Orchid habitats

GRASSLAND

CHALK AND LIMESTONE GRASSLAND

Downland is a type of pasture typical of southern England, which has generally developed on steep chalk or limestone slopes with extensive sheep grazing. The tradition of using the river valleys in the winter to gain an 'early bite' for livestock, and the chalk ridges for summer grazing has led to a species-rich turf which often includes a range of orchids. Whilst much has fallen under the plough - particularly with the UK's drive to become self-sufficient in food during the Second World War - superb stretches of downland still

Chalk grassland on the South Downs, East Sussex.
IMAGE © 2005: David Lang

remain on the South Downs in Sussex, in Hampshire, Wiltshire, Dorset, the Chilterns and the Cotswolds. The short turf is rich in flowers and is colourful, comprising the yellows of Common Bird's-foot-trefoil and hawkweeds, the blues of scabious and milkworts and the pink of the dwarf Squinancywort. The orchid flora is often very diverse, including Early and Late Spiderorchids, Bee, Frog, Musk, Fragrant and Pyramidal Orchids, Greater and Lesser Butterfly-orchids, and Early-purple, Green-winged and Burnt Orchids. The latter are virtually restricted to ancient, undisturbed pasture, except for one site at Martin Down in Wiltshire, where they have spread onto an area ploughed during the Second World War.

Breckland grassland.
IMAGE © 2005: Peter Lamley

The Breckland of Norfolk and Suffolk was probably cleared of trees in the Neolithic period. There, the soil is a fine, acid sand overlying chalk, and supports a number of rare flowers such as Spiked Speedwell, Maiden Pink and Spanish Catchfly. Early Spider-orchid was found there in 1991 - the first time it had been recorded in Suffolk since 1793.

The limestone grasslands of northern England, in the Dales of Yorkshire and Derbyshire, are particularly species-rich. Burnt Orchid reaches its northernmost site in Wharfedale, while the magnesian limestone grassland of east Durham carries most of the species found in southern England, with the addition of Dark-red Helleborine. In Scotland, there are small areas of superb limestone grassland in Glen Clova, Angus; and at Inchnadamph and Durness, Highland. Here, the Fragrant Orchid occurs mainly as the sub-species borealis, together with Frog Orchid, Small-white Orchid and Dark-red Helleborine.

Coastal calcareous grassland, Purbeck, Dorset.
IMAGE © 2005: David Lang

COASTAL LIMESTONE GRASSLAND

This very special habitat exists in a number of sites on the west coast of Britain, from the Gower peninsula in south Wales, northwards to the Ayrshire coast. Bounded by sea cliffs on one side and arable fields inland, it is never extensive. The finest example is, without doubt, found on the Dorset coast over the Purbeck limestone between Swanage and Lulworth, where pride of place must go to the Early Spider-orchid, which numbers in tens of thousands in a good year.

NEUTRAL GRASSLAND

Many of Britain's traditional pastures and meadows were established on land which was neither strongly acidic nor calcareous. These traditionally-managed 'neutral' grasslands are the main habitat in Britain for Green-winged Orchid. Although examples remain in many counties, this habitat has suffered more than most from the intensification of agriculture in recent decades. Activities such as ploughing, reseeding, cutting early for silage and the application of high levels of artificial fertilisers all have a detrimental effect on orchids, as well as other sensitive plants. It is, therefore, not surprising that the Greenwinged Orchid has declined more than any other species of orchid in recent years.

MACHAIR

Machair habitat is peculiar to the west coast of the Hebridean Islands, apart from a few isolated pockets situated on the west coast of mainland Scotland, and on the western seaboard of Donegal to Kerry and on the Mullet peninsula in Co. Mayo in Ireland. The finest stretches occur on the Outer Hebrides, such as North and South Uist, Benbecula, Barra and Tiree. Machair is found on the western shores of the islands and comprises flat grazing areas overlying wind-blown shell sand, inland from the coastal sand dunes. In the past these areas provided improved grazing on 'township' commons under a system called 'souming'. They were grazed by moderate numbers of cattle, although the number sometimes increased during the winter months. After the early 1800s, the grazing became dominated by sheep. Machair grasslands have been influenced by arable cultivation since Viking times.

Machair on South Uist.
IMAGE © 2005: David Lang

Later on, there was a rotation of crops, oats and potatoes, then reverting to grass, with seaweed being spread as a manure. In recent years this practice has declined as the use of artificial fertilisers has increased, with grants only awarded on production of an empty plastic bag. Great care had to be taken to prevent overgrazing and the erosion of the thin 'skin' of plant growth, since the strong winds experienced on the coasts that are exposed to the Atlantic gales could result in catastrophic 'blow-outs', and the subsequent destruction of the precious grazing land.

