China forests show increase in soil carbon: doi: 10.5194/bg-17-715-2020
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" eight permanent forest plots, which represent boreal (1998–2014), temperate (1992–2012), subtropical (1987–2008), and tropical forest biomes (1992–2012) across China. SOC contents increased significantly from the 1990s to the 2010s, mostly in the upper 0–20 cm soil depth, "
" averaged SOC stocks increased significantly from 125.2±85.2 Mg C ha−1 in the 1990s to 133.6±83.1 Mg C ha−1 in the 2010s across the forest plots, with a mean increase of 127.2–907.5 kg C ha−1 yr−1. This SOC accumulation resulted primarily from increasing leaf litter and fallen logs, which accounts 3.6 %–16.3 % of above-ground net primary production"
and soilC increases as deep as they studied, down to 100cm:
"We further compared SOC stocks of the whole soil profile between 1990s and 2010s at a depth of 0–40 cm in the boreal site, 0–60 cm in the subtropical site, and 0–100 cm in the temperate and tropical sites (Fig. 3). The SOC stocks of all sampling sites in the 2010s were higher than those in the 1990s"
"SOC accumulation rates in the subtropical and tropical sites were relatively higher than those in the boreal and temperate sites (Fig. 3). The greatest increase in SOC stock occurred in the subtropical evergreen old-growth forest (907.5±60.1 kg C ha−1 yr−1), and the least in the temperate deciduous oak forest (127.2±25.3 kg C ha−1 yr−1; Table S3)"
"The SOC stocks within the top 20 cm increased by 2.4–12.6 Mg C ha−1 across the forests during the past 2 decades, with an annual accumulation rate of 332.4±200.2 kg C ha−1. If all soil horizon profiles were included, the soils may have been found to have sequestered 3.6 %–16.3 % of the annual net primary production across the investigated sites, and the averaged accumulated rate (421.2 kg C ha−1 yr−1) may have been more than one-half of the vegetation C uptake rate (702.0 kg C ha−1 yr−1) in China's forests"
sidd