So far, few detailed bryofloristic studies have been carried out in protected areas in Finland (Tuomikoski, 1939,1941; Koponen, 1967; Kujala et al., 1979; Kartunen, 1986; Haapasaari & Fagersten, 1987; Laaka, 1993). In 1996, the bryophyte biodiversity of old spruce forests was studied in the North Karelia Boispheric Reserve, located in the eastern corner of the biogeographic province of Karelia borealis (Kb).

Altogether, 80 bryophytes (60 mosses and 20 liverworts) were revealed at 18 sites studied in old spruce forests. Twenty-eight mosses and five liverworts occur in the suprasoil cover of old spruce forests. Sphagnum quinquefarium, which is indicate of old forests, is common there. Six mosses and eight liverworts were revealed on rotten wood and Calypogeia suecica is an indicator species there. Nine mosses and one liverwort were revealed on the exposed roots of fallen trees on the disturbed soil cover and indicator species Schistostega pennata grows there. Ten mosses and two liverworts were most abundant at the base of the trunks and on the jutting roots of Populus tremula. Six mosses and three liverworts are covered the base of the trunks and the juttihg roots of Salix caprea. The base of the trunks of Picea abies is usually covered by 3 mosses and 1 liverwort, and the base of the trunks of Betula pendula is covered by 4 mosses and 1 liverwort. Nine mosses and three liverworts were revealed on big boulders and rocks. Aspen epyphytes are represented by 4 mosses and 2 liverworts.

Some indicator species of old spruce forests, such as Sphagnum quinquefarium and Schistostega pennata, are fairly common at the sites studied. The liverwort Calypogeia suecica, proposed for the Red Book of East Fennoscandia, is very scarce.