The flowering of the machair in early June is breathtaking - a virtual carpet of flowers - with buttercups, daisies, Bloody Crane's-bill, Sea Stork's-bill, Common Bird's-foottrefoil, Harebell, Lady's-bedstraw and Rue-leaved Saxifrage. The orchid flora is also fantastic, with millions of spikes of the dwarf sub-species hebridensis of Common Spottedorchid and both the sub-species incarnata and the striking, brick-red coccinea of Early Marsh-orchid, as well as Lesser Butterfly-orchid, Frog Orchid and Common Twayblade.

Dune slacks at Ynyslas, north Wales.
IMAGE © 2005: David Lang

DUNE SLACKS

Dune slacks are part of a constantly evolving habitat. On the seaward side a fringe of sand forms on the debris found along the tide-line. This gradually builds up and is colonised by a few species of plants which are able to tolerate these exposed conditions. Once the sand dune has built up, it is then colonised by Marram Grass. A little way inland, away from the sea, further dunes form which are rich in calcareous shell debris. Wind action and rain combine to create flat zones between the dunes which are fractionally above the level of the water table. These areas are known as dune slacks and may contain transient pools of water.

This uncommon habitat is characterised by extensive areas of Creeping Willow, which further stabilises the sand against erosion by wind, and a ground cover of Red Fescue, daisies, thyme, Fairy Flax, Water Mint, Marsh Pennywort and Variegated Horsetail. Plants that are more often associated with chalk downland, such as Lady's-bedstraw and Yellowwort, mingle with typically coastal plants such as Sea Holly, Sea Spurge and Portland Spurge.

Dune slacks are incredibly rich in orchids, both in quantity and in interesting species, depending upon where the dunes are sited. They occur from Braunton Burrows in north Devon, along the south Wales coast at Kenfig and Oxwich, on the north Wales coast at Ynyslas, Morfa Dyffryn and Morfa Harlech, Newborough Warren on Anglesey and Ainsdale on the coast of Lancashire. In Scotland, they occur on the east coast at Culbin Sands in Morayshire and Tentsmuir in Fife. In Ireland this habitat can be found all around the coastline (e.g. Magilligan Point, Co. Derry; Tramore Dunes, Co. Waterford; Killala Bay, Co. Mayo; and Bull Island, Co. Dublin).

Marsh-orchids can be abundant in dune slacks and form spectacular displays, particularly the brick-red sub-species coccinea of the Early Marsh-orchid. Helleborines are also well represented, with Marsh, Green-flowered and Dune Helleborine occurring in Wales and Lancashire. Most important are the populations of the broad-leaved variety ovata of Fen Orchid in south Wales, where colonies can be extensive. However, this species is highly sensitive to environmental change and only thrives in newly-formed dune slacks which are scarcely above the level of the water table. It therefore relies upon a succession of new dune slacks being formed, into which they can seed and spread.

In addition to their marsh-orchids, the dune slacks on the east coast of Scotland contain Lesser Twayblade, growing in moss under Heather, and Creeping Lady's-tresses. Both species occur where the ground is drier, often under planted coniferous trees. Dune slacks in North Uist are the habitat for the rare sub-species scotica of the Western Marsh-orchid.

LIMESTONE PAVEMENT

The almost lunar appearance of limestone pavement is unforgettable. At first glance, the landscape resembles porridge, with grey, continuous cover. However, on closer inspection it will be seen to be composed of flat blocks (or clints) separated by deep cuts or fissures (known as grykes). Small areas can occur wherever there is exposed Carboniferous limestone, but the most spectacular stretches of limestone pavement in England are at Gait Barrows in Lancashire and Souther Scales below Ingleborough in Yorkshire. Smaller areas exist from south Cumbria up to Durness in Sutherland. All are fascinating, with a rich flora often sheltering deep in the grykes where it is warm and sheltered. Here it is possible to find Bloody Crane's-bill, Angular Solomon's-seal and the poisonous Baneberry, as well as orchids including Common Twayblade, Early-purple, Fly and Small-white Orchid as well as Dark-red Helleborine.

The finest limestone pavement of all is known as The Burren, which is situated in Co. Clare on the west coast of Ireland. In this area, a number of different plant groups combine to form unique communities at sea level, and include species such as Mountain Avens, Spring Gentian and Dense-flowered Orchid - this latter orchid is now restricted to this area. Amongst the stretches of limestone are small seasonal lakes, or turloughs, along the edges of which flourish Fly Orchids, Lesser Butterfly-orchids, the rare sub-species cruenta of Early Marsh-orchid and the white-flowered sub-species okellyi of Common Spotted-orchid.

