A PRELIMINARY CROWN BIOMASS TABLE FOR EVEN-AGED PICEA-ABIES STANDS INSWITZERLAND

The assessment of biomass and biomass changes due to environmental inf luences 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 resultin g predictions more precise. A hybrid method is described to derive reg ressions for site quality, needle and branch biomass for individual Pi cea abies trees. By using Swiss stand table data on tree density distr ibutions, a traditional yield table for branch and needle biomass is c omputed, and from these, regressions are derived which use only age an d site quality as independent variables. Three tables for typical site qualities are given. The tabulated regressions include pseudo-probabi lity values, coefficients of determination and estimated standard erro r for the overall models. These biomass fractions comprise a varying f raction of the tree, being important at low ages and much less so at l ater ages.