Macrofungi promote SOC decomposition and weaken sequestration by modulating soil microbial function in temperate...

Area of Science:

• Soil Science
• Ecology
• Microbiology

Background:

• Soil organic carbon (SOC) sequestration is vital for grassland ecosystems.
• Macrofungi, particularly through their mycelia, influence carbon cycling, but their precise impact on SOC storage in grasslands is not fully understood.
• Fairy rings offer a unique model to study macrofungal effects on SOC.

Purpose of the Study:

• To investigate the effects of macrofungi on SOC fractions (POC, MAOC) and microbial mechanisms of SOC storage in a temperate steppe.
• To analyze changes in microbial community structure and functional genes related to carbon cycling in response to macrofungal presence.

Main Methods:

• Topsoil samples (0-10 cm) were collected from four grassland fairy ring zones.
• SOC fractions (POC, MAOC), microbial biomass carbon (MBC), and enzyme activity (β-1,4-glucosidase) were measured.
• Metagenomic sequencing was employed to analyze microbial community composition and functional gene abundance.

Main Results:

• Macrofungal presence led to a 7.37% reduction in total SOC, with decreases in both POC and MAOC.
• Microbial biomass carbon (MBC) decreased, while β-1,4-glucosidase activity and dissolved organic carbon (DOC) increased.
• Shift in microbial community towards copiotrophs and away from oligotrophs, with reduced C-fixation genes and increased C-degradation genes (especially hemicellulosic).

Conclusions:

• Macrofungi reduce SOC storage in grasslands by inhibiting microbial carbon sequestration and promoting carbon decomposition.
• Fungal activity alters soil microbial community structure and function, favoring decomposition pathways.
• These findings enhance mechanistic understanding of SOC persistence and the role of macrofungi-microbe interactions.