Photographic Key for the Microhistological Identification of some Arctic Vascular Plants

Microhistological techniques are used in many studies of food habits in herbivores. A photographic key for the microhistological identification of 112 Arctic and Subarctic plant species is presented. Epidermal features used in the key are described and illustrated in a photographic glossary. Enough information is given on plant collection, fragment preparation, and feature identification to help users customize the key with additional Arctic plant species.L'analyse microhistologique est couramment utilisée lors d'études du régime alimentaire des herbivores. On présente un tableau photographique d'identification microhistologique de 112 espèces de plantes arctiques et subarctiques. Les caractéristiques épidermiques utilisées dans le tableau sont décrites et illustrées dans un glossaire photographique. L'article fournit assez de détails sur la collecte des plantes, la préparation des épidermes et l'identification des caractéristiques pour permettre aux utilisateurs d'adapter le tableau en y incluant d'autres espèces végétales

Habitat Use by Brood-Rearing Waterfowl in Subarctic Québec

Aerial surveys of waterfowl were conducted in subarctic Quebec in 1989 and 1990 on randomly selected 100 sq km plots. We used logistic regression for modelling relationships betweren the presence of waterfowl broods and habitat characteristics. For each species, models of habitat use were generated with one data set and tested with two others. We also compared the frequency distributions of broods of each species in different habitat types. Correct-classification rates of models varied betweren 0.53 and 0.77. Sensitivity of models generally increased when applied to validation data sets. Models showed that green-winged teals (Anas crecca) avoided lakes >501 ha and used vegetated lakes, ponds and fens or bogs more than predicted by their availability. Black scoters (Melanitta nigra) and surf scoters (M. perspicillata) were found mostly on small lakes (<10 ha) and medium lakes (10-100 ha). Black scoters were associated with the presence of ponds and lakes with sedge and grass, whereas surf scoters were not. The presence of scaup (Aythia spp.) broods was associated with the presence of vegetation. Green-winged teals were observed more often on bogs than were either scoters or scaups. Black scoters were observed more often on ponds and less often on medium-sized lakes than surf scoters and scaups. The latter differed in their use of lakes <10 ha: surf scoters, like black scoters, mostly used unvegetated lakes, while scaups and green-winged teals mostly used vegetated lakes. The accuracy and precision of logistic models may be enhanced by additional habitat variables, careful selection of sample-cell size and further investigation of the breeding biology of the surveyed species.Key words: habitat, model, logistic regression, northern Québec, black scoter, surf scoter, green-winged teal, scaup, broodDes inventaires aériens de sauvagine dans des parcelles de 100 km² sélectionnées aléatoirement ont été réalisés dans le Québec subarctique en 1989 et en 1990. La régression logistique fut utilisée pour modéliser les relations entre la présence de couvées et des paramètres d'habitat. Des modèles d'utilisation d'habitat ont été générés à l'aide d'une série de données et validés à l'aide de deux autres. Nous avons aussi comparé les distributions de fréquences des couvées des espèces étudiées dans divers types de biotopes. Les taux de classification correcte des modèles ont varié entre 0.53 et 0.77. De façon générale, la sensibilité des modèles augmentait lorsque ces derniers étaient appliqués aux données de validation. Les modèles montrent que la Sarcelle à ailes vertes (Anas crecca) a utilisé les plans d'eau avec de la végétation, les étangs et les tourbières et a évité les lacs > 501 ha. Les macreuses (Melanitta nigra, M. perspicillata) ont surtout été vues sur des lacs de petite (< 10 ha) et moyenne (10-100 ha) superficies. Les Macreuses à bec jaune se démarquaient des Macreuses à front blanc en étant associées à la présence d'étangs et de lacs avec des herbaçaies. La présence de couvées de morillons (Aythia spp.) dans les cellules était associée à celle de végétation. La Sarcelle à ailes vertes fut observée plus souvent dans les tourbières que les autres espèces. La Macreuse à bec jaune fut observée plus souvent sur des étangs et moins souvent sur des lacs de superficie moyenne que la Macreuse à front blanc et les morillons. Ces dernières espèces différaient dans leur utilisation de lacs <10 ha: les Macreuses à front blanc, comme les Macreuses à bec jaune, utilisaient surtout les lacs aux rives sans végétation alors que les morillons et les sarcelles utilisaient surtout des lacs avec végétation. La précision des modèles de régression logistique pourrait être augmentée par l'utilisation de paramètres d'habitat supplémentaires, un choix différent de la taille de l'unité de mesure et une meilleure connaissance de l'écologie des espèces cibles.Mots clés: habitat, modèle, régression logistique, Québec, Macreuse à bec jaune, Macreuse à front blanc, Sarcelle à ailes vertes, Morillons, couvé

