Anyone who follows this page, or who follows the debate over moorland management in any way, will already be well aware of the many attempts by anti-shooting campaigners to ban the controlled burning of heather in the uplands. We have covered the arguments in favour of rotational burning so many times on this page that we are sure our readers are aware of them; but in short, they help prevent wildfires by removing old and dead vegetation that create fuel load, as well as creating fire breaks; they encourage new vegetation, and create a mosaic of habitats which encourages a diverse range of wildlife.
Despite this, campaigners still push for rotational burning to be banned in the name of carbon capture; just this week, Bradford Council wrote to Defra encouraging them to introduce a ban on all heather burning.
New research has just been published, however, which adds yet another aspect to the burning debate, and reinforces why upland land managers choose heather burning as a tool. A study from the University of Cambridge – published in the journal Nature Geoscience – has confirmed that controlled burning can in fact increase carbon in the soil.
The study found that controlled burns cause changes in soil composition which as well as offsetting immediate carbon losses, can actually lock in or increase carbon in the soils of forests and grasslands.
“Most of the fires in natural ecosystems around the globe are controlled burns, so we should see this as an opportunity”, said Dr Adam Pellegrini in the University of Cambridge’s Department of Plant Sciences, the first author of the report. “Humans are manipulating a process, so we may as well figure out how to manipulate it to maximise carbon storage in the soil.”
Fire stabilises carbon within the soil by creating charcoal, which is very resistant to decomposition, and forms ‘aggregates’ – physical clumps of soil that can protect carbon-rich organic matter at the centre. Fire can also increase the amount of carbon bound tightly to minerals in the soil.
The study confirmed that infrequent, cooler fires – such as those used by moorland managers during rotational burning – can increase the retention of soil carbon through the formation of charcoal and soil aggregates that protect from decomposition.
The scientists who carried out the study also say that ecosystems can – and perhaps should – be managed to increase the amount of carbon stored in their soils. Much of the carbon in grasslands is stored below-ground, in the roots of the plants. Controlled burning, which helps encourage grass growth, can increase root biomass and therefore increase the amount of carbon stored.
“In considering how ecosystems should be managed to capture and store carbon from the atmosphere, fire is often seen as a bad thing. We hope this new study will show that when managed properly, fire can also be good – both for maintaining biodiversity and for carbon storage,” said Pellegrini.