HEATHLANDS ON THE INTERNET
Heathland is a valuable ecosystem, which often has to be managed. Some management plans for areas of the UK can be found on county council websites where Heathlands are common, and are therefore part of the management plans: e.g.:
The site of DEVON COUNTY COUNCIL from which the passage below is taken, to give a flavour for what is available.
DEFINITION of Heathland
The expansive purple, golden and brown landscape which is lowland heathland is an evocative feature of southern England. Charged with history and alive with scent and colour, it combines an ancient origin with a vibrant living character. The power of heathland to evoke a sense of human desolation against the vastness of nature has led to it forming the backdrop to some of the most dramatic human stories of English literature over the last few hundred years.
Heathland is a product of human activity, formed where primeval forest was cleared for early agriculture on nutrient-poor soils, in the cool, moist climate of the Atlantic zone of north-western Europe. It relies upon the continuation of that human activity, and without it a reversion to woodland quickly takes place. However, while in the past heathland represented the most productive use which agricultural techniques could make of intrinsically poor quality land, today heathland survives only where there is a conscious intent to retain it, in the face of the capacity of modern agriculture and forestry to turn it to other uses.
Lowland heathland is defined as open uncultivated land below about 300 metres in altitude, dominated by dwarf shrubs - ling, cross-leaved heath and gorse - intermixed with acid grassland, bog, bracken, scrub and scattered trees. In Devon, lowland heath represents part of a continuum of overlapping, related habitats between the upland heaths of Dartmoor and Exmoor.
The UK’s lowland heathlands are of international importance, and represent some 20% of the total area of the habitat in Europe. Most of that lowland heathland occurs in southern England and parts of Wales, from the Brecklands in Norfolk, the Suffolk Sandlings, through Surrey, the New Forest in Hampshire, through the large Dorset heaths, down to east and south Devon and the Lizard in Cornwall, and up through Pembrokeshire into parts of Gwynedd. Devon’s lowland heathland is sometimes overlooked between the larger expanses in Dorset and Cornwall, yet it represents one fifth of the total in the South West, and has a unique character.
Devon’s lowland heathland, like many of its special wildlife habitats, is subject to great pressures and has declined markedly in the course of this century. Losses to agricultural improvement, with former heathland being converted to more productive pasture, and forestry, which now covers substantial areas of former heath, have reduced the county’s lowland heaths to some 4000 hectares. Much of what remains is now managed specifically for its wildlife and landscape value, but such management is costly and relies upon a continued political commitment to existing and future funding mechanisms. Meanwhile strategic decisions about land use offer the potential for the re-establishment of heathland in some areas, if there is a collective will to see the habitat consolidated and enhanced.
Many of Devon’s most cherished and characterful wildlife species depend upon heathland, including the nightjar, woodlark, Dartford warbler and silver-studded blue butterfly. Their continued presence in Devon, and that of the superb landscape they inhabit, requires the commitment of a number of organisations, which in turn requires a clear, agreed framework for action.
The character of Devon’s lowland heathland is provided not just by heather, which is less predominant in Devon’s heathlands than it is in other heathland areas further to the east, but by a varying mosaic of heather, western gorse, bristle bent, cross-leaved heath and bell heather. Other frequent plants are bilberry, bracken, tormentil and lichens of the genus Cladonia, with bracken sometimes predominating.
Most of Devon’s heathland complexes contain wetter areas, where purple moor grass becomes abundant and cross-leaved heath more frequent, together with a variety of sedges (common, carnation and star sedge for example), bog mosses, rushes and devil’s-bit scabious. Less common specialities of these boggy areas include bog pimpernel, bog asphodel, round-leaved sundew and pale butterwort.
Patches of scrub, dominated by willow and birch, are also an integral part of heathland, though without management these spread to the detriment of the open heath. Isolated trees, including Scots pine, are also a feature of drier heathland sites, and add much to their character.
The fauna of lowland heathland in Devon is diverse and includes a wide range of species dependent on the conditions heathland provides. The invertebrate and bird faunas are especially notable. More than 35 species of butterfly, and 21 species of dragonfly and damselfly breed on Devon’s heathland, making heathland one of the most important invertebrate habitats in the county. Meanwhile a number of specialist bird species breed on the county’s lowland heathland, including nightjar, Dartford warbler, stonechat, whinchat, tree pipit and a dwindling number of curlew in wetter areas. The reptile fauna which is such a speciality of Dorset heathlands is less well represented in Devon, though adders are frequent.
PROBLEMS facing Heathland areas
Agricultural improvements Much of the loss of lowland heathland over the course of this century in Devon has been due to agricultural improvement of land by drainage, ploughing, re-seeding and fertiliser application. Losses to this cause have largely come to a halt now, though some of the smaller heathland sites remain vulnerable, and a recent prosecution by English Nature for ploughing of part of a major heathland SSSI in the county has once again highlighted that heathland remains open to abuse.
