Promoting the O3 flux concept for European forest trees

Amsterdam

2007

S. 587-607

SonderdruckBandaufführung

10045S

137669

Tropospheric ozone (O3) levels are predicted to stay high, being a factor within "global change" with potential effects on the carbon sink strength ot forest trees. Hence, new approaches to O3 risk assessment and their validation are required, allhough appropriate databases for adult trees are scant. Approaches based on extemal O3 exposure are presently being evaluated against the ones on O, flux into Ieaves, as the cumulative uptake has the capacity for deriving O3 risk from cause-effecl relationships. The effective dose, however, needs to account for the trees' O3 defence and tolerance in addition to O3 uptake. The current status of promoting the preferable mechanistic O3 flux concept is highlighted for major regions of Europe, addressing refinements and simplifications needed for routine use. At the pan-European scale, however, the flux-based concept is ready for use in O3 risk assessment and has the potential of meso-scale application at the forest ecosystem level.