Suillus flavidus, a Peatland-Associated Mycorrhizal Fungus in Poland: Ecology, Distribution, Conservation Threats, and Sustainability Considerations

Suillus flavidus is an ectomycorrhizal fungus associated with moist, nutrient-poor habitats, particularly peat bogs and transitional mires, where it forms symbiotic relationships with two-needle pines, especially Pinus sylvestris. This study presents an updated assessment of its distribution in Poland, identifies key ecological factors influencing its occurrence—such as habitat type and phenology—and evaluates its conservation status in the context of sustainability goals. Analysis of available data shows that over two-thirds of the known sites in Poland are located in peatland ecosystems, with more than half occurring within protected areas. Although S. flavidus is distinctly hygrophilous, it appears to prefer moderately wet habitats, particularly swamp forests. Despite an increase in recorded localities over the past five decades, S. flavidus remains an endangered species due to the ongoing degradation of peatland habitats, which are increasingly threatened by land-use change, drainage, and climate-related shifts in hydrology. The species’ long-term survival depends on sustainable landscape management, the preservation of suitable host tree populations, and the inclusion of fungi in conservation and restoration strategies. Thus, S. flavidus should be considered both an indicator species and a relevant element in meeting sustainability goals.