Alan Watson Featherstone, the founder of Trees for Life, writes about his experiences out in the Caledonian Forest, and about his work for the charity.


A day in Glasdrum Wood, Part 2

Alder trees (Alnus glutinosa) covered in moss in the temperate rainforest of Glasdrum Wood National Nature Reserve.

Alder trees (Alnus glutinosa) covered in moss in the temperate rainforest of Glasdrum Wood National Nature Reserve.

This is the follow up to my previous blog, about my visit to Glasdrum Wood National Nature Reserve in Argyll at the end of July. Rather than make one very long blog, I decided to split it into two, in the interest of making it more readable, and also for my own ease of posting blogs relatively regularly. The amount of work involved in creating each blog is obviously proportional to the length of the blog, and my aim is to get two blogs posted each month, so dividing my day at Glasdrum between two has enabled me to keep to that schedule.

Common spangle galls induced by a wasp (Neuroterus quercusbaccarum) on the underside of an oak leaf.

Common spangle galls induced by a wasp (Neuroterus quercusbaccarum) on the underside of an oak leaf.

Anyway, continuing on after my lunch break at Glasdrum, I came to another group of oaks (Quercus petraea) and on one of those I found some common spangle galls on the underside of several leaves. These are induced by the sexual generation of a tiny wasp (Neuroterus quercusbaccarum), and I featured the currant galls produced by the agamic, or non-sexual, generation of this wasp in a recent blog from Glen Affric. These spangle galls were quite young and hadn’t reached their full size yet. They would do so by the end of the summer, and then the wasp larvae overwinter as pupae in the galls on the fallen oak leaves on the ground, before emerging in the next spring to lay eggs on the new leaves and catkins of the oak, inducing the currant galls once again. So the cycle of alternating gall types induced by this wasp continues …

Some more common spangle galls induced by a wasp (Neuroterus quercusbaccarum) and an aphid (Tuberculatus annulatus) on the underside of an oak leaf.

Some more common spangle galls induced by a wasp (Neuroterus quercusbaccarum) and an aphid (Tuberculatus annulatus) on the underside of an oak leaf.

While I was looking at the galls I noticed one or two aphids on the oak leaves and I suspected these were the common oak aphid (Tuberculatus annulatus). Ed Baker, who helps me with aphid identifications, confirmed they were indeed Tuberculatusbut said he’d need a specimen to confirm the species.

Closer view of one of the common spangle galls and a common oak aphid (Tuberculatus annulatus).

Closer view of one of the common spangle galls and a common oak aphid (Tuberculatus annulatus).

 

 

 

 

 

 

 

Detailed view of the common oak aphid (Tuberculatus annulatus) on the oak leaf.

Detailed view of the common oak aphid (Tuberculatus annulatus) on the oak leaf.

In the interim, I’ve labelled these photos here as being the common oak aphid (Tuberculatus annulatus), and will amend this if necessary, if Ed comes back with a different identification from the specimen I’ve sent him. I liked the visual combination of the hairy, deep red gall and the yellow-green of the aphid. Seen together in close up they reveal some of the wonders of the miniature world all around us, but which is rarely seen or appreciated – I had to search quite a number of the oak’s leaves to find the galls and then spot the aphids amongst them.

I thought these orange protuberances might be some sort of fungus, but they turned out to be adventitious roots on the trunk of this downy birch.

I thought these orange protuberances might be some sort of fungus, but they turned out to be adventitious roots on the trunk of this downy birch.

Something caught my eye on a nearby downy birch tree (Betula pubescens) – small protuberances sticking out from the trunk in various places. These were a new sight for me, and I thought they might be an unusual fungus.

I'd never seen these small shapes on the trunk of a birch tree before, and was puzzled as to what they could be.

I’d never seen these small shapes on the trunk of a birch tree before, and was puzzled as to what they could be.

 

 

 

 

 

 

 

However, when I sent some samples to Liz Holden, the mycologist who helps me with fungal identifications, she replied saying they were not a fungus at all, but were instead adventitious roots growing out of the tree’s trunk.

Another view of the 10-spot ladybird (Adalia decempunctata) on a young twig of a downy birch.

Another view of the 10-spot ladybird (Adalia decempunctata) on a young twig of a downy birch.

Looking at another birch tree nearby, I noticed a ladybird on some of the new shoots, so I stopped to take some photographs of it.

10-spot ladybird (Adalia decempunctata) on a young twig of a downy birch.

10-spot ladybird (Adalia decempunctata) on a young twig of a downy birch.

