Biomass functions for Scots pine, Norway spruce and birch in Finland

Abstract

In this study, biomass models for the above- and belowground tree components of Scots pine (Pinus sylvestris), Norway spruce (Picea abies [L.] Karst) and birch (Betula pendula and Betula pupescens) were compiled, and complementary equations developed for average stem density. The models were based on 1684 sample trees collected in 101 stands located on mineral soil sites, comprising 41 pine, 36 spruce and 24 birch stands. The study material consisted of subjectively selected experiments and temporary sample plots representing a wide range of stand and site conditions in Finland.The models were estimated for individual tree components: stem wood, stem bark, living and dead branches, foliage, stump, and roots. A linear mixed model technique was applied in analyzing the data, and logarithmic transformation was used to convert the model to a linear form. Two model sets were developed. The simple models were mainly based on tree diameter and height, and the full models on all the variables measured in the Finnish national forest inventory. The generalization and applicability of the models may be restricted by the fact that the study material was not an objective, representative sample of the tree stands in Finland, and some tree components (stump and roots and birch foliage) were poorly represented. Despite these shortcomings, the models provided uniform biomass predictions for a number of tree components, apart from stump and root biomass for pine, and were comparable with other functions used in Finland and Sweden (Hakkila 1972, 1979, 1991, Marklund 1988, Petersson 1999, 2006).