Variability of wood extractives among Quercus robur and Quercus petraea trees from mixed stands and their relation to wood anatomy and leaf morphology

Heartwood ellagitannins and volatile extractives were studied by high-pressure liquid chromatography and gas chromatography--mass spectrometry after extraction of wood samples taken from 54 mature trees of pedunculate oak (Quercus robur L.) and sessile oak (Quercus petraea (Matt.) Liebl.) from 14 mixed stands located in the forest of Citeaux (Bourgogne). These same trees had been previously subject to detailed study of leaf morphology and wood anatomy. Over 50 compounds, of diverse chemical types, were identified in the wood extracts and over 30 of these compounds were quantified. No species-specific extractives were identified, but the amounts of ellagitannins and a small number of volatile compounds, including cis- and trans-beta-methyl-gamma-octalactone isomers, were found to vary significantly between the two species. Multivariate analyses of these extractives allowed the classification of samples according to species, although less distinctly than similar analyses using leaf morphological characteristics. No strong intraspecific correlations between chemical constituents and anatomical or morphological characteristics were found that were common for both species. Nonetheless, sessile oaks displaying atypical wood anatomy were also less morphologically and chemically representative of their species. Trees possessing the lowest levels of cis- and trans-beta-methyl-gamma-octalactone are found to be those with a morphology the least distinct of either species.