Search

Despite bryophytes being well adapted to various ecological settings, they are rarely considered in reclamation projects. In this study, propagation regenerative capabilities of bryophytes on different substrates (sand, amphibolite, and pegmatite) and conditions (with or without peat amendment, shade and shredding) were tested in greenhouse and field experiments. In the greenhouse trial, after 6 months of reintroduction, Racomitrium species (Racomitrium canescens (Hedw.) Brid. and Racomitrium elongatum Frisvoll.) had higher regeneration compared to Polytrichum species (Polytrichum juniperinum Hedw. mixed with Polytrichum piliferum Hedw.; a combination of shade (65% shading) and peat amendment (0.5 cm depth) was found to be particularly effective, resulting in up to 100% of Racomitrium species regeneration; shredding the stems of Polytrichum species into small pieces of 0.5-1.0 cm inhibited its regeneration. In the field trial, peat amendment had no effect on moss regeneration. The addition of fluvioglacial sand or till on waste rocks promoted bryophytes regeneration in both the greenhouse and field. These results provide science-based practical knowledge to support the inclusion of native bryophytes in waste rock restoration plans for mines located in northern boreal forests. Key words: bryophyte, ecological restoration, heavy metal, lithium mine, native species, Introduction Mine tailings are often characterized by the absence of organic matter and extreme pH conditions, coupled with hostile physical (low moisture and high surface temperatures during summer months) and [...]

Over the past decades, a variety of ice control structures (ICSs) have been designed and built, but to date, there has been no systematic evaluation of the effectiveness of these structures. To achieve this objective, first an understanding of the interaction between different ice processes and the ICSs must be established. For this purpose, a total of four ICSs located in the province of Quebec were monitored during the 2021-2022 winter. The results showed that the ice jam holding time could vary from 1.5 to 68.5 h. The release of the jam was mechanically driven when the ratio of release to initiation Froude number was higher than one and was thermally driven when this ratio was lower than one, and the water temperature increased between initiation and release. Also, as the ratio of the total pier spacing to upstream river width increased, the holding time decreased. Key words: ice control structure, ice engineering, ice jam, HS-flood control works, field monitoring, 1. Introduction River ice encompasses a range of processes, including the formation, evolution, transport, accumulation, dissipation, and deterioration of different types of ice. These processes are influenced by the dynamic [...]

According to Department of Fisheries and Oceans Canada, culverts and other stream crossings must be designed to ensure fish passage. The effects of ice processes on these fish passage designs have never been assessed. This study is the first to document ice processes on two different types of fish passage designs (streambed simulation and baffle). The results of a 2 year field monitoring campaign showed that the culvert simulating the streambed retains a natural ice regime, i.e., both freeze-up and break-up occurred concurrently with the rest of the stream, while multiple supercooling events were recorded under a thin ice cover. As for the culvert with baffles, it was observed that the ice cover formed earlier and stayed longer in the culvert, which can create a barrier for fish transiting through them. Key words: ice engineering, culvert design, fish passage, baffles, streambed simulation, 1. Introduction Culverts are among the most widely used man-made hydraulic structures designed to ensure flow continuity from streams and creeks across roads and highways. In Quebec alone, there are [...]

The blockage of water intakes by ice is recurrent in northern rivers during winter. Previous field studies have monitored field conditions leading to ice blockage and provided a review of mitigations methods. However, to improve the efficacy of these measures, the mechanisms that create the blockage need to be locally measured. For this purpose, a field campaign was implemented to monitor a water intake on the Mille-Iles River at Terrebonne, Quebec, during the winter of 2020-2021. Results from this study showed that ice accumulation on the trash rack had an average growth rate of 1.35 cm/h and reached a maximum thickness of 24 cm. The release rate of these trash rack accumulation events was on average 1.8 cm/h, which is 30% faster than the deposition rate. A minimum cumulative degree minutes of supercooling of 4.5[degrees]C.min was required for the start of a trash-rack ice-accumulation event. Key words: ice engineering, ice blockages, frazil ice, supercooling, water intakes, 1. Introduction Blockage of water intakes by frazil ice is a recurring problem during winter, often resulting in shutdown of the related plants. The production of frazil occurs when water [...]

The natural disturbance-based management (NDBM) aims to maintain specific structural and compositional attributes of natural forests in managed stands. Operationally, NDBM relies on diversifying and adapting silvicultural practices, including partial harvesting (PC), to expand the range of options beyond that of simply clearcuts (CC). Established in 1998, the Sylviculture et Amenagement Forestier Ecosystemique (SAFE) project evaluates this potential in hardwood, mixedwood, and coniferous stands in northwestern Quebec, Canada. Our results confirmed a part of the NDBM objectives, i.e., PC allowed the maintenance of stands with mixed structure and composition, constituting an interesting complement to CC, which reset stand regeneration. However, PC did not accelerate the stand transition to later stages with less intensive harvesting or to earlier stages with more intensive harvesting. We essentially had an initial impact, delaying or stopping the stand evolution that dissipates over time and more quickly with less intensive harvesting. Furthermore, our results did not support the ability of PC to enhance the development of old-growth attributes like deadwood. Despite the 20-year horizon of this study, further field surveys will be required in the future to better understand the impact of different silvicultural treatments on forest productivity and biodiversity preservation throughout a forest rotation. Key words: natural disturbance-based management (NDBM), mixed stands, boreal forest, partial cuts, clearcuts, 1. Introduction Natural disturbance-based management (NDBM) has been widely advocated as a means to maintain healthy and resilient forest ecosystems by reducing differences between natural and managed landscapes throughout North [...]

Wildfires are increasing in importance in many regions of the Canadian boreal forest and are an ongoing risk for forest management activities. We simulated the effects of fires on long-term harvest levels on the 59 forest management units of the province of Quebec, Canada, for the 2020-2100 period. Different climate change pathways (stable, RCP 4.5 or 8.5) and salvage logging rates (20% or 70% of mature burned stands) were simulated. Changes in forest flammability due to climate change, species migration, and forest management were also considered. Under stable climatic conditions, the decline in potential harvest levels due to fire, based on 50 simulations per scenario, ranged between 3% and 33% (mean = 11%) when high salvage logging rates were simulated, compared to 6%-45% (mean = 20%) for low salvage rates. Climate change caused increases in burn rates between -3% and 39% for RCP 4.5 and between 33% and 69% for RCP 8.5 at the end of the 21st century, depending on fire zones. However, the effects of these modified burn rates on harvest levels did not differ substantially from those of baseline burn rates, probably because the projected burn rates were highest during the later part of the simulations (2070- 2100), when their impacts on harvest level calculations were limited. This study indicates that potential harvest levels calculated without considering wildfires are likely to be non-sustainable. Key words: forest landscape modelling, harvest level, wildfire, climate change, salvage logging, 1. Introduction Wildfires have an important influence on forest management activities. In the short term, fire suppression is expensive (Stocks and Martell 2016), as are post-fire silvicultural interventions to restore [...]

