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Decades of acidic deposition and timber harvesting have depleted calcium (Ca) stocks in soils, especially at base-poor soils characterized by low base cation weathering rates. One approach to tracking Ca sources from soil is by using Ca/Sr ratios in vegetation, while [sup.87]Sr/[sup.86]Sr ratios have also been used to estimate mineral weathering rates. To evaluate the uses of Ca/Sr ratios and Sr isotopes in identifying Ca sources in sugar maple (Acer saccharum Marsh.) trees, three base-poor sites on the Canadian Shield and three limestone sites in southern Ontario were sampled for Ca, Sr, and [sup.87]Sr/[sup.86]Sr ratios. Higher Ca/Sr ratios in soil extracts and sugar maple tissues at base-rich sites compared with base-poor sites reflect different minerology among regions, while the Ca/Sr discrimination factor between roots and foliage indicated that internal cycling exerts a major control on Ca/Sr ratios in sugar maple. At the three off-shield sites, [sup.87]Sr/[sup.86]Sr ratios in soil and tree tissues were higher than precipitation but were indistinguishable for off-shield sites. Mixing models using a 1.0 mol [L.sup.-1] HCl soil extract as the weathering endmember indicated that a lower proportion of weathering Ca compared with other geochemical approaches. One potential explanation is that the extraction method dissolves more recalcitrant minerals to a greater extent than under field conditions, leading to a higher weathering rate endmember value used in the mixing model. Key words: calcium, strontium isotopes, weathering, deposition, sugar maple, Introduction A century of atmospheric acidic deposition and timber harvesting has reportedly depleted soil calcium (Ca) stocks over large parts of eastern North America (Likens et al. 1996; Watmough et [...]

Ruth-Roy Lake (Killarney Provincial Park, Ontario, Canada) is an ultra-oligotrophic, naturally acidic waterbody. Lakes in Killarney Provincial Park were impacted by long-range transportation of contaminants from copper-nickel smelting operations in nearby Sudbury, but recent lake monitoring indicates that Ruth-Roy Lake has been less acidic than inferred pre- industrial pH conditions. We assessed the effects of pH change, reduced sulphur emissions, and drivers of reduced acidity using biological and geochemical paleolimnological techniques. Ruth-Roy Lake experienced notable biological and chemical change over the past ~150 years. All examined proxies supported that Ruth-Roy Lake was naturally acidic but further acidified as early as ca. 1920s, with the strongest acidification signal apparent in ca. 1940s. Biological recovery in diatom and cladoceran assemblages, however, is modest. We highlight the importance of understanding reference conditions to assess ecosystem recovery and climate-mediated change in clear acidic lakes located in industrial landscapes. Key words: acidification, smelting, monitoring, paleoecotoxicology, Introduction Sudbury (Ontario, Canada) is one of the world's largest copper-nickel metal smelter centres, with base metal ores discovered in the region in the late 19th century. Since the copper [...]

Groundwater is an important component of the hydrological cycle of southern Ontario, significant to water supply and discharge to surface water. To improve overall understanding of key hydrological mechanisms, a proof-of-concept framework is presented that consists of seven typical terrains or hydrogeological settings. Geologic and topographic controls influence each setting as recorded by climate, streamflow, and groundwater level data, which trace how water moves through various parts of the southern Ontario landscape. This hydrogeological framework considers the geology of surface sediment and bedrock, permeability and porosity (inferred), physiography, and topographic gradients to define seven distinctive hydrogeological terrains. The data and watershed selection process allow for concentration on patterns of hydrologic response across the landscape, with less focus on hydrologic accounting of the terrain. The analysis identifies events in climate, stream, and well-monitoring data indicative of influxes and temporal patterns of hydrological and hydrogeological response to local geology and topography, thus differentiating styles of groundwater movement in sediment/bedrock landscapes of the Paleozoic basin and Shield margin. A case study is provided for each setting: five in sediment (clay, sand, gravel, till upland, and thick till); and two in bedrock (crystalline and carbonate). The selected hydrogeological terrains characterize ~90% of the landscape based on a simplified geological map of southern Ontario. The main hydrogeological characteristics and behaviour of these terrains are proposed as a set of conceptual models representative of near-surface groundwater regimes. Such models can inform water and land resource management as future climates change. Key words: hydrogeology, southern Ontario, base flow, terrain geology, hydrological monitoring Résumé L'eau souterraine est un élément important du cycle hydrologique du sud de l'Ontario, notamment pour l'approvisionnement en eau et la contribution aux eaux de surface. Afin d'améliorer la compréhension globale de mécanismes hydrologiques importants, un cadre de validation de principe est présenté qui consiste en sept reliefs ou milieux hydrologiques typiques. Des facteurs géologiques et topographiques influencent chaque relief, comme en témoignent des données sur le climat, le débit des cours d'eau et les niveaux d'eau souterraine, qui reflètent l'écoulement de l'eau à travers différentes parties du paysage du sud de l'Ontario. Ce cadre hydrogéologique tient compte de la géologie des sédiments de surface et du roc, de la perméabilité et de la porosité (inférée), de la physiographie et de gradients topographiques pour définir sept types de reliefs hydrogéologiques distincts. Le processus de sélection des données et des bassins versants permet de mettre l'accent sur les motifs de réponse hydrologique à l'échelle du paysage, plutôt que sur la quantification de l'hydrologie du relief. L'analyse fait ressortir des épisodes dans les données climatiques, de débit et de surveillance de puits qui indiquent des influx et des motifs temporels des réactions hydrologiques et hydrogéologiques à la géologie et la topographie locales, distinguant ainsi des styles d'écoulement de l'eau souterraine dans les paysages de sédiments/roc du bassin paléozoïque et de la bordure du bouclier. Une étude de cas est présentée pour chaque milieu, dont cinq dans des sédiments (argile, sable, gravier, crête de till et till épais) et deux dans le roc (cristallin et à carbonates). Les reliefs hydrogéologiques sélectionnés caractérisent ~90% du paysage à la lumière d'une carte géologique simplifiée du sud de l'Ontario. Il est proposé que les principaux comportements et caractéristiques hydrogéologiques de ces reliefs forment un ensemble de modèles conceptuels représentatifs des régimes d'eau souterraine près de la surface. Ces modèles peuvent éclairer la gestion des ressources en eau et en sols dans le contexte des changements climatiques à venir. [Traduit par la Rédaction] Mots-clés : hydrogéologie, sud de l'Ontario, débit de base, géologie des reliefs, surveillance hydrologique, 1. Introduction 1.1. Context In addition to surface water, groundwater is an important component of the hydrological cycle of southern Ontario. It is significant to water supply as it provides [...]

Freshwater mussels (Bivalvia: Unionidae) are the most imperilled taxon in Canada. To facilitate species recovery efforts, an understanding of species distribution and habitat that supports species persistence is needed. Detecting mussels presents unique challenges and requires considerable effort owing to their complex life histories and widespread declines. Here, observations of the imperilled Wavyrayed Lampmussel (Lampsilis fasciola Rafinesque, 1820) from the Grand and Thames rivers, Ontario, Canada, were used to quantify species detection and occupancy probabilities, and the relationship between occupancy probability and substrate size. The best model for the data included a river-specific covariate for detection and an intercept model for occupancy. Detection probability of Wavyrayed Lampmussel was higher in the Grand River than in the Thames River. Limited variation in substrate size measurements restricted occupancy modelling, but field measurements qualitatively aligned with previous habitat descriptions. Overall, knowledge of species detection and occupancy probabilities for Wavyrayed Lampmussel will not only enhance the understanding of species distribution and habitat associations, but also ensure that the response of the species to threats and recovery actions are captured. Les moules d'eau douce (bivalves : unionides) constituent le taxon le plus menace au Canada. Pour faciliter les efforts visant leur retablissement, il est necessaire de comprendre la repartition et les habitats qui supportent la persistance de ces especes. La detection d'unionides presente cependant des defis particuliers qui exigent un effort considerable en raison de leurs cycles biologiques complexes et de leurs vastes declins. Nous utilisons des observations sur une espece en peril, la lampsile fasciolee (Lampsilis fasciola Rafinesque, 1820), dans les rivieres Grand et Thames (Ontario, Canada) afin de quantifier les probabilites de detection et d'occupation de l'espece, ainsi que la relation entre la probabilite d'occupation et la granulometrie du substrat. Le meilleur modele pour les donnees integre une covariable propre a la riviere pour la detection et un modele d'intersection pour l'occupation. La probabilite de detection de lampsiles fasciolees est plus grande pour la riviere Grand que pour la riviere Thames. Le peu de variation des mesures de granulometrie du substrat limite la modelisation de l'occupation, mais les mesures de terrain concordent qualitativement avec des descriptions d'habitat anterieures. En general, la connaissance des probabilites de detection et d'occupation des lampsiles fasciolees va non seulement ameliorer la comprehension de la repartition de l'espece et des associations d'habitat, mais permettra aussi de documenter les reactions de l'espece a des menaces et mesures de retablissement. [Traduit par la Redaction], Introduction The recovery of imperilled freshwater species is unattainable without an understanding of species ecology and the threats limiting population persistence. The extensive list of threats to freshwater biodiversity is [...]

