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International Journal of Forestry Research
Volume 2012, Article ID 573640, 12 pages
http://dx.doi.org/10.1155/2012/573640
Research Article

Identifying and Characterizing Important Trembling Aspen Competitors with Juvenile Lodgepole Pine in Three South-Central British Columbia Ecosystems

1BC Ministry of Forests, Lands and Natural Resource Operations, 200-640 Borland Street, Williams Lake, BC, Canada V2G 4T1
2J. Heineman Forestry Consulting, 2125 E. 5th Avenue, Vancouver, BC, Canada V5N 1M5
3International Statistics and Research Corp., P.O. Box 39, Brentwood Bay, BC, Canada V8M 1R3

Received 12 October 2011; Revised 20 December 2011; Accepted 3 January 2012

Academic Editor: Han Chen

Copyright © 2012 Teresa A. Newsome et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Critical height ratios for predicting competition between trembling aspen and lodgepole pine were identified in six juvenile stands in three south-central British Columbia ecosystems. We used a series of regression analyses predicting pine stem diameter from the density of neighbouring aspen in successively shorter relative height classes to identify the aspen-pine height ratio that maximized R2. Critical height ratios varied widely among sites when stands were 8–12 years old but, by age 14–19, had converged at 1.25–1.5. Maximum R2 values at age 14–19 ranged from 13.4% to 69.8%, demonstrating that the importance of aspen competition varied widely across a relatively small geographic range. Logistic regression also indicated that the risk of poor pine vigour in the presence of aspen varied between sites. Generally, the degree of competition, risk to pine vigour, and size of individual aspen contributing to the models declined along a gradient of decreasing ecosystem productivity.