Bogs and Wetlands Dartmoor Factsheet

Sphagnum mosses - This remarkable group of mosses Anybody who walks on Dartmoor will be owe many of their special qualities familiar with the bogs and mires of the high to their cellular structure. Their cell walls enable the plant to absorb moor. These wet areas are notorious and and hold copious amounts of water. crop up in many Dartmoor stories, the most This helps create the water-saturated famous being the Hound of the Baskervilles. environment it needs Sphagnum The legends emphasise the dismal, dangerous to grow. It grows in moss and evil smelling qualities of the bogs. clumps and has no roots. The truth is somewhat different. There are twelve known If you consider that Dartmoor consists species on Dartmoor, of impervious granite and combine each indicating that with the high rainfall that an slightly different upland area attracts, it is not surprising conditions. They vary that much of Dartmoor is wet underfoot. in colour from red to green; each However, high rainfall and granite rocks alone species have different do not explain why there are bogs and mires Sphagnum moss requirements such as levels on the moor. To create these habitats you of acidity and moisture. They also vary in their ability also need the remarkable sphagnum mosses. to colonise new areas. The plant has been much used This is a small absorbent plant that causes for its absorbent and cleansing properties. The Vikings water logging and stops dead plant matter used it as toilet paper, the Eskimos used it for nappies from breaking down. Over many hundreds of and on Dartmoor they collected it as wound dressings years the accumulation of dead moss and any during the First World War. associated plant matter creates a layer of peat that is found over most of the higher parts of The four wetland habitats (as defined in Dartmoor. Where this layer becomes thick The Nature of Dartmoor: A Biodiversity (more than 0.5m) and extensive, the habitat Profile) included in this factsheet are: produced is known as blanket bog. blanket bog, valley mires, rhôs pastures and wet woodland.

Wetland habitat locations on Dartmoor Blanket bog

Wet Valley mire woodland Rhôs pasture

Dartmoor National Park Authority Bogs & Wetlands Factsheet September 2004 Page 1 of 6 Blanket Bog Blanket Bog structure Blanket bog is made up of 85% water This is the term given to the mantle of peat Bog which covers the central parts of the higher asphodel north moor centred on Cranmere Pool and the south moor centred on Naker’s Hill. Sphagnum There are about 120 square kilometres of Sundew blanket bog on Dartmoor and these areas are recognised as being of international importance. Great Britain contains about 10-15% of the global resource. Even though Dartmoor contains a relatively small area of blanket bog, it is the most southerly in Britain and there is very little further south in Europe.

Acrotelm (Top layer“the living” skin of blanket bog) Normally no more than 30 cm deep Upright stems of sphagnum mosses - majority still alive

Catoelm (Lower peaty layer of blanket bog) 30cm to many metres deep Amorphous, chocolate-covered mass of dead sphagnum fragments, nearly always waterlogged

There has been a growing awareness of the importance of blanket bog as a holder of water, a vital natural resource as well as an appreciation of its role as a ‘carbon sink’ or carbon reservoir.

The Characteristic wildlife of blanket bog Factors affecting the habitat ● Deer Grass ● Hare’s-Tail Cotton Grass ◆ Much of the blanket bog has been ● Round-leaved Sundew degraded by uncontrolled burning, ● Cross-leaved Heath especially in the summer. Burning removes ● bog mosses the top layer of moss, damaging the living skin of the bog. Special species ● Golden Plover ◆ Breeding Dunlin and Golden Plover ● Dunlin numbers are declining, possibly because ● Crowberry of changes in the vegetation and climate, ● Sphagnum imbricatum and disturbance by recreational users. ◆ Acidification by acid rain may be a cause for concern.

Conservation objectives

▲ To reverse degradation of the blanket bog Golden plover by providing the stable conditions necessary for its recovery.

▲ To maintain populations of breeding Golden Plover and Dunlin.