Increasing fire and the decline of fire adapted black spruce in the boreal forest

Intensifying wildfire activity and climate change can drive rapid forest compositional shifts. In boreal North America, black spruce shapes forest flammability and depends on fire for regeneration. This relationship has helped black spruce maintain its dominance through much of the Holocene. However, with climate change and more frequent and severe fires, shifts away from black spruce dominance to broadleaf or pine species are emerging, with implications for ecosystem functions including carbon sequestration, water and energy fluxes, and wildlife habitat. Here, we predict that such reductions in black spruce after fire may already be widespread given current trends in climate and fire. To test this, we synthesize data from 1,538 field sites across boreal North America to evaluate compositional changes in tree species following 58 recent fires (1989 to 2014). While black spruce was resilient following most fires (62%), loss of resilience was common, and spruce regeneration failed completely in 18% of 1,140 black spruce sites. In contrast, postfire regeneration never failed in forests dominated by jack pine, which also possesses an aerial seed bank, or broad-leaved trees. More complete combustion of the soil organic layer, which often occurs in better-drained landscape positions and in dryer duff, promoted compositional changes throughout boreal North America. Forests in western North America, however, were more vulnerable to change due to greater long-term climate moisture deficits. While we find considerable remaining resilience in black spruce forests, predicted increases in climate moisture deficits and fire activity will erode this resilience, pushing the system toward a tipping point that has not been crossed in several thousand years

Habitat selection by sympatric black ducks and mallards in Abitibi, Quebec

Habitat use by sympatric black ducks (Anas rubripes) and mallards (A platyrhynchos) was studied in Abitibi, Quebec during May-August 1988 and 1989.Black duck broods preferred emergent and shrub-rich areas in both years. Mallard broods' habitat use differed from 1988 to 1989 (from emergent to shrub-emergent areas) when average water levels were higher. Diversity of habitats seems more important to rearing black ducks than to mallards. Rearing mallards seem to modify their use of habitats according to changing habitat availability. Daily survival rates differed only slightly between "species".Telemetry was used to study wetland use by six mallard and three black duck non-breeding females. Swamps were preferred whereas ericaceous shrub wetlands were avoided by both "species". Beaver (Castor canadensis) ponds were extensively used during the moulting period. Home ranges averaged 302.7 ha for black ducks and 201.2 ha for mallards

Age Ageing

Objective: the aim of this study was to examine the bidirectional association of vision loss (VL) and hearing loss (HL) with anxiety over a 12-year period. Design: this was a prospective population-based study. Setting: community-dwelling French adults. Participants: the study included 3,928 adults aged 65 and above from the Three-City study. Methods: the relationships of VL, as assessed by near visual acuity and self-reported HL to a diagnosis of generalised anxiety disorder (GAD) were assessed over 12 years. A further objective was to explore whether sensory loss has a differential relationship with GAD than with anxiety symptoms, assessed by the Spielberger's State-Trait Anxiety Inventory. Results: at baseline, HL [odds ratio (OR) = 1.41, 95% confidence interval (CI) 1.02-1.96, P = 0.04], but not mild or moderate to severe VL, was associated with self-reported anxiety symptoms (OR = 1.07 95% CI 0.63-1.83, P = 0.80; OR = 0.66 95% CI 0.12-2.22, P = 0.50, respectively). Neither vision nor HL was significantly associated with incident GAD. Baseline GAD was related to increased risk of incident HL (OR = 1.17, 95% CI 1.07-1.28, P < 0.001), but not mild or moderate to severe vision loss (OR = 1.01, 95% CI 0.96-1.06, P = 0.81; OR = 0.97, 95% CI 0.89-1.05, P = 0.45, respectively). Conclusions: increased anxiety symptoms were observed in older adults with HL, whereas we found no evidence for an association between VL and anxiety. Anxiety was prospectively associated with increased risk of reporting HL. Improved detection of anxiety in older adults with HL may improve quality of life