “divergence problem” in the last decades which is most pronounced for δ13C series. We conclude that the spruce δ18O series appears to be the most appropriate indicator for reconstructing June–August maximal temperature in the studied area despite the divergence issue, given that the calibration–validation tests and reconstruction can exclude the divergent last decade.

Across Eastern Canada (EC), taiga forests represent an important carbon reservoir, but the extent to which climate variability affects this ecosystem over decades remains uncertain. Here, we analyze an extensive network of black spruce (Picea mariana Mill.) ring width and wood density measurements and provide new evidence that wood biomass production is influenced by large-scale, internal ocean-atmosphere processes. We show that while black spruce wood biomass production is primarily governed by growing season temperatures, the Atlantic ocean conveys heat from the subtropics and influences the decadal persistence in taiga forests productivity. Indeed, we argue that 20–30 years periodicities in Sea Surface Temperatures (SSTs) as part of the the Atlantic Multi-decadal Oscillation (AMO) directly influence heat transfers to adjacent lands. Winter atmospheric conditions associated with the North Atlantic Oscillation (NAO) might also impact EC’s taiga forests, albeit indirectly, through its effect on SSTs and sea ice conditions in surrounding seas. Our work emphasizes that taiga forests would benefit from the combined effects of a warmer atmosphere and stronger ocean-to-land heat transfers, whereas a weakening of these transfers could cancel out, for decades or longer, the positive effects of climate change on Eastern Canada’s largest ecosystem.

1. Although wildfire is the main natural disturbance factor driving changes in the North American boreal forest, understanding how the fire history of the last millennium shaped the present-day landscape diversity is a difficult task due to the lack of palaeoecological reconstructions with high spatial (few hundreds of square metres) and temporal (annual) resolutions. 2. We combined a detailed inventory of the present-day lakeshore forest of two lakes of the Eastern Canadian taiga with the dendrochronological dating of the subfossil logs that accumulated in the lit-toral zones facing these shores. Our objective was to compare the millennial impact of wildfires among stands of various structures and compositions. Past stem densities and fire years were reconstructed from log recruitment rates and dating of charred logs. 3. Multivariate analysis of the present-day lakeshore forest revealed three and two homogeneous shore segments per site (i.e. clusters). Cluster 1 at both sites exhibited denser forest, higher dead wood values and a higher percentage of balsam fir, a fire-sensitive species. 4. In total, 426 and 611 subfossil logs (mostly black spruce) were crossdated over the last ~1400 years. Their dendrochronological analysis confirmed that each lakeshore cluster, identified from the traits of the present-day forest, experienced a specific fire history over the last millennium (i.e. 0–5 fires of variable severity) that locally influenced forest composition, tree density and growth. Each fire triggered a specific forest structure trajectory characterized by a different stem density and rate of recovery. 5. Synthesis. This study provides a long-term perspective that helps explain how the present-day landscape diversity in the Eastern Canadian taiga reflects the site-specific fire history over the last millennium. Fires have caused persistent and cumulative impacts resulting in a progressive opening of the forest cover along with balsam fir exclusion. Present-day landscapes are mosaics of forest stands characterized by different times since fire and different post-fire forest structure trajectories.

In the boreal zone of northeastern Canada, paleoclimatic reconstructions of millennial length are rare and long isotopic climatic records are unavailable. However, millennial tree-ring series could be constructed within the region by cross-dating sub-fossil stems preserved in the littoral part of lakes. Thus, there is a need to evaluate the potential of using stable isotopes of lakeshore black spruce trees (Picea mariana [Mill] B.S.P.) as proxies for climatic reconstruction. We collected four living riparian black spruce trees and we investigated the inter- and intra-tree correlations for four trees, at two different sampling heights (1 and 4 m), for their carbon (δ13C) and oxygen (δ18O) isotopes, as a test for potential long-term reconstruction. A significant correlation (Pearson coefficient) for the isotopic series was found for the two sampling heights (r = 0.92 for δ13C; 0.65 for δ18O), and between the four trees. We further assessed the climatic significance of the mean of the four trees. The strongest correlation of the δ13C series was with the mean of June to August vapor pressure deficit (VPD; r = 0.50), and the δ18O values with the June to August climatic index and June to July maximal temperature (r = − 0.61 and 0.55, respectively). This study suggests that δ18O series of riparian black spruce trees, and eventually their sub-fossil counterparts, can be used as proxies for reconstructing long climatic series in northeastern Canada.

International audience; 1. Large woody debris (LWD) is an important cross-boundary subsidy that enhances the productivity of lake ecosystems and the stability of aquatic food webs. LWD may also be an important carbon sink because LWD pieces are preserved for centuries in the littoral zone of lakes and rivers. However, a long-term analysis of LWD stocks and fluxes in lakes, coupled with the reconstruction of past disturbances at the site level, has never been attempted. 2. Large woody debris was sampled in five lakes of the Quebec taiga. Actual LWD stocks were described and residence time of the LWD pieces was established using tree-ring and radiocarbon dating. LWD losses by decomposition and burial and other factors influencing LWD residence time were investigated using linear regressions. 3. Impacts of wildfires on LWD fluxes during the last 1400 years were reconstructed separately for the five lakes using piecewise regression models. Fire years at each site were identified from the recruitment dates of charred LWD pieces. 4. Large woody debris volume ranged between 0.92 and 1.57 m 3 per 100 m of shoreline, and extrapolating these results to the landscape scale, it was concluded that LWD littoral carbon pools represent a minimal portion of boreal carbon storage. 5. Large woody debris residence time in boreal lakes was confirmed to be very long. Tree-ring dates of 1571 LWD pieces, mainly black spruce (Picea mariana (Mill.) BSP.), spanned the last 1400 years, while LWD specimens of older floating chronologies were preserved from decomposition for up to five millennia. The most influential variables explaining the variation in LWD residence time were the degree of burial and the distance from the shore. 6. Large woody debris recruitment rates averaged 5.8 pieces per century per 100 m of shoreline. Fourteen wildfires were the primary cause for changes in the rates of tree establishment in the ripar-ian forests and of LWD recruitment in the lakes. 7. Synthesis. Interactions between terrestrial and aquatic ecosystems in northern boreal regions are strongly influenced by wildfires whose effects can last for centuries due to the slow large woody debris decay rate. Actual LWD stocks and carbon pools are a legacy of the past fire history.

