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Warming and Reduced Rainfall Alter Fungal Necromass Decomposition Rates and Associated Microbial Community Composition and Functioning at a Temperate–Boreal Forest Ecotone

Summary

When soil gets warmer and drier due to climate change, dead fungal biomass breaks down faster at first but slower overall compared to normal conditions. The microorganisms that decompose this fungal material change their composition and abilities depending on how long the decomposition has been happening. This study shows that climate change affects soil carbon cycling in complex ways that depend on timing and environmental conditions.

Background

Fungal necromass constitutes a significant portion of soil organic carbon pools and represents a rapidly cycling component. Climate change is expected to increase temperatures and alter precipitation patterns in temperate and boreal forests, potentially affecting decomposition dynamics and microbial community functioning.

Objective

To determine how combined warming (+3.3°C) and reduced rainfall (~40% reduction) impacts fungal necromass decomposition rates, microbial community composition, and functional capacity at a temperate-boreal forest ecotone.

Results

Warming and reduced rainfall accelerated initial necromass decay by ~20% over the first 2 weeks, but resulted in ~6% greater mass remaining at 14 weeks. The necrobiome composition shifted toward fast-growing fungi and copiotrophic bacteria under altered conditions, with higher fungal-to-bacterial ratios. Microbial substrate utilization capacity was higher in altered plots early in decomposition but reversed later, with ambient plot communities showing greater degradation capacity.

Conclusion

Fungal necromass decomposition responds to climate change in a stage-dependent manner, with initial stimulation followed by inhibition under warming and reduced rainfall. This dynamic response reflects synergistic interactions between shifting abiotic conditions, necromass substrate chemistry, and microbial community functional capacity, with implications for soil carbon and nitrogen cycling.
  • Published in:Global Change Biology,
  • Study Type:Field Experiment,
  • Source: PMID: 41065083, DOI: 10.1111/gcb.70536
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