Upland peatlands - vegetation and habitats

What I believed was going to be a straightforward overview has instead turned into a learning curve penetrating the syntax of ecologists describing upland peatlands. It will be some time before 'soligenous mire' finds itself into the vernacular of hill walkers.

Bog cotton - Eriophorum vaginatum

In the UK plants have common names that vary from region to region and a scientific name, the common names are usually succinct, whilst the scientific name is usually not so succinct and in the dead language of latin. A common sedge of upland peatlands has the scientific name Eriophorum angustifolium which will mean little to many people who frequent the uplands unlike its common names: cotton-grass, cotton-sedge and bog cotton. The problem is that another common sedge of upland peatland is Eriophorum vaginatum has cotton like spikelets and a number of common names: tussock cottongrass, hare's-tail cottongrass, sheathed cottonsedge and bog cotton. Another common plant is Vaccinium myrtillus commonly known as blaeberry, blueberry, whortleberry, whimberry, whinberry and bilberry.  So to avoid confusion in this blog post I'll use the common plant name that I am familiar with and the scientific name italicised in brackets.

Wild camping in a bog - Moelwyns, Wales

Anyone who has wild camped in upland peatlands will be acutely aware of the tussocky nature of the vegetation, the benefits of long tent pegs, the enhanced comfort of an inflatable matt a couple of inches thick and the exponential increase in potential pitch sites if a tent incorporates a bathtub floor. The length of night between the Autumn and Spring equinoxes at higher latitudes, allows for plenty of reflection on the wisdom of gear purchases, choice of tent pitch and vegetation discomfort level.

Upland peatland ~ Arenigs, Wales

The image above illustrates the colour palette of an area of the Arenigs in autumn with vegetation identified by its autumnal colour: red patches signify bog cotton (Eriophorum angustifolium), the pale straw coloured patches are a tussock forming matgrass (Nardus stricta), on the image right is a crescent of yellow/green bog mosses (Sphagnum spp.) and the lower third of the image has a 'textured' appearance the colour of brown mustard indicating purple moor-grass (Molinia caerulea) another tussock forming grass. The white dots are sheep in single file ascending an historic animal track that follows the line of least resistance.

Deergrass (Trichophorum cespitosum) and Purple moor-grass (Molinia caerulea)  ~ Moidart, Scotland

The British National Vegetation Classification (NVC) is a ‘phytosociological’ classification solely on the basis of the plant species and no consideration is given to other site factors, although the NVC  recording form does include some site factors. Nonetheless it does serve to highlight the mosaic of vegetation communities and below are three illustrations taken from "An illustrated guide to British upland vegetation" where M = Mire. H = Heath. MG = Mesotrophic grassland U = Upland

Screen shot from An Illustrated Guide to British Upland Vegetation (2004) Averis, A., Averis, B., Birks, J., Horsfield, D., Thompson, D., & Yeo, M.,

Screen shot from An Illustrated Guide to British Upland Vegetation (2004) Averis, A., Averis, B., Birks, J., Horsfield, D., Thompson, D., & Yeo, M.,

Screen shot from An Illustrated Guide to British Upland Vegetation (2004) Averis, A., Averis, B., Birks, J., Horsfield, D., Thompson, D., & Yeo, M.,

From the laymans perspective the dominant vegetation of upland peatlands in the UK are in alphabetical order:bilberry (Vaccinium myrtillus), deergrass (Trichophorum cespitosum), heather (Calluna vulgaris), matgrass (Nardus stricta), purple moor-grass (Molinia caerulea),  bog cotton (Eriophorum angustifolium / Eriophorum vaginatum) and bog mosses (Spaghnum spp.). From a practical perspective the vegetation is an indicator of how slow and character building the walking will be, as one author was moved to write:

"These are the wet grasslands that can make walking in the hills of Wales, Galloway and the western Highlands and Inner Hebrides so wearisome. The tall dense tussocks of Molinia caerulea, with long leaves blown into waves by the wind and rain, conceal a treacherous network of peaty channels and in some places small winding streams"

So the vegetation of upland peatlands can be a mosaic of vegetation communities, but at least there is agreement on some of the communities. Describing habitats in upland peatlands are more of a challenge. In the classic text 'Mountains and Moorlands' published in 1950, the introductory sentence to the chapter on 'Moorland and Bogs' was:

There is no good definition of moors and moorland. 

