The Influence of Stocking and Stand Composition on Productivity of Boreal Trembling Aspen-White Spruce Stands

We analyzed productivity, in terms of periodic annual increment (PAI) in volume, of pure and mixed unmanaged naturally regenerated boreal stands mainly comprised of Populus tremuloides Michx. (trembling aspen) and Picea glauca (Moench) Voss (white spruce) ranging from 25–260 years old, in Alberta, C...

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Bibliographic Details
Published in:Forests 2015-12, Vol.6 (12), p.4573-4587
Main Authors: Reyes-Hernández, Valentín, Comeau, Philip
Format: Article
Language:English
Subjects:
Combining ability
Competition
Composition
Deciduous trees
Density
Ecology
Forests
Growth rate
Independent variables
Phenology
Productivity
Regression analysis
Regression models
Species
Stocking
Trees
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Summary:We analyzed productivity, in terms of periodic annual increment (PAI) in volume, of pure and mixed unmanaged naturally regenerated boreal stands mainly comprised of Populus tremuloides Michx. (trembling aspen) and Picea glauca (Moench) Voss (white spruce) ranging from 25–260 years old, in Alberta, Canada. Measures of density, site occupancy (Reineke’s stand density index-SDI), height, and site quality were evaluated in non-linear regression models aiming to explain the variation in PAI for the separate component species and for the entire stand. Analyses also included examination of the influence of stand composition. Results indicated a positive effect of both density of deciduous trees and of the percentage of deciduous tree stand basal area on trembling aspen volume PAI. White spruce PAI was positively influenced by spruce and aspen basal area, although effects of aspen were small. Height of both aspen and spruce were the most consistent independent variables in the models tested. Maximum PAI was achieved in mixed stands when site occupancy of both species was at its maximum, indicating the ecological combining ability of these two species. Variation in maximum stocking densities (i.e., stockability) has a strong influence on increment in these forests and is a major factor leading to increased productivity of mixed compared to pure stands.
ISSN:1999-4907
1999-4907
DOI:10.3390/f6124387