Forest carbon stock budget development following extreme drought- induced dieback of coniferous stands in Central Europe – a CBM-CFS3 model application

Abstract Background The aim of this contribution is to analyze the forest carbon budget development following the recent historically unprecedented dieback of coniferous stands in the Czech Republic. The drought-induced bark-beetle infestation resulted in record-high sanitary logging, turning the Czech forestry from a long-term carbon sink offsetting about 6% of the country's greenhouse gas (GHG) emissions since 1990 to a significant source of CO 2 emissions in recent years (2018–2021). In 2020, the forestry sector accounted for almost 10% of the country's overall GHG emissions. Using the nationally calibrated Carbon Budget Model of the Canadian Forest Sector at a regional spatial resolution, we analyzed the trend and scenarios of forest carbon budget development until 2070. Two critical points arise: the short-term prognosis for reducing current emissions from forestry and the implementation of adaptive forest management focused on tree species change and sustained carbon accumulation. Results This study used four different scenarios to assess the impact of adaptive forest management on the forest carbon budget and CO 2 emissions, tree species composition, harvest possibilities, and forest structure in response to the recent calamitous dieback in the Czech Republic. The model analysis indicates that the Czech forestry may stabilize by 2025, or at the latest, by the end of this decade. Subsequently, it may become a sustained sink of about 3 Mt CO 2 eq./year (excluding contribution of harvested wood products), while enhancing forest resilience by the gradual implementation of necessary adaptation measures that ensure the provision of all expected forest functions to society. The speed of adaptation is linked to harvest intensity and severity of the current calamity. Under the most severe black scenario, the proportion of unstable spruce stands declines from the current 43% to approximately 25% by 2070, in favor of more suited tree species such as fir and broadleaves. These species would also constitute about 50% of the harvest potential, while maintaining levels generated by the Czech forestry prior to the current calamity. Conclusion The results show progress of stabilizing CO 2 emissions, implementing tree species change, and quantifying the expected harvest and mitigation potential in Czech forestry until 2070.