Eastern white cedar (Thuja occidentalis) and red spruce (Picea rubens) contribute to the biodiversity and resilience of mixedwood forests. However, cuts that remove most or all the forest cover can cause the decline of these species. Among partial cutting options, the irregular shelterwood system (ISS) can create successful conditions for the development of advance regeneration and enrichment planting. We studied 6 years of ecophysiology of lower advance regeneration and planted seedlings of eastern white cedar and red spruce growing under a first ISS cut according to three cutting intensities: light cut (35% removal, 20 [m.sup.2]*[ha.sup.-1] residual basal area), moderate cut (42%, 18 [m.sup.2]*[ha.sup.-1]), and heavy cut (52%, 15 [m.sup.2]*[ha.sup.-1]). Light-saturated photosynthesis and height growth of planted cedar and both spruce types decreased with increasing cutting intensity, in response to an increase in competing vegetation. Therefore, to limit the negative impact of competing species on cedar and spruce regeneration, we recommend protecting tall advance regeneration (2 m+) during partial cut operations and using large-sized containerized seedlings (40-50 cm height) for enrichment planting. Results also suggest that a mechanical release could help optimize the physio-morphology and growth of both regeneration types of cedar and red spruce. Key words: continuous cover forestry, declining species, ecological silviculture, enrichment planting, natural regeneration, uneven-aged management Le thuya occidental (Thuja occidentalis) et l'epinette rouge (Picea rubens) contribuent a la biodiversite et a la resilience des forets mixtes. Cependant, les coupes qui suppriment la majeure partie ou la totalite du couvert forestier peuvent entrainer le declin de ces especes. Parmi les options de coupe partielle, le procede de regeneration par coupes progressives irregulieres (CPI) peut creer des conditions favorables au developpement de la regeneration preetablie et a la plantation d'enrichissement. Nous avons etudie pendant 6 ans l'ecophysiologie de la basse regeneration preetablie et de semis plantes de thuya occidental et d'epinette rouge poussant sous une premiere CPI selon trois intensites de coupe: coupe legere (35% de prelevement, 20 [m.sup.2]*[ha.sup.-1] de surface terriere residuelle), coupe moderee (42%, 18 [m.sup.2]*[ha.sup.-1]) et coupe forte (52%, 15 [m.sup.2]*[ha.sup.-1]). La photosynthese sous lumiere saturante et la croissance en hauteur du thuya plante et des deux types d'epinette ont diminue avec l'augmentation de l'intensite de la coupe, en reponse a une augmentation de la vegetation concurrente. Par consequent, pour limiter l'impact negatif des especes concurrentes sur la regeneration du thuya et de l'epinette, nous recommandons de proteger la regeneration preetablie de grande taille (2 m+) pendant les operations de coupe partielle et d'utiliser des semis en conteneur de grande taille (40-50 cm de hauteur) pour la plantation d'enrichissement. Les resultats suggerent egalement qu'un degagement mecanique pourrait contribuer a optimiser la physio-morphologie et la croissance des deux types de regeneration de thuya occidental et d'epinette rouge. Mots-cles : foresterie a couvert permanent, especes en declin, sylviculture ecologique, plantation d'enrichissement, regeneration naturelle, amenagement inequienne, Introduction The temperate mixedwood forest of Quebec (Canada) represents a rich, diversified, and complex ecosystem providing many economic and ecological services to society. Located in the balsam fir (Abies balsamea [...]

A flood frequency analysis is conducted using instantaneous peak flow data over a hydrologic sub-region of southern Quebec following three distinct methodological frameworks. First, the analysis is conducted locally using available instantaneous peak flow data. Second, the analysis is conducted locally using daily peak flow data processed to consider the peak flow effect. Third, a regional frequency analysis is conducted pooling all available instantaneous peak flow data over the study area. Results reveal a notable diversity in the resulting recurrence peak flow estimates and related uncertainties from one analysis to another. Expert judgement appears essential to arbitrate which alternative should be operated considering a specific context of application for flood plain delineation. Pros and cons for each approach are discussed. We finally encourage the use of a diversity of approaches to provide a robust assessment of uncertainty affecting peak flow estimates. Key words: flood frequency analysis, instantaneous peak flow, peak flow effect, regional frequency analysis. Une analyse de la frequence des crues est effectuee a l'aide de donnees instantanees sur les debits de pointe dans une sous-region hydrologique du sud du Quebec, selon trois cadres methodologiques distincts. Tout d'abord, l'analyse est menee localement a l'aide des donnees instantanees de debit de pointe disponibles. Deuxiemement, l'analyse est menee localement a l'aide des donnees de debit de pointe quotidiennes traitees afin de tenir compte de l'effet de debit de pointe. Troisiemement, une analyse de frequence regionale est effectuee en regroupant toutes les donnees instantanees de debit de pointe disponibles pour la zone d'etude. Les resultats revelent une diversite notable dans les estimations des debits de pointe recurrents et les incertitudes connexes d'une analyse a l'autre. Un jugement d'expert semble essentiel pour determiner quelle solution de rechange devrait etre utilisee en tenant compte d'un contexte particulier d'application pour la delimitation des plaines inondables. Les avantages et les inconvenients de chaque approche sont discutes. Enfin, les auteurs encouragent l'utilisation d'une diversite d'approches afin de fournir une analyse solide de l'incertitude qui influe sur les estimations des debits de pointe. [Traduit par la Redaction] Mots-cles : analyse de frequence des crues, debit de pointe instantane, effet de debit de pointe, analyse de frequence regionale., 1. Introduction Frequency analysis is a common tool for flood risk assessment. It associates a peak flow value [x.sub.T] with a recurrence interval T (or return period), which is the [...]