Leeches have a worldwide distribution, yet numerous geographical regions remain to be adequately surveyed. Here, we present leech species records for one of these regions: the far north of Ontario, Canada. This region is primarily wetland habitat and includes two of Ontario's three ecozones. Morphological examinations, as well as a single instance of successful DNA amplification with subsequent molecular identification, allowed us to identify representatives of 12 species from two predatory families (Erpobdellidae and Haemopidae) and one parasitic family (Glossiphoniidae) among samples of 130 individuals. To provide a more inclusive list of species records for this remote region, our data were also augmented by 25 largely unpublished collection records (for 102 individuals) from the Canadian Museum of Nature, which revealed the presence of an additional species. We comment on finds of particular interest in our sampling with comparison to relevant literature and provide new distribution data for these species. Key words: Hirudinea, leeches, northern Ontario, species distribution, specimen records, checklist. Si la repartition des sangsues est planetaire, de nombreuses regions geographiques n'ont pas ete adequatement etudiees. Nous documentons des registres d'especes de sangsues pour une de ces regions, l'extreme-nord de l'Ontario (Canada). Cette region consiste principalement en des habitats de milieu humide et comprend deux des trois ecozones de l'Ontario. Des examens morphologiques et un seul cas reussi d'amplification d'ADN avec identification moleculaire subsequente nous permettent d'identifier des representants de 12 especes de deux familles de sangsues predatrices (erpobdellides et hemopides) et d'une famille de sangsues parasitiques (glossiphoniides) parmi des echantillons de 130 individus. Afin d'en arriver a une liste plus inclusive de registres d'especes pour cette region eloignee, nos donnees ont egalement ete completees par 25 registres de collections (pour 102 individus) principalement non publies du Musee canadien de la nature, qui revelent la presence d'une autre espece. Nous discutons de decouvertes d'interet particulier dans notre echantillonnage au vu de publications pertinentes et presentons de nouvelles donnees relatives a la repartition pour ces especes. [Traduit par la Redaction] Mots-cles : hirudines, sangsues, nord de l'Ontario, repartition des especes, registres de specimens, liste de verification., Introduction Leeches (Annelida: Hirudinea) are a globally distributed, sparsely diverse, but highly abundant group of annelids. They have been recorded from every ocean and every continent, and inhabit freshwater, marine, [...]

Wastewater reclamation is becoming an important alternative for sustainable water resources management and building climate change resiliency in many regions around the world. This research investigated the polishing of secondary effluents and combined sewer overflows (CSOs) by a laboratory-scale soil aquifer treatment considering local soils and wastewater characteristics of southwestern Ontario. Results show that high permeability soils of southwestern Ontario, have the ability to polish secondary effluents in terms of dissolved organic carbon, Escherichia coli, and total coliforms. Regarding the simulated CSOs, low to moderate improvements of wastewater quality were observed. Denitrification of secondary effluents improved significantly by the addition of readily available organic matter, which supports the importance of protecting recharge wetlands for groundwater quality protection. Soil aquifer treatment in southwestern Ontario is a feasible alternative for the recharge of non-potable and potable aquifers with secondary effluents. However, for potable aquifers further treatment of wastewater effluents may be required. Key words: soil aquifer treatment, resiliency, water resources management, wastewater reclamation, sustainability. La recuperation d'eaux usees devient une option importante en matiere de gestion des ressources en eau durable et afin de creer la resilience au changement climatique, et ce, dans de nombreuses regions dans le monde entier. Cette recherche a examine le polissage d'effluents secondaires et du trop-plein des egouts unitaires par un traitement par sol aquifere (<< soil aquifer treatment >>) a l'echelle laboratoire en tenant compte des sols locaux et des caracteristiques des eaux usees du sud-ouest de l'Ontario. Les resultats montrent que les sols de haute permeabilite du sud-ouest de l'Ontario ont la capacite d'epurer les effluents secondaires au niveau du carbone organique dissous, de l'Escherichia coli et des coliformes totaux. Quant aux trop-pleins d'egouts unitaires simules, des ameliorations allant de bas a modere de la qualite des eaux usees ont ete observees. La denitri- fication d'effluents secondaires s'est beaucoup amelioree par l'apport de matiere organique aisement disponible, ce qui soutient l'importance de proteger la recharge des terres humides pour la protection de la qualite de l'eau souterraine. Le traitement par sol aquifere dans sud-ouest de l'Ontario est une option possible pour la recharge des aquiferes non potables et potables avec des effluents secondaires. Cependant, pour des aquiferes potables un traitement supplementaire des effluents des eaux usees peut etre necessaire. [Traduit par la Redaction] Mots-cles : traitement par sol aquifere (<< soil aquifer treatment >>), resilience, gestion des ressources en eau, recuperation des eaux usees, durabilite., Introduction Water resources around the world are under increasing pressure from the rapidly growing demands of rising population and industrialization. Furthermore, changes in global weather patterns are expected to intensify [...]

The plausibility of land disturbance as a cause of declining phosphorus (P) concentrations in oligotrophic lakes within south-central Ontario, Canada, is evaluated using the process-based model INCA-P. The model was calibrated upon three catchments in the Muskoka-Haliburton region (MHR): Harp (HP), Dickie (DE), and Plastic (PC), which have varying degrees of declining P export and different forms of historic disturbances (timber harvesting, tree death, and soil acidification, respectively). Hindcasts (1978-2007) were run with and without simulated disturbances. Model performance of both DE and HP was greatly improved when effects of wetland tree deaths (DE) and harvesting (HP) were included. In PC, with no record of timber harvesting and relatively minor declines in P, initial hindcasts successfully accounted for the majority of interannual P fluxes, and performance was only marginally improved through the simulation of soil acidification. Vegetation decay, harvesting, and catchment acidification accounted for 63%, 24%, and 0.6%, respectively, of P export over the past 30 years. Of all disturbances, wetland vegetation death had the highest impact on areal P exports, indicating that riparian stability is particularly important. La possibility que des perturbations de milieux terrestres soient la cause de baisses de concentrations de P dans des lacs oligotrophes du centre-sud de l'Ontario (Canada) est evaluee a l'aide du modele axe sur les processus INCA-P. Ce modele a ete etalonne sur trois bassins versants dans la region de Muskoka-Haliburton (MHR), ceux de Harp (HP), Dickie (DE) et Plastic (PC), caracterises par differents degres de diminution des exportations de P et differentes formes de perturbations historiques (recolte du bois, mortalite d'arbres et acidification des sols, respectivement). Des previsions a posteriori (1978-2007) ont ete effectuees avec et sans perturbations simulees. La performance du modele pour les bassins DE et HP est bien meilleure quand les effets de la mortalite d'arbres dans les zones humides (DE) et de la recolte (HP) sont inclus. Dans le bassin PC, ou aucune coupe de bois n'a eu lieu et les baisses de P sont relativement faibles, les previsions a posteriori initiales expliquent bien la majorite des flux de P interannuels; la simulation de l'acidification du sol n'ameliore que legerement la performance du modele. La decomposition de la vegetation, l'exploitation forestiere et l'acidification du bassin expliquent 63 %, 24 % et 0,6 %, respectivement, des exportations de P au cours de 30 dernieres annees. De toutes les perturbations, la mortalite de la vegetation de zone humide a eu la plus grande incidence sur les exportations de P en fonction de la superficie, ce qui souligne l'importance de la stabilite des berges. [Traduit par la Redaction], Introduction Phosphorus (P) is an essential nutrient (Sharpley et al. 2013) that can limit aquatic productivity (Jeppesen et al. 2005). In the predominantly oligotrophic lakes of the Precambrian Shield landscape [...]

The issue of calcium (Ca) decline in surface waters of eastern Canada is an emerging concern that may be made worse by timber harvesting. In the Muskoka River Watershed (MRW) in Ontario, the mean lake Ca concentration in 104 lakes decreased by 30% since the 1980s, with the rate of decrease slowing over time consistent with changes in lake sulfate (S[O.sub.4]) as the region recovers from acid deposition. Recent data suggested that smaller lakes, at higher elevation, in smaller catchments with higher runoff that are minimally impacted by the influence of roads and agriculture are associated with lower Ca concentrations and thus are the lakes most at risk of amplified Ca depletion. Using proposed annual allowable harvest cuts from 10-year forest management plans, 38% of 364 lakes assessed in the MRW will fall below a reported critical 1 mg x [L.sup.-1] Ca threshold compared with just 8% in the absence of future harvesting. It is concluded that Ca decline poses a serious threat to aquatic ecosystems and should be taken into consideration in future forest management plans. L'appauvrissement en calcium (Ca) dans les eaux de surface dans l'est du Canada constitue une nouvelle problematique que la recolte du bois pourrait exacerber. Dans le bassin versant de la riviere Muskoka (MRW) en Ontario, la concentration moyenne de Ca dans 104 lacs a diminue de 30% depuis les annees 1980, a un taux decroissant dans le temps, parallelement a une evolution a l'avenant des concentrations de sulfate (S[O.sub.4]) des lacs, alors que la region se remet de la pollution acide. Des donnees recentes donnent fi penser que les plus petits lacs, fi plus haute elevation, dans des bassins versants plus petits et caracterises par un ruissellement plus important sur lesquels les impacts des routes et de l'agriculture sont limites, sont associes a de plus faibles concentrations de Ca et, donc, sont les lacs les plus a risque d'amplification de l'appauvrissement en Ca. En utilisant les possibilites annuelles de coupe tirees de plans d'amenagement forestier decennaux, nous avons determine que 38 % des 364 lacs evalues dans le MRW seront sous le seuil critique de 1 mg x [L.sup.-1] Ca, comparativement a seulement 8 % en l'absence de coupe future. Nous en concluons que l'appauvrissement en Ca constitue une grave menace pour les ecosystemes aquatiques et devrait etre pris en consideration dans les plans d'amenagement forestier futurs. [Traduit par la Redaction], Introduction Anthropogenically induced increases in sulfur (S) deposition has led to declines in soil calcium (Ca) in thin, acid-sensitive, mineral-poor soils in eastern North America (Watmough and Dillon 2003a; Yanai [...]

