Selective harvesting at rational intervals promotes carbon sequestration in temperate coniferous and broad-leaved mixed forests in China

Evidence-based selective cutting at prescribed intervals as part of good forest management can enhance the carbon sequestration capacity of the forest. The effect of forest management on carbon sequestration has, however, not been quantified. Thus, carbon content of various organs was measured for 323 tree species, 247 shrub species, and 233 herb species in seven temperate coniferous and broad-leaved mixed forests that were subjected to selective cutting with restoration durations of 100, 55, 45, 36, 25, 14, and 6 years to explore dynamic changes in carbon storage. The results showed that biomass carbon allocation in different organs followed a pattern: trunk > root > branch > leaf for all forests. With longer restoration durations, more carbon accumulated in different organs and in soils. Interestingly, when the restoration duration exceeded 50 years, carbon storage in ecosystem was larger than that in primary forests with 100-year cutting intervals, suggesting that a reasonable selective cutting interval can increase forest carbon sequestration. Mean diameter at breast height (DBH) and forest carbon storage were significantly positively correlated, and carbon storage of selectively cut forests exceeded that of primary forests when the stand mean DBH exceeded 15.66 cm. Therefore, mean DBH of forests can be an indicator for combining sustainable forest management and forest carbon sequestration. Additionally, the classic coefficients of 0.45 and 0.50 used to estimate carbon sequestration underestimated values by 2.65% and overestimated by 8.16%, respectively, in comparison with the measured carbon content from different plant organs.