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The wildlife and habitats of Avon
The former county of Avon (now divided into the unitary
authorities of Bath & North East Somerset, Bristol,
North Somerset and South Gloucestershire) is situated in
the south-west region of the UK. The area is bordered by
the Bristol Channel to the west and the counties of Gloucestershire,
Wiltshire and Somerset to the north, east and south respectively.
Ecologically the area is exceptionally
diverse for its size, its varied geology resulting in
the occurrence of a number of distinct landscape types
(some of which are internationally important) supporting
different types of wildlife. These include the Cotswolds,
the Mendips, the Severn Estuary, the North Somerset Levels & Moors,
the Severn Vale, the Gordano Valley and the Avon Gorge.
Altogether around three quarters of the area consists
of open countryside, although over 80% of the population
live in urban areas. The Trust has always recognised the
importance of both urban and rural nature conservation,
and works to promote the value of green space to people
living in all parts of the Avon area.
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Brown's
Folly • photo: Ross Chamberlain |
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Brown's
Folly nature reserve is characteristic of the
southern Cotswolds landscape which forms a dramatic
backdrop to Bath. Overlooking the city across a steep-sided
valley, this site lies on top of a network of limestone
mines (the rock used to build the city) which now
supports a nationally important bat population. |
The
Cotswolds
The Cotswold Hills are designated as an Area of Outstanding
Natural Beauty (AONB) - a nationally important landscape.
The hills are an outcrop of Oolitic limestone extending
from Warwickshire to Bath, through Oxfordshire, Gloucestershire
and Wiltshire; they form the eastern strip of the Avon
area.
The Cotswolds are characterised by limestone grassland,
barley and other arable land, and ancient broadleaved woodland,
where traditional management (eg grazing, sustainable timber
production) has favoured a diversity of wildlife. These
habitats support a number of species which are rare in
Britain, for example clustered bellflower (on limestone
grassland), shepherd's needle (on arable land) and Bath
asparagus (in woodland). However, in the last 60 years
more intensive agricultural practices have resulted in
significant habitat loss, especially of the limestone grassland.
Through our Biodiversity
Project we work with landowners in the Cotswolds to
promote and advise on land management which can benefit
wildlife; this work is currently focusing on declining
arable birds and plants.
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sheep
on Hellenge Hill |
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Hellenge
Hill was bought by the Trust with the support
of the Heritage Lottery Fund. Lying on hard Carboniferous
limestone, with shallow soils and rocky outcrops,
the site's south-facing slopes overlook the Somerset
Levels
& Moors, Brent Knoll, and the Bristol Channel. |
The
Mendips
The Mendip Hills are also designated
as an AONB (see the Cotswolds above), and extend eastwards
from the Bristol Channel, across the edges of Somerset
and North Somerset, towards Frome in Wiltshire. Like
the Cotswolds, the Mendips are formed from limestone
but of a harder type - Carboniferous - which produces
a different, more varied type of landscape, with open
levels, low hills, heathland, plateaux, ridges and steep
valleys.
The part of the Mendips which falls within the Avon area
is particularly important for its south-facing limestone
grassland with maritime influences. At the best sites,
such as Hellenge
Hill and Walborough ,
this habitat supports a number of nationally rare plants
and invertebrates such as Somerset hair-grass, honewort
and spring cinquefoil. Further inland, Dolebury
Warren is one of the most dramatic of the Mendip hillforts,
with exceptional limestone grassland and heath, steep wooded
slopes and fine views over the surrounding countryside.
This reserve is also very important for invertebrates,
with 35 nationally rare species recorded.