Dartmoor National Park Authority Bogs & Wetlands Factsheet September 2004 Page 2 of 6 The history of the blanket bog Valley Mire

About 10,000 years before present (BP) most Valley mires are areas of waterlogged, deep of high Dartmoor was covered with oak and peat in valley bottoms, with characteristic acid hazel woodland* with some small patches wetland plant communities. Dartmoor has of open heath land around the highest tors. many of them, following the rivers and By the Mesolithic period (8,000 BP) human streams that drain the moor. At about 300 activity appears to have started to change metres above sea level, they often occur as this landscape. Burning was used to clear basin mires, often in newtakes (for more the edges of woodland to encourage foraging information see the Farming on Dartmoor animals like deer for hunting. This enabled factsheet). Mires on Dartmoor are sometimes small patches of blanket bog to expand into associated with old tin streaming works, the heath and wet grassland. The tree line which served effectively to dam valleys, gradually moved lower down the slopes and allowing peat to accumulate. This habitat blanket bog continued to spread. By the grades into rhôs pasture in valley systems Bronze Age (4,000 BP to 2,300 BP) much larger away from the open moor. areas of Dartmoor were being cleared of forest for farming. Sheep, cattle and ponies The valley mires of Dartmoor are unparalleled were introduced and grazed extensively, in upland Britain - only those on Bodmin not allowing the forest to regenerate. Moor approach them in quality. The main Eventually soils were exhausted through plant community present is rarely found in farming with leaching causing iron pans other upland areas. The distribution and to form. The land became increasingly extent of this plant community in Europe is waterlogged and acidic. When the climate not known, but is likely to be limited. This is became cooler and wetter, as it may have another wetland habitat for which Dartmoor done at the end of the Bronze Age, these is internationally important. conditions provided another opportunity Characteristic species of valley mire for the blanket bog mosses to extend over ● Cotton grass a far larger part of Dartmoor than before. ● Cross-leaved heath Since then the layer of peat has grown ● Bog Asphodel metres thick in places. ● Bog-bean ● sundews Grazing and burning has continued. Burning, ● especially in the summer months, can damage Pale Butterwort that delicate living sphagnum moss ‘skin’. ● Marsh St.John’s Much of the peat has been cut for fuel. Wort Many areas have been disturbed while people ● Moorland Water Marsh have been looking for and extracting tin ore. Crowfoot St.John’s Wort Shelling by artillery for military training only ● Bog Pimpernel ended in 1998 leaving some areas of Blanket ● sedges and bog mosses bog pockmarked. Other areas have been deliberately drained for agricultural Less common are ● improvement and forestry plantations. White Beak Sedge ● More recently, pressure from recreational Marsh Lousewort ● users such as walkers, horse riders, mountain Bog Myrtle bikers has led to some erosion. All these Fauna includes factors, and the combined effects of climate ● Snipe change with more periods of drought and ● Common Frog higher temperatures, have stopped the ● Golden-ringed dragonfly ● further growth of blanket bog. Black Darter dragonflies Understandably very little of Dartmoor’s Special species blanket bog now remains undamaged. ● Bog Orchid * One of the special qualities of peat bog is that it preserves ● Irish Lady’s Tresses organic matter, including old plant pollen. An expert with a ● microscope can identify the presence of plants by identifying Curlew the different types of pollen. By taking samples from different ● Lapwing layers in the peat, one can make a rough reconstruction of ● Keeled Skimmer dragonfly the past vegetation. This technique is called pollen analysis. ● From pollen analysis on Dartmoor we know that it was Southern damselfly covered with oak and hazel. ● Fir Club Moss

Dartmoor National Park Authority Bogs & Wetlands Factsheet September 2004 Page 3 of 6 Factors affecting habitat Special species ◆ Water extraction for human supply may ● Marsh Fritillary butterfly have caused some mires to dry out. ● Southern damselfly ● ◆ In some newtakes fertilisers and too much Mud snail Lymnaea glabra ● Narrow-bordered Bee Hawkmoth manure from livestock have affected and ● changed plant life. Double Line moth ● Cranberry ◆ Acidification from acid rain may be ● Dormice damaging the valley mires. Factors affecting habitat ◆ Disturbance by people and dogs, and ◆ Agricultural improvement has declined predation by crows, and foxes may cause as a threat to these pastures on Dartmoor. decline in Lapwing and Curlew numbers. ◆ Under grazing and lack of scrub control Conservation objectives is a threat to rhôs pastures. ▲ To maintain all valley mires in good condition in terms of water and species ◆ The Dartmoor National Park Authority has composition. targeted this habitat, completing a survey, ▲ To make sure the Bog Orchid and Irish identifying the best sites and valley systems Lady’s Tresses survive and the Keeled and providing management agreements Skimmer Dragonfly remains common. and Environmentally Sensitive Area top up ▲ To stop the decline in breeding waders’ payments for positive management. population by good management practices. Conservation objectives ▲ Maintain and, where possible, Rhôs Pasture improve the area and condition of rhôs pasture on Dartmoor. Rhôs pasture (species-rich purple moor grass and rush pastures) are ▲ Maintain the populations of an internationally rare habitat. Marsh Fritillary Butterfly, On Dartmoor they are found mainly Southern Damselfly and in valley bottoms within enclosed Keeled Skimmer Dragonfly. farmland. The maintenance of ecological value relies on controlled A conservation success cattle or pony grazing, mainly during In the 1980s wet grassland the summer months. The UK probably called Culm grassland has more of this habitat than the rest of was identified as a rare Europe (with the possible exception of and important habitat the Republic of Ireland). Dartmoor across Devon that was contains 1,200 hectares of Rhôs pasture under considerable threat. representing about 2% of the UK resource. Reed In the mid 1980s Dartmoor National Bunting Park Authority played its part by Characteristic wildlife of rhôs pasture carrying out a survey to identify the ● Marsh Plume Thistle most important wet grasslands ● Devil’s-bit Scabious within the National Park. ● Heath Spotted Orchid As Dartmoor is mostly composed ● Saw-wort of granite and not of Culm ● Purple Moor Grass measures (a rock type), the more ● Sharp-flowered Rush general Welsh term rhôs pasture ● Creeping Willow was used to identify this habitat. ● Ivy-leaved Bellflower ● Marbled White ● Small Pearl-bordered Fritillary ● Snipe ● Reed Bunting ● Grasshopper Warbler ● Woodcock ● Barn Owl ● Short-eared Owl ● Fox and Roe Deer

