2. Vascular Plants
Much of the restoration work planned for Independent Quarry will be aimed at encouraging the natural colonization of Portland's indigenous flora. Whilst none of these species are unique to the island, the particular assemblage of species is very unusual, comprising typical limestone flora alongside relict woodland species and agricultural weeds. Many of these species exist on Portland as ecotypes adapted to dry and windy conditions, often in more prostrate forms than found elsewhere. This style of growth not only ensures the survival of the plants but also creates warmer conditions on the plants essential for the development of the early stages of insects such as the silver-studded blue.
The species in the lists below have been arrived at by a combination of field observations and literature searches. They include species currently growing in adjacent quarries such as Kingbarrow to the north, Tout and Inmosthay to the west, Withies Croft and Admiralty to the east and Yeolands and Broadcroft to the south.
2a. Pioneer species
These are the plants which have already colonized the quarry, either from seed blown into the area or from plants growing around the perimeter. These are likely to be the dominant species over the next 5 - 10 years, being slowly replaced by a more typical limestone flora in the more stable areas.
click here to view the list of pioneer species in a new window
2b. Paths and disturbed areas
Many of the pioneer species currently found in the quarry will continue to grow around the edges of paths and other areas where there is less competition from other plants. New species will also colonize such areas, spreading from nearby quarries. The table below lists these additional species expected to appear in disturbed areas of the quarry, all of which are already to be found in nearby quarries.
click here to view the list of species expected to colonize disturbed areas in a new window
2c. Grassy banks and bunds in full sun
The tops of any bunds and their south-facing slopes should eventually produce a stable limestone grassland flora, supporting a wide range of species characteristic to Portland and already found in clifftop areas and the older quarries. Some of these species are very rare in Britain and make this habitat the single most important reason for restoring the quarry to a natural state. One species, the Early Gentian, is endemic to southern England. It is expected that this community will take at least 10 years to establish, with some species not arriving until well after this period.
2d. North-facing banks and shaded areas
Whilst many species will be able to grow on all sides of a bund, there are some which will always do better where the soil is cooler and wetter. Planting of trees and shrubs will be concentrated in these areas, so as to limit the shading of the important south-facing slopes.
2e. Exposed rock and scree slopes
Even bare rock will eventually support some plant life, although these areas are the most difficult for plants to colonize due to the lack of soil and exposure to the elements. Two species, the Male Fern and the Harts-tongue Fern will grow in damp, shady rocks, whilst the very rare Maidenhair Fern could colonize shady rock faces.
click here to view the list of species growing in rocky areas in a new window
2f. Ponds
A completely different population of plants will appear around and in any permanent or temporary freshwater habitats. All of the species below have been found in temporary ponds on Portland, mainly in quarries.
click here to view the list of species growing in freshwater habitats in a new window
References for Section 2.
1. Bowen, H. (2000) The Flora of Dorset, Pisces Publications
2. Joint Nature Conservation Committee web site, http://www.jncc.gov.uk
3. Dorset Environmental Records Centre web site, http://www.derc.org.uk
4. English Nature web site, http://www.english-nature.org.uk, Isle of Portland to Studland Cliffs Special Area of Conservation
5. Stace, C. (1997) New Flora of the British Isles, Cambridge University Press