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Habitats in Britain
& Europe
1 - Forests and woodlands
2 - Grasslands and scrub
3 - Heathlands and moors
4 - Coastal habitats
Forests
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Hazel coppice with scattered mature oaks - a transitional
woodland habitat ideal for species such as Pearl-bordered
Fritillary and Duke of Burgundy. |
Transitional woodland
There are many different types of woodland in Britain, most of which
are plantations of oak, beech or conifers, managed by the government
agency Forest Enterprise.
Only a small number of
woods are now privately owned. Some of the latter are managed for
timber, some for recreation, and some ( mostly nature reserves ) are
coppiced.
In coppiced woodland the trees are
cut near the base of the trunk to stimulate the growth of new
shoots, used for hurdle making or charcoal production.
These coppiced woodlands
are of considerable value as butterfly habitats, as the regular
cutting regime stimulates a continuous stable supply of foodplants
and nectar sources, and creates a warm sheltered environment that is
ideal for butterflies.
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Sweet chestnut,
cut near base of trunk to stimulate growth of new shoots.
After about 8 - 12 years the shoots reach a diameter of about
8 inches, and are harvested again. |
Trees which are traditionally coppiced
include hazel, sweet chestnut and hornbeam.
Hazel coppice is particularly valuable as a butterfly and moth
habitat because the fallen leaves decompose quickly. This allows
sunlight to reach the ground, encouraging the germination of wild
flowers. Hornbeam and sweet chestnut coppice in contrast tends to
have a semi-permanent layer of dead leaves carpeting the forest
floor, reducing light penetration so the habitat is far less rich in
herbaceous plants.
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Oak woodland with coppiced hazel.
The fallen hazel leaves decompose very quickly, exposing the
ground to direct sunlight, which stimulates the germination of
violets, primroses, wild strawberry, bugle, trefoils and other
larval foodplants. |
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Sweet chestnut leaves decompose
slowly, leaving a year-round carpet of dead leaves beneath the
trees which stifles the germination of wild flowers.
Consequently butterfly diversity and abundance is considerably
lower than in actively coppiced hazel woodlands. |
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Oak / ash woodland with coppiced
hazel. This small damp but sunny glade provides ideal breeding
habitat for Orange tip, Green-veined White and Speckled Wood.
Small clumps of nettles growing in sheltered sites like this
are chosen for egg-laying by Comma and Peacock. |
In most coppiced woodlands a small
number of "standard" trees are allowed to reach maturity. These
include oak, ash and beech, sometimes supplemented by wych elm, lime
or field maple. The shrub layer also invariably includes a number of
incidental species such as holly, hawthorn, blackthorn, buckthorn,
birch and sallow. A coppiced woodland thus comprises a vast range of
trees, shrubs, herbs and grasses, providing foodplants for many
caterpillars, and a variety of nectar sources for adult butterflies.
Butterflies confined
mainly to transitional woodland habitats include Wood White, Heath
Fritillary, Pearl-bordered Fritillary, and Small Pearl-bordered
Fritillary. Many other species also use such places as supplementary
or secondary habitats. These include Duke of Burgundy, Grizzled
Skipper, Dingy Skipper, Holly Blue, Orange tip, Green-veined White,
Brimstone, and ( in Scotland ) Chequered Skipper.
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A
recently cleared area of hazel coppice in mid March. By late
April the ground will be carpeted with violets, bugle,
wood anemone, primrose and many other
wild flowers essential as larval foodplants or as nectar
sources for adult butterflies. Pearl-bordered Fritillaries
love habitats like this. |
When coppiced
woodland reaches maturity the amount of light reaching the forest
floor greatly diminishes, the herb layer virtually disappears, and
the only butterflies able to continue breeding are Speckled Woods. As one area of the
wood matures and shades out the flowers, emerging butterflies of
other species will
disperse in search of other more suitable breeding areas.
Unfortunately most butterfly species have very poor powers of
dispersal, and rarely travel more than about 100-200 metres from
their emergence site. It can take several years for successive
generations to find a new breeding area. During the intervening
years they often survive in only very low numbers, breeding along
the edges of sunny woodland rides. Woodland managers can make things
easier for them by creating a network of wide sunny rides which can
be used as migration corridors.
If butterfly
diversity and abundance are to be sustained it is vital that the
coppice cycle is maintained. This ensures a varied age structure and
diverse range of habitats, rich in the foodplants and nectar sources
on which butterflies depend.
Conditions similar to those of
coppiced woodland can be found in other transitional habitats such
as the corridors of regularly cleared woodland beneath electricity pylons, or
sunny railway embankments in wooded areas.
