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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.)

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.)

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.)

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.)

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.)

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.)

Presents a study that examined whether computationally demanding competition indices outperform traditional indices in predicting mean basal area increment in a black spruce in northeastern Quebec. Background on black spruce; Materials and methods; Expectation on the competition indices used in the study.

Investigates the evolution pattern of the diameter structure of boreal black spruce stands originating from fire or logging in Quebec. Comparison of stands originating from fire and from logging; Impact of the widespread careful logging on the stands; Reconstitution of the dynamics of 40- to 90-year-old stands.

Giant circular patterns of low tree density in black spruce (Picea mariana) stands were investigated in the Abitibi region of Quebec. We used dendrochronological techniques to test the hypotheses that ring patterns of low tree density are caused either by radial changes in spruce mortality or productivity. Seven circles were sampled. We found no gradient in the age of spruce along circle radii suggesting that rings of low tree density do not expand radially, that is, they are not spatially dynamic entities. The results indicate, however, that spruce trees were less dense and productive within the rings due to excessive moisture in the soil. Measurements of surface elevation, thickness of the organic layer and elevation of the mineral substrate across the circles revealed that a depression in the mineral soil beneath the rings traps the surface water and this area of poor drainage seems to prevent the establishment of black spruce within the rings. The origin of the ring-shaped depressions was attributed to geological or geomorphological causes.Key words: black spruce, Picea mariana, mortality, productivity, rings, geomorphology.Des formations circulaires géantes caractérisées par une densité arborescente faible ont été étudiées dans des peuplements d'épinettes noires (Picea mariana) de l'Abitibi au Québec. Les hypothèses liées à un processus de mortalité radiale ou à une baisse de productivité dans l'anneau ont été documentées dans sept cercles à l'aide de techniques dendrochronologiques. L'absence d'un gradient d'âge des épinettes ne supporte pas une expansion radiale des anneaux. Par contre, les résultats indiquent que la productivité et la densité des épinettes sont plus faibles dans l'anneau à cause de l'humidité excessive du sol à cet endroit. Des relevés topographiques de la surface du sol, de l'épaisseur de la couche organique et de l'altitude du substrat minéral ont démontré l'existence d'une dépression dans le sol minéral sous l'anneau. Cette dépression, dans un environnement comme celui-ci où la nappe phréatique est près de la surface, piège les eaux de surface et maintient l'humidité excessive du sol prévenant ainsi l'établissement de l'épinette noire. Les anneaux sont donc statiques et l'origine de la dépression annulaire relève de causes géologiques ou géomorphologiques.Mots clés : épinette noire, Picea mariana, mortalité, productivité, anneau, géomorphologie. [ABSTRACT FROM AUTHOR]