The decomposition of ectomycorrhizal fungal necromass

Abstract

a b s t r a c tThe turnover of ectomycorrhizal (EM) fungal biomass represents a significant input into forest carbon (C) and nutrient cycles. Given the size of these fluxes, understanding the factors that control the decomposition of this necromass will greatly improve understanding of C and nutrient cycling in ecosystems. Recent research has highlighted the considerable variation in the decomposition rates of EM fungal necromass, and patterns from this research are beginning to emerge. In this article we review the research that has examined both intrinsic and extrinsic factors that control the decomposition of EM fungal necromass and propose additional factors that may strongly influence EM fungal necromass decomposition and ecosystem properties. We argue that, as with most plant litters, the stoichiometry (C:N) of EM necromass is an important factor governing decomposition, but its role is modulated by the nature of the C and N in the tissue. In particular, melanin concentration appears to negatively influence the quality of EM fungal necromass much as lignin does in plant litters. Other intrinsic factors such as the morphology of the mycelium may also play a large role and suggest this as a focus for future research. Extrinsic factors, such as decomposer community activity and physical protection by soil, are also likely to be important in governing the decomposition of ectomycorrhizal necromass in situ. Finally, we highlight the potential importance of EM fungal necromass diversity and abundance in influencing terrestrial biogeochemical cycles. Understanding the factors that control the decomposition of EM necromass will then improve the predictive power of next-generation terrestrial biosphere models.

Maintaining connectivity: understanding the role of root order and mycelial networks in fine root decomposition of woody plants

“…In fact, concentrations of chitin were associated with faster rates of decomposition (Fernandez and Koide 2012). These findings have been supported by Drigo et al (2012), Zeglin et al (2013) and Russell (2014), who report rapid declines in chitin concentrations within decomposing fungal tissues (Fernandez et al 2016).…”

“…For instance, AM fungi produce the hydrophobic glycoprotein, glomalin which may aid in waterproofing hyphae as they transport nutrients (Rilling et al 2002;Fernandez et al 2016). Like glomalin, ECM fungi produce hydrophobic proteins or hydrophobins that coat the outside of cell walls, making hyphae un-wettable (Fernandez et al 2016). The hydrophobic nature of these fungal proteins also likely retards enzymatic decomposition.…”

“…The hydrophobic nature of these fungal proteins also likely retards enzymatic decomposition. Additionally, the hydrophobic pigment, melanin which is located within fungal cell walls is thought to be important in regulating decomposition of ectomycorrhizal tissues (Fernandez and Koide 2014;Fernandez et al 2016). ECM species differ with respect to the structure of their hyphal sheaths, the majority of which are hydrophobic; mantles can be made up of either loosely associated or tightly woven hyphae that form an outer cover comparable to a leaf's epidermis (Agerer 2006).…”

Comparative genomics and transcriptomics depict ericoid mycorrhizal fungi as versatile saprotrophs and plant mutualists

“…Melanin allows fungi to tolerate environmental stress and makes their biomass recalcitrant to degradation (Fernandez et al ., ). The analyses of five genes linked to melanin biosynthesis (Methods S1) showed that two of them ( arp1 – scytalone dehydratase and abr1 – brown 1) were significantly enriched in ERM fungi compared with fungi with different ecological strategies (Table S9).…”

Understory Dwarf Bamboo Affects Microbial Community Structures and Soil Properties in a <i>Betula ermanii</i> Forest in Northern Japan

“…As a result, Ascomycota mycelia are more likely to leave a large proportion of a fungal necromass that serves to store carbon in boreal soil (6, 9). Our results showed that the abundance of mycorrhizal fungi of the phylum Ascomycota increased with higher TC contents in the Sasa -intact plot (Fig.…”