And there is still no exact definition today. The general consensus is that moorland is an uninhabited area of uncultivated infertile upland and the google street views below from Exmoor, Rannoch Moor and the Denbigh Moors, do support that consensus.



There are a seeming plethora of names given to habitats found in upland peatlands - valley mire, blanket mire, blanket bog, blanket peat, bog pool, wet heath, heather moor, bilberry moor, sedge moor, grass moor, upland grassland, wet grasslands, upland wetlands, topogenous mire, soligenous mire, ombrogenous blanket bog, lagg fen ... The situation is summed up by the National Biodiversity Network Habitats Dictionary which has this to say :

"Habitat classification is not like species classification. There is no clearly agreed ‘taxonomy’ and many different systems have been developed, often independently of each other and for different purposes. Although botanists have been classifying vegetation for the past century, habitat classification, which builds on the system of European vegetation classification so as to include abiotic features of the habitat, is a relatively new development. 

The need for a classification has several driving forces:

• establishment of habitat protection legislation

• inventory of habitats in a country, region, or site

• biodiversity monitoring and reporting

• or description of a species’ habitat requirements

Habitat classification systems which are scientific, unambiguous and easy to use are therefore required."

However after more syntax it finishes:

"The NBN Habitats Dictionary is currently unavailable."

So at that point it's probably best to await developments. The next post on upland peatlands will cover landscape photography and the issue of photogenic and photographic uplands.

Upland peatlands in the Arans ~ Wales

Upland peatlands - The current state of vegetation and blanket bog

Peat can be sampled and then analysed in a laboratory for pollen, leaves, seeds, roots, stems, insects, charcoal, tephra and radiocarbon dated by scientists to elucidate an environmental and ecological history. It appears that vegetation communities currently growing on peatlands may be unrepresentative of the vegetation communities that formed peat in the past. Two research papers that sampled and investigated peat vegetation in Wales produced compelling evidence to support the change in vegetation growing in upland peatlands.

Mynydd Llangattock ~ Wales

Palaeoecology of degraded blanket mire in South Wales: Data to inform conservation management

Abstract: Many European blanket mires are degraded and contain few Sphagna. In Wales, more than half exhibit symptoms of degradation. We used palaeoecological techniques to chronicle recent vegetation history at two upland localities in South Wales to provide an understanding of the contribution of various factors in mire degradation and to aid wider conservation management strategies. The data suggest a major vegetation change post-dated the start of the industrial revolution. There was evidence for increased burning activity, but as this phenomenon was not present in all profiles it seems unlikely that fire was the principal or sole agent in vegetation change. Rather, increased atmospheric input, plus a change in grazing pressure, may have been responsible. The implications for conservation management are far-reaching. The present overwhelming dominance of Molinia at Hirwaun Common is unprecedented. So also is a local dominance of Calluna, shown in one area at Mynydd Llangatwg. Hence, the approbation often accorded to Callunetum needs to be tempered with the knowledge that its presence in the Mynydd Llangatwg landscape is not long-standing. Indeed, millennial-scale dominance of Sphagnum imbricatum characterizes the earlier record. Its demise and that of Drosera intermedia took place in historical times. Both localities show floristic impoverishment within the 20th Century, with relatively recent single-taxon supremacy. So, conservation management to reduce the current pre-eminence of Molinia would not run counter to long-established dominance; ways to achieve this are suggested. The methods used in this study have wide applicability in mire conservation. 

Frank M. Chambers, Dmitri Mauquoy, Andy Gent, Freya Pearson, John R.G. Daniell, Peter S. Jones, Biological Conservation, Volume 137, Issue 2, 2007, Pages 197-209, ISSN 0006-3207, http://dx.doi.org/10.1016/j.biocon.2007.02.002.

View south from Drygarn Fawr over the Elenydd peatlands ~ Wales

Recent vegetation history of Drygarn Fawr (Elenydd SSSI), Cambrian Mountains, Wales: implications for conservation management of degraded blanket mires 

