What is one major role of fungi in soils?

• A. Nitrogen fixation
• B. Long-term carbon storage
• C. Weathering of minerals
• D. Pollutant degradation

Answer: (B)

Fungi influence soils most importantly by driving long-term carbon storage through their role in breaking down plant litter and turning it into stable soil organic matter. They secrete enzymes that decompose complex plant polymers like cellulose and lignin, and the resulting fungal biomass and necromass become part of the soil organic pool. This material tends to be more resistant to quick decomposition, helping accumulate carbon over time. In addition, fungal hyphae help bind soil particles into aggregates, and the glycoprotein glomalin produced by many mycorrhizal fungi acts like a glue that stabilizes those aggregates and protects carbon-containing material from rapid breakdown. This combination of producing carbon-rich, persistent organic matter and enhancing soil structure is why fungi are linked to long-term carbon storage in soils. By contrast, nitrogen fixation is primarily performed by bacteria and not a typical fungal function; mineral weathering is largely driven by physical and chemical processes with some microbial contribution, and pollutant degradation, while possible, is not the general defining role of fungi in soils.