Culag Wood re-visited
In 1994 five members of the Field Club produced a Nature Trail for Culag Wood, with an A3 printed guide to 15 stopping points with numbered posts (photos 1-2). At that time, one of us (IME) thought he knew the Wood quite well.
We have visited the Wood many times since, but it wasn’t until last autumn that we systematically walked all its paths in connection with the revision of the Forest Plan. Some of these paths did not exist in 1994.
It is an intriguing place, since the native broad-leaved woodland on its crags and scree was augmented during the 19thand 20th centuries by extensive plantings of non-native species, both conifers and broad-leaves. The resulting variety of trees supports, amongst other things, a wide range of fungi and related organisms, with a species list running into three figures.
This article is based on a virtual presentation via ‘Zoom’ to the Field Club on 18th March 2021, and illustrates features of interest we came across in seven visits from October 2020.
A surprise on this first visit was the local abundance of old hazel stools, especially on the School Path, often regenerating well from the base (photo 3).
Downy birch Betula pubescens is an abundant native species, whose old stems support a number of wood-rotting fungi, such as this birch woodwart Hypoxylon multiforme (photo 4).
The top of the Viewpoint Path offers good panoramic views, and in the autumn, flowering bushes of western gorseUlex gallii (photos 5-6), at its only known site in Assynt, where it was first recorded in 1929. The prickles are softer than common gorse U, europaeus and there are small differences in the flowers. Western gorse only flowers in the autumn, whilst the other flowers all year round, although most abundantly in the spring.
We gathered some fallen leaves from a tall lime on the White Shore Path (together with those of an oak and a beard lichen) to check their identity (photo 7). They proved to be the frequently-planted hybrid common limeTilia x europaea. Tiny black dots on them were identified by Bruce Ing as the fruiting bodies of an ascomycete fungusGloeosporium tiliae, which is specific to limes and was ‘new’ to Assynt. We also noted the large funnel-shaped fruiting bodies of the gill fungus known as The Goblet Clitocybe cyathiformis (photo 8).
A visit to the White Shore revealed old leaves of primrose Primula vulgaris mined by the larvae of a fly Chromatomyia primulae (photo 9). We first noticed these leaf-mines on 4th November beside the Allt na Claise (see article), but did not realise they had not previously been recorded from north-west Scotland.
Members of the Board of Directors of the CCWT, suitably distanced, toured parts of the Wood on this date. Chris Goodman took us to an area just off the Main Track to the Car-park, where we found several non-native trees previously unrecorded from the Wood (photo 10). There was a sweet chestnut Castanea sativa, and fallen leaves of silver birch Betula pendula, typically triangular with double-toothed margins. This species only occurs in the west as a planted tree; our native species is the above-mentioned downy birch.
There was also a rather straggly conifer with leaves giving off a faint smell of oranges, obviously not the abundant Sitka spruce and European larch. A sample twig was run through keys later and proved to be Douglas fir Pseudotsuga menziesii, originally from the west coast of North America.
Whilst using a microscope to count the parallel rows of stomata on the underside of the needles, lines of tiny black dots were noticed (photo 11). These were identified as the fruiting bodies of another ascomycete fungus specific to Douglas fir, Phaeocryptopus gaeumanii, which causes a condition known as Swiss Needle Cast. Its spores enter the tough-skinned needles through the stomata, colonise the interior and then fruit through the points of access, hence the alignment. There were, again, no previous records from the north-west.
The tour finished in an open area near Billy’s Path, where fallen spruces had been cut up, resulting in a huge pile of wood chips and sawdust (photo 12). This was speckled with abundant orange sporangia of a slime mould Trichia decipiens (13). Although slime moulds or myxomycetes are often studied by mycologists, they are actually more closely related to protozoans than fungi.
On a walk along Anna’s Path which runs parallel to the western shoreline of the Wood (photo 14), we noted a fine display of the green satin lichen Lobaria virens on a sheltered gneiss outcrop (photos 15-16). This is one of the four British species of large lungwort lichens, all of which occur in the Wood. Lichens are also fungi, but ones in a shape-shifting symbiotic partnership with algae or other photosynthetic organisms.
Another unfamiliar if tiny ascomycete fungus was found by Gwen on Billy’s Path some two months later (photo 17). It is called Leptotrochila prunellae and lives within the old leaves of self-heal Prunella vulgaris which grows along the woodland paths. This fungus produces its tiny black fruiting bodies on the upper surface of the leaves (photos 18-19). Bruce Ing describes it as infrequent and it appeared, again, to be ‘new’ to Assynt.
And just to show that we don’t have our eyes down all the time, a reminder of the autumn glories of beech Fagus sylvatica (photo 20). It is another of the planted additions to the trees of Culag Wood, which does surprisingly well on rocky soils around Lochinver, and also adds greatly to the diversity of mycorrhizal fungi.
A miscellaneous collection of observations, and some might say – so what? Well, a leisurely walk, with eyes skinned for anything new, either to us or the site, is our idea of fun. The colours and patterns, even of familiar subjects, can be exquisite. We also get a glimpse of the wondrous and almost infinite layers of intricacy, diversity and inter-relationship that make every natural system unique. And that’s just those organisms large enough to be visible to the naked eye. Culag Wood re-visited? Never often enough!
Ian M. Evans and Gwen Richards