To Clean Or Not To Clean?

18/04/2018

Lichens are fascinating organisms made up of a fungus and photobiont (algae or cyanobacteria) that appear to live symbiotically – layers of fungus provide a protective environment within which the algae produce carbohydrates which are used by the fungus. There are approximately 1,700 lichen species in the UK, with habitats ranging from coastal shingle to heaths and woodlands to churchyards and cemeteries. A common sight, particularly in the older sections of churchyards and cemeteries, is lichens growing on the stonework – buildings, walls and Memorials.

The surface of older stonework can provide an excellent habitat for certain lichens, which in turn can provide an indication of environmental health – namely air quality and pollution. This sensitivity to pollution can have significant consequences for lichens, with airborne pollutants being dissolved in water vapour then falling as rain and causing damage to or even destroying lichen colonies. Pollution can also have an impact on the pH of tree bark which can affect the ability of lichens to colonise it.

Over the past few decades, the British Lichen Society has been carrying out surveys of churchyards throughout Britain, mapping the diversity of lichens, discovering the presence of species previously believed to be extinct and also observing significant decreases in some areas. Over 300 lichen species have been observed growing in English churchyards, prompting some councils to develop Lichen Policies with a view to promoting lichen conservation, such as Chesterfield Borough Council https://www.chesterfield.gov.uk/living-here/people-and-families/bereavement-services/cemeteries-and-churchyards/lichen-policy.aspx

So with Spring now in full swing, it’s time to consider whether to clean any growth from the surface of any Memorials that you tend to or to promote biodiversity conservation and let it be!

If you would like any further information about lichens, please visit http://www.britishlichensociety.org.uk/