Dartmoor National Park Authority Bogs & Wetlands Factsheet September 2004 Page 4 of 6 At this time the government was giving grants Characteristic wildlife of wet woodland to farmers to improve the productivity of their ● Grey Willow land by draining it. Many farmers were also ● Goat Willow considering creating ponds. The changes in ● Alder livestock farming and the breeds that they ● Downy Birch used meant that the traditional grazing that ● Ash maintained the rhôs pastures was much ● Marsh Marigold reduced. As a result these neglected areas ● Opposite-leaved Golden Saxifrage were being invaded by willow, alder and ● Marsh Violet birch trees and would soon disappear under ● Great Tussock Sedge wet woodland. ● ferns ● bog mosses Action was needed to conserve the rhôs ● rich and diverse lichen communities pastures. Ecologists at DNPA convinced many ● Royal Fern of the owners of rhôs pastures of their Birds include importance and so secured management ● Redpoll agreements both directly with the National Park ● Siskin Authority or through Environmentally Sensitive ● Willow Tit Area agreements (see relevant section). ● Woodcock

By the mid 1990s another survey showed Conservation objectives ▲ that much of this habitat’s decline had been To identify the most important wet woods halted. However, the lack of proper grazing on Dartmoor and protect and manage and the threat of ‘scrubbing up’ and them appropriately. developing into woodland remained. Owners were encouraged through their How are Bogs and Wetlands agreements to put livestock onto the pastures Protected? and volunteers were used to clear some of the invading trees. The most exciting recent There are several ways a particular site can be protected: initiative has been to create a herd of true Dartmoor ponies that can be taken from ▲ by being designated by English Nature as pasture to pasture as a grazing and a Site of Special Scientific Interest because conservation tool. Dartmoor ponies have of special conservation interest under the adapted to local conditions and are an ideal Wildlife and Countryside Act (1981). conservation tool. In this way the Authority The owner has to be very careful and can help conserve the Dartmoor pony, while consult with English Nature before doing managing the threatened rhôs pasture at anything that may affect the wildlife of the the same time. In 1997, The Dartmoor rhôs site. At least four of Dartmoor’s SSSIs are pasture Initiative won the internationally blanket bog or valley mires, including the recognised Eurosite Award for its success in two biggest - North Dartmoor 13,413 involving local people in the management of hectares, and South Dartmoor 9,668 hectares. this wonderful habitat. ▲ Environmentally Sensitive Areas and Dartmoor National Park management Wet Woodland agreements are annual payments to the Willow and Alder woods occur frequently local landowner to manage the land in where the ground is waterlogged within ways that are beneficial to wildlife. Over the National Park. The importance of these 75% of the Dartmoor rhôs pasture is now woods in a national or regional context is covered by agreements which ensure that unclear. However, the habitat is not a they are managed appropriately. common one in England as a whole, the total resource probably being less than Bogs and Mires in Folklore 10,000 hectares (about 5% on Dartmoor). Like the granite tors, Dartmoor’s mires are Within Dartmoor, wet woodlands are often the setting for many a Dartmoor yarn. The found in association with oak woods or rhôs nasty witch Vixana of Vixen Tor lured unwary pasture in valley systems. These woodlands travellers into them. Even now, mischievous are usually of small size, although a few Pixies can confuse you and cause you to be large and well developed examples occur “Pixie led” into them. Livestock are said to within the National Park. disappear into the worst of them.

