representing SOM formation, provide a basis for the linked development
of prediction and theory.
Thus, the representation in models of the microorganisms
responsible for SOM transformations is showing promise; yet, the
decomposer food web is complex and includes soil fauna, which
represent an array of functions that can directly and indirectly influence
soil biogeochemical processes. These functions include
shredding and redistributing litter, altering soil physical properties
including aggregation and pore space structure, microbivory, and
accelerating nutrient cycling in soil and litter (Verhoef and
Brussaard, 1990; Brussaard et al., 2007; Coleman, 2008). Given
the promise of microbial-explicit models, and the range of potential
effects of fauna on soil processes and SOM, here we consider the
advantages and drawbacks of adding fauna to already complex soil
biogeochemistry models (Fig. 1).