Abstract
Forest soil is the largest carbon pool in terrestrial ecosystem, and the
soil-to-atmosphere CO2 flux (soil respiration,
Rs) is the main link between soil and atmosphere. However, due to
the lack of integration of field observations, substantial uncertainties
exist in quantifying large-scale soil carbon effluxes, which limit our
understanding of the fate of forest soil in a warming world. Here,
China’s forest ecosystems were divided into six forest types in six
regions, and an integrated soil respiration database (N=634) was
compiled to evaluate soil carbon effluxes by random sampling with
replacement. Average annual Rs was 783 g C m-2
yr-1 across China, ranking from the highest to the
lowest as follows: East, Southwest, South, Northwest, Northeast and
North. Total soil carbon emissions were 1472.6 Tg C
yr-1 in China’s forest ecosystems, and about 69% from
three southern regions (i.e., Southwest, Southern China and Eastern
China) and 31% from three northern regions (i.e., Northwest, Northern
China and Northeast). Evergreen needleleaf forest (529.09 Tg C
yr-1, 52%) and evergreen broadleaf forest (343.01 Tg
C yr-1, 34%) were the main source of soil carbon
emissions in three southern regions, while deciduous broadleaf forest
(334.36 Tg C yr-1, 74%) was the main emissions in
three northern regions. Our results provide a better understanding of
the distribution and magnitude of soil carbon effluxes in China’s forest
ecosystems.