A collaborative school consulting programme model, using functional assessment and applied behavioural techniques, was offered to secondary school teachers in two modalities: individual consultation and small-group consultation. The objective was to facilitate the integration of students with behavioural difficulties into mainstream secondary school classes. Both consulting programme modalities shared the same postulates. This article presents the stakeholders’ perceptions of the consulting model and its impacts on teachers and students. Presented here are the results of semi-structured interviews conducted with teachers (N = 42), resource persons accompanying individuals or groups (N = 11) and school managers (N = 8) in the programme’s first year of implementation. According to qualitative analysis of the interviews, these two models seem to have had positive impacts on teachers, especially in relation to their perceptions of students with behavioural difficulties and their understanding of behavioural p...

A denser global network of millennial tree ring chronologies is needed to verify whether the warming of the last century is anomalously rapid or of large amplitude in the context of the last millennium. The North American boreal forest in particular has been poorly represented in long climatic reconstructions based on tree rings, because of short tree longevity, as well as frequent and severe wildfires. In this study, we exhaustively sampled tree remains in the littoral zone of two lakes and partially sampled seven additional lakes in the northern boreal forest of eastern Canada to verify if highly replicated millennial tree ring chronologies could be developed. In total, 989 black spruce (Picea mariana (Mill.) BSP.) tree remains were sampled, of which 529 could be crossdated, providing a master chronology spanning the AD 676-1991 time period. Radiocarbon dating of a floating chronology indicates that maximum residence time of tree remains outside of sediments is at least 1500 years. Past fires halted or reduced wood inputs at least once at all but one site and thus influenced the replication of local chronologies. However, fire effects can be minimized using appropriate site selection criteria (old-growth forest on the leeward shore, sharp deepening of the littoral zone, burial of tree remains by fine sediments), such that it would be possible to develop a network of several highly and evenly replicated multi-century local chronologies. These tree ring chronologies would have desirable properties for extracting low-frequency tree growth trends and for reconstructing forest disturbance histories. Copyright # 2013 John Wiley & Sons, Ltd.

This is the last in a series of three articles on Quebec psychoeducation. While the first article introduced the historical and theoretical foundations of psychoeducation as a university discipline in Quebec, the second presented the Psychoeducative Intervention Method. This final article broaches the concept of psycho-social adaptation, with reference to the subject’s adaptive process as a result of having learned skills within the context of a shared psychoeducational experience. This third article also further examines the Utilizing of experiences for therapeutic purposes, a fundamental professional process in the field of psychoeducation. The aim herein is to consolidate the many concepts presented in the previous articles and facilitate the reader’s understanding of how they all come together and are activated by the psychoeducator in a treatment context by means of a highly-specialized therapeutic activity.

Extending climatic series back to the first millennium using isotopic tree-ring chronologies in northern regions represents a challenge because trees seldom reach the adequate age. Fossil trees deposited in boreal lakes could serve such an endeavor provided that dating the tree-ring series is possible and that the isotopic ratios of sub-fossil wood are preserved. From two boreal lakes in north-eastern Canada, we collected segments of Picea mariana (black spruce) stems with different degrees of wood textural preservation and covering the last millennium. Our main objectives are to assess the selection criteria for wood textures suitable for isotopic reconstruction, and verify the reliability of sub-fossil cellulose carbon and oxygen isotopic series for climatic reconstruction in boreal regions. The isotopic differences between cellulose and lignin obtained for 48 ring pairs of a living tree (Δδ13Cc–l = 3.7 ± 0.3‰; Δδ18Oc–l = 13 ± 1) and 46 contemporaneous pairs from a sub-fossil stem (3.5 ± 0.3 and 12.9 ± 0.9‰ in the same order), are systematic and matching. For the selection of all sub-fossil samples, we have visually identified three main classes of wood textures for which the degree of alteration is confirmed by secondary electron microscopy: well preserved, slightly altered and highly altered. Slightly altered stem segments have cellulose proportion showing a relative decrease reaching 35%, but Δδ13Cc–l and Δδ18Oc–l values within the range of living trees. Non-altered sub-fossil stems covering the 14th and 11th centuries show systematic and coherent Δδ13Cc–l (3.5 ± 0.2; 3.8 ± 0.4‰) and Δδ18Oc–l results (13.9 ± 0.7; 13.5 ± 0.5‰). Highly altered wood shows a decrease in both cellulose proportion and δ18Ocellulose values, but apparently preserved δ13C ratios. This research shows that it is possible to visually identify the degree of wood preservation and preselect sub-fossil segments holding reliable isotope-ratios, and to use sub-fossil stems collected from boreal lake floors to reconstruct climate over the last millennia.

We analyzed how the pretreatment method of Scots pine (Pinus sylvestris L.) wood specimens together with X-ray methodology applied for density analyses affect resulting tree-ring data and derived proxy-based climate information. We also evaluated whether these results from two contrasting laboratory circumstances could be homogenized by applying dendroclimatic statistical methods. For this study, we measured a pair of X-ray based microdensitometry datasets using double samples of subfossil and recent wood specimens. Dendrochronological information of earlywood and latewood series was examined to determine for alterations in the resulting data. We found that the level of overall density, its trend over cambial ages and the growth amplitude altered due to the sample pretreatment/density measuring exercise, which means that comparisons of heterogeneous datasets should be, in general, regarded cautiously. Dendrochronological standardization did, however, even out several potentially biasing influences from the differing overall densities and their trends. The two latewood (maximum) density chronologies yielded paleoclimatic reconstructions which both calibrated and verified satisfactorily with the instrumental warm-season (March–September) mean temperatures. The transfer functions were found to further equalize the differences between the two proxy records. We recommend (if no strictly homogenous data are available) reconciling similar data assemblages through transfer functions with multiple independent variables.

