Lichens

Dartmoor’s granite tors and granite boulders (known as clitter fields) are one of Devon’s most iconic landscapes. The granite on Dartmoor was intruded between 280 and 300 million years ago and has subsequently been shaped by physical and chemical weathering.. The wealth of microhabitats amongst the tors, clitter fields and drystone walls on Dartmoor have allowed the development of extensive saxicolous lichen communities on the rocks.. The metamorphic rocks around the edge of Dartmoor, including the slates and sandstones in the Teign Gorge, increase habitat diversity for lichens. Some of the species found in these habitats also occur on well-lit, south-facing slate outcrops in coastal areas.    

Key pressures include recreational disturbance, changes in vegetation, the potential impacts of ammonia, and lack of survey. Vince Giavarini surveyed 29 tors on Dartmoor during the summers of 1987 and 1988. This survey has not been repeated. See Pressures above.

Two species have Threatened or Near ThreatenedA species likely to qualify for threatened category in the future, perhaps very quickly. More status: Lepra melanochlora and Umbilicaria hirsuta. Other Devon Species of Conservation Concern include Agonimiaopuntiella, which in south-west England has only been recorded on Dartmoor and at Bodmin Moor; Buellialeptoclinoides, which in Britain is mostly recorded in the South Hams; and Clauzadeanamacula, Fuscideagothoburgensis and Rhizocarponsubgeminatum, which are rarely recorded in England. 

See the detailed overview for this group in Find out more below.

Aquatic lichens live on rocks in rivers and streams. Different species live on different types of rock.

Good freshwater lichen habitats are uncommon. Devon’s upland acidic watercourses, flowing from Dartmoor and Exmoor, provide suitable habitat with exposed riverbed rocks and large rounded boulders. Nutrient-rich lowland rivers with heavy silting have far fewer lichen species.

Different species of aquatic lichens live in different zones of the river depending on the adaptions these have to submersion in water. Some, such as the river jelly lichen, can live largely underwater while others, such as Porina interjungens, prefer damp rocks on the shaded, vertical faces of gorges.

The West Dart and the upper Teign Rivers both meet the criteria to be designated as SSSIs due to their lichen interest.  However, no SSSIs in Devon include aquatic lichens as a designated interest feature. 

Key issues include water quality, water quantity, recreational impacts, management of riverbanks, and invasive species. See Key pressures and opportunities above. Given the lack of baseline data and surveys, it is not known whether individual species are stable, increasing, or declining. 

There are six Devon Species of Conservation Concern in this group including Porocyphus kenmorensi which lives largely underwater. The river jelly lichen is discussed below as a flagship for this group.

See the detailed overview for this group in Find out more below.

Lichens can be divided into three different rainforest communities, although these overlap: upland rainforest, lowland rainforest, and southern oceanic woodland. The lowland rainforest community only occurs from north Wales to western Scotland and so is not discussed here.  Deadwood specialist lichens also occur in all rainforest communities.

Devon is a stronghold for woodland lichens, especially when compared to the Midlands and eastern England. This is in part due to more limited agricultural improvement on Dartmoor and Exmoor but also to lower levels of acidifying sulphur dioxide pollution during the nineteenth and twentieth centuries.

Management 

Lichens in Devon’s rainforest communities need successive generations of well-lit trees. These therefore prefer open woodlands with well-spaced trees. Traditionally these woodlands are thought to have been managed by a combination of the extraction of wood products and through regular grazing by wild herbivores and livestock such as cattle, sheep, and ponies.. . Pressures include shading by invasive species , lack of natural regeneration, lack of grazing to control the understorey, climate change, and air pollution.  See Key pressures and opportunities above. 

SSSIs 

SSSIs with these lichens as a designated interest feature: Arlington Court, the Barle Valley (both Exmoor or edge of Exmoor), Dendles Wood and Holne Woodlands (Dartmoor), Clovelly Deer Park, Dunsland Park, Hobby to Peppercombe, Marsland to Clovelly Coast, Ugbrooke Park and Whiddon Deer Park. Dartmoor SACSpecial Area of Conservation More includes Black Tor Copse, Dendles Wood and Wistman’s Wood.    

Read more about the three groups below. See the detailed overviews for these groups in Find out more below. 

High rainfall in exposed areas produces nutrient-poor acidic bark, especially on oak, birch and holly trees . Most lichens in this group are in the Parmelion community and have a foliose (leaf-like) structure. These species can form extensive patches, sometimes spreading onto adjacent rocks.

