Lobaria pulmonaria has been subject to strict and zonal protection in Poland for almost 20 years, assuming the function of an umbrella species for the protection of natural biodiversity. Knowledge about this function, however, is limited, mainly due to a lack of relevant research. The current protection zone with a radius (R) of up to 50 m was significantly reduced in 2014 compared to the previous one from 2004 (R=100 m), mainly due to the needs of forest management. This legislative change became why it was worth making a scientific balance of potential gains and losses. Corticolous lichens growing at circular sites with a radius of 150 m around lungwort host-trees, divided into three zones R=50 m, R=51-100 m, R=101-150 m, were selected as the biological group for verification. Beech (Fagus sylvatica) and sycamore (Acer pseudoplatanus) trees with DBH ≥40 cm, randomly located along the target azimuths of 0°, 120°, and 240°, were selected for the study at 15 sites located in the Polish Carpathians (Gorce and Bieszczady Mts). The research hypothesis was that the size of the L. pulmonaria protection zone in the Polish Carpathians is important for the conservation of a greater diversity of corticolous lichens. Based on the list of species, we assessed the statistical significance of differences in diversity indices between the zones and between the Gorce and Bieszczady sites, which was justified by the result of the DCA analysis. Both the total number of species and old-growth forest, legally protected and endangered species in Poland (categories EN, CR) were analyzed. Generally, the current protection zone with a radius of 50 m protects approx. 70% of all epiphytic lichen diversity and the same share of other investigated groups, while increasing the protection zone to R=100 m saves almost 90% of species representing these groups of lichens. Keywords: Lobaria pulmonaria; nature protection; umbrella species; zonal conservation; lichen diversity; diversity index.