Tong Gao;Xinyu Song;Yunze Ren;Hui Liu;Hangfeng Qu;Dong Xia

Northeast Forestry University;Key Laboratory of Sustainable Forest Management and Environmental Microorganism Engineering of Heilongjiang Province, Northeast Forestry University, Harbin, People’s Republic of China;Key Laboratory of Sustainable Forest Management and Environmental Microorganism Engineering of Heilongjiang Province, Northeast Forestry University, Harbin, People’s Republic of Chin

Forest carbon cycle;Seasonal freeze-thaw;Thinning;Climate change;SOIL MICROBIAL BIOMASS;LITTER DECOMPOSITION;BOREAL FOREST;CLIMATE;PERMAFROST;CYCLE;FEEDBACKS;STORAGE;BALANCE;STAND

Abstract To explore how to respond to seasonal freeze–thaw cycles on forest ecosystems in the context of climate change through thinning, we assessed the potential impact of thinning intensity on carbon cycle dynamics. By varying the number of temperature cycles, the effects of various thinning intensities in four seasons. The rate of mass, litter organic carbon, and soil organic carbon (SOC) loss in response to temperature variations was examined in two degrees of decomposition. The unfrozen season had the highest decomposition rate of litter, followed by the frozen season. Semi-decomposed litter had a higher decomposition rate than undecomposed litter. The decomposition rate of litter was the highest when the thinning intensity was 10%, while the litter and SOC were low. Forest litter had a good carbon sequestration impact in the unfrozen and freeze–thaw seasons, while the converse was confirmed in the frozen and thaw seasons. The best carbon sequestration impact was identified in litter, and soil layers under a 20–25% thinning intensity, and the influence of undecomposed litter on SOC was more noticeable than that of semi-decomposed litter. Both litter and soil can store carbon: however, carbon is transported from undecomposed litter to semi-decomposed litter and to the soil over time. In summary, the best thinning intensity being 20–25%.