The hypothesis tested in this study is that ice-scars recorded by lakeshore tree stands can be used as an integrative proxy indicator of the overall hydrodynamic disturbance regimes affecting northern lakeshores. A 2-km-long shore segment was divided into 21 sections according to shore orientation and slope. An ice-scar chronology and a wave exposure index value were obtained for each shore section. A significant relationship was found between ice-scar chronology and wave exposure index, which indicates that the mechanical action and physical force of ice activity mainly depend on the same environmental factors determining exposure to wave action (i.e. fetch, wind direction and velocity, and shore slope). The spatial and temporal variability of ice-scar chronology features also corresponded to the distribution of geomorphological features associated with ice activity along the shoreline. Analysis of the hydrological signal associated with these ice-scar chronology features indicated that an increase in ice-push frequency observed in the 1930s can be associated to an increase in wave action related to more frequent spring floods maintaining high lake levels during the ice-free period. This study demonstrates that ice-scars have strong potential as proxy indicators of shore exposure and provide a temporal frame to reconstruct the history of lakeshore disturbance regimes at a local scale. Together, ice-scars and wave exposure index provide essential information to interpret the evolution of lakeshore vegetation mosaics in time and space. Copyright © 2012 John Wiley & Sons, Ltd.

Paleoclimate reconstructions are generally validated on recent periods. To obtain a set of instrumental records at the regional scale, a time series of monthly mean temperatures in Northeastern Canada were interpolated for the 19612000 period. Records were provided by 202 meteorological stations. Temperatures derived from a Canadian regional climate model (Climate Model CRCM 4.2.3 from the AMNO domain produced at approximate to 50 km resolution) were added as secondary information to take into account local heterogeneity and temporal dependencies. Geostatistical interpolation of the measured temperature was calculated using CRCM modelled data as a covariable and then compared to an ordinary kriging performed on a time series of mean temperature anomalies. Spherical distances between locations were calculated taking into account the curvature of the Earth with monthly semivariances being modelled using Cauchy variograms. Mean absolute error values (1.5 +/- 1.2 degrees C) were calculated for the whole period using cross-validation procedures. Errors were found to have the same order of magnitude in the central part of the study area where few recorded temperatures were available

Understanding the various spatial and temporal scales to which river ice shapes and alters natural channels is a crucial step towards a better assessment of the full range of physical processes that occur in cold-region watersheds. InEttema andKempema’s paper on ice effects, the primary focus is on processes that typically occur at the intra-annual time scale and at length scales that are generally equal (and often inferior) to that of the channel reach. Of course, such scales are appropriate to investigate, on one hand, river-ice cover formation and break-up processes, and on the other hand, allow for the study of local sediment transport and ablation, the description of ice-covered hydraulics and the analysis ofmorphological and geotechnical changes that relate to ice dynamics. However, to establish whether or not river ice, per se, can be considered a geomorphologically significant agent in the long term remains to be evaluated on much larger time and spatial scales. Investigating ice effects at larger spatial and temporal scales in gravel-bed rivers, by definition, implies that the characteristics of the ice regime (frequency, magnitude, duration, moment of occurrence of events) and their variations through time and space need to be taken into account. For example, all of the following questions regarding ice jam dynamics need to be addressed with at least a partial understanding of ice regime characteristics

The Great Whale River region on the eastern shore of Hudson Bay, Canada, encompasses the villages of Whapmagoostui (Cree First Nation) and Kuujjuarapik (Inuit) and surrounding areas. The principal field station of Centre d'etudes nordiques (CEN: Centre for Northern Studies) has operated at Whapmagoostui-Kuujjuarapik (W-K; 5 5° 1 5' n, 77° 45' w) since the 1970s, with diverse research projects on past and present environments. The climate at W-K is strongly influenced by the proximity of Hudson Bay, and the recent pronounced loss of sea ice in this sector of northern Canada has been accompanied by large increases in air temperature. Discontinuous or scattered permafrost occurs throughout the region and is degrading rapidly. The W-K region continues to experience particularly rapid isostatic uplift in response to the retreat of the Laurentide Ice Sheet. Parabolic dunes occur along the coast and are strongly influenced by the plant cover. Paleoecological studies have documented the Holocene evolution of landscapes, including lakes, wetlands, and forests. The vegetation type is coastal forest tundra, with some 400 recorded species. Studies on certain insect groups provide a baseline for assessing future ecological change. The first signs of human occupation in the W-K region have been dated at 3800 BP . The arrival of the Hudson's Bay Company in the 18 th century marked the onset of continuous occupation. Rapid social, economic, and environmental change initiated in the mid-20 th century continues to this day.

Tree-ring formation of eastern white-cedar (Thuja occidentalis L.) at a boreal lake in northwestern Quebec, Canada, was monitored using manual band dendrometers to (i) retrace cambial activity phases, (ii) evaluate the effects of flooding on radial growth, and (iii) analyze the relationships with meteorological factors. The daily circumferential activity of four trees at each of two sites, a riparian and an upland site, was recorded during the growing season of 1996, a year with an extreme spring flood. First cambium cell divisions occurred near June 9, followed by a distinct and sustained upward trend in the stem basal area until mid-July that reflected the earlywood formation. The strongly synchronous circumferential activity at both sites suggests no adverse flooding effect on growth of the riparian trees, which is explained by the rapid retreat of the water just before growth initiation in early June. The following month until mid-August was characterized by strong short-term fluctuations cau...

In the context of intense emissions causing atmospheric pollution, tree growth reductions could be related to soil chemistry modifications or direct foliar injuries. To verify these hypotheses, mineral soils were sampled in an area (Murdochville, Canada) where previous studies had demonstrated that tree growth was impacted by smelter emissions and that forest floor lead concentrations could be used as a proxy for atmospheric pollutant depositions. Samples were analysed for Al, Pb (concentrations and isotope ratios), basic cations (Ca, K, P, and Mg) and Zr. Mass balance calculations were performed on soil profiles to assess vertical migration of elements. Pb concentrations in litter diminished gradually with distance from the smelter. The Pb isotope ratios in these organic soil layers were close to those measured in the Murdochville ores. These patterns were not encountered in mineral soil layers. Pb isotope ratios in these layers were close to those measured in uncontaminated geological materials, and Pb concentrations and basic cation depletions were not related to the proximity of the smelter. Growth reduction was closely associated with litter Pb concentrations, which were used as a proxy for atmospheric deposition, but was not correlated with any elemental concentration or cation depletion measured in mineral soil layers. Our overall results suggest that trees responded mainly to direct atmospheric emissions, which caused foliar damage, rather than to soil chemistry modifications.

