The effect of size and competition on tree growth rate in old-growth coniferous forests

Canadian Journal of Forest Research



Tree growth and competition play central roles in forest dynamics. Yet models of competition often neglect important variation in species-specific responses. Furthermore, functions used to model changes in growth rate with size do not always allow for potential complexity. Using a large data set from old-growth forests in California, models were parameterized relating growth rate to tree size and competition for four common species. Several functions relating growth rate to size were tested. Competition models included parameters for tree size, competitor size, and competitor distance. Competitive strength was allowed to vary by species. The best ranked models (using Akaike’s information criterion) explained between 18% and 40% of the variance in growth rate, with each species showing a strong response to competition. Models indicated that relationships between competition and growth varied substantially among species. The results also suggested that the relationship between growth rate and tree size can be complex and that how we model it can affect not only our ability to detect that complexity but also whether we obtain misleading results. In this case, for three of four species, the best model captured an apparent and unexpected decline in potential growth rate for the smallest trees in the data set.
Publication type Article
Publication Subtype Journal Article
Title The effect of size and competition on tree growth rate in old-growth coniferous forests
Series title Canadian Journal of Forest Research
DOI 10.1139/x2012-142
Volume 42
Issue 11
Year Published 2012
Language English
Publisher NRC Research Press
Contributing office(s) Western Ecological Research Center, John Wesley Powell Center for Analysis and Synthesis
Description 13 p.
Larger Work Title Canadian Journal of Forest Research
First page 1983
Last page 1995
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