Siedliskowe uwarunkowania występowania wątrobowca Frullania dilatata w Wigierskim Parku Narodowym (północno-wschodnia Polska)

The aim of the article was to verify the hypothesis that humidity, temperature and light con- ditions play a fundamental role in the distribution of Frullania dilatata within the forest complexes in the Wigry National Park. 41 monitoring localities were selected in places of epiphytic liverworts occurrence (22 sites with F. dilatata, 19 – without these plant). Humidity and temperature were recorded hourly during one year. Light conditions on the tested sites were determined on the basis of hemispherical photos. Additional parameters were calculated based on the digital terrain model in the SagaGis program. The results indicate that the hypothesis is false.