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| Titel |
Isoprene and monoterpene emissions from a mixed temperate forest. |
| VerfasserIn |
Quentin Laffineur, Bernard Heinesch, Crist Amelynck, Niels Schoon, Jean-Francois Müller, Jo Dewulf, Herman Van Langenhove, Eva Joó, Kathy Steppe, Marc Aubinet |
| Konferenz |
EGU General Assembly 2011
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 13 (2011) |
| Datensatznummer |
250053166
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| Zusammenfassung |
| Isoprene (IP) and monoterpenes (MTP) are the most abundant biogenic volatile organic
compounds (BVOCs) emitted by terrestrial vegetation, particularly by forests. Global IP and
MTP emissions are estimated to be 460 TgCÂ yr-1 and 117 TgCÂ yr-1, respectively,
representing 80% of the total BVOC emissions. These components have a significant impact
on atmospheric chemistry and physics.
Long term ecosystem-scale BVOC flux measurement is the sole method allowing
quantification and description of BVOC emission responses to episodic events like
budburst or stress; follow up of emission during vegetation growth and analysis of
interaction with climate and environment. We will analyse the IP and MTP fluxes
measured above a mixed temperate forest in order to illustrate the interest of long-term
flux measurements by investigating the main driving variables and the underlying
mechanisms of emission, how de novo carbon allocation to the isoprene/monoterpenes
skeleton structure is altered through time. A disjunct eddy covariance system was
installed at the forested site of Vielsalm (Belgium) from July to October 2009 and
from April to October 2010 covering thus most of the vegetation season (spring,
summer and first part of autumn). The system was completed by micrometeorological
measurements and an eddy covariance system measuring continuously CO2 and H2O
fluxes.
During the day, IP and MTP fluxes were mainly controlled by air temperature and light.
This behavior resulted largely from a response of IP and MTP flux to photosynthesis itself.
Indeed, a strong linear relation was found between these fluxes and the Gross Primary
Production. In addition to these responses, a flux seasonal evolution was observed: a decrease
in the standard emission factor was observed, probably due to acclimation or senescence. The
standard emission factor (30Ë C, 1000 μmol m-2 s-1) varied from 0.91 ±Â 0.01 to
0.56 ±Â 0.02 μg m-2 s-1 for IP fluxes and from 0.74 ±Â 0.03 to 0.27 ±Â 0.03 μg m-2
s-1for MTP fluxes.
During the night, IP flux was zero but a slight positive MTP flux was observed that
seemed to be driven by air temperature. These night emissions were probably due to the
volatility of monoterpenes stored in the needle resin ducts of coniferous species. There could
also be a contribution from the soil through litter decomposition, from roots or from
micro-organisms. The standard emission factor (30Ë C) for night-time MTP fluxes was equal
to 0.093 ±Â 0.019 μg m-2s-1. |
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