LICHENS thought to have become extinct have been rediscovered on areas of Dartmoor, including Black Tor Copse near Okehampton.
Black Tor Copse, two miles west of the town, is one of the best examples in Britain of high altitude oak woodland.
The high humidity, mild winters and low levels of air pollution on Dartmoor provide perfect conditions for mosses and lichens. Some of the species found in the copse are threatened with extinction in Europe, primarily because of air pollution.
The copse is owned by the Duchy of Cornwall and was declared a National Nature Reserve by English Nature in 1996. English Nature became concerned about an outbreak of honey fungus whch had killed several of the trees on which the rare lichens were found.
Lichen experts were called in to carry out a survey and re-found the critically endangered lichen Bryoria smithii as well as lots of the nationally rare lichen Bryoria bicolor.
A further survey found the rare lichen Graphina pauciloculata growing in eight areas on three different sites on Dartmoor ? on riverside holly, rowan and hazel in sheltered steep valley woods close to rivers and waterfalls.
Simon Bates, conservation officer for Dartmoor, said: ?It is ironic that a lichen should be called Smith and yet be so rare! Though these lichens are small and indistinctive, they are very sensitive to air pollution. The long-term monitoring that we do at these sites is incredibly important and tell us about the health of our environment?.