Climate mitigation using wood: a theoretical calculation of aggregated carbon stocks in Dutch forests and wooden products including house building

Abstract

Human activities release 40 billion tons of carbon dioxide (CO2) into the atmosphere every year. 150 Mton CO2 is emitted annually in the Netherlands. Forest can contribute to climate change mitigation by capturing CO2 and storing it as woody biomass. Harvesting this wood and processing it into wooden products can ensure that the CO2 remains withdrawn from the atmosphere for an extended time thereby contributing to climate change mitigation.
This study examined the extent to which common Dutch homogeneous forests can contribute to climate change mitigation if the harvested wood is processed into wooden products. Existing yield tables based on the theoretical growth of Dutch homogeneous forests were used as input data. These forests concerns homogeneous beech, Douglas fir, oak, spruce, larch, poplar and Scots pine forests on a growing site where the conditions are such that the trees have optimal growth development. To determine the forest contribution to climate change a mathematical model was set up and applied which calculates the CO2 stock in the atmosphere for varying residence times of harvested wood in the economy and also determines the influence of this residence time on the optimal harvest age.
This study showed that homogenous forests in the Netherlands can extract on average a maximum of between 7 and 17 tons CO2 per hectare per year depending on the tree species. For all tree species, the amount that remains extracted from the atmosphere approaches the maximum when the residence time in the economy is increased. After an initial rapid growth towards this maximum with increasing residence time, however, this development levels off and the maximum is never reached. The optimal felling age varies because of the economic residence time. Building wooden houses with a lifetime of 150 years offers the possibility of extracting CO2 from the atmosphere for a long time. Until 2050, the speculative demand of 660,000 single-family homes will allow an average of 1.5 Mton of CO2 to be extracted from the atmosphere every year. If the total forest area in the Netherlands is used to store wood in the economy for 150 years, an average of almost 6 Mton is extracted each year.
The conclusion is that from the point of view of climate mitigation, forest management requires customization and coordination based on the lifespan of the wooden product to be produced. In addition, building wooden houses with a long economic residence time offers the possibility to transfer almost the complete maximum amount of CO2 stored in biomass from the forest to the economy. In the Netherlands, however, the average annual amount of CO2 that can be extracted from the atmosphere by forests is a small percentage compared to the annual CO2 emissions. As a result, the average annual CO2 extraction into the atmosphere by building wooden houses is relatively low, but because the wood also significantly limits the use of concrete, it is a possibility that fits well in the mix between other options that can contribute to the mitigating climate change.

Date of Award	28 Jan 2022
Original language	English
Supervisor	Angelique Lansu (Examiner), Winnie Gerbens-Leenes (Supervisor) & Jikke van Wijnen (Co-assessor)