0 Tuovinen, J-P. Emberson, L. Simpson, D. 2009 Annals of Forest Science 66 401 ozone,risk assessment /stomatal flux /modelling / <p>• Risk assessment of ozone effects on forests is gradually moving from concentration-based exposure<br /> metrics to a more complicated approach that requires modelling of ozone fluxes to trees.<br /> • This study reviews the status of the DO3 SE stomatal flux model employed within the Convention<br /> on Long-range Transboundary Air Pollution, describing a range of applications and identifying ma-<br /> forest monitoring jor research needs, especially in the context of support that could be provided by the International<br /> Co-operative Programme on Assessment and Monitoring of Air Pollution Effects on Forests.<br /> • The most urgent development need for DO3 SE is the modelling of the soil moisture status and its<br /> effect on stomatal conductance. Furthermore, the data related to the physical characteristics and the<br /> seasonal dynamics of physiological activity of vegetation continue to pose problems.<br /> • There is a clear need for more extensive validation of models and risk estimates using more rigorous<br /> statistical procedures and comparisons with flux networks and satellites.<br /> • The current large-scale forest monitoring activities provide only limited possibilities for flux mod-<br /> elling, but could be enhanced by introducing a new monitoring strategy outlined here.</p> www.afs-journal.org