Field campaign

Whole tree 13CO2 labelling

Since a few days we have now labelled in total 10 100-year old Scots pine trees with 13C enriched CO2 at the field site Pfynwald to trace the fate of carbon within the tree and ecosystem. The Pfynwald precipitation manipulation experiment that started in 2003 aims at releasing drought stress from adult pine trees growing at this stand in the Valais close to its area of distribution. On the one hand non-irrigated trees are more and more prone to mortality due to the increasing frequency of drought event, on the other hand the irrigation treatment (doubling the amount of the natural precipitation) resulted in a clear increase in growth and a reduction of mortality.
The 13C labelling of the trees of both treatment should now show if and how the allocation and distribution of newly assimilated carbon is affected by this long-term difference in water availability. With an international team with researchers from Switzerland, Germany, China and Finland we track the 13C label in different plant and ecosystem compartments (leaves, phloem, fine roots, soil microbes) and chemical compounds (resin, respired CO2, storage compounds) in order to understand if switches in C allocation under drought might lead to lack of reserves over longer times or predispose trees to insect attacks.

related film in the Swiss Television (in German)