Acidophilous forests of the Baltic-North Sea plain, composed of Quercus robur, Betula pendula and Betula pubescens, often mixed with Sorbus aucuparia and Populus tremula, on very oligotrophic, often sandy and podsolised or hydromorphic soils; the shrub layer, poorly developed, includes Frangula alnus; the herb layer, formed by the group of Deschampsia flexuosa, always includes Molinia caerulea and is often invaded by bracken. Forests of this type often prevail in the northern European plain, from Jutland to Flanders; they occupy more limited edaphic enclaves in the Ardennes and the middle and upper Rhenish ranges, in northwestern France, Normandy, Brittany, the Paris basin, the Morvan and Great Britain. East of the Elbe, in the Baltic lowlands, they are represented, east to Mecklenburg, by stands transitional, to a greater or lesser extent, to those of unit G4.71.