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Severn
Estuary |
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The
Severn Estuary has the second highest tidal range
in the world. This produces high tidal scour and
harsh conditions for wildlife, but those species
that can tolerate this survive in abundance. The
estuary's numerous waders attract predators such
as peregrine falcons, which can be seen perched on
the bridges. |
Severn
Estuary
The Severn Estuary runs the length of Avon's coastal boundary,
and is an internationally important wildlife habitat. This
is reflected in its many designations: Site of Special
Scientific Interest; Special Protection Area (under the
EU Directive for Conservation of Wild Birds 1992); Natura
2000 site (under the EU Habitats and Species Directive
1992) and Ramsar site (under the Convention on Wetlands
of International Importance). It is also being considered
for designation as a Special Area of Conservation under
the EC Habitats and Species Directive.
The estuary forms one of the most important inter-tidal
zones in Britain, supporting a wide variety of habitats.
As well as providing feeding grounds for over-wintering
and migratory waders and wildfowl (such as dunlin, redshank
and ringed plover), it also attracts a variety of migratory
fish species (eg salmon, sea trout and twaite), and accommodates
a number of rare plants (eg sea clover, sea barley and
slender hare's-ear). It is however a fragile environment;
its high tidal range carries the risk of flooding and erosion,
and there are other threats from development, pollution
and dredging for aggregates. To address these issues, local
authorities and other organisations on both sides of the
estuary (including local wildlife trusts) are preparing
an Estuary Management Plan.
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Littleton
Brick Pits |
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Littleton
Brick Pits nature reserve, although man-made,
forms part of an important chain of reedbeds lying
close to the Severn Estuary. These reedbeds provide
feeding and breeding grounds for migrating birds
such as reed warbler. |
Severn
Vale
The Severn Vale is the strip of coastal plain between
the Severn Estuary and the Severn Ridge (the ridge running
from the Avon Gorge north-east to Thornbury in South Gloucestershire).
The land is generally less than 10m above sea level, and
lies on estuarine silt on the coast and peat deposits further
inland. The character of the Severn Vale is defined by
the historic management of the land; the construction of
a sea wall and drainage of fields to form improved pasture
land has resulted in a landscape of farmed grassland criss-crossed
by ditches.
Along the coastline river and stream banks run into mudflats
and saltmarsh. This habitat is closely linked to the Severn
Estuary; indeed a band of coastline 1 km wide falls under
the estuary's designation zone and forms an important wildlife
corridor. Further south, where the Vale meets the River
Avon at Avonmouth, the landscape is dominated by industrial
development. However, even in this built-up area networks
of ditches have survived and are still important for wildlife,
notably a population of water voles.
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Puxton
Moor |
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Puxton
Moor (purchased
by the Trust with support from the Heritage Lottery
Fund) is nationally important for its archaeology
as well as its wildlife. The waterlogged nature
of the Levels & Moors means that remains are
often well preserved, and at Puxton Moor there
is evidence of land use and settlements dating
back to Romano-British times. |
North
Somerset Levels & Moors
The North Somerset Levels & Moors are the northern
counterpart to the more widely celebrated Somerset Levels & Moors,
and are very similar in terms of landscape character and
wildlife value. The area also bears close resemblance to
the Severn Vale (see above) and includes the Gordano Valley
(see below); essentially they are all part of the same
strip of reclaimed wetland lying on alluvial silt and peat.
The Levels & Moors landscape
is characterised by flat pasture land drained and enclosed
by networks of ditches (known locally as 'rhynes'). The
patterns of these ditches reflect different periods of
reclamation and enclosure dating back to Roman times.
This man-made wetland landscape is ecologically rich,
with rivers, rhynes and wet fields supporting a tremendous
variety of species, many of which are locally notable
or nationally rare. These include plants (marsh marigold,
ragged robin), invertebrates (great silver diving beetle,
hairy dragonfly), birds (lapwing, snipe) and mammals
(otters, water voles). Although modern agricultural improvements
and intensive drainage have damaged and continue to threaten
the area's nature conservation value, restoration is
possible through raised water level management (see Clapton
Moor below). The Trust works to protect and promote awareness
of this important local landscape through the North
Somerset Levels & Moors Project
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Clapton
Moor |
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Clapton
Moor was one of the first reserves purchased
by the Trust with support from the Heritage Lottery
Fund. Major work has been carried out in order
to raise the water levels on the site, creating
a suitable habitat on the lower fields for breeding
waders such as lapwing, redshank and snipe. |
Gordano
Valley
The Gordano Valley forms the northern
tip of the North Somerset Levels
& Moors (see above), separated from the main part of
this landscape by the Tickenham Ridge. It is bound to
the north-east by the River Avon, and to the north-west
by the Walton Ridge - the coastal ridge stretching from
Portishead to Clevedon.