Limestone cliffs at Dovedale, Derbyshire.
IMAGE © 2005: David Lang

LIMESTONE CLIFFS

Limestone cliffs rarely support large orchid populations, as they are exposed and liable to erosion. Nevertheless, they can serve as places of refuge for plants from the teeth of grazing sheep. Good examples can be found in the Avon Gorge in Somerset, Dovedale in Derbyshire and in many sites in North and West Yorkshire, such as Malham Cove, Gordale Scar, Arnecliffe, Kilnsey Crag and Pen-y-ghent. The Carboniferous limestone cliffs of the Gower peninsula in south Wales are superb for plants, as are the cliffs of Inchnadamph and Durness in west Sutherland. Dark-red Helleborine is particularly prevalent on these northern cliffs, while Frog Orchid and the northern sub-species borealis of Fragrant Orchid can be found on the grassy slopes at their feet.

MARSH

Marshes have often been formed as the result of human activity. From Roman times onwards, land has been reclaimed from the sea by walling off tidal mudflats. These then become colonised by reeds as the salinity decreases, and finally dry out and become used for grazing land. A similar process has led to marshland forming along the banks of slowflowing rivers in flood-plains.

Marsh at Warnborough Green, Hampshire.
IMAGE © 2005: Bob Gibbons (Natural Image)

Many of these marshes have been drained in recent centuries, but they still exist in north Kent and Essex along the Thames, the Pevensey Levels in East Sussex, the Lymington Marshes in Hampshire, the Somerset Levels, along the river valleys of Suffolk, Norfolk and Cambridgeshire, and particularly along the Lincolnshire coast.

Marsh-orchids can be found along the edges of wet marshes, where they are not out-competed by Common Reeds. Early, Southern, Northern and Narrow-leaved Marsh-orchids are all recorded, with smaller numbers of Greater and Lesser Butterfly-orchids and Heath Spotted-orchid. Coastal marshes can also hold extensive populations of Marsh Helleborine.

BOG

Bogs can form wherever water becomes trapped and the ground surface remains consistently saturated. The water involved may be primarily rainwater or predominantly ground water and the types of bog which result are significantly different in their importance for orchids. Although both types of bog are poor in minerals and nutrients, and characterised by acid-loving plants such as Sphagnum mosses and sundews, they differ in particular in the movement of water through the developing peat.

Valley bog and wet flush on Crane's Moor, New forest, Hampshire.
IMAGE © 2005: Bob Gibbons (Natural Image)

Bogs which obtain their water entirely from rainfall occur mainly in the west and north of Great Britain and Ireland where the rainfall is high, and they form on gently sloping or flat terrain, usually over an acid substrate. They can be divided into two types:

• RAISED BOG which forms on a flat underlying surface, frequently as an infill of glacial lakes, and has a gently dome-shaped profile, with peat deepest at the centre.
• BLANKET BOG which forms in areas with such a high rainfall that moss, and hence peat, can develop over more sloping terrain. The vegetation literally smothers gentlysloping uplands in a blanket, following the land contours. It is this type of bog which covers huge areas of the 'flow country' in east Sutherland and Caithness.

Bogs that are more influenced by ground water also form in very gently-sloping river valleys. They are especially frequent in places such as the New Forest, although small examples can be found almost anywhere in Great Britain and Ireland, and are much less dependent upon a high rainfall. These bogs usually have greater water flows and as a result are less nutrient deficient and better oxygenated. Consequently, the number of orchids occurring in these types of bog tends to be greater than in raised or blanket bogs.

Bogs are composed of mosses, predominantly Sphagnum species, with sundews and creeping plants such as Dewberry, Crowberry and Cranberry. In the more mature, drier, areas plants such as Bilberry, Ling, Heather and Dwarf Birch also occur. Since the environment is acidic, orchids are not widespread, although species such as Heath Spotted-orchid, Lesser Butterfly-orchid and Lesser Twayblade are found. Bogs are, of course, the habitat of the rare Bog Orchid which flourishes in the saturated moss. Important areas for bogs include the New Forest in Hampshire, on Dartmoor and Exmoor, throughout Wales and on Anglesey, the Cheshire and Shropshire meres and mosses, the Solway and Duddon mosses of Cumbria, Thorne and Hatfield moor in Yorkshire, and all of upland northern England and Scotland. They are very extensive in central and northern Ireland.

