Ecology: Wildfires may increase carbon storage in some circumstances

Vegetation type may determine if wildfires lead to more carbon being stored than released, according to a mathematical modelling study published in Nature Geoscience. However, future observational efforts will be needed to better constrain these complex interactions.

Wildfires are destructive processes that can burn through ecosystems, devastate lives, and release substantial amounts of carbon dioxide and other greenhouse gasses into the atmosphere. However, the charring of biomass can also transform the carbon within soil to make it more resistant to oxidation and the processes of being released back into the atmosphere as carbon dioxide.

Simon Bowring and colleagues used a land surface model to assess the global impact of fires on the Earth’s carbon cycle between 1901 and 2010. Owing to a lack of observations, the authors rely on numerous mathematical assumptions to support their estimate that approximately 0-89 teragrams (89 x 1012 grams) of carbon per year could be retained within soils for many thousands of years due to the processes of burning. However, the impacts of fires vary substantially according to vegetation. In their models, burned grasslands dominate carbon storage whilst forest fires are a source of carbon to the atmosphere.

The authors emphasize that, if we are to decipher the true role of fire in the global carbon cycle, efforts must be made to better quantify the amount of fire-transformed carbon that can be stored in soils along with the understanding of its long-term stability.

doi: 10.1038/s41561-021-00892-0

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