| Summary: | Certain aspects of the biology and ecology of selected wood-decaying, cord-forming fungi were investigated. These included identification of the major species involved and quantitative assessments of their importance in wood decay, particularly of virgin substrata and suppressed oak trees. Cord-forming fungi rapidly arid frequently colonized such substrata and came to occupy large volumes within them (particularly Phanerochaete velutina), first invading peripheral parts of wood in ground contact and then spreading to more central tissues, where they could persist for long periods. The form and extent of individual cord systems and their mode of development in soil were investigated. All species studied developed in a similar manner in non-sterile soil. i.e. growth occurred via fronts of fine cords ('fans') at the advancing edges of systems, which were superseded by more substantial cords behind them, linking the advancing fronts to food-bases. In sterile conditions, however, none of the species investigated (except Phallus impudicus to a limited extent) formed cords. In the field individual cord systems were commonly found to be over 20m in length. Studies involving intraspecific pairings between cord systems of Phanerochaete velutina in soil indicated that a mechanism exists for distinguishing 'like' from 'unlike' mycelial types. An analysis of the spatial di'stribution of a population of Tricholomopsis platyphylla revealed that this species has tetrapolar incompatibility and that a limited number of often extensive mycelial types were present at a woodland site of area 20.8ha. Certain cord-forming fungi physically overgrew Armillaria bulbosa and A. ostoyae in culture and may have been able to at least restrict the spread of Armil1aria species in the bases of suppressed oak trees Cords of selected species were often highly differentiated internally and the various types of constituent hyphae were considered in terms of function namely protection, strengthening and translocation.
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