Resolving complexity: Material flow analysis of a national wood flow system integrating the versatility of wood

A systemic understanding of the use of wood resources is required to defossilize society and promote bio-based developments. This study provides a novel approach to represent a comprehensive material flow analysis (MFA) spanning the entire wood value chain; encompassing wood harvest to products, use in society, collection, reuse, recycle, energy generation, and trade. By recognizing wood as a complex material, with changing properties throughout its lifespan, we developed a method where we employed a color-coded system for processes (27 boxes) and 110 flows to symbolize distinct life stages and the dynamic characteristics, including 23 different trade flows. The wood processes and flows are categorized (11 categories) into different wood types (e.g., softwood and hardwood) and harmonized to include all available data on each single step of the wood life cycle, improving data traceability and visualization, and allowing for replicable analysis with respective data noted for each process and flow. Methodological obstacles due to different units, uncertainty of flows, and discrepancies in data are addressed and adjustments proposed. Switzerland was chosen as a case study as a large number of various types of data were available to perform the analysis. The categorized and harmonized flows of woody biomass mapped and analyzed in the MFA provide a comprehensive basis to identify and recommend avenues to increase cascading use of wood as a carbon sink, by considering relevant aspects like the network of flows and processes, the quality and availability of the woody biomass, and the organization of the industry.