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Mycelial biomass growth stage at death determines fungal necromass decay dynamics

Maillard, François LU ; Lopes Ramos, Danny LU ; Zhang, Bowen LU orcid ; Ahlawat, Ashish LU orcid ; Gill, Allison L. ; Troein, Carl LU orcid ; Hedenström, Mattias ; Sparrman, Tobias ; Persson, Per LU and Tunlid, Anders LU (2026) In Soil Biology and Biochemistry 214.
Abstract

Fungal necromass is increasingly recognized as a major component of soil organic matter, and identifying the factors that govern its formation is critical for understanding and predicting the global carbon cycle. Among these factors, the biochemical composition of mycelial residues at senescence, particularly melanin content, has been consistently identified as a key determinant of the fraction of fungal necromass that persists in soils. However, even non-melanized mycelial residues exhibit a recalcitrant fraction that resists microbial decomposition, and the reasons for this persistence are not well understood. To address this gap, we asked whether the growth stage at which a single non-melanized fungal species dies governs the decay... (More)

Fungal necromass is increasingly recognized as a major component of soil organic matter, and identifying the factors that govern its formation is critical for understanding and predicting the global carbon cycle. Among these factors, the biochemical composition of mycelial residues at senescence, particularly melanin content, has been consistently identified as a key determinant of the fraction of fungal necromass that persists in soils. However, even non-melanized mycelial residues exhibit a recalcitrant fraction that resists microbial decomposition, and the reasons for this persistence are not well understood. To address this gap, we asked whether the growth stage at which a single non-melanized fungal species dies governs the decay of its necromass in soil. Using Neurospora crassa , we produced seven necromass types that ranged from early exponential growth to prolonged starvation and decomposed them in forest soil. Necromass derived from biomass experiencing net growth at the time of harvest decomposed up to ten times faster than necromass from starved cultures, which were undergoing biomass loss. By the end of decomposition, only about 10 % of necromass from early-growth-stage biomass remained, while nearly 65 % of necromass from starved biomass persisted. Differences in mycelial biochemical traits, particularly C:N ratio and the degree of branching of glucans, which varied with fungal growth stage at death, explained variation in both decay rates and the size of the persistent fractions. Our findings suggest that the growth stage of fungi at death is a key factor driving fungal necromass decay profiles, with potentially large consequences for the contribution of fungal necromass to soil organic matter stocks.

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organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
FTIR, Fungal cell wall, Fungal necromass, NMR, Organic matter decomposition, Raman spectroscopy
in
Soil Biology and Biochemistry
volume
214
article number
110079
publisher
Elsevier
external identifiers
  • scopus:105026125306
ISSN
0038-0717
DOI
10.1016/j.soilbio.2025.110079
language
English
LU publication?
yes
additional info
Publisher Copyright: © 2025 The Authors.
id
abcea3e5-ecf2-48fc-bee7-4564dc943c3c
date added to LUP
2026-03-09 10:20:06
date last changed
2026-03-10 03:51:00
@article{abcea3e5-ecf2-48fc-bee7-4564dc943c3c,
  abstract     = {{<p>Fungal necromass is increasingly recognized as a major component of soil organic matter, and identifying the factors that govern its formation is critical for understanding and predicting the global carbon cycle. Among these factors, the biochemical composition of mycelial residues at senescence, particularly melanin content, has been consistently identified as a key determinant of the fraction of fungal necromass that persists in soils. However, even non-melanized mycelial residues exhibit a recalcitrant fraction that resists microbial decomposition, and the reasons for this persistence are not well understood. To address this gap, we asked whether the growth stage at which a single non-melanized fungal species dies governs the decay of its necromass in soil. Using Neurospora crassa , we produced seven necromass types that ranged from early exponential growth to prolonged starvation and decomposed them in forest soil. Necromass derived from biomass experiencing net growth at the time of harvest decomposed up to ten times faster than necromass from starved cultures, which were undergoing biomass loss. By the end of decomposition, only about 10 % of necromass from early-growth-stage biomass remained, while nearly 65 % of necromass from starved biomass persisted. Differences in mycelial biochemical traits, particularly C:N ratio and the degree of branching of glucans, which varied with fungal growth stage at death, explained variation in both decay rates and the size of the persistent fractions. Our findings suggest that the growth stage of fungi at death is a key factor driving fungal necromass decay profiles, with potentially large consequences for the contribution of fungal necromass to soil organic matter stocks.</p>}},
  author       = {{Maillard, François and Lopes Ramos, Danny and Zhang, Bowen and Ahlawat, Ashish and Gill, Allison L. and Troein, Carl and Hedenström, Mattias and Sparrman, Tobias and Persson, Per and Tunlid, Anders}},
  issn         = {{0038-0717}},
  keywords     = {{FTIR; Fungal cell wall; Fungal necromass; NMR; Organic matter decomposition; Raman spectroscopy}},
  language     = {{eng}},
  publisher    = {{Elsevier}},
  series       = {{Soil Biology and Biochemistry}},
  title        = {{Mycelial biomass growth stage at death determines fungal necromass decay dynamics}},
  url          = {{http://dx.doi.org/10.1016/j.soilbio.2025.110079}},
  doi          = {{10.1016/j.soilbio.2025.110079}},
  volume       = {{214}},
  year         = {{2026}},
}