| Upland
habitat types include heathland, bog, acid grassland and marshy grassland. Upland
habitats are the most extensive semi-natural vegetation types in Lancashire, i.e.
over 40,000ha covering more than 13% of the County and over 50% of the semi-natural
area. Bowland Fells are the largest continuous area of semi-natural habitat in
Lancashire. However, bog and heathland are globally scarce habitat types. The
differences between bog, especially that which has been modified, and wet heath,
and between bog and marshy grassland, can be subtle and they also occur together
in mosaics. If the peat is deeper than 50cm it is defined as bog, even if dominated
by heather. Wet heath and marshy grassland occur on peat less than 50cm deep.
Flushes frequently occur and are associated with flowing water. Stands of bracken
are another significant habitat on the lower slopes of moors & fells. Rock outcrops
may support scarce plants and provide nesting sites for some birds of prey. Moorland
dominated by heather (i.e. over 50% cover) is sometimes referred to as `black
moor`, that with 25-50% cover as `grey moor` and that with less than 25% cover,
including little or no heather, as `white moor`. Blanket
bog is one of two main mire habitats found in Lancashire, the other being Lowland
Raised Mire. Peat
bogs are confined to parts of the world with a cool humid climate, with 10 to
12% of the World's blanket bog occurring in the UK (approx. 1.5 M ha), the majority
of which is in Scotland. Peat
is formed over thousands of years from decaying vegetation in cool wet conditions
as a layer or blanket on gently-undulating hillslopes and on hill-tops. Valley
mires may develop along the lower slopes and floor of small valleys. Basin mires
develop in waterlogged hollows. The
cool wet climate of the UK's west coast provides the right conditions. In Lancashire
the gentle slopes of the Bowland Fells and the Southern Pennines, including the
West Pennine Moors, are particularly suitable for its development. Upland
heathland Heathland
must have at least 25% cover of dwarf shrub heath plants to be defined as such
and can be wet, dry or montane. Upland
heathland is largely confined to the western sea-board of Europe, at an estimated
2 Million hectares, but there have been considerable losses since the Second World
War due to afforestation and heavy grazing by sheep. In Lancashire, losses have
occurred in the Southern Pennines, including the West Pennine Moors, the latter
suffering a decline in heather cover of 50% between 1946 and 1988. Acid
grassland is often unenclosed and occurs on a range of acid soils with pH less
than 5.5. It is generally species-poor and may be derived from blanket bog or
heathland as a result of grazing. Acid grassland is normally dominated by one
or more of wavy hair-grass, sheep's fescue, mat-grass and heath rush. Herbaceous
plants include heath bedstraw, sheep's sorrel and tormentil. It often grades into
wet or dry heathland. Marshy
grassland is a diffuse category that includes areas dominated by purple moor-grass,
often on shallow peat and grasslands with a high proportion of rushes, sedges
and/or purple moor-grass. Marshy grassland generally occurs on level or gently
sloping ground. Areas can be herb-rich and may provide breeding grounds for birds
such as curlew and snipe. Flushes.
Flushes are associated with a flow or seepage of water, occur on gently sloping
ground, are often linear or triangular and may include small watercourses or below
spring lines. They may or may not form peat, but where they do, the peat is often
less than 50cm deep. Bryophytes are normally a conspicuous feature. Flushes reflect
the underlying geology and generally they are acidic or neutral. Acidic
to neutral flushes can be dominated by rushes or even a carpet of mosses overlain
by sedges and/or rushes. They can be species-rich in comparison to other upland
habitats. Characteristic mosses include bog mosses (Sphagnum moss) &/or star moss
(Polytrichum species). The dominant vegetation is usually soft-rush and/or sharp-flowered
rush. Where there is some enrichment from surrounding areas other plants may occur,
such as sedges, bogbean, bog pondweed, lesser celandine, creeping forget-me-not,
marsh willowherb, marsh violet, marsh pennywort and marsh thistle. Although examples
of upland basic flushes are rare in Lancashire, good examples occur on Leck Fell.
Flushes can be species-rich in comparison to surrounding upland habitats. |