Baumann, M., Dittrich, S. & Oheimb, G. v. 2019. Effects of periodic liming on the bryophyte layer in Norway spruce (Picea abies) stands in the Erzgebirge (Ore Mountains). – Herzogia 32: 269–287.Severe changes in forest soil conditions, tree health and growth as well as plant species composition have been observed as a consequence of atmospheric acid deposition. The most important measure to counteract soil acidification is forest liming. The long-term effects of repeated liming on the bryophyte layer of forests, however, have rarely been analysed. We used a stratified design to sample the bryophyte layer of spruce stands located in the Erzgebirge (Ore Mountains, eastern Germany). Study sites were unlimed or limed at different intensities between one and five times since 1988. We found a significant effect of liming intensity on the composition and diversity of the bryophyte layer. The liming gradient is reflected by numerous indicator species, by indicator values for pH and nitrogen, and the by alpha and beta diversity of the species present. Liming strongly reduces the cover of many acidophytes typical for the habitat. By contrast, indicator species of disturbance and some rare, nutrient-demanding species appear to benefit from liming. These effects increase with liming intensity. Our results suggest that larger liming exclusion zones should be created to protect the typical bryophyte species composition.