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 purpose of the paper is to analyse the extent of policy change and learning in the 20 years following the implementation of Ontario's forest sustainability legislation. Extent of policy learning and change towards sustainable forest management are measured using a combination of content, co-occurrence, and textual analysis of the previous Crown Timber Act and the new Crown Forest Sustainability Act, as well as the latter's 1996 and 2009 forest planning manuals. There were four key findings. First, policy change towards sustainable forest management has been limited. Second, although there was an increased number of values mentioned in new legislation and planning manuals, the frequency of timber values remained dominant. Third, although integration occurred among a greater range of values, integration with timber values continued to dominate. Fourth, with respect to policy learning, the achievement of sustainable forest management is now explicit and judged based on evidence regarding the inclusion of a range of values beyond timber. The paper concludes that the transition to the more integrative and responsive policies of sustainable forest management remains a work in progress. Key words: sustainable forest management, changing paradigms, organizations, institutionalization, learning. Cet article a pour but d'analyser l'ampleur du virage et de l'apprentissage politiques 20 ans apres la mise en oeuvre de la loi ontarienne sur la durabilite des forets. L'ampleur de l'apprentissage et du virage politiques vers l'amenagement forestier durable a ete mesuree a l'aide d'une combinaison d'analyses de contenue, de cooccurrences et textuelle de l'ancienne Loi sur le bois de la Couronne et de la nouvelle Loi sur la durabilite des forets de la Couronne ainsi que des manuels de planification forestiere de 1996 et de 2009 decoulant de cette derniere loi. Voici les quatre principales constatations qui se degagent des analyses. Premierement, le virage politique vers l'amenagement forestier durable a ete limite. Deuxiemement, bien qu'un plus grand nombre de valeurs aient ete mentionnees dans la nouvelle loi et les manuels de planification, la frequence des valeurs ligneuses est demeuree dominante. Troisiemement, malgre l'interaction entre un plus large eventail de valeurs, l'integration avec les valeurs ligneuses a continue de dominer. Quatriemement, en ce qui concerne l'apprentissage politique, la realisation de l'amenagement forestier durable est maintenant explicite et evaluee sur la base des preuves d'inclusion d'un eventail de valeurs nonligneuses. La conclusion de cet article est que la transition vers des politiques plus integratives et mieux adaptees d'amenagement forestier durable demeure une demarche inachevee. [Traduit par la Redaction] Mots-cles: amenagement forestier durable, changement de paradigmes, organisations, institutionnalisation, apprentissage., Introduction As more and more Canadians attach greater importance to recreation, tourism, and other noncommodity values of forests (Wetzel et al. 2006) on public (Crown) lands where timber harvesting takes [...]

The exposures at the St. Marys Cement Inc. quarry at St. Marys, Ontario, have been studied by geologists since the mid-1950s. This paper summarizes previous and new information collected in 2009, 2010, and 2012 and discusses the record of sediments resting on the bedrock surface that have been exposed during quarry operations. The exposed sediments illustrate the dynamic behavior of the Laurentide Ice Sheet in this area during the Late Wisconsin. Evidence for subglacial meltwater activity, shifting ice-flow directions during till deposition, a local or regional erosion event, possible subaerial exposure, and ice-marginal sedimentation is observed in the sequence of tills and stratified sediments exposed in the quarries. It also highlights how rapid lateral facies changes, complex contact relationships, and steep erosional contacts can prove to be challenging for correlation and extrapolation of subsurface units into three-dimensional stratigraphic models. Fourteen units were identified of which the lower six were deposited during the Nissouri age (Catfish Creek Drift). This included five layers of till deposited by a glacier that alternated from flowing out of the Lake Huron basin to that of a regional flow to the south-southwest. An angular unconformity cuts into these sediments and separates them from a finer-grained sediment sequence (primarily of Port Bruce age) consisting of glaciofluvial gravel, two fine-textured till layers, and rhythmically bedded glaciolacustrine sediments, all overlain by the uppermost till, the Rannoch Till, and Mitchell Moraine ice-marginal fan sediments. Les geologues etudient les affleurements a la carriere de la St. Marys Cement Inc., a St. Marys en Ontario, depuis le milieu des annees 1950. Le present article resume des donnees deja acquises et de nouvelles informations recueillies durant les annees 2009, 2010 et 2012; il traite du profil geologique des sediments qui reposent sur le socle et qui ont ete exposes durant l'exploitation de la carriere. Les sediments exposes illustrent le comportement dynamique de l'Inlandsis laurentidien dans ce secteur au Wisconsin tardif. Des evidences d'activite d'eau de fonte sous-glaciaire, la variation de la direction de l'ecoulement glaciaire, un evenement d'erosion local ou regional, une possible exposition subaerienne et une sedimentation en bordure de la glace sont observes dans les sequences de tills et de sediments stratifies qui affleurent dans les carrieres. Tous ces points soulignent aussi la maniere dont les changements lateraux rapides de facies, les relations complexes de contact et les contacts d'erosion abrupts peuvent poser des defis pour la correlation et l'extrapolation des unites sous la surface dans des modeles stratigraphiques tridimensionnels. Quatorze unites ont ete identifiees dont six unites inferieures qui ont ete deposees durant le stade glaciaire Nissouri (drift de Catfish Creek). Ces unites comprenaient cinq couches de till deposees par un glacier qui s'ecoulait alternativement entre le bassin Huron et de maniere regionale vers le sud-sud-ouest. Une discordance angulaire recoupe ces sediments et les separe d'une sequence a grains plus fins (surtout d'age Port Bruce) qui est composee de gravier fluvioglaciaire, de deux couches de till a texture fine et de sediments glacio-lacustres a stratification rythmique; le tout est recouvert par le till superieur, le till de Rannoch et des sediments de lobe proglaciaire en bordure de la moraine de Mitchell. [Traduit par la Redaction], Introduction With the onset of three-dimensional (3D) mapping of Quaternary sediments primarily for regional groundwater applications in areas surrounding the Great Lakes by State, Provincial, and Federal surveys, emphasis has [...]

Abstract The community of Goderich, Ontario, devastated by a severe tornado on August 21, 2011, was the focus of this study. Examining the community's capacities and vulnerabilities at different stages [...]

Unraveling the cause(s) of declines in total phosphorus (TP) observed over the past three decades across many forested catchments in central Ontario remains a research priority. The objectives of this paper were firstly to test the assumption that weir water chemistry is representative of catchment changes at two adjacent headwater streams that have shown declines in TP and secondly use long-term measurements of weir water quality (1980-2008) to identify potential drivers of TP declines. Longitudinal measurements confirmed that weir water chemistry is generally representative of the entire stream channel, although channel-associated wetlands have a strong influence on TP. Additionally, processes operating in wetlands dictate seasonal patterns in TP, and differences in wetland cover explain the approximately twofold difference in average TP between the two catchments. Changes in wetland cover or processes, however, cannot explain declines in TP. Rather, declines in TP are most coherent with declines in stream potassium (K) and nitrate (N[O.sub.3]-N), which also occurred over the past 30 years. We suggest that coincident declines in TP, N[O.sub.3]-N, and K may be best explained by recovery from a disturbance event. La comprehension des causes des appauvrissements en phosphore total (TP) observes au cours des trois dernieres decennies dans de nombreux bassins versants forestiers du centre de l'Ontario demeure une priorite de recherche. Les objectifs du present article consistaient d'abord a verifier l'hypothese selon laquelle la chimie de l'eau dans les deversoirs est representative des changements au bassin versant pour deux cours d'eau d'amont adjacents dans lesquels ont ete notees des baisses du TP, puis d'utiliser des mesures de longue duree de la qualite de l'eau dans des deversoirs (1980-2008) pour cerner les causes possibles des baisses de TP. Des mesures longitudinales ont confirme que la chimie de l'eau dans les deversoirs est generalement representative de l'ensemble du chenal du cours d'eau, bien que les milieux humides associes au chenal exercent une forte influence sur le TP, que les processus intervenant dans les milieux humides imposent des variations saisonnieres de TP et que les variations de la couverture des milieux humides expliquent une difference du simple au double entre le TP moyen des deux bassins versants. Les variations de la couverture ou des processus de milieux humides ne peuvent toutefois expliquer les baisses de TP. Ces dernieres concordent plutot avec les baisses des teneurs en potassium (K) et en nitrate (N[O.sub.3]-N) dans les cours d'eau egalement notees au cours des trente dernieres annees. Nous postulons que la meilleure explication pour les baisses coincidentes de TP, N[O.sub.3]-N et K soit le fait que les cours d'eau se remettent d'un evenement perturbateur. [Traduit par la Redaction], Introduction Total phosphorus (TP) concentrations in streams are typically low (i.e., Surprisingly, despite already low P levels and a general trend toward increasing shoreline development around many lakes (e.g., by [...]

