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I was recently asked to look at a churchyard to assess its importance for lichens. The most notable lichen present is perhaps the Nationally Rare Rinodina calcarea, present in abundance on the top of the chest tomb shown here (left side of photo).
Rinodina calcarea will probably be downgraded to Nationally Scarce now we can recognise it in the sterile state but is still a notable lichen. https://twitter.com/obfuscans3/status/1169906826214703107
In its sterile state, R. calcarea was my 'Sand Point mystery' for several years. https://twitter.com/obfuscans3/status/1210927636194713601
The churchyard is in a small town and many of the memorials were removed in the past. These factors mean that it is not as rich as a good rural yard but still supports a good range of interesting lichens.
On the vertical stonework below the buttress slope is a sooty evaporite deposit, a legacy of decades of coal burning in the past. On the slightly mossy buttress slope above is more black crust, this time a lichen (Verrucaria nigrescens).
So, in close up, here are two apparently similar black crusts but one is mineral (lower half of image, the sooty evaporite deposit) while the upper half is living - a black lichen.
Here we have white lichen thalli, on the gravestone and on the tree trunk behind. Predominantly Lecanora horiza on the former and L. chlarotera on the tree. Each 'splodge' is an individual. Can you see a difference in shape between splodges on stone and tree bark?
Note that the thalli on stone are roughly circular, each started from a germinating spore and grew outwards at roughly equal rate in all directions. The thalli on the tree trunk are horizontal ovals - caused by 'stretching' of the thalli as the tree trunk increased in girth.
Here we have a limestone gravestone with over twenty species of lichens. Note that there is a vertical central zone where grey lichens are more exuberant. The stone leans slightly away from us. Droppings from perching birds fall mainly on this side and mainly below the apex.
Sometimes yellow lichens predominate where the droppings fall and produce more noticeable bird stripes. https://twitter.com/obfuscans3/status/962461574169595906
The second image shows the other side, leaning towards the camera, receiving no direct deposition of droppings but some seepage from the shoulders forming inconspicuous yellowish vertical stripes. The dry central part has very sparse lichen cover.
Sometimes I encounter specimens of Xanthoria 'calcicola' like this which look somewhat different, without the distinct colour zonation at the edge and with larger isidia-like structures. Is this a separate taxon? I am undecided.
Are these really the same taxon?
Here are five gravestones, the centre one is ironstone, the four others to either side are limestone. There is some overlap in species but the abundances and lists are very different.
The side of the ironstone gravestone is dominated by Diploicia canescens (Brain Lichen). https://twitter.com/obfuscans3/status/1209546088757256192
Behind and right of the chest tomb is a very mossy coped tomb. This is made of calcareous sandstone, more porous than most other stone in the graveyard and the moisture holding properties gives moss an advantage.
Note the absence of ivy on the memorials in this well kept churchyard. Ivy provides valuable habitat but is much more common than the lichen communities on these old memorials. Keeping them free of ivy is good for biodiversity.
Here is a granite memorial, the inscriptions obscured by (mainly) algal growth. Is it acceptable to clean it so the inscriptions can be read? I said 'yes'. There are no notable lichens present on the main memorial.
Note the bottom tier of the memorial, while still granite, has more lichen and algal growth. The upper parts are polished while the lower tier is dressed with chisel marks. The finish of the surface has a long-term influence on the colonisation.
The granite memorial sits on a sandstone slab (supporting the railings), this slab much more heavily colonised by lichens than the granite. The under-recorded Bacidia fuscoviridis is a feature of the horizontal surface of the sandstone here.
On the church wall behind the railings there is a brown block of ironstone in a predominantly limestone wall. Much of this shaded wall has a reddish crust of Trentepohlia alga (not a lichen).
Restoration of the Chantry Chapel. Nice to see that some of the old chamfered plinth has been left. This allows for long term colonisation from the ancient stonework which is retained.
In an hour and a half, just over seventy species of lichen were recorded. More work to do another day.
Memorial plaque to those killed in the Great War, including my namesake and uncle.
