Effect of cascade use on the carbon balance of the German and European wood sectors

Abstract Wood product models have often been used to estimate the carbon dynamics of wood products and evaluate their effects on the mitigation of climate change. Their increasing complexity allows for advanced analysis of industrial product conversion efficiency, product lifespan and recycling rate, although data availability for such analyses is very often problematic. In spite of the widely recognised importance of cascade chains from one wood product to another, some wood product models represent them with recycling parameters that allocate part of the recycled wood to the same product category. Consequently, the infinite repetition of these loops overestimates carbon stock. This study analyses and benchmarks the effect on carbon stock in wood products for the German wood sector, when infinite recycling loops in wood product models are replaced by cascade chains. Different scenarios were simulated to analyse the effect of enhanced cascade chains. We estimated the carbon stock in the German wood product sector at 22.17 ± 3.82 t C per hectare of forest in the most realistic current scenario, an amount that is overestimated by 15.8% if infinite recycling loops were used instead. The deviation on the estimated carbon stock was derived from the uncertainty of allocation parameters. Then we estimated the carbon stock in the European wood product sector (EU-28) at 1231.76 t C, representing 9.16 t C per hectare of forest. The carbon stock in German wood product sector estimated for the high quality wood benchmark scenario (103.17 t C per hectare of forest) indicated that strategies to promote the development of new product designs and material technologies to enhance cascading may have the highest impact on carbon stock in the wood product sector. Studies aiming at reducing uncertainty on results are urgent, because the use of wood products is becoming an important strategy of the international community to mitigate climate change. At the same time, a correct representation of cascade use in wood product models is important because cascade practices are being promoted by governments and will probably become more common in the near future.