With the effect of global climate change the rainfall intensity is changing, and in many places it is drastically increasing. The use of intensity-duration-frequency (IDF) curves based on historic rainfall data might, therefore, underestimate the risk associated with the design and assessment of drainage systems. The theoretical probability distribution function used in the establishment of IDF curves based on historical observations might need to be different for the future conditions. The Gumbel (EV1) distribution is the currently recommended distribution for use in Canada and the EV1 and the Log-Pearson type 3 (LP3) are routinely used in the US. This study investigates potential utility of the generalized extreme value (GEV) distribution for use in climate change impact studies by the City of London that is located in the Upper Thames River Basin. All results point that GEV seems to be the best choice for the use with the Upper Thames River Basin data. We would like to use results of this study and open the discussion on the choice of most appropriate distribution for the development of IDF curves under changing climate conditions in Canada. Key words: IDF curve, climate change, extreme value modeling. L'intensite des precipitations change sous l'effet des changements climatiques et, dans plusieurs endroits, elle augmente de maniere importante. L'utilisation des courbes intensite-duree-frequence (IDF) basees sur les donnees historiques de precipitation peuvent donc sous-estimer le risque associe a la conception et a l'evaluation des systemes de drainage. La fonction de distribution theorique des probabilites, utilisee pour etablir les courbes IDF basees sur les observations historiques, pourrait devoir etre modifiee pour les conditions a venir. L'utilisation de la distribution de Gumbel (EV1) est presentement recommandee au Canada et la EV1 et l'equation Log-Pearson de type 3 (LP3) sont couramment utilisees aux Etats-Unis. La presente etude examine l'utilite potentielle de la distribution GEV (valeur extreme generalisee) dans les etudes d'impact des changements climatiques de la Ville de Londres, situee dans le bassin superieur de la Thames. Tous les resultats indiquent que la GEV semble etre le meilleur choix pour etre utilise avec les donnees du bassin superieur de la Thames. Nous aimerions utiliser les resultats de cette etude et ouvrir une discussion sur le choix de la distribution la plus adequate pour le developpement de courbes IDF pour les conditions climatiques changeantes au Canada. [Traduit par la Redaction] Mots-cles: courbe IDF, changement climatique, modelisation de la valeur extreme., 1. Introduction The estimation of rainfall intensity for various durations and frequency, referred to as intensity-duration-frequency (IDF) curve, is needed when analyzing hydrologic risk. In the estimation of IDF curve, [...]

This paper explores the question of whether people involved with a successful watershed policy initiative embraced and/or negated the complexity with which they worked. The setting was Lake Simcoe, in central Canada: an area important for fisheries, agriculture, tourism, recreation and citizens' identities. Human activities had impacted water quality, and planned development posed further threats. Although government had supported considerable scientific data collection, citizens became frustrated by what they saw as a lack of regulatory and enforcement work. Citizens embarked on a range of creative pressure tactics for change. In early stages, citizens felt marginalized, but over time they were included in increasingly meaningful ways. This paper explores several complex system themes in interview transcripts, including initial starting conditions, attractors, and boundaries. A key finding is that citizens used scientific data as an attractor to enable their inclusion for a more complex range of agendas and benefits., Introduction This paper presents a successful policy initiative called the Lake Simcoe Protection Plan, intended to protect the Lake Simcoe watershed in Ontario, Canada. Using complexity theory lenses, it explores [...]

There is a crucial need to understand the genetic consequences of landscape modifications on continuous populations that could become fragmented, and to evaluate the degree of differentiation of isolated populations that were historically part of the core. Using 15 microsatellite loci, we evaluated the genetic structure of American black bears (Ursus americanus Pallas, 1780) across a vast, contiguous Ontario landscape (>1 x [10.sup.6] [km.sup.2]) that largely represents their pre-European settlement distribution. Because geographic barriers are absent, we predicted that isolation by distance would drive genetic structure. We identified three genetic clusters (Northwest, Southeast, and Bruce Peninsula) that were less differentiated than when assessed with mtDNA, suggesting the influence of male-biased dispersal on large-scale genetic differentiation. Isolation by distance (r = 0.552, P = 0.001) was supported by a weak, clinal variation between Northwest and Southeast, illustrating the challenges to delineate populations in wide-ranging taxa. The Bruce Peninsula cluster, confined to a small area under strong anthropogenic pressures, was more differentiated from neighbouring clusters (FST > 0.13, P < 0.0001), with a genetic diversity corresponding to disjunct populations of black bears. Our results could be used in landscape genetics models to project the evolution of population differentiation based on upcoming landscape modifications in northern regions of North America. Key words: American black bear (Ursus americanus), cluster, gene flow, genetic structure, isolation by distance, male- biased dispersal, microsatellite, North America, spatial autocorrelation. La comprehension des consequences genetiques des changements environnementaux pour les populations continues qui pourraient devenir fragmentees est d'une importance cruciale, tout comme l'evaluation du degre de differentiation des populations historiquement centrales. Grace a 15 microsatellites, nous avons evalue la structure genetique de l'ours noir (Ursus americanus Pallas, 1780) dans un vaste paysage contigu (>1 x [10.sup.6] [km.sup.2]) en Ontario representant en bonne partie l'aire de repartition de l'espece avant l'arrivee des Europeens. Etant donne l'absence de barrieres geographiques, nous anticipions que l'isolement par la distance influencerait la structure genetique. Nous avons identifie trois groupes genetiques (nord-ouest, sud-est et peninsule de Bruce) qui presentaient une differentiation moins importante que celle etablie par analyse d'ADN mitochondrial, suggerant un effet de la dispersion des males sur la differentiation genetique a grande echelle. L'isolement par la distance (r = 0,552, P = 0,001) a ete confirme par la variation genetique clinale entre les groupes du nord-ouest et du sud-est, illustrant les difficultes liees a la delimitation de populations de taxons a grande aire de repartition. Le groupe de la peninsule de Bruce, confine a une petite region assujettie a de fortes pressions anthropiques, etait plus differencie des groupes voisins (FST > 0,13, P < 0,0001), sa diversite genetique correspondant a celle de populations d'ours noirs isolees. Nos resultats pourraient etre utilizes dans les modeles de genetique du paysage afin de prevoir l'evolution de la differentiation des populations en fonction des futurs changements environnementaux dans les regions nordiques de l'Amerique du Nord. Mots-cles : ours noir (Ursus americanus), flux genetique, structure genetique, isolement par la distance, dispersion des males, microsatellite, Amerique du Nord, autocorrelation spatiale., Introduction Over the last 500 years, many species have experienced range contractions and demographic declines as a consequence of habitat loss and landscape fragmentation (Laliberte and Ripple 2004; Wiegand et [...]

Predicting the effect of climate change on insect populations is critical to improve the reliability of forest management plans, wood supply projections, and pest protection programs. In this study, we use an empirical model to relate the spatial distribution of past defoliation by spruce budworm (Choristoneura fumiferana Clem.) in Ontario to bioclimatic variables. We then apply data from six climate change scenarios to this model to project potential changes in the distribution of defoliation for 2011-2040. The spatial distribution of historical defoliation was found to be related to winter maximum and minimum temperatures, forest content in balsam fir (Abies balsamea (L.) Mill.) and white spruce (Picea glauca (Moench) Voss), and spring and summer minimum temperatures. All six climate change scenarios project broadly similar changes in the spatial patterns of defoliation: (i) an extension of the northern limit of defoliation as far as available data go or close to it, (ii) a decrease in the frequency of defoliation in the center of the historical defoliation belt, and (iii) a persistence of the southern limit of defoliation. This leads to a projected increase of the total area defoliated of between 22.8% and 25.5%, while the mean frequency of defoliation, calculated over the whole study area, would slightly increase (+1%) or decrease (- 17.7% to -2.9%). Il est crucial de prevoir l'effet des changements climatiques sur les populations d'insectes pour ameliorer la fiabilite des plans d'amenagement forestier, des previsions des stocks de bois et des programmes de protection contre les ravageurs. Dans cette etude, nous utilisons un modele empirique pour relier la distribution spatiale des defoliations passees causees par la tordeuse des bourgeons de l'epinette (Choristoneura fumiferana Clem.) en Ontario aux variables bioclimatiques. Nous appliquons ensuite les donnees provenant de six scenarios de changement climatique a ce modele pour predire les changements potentiels dans la distribution de la defoliation de 2011 a 2040. Les resultats indiquent que la distribution des defoliations passees etait reliee aux temperatures hivernales minimum et maximum, a la quantite de sapin baumier (Abies balsamea (L.) Mill.) et d'epinette blanche (Picea glauca (Moench) Voss) que contient la foret et aux temperatures minimum au printemps et a l'ete. Les six scenarios de changement climatique prevoient des changements largement similaires dans les patrons de defoliation: (i) une extension de la limite septentrionale de la defoliation aussi loin ou presque que les donnees disponibles permettent d'aller, (ii) une diminution de la frequence des defoliations dans le centre du couloir traditionnel de defoliation et (iii) la persistance de la limite meridionale de la defoliation. Cela mene a une augmentation prevue de la superficie totale defoliee de 22,8 % a 25,5 %, tandis que la frequence moyenne des defoliations, calculee sur l'ensemble de l'aire d'etude, augmenterait legerement (+1 %) ou diminuerait (-17,7 % a -2,9 %). [Traduit par la Redaction], Introduction It is commonly recognized that climate change will affect boreal forest ecosystems through changes in disturbance regimes (Stocks 1991; Price and Apps 1995; Fleming and Candau 1998). This association [...]

