Natascha Kljun

Boreal forests play a crucial role in global carbon sequestration and storage, yet their vulnerability to climate change remains a significant concern. We present results from simulations with the process-based dynamic global vegetation model LPJ-GUESS of the combined effects of climate change and forest management on the carbon sink capacity of a boreal forest in southern Sweden. We compared two future climate change scenarios (RCP 4.5 and RCP 8.5) along with four forest management options against a baseline scenario without management interventions. Our findings indicate that projected temperature increases (+2 to +4°C) in the late 21st century will diminish the net carbon sink strength, particularly in old-growth forests. Clear-cut and subsequent reforestation resulted in a substantial decline (57-67%) in vegetation carbon during 2022-2100. The carbon compensation point (CCP) was reached 12-16 years after the clear-cut, indicating a period of carbon debt before the ecosystems resumed acting as a net carbon sink. Specific reforestation strategies, such as pine plantations, enhanced the overall net carbon sink by 7-20% relative to the baseline during 2022-2100. The carbon parity point, without considering harvested carbon, was reached 56-73 years after the clear-cut, highlighting the extended period required for the reforestation to achieve a carbon stock equivalent to the uncut baseline. These findings highlight the substantial influence of forest management on the net carbon budget, surpassing that of climate change alone. The adoption of relevant reforestation strategies could enhance carbon uptake, simultaneously improving forest productivity and ensuring the forest's vital role in carbon sequestration and storage amid a changing climate.