Extreme faint flux imaging with an EMCCD

An EMCCD camera, designed from the ground up for extreme faint flux imaging, is presented. CCCP, the CCD Controller for Counting Photons, has been integrated with a CCD97 EMCCD from e2v technologies into a scientific camera at the Laboratoire d'Astrophysique Experimentale (LAE), Universite de Montreal. This new camera achieves sub-electron read-out noise and very low Clock Induced Charge (CIC) levels, which are mandatory for extreme faint flux imaging. It has been characterized in laboratory and used on the Observatoire du Mont Megantic 1.6-m telescope. The performance of the camera is discussed and experimental data with the first scientific data are presented.Comment: 33 pages, 17 figures, accepted for publication in PAS

Evidence of climate effects on the height-diameter relationships of tree species

International audienceAbstractKey messageThe mean temperature from March to September affects the height-diameter relationship of many tree species in France. For most of these species, the temperature effect is nonlinear, which makes the identification of an optimal temperature possible. Increases in mean temperature could impact the volume supply of commercial species by the end of the twenty-first century.ContextHeight-diameter (HD) relationships are central in forestry since they are essential to estimate tree volume and biomass. Since the late 1960s, efforts have been made to generalize models of HD relationships through the inclusion of plot- and tree-level explanatory variables. In some recent studies, climate variables such as mean annual temperature and precipitation have been found to have a significant effect on HD allometry. However, in these studies, the effects were all considered to be linear or almost linear, which supposes that there is no optimal temperature and no optimal precipitation.AimsIn this study, we tested the hypothesis that an optimum effect of temperature and precipitation exists on tree heights.MethodsWe fitted generalized models of HD relationships to 44 tree species distributed across France. To make sure that the climate variables would not hide some differences in terms of the local environment, the models included explanatory variables accounting for competition, tree social status and other plot-level factors such as slope inclination and the occurrence of harvesting in the last five years.ResultsIt turned out that the temperature effect was significant for 33 out of 44 species and an optimum was found in 26 cases. The precipitation effect was linear and was found to be significant for only seven species. Although the two climate variables did not contribute as much as the competition and the social status indices to the model fit, they were still important contributors. Under the representative concentration pathway (RCP) 2.6 and the assumptions of constant form factors and forest conditions in terms of competition and social statuses, it is expected that approximately two thirds of the species with climate-sensitive HD relationships will generally be shorter. This would induce a decrease in volume ranging from 1 to 5% for most of these species.ConclusionForest practitioners should be aware that the volume supply of some commercial species could decrease by the end of the twenty-first century. However, these losses could be partly compensated for by changes in the form factors and the species distributions

Biologie et situation de la Lamproie du Nord, Ichthyomyzon fossor, au Québec

La Lamproie du Nord est une espèce propre à l’Amérique du Nord et elle ne se rencontre, au Québec, que dans l’extrême sud de la province. Cette lamproie a été observée dans le fleuve Saint-Laurent ainsi que dans 11 de ses tributaires. Elle aurait disparu de la rivière Yamaska où elle avait été recensée entre 1946 et 1959. Poisson non parasite, sa taille au stade adulte ne dépasse habituellement pas 160 mm. Les larves, appelées ammocètes, et les adultes ne se retrouvent qu’en eau douce. Les cours d’eau utilisés sont généralement des ruisseaux et des rivières à fond graveleux ou sablonneux. La Lamproie du Nord requiert deux habitats distincts, soit un pour les adultes reproducteurs et un autre, le long du même cours d’eau, pour le développement des ammocètes. La détérioration de l’habitat et la pollution des eaux représentent les principales menaces à la survie des lamproies. La faible fécondité et la mobilité réduite de la Lamproie du Nord font en sorte que cette espèce est peu adaptable aux modifications de son environnement.The Northern Brook Lamprey is endemic to North America. In Quebec, it is restricted to the southernmost part of the province. This lamprey is known from the St. Lawrence River as well as in 11 of its tributaries. It appears to have been extirpated from the Yamaska River where it was collected between 1946 and 1959. It is a nonparasitic fish and its adult size does not usually exceed 160 mm. Larvae, called ammocoetes, and adults are found only in fresh water. Watercourses where it occurs are generally streams and rivers with gravel or sandy bottoms. The Northern Brook Lamprey requires two types of habitats during its life cycle, one for spawning adults and one, along the same watercourse, for the developing ammocoete. Habitat degradation and water pollution are the major threats to the survival of lampreys. The low fecundity and low dispersal abilities of the Northern Brook Lamprey make this species poorly adapted to withstand changes in its environment

