A new study has revealed how different types of mycorrhizal fungi associated with trees influence soil organic carbon (SOC) storage in temperate forests. Published in Functional Ecology, the study, led by researchers from the Institute of Applied Ecology of the Chinese Academy of Sciences, offers new insights into the important role of tree mycorrhizal type in determining SOC stocks at local scales in a temperate forest.

In temperate forests, trees form symbiotic associations—mutually beneficial partnerships—with two major fungal types: arbuscular mycorrhizal (AM) fungi and ectomycorrhizal (EcM) fungi. It is known that these fungal partnerships influence the levels of SOC, however, the exact local-scale processes had not been fully understood.

The research was conducted in a 25-hectare broad-leaved Korean pine forest in Changbai Mountain, where the team assessed various factors influencing SOC storage. Their findings revealed that vegetation traits, such as plant diversity and root structure, accounted for 45% of the variation in SOC storage—almost double the influence of soil microbes (26%) and physical soil factors like composition (20%). Specifically, SOC storage increased in areas with richer plant species, diverse leaf litter inputs (litter refers to naturally fallen leaves and branches), and larger tree roots, but declined in soils with higher clay and silt content.

Additionally, forest areas where EcM-associated trees prevail tended to have reduced SOC, a trend that might be due to lower tree species diversity, excessive carbon-rich leaf litter accumulation, and distinctly structured soil microbial communities.

These insights highlight the significant role of tree mycorrhizal associations in regulating the complex interactions between aboveground and belowground systems. Understanding these relationships offers a new perspective on the biological mechanisms governing SOC accumulation in forest ecosystems. This suggests that forest management strategies could enhance soil carbon storage by prioritizing mycorrhizal community dynamics.

Influence of tree mycorrhizal types, plant, and microbial community attributes on soil organic carbon storage (Image by ZHANG Meixu)