The Rare Polypore Antrodiella citrinella and Its Special Phenology in the Black Forest National Park (Germany)

In the old growth spruce-fir forest “Wilder See”, a long-term protected zone of the Black Forest National Park (Baden-Wuerttemberg, Germany), the phenology of two associated polypore fungus species on Picea abies logs, Fomitopsis pinicola and the rare red-data list species Antrodiella citrinella were investigated. We combined detailed field studies and temperature-related in-vitro growth studies. Whereas perennial fruitbodies of F. pinicola developed from late spring to autumn, the annual A. citrinella fruitbodies were formed mainly in late autumn (October, November) and again in spring (April and May). Growth studies on agar media confirm that A. citrinella grows faster at lower temperatures (5-10 °C), whereas F. pinicola is clearly superior in growth rate between 15 °C and 25 °C. This indicates that A. citrinella is a generally rare, but locally common species that may have been overlooked because of its special phenology in colder periods. The “Wilder See” area in the National Park seems to be an important refuge for the species. Its existence seems to depend on high humidity, high amount of woody debris (P. abies) and the occurrence of F. pinicola. In the presence of living A. citrinella fruitbodies, fruitbodies of F. pinicola were found to be always dead. This supports earlier speculations that the relation may be parasitic.