CARBON TRANSLOCATION IN MYCELIAL CORD SYSTEMS OF PHANEROCHAETE-VELUTINA (DC, PERS) PARMASTO

Movement of radiotracer was monitored in mycelial cord systems develop ed from wood block inocula, precolonized by Phanerochaete velutina (DC .: Pers.) Parmasto grown on unsterile soil. In short-term studies, rep roducible but low-level loading of radiotracer was observed which was independent of the extent of cord systems. Carbon translocation veloci ties ranged from 132 to 336 cm h-1, whilst fluxes were estimated to ra nge from 35 to 66 nmol cm-2 h-1 (as glucose). When cord systems were s upplied with a range of potential carbon resources as baits considerab le movement of carbon was detected over 9 wk. More than 80% of exogeno usly supplied carbon was retained in resource units rather than being allocated to extra-resource mycelium. The direction and extent of carb on movement, and partitioning of decay between inocula and baits withi n cord systems, was dependent upon the type and size of bait and wheth er or not combinations of baits included wood pre-colonized by other s aprotrophic fungi. There was evidence for coordinated use of resources within cord systems and that carbon movement was not a function of my celial growth. Respiratory carbon losses were greatest when baits incl uded sterile leaf litter packs and least when sterile wood baits were supplied. The results are discussed in terms of nutrient conservation and cycling in cord systems.