Biomass equations for birch in Finland.

摘要

Biomass equations were compiled for the above- and belowground tree components of birch (Betula pendula and B. pubescens). The equations were based on 127 sample trees in 24 birch stands located on mineral soil sites in Finland. The study material consisted of 20 temporary plots and 10 plots from four thinning experiments with different thinning intensities (unthinned, moderately and heavily thinned plots). The equations were estimated for the following individual tree components: stem wood, stem bark, living and dead branches, foliage, stump, and roots. In the data analysis, a multivariate procedure was applied in order to take into account the statistical dependency among the equations. Three multivariate variance component models were constructed for the aboveground biomass components, and one for the belowground biomass components. The multivariate model 1 was mainly based on tree diameter and height, and in the multivariate models 2 and 3 additional commonly measured tree variables were used. The equations provided logical biomass predictions for a number of tree components, and were comparable with other functions used in Finland and Sweden. The applied statistical method generated equations that gave more reliable biomass estimates than the equations presented earlier. Furthermore, the structure of the multivariate models enables more flexible application of the equations, especially for research purposes.