The assessment of biomass and biomass changes due to environmental influences requires not only stem or merchantable mass, but also branches and needles. They have been of relatively little importance to forest managers to date, but their inclusion in models can make the resulting predictions more precise. A hybrid method is described to derive regressions for site quality, needle and branch biomass for individual Picea abies trees. By using Swiss stand table data on tree density distributions, a traditional yield table for branch and needle biomass is computed, and from these, regressions are derived which use only age and site quality as independent variables. Three tables for typical site qualities are given. The tabulated regressions include pseudo-probability values, coefficients of determination and estimated standard error for the overall models.
These biomass fractions comprise a varying fraction of the tree, being important at low ages and much less so at later ages.