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The effect of light availability and basal area on cone production in Abies balsamea and Picea
 

Summary: The effect of light availability and basal area on
cone production in Abies balsamea and Picea
glauca
David F. Greene, Christian Messier, Hugo Asselin, and Marie-Josée Fortin
Abstract: Mean annual seed production is assumed to be proportional to basal area for canopy trees, but it is not
known if subcanopy trees produce fewer seeds than expected (given their size) because of low light availability. Ovu-
late cone production was examined for balsam fir (Abies balsamea (L.) Mill.) and white spruce (Picea glauca
(Moench) Voss) in 1998 and for balsam fir in 2000 in western Quebec using subcanopy stems, near or far from forest
edges, or (at one site) planted white spruce trees in fully open conditions. A very simple light model for transmission
through mature trembling aspen (Populus tremuloides Michx.) crowns and through boles near forest edges was devel-
oped to account for the effect of light receipt on cone production. The enhanced light near forest edges (e.g., recent
clearcuts) leads to about a doubling of cone production for subcanopy stems. The minimum subcanopy height for cone
production far from an edge is about 10 m for balsam fir and 14 m for white spruce, with these minima decreasing
near edges. By contrast, the minimum height for white spruce in a plantation (full light) is about 3 m. Accounting for
light receipt leads to an increase in the explained variance.
Key words: balsam fir, cone production, light model, regressions, subcanopy stems, white spruce.
Résumé : La production annuelle moyenne de graines est proportionnelle à la surface terrière pour les arbres compo-
sant la canopée. Cependant, il reste à démontrer que des individus croissant sous couvert produisent moins de graines
que prévu (en fonction de leur taille) en raison de la faible disponibilité de lumière. La production de cônes a été exa-
minée pour le sapin baumier (Abies balsamea (L.) Mill.) et l'épinette blanche (Picea glauca (Moench) Voss) en 1998

  

Source: Asselin, Hugo - Chaire de recherche du Canada en foresterie autochtone, Département des sciences du développement humain et social, Université du Québec en Abitibi-Témiscamingue
Fortin, Marie Josee - Department of Ecology and Evolutionary Biology, University of Toronto

 

Collections: Environmental Sciences and Ecology