LNHG field trip to Glen Creran Woods

We met at the same place as for our December 13 trip, but instead of making for St Cyril's well, this time we headed in the opposite direction with the aim of reaching the "ship on the rock" carving by lunchtime, looking at lichens along the way.

Conditions were mostly dry with the odd spot of rain and occasional glimpse of sun. Lichens on dark trunks in winter woodland are not well lit so please make allowances for the photography. I generally take some with flash and some without, but though the flash ones are much sharper they look nothing like the real thing so I always end up using the non-flash ones, and so do our other photographers.

Glen Creran Woods SSSI is "outstanding, on a national and international scale, for its exceptionally rich oceanic lichen assemblage which includes 4 globally vulnerable species, 19 globally near-threatened species, 10 nationally rare species and 66 nationally scarce species." (SNH) Old birches are plentiful here. In Sallie's photo above the two large yellow-green patches are Flavoparmelia caperata, common on birch and probably the only British lichen that can be recognised at such a distance - you can often spot it from the car.

On the left a close-up of F caperata with its characteristic wrinkled surface. Another very common birch lichen in our area is Hypotrachyna laevigata. It is usually infertile but in these woods it bore fruit as shown in Jan's pic on the right.

Hypotrachyna taylorensis reproduces by countless small fragments which can form new individuals when detached. It is also notable for the hanging rolled-up lobes that it develops when well-grown.

Mycoblastus sanguinarius has globular black fruits which show bright red tissue underneath when they break off.

Unlike hazel lichens, those on birch are nearly all the same colour, a pale blue which is greener when wet (as in the H taylorensis above which was at the foot of a trunk and had not dried out as much as today's other lichens). This may be due to the limited range of algae suitable for lichens on acid-barked trees. Not a subject that I know much about.

As expected in old oceanic birchwood, we found several examples of the Flute Lichen, our Species of the Month. Most of them were small patches hemmed in by other lichens, but this one has attained a good size and shape. The close-up shows the holes in the hollow lobes. As well as its usual host of Birch, we also found the Flute Lichen on Alder and Holly.

Hazel with its alkaline bark has a much more colourful range of lichens, many of which contain cyanobacteria rather than green algae, and in some cases both. Jan's pic on the left shows the blue-grey Lobaria scrobiculata (lower half of pic), the grass-green of L pulmonaria (top), the deeper green of L virens (left of centre) and the pale blue of Parmotrema crinitum (just above centre on right). The RH pic shows more P crinitum, aka "Desperate Dan", on Holly, which in this wood had many of the same species as Hazel. Desperate Dan is easily recognised by the stubble of black hairs which arise from the upper surface of the lichen, similar to the hairs which form "roots" from the underside and "eyelashes" from the edge in related species.

Hazel also supports a number of jelly lichens, including the Frilly-fruited Jelly Lichen (Leptogium burgessii) on the left, easily recognised by the much-incised leafy edging to the fruit, and the rare L hibernicum on the right. This oceanic species is "dependant on a very humid climate with more than 200 rain days per year" (Coppins 1976, quoted on the excellent Oslo Natural History Museum site)

Made it! A GPS is a wonderful thing when you're lost in the woods. This is the Birlinn carving, dated 1729 but thought to have been re-touched on that date from an earlier original. Time for lunch.

Near the carving are the Well of the Eye (left) and the Well of the Knee (right). Dip your knee in that and you'll never have knee trouble again. They are not real wells but hollowed-out stones which hold rainwater and are covered by the slabs seen in these photos.

This might be another carving on a rock near the Birlinn, but we couldn't make out what it was meant to represent and the lines may be natural features. Where's a geologist when you need one?

Another ancient woodland indicator is the Horizontal Dog Lichen (Peltigera horizontalis), recognised by the large fruits which are held horizontally relative to the lichen surface. On the right is the more widespread Smooth Dog Lichen (P hymenina) which has smaller vertical fruits. (the fruits appear at all angles in the photos because the lichen surfaces that they're growing from are at all angles).

It was pleasing to find a large patch of Tunbridge Filmy Fern hanging over damp shady rocks. It differs from the commoner Wilson's Filmy Fern in having toothed valves to the spore capsules, shown in Jan's close-up on the right.

Cladonia species are photogenic but hard to identify. The one on the left comes out as C macilenta. On the right is C pyxidata, which is normally on the ground or low rocks and peat-banks, but is "surprisingly able to grow on Hazel branches in high-Atlantic hazelwoods" (Alan Silverside) and that's exactly what it's doing here.

This amazing shot by Jan is probably another C pyxidata but I can't be sure and didn't see what it was growing on. Worth including anyway!

Another great shot for Jan's future best-selling Atlantic Woodland Calendar, if anybody can persuade her to produce one.

Leaves that remain on willows when the rest fall off are normally due to the chemical action of the Willow Cabbage Gall-midge, but this is something different. Some creature has woven a shelter out of the leaves for its eggs or itself to overwinter in, and it may be just the physical effect of the webbing that keeps the dead leaves in place.

Hummocks of Sphagnum palustre dominate the wetter parts of the woodland floor. The drier parts are turned to slushy mud by the feet of cattle, and the steeper bits are of slippery grass. At least the bracken doesn't get in your way at this time of year.

The cinder fungus Birch Woodwart on birch, and the Barnacle Lichen, Thelotrema lepadinum, on Hazel.

Thanks to all who took part. Next field trip is on Sat 14 Feb at North Shian, details to be announced.