EGU General Assembly 2020
© Author(s) 2020. This work is distributed under
the Creative Commons Attribution 4.0 License.

Winter is coming – ecosystem-scale COS exchange during senescence of a deciduous forest

Felix M. Spielmann1, Albin Hammerle1, Alexander Knohl2, Malte Julian Deventer2, and Georg Wohlfahrt1
Felix M. Spielmann et al.
  • 1Universität Innsbruck, Ecology, Biometeorology, Innsbruck, Austria
  • 2University of Goettingen, Bioclimatology, Göttingen, Germany

The gross uptake of CO2 on ecosystem level (GPP) can’t be measured directly, but has to be inferred from models or proxies. One of the newly emerged constrains on GPP is the trace gas carbonyl sulfide (COS). COS enters the plant leaf through the stomata and diffuses through the intercellular space, the cell wall, the plasma membrane and the cytosol like CO2. Within the cytosol, it is then catalyzed by the enzyme carbonic anhydrase (CA) in a one-way reaction to H2S and CO2. Basically, this one way flux would make COS a very promising tracer for GPP on ecosystem level, but there is growing evidence that plants are also capable of emitting COS. Mosses and even vascular plants that are under high stress like drought and fungal infection, have been reported to emit COS. Furthermore, a winter wheat field, that showed a good correlation between the CO2 and COS ecosystem fluxes during the peak growing phase turned into a source for COS after going into senescence. This indicates that yet unknown COS emission processes likely related to plant degradation, could complicate the use of COS as a tracer for GPP.

Since the majority of studies have focused on measuring COS ecosystem fluxes during peak growing times or on evergreen forests, we seek to quantify the relationship between the ecosystem-scale exchange of CO2 and COS of an ecosystem going into senescence.

Between September and November 2019 we deployed our quantum cascade laser (Aerodyne Research Inc., MA, USA) at a beech forest in Leinefelde, Germany to conduct eddy covariance measurements for COS, CO2 and H2O. Our observations started when the beech forest was still green and in full leaf and ended when most of the trees had already shed their leaves. The ecosystem fluxes of COS and CO2 concurrently decreased over the course of our campaign up to the point when we could not observe a net uptake of CO2 anymore. We will further compare the GPP estimates resulting from classical flux partitioning and flux partitioning with the additional use of COS to determine if the model differences increase towards the end of the season.

How to cite: Spielmann, F. M., Hammerle, A., Knohl, A., Deventer, M. J., and Wohlfahrt, G.: Winter is coming – ecosystem-scale COS exchange during senescence of a deciduous forest, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-8871,, 2020


Display file