EGU21-13117
https://doi.org/10.5194/egusphere-egu21-13117
EGU General Assembly 2021
© Author(s) 2021. This work is distributed under
the Creative Commons Attribution 4.0 License.

The role of cows on OVOC exchanges of a pasture

Bernard Heinesch1, Colin Michel1, Crist Amelynck2,3, Niels Schoon2, Ahsan Mozaffar2, Marc Aubinet1, Aurélie Bachy1, and Pierre Dumortier1
Bernard Heinesch et al.
  • 1University of Liege, Gembloux Agro-Bio Tech, TERRA Teaching and Research Center, GEMBLOUX, Belgium (bernard.heinesch@ulg.ac.be)
  • 2Atmospheric Composition Division, Royal Belgian Institute for Space Aeronomy
  • 3Department of Chemistry, Ghent University

The presence of cows on a pasture considerably modifies exchanges of biogenic volatile organic compounds (BVOCs). By regulating the biomass present, they can have an impact on the constitutive flux (exchanges from soil and grass that are not induced by leaf wounding or trampling by cows) but they can also cause direct emissions from exhalation and indirect emissions by leaf injury (grazing), trampling and wastes. In this study conducted on the ICOS pasture site of Dorinne (Belgium), we disentangled these different sources/sinks for three oxygenated BVOCs commonly exchanged on grasslands (methanol, acetaldehyde and acetone), using a combination of turbulent flux measurements, enclosure flux measurements, tools to detect the presence and activity of cows in the footprint of the turbulent flux measurements and a flux footprint model. Direct exhalation emissions were low, representing only 2.3% and 10% of the spring total flux of methanol and acetone respectively. Comparison of grazed and non-grazed enclosures pointed out that emissions following leaf wounding were significant for all studied BVOCs, decreased exponentially with time to become negligible after maximum five days. Cow indirect emissions at the pasture scale (turbulent flux measurements) where likely dominated by grazing and were shown to be a major component of the total diurnal flux for each of the three studied BVOCs. Comparison with a hay meadow also showed that the temporal dynamics of those BVOC emissions were very different according to the grass management type, calling for specific parametrization in up-scaling emission models.

How to cite: Heinesch, B., Michel, C., Amelynck, C., Schoon, N., Mozaffar, A., Aubinet, M., Bachy, A., and Dumortier, P.: The role of cows on OVOC exchanges of a pasture, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-13117, https://doi.org/10.5194/egusphere-egu21-13117, 2021.

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