Decision-support program “EnerTree” for analyzing forest residue recovery options

The extraction of residues from the harvesting processes for energy production is common practice particularly in Finland and Sweden. Furthermore, the removal is expected to increase also in Central European and the Baltic countries. The extraction of forest biomass provides an extra source of income for the forest owner and positively affects the economy of the forest operation, scenic values and reduces chances of an insect pest outbreak. At the same time, the harvesting of forest residues affects the ecological state of the forest site both in the long term and short term. For example, nutrient depletion might have a negative effect on the future growth of the stand and additionally may be detrimental for biodiversity. The impact on the stand can be manipulated by either seasoning the residues so that needles are left in the stand or through compensation fertilizing using ash.The individual forest owner is faced with a large number of options regarding forest fuel recovery though they have only limited knowledge of the potential impact on the forest ecosystems. Consequently, they will probably have difficulties making a decision. Another aspect is that various forest owners have different preferences regarding economical or ecological factors. A computer-based decision support program is therefore developed to assist the forest owners in making a decision concerning the utilisation of wood for energy. The program deals with a large number of aspects such as revenues from sales, environmental effects and silvicultural benefits. The forest owner provides the program with the basic data of the forest site such as site classification, basal area, mean height and diameter. Thereafter, the forest owner can rank their personal preferences, for instance, how they weigh the importance of net income, nutrient loss, biodiversity, scenic value or the risk of insect pests. The results of various treatment options are then presented to the forest owner, and recommendations for further additional treatment (amount of fertilizer) will also be provided.The decision support program is a unique tool to assist the forest owner to make a comprehensive decision on whether they should harvest forest residues on their forest site and, if they decide to do so, what fuel recovery option will be the most beneficial for them. The EnerTree decision support program also provides an excellent opportunity to convey knowledge gained in research to the forest owner by very practical and understandable means.