25 March 2024

In peatlands, climate change supports the degradation of organic carbon

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An experiment shows that in peatlands all organic soil components decompose more rapidly when temperatures are higher

by Matteo Cavallito

 

Peatlands would be more vulnerable than expected to climate change. Rising temperatures, in particular, would stimulate the breakdown of all components of organic matter in the same way thus contradicting a previous hypothesis. This is stated in a research published in the journal Nature Communications.

Climate change impacts peatlands

The team of researchers, which includes scientists from several institutions including the University of Zurich, CEREEP-Ecotron IleDeFrance in Saint-Pierre-lès-Nemours, Oak Ridge National Laboratory and other U.S. universities, worked at an experimental site called SPRUCE and located in northern Minnesota, in the United States, heating the environment to simulate the effects of climate change in peatlands. The four-year study analyzed the impact of rising temperatures and atmospheric CO2 concentrations, highlighting the vulnerability of these ecosystems.

“Peatlands, are cold, water-saturated, and acidic,” explains a statement quoted by the U.S. Department of Energy. “These conditions slow microbes’ decomposition of organic matter into greenhouse gases. This process stores carbon in the soil.”

Researchers “tested whether different components of the organic matter in soil would degrade at different rates in response to climate change. Surprisingly, the experiments showed that all organic soil components can break down more quickly in warmer conditions.”

The study

In detail, “Four years of experimental warming decreased SOC (soil organic carbon) molecules content in the surface peat (0–30 cm),” the study explains. “Solvent-extractable compounds of plant and microbial origins declined by 30% between the 0 and 9 °C treatments.”

Furthermore, under the same conditions, “plant-derived hydrolysable biopolymers that presumably cycle more slowly, decreased by 14%.” The researchers, in other words, found that all molecular compounds are vulnerable to changes in climatic factors.

La distribuzione delle torbiere in Europa. FONTE: JRC Commissione Europea.

The distribution of peatlands in Europe. SOURCE: JRC European Commission.

Peatlands store one-third of the Planet’s organic carbon

Peatlands, researchers observe, store one-third of the Earth’s soil organic carbon and have continued to sequester the element for millennia. Rising temperatures now threaten “to destabilize” this reservoir by stimulating “microbial decomposition that fuels greenhouse production in response to warming.” Rising temperatures and CO2 concentrations, finally, “could result in larger amounts of degradable substances produced by plants that in turn support microbes that produce greenhouse gases.” Thus exacerbating climate change.

“Peatlands build C stocks over centuries,” the research recalls. But rising temperatures and increasing atmospheric CO2 concentrations “rapidly changed the equilibrium at SPRUCE within a 4-year timescale, highlighting the vulnerability of these C-rich ecosystems to global change.”