Guest essay by Eric Worrall

University of Stirling researchers have received a £800K grant to study what proportion of carbon captured by soil is from partially burned plants.

NEWS RELEASE 12-MAY-2020
£800k study to look at link between fire and climate change

UNIVERSITY OF STIRLING

University of Stirling experts will lead a new £800,000 study investigating the behaviour of pyrogenic carbon – partly-burned plants left behind following fire – and its potential impact on climate change.

Fires affect more than 500 million hectares of the world’s surface each year – with the majority occurring naturally – and leave residues of pyrogenic carbon (PyC), similar to charcoal.

However, due to the lack of data available, it is not clear what proportion of soil carbon derives from PyC; by which processes PyC is incorporated into the soil; how quickly it returns to the atmosphere as carbon dioxide; and how these processes may be impacted by climatic conditions.

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Dr Subke, Lead Principal Investigator, said: “It is estimated that pyrogenic carbon contributes between 116 and 379 teragrams of carbon to soils each year – a considerable amount given that the annual net increase of carbon to all of Earth’s ecosystems on land is around 4,300 teragrams. In some fire-prone ecosystems – such as tropical savannahs – deposits from fire can account for as much as half of total carbon stored in soils.

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Read more: https://www.eurekalert.org/pub_releases/2020-05/uos-st050820.php

I confess I never really thought about the difference between soil charcoal from fires and soil carbon from decomposition of forest debris. But Dr. Subke’s point that up to half the carbon sequestered in some soil could be fire residue, and that it is not known about how much fire contributes to soil carbon content, makes you wonder how accurate current models of soil carbon are.