Variation of heartwood phenolics and oak lactones between the species and phenological types of Quercus petraea and Q-robur

Pressler cores were taken of Quercus petraea and Q. robur trees from young German provenance stands and mature mixed plantations in England. The concentration of total phenolics extracted from the outer heartwood was measured and significant differences found between the two species. Concentrations of oak lactones, measured from provenance samples, also varied significantly between the species. However, the difference in total phenolics between species was much lower among the trees from the mixed plantations than from the provenance trials. Q. petraea was characterized by lower levels of total phenolics but greater concentrations of oak lactones than Q. robur. A comparison between late and early flushing Q. petraea trees found no significant difference in total phenolics between these phenological types.