Читать книгу The Isles of Scilly - Rosemary Parslow - Страница 48

Most of the coastland of St Mary’s consists of cliffs, not very high, but spectacular enough at times when gales drive the waves in onto the rocks. In places a few small bays break the coastline and there are two large promontories, the Garrison in the southwest and Peninnis Head in the south. In many places there are granite carns (tors) eroded into extraordinary, fantastical shapes: Pulpit Rock, Tooth Rock and the Loaded Camel are just a few well-known examples (Fig. 30). Above the cliffs and steep slopes along the west coast are typical maritime-cliff plant communities, dense bracken communities on the deeper soils, heather-dominated heath and short grassland on the shallower soils and over rocks. Among the shrub species growing on the coast are both common gorse Ulex europaeus and western gorse U. gallii and scattered patches of broom. Along the coastal edge the maritime grassland sometimes extends inland as a series of pastures that in summer are bright with the yellow flowers of common cat’s-ear Hypochaeris radicata amid a colourful mixture of grasses and forbs.

At Carn Morval, on the steepest part of the coast, part of the nine-hole golf course is perched on a rocky promontory above the slope. The rest of the

FIG 30. Pulpit Rock on Peninnis Head, St Mary’s, May 2006. (Richard Green)

FIG 31. Bant’s Carn on Halangy Down, St Mary’s, probably the best known of the Bronze Age entrance graves in the Isles of Scilly. March 2006. (Rosemary Parslow)

golf course sits high above at the top of the slope, where its manicured greens frequently attract migrating birds. As with the airfield this can be very frustrating for the excluded birdwatchers! Beyond Carn Morval is another area of coastal heath at Halangy Down, where in a carefully tended area of grass and mown heather is an important archaeological site managed by English Heritage. These are the remains of an Iron Age/Romano-British village settlement of many small buildings, now marked only by low walls, and the ridges denoting earlier field systems on the nearby slopes. At the top of the hill is Bant’s Carn, a large Bronze Age entrance grave, one of the best examples of its type in Scilly (Fig. 31). The whole closely managed and mown site is quite species-rich, and even the walls and banks of the ancient village have an interesting flora that includes western gorse, hairy bird’s-foot-trefoil Lotus subbiflorus, subterranean clover Trifolium subterraneum growing on and among the stones. The turf is also full of chamomile Chamaemelum nobile, deliciously scenting the air as you explore. Ruts on some of the paths nearby have a miniature flora of toad rush Juncus bufonius and sometimes in spring an unusual but very inconspicuous alien called Scilly pigmyweed Crassula decumbens. This is a South African species, probably introduced accidentally with other plants to the nearby Bant’s Carn farm. Only very recently has it apparently started to spread away from the farm, and it can now sometimes be seen on the path leading up the hill towards the golf course.

Just beyond Bant’s Carn Farm the land slopes down to the sand dunes that form the northern tip of the island at Bar Point. The dune system is very disturbed. Part has been quarried and there is also a part used as a dump. Much of the dune system has become colonised by bracken and bramble Rubus agg. communities. There are areas of scattered gorse bushes, where both the rare balm-leaved figwort and Babington’s leek Allium ampeloprasum var. babingtonii can be found. Closer to the quarry and the dump some plants of garden origin have become established so that you can come upon bear’s breech Acanthus mollis, montbretia Crocosmia x crocosmiiflora, fennel Foeniculum vulgare and even the giant rhubarb plant Gunnera tinctori. Somewhere in the dunes near here the fern moonwort Botrychium lunaria used to grow under the bracken. It was last recorded by Lousley in 1940, and may have been lost when the area suffered major disturbance some time after 1954, from various activities including relaying the submarine telegraph cable, winning sand and dumping rubbish. Since then, despite much searching, there has been no further sign of the moonwort.

More areas of bracken communities follow the northern coast of the island all the way round from Bar Point to Innisidgen, Helvear Down, and right down to the narrow inlet at Watermill Cove. On this northern part of the coast there are areas of pine shelterbelts, which extend right round to the eastern side of the island, and large stretches of beautiful heathland near the coast. Patches of tall gorse with an understorey of lower heathland plants grow along the sides of the path as it continues around the coast, also appearing anywhere there are breaks in the bracken cover.

