Modelling the stump biomass of stands for energy production using a harvester data management system

The value and volumes of industrial stump wood fuel supply are increasing. In 2006, the consumption of stump wood for energy generation in Finland was equivalent to more than 900 GWh. Accurate estimates of the below-ground biomass of trees are important when estimating the potential use of stumps as bioenergy sources. In this study the biomass model by Marklund {(1988). Biomassafunktioner för tall, gran och björk i Sverige. [Biomass Functions for Pine, Spruce and Birch in Sweden], Rep. No 45, Department of Forest Survey, Swedish University of Agricultural Sciences (in Swedish)} was tested at the operational level of stump wood procurement and a calibrated biomass model was developed to predict the stump biomass of local stands. Regression analysis was applied to best fit model using forest harvester data as the source of local information. The independent variables of the best fit model were the cumulative sum of biomass estimates from Marklund, and the cumulative sum of the square of the diameter at 30% relative height. In tests of goodness of fit for the linear relationships, better reliability of the estimates obtained with the model was presented as a root mean square error (RMSE) of the stand stump biomass. The adjusted R2 value obtained was 60% which was higher than the adjusted R2 values of the stump biomass model (52%) obtained by Marklund. Thus, the data management system can be used to produce more accurate information for planning and business management of energy production.