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Introduces a series of articles regarding the impact of the mass extinction of rare and exotic species on global environment and evolution, published in the 1999 issue "Canadian Journal of Earth Sciences."

A number of national environmental objectives have been decided on by the Swedish parliament. In this paper, a measure of willingness to pay for attaining these objectives is outlined in terms of an “environmental budget”, which can be disaggregated. Based on a nationwide contingent valuation survey, the average environmental budget was estimated and then disaggregated on specific “green” indicators. This paper focuses especially on protection of forest land for biodiversity purposes. Multiple bounded dichotomous choice questions were employed in the survey, allowing respondents to express uncertainty in their valuations. The effect of different question formats and valuation scenarios on the disaggregation of the environmental budget was investigated. Consideration of uncertainty had a significant impact on willingness to pay estimates. Willingness to pay varied between different levels of forest land protection when uncertainty was explicitly introduced. When valuation estimates were aggregated on the national level, the value of forest land protection exceeded the costs by a small margin. Plusieurs objectifs environnementaux ont été arrêtés par le Parlement suédois pour l’ensemble du pays. La mesure du consentement à payer pour atteindre ces objectifs constitue l’objet de cet article. Cette mesure est présentée en terme de budget environnemental qui peut être décomposé. tabli à partir d’un sondage réalisé avec la méthode d’évaluation contingente à l’échelle du pays, le budget environnemental moyen a été estimé puis décomposé selon des indicateurs « verts »spécifiques. Cet article met une emphase particulière sur la protection du territoire forestier pour des fins de biodiversité. Des questions contraintes par des choix de réponses multiples dichotomiques ont été utilisées lors du sondage pour permettre aux répondants d’exprimer de l’incertitude à propos de leurs évaluations. L’effet des différentes formulations des questions et des différents scénarios d’évaluation proposés sur la décomposition du budget environnemental a été étudié. Le fait de considérer l’incertitude a un impact significatif sur les estimations du consentement à payer. Le consentement à payer varie selon le niveau de protection du territoire forestier lorsque l’incertitude est explicitement introduite. Lorsque les estimations des valeurs sont regroupées à l’échelle nationale, la valeur de la protection du territoire forestier excède légèrement les coûts. [ABSTRACT FROM AUTHOR]

Poplars are trees of the angiosperm genus Populus, a group of generally diploid, dioecious, and deciduous pioneers that are widespread in forests around the Northern Hemisphere. Canada is a centre of poplar abundance and diversity, with 7 of the 29 global Populus species occurring naturally, and other species being introduced. Numerous interspecific hybrids also occur, including native hybrids that create centres of biodiversity, and artificial hybrid poplars that are planted for wood and fiber production, as well as for environmental and landscape applications. This paper introduces poplars and their distribution across Canada and explores Canadian and international contributions to poplar research. It also discusses papers of the special issue Poplar Research in Canada in the November 2007 and December 2007 issues of the Canadian Journal of Botany, which contains a collection of 19 contributions from Canadian institutions that report on a diverse range of topics including genomics and molecular biology, physiology, ecology, population genetics, and systematics. Many of these contributions address issues pertinent to silviculture and other applications, and one article chronicles poplar research and poplar utilization in Canada. These studies that appear in this special issue reflect the growing international emphasis on poplar, not only as an important and widespread group of trees, but also as a model that provides broader insights relevant to fundamental and applied sciences involving trees and forest systems. [ABSTRACT FROM AUTHOR]

This paper discusses local understanding of plants and habitats, based on the linguistic evidence [terms for plants and (or) habitats] gathered from ethnobotanical and ethnoecological field work conducted with several Dene Nations of the Canadian northwestern boreal forest and adjacent regions. Nations involved in the study include Gwich’in (Mackenzie Delta Region), Sahtú’otine’ (Great Bear Lake), Kaska Dena (southern Yukon), and Witsuwit’en (northwest British Columbia). Key plant-related habitats include meadow, “swamp”, forest, “willows”, and “brush”. The ethnobotanical classification of willows is explored in conjunction with the explanation of the Dene habitat concept. In local classifications, ‘willow’ is not co-extensive with the genus Salix, but includes a variety of medium to tall woody shrubs that lack either conspicuous flowers, ‘berries’, or thorns; these may include shrubby species of Salix, Alnus, Cornus, and Betula. Shoreline and alpine environments are also discussed as plant habitats. Dene use of alpine environments and resources is ancient, according to the results of recent alpine ice patch research in the Yukon region. The Human dimensions of habitat knowledge are presented. Indigenous concepts of plant taxa and of landscape associations or habitats may differ substantially from those of scientific botany and ecology, and are based in a holistic and interactive ethnoecology. [ABSTRACT FROM AUTHOR]

Diatom ecology and species compositional patterns across current arctic treeline can provide important paleoecological information associated with climatic and environmental change. In this paper we examine the relationships between measured environmental variables and modern diatom assemblage composition from 77 lakes across the treeline ecozones of the Central Canadian Arctic. The weighted-average optima for selected enviromental variables were calculated for 74 of the most common diatoms, and photographic plates of these taxa are included. Our results indicated that both forest-tundra and arctic tundra lakes differed significantly in diatom assemblage composition from boreal forest lakes. In general, planktonic diatom taxa (e.g., Cyclolella species) were more common in forested lakes, which may be due to ecological conditions related to climate. Small, benthic, alkaliphilic Fragilaria taxa reached their highest abundances in forested lakes, likely because of the more alkaline nature of these lakes. Arctic tundra lakes were characterized by higher abundances of circumneutral to acidophilic taxa. Heavily silicified Aulacoseira taxa (e.g., Aulacoseira lirata, Aulacoseira perglabra) were more common in deeper tundra lakes, likely because of the less alkaline nature of these lakes and greater wind-induced turbulence in this zone. These trends provide important information on the variability of aquatic ecosystems across this climatically sensitive vegetational gradient. [ABSTRACT FROM AUTHOR]

Introduces a series of articles featured in the special issue of the "Canadian Journal of Earth Sciences." Discussion of articles on the final compendium of papers on the Alberta Basement Transect of Lithoprobe.