Close to the coast path are two impressive entrance graves, Innisidgen Upper Chamber and Innisidgen Lower Chamber. Around the barrows the vegetation is kept regularly mown, resulting in species-rich lawns of grasses, sedges and typical heathland plants, demonstrating the potential richness of the vegetation if the surrounding overgrown areas could be restored and perhaps maintained by grazing. Beside the path what appears to be a low wall is the remains of the former Civil War breastworks, half-buried in dense vegetation. As the path drops down the hill into Watermill Cove, the Watermill Stream runs into the sea through mats of dense hemlock water-dropwort, fool’s-water-cress Apium nodiflorum and a group of grey sallow Salix cinerea oleifolia trees. Just round the corner there are steep cliff exposures along the section of the inlet at Tregear’s Porth, an important geological site, notified as the Watermill Cove Geological Conservation Review site. From here the path continues along the coast, and another one follows the Watermill Stream inland along the heavily shaded lane lined with ferns.

The mosaic of heathland, gorse, bracken and bramble continues along the coast past Mount Todden. In places there are more sections of Civil War fortifications and much earlier archaeological sites. Below the cliffs at Darity’s Hole is a very important underwater site where many unusual marine species have been recorded. Towards Deep Point there is an area of ‘waved heath’ (see Chapter 10), and elsewhere there are patches of heather still beneath the taller bracken, as well as around rocks and paths. Where there is a freshwater seepage down one of the slopes, the understorey consists of broad buckler fern Dryopteris dilitata, occasional soft shield-fern Polystichum setiferum and marsh pennywort Hydrocotyle vulgaris. Near Deep Point in an area of short coastal turf careful searching may reveal another rare lichen, ciliate strap-lichen Heterodermia leucomela. It was at Deep Point that at one time the islanders disposed of cars and other rubbish over the cliff. Although the practice has been stopped, the remains of vehicles at the bottom of the cliff in deep water apparently now support a rich marine flora and fauna! At Porth Wreck there is a former quarry in the cliff, often the place to find unusual casual plants.

Porth Hellick Down is one of the largest areas of wind-pruned waved heath on St Mary’s. Much of the gorse among the heathers in the area is western gorse, with flowers a deeper golden colour than the yellow of common gorse. Around the Porth Hellick barrow Ancient Monument is a closely mown circle of grass starred with flowers of chamomile, tormentil Potentilla erecta and lousewort Pedicularis sylvestris, as well as stunted bell heather and other typical heathland plants. Similar vegetation covers the burial mound with a dense sward of low grasses and flowers.

South of the deep bay of Porth Hellick lies the open heathland of Salakee Down with the rather eroded outline of Giant’s Castle, an Iron Age hill fort. At Salakee Down is a beautiful stretch of coastal grassland and waved heath, again with common gorse and western gorse, bell heather, ling and other heathland species (Fig. 32). Close to the Giant’s Castle are a number of small damp and seasonally waterlogged pits with wetland plants including lesser spearwort Ranunculus flammula, bulbous Juncus bulbosus and soft rushes J. effusus as well as small adder’s-tongue fern Ophioglossum azoricum and royal fern Osmunda regalis. Further towards Porth Hellick are more areas of waved heath, where the heather is deeply channelled into ridges by the wind. These coastal areas are among the best places to look out for migrating birds, especially wheatears Oenanthe oenanthe, and even migrating butterflies such as clouded yellow Colias croceus. These ‘downs’ are also home to green tiger beetles Cicindela campestris, rose chafers Cetonia aurata and other insects.

Between Giant’s Castle and Blue Carn one of the runways of the airport

FIG 32. An example of ‘waved heath’ can be seen near Giant’s Castle, an Iron Age cliff castle. Salakee Down, June 2002. (Rosemary Parslow)

interposes itself into the cliff edge. Not a place to linger, although the system of traffic lights at the top of the slope on the edge of the cliff warns of the imminent approach or departure of aircraft. The airport is one of largest areas of open grassland on St Mary’s, but access is restricted due to safety considerations. Most galling for the birdwatchers, as the mown grass attracts rare plovers, wheatears and other birds of open habitats. Usually some kind of viewing place is negotiated each autumn so that birdwatchers can see part of the airfield without interfering with the business of flying.

As you round the corner into Old Town Bay you pass the narrow rocky promontory of Tolman Point, between the bay and Porth Minick. Here there are maritime grassland and cliff communities and a small triangular group of planted shrubs including shrubby orache Atriplex halimus. On the Old Town side of the headland Hottentot fig and rosy dewplant Drosanthemum roseum grow over the rocks and grassland, in places completely submerging native species.

