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

Latitude and light envelopes

The graph below illustrates the solar elevation and azimuth for 56 degrees north and has some profound implications for landscape photography at that latitude. Sunrise on the summer solstice will illuminate north east facing subject matter and sunset on the winter solstice will illuminate south west facing subject matter.

Illustration for a point 56 degrees North
By Deditos (Own work) [CC BY-SA 4.0 (http://creativecommons.org/licenses/by-sa/4.0)], via Wikimedia Commons

A look at the solar elevation for the summer solstice on the 56th parallel suggests the camera will not be required for much of the day, unless some 'weather' puts in an appearance. However on the winter solstice there is nearly 7 hours of daylight and a maximum solar elevation of ~10 degrees, which means there is theoretically photogenic lighting all day. But what about the rest of the year?

Copyright https://www.esrl.noaa.gov/gmd/grad/solcalc/

The US National Oceanic and Atmospheric Administration has an excellent solar calculator for investigating the potential of a locations light envelope. Some user interaction is required, but the time window of the 10 degree solar elevation can be gleaned and the azimuth of the 10 degree elevation established. It's a sad reality that many locations will never be illuminated by light at the extremes of the day but can be illuminated by photogenic light when the sun clears whatever it is that is masking sunrise/sunset and the NOAA solar calculator in conjunction with maps is a useful aid in determining when that might happen. Twilight duration can also be investigated by entering times before/after sunrise/sunset and noting the negative value of solar elevation.  I've used it for a number of years and have no hesitation in recommending it.

Nic photographing in the Graian Alps ~ 30th June 2014

The vagaries of upland weather

The last two trips have perfectly illustrated why it's best to adopt a phlegmatic approach to landscape photography. The first one Nic accompanied me to Y Mynyddoedd Duon (Black Mountains) and a walk up onto and along the Ffawyddog ridge. The walking was enjoyable in warm sunshine with a cooling breeze, heather moorland in bloom and natures larder of bilberries were deliciously sweet.

It became apparent the area encompassed by the Ffawyddog ridge, Vale of Ewyas and Hatterall ridge was a magnet for clear skies, whilst trains of photogenic cloud formations rolled in from the NW further east and to the west over the Gaider Fawr ridge.

Photogenic cloud

I have no great enthusiasm for landscape photography with overhead clear blue skies due to their propensity to drain colour from a landscape and whilst black and white photography would rescue some images it holds no interest for me. When I belatedly decided to explore the moorland vegetation with a macro lens, the wind increased in strength and as sunset drew near a visibly long bank of slow moving cloud appeared to the NW that would mask the best light. The last of the sunlight was utilised for an image of photogenic cloud and then the walk back to the car unassisted by head torch light. The lack of any sunlight on distant hills confirmed the early departure was a wise decision.

The second trip had a rather enticing weather forecast of heavy showers and spells of sunshine with the wind from the SW or the distinct possibility of heather moorland illuminated by fleeting light under stormy skies and the chance of a rainbow. Except the cloud never broke up, towards dusk the rain squalls were heavy and persistent. To be fair the wind strength was spot on with winds of 30 mph (Strong breeze/near gale) and gusts to 40 mph (gale force intensity). The weather and exposed location meant I was relieved to have packed the winter jacket, over trousers and gloves.

Calluna vulgaris and Ulex Gallii

Photography ambitions were restricted to leeward ground and then ground level macro photography before rain curtailed this activity. Chatting to a hill walker descending from a nearby summit it seemed that further south, the cloud was breaking up and sunlight breaking through, this kept me enthused until it became apparent with sunset approaching that this trip would also be curtailed. So two successive trips made where the landscape photography rewards would have been very good if the locations chosen were just a couple of miles distant, c'est la vie!

A trip to a heather moor.

The flowering of heather (Calluna vulgaris) marks the end of a self imposed break from visiting the hills in Wales as the welcome addition of purple hues to the vegetative colour palette of greens and yellows transforms the uplands in late summer.

Eventually a number of weather forecasts aligned to give some confidence to what the weather might be and importantly the words 'excellent visibility' and 'cloud breaking up' were prominent.  The one downside was the wind strength of a northerly 'fresh' to 'moderate' breeze that would induce vegetative movement, although a positive would be the suppression of the resident winged insect population. Suitably inspired and motivated an excursion was made to the National Trust property Mynydd Pen-y-fâl an outlier of Y Mynyddoedd Duon (The Black Mountains) in the Brecon Beacons National Park.

