Substitution effect of Finnish wood products according to dominant tree species

Abstract

Finland has committed under Paris Agreement to limit global temperature rise to well below 2 ̊C compared to pre-industrial levels, and to reach carbon neutrality by 2035. Finnish forests have a key role in reaching these targets. Firstly, forests contribute to climate change mitigation by sequestrating carbon dioxide (CO2) from the atmosphere through photosynthesis. Secondly, forest is a valuable resource pool of renewable low carbon material that has several advantageous attributes. Long-lived harvested wood products (HWP) function as external carbon pools supporting continuous growth of biomass in the forest, and substitute for fossil-intensive material. Processing of wood material result in substantially smaller life-cycle emissions compared to its energy intensive substitutes concrete, aluminium and steel. The substitution potential of wood use is particularly significant in construction sector that caused one third of both national and global GHG emissions in 2018. In this study the substitution effect of Finnish wood products by dominant tree species was assessed by combining information on current consumption with substitution factors (SF) for structural construction, non-structural construction and energy usage from previous studies. The aim was to identify those factors that influence the substitution potential most extensively and estimate the overall climate effect of mechanical forest industry in the light of current production levels and consumption trends. Current production volumes of mechanical forest industry are averages from LUKE statistical service from 2015-2018. Proprietary information on wood use in Finland was obtained from Forecon report on use of sawn wood and wood-based panels. Contrary to previous ones, this study provides substitution factors by tree species, which has been an unidentified area of research to date. The results show that with current consumption trends, the substitution effect for pine, spruce and birch were 1.37, 1.27 and 1.04 tC / tC, respectively. This implies that every ton of carbon used in wood product result to an emission reduction of 1.04-1.37 (3.8–5 t CO2) carbon tons. Sensitivity analyses showed that the SFs for coniferous trees were highly sensitive for changes in the use of general sawn wood, which represents the largest singular product group. The substitution effect of birch was determined by its use in short-lived products. The overall substitution effect of current consumption of sawn wood and wood-based panels equals to 3.3 Mt C (12,1 MtCO2). The results imply that the external carbon stock in produced wood products (2.5 Mt C, or 9.2 MtCO2) and its substitution effect (3.2 Mt or 12.1 MtCO2) could increasingly offset the reduction in forest carbon stock (6 Mt C or 22 MtCO2) due to raw-material acquisition, if forests are managed sustainably and wood is used primary for production of long-lasting wood products.