The challenges faced recently by the North American forest products industry have forced it to review many of its key operations. Implementing logistics centers for such a context may therefore help in allocating the wood fibre more efficiently and in reducing sorting and transportation costs. This paper aims to better understand the interaction between a forest logistics center and a complex forest network while exploring the business environment favoring the use of such a structure. A profit maximization model is proposed and applied to a real case in the Mauricie region in Quebec, Canada. A total of 18 groups of scenarios are tested, based on the use of a sort yard and of backhauling. Results show that a logistics center already in operation adds $0.52 in profits for each cubic metre of wood available for harvest (over 2 580 411 [m.sup.3] per year) for the network under study ($1.4 million annually). A sensitivity analysis also highlights that higher prices and sorting error rates have the greatest impact on the logistics center's profitability. Key words: logistics centers, forest network, backhauling, sorting yards, supply chain management and design. Les defis recents auxquels a fait face l'industrie forestiere en Amerique du Nord l'ont amenee a revoir plusieurs operations majeures. Dans un tel contexte, la mise en place de centres logistiques pourrait donc aider a assurer une allocation plus efficace de la matiere ligneuse et a reduire les couts de triage et de transport. Cet article vise a mieux comprendre l'interaction entre les centres logistiques forestiers et un reseau forestier complexe tout en explorant l'environnement d'affaire favorisant l'utilisation d'une telle structure. Un modele de maximisation des profits est propose et applique pour un cas reel dans la region de la Mauricie au Quebec, Canada. Au total, 18 groupes de scenarios ont ete testes, fondes sur l'utilisation d'une cour de triage et d'un transport de retour. Les resultats demontrent que le centre logistique deja en operation fait augmenter le profit de 0,52 $ pour chaque metre cube de bois disponible pour la recolte (plus de 2 580 411 [m.sup.3] par an) dans le reseau a l'etude (1,4 M$ par an). Une analyse de sensibilite a aussi mis en evidence que des prix et des taux d'erreur de triage plus eleves ont le plus d'impact sur la rentabilite des centres logistiques. [Traduit par la Redaction] Mots-cles : centre logistique, reseau forestier, transport de retour, cour de triage, conception et gestion de la chaine d'approvisionnement., Introduction The forest products industry in North America has been facing important challenges in the past few years with the housing crisis of2008-2009 and the decline of the pulp and [...]

In recent years, inclusion of spatial considerations in forest operations management has attracted great attention of both researchers and practitioners. In the province of Quebec, Canada, forest product companies subcontract harvesting operations to contractors. One of the challenges faced by the harvesting teams relates to moving the harvesting machineries between harvest areas, which is usually very costly and time consuming. To facilitate these operations, we propose a planning support tool to group the harvest areas in a way that the spatial dispersion of the clusters is reduced. We employed the spectral clustering algorithm to generate many alternative clusters of a set of harvest areas based on their transportation distance from one another and their available timber volume. Afterwards, a set covering model is developed to choose the clusters corresponding to the least spatial dispersion and approximately equal volume of timber. The approach is tested in a real case in Quebec and the results of two versions of set covering model were compared and analyzed.Key words: forest operations management, spatial dispersion, minimum spanning tree, spectral clustering, set covering.Ces dernieres annees, l'inclusion de considerations spatiales dans la gestion des operations forestieres a suscite beaucoup d'interet tant chez les chercheurs que chez les praticiens. Dans la province de Quebec, au Canada, les compagnies de produits forestiers donnent les operations de recolte en sous-traitance a des contracteurs. Un des defis auxquels sont confrontees les equipes qui font la coupe est associe au deplacement de la machinerie entre les aires de coupe qui est habituellement tres couteux en temps et en argent. Par consequent, dans le but de faciliter ces operations, nous proposons un outil d'aide a la planification pour regrouper les aires de coupe afin de reduire la dispersion spatiale des groupements. Nous utilisons un algorithme de groupement spectral pour generer plusieurs alternatives de groupement d'un ensemble d'aires de coupe sur la base de leur distance les unes des autres et des volumes de bois disponibles. Ensuite, un modele de couverture d'ensemble est elabore pour choisir les groupements correspondant a la moins grande dispersion spatiale avec un volume de bois approximativement egal. La methode a ete testee avec un cas reel au Quebec et les resultats de deux versions du modele de couverture d'ensemble ont ete compares et analyses. [Traduit par la Redaction]Mots-cles : gestion des operations forestieres, dispersion spatiale, arbre couvrant de poids minimal, groupement spectral, couverture d'ensemble., 1. IntroductionIn the province of Quebec, Canada, forestry companies subcontract timber harvesting operations to third-party contractors. In order for these contractors to continue earning profits, they need to find a [...]

The electricity sector is the largest source of greenhouse gases (GHG) emissions in the world, and reducing these emissions can often be costly. However, because electricity markets remain integrated at a shallow level (with different pricing regulations), many gains from deeper integration (adoption of marginal cost pricing everywhere) are yet to be realized. This paper assesses the benefits of deep integration between a 'hydro' jurisdiction and a 'thermal' one. It also underscores the inefficiency of trade when pricing rules differ. Our detailed hourly model, calibrated with real data from the provinces of Ontario and Quebec, Canada, estimates price, consumption, emissions and welfare changes associated with fully integrating electricity markets, under transmission constraints. A negative abatement cost of $37/tonne of C[O.sub.2] was found (for more than 1 million tonnes), clearly illustrating the untapped potential of wealth creation in carbon reduction initiatives. Furthermore, given the inefficiency of shallow integration between markets, we found that removing interconnections between markets offers a relatively affordable C[O.sub.2]-reduction opportunity, at $21.5/tonne. Keywords: Market Integration, Regulation, Electricity Trade, Environmental Impacts, 1. INTRODUCTION While many economic and environmental issues have become global, electricity markets have, to a large extent, remained local. Despite the existence of numerous regional integration initiatives, many obstacles [...]

