Abstract
Comparing soil organic carbon (SOC) stocks across space and time is a fundamental issue in global ecology. However, the conventional approach fails to determine SOC stock in an equivalent volume of mineral-soil, and therefore, SOC stock changes can be under- or overestimates if soils swell or shrink during forest development or degradation. Here, we propose to estimate SOC stock as the product of mineral-soil mass in an equivalent mineral-soil volume and SOC concentration expressed as g C Kg-1 mineral-soil. This method enables researchers to compare SOC stocks across space and time. Our results show an unaccounted SOC accumulation of 2.4 - 10.1 g C m-2 year-1 in the 1m surface mineral-soils in global forests. This unaccounted SOC amounts to an additional C sink of 0.12 – 0.25 Pg C year-1, which equals 30 – 62% of the previously estimated annual SOC accumulation in global forests. This finding suggests that forest soils are stronger C sinks than previously recognized.
Footnotes
weixinzhang{at}139.com, yqchen{at}hnust.edu.cn, shileilei{at}scib.ac.cn, wangxiaoli{at}scbg.ac.cn, liuyongwen{at}pku.edu.cn, rxq99{at}scib.ac.cn, linyb{at}scbg.ac.cn, shaoyuanh{at}scib.ac.cn, lixiaobo{at}scib.ac.cn, liushengjiehu{at}163.com, slpiao{at}pku.edu.cn, wxzhu{at}binghamton.edu, xzou2011{at}gmail.com, sfu{at}scbg.ac.cn
Data accessibility statement: We confirm that, should the manuscript be accepted, the data supporting the results will be archived in an appropriate public repository such as Dryad or Figshare and the data DOI will be included at the end of the article.