30 November 2023

This is how fungi regulate the carbon cycle in forests

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Chinese research highlights how different categories of mycorrhizal fungi record different nutrient uptake while impacting biomass and soil carbon

by Matteo Cavallito

 

The presence of different species of fungi affects soil carbon uptake capacity. This is reported in a recent research by a group of scientists led by Zhu Jiaojun, a professor at the Institute of Applied Ecology of the Chinese Academy of Sciences (CAS). The investigation, published in the journal Nature Climate Change, specifically highlighted the dynamics between mycorrhizal species and plant biomass in forest ecosystems under conditions of nitrogen deposition and warming.

“Forest ecosystems store ~80% of the carbon in terrestrial ecosystems, but their long-term carbon sequestration depends partly on how plant biomass and soil carbon stocks will respond to global changes,” the study says. That response, anyway, “remains uncertain.”

The importance of mycorrhizal fungi

This study examines the two most common species of mycorrhizal fungi that play a key role in soil dynamics: arbuscules (AM) and ectomycorrhizal fungi (ECM). The interaction of these with plants is critical to the carbon cycle in forests. Indeed, it influences the growth of the plants themselves, the acquisition of nutrients and the storage of the element in the soil.

Chinese researchers had already studied subsurface carbon accumulation in Qingyuan forest in the south of the country. The results, recalls a statement from the Beijing Academy of Sciences, showed 25 percent higher subsurface carbon stocks in forests dominated by shrubs when compared with those where ectomycorrhizal fungi were prevalent. The ways in which fungi affect carbon distribution among trees, however, is still unclear.

The study

The researchers conducted a meta-analysis on previous experimental observations that had collected plant and soil carbon data from around the world. Specifically, the authors collected more than three thousand data sets on forest biomass, soil carbon, and other environmental factors. Such as nitrogen deposition and higher temperatures.

In doing so, “They found that plant biomass increased 17.9%-31.4% under global change drivers whereas soil C stocks varied depending on specific global change drivers in forest ecosystems” according to the statement.

The impact on carbon

In detail, “Soil C stocks increased 7.8% under elevated CO2 due to increasing root biomass and microbial activity. However, soil C stocks did not significant change under N deposition and warming as a result of soil acidification and priming effect.”

Moreover, “Under nitrogen deposition and warming, soil carbon stock depended on mycorrhizal associations, decreasing in forests dominated by arbuscular mycorrhizal tree species while increasing in forests dominated by ectomycorrhizal tree species.” These results thus highlight the presence of an interaction between fungi, plant biomass and soil carbon sequestration in forests.