The Kamouraska Formation is an uppermost Cambrian--lowermost Ordovician quartz-arenite-dominated unit of controversial origin deposited on the southeastern slope of Laurentia bordering the Iapetus Ocean. It is exposed in the Quebec Appalachians on the south shore of the St. Lawrence Estuary. The formation consists of basal polymictic conglomerate and overlying massive sheet-like quartz arenite. The conglomerate beds are reversely and reversely to normally graded. The quartz arenite beds are generally massive, although they may show coarse-tail grading. Beds containing full or partial Bouma sequences are rare. Paleoflow directions from ripple-cross lamination, ripple marks on bed surfaces, and sole marks point towards southeast, south, and southwest. The clastic sediments of the Kamouraska were transported into the deep sea by sediment gravity flows that evolved from hyperconcentrated to concentrated density flows, and then to turbidity currents. The depositional environment is interpreted to have been a southwest-trending meandering submarine canyon. The exposed part of the canyon deposits is slightly oblique to the strike of slope. If correct, our interpretation establishes the preservation of continental-slope deposits in more distal deep-water siliciclastic sedimentary rocks of the Taconian orogen in Quebec, which traditionally have been interpreted as submarine-fan and (or) basin-plain deposits. The orientation of a canyon near parallel-to strike of the slope may have been controlled by syn-depositional growth faults. The coarsest hyperconcentrated flows, which deposited the conglomerate, were restricted to the deepest parts of the canyon during its early stages of development, whereas the concentrated density flows that deposited the massive quartz-arenite beds covered a wider area. La Formation de Kamouraska est une unite du Cambrien superieur--Ordovicien inferieur dominee par une arenite quartzique d'origine controversee deposee sur la pente sud-est de la Laurentie bordant l'Ocean Iapetus. Elle affleure dans les Appalaches du Quebec sur la rive sud de l'estuaire du Saint-Laurent. La formation comprend un conglomerat de base polymictique sous une arenite quartzique en forme de feuillet massif. Les lits de conglomerat sont a gradation inverse et inverse a normale. Les lits d'arenite quartzique sont generalement massifs bien qu'ils puissent avoir un granoclassement frustre a la base. Les lits contenant des sequences entieres ou partielles de Bouma sont rares. Les directions des paleo-ecoulements a partir de laminations obliques de rides, de rides de plage a la surface des lits et de marques de structure basale pointent vers le sud-est, le sud et le sud-ouest. Les sediments clastiques de la Formation de Kamouraska ont ete transportes en profondeur dans la mer par des ecoulements gravitaires de sediments qui ont evolue a partir de courants de densite hyperconcentres a concentres puis a des courants de turbidite. L' environnement de deposition est interprete comme ayant ete un canyon a meandres a tendance vers le sud-ouest. La partie des depots de canyon qui affleure est legerement oblique par rapport a la direction de la pente. Si elle est juste, notre interpretation etablit la preservation des gisements sur la pente continentale dans des roches sedimentaires d'eau profonde plus distales de l'orogene taconique au Quebec, lesquelles ont traditionnellement ete interpretees comme un eventail sous-marin et (ou) des depots de plaine abyssale. L'orientation d'un canyon presque parallele a la direction de la pente pourrait avoir ete controlee par des failles syn-depositionnelles de croissance. Les ecoulements hyperconcentres les plus grossiers, qui ont depose le conglomerat, ont ete restreints aux parties les plus profondes du canyon durant ses premiers stages de developpement, alors que les ecoulements de densite concentres qui ont depose les lits d' arenite quartzique massifs recouvraient un plus grand secteur. [Traduit par la Redaction], Introduction The Kamouraska Formation is a quartz-arenite unit deposited during the Cambrian-Ordovician boundary interval in the Quebec Appalachians. It forms prominent ridges in the folded lower Paleozoic rocks on the [...]

Differential subsidence of as much as 0.85 m is affecting the access road to Umiujaq Airport in Nunavik (Quebec), Canada, located in the discontinuous permafrost zone. A geotechnical and geophysical investigation including piezocone test, ground-penetrating radar profiling, electrical resistivity tomography, and numerical modeling of the thermal regime of the road embankment and subgrade is presented to characterize the ground stratigraphy and permafrost conditions and to assess the exact causes and effects of permafrost degradation on the road embankment. The subsidence is due to thaw consolidation taking place in a layer of ice-rich silt underneath a superficial sand layer. While the seasonal freeze-thaw cycles were initially restricted to the sand layer, the thawing front has now reached the thaw-unstable ice-rich silt layer. According to our numerical modeling, the increase in air temperature recently observed in Nunavik cannot be the sole cause of the observed subsidence affecting this engineering structure. The thick embankment also acts as a snow fence favoring the accumulation of snow on the embankment shoulders. The permafrost degradation is also due to the thermal insulation of the snow cover reducing heat loss in the embankment shoulders and toes. Key words: permafrost degradation, thaw subsidence, piezocone test, geophysical surveys, numerical modeling, thermal regime. La route d'acces a l'aeroport d'Umiujaq au Nunavik (Quebec), Canada, dans la zone de pergelisol discontinu est affecte par un affaissement differentiel aussi important que 0,85 m. Des travaux d'investigation geotechnique et geophysique, dont un essai de penetration au piezocone, des profils de georadar et de resistivite electrique, et des simulations numeriques du regime thermique du remblai routier et de l'infrastructure sont presentes afin de caracteriser la stratigraphie du sous-sol et les conditions du pergelisol, et d'expliquer les impacts de la degradation du pergelisol sur le remblai routier. L'affaissement est cause par la consolidation au degel d'une couche de silt riche en glace sous une couche superficielle de sable. Alors que seule la partie superieure de la couche de sable subissait initialement les cycles saisonniers de gel--degel, le front de degel atteint maintenant la couche de silt riche en glace instable au degel. Selon les resultats obtenus des simulations numeriques, l'augmentation de la temperature de l'air recemment observee au Nunavik ne peut pas etre la seule cause de l'affaissement. Telle une barriere a neige, le remblai routier epais favorise l'accumulation de la neige sur ses accotements. La degradation du pergelisol est aussi provoquee par l'effet d'isolation thermique du couvert nival qui reduit les pertes de chaleur sur les accotements et aux pieds du remblai. Mots-cles : degradation du pergelisol, affaissement au degel, essai de penetration au piezocone, leves geophysiques, modelisation numerique, regime thermique., Introduction Geohazards in cold regions Climate warming already occurring at high latitudes (IPCC 2007) is accompanied by geohazards such as thaw subsidence and active-layer detachment failure. Among these geohazards associated [...]

Resume: La coupe avec protection des petites tiges marchandes est un type de coupe partielle qui consiste generalement a recolter toutes les tiges d'un diametre a hauteur de poitrine (dhp) superieur a 15,0 cm, tout en conservant les tiges de plus petites dimensions. Le succes du traitement, applique a des forets resineuses mures dominees par le sapin baumier (Abies balsamea (L.) Mill.) ou l'epinette noire (Picea mariana (Mill.) Britton, Sterns & Poggenb.), repose en partie sur la capacite des tiges protegees a survivre. Un modele logistique mixte a ete calibre a partir de 27 blocs experimentaux etablis au Quebec. Ce modele identifie les variables qui conditionnent les probabilites de pertes des tiges individuelles protegees de 5,1 cm et plus de dhp, par mortalite sur pied ou par chablis, 5 ans apres des coupes avec protection des petites tiges marchandes. Les resultats indiquent que les probabilites de pertes apres traitement sont largement tributaires des caracteristiques du peuplement avant coupe (surface terriere marchande, densite de gaules, proportion de pin gris (Pinus banksiana Lamb.)), de la qualite des operations (procedede recolte, taux de protection des petites tiges marchandes) et des caracteristiques des tiges protegees au moment de la coupe (inclinaison, dhp, essence). Les variables associees a l'exposition aux vents et a l'ecologie des stations n'ont pas permis d'ameliorer le modele. Afin d'eviter des pertes trop elevees, il importe de bien cibler les peuplements a traiter et de realiser un suivi rigoureux des operations de recolte. Harvesting with protection of small merchantable stems is a type of partial harvesting whereby all trees larger than 15.0 cm in diameter at breast height (dbh) are usually cut while smaller stems are retained. In mature coniferous stands dominated by balsam fir (Abies balsamea (L.) Mill.) or black spruce (Picea mariana (Mill.) Britton, Sterns & Poggenb.), the success of the treatment depends partly on the survival of retained trees. A mixed logistic model was calibrated to identify the variables affecting the likelihood of losses of protected individual stems with dbh [greater than or equal to] 5.1 cm, by standing-tree mortality or windfall, 5 years after harvesting with protection of small merchantable stems in 27 experimental cutblocks in Quebec. The results indicate that postharvest losses were largely dependent on preharvest stand characteristics (merchantable basal area, sapling density, and jack-pine (Pinus banksiana Lamb.) ratio), the quality of the treatment (harvesting methods, retention rate of small merchantable stems), and the characteristics of retained trees at harvest time (tilt, dbh, and species). The variables associated with wind exposure and site ecology did not allow for improvement of the model. It is imperative to carefully choose the stands to be treated and to closely monitor harvesting to minimize losses. [Journal translation], Introduction En foret boreale canadienne, le cycle de feu joue un role important dans la dynamique et la structure des peuplements forestiers. Lorsque les cycles sont longs, les forets preservees [...]