We used a 54-year (1950-2003) ice scar chronology constructed from damaged trees to investigate relationships between large scale hydro-climatic conditions and mechanical breakup magnitude in the Necopastic River watershed (James Bay, northern Quebec). Our objectives were: (1) to identify hydrologic and climatic variables that explain variations in mechanical breakup magnitude at the watershed scale, (2) to organize these variables in terms of importance and (3) to construct a predictive model for ice-floods in the Necopastic watershed. We used parametric correlation analysis to measure the degree of linear association between variables and classification trees (CT) coupled with a cross-validation approach to construct the predictive model and to organize variables according to their importance. In the Necopastic watershed, the type and magnitude of breakups are determined by an interaction between forces that maintain the ice cover in place and forces that tend to dislodge it. In contrast with lakes, early and rapidly rising floods, rather than abnormally high flood discharge, create conditions that favour intense mechanical breakups. Moreover, cold and snowy spring conditions during high positive Arctic Oscillation (AO) indices delay the thermal degradation of the ice cover and preserve its mechanical properties over longer time periods.

article i nfo River ice jams are generally perceived as significant erosive events and are well known to impact both channel morphology and geometry. However, the extent of these impacts and the frequency of events required to maintain erosion-induced morphologies remain unexplored in most cold region watersheds. In this study, we investigated downstream variations in channel width, cross-sectional area, depth, and geomorphological characteristics in a small high-boreal basin. We coupled these observations to dendrochronological data on ice jam frequency. Our results show that channels affected by ice erosion appear enlarged and present an important retreat of the upper bank. Such enlarged channels present a typical two-level, ice-scoured morphology when ice jams recur more often than once every 5 years. By contrast, channels appear unaffected when ice jams are less frequent. These results suggest that ice jams maintain ice-scoured and enlarged morphologies once a minimal frequency-of-occurrence threshold is exceeded. We therefore conclude that ice jam frequencies should be taken into account in order to better define the role of ice as a geomorphological agent in cold environments.

Current-year, 1-year-old, and 2-year-old needles were collected separately on 37 black spruce (Picea mariana Mill. B.S.P.) trees located on a heavy metal contamination gradient around the smelter in Murdochville, Quebec (Canada). Needles were analyzed separately by year for the concentrations of Pb and Cu, a nonessential and an essential metal, respectively. Lead concentrations increased significantly with needle age in the highly contaminated area near the smelter. In contrast, Cu concentrations decreased with needle age in the same area. Our results support the hypothesis that the passive sequestration of toxic metals in the senescing foliage is a detoxification process contrasting with the active translocation of essential metals in the nonsenescent part of the foliage.

Ice-scars were investigated to reconstruct the ice-flood history of Corvette Lake in Northern Québec in an attempt to determine the hydrological threshold of shore ice and identify the accompanying climatic conditions. The ice-scar record started around 1850 and showed a rapid increase in frequency at the start of the 1930s, while trees damaged by the ice were already mature and established over several decades. The study supports the hypothesis that this shift could correspond to an increase in flood discharge. Hydrological analysis of every event that occurred since 1961, the year during which instrumental recording began, indicated that scar frequency and scar maximum height were strongly correlated with average recession discharge, average flood discharge, peak discharge and flood onset. Ice-scars provided a discontinuous record of discrete events triggered by hydrologic extremes that were used to document the instrumental record using logistic regression. Results from multiple regressions suggested that ice-scars correspond to years with highs in total precipitation from January to March and from May to June, in the sum of degree-days of frost in April, and in the sum of degree-days of heat from October to April. Although imperfect for reconstructing past events, this study exemplifies the potential use of ice-scars for extending the historical record of ice-floods with hydroclimatic significance.

Growth responses of riparian eastern white cedar trees ( Thuja occidentalis L.) to the double damming of a large lake in the southeastern Canadian boreal forest was analyzed to determine whether the shoreline tree limit is the result of physiological flood stress or mechanical disturbances. The first damming, in 1915, caused a rise in water level of ca. 1.2 m and resulted in the death of the trees that formed the ancient shoreline forest, as well as the wounding and tilting of the surviving trees (by wave action and ice push) that constitute the present forest margin. The second damming, in 1922, did not further affect the water level, but did retard the occurrence of spring high water levels, as well as reduce their magnitude. However, this did not injure or affect the mortality of riparian eastern white cedars. Radial growth was not affected by flooding stress, probably because inundation occurred prior to the start of the growing season (1915–1921) or was of too short duration to adversely affect tree metabolism (after 1921). It follows that (i) the shoreline limit of eastern white cedar is a mechanical rather than a physiological limit, and (ii) disturbance-related growth responses (e.g., ice scars, partial cambium dieback, and compression wood) are better parameters than ring width for the reconstruction of long-term water level increases of natural, unregulated lakes.

Dans le but de retracer les parametres du regime hydrologique dans le temps, nous avons reconstitue les principales variables hydro climatiques servant dans les modeles de prevision hydrologique. Le travail porte sur un territoire de 3 200 km 2 couvrant le complexe hydroelectrique de La Grande Riviere. Les arbres occupant des sites sensibles aux principales variables hydro climatiques (milieux secs, mesiques ou hydriques) et aux conditions thermiques (selon leur exposition) offrent la possibilite de reconstituer les variations interannuelles du climat. Une periode de calibration est necessaire avec les donnees instrumentales. Le modele exprimant la relation cernes - climat est aussi verifie sur la base de donnees independantes. Plus de 100 dendroseries de plus de 180 ans, une dizaine de plus de 250 ans et une de pres de 1000 ans ont ete construites. Ces dendroseries sont etalees sur un territoire couvrant 320 000 km 2 , soit 800 km de longitude par 400 km de latitude. Les temperatures estivales, les precipitations nivales et les apports en eau, selon les saisons, ont ete reconstituees sur 200 ans au moyen des indicateurs dendrochronologiques que sont la largeur des cernes, la densite (9 variables derivees) et les ratios des isotopes stables de l'Oxygene et du Carbone.

