DIAMETER-BASED BIOMASS REGRESSION-MODELS IGNORE LARGE SAPWOOD-RELATED VARIATION IN SITKA SPRUCE

Improvements in prediction of foliage and branch biomass were sought by comparing multiple regression models using stem diameter, sapwood radial thickness, and tree height as independent variables in stands of Picea sitchensis in SE Alaska. Stem biomass equations were not improved by including tree height or sapwood thickness. Use of a diameter-sapwood thickness sampling matrix for construction of biomass equations may reduce the sample size needed and result in equations with wider application. -from Author