Leaving disturbance legacies conserves boreal conifers and maximizes net CO2 absorption under climate change and more frequent and intense windthrow regimes

Context Forest landscape management practices that conserve species composition and maximize carbon sequestration despite changes in climate and disturbance regimes are required to achieve social and environmental targets. Although post-windthrow management, such as salvage logging, can reduce carbon dioxide (CO2) emissions within ecosystems by removing downed logs, it can result in major changes in tree species composition. Additionally, the net effects of salvage logging on CO2 emissions may become negative based on a cradle-to-grave analysis (i.e., all aspects of wood processing including manufacturing and the disposal of wood products made from windthrow-damaged trees). Objectives Our objective was to assess the effects of climate change, changes in windthrow regimes, and post-windthrow management on tree species composition, as well as on the carbon balance in the forest sector by combining forest landscape simulations and life cycle assessments at the forested landscape in northern Japan. Methods We simulated forest dynamics in 36 scenarios based on features of the climate, windthrow regime, and post-windthrow management using the LANDIS-II forest landscape model. We also estimated CO2 emissions related to post-windthrow management using a life cycle assessment approach. Results Increases in the windthrow area, which is more vulnerable to climate warming, resulted in the development of temperate broadleaf-dominant forests and a decrease in aboveground biomass. The removal of advanced seedlings and dead woods due to post-windthrow management accelerated changes in the aboveground biomass and species composition due to the increase in windthrow frequency and intensity and temperature. The cumulative net CO2 absorption of the forest sector over 115 years, including the carbon balance within ecosystems and the CO2 emissions related to the management, manufacturing, and disposal of products, greatly decreased due to salvage logging and scarification after logging. Conclusions Our results demonstrate that leaving downed logs and advanced seedlings is recommended to conserve species composition and carbon sink function and maximize net CO2 absorption despite a warming climate and more frequent and intense windthrow regimes.