Grzyby zasiedlające bagno zwyczajne (Ledum palustre L.) w Wigierskim Parku Narodowym

Peat bogs serve as crucial biodiversity centers and environmental archives, yet they are highly sensitive to climate change. Fungi are excellent biological indicators used to diagnose the state of these ecosystems. The aim of this study was to investigate the fungal communities inhabiting dying common marsh plants (Ledum palustre L.) in the peat bogs of Wigry National Park. Field observations conducted at Suche Bagno, Słupie, and Czarna Hańcza revealed significant disease symptoms, including leaf spots (found on 100% of plants at Suche Bagno) and tip dieback in approximately 80% of older shrubs. Fungal isolates were obtained from diseased tissue and identified using both morphological and molecular methods, specifically through the analysis of ITS rDNA regions. A total of nine fungal taxa were isolated. The most frequent species were Epicoccum nigrum (35.1%) and Fusarium sporotrichioides (16.2%). The presence of Fusarium species in the vascular bundles is suggested as a direct cause of the wilting and decline of L. palustre. Other identified taxa included Phacidium lacerum, Penicillium commune, and Alternaria alternata. Notably, the study did not detect Chrysomyxa ledi, previously associated with this host. The results indicate that the poor health of the common marsh, particularly at the Suche Bagno site, acts as an indicator of deteriorating environmental conditions. Without improvement in water retention, further population decline and natural succession toward forest habitats are expected. Monitoring plant health in such protected areas allows for the early detection of ecological shifts within these sensitive habitats.