Linking soil microbial community to the chemical composition of dissolved organic matter in a boreal forest during freeze–thaw cycles

Summary

This incubation study investigated how freeze–thaw cycles typical of boreal forest warming alter the interactions between soil microbial communities and dissolved organic matter (DOM) chemistry. The authors found that freeze–thaw cycles increased DOM availability and activated molecular components, with bacterial communities showing greater sensitivity to the disturbance than fungal communities, and significant shifts in community network structure indicating enhanced microbial-substrate interactions. These findings suggest that warming-induced freeze–thaw intensity may promote soil carbon turnover and DOM stabilisation in boreal systems.

Regional applicability

The boreal forest context and freeze–thaw cycle mechanisms are not directly representative of United Kingdom soil conditions, which experience milder winters and different soil temperature dynamics. However, the molecular understanding of how freeze–thaw stress alters microbial community function and DOM bioavailability may have transferable implications for UK upland and northern soils subject to winter temperature fluctuations.

Key measures

Dissolved organic carbon (DOC) content; ammonium nitrogen (NH₄⁺-N); DOM chemical composition (aromatic compounds, polysaccharides, fatty acid methyl esters); bacterial and fungal community composition; bacterial and fungal network connectivity metrics; α-diversity; relative abundance of dominant phyla

Outcomes reported

The study measured changes in dissolved organic matter (DOM) chemical composition and soil microbial community structure in response to freeze–thaw cycles using pyrolysis gas chromatography-mass spectrometry and high-throughput sequencing. Both bacterial and fungal community responses were characterised alongside DOM fingerprinting to elucidate microbial-DOM interactions.

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