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Copyright of Environmental Reviews is the property of Canadian Science Publishing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Much of Canada's terrestrial biodiversity is supported by boreal forests. Natural resource development in boreal forests poses risks to this biodiversity. This paper reviews the scientific literature to assess the effects of natural resource development on terrestrial biodiversity in Canadian boreal forests. We address four questions: (1) To what extent have Canadian boreal forests changed due to natural resource development? (2) How has biodiversity responded to these changes? (3) Will the biodiversity of second-growth forests converge with that of primary boreal forests? (4) Are we losing species from boreal forests? We focus on trees, understory plants, insects, fungi, selected mammals, and songbirds because these groups have been most studied. We review more than 600 studies and found that changes in community composition are prevalent in response to large-scale conversion of forest types, changes in stand structures and age distributions, and altered landscape structure resulting from forest management and habitat loss associated with other developments such as oil and gas, hydroelectric, and mining. The southern boreal forest has been more highly impacted than the north due to more extensive forest management and the cumulative effects of multiple forms of development. There is abundant evidence that most species are not in danger of being extirpated from the boreal forest due to these anthropogenic changes. A few species, including woodland caribou ( Rangifer tarandus) and grizzly bear ( Ursus arctos), have, however, undergone long-term range contractions. Significant gaps in our ability to assess the effects of natural resource development on biodiversity in the boreal zone are the lack of long-term spatial and population data to monitor the impact of forest changes on ecosystems and species. [ABSTRACT FROM AUTHOR]

Copyright of Canadian Journal of Forest Research is the property of Canadian Science Publishing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Natural forests will likely be unable to sustainably fulfill society needs for wood fibers and intensively managed plantations could be an alternative source of timber in the future. Abandoned farm fields are often targeted for conversion, as they are already disturbed sites; however, they also represent high-quality habitat for species such as snowshoe hares (Lepus americanus Erxleben 1777), a keystone mammal in the boreal forest. We evaluated the effect of converting abandoned farm fields (n = 22) to conifer plantations (n = 19) on habitat use by snowshoe hares, using pellet counts and snow-tracking surveys. Both survey techniques yielded similar results: winter habitat use by hares is mostly affected by vegetation cover rather than habitat type. In the short term, plantations do not offer less protective cover than the one found in abandoned farm fields. However, upon reaching a certain height (>=7 m), plantations are mechanically pruned and lose their protective quality. Promoting silvicultural techniques that maintain lateral cover beyond a critical threshold (70%) could preserve the quality of hare habitat for an extended proportion of rotation time of the plantation. Il est vraisemblable que les forêts naturelles ne puissent pas combler de façon durable les besoins de la société pour les fibres de bois et que des plantations intensives servent alors de sources de replacement de bois dans le futur. Les champs de ferme abandonnés sont souvent visés pour la conversion en plantation, car ce sont des sites déjà perturbés; ils représentent toutefois un habitat de grande qualité pour des espèces comme le lièvre d’Amérique (Lepus americanus Erxleben, 1777), un mammifère clé de la forêt boréale. Nous avons évalué l’effet de la conversion de champs de ferme abandonnés (n = 22) en plantations de conifères (n = 19) sur l’utilisation de l’habitat par le lièvre d’Amérique en utilisant le décompte de fèces et les inventaires de pistes sur la neige. Les deux techniques d’inventaire donnent des résultats similaires : l’utilisation de l’habitat en hiver par les lièvres est plus affectée par le couvert protecteur que par le type d’habitat. À court terme, les plantations n’offrent pas moins de couvert protecteur que les champs de ferme abandonnés. Cependant, lorsqu’elles ont atteint une certaine taille (>=7 m), les plantations sont émondées mécaniquement et perdent leur propriété protectrice. La promotion de techniques de sylviculture qui laisseraient la couverture latérale au-delà d’un seuil critique (70 %) pourrait préserver la qualité de l’habitat du lièvre pendant une portion étendue de la période de rotation de la plantation. [ABSTRACT FROM AUTHOR]

The economic decision model serving as an objective function in forest economics was conceived originally by Faustmann at the stand level. Nevertheless, the tree level seems to be an appropriate scale for analysis, especially for harvesting decisions and certain estimations both at tree and stand levels. However, the Faustmann formula cannot be directly applied to the tree level. The present research has provided certain tree-level formulations of the Faustmann formula, including, in particular, tree expectation value (TEV) and land expectation value (LEV). TEV and tree-level LEV formulas were developed by analyzing the Faustmann formula under deterministic conditions. Unlike previous tree-level decision models presented in the forest economics literature, TEV and tree-level LEV formulas incorporate the expectation value of the land occupied by trees and its variability over time as well as the interaction between trees and their trajectories (cutting age). The proposed formulas were then compared with the Faustmann formula using the first-order condition of optimal harvest age. The TEV and tree-level LEV formulas appeared to be absolutely compatible with the Faustmann formula. The utility of the proposed formulas was then illustrated with application examples, including target diameter, stand expectation value, TEV, LEV, and the value of damage to beech trees or stands in northeastern France. Le modèle de décision économique qui sert de fonction objective en économie forestière a initialement été conçu par Faustmann à l’échelle du peuplement. Néanmoins, l’arbre semble être un niveau d’analyse approprié, spécialement pour les décisions relatives à la récolte et pour certaines estimations, tant à l’échelle de l’arbre que du peuplement. Cependant, la formule de Faustmann ne peut pas être directement appliquée à l’échelle de l’arbre. La présente recherche a fourni certaines formulations de la formule de Faustmann à l’échelle de l’arbre, incluant plus particulièrement la valeur d’attente de l’arbre (VAA) et la valeur d’attente du fond (VAF). Les formules de la VAA et de la VAF à l’échelle de l’arbre ont été développées en analysant la formule de Faustmann sous des conditions déterministes. Contrairement aux différents modèles de décisions à l’échelle de l’arbre décrits dans la littérature, les formules de la VAA et de la VAF à l’échelle de l’arbre incluent la valeur d’attente du fond occupé par les arbres et sa variabilité au fil du temps, de même que l’interaction entre les arbres et leur évolution (âge de récolte). Les formules proposées ont ensuite été comparées à la formule de Faustmann en utilisant la condition de premier ordre de l’âge optimal de la récolte. Les formules de la VAA et de la VAF à l’échelle de l’arbre semblent tout à fait compatibles avec la formule de Faustmann. L’utilité des formules proposées a ensuite été démontrée par des exemples d’application incluant le diamètre cible, la valeur d’attente du peuplement (VAP), la VAA, la VAF et la valeur des dommages aux arbres et aux peuplements de hêtre du nord-est de la France. [ABSTRACT FROM AUTHOR]