Figure 2: Factors affecting the ‘apparent’ sensitivity of decomposition of soil organic matter.
From: Temperature sensitivity of soil carbon decomposition and feedbacks to climate change
The intrinsic temperature sensitivity (as in Arrhenius functions, Box 1) of decomposition of an organic-C substrate is a function of the decomposability of the molecule and the ambient temperature. In general, more complex molecular structures have higher activation energies and, hence, higher temperature sensitivity. However, several environmental constraints on decomposition can dampen or obscure the intrinsic temperature sensitivity by reducing substrate availability, often causing the measured (or ‘apparent’) temperature sensitivity to be less than expected. The responses to these multiple factors are shown here as a plane for graphic simplicity, but nonlinear functions (for example, oxygen availability) or step functions (for example, melting of permafrost) may be more realistic for some factors.
