Western Morning News (Saturday)
Liking lichens of all shapes and sizes
The Westcountry is a stronghold for numerous species of lichen. A new project is encouraging people to get to grips with these fascinating organisms and record what they find, writes Charlie Elder
Down in the woods where I live, one of the old trees looks like something from the props department for Lord of the Rings films, the branches adorned with various versions of Gandalf ’s beard.
The long tresses hang down from the boughs, tangles of pale filaments some of which extend to a couple of feet in length.
These outlandish growths that festoon the tree are beard lichens, and if you spot them you can breathe easy in the knowledge that they only grow in woodlands where the air is clean.
Other lichens familiar to most people include those paint-like splotches of colour you see on walls and coastal rocks, as if the abstract artist Jackson Pollock had been let loose with a splatter gun and cartridges of orange and yellow paint.
There are also the more subtle species which adorn churchyard gravestones and tree trunks with their disc-shaped badges of grey-green or scattered brown tufts resembling dried seaweed.
Lichens are a varied and fascinating group of organisms, though far from easy to get to grips with when it comes to identification, especially as there are around 1900 different kinds in the UK.
A Westcountry project is now calling on people to get involved in helping map a selection of specific species as part of the Saving Devon’s Treescapes project.
The Treescapes project, led by Devon Wildlife Trust, was launched in response to the spread of ash dieback disease which threatens to wipe out 90 per cent of ash trees in the county. The partnership project, supported by the National Lottery Heritage Fund among other funders, aims to plant 250,000 trees to mitigate losses, and is also assessing wider impacts on nature.
One concern is that lichens which grow on ash trees may decline or be lost as a result, and earlier this year a recording scheme got underway, with an online training video to help volunteers identify a dozen or so target species.
The Westcountry is a stronghold for many lichens, especially those which favour clean air and damp conditions, and Devon boasts over 900 species.
That is a fairly daunting number for anyone trying to begin identifying lichens – myself included. However, there are a few ways to narrow things down.
But firstly, what on earth is a lichen? They can appear more dead than living.
Lichens are actually made up of two or more organisms which live in partnership. The protective structure is a fungus and living within, providing carbohydrate energy generated from sunlight, are photosynthesising algae and/or single-celled cyanobacteria.
Lichens are slow growing and can be long-lived (an Arctic species called ‘map lichen’ has been dated at a staggering 8,600 years old). They are also not parasitic, so they don’t damage the trees they grow on.
Some species require alkaline conditions and bark can become more suitable with age, in particular the bark of ash trees. It is estimated some 500-plus lichen species are associated with ash, so the loss of these trees through dieback disease is real cause for concern.
Jess Smallcombe, a community ecologist with the Devon Biodiversity Records Centre who is involved in the recording project, says: “If ash trees are going to be affected as much as we fear they are, then we would like to see if there’s a knock-on effect on various other species, such as lichens that live on them. To do that we need to know what’s there now.”
Lichens basically consist of a main body called a thallus, root-like fibres beneath, known as rhizines, used to attach to a surface, and they reproduce by producing fruiting bodies which expel fungal spores, or by shedding tiny packages of good-to-grow material – and the species’ reproductive growths or indentations can help with identification.
In simple terms our lichens can be divided into three kinds: flat crusty ones, leafy ones and bushy ones.
The crusty ones, known as crustose lichens, are the thin, flat kinds which look as if they have been pressed like a sticker onto the bark or stone, or coat surfaces as closely as a layer of paint. The leafy ones, known as foliose lichens, look a little more like plants, having leaf-like lobes, while the bushy fruticose types have branching filaments attached by rhizines at the centre to the tree, and include the beard lichens.
While some lichens are very sensitive to pollution, others are more tolerant, and some thrive in nitrogen-rich environments – even on bird dropping-splattered rooftops.
The panel on the right lists some key species being recorded by the Treescapes scheme in Devon.