Pinus uncinata forests of the western outer Alps, the Jura and Pyrenean north facing slopes (ubacs), developed on siliceous or decalcified soils of the subalpine level with a predominately ericaceous undergrowh comprising Rhododendron ferrugineum (dominant), Vaccinium myrtillus, Vaccinium uliginosum, Calluna vulgaris, Homogyne alpina, Deschampsia flexuosa, Lycopodium annotinum.