Lichen: the powerful, silent voice for air quality

Living in Devon, with its pristine air at coastlines and over high moors, and miles of lush lanes and quiet woodlands, we are party to the beauty and detail of diverse lichens in our midst. In some locations, there are startling wisps of rare usnea species, bearding elderly trees on misty days. In much of the county and into neighbouring counties too, rocks, and the twigs and branches of elderly trees are touched with golden parmelia whose reproductive apothecia cluster like tiny gold and jade jewels; or by woodland paths, the intriguing graphis scripta or ‘secret writing lichen’ marks natures codes on tree trunks. Tiny stems of red-tipped fruiting cladonia peer sometimes, from quartzite nooks in granite walls and on the backs mossy boulders. A camera or magnifying lens enhances these details significantly: beware, though, such observations can lead to full blown lichen intrigue and a compulsive longing to find and identify more of the stuff.

The British Lichen Society states that there are up to 1800 known varieties of lichen in the UK alone. Lichens (a sub genus of fungi, comprising in their make-up, of fungus, algae and bacteria) are often estranged from our common vocabularies of wild things: many, if not most country dwellers can identify some varieties of butterfly, bird, tree, amphibian, or wildflower: but who knows lichen? How quietly it dwells amongst us!

Lichen has always played a part in human culture as dyestuffs, animal fodder, preservatives, perfumes and medicines; but it is only in recent decades that scientists have discovered air quality can be monitored by lichen growth. With serious concerns arising in the 1970s, regarding levels of sulphur dioxide pollution in our atmosphere: global scientific observations of lichen growth found that specific species of lichen absent or present, correlated with air quality. This resulted in an accurate, global monitoring index, established by the 1990s.

However, it was as late as 2012 before British lichenologist J.E.J. Lewis proposed a similar monitoring process for nitrogen pollution, in his thesis: Bio-monitoring for atmospheric nitrogen pollution using epiphytic lichens and bryophytes. With nitrogen pollution a major contributory factor to global warming, respiratory diseases, and harm within air-land-water cycles: monitoring nitrogen is valuable research for local and global concerns.

“Nitrogen enrichment in sensitive habitats has become a matter of concern in recent years, and has led to the need to develop a bio-monitoring scheme that could be used by non-specialists to undertake site evaluation across the UK,” wrote Lewis; and from this statement onward, introduced the method by which this study could accurately, reliably and accessibly be carried out.  (Lewis, J.E.J; 2012)*

The method, intentioned to be accessible to members of the public, was further developed by the British Lichen Society, so that all are now able to access the required information, to study and learn, and to participate in monitoring our local lichen distributions for the purpose of monitoring local air quality. The combined results of such monitoring, compiled by the BLS, builds a national picture of nitrogenic air pollution, species diversity and distribution.

For those who have not yet ventured to view more closely, the detail of lichen and how one variety differs in subtle detail to another, I encourage going and looking. Any reason to observe one single subject in nature, leads to delight in more reasons; and from pursuing this intriguing micro-botany into its habitats, curiosity is aroused to its awareness of geology, nature’s soundscape, and the diversity of landscapes or micro landscapes about us.

This serendipitous meandering differs, however, from monitoring lichens for more exacting study. As a forager, salvage-botanist, and otherwise wanderer of waysides, my ventures into lichenology have required additional focus.  For the lay-person to take up and establish a new practice such as lichen identification for air monitoring: community support and encouragement via shared time, knowledge and learning-resources for field trips, are an advantage. It is also beneficial to the integrity of the study.

Over the past two years or so, I have covered some foundation of lichen identification from printed resources, gathered and photographed field samples, online contacts, and the BLS website with its many useful links. I would now like to share this knowledge with others who will carry the practice of lichen identification, for its own sake and for air quality monitoring, into their own communities and networks. This is work that deserves, and which is part of efforts towards change for sustainability and ultimately for the regeneration of eco systems.

What lichens have to tell the world, is magnificent and necessary. Please add your voice and involvement on behalf of this quiet front line.

by Lucy Lepchani


The first meeting of Lichen Club at the Glade on Sunday 23rd June will introduce the basics of lichen identification using samples, lenses, photographs and identification charts, and a mini field-trip.  Further identification meet-ups will also take place this summer.

Cost is by donation, and will go towards furthering lichen awareness projects and resources.

A training day for those interested in the process of ongoing monitoring of lichens for air quality, will take place later in the autumn.


Other links and organisations:

Facebook groups: Lichen Whisperers Network; British Lichen Society

Instagram: #lichenwhisperer #lichenologist #lichenclub


References & further reading:

Lichens as Monitors of Air Pollution:

*Bio-monitoring for atmospheric nitrogen pollution using epiphytic lichens and bryophytes: Lewis_PhD_thesis.pdf

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