Automatic Measurement of Vessel Lumen Area and Diameter With Particular Reference to Pedunculate Oak and Common Beech

Abstract

A method for measuring cell diameter and area in transverse seetions of wood with an automatie image analyser is described. The parameters measured were vessel lumen area, vcssel lumen diameter and percentage conductive area (PCA). The automatie image analyser was used to measure these parameters in root, trunk and branch wood of pedunculate oak (Quercus robur L.) and European beech (Fagus sylvatica L.). The measurements were compared with those obtained with a digitiser from sampies of holm oak (Quercus ilex L.) and Turner's oak (Quercus × turneri Willd. = Quercus ilex × Q. rabur). Both techniques permit the rapid examination of transverse seetions of wood and the accumulation of a large data base. The automatie method is more rapid than the semi-automatic one using a digitiser, the measurements are more accurate and the method is less labour intensive. The data obtained permit the interpretation of variation in vessel size and distribution throughout the tree and relate this to the water carrying capacity .of the xylem. In Quercus robur, PCA and vessel diameter tend to increase [rom immature aerial, to mature aerial, to root xylem, whereas in Fagus sylvatica although vessel diameter tends to show the same trend, PCA does not. The conclusions reached for Quercus ilex and Q. × turneri were less definite.