Managing for the unexpected: Building resilient forest landscapes to cope with global change

Natural disturbances exacerbated by novel climate regimes are increasing worldwide, threatening the ability of forest ecosystems to mitigate global warming through car-bon sequestration and to provide other key ecosystem services. One way to cope with unknown disturbance events is to promote the ecological resilience of the forest by increasing both functional trait and structural diversity and by fostering functional connectivity of the landscape to ensure a rapid and efficient self- reorganization of the system. We investigated how expected and unexpected variations in climate and biotic disturbances affect ecological resilience and carbon storage in a forested region in southeastern Canada. Using a process- based forest landscape model (LANDIS-II), we simulated ecosystem responses to climate change and insect outbreaks under dif-ferent forest policy scenarios—including a novel approach based on functional diver-sification and network analysis—and tested how the potentially most damaging insect pests interact with changes in forest composition and structure due to changing cli-mate and management. We found that climate warming, lengthening the vegetation season, will increase forest productivity and carbon storage, but unexpected impacts of drought and insect outbreaks will drastically reduce such variables. Generalist, non- native insects feeding on hardwood are the most damaging biotic agents for our region, and their monitoring and early detection should be a priority for forest au-thorities. Higher forest diversity driven by climate-smart management and fostered by climate change that promotes warm-adapted species, might increase disturbance severity. However, alternative forest policy scenarios led to a higher functional and structural diversity as well as functional connectivity—and thus to higher ecological resilience—than conventional management. Our results demonstrate that adopting a landscape-scale perspective by planning interventions strategically in space and adopting a functional trait approach to diversify forests is promising for enhancing ecological resilience under unexpected global change stressors.MM received funding from the Swiss National Science Foundation (grant n.175101) and the European Union’s Horizon 2020 research and innovation program under the Marie Skłodowska-Curie framework (grant n.891671, REINFORCE project). NA was supported by a Juan de la Cierva fellowship of the Spanish Ministry of Science and Innovation (FCJ2020-046387-I). This work has also been supported by funding to NA and MM from the Canada Research Chair in Forest Resilience to Global Changes attributed to CM. MJF acknowledges the support of the Canada Research Chair in Spatial Ecology

Comparing different forest zoning options for landscape-scale management of boreal forest: Possible benefits of the TRIAD

Forest management has been criticised in the last 20 years for its negative impact on the native species, structures and functions of the forest. Of many possible alternatives proposed to minimize these effects, the functional zoning (or TRIAD) approach is gaining popularity in North America. The goal of this approach is to minimize the negative environmental impacts of forestry while maintain timber supply by dividing the forest into three broad land-use zones: (1) conservation, (2) ecosystemmanagement, and (3) wood production. In this study, we used a spatially explicit landscape model to simulate the effects of fire and six different forest management scenarios on a boreal mixedwood forest management unit in\ud central Quebec. Themanagement scenarios examined included the current practices scenario, a scenario proposed by the provincial government, and four TRIAD scenarios varying in the amount of forest allocated to each of the three zones. For each scenario, we examined the harvest volume, percentage oldgrowth forest or old forest managed to favour old-growth attributes, and effective mesh size of forest patches by 20-year age classes. Withmore area set aside for conservation and high-retention partial cut harvesting techniques designed to maintain the attributes of old-growth stands, all TRIAD scenarios resulted in higher percentages of stands with old-growth attributes than the current practices scenario and the government proposed scenario, and two of the four TRIAD scenarios also resulted in higher harvest volume over the long term. All forest management scenarios resulted in significantly lower effective mesh size than the fire-only scenario, but this difference was not as pronounced for the four TRIAD scenarios as for the current practice and government proposed scenarios. We conclude that the\ud TRIAD approach has the potential to minimize some of the negative impacts of forestry on the landscape, while maintaining timber supply over the long term

Sugar maple (Acer saccharum March.) growth is influenced by close conspecifics and skid trait proximity following selection harvest