Les phases d'activité littorale dans un site de la rive sud du Saint-Laurent ont été étudiées à l'aide de la dendrochronologie. L'analyse des dates de formation de bois de réaction chez les arbres déstabilisés sous l'effet de décrochements mineurs survenus au pied des versants forestiers a permis d'établir le cadre spatio-temporel de la reprise d'érosion associée aux débordements récents du fleuve. Deux périodes de hauts niveaux de l'eau semblent avoir particulièrement marqué révolution des rives, les décennies 1920 et 1970, au cours desquelles une régression des franges forestières se serait produite en raison d'une érosion accrue. Lors des périodes intercalaires de bas niveaux, soit autour de la décennie 1910 et de 1930 à 1950, la forêt se serait rapprochée du fleuve en colonisant les sédiments de plage. Depuis 1970, l'amplitude et la fréquence des débordements ont considérablement augmenté. Ce changement de régime du fleuve implique de fréquents débordements d'hiver associés aux variations des conditions pluvio-thermiques, aux ouvrages de rétention des grands lacs et au contrôle de débit par des barrages. Les débordements hivernaux contribuent à favoriser une forte activité glacielle sur le littoral., Phases of shoreline changes on a site located along the south shore of the St. Lawrence River were studied by means of dendrochronology. Analysis of the dates of formation of reaction wood among destabilized trees at the base of a wooded backshore yielded a time-space framework for erosion phases related to extreme flood events. Two high-water periods were depicted: the 1920s and 1970s, while a regression of forest margins occurred in response to increasing geomorphic activity on the upper shore. Relatively low-level stages in the 1910s, and during the 1930-1950 period, favoured forest colonization of the upper beach sediments. Since the 1970s, there has been a noticeable rise in the frequency and magnitude of floods. Winter floods are now frequent due to changes in pluvio-thermal regimes and man-made flood controls works in the Great Lakes and on affluents. As a result of increasing cold-season flood activity, shore susceptibility to drift ice action intensifies., Analyse und Datierung des Reaktionsholzes, was die Holzpflanzen unter EinfluB geringfugiger Sub-stratablôsungen am HangfuR gebildet haben, sowie des Wachstumsrùckgangs infolfge des Rùckversatzes eines Kleinabhanges in den Sedimenten eines frùheren Strandes erleuben, den zeitlichen und ràumlichen Rahmen der gegenwàrtigen Erosion durch den St.-Lorenz zu ermitteln. Drei Hochwasser-perioden scheinen die Uferentwicklung entscheidend beeinfluRt zuhaben : Demnach zeige sich ein Rùckschritt der Waldvegetation infolge starker geomorphologischner Aktivitàt fur die achtziger Jahre des vorigen Jahrhunderts sowie fur die zwanziger und die siebziger Jahre diesen Jahrhunderts. Wàhrend der Zwischenphasen mit niedrigeren Wasserstânden um die Jahre, 1930 und 1950 und gegen Ende der sechziger Jahre scheint die Waldvegetation mehr in Uferrichtung vor-gedrungen zu sein und die Sedimente der Reliktstrànde besiedelt zu haben. Seit 1970 und besonders im Laufe der siebziger Jahre nahmen Amplitude und Frequenz der Wasserùberlàufe betràchtlich zu. Die hohen Wasserstànde im Winter sind jetzt hàufiger aufgrund von Niederschlags- und Temperatur-verànderungen sowie wegen anthropogener Eingriffe und Hochwasser-Kontrollmethoden. Dièse winterlichen Erscheinungen bedingen einen versta'rkten EinfluR des FluReises auf die Uferdynamik.

One of the most important ways by which northern forests will respond to anticipated climate change is through variations in seed maturation. In this study, the relationship between growing degree-days (DD) >5°C and seed maturity was evaluated at three spatial scales. At the continental scale, the development of female gametophytes and embryos was evaluated as a function of the heat sums obtained from 11 sites distributed across the Canadian range of black spruce. At the regional scale, cone size and the percentage of germinated seeds formed in 1998, 1999, and 2000 were analyzed from seven sites situated along a latitudinal gradient in northern Quebec. At the local scale, cones were collected along perilacustral and insular transects according to their exposure to large water bodies, and from 10 islands located within a 2835-km2 hydroelectric reservoir. Our results confirm the 800–940 DD thermal sum threshold necessary for the complete maturation of black spruce embryos at several populations distributed across the total range of the species. Along the regional south-to-north climatic gradient, the percentage of germination can be predicted by a sigmoid function of a thermal sum (y = 2.8 + 25.1/[1 + e(x−896.6)/84.6]; r2 = 0.85, P < 0.0001) that attains a plateau at around 800–940 DD. Once the 800–940 DD threshold is attained, variations in the percentage of seed germination are mainly associated with inter-tree differences and local site factors (thickness of organic matter, tree density, tree height, tree age, and fetch). In the springtime, cold enclaves are created by the presence of the hydroelectric reservoir. The seed germination percentages in these enclaves varied from 0.6% ± 0.7% to 14.9% ± 19.1% (mean ± SD) according to the site (compared to 22.7% ± 15.1% for a site not exposed to the reservoir), which was equivalent to the germination percentages for sites at latitudes 1–3° farther north. These data suggest that the potential for black spruce regeneration increases strongly beyond the 800 DD isotherm, which evokes the possibility that subarctic open forests may become more dense under the current anticipated climate changes.

