Saturday, 22 July 2017

Wet heath and blanket bog in the North West Highlands - a lifetimes passion

Blanket bog, with An Teallach in the background (the mountain NOT the beer!)
Blanket bog and wet heath cover vast areas of the the North West Highlands of Scotland. Many nationally scarce or rare species are associated with these areas, including plants, bryophytes, birds and dragonflies. They are often important communities in world terms because there is so much in Scotland and yet so little of it elsewhere in the world. I've spent a lot of time surveying these types of habitats over the past few years and this has really enhanced my knowledge and love of an area for which I already had a passion since my youth.  


Blanket bogs are amongst my favourite habitats, in fact in a professional capacity it's the habitat I enjoy surveying the most, they're just so interesting! Not only do they have a good range of fascinating plants, including bryophytes and orchids, they often have many surprises, such as in the case of this bog, a decent population of common lizards.


On the face of it blanket bogs are a rather bleak, bland and difficult terrain to survey, but look a little closer and it's a totally different story.


Work doesn't come much better than this, an NVC survey in the North West Highlands! The sun is shining, the views magnificent, the wind just strong enough to keep the midges away and a pint of the local brew An Teallach ale awaits in the pub below. Perfect! I love the solitude I get when I'm in these places, I can spend all day miles from the nearest person, and often there is an absolute silence only occasionally broken by the song of birds.


The vegetation of the two communities can be very similar and the differences subtle.  Often the vegetation alone is not enough to seperate them, so when surveying wet heath and blanket bog a stick or cane is an essential part of the surveyors kit. In general blanket bogs have a peat depth of >50cm whilst wet heath is less, so the cane is used to help get a rough idea of the depth of peat at each quadrat. In these areas, there's more to an NVC survey than just identifying the plants.


I use a home made quadrat, made from a broom handle sawn into quarters and a piece of washing line. It's much easier to carry than those newfangled fold up plastic things, and a fraction of the price! If whittling broom handles isn't your idea of fun, try using plastic tent pegs instead.


Sphagnums are amongst the most obvious species on most bogs and wet heaths, and the colours are breathtaking, rivaling any flowering plant.


Sphagnum papillosum is one of the commonest sphagnums in this area and is a good indicator species of a healthy and  active bog. This is one of the peat forming sphagnums.


Sphagnum capillifolium is another common species on both blanket bog and wet heath, in fact on the latter it can often be the only sphagnum present. Here growing with Hypnum jutlandicum.

Sphagnum affine, one of the rarer sphagnums on these bogs.

It's always exciting to find Sphagnum magellanicum, one of my favourite sphagnums. You really know that you're on a bog if you've got magellanicum, I've never yet found it on wet heath.


Sphagnum cuspidatum prefers very wet conditions and is usually found around the edges of pools and often growing directly in the water as in this case.


Sphagnum papillosum with a small patch of Sphagnum austinii.

Sphagnum compactum

Bog myrtle Myrica gale is always a pleasure to find, it is most common on blanket bog, but does also grow on wet heath. The leaves have a sweet smelling resinous aroma which when crushed underfoot adds a delightful fragrance to the moors.


Not snow but a cladonia covered blanket bog. Cladonia are a group of lichens, sometimes referred to as reindeer lichens, which can be very common on blanket bogs and wet heath, but this is just amazing, I've never seen such a high coverage of Cladonia, it really was as if the bog was covered in snow. This photo also shows another feature of blanket bogs, the deep peat hags. In places these can be above head height, and they can make for slow progress across the bog.



Cladonia portentosa is one of several very simlilar lichens.


This is neither snow nor Cladonia, it's hummocks of the moss Racomitrium lanuginosum.


Racomitrium lanuginosum one of the commonest non-sphagnum bryophytes on the bog.


The large heath butterfly is a species typical of these bogs. This individual had me confused for a while, because although it was clearly much larger than small heath, it looked considerably different to the large heath I am familiar with in the English South Lakes, which has much more distinct underside eyespots. However, this is large heath of the race Coenonympha tilla scotica, which occurs in Scotland north of a line from Clyde to Aberdeen. In this subspecies the eyespots are either faint or not present at all.



Bog asphodel Narthecium ossifragum is a very common and very welcome plant on these moors, in summer they have vivid yellow flowers and when they go to seed in autumn they are a beautiful orange colour. Despite the name, they can occur on both bog and wet heath.


