The woodland at Silverglades is growing on limestone pavement, a rare environment in England and protected by law.
Limestone pavements are unique habitats. Carboniferous limestone, laid down under a warm sea about 350 million years ago, became exposed as the land shifted and seas retreated. During the last Ice Age (some 10,000 years ago), this rock was deeply scoured by creeping glaciers; it has since weathered to produce solid blocks or paving stones of bare limestone (clints), separated by an intricate pattern of fissures (grikes).
Less than 3,000 hectares of limestone pavement remain in the UK, most of it in the Yorkshire Dales and on the edge of the Lake District. Elsewhere in Europe, limestone pavement is found only in The Burren in Western Ireland, in the high Alps and in parts of former Yugoslavia. On a global scale, limestone pavement is rare.
The unique conditions on limestone pavements support many different plants and animals. Not surprisingly, plants of rocky habitats are common such as wall-rue, maidenhair spleenwort and wall lettuce. Rarer species include limestone fern, angular Solomon’s-seal, dark-red helleborine, juniper and rigid buckler-fern.
Lowland pavement is often wooded, but even on the more exposed, higher altitude pavement, many species typical of the woodland floor, such as herb-Paris and dog’s mercury, flourish in the sheltered, humid micro-climate of grikes.
A variety of insects feed on plants associated with limestone pavement including the threatened high brown and pearl-bordered fritillary butterflies and the wall mason bee. Birds such as skylark, wheatear, meadow pipit and chiffchaff frequent the pavements.
Traditional uses of limestone for walling, gateposts and agricultural improvement have had only a minor impact on limestone pavement. Much more widespread loss and destruction of this irreplaceable resource has resulted from the quarrying of ‘water-worn limestone’ to satisfy the demand for its use in garden rockeries. Intensive grazing and inappropriate management have also taken their toll.
Only 3% of the UK’s limestone pavements are thought to have escaped damage. This precious habitat, millions of years in the making, is all too easily destroyed in a matter of hours. Once gone, it is lost forever, together with the plants and animals which depend on it.
Under the Wildlife and Countryside Act (1981) all major and most minor areas of limestone pavement in England (including that at Silverglades) is subject to protection measures known as Limestone Pavement Orders. Removal of rock becomes a criminal offence under the Wildlife and Countryside Act and anyone taking pavement from a designated site can be prosecuted and fined, even if the rock they remove is loose or lying in a field.
Many of the limestone pavement features at Slverglades can also be seen at the Cumbria Wildlife Lancelot Clark Storth reserve, Hutton Roof, a few miles north of Silverglades.
Page last updated 2018/09/10/13:00 by Martin R