In the Saint-Charles River watershed, it is necessary to better manage water from both a qualitative and quantitative point of view. Hydrological modelling can help managers in their decision making regarding water. This work concerns the implementation of the semi-distributed water quality model soil and water assessment tool (SWAT) for the simulation of stream flows in this urbanized and relatively mountainous watershed. This first approach is compared with two others, one relying on the use of the GR4J global hydrological model, and the other relying on the use of an artificial neural network. The amount of water resulting from the melting of snow, here calculated by SWAT's snowmelt algorithm, has been provided to the models used in these other two approaches. The watershed offers an important challenge to hydrologists because of the scarcity of its database, namely the quasi absence of spatial information on precipitation and the absence of detailed pedological studies. Results show that the hydrological performance resulting from all three approaches is limited by the availability of data, but the performance of the approach using SWAT is more so than the other two. The lack of information hinders exploiting the full modelling capability of SWAT. Moreover, SWAT's complexity turns out to be disadvantageous when compared with the simpler model structures of GR4J and of the neural network. It thus appears essential, considering the Saint-Charles River watershed's strategic importance for water supply and touristic and recreational activities, that more effort should be spent in gaining climatological and pedological observations within the watershed. Key words: hydrologic modelling, stream flow simulation, SWAT, GR4J, artificial neural network. Sur le bassin versant de la riviere Saint-Charles, il est necessaire de mieux gerer l'eau, d'un point de vue quantitatif et qualitatif. Or la prise de decisions peut etre aidee par la modelisation hydrologique. Ce travail porte sur la mise en place du modele semi-distribue de qualite de l'eau SWAT (<< soil and water assessment tool >>) sur ce bassin versant urbain et relativement montagneux, et sur revaluation de sa capacite a simuler les debits. Cette premiere approche est comparee a deux autres, reposant pour l'une sur l'utilisation du modele hydrologique global GR4J, et pour l'autre sur l'emploi d'un reseau de neurones. La quantite d'eau issue de la fonte de la neige, calculee ici par le module de fonte de SWAT, a ete renseigneeea ces deux autres modeles. Ce bassin presente par ailleurs de reelles difficuMs pour ce type de modelisation, liees essentiellement au manque de donneees : quasi-absence d'information spatiale sur les precipitations et absence d'eetude pedologique detaillee. Les resultats, globalement satisfaisants, montrent toutefois que la performance hydrologique resultant des trois approches est limiteee par ces manques : celle utilisant SWAT davantage que les deux autres. Dans ce cas, les lacunes ne permettent pas d'utiliser le plein potentiel du modele SWAT, dont la structure plus lourde devient un inconvenient des que les donneees sont disponibles en quantite et en qualite insuffisantes pour en justifier l'exploitation, en opposition a GR4J et au reseau de neurones. Il semble donc incontournable, consideerant l'importance strategique du bassin versant de la riviere Saint-Charles pour l'approvisionnement en eau potable et le support aux activitesrecreatives et touristiques, que l'effort d'observation de ce territoire soit accru, afin d'y augmenter notamment les donneees climatologiques et pedologiques disponibles. Mots-cles: modelisation hydrologique, simulation des debits, SWAT, GR4J, reseau de neurones artificiel., 1. Introduction La riviere Saint-Charles (fig. 1), qui traverse la ville de Quebec de part en part, revet un caractere important pour sa population. En premier lieu, ce bassin versant [...]

We studied the in situ release of dissolved organic carbon (DOC) by growing a submerged freshwater macrophyte-epiphyte complex. Incubations with benthic chambers in five southeastern Quebec lakes show a net DOC production for different communities of Myriophyllum spicatum and Potamogeton spp. Daytime DOC release rates range from undetectable to 9.7 mg C x [m.sup.-2] x [h.sup.-1]. Although DOC release was restricted to daylight hours and thus suggestive of a photosynthesis-related process, we found no strong link between DOC release rates and concurrent illumination or temperature. We found no difference in DOC release rates between the three main colonizing species of the studied region. The overall mean DOC release rate was 4.57 mg C x [m.sup.-2] x [h.sup.-1] (standard deviation (SD), [+ or -]0.65) or 56 [micro]g C x g dry [weight.sup.-1] x [h.sup.-1] (SD, [+ or -]8), which we suggest can be used for extrapolations at the lake scale. Nous etudions la liberation in situ de carbone organique dissous (DOC) par un complexe submerge de macrophytes et d'epiphytes d'eau douce en croissance. Des incubations dans des enceintes benthiques dans cinq lacs du sud-est du Quebec indiquent des productions nettes de DOC dans differentes communautes de Myriophyllum spicatum et de Potamogeton spp. Les taux de liberation de DOC durant le jour varient de valeurs indecelables a 9,7 mg C x [m.sup.-2] x [h.sup.-1] Bien que la liberation de DOC soit restreinte aux heures d'eclairement et donc probablement un processus relie a la photosynthese, il n'existe pas de lien solide entre les taux de liberation de DOC et la temperature et l'eclairement concomitants. Il n'y a pas de difference entre les taux de liberation de DOC des trois principales especes colonisatrices de la region etudiee. Le taux global moyen de liberation de DOC est de 4,57 C x [m.sup.-2] x [h.sup.-1] (ecart type (ET), [+ or -]0,65) ou 56 [micro]g C x g masse [seche.sup.-1] x [h.sup.-1] (ET, [+ or -]8), valeurs que nous croyons pouvoir etre utilisees pour des extrapolations a l'echelle du lac tout entier. [Traduit par la Redaction], Introduction The loading of terrestrial dissolved organic carbon (DOC) can contribute significantly to the energy pathways of lake ecosystems (Pace et al. 2004; Carpenter et al. 2005; Kritzberg et al. [...]

