ECTOMYCORRHIZATION AND HEALTH OF BEECHES AND OAKS IN THE FOREST OF SOIGNES

In order to compare the intensity and the vitality of mycorrhizal infe ction on healthy and declining trees, we have examined the mycotrophy of 14 Quercus robur and 12 Fagus sylvatica (healthy or declining) in t he forest of Soignes. On the basis of their morphological characterist ics, 31 mycorrhizal types were distinguished on the oaks and 47 mycorr hizal types on the beeches. In the quantitative side of the study, it was discovered that the percentage of living roots and the intensity o f mycorrhization were relatively lower on declining trees than on heal thy ones. Moreover, for the oaks, some mycorrhizal types with a wooly fungal mantle and many emanating hyphae seem to be more frequent on th e roots of healthy trees.