Joint International Conference on Long-term Experiments ...

Image no.1 ImageTool programme was used to get the width of the annual rings
• the width of the annual rings was obtained with the Distance option from the
ImageTool programme;
• saving the results and transforming the size of the annual rings from dpi into
milimeters.
For this process of transformation of the pixels into milimeters, the following pattern
was used: Ring width (mm) = 0,042333*Ring width (dpi)
The equation coefficients (Leahu I., 1990) were established by the following steps:
• The obtaining of the medium growth for each particular tree;
• Establishing the growth average for all the samples taken from a type of
environment;
• The establishing of the medium diameter for the diameter categories and within
these, there were trees from which samples were taken with Pressler’s borer;
• The calculating of the relative values for the entire string of diameter values and of
the relative values of the medium growths, respectively.
3. RESULTS AND CONCLUSIONS
On the basis of the algorythm presented previously, after the calculations, the following
values of the regression equation coefficients were obtained. These coefficients are
presented in the table below.
Table nr. 1Regression equation coefficients and the string of values which they are
suitable for
The linear regression equation coefficients
(y = ax+b)
Type of site
Coefficients Limit diameters
a b Minimum maximum
5153 0,0021 0,8486 16 40
5242 0,0462 0,7431 34 66
5243 0,0059 0,8274 24 64
499