The long-term monitoring of eight lakes near Dorset, Ontario, indicates that the water quality has changed significantly over the last 30 years. However, trends in the Dorset lakes may not be representative of changes in other south-central Ontario lakes, as the Dorset lakes are within a small area and span a limited gradient of lake and watershed characteristics. To determine the regional extent of water quality changes, we assessed the chemical changes in 36 diverse lakes that were first sampled between 1981 and 1990 and were resampled in 2004-2005. Similar to trends in the Dorset lakes, changes in the regional lakes included decreasing acidity, calcium, conductivity, metals, and phosphorus, and increasing dissolved organic carbon, nitrogen, sodium, and chloride. Water quality changes were driven by regional stressors, including acidic deposition, climate, and lakeshore residential development. However, stressor-induced responses differed among lakes. Increases in sodium and chloride were greater in developed lakes that were close to winter-maintained roads. Site-specific characteristics, such as lake and watershed morphometry, could not explain heterogeneous changes in the remaining water quality parameters. These results indicate that other factors play an important role in regulating individual lake response to regional stressors. La surveillance a long terme de huit lacs pres de Dorset, Ontario, Canada, revele que la qualite de l'eau a change significativement au cours des 30 dernieres annees. Cependant, les tendances observees dans les lacs de Dorset peuvent ne pas etre representatives du changement dans d'autres lacs du centre-sud de l'Ontario, parce que les lacs de Dorset se situent dans une region restreinte et couvrent un gradient limite de caracteristiques de lacs et de bassins versants. Afin de determiner l' etendue regionale des changements dans la qualite de l' eau, nous avons evalue les changements chimiques dans 36 lacs diversifies, echantillonnes d'abord entre 1981 et 1990, puis de nouveau en 2004-2005. Comme dans les tendances observees dans les lacs de Dorset, le changement dans les lacs de la region incluent une diminution de l' acidite, du calcium, de la conductivite, des metaux et du phosphore et une augmentation du carbone organique dissous, de l'azote, du sodium et du chlorure. Les changements dans la qualite de l' eau s' expliquent par les facteurs de stress regionaux, en particulier les precipitations acides, le climat et le developpement residentiel en bordure des lacs. Cependant, les reactions aux facteurs de stress ne sont pas les memes dans tous les lacs. L' augmentation du sodium et du chlorure est plus importante dans les lacs developpes situes pres de routes entretenues en hiver. Les caracteristiques specifiques aux sites, telles que la morphometrie du lac et du bassin versant, ne peuvent pas expliquer les changements heterogenes dans les autres variables de la qualite de l'eau. Nos resultats indiquent que d'autres facteurs jouent un role important dans le controle des reactions des lacs individuels aux facteurs de stress regionaux. [Traduit par la Redaction], Introduction Among Canada's most abundant natural resources are its over 3 million lakes covering 7.6% of the country's surface area (Environment Canada 2007). The ecological, financial, aesthetic, and public health [...]

The Parry Sound domain is a granulite nappestack transported cratonward during reactivation of the ductile lower and middle crust in the late convergence of the Mesoproterozoic Grenville orogeny. Field observations suggest the following with respect to the ductile sheath: (1) Formation of a carapace of transposed amphibolite facies gneiss derived from and enveloping the western extremity of the Parry Sound domain and separating it from high-strain gneiss of adjacent allochthons. This ductile sheath formed dynamically around the moving granulite nappe through the development of systems of progressively linked shear zones. (2) Transposition initiated by hydration (amphibolization) of granulite facies gneiss by introduction of fluid along cracks accompanying pegmatite emplacement. Shear zones nucleated along pegmatite margins and subsequently linked and rotated. The source of the pegmatites was most likely subjacent migmatitic and pegmatite-rich units or units over which Parry Sound domain was transported. Comparison of gneisses of the ductile sheath with high-strain layered gneiss of adjacent allochthons show the mode of transposition of penetratively layered gneiss depended on whether or not the gneiss protoliths were amphibolite or granulite facies tectonites before initiation of transposition, resulting in, e.g., folding before shearing, no folding before shearing, respectively. Meter-scale truncation along high-strain gradients at the margins of both types of transposition-related shear zones observed within and marginal to Parry Sound domain mimic features at kilometer scales, implying that apparent truncation by transposition originating in a manner similar to the ductile sheath may be a common feature of deep crustal ductile reworking. doi: 10.1029/2009TC002537.

In the Central Gneiss Belt of the Grenville Orogen (Ontario), ca. 1020 Ma, extensional shearing, disharmonic buckle folding, and seismic faulting at middle to upper crustal levels affected the geological structure of pre-1040 Ma, ductile-thrust sheets. Because much of the repeated in situ deformation was mechanically discontinuous, the present contacts between thrust sheets may not coincide at all localities with the original thrust surfaces. We focused special attention on the basal contact of the Parry Sound domain, whose synformal structure may have resulted from gravitational subsidence of its dense rocks immediately after ductile thrusting. East of Wahwashkesh Lake, a transverse gradient of total strain is absent on horizontal scales of 100-1000 m in lithologically uniform granite gneiss comprising the uppermost western footwall of the northern Parry Sound domain. This contrasts with the steep transverse-strain gradients documented by others, on the same scale, in the wall rocks of Phanerozoic ductile thrusts. We hypothesize that ductile or brittle extension faulting may have removed a 10-20 km long sole-thrust segment at the western flank of the northern Parry Sound domain, together with severely strained rocks of the original uppermost footwall, from the level of the current erosion surface. Within the Parry Sound domain, by contrast, most if not all of the original footwall of the 1160 Ma Mill Lake thrust seems to be preserved at the presently exposed contact surface between the allochthonous basal and interior Parry Sound assemblages. Dans la Ceinture centrale gneissique de l'orogene de Grenville (Ontario), un cisaillement d'extension, un plissement par flambage disharmonique et des failles causees par des seismes dans les niveaux moyens a superieurs de la croute a ~1020 Ma ont perturbe la structure geologique des nappes de charriage ductile pre-1040 Ma. Une grande partie de la deformation in-situ etant mecaniquement discontinue, les contacts actuels entre les nappes de charriage pourraient ne pas coincider a toutes les localites avec les surfaces originales de charriage. Nous avons porte une attention particuliere au contact a la base du domaine de Parry Sound, dont la structure synforme decoulerait possiblement d'une subsidence par gravite de ses roches denses immediatement apres le charriage ductile. A l'est du lac Wahwashkesh, un gradient transversal de la deformation interne totale est absent a des echelles horizontales de 100-1000 m dans des gneiss granitiques a lithologie uniforme qui comprennent la partie superieure de l'eponte inferieure ouest du domaine Parry Sound septentrional. Cela differe des gradients abrupts transverses documentes par d'autres auteurs, a la meme echelle, dans les epontes superieures des charriages ductiles du Phanerozoique. Selon nous, les failles d'extension ductiles ou cassantes pourraient avoir retire un segment de charriage de la semelle d'une longueur de 10 a 20 km au flanc ouest du domaine Parry Sound septentrional, de concert avec des roches fortement deformees de la partie superieure de l'eponte inferieure originale, a partir du niveau de la presente surface d'erosion. A l'interieur du domaine de Parry Sound, par contre. la plus grande partie, sinon toute l'eponte inferieure originale du charriage Mill Lake, 1160 Ma, semble etre preservee au contact, maintenant affleurant, entre l'assemblage de base allochtone et l'assemblage interieur Parry Sound. [Traduit par la Redaction], Introduction 'Field work is not always a fashionable geological activity, but it remains the lifeblood of earth science. It is the only sound way of discovering reality, making observations which [...]

Surface water samples were collected from 43 streams distributed throughout watersheds of mixed land use in southern Ontario, Canada. Absorbance and fluorescence spectroscopy with parallel factor analysis (PARAFAC) was used to characterize dissolved organic matter (DOM). DOM characteristics were related to environmental variables, microbial activity indicators (bacterial production and extracellular leucine aminopeptidase activity), and riparian land use to understand better how these factors influence DOM in streams. PARAFAC produced a six-component model (C1 to C6). Temperature correlated with each PARAFAC component, suggesting that water source, drainage area, and light penetration broadly affected DOM characteristics. C1 and C2 represented terrestrial, humic-like DOM fluorophore groups and comprised 41-65% of stream DOM fluorescence. C5, a tryptophan-like component, related negatively to a humification index but positively to leucine-aminopeptidase activity and recently produced DOM, suggesting that C5 consisted of autochthonous, microbially produced DOM. C3, C4, and C6 showed signs of quinone-like, humic-like, and microbial transformable fluorophores. The distribution of these potentially redox-active PARAFAC components indicated that DOM was in a more reduced state in streams with higher bacterial production and agricultural land use than in streams with increased wetlands area, which had greater relative abundance of the oxidized quinone-like component. Anthropogenic land use and microbial activity altered the quantity and quality of DOM exported from human-affected streams from that observed in forest- and wetland-dominated streams. DOM in agriculturally affected streams was likely more labile and accessible to the microbial community than DOM in wetland streams, which supported low rates of microbial activity. doi: 10.4319/lo.2010.55.3.1159

We examined the dispersal of larvae (glochidia) of a common unionid mussel species, Actinonaias ligamentina, which need to attach to a host fish in order to develop into juveniles, in a lowland river (Sydenham River, Ontario, Canada). Generally, the decline in the number of glochidia captured with distance from release was best described by an inverse power function. The highest proportion was found in the first net 4 m downstream (range 0.1-3.6%), but a small proportion of glochidia was captured 96 m downstream (0-0.03%). This indicates that infestation of host fish may occur several tens to hundreds of meters downstream of the adults' location, even at relatively low flow conditions (mean velocity, 15 cm [s.sup.-1]). Dispersal distances increased with velocity, but the number of glochidia sampled at a given location can vary considerably due to stochastic effects of turbulence, especially at shorter distances. Individual trials could, therefore, deviate considerably from the predictions of an existing turbulent transport model (local exchange model), but overall there was a good correlation between measured data and model prediction. However, model predictions were quantitatively much higher than measured values (i.e., > 50 fold in some cases), which could be in part due to several simplifying assumptions of the model.

