DECOMPOSITION OF SUPPRESSED OAK TREES IN EVEN‐AGED PLANTATIONS.

SUMMARY Armillaria (= Armillariella ) bulbosa , and several cord‐forming basidiomycetes were found to be the principal colonizers of suppressed oak tree roots on one site studied, whilst A. ostoyae and cord‐forming fungi prevailed on a second site. Interestingly A. mellea was not isolated at all. The rhizornorphic and cord‐forming fungi appeared to colonize peripherally at first but ultimately occupied large volumes of wood. Some cord‐forming fungi were able to replace others in culture whilst in other pairings deadlock was reached. There is some evidence that cord‐forming fungi can replace A. bulbosa and A. ostoyae but cultural experiments were difficult to interpret. A. bulbosa acts mostly saprophytically and probably occupies a similar ecological niche to cord‐forming fungi, e.g. Phanerochaete velutina, Hypholoma fasciculate and Phallus impudicus , which are also saprophytes. Whether A. ostoyae acts pathogenically or purely saprophytically is uncertain. Tricholomopsis platyphylla , another cord‐forming fungus, was prevalent on a third site studied in less detail and is suggested as being a later colonizer than the other cord‐forming and rhizomorphic fungi. Individual mycelia of A. bulbosa, A. ostoyae and P. velutina are shown to colonize roots in large areas of the sites studied and it is suggested that these fungi may be of significance in nutrient translocation in deciduous woodland ecosystems.