GENERALIZED VERSUS SITE-SPECIFIC BIOMASS REGRESSION EQUATIONS FOR PSEUDOTSUGA-MENZIESII VAR MENZIESII AND THUJA-PLICATA IN COASTAL BRITISH-COLUMBIA

Site-specific biomass regression equations developed for Pseudotsuga menziesii var. menziesii and Thuja plicata by destructive sampling of individual trees in southwestern British Columbia were compared to generalized equations developed from the large data-set of Standish et al. (Standish, J. T., Manning, G. H. & Demaerschalk, J. P., 1985, Development of biomass equations for British Columbia tree species. Report BC-X-264, Canadian Forestry Service, Victoria, BC) for trees growing over a wide geographic area in western British Columbia. In the case of Pseudotsuga, equations developed for trees growing on poor sites were also compared to those for trees growing on good sites. For Pseudotsuga, both geographical and site-specific variations in tree growth significantly influenced the parameters in biomass regression equations. These influences are likely to be most noticeable for sites exhibiting extremely low productivity. For Thuja, geographical variations also significantly influenced the parameters in biomass regression equations.