435 research outputs found

    Geology of Canadian Wetlands

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    Wetlands have not gained as much attention as they ought to by geologists despite being so prevalent in the Canadian landscape. Some of this stems from a poor understanding of wetland geology and what wetland landforms are. Wetlands constitute unusual landformsin that they are formed of biological material predominantly shaped by biological processes rather than being formed of minerals and rock shaped more by physical processes. There are two main groups of wetlands: mineral wetlands, commonly situated in high-energy settings; and peatlands, situated in low-energy settings that undergo either terrestrialization or paludification during the course of their development. Wetlands, as both a landscape unit and economic resource, have historically been and will continue to be important in Canada. New and more specialized skills and engineering designs will be required to build infrastructurein wetland terrain. Wetlands should be regarded as an economic resource that requires wise use and management. Nature-sensitive technologies need to be invented for use with wetlands to conserve and enhance the resource to serve the needs and protect the health of human society. RÉSUMÉ Bien qu'elles constituent un trait dominant du paysage canadien, les gĂ©ologues n'ont pas prĂȘtĂ© suffisamment d'attention aux terres humides. Cela tient en partie Ă  une mauvaise connaissance de la gĂ©ologie des terres humides et de ce que sont ces Ă©lĂ©ments gĂ©omorphologiques. Comme Ă©lĂ©ments gĂ©omorphologiques, les terres humides ont ceci de particulier qu'elles sont principalement constituĂ©es de matĂ©riaux biologiques issus de processus biologiques, et non de minĂ©raux et de roches formĂ©es par des processus physiques. Il existe deux grands groupes de terres humides, soit les terres humides minĂ©rales, gĂ©nĂ©ralement situĂ©es en milieux de hautes Ă©nergies, et les tourbiĂšres, situĂ©es en milieux de basses Ă©nergies, et dont le dĂ©veloppement comporte une Ă©tape de terrestrialisation ou de tourbification. Tant comme Ă©lĂ©ment topographique que ressource Ă©conomique, les terres humides ont Ă©tĂ© et demeurent importantes au Canada. Des savoirfaire techniques nouveaux et plus spĂ©cialisĂ©s seront nĂ©cessaires pour concevoir et Ă©difier des infrastructures en milieux humides. On devrait voir les terres humides comme une ressource Ă©conomique devant ĂȘtre gĂ©rer avec sagesse. Il est nĂ©cessaire que des technologies douces soient inventĂ©es pour conserver la ressource et en tirer un meilleur parti tout en protĂ©geant la santĂ© humaine

    Pollen, Plant Macrofossils, and Insects from Fossil Woodrat (Neotoma Cinerea) Middens in British Columbia

