This oak savannah is burned in a controlled manner. Surprisingly, this leads to more carbon being stored in the soil and thus contributes to climate protection.
Severe forest fires release large parts of the carbon stored in the soil – but this does not always have to be the case. Scientists led by Adam Pellegrini from the Institute of Plant Science at the University of Cambridge have found that fire in ecosystems such as temperate forests, savannas and grasslands can stabilize or even increase the amount of soil carbon. This is because decomposition-resistant charcoal and so-called aggregates are formed during combustion. These are clods of soil that can protect carbon-rich organic material in the middle and thus serve as storage.
“Ecosystems can store enormous amounts of carbon if the frequency and intensity of fires are just right. It’s about the balance between the carbon that gets into the soil through dead plant biomass and the carbon that escapes from the soil through decomposition, erosion and leaching, ”explains Pellegrini. However, if the fires are too strong or occur too often, the dead plant biomass is completely burned, the carbon of which would otherwise be stored in the soil and is now released. In addition, soil bacteria and fungi die, which destabilizes the soil.
The scientists conclude from their observations that ecosystems can be managed in such a way that the amount of carbon in the soil is increased. In grasslands, for example, carbon is mainly stored in the roots, controlled combustion stimulates grass growth and a larger root biomass in turn represents a larger CO2 store.
“When considering how ecosystems should be managed to sequester and store carbon from the atmosphere, fire is often viewed as a bad thing. We hope that this new study will show that when properly managed fire can be good for both biodiversity conservation and carbon storage, ”says Pellegrini. Worldwide, more carbon is stored in soils than in vegetation and atmosphere combined. Fires therefore play a major role in the global carbon cycle and, if used in a targeted manner, they can even contribute to climate protection.