Harebells (Campanula rotundifolia)

The ascent route wasn't the planned one, but the convenient one due to the bracken (Pteridium aquilinum) growth. The relatively low winds, increased warmth and sunshine that characterised the early summer of 2017 were optimal for bracken growth and in places exceeded over 2.0 metres in height. However the weather subsequently reverted to the heavy rain and high winds that have afflicted recent summers in the UK. The adverse weather had collapsed the bracken, obscuring the minor paths, necessitating taking a well trodden route to the hills. The consolation of which was chancing upon a colony of Harebells by the side of the track under bracken.

Heather (Calluna vulgaris) and Bilberry (Vaccinium myrtillus) re-colonising a burned area of moorland.

With height gained the bracken covered slopes changed to open moorland and by mostly keeping to vehicle and sheep tracks, footfall was minimised on the vegetation. The moorland is actively managed for conservation by creating a mosaic of varying aged vegetation, the methods employed appeared to be controlled burning and in the absence of charred material on the ground presumably by cutting or flailing. Whilst heather dominated the moorland vegetation there were areas where other plant communities also put in an appearance : Western gorse, bilberry, grasses, rushes, sedges and bracken.

Western Gorse (Ulex gallii), Bilberry (Vaccinium myrtillus) and wind blown Wavy hair grass (Deschampsia flexuosa)

Eventually the cloud started to break up and allowed some welcome sunlight to play over the landscape.

The one downside of the location at this time of year is the curtailing of last light by the main bulk of the Black Mountains massif and the last of the direct sunlight was used on a less exposed area of moor with a mosaic of moorland vegetation modified by conservation management.

The wind negated any dusk twilight photography and a revisit will be made at some point in less windy conditions.

Wood of the Waterfalls

The mountain forecast indicated cloud and low hill fog, Nic fancied waterfalls and recent heavy rainfalls would ensure some photogenic water flows so a trip was made to Coed y Rhaeadr. The area provides an insight into fluvial geomorphology with steep sided ravines cut through bands of shale/siltstones/sandstone and floored by more competent sandstone. The geology is also responsible for the prevalence of waterfalls with rock competence and faults dictating their individual nature. The first photography stop was at Sgwd Ddwli Uchaf on the Nedd Fechan, where the first Dipper was seen.

Sgwd Ddwli Uchaf

Then a wander down to the confluence with Afon Pyrdin, where water levels indicated that a visit could safely be made to Sgwd Einion Gam a destination reached by a number of unassisted river crossings.

Sgwd Einion Gam

Sgwd Einion Gam

The area also falls within the Coedydd Nedd a Mellte Special Area of Conservation designated for sessile oak woods and ravine woodland, with the topography, underlying geology and superficial deposits determining the mixture of trees in the woodlands.  With the trees in leaf small leaved limes were evident and took the form of derelict coppice stools of some age. The area has a moderately oceanic climate that combined with a closed tree canopy and high levels of humidity, provide a habitat for bryophytes and ferns. Both oak ferns and beech ferns were present along the banks of the Afon Pryddin.

Oak ferns (Gymnocarpium dryopteris)

Beech ferns (Phegopteris connectilis)

A carpet of enchanter's nightshade also indicated the habitat of a closed woodland canopy and moist soil conditions.

Enchanter's nightshade (Circaea lutetiana)

The trip was a rewarding one, with plenty of interest along the way and further insights gained into the flora and landscape.

Shades of green

Persistent rain and almost negligible wind provided the necessary inspiration and motivation for a late spring photography trip to a scowles woodland. Whilst I have written about the benefits of rain wetted surfaces elsewhere in this blog, an additional bonus of heavy rain is the dampening effect on the surprisingly large and diverse resident population of biting insects, that would have otherwise made photography purgatory.

The tree species tally was impressive : beech (Fagus sylvatica), oak (Quercus spp.), ash (Fraxinus excelsior), cherry (Prunus avium), rowan (Sorbus aucuparia), wych elm (Ulmus glabra), holly (Ilex aquifolium), yew (Taxus baccata, field maple (Acer campestre), hazel (Corylus avellana),  hawthorn (Crataegus spp), birch ((Betula spp.), large leaved lime (Tilia platyphyllos), small leaved lime (Tilia cordata) and wild service (Sorbus torminalis). Some trees were derelict coppice stools of considerable girth indicative of a long life span.

Having exhausted my supply of dry micro fibre towels, I made my way back to the car and chanced upon a Greater Butterfly Orchid, the first I have ever seen in a woodland and the end to a satisfying outing.