 

 

 

 

 

 

 

Winged adult downy birch aphid (Euceraphis punctipennis) and younger nymphs of the same species on the underside of a downy birch leaf.

Winged adult downy birch aphid (Euceraphis punctipennis) and younger nymphs of the same species on the underside of a downy birch leaf.

It was the 10-spot ladybird (Adalia decempunctata), which is a common species throughout the UK. Knowing that ladybirds are predators of aphids, I began searching the leaves of this birch, and very soon found some aphids on one of them. There was a large, slightly blue-ish winged aphid that I recognised as being the downy birch aphid (Euceraphis punctipennis), together with some smaller, wingless aphids which turned out to be nymphs, or an earlier life stage, of the same species.

IMG_2696 Black-kneed capsid bug (Blepharidopterus angulatus)

Black-kneed capsid bug (Blepharidopterus angulatus) on a leaf of the downy birch tree.

I looked at a number of other leaves on the tree as well, but didn’t find any more aphids, so I don’t know if I was just lucky with the first ones I searched, or whether there were more on other parts of the tree that I didn’t see. However, I did spot another insect of interest – a green bug or Hemipteran, which like the aphids, sucks the sap of plants and trees. This was identified for me by Joe Botting as being the black-kneed capsid bug (Blepharidopterus angulatus). Like the ladybird, it is a common species throughout Britain, occurring on various trees, including birch.

These alder trees (Alnus glutinosa) and ferns combined to create a good visual image of the lushness of the temperate rainforest.

These alder trees (Alnus glutinosa) and ferns combined to create a good visual impression of the lushness of the temperate rainforest.

Walking further along, I came to a group of alder trees (Alnus glutinosa) with their trunks covered in moss and some ferns growing at their base – together they formed a classic temperate rainforest tableau.

Another view of the alder trees.

Another view of the alder trees.

 

 

 

Galls induced by a mite (Eriophyes laevis) on a leaf of one of the alder trees.

Galls induced by a mite (Eriophyes laevis) on a leaf of one of the alder trees.

 

 

 

 

 

I had a quick look at some of the leaves on one of the alders and soon spotted some galls induced by a mite (Eriophyes laevis). This is another common and widespread species and the pustule-like galls are highly visible on the leaves, often bright yellow-green or even red in colour.

Galls induced by a midge (Dasineura ulmaria) on a leaf of meadowsweet (Filipendula ulmaria).

Galls induced by a midge (Dasineura ulmaria) on a leaf of meadowsweet (Filipendula ulmaria).

Just a few feet away from the alder, there were some meadowsweet plants (Filipendula ulmaria), so knowing that galls also occur on those leaves, I had a look at them. I felt like I was in ‘gall finding mode’, as almost immediately I saw some galls induced by a midge (Dasineura ulmaria) on one of the plants.

A closer view of the some of the galls induced by a midge (Dasineura ulmaria) on a meadowsweet leaf.

A closer view of the some of the galls induced by a midge (Dasineura ulmaria) on a meadowsweet leaf.

 

 

 

 

 

These galls look superficially similar to those on the alder, but midges of course are insects, whereas mites are invertebrates in the class Arachnida, along with spiders and ticks.

Hard ferns (Blechnum spicant) lined this small watercourse in the forest.

Hard ferns (Blechnum spicant) lined this small watercourse in the forest.

It’s interesting that these two very different and evolutionarily quite distinct organisms should induce similar-looking galls on unrelated plant species – alder and meadowsweet. In both cases, the galls provide protection and a food source for the mite nymphs and midge larvae respectively. This is an example of the phenomenon called convergent evolution, whereby completely unrelated species evolve similar traits or behaviours, in response to environmental or ecological factors.

Oak trees (Quercus petraea) with moss on their roots and branches - a typical feature of temperate rainforests.

Oak trees (Quercus petraea) with moss on their roots and branches – a typical feature of temperate rainforests.

Continuing further along, I came to another area with a number of large oak trees (Quercus petraea) so I left the trail and walked around in amongst them for a few minutes. It was a classic temperate rainforest setting, with lots of moss on both the trees and the rocks on the forest floor. There were also plenty of ferns, especially on the larger branches of the oaks, and I find the rich green vibrancy of these wet forests very pleasing to my eye, and also a good subject for photography.

img_2770

Bracken fronds and the moss-covered base of one of the large oak trees.

Another group of moss-covered oak trees, surrounded by bracken (Pteridium aquilinum).

Another group of moss-covered oak trees, surrounded by bracken (Pteridium aquilinum).

