Carbon emissions from forest harvest and fire offset approximately half of carbon sequestration of forestation in China during 1986-2020

Forest activities and fire disturbance (FAFD) play an important role in the global carbon cycle. Although many studies have been explored to examine the individual effect of forestation, forest harvest, and forest fire on the carbon cycle in China, their combined impacts remain unclear. Moreover, rare research has been examined the impacts of these activities at the species level on the net carbon budget. By integrating remotely sensed, detailed tree species and statistical data into a spatialized modeling approach, we estimated the carbon budget from three major FAFD (i.e., forestation, forest harvest and forest fire) in China during 1986-2020. We found that FAFD overall showed net carbon sequestration of total -710.64±136.4 Tg C with sequestration of -1529.36 ± 202.59 Tg C from forestation and emission of 585.38 ± 29.91 Tg C from forest harvest and 233.34 ± 36.28 Tg C from fire. Spatially, the national average carbon sequestration density from FAFD was -172.95 Mg C km^-2, with notable regional variations. Carbon emissions from forest harvest and fire offset 53.52% (38.26% and 15.26%, respectively) of carbon sequestration from forestation. More than 90% of tree species exhibited net carbon sequestration from forestation and harvest. The national offset impact of forest harvest varied by tree species, ranging from 3.51% to 101.27%. Owing to high carbon emission from forest harvest, Quercus and Eucalyptus showed large offset effects over 97%. In contrast, Pinus tabulaeformis and Larix demonstrated small offset effects of only 3.51% and 10.23% due to high carbon sequestration. These findings highlight the importance of accounting for carbon emissions from deforestation and forest fire when aiming to maximize carbon sequestration through forestation.