Variabilites geographique, sylvicole et individuelle de la teneur en extractibles de chenes sessiles francais (Quercus petraea Liebl.): Polyphenols, octalactones et phenols volatils

Abstract

The experimental material consists of 82 sessile oaks sampled from 48 plots characterized by two types of silvicultural management: high forest and coppice with standard. These plots are located in five french regions: Allier, Loir-et-Cher, Orne-Sarthe, Lorraine and Alsace (ONF-INRA convention 1992-1996 'Sylviculture et Qualite du bois de chine (chene rouvre)'). For each tree, two extractions were made from the first 15 rings of the heart-wood of two opposite radii which were situated at 1.30 m from the bottom of the tree. Optic density at 280 nm (which is well correlated with tannin content for this type of extraction) and the concentrations of methyl-octalactones and volatile phenols (among which eugenol) were measured. Different effects were tested by variance analysis: 'tree within plot', 'plot within type of management x region', 'type of management x region', 'region' and 'type of management'. For the majority of compounds, tree effect is very significant. Significances for plot effect and for interaction of region with type of management are generally poor. The effect of 'type of management' is very significant for tannins, trees of high forest having lower concentrations than trees of coppice with standard. Regions only differ by eugenol content. For methyl-octalactones, there is a little more of the trans racemic form for high forest and no type of management or region effect for the cis racemic form.