Optimizing forest management for climate impact and economic profitability under alternative initial stand age structures

Highlights: • Increased stocking and N fertilization increased climate impact of forest production and biomass use. • No single management scenario maximized both climate impact and NPV. • Largest trade-offs between climate impact and NPV occurred in older initial age structures. • Climate impacts could be evaluated by using average displacement factors for HWPs. The full climate impacts of forest production and biomass use, and economic profitability of forest biomass production were studied under four alternative initial age structures of a forested landscape (young, even-aged, middle-aged and mature) in boreal conditions over 80 years. The forested landscapes occupied either by Scots pine or Norway spruce were managed by using seven management scenarios. The current thinning recommendations were considered as a baseline and alternative scenarios included maintaining 20% higher or lower stocking than in the baseline. The previous ones were also managed by using N fertilization, and an unthinned scenario (with final felling) was used as a comparison. A life cycle assessment tool with inputs from a forest ecosystem model was used to calculate full climate impacts of forest production and biomass use in substituting fossil-fuel-intensive materials and fossil fuels. The results showed that increased stocking and N fertilization were generally the most optimal forest management scenarios for full climate impacts and economic profitability in both species. Increased carbon sequestration through forest management surpassed the decreased economic profitability, and no single management scenario maximized both climate impact and economic profitability. The lowest climate impact, but the highest economic profitability, was found for the initially mature age structure. The calculated average displacement factors for the harvested wood products served as valid indicators for climate impacts but could not thoroughly depict the absolute climate impacts. More research is needed to improve the dynamic connection between forest ecosystem carbon balances and the substitution effects of harvested wood products.