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| North Pennines |
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| Habitat: Upland heathland (of national significance) |
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Occurs below the montane zone and above enclosed agricultural land (around 300 m altitude), on mineral soils and shallow peats. Characterised by at least 25% cover of dwarf shrubs.
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Heathland habitats account for almost 20% of the Natural Area. Dry heath is an importantelement of the North Pennines' habitat resource and constitutes 67% of all the heathlandhabitat.
Heather is the most characteristic plant of upland dry heath communities in the NorthPennines, Britain and North West Europe as a whole. Heather is the most abundant dwarfshrub throughout a number of heathland communities, producing the distinctive brilliantpurple which is on display across the uplands in late summer. Where it is foundpredominantly above the upper limits of enclosed pasture at relatively low altitudes, heathercan form almost pure and uniform stands and the only other constant species within these iswavy hair-grass. This community is typical of the more southern Pennines and reaches itsnorthern limit of distribution in north-eastern England. Much of its character stems fromintensive grazing and burning management.
Heath often lies downslope from adjacent blanket mire communities on drier shallower peats. A good example of this zonation occurs on Cotherstone Moor (Teesdale) where dry heath liesimmediately to the east of wet bog vegetation. Wavy hair-grass can, together with bilberry,attain local dominance where grazing intensity is high, especially in the winter months whenheather is favoured by sheep. Chronic heavy grazing often encourages a greater occurrence ofgrasses such as mat-grass, sheep's fescue and wavy hair-grass as young heather shoots areunable to regenerate quickly enough and become swamped by these more competitivegrasses. Consequently, mixtures of heath and acid grassland communities pattern large areasof land. In some cases heather cover is suppressed completely and heathland vegetationgrades into acid grassland. The moss flora is very sparse in this heathland community as awhole due to the poor retention of soil moisture and cool air temperatures. Species such as Pohlia nutans, Hypnum cupressiforme and Dicranum scoparium can occur at low frequencies however, together with vascular plants such as bracken, heath bedstraw and crowberry. Oak and birch seedlings can also be found amongst the heathers, emphasising the ever-present dynamism of this habitat type. Grazing pressure, however, usually prevents such tree and shrub species from successfully establishing.
Another common feature of upland dry heath vegetation in the north-east of England atmoderate altitudes is the abundance of heather and bilberry growing together. Widely burnton a rotation of between 10-25 years and grazed, the heather is often very variable in age andheight. On the shallow peat soils of the upland plateau margins, bilberry is a more constantcomponent of the heath vegetation and thrives on the more severe climate of the hills. Theclimatic influence is also reflected in the greater abundance of two Arctic-Alpine dwarfshrubs, crowberry and cowberry. Bell heather is also reasonably frequent here along withcharacteristic species such as tormentil, sheep's fescue and wavy hair-grass. Bryophytes aremore pronounced and can include Hylocomium splendens and Pleurozium schreberi. This particular heathland type is perhaps the most abundant in the North Pennines and the most extensive heathland type encountered in the UK.
The contribution of cowberry and crowberry to heathland vegetation does, however, declinewith a move further westwards into a more oceanic zone with a considerable Atlanticinfluence. Heather-dominated communities at lower altitudes here are characterised by aprofusion of heather and bell heather, but also species which thrive in cooler, wetterconditions. The thick tussocks of purple moor-grass are a feature here, along with sedgessuch as green-ribbed sedge and pill sedge, and hard fern. This community is uncommon andvery restricted in the Natural Area, being more characteristic of the Lake District andnorth-west Scotland but outlying examples do occur on Stanhope and EdmundbyersCommons.
Another heathland type of limited occurrence in the Natural Area, due to its preference forAtlantic conditions of north-western Britain, is a community where bryophytes become moreprominent. This type of heath is a feature of ravines, steep gills and scree where burning isavoided, grazing is less intensive due to the terrain and local climatic conditions are muchmore humid. Heather and bell heather still dominate, but the humidity allows thedevelopment of bog mosses. Sphagnum capillifolium is by far the most characteristic species of this type of heath. Examples occur on areas of Woodland Fell (Teesdale) andEdmundbyers Common.
Upland wet heaths are relatively scarce in the North Pennines due to unsuitable climaticconditions and management. Cross-leaved heath tends to be a prominent feature of thesecommunities, along with purple moor-grass and deergrass. Compared with drier heath, thereis usually a very striking increase in Sphagnum mosses, although the bog mosses which occur fail to attain the levels of abundance found in bog vegetation. In the North Pennines themajority of the wet heath is found in the wetter western areas.
Habitats strongly resembling wet heath are often found in the uplands where heath grades intobog. However most of these transitional areas have been pushed towards either drier heath ormodified bog through burning (and hence suppression of bog-mosses) or grazing, and theircharacter lost.
These are particular forms of upland heath which occur on the highest, more exposedsummits of the North Pennines (e.g. Cross Fell). They are more typical of the central andeastern highlands of Scotland, but can be found at scattered localities in the southern uplandsof Scotland and parts of the north of England. Typically they consist of low mats of prostrateshrubs with an abundance of lichens and mosses, some of which are nationally rare. Thisform of heath comprises only 184 ha in the North Pennines Natural Area.
Britain has the most extensive examples of upland heath in Europe, a habitat type which islimited to the Atlantic fringe of the north-west. In Britain, and in the North Pennines, thishabitat type holds internationally important numbers of breeding birds such as red grouse,merlin and golden plover. Upland heaths, therefore, assume considerable internationalsignificance and are listed under the EC Habitats Directive. The extent and quality of uplandheath in the North Pennines is widely acknowledged, the result being that the region has aninternational responsibility to promote the sustainable management of these communities. Sympathetic moorland management is vitally important in maintaining both the economicand conservation interest of these habitats. Already, 20% of British heather moorland(including mire communities) have been lost since 1947 with an additional 50% at risk ofdegradation. Heavy sheep grazing and poor burning practices are largely the problem andencourage the conversion of heath to acid grassland. There have also been recent examplesof moorland reclamation for agriculture by ploughing and reseeding on the eastern fringes ofthe Durham Pennines.
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