IMPORTED PRAIRIE SOIL HELPS LANCASTER RESEARCHERS MEASURE TREES' ABILITY TO ABSORB CARBON

8.5 tons of soil from a prairie in Kansas imported to Lancaster University may hold the key in answering questions about whether forests can continue to absorb the world's carbon emissions.

With £ 300k of funding from the National Environment Research Council, Lancaster researchers have set up an experiment which they hope will tell them how much carbon trees are taking in from the air and depositing in the soil and which species of trees might be better at taking in carbon.

The large scale experiment took 18 months to set up and YOUNG trees are now growing in 12 special greenhouses called Solardomes at the Biology Field Station at Lancaster University and researchers hope to measure how much carbon trees take in and transfer to the soil. By using the imported soil, they can trace the changes in the total amount of carbon stored below ground.. Six different tree species with differing physiological traits have been chosen, which may allow responses to elevated CO2 concentrations to be predicted.

Many countries such as USA, Japan, Australia and Canada want to be allowed to use so-called 'carbon sinks' to off-set their CO2 emissions from the burning of fossil fuels. Environmentalists are worried that there is a limit to the amount of carbon that forests can absorb and that the soil may soon reach saturation point.

There is very little known about the potential magnitude of these carbon sinks. Less is known of how long forest soils can continue to act as carbon sinks while atmospheric CO2 concentrations carry on rising at an accelerating rate. Clearly, this is vital information if carbon sinks are effectively going to be traded for increased CO2 emissions.

James Heath from Lancaster University's Biology Field Station explained that the new technique that they are using should enable them to address questions of equal importance to those being dealt with by the most sophisticated facilities for CO2 research in the world.

'We should be able to accurately quantify inputs of carbon to the soil from trees growing at four different CO2 concentrations.

'We do this by making use of large differences in the relative abundance of carbon isotopes (13C and 12C) between our temperate tree species and the soil which has developed beneath a Kansas grassland - hence the importing of 8.5 tons of soil.

'In other words, the carbon already in the Kansas soil has a completely different isotopic signature (13C/12C) to that entering it from the trees. By using mass spectrometry to follow the changes in the 13C/12C ratio of the soil, we can accurately calculate the total amount of carbon the trees are taking from the atmosphere and transferring to the soil - which could potentially act as a long-term carbon sink.'

Ends

For more information Vicky Tyrrell 01524 594120

NOTES

The trees are growing in large pots in 12 Solardomes at the Biology Field Station. The Solardomes have recently been upgraded and refitted with new environmental monitoring equipment. The soil was taken from the Konza Prairie in collaboration with Professor Clenton Owensby, Kansas State University. All the carbon isotope measurements are being carried out at CEH Merlewood and the experiment is funded by the Natural Environment Research Council.

RESEARCHERS

DR. James Heath - Biological Sciences with two PhD students (Edward Ayres and Malcolm Possell)

Dr. Gerhard Kerstiens (Biological Sciences)

Prof. Phil Ineson (York University)

Dr. Helaina Black (CEH Merlewood)

Dr. Richard Bardgett (Biological Sciences)

Prof. Nick Hewitt (Environmental Sciences)

Dr. Sue Owen (Environmental Sciences)