Moorland, Rannoch Moor, Highland.
IMAGE © 2005: David Lang

ACID HEATH AND MOORLAND

Heathland and moorland are mostly comprised of shrubby species including heathers and gorses. Whilst lowland heathland characterises generally dry areas, moorland occurs at higher altitude and in wetter districts. Trees tend to be sparse, chiefly scattered Pine and Birch, with a ground cover including shrubs such as European and Dwarf Gorse, Heather, Ling and Bilberry. They originated following the clearance of woodland with fire by early human settlers in the Neolithic and Early Bronze Ages. Moorland covers large areas of Scotland, Wales, Ireland and the north of England, with similarly extensive areas on Exmoor and Dartmoor in the south-west.

Lowland heathland characterises areas of southern and central England. Relatively small pockets remain in the Ashdown Forest in East Sussex, in West Sussex, the New Forest of Hampshire, parts of the Breckland in East Anglia, the Dorset heaths, in Devon and on the Gower in south Wales. The ancient heathlands of the Lizard peninsula in Cornwall lie over outcrops of serpentine rock, and host a number of rare plants, including Cornish Heath. Further north, there are the 'Coversands' of Lincolnshire and Humberside.

Orchids are not often present in large numbers on heathland, Heath Spotted-orchid being the most widespread and plentiful species, with marsh-orchids in damp areas. In the northern half of Britain, sub-species pulchella of Early Marsh-orchid and Northern Marsh-orchid are the most common. Lesser Butterfly-orchid occurs sporadically and Lesser Twayblade is not uncommon, growing in Sphagnum mosses under the heather.

LOW MONTANE

Low montane comprises a mosaic of many different types of habitat. It occurs in Wales, northern England, Scotland and Ireland up to an altitude of 500m. It is an area of high rainfall, but the habitat lacks the extremes of exposure and cold experienced in truly mountainous areas. The countryside comprises a patchwork of unimproved pasture and small hay meadows with extensive areas of moorland and exposed rock. Stream valleys have birch as the dominant tree species, whilst lakes and lochans may be bordered by bog.

Low montane habitat at Tir Stent, Dolgellau, Gwynedd.
IMAGE © 2005: David Lang

Orchids may not be numerous, but some less common and fascinating species can be found in these areas. Heath Spotted-orchid is once more the most common species, with Northern Marsh-orchid occurring in the damper areas. Lesser Butterfly-orchid, Small-white Orchid and the northern subspecies borealis of Fragrant Orchid grow in the old pasture areas, with Lesser Twayblade in the rocky parts and even Bog Orchid on the edge of flushes and stony runnels. In north-west Scotland, Lapland Marsh-orchid grows in damp hill flushes, with the rare Irish Lady's-tresses on the edge of hill lochs and rivers which are inundated in the winter.

BROAD-LEAVED WOODLAND

Broad-leaved woodland is primarily a feature of lowland Britain, becoming less extensive further north. The dominant species of trees changes with latitude, resulting in a wide variation of woodland types. Each type of woodland favours different orchid species which have differing preferences for light and shade, depth of leaf litter and competition from shrubs and other ground flora.

Early-purple Orchids under Ash coppice at Kings Wood, Heath and Reach National Nature Reserve, Bedfordshire.
IMAGE © 2005: Peter Wakeley (English Nature)

Beech woodlands support the most exciting orchid flora. Mature Beech woodland with a typically light ground cover of Dog's Mercury can be found along the North and South Downs, in Hampshire, Wiltshire and Dorset, the Chilterns and the western end of the Cotswolds. White Helleborine and the rarer Narrowleaved Helleborine can occur in considerable numbers, with the very rare Red Helleborine found in favoured sites. Bird's-nest Orchid also occurs, often with the unrelated but similar-looking Yellow Bird's-nest. Rare inhabitants include Lady Orchid, Narrow-lipped Helleborine and Ghost Orchid, the latter restricted entirely to mature Beech woodland within which there is a deep layer of litter.

Woodland composed of Beech mixed with birch, Field Maple and whitebeam, with a ground cover including Bramble, Lords-and-Ladies and Wood Anemone, is also widespread along the North and South Downs, the New Forest and the Chilterns. Additional orchid species that occur here include both Broad-leaved and Violet Helleborine, the latter tolerating more shade, Early-purple Orchid, Common Twayblade, Green-flowered Helleborine, Fly Orchid and the two splendid relatives, Lady Orchid and Military Orchid.

Coppicing is a form of woodland management practised mainly in the south of England. Woodland composed of Hazel, Hornbeam and Sweet Chestnut is periodically cut down to ground level, producing broad-based 'stools' from which multiple, tall, straight branches grow, ideal for use in hedge-laying or as hop-poles. Early-purple Orchids, Common Twayblade, Fly and both Greater and Lesser Butterfly-orchids all flourish, particularly under Hazel and Hornbeam, as does Lady Orchid in Kent. As the trees grow and the canopy thickens orchid numbers tend to decrease, but, in the first couple of years after fresh coppicing, they can be spectacular.

