'Carbon vault' peat suffers from drought

10 January 2024 Research news item

Peatlands are affected more by drought than expected. This is concerning, as these ecosystems are an important ally in the fight against climate change. Following long periods of drought, peat is able to absorb little to no extra carbon (CO2). Increasing biodiversity also does little to make peat more drought-resilient. These are the conclusions drawn by researchers from Radboud University in a publication appearing today in Proceedings of the Royal Society B.

Peat is a vast carbon sink: per square metre it is able to store more CO2 than any other ecosystem in the world. The peatlands of the Netherlands, but also those in places such as Scandinavia and the Baltic states, therefore play an important role in the fight against climate change. However, peat is coming under increasing pressure and is extremely sensitive to the dry summers we are experiencing as a result of climate change. This is what researchers from the Radboud Institute for Biological and Environmental Sciences have concluded.

‘In our lab, under controlled conditions, we first ensured that large blocks of peat were well moistened over a long period of time’, explains lead author Bjorn Robroek. ‘We then slowly dried the peat out. One half was exposed to mild drought, with the water level roughly five centimetres lower than the peat itself. The other half was subjected to extreme drought conditions; in this case the water was twenty centimetres below the peat. This is comparable to a period of three weeks without rain – something that has also become increasingly common in the Netherlands in recent years.’

These experiments revealed that peat exposed to mild drought still absorbs a reasonable amount of carbon. Robroek: ‘Under extreme drought conditions, however, the peat can hardly take on any more carbon. In the event of an extended period of drought it even releases the carbon again.’

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