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A set of speculative and exploratory treatments was applied to a severely repressed strand of 18-year-old lodgepole pine in 1979. After 19 years, various combinations of row thinning, hand thinning and fertilization have provided a remarkable range of results, with the best treatments gaining 3 m in top height and 8 m in apparent site index (reference age 50 years breast height) over the untreated stand. The best results were observed where both growing space and nutrition were improved. Extrapolation of the results using simulation suggests large gains in yield at harvest.Key words: thinning, fertilization, lodgepole pine, repression, stagnation Une série de traitements expérimentaux et exploratoires a été appliquée à un peuplement très opprimé de pin lodgepole âgé de 18 ans en 1979. Dix-neuf ans plus tard, diverses combinaisons d'éclaircie en rangée, d'éclaircie manuelle et de fertilisation ont démontré un spectre remarquable de résultats, où les meilleurs traitements ont démontré des gains de 3 m dans la hauteur des houppiers et de 8 m dans l'indice apparent de la station ( l'âge de référence étant de 50 ans à hauteur de poitrine) par rapport au peuplement non traité. Les meilleurs résultats ont été observés là où l'espacement et la nutrition ont été tous deux améliorés. L'extrapolation des résultats au moyen d'une simulation laisse entrevoir d'importants gains au niveau du rendement au moment de la récolte.

This paper highlights the potential for moving from stocking standards as simple tools for administering contractual or policy-based stocking requirements to regeneration standards that play an active role in forest management. A framework is introduced for developing simplified models on which regeneration standards can be based. A case study for boreal mixedwoods is presented in which simplified models based on quadrat stocking summaries are used to predict total yield and species composition for various admixtures of white spruce and trembling aspen. It is suggested that these values can be used to satisfy both the evaluation of basic reforestation obligations and cut block level contributions to landscape level species composition objectives.Key words: regeneration standards, stocking standards, surveys, simulation, mixedwood management, forest management objectives RÉSUMÉCet article fait état de la possibilité de passer de l'utilisation des normes de densité relative en tant que référence usuelle de gestion d'un contrat ou d'une directive portant sur le nombre de semis par unité de surface, à des normes de régénération ayant un rôle actif en aménagement forestier. Un cadre de référence pour le développement de modèles simplifiés est présenté et pour lesquels les normes de régénération peuvent être retenues. Une étude de cas sur les forêts boréales mixtes est présentée pour laquelle des modèles simplifiés établis à partir de sommaires de stocking par quadrant sont utilisés pour prédire le rendement total et la composition en espèces dans le cas de différentes compositions d' épinette blanche et de peuplier faux-tremble. Il est suggéré que ces valeurs peuvent être utilisées pour répondre à la fois à l' évaluation des exigences de base en matière de régénération et pour le niveau de contribution d'un bloc de coupe aux objectifs de composition par espèce dans l' écosystème.

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A localized version of the Forest Vegetation Simulator (FVS) individual tree growth model was developed to simulate stand level impacts under a variety of uneven-aged management regimes in old-growth interior spruce-subalpine fir forests near Prince George British Columbia. Options for using uneven-aged management to satisfy a range of management objectives were simulated using different sets of BDq regulation parameters, and by varying species composition and rules for reserve trees. The greatest timber yields were attained by promoting the highest possible spruce component, using high q ratios, low to moderate maximum diameters and 20 to 25 year cutting cycles, and allowing no reserves. Using strategies to promote stand structures maintaining some old-growth attributes resulted in much lower timber yields.

Controlled mixtures of trembling aspen (Populus tremuloides Michx.) and white spruce (Picea glauca [Moench] Voss) were established in 1989 at two locations in the Boreal White and Black Spruce (BWBS) biogeoclimatic zone in northeastern British Columbia. The initial study design of three aspen treatment densities of 0, 5000, and 10000 stems per hectare was expanded by reducing existing densities of aspen on a subset of plots to 1000 and 2000 stems per hectare. A random-coefficients regression model was used to analyze height and diameter growth trends for aspen and spruce 13–17 years after establishment. White spruce grown without aspen had significantly greater rates of height and diameter growth. There were no significant differences in spruce growth between the 5000 and 10000 aspen stems per hectare treatments. Differences in spruce height and diameter growth did not consistently display a pattern of declining growth as aspen density increased from 1000 to 10000 stems per hectare. Aspen responded to aspen density reduction by increased diameter growth of the remaining stems.The Mixedwood Growth Model was used to predict future growth of the experimental stands. Yield projections indicated that a total productivity gain of 21% may be achieved for mixtures compared to a pure spruce scenario. Over the range of conditions studied, spruce comprised approximately 40% of the total volume in mixed stands. These initial results will improve the assessments of the relative contributions that pure- and mixed-species management regimes may offer to achieving forest-level objectives.

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