Technique tests soil CO2 emissions

Almost £500,000 has been awarded to scientists who want to see if climate change could affect the levels of CO₂ released from Europe's soils.

The Natural Environment Research Council grant will enable Prof David Robinson and Prof Pete Smith from the Institute of Biological and Environmental Sciences at Aberdeen University, and Prof Pete Millard and Dr Andy Midwood of the Macaulay Land Use Research Institute to test if soils are likely to release more CO₂ if Europe's climate changes.

Increases in atmospheric CO₂ are a main driver of climate change, and a potentially large source of CO₂ is in the organic matter in soil. If the climate warms up or becomes wetter this might encourage soil microbes to produce more CO₂ that will enter the atmosphere.

The researchers will use a novel technique developed at the Macaulay Institute to determine whether CO₂ is being released from young organic matter in soil – mainly dead plant remains – or from much older material: so-called 'historical' soil organic matter.

Robinson said: 'If CO₂ produced from the old organic matter outstrips that taken up by vegetation, it will contribute to the continuing CO₂ increases in the atmosphere. We need to know the climatic conditions when this is likely to occur.'

Soil provides a vast reservoir into which CO₂ taken up from the atmosphere by living plants is transferred when they die, and where it can be stored as organic matter for thousands of years.

But when soil is disturbed during vegetation burning or clearing, or if soil microbes respond to warmer climates, the release of CO₂ from the large underground carbon stores can increase. 

Millard added: 'Many people know that CO₂ is released from cars and factories, but emissions from soil are also an important factor contributing to climate change.'

The research team will visit forest sites in continental Europe during the next two years, from Italy to Finland, to measure CO₂ emissions across the widest range of climatic conditions.

The potential impact of their results will be analysed back in Aberdeen using computer models that predict possible future climates.