Multiple cell wall chemical components drive the decomposition of
ectomycorrhizal necromass over time
Abstract
The extramatrical mycelium of ectomycorrhizal fungi (EMF) is an
important source of soil carbon. While the importance of recalcitrant
compounds in the fungal cell wall has been reported earlier, the
contribution of abundant and more labile components, like glucans, and
the role of their temporal dynamics during decomposition remains
unknown. We examined how the decomposition of EMF mycelium is related to
the dynamics of 3 main fungal cell wall components; chitin, melanin, and
glucans. Across six EMF species, the initial concentrations of the three
components were not a good predictor of necromass loss after 6 weeks.
However, the dynamics of chitin concentration during the decomposition
process contributed to the weekly necromass degradation, with trends of
chitin loss dynamics being dissimilar across the fungal species. In
contrast, the dynamics of loss of melanin and glucans was not related to
the weekly necromass loss. Given similar total necromass loss across
species, we suggest that glucans and chitin are not discriminated by
decomposers. This mechanism compensates for the interspecific difference
in their initial concentration. Our results indicate that fungal
necromass decomposition does not behave similarly to plant litter, while
it is critical to soil carbon dynamics.