Joint International Conference on Long-term Experiments ...

2. WORKING METHODS
Radial increases have different characteristics, which have had an impact upon what
working method was used. Thus, in order to establish the diameter categories from
which samples were taken with the help of the Pressler’s borer, the following issues
were taken into account:
• For the same category of diameters, the variation coefficients of growth have
reduced values, comprised between 20-30%;
• In the same diameter category, the species has little influence upon the variation
factors;
• The variation coefficients of the radial growths decrease from the inferior diameter
categories to the superior ones, as a size order, these are situated between 20-25%;
• Within the same category of diameters, the variation amplitude of the growths is
comprised somewhere in between 0,1 and 1,9;
• The variation coefficients of growth for the whole stand are larger, with regards to
values, than the variation factors established for the diameter categories, superior
to the medium diameter of the stand (Giurgiu V., 1972).
The selection of the trees, for the taking of the growth sample, was made as
follows(Dorog S., 2006):
• all the trees from the trial square were inventoried, established from the 8 cm
diameter upwards;
- the medium diameter of the trees from the test area was established;
- the trees, from which samples were to be taken, were selected; these trees
were chosen so that they would be a part of diameter categories, with values around the
arithmetic average.
The samples obtained with the Pressler’s borer have necessitated preliminary
procedures, before their actual measurement. The preliminary procedures were the
following:
• the conversion through grinding with abrasive paper (granulation 180) of the
samples;
• establishing by visual analysis which parts from the sample come from the inside
and which from the outside of the radial section.
The conversion and measurement of the samples included the following steps (Dorog
S., 2006):
• the scaning of the samples with a specialised program, secondary to the scaner and
saving he pictures in a *bmp format.
• the annual rings were established by means of a specialised programme of picture
analysis;
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