Division II.4 Selection and quantity of leaves and needles

The trees in the plot shall not be felled, which may influence the sampling method of leaves or needles. It is important that sampled leaves or needles have developed in full light.

The sampled leaves or needles shall be taken from the upper third of crown, but not from the very first whorls in the conifers;

For deciduous species, sampling shall be done on current year leaves or needles.

For evergreen species, sampling shall be done of both the current year needles or leaves and the second year needles or leaves (current + 1).

For all species it is necessary to take care that leaves or needles which are sampled are mature ones, especially for species which have several flushes per year (e.g. Pinus Halepensis, Pseudotsuga menziesii, Eucalyptus sp. Quercus sp.) For Larix sp. and Cedrus sp. samples are taken of the short twigs of the previous year.

In general, sampling shall be carried out in such a way that all the orientations are represented in the set of sample trees. If necessary it is allowed to sample different orientations on each tree of the sample set. In special sites with evident influence of one orientation (e.g. steep slopes or strong dominant wind) only one orientation is sampled, which always has to be the same. In such cases, it is necessary to document the orientation.

For the analysis of major elements and Fe, Mn, Zn, Cu, the recommended quantity is 30 grams of fresh needles or leaves for each sampled age class.

Each country may decide to sample a larger quantity of leaf material, according to the need of its own analytical methods, or in order to conserve samples for the future.