The Valley has developed as a distinct ecological unit,
partly because it has a self-contained water catchment
area. Its rhynes in particular have developed a unique
range of plant, invertebrate and animal communities which
are of outstanding wildlife value. For example, the Valley
is nationally important for stoneworts. Large parts of
the Valley floor are in conservation management, including
a National Nature Reserve part-owned by English Nature,
and two reserves owned by the Trust - Weston
Moor and Clapton
Moor. The sides of the Valley are also important in
terms of wildlife and local landscape character, supporting
bands of semi-natural ancient woodland such as Weston
Big Wood , as well as blocks of limestone grassland
such as Walton
Common
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Avon
Gorge |
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The
Avon Gorge (together with the Clifton Suspension
Bridge which spans it) is one of the most famous
landmarks in Bristol; few other major cities in the
UK can boast such an outstanding wildlife location
within its boundaries. |
Avon
Gorge
The Avon Gorge extends approximately 3 km north-westwards
from the edge of Bristol's docks at Hotwells, levelling
out before Sea Mills, but with further areas of limestone
cliff occurring further downstream as far as Pill.
The Gorge is designated as an SSSI for its geological
as well as its wildlife interest, and has also been proposed
for designation as a Special Area of Conservation under
the European Habitats Directive. It is of international
wildlife importance, supporting an exceptional range of
plant species including two (Bristol whitebeam and Wilmott's
whitebeam) which are not found anywhere else in the world,
and another two (Bristol rock cress and Bristol onion)
which are not found anywhere else in Britain. The Gorge
is also important for invertebrates and for breeding peregrine
falcons.
The Avon Gorge is managed by the National Trust on the
North Somerset side. On the Bristol side, it is managed
by Bristol City Council in partnership with Bristol Zoo,
WWF and English Nature as part of a major initiative to
secure the wildlife interest of the area and raise awareness
of its importance.
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Brandon
Hill |
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At Brandon
Hill in 1980 the Trust carried out a major
habitat creation project to develop a nature park
in the centre of the city - the first of its kind
in a formal park anywhere in the country. Habitats
include ponds, a wildflower meadow, a butterfly
garden and woodland. |
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Bristol
Centrally positioned within the Avon area and influenced
by the ecologically rich landscapes described above, Bristol
supports a surprising diversity of wildlife. Indeed the
city was at the forefront of the urban nature conservation
movement, and continues to be a major focus for the Trust
through the Bristol
Wildlife Project , which is run in partnership with
Bristol City Council.
A wide range of wildlife sites can be found in Bristol
- from the large estates on the edges (such as Ashton Court,
Blaise Castle and Stoke Park), to numerous 'green spaces'
dotted throughout the city (including parks, gardens, allotments,
cemeteries and sports grounds). Important areas of woodland
have survived the urban sprawl, for example Badocks Wood,
while notable grassland sites include Hawkfield Meadows,
Troopers Hill, and the Downs. The rivers Avon, Frome and
Trym form important wildlife corridors, as well as wetland
habitats in themselves, supporting invertebrates, fish
and birds. Lawrence
Weston Moor is the only true remaining area of marshland
in the Bristol area, while Avonmouth
Sewage Treatment Works provides a stopover for many
species of wildfowl within a heavily industrial area.
Wildlife can be found in even the most built-up parts
of the city, for example on derelict land, road verges
and railway embankments. Buildings can support bats and
nesting birds, while up to eight species of fern have been
recorded growing on walls in the Bristol area.
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