The habitat this lichen community needs is very restricted in England,  only being found in limited areas of Devon, Cornwall, Somerset and Cumbria. In Devon, species in this group are found in Dartmoor’s higher altitude oakwoods at Black-a-Tor Copse and Wistman’s Wood, and in ancient oak woodlands along the river valleys or Dartmoor and Exmoor. 

The majority of the species on the SSSI Upland Rainforest index are found in Devon (at least 33). Four of these are currently Threatened or Near Threatened: Allographa pauciloculata, Arthonia invadens, Hypotrachyna horrescens,  and *Bryoria smithii (a horsehair lichen).    

Southern oceanic woodland is one of the best developed lichen habitats in Britain and with many species with international conservation importance. The richest areas are found in humid, sheltered sites in southern England, from Cornwall to the New Forest, and up into North Wales. 

The lichens that live here (many belonging to the Lobarion community) grow on tree bark that is less acidic than that found on trees in the upland rainforest community. Important host trees are oak, hazel and holly.

Like upland rainforest lichens, this community is found in ancient oak woodlands in the river valleys of Dartmoor and Exmoor (but not the higher altitude woodlands). It also occurs in coastal woodlands in the North Devon Protected Landscape and in parklands with veteran trees such as Ugbrooke Park near Chudleigh and Woodend Deer Park in East Devon.  

Some lichens in this community including Leptogium cyanescens and species of Nephroma, Peltigera and Sticta can be also found on  rocks and on sheltered dry stone walls on Dartmoor

Most of the lichen species on the SSSI southern oceanic woodland index are found in Devon. Of these, 32 of the species have Threatened or Near Threatened status.

Two species in England are confined to Devon. Porina effilata is Critically Endangered and has only been recorded from a small number of oaks near Clovelly Deer Park in north Devon. Nevesia sampaiana  is only found in a small area of Holne Woods on Dartmoor.

A lignicolous lichen community, recorded primarily  on dead wood without bark (decorticate) can occur on both living and dead trees. This community develops on dead wood sheltered from direct rainfall or is in exposed situations where the wood dries out quickly.

There are six Threatened or Near Threatened species in this group including two that are Endangered, Buellia hyperbolica and Lecanora strobilina.    

These lichens are found across Devon on old, well-lit trees in habitats such as parklands, farmland, hedgerows, churchyards, and gardens. Parklands are the best areas as these have the largest number of veteran trees. See Parkland and wood pasture and Veteran trees.

Key issues include shading, loss of veteran trees, lack of protection and management to prolong the life of veteran trees, and lack of planting  of new trees, sometimes for almost a century. See Pressures above.

There are 14 Threatened or Near Threatened species in this group. Seven species are also categorised as Endangered and Devon Species of Conservation Concern.

Other species that are recorded in this habitat include members of the Lobarion lichen community. No species in this group are confined to Devon but the populations of Parmelina carporrhizans, and Cryptolechia carneolutea are nationally significant and the county is also a national stronghold for Wadeana dendrographa  which grows on the bark of veteran trees, generally favouring ash.

See the detailed overview for this group in Find out more below.

Lichens in this habitat  grow largely on willows, which naturally have less acidic bark than that found on alder and birch. Pockets  of mature wet woodland within mires, bogs, culm grasslands and along watercourses are ideal for promoting the growth of lichens by providing  well-lit edge habitat,  shelter, and near constant humidity.  This is especially important for species in the Lobarion community which favour sheltered trees with base-rich bark..

There are three species in this group with Threatened or Near Threatened status:  Hypotrachyna horrescens, Phlyctis agelaea, and Tylophoron hibernicum.  Two species which are recorded in this habitat: Lobarina scrobiculata and Ricasolia amplissima are also likely to be categorised as Threatened in an upcoming review of lichen conservation status. 

Parmelia submontana occurs in Wales and Scotland but in England it has only been recorded in Devon, where it grows on willows in the Devon Wildlife Trust Emsworthy Mire reserve, on the Heathercombe estate, and at the Heatree Activity Centre near Manaton. Currently there is insufficient data to assess whether it is a threatened species.

See the detailed overview for this group in Find out more below.

Metal mines

Metallophytes are a very specialist group of lichens that were once found on natural outcrops of metal-rich rock but are now mainly restricted to disused metal mines and other contaminated sites. In the past there were extensive copper and tin mines around the edge of Dartmoor (see Geology and soils). Many are now archaeological sites and the spoil heaps and other features form complex habitats that support these rare lichens.