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    Bushy-tailed woodrats (Neotoma cinerea) occur commonly in cliffs, rock talus, and caves in the open Pseudotsuga menziesii and Pinus ponderosa forests throughout interior British Columbia. Fossil N. cinerea middens from two sites in central British Columbia were radiocarbon dated and examined for pollen, plant macrofossils and insect remains. The Oregon Jack Creek site contains a midden that is dated 1150 ± 80 (WAT-1764) radiocarbon years ago. Pollen analyses reveal an abundance of Cupressaceae (Juniperus) and Pinus. Shrub and herb pollen types include Artemisia. Fabaceae, Poaceae, and Asteraceae. Juniperus scopulorum leaves, Pseudotsuga menziesii needles, Chenopodiaceae seeds. Rosa thorns and Artemisia leaflets are the main plant macrofossils. The remains of three beetle genera, Cryptophagus, Lathridius, and Enicmus represent insects that probably lived in the midden, eating decaying organic matter or moulds. Click beetle (Limonius) remains were probably brought into the midden from nearby soil or plant material. The Bull Canyon site contains a midden that dates to 700 ± 80 (WAT-1765) years BP. Pollen and plant macrofossil assemblages are similar to those at the Oregon Jack Creek site. Woodrat middens offer a new dimension in reconstructing Holocene paleoenvironments in the arid interior of British Columbia, in much the same way as they do in the southwest United States.Les rats Ă  queue touffue s'observent souvent dans les escarpements, les talus rocheux et les cavernes dans les forĂȘts ouvertes de Pseudotsuga menziesii et de Pinus ponderosa de l'intĂ©rieur de la Colombie-Britannique. Des amoncellements de matiĂšres fĂ©cales fossilisĂ©s de N. cinerea recueillis dans deux sites du centre de la Colombie-Britannique ont Ă©tĂ© datĂ©s au radio-carbone et analysĂ©s pour leur contenu en pollen, en macrofossiles de vĂ©gĂ©taux et en restes d'insectes. Le site d'Oregon Jack Creek renferme un amoncellement datĂ© Ă  1150 ± 80 BP (WAT-1764). Les analyses polliniques ont rĂ©vĂ©lĂ© qu'il y avait abondance de Cupressaceae (Juniperus) et de Pinus. Les grains de pollen d'arbustes et d'herbacĂ©es comprennent Artemisia, Fabaceae. Poaceae et Asteraceae. Les principaux macrofossiles de vĂ©gĂ©taux Ă©taient des feuilles de Juniperis scopulorum, des aiguilles de Pseudotsuga menziesii, des graines de Chenopodiaceae, des Ă©pines de Rosa et des folioles o"Artemisia. Les restes de trois genres de colĂ©optĂšres (Cryptophagus, Lathridius et Enicmus) reprĂ©sentent les insectes qui vivaient probablement dans les amoncellements, se nourrissant de la matiĂšre organique en dĂ©composition ou des moisissures. Les restes de Limonius proviennent probablement du sol environnant ou des vĂ©gĂ©taux. Le site de Bull Canyon renferme un amoncellement qui date de 700 ± 80 BP (WAT-1765). Les assemblages de pollen et de vĂ©gĂ©taux ressemblent Ă  ceux du site d'Oregon Jack Creek. Les matiĂšres fĂ©cales du rat Ă  queue touffue offrent de nouvelles possibilitĂ©s de reconstitution des palĂ©oenvironnements de l'HolocĂšne de la rĂ©gion intĂ©rieure aride de la Colombie-Britannique, un peu comme c'est dĂ©jĂ  le cas dans le sud des Etats-Unis.Ratten mit buschigem Schwanz (Neotoma cinerea) findet man oft in den Klippen, Schutthalden und HĂŽhlen in den offenen Pseudotsuga menziesii und Pinus ponderosa WĂ ldern im ganzen lnnern von British Columbia. Fosile N. cinerea FĂąkalien von zwei PlĂątzen in Zentral British Columbia wurden mit Radiokarbon datiert und auf Pollen, pflanzliche Makrofossile und lnsektenspuren untersucht. Der Platz Jack Creek in Oregon enthĂ lt einen Fakalienfund, der auf 1150 ± 80 (WAT-1764) Radiokarbonjahre v.u.Z. datiert wird. Die Pollenanalysen enthullen eine FuIIe von Cupressaceae (Juniperus) und Pinus. Buschund Graspollenarten schliessen Artemisia, Fabaceae, Poaceae und Asteraceae ein. Blatter von Juniperus scopulorum, Nadeln von Pseudotsuga menziesii, Samen von Chenopodiaceae, Dornen von Rosa und BlĂąttchen von Artemisia sind die hauptsĂąchlichen Pflanzenmakrofossile. Die Reste von drei Kaferarten, Cryptophagus, Lathridius und Enicmus reprĂąsentieren Insekten, die mĂŽglicherweise in den FĂąkalien lebten und verwesendes organisches Material Oder Schimmel assen. Limonius-Reste wurden wahrscheinlich in die FĂąkalien von nahegelegenem Erdreich Oder Pflanzenmaterial gebracht. Der Platz Bull Canyon enthĂ lt FĂąkalien, die auf 700 ± 80 (WAT-1765) Jahre v.u.Z. datiert werden. Pollen- und makrofossile Pflanzenansammlungen sind denen des Jack Creek-Platzes von Oregon Ă hnlich. FĂąkalien von Waldratten liefern eine neue Dimension bei der Rekonstruktion der PalĂ oumwelt im HolozĂ n im trockenen lnnern von British Columbia, ganz in derselben Weise, wie sie das schon im Sudwesten der Vereinigten Staaten tun

    Effects of Wetland Creation on Breeding Season Bird Use in Boreal Eastern Ontario

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    Wetland construction has been an effective means of mitigating wetland habitat losses due to agricultural and other activities. However, the type, variety, and age of the habitats created are often critical components in the success of the wetland when the aim is to enhance the bird community. Hilliardton Marsh was constructed as a series of cells between 1993 and 1997 in boreal eastern Ontario to provide waterfowl habitat. We determined habitat change and monitored breeding-season bird use before construction and one year after the last cell was constructed. Wetland construction resulted in dramatic changes to the vegetation and bird communities. The area was transformed into a variety of wetland habitats, but primarily marsh, one of the rarest wetland types in boreal Ontario. Survey stations with moderate habitat change exhibited the greatest change in bird species richness. Total species richness increased 55% from 56 to 87 species, with obligate wetland birds increasing from 3 to 26 species. Rare birds increased from 11 to 27 species, with most as obligate or facultative wetland birds, but also Peregrine Falcon (Falco peregrinus). Bird abundance, as measured by the number of stations where a species was observed, increased significantly for obligate wetland birds. There were no significant losses of species from any bird group, as adjacent upland habitat was preserved. This short-term study has shown that construction of new wetland habitat in boreal eastern Ontario, especially marsh, can significantly increase the numbers of breeding-season birds, including rare species. However, longterm monitoring is required to ensure sustained success of wetland construction projects for birds