Afforestation Much of the former heathland area of the county is now under forestry. In particular the large Forest Enterprise estate on the Haldon Ridge was originally established in large part on open heath. Some blocks of former heathland were turned to forestry also in the Bovey Basin and on the East Devon Pebblebeds. Forestry and heathland are not necessarily entirely incompatible however; heathy vegetation may persist under plantations, and can be maintained on forest rides and glades. Areas of clearfell and crops under 8 years old also provide a heath-like environment which provides a habitat for the more mobile species; these areas can be maintained at about one sixth of the forest area. The persistence of heathland under forestry means that in many cases heathland can be restored if the conifer crop is harvested and not replaced.
Mineral workings have caused the loss of lowland heathland sites in the Bovey Basin (ball clay extraction), the Dartmoor fringes (china clay extraction) and the East Devon Pebblebeds (sand and gravel extraction), both to mineral excavation and to subsequent mineral waste tipping. Such losses are absolute, but in the long term site restoration plans offer the potential to recreate a heathland after-use. Several heathland sites are subject to extant mineral planning consents.
Overgrazing Less drastic than full agricultural improvement, but ultimately as damaging, overstocking of heathland vegetation with sheep or cattle causes a gradual transition to poor acid grassland, as the vigour of the heather and other dwarf shrubs is reduced by excessive grazing and trampling. Poorly regulated exercising of common grazing rights is sometimes the cause of such overstocking.
Abandonment and neglect Conversely, many of the smaller heaths, and much of the coastal heathland complexes, have suffered from too little rather than too much grazing, often because they do not offer a viable source of grazing, and are not in keeping with the rest of larger farm units, yet have not been economic to convert to grass. Such sites become degraded, or have been lost altogether due to scrubbing up and succession to woodland.
Fragmentation and isolation of sites The above factors mean that some heathland sites are separated and surrounded by improved agricultural land or forestry, often making their continued management by traditional means impractical, and preventing free movement and colonisation by less mobile species.
Recreational use One site in the Bovey Basin currently suffers from unsustainable use as an unofficial motorbike scrambling site. In recent summers several sites have been subject to accidental or deliberate fires which, though fire is an important tool in heathland management when carried out carefully in the winter months, is seriously damaging to vegetation and to breeding wildlife if it occurs in the summer. One of these fires was caused by a model aircraft igniting after crashing on the heath, illustrating the risks accompanying large scale recreational use of heathland sites.
THE ROLE OF FIRE IN HEATHLAND AREAS
Try this GERMAN SITE for more on HEATHS.
Heathlands dominated by ericaceous dwarf shrubs are widespread on acid nutrient-poor soils throughout those regions of north-western Europe with an Atlantic climate. They developed c. 4000 years ago following forest clearances and have been maintained by grazing, burning, turf (sod) cutting, and the gathering of vegetation for fuel. These activities arrest succession to scrub and woodland (Webb 1986). Heathland is burnt to improve the forage for grazing stock but some fires are uncontrolled and wildfires may occur.
Heathlands show some of the characteristics of a fire climax (Gimingham et al. 1979). The dominant species Calluna vulgaris regenerates freely from the stem bases when burnt and the germination of its seeds is promoted by heat. Regular burning reduces the floristic composition of heathland and species which regenerate from underground organs or rapidly from seeds (eg. Calluna vulgaris) tend to dominate. Species such as Juniperus communis are eliminated by regular burning (Gimingham 1972).
During heathland fires about 95% of the nitrogen and 20-30% of the other principal plant nutrients in the standing crop and accumulated litter are lost from the system. Losses of Na, K, Ca and Mg can be replenished from precipitation within a few years but the losses of P and N cannot. Phosphorus is held in the soil organic matter, and where the adsorption capacity is low, some of the P released during the fire is lost through leaching. It takes c. 20 years for P to be replaced (Chapman et al. 1989). The nitrogen budget is not fully understood. Because losses during a fire cannot be made up through rainfall, nitrogen-fixing plants (Ulex spp.) may be important (Chapman and Webb 1978).
Where the fire has not been too hot Calluna regenerates from the stem bases and within three years enters the building phase. If the roots are killed regeneration is from seed giving a true pioneer phase, but taking longer before the building phase is reached. Over the 30-40 years of heath growth production increases but declines from about 20 years and onwards. The structure of the vegetation affects the microclimate during this process. At first, the canopy is open and the soil and litter surface dry with extremes of temperature. During the mature phase when the canopy is more or less complete, humid, still conditions with small fluctuations of temperature prevail. As the canopy opens during the late mature and degenerate phases more extreme conditions occur again.
