Forests of Quercus robur or Q. petraea on acid soils with an herb layer mostly constituted by the ecological groups of Deschampsia flexuosa, Vaccinium myrtillus, Pteridium aquilinum, Lonicera periclymenum, Holcus mollis, and of Maianthemum bifolium, Convallaria majalis, Hieracium sabaudum, Hypericum pulchrum, Luzula pilosa, and the mosses Polytrichum formosum and Leucobryum glaucum.