    Licit and illicit drug policies: a typology

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    To foster comparison of policy interventions across the various categories of licit and illicit drugs, we develop a typology of policies intended to address drug abuse problems. The principal dimensions of the typology are policy type and intervention channel. While the typology has important limitations, as a mechanism to organize information and stimulate thought it holds the potential to improve understanding of commonalities and distinctions among policies applying to widely discrepant drug problems, both within and across cultures. As such, it could contribute to the development of more effective approaches to grappling with a diverse set of drug policy issues.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/73129/1/j.1360-0443.1990.tb03081.x.pd

    Addressing food insecurity in Papua New Guinea through food safety and sago cropping

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    Papua New Guinea (PNG) is known to have a large resource base of sago with over 1 million ha, as well as a high number of germplasm types of the Metroxylon species. The country’s food security status is very low and is primarily dependent on subsistence fresh garden produce as practiced by 85% of the population who are rural dwellers. Postharvest losses can be as high as 40% with little to no postharvest technology nor processing of foods done. Sago provides well for food security and sustains life in rural communities during disasters such as droughts, floods, and cyclones. The dilemma of sago being an underutilized crop in PNG is exacerbated by the introduction of new food crops, cash crops, and limited accessibility to cash to purchase other foods. Over the last 50 years, sago consumption has diminished as one of the major traditional food staples, from 16% to less than 10%. Neglect of sago is further due to food safety concerns about traditionally processed sago, in particular, the risk from sago hemolytic disease (SHD). For over30 years, SHD has been a food safety issue since it was first reported in 1973.Investigations on SHD highlight the serious need to improve on the hygiene and sanitation of the traditional postharvest processing and storage methods of sago starch in PNG. A set of hazard analysis and critical control point (HACCP) protocols has been developed for traditional processing of sago as a food safety measure to improve food safety for food security. While commercial cultivation is nonexistent, there is increased planting of the larger hapaxanthic, non-soboliferous sagospecies, Metroxylon salomonense Becc., in some nontraditional sago-consuming areas as a low-cost raw material source for roof thatching and other building materials. It is however a wasted opportunity for food security in these areas as the starch from the palm is not utilized. Current work in these areas promotes sago as a potential food source that can be harvested or processed into flour. This is to improve the food security status in areas of high population density, like island communities where land is scarce

    Testing peatland testate amoeba transfer functions: Appropriate methods for clustered training-sets

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    Transfer functions are widely used in palaeoecology to infer past environmental conditions from fossil remains of many groups of organisms. In contrast to traditional training-set design with one observation per site, some training-sets, including those for peatland testate amoeba-hydrology transfer functions, have a clustered structure with many observations from each site. Here we show that this clustered design causes standard performance statistics to be overly optimistic. Model performance when applied to independent data sets is considerably weaker than suggested by statistical cross-validation. We discuss the reasons for these problems and describe leave-one-site-out cross-validation and the cluster bootstrap as appropriate methods for clustered training-sets. Using these methods we show that the performance of most testate amoeba-hydrology transfer functions is worse than previously assumed and reconstructions are more uncertain

    Spectro-interferometric observations of classical nova V458 Vul 2007

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    We used the Palomar Testbed Interferometer (PTI) to resolve 2.2 ÎŒ\mum emission from the classical nova V458 Vul 2007 over the course of several days following its discovery on 2007 August 8.54 UT. We also obtained K-band photometric data and spectra of the nova during the early days of the outburst. We also used photometric measurements from the AAVSO database. This is a unique data set offering a 3-technique approach: high-resolution imaging, spectroscopy and photometry. Our analysis shows that the nova ejecta can be modeled as an inclined disk at low inclination i.e. low ellipticity which is consistent with the nova being in the fireball phase at which the outflowing gas is optically thick, confirmed by the presence of strong P-Cygni Balmer lines in the spectra. The expansion velocity is ≈\approx1700 km s−1\rm km\ s^{-1}, derived from the Hα\alpha line. By combining the nova's angular expansion rate measured by PTI with the expansion rate measured from spectroscopy, the inferred distance to the nova is 9.9-11.4 kpc. We also used the K-band fluxes and the derived size of the emission to estimate the total mass ejected from the nova ≈4×10−4M⊙\approx 4\times 10^{-4} M_{\odot}. The quick transition of the nova from Fe II to He/N class makes V458 Vul 2007 a hybrid nova.Comment: 31 pages, 7 figures, accepted for publication in Ap
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