Division II.2 Selection of trees

Every second year, at least five trees of each main species present in the plot shall be sampled.

The numbers of trees needed for the sampling shall be selected in such a way that:

• the trees are different from those used for the crown assessment, in order to avoid that successive samplings introduce loss of foliage,

• in case the vitality assessment is restricted to the trees in the sub-plot, the trees for the foliage sampling shall be selected from the remaining part of the total plot. If no sub-plot is used the trees for sampling shall be selected from the trees in the buffer zone. In this case the trees selected for sampling in the buffer zone shall be given a special number,

• the trees belong to the predominant and dominant classes (forest with closed canopy) or to the trees with average height ±20 % (forest with open canopy),

• the trees are in the vicinity of the locations where soil samples were taken for analysis; however care shall be taken that the main roots of the sample trees have not been damaged by soil sampling,

• the trees are representative of the mean defoliation level of the plot (±5 % of the mean foliage loss),

• the trees are representative of the sanitary status of the plot.

The same sample trees shall be sampled over the years; the trees shall be numbered. To avoid damage to the sample trees, it is allowed to alternate between two sets of five trees, when necessary. Each set shall respond to the above conditions.

Only trees of the main species shall be sampled (see Annex I, Chapter 15, item 16).

Trees which are used for the sampling of foliage shall be assessed on crown condition, using the existing or the specially assigned numbers.