Yesterday I was back in Glen Affric again, at the same spot I’d been to a week before. Then, I’d finished the day off by taking some more photographs of one of my current favourite subjects – slime moulds. When I sent the images to Bruce Ing, the expert on slime moulds who helps me with identifications, he said that it was too early to identify that species, as it wasn’t at the spore-producing stage yet, but it could be one of three species, all of which would be interesting records for the glen. So, a week after I’d last been there, I found myself back at a small Scots pine log by the roadside, overlooking Loch Beinn a’Mheadhoin.
I wasn’t sure if the slime mould would still be there, as they are very ephemeral, and sometimes are only visible for a few days at most before they disintegrate and decompose, after they’ve released their spores. However, this one was still on the log, in all the same patches that I’d seen the previous week, although the development of each patch was more advanced. I took quite a few more photographs to send to Bruce, and also collected a few tiny samples, in case they were needed to confirm the species. In due course, Bruce confirmed the identity of this species as being Arcyria ferruginea.
Moving on, I crossed the road and explored the steep slope below it, between the road and the shore of the loch. I walked to a particular area that I hadn’t been to before, and was drawn to a large fallen silver birch tree (Betula pendula), that was covered in moss and had numerous tinder fungi (Fomes fomentarius) growing out of it. The tree was unusual in having two parallel main trunks, with numerous side branches coming off them, and I thought that there might be some interesting things to see on it. Little did I know then that I would spend the rest of the day exploring this one log!
I was attracted initially by the tinder fungi, having recently written a species profile about them. These bracket fungi are hard and woody, fruiting on dead birch trees mostly (although I’d seen one on an alder tree in Strathfarrar a couple of weeks ago) and persist for many years. Some of these ones were quite old and their top surfaces were being colonised by mosses.
Further along the birch trunk there were a couple of fruiting bodies which demonstrated one of the interesting characteristics of this species – its ability to change the direction of its growth, if the tree’s orientation changes. These brackets had begun fruiting when the tree was still standing, and had grown horizontally out from the trunk. However, once the tree had fallen over, their existing growth was now oriented vertically, so they began growing at right angles to their previous direction, with the new growth in a horizontal plane again.
As I explored the tree trunk, I saw some beautiful Cladonia lichens, with distinctive brown apothecia (the part that releases the spores from the fungal component of the symbiotic partnership that is the lichen). There was a whole miniature forest of them, which I looked at through my hand lens – I’ll need to get which species of Cladonia they are confirmed by an expert, as I didn’t recognise them myself. Sometimes I wish I could shrink myself down to miniscule size, just so that I could explore the beauty of these lichen gardens more fully!
Nearby, there were some other lichens that at first glance looked similar, but they didn’t have the brown apothecia – I suspect they are a different species, but again I’ll have to rely on an expert opinion to confirm that. The podetia (or stalks) of these ones were narrower and more finely branched at their tips. Each stalk was an individual work of Nature’s art, covered in tiny scales (or squamules), and together they made a miniature living sculpture that seemed breathtaking to me in its beauty.
Moving up to the base of the fallen birch, I spotted some more slime mould fruiting bodies. These were of a species I know (Lycogala terrestre), and are quite common in our forests. These particular ones were quite mature and were in a cluster. When they are younger they are a pinkish colour and are soft to the touch, whereas the mature brown fruiting bodies are firm to the touch.
I also had a look at the fractured stump of the tree, which was just beside the base of the fallen trunk, and about 6 feet tall. On the side of it some bright yellow shapes drew my attention. These were also slime moulds I think, although it will be another case of relying on experts to get a definitive identification for them – I subsequently had them confirmed as a slime mould (Trichia affinis). I’ve just written an extensive article about decomposition and decay for the Trees for Life members’ magazine, Caledonia Wild!, with information about how fungi and slime moulds play a crucial role in the breakdown of the cellulose and lignin in wood, and this dead birch was providing a classic example of these saprotrophic (or dead wood feeding) species in action.
Back on the fallen trunks of the birch, there were more interesting lichens, and a tiny speck of red amongst some reindeer lichen (Cladonia sp.) caught my eye. It was the red apothecia of another different Cladonia species, and its scarlet colour contrasted vividly with the white of the reindeer lichen around it. The reindeer lichen themselves resemble some corals, with a delicate multi-branched structure that is a good example of fractal geometry in Nature.
There were a number of fallen willow leaves on the birch trunks, from a nearby tree that may have been a goat willow (Salix caprea), although its bark and leaves looked a little different to others of that species that occur in Glen Affric. Many of the willow leaves were still brightly coloured, and some had some large galls on their undersides. These were caused by a species of sawfly, and having consulted with an expert, I’ve been advised that it was most likely Eupontania pedunculi.
The underside of another willow leaf had an unusual insect on it. I’ve subsequently discovered this is the larva of a ground beetle (Leistus sp. probably Leistus spinibarbis, according to comments below from Jorge Angel Ramos Abuin – thank you!), but beetle larvae in general are apparently not well known. It seemed quite late in the year to be seeing insects like this, but it has been very mild for the past few weeks, which has extended the season for invertebrate activity longer than is usual in other years.
As I continued along the other side of the fallen birch, and reached some of the smaller branches, I spotted some more bracket fungi of several different species.
By this time, I was feeling slightly in awe of just how much life there was on this log – the more closely I looked at it, the more I discovered. There were plenty of mosses too, of various species, some of them with their spore capsules held aloft.
There were also other, different lichen species on the smaller branches of the tree, which had presumably been growing in a slightly different micro-climate, higher up in the air, when the tree was still standing.
Despite all that I had seen and photographed on this fallen birch, I realised that I had probably only noticed a small proportion of the total number of species actually living on, and in, the habitat that this log provided. I could probably have spent several more hours exploring it in detail, but the light was fading on this short November day, so I had to pack up my equipment and head for home. Many people might be surprised that I had effectively spent most of the day with this one log, but I hope that this ‘Life on a log blog’ will help to explain why it was so interesting for me!
Jorge Angel Ramos Abuin says
I think it is probably a Leistus spinibarbis larva. Not completely sure. You know, it feeds on springtails…
Alan Watson Featherstone says
Hi Jorge,
Thanks for this – I’ve updated the blog with that information. Intriguing that the larva feeds on springtails, as that’s a group of invertebrates I have a special interest in!
With best wishes,
Alan
Jorge Angel Ramos Abuin says
hello, Alan:
the photograph of the Leistus larva is really good. Do you have more photographs about this larva? Perhaps it is possible to know which species is , but it would be important a photograph of its rear…
Thank you for your work. Congratulations!
Alan Watson Featherstone says
Hi Jorge,
Thanks for your feedback on this photo. I have some more photos of the larva, but I’m not sure any of them will enable a positive identification to species level to be made. I’ll send a couple to your email address though, and you can let me know what you think.
With best wishes,
Alan