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Crown allometry and application of the pipe model theory to white spruce (Picea glauca (Moench) Voss) and aspen (Populus tremuloides Michx.) in the western boreal forest of Canada
Crown allometry and application of the pipe model theory to white spruce (Picea glauca (Moench) Voss) and aspen (Populus tremuloides Michx.) in the western boreal forest of Canada
- Source :
- Canadian Journal of Forest Research. February 1, 2016, p262, 12 p.
- Publication Year :
- 2016
-
Abstract
- White spruce (Picea glauca (Moench) Voss) and aspen (Populus tremuloides Michx.) from unmanaged stands in the boreal forest of Alberta, Canada, were examined for two of the main structural assumptions in the process-based model CROBAS: (i) a constant allometric relationship between foliage mass and crown length and (ii) a constant relationship between foliage mass and sapwood area. We evaluated these relationships at both at the whole-crown and within-crown levels. Results indicated that for both species, a constant allometric relationship between foliage mass and crown length was maintained at the whole-crown level over a period exceeding the peak mean annual increment of each species. Within the crowns of spruce, foliage mass accumulated faster near the tree apex as total crown length increased. For aspen, the increase in foliage mass per unit crown length for any section within the crown showed greater similarity to the relationship observed at the whole-crown level. The assumption of a constant relationship between foliage mass and sapwood area at the crown base generally held for spruce but showed considerable variation for any given diameter class. For aspen, this assumption did not appear to be appropriate. For both species, there was more foliage mass per unit sapwood area with increasing height from the ground for nearly all tree size classes. This latter finding was in conflict with the pipe model theory but could not be explained by the hydraulic theory of crown architecture, which predicts a decrease in the ratio of foliage mass to sapwood area with increasing path length. Key words: pipe model, crown allometry, foliage mass, Picea glauca, Populus tremuloides. A partir d'epinettes blanches (Picea glauca (Moench) Voss) et de peupliers faux-tremble (Populus tremuloides Michx.) provenant de peuplements boreaux non amenages de l'Alberta, nous avons etudie deux des principales hypotheses structurales du modele fonctionnel CROBAS : (i) une relation allometrique constante entre la masse foliaire et la longueur de la cime, et (ii) une relation constante entre la masse foliaire et la surface d'aubier. Nous avons evalue ces relations aux echelles de la cime entiere et de l'interieur de la cime. Les resultats indiquent que pour les deux especes, une relation allometrique constante entre la masse foliaire et la longueur de la cime a ete maintenue a l'echelle de la cime entiere au cours d'une periode depassant l'age d'atteinte de l'accroissement annuel moyen maximal de chaque espece. Dans les cimes d'epinette, la masse foliaire s'accumulait plus rapidement pres de l'apex de l'arbre a mesure que la longueur totale de la cime augmentait. Chez le peuplier, l'augmentation de la masse foliaire par unite de longueur de cime de toutes les sections de la cime ressemblait davantage a la relation observee a l'echelle de la cime entiere. L'hypothese d'une relation constante entre la masse foliaire et la surface d'aubier a la base de la cime a generalement ete validee pour l'epinette, mais sa variation etait considerable pour toutes les classes de diametre. Dans le cas du peuplier, cette hypothese ne semblait pas appropriee. Chez les deux especes, la masse foliaire par unite de surface d'aubier augmentait avec la hauteur par rapport au sol pour a peu pres toutes les classes de taille d'arbre. Ce dernier resultat contredit la theorie du modele tubulaire, mais ne peut etre explique par la theorie hydraulique de l'architecture de la cime qui predit une diminution du rapport entre la masse foliaire et la surface d'aubier avec l'augmentation de la distance de transport. [Traduit par la Redaction] Mots-cles : modele tubulaire, allometrie de la cime, masse foliaire, Picea glauca, Populus tremuloides.<br />Introduction CROBAS (Makela 1997) is a process-based model that not only is based on the principle of carbon balance, but also incorporates principles related to the functional balance (Davidson 1969; [...]
Details
- Language :
- English
- ISSN :
- 00455067
- Database :
- Gale General OneFile
- Journal :
- Canadian Journal of Forest Research
- Publication Type :
- Academic Journal
- Accession number :
- edsgcl.442907014
- Full Text :
- https://doi.org/10.1139/cjfr-2015-0165