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| Titel |
Measurement and modelling ozone fluxes over a cut and fertilized grassland |
| VerfasserIn |
R. Meszaros, L. Horvath, T. Weidinger, A. Neftel, E. Nemitz, U. Dämmgen, P. Cellier, B. Loubet |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1726-4170
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| Digitales Dokument |
URL |
| Erschienen |
In: Biogeosciences ; 6, no. 10 ; Nr. 6, no. 10 (2009-10-02), S.1987-1999 |
| Datensatznummer |
250004027
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| Publikation (Nr.) |
 copernicus.org/bg-6-1987-2009.pdf |
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| Zusammenfassung |
| During the GRAMINAE Integrated Experiment between 20 May and 15 June 2000,
the ozone flux was measured by the eddy covariance method above intensively
managed grassland in Braunschweig, northern Germany. Three different phases
of vegetation were covered during the measuring campaign: tall grass canopy
before cut (29 May 2000), short grass after cut, and re-growing vegetation
after fertilization (5 June 2000). Results show that beside weather
conditions, the agricultural activities significantly influenced the O3
fluxes. After the cut the daytime average of the deposition velocity
(vd) decreased from 0.44 cm s−1 to 0.26 cm s−1 and increased
again to 0.32 cm s−1 during the third period. Detailed model
calculations were carried out to estimate deposition velocity and ozone
flux. The model captures the general diurnal patter of deposition, with
vd daytime values of 0.52, 0.24, and 0.35 cm s−1 in the first,
second and third period, respectively. Thus the model predicts a stronger
response to the cut than the measurements, which is nevertheless smaller
than expected on the basis of change in leaf area. The results show that
both cut and fertilization have complex impacts on fluxes. Reduction of
vegetation by cutting decreased the stomatal flux initially greatly, but the
stomatal flux recovered to 80% of its original value within a week. At
the same time, the non-stomatal flux appears to have increased directly
after the cut, which the model partially explains by an increase in the
deposition to the soil. A missing sink after the cut may be the chemical
interaction with biogenic volatile organic compounds released after the cut
and exposed senescent plant parts, or the increase in soil NO emissions
after fertilization. Increased canopy temperatures may also have promoted
ozone destruction on leaf surfaces. These results demonstrate the importance
of canopy structure and non-stomatal pathways on O3 fluxes. |
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