This vegetation type occurs in forest springs with calcium carbonate precipitation. Species richness of vascular plants is usually very low, and it decreases as the amount of calcium carbonate precipitation increases. Bryophytes mostly predominate over herbs. A well-developed moss layer can significantly increase calcium carbonate precipitation due to high carbon dioxide uptake from water for photosynthesis. In the Czech Republic, this vegetation has been recorded at low and middle altitudes on calcium-rich bedrock.