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In southern China, Chinese fir Cunninghamia lanceolata is one of the most important native conifer trees, widely used in afforestation programs. This area has the largest forestland atmospheric carbon sink, and a relatively young stand age characterizes these forests. However, how C. lanceolata forests evolved regarding their ability to sequester carbon remains unclear. Here we present data on carbon storage and sequestration capacity of C. lanceolata at six stand ages (5-, 10-, 15-, 20-, 30- and 60 - year-old stands). Results show that the carbon stock in trees, understory, vegetation, litter, soil, and ecosystem significantly increased with forest age. The total ecosystem carbon stock increased from 129.11 to 348.43 Mg ha -1 in the 5- and 60 - year-old stands. The carbon sequestration rate of C. lanceolata shows an overall increase in the first two stand intervals (5-10 and 10-15), peaks in the 15-20 stand intervals, and then decreases in the 20-30 and 30-60 stand intervals. Our result revealed that carbon sequestration rate is a matter of tree age, with the highest sequestration rates occurring in the middle age forest (15-20 - year-old). Therefore, this information may be useful for national climate change mitigation actions and afforestation programs, since forests are primarily planted for this purpose., Competing Interests: Declaration of competing interest The authors declare that they have no conflict of interest to influence the work reported in this paper., (Copyright © 2023 Elsevier B.V. All rights reserved.)

The temporal variation of greenhouse gas concentrations in China during the COVID-19 lockdown in China is analyzed in this work using high resolution measurements of near surface △CO 2 , △CH 4 and △CO concentrations above the background conditions at Lin'an station (LAN), a regional background station in the Yangtze River Delta region. During the pre-lockdown observational period (IOP-1), both △CO 2 and △CH 4 exhibited a significant increasing trend relative to the 2011-2019 climatological mean. The reduction of △CO 2 , △CH 4 and △CO during the lockdown observational period (IOP-2) (which also coincided with the Chinese New Year Holiday) reached up to 15.0 ppm, 14.2 ppb and 146.8 ppb, respectively, and a reduction of △CO 2 /△CO probably due to a dramatic reduction from industrial emissions. △CO 2 , △CH 4 and △CO were observed to keep declining during the post-lockdown easing phase (IOP-3), which is the synthetic result of lower than normal CO 2 emissions from rural regions around LAN coupled with strong uptake of the terrestrial ecosystem. Interestingly, the trend reversed to gradual increase for all species during the later easing phase (IOP-4), with △CO 2 /△CO constantly increasing from IOP-2 to IOP-3 and finally IOP-4, consistent with recovery in industrial emissions associated with the staged resumption of economic activity. On average, △CO 2 declined sharply throughout the days during IOP-2 but increased gradually throughout the days during IOP-4. The findings showcase the significant role of emission reduction in accounting for the dramatic changes in measured atmospheric △CO 2 and △CH 4 associated with the COVID-19 lockdown and recovery., (Copyright © 2021. Published by Elsevier B.V.)