Climatic reconstructions for north-eastern Canada are scarce such that this area is under-represented in global temperature reconstructions. To fill this lack of knowledge and identify the most important processes influencing climate variability, this study presents the first summer temperature reconstruction for eastern Canada based on a millennial oxygen isotopic series (δ18O) from tree rings. For this purpose, we selected 230 well-preserved subfossil stems from the bottom of a boreal lake and five living trees on the lakeshore. The sampling method permitted an annually resolved δ18O series with a replication of five trees per year. The June to August maximal temperature of the last millennium has been reconstructed using the statistical relation between Climatic Research Unit (CRU TS3.1) and δ18O data. The resulting millennial series is marked by the well-defined Medieval Warm Anomaly (AD 1000–1250), the Little Ice Age (AD 1450–1880) and the modern period (AD 1950–2010), and an overall average cooling trend of −0.6 °C/millennium. These climatic periods and climatic low frequency trends are in agreement with the only reconstruction available for northeastern Canada and others from nearby regions (Arctic, Baffin Bay) as well as some remote regions like the Canadian Rockies or Fennoscandia. Our temperature reconstruction clearly indicates that the Medieval Warm Anomaly has been warmer than the modern period, which is relatively cold in the context of the last 1000 years. However, the temperature increase during the last three decades is one of the fastest warming observed over the last millennium (+1.9 °C between 1970 and 2000). An additional key finding of this research is that the coldest episodes mainly coincide with low solar activities and the extremely cold period of the early 19th century has occurred when a solar minimum was in phase with successive intense volcanic eruptions. Our study provides a new perspective unraveling key mechanisms that controlled the past climate shifts in northeastern Canada.

This study aims at determining the dendrochronological indicators of a changing snow accumulation regime on an island of a recently created reservoir in northern Quebec. Reservoir Robert-Bourassa (LG-2) is a vast lake (2,835 km2) covered by ice from mid-December to mid-May. Snow drifts across the frozen lake until it is trapped by obstacles on islands and at reservoir margins. Pre-established trees on the islands are negatively affected by the local augmentation of snow accumulation. Changes in tree growth forms of a severely exposed forested island indicate that damage occurred soon after reservoir filling. At the island edges, the decay of trees increases the wind exposure of border trees, causing massive foliage loss, thus reducing tree growth. Beyond the edge, in the island interior, drifted snow accumulates due to the wind breaking effect of the shoreline trees. Since reservoir filling, incidents of stem breakage, shoot bending and tilting, and branch tearing have increased due to snow packi...

Cell formation in growth rings of balsam fir (Abies balsamea (L.) Mill) in the boreal forest was studied to describe the timing of ring formation and the development patterns of earlywood and latewood. Wood micro-cores were extracted during the growing season from 1998 to 2000. The micro-cores were stained with cresyl fast violet to facilitate counting the number of cells in the radial enlargement, wall thickening phases, and mature cell phases. The periods required to complete these various phases were then estimated. Variations in the beginning of the growing season (May 7 – June 7), the earlywood–latewood transition (July 2 – July 19), and the end of the growing season ( August 20 – September 20) were observed. Short cell enlargement durations of less than a week for earlywood and 5–10 days for latewood were observed. Time required for cell wall thickening was about 20 days for earlywood and longer than 10–15 days for latewood. A certain flexibility was observed in the ring formation patterns and in the cell development rate, providing an advantage in the boreal forest where optimal growth conditions change from year to year. These findings on the spatial and temporal patterns of ring development may be useful for understanding tree relationships with climate or other environmental parameters.

Dendrochronological analysis of the climatic effects of a vast hydroelectric reservoir in northern Quebec (Canada). The climatic effect of reservoir Robert-Bourassa (2 835 km2) on surrounding forest was studied by mean of dendrochronology. A cooling effect was recorded, which postpones the onset of seasonal tree growth, reduces early season tree productivity and causes a variety of stress events. Shoreline trees show frequent light rings (rings with low density), rare frost rings (the last spring frost events occur prior the onset of tree growth) and numerous traumatic rings as a result of foliage stress. The average seasonal wood production do not show significant change associated with the reservoir effect, but dense earlywood and large proportion of latewood are common. Since reservoir filling in winter 1978-1979, its climatic effects appeared to be limited to islands and the near periphery of the water body., Résumé : L'influence climatique du réservoir Robert-Bourassa (2 835 km2) sur l'environnement forestier a été étudiée au moyen de la dendrochronologie. Le réservoir a pour effet de refroidir le climat local. Ceci engendre un retard dans la levée de dormance, une faible productivité des arbres en début de saison et de nombreux stress physiologiques. Les arbres riverains périlacustres et insulaires montrent une haute fréquence de cernes pâles (cernes ayant une faible densité), très peu de cernes de gel (la croissance débute après les derniers gels printaniers) et une abondance de cernes trau- matiques témoins de stress foliaire. La productivité des arbres sur le territoire ne semble pas significativement affectée par la création des réservoirs. Toutefois, les cernes des arbres situés près des grandes nappes d'eau comportent généralement un bois initial dense et une forte proportion de bois final. Les effets du réservoir sur la forêt, depuis sa création en hiver 1978-1979, semblent donc limités aux îles et à la périphérie immédiate du bassin., Begin Yves. Analyse dendrochronologique des effets climatiques d'un vaste réservoir hydroélectrique au Québec nordique (Canada) / Dendrochronological analysis of the climatic effects of a vast hydroelectric reservoir in northern Quebec (Canada). In: Revue de géographie alpine, tome 91, n°1, 2003. Hydrosystèmes lacustres et changements environnementaux / Lake hydrosystems and environmental changes sous la direction de Laurent Astrade et Rachid Nedjaï. pp. 67-80.

Tracheid cell number, cell diameter, and cell-wall thickness of black spruce (Picea mariana (Mill.) BSP) tree rings at the tree line (northern Quebec, Canada) were measured using image analysis. The densitometric data from the same samples were used to evaluate the features of image analysis. The anatomical data were correlated with summer temperature variables, including: means of pentad temperature (five consecutive days), growing season (May- September), sum of degree-days, and number of frost-free days. Our results suggest that the main cause of the pale appearance of light rings is thinner latewood cell-wall thickness. Some latewood variables are strongly correlated with corresponding indices for ring cell number and diameter, and ring cell wall thickness. Anatomical ring cell number and the sum of cell diameters (ring widths) were correlated to tree-ring width parameters derived from densitometry. Ring cell number and annual sum of cell diameter also showed very similar trends with both chronologies, suggesting that ring-width length may depend on the number of cells within a ring. Ratio diagram of double cell-wall thickness to cell radial diameter showed similar trend to wood density profile. There is a statistically significant correlation between maximum density and the highest annual ratio between cell wall thickness and lumen diameter. Cell-wall thickness was significantly correlated to maximum density, and both were significantly correlated with summer temperature variables. Our results suggest that wood anatomy may be used as a substitute to densitometry for climate reconstruction as densitometric data require expensive equipments. Also the anatomical method allows the recording of intra-annual information for dendroecological purposes.

