Oligotrophic swamp alder woods

Oligotrophic or meso-oligotrophic, acidocline [Alnus glutinosa] woods of fens and poorly drained banks of brooks or small rivers of western Europe, mostly characteristic of siliceous regions and Atlantic climates, south to Galicia. [Betula pubescens] and [Frangula alnus] often accompany the alders. The ground layer is usually rich in [Sphagnum] spp. and includes [Carex laevigata], [Equisetum sylvaticum] and many ferns, including [Oreopteris limbosperma], [Blechnum spicant], [Athyrium filix-femina], [Dryopteris cristata] and [Dryopteris carthusiana].