A retrospective study was conducted in 1993 that quantified the effects of overstory shading on both spruce weevil (Pissodesstrobi (Peck)) and leader growth on white spruce (Piceaglauca (Moench) Voss × Piceaengelmannii Parry ex Engelm.). The study was undertaken in the interior of British Columbia, where the weevil is causing extensive damage to plantations of white spruce. Shading on the spruce trees was measured by calculating the light interception index and percent overstory cover on individual white spruce trees at the centre of a 2.52 m radius plot. Current weevil attacks decreased significantly with increasing overstory cover, and the rate of decrease was greater in heavily versus lightly attacked stands. Shading also decreased leader growth. These results indicate that the optimum level of overstory removal may be a compromise between volume loss due to overstory competition and volume gain due to decreased weevil attacks.

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We examined the growth of white spruce planted underneath a 33-year-old stand of trembling aspen following thinning and fertilization. Thinning the stand to 2000 stems·ha -1 resulted in increased light reaching spruce seedlings and significant increases in height and diameter growth of seedlings over that observed in either the unspaced or 3000 stems·ha -1 treatments. Fertilization (applied 3 years prior to planting) stimulated development of understory vegetation and did not benefit the planted spruce. While growth was improved by thinning, the benefits of the thinning treatment to establishment of white spruce appeared to be small, and amounted to increasing seedling height from 62 cm (unthinned) to 73 cm (thinned to 1000 or 2000 stems·ha -1 ) at the end of 5 years. Results indicated that when stands are thinned for the purpose of accelerating growth rates of underplanted spruce, residual basal areas above 25 m 2 ·ha -1 should be retained to suppress growth of understory vegetation. Comparison of height at age 5 for seedlings planted under untended stands at Fort Nelson with three sites near Dawson Creek indicated no differences between locations, when height at the time of planting was included as a covariate.Résumé : Nous avons étudié la croissance des épinettes blanches plantées sous un peuplement de peuplier faux-tremble âgé de 33 ans à la suite d'une éclaircie et d'une fertilisation. Le fait d'éclaircir le peuplement à 2000 tiges·ha -1 a procuré plus de lumière aux semis d'épinette et a significativement augmenté leur croissance en hauteur et en diamètre comparativement à ce qui a été observé dans le traitement témoin ou l'éclaircie à 3000 tiges·ha -1 . La fertilisation (appliquée 3 ans avant la plantation) a stimulé le développement de la végétation de sous-bois mais n'a pas bénéficié aux semis d'épinette. Bien que l'éclaircie ait amélioré la croissance, les effets bénéfiques de ce traitement sur l'établissement de l'épinette semblent peu importants et se traduisent par une augmentation de la hauteur des semis de 62 cm (sans éclaircie) à 73 cm (éclaircie à 1000 ou 2000 tiges·ha -1 ) après 5 ans. Les résultats indiquent que lorsque les peuplements sont éclaircis dans le but d'accélérer le taux de croissance des épinettes plantées en sous-étage, la surface terrière résiduelle devrait être maintenue au-dessus de 25 m 2 ·ha -1 pour supprimer la croissance de la végétation de sous-bois. La comparaison de la hauteur à 5 ans de semis plantés sous des peuplements non traités à Fort Nelson avec les données provenant de trois sites près de Dawson Creek indique qu'il n'y a pas de différence entre ces endroits lorsque la hauteur au moment de la plantation est incluse comme covariable.[Traduit par la Rédaction] Comeau et al. 2283

The 7th North American Forest Ecology Workshop, consisting of 149 presentations in 16 oral sessions and a poster session, reflected a broad range of topical areas currently under investigation in forest ecology and management. There was an overarching emphasis on the role of disturbance, both natural and anthropogenic, in the dynamics of forest ecosystems, and the recognition that legacies from past disturbances strongly influence future trajectories. Climate was invoked as a major driver of ecosystem change. An emphasis was placed on application of research findings for predicting system responses to changing forest management initiatives. Several “needs” emerged from the discussions regarding approaches to the study of forest ecosystems, including (1) consideration of variable spatial and temporal scales, (2) long-term monitoring, (3) development of universal databases more encompassing of time and space to facilitate meta-analyses, (4) combining field studies and modeling approaches, (5) standardizing methods of measurement and assessment, (6) guarding against oversimplification or overgeneralization from limited site-specific results, (7) greater emphasis on plant-animal interactions, and (8) better alignment of needs and communication of results between researchers and managers.

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