Just a beautiful flower, bog asphodel, a member of the lilly family.


Cross-leaved heath Erica tetralix, grows in wetter conditions than its cousin bell heather Erica cinerea which is an indicator species for dry heath.


Ling Calluna vulagris is the commonest heather on these moors, it prefers slightly drier conditions than Erica tetralix. The coverage and mix of the ericoids (heathers) combined with the sphagnum assemblage is a crucial factor in determining the health of a bog.



Eriophorum angustifolium, common cottongrass.


Greater sundew Drosera anglica, also known as English sundew, is a plant which grows almost exclusively in Scotland and a few parts of Wales. 




Chickweed wintergreen Trientalis europaea


Heath spotted orchid Dactylorhiza maculata is by far the commonest orchid of these moors, but there are others which are worth keeping an eye open for. 



Lesser twayblade Neottia cordata is more than a tiny version of its larger cousin common twayblade Neottia ovata, it is in fact a much more beautiful orchid. Lesser twayblade is a plant of wet heaths rather than bogs.



Lesser twayblade Neottia cordata.



Lesser butterfly orchid Platanthera bifolia. I never fail to be surprised when I come across this orchid in the middle of a bog. It's not common in such habitat, but one or two plants can occasionally be found.



Now this is a really special find, Scottish asphodel Tofieldia pusilla. Compare the size of the leaves to those of bog asphodel in the background and you can see why it can be such a hard species to connect with. It's found in many parts of the Scottish highlands, and also bizarrely in Teesdale in Northern England, but it is never common anywhere in my experience.


Purple spoonwort Pleurozia purpurea a type of liverwort that can cover quite large areas in flushes.


Dwarf birch Betula nana occurs almost exlusively in the UK on blanket bog and wet heath in Northern Scotland.



Alpine bearberry  Arctostaphylos alpina, another mountain species which occurs in the UK exclusively in Scotland.



Cloudberry Rubus chamaemorus


Crowberry Empetrum nigrum  


Cowberry Vaccinium vitis-idaea


Common cow-wheat Melampyrum pratense


Field gentian Gentianella campestris, not really a bog species but grows rarely on acidic grasslands adjacent to bogs. I found this growing at the side of a road which cut right through the centre of the bog!



Northern bedstraw Gallium boreale, again not a bog species but occasionally found growing along the sides of streams which run through the bog.



It can be hard work, often the weather is poor, sometimes it's a long walk to the survey site, but I love it and I'm always learning when I survey these areas, there's always something new and unexpected.


Some blanket bogs, such as this one at Bridge of Grudie, Loch Maree, have some really special invertebrates.


This is the rare Northern Emerald dragonfly at Bridge of Grudie, which in the UK is only found in northern Scotland. Azure hawker also occurs here but unfortunately it has so far eluded me!


Large lochs in this area such as Loch Maree hold important populations of Black-throated diver, though the slightly commoner red-throated diver is perhaps the true diver of blanket bogs because it prefers smaller lochs often right in the heart of the bog.



Since I was last in the highlands I've developed a passion for hoverflies, and it was an added interest this time to see what I could find. This is the impressive Sericomyia silentis, a species which I have seen before, even at Pennington Flash, Greater Manchester, but only in very small numbers. Here in the North West Highlands it is about the commonest of the larger hoverflies at this time of year on bogs and heaths.


This is another impressive species, one of a group of five which are difficult to seperate, this is Chrysotoxum arcuatum at Loch Maree. There are several features which seperate this species from the other four, including the length of the third antennal segmant which is longer than the combined lengths of the first two segments, but range also seperates them in this case. The other four don't really occur much further north than the English midlands, a good 450 miles south of here. Even for Chrysotoxum arcuatum this is about as far north as it occurs in the UK.


I've no idea what this is, but it was growing extensively in a stream which ran through a bog.


Viviparous sheep's-fescue Festuca vivipara. This is closely related to sheep's fescue Festuca ovina but differs in that it has viviparous flower heads (lots of 'baby plants') rather than flowers.

 
Purple moorgrass Molinia caerulea, far and away the commonest grass on these bogs, in places it can completely dominate to the exclusion of most other plants, when it is known as molinia mire. Too much molinia can be a sign of a degraded bog. Thankfully it does not dominate the majority of the North West Highlands.......


The end of a perfect day!

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