Science and London lichens
The London scientists who study lichens
Coal miners once used canaries to warn them of the presence of dangerous gases. In a similar way today, we can use lichens as indicators of air pollution.
The Department of Botany at the Natural History Museum has a collection of over 6 million preserved specimens which includes lichens. Among the 50 scientists who work in the department are experts in the study of lichens.
The 'canaries' of the plant world
Lichens. are very sensitive to air pollution so they are natural indicators of the health of the environment.
Many pollutants affect lichens including sulfur dioxide, acid rain and various nitrogen compounds such as fertilisers and ammonia. This means that there are not many lichens to be found in London compared to remote rocky coasts, mountain tops and the polar regions.
Lichens in Regent's Park
Regents Park is just one of the places in London where you will find lichens. Most obviously on the rims of the stone urns in the formal gardens. These lichens have to survive in air affected by cars on the nearby roads. Lichens are returning to London following major reductions in sulphur dioxide air pollution produced by domestic coal burning and power stations.
Recent research by scientists at the Natural History Museum suggests that nitrogen pollution from cars may be nowadays limiting lichen growth and distribution.
The yellow lichen on the stone urns is a good example. It is Xanthoria parietina normally associated with rocks where birds perch. It is abundant at the coast but has now spread as a result of human activities. This species features on the front cover of a booklet on lichens by William Purvis which is available from the Natural History Museum.
Submitted by: William Purvis, 17 January 2007