In this study, we quantified the effects of local neighbourhood competition, light availability, and proximity to skid trails on the growth of sugar maple (Acer saccharum Marsh.) trees following selection harvest. We hypothesized that growth would increase with decreasing competition and increasing light availability, but that proximity to skid trails would negatively affect growth. A total of 300 sugar maples were sampled 10 years after selection harvesting in 18 stands in Témiscamingue (Québec, Canada). Detailed tree and skid trail maps were obtained in one 0.4 ha plot per stand. Square-root transformed radial growth data were fitted to a linear mixed model that included tree diameter, crown position, a neighbourhood competition index, light availability (estimated using the SORTIE light model), and distance to the nearest skid trail as explanatory variables. We considered various distance-dependent or -independent indices based on neighbourhood radii ranging from 6 to 12 m. The competition index that provided the best fit to the data was a distance-dependent index computed in a 6 m search radius, but a\ud distance-independent version of the competition index provided an almost equivalent fit to data. Models corresponding to all combinations of main effects were fit to data using maximum likelihood, and weighted averages of parameter estimates were obtained usingmultimodel inference. All predictors had\ud an influence on growth, with the exception of light. Radial growth decreased with increasing tree diameter, level of competition and proximity to skid trails, and varied among crown positions with trees in suppressed and intermediate positions having lower growth rates than codominants and dominants. Our results indicate that in selection managed stands, the radial growth of sugarmaple trees depends on\ud competition from close (6 m) conspecific neighbours, and is still affected by proximity to skid trails 10 years after harvesting. Such results underscore the importance of minimizing the extent of skid trail networks by careful pre-harvest planning of trail layout. We also conclude that the impact of heterogeneity among individual-tree neighbourhoods, such as those resulting from alternative spatial patterns of harvest, can usefully be integrated into models of post-harvest tree growth

Forest processes from stands to landscapes: exploring model forecast uncertainties using cross-scale model comparison

Forest management practices conducted primarily at the stand scale result in simplified forests with regeneration problems and low structural and biological diversity. Landscape models have been used to help design management strategies to address these problems. However, there remains a great deal of uncertainty that the actual management practices result in the desired sustainable landscape structure. To investigate our ability to meet sustainable forest management goals across scales, we assessed how two models of forest dynamics, a scaled-up individual-tree model and a landscape model, simulate forest dynamics under three types of harvesting regimes: clearcut, gap, and uniform thinning. Althougth 50– 100 year forecasts predicted average successional patterns that differed by less than 20% between models, understory dynamics of the landscape model were simplified relative to the scaled-up tree model, whereas successional patterns of the scaled-up tree model deviated from empirical studies on the driest and wettest landtypes. The scale dependencies of both models revealed important weaknesses when the models were used alone; however, when used together, they could provide a heuristic method that could improve our ability to design sustainable forest management practices

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ABSTRACT. Objective. We describe the pattern of incidence of thrombovascular events after diagnosis of systemic lupus erythematosus (SLE) in a cohort of lupus patients. Methods. Descriptive study of prospectively collected data using incidence rates of thrombovascular events and 95% confidence intervals (CI) calculated for predetermined periods of observation. KaplanMeier survival curves were plotted to estimate thrombovascular event-free survival. Results. Among 426 individuals, person-years contributed were as follows: 399 persons and 4356.0 person-years for all events; 417 persons and 4691.9 person-years for arterial events; and 408 persons and 4846.6 person-years for venous events. The incidence of thrombovascular events was highest during the first year after SLE diagnosis (4.00, 95% CI 2.24-6.59) and after 20 years (ranging from 3.32, 95% CI 1.52-6.30, to 4.99, 95% CI 0.60-18.01), and was lowest between 1 and 5 years after SLE diagnosis (1.00, 95% CI 0.53-1.72). A similar pattern was observed for arterial events, while venous events showed a higher incidence rate only in the first 30 days after SLE diagnosis (12.06, 95% CI 3.29-30.87) and remained low afterwards. The probabilities of remaining event-free at 5, 10, and 15 years were as follows: 0.92, 0.85, and 0.78, respectively, for all thrombovascular events; 0.95, 0.88, and 0.82, respectively, for arterial events; and 0.98, 0.95, and 0.94, respectively, for venous events. Conclusion. Thrombovascular events occur throughout the course of lupus, with the highest risk of arterial or venous events in the first year after diagnosis, and the pattern of occurrence varying there

Mittelfristige Prognose der österreichischen Wirtschaft 2012-2016: Jahresmodell LIMA/05 ; Ökonometrisches Forschungsprogramm des Instituts für Höhere Studien

aus dem Inhaltsverzeichnis: Einleitung und Zusammenfassung; Die internationale Konjunktur; Die österreichische Außenwirtschaft; Perspektiven der Inlandskonjunktur; Monetäre Prognose; Tabellenanhang