Grazing alters network architecture during interspecific mycelial interactions

The changes that occur in mycelial architecture of Phanerochaete velutina interacting with Hypholoma fasciculare mycelium in soil microcosms in the presence and absence of the collembola Folsomia candida are investigated employing tools developed in graph theory and statistical mechanics. There was substantially greater overgrowth of H. fasciculare by P. velutina mycelium when grazed than when un-grazed. There was a marked disappearance of hyphal links in all un-grazed systems between 8 d and 34 d, predominantly in areas distant from the interaction, but this was much less evident in grazed systems. Further, new tangential cross-links connecting radial cords distant from the inoculum formed in grazed systems. The thickness of cords increased with time, and more so in grazed systems. There was no significant difference in transport efficiency between the grazed and un-grazed systems. The ability of the mycelial network to modify dynamically link strengths is crucial to achieving a balance between transport capacity/robustness to damage and overall cost of production.