Jack-in-the-Pulpit (Arisaema triphyllum (L.) Torr.) is a perennial forest herb of southern Canada and the eastern United States. The flowering periods of male and female inflorescences in relation to the temperature of the inflorescence and the activity pattern of visiting insects were studied in one population in western Montreal Island (Quebec, Canada). The flowering period of A. triphyllum was long (20 d in male and female plants), which is unusual in temperate Aroideae. This floral trait could have evolved secondarily as an adaptation to increase pollination efficiency under highly variable weather conditions at high latitude. In male and female plants, no significant temperature increase of the appendix was recorded. The warming effect of sunlight during the day could be sufficient for the emission of the attractive odour. Two Dipteran families, the Mycetophilidae and the Cecidomyiidae, were the most frequent insect visitors of A. triphyllum. Our observations showed that odour production is linked with the pollination activity beginning with insect visits. Key words: appendix temperature, temperate climate, long flowering period, latitudinal gradient, Mycetophilidae, Cecidomyiidae. Les periodes de floraison des inflorescences males et femelles du pent precheur (Arisaema triphyllum (L.) Torr.) ont ete etudiees dans une population situee dans l'ouest de l'Ile de Montreal (Quebec, Canada). La periode de floraison d'A. triphyllum est longue (20 fours pour les inflorescences males et femelles) contrairement aux autres Aroideae temperees. Ce trait floral pourrait avoir evolue secondairement comme une adaptation pour augmenter l'efficacite de la pollinisation sous une latitude plus nordique, la ou les conditions climatiques sont tres variables. Aucune augmentation significative de la temperature de l'appendice n'a ete enregistree chez les plants males et femelles. Le rechauffement solaire durant la journee pourrait etre suffisant pour provoquer l'emission dune odeur attractive. Deux famines de dipteres, les Mycetophilidees et les Cecidomyudees, representent les principaux insectes visiteurs d'A. triphyllum. Nos observations demontrent que la production d'odeur commence avec le debut de la periode d'activite des insectes visiteurs. Mots-cles : temperature appendice, climat tempere, longue periode florale, gradient latitudinal, Mycetophilidae, Cecidomyudae., Introduction The genus Arisaema Mart., a member of the Arum lily family (subfamily Aroideae), contains about 200 species mainly distributed throughout Asia (Gusman and Gusman 2002). In North America, Arisaema [...]

This paper presents soil fluxes of methane (C[H.sub.4]), nitrous oxide ([N.sub.2]O), and carbon dioxide (C[O.sub.2]) from 12 sites located in four major forest types, black spruce (Picea mariana (Mill.) BSP), jack pine (Pinus banksiana Lamb.), aspen (Populus spp.), and alder (Alnus spp.) stands, in the Eastmain and Chibougamau regions of Quebec. Fluxes were determined with closed chambers during the snow-free period from May to October 2007. Well-drained black spruce, jack pine, and aspen forest soils were net sinks of atmospheric C[H.sub.4] (-0.33 ± 0.11 mg*[m.sup.-2]*[day.sup.-1]), while alder-dominated wetland soils were sources of C[H.sub.4] (0.45 ± 0.12 mg.[m.sup.-2]*[day.sup.-1]). The cut-over alder wetland soil produced 131 times more C[H.sub.4] than the undisturbed wetland soil. Soil moisture and temperature mainly regulated C[H.sub.4] fluxes. [N.sub.2]O fluxes from these forest soils were highly variable and smaller (1.6 ± 0.33 µg N*[m.sup.-2]*[h.sup.-1]) than those from deciduous forest soils. [N.sub.2]O emission from the cut-over black spruce forest soil was 2.7 times greater than that from the mature black spruce forest soil. Large C/N ratios (27 to 78) and slow soil N mineralization and nitrification rates in these forest soils may have led to small [N.sub.2]O fluxes. C[O.sub.2] emissions from these forest soils, ranging from 0.20 to 2.7 g*[m.sup.-2]*[day.sup.-1], were mainly controlled by soil temperature. Cet article porte sur les flux de methane (C[H.sub.4]), d'oxyde nitreux ([N.sub.2]O) et de dioxyde de carbone (C[O.sub.2]) dans les sols de 12 stations situees dans quatre grands types de foret : peuplements d'epinette noire (Picea mariana (Mill.) BSP), de pin gris (Pinus banksiana Lamb.), de peuplier (Populus spp.) et d'aulne (Alnus spp.), dans les regions d'Eastmain et de Chibougamau au Quebec. Les flux ont ete mesures a l'aide de chambres fermees pendant la periode exempte de neige, de mai a octobre 2007. Les sols bien draines des forets d'epinette noire, de pin gris et de peuplier etaient des puits nets de C[H.sub.4] atmospherique (-0,33 ± 0,11 [mgm.sup.-2]*[j.sup.-1]) tandis que les sols des milieux humides domines par l'aulne etaient des sources de C[H.sub.4] (0,45 ± 0,12 mg*[m.sup.-2]*[j.sup.-1]). Un sol en milieux humides oU l'aulne avait ete coupe produisait 131 fois plus de C[H.sub.4] qu'un sol en milieux humides non perturbe. La temperature et l'humidite du sol regulaient le flux de C[H.sub.4]. Le flux de [N.sub.2]O dans ces sols forestiers etait tres variable et plus faible (1,6 ± 0,33 µg N*[m.sup.-2]*[h.sup.-1]) que dans les dans le sol de la foret feuillue. Les emissions de [N.sub.2]O provenant du sol d'une foret d'epinette noire coupee etaient 2,7 fois plus elevees que celles provenant du sol d'une foret mature d'epinette noire. Un rapport C:N eleve (27 a 78) et de faibles taux de mineralisation et de nitrification dans le sol de ces forets pourrait avoir limite le flux de NZ0. Les emissions de C[O.sub.2], qui variaient de 0,20 a 2,7 g C*[m.sup.-2]*[j.sup.-1] dans ces sols forestiers, etaient surtout fonction de la temperature du sol. [Traduit par la Redaction], Introduction Forests represent about 50% of the total land area in Canada (Lemmen and Warren 2004), and boreal forest is the dominant forest type, representing about one third of the [...]

