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Development of height-age and site index functions for even-aged interior douglas-fir in British Columbia

Author(s) or contact(s): J.S. Thrower and J.W. Goudie
Source: Research Branch
Subject: Growth and Yield
Series: Research Note
Other details:  Published 1992. Hardcopy is available.


Height-age and site-index curves were developed from stem analysis of 262 dominant trees in 68 plots located in even-aged Douglas-fir stands in the interior of British Columbia. Study plots were located throughout the geographic range of the species in the Interior Douglas-fir, Interior Cedar-Hemlock, and Sub-Boreal Spruce biogeoclimatic zones. Plots ranged in site index from 7.8 to 30.4 m at 50 years breast-height age, and in age from 64 to 347 years. A polymorphic conditioned logistic function was selected for predicting height as a function of breast-height age and site index; a linear model was selected for predicting site index as a function of height and breast-height age. The height-age and site-index curves were slightly different from polymorphic curves developed from stem analysis data in nearby northern Idaho and greatly different from existing anamorphic curves developed from temporary sample plot data in the interior of British Columbia.

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Updated May 29, 2009