Abstract: Many areas of blanket mire in Britain display apparently degraded vegetation, having a limited range of ericaceous and Sphagnum species. Data are presented here from Wales from the upland locality of Drygarn Fawr (Elenydd SSSI), which is dominated overwhelmingly by Molinia caerulea. Palaeoecological techniques were used to chronicle vegetation history and to determine the nature and timing of vegetation changes, as an aid to devising conservation management and restoration strategies. Although for the past 2000 years the pollen and plant macrofossil data indicate some evidence for cyclic vegetation change, they demonstrate that here the major vegetation change post-dated the start of the industrial revolution. The palaeoecological data show a greater proportion of Sphagnum than currently. Local extinction of some species (e.g., Myrica gale) apparently took place in Medieval times, but most of the degradation and floral impoverishment apparently occurred during the 20th Century. The implications for conservation management are far-reaching. The overwhelming dominance of Molinia is clearly unprecedented. While it was locally present for hundreds of years, some factor(s)—possibly a change in grazer and grazing regime—encouraged its recent ascendancy in the 20th Century. Consequently, any management attempts to reduce the pre-eminence of Molinia would not be countering an ingrained, long-established dominance. It is suggested that investigation of degraded blanket mires elsewhere by historical and multi-proxy palaeoecological techniques—through multiple, dated cores to track species extinctions and directional vegetation changes—would help ascertain previous mire floras and so indicate a range of restoration targets for mire vegetation. 

F. M. Chambers, D. Mauquoy, E. W. Cloutman, J. R. G. Daniell, P. S. Jones Biodiversity and Conservation September 2007, Volume 16, Issue 10, pp 2821–2846https://link.springer.com/article/10.1007/s10531-007-9169-3 

Across the UK peat has been sampled and a picture has emerged of mire vegetation change in some regions as a response to a combination of postulated factors i.e drainage, air pollution, grazing intensification, grazing regime change, afforestation, climate change and other factors.

Hill ponies and sheep grazing on Gwaun Cefnygarreg ~ Wales

Across the UK there are a number of projects actively restoring degraded peatlands and the following two videos outline a project funded by the EU LIFE-nature programme restoring two areas in North Wales.





The International Union for the Conservation of Nature (ICUN) Peatlands Programme has produced a booklet "UK Peatland Restoration - Demonstrating Success" and is well worth a read. The next post will look at the vegetation and habitats in the UK upland peatlands.

Upland peatlands

The first in a series of posts covering the 'peatlands' in the uplands of the UK.

Peatland in the Brecon Beacons National Park

A generally accepted definition of what constitutes an upland in the UK is the uncultivated land above 250m - 400m in England and Wales, whilst in Northern Ireland and Scotland upland environments can occur at lower elevations. A relief map of the UK is one way of visually representing the distribution of uplands.

Relief map of the UK
By Captain Blood - Own work, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=930331

A case could also be made for visually representing uplands by climatic criteria.

http://www.metoffice.gov.uk/public/weather/climate

Wind

http://www.metoffice.gov.uk/public/weather/climate

Rainfall

http://www.metoffice.gov.uk/public/weather/climate

Days of rain

http://www.metoffice.gov.uk/public/weather/climate

Mean Maximum Temperature

http://www.metoffice.gov.uk/public/weather/climate

Mean Minimum Temperatures

http://www.metoffice.gov.uk/public/weather/climate

So on average the UK upland climate is cool, windy and often wet. The rain falls onto ground underlain by predominantly impermeable bedrock lithologies and that causes at least seasonal waterlogging of the overlying soil layer. Water saturated soils create anaerobic conditions and low temperatures reduce biological activity slowing down the rate of organic material decomposition. Once a threshold is passed for low temperature/months of soil waterlogging, organic material starts to accumulate in soil.

View uphill of an exposure of blanket peat and minerogenic surface from fluvial erosion on a moderate hill slope ~ Mynydd Du, Brecon beacons National Park.

Unsurprisingly the uplands also reveal their presence on a soil carbon map.

Ostle, Nicholas & Levy, Peter & D. Evans, C & Smith, P. (2009). UK land use and soil carbon sequestration. Land Use Policy 26:S274-S283. Land Use Policy. 26. . 10.1016/j.landusepol.2009.08.006.

Comparing the organic carbon content of the UK upland soils to European soils highlights their significance and explains why so many walkers in southern Europe wear fabric walking boots.

There are numerous descriptions of what constitutes a peatland in press - varying minimum depths of peat, satisfying a varying minimum criteria of % carbon content covering a minimum area of land. The International Union for Conservation of Nature, UK Committee have taken a pragmatic approach and define it simply as:

Peatlands are areas of land with a naturally accumulated layer of peat. These are formed under waterlogged conditions from carbon rich, dead and decaying plant material. 

The next post will concentrate on the vegetation and habitats that cover upland peatlands.

Rannoch Moor