Participation of aboriginal people in Canadian forestry is a requirement of sustainable management. We proposed a culturally adapted process to integrate Cree and scientific knowledge in Eeyou Istchee (northern Quebec) that could contribute to a better mutual understanding between Cree and non-Cree, and eventually favour the social acceptability of forest management strategies. We studied moose (Alces alces L.), the Cree featured species and the main forestry issue for the past 40 years. Cree and non-Cree have culturally differing visions for the management of moose habitat. In a previous article, we documented Cree knowledge about moose-habitat relationships. Here, we evaluated some hypotheses built from Cree knowledge by studying the behaviour of moose equipped with GPS collars. In general, results from our habitat use and selection analyses agreed with Cree observations and improved our understanding of moose--habitat relationships in northern Quebec. We jointly demonstrated the importance of mature mixed woods, balsam fir (Abies balsamea (L.) Mill.) stands, and riparian areas for moose in the northern black spruce (Picea mariana (Mill.) BSP) forest. In these specific areas, management approaches other than clear-cutting should be developed to preserve moose habitat quality. Such an alternative would potentially be more acceptable for the Cree people. La participation des autochtones a la foresterie canadienne est un prerequis a la gestion durable. Nous avons propose un processus culturellement adapte pour integrer les connaissances cries et scientifiques en Eeyou Istchee (nord du Quebec) pour accroitre la comprehension mutuelle entre les Cris et non-Cris, et favoriser l'acceptabilite sociale des strategies d'amenagement. Nous avons etudie l'orignal (Alces alces L.) qui est l'espece d'interet des Cris et une importante problematique forestiere, puisque se confrontent des visions culturelles distinctes au sujet de l'amenagement de son habitat. Dans un article precedant, nous avons documente les connaissances cries sur l'habitat de l'orignal. Dans le present article, nous avons evalue des hypotheses basees sur les connaissances cries avec des orignaux equipes de colliers GPS. Dans l'ensemble, nos resultats d'analyse d'utilisation et de selection d'habitat coincident avec les connaissances cries et ameliorent nos connaissances de l'habitat de l'orignal au nord du Quebec. Nous avons conjointement demontre l'importance des peuplements matures mixtes et de sapin baumier (Abies balsamea (L.) Mill.) et des zones riveraines pour l'orignal dans la pessiere noire (Picea mariana (Mill.) BSP). Dans ces zones specifiques, des alternatives a la coupe rase devraient etre developpees afin de preserver un habitat de qualite pour l'orignal. Ces methodes seraient susceptibles d'etre mieux acceptees par les Cris., Introduction The participation of aboriginal people in Canadian forestry is a requirement for sustainable forest management (CCFM 2003; Gilchrist et al. 2005; Manuel-Navarrete et al. 2006). However, cultural divergences (including [...]

We investigated whether woodland caribou (Rangifer tarandus caribou) would remain in a 2772 [km.sup.2] area in eastern Quebec where the forest management plan included the preservation of large forest blocks (35-182 [km.sup.2]) linked with > 400 m wide corridors and where cuts were amalgamated in large zones. To evaluate changes in caribou abundance and habitat selection, we conducted five aerial surveys and followed by telemetry 13 to 22 female caribou each year, from March 1998 to March 2005. Caribou numbers declined by 59% between 1999 and 2001 but gradually recovered to initial abundance. Female survival increased from 73.3% in 1999 to 87.3%-93.4% in 2004 and 2005. Caribou selected protected blocks, used corridors in proportion to their availability, and avoided logged areas. They preferred closed conifer stands without terrestrial lichens and open conifer stands with or without terrestrial lichens throughout the study. Open habitats (clearcuts and burns), regenerating sites, mixed and deciduous stands, and water bodies were avoided. The main zones used by caribou gradually shifted towards the southwest of the study area, likely as a result of disturbance and habitat loss due to logging of mature conifers in the east. We conclude that caribou numbers were maintained within the managed area as a result of the presence of protected blocks and uncut continuous forest. Nous avons verifie si le caribou forestier (Rangifer tarandus L.) pourrait se maintenir dans une afire de 2772 [km.sup.2] dans l'est du Quebec ou l'amenagement forestier incluait la protection de vastes blocs de foret (35-182 [km.sup.2]) relies par des corridors boises d' au moins 400 m de largeur et ou les coupes etaient regroupees dans de vastes zones. Pour evaluer les changements dans l'abondance du caribou et la selection de l'habitat, nous avons realise cinq inventaires aeriens et suivi par telemetrie de 13 a 22 caribous femelles chaque annee, de mars 1998 a mars 2005. Le nombre de caribous a diminue de 59 % entre 1999 et 2001, mais s'est graduellement retabli jusqu'au niveau initial. La survie des femelles a augmente de 73,3 % en 1999 a 87,3 % en 2004 et 93,4 % en 2005. Le caribou a choisi les blocs proteges, a utilise les corridors proportionnellement a leur disponibilite et a evite les wires coupees. Il a prefere les peuplements fermes de coniferes sans lichens terrestres et les peuplements ouverts de coniferes avec on sans lichens terrestres tout an long de l'etude. Le caribou a evite les habitats ouverts (coupes a blanc et brulis), les sites en regeneration, les peuplements melanges et feuillus et les plans d'eau. Les principaux secteurs utilises par le caribou se sont deplaces graduellement vers le sudouest, de toute evidence en reponse a la perturbation et a la perte d'habitat cauees par la recolte des peuplements matures de coniferes dans l'est. Nous concluons que le nombre de caribous s'est maintenu dans Faire amenagee grace a la presence de blocs proteges et de corridors de foret non coupee. [Traduit par la Redaction], Introduction The abundance and distribution of woodland caribou (Rangifer tarandus caribou) have drastically declined over the last 150 years across North America (Bergerud 1974). Although the reasons for this decline [...]

