SD86 - 01b - SD8061 - Rathmell - North - Drought - May 2020 - Lichens

20 May 2020.

Here we are - a year and a quarter into of my SD86 hectad survey  surveying the area 1km square (monad) at a time. This 10 by 10km square includes Settle, of Settle Carlisle Railway fame.

And I am back at only the second monad.

SD8061, near the Ribble near Rathmell.

I surveyed strip of 10 monads SD8060 to SD8069 last year (Rathmell to Helwith Bridge) and initially aimed to do the adjacent strip of 10 monads SD8160 to SD8169 this year. I am here today because, with the Coronavirus Lockup, I am doing lots of walks (Settle Wildflower) from home and from Settle - and today I am walking two miles downstream along the Ribble from Settle. 

And I have ended up back in SD8061

I am standing next to a large alder tree with an amazing covering of lichens on its trunk.

Amazing because the majority of the other trees around (and there are only about 16 large trees in the 1km square) have very few lichens.

Last time I was surveying near here I was limited as to where I could survey because of ...

floods



So the base of this tree was then standing in one foot of water - and the depressions under several feet. 

The alder tree is to the right
just off the picture taken in March 2019.

Now we are in a drought.

I have only crept south into this monad by a few tens of meters. It is 8pm and I am making my way from the river Ribble back to the road, having photographed Settle Sewage works for a photo project. It is still light so I trundle across to an alder trunk not far off my route, lit up by the sun as it shines brightly. The sunlight, now parallel to the ground, dazzles into my eyes.

- First I notice the frilly  Ramalina and maybe some Evernia on the trunk -

- and then that the trunk has abundant lichen cover nearly all the way round.

In fact all the way round except for an area where cattle enjoy rubbing against it.

- and then that all the species seemed to be exceptionally isidiate or sorediate. (pictures at end.)

I ask myself "Is this really Parmelia saxatilis .. with so many isidia.. but no pseudocyphellae?"  "Is this a new species of Physcia with not just the tips of the lobes turned up and covered with soralia, but all the margin of the thallus?"

Then I discover the Xanthoria polycarpa. (Cushion Xanthoria according to an Opal leaflet)

Shown here and magnified A LOT



Whoopee!. My first very own X. polycarpa in SD86

(The above tuft measures about 0.5 cm across. Note it does not have much thallus. The very common Xanthoria parietina is different because it is big and has lots of thallus and just a relative few fruiting bodies scattered across it.)

Some may wonder at my enthusiasm for finding this.

Yes, Allan Pentecost showed me a piece at Malham Tarn several years ago but a) That was "his" and b) It wasn't there the next year. - It is good to find a specimen for yourself.

(There is no dot for SD86 the distribution map of X. polycarpa in Dobson 2018), though I know that many records have been added to the BLS database since then)

Those of you who have taken part in the OPAL Lichen Air Survey will know that on printed card there are three species designated as "Indicators of heavy N Pollution" : Leafy Xanthoria (parietina) Cushion Xanthoria (polycarpa) and Physcia.

But what does Cushion Xanthoria look like? I have been constantly asking, over at least 6 years. "We don't get it round Settle".. Gallons, acres, swimming baths full of Xanthoria parietina, But no polycarpa.

In 2016 I found some polycarpa in Leeds in Meanwood Park preparing for the YNU students and blogged about it here

Well back to the X polycarpa - there are about dozen small pieces of it on the trunk. There are some other yellow lichens too.

Possibly Candelariella reflexa and Xanthoria ucrainica


I work my way round the trunk at nose level and find a piece of Flavoparmelia caperata

Flavoparmelia caperata

and then - my pièce de résistance - Parmellina pastillifera. This is now the 9th monad I have found it in out of the 25 monad's I have looked at so far. (There were no records of this in the Hectad  six years ago)

Parmelina pastillifera plus Candelariella reflexa - the fine yellow powder like lichen at the bottom right 

Close-up of Parmelina pastillifera You can clearly see the dark brown button-on-stalk shaped isidia

I makes me wonder, Why are some trees, indeed sometimes just a bough of a tree, able to support a good covering of lichen whilst so many other trees have none or hardly any at all.

Just as I am leaving I notice that the tree is actually growing over a (now totally dry) drainage ditch, which went undergound here. These drainage ditches must be very important in times of flooding. I wonder when they were built. 1700s? Late 1600s?

So why such good cover on certain individual trees?

Hypotheses:

1. The lichens benefited from the cows rubbing the tree.
2. The lichens benefited from the drainage ditch
3. There is some magic fungal (maybe algal or bacterial) species present on this trunk - from which all the lichens on this trunk are benefiting. Maybe in some way the lichens help each other.

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Any suggestions?

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That evening I then got side-tracked into drainage ditches. (This one could easily be 250 or 300 years old - older than the tree)

The flat area between Settle and Hellifield used to be a glacial lake.

The Ribble used to flow east into the Aire near Hellifield, continuing east to the Ouse, Humber and North Sea. Ice sheets / glaciers flowed from the Lake District in the west and down the Ribble Valley. But at the end of the Ice age moraines and drumlins blocked the Ribble. It was a lake. It was diverted south west back to Preston.

See Long Preston Geotrail

Then I got side tracked into into heights above sea level. The current Ribble bank and my Alder tree are at 128 m above sea level. But heights are for another day.
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Here are some more pictures. I am still pondering over the identification of some of the lichens

Xanthoria ucrainica? (goes red with KOH)

This picture is Ramalina farinosa

What is this? (Lichen1) (plus ordinary Physcia tenella top right)

I think this is Lecidella eleochroma

Physcia tenella (including apothecium with black centre) - but all the margin of the thallus seems to have soredia .
Also Lecanora chlarotera, Xanthoria polycarpa, Melanelia glabratula (top left) Lecidella eleochroma (top middle left)



Is this Ramalina farinacea being very frilly?

View of fields from Settle-Rathmell road in March 2019 - the alder tree is to the right just off the picture.