Abstract
Sclerotia of Cenococcum geophilum tend to be particularly abundant near its mycorrhiza as spherical grains of about 0.05–4 mm in diameter. In this study, we examined sclerotium propagules to investigate the persistent structure of sclerotia in forest soils. Sclerotia were collected from the surface A horizon of Luvisols in the Harz Mountains (HRZ) of central Germany, Podsols on Mount Ontake in central Japan, and Andosols on the Lake Tazawa plateau in northeastern Japan. For comparison, we examined sclerotia from the surface and buried humic layer beneath tephra of an 11th-century eruption of Mount Myoko in central Japan. The sclerotia from the different study areas basically resembled each other, although HRZ sclerotia exhibited the greatest physical strength. On the basis of sclerotia bulk density, Fourier transform infrared spectrum, and accelerator mass spectrometry 14C ages, we conclude that young and fresh cell material of HRZ sclerotia support their physical strength. The physical strength of the sclerotia could be initially regulated by internal structure and cell wall properties (e.g., thickness, chemical composition, and confluency of cells), which might be differentiated by genetic variation. The length of time spent in soil and decomposition intensity, which can be regulated by the soil environment, may be secondary factors regulating the physicochemical characteristics of sclerotia
