Enviroment

The Wildlife of the Avon Gorge

The Avon Gorge is special when it comes to wildlife. With a micro-climate that’s a degree or so warmer than the surrounding landscape, the steep rocky slopes of the gorge have preserved a unique wilderness at the edge of a busy city. The Gorge supports 30 nationally rare and scarce plants, making it one of the top botanic sites in the UK. Species of plants have survived in the wooded and grassy areas of the Gorge that have either disappeared elsewhere or are rare. Others have evolved in the isolation of the Gorge, so that they are now quite unique versions of their species including Bristol rock-cress and the Bristol white beam.  Scarce wildflowers found here include wild thyme, rock rose and several native orchids. It’s been designated as a Site of Special Scientific Interest and a Special Area of Conservation

Libby Houston

Libby Houston

Over the years climbers have collaborated with conservation groups and Bristol City Council to help clear parts of the cliffs of scrub and ivy – vigorous plants that smother and squeeze out the rarities if left unmanaged. In January 2013 Natural England authorised an expert ClimbBristol volunteer work-party to remove loose rocks and damaging scrub from a key climbing cliff in Avon Gorge.  They worked with local botanist and climber Libby Houston who believes this type of clearance is: ‘valuable for conservation as well as climbing.’

The Avon Gorge is also home to rare horseshoe bats and ravens, and since 1990 a pair of peregrine falcons have found the sheer cliffs to be a place where they can safely breed. Since 2009 volunteers from the climbing community have provided vital practical help to the British Trust for Ornithology for the annual ringing of the peregrine chicks. And during the breeding season climbers keep well clear!

Teddy Llovet

Teddy Llovet

The Avon Gorge Wildlife Project (http://www.avongorge.org.uk/aboutus.php?ContentID=1) was launched in 1999 to manage its conservation, monitor and survey the rare plant and animal species, and to encourage public understanding. Part of the management plan has been to introduce a small herd of goats to the Gully to help restore wildlife rich grassland by eating the scrub, which if left unchecked, will shade out the rarities.

These are some of the plants that climbers can find on their way up and at the top of routes: (as compiled by botanist Libby Houston)

Avon Whitebeam – Avon Gorge endemic – only here in the world (above the easy way up to the Gallery Roof)

Libby Houston

Libby Houston

Bristol Onion (aka Round-headed Leek) – Nationally Rare. Only found in the Avon Gorge in UK; otherwise a few in Jersey, & round Mediterranean  (on easy way up to Gallery Roof) [& in Goats’ Gully]

Libby Houston

Libby Houston

Bristol Rock-cress – Nationally Rare. Avon Gorge is the only natural site in British Isles, otherwise found in the French Alps/Pyrenees –  coincides with climbers at top of Sea Walls; Main Wall especially rocks below Corpse – Maltravers – Dawn Walk – Dexter; Lunchtime Ledge, cliff-top above; Easy Slab; & above Harvey’s Wall; also Quarries on Leigh Woods side (& non-climbing sites)

Libby Houston

Libby Houston

Bristol Whitebeam – Avon Gorge endemic, & best-known because of its name, probably oldest endemic Whitebeam here. Nearly 300 of them & some beautiful conspicuous ones on cliff tops, nice one on top at N end of Main Wall, Liverbird Buttress, Battleship Buttress (otherwise classic cliff tops ones on wooded cliff tops in Leigh Woods)

Compact Brome – Nationally Rare native & thought (but not by everyone) to be native in Avon Gorge . Bottom of Main Wall & rocks below Corpse – Maltravers – Mercavity – Steppenwolf – Dawn Walk; also Quarries on Leigh Woods side [and railway line]

Dwarf Mouse-ear – Nationally Scarce, a bit in decline here lately – coincides with climbers at top of Sea Walls & bottom of Giant’s Cave Buttress, maybe more….

