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Contrasting stability of fungal and bacterial communities during long-term decomposition of fungal necromass in Arctic tundra

Summary

Scientists studied how dead fungal material breaks down in Arctic soil over three years. They found that melanized fungi, especially Pseudogymnoascus, are key decomposers that help break down tough fungal material containing melanin. While bacterial diversity increased over time, the fungal community remained relatively stable. Even after three years, about 20% of the fungal material remained undecomposed, suggesting it can help store carbon in Arctic soils.

Background

Fungal necromass represents a substantial proportion of soil carbon in Arctic regions, and understanding its decomposition is crucial for predicting terrestrial carbon cycling in the face of climate change. The biochemical composition of fungal cell walls, particularly melanin content and nitrogen availability, regulates decomposition rates and soil organic matter formation in high-latitude ecosystems.

Objective

To investigate the decomposition rate, chemical changes, and succession of fungal and bacterial communities associated with two types of fungal necromass differing in biochemical properties over a three-year period in Arctic tundra soils.

Results

Up to 20% of fungal necromass remained after three years, with low-quality necromass decomposing more slowly than high-quality necromass. Fungal communities showed relatively stable richness but dynamic succession, with Pseudogymnoascus becoming increasingly dominant, especially on low-quality necromass. Bacterial communities exhibited increasing richness over time with a shift from copiotrophic to oligotrophic species.

Conclusion

The study demonstrates that fungal necromass decomposition in Arctic tundra follows typical ecological patterns with an initial rapid phase followed by slow long-term decomposition of recalcitrant material. Fungal communities remain relatively stable while bacterial communities undergo dynamic changes, highlighting the distinct roles of fungi and bacteria in Arctic soil carbon cycling and sequestration.
  • Published in:Environmental Microbiome,
  • Study Type:Field Experiment,
  • Source: 10.1186/s40793-025-00730-5, PMID: 40542454
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