Pteridium aquilinum stand

In the humid regions of Europe bracken (Pteridium aquilinum) may form species-poor 1 to 2 meter high stands on deeper, acidic to neutral, well drained, well aerated and poor to relatively fertile soils. The associated species assemblage may vary depending on the context in which the bracken stands develop, particularly with the acidity and fertility of the soil and the density of the cover of fronds. On less acid soils, the herbaceous associates may be those of mesotrophic grasslands and it may be mixed with bramble species (Rubus), scattered scrubs (Crataegus, Prunus) or trees (Fraxinus, Quercus) , forming transitions towards Red List scrubs F3.1b and F3.1e. In other cases it may contain components of heath or acidic grassland, for example Vaccinium myrtillus, Galium saxatile, Potentilla erecta or Anthoxanthum odoratum.

Bracken is probably naturally a forest fern held in check by the shade of a canopy of trees and shrubs but it is found as this habitat in forest gaps and clearings, along forest margins, in heathlands, in drained bog areas, on burnt sites, being a component of agricultural or heathland areas and rarely occurring also in coastal dunes. Bracken can colonise open ground in such habitats by spore dispersal, but this is a relatively rare phenomenon. More usually the species expands from existing populations by vegetative rhizome spread, slowly forming larger clonal stands. Once established the species creates a hostile environment for other plants, by producing dense summer shade and large amounts of slowly-rotting litter. The result is a relatively species-poor habitat, not considered of high value from a nature conservation point-of-view. In many cases it is rather considered as a threat to other habitats, like grasslands and heathlands, developing as a result of abandonment of traditional management in which it was often cut and used as bedding for farm animals and also held in check by trampling of cattle.

The main distribution covers the Atlantic and Subatlantic lowlands and mountains of Europe, being most widespread in Ireland, the British Isles and Brittany (France). Further eastwards Pteridium aquilinum is mainly restricted to the humid microclimate of forests. More species-rich tall herb stands dominated by this species are widespread but not very common, and mostly confined to temperate mountains. In boreal and warm Mediterranean regions the conditions are less optimal for the habitat to develop.

Indicators of good quality:

• Being part of a landscape mosaic with heathlands, forests and grasslands
• No co-dominance of trees and shrubs

Synthesis of Red List assessment

Confidence in the assessment

Pressures and threats