Detailed mapping of a portion of the North Spirit Lake greenstone belt reveals a basal basaltic volcanic unit (ca. 3 Ga) with a komatiitic component and strong major and trace element geochemical affinity with typical mid-ocean ridge basalts (e.g., N-MORB). The overlying transitional unit includes basaltic tufts, which have close geochemical affinity to the underlying basalts, and to N-MORB. Interbedded with and overlying the tufts is a thin, laterally continuous sulfide-rich unit with chert interbeds, which is in turn over-lain by interbedded carbonate, chert, and iron-rich sedimentary rocks. The chemical sedimentary rocks of the transitional unit display rare-earth element (REE) patterns and positive Eu anomalies consistent with derivation from fluids associated with submarine hydrothermai vent fields. The sulfide unit is interpreted to represent proximal hydrothermal vent deposits derived from black smoker activity near a spreading center. The overlying carbonate and chert mounds and beds are interpreted as hydrothermal deposits formed at lower temperatures in a more distal setting relative to the spreading center. The carbonate deposits may have formed in an environment analogous to that of the Lost City hydrothermai field (Kelley et al., 2001), where abundant chimneys, dendrites, and beds of carbonate are produced ~15 km from the mid-Atlantic rift axis. The basal volcanic unit consequently is interpreted as ocean-floor basalts formed at an Archean spreading center, with the basaltic tufts representing the last volcanic emanations, and with the chemical sediments representing hydrothermalvents deposits both proximal and distal to the spreading center. The capping siliciclastic unit likely is part of an accretionary wedge, possibly representing ocean closure after a protracted seafloor speading episode. The sedimentary rocks were derived in part, from a weathered tonalite-trondhjemite-granodiorite source. The supracrustal rocks of the North Spirit Lake greenstone belt provide an unusually clear window into some tectonic activity on the primitive Earth, including evidence for the existence of ocean-floor basalts, proximal and distal hydrothermal activity, and possibly a protracted cycle of ocean opening and destruction.

Beginning in the late 1980s with the release of Our Common Future by the World Commission on Environment and Development, followed by the development of international accords such as the 1992 Convention on Biological Diversity, international pressure to resolve Indigenous rights issues has been steadily mounting. Successive Canadian governments have been striving increasingly to recognize and incorporate Aboriginal traditional knowledge into resource management planning. Following more than a decade of such efforts, the question of how to achieve such incorporation appropriately remains inadequately answered. This essay contributes to the resolution of this issue by first clarifying some key differences between Aboriginal and non-Aboriginal definitions of 'traditional knowledge.' Then, three Ontario case studies are briefly described that highlight the most and least successfu] aspects of previous undertakings. Among the lessons learned are the need to value traditional knowledge on a par with Western science while recognizing the particular capabilities of each system, and the requirement that Aboriginal peoples and their knowledge participate on a mutually respectful basis. Avec la publication vers la fin des annees 1980 du rapport Notre avenir a tous de la Commission mondiale sur l'environnement et le developpement (1987), suivie par l'elaboration d'ententes internationales, comme la Convention sur la diversite biologique (1992), des pressions internationales encourageant la resolution des problemes associes aux droits des Autochtones se firent de plus en plus sentir. Des gouvernements canadiens successifs essaient toujours plus de reconnaitre et d'integrer les connaissances traditionnelles autochtones dans la planification de la gestion des ressources. Apres plus de dix ans d'efforts de ce genre, la facon de realiser adequatement une telle integration n'est toujours pas claire. Cet article contribue a la resolution de ce probleme en precisant d'abord certaines differences cles entre les definitions autochtones et non autochtones de << connaissances traditionnelles >>. Trois etudes de cas ontariennes sont ensuite decrites brievement pour illustrer les aspects les mieux reussis et les moins bien reussis des efforts anterieurs. Parmi les lecons apprises, notons le besoin d'accorder la meme valeur aux connaissances traditionnelles qu'aux connaissances scientifiques occidentales tout en reconnaissant les capacites particulieres de chaque systeme, ainsi que l'obligation pour les Autochtones et leurs connaissances d'etre acceptes avec un respect mutuel.

During the last two decades (1979-2002), there has been an ever-increasing frequency of summer severe-rainfall events over Ontario, Canada. This observed upward trend is robust as demonstrated through the Mann--Kendall test with consideration of removing a lag-1 autoregressive process. It is shown through composite analyses using the NCEP reanalysis data that in the presence of warming conditions the summer severe-rainfall events occur more frequently over Ontario, especially under atmospheric conditions with stronger low-level cyclonic circulations and more precipitable water. Further analyses indicate that over north and central Ontario the summer severe-rainfall frequency is linked with a positive trend of precipitable water whereas over central and south Ontario there is a strong interannual response of summer severe-rainfall frequency to the changes in precipitable water through the variations of air temperature.

There are pronounced differences in the processes that act to determine the type and amount of standing and downed coarse woody debris present under partial harvesting versus other noncatastrophic disturbances. To evaluate long-term differences in snag and downed woody debris (DWD) dynamics, we developed a simulation model to project snag density and DWD volume by size and decay class in white pine (Pinus strobus L.) and red pine (Pinus resinosa Ait.) dominated stands under (i) a high-retention shelterwood system, (ii) periodic surface fire, and (iii) fire suppression. Snag densities under a high-retention shelterwood system were consistently lower than those in the fire-suppression and surface-fire scenarios, even if no large snags were felled at the time of harvest. Regular inputs from harvest residues were important in maintaining the total volume of DWD, but this material tended to be concentrated in a narrow range of decay classes at any given time. Preserving existing DWD at harvest was less influential than the level of inputs from harvest residues. Active measures for snag creation and staggering of harvest stages among adjacent stands may help minimize differences in the overall supply and temporal variation of coarse woody debris between managed and both naturally disturbed and old-growth stands. Il y a des differences prononcees entre les processus qui jouent un role dans la determination du type et de la quantite de debris ligneux grossiers sur pied et au sol a la suite de coupes partielles par opposition a d'autres perturbations non catastrophiques. Pour evaluer les differences a long terme de la dynamique des chicots et des debris ligneux au sol (DLS), nous avons mis au point un modele de simulation pour predire la densite des chicots et le volume de DLS par classes de taille et de decomposition dans des peuplements domines par les pins blanc et rouge (Pinus strobus L. et Pinus resinosa Ait.) et soumis a (i) un systeme de coupe progressive a forte retention, (ii) des feux de surface periodiques et (iii) un programme de lutte contre le feu. Avec un systeme de coupe progressive a forte retention, la densite des chicots etait invariablement plus faible que celles associees aux scenarios de feux de surface ou de lutte contre le feu, meme si aucun gros chicot n'a ete abattu lors de la coupe. Les apports reguliers de residus de coupe etaient importants pour maintenir le volume total de DLS, mais ce materiel avait tendance a etre concentre dans un nombre reduit de classes de decomposition. La preservation des DLS presents au moment de la coupe avait moins d'impact que les apports de DLS provenant des residus de coupe. Des mesures actives de creation de chicots et d'etalement des stades de coupe entre peuplements adjacents pourraient aider a minimiser les differences de quantite totale et de variation temporelle entre les debris ligneux grossiers des forets amenagees et ceux des vieilles forets ou des forets naturellement perturbees. [Traduit par la Redaction], Introduction In recent years, proponents of ecosystem-based forest management have advocated that managed stands should retain elements of complex stand structure, including live residual trees, dead wood legacies, and advanced [...]

Abstract This paper reports on a pilot project exploring the impacts of climate change on maple syrup production in understudied near north, Ontario spaces. Maple syrup is produced by settler, [...]

Thousands of lakes around Sudbury, in northeastern Ontario, Canada, were badly damaged by acid deposition and many were also metal-contaminated. Large reductions in atmospheric sulphur and metal emissions have led to widespread chemical improvements in these lakes, and recovery has been documented for various biota. These findings were very important in establishing the necessity and value of sulphur emission controls during the international debates about the effects of acid deposition and the need for cleaner air. Studies of northeastern Ontario lakes are continuing to advance our understanding of chemical and biological recovery processes; however, that knowledge is still incomplete. It has become apparent that the recovery of lakes from acidification is closely linked with the responses to, and interactions with, other large-scale environmental stressors like climate change and calcium declines. Developing a better understanding of lake recovery processes and their future outcomes within such a multiple stressor context will be difficult. It will demand the merging of various approaches, including monitoring, experimentation, paleolimnology, and modelling, and will require effective collaboration among different research and monitoring sites and various agencies and institutions engaged in environmental science. Des milliers de lacs des environs de Sudbury, dans le nord-est de l'Ontario, Canada, ont ete lourdement endommages par les depots acides et plusieurs ont ete aussi contamines par des metaux. Les reductions importantes des emissions atmospheriques de soufre et de metaux ont conduit a une amelioration generale de la chimie de ces lacs et on a demontre le retablissement de divers organismes. Ces resultats ont ete de grande importance pour etablir la necessite et l'importance du controle des emissions de soufre lors des debats internationaux sur les effets des depots acides et la necessite d'air plus pur. Les etudes faites sur les lacs du nord-est de l'Ontario continuent a faire progresser notre comprehension des processus de retablissement chimique et biologique; ces connaissances demeurent cependant encore incompletes. Il est devenu evident que la recuperation des lacs de l'acidification est reliee etroitement a leurs reactions aux autres sources de stress a grande echelle dans l'environnement, tels que le changement climatique et le declin du calcium, ainsi qu'a leurs interactions avec ces sources. Il sera difficile d'obtenir une meilleure comprehension des processus de recuperation des lacs et de leur destin futur dans un tel contexte de sources multiples de stress. Cela necessitera la conjonction de plusieurs approches dont la surveillance continue, l'experimentation, la paleolimnologie et la modelisation; il faudra aussi une coordination effective entre les divers sites de recherche et de surveillance, ainsi qu'une collaboration des differentes agences et institutions impliquees dans les sciences de l'environnement. [Traduit par la Redaction], Introduction During the 1980s, the acidification of lakes by acid deposition emerged as a major international concern (e.g., Cowling 1982), although acid rain effects on lakes had been identified much [...]

