LOCALIZATION OF THE EARLYWOOD-LATEWOOD TRANSITION IN OAK RINGS USING MICRODENSITOMETRIC ANALYSIS

The ring widths and the earlywood-latewood limits in 96 annual rings o f oak (Quercus petraea Liebl.) have been measured by image analysis of cross sections. A microdensitometric analysis has been performed on t he same rings. The position of the earlywood-latewood transition has b een estimated in each ring by searching the intersection of the densit y profile with a threshold of density. This threshold has been compute d in three ways: 1) a fixed threshold, 2) a floating threshold dependi ng on the minimal and maximal densities in the ring and 3) a floating threshold depending on the mean density in the ring. Each method has b een tested with several parameters and the estimated values of the ear lywood and latewood widths and ratios have been compared with the anat omical observations. The second and third methods are more accurate th an the first method. The second method is preferred because the qualit y of the results is less dependent on the choice of the parameters. (( C) Inra/Elsevier, Paris.).