Projected effects of climate change and forest management on carbon fluxes and biomass of a boreal forest

Boreal forests are key to global carbon (C) sequestration and storage. However, the potential impacts of climate change on these forests could be profound. Nearly 70 % of the European boreal forests are intensively managed, but our understanding of the combined effects of forest management and climate change on the forest's integral role as a C sink is still limited. In this study, we aim to fill this gap with simulations of the process-based dynamic global vegetation model LPJ-GUESS. We evaluated the effects of four forest management options under two different climate scenarios (RCP 4.5 and RCP 8.5), at a southern boreal forest stand in Sweden. These options were compared against a baseline without clear-cut or management interventions. We found that the projected increase in temperatures (+2 to +4 °C) during the latter part of the 21st century will reduce the net C sink strength, particularly in the unmanaged forest. The standing biomass C for reforestations was projected to be 57–67 % lower in 2100 than in the old forest in 2022. The study also revealed that the C sequestration potential of replanted pine forests may surpass that of 200-years old forests in the far future (2076–2100). The study did not detect statistically significant differences in overall net C exchange between the clear-cut with subsequent reforestation options and the baseline, even though specific reforestation strategies, such as pine plantations, enhanced the overall net C sink by 7–20 % relative to the baseline during 2022–2100. These findings underscore the profound influence of forest management on the net C budget, surpassing that of climate change scenarios alone. By adopting pertinent reforestation strategies, C uptake could be augmented, with concurrently improved forest productivity, resulting in favourable outcomes for the forest's critical role in C sequestration and storage amidst a changing climate.