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Old Growth Forest Indicators

Some lichens are poor dispersers and are slow to populate new habitats. Such species tend to stay and flourish in a single habitat such as a forest. These lichens are called old-growth forest indicators. When they are found, their presence can be interpreted as indicating that their current habitat was once part of an ancient forest. Ireland has no forests today, and just a few unpolluted woodlands. Finding an old-growth forest lichen implies that this area may have been part of an ancient forest.

The following species are selected old-growth forest indicators. For a complete list see the West Of Ireland Index of Ecological Continuity published by the British Lichen Society.

Arthonia astroidesters

Arthonia ilicina

Arthothelium lirellans

Bacidia biatorina

Collema fasciculare

Collema nigrescens

Dimerella lutea

Lobaria pulmonaria

Lobaria scrobicilata

Nephroma parile

Ochrolechia inversa

Pertusaria velata

Porina atlantica

Porina hibernica

Sticta canariensis