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Economic-ecological optimization of timber and bioenergy production and sequestration of carbon in Norway spruce stands

Academy of Finland 2008-2011

Responsible leader: Olli Tahvonen, professor, Finnish Forest Research Institute
Partners: Annikki Mäkelä, University of Helsinki, Heljä-Sisko Helmisaari, FFRI

The theme of this project is economically optimal management of Norway spruce stands for joint production of saw logs, pulpwood, bioenergy and carbon sequestration. At present, wood-based fuels comprise 20% of Finnish energy consumption, but in line with EU policies, the aim is to increase the share of renewable energy, especially in the form of woody biomass. The main source of this will be logging residues and forest chips, the use of which is targeted to double from 2-3 to 5 mill m3/year by 2010. Intensified removals are likely to concentrate on the most fertile sites of spruce.

At present, forestry practices and research focus on conventional timber production. The intensified removal of logging residues will affect the material balances of the forest ecosystem and may have unexpected consequences unless thoroughly quantified. Firstly, it will draw on the nutrient pool of the soil and may reduce tree growth. Secondly, it will decrease carbon sequestration in forest soils, demanding attention through the Kioto protocol.

We will develop a detailed economic-ecological optimization framework for joint production of timber, bioenergy and carbon sequestration in spruce stands. To this end, we will (1) compile data from long-term logging experiments to assess the effects of biomass removal on soil nutrients, (2) adapt a process-based stand growth model to spruce, linking it with soil nutrient and carbon dynamics and climate change, (3) develop a simulation model for computing social and private economic surplus of forestry for alternative management chains, and (4) develop an optimization procedure for solving the management chain for maximizing long term economic gain. The expected increase in bioenergy production requires that the nutrient balance be incorporated in the analysis. A scientific framework has not yet evolved for including elements (1)-(4). Solving the problem will yield a chain of dissimilar rotations that will considerably widen the scope of the existing models.

Economic-ecological optimisation is the most scientifically efficient method for analysing implications of intensified bioenergy production on forest management and optimal stand density, thinnings, fertilization and rotation. In addition, the project will yield information on how the supply of timber, bioenergy and carbon sequestration depend on relative prices of stumpage, forest chips and carbon emission permits. As we will obtain results for a variety of forest sites it will be possible to assess the bioenergy potential over a large regional scale. This project must be contrasted with studies that describe technical bioenergy production possibilities without taking into account the economic dimensions. The economic results can be applied to private and public forest management and in specifying public energy policies.

The team includes an economist, a forest economist, an expert in ecological forest models and an expert in nutrient cycling in forests. Earlier, we have developed a similar model for Scots pine that has been used in reformulating the Finnish silvicultural guidelines and forest legislation.

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