In the summer of 2007 a short article appeared in White Admiral No.67 about lichens on wood and how structures, such as fencing, took a long time to get to a state where lichens could colonise them before they decayed and were replaced.

It was therefore exceedingly delightful, to discover a park bench in Aldeburgh, by the public library, which was well covered with lichens. On a subsequent visit 18 species were recorded from the seat, and a note relating to the finds was written up in The Aldeburgh Gazette No.452 (September 2009).

The town council was contacted in case the seat might be cleaned, though in fact it was found to belong to Suffolk Coastal District Council, who when contacted said that they would leave it as it was. During a subsequent telephone call, it was discovered that the Council’s policy was to sweep round any seat, but not to clean it, so hopefully it will stay like it is for years to come.

Lichen species on the woodwork
(* illustrated in the photos)

The bench, made of teak, which is a very hard and durable material has obviously been at its present position for a long time, exemplifying the weathering effects, prior to colonisation and also due to the fact that lichens are very slow growing, with increases in radius of about 0.5 to 1.5 mm per year. Thus for the thallus of Physconia grisea, (below), which was approximately 4cm diameter, this would mean about 20 years growth and 10 years weathering time giving a total of 30 years. It will be very interesting to find out when in fact the bench was placed on the green.

Greenish brown foliose Physconia grisea, with dying out central area

The majority of the lichens, as can be seen in the photo below, are located on the seat, arms and top rail of the back. The slats forming the back of the seat, together with the legs and the reverse side are covered with Lecanora expallens, a pale green powdery crustose lichen, and also algae, which in places was parasitised by a fungus, (cf. Athelia arachnoidea), causing a bleached necrotic area.

The park bench well covered with lichens, on the seat, arms and top rail

Most of the lichens seen the seat appeared to be present as one thallus only. The most common was the foliose species, Physcia tenella, which was colouring the seat grey and Xanthoria species, which, though orange, were much less evident. These are indicators of the Xanthorion community, which is present in urban environments, where there are higher levels of nitrogen, from car exhausts sometimes turning roadside trees orange, and dogs which foul bases of trees and lamp posts. Some of the species present, such as Lecanora conizaeoides and Micarea denigrata are common constituents of this habitat, but others like Flavoparmelia soredians, Lecanora chlarotera, Melanelixia subaurifera and Parmelia sulcata are usually found on tree branches, so it was interesting to see them in this situation where they had probably developed from propagules of the lichens on the sycamore (Acer pseudoplatanus) trees close by. Flavoparmelia soNovember 19, 2011 9:17 thallus), but its identity was confirmed by chemical tests.

Amandinea punctata and Phaeophyscia orbicularis are equally at home in a wide range of habitats, including trees, rocks, wood etc, so it was not surprising to see them on the seat. However, Candelarierlla vitellina and Physcia caesia prefer rocks, either acidic for the former or basic for the latter and it is probable that the pH of the wood is neutral thus accommodating all the different species found. One interesting lichen found on the seat was Xanthoria cf. polycarpa. It is morphologically similar to X. polycarpa, but unlike that species, is widely spreading, with relatively few apothecia (fruits) see below, and is thought to be a distinct, but unidentified taxon. It is not uncommon, having been found several times in Suffolk, and also in Scotland, usually on trees.