Ancient woodland
The New Forest in Hampshire is a unique area now designated as a
National Park. It covers an area of over 57,000 hectares, and is
largely managed by the government agency Forest Enterprise. It
comprises of a mosaic of heathland, mires, pasture land, conifer
plantations, and ancient oak / beech forest.
Entomological
records indicate that a century or two ago it was the richest area
of Britain for butterflies, supporting a vast number of woodland,
heathland and grassland species. Sadly that is no longer the case -
wild ponies and domestic cattle have been allowed to wander within
the forest Inclosures, and grazing has been so intensive that the
herb layer of much of the area has disappeared, causing butterfly
populations to be decimated.
Recently
a more enlightened management policy has been introduced and the
situation is improving - a small number of Inclosures are now
beginning to regain their former glory, with violets, bugle and
other wild flowers reappearing. In these Inclosures Pearl-bordered,
Dark Green and Silver-washed Fritillaries are flourishing.
Mature oak woodland
in the New Forest provides habitat for Purple Hairstreak, White
Admiral and Silver-washed Fritillary, while the wider rides and
clearings are home to Pearl-bordered Fritillaries, Dark Green
Fritillaries and grassland butterflies such as Browns and Skippers.
Broadleaf and conifer plantations
The vast majority of modern forests in
Britain are plantations.
Some are in private hands but most are state owned, and managed by
Forest Enterprise.
These
forests are typically broken up into small blocks of between 1 - 6
hectares in area, divided by firebreaks. Often several species of
tree will be planted in the forest, but each individual block will
consist of a monoculture of conifers ( pine, spruce, larch, cypress,
fir etc ), or less commonly broadleaves ( oak, beech or poplar ).
Butterflies cannot survive in the gloom within modern pine plantations,
but when the trees are felled
and sunlight once again reaches the forest floor, millions of
dormant seeds germinate, carpeting the ground with violets, trefoils
and bugle - the nectar sources and larval foodplants of butterflies.
This abundance of food sources however is very short-lived, because
within about 4 or 5 years, the new trees will have grown
sufficiently to shade out the herb layer.
If butterfly colonies are to
survive, it is vital that plantations are managed so that new
clearings are created every year or two, to supply a continuous
availability of suitable breeding habitat. It is also essential to
give the butterflies a helping hand so that they can
easily and quickly find their way to suitable new areas of breeding habitat.
This can be done by creating wide sunlit rides which act as
migration corridors between the forest blocks. Scalloping ride
edges, and enlarging intersections provides additional temporary
habitats where butterflies can breed.
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Pine plantations
are dark dismal places where butterflies cannot survive |
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In larch
plantations higher levels of sunlight reach the forest floor,
encouraging the growth of bracken and bramble. Mown rides allow violets and other larval foodplants to grow. |
Timber nowadays offers little
financial return, and this fact, together with increasing public
demand for leisure facilities has brought about a change in
Government forestry policy. The tendency now is for the plantations
to be periodically thinned, rather than clear-felled and replanted,
and for the woodlands to become retained for their amenity value -
many former timber plantations are now Country Parks.
The edges of the tracks and rides in
plantations are often planted with a narrow strip of amenity broadleaves such as
oak, sallow, buckthorn, field maple and wych elm. There are also
often a few ornamental species such as scarlet oak,
sycamore, lime and cherry.
Most woodland blocks are edged with
drainage ditches and small embankments, while other habitats may
include small semi-permanent glades, grassy avenues, riversides and
ponds. A modern woodland is thus comprised of a multitude
of sub-habitats which support many native trees, shrubs and bushes.
The structure of the woodland usually ensures that there is an
abundance of sheltered sunny areas, supporting a rich variety of
grasses and wildflowers growing along the ditches, embankments and
ride edges.
Wide grassy forest
rides
can be thought of as "linear meadows". Vetches, trefoils
and violets growing along the ride edges are used as larval
foodplants by many species, as are buckthorn, sallow, dogwood and
holly. Nectar sources also abound - hemp agrimony, thistles, bugle
and bramble each attracting numerous butterfly species.
The consequence of this rich botanical variety
is that many plantations in southern Britain support
not only true woodland butterflies such as Silver-washed Fritillary, Purple Emperor,
White-letter Hairstreak, Purple Hairstreak and White Admiral, but also often have
populations of species normally associated with scrubby grassland -
e.g. Dark Green Fritillary, Brown Hairstreak, Grizzled Skipper, Dingy Skipper,
Large Skipper,
Marbled White,
Meadow Brown, Ringlet and Gatekeeper.
Most species however exist at very low
densities and there is an absolute and immediate need for
landscape-level conservation management to be implemented to prevent
their continuing decline and ultimate extinction.
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