 

 

 

 

 

 

Detail of one of the oak trees, showing the ferns and moss growing on its trunk and branches.

Detail of one of the oak trees, showing the ferns and moss growing on its trunk and branches.

 

 

 

Like the cloud forests of the tropics, a temperate rainforest such as this has plenty of epiphytes growing on the trees. Whereas in a tropical forest those will be bromeliads and orchids, here the epiphytes are mostly mosses, lichens and ferns.

Wider angle view of the same tree, showing how much moss is growing on its branches.

Wider angle view of the same tree, showing how much moss is growing on its branches.

In both ecosystems though, those plants use the trees for support, but do not take any nutrients from them. Instead, they rely on the near constant atmospheric humidity for moisture, and airborne particles of dust and organic material to provide the nourishment they need to grow. These epiphytes also play a role in intercepting some of the rain that falls, absorbing it and thereby reducing the amount that reaches the ground.

Moss also grows on the trunks of the oak trees.

Moss also grows on the trunks of the oak trees.

Some of that moisture will later evaporate from the epiphytes, helping to maintain a high level of humidity in the local atmosphere, and creating optimal conditions for the continued growth of the epiphytes. Mosses that grow on the trunks of the trees also absorb some of the water that flows down the trunks in times of heavy rainfall, and the capacity of the epiphytes to soak up a large quantity of moisture reduces the likelihood of flooding.

As if to emphasise this, I came across a small stream, where the water was cascading over some rocks, and it was lined in part with a couple of different fern species, including hard fern (Blechnum spicant). The upright fronds of this are the fertile fronds, which release the fern’s spores – the majority of its fronds lie flat to the ground and are sterile, playing no part in the reproductive process.

Hard ferns (Blechnum spicant) and another fern growing beside cascades on a small in the forest.

Hard ferns (Blechnum spicant) and another fern growing beside cascades on a small stream in the forest.

The elegant curves of the fern fronds seemed to echo the flow of the water over the rocks.

The elegant curves of the fern fronds seemed to echo the flow of the water over the rocks.

 

 

 

 

 

 

img_2864

Closer view of the fern fronds and the cascading water.

 

 

Detailed view of the fertile fronds of the hard fern (Blechnum spicant) with the cascading water behind.

Detailed view of the fertile fronds of the hard fern (Blechnum spicant) with the cascading water behind.

 

 

 

 

 

 

 

By this time it was late in the afternoon and I was nearing the end of the circular trail in the forest. I’d read on the information leaflet about the reserve that Glasdrum is noted for the presence of a rare lichen, Norwegian specklebelly (Pseudocyphellaria norvegica), which can be seen on the trunks of hazel trees along the path, but I hadn’t found any of it yet.

Green satin lichen (Lobaria virens) (left) and another lichen (Pseudocyphellaria intricata) (right) on the trunk of a hazel tree.

Green satin lichen (Lobaria virens) (left) and another lichen (Pseudocyphellaria intricata) (right) on the trunk of a hazel tree.

When I came to an area with quite a few hazel trees growing beside the path, I began checking their trunks to see if I could spot this lichen. There was a photograph of it on the leaflet I’d picked up, so I knew what to look for, and fairly quickly I found a tree with a likely candidate lichen on it, growing next to some of the green satin lichen (Lobaria virens) that I’d seen earlier (in Part 1 of this blog). However, upon closer examination it didn’t look quite right, as the thallus (as the main body of a lichen called) didn’t have spots on it.

Another view of the patch of the lichen (Pseudocyphellaria intricata) on the moss-covered trunk of a hazel tree.

Another view of the patch of the lichen (Pseudocyphellaria intricata) on the moss-covered trunk of a hazel tree.

I was later able to get this species confirmed as being Pseudocyphellaria intricata by John Douglass, a lichenologist who very kindly helps me with identifications. Back on the trail though I soon found another lichen with spots on it, which I was sure was the Norwegian specklebelly.

Norwegian Specklebelly lichen (Pseudocyphellaria norvegica) amongst moss on the trunk of a hazel tree.

Norwegian specklebelly lichen (Pseudocyphellaria norvegica) amongst moss on the trunk of a hazel tree.

 

 

 

 

 

Another patch of the Norwegian specklebelly lichen (Pseudocyphellaria norvegica) amongst moss on a hazel tree.

Another patch of the Norwegian specklebelly lichen (Pseudocyphellaria norvegica) amongst moss on a hazel tree.

 

 

Because I knew what to look for, it was quite a distinctive lichen when I saw it, and there were several patches on some hazels that were growing beside each other.

