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Impact of competitor species composition on predicting diameter growth and survival rates of Douglas-fir trees in southwestern Oregon

Canadian Journal of Forest Research

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Abstract

Mixed conifer and hardwood stands in southwestern Oregon were studied to explore the hypothesis that competition effects on individual-tree growth and survival will differ according to the species comprising the competition measure. Likewise, it was hypothesized that competition measures should extrapolate best if crown-based surrogates are given preference over diameter-based (basal area based) surrogates. Diameter growth and probability of survival were modeled for individual Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) trees growing in pure stands. Alternative models expressing one-sided and two-sided competition as a function of either basal area or crown structure were then applied to other plots in which Douglas-fir was mixed with other conifers and (or) hardwood species. Crown-based variables outperformed basal area based variables as surrogates for one-sided competition in both diameter growth and survival probability, regardless of species composition. In contrast, two-sided competition was best represented by total basal area of competing trees. Surrogates reflecting differences in crown morphology among species relate more closely to the mechanics of competition for light and, hence, facilitate extrapolation to species combinations for which no observations are available.

Additional Publication Details

Publication type:
Article
Publication Subtype:
Journal Article
Title:
Impact of competitor species composition on predicting diameter growth and survival rates of Douglas-fir trees in southwestern Oregon
Series title:
Canadian Journal of Forest Research
Volume
31
Issue:
12
Year Published:
2001
Language:
English
Contributing office(s):
Forest and Rangeland Ecosystem Science Center
Description:
p. 2237-2247
Larger Work Type:
Article
Larger Work Subtype:
Journal Article
Larger Work Title:
Canadian Journal of Forest Research
First page:
2237
Last page:
2247
Number of Pages:
11