There appears little to see in our churchyard on a grey February day, but take a walk round and look at the graves and monuments and the bare branches of the trees, and you will see the coloured patches and crusty growth of lichen, a strange organism that seems to be neither plant, animal, nor fungus. These fascinating but often overlooked lifeforms are everywhere around us.
Lichens are actually 'dual' organisms, consisting of two or more different lifeforms living together symbiotically. The main partner is a fungus while the other is either a green alga or a photosynthesising cyanobacterium, sometimes both, known as a ‘photobiont’. Lichens pose a problem for biological classification because the three types of organism concerned come from three different kingdoms. After long debate, lichens are now classified as fungi, named under the genus and species of the host fungus.
The fungal partner provides a sheltered environment for the photobiont, protecting it from the elements and providing mineral nutrients. The alga or cyanobacterium partner provides food for both by the process of photosynthesis. Although the photobiont partner can in some cases live independently if conditions are right, the fungus cannot, and is totally dependent on the photobiont for its shape and structure.
There are around 1800 species of lichens in Great Britain and Ireland with more still being discovered each year, either new to the region or new to science. This compares with about 1760 species of native plants. There are four basic lichen growth forms; crustose, squamulose, foliose and fruticose, each with specific, although sometimes difficult to determine, characteristics. The fossil record for lichen definitely dates back 400 million and earlier forms may have existed up to 600 million years ago making them one of the earliest life-forms on land.
Lichens add another layer of diversity and beauty to our environment with their different colours and shapes. A landscape without lichens on the rocks, walls, fences and trees would be so much less interesting. They contribute to a rich ecosystem, providing food and shelter for a wide variety of tiny invertebrates, and small birds use fragments of lichen to camouflage their nests.
Reproduction is asexual, with flakes of dry lichen breaking off to be blown away on the wind to colonise where they land.
Many lichens are sensitive to changes around them and can be used by scientists to analyse air quality and show changes in the environment such as air pollution, ozone depletion and metal contamination. They grow extremely slowly, some reaching up to 1000 years old, and their diameter on a piece of rock can be used to show how long the rock has been exposed.
Some lichens produce substances which kill bacteria and have been used by people over the centuries as natural antibiotics to heal wounds. Lichens have also been used to make dyes, perfumes and herbal medicines.
Churchyards are usually areas of ground that have remained uncultivated for many years, and as such they have the potential to be havens for wildlife where plants and animals can thrive among the graves and monuments. Indeed, until the 20th century they were wild, un-mown places, alive with bees and butterflies, occasionally even grazed by sheep! In the 21st century properly and sympathetically managed churchyards can again become places of wild beauty and tranquillity, surrounding us with the comforting reminder of the ongoing life and vitality of God's creation even amidst the sadness we feel at the passing of our loved ones.
The seeds of the Churchyard Conservation Project were sown early in 2013 when, while looking at ways we might try to encourage new people to come along to church, and with the added asset of an enthusiastic zoology graduate embarking on a career in conservation and ecology, we hit upon the idea of organising a bird box building session in the churchyard, which we advertised with posters around the village, and which proved to be a huge success.