Heathland managed by burning consists of stands of a uniform age where the bushes all have the same structure. Other forms of management create mixed-age stands where bushes of different structure grow side by side. The invertebrate fauna is dependent on the structure of the Calluna bushes and there is a positive relationship between invertebrate diversity and the structural diversity of the vegetation. For some ground living species (eg. ants; Hymenoptera: Formicidae) this relationship may be negative as the developing vegetation canopy reduces insolation. After a fire there is a well-marked succession of species, with some species being characteristic of the early stages and others characteristic of the mature and degenerate phases. Spiders (Araneae) and ground beetles (Coleoptera: Carabidae) are typical examples. The soil fauna is dependent on soil moisture and the presence of plant litter. After a fire the development of the fauna is closely associated with the recovery of the heathland vegetation (Webb 1994). During a fire soil temperatures are <45° C because of the good insulating properties of the litter layer. Few animals are killed by the fire; however, populations decline rapidly once the vegetation canopy has been removed because the litter becomes very dry and blows away. A new layer begins to form only when the plant canopy closes c.10 years after the fire.
Heather moorland in the north of England and Scotland is burnt every 12-15 years to provide nutritious young heather shoots for sheep and grouse. Grouse moors are burnt in strips because grouse require young heather for food and taller old heather for nesting and a supply of invertebrate food for their chicks. The management aims for these moors are very clear, but for lowland heathland conservation Chapman and Webb (1978) have suggested burning every 20 years. This cycle matches the replacement rate of nutrients, particularly P, by rainfall. Although the 20-year cycle matches nutrient inputs, too large a fuel load develops causing hotter fires and affecting plant succession. Fire temperatures depend more on conditions (moisture, rainfall, wind) at the time of burning, than on fuel load (Allchin et al. 1996).
Accidental fires are common with peaks in their numbers during holiday periods in April and August. Most of the accidental fires occur near the urban areas and because of this there has been a reluctance to use controlled burning for heathland management. Strict fire protection measures have been implemented over the last 20 years and in Dorset the area burnt has declined from 1071 ha in 1978 to 451 ha in 1987. Until recently, when grazing has been introduced, fire has almost been the factor controlling succession. Because of the decline in burning the extent of scrub increased by 15% between 1978-87 (Webb 1990).
In the very hot dry summer of 1976 eleven percent of the Dorset heathlands was burnt. A landscape scale analysis over the period 1978-1987 (Bullock and Webb 1995) showed that neither the extent nor the composition of the principal heathland types was affected by these fires. The only long-term effect was in the species composition of scrub. The fires had conserved the dynamic mosaic of the heathland vegetation types by preventing the succession of heathland to scrub and by reducing the cover of woodland. At large temporal and spatial scales the heathland landscape remained stable despite catastrophic disturbance at specific locations
Ideas for restoring heaths can be found HERE.
Chapman and Webb (1989) define a heathland as a "plagioclimax community dominated by ericaceous dwarf shrubs". Many European heathlands are dominated by the heather Calluna vulgaris (Snow and Marrs 1997). Heathland in north-western Europe expanded 3000-4000 years ago following the clearing of the forests. In England, "between the mid 18th century and 1978," 80% of heathlands were lost (Chapman et al. 1989). The current distribution of heathland ranges from the lowlands to the upland moors of Great Britain (Putwain and Gillham 1990).
The fragmentation of lowland heathland is of greatest concern in southern England (Putwain and Gillham 1990). Lowland heath communities are important to rare faunal species like the Dartford Warbler, Sylvia undata, the Sand Lizard, Lacreta agilis, and are home to the rare heather species Dorset Heather, Erica ciliaris (Bullock and Webb 1995). Recent changes in governmental agricultural policy have created new opportunities to set aside and restore lands for conservation purposes. One of the programs involved is the "Countryside Stewardship" which provides "financial incentives to recreate biotopes of conservation interest, including lowland heath" (Pywell et al. 1994).
Many heathland restorations have been undertaken on old farm fields (Smith et al. 1991), mined lands and lands disturbed in order to bury pipelines, as well as road construction, and the construction of power stations and oil terminals. Other restorations have taken place to replace those heathlands lost to development (Putwain and Gillham 1990). Some of the parties responsible for heathland restoration include English China Clay International and Shell UK Ltd., as well as British Gas and the Central Electricity Generating Board (Putwain and Rae 1988).
Some of the techniques for restoration include:
Transplanting heather turves
Use of heather topsoil
Restoration of heathland on old farm fields
Use of heather litter
Use of heather shoots
Bracken control measures
There are also maps of heathland areas which can be used as named case studies:
e.g Gittisham Common, E. Devon
If left unattended heathland will move from its position as a plagioclimax, through the normal succession to woodland.