After spending a day alongside the Allt na Imrich watercourse and nearby areas in Glen Affric, I’d been hoping for a still, clear night, followed by one of those misty, atmospheric mornings that are so characteristic of the Caledonian Forest in the autumn. However, the weather proved to be very different, and it rained heavily for almost the entire night, although I was completely dry inside my tent. There was no let up in the morning either, and it was a very grey, dull and wet landscape that greeted me when I eventually emerged into the new day.
One of the first things I noticed was the remarkable proliferation of lichens on the trees. They are there all the time of course, but after heavy rain like this they are much more visible and obvious, as they have expanded to their full size because of all the moisture.
These lichens are all epiphytes, meaning that they use the trees for support only, and do not take any nutrients from them. They obtain their food instead from dust and small pieces of plant debris that get blown on to the trunks and branches where they are growing, and from the moisture in the air itself. The presence such an exuberant abundance of arboreal lichens in places like Glen Affric is due to two main factors – the clean, unpolluted air, and the generally wet weather, which provides the ongoing high levels of atmospheric humidity that are necessary to support the lichens.
As I was nearby, I decided to return to the Allt na Imrich, and was only slightly surprised to discover that the water level was even higher than it had been the previous day!
The relentless overnight rain had swollen the watercourse still further. Whereas the day before it had been a raging torrent, now it was in full, tumultuous spate, pouring over and around the rocks, and temporarily inundating some small groups of young trees that were growing on what is usually an island in the middle of the burn. The sheer volume, power and sound of the rushing, cascading water was impressive and awe-inspiring. How rivers like this must love the rain, I thought, as I reflected no how much more fully it had become itself, due to the greatly increased amount of water flowing in it.
I walked a little further upstream beside the burn than I had done the previous day, and I found another cluster of golden-scaled male ferns (Dryopteris affinis), growing right beside the water’s edge and at the peak of their autumn colour as well.
Although it was another gusting, windy and wet day, this spot was slightly sheltered, because of a small rise to the west, on the upwind side of the burn. By waiting for a few minutes I was able to take some more photographs of the fern fronds completely motionless against the blurred background of the rushing water behind. Somehow the contrast between the fluid motion and utter stillness, combined with the rich autumn colours of this scene really spoke to me …
It struck me again that there is such stunning beauty in the detail of Nature all around us. Even a simple fern like this was creating a beautiful living work of art, with its brilliant colour and still poise, whilst seemingly being oblivious to the torrent of peat-stained water rushing past just a few inches away. In our increasingly speedy modern world, where everything seems to occur at a faster and faster rate, the stillness and beauty of this fern resonated deeply with me, symbolising some of things I value most dearly in my life.
Leaving the burn, I walked through the trees back towards the road, passing as I did so a birch log which had a number of brackets of the tinder fungus (Fomes fomentarius) fruiting on it.
These were also looking vibrant and alive from all the rain, which had given them a shiny and wet appearance. On one part of the log there were two brackets which were growing in planes at right angles to each other. This is because the fungus is positively phototropic, meaning that it grows towards the light, so that its fertile surface, where the pores are that release the spores, is always facing towards the ground. In this case, one of the brackets must have grown when the tree was still standing, but was now pointing vertically upwards, while the other, younger one had grown since the tree fell, so that its orientation towards the light was correct.
The fallen trunk and branches of the birch were scattered on the forest floor, and on one of the smaller branches I spotted a few tiny clusters of the fruiting bodies of a slime mould. I was pleased to spot these, as, rather surprisingly, I haven’t seen many of them at all this year. I don’t know if the conditions haven’t been right for slime moulds to fruit this autumn, or if it’s just a case of me not being in the right place at the right time to see them. I wasn’t able to immediately identify this particular one, so I’ll have to consult with Bruce Ing, the country’s expert on slime moulds, to find out the scientific name for it.
These blaeberry plants were a slightly different colour to those I’d seen on the knoll the previous day, being more orange and paler red than the scarlet of the other patch, possibly due to there being different nutrients available in the soil here.
The weather was making photography quite difficult, as it was raining more or less continuously, and the wind was often gusting quite strongly, so it was hard to keep the lenses on my camera dry, even with the aid of an umbrella to provide some protection. Sometimes I was having to wait for 10 or 15 minutes in order to be able to take a photograph, and I had to discard many that I did take, when I found that raindrops on the camera lens created a blurry distorted area on the images. With the conditions showing no sign of improving, I decided to head back down towards the road, where I’d be able to take some shelter in my car from the elements.
There were some colourful rowan trees (Sorbus aucuparia) beside the bridge over the Allt na Imrich that I’d seen earlier in the day, but had been unable to photograph at the time, because of the conditions. I returned to them now, and after waiting for a few minutes, was able to take advantage of a lull in the wind to catch some images of the trees with their leaves motionless.
While I was waiting for a break from the wind and rain, I noticed a patch of brown lichen on top of the parapet of the bridge over the burn. Looking closer, I saw that it was one of the kidney lichens (Nephroma laevigatum), which is an indicator species for old growth forests. It also grows in very wet places, occurring in the temperate rainforests of the Pacific Northwest of the USA and Canada, as well as in western Ireland, indicating that, like that region of North America, parts of Scotland and Ireland previously had temperate rainforest ecosystems as well – today only tiny remnants of those survive.
Lichens are compound organisms, consisting of a symbiotic, mutually-beneficial partnership between a fungus and an alga. In some lichens, including those in the genus Nephroma, there’s also a third organism in the partnership – a cyanobacterium in the genus Nostoc. This acts as a photobiont, enabling the lichen to absorb, or fix, nitrogen from the air into its physical structure. When the lichen eventually dies and decomposes, this nitrogen becomes available in the soil and for other organisms, so the lichen acts as a dynamic source of natural fertiliser for the forest ecosystem.
With there still being very little respite from the wind and rain, I decided to head for home, but as I was driving back down the glen, my attention was caught by the brilliant gold colour of an aspen tree (Populus tremula) at Dog Falls. This is at a narrow part of the gorge of the Affric River, so I stopped, hoping that the confines of the area might provide a little shelter from the wind, so that I could take some photographs.
While I was waiting for the wind to stop, I saw a brightly-coloured fallen aspen leaf on a rock beside the river. This had a distinctive green patch on it, which is the result of a mine made near the base of the leaf by the aspen green island leaf miner moth (Ectoedemia argyropeza).
The mine, where the moth’s larva feeds in between the cell layers of the leaf, acts as a natural blockage, preventing the tree from withdrawing chlorophyll from that part of the leaf. It remains green as a result, while the rest of the leaf turns yellow, once the chlorophyll from it has been taken back into the tree, and the other colours in the leaf become visible. This leaf was slightly unusual because it also had some patches of red on it.
By this time the light was beginning to fade because of the overcast conditions, and this is particularly evident in the photograph here looking up the Affric River towards Dog Falls, where the colours are very muted and dull. As I set off for home I reflected on the fact that it had been quite a challenging day for photography. However, despite that, and the absence of the foggy, wind-still conditions I’d been hoping for in the morning, I had nevertheless managed to find a few interesting subjects, so I left feeling satisfied, albeit rather wet!