ANR ORCA WP1

Rationale

Although COS uptake by the biosphere is thought to be roughly proportional to the GPP of plants, the dynamics of COS and CO2 concentration variations do not appear to follow the same seasonal pattern at large scales. Indeed, even if COS is fully hydrolysed within the leaf mesophyll (the current assumption), depending on where COS is hydrolysed and how its transport is regulated from outside the leaf to the point of catalysis, COS uptake and GPP may not necessarily scale with one another. Furthermore, a number of studies now indicate that COS is taken up by plants and ecosystems in the dark when no photosynthesis occurs. This is because CA-catalysed hydrolysis is not a light-dependent reaction, and as long as plant stomata remain open in the dark (even partially) then hydrolysis of COS can continue. Thus, before using a general relationship linking GPP and COS fluxes to upscale, a number of caveats must be considered, regarding the location of COS hydrolysis within the leaf mesophyll and the temporal variability of daily and nocturnal COS uptake rates in relationship to daylight GPP.

Objective

The overall objective of WP1 is to characterise the COS transport and CA activity within the leaf using gas exchange and isotopic tracing techniques on wild species but also mutants with different CA isoforms, in order to better understand how COS and CO2 fluxes are related at the leaf level and respond to environmental factors.

Jason West, performing carbon and oxygen isotope gas exchange measurements on poplar leaves.

On-going results and publications

Peer-reviewed journals
Communications at international conferences

Gimeno T., Royles J., Ogée J., Jones S., Burlett R., West J., Sauze J., Wohl S., Genty B., Griffiths H., & Wingate L. (2016) Investigating the impact of light and water status on the exchange of COS, 13CO2, CO18O and H218O from bryophytes. European Geophysical Union (EGU) Annual Meeting, Vienna, Austria, 17th-22nd April 2016.

West J., Ogée J., Burlett R., Gimeno T., Genty B., Jones S., Wohl S., Bosc A. & Wingate L. (2016) A new approach to quantifying internal diffusion resistances and CO2 isotope exchange in leaves. European Geophysical Union (EGU) Annual Meeting, Vienna, Austria, 17th-22nd April 2016.

Ogée J., Wehr R., Commane R., Launois T., Meredith L., Munger B., Nelson D., Saleska S., Zahniser M., Wofsy S. & Wingate L. (2016) Developing multi-tracer approaches to constrain the parameterisation of leaf and soil CO2 and H2O exchange in land surface models. European Geophysical Union (EGU) Annual Meeting, Vienna, Austria, 17th-22nd April 2016.

Wingate L., Wehr R., Commane R., Ogée J. Sauze J., Jones S., Launois T., Wohl S., Whelan M., Meredith L., Genty B., Gimeno T., Kesselmeier J., Bosc A., Cuntz M., Munger B., Nelson D., Saleska S., Wofsy S. & Zahniser M. (2015) The impact of Carbonic Anhydrase on the partitioning of leaf and soil CO18O and COS gas exchange across scales. American Geophysical Union (AGU) Fall Meeting, San Francisco, California, USA, 14th-18th December 2015. (invited)