Libby Houston

Libby Houston

Dwarf Sedge – Nationally Scarce. Ancient limestone grassland indicator/key species. Lovely titchy inconspicuous thing, but a nice shade of green & has  matchstick flowers in late March – coincides with climbers on upper ledges & top of Nightmare & that end of Sea Walls; top edge of Main Wall/Main Area

Libby Houston

Libby Houston

Grey-Leaved Whitebeam – Nationally Scarce but key perpetrator of new Whitebeam species. Not many on Bristol side, just above Desecrator & all the meshed face above Fickle Finger of Fate (otherwise Leigh Woods quarries) PHOTO

Hutchinsia – smallest, earliest Nationally Scarce annual. Near climbers at top of Morpheus/Nightmare & N end Main Wall, top of Corpse & rocks below, upper ledges of Amphitheatre, & Gallery Roof screen

Libby Houston

Libby Houston

Little Robin – Nationally Scarce annual, normally green but goes an amazing scarlet in fruit & probably a bit stressed. Good population all along the rocks below Main Wall routes, especially between Mercavity and Evening Light – it’s probable that climbers brought it here from Suspension Bridge Buttress; all over Amphitheatre as well.

Libby Houston

Libby Houston

Observatory Whitebeam – identified by Libby Houston. All the Whitebeams below the Observatory & nearly all on the Amphitheatre cliffs. Avon Gorge endemic. Lush fruit. Nowhere else in the Gorge or the world.

Libby Houston

Libby Houston

Robertson’s Whitebeam – a one-off hybrid named in honour of Ashley Robertson, the chap who sorted out Sorbus DNA which made it easier to declare new species in the face of sceptics, & who found this one by chance . It’s threatened by rockfall from above and landslip below, below Battleship Buttress, but grafts have been taken.

Rock Stonecrop – Nationally Scarce, only on Amphitheatre rocks here, & possibly this is a bit of a genetic weakling PHOTO

Spiked Speedwell – Nationally Scarce, it’s possible that the Avon Gorge population is the best in Britain. Very long-lived. You could have a plant 10,000 yrs old, but not where it’s been quarried. Again only on Amphitheatre (& railway cutting opposite) – but throughout except not Suspension Bridge Buttress itself, bar the abseil point where there are lots there.

Libby Houston

Libby Houston

Spring Cinquefoil – Nationally Scarce. Coincides with climbers in Amphitheatre, especially below Giant’s Cave Buttress

Libby Houston

Libby Houston

White’s Whitebeam – Nationally Rare. Only in Avon Gorge & Shorn Cliff in the world, & not very healthy. Nice ones at the bottom of N end Main Wall, & this one actually on the cliff, like a pitchfork.

Libby Houston

Libby Houston

Wilmott’s Whitebeam – Avon Gorge endemic. Not as famous as Bristol Whitebeam because of the name, & it’s harder to recognize – except it’s very upright & upward-growing. Very recently it moved in to the bottom of Main Wall, on the way up to Mercavity etc. Otherwise doesn’t coincide with climbers on the Clifton side.

Libby Houston

Libby Houston

Geology

It took geologists a long time to work out why the River Avon had chosen its path through hard limestone rather than the easier way through Aston vale towards Weston Super-mare.  The current theory is that during the last ice age the river channel became blocked by ice. 20,000 years ago, as the ice melted, torrents of meltwater scoured out a 2.5km long and 90m deep gouge through a series of Devonian and Carboniferous limestones and sandstones.

The Gorge is seen as an important site by geologists as it reveals millions of years of the Earth’s history. The fossil shells and corals that can be found in the gorge show that it the limestone was formed in shallow warm seas about 350 million years ago in the Carboniferous era.

Massive earth movements tilted the bedrock to form a huge fold which we now know as the Mendip hills. It only takes a 10 minute walk along the River  to see this history: from the  oldest  limestones in the Unknown Area, through the crinoid-rich  limestones and dolomite of  Sea Walls,  to the youngest coral oolites of Main Wall, the Amphitheatre and Suspension Bridge Buttress.

For more info look at:

http://www.naturalengland.org.uk/publications/nca/bristol_avon_valleys_and_ridges.aspx

http://www.naturalengland.org.uk/ourwork/conservation/geodiversity/englands/counties/area_ID31.aspx

 

James F Clay

James F Clay

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