# Commission Regulation (EC) No 1737/2006 of 7 November 2006 laying down detailed rules for the implementation of Regulation (EC) No 2152/2003 of the European Parliament and of the Council concerning monitoring of forests and environmental interactions in the Community, Division III.4: Evaluation for the main broadleaf tree species

Extent: E+W+S+N.I.

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).
Score
Percentage, definition
0
No injury, none of the leaves injured.
1
1 %-5 % of the leaves show ozone symptoms
2
6 %-50 % of the leaves show ozone symptoms
3
51 %-100 % of leaves show ozone symptoms

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Source: https://www.legislation.gov.uk/eur/2006/1737/annex/I/chapter/11/division/III/division/III.4 (the official version)
Page: https://openlegislation.uk/eu-regulation-2006-1737/annex-I/chapter-11/division-III/division-III.4
Contains public sector information licensed under the Open Government Licence v3.0. Source: legislation.gov.uk, The National Archives.