Microbial community structure shapes the effectiveness and
mechanisms of utilizing SOM by microbes (Monson et al., 2006;
Balser and Wixon, 2009; Keiblinger et al., 2010), and thus the
changes of microbial community structure may affect the SOM
decomposition rates and CO2 production. Söderberg et al. (2004)
reported that the distribution of Gram negative bacteria was
linked to the root distribution and their biomass increased when
readily decomposable C compounds such as sugars, organic and
amino acids were available, due to the linkage to roots and fungal
mycelia