Dartmoor National Park Authority Bogs & Wetlands Factsheet September 2004 Page 5 of 6 Some time ago a man was making his way Commercial peat workings across Aunehead and was annoyed about losing The 19th century saw an extraordinary number his way in the boggy terrain up there. As he of attempts to develop industries based on struggled across the bog he saw a hat lying on Dartmoor peat. Much ingenuity was used to the bog, so to relieve his frustration he gave the devise ways to dry peat by squeezing and hat a good kick. Much to his surprise he found heating it. There were plans to extract crude the head of a well- known local farmer oil and various kinds of gas. Naptha gas in underneath. Apologising profusely, he asked particular was transformed into candles and the farmer if he was all right, to which he moth balls as well as being used for lighting. replied that he was fine, but he was worried Fibres were extracted to make paper and about the horse he was sitting on. further attempts were made to make peat useful for agriculture and horticulture. It is not surprising that Conan Doyle used Foxtor Some of these ventures carried on for a mire, thinly disguised by renaming it Grimpen few years but most failed miserably. Working Mire, as the climax for his famous Sherlock conditions were very tough on the high moor. Holmes story, The Hound of the Baskervilles. Some peat workers survived by poaching rabbits from nearby Huntingdon Warren. Transporting peat to where it was needed Industries based on peat off the moor has left Dartmoor littered with Peat is an accumulation of plant matter and as tracks, tramways and railways, the Rattlebrook such can be burnt and makes a useful fuel for railway being one example. Between 1868 domestic and industrial use. Its disadvantage and 1955 there were no less then twelve is that it contains lots of water and has to be attempts to make the Rattlebrook peatworks carefully dried before it can be used. 1.8 to 2 viable. Most attempts quickly petered out kilos of dried peat contain the equivalent when the cost of transport became apparent. energy of 1 kilo of good quality coal. In 1961 the abandoned ruins were, at that Generations of moor dwellers have made use time, viewed as a hazard for livestock and of the peat, and peat cutting scars can be were blown up by the military. traced all over the blanket bog area.

The right to take peat from the moor is Domestic use of peat referred to as “turbary”. This privilege was For centuries peat cutting formed an granted by the Crown to the tinners in the important part of the Dartmoor farmer’s year. Cutting, drying and transporting it involved 12th century. Smelting tin ore needs lots of much labour using specialised tools and fuel and very high temperatures and so they specialised words to describe it. An average removed and burnt a lot of it. Dried peat was Dartmoor farmstead required 40 cartloads of part-burnt in kilns or under earth-covered dried peat to see them through the year. mounds and turned into a coke like charcoal Many moor men made some income supplying that in turn would burn at very high towns and villages around the moor. It was all temperatures to smelt tin. 100 kilos of dried carried by horse, pony or donkey with heavily peat produced 36 kilos of charcoal. Unlike the laden panniers on their backs. With the coal that eventually replaced it, charcoal was advance of the railway making coal easily valued as carbon with no impurities. Trains of available the peat trade disappeared. packhorses came from as far away as Cornwall However, peat was still being cut for domestic to collect it. use right up to the Second World War.

Useful web links for further information: For further information, and a list of other Fact Sheets available, contact the: Other factsheets: Education Service, • Wildlife and Habitats Dartmoor National Park Authority, • Dartmoor Commons Parke, Bovey Tracey, Newton Abbot, • Farming on Dartmoor Devon TQ13 9JQ http://www.dartmoor-npa.gov.uk/dnp/factfile/homepage.html Tel: (01626) 832093 Other publications: E-mail: [email protected] • The Nature of Dartmoor: A Biodiversity Profile Website: www.dartmoor-npa.gov.uk http://www.dartmoor-npa.gov.uk/dnp/pubs/natureod.html • Action for Wildlife: The Dartmoor Biodiversity Action Plan This publication may be photocopied for educational http://www.dartmoor-npa.gov.uk/dnp/pubs/bap.html purposes under the Copyright Act 1988. Other information: • http://www.actionforwildlife.org.uk • http://www.dartmoor-npa.gov.uk/dnp/biodiversity/homepage.html Other publications (not available on-line): •Dartmoor Pocket Guides: Natural History set available to purchase at DNPA Information Centres and through our on-line shop: http://www.dartmoor-npa.gov.uk/acatalog/

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