In the west and north, from Dartmoor to Sutherland, but especially in mid- and north Wales and the Lake District, the dominant broad-leaved woodland consists of Sessile Oak mixed with Downy Birch, Rowan and Holly. The understorey is predominantly Bilberry and Heather and sometimes includes Creeping Lady's-tresses, but this is a generally poor habitat for orchids. Upland woodlands containing Ash and Hazel mixed with Rowan and Downy Birch are far more open in character with plentiful Dog's Mercury and flowers such as Solomon's-seal and Wood Crane's-bill. Orchids are few in number, but this is the habitat for the lovely Lady's-slipper where there is underlying limestone.

In north Yorkshire, Cumbria, south and north-east Scotland there is woodland composed of Bay Willow growing over a peaty soil, with a healthy growth of sedges such as Bottle Sedge. This is one habitat where Coralroot Orchid may be found.

Caledonian Pine Forest, Loch Maree, Highland.
IMAGE © 2005: Bob Gibbons (Natural Image)

PINE WOODLAND

Ancient pine forest, composed of Scot's Pine, is now entirely restricted to small remnants of the Caledonian Forest of Scotland, such as that in Glen Feshie, Highland. Trees are spaced well apart, with a dense ground cover of Heather, Ling, Bilberry and Crowberry. In places there can be shelter and a dense carpet of moss, with fascinating flowers such as Twin-flower, Common, Roundleaved and One-flowered Wintergreens. Orchids such as Creeping Lady's-tresses flourish and their root system runs through the moss carpet, with Lesser Twayblade growing in Sphagnum under the Heather and Coralroot Orchid in slightly drier sites.

Planted conifers, especially plantations of closely-ranked Sitka Spruce, are valueless as orchid habitat, but some areas such as the Culbin Forest in Morayshire and Tentsmuir Forest in Fife have matured over the years and become superb orchid habitat.

ROAD VERGES, LAWNS AND CHURCHYARDS

Whilst most human activity spells doom for orchids, we have managed, despite ourselves, to create habitat which is highly supportive of the more opportunistic orchid species.

Road verge at Amberstone, East Sussex.
IMAGE © 2005: David Lang

Road verges - provided that they are subject to sympathetic management and not regularly mown - can support stunning populations of Common Spotted-orchids, Early-purple Orchids and Pyramidal Orchids. Bee Orchids seem almost to relish the disturbance, and will appear in impressive numbers on recently graded roadsides. Their numbers then decrease over succeeding years. Experimental work is currently being carried out involving the scarification of certain motorway verges to see if Bee Orchid numbers respond positively.

Lawns, tennis-courts and churchyards can provide equally productive orchid habitat, with Common Spotted-orchids, Early-purple Orchid, Green-winged Orchid and Autumn Lady's-tresses all gracing suitably managed grass. Indeed, Autumn Lady's-tresses benefits from a well-maintained, mown sward, the leaf rosette being so flat that the mower blades do no harm.

FLY-ASH TIPS AND LAGOONS

Of all the habitats which appear to be unpromising for orchids, fly-ash tips and lagoons must seem among the worst. Each year, 10 million tons of ash is produced from coalburning power stations. Much is used in the construction industry but the rest is disposed of as mounds or as lagoons. Initially barren, the first plants to appear are species of goosefoots and salt-marsh grasses, plants that are well able to cope with the high level of mineral salts in the substrate. Over many years there is a gradual sequence of development, with birch and willow appearing and then, after some 10-20 years, orchids starting to colonise, weathering having reduced the ash to a base-rich 'soil'. Common Spotted-orchid, Early and Southern Marsh-orchid are the first to appear, often in impressive numbers, including swarms of hybrids. Bee Orchid has also been recorded, as has Marsh Helleborine on very mature sites. Unfortunately, some of the orchid sites have to be 'restored', since this was part of the original planning consent. Access to these sites is inevitably restricted for safety reasons.

Southern Marsh-orchids at a post-industrial site, Canvey Island, Essex.
IMAGE © 2005: Chris Gibson (English Nature)

Particularly interesting orchid sites exist in the Cheshunt gravelpit complex in the Lee Valley in Hertfordshire, at the Carmarthen Bay wind energy centre, at the old Wilford power station site in Nottinghamshire, at Wakefield and Wigan power stations in Yorkshire, and at other sites such as Rye House in Hertfordshire, Meaford in Staffordshire, Fiddlers Ferry in Lancashire and Elland in West Yorkshire.