Das Projekt "Modellierung des Kohlenstoffaustausches zwischen Waeldern, Holzprodukten und der Atmosphaere - Teil: ESCOBA - European Study of Carbon in Ocean, Atmosphere and Biosphere: Biosphere" wird vom Umweltbundesamt gefördert und von Joanneum Research Forschungsgesellschaft, Institut für Energieforschung durchgeführt. The influence of the management of the forest ecosystems as well as the utilization of wood on the global carbon cycle is expected to be large. The aim of this study is to simulate both the carbon exchange processes in managed forests and the effects of wood products and biofuel use on the carbon balance by coupling the Frankfurt Biosphere Model (FBM) with a wood utilization model. The coupled model is used to analyze four selected European countries: Austria, Finland, Germany and Portugal. Forest growth is simulated by the FBM, a global, mechanistic and prognostic biosphere model dependent on spatially and temporally varying climatic conditions. Management and harvest regimes are treated as an anthropogenic disturbance to the natural ecosystem, which leads to a forest called 'age class structured highforest'. The soil carbon model of the FBM allows the calculation of the net carbon exchange between the forest ecosystem (organisms in forests and soils) and the atmosphere. The use of age class distributions and four major tree species (pine, spruce, oak and beech) allows for an appropriate simulation of the carbon balance of the forests and the accompanying harvested biomass. Together with a matrix type model of age class dynamics, the full carbon balance of forestry can be simulated over a long period. Data on harvested wood are used by the wood utilization model to calculate the total carbon balance of the forest sector by different accounting approaches: the present 'Default IPCC Approach', the 'Stock-change Approach', the 'Production Approach' and the 'Atmospheric-flow Approach'. The amounts of industrial roundwood, wood products and fuelwood production including imports and exports are treated separately. CO2 releases from wood harvested in the past and carbon emission benefits from using wood for energy or products replacing other materials are considered as well. The approaches also require the calculation of the net ecosystem production (NEP) of a country's forest, provided by the FBM. Different scenarios approximating possible deviations from the 'business as usual' path regarding forest management and wood utilization are described.