Total mercury and methylmercury concentrations ([THg], [MeHg]) were measured in littoral macroinvertebrates from Lake St. Pierre, Quebec, Canada. Functional groups (detritivore, grazer, edible predator, inedible predator) explained the greatest fraction of [MeHg] variation compared with time (year, month), and space (station and shore). Greatest [THg] and [MeHg] were found in inedible predators mostly from families of heteropterans and coleopterans. Detritivores and grazers exhibited the lowest Hg concentrations, while edible predators were intermediate. Inedible predators also had the highest percentage of MeHg ([MeHg]/[THg]), with some taxa close to 100%. Such high percentages are seldom observed in freshwater organisms other than piscivorous fish. MeHg burden (concentrations x biomass) in inedible predators accounted for 10% of the MeHg pool for the whole invertebrate community. These large quantities of MeHg are sequestrated in aquatic 'trophic dead ends' and could partly explain the low [MeHg] measured in fish, compared with [MeHg] of macroinvertebrates from Lake St. Pierre and other freshwater ecosystems with large littoral zones. We recommend taking into account the inedible organisms in Hg cycling models to avoid a possible overestimation of the MeHg pool available to fish. Nous avons mesure les concentrations en mercure total et methylmercure ([THg] et [MeHg]) chez les macroinverte bres littoraux du lac Saint Pierre, Quebec, Canada. Le groupe fonctionnel (detritivore, brouteur, predateur consommable, predateur non consommable) explique la plus forte proportion de la variation de [MeHg] compare au temps (annee, mois) et a l'espace (station, rive). Les plus fortes [THg] et [MeHg] se retrouvent chez les predateurs non consommables appartenant a des familles de coleopteres et d'heteropteres. Les detritivores et les brouteurs montrent les plus faibles concentrations, alors que les predateurs consommables sont intermediaires. Les predateurs non consommables presentent egalement les plus forts pourcentages de MeHg ([MeHg]/[THg]), avec certains taxons proches de 100 %. De tels pourcentages ne sont habituellement observes en eau douce que chez les poissons piscivores. La charge de MeHg (concentration x biomasse) chez les predateurs non consommables represente 10 % du reservoir de MeHg de la communaute des macroinvertebres. Cette quantite importante de MeHg est sequestree dans des impasses trophiques aquatiques et pourrait expliquer partiellement les faibles [MeHg] mesurees chez les poissons comparees aux [MeHg] des macroinvertebres du lac Saint Pierre et des autres ecosystemes d'eau douce avec des zones littorales etendues. Nous recommandons de tenir compte des organismes non consommables dans les modeles de cycle du Hg afin de ne pas surestimer les quantites de MeHg disponibles pour les poissons., Introduction Monomethylmercury (MeHg) is considered a global threat to human and ecosystem health because of its neurotoxicity and accumulation in food webs through biomagnification (Boening 2000). Since fish consumption is [...]

Abstract: In this study, a diameter increment model was calibrated for individual trees in hardwood stands in Quebec, Canada. Two random effects, a first one for the plot and a [...]

Abstract: For Quebec's black spruce forests, the usual harvesting process involves logging with protection of regeneration and soil (CPRS) or clearcutting, but at the social level, public perception of this [...]

Abstract: An in situ experiment was done in July 2004 to test and compare the influence of suspended bivalve cultures (1- and 2-year-old blue mussels (Mytilus edulis) and sea scallops [...]

Abstract: In a previous laboratory experiment, water velocity had a strong negative effect on periphyton [[delta].sup.13]C and [[delta].sup.15]N, probably reflecting the effect of flow on boundary-layer exchange. To determine whether [...]

Abstract: This study aims at evaluating the hydrologic impacts of climate change on the Chateauguay River basin in the province of Quebec, Canada. Three global climate models (GCMs) covering a [...]

While empirical studies linking biodiversity to local environmental gradients have emphasized the importance of lake trophic status (related to primary productivity), theoretical studies have implicated resource spatial heterogeneity and resource relative ratios as mechanisms behind these biodiversity patterns. To test the feasibility of these mechanisms in natural aquatic systems, the biodiversity of crustacean zooplankton communities along gradients of total phosphorus (TP) as well as the vertical heterogeneity and relative abundance of their phytoplankton resources were assessed in 18 lakes in Quebec, Canada. Zooplankton community richness was regressed against TP, the spatial distribution of phytoplankton spectral groups, and the relative biomass of spectral groups. Since species richness does not adequately capture ecological function and life history of different taxa, features which are important for mechanistic theories, relationships between zooplankton functional diversity (FD) and resource conditions were examined. Zooplankton species richness showed the previously established tendency to a unimodal relationship with TP, but functional diversity declined linearly over the same gradient. Changes in zooplankton functional diversity could be attributed to changes in both the spatial distribution and type of phytoplankton resource. In the studied lakes, spatial heterogeneity of phytoplankton groups declined with TP, even while biomass of all groups increased. Zooplankton functional diversity was positively related to increased heterogeneity in cyanobacteria spatial distribution. However, a smaller amount of variation in functional diversity was also positively related to the ratio of biomass in diatoms/chrysophytes to cyanobacteria. In all observed relationships, a greater variation of functional diversity than species richness measures was explained by measured factors, suggesting that functional measures of zooplankton communities will benefit ecological research attempting to identify mechanisms behind environmental gradients affecting diversity. Key words: communities; functional diversity; heterogeneity; lakes; phytoplankton; productivity; Quebec, Canada; species richness.

Abstract: Ecosystem management requires good knowledge of preindustrial ecosystems and their dynamics. However, in most regions of Quebec, the original forested landscape has been altered by human activities. To validate [...]

Abstract: We assessed the organic C stocks and inferred their changes in vegetation biomass, forest floor, and soil using a 50 year chronosequence of red pine (Pinus resinosa Ait.) plantations [...]

Resume: L'estimation de l'ampleur de la crue moyenne de petits cours d'eau, rarement instrumentes, prend de plus plus d'interet, notamment dans l'optique d'une gestion environnementale systemique d'un bassin versant. A [...]

Abstract: The effects of 20th century spruce budworm (Choristoneura fumiferana (Clem.)) outbreaks on forest dynamics was examined in the southern and northern parts of the mixedwood forest zone in central [...]

Abstract: Large-scale timber harvesting in the northern black spruce forest, on Quebec Cree territory, causes immediate loss of productive wildlife habitat for Cree hunters. Duration of this impact is key [...]

Abstract: The long-term effects of high-intensity diameter-limit cuttings conducted in the winter and summer of the 1940s and 1950s on the dynamics of softwood and mixedwood stands in southeastern Quebec [...]

The objective of this experiment was to evaluate the response of two unimproved mixed-species hayfields in Quebec, Canada, to management regimes of high fertilization and intensive mowing. Dry matter and nutrient yields, tissue nutrient concentrations, and soil nutrient pools were determined in Bromus-Poa and Pleum-Lolium hayfields fertilized with inorganic fertilizer, liquid dairy manure, or no fertilizer and mown at different intensities (every 2 wk or unmown, during a 12-wk period). Dry matter and nutrient yields, and tissue nutrient concentrations were similar in plots receiving inorganic and dairy manure fertilizers, hut the dry matter yield was 0.6 to 2.8 Mg [ha.sup.-1] higher in fertilized plots than the unfertilized control. Repeated mowing reduced dry matter yield by 1.5 to 2.7 Mg [ha.sup.-1], however, tissue nutrient concentration and nutrient yield were greater in mown than unmown plots. The apparent N recovery in a mown, fertilized Pleum-Lolium hayfield was greater than 100%, as the nutrient yields (143 kg N [ha.sup.-1]) were greater than the N fertilizer input of 75 kg N [ha.sup.-1]. Soil N[O.sub.-3] and microbial biomass N concentration were significantly (P < 0.05, Tukey test) lower in fertilized plots that were mown every 2 wk than unmown during the study period. Frequent mowing may be a management option that can reduce soil residual N and thus limit N[O.sub.-3] leaching from mixed-species hayfields.