A study of the cambial zone and conductive phloem of common beech (Fagus sylvatica L.) using an image analysis method

Abstract

Abstract. Quantification is a major problem when using histology to study the influence of ecological factors on tree structure. This paper presents a method to prepare and to analyse transverse sections of cambial zone and of conductive phloem in bark samples. The following paper (II) presents the automated measurement procedure. Part I here describes and discusses the preparation method, and the influence of tree age on the observed structure. Highly contrasted images of samples extracted at breast height during dormancy were analysed with an automatic image analyser. Between three young (38 years) and three old (147 years) trees, age-related differences were identified by size and shape parameters, at both cell and tissue levels. In the cambial zone, older trees had larger and more rectangular fusiform initials. In the phloem, sieve tubes were also larger, but their shape did not change and the area for sap conduction was similar in both categories. Nevertheless, alterations were limited, and demanded statistical analysis to be identified and ascertained. The physiological implications of the structural changes are discussed.

A study of the cambial zone and conductive phloem of common beech (Fagus sylvatica L.) using an image analysis method

“…Cell p a r a m e t e r s used for cambium and phloem analysis are identical. Variable definitions are given in Table 1, and their biological significance is discussed in Vollenweider et al (1994).…”

“…1). In each tissue, three areas, containing about five stacks of cells, are chosen on the northern and southern side of each tree (Vollenweider et al 1994). Each area is separated from the others anticlinally by medullar rays and periclinally by the adjacent tissues.…”

“…The specimens were photographed on Kodak Technical Pan 2415 film, as described by Vollenweider et al (1994). The 24x36 mm negatives were put in a holder and placed on a light box.…”

“…The aim is to study the influence of age on the structure of these tissues. Part I of this study (Vollenweider et al 1994) dealt with sample extraction and preparation, and discussed the biological meaning of the results. Image analysis procedures are described and discussed below.…”

“…Image analysis provides the means to overcome quantification problems in plant science. Part I of this study (Vollenweider et al 1994) presented a method of preparing transverse views of the cambial zone and conductive phloem in bark samples. Part II of the study presents computerized analysis of the images thus obtained.…”