Division III.4 Evaluation for the main broadleaf tree species

For the main tree species, five branches (as small as possible, but with all leaf age stages present) from each tree shall be pruned from the sun exposed portion of the upper third of the crown, simultaneously with the biannual foliar sampling for the chemical analysis of needles and leaves or according to the local symptoms phenology if possible. Once collected, a representative number of leaves per branch (i.e. approximately 30 leaves in the case of Fagus sylvatica) shall be examined under best light conditions and scored for occurrence of ozone-injury (yes/no).