Knowledge of postfire residuals in boreal forest landscapes is increasingly important for ecological applications and forest management. While many studies provide useful insight, knowledge of stand-scale postfire residual occurrence and variability remains fragmented and untested as formal hypotheses. We examined the spatial variability of stand-scale postfire residuals in boreal forests and tested hypotheses of their spatial associations. Based on the literature, we hypothesized that preburn forest cover characteristics, site conditions, proximity to water and fire edge, and local fire intensity influence the spatial variability of postfire residuals. To test these hypotheses, we studied live-tree and snag residuals in 11 boreal Ontario forest fires, using 660 sample points based on high resolution photography (1:408) captured immediately after the fires. The abundance of residuals varied considerably within and among these fires, precluding attempts to generalize estimates. Based on a linear mixed-effects model, our data did not support the hypotheses that preburn forest cover characteristics, site conditions, and proximity to water significantly affect the spatial variability of stand-scale residuals. The results do indicate, however, that stand-scale residual variability is associated with local fire intensity (strongly) and distance to fire edge (weakly). La connaissance des residus apres feu dans les paysages forestiers boreaux prend de plus en plus d'importance pour les applications ecologiques et l'amenagement forestier. Meme si plusieurs etudes fournissent des renseignements utiles, la connaissance de la presence et de la variabilite des residus apres feu a (echelle du peuplement demeure fragmentee et n'a pas ete testees sous forme d'hypotheses formelles. Nous avons etudie la variabilite spatiale des residus apres feu a (echelle du peuplement en foret boreale et nous avons teste des hypotheses reliees a leurs relations spatiales. S'appuyant sur la litterature, nous avons pose l'hypothese que la variabilite spatiale des residus apres feu est influencee par les caracteristiques du couvert anterieur au feu, les conditions de la station, la proximite de Peau et de la limite du feu, et l'intensite locale du feu. Pour tester ces hypotheses, nous avons etudie les arbres vivants et les chicots residuels a la suite de feux survenus dans 11 peuplements boreaux de l'Ontario a l'aide des photographies a haute resolution (1 : 408) de 660 points d'echantillonnage prises immediatement apres le feu. L'abondance des residus variait considerablement a l'interieur et entre les feux, excluant toute tentative de generaliser les estimations. En se basant sur un modele lineaire a effets mixtes, nos donnees n'ont pas confirme les hypotheses selon lesquelles les caracteristiques du couvert anterieur au feu, les conditions de la station et la proximite de l'eau influencent la variabilite spatiale des residus a l'echelle du peuplement. Cependant, les resultats indiquent que la variabilite residuelle a l'echelle du peuplement est associee a l'intensite locale du feu (lien fort) et a la distance de la limite du feu (lien faible). [Traduit par la Redaction], Introduction Forest fires are frequent in boreal North America, burning over 7 x [10.sup.-6] ha annually in Canada alone (Van Wagner 1988), and are considered a major cause of forest [...]

Salamanders have been identified as potential indicators of sustainable forest management in boreal Ontario, Canada. However, little information is available on their distribution, abundance, and habitat associations within the boreal forests on which to base a monitoring program. We surveyed salamanders near White River, Ontario, and related their distribution to climate and vegetation information and to habitat suitability models currently used for forest planning within the region. Primarily red-backed salamanders (Plethodon cinereus Green) and blue-spotted salamanders (Ambystoma laterale Hallowell) were recorded, although both were observed in low numbers and captures varied spatially and temporally. Capture rates were 3-7 times lower for P. cinereus than has been reported elsewhere. Trend monitoring will be expensive and have low power to detect significant declines over moderate time frames unless capture rates can be doubled and within-site variability in capture rates halved. We found few strong habitat relationships using either coverboard or pitfall trap data. Plethodon cinereus was negatively correlated with the volume of downed wood, which has been noted in other regions and may be an artefact of the coverboard survey technique. Further focused studies in the boreal forest are required to support the use of both habitat supply models and trend analysis to monitor salamander populations. Les salamandres ont ete considerees comme indicateurs potentiels d'un amenagement forestier durable dans la region boreale ontarienne, au Canada. Cependant, peu de donnees pouvant servir de base a un programme de suivi concernant leur distribution, leur abondance et leur association a des habitats dans les forets boreales sont disponibles. Nous avons inventorie les salamandres pres de White River, en Ontario, et relie leur distribution aux donnees sur le climat et la vegetation ainsi qu'aux modeles de qualite de l'habitat actuellement utilises pour la planification forestiere dans la region. La salamandre cendree (Plethodon cinereus Green) et la salamandre a points bleus (Ambystoma laterale Hallowell) ont ete le plus souvent observees bien que les deux salamandres aient ete observees en petit nombre et que les captures aient variees dans le temps et dans l'espace. Les taux de capture de P. cinereus etaient 3-7 fois plus faibles que ceux qui ont ete rapportes ailleurs. La surveillance des tendances sera onereuse et aura une faible capacite de detecter des diminutions significatives sur des periodes de temps raisonnables a moins que les taux de capture puissent etre doubles et que la variation intra-site des taux de capture puisse etre reduite de moitie. Nous avons observe peu de relations etroites avec l'habitat en utilisant les donnees des pieges sous des planches de bois ou des pieges a fosse. Plethodon cinereus etait negativement correle avec le volume de debris ligneux au sol, ce qui a ete observe dans d'autres regions et est peut-etre un artefact de la technique d'echantillonnage avec des pieges sous des planches de bois. D'autres etudes bien ciblees en foret boreale sont necessaires pour supporter l'utilisation des modeles d'indice de qualite de l'habitat et de l'analyse des tendances pour le suivi des populations de salamandres. [Traduit par la Redaction], Introduction There is increasing social and legal pressure to manage forests in a sustainable manner and to be able to measure progress towards this goal (Statutes of Ontario 2001). However, [...]

Science-based approaches for selecting among single-species, community-, and ecosystem-based recovery plans are needed to conserve imperilled species. Selection of recovery plans has often been based on past success rates with other taxa and systems or on economic cost, but less on the ecology of the system in question. We developed a framework for selecting a recovery plan based on the distributions and ecology of imperilled and nonimperilled species across available habitat types and applied it to fishes in the Sydenham River, Ontario, Canada. We first tested whether distributions of fishes were adequately predicted by habitat features hypothesized to limit the distributions of imperilled fishes versus a broader set of habitat features known to predict fish distributions. We then tested whether imperilled species occurred in similar or disparate habitat types. For the Sydenham River, an ecosystem-based recovery plan was deemed most appropriate because imperilled species occur in disparate habitat types. We lastly provide decision criteria to facilitate applications of our framework to the selection of recovery plans for other species and systems. Afin d'assurer la conservation des especes en peril, il est necessaire de posseder des methodes basees sur la science pour choisir entre les plans de recuperation centres sur une seule espece, sur une communaute ou sur un ecosysteme. Le choix d'un plan de recuperation se base souvent plus sur les taux de succes obtenus avec d'autres taxons et dans d'autres systemes ou sur le cout economique, mais moins sur l'ecologie du systeme en question. Nous avons mis au point un cadre de selection d'un plan de recuperation base sur la repartition et l'ecologie des especes menacees et non menacees dans les differents types d'habitats disponibles et nous l'avons utilise dans le cas des poissons de la riviere Sydenham, Ontario, Canada. En premier lieu, nous avons verifie si les repartitions des poissons pouvaient etre adequatement predites d'apres les caracteristiques de l'habitat que nous soupconnions limiter les repartitions des poissons menaces, par comparaison a celles obtenues a partir d'un eventail connu et plus etendu de caracteristiques de l'habitat capable de predire les repartitions de poissons. Nous avons ensuite verifie si les especes menacees se retrouvaient dans des types d'habitat similaires ou disparates. Dans la Sydenham, un plan de recuperation a l'echelle de l'ecosysteme nous semble plus approprie car les especes menacees vivent dans des types d'habitat disparates. Nous fournissons enfin des criteres de choix pour faciliter l'utilisation de notre cadre dans la selection des plans de recuperation pour d'autres especes et systemes. [Traduit par la Redaction], Introduction Science-based approaches for selecting between recovery plans are needed to protect the growing number of imperilled species listed by conservation agencies. Federal agencies in Canada, the United States, Europe, [...]