Closer view of some of the Norwegian speckle belly lichen (Pseudocyphellaria norvegica).

Closer view of some of the Norwegian specklebelly lichen (Pseudocyphellaria norvegica).

 

 

 

 

 

 

The common name for this species is derived from the whitish speckles on the underside of its thallus, but it is the spots on the upper surface that are conspicuous and distinctive, as in the photos above. Most lichens do not have common or English names, including the other lichen in the same genus (Pseudocyphellaria intricata) that I found on some of the hazels, but this one has been given quite a descriptive name, because of its rarity, and that helps with remembering it.

Another photograph of the Norwegian specklebelly lichen (Pseudocyphellaria norvegica).)

Another photograph of the Norwegian specklebelly lichen (Pseudocyphellaria norvegica).

In recent years considerable work has been done to give English names to over 1,000 of the most common fungi that occur in Britain, and the same has been done for many of our moss species. A similar effort is much-needed for lichens, and I hope that someone will take on this task in the near future, as it will greatly assist in helping people to identify, and identify with, lichens.

Norwegian specklebelly is listed as Endangered on the European Red List of threatened lichens, and western Scotland, particularly Argyll, is recognised as containing the best populations of this species in the world. Like the tree lungwort (Lobaria pulmonaria) and green satin lichen (Lobaria virens) that I’d seen earlier in the day, it is a member of the Lobarion group of lichens, and is a key indicator species of Atlantic temperate rainforests of high conservation importance. Also like the lungworts, Norwegian specklebelly is a cyano-lichen, meaning that in addition to the fungus and alga that comprise all lichens, it also has a third partner in its symbiosis – a cyanobacterium (Nostoc sp.). Cyanobacteria absorb nitrogen from the air, fixing it into the thallus of the lichen, and when the lichen decays or falls to the ground, the nitrogen becomes available for other organisms. By doing so, the lichen adds natural fertiliser to the soil, and this process is an important and integral one in these temperate rainforest ecosystems.

Finding the Norwegian specklebelly was a fitting climax and highlight to what had been an excellent day of exploration in Glasdrum Wood. However, I’d only seen a very small part of its total area, so I’ll need to return another time to wander around in other parts of it, further afield from the visitor footpath. Meanwhile, here’s a compilation of some video footage that I took during the day:

Dramatic light and rainclouds looking across Loch Linnhe to Morvern, on my way back from Glasdrum Wood.

Dramatic light and rainclouds looking across Loch Linnhe to Morvern, on my way back from Glasdrum Wood.

Having started the day by leaving my home at 6 am, it was after 6 pm when I left Glasdrum for the 3 hour drive back to Findhorn, so it was a long trip overall. Shortly after departing from the reserve, the road passes through the village of Appin and reaches Loch Linnhe, the long sea loch that stretches northeast up to Fort William. When I reached the first viewpoint of the loch, there was some very dramatic late afternoon light, with shafts of sunlight shining through gaps in what looked like serious rain clouds. It had been dry for the entire time I’d been at Glasdrum, so this seemed like a fitting farewell gift from the day, with the rain for which the area is famous beginning to move in as I was leaving …

 

4 Responses to A day in Glasdrum Wood, Part 2

  1. John Lowry says:

    Reminds me very much of my time in Balquhidder last September and some of the trees I saw there by the old bridge. Beautiful to see. Spent several days there before heading to Glen Affric for my TFL conservation week. Thanks for the great pictures.

  2. David Scott says:

    Excellent post, as always, great photography. I love your attention to the small things, the aphids, the lichens. It’s all important.

    I read Richard Preston’s The Wild Trees recently. About the folk who climbed up into the coastal redwood canopy in California. The tree climbing provided most of the excitement, but the important of the lichens to the whole ecosystem was made clear as well. The author climbed up into the Scots Pine canopy while he was over on holiday, found many similarities. Bonsai Rowan trees growing out of pockets of soil in the older trees. Great book.

    • Hi David,

      Many thanks for your comment – I’m glad you enjoy my photography and blogs.

      Interestingly enough, someone we had here for lunch a couple of days ago was talking about that book by Richard Preston. I had the privilege of climbing with Richard into the canopy of Scots pines in Glen Affric when he came to Scotland, and he later wrote an essay for one of our annual

      Trees for Life Engagement Diaries

      I have a copy of his book, but haven’t read it yet, so the synchronicity of two different people mentioning it in 3 days is a sign that I should do so now!

      With best wishes, Alan

Leave a Reply

Your email address will not be published. Required fields are marked *