The production of plant macroremains was studied in a conifer forest twomonths after it burned in 1996 in northern Quebec. The proportions ofvarious types of charred and uncharred pieces (needles, cones andwood) produced by black spruce (Piceamariana) and jack pine (Pinusbanksiana) were determined by sampling around individual trees.Both species produced equivalent masses of charred material, but pieces of woodcharcoal from jack pine are generally larger that those of black spruce. Theproportion of charred versus uncharred needles is the bestindicator of the species dominance in the forest. Although the fall of uncharredneedles is delayed from the time of a fire, they contribute to more than half ofall remains produced. Jack pine cones remain on the tree for a long time after afire, while charred cones of black spruce are dehiscent (cones come off thebranches easily). Trees are poor wood charcoal producers compared toundergrowth shrubs. As a result, the macroremains assemblage associated with afire event is made up of large amount of uncharred material from trees and alarge proportion of charred pieces produced by undergrowth vegetation. Modernassemblages of plant macroremains indicate that in order to reconstruct pastvegetation associated with fire disturbance, it is important to distinguishbetween the various types of remains, because wood charcoal is mainly producedby material that is already dead.

AIM To test the safety and effectiveness of hypertonic saline solution (HSS + F) as a strategy for weight loss and prevention of further deterioration of renal function. METHODS Patients admitted with acute decompensated heart failure (ADHF) who received HSS + F were included in the study. After a period of a standard ADHF treatment, our patients received an intravenous infusion of furosemide (250 mg) combined with HSS (150 mL of 3% NaCl) twice a day for a mean duration of 2.3 d. Our primary outcomes were weight loss and a change in serum creatinine per day of treatment. The parameters of the period prior to treatment with HSS + F were compared with those of the period with HSS + F. RESULTS A total of 47 patients were included. The mean creatinine on admission was 155 μmol/L ± 65 μmol/L, the ejection fraction was 40% ± 17%. The experimental treatment (HSS + F) resulted in greater weight loss per day of treatment than the standard treatment (-1.4 kg/d ± 1.4 kg/d vs -0.4 kg/d ± 1.0 kg/d, P = 0.0168). Importantly, the change in creatinine was not significantly different. CONCLUSION This study supports the effectiveness of HSS + F on weight loss in patients with ADHF. The safety profile, particularly with regard to renal function, leads us to believe that HSS + F may be a valuable option for those patients presenting with ADHF who do not respond to conventional treatment with intravenous furosemide alone.

International audience; The objective of this study was to reconstruct 200 years of spring (Q(spr)), summer (Q(sum)) and annual (Q(ann)) water supply variability at the Caniapiscau Reservoir in a remote area of northern Quebec. This region which is a key hydropower region of North America lacks long-term hydrological series, and tree-ring proxies are seen here as the best alternative for the extension of the climatic series beyond instrumental records. Thus, ring widths, ring densities and stable isotope ratios (delta C-13 and delta O-18) were used to perform paleohydrological reconstructions. The following reconstruction techniques were evaluated for each variable reconstructed: partial least square (PLS) regression applied to all of the tree-ring series, PLS regression applied to selected tree-ring series, and the best analogue method (BAM) applied to selected tree-ring series. These three reconstructions were then combined in a composite reconstruction. Reconstruction verification shows that the annual and summer water supply reconstruction quality is good. Conversely, the verification tests disqualified our spring water supply reconstruction. The reconstructed long-term water supply variations over the last two centuries are dominated by decadal to sub-decadal fluctuations, including distinct long hydrological periods during which water supplies change in intensity and variability. Annual water supplies (Q(ann)) inversely correlate with both winter and summer indices. Annual water supplies (Q(ann)) inversely correlate with Arctic oscillation (AO) and North Atlantic Oscillation (NAO) winter and summer indices. Also, AO indices also influence Q(ann) to a greater degree than NAO indices. Finally, summer water supplies inversely correlate only with summer indices. (C) 2014 Elsevier B.V. All rights reserved.

International audience; We present a method of multiproxy reconstruction of the climate of Europe during the last millennium. The proxies used comprise long tree-ring width series, grape harvest dates, Greenland ice oxygen isotope series and temperature indices based on historical documents. The proxies are calibrated using gridded April to September mean temperatures for western Europe, i.e., between 10°W and 20°E and between 35°N and 55°N. They are calibrated also using the long instrumental summer temperature series of the Marseilles observatory of Longchamp, which begins in the mid-eighteenth century. The method is a combination of an analogue technique, which is able to deal with missing data, an artificial neural network technique for an optimal non-linear calibration and a bootstrap technique for calculating error bars on the reconstruction. About 70% of the temperature variance is reconstructed. The amplitude of the past temperature variations is particularly well reconstructed, which is important when considering whether the recent temperature trend is or is not within the natural variability. It appears that the temperature of the last decade of the twentieth century was reached only 14 times during the last millennium. The reconstruction is discussed with respect to other multiproxy and borehole temperature reconstructions. We conclude that a reconstruction such ours, with a specific regional focus (as opposed to the larger Northern Hemisphere) is more reliable and is in better agreement with borehole results, even allowing for the fact that only a part of the long-term variance is reconstructed. 'Little Ice Age' (c. AD 1560 - 1930) summers were 0.2±0.5°C cooler than the 1961 - 1990 period. Borehole temperatures indicate a cooling of 0.4°C which falls in the 95% confidence interval of our reconstructions.

