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| Titel |
Interactions among vegetation and ozone, water and nitrogen fluxes in a coastal Mediterranean maquis ecosystem |
| VerfasserIn |
G. Gerosa, A. Finco, S. Mereu, R. Marzuoli, A. Ballarin-Denti |
| 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. 8 ; Nr. 6, no. 8 (2009-08-26), S.1783-1798 |
| Datensatznummer |
250003961
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| Publikation (Nr.) |
 copernicus.org/bg-6-1783-2009.pdf |
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| Zusammenfassung |
Ozone, water and energy fluxes were measured over a Mediterranean maquis
ecosystem from 5 May until 31 July 2007 by means of the eddy
covariance technique. Additional measurements of NOx fluxes were
performed by the aerodynamic gradient technique. Stomatal ozone fluxes were
obtained from water fluxes by a Dry Deposition Inferential Method based on a
big leaf concept.
The maquis ecosystem acted as a net sink for ozone. The different water
availability between late spring and summer was the major cause of the
changes observed in stomatal fluxes, which decreased, together with
evapotranspiration, when the season became drier.
NOx concentrations were significantly dependent on the local
meteorology. NOx fluxes resulted less intense than the ozone fluxes.
However an average upward flux of both NO and NO2 was measured.
The non-stomatal pathways of ozone deposition were investigated. A
correlation of non-stomatal deposition with air humidity and, in a minor
way, with NO2 fluxes was found.
Ozone risk assessment was performed by comparing the exposure and the dose
metrics: AOT40 (Accumulated dose over a threshold of 40 ppb) and
AFst1.6 (Accumulated stomatal flux of ozone over a threshold of 1.6 nmol m−2 s−1). AOT40, both at the measurement height and at canopy
height was greater than the Critical Level for the protection of forests and
semi-natural vegetation (5000 ppb h) adopted by UN-ECE. Also the
AFst1.6 value (12.6 mmol m−2 PLA, Projected Leaf Area) was higher
than the provisional critical dose of 4 mmol m−2 PLA for forests. The
cumulated dose showed two different growth rates in the spring and in the
summer periods, while the exposure showed a more irregular behavior in both
periods. |
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