The work on studying of a condition of population of the protected lichen Bryoria nadvornikiana performed in the first time in plant communities of Petrozavodsk with help two methods (routing method and a method of the trial areas). It was registered 555 thalli growing on 195 trees of spruce as a result of researches. Length, width of thalli and growth of height over the ground noted for each thallus. It was established that in forest communities of the city Bryoria most often meets in spruce bilberry wet (46%). The maximum number of thallus (43%) is revealed on young trees age of 40-54 years, 4-6 m, with a diameter of a trunk 6-10 cm. The most favorable conditions for this species are formed in the lower part of the crown. The appearance of species in aspen forests is caused by existence of young spruce emerging from the undergrowth with lower dry branches suitable for colonization. Number of thallus B. nadvornikiana decreases with increase in anthropogenous loading. State populations of Bryoria in plant communities of the city can be described as normal.