T151 Alnus swamp forests not on acid peat

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Description

Alder-dominated swampy forests typically colonising the margins and silted-up areas of oxbow lakes or backwters (be them natural like those created by sea-borne dunes or pebble-deposits blocking the river mouth, or artificial as around the upstream end of reservoirs). Due to the leaching of reasonably large catchment areas, the system lacks the intrinsic oligotrophy required by treeless vegetation like bogs or fens; but waterlogging, preventing soil aeration and leading to denitrification, ensures the predominance of aerenchymatous and nitrogen-fixing woody plants like alder itself.

Protection

This habitat is not protected under the EU Habitat Directive.

Floristic Composition

Frequent species

Alnus glutinosa aggr. 100%, Salix atrocinerea 93%, Athyrium filix-femina 56%, Hedera helix aggr. 50%, Osmunda regalis 40%, Lonicera periclymenum 37%, Solanum dulcamara 36%, Viola riviniana aggr. 31%, Rubus ulmifolius 31%, Lycopus europaeus 30%, Angelica sylvestris 28%, Carex laevigata 28%, Blechnum spicant 27%, Lythrum salicaria 26%, Carex pendula 24%, Galium palustre 24%, Scrophularia auriculata 24%, Filipendula ulmaria 23%, Sambucus nigra 23%, Iris pseudacorus 22%, Mentha aquatica 22%, Brachypodium sylvaticum 22%, Carex paniculata 22%, Cirsium palustre 22%, Frangula alnus 21%, Oenanthe crocata 21%, Laurus nobilis 21%, Fraxinus angustifolia 20%, Calystegia sepium 20%, Ranunculus repens 20%, Quercus robur 20%, Dioscorea communis 19%, Juncus effusus 19%, Teucrium scorodonia 19%, Carex remota 18%, Omphalodes nitida 18%, Crataegus monogyna 17%, Polystichum setiferum 16%, Lysimachia nemorum 16%, Eupatorium cannabinum 16%, Fraxinus excelsior 16%, Geranium robertianum 16%, Hypericum androsaemum 16%, Peucedanum lancifolium 16%, Dryopteris dilatata 15%, Cardamine pratensis 15%, Euphorbia amygdaloides 14%, Urtica dioica 14%, Scutellaria minor 14%, Humulus lupulus 14%, Dryopteris affinis 14%, Viola palustris 13%, Corylus avellana 13%, Dryopteris filix-mas 13%, Arum italicum 12%, Populus nigra 12%, Valeriana dioica 11%, Chaerophyllum hirsutum 11%, Holcus lanatus 11%, Cornus sanguinea 11%, Jacobaea aquatica 11%, Ficaria verna 11%, Equisetum palustre 11%, Cardamine raphanifolia 10%, Bryonia dioica 10%, Rosa canina aggr. 10%, Circaea lutetiana 10%, Helosciadium nodiflorum 9%, Betula celtiberica 9%, Carex reuteriana 9%, Heracleum sphondylium 9%, Primula acaulis 9%, Cardamine flexuosa 9%, Ajuga reptans 9%, Poa trivialis 9%, Potentilla erecta 8%, Rubus caesius 8%, Ranunculus flammula 8%, Saxifraga hirsuta 8%, Ligustrum vulgare 8%, Luzula sylvatica 8%, Euphorbia dulcis 8%, Myosotis martini 8%, Pteridium aquilinum 8%, Silene dioica 7%, Agrostis capillaris 7%, Salix salviifolia 7%, Prunella vulgaris 7%, Hypericum tetrapterum 7%, Dryopteris borreri 7%, Dactylis glomerata 7%, Salix purpurea 6%, Equisetum arvense 6%, Salix alba 6%, Molinia caerulea 6%, Caltha palustris 6%, Aquilegia vulgaris aggr. 6%, Allium ursinum 6%, Agrostis stolonifera 6%, Senecio bayonnensis 6%, Silene flos-cuculi 6%, Valeriana pyrenaica 6%, Salix euxina 6%, Digitalis purpurea 6%, Picris hieracioides 6%, Lamium maculatum 6%, Symphytum tuberosum 6%, Rumex acetosa 6%, Ruscus aculeatus 6%, Narcissus cyclamineus 5%, Deschampsia cespitosa aggr. 5%, Lysimachia vulgaris 5%, Geum urbanum 5%, Stellaria holostea 5%, Stellaria alsine 5%, Sparganium neglectum 5%, Brachypodium pinnatum 5%, Crepis lampsanoides 5%, Castanea sativa 5%, Wahlenbergia hederacea 5%

Phytosociology

  • Carici lusitanicae-Alnetum glutinosae

Relations with other habitat types

Instead of the diverse array of nemoral herbs inhabiting the riverine T121, the undergrowth of these is dominated by a smaller number of mostly specialist plants, including tall helophytes and large tussock-formers like Carex paniculata.

Regional distribution

Known occurrences and potential area of occupancy of the habitat type in the study region.

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Citation: IBEROATLANTICA – Flora and Habitats of the Cantabrian Mixed Forests ecoregion.
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