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.