The next headland round the coast is Peninnis Head, the southernmost point on St Mary’s (Fig. 33). This rocky promontory is important, with habitats that support rare plants and lichens. The impressive weathering of the granite tors and the lack of glacial features also contribute to the geological significance of the site. In the nineteenth century Peninnis ‘was considered one of the pleasantest places on the island by visitors; it was a large open downs with no hedge on the west side of it until you got halfway to Buzza Hill, and it was covered with long heath and wild flowers of various kinds which made it very pleasant in summer time’ (Maybee, 1883). The headland is still popular with visitors, who enjoy the dramatic scenery of massive granite carns eroded into natural sculptures and, among the rocks and tumbled boulders, the squat little lighthouse on the Head overlooking St Mary’s Sound. This is the place where the islanders have lit ceremonial bonfires in the past, and it was also the site for the Millennium beacon on 1 January 2000. There are the usual stretches of coastal grassland and maritime heath over the granite, with western clover Trifolium occidentale and two species uncommon elsewhere, spring squill Scilla verna and wild thyme Thymus polytrichus at one of its few Scilly locations. The most exposed edge of the headland is noted for its rare lichen flora including Ramelina siliquosa, Roccella fuciformis, R. phycopsis, golden hair-lichen Teloschistes flavicans and ciliate strap-lichen. To reach the Peninnis headland there is either the track around the coast or the central track from Hugh Town, King Edward’s Road, bisecting the cultivated centre of the headland, with arable fields and pastureland either side. The soils here are deep and less sandy than elsewhere

FIG 33. Peninnis Head is a jumble of extraordinary granite tors. May 2005. (Rosemary Parslow)

so a different range of arable weed species is found among the crop: these include some of the goosefoots Chenopodium spp. as well as the ubiquitous corn marigold Chrysanthemum segetum, docks Rumex spp., shepherd’s-purse Capsella bursa-pastoris and sow-thistles Sonchus spp.

Above Hugh Town is the high, rocky promontory of the Hugh, almost completely surrounded by the granite walls of the early fortifications of the Garrison. Here the long history of the Garrison is marked by an array of buildings, defence works and other structures. English Heritage manages most of the historic buildings and walls that form the Ancient Monument. There are some areas of semi-natural vegetation within the fortifications managed by the Wildlife Trust, mainly areas of bracken and bramble thickets, rough heathland and mown grassland. Some of the windbreaks of Monterey pine have died but there are still more pines and other trees on the eastern flank of the promontory. On the slopes of the hill Babington’s leek and balm-leaved figwort both grow among the bracken and bramble. And a few stands of the Nationally Scarce wild leek Allium ampeloprasum can also be found here, probably overlooked because they were assumed to be the commoner Babington’s leek variety. On the exposed southern side of the Garrison there are more maritime habitats from below the walls to the rocky shore (Fig. 34). There is also a row of tiny abandoned gardens perched on the edge of the cliffs. The thin soils on top of the massive granite walls often support a therophyte community (therophyte plants overwinter as seeds and germinate in spring) of dwarfed species of grasses and forbs similar to that seen on natural granite outcrops around the coast. Where they are permitted to flourish, small ferns such as sea spleenwort lodge in the mortar between the granite blocks, as do other plants that are usually found in rock crevices on the cliffs: Danish scurvygrass Cochlearia danica, pearlworts Sagina spp. and thrift Armeria maritima are frequent examples.

Other interesting species of ferns and other plants grow on both sides of the high granite walls. Between the ramparts are mown lawns that in some places are still typical of coastal grasslands with a tight sward of fescues Festuca spp., buck’s-horn plantain Plantago coronopus, sheep’s sorrel Rumex acetosella, small-flowered catchfly Silene gallica, western clover, rough clover Trifolium scabrum and other clovers. Besides the usual resident birds, the coastal area and the shelterbelts are good venues at bird migration times to look out for species such as wheatear, wryneck Jynx torquilla and black redstart Phoenicurus ochrurus. One section of wall near the Woolpack Battery is remarkable for the hundreds of autumn lady’s-tresses orchids Spiranthes spiralis that flourish there just at eye level in late summer.

FIG 34. Exposure to southern gales restricts growth on the seaward side of the Garrison walls to lichens, tiny ferns and a few other plants. November 2002. (Rosemary Parslow)