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Necromass of Diverse Root-Associated Fungi Suppresses Decomposition of Native Soil Carbon via Impacts of Their Traits

Summary

When fungi die in soil, their dead remains (necromass) affect how quickly the rest of the soil carbon breaks down. This study found that fungi with dark pigments and certain chemical compositions can actually slow down the decomposition of native soil carbon, helping more carbon stay stored in the soil longer. The researchers identified specific fungal traits like melanin content and growth rates that determine whether fungal remains promote or suppress carbon loss from soil.

Background

Soil fungi play critical roles in carbon cycling through their biomass, enzymatic capabilities, and mycelial structures. When fungi die, their necromass becomes part of soil organic matter and can influence the decomposition of native soil carbon. Understanding how different fungal species and their chemical traits affect this process is important for soil carbon storage and climate regulation.

Objective

To investigate the decomposition dynamics of diverse root-associated fungal necromass, their influence on native soil carbon dynamics, and the relationship between fungal traits and soil carbon processes. The study examined how fungal chemical, morphological, and physiological traits control carbon decomposition and stabilization in soil.

Results

Fungal necromass addition commonly suppressed native soil carbon decomposition (negative priming) and increased resistant carbon pools. Fungal traits including melanin, blackness, C/N ratio, and growth rates were linked to necromass decomposability. Fungi with lower decomposability caused stronger suppression of soil carbon decomposition and were associated with reduced microbial use of resistant carbon pools.

Conclusion

The study provides empirical evidence that root-associated fungal traits directly influence necromass decomposition rates and soil carbon stability. Fungi with high melanin content, high C/N ratios, and slow growth rates produced more recalcitrant necromass that suppressed native soil carbon decomposition and promoted carbon persistence, suggesting potential mechanisms for fungal contributions to soil carbon storage.
  • Published in:Ecology Letters,
  • Study Type:Laboratory Incubation Study,
  • Source: 10.1111/ele.70216; PMID: 40961342
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