Key sites include Wheal Betsy (copper and lead), Devon Friendship (copper), Ramsley (copper), Devon Great Consols (copper and arsenic), Vitifer (tin) and Gawton (copper and arsenic).  Mines in the Tamar Valley are in the West Devon Mining Landscape World Heritage Site.

The assemblageA group of different species that are found together in one place. More in Devon includes three species that are Threatened or Near Threatened: Cladonia rei, Lecanora handelii, and Rhizocarpon furfurosum. None though are confined to Devon.

Clay quarries

A group of specialist  lichens occurs in the exposed, low-fertility clay wastes in Devon’s clay quarries at Lee Moor in south-west Dartmoor, the Bovey Basin near Newton Abbot, and the Petrockstowe basin in north Devon. These species colonise undisturbed ball and china clay spoil, especially around flooded pits, beside tracks, and on the steep damp sides of gullies. High rainfall totals in south-west England ensure that the clay remains damp, particularly during the winter months when these ephemeral lichens are growing.. 

The assemblage in Devon includes two Near Threatened species, Cladonia rei and Scytinium palmatum, and supports a number of other   infrequently recorded lichens.

Limestone quarries

The Near Threatened lichen Pseudoleptogium diffractum has been recorded on inland calcareous cliffs in Devon, near Buckfastleigh and Newton Abbot. 

See the detailed overviews in Find out more below.

This group occurs on a range of coastal habitats from inter-tidal rocks to coastal heathlands. It can be found up to the salt-spray limit which can be over 1 km inland on very exposed coasts. The greatest diversity of species are found on hard rocks in south-west England and Wales.

Distinct zones can easily be seen as the most abundant lichens are different in colour. In the lower intertidalThe area of the shore that is covered by water at high tide and exposed to air at low tide. More zone, lichens form a conspicuous black band on the rocks. The zone above this, which is only submerged at high tide, supports lichens that are typically grey, brown, or yellow. Rocks higher up, which get sea spray but are usually only reached by waves during storms, are characterised by bright orange or white lichens.

Short, sunny coastal grassland is another important lichen habitat. Some of the most threatened coastal species in Devon grow on thin soils on cliff edges.   

There are 16 Threatened or Near Threatened species in this group in Devon. Four of these Threatened species are also UK Priority Species: Alyxoria subelevata, found on cliffs around Ilfracombe and on slate outcrops on the southern bank of the Teign Estuary; Fulgensia fulgens (scrambled egg lichen) which is found on limestone cliffs at Saunton Down in north Devon and at Braunton Burrows (see the Braunton Burrows group below); Heterodermia leucomelos, found at Morte Point and on Lundy; and Teloschistes flavicans, found on cliff tops mainly on the western  of Lundy but also at Morte Point and on the south coast between Bolt Head and Bolt Tail, and at Prawle Point.

No species in this group are confined to Devon although we have a significant proportion of the UK populations of Alyxoria subelevata, scrambled egg lichen (Fulgensia fulgens) and Teloschistes flavicans

See the detailed overview for this group in Find out more below.

Braunton Burrows in north Devon supports a rare  community of terricolous lichens, including several species of national importance.

These lichens thrive in areas of stabilised open, level, low nutrient sward, frequently growing in association with the moss Trichostomum crispulum. The lichens require ground which is kept open by  grazing rabbits and sometimes past compaction from vehicles.. Key areas are Pebble Slack and a disused car park at Broadsands. This habitat is very different to the more mobile sands found along the dune ridges which are dominated by taller grassland communities..

Threats include encroaching scrub, too much disturbance from vehicles, and scraping to rejuvenate the dunes. Cattle grazing can help to reduce vegetation but can damage the lichens. There have been steady declines in terricolous lichens at other sites nationally, particularly in the East Anglian Brecks, where significant decreases in natural grazers have led to an increase in grassland cover by higher plants. Colonies of the scrambled egg lichen (Fulgensia fulgens) at Braunton Burrows were lost at Pine Slack and Bomber Slack between 2013 and 2023. 

There are at least 18 species in this community including six that are Threatened or Near Threatened and listed as Devon Species of Conservation Concern. Scrambled egg lichen (Fulgensia fulgens) is classified as Endangered, it and Usnea articulata are UK Priority Species. Both have nationally significant populations in Devon, although Usnea articulata is better known as a species of woodlands on Dartmoor and Exmoor.  

Maritime lichens are also recorded at other sites in Devon such as Saunton Down, Baggy Point, and Berry Head.

See the detailed overview for this group in Find out more below.