Background
Forestry plays a major role in climate change mitigation. However, which intensity of logging is best suited for that task, remains controversial. We contribute to the debate by quantitatively analyzing two different forest management scenarios in Germany, an intensive and an extensive one. We assess whether increased carbon storage in wood products and substitution of other emission-intensive materials can offset reduced carbon stocks in the forest due to increased harvesting. For that, we calculate annual Required Displacement Factors (RDF) - a dimensionless quantity that indicates the minimal Displacement Factor (DF) so that intensive forestry outperforms extensive forestry from a climate perspective.
Result
Annual RDFs show values of about 1 in the first two decades and after 2030 a steady decline to about 0. The comparison between current average DF and calculated RDFs indicates that for now, a compensation of lower carbon stocks in forests by material and energy substitution as well as product carbon storage is possible. In the future however, DFs will decline due to a decarbonization of the economy, hence the net climate mitigation potential of substitution diminishes. In terms of total global warming potential, the performance of the two scenarios is likewise dependent on how quickly the rest of the economy decarbonizes: With a conservative estimate on future emission reduction, leading to relatively high DFs, intensive forestry is beneficial, reducing total global warming potential (GWP) over the analysed time period of 40 years by 100 - 300 Mt CO2-equ. compared to extensive forestry. With an optimistic estimate for low future DFs extensive forestry is beneficial, reducing GWP over the same time period by 0 - 200 Mt CO2-equ. compared to intensive forestry.
Conclusion
Our findings highlight the necessity of a broad systems perspective for assessing the climate impacts of wood use. Robust statements about the climate performance of different forestry scenarios can only be made by including different possible industry decarbonisation pathways into the assessment. Still, we can robustly conclude that the later a change in forest management is initiated, the more beneficial the extensive scenario will be, because carbon displacement diminishes as decarbonization proceeds.