Fungi and protists make up an ecological group, trichomycetes, that inhabit the guts of invertebrates, mostly aquatic insects. Trichomycetes are reported herein from arthropods collected in lotic habitats (fast flowing streams) and lentic environments (ponds, ditches, seeps, and lakes) from 11 sites in Algonquin Park and 6 other sites in Ontario, Canada. Thirty-two trichomycete species were recovered, including 7 new species: Legeriomyces algonquinensis, Legeriosimilis leptocerci, Legeriosimilis whitneyi, and Paramoebidium umbonatum are described from mayfly nymphs (Ephemeroptera); Pennella digitata and Glotzia incilis from black fly and midge larvae (Diptera), respectively; and Arundinula opeongoensis from a crayfish (Crustacea). Legeriomyces rarus Lichtw. & M.C. Williams and Stachylina penetralis Lichtw. are new North American records, and seven species are documented for the first time in Canada. More common and widely distributed trichomycete species such as Harpella melusinae Leger & Duboscq and Smittium culicis Manier, were also recovered. Most previous studies on trichomycetes have been done primarily in lotic environments but clearly lentic systems (e.g., ponds and lakes) harbour diverse arthropod communities and further exploration of these habitats will continue to increase our knowledge of trichomycete diversity. Key words: Amoebidiales, Eccrinales, Harpellales, insect fungal endobionts, symbiotic protista. Les champignons et les protistes comportent un groupe ecologique, les trichomycetes, qui habitent les intestins de la plupart des insectes aquatiques. Les auteurs rapportent des ttrichomycetes provenant d'arthropodes vivants dans des habitats lotiques (cours d'eau rapides) et des environnements lentiques (etangs, fosses, suintement et lacs) recoltes sur 11 sites dans le parc Algonquin et six autres sites en Ontario, au Canada. On a trouve 33 especes de trichomycetes, incluant sept nouvelles especes pour l'Amerique du Nord: Lageriomyces algonquinensis, Lageriosimilis leptocerci, Lageriosimilis whitneyi et Paramoebidium umbonatum, decrits a partir de nymphes d'ephemeres (Ephemeroptera); Pennella digitata et Glotzia incilis a partir de mouches noires et de brulots (Diptera) respectivement; et Arundinula opeongoensis a partir d'un ecrevisse (Crustacea). Le Lageriomyces rarus Lichtw. & M. C. Williams et le Stachylina penetralis Lichtw. Sept especes sont repertoriees pour la premiere fois au Canada. On a egalement retrouve des especes de trichomycetes communes et largement distribuees, comme l'Harpella melusinae Leger & Duboscq et le Smittum culicis Manier. La plupart des etudes antecedentes sur les trichomycetes ont ete conduites surtout en environnements lotiques, mais il est clair que les systemes lentiques (etangs et lacs) comportent diverses communautes d'arthropodes et que d'autres explorations de ces habitats vont permettre d'augmenter notre connaissance de la diversite des trichomycetes. Mots-cles : Amaoebidiales, Eccrinales, Harpellales, champignons endosymbiontes des insectes, protistes symbiotiques. [Traduit par la Redaction], Introduction Canada has a wide variety of freshwater aquatic habitats such as lakes, ponds, swamps, rivers, and streams, making up extensive watersheds. Information on Canada's immense hydrologic diversity is available [...]

The effective discharge ([Q.sub.e]) of a channel reach may be analytically determined by fitting the flow-duration relationship with a distribution model and representing the bed-material transport with a power function. Analysis of stream-flow data from small southern Ontario streams showed that the commonly used lognormal distribution does not provide a good fit to many streamflow records. A mixed exponential distribution model is proposed and a formula for computing the resulting [Q.sub.e] is derived. The results from this new [Q.sub.e] formula were compared with those obtained using other analytical distribution functions and those from empirical sediment transport effectiveness curves. These comparisons indicate that the new analytical solution provides on average the most accurate estimates of [Q.sub.e] when the exponent β of the power function describing sediment transport at the channel reach is not more than 2; when β > 2, a gamma distribution provides the most accurate estimates followed closely by the mixed exponential distribution. Key words: effective discharge, stream restoration, flow-duration relationship, flow distribution model. Le debit effectif ([Q.sub.e]) d'un canal peut etre determine par analyse en ajustant la relation debit-duree a un modele de distribution et en representant le transport du materiel du lit par une fonction puissance. L'analyse de l'ecoulement dans de petits ruisseaux du sud de l'Ontario a montre que la distribution log-normale couramment utilisee ne fournit pas un bon ajustement a plusieurs donnees de debits. Un modele de distribution exponentielle mixte est propose et une formule de calcul du [Q.sub.e] qui en decoule est derivee. Les resultats de cette nouvelle formule du [Q.sub.e] ont ete compares a ceux obtenus en utilisant d'autres fonctions analytiques de la distribution et a ceux provenant de courbes empiriques d'efficacite de transport des sediments. Ces comparaisons montrent que la nouvelle solution analytique fournit en moyenne les plus precises estimations des [Q.sub.e] lorsque l'exposant (β) de la fonction puissance decrivant le transport des sediments dans le parcours du canal n'est pas superieure a 2; lorsque β > 2, une distribution gamma fournit les estimations les plus precises, suivies de pres par la distribution exponentielle mixte. Mots-cles : debit effectif, restauration des ruisseaux, relation debit-duree, modele de repartition des debits. [Traduit par la Redaction], 1. Introduction Discharges in a river reach vary widely with time. A single discharge value known as the channel-forming discharge is often used as the representative value for channel stability [...]

The reported effects of selection silviculture on downed woody debris (DWD) vary. To investigate the processes underlying potential management impacts on DWD stocks and fluxes, we conducted a repeated census of downed wood in selection-harvested, selectively harvested, and unmanaged (old-growth) stands in central Ontario. DWD was significantly more abundant in stands harvested within the last 20 years than in stands harvested earlier, and shifted towards more advanced decay classes over the first 20 years after harvest. These results are consistent with persistence of a harvest-related DWD pulse for up to two decades in managed stands. The transition of DWD from early and middle decay classes to more advanced decay classes proceeded more slowly in managed than unmanaged stands. Species type, identity of fungal fruiting bodies, presence of a cut surface, and plot moisture class were significant predictors of variation in decay dynamics within particular decay classes; however, these factors did not account for observed differences in decay-class transitions between managed and unmanaged stands. A decay class matrix model projected DWD half-lives of 19 years for unmanaged stands and 21 years for managed stands. Over the long term, slower decay dynamics may help somewhat in maintaining relatively high DWD abundances in stands managed under selection silviculture. Les resultats qui ont ete rapportes concernant les effets du jardinage sur les debris ligneux an sol (DLS) varient. Dans le but d'etudier les processus sons-jacents aux impacts potentiels de l'amenagement sur les stocks et les flux de DLS, nous avons effectu6s des releves repetes des DLS dans des peuplements soumis a une coupe de jardinage, a une coupe d'ecremage on non amenages (foret ancienne) dans le centre de l'Ontario. Les DLS etaient significativement plus abondants dans les peuplements recoltes an cours des 20 dernieres annees que dans les peuplements recoltes il y plus long-temps et ont evolue vers des classes de decomposition plus avancees an cours des premiers 20 ans apres la recolte. Ces resultats concordent avec la persistance d'une recrudescence des DLS reliee a la recolte pendant une periode pouvant aller jusqu'a deux decennies dans les peuplements amenages. Le passage des DLS des classes de decomposition initiale et intermediaire vers une classe de decomposition plus avancee s'est fait plus lentement dans les peuplements amenages que dans les peuplements non amenages. Le type d'essences, l'identite des carpophores, la presence d'une decoupe et la classe d'humidite de la placette etaient des indicateurs significatifs de la variation dans la dynamique de la decomposition dans une classe de decomposition donnee. Cependant, ces facteurs n'expliquaient pas les differences observees entre les peuplements amenages et non amenages dans la transition entre les classes de decomposition. Un modele matriciel des classes de decomposition predisait une demi-vie des DLS de 19 ans dans les peuplements non amenages et de 21 ans dans les peuplements amenages. A long terme, une dynamique de decomposition plus lente pent contribuer un pen a maintenir une abondance relativement elevee de DLS dans les peuplements amenages soumis an jardinage. [Traduit par la Redaction], Introduction Maintaining stocks of downed woody debris (DWD) is increasingly regarded as a necessary component of ecologically sound forest management practices (Hagan and Grove 1999; McComb and Lindenmayer 1999). In [...]

Abstract: We analyzed data on downed woody debris (DWD) from 435 permanent sample plots in boreal and mixedwood forests of Ontario seeking empirical relationships to predict DWD quantity from stand [...]

Abstract: Preindustrial forest composition for >180000 k[m.sup.2] throughout central and northeastern Ontario was recreated from Ontario Crown land survey notes (1816-1955) and compared with existing forest composition derived from current [...]

Abstract: Decline index (indicator of crown condition) data from 102 forest plots (approximately 10000 trees) during 1986-2004 were compiled to derive survival models for south-central Ontario, Canada. The dominant species [...]

A 34% reduction in 10-m wind speeds at Sudbury Airport in Ontario, Canada, over the period 1975-95 appears to be a result of significant changes in the surface roughness of the surrounding area that are due to land restoration and reforestation following historical environmental damage caused by high sulfur dioxide and other industrial emissions. Neither 850-hPa winds extracted from the NCEP-NCAR reanalysis database nor wind measurements at meteorological stations 200 km to the north and 120 km to the east of Sudbury show the same decrease. To assess these changes in observed wind speed quantitatively, geostrophic drag laws were employed to illustrate potential changes in near-surface wind speeds in areas surrounding the airport. A model of the internal boundary layer flow adjustment associated with changes in the surface roughness length between the surroundings and the grass or snow surface of the airport was then applied to compute expected annual average wind speeds at the airport site itself. The estimates obtained with this relatively simple procedure match the observations and confirm that reforestation is likely the major cause of the reduced wind speeds. This finding bears economic, social, and ecological importance, because it will influence wind energy potential, wind loads on structures, wind chill, and home heating costs through to the biology of small- to medium-sized lakes.