Melanization of mycorrhizal fungal necromass structures microbial decomposer communities

Christopher W. Fernandez, Peter G. Kennedy

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37 Scopus citations


Mycorrhizal fungal necromass is increasingly recognized as an important contributor to soil organic carbon pools, particularly in forest ecosystems. While its decomposition rate is primarily determined by biochemical composition, how traits such as melanin content affect the structure of necromass decomposer communities remains poorly understood. To assess the role of biochemical traits on microbial decomposer community composition and functioning, we incubated melanized and non-melanized necromass of the mycorrhizal fungus Meliniomyces bicolor in Pinus- and Quercus-dominated forests in Minnesota, USA and then assessed the associated fungal and bacterial decomposer communities after 1, 2 and 3 months using high-throughput sequencing. Melanized necromass decomposed significantly slower than non-melanized necromass in both forests. The structure of the microbial decomposer communities depended significantly on necromass melanin content, although the effect was stronger for fungi than bacteria. On non-melanized necromass, fungal communities were dominated by r-selected ascomycete and mucoromycete microfungi early and then replaced by basidiomycete ectomycorrhizal fungi, while on melanized necromass these groups were co-dominant throughout the incubation. Bacterial communities were dominated by both specialist mycophageous and generalist taxa. Synthesis. Our results indicate that necromass biochemistry not only strongly affects rates of decomposition but also the structure of the associated decomposer communities. Furthermore, the observed colonization patterns suggest that fungi, and particularly ectomycorrhizal fungi, may play a more important role in necromass decomposition than previously recognized.

Original languageEnglish (US)
Pages (from-to)468-479
Number of pages12
JournalJournal of Ecology
Issue number2
StatePublished - Mar 2018

Bibliographical note

Funding Information:
We thank E. Andrews, L. Mielke, K. Beckman and B. Auch for field and laboratory assistance. PacBio sequencing was supported with a GenoPitch competitive grant from the University of Minnesota Genomics Center. Support for this project was provided by a Norwegian Centennial Chairs Research Grant to P.G.K. We also thank K. Clemmensen and two anonymous reviewers for their helpful comments and suggestions on a previous version of this manuscript.

Publisher Copyright:
© 2018 The Authors. Journal of Ecology © 2018 British Ecological Society


  • bacteria
  • carbon cycle
  • decomposition
  • fungi
  • melanin
  • mycorrhizal fungi
  • necromass
  • nitrogen cycle


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