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Determining the feasibility of a large-scale afforestation program is one approach being investigated by the Government of Canada to increase Canada's potential to sequester carbon from the atmosphere. Large-scale afforestation, however, requires knowledge of where it is suitable to establish and grow trees. Spatial models based on Boolean logic and/or statistical models within a geographic information system may be used for this purpose, but empirical environmental data are often lacking, and the association of these data to land suitability is most often a subjective process. As a solution to this problem, this paper presents a fuzzy-logic modeling approach to assess land suitability for afforestation of hybrid poplar (Populus spp.) over the Prairie Provinces of Canada. Expert knowledge regarding the selection and magnitudes of environmental variables were integrated into fuzzy rule sets from which estimates of land suitability were generated and presented in map form. The environmental variables selected included growing season precipitation, climate moisture index, growing degree days, and Canada Land Inventory capability for agriculture and elevation. Approximately 150,000 km2, or 28% of the eligible land base within the Prairie Provinces was found to be suitable for afforestation. Accuracy assessments conducted with fuzzy accuracy methods provided a more descriptive assessment of the resulting land suitability map than figures generated from a more conventional Boolean-based accuracy measure. Modeling, mapping and accuracy assessment issues were identified for future extension of this work to map hybrid poplar land suitability over Canada.

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This study presents a model that assesses the potential impact of a new alien insect species, Sirex noctilio Fabricius, on pine timber supply and harvest activities in eastern Canada. We integrate the spread of S. noctilio with a broad-scale growth and harvest allocation model. Projections of pine mortality range between 25 Â 10 6 and 115 Â 10 6 m 3 over 20 years depending on S. noctilio spread and impact assumptions. Our model suggests Ontario could experience the highest, most immediate losses (78% of the potential losses across eastern Canada), with Quebec sustaining most of the rest of the losses over the next 20 years. Potential losses of $86 to $254 million per year are simulated after 20 years. The net present value of total harvest losses after 28 years of outbreak ranges between $0.7 to $2.1 billion. Adaptation policies decrease shortterm losses by 46%-55% and delay larger harvest failures by 9-11 years. Without harvest adaptation, failures to maintain annual allowable cut levels may occur once the total area infested exceeds 15 Â 10 6 ha. While better understanding and representing S. noctilio behaviour will involve a significant effort, there is a strong demand by policy makers for this kind of information.Résumé : Cette étude présente un modèle qui évalue l'impact potentiel d'une nouvelle espèce d'insecte exotique, Sirex noctilio Fabricius, sur les stocks de bois de pin et les activités de récolte dans l'est du Canada. Les auteurs ont intégré la propagation de S. noctilio à un modèle de croissance à grande échelle et d'allocation de la récolte. Les projections concernant la mortalité du pin varient de 25 Â 10 6 and 115 Â 10 6 sur 20 ans selon les hypothèses de propagation et d'impact de S. noctilio. Leur modèle indique que l'Ontario pourrait subir les pertes les plus élevées très tôt (78 % des pertes potentielles de tout l'est du Canada) et le Québec, presque toutes les pertes à venir au cours de la période s'étendant sur les 20 prochaines années. Les pertes annuelles pourraient atteindre 86-254 millions $ après 20 ans. La valeur actualisée nette des pertes totales de réc-olte après 28 années d'épidémie varie de 0,7 à 2,1 milliards $. Des stratégies d'adaptation diminueraient les pertes à court terme de 46-55 % et retarderaient les pires récoltes de 9-11 ans. Sans adaptation de la récolte, l'incapacité à maintenir les niveaux de possibilité annuelle de coupe pourrait survenir lorsque la superficie totale infestée dépassera 15 Â 10 6 ha. Bien que d'importants efforts restent à faire pour mieux comprendre et représenter le comportement de S. noctilio, il y a une forte demande de la part des décideurs pour ce type d'informations.[Traduit par la Rédaction]