Mycorrhizal mycelium as a global carbon pool

Area of Science:

• Ecology
• Mycology
• Soil Science

Background:

• Mycorrhizal fungi form crucial symbiotic relationships with plants, essential for ecosystem function.
• While their role in plant nutrition is known, their global impact on soil carbon storage is under-explored.
• Terrestrial carbon storage is largely belowground, with mycorrhizal fungi at a key entry point for soil carbon.

Purpose of the Study:

• To provide the first global quantitative estimates of carbon allocation from plants to mycorrhizal fungi.
• To assess the significance of mycorrhizal fungi in global carbon cycling.
• To explore mechanisms of soil carbon alteration by mycorrhizal fungi and identify research needs.

Main Methods:

• Analysis of nearly 200 global datasets on plant-fungal carbon allocation.
• Quantitative estimation of carbon allocated to arbuscular, ectomycorrhizal, and ericoid mycorrhizal fungi.
• Exploration of fungal mechanisms influencing soil carbon pools.

Main Results:

• Global plant communities allocate an estimated 13.12 Gt CO2e annually to mycorrhizal fungi.
• This allocation represents approximately 36% of current annual CO2 emissions from fossil fuels.
• Specific allocations: 3.93 Gt CO2e to arbuscular, 9.07 Gt CO2e to ectomycorrhizal, and 0.12 Gt CO2e to ericoid mycorrhizal fungi.

Conclusions:

• Mycorrhizal associations make a significant, confirmed contribution to global carbon dynamics.
• Findings highlight the need to include mycorrhizal fungi in climate and carbon cycling models.
• The study advocates for integrating mycorrhizal fungi into conservation policy and practice.