Percent stocking models for four major Alberta tree species
Authors: Yang, Yuqing; Huang, Shongming; Dick Dempster, W.R.
Source: Forestry, Volume 81, Number 5, 1 December 2008 , pp. 599-615(17)
Publisher: Oxford University Press
Abstract:Based on stem-mapped permanent sample plot data, percent stocking dynamics were modelled for four major tree species in the province of Alberta, Canada: trembling aspen (Populus tremuloides Michx.), white spruce (Picea glauca (Moench) Voss), lodgepole pine (Pinus contorta Dougl. var. latifolia Engelm.) and black spruce (Picea mariana (Mill.) B.S.P.). Percent stocking was defined as the percentage of 10-m2 plots occupied by at least one tree with a minimum height of 1.3 m. The difference equation technique was applied for model fitting. Site index was a significant predictor in all models. Heterogeneous residual variances present in the aspen, white spruce and lodgepole pine models were corrected by applying a power-of-the-mean variance function. Serial correlation due to repeated measurements was considered through a linear log covariance structure. A percent stocking index, defined as the percent stocking at 50 years total age, was derived from the fitted percent stocking models and used for assessing species interactions in mixed-species stands. The presence of other species did not appear to affect percent stocking changes over time for aspen and black spruce. However, white spruce percent stocking was reduced when growing together with aspen, and lodgepole pine percent stocking was negatively affected by the presence of aspen, white spruce and black spruce.
Document Type: Research article
Publication date: 2008-12-01
- Forestry publishes refereed papers on all aspects of research, practice and policy that promote the sustainable development of forests, woodlands and trees. In considering suitability for publication attention is given to both the originality of contributions and their practical application. Preference is usually given to work undertaken in the temperate and/or boreal zones; only articles of exceptional merit from tropical zones will also be considered.