Thinning intensity affects carbon sequestration and release in seasonal freeze–thaw areas

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%.

Effects of Different Thinning Intensities on Carbon Storage in Pinus koraiensis Middle-Aged Plantations in Northeast China

“…Comparing moderate thinning (35%-55%) to other thinning intensities, soil carbon storage increased by 16.1% [50]. Another study reported that litter and soil layers with a 20%-25% thinning intensity were shown to have the most favorable effects on carbon sequestration [19]. In this study, 22% thinning had higher carbon storage in the soil at 0-20 cm depth than in the 16% and 18% thinned plots, consistent with previous research [19].…”

“…Another study reported that litter and soil layers with a 20%-25% thinning intensity were shown to have the most favorable effects on carbon sequestration [19]. In this study, 22% thinning had higher carbon storage in the soil at 0-20 cm depth than in the 16% and 18% thinned plots, consistent with previous research [19]. Soil carbon storage is significantly influenced by soil depth [51].…”

“…Although there were differences in the carbon storage of vegetation across thinning intensities, an overall trend was not observed. Our carbon storage of shrubs and vegetation was a little low, but it was consistent with the findings of Gao et al (2023) [19]. The effects of decreasing shrub and vegetation layers on the carbon stock can be varied and complex.…”

“…Under some thinning procedures, this may result in greater carbon storage in the herb and shrub layers [18]. A thinning intensity of 20%-25% can successfully reduce the depletion of organic carbon in seasonal freezethaw forest settings [19]. By improving light availability and lowering competition from overstory trees, thinning can also promote the growth of understory vegetation [20].…”

Evaluation of Ecological Function Restoration Effect for Degraded Natural Forests in Xiaoxinganling, China

“…Several studies have evaluated the restoration effect for the ecological functions of degraded natural forests and demonstrated that an accurate and comprehensive evaluation of restoration effectiveness is a prerequisite for guiding the restoration process [9,10]. However, most of the studies on the effectiveness of forest vegetation restoration mainly focused on changes in the vegetation cover and the vegetation growth state [11][12][13]. Most studies evaluating the effect of forest ecological restoration focused on a single indicator, such as a single stand type and a single stand age [14,15].…”