| Our FOrest Carbon Sink Optimization Model (FOX) is a bio-economic optimization model where production of forest wood is biologically determined by growth functions but decision making about harvesting or further growth is resolved by an economic profit maximization objective function. Besides timber related costs and benefits, the FOX Model provides a carbon payment after the incremental carbon sequestration when harvesting is delayed by another period and internalizes an equivalent level of carbon cost in the period when previously sunk carbon gets released by final cut. This introduces the potential for wood as a carbon instrument in addition to wood as a commodity.
The FOX Model can help understand how forest resources can more efficiently contribute to a national climate policy by making explicit the trade-off between forest wood for biomass energy versus forest wood as an instrument for carbon sequestration.
The FOX Model determines the optimal harvest of forests on a national level based on the exogenous forest growth functions, timber and carbon prices. It is a dynamic, linear mathematical optimization model. The harvesting process includes both cutting and thinning of forests. The model allows the co-existence of multiple forest age classes. Carbon prices can be set constant or changing for each period. The timber prices are defined for three main demand segments: ‘sawlogs’ for the timber industry, ‘pulpwood’ for the fibreboard and paper industries and ‘firewood’ for all energy purposes. The model can process up to 10 species/species groups in 10-year age classes and can be run for up to 220 years (with 10-year time periods). All characteristics can be further expanded upon based on the granularity of input data.
FOX can be used to represent any real or hypothetical forest management entity. Currently, it is calibrated with country specific datasets collected from the forest authorities of Hungary and Romania, while the calibration of the Bulgarian model is work in progress.
In the context of dynamic exogenous factors, model outputs can be computed for all modelled periods: forest stock changes (by species and age), forest final cutting (by species and age), forest thinning as a function of the available forest (by species and age), CO2 sequestration and the impact of carbon price on forest stock, cutting, thinning and CO2 sequestration. Ultimately, the model constructs forest carbon sink supply curves for different time periods.
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