Living, dead and subfossil trees of black spiruce (Picea mariina [Mill.] BSP were used to build a 1300-year chronology based on ring width and wood density. All density sariables (maximcum, minimum, earlywood and latewood densities) among the three types of trees were simlilar, whereas ring width was significantly Higher in liviing trees thani in deacd and subfossil trees. Correlition of the indexed series from liviing and dead trees and from dead and subfossil trees that grew during the samiie periods were higher for Maximum density (r = 0.70, 0.63) and mean latewood density (r = 0.65, 0.66) than for Minimum density (r = 0.16. 0.35 and ring with (r=0.15, 0.49). respctively. Maximum density and mean latewood density were significantly correlated with all temperature variables: mean annual (January-December) and growing season (May September) temperatures, sum of degree days and frost-free days. Accordingly, Maximum and latewood density in tree-rings of spruce stem at tree-linec can be conisidered as a function Of summner-temnperature distributions and different types of trees can be combined for the reconstruction of long-term climatic trends due to theii synchronous variations.

The dates of extreme water levels of two large lakes in northern Quebec have been recorded over the last century by ice scars on shoreline trees and sequences of reaction wood in shore trees tilted by wave erosion. Ice-scar chronologies indicate high water levels in spring, whereas tree-tilting by waves is caused by summer high waters. A major increase in both the amplitude and frequency of ice floods occurred in the 1930s. No such change was indicated by the tree-tilting chronologies, but wave erosion occurred in exceptionally rainy years. According to the modern record, spring lake-level rise is due to increased snowfalls since the 1930s. However, the absence of erosional marks in a large number of years since 1930 suggests a high frequency of low-water-level years resulting from dry conditions. Intercalary years with very large numbers of marked trees (e.g., 1935) indicate that the interannual range of summer lake levels has increased since the 1930s. Increased lake-flood frequency is postulated to be related to a slower expansion of arctic anticyclones, favoring the passage of cyclonic air masses over the area and resulting in abundant snowfall in early winter. Conditions in summer are due to the rate of weakening of the anticyclones controlling the position of the arctic front in summer. This position influences the path of the cyclonic air masses, which control summer precipitation and consequently, summer lake levels in the area.

This paper presents the dendrochronological markers used to date the erosive activity of ice and waves on the shores of two large lakes in Northern Quebec. Damages to trees are dated by detailed analysis of anomalous tree rings in response to the shore geomorphic activity associated with extreme water levels over the last 2 centuries. Spring floods are dated using ice scars on trees and shrubs. Lake ice breakup occurs 4–6 weeks after snowmelt. Marks on trees made by ice displaced by the wind indicate the flood levels. Once ice breakup is complete, waves erode forest edges. Tree tilting, dated by counting rings in compression wood, mark high lake levels at the beginning of summer. At submerged sites that are not subject to waves and ice, stress related to prolonged submersion results in narrow tree rings. Trees located in the immersion zone show narrow rings compared to wider rings in unsubmerged trees. However, tree response is not immediate; they can primarily respond to sequences of several consecutive ...

Light rings in black spruce (Picea mariana [Mill.] BSP.) at the arctic treeline are characterized by pale-colored latewood made of a single or very few latewoodcell layers with thin-walled cells. Their widespread occurrence and their high frequency greatly facilitate the cross-dating procedure in dendrochronological studies. In this study, black spruce tree-ring density and wood structure were analyzed for light ring characteristics along with the mechanism of their formation according to ambient temperature. Light rings were quantitatively categorized into three classes based on the maximum tree-ring density using a normalized standard distribution. A light-ring chronology was established according to this classification. The results indicate that the grade of light ring was positively related to the frequency of light rings obtained from visual light-ring chronologies. The following anatomic variables were examined: number of cell layers of latewood, number of cells of the whole ring, percentage of latewood in the total ring width, and mean latewood cell-wall thickness. Among these anatomic variables, the mean latewood cell-wall thickness represents the best quantitative descriptor of a typical light ring as recognized by optical examination. The main causal factors of light rings are insufficient length of the growing season or cool summers.

The objective of this study was to evaluate the most important environmental factors determining the distribution of tree species within the riparian zone of Lake Duparquet, located in the southern boreal region of Quebec, Canada. Occurrence and relative basal area of 10 species were recorded within an altitudinal range of 200 cm above mean water level along 95 transects. Stepwise logistic regression and canonical correspondence analyses were performed on the overall data set as well as separately for the five geomorphological shore types distinguished (depositional flats, floodplains, beaches, terraces, and rock outcrops). The elevation gradient, representing seasonal floodings, is the main factor determining the distribution of the species. The differences between the geomorphological shore types with respect to composition and arrangement of the arborescent vegetation along the elevation gradient are at least partially explained by surficial substratum, topography, aspect, and fire. Exposure to wave activity seems to be of minor importance only. However, since they are the driving force of erosion and sedimentation, the waves are to a great part responsible for the morphological differentiation of the shoreline. The distribution of the tree species along a characteristic physiographic cross-section is illustrated for each geomorphological shore type.

Ice scars on lakeshore trees were surveyed on the islands of two large lakes in northern Québec: Clearwater Lake (1270 km2) and Bienville Lake (900 km2), respectively at the southern edge of the Subarctic and at the northern limit of the Boreal zones. Correspondence of ice-scar chronologies with hydrological and climatological instrumental registers indicated that shore ice pushes are due to lake floods. In the AD 1930s, a shift in the flood regimes occurred. In the high Boreal, ice-push activity was much more frequent prior to 1930 than in the Subarctic. Major regional ice pushes occurred in AD 1854, 1903, 1914, 1936, 1947, 1954,1959-60, 1970 and 1979. Prior to 1930, local major events were concentrated south of the Subarctic zone, but the situation inverted after 1930. A northward shift in the average position of the Arctic front is postulated as having been the driving force of local hydrologic regimes that allowed ice disturbances to occur, especially A in controlling the amount of snowfall. Ice scars provide proxy indicators of an increase in the frequency of snowy winters between the mid-1930s and 1980. The recent period of low levels represents an anomalous incursion in the century trend, but equivalent long episodes of low seasonal lake levels occurred prior to 1930.