摘要：We use root exclusion plots, subsurface gas sampling and in situ diffusivity measurements to
quantify in situ soil organic carbon (SOC) decomposition dynamics within separate
depth-dependent soil pools (0 and 35 cm). We contrast these measurements with
observations of temperature–decomposition potentials, generated from laboratory
incubations of the same soils at optimal moisture levels and native temperatures. The
decomposition–temperature response was similar at different depths in the field, but every
gram of soil C at 35 cm was more than 100 times less active in decomposition than surface
soil. These depth-related variations were not evident in decomposition potentials generated
from aerobic laboratory incubations, highlighting the importance of environmental physical
factors in constraining soil organic carbon decomposition. At depth, physical
protection of SOC could match or even override the importance of quality and
temperature in determining the future stability of deeper, recalcitrant pools.
