Pinus pinaster ssp. atlantica forests with a subcanopy of Quercus suber, Arbutus unedo and sometimes Quercus robur and an undergrowth of Erica cinerea, Pteridium aquilinum, Frangula alnus, Rubia peregrina and, in the more open stands, Cistus salvifolius, Cytisus scoparius, Erica scoparia, Calluna vulgaris or, in more closed ones, Hedera helix, Ruscus aculeatus, Ilex aquifolium, developed on acidocline inner dunes of the warmer, more humid coasts of the Marensin, between the Eyre and the Adour river mouths.