Wednesday 29 February 2012

Lichens of Malham Tarn Fen

We're off to the woods today!
Allan Pentecost is leading the first of two introductory lichen days, as part of a series of introductory days run by the Lichen Society at FSC centres throughout the country - His second day will be 31 March

Today I am one of his eight students. We set off through the cutting . (N.B. this page has not yet been checked by Allan)
Past the snowdrops at the cottages
to the boardwalk on the fen, and the side bridge at the inflow stream.

Parmelia saxatilis  This foliose lichens has isidia on the older parts -( lots of tiny dark grey projections -)
and a coarse network of white lines on the younger parts
(click on the image to see a larger version)

Where we look at a willow tree in detail

Les takes a photo

In great detail.
Left: Parmelia sulcata This also has raised white lines, along which, on older parts, soralia  may develop
 It does not have isidia.
Right: Platismatia glauca -
This is only attached at one point, it is not flat on the bark,
so it is more like a shrubby lichen.
It is pollution tolerant.
The underside is dark and the thallus has frilly lobes.
Platismatia contains a lot of a chemical  called lichenin
-  a starch similar to that found in bread -

Pollution -

I remember 30 years ago (oh so long!!) being told by Mark Seaward whilst looking at the same trees (but 30 years younger..)  that the lichens we were finding could tolerate up to 60ppm sulphur dioxide pollution.  Sulphur dioxide pollution in the past limited lichen growth - from the Lancashire milltowns 25 miles away (south) and Yorkshire mill towns 30 miles -Plus to the east. Thirty years ago we found only one patch pollution sensative Usnea on a birch tree. This time we looked hard and someone did find a tiny piece of Usnea - but not near the board walk, and I haven't got a picture of it.

On a side branch of a willow tree we find an early coloniser - Fuscidia lightfootii
Fuscidia lightfootii This has colonies that are usually less than the size of a 50p piece.
It is light green with dark fruiting bodies.
It is found on twigs and you branches in wet and boggy places especially in the south and west.

On the same trunk as Les is photgraphing we have
Mycoblastus fucatus a grey crusotose lichen .
Now, is that the papery grey of patches 1a and 1b (note they have a few black apothecia)
or is it the more lumpy bluey grey of 2?

Next we follow the side stream about 20 yards and look at an area where the birch and willow scrub was removed about three years ago. We find not one but several species of Peltigera.

Peltigera are the only lichens that we find on the fen that have Cyanobacterai (Blue green algae) as the algal part of the lichen - all the other Lichens have green algae. Allan suggests this is because bluegreen algae tend to prefer less acid conditions - and the fen and peatbog are made of Peat - perhaps the parts where we find the Peltgera are lower down and growing on plants that receive more base rich groundwater.
There are two Peltigeras here. There one with a felty surface and one with a smooth surface.


Need to look at them with a hand lens or under a low power microscope to look at the rhizinae. 

We found P praetextata, P hymenina, P horizontalis, P membrancea,.. but I still need to sort them out.
I think we could have had a whole day on Peltigeras!!

We found lots of different species of Cladonia:- 
Cladonia fimbriata
That's the one in the centre of the picture,
on the left side of the trunk.
We had a brief visit to the peat bog proper - but by, was it cold! 
then returned for lunch.- Hot soup and fresh sandwiches. Delicious.

Welcome Hot homemade soup back in Malham Tarn House.

In the afternoon we looked at our specimens .. and then ..... a guided tour of the lichens on the wall of the house... but that is for another blog post..

introductory British lichen society - FSC days 

Other posts on this blog on lichens:-

  1. Lichens of Malham Tarn Fen - with Allan Pentecost 29 February 2012
  2. Lichens flourescent in bonfire light  5 Nov 2011
  3. Opal Lichens Settle    CCG walk led by myself -  2 April 2011
  4. Algae (and Lichens) for Beginners - Malham Walkwith Allan Pentecost Aug 2009
  5. Lichens Day at Giggleswick Churchyard with Mark Seaward 14 June 2009

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