Sefton Coast Partnership	Shoreline Management	Nature and Wildlife	Coastal Heritage	Visiting the Coast	Students and Teachers	Coastlines

Magazine Coastlines Archive Subscribe Games

Summer 1994 Dune Heath – A special habitat on the Sefton Coast Article by Peter Gateley, Local Botanist Of the many plant communities that have developed on the Sefton dunes one of the rarest is dune heath. This distinctive vegetation type is dominated by heather, also known as Ling (Calluna vulgaris), which thrives where soils are strongly acidic. Dune heath patches are the most noticeable and appreciated in autumn when the heather flowers in a haze of purple. On the face of it, it seems odd that such acid loving species should come to dominate areas of these dunes, which are noted for their high calcium content and the wide range of lime-loving plants found here. The sand that forms this dune system was washed-down onto the bed of the Irish Sea by the melting glaciers of the last Ice Age. Tides and waves bring this sediment onto the foreshore from where it is blown inland. Because the sea here is rich in marine molluscs many shell fragments (composed of calcium carbonate) are also blown inland so that freshly deposited sand has a pH value of up to 9. The sand/shell mix is exposed to the natural processes of soil formation, and rainfall over many years leaches out the calcareous component of the sand leading to increased acidification. As long ago as 1925 the renowned pioneer dune expert, Dr Salisbury, calculated that it took about two centuries for sand reaching the coast to fall in pH value to 6.4. More recent work has shown that our sand dunes have been accumulating over the last 4,000 years, possibly since the sea settled near to its present level (after the post glacial fluctuations) about 5500 years ago. At one time large stretches of the oldest eastern-most dunes would have had the right conditions for primary dune heath formation. However, as the accompanying map shows, nothing now exists of this eastern fringe of dune, which has either been buried or strongly modified by urban development and agricultural activities. The vegetation history of this area can be gleaned from analysis of pollen from samples obtained by borehole drilling. This evidence indicates extensive colonisation by heather in this zone prior to development. These heaths and dune woodlands would have been relatively easy for early human settlers to manage, by burning, and would have been much dryer than the adjacent mosslands and more productive than the open sand dunes. Pollen samples also show evidence of weed species typical of agricultural use following changes to the natural vegetation brought about by human activities. Although it is probable that all the primary dune heath has been permanently lost, there are areas of Heather today thriving along sections of the eastern fringe of the still open dunes. These areas have been surveyed and their vegetation make up and structure recorded. The main areas are shown on the map :-1)Larkhill Lane, 2)Formby Golf Course, 3)Freshfield Dune Heath, 4)Cloven-le-Dale, 5)Woodvale Airfield, 6) Southport and Ainsdale Golf Course. Of these areas 1 and 3 are open to the public, the remainder are private and restricted. There is a remarkable outlier surviving in the grounds of St Anne's Church in Timms Lane, indicating a formerly much more extensive cover of this vegetation type. Heather cover naturally waxes and wanes in cycles of growth and decay: the survey recognises all stages, from vigorous young colonising heather to the oldest stands collapsing and decaying in parts of Woodvale Airfield. Some areas of Heath are quite intensively managed, with stands on the golf courses being regularly cut back to less than 10cm in height. The oldest leggiest specimens in unmanaged areas can reach more than 1.2m! The varying states of heather development affect other species able to co-exist in the community, for example in the densest, maturing Heather cover very little else can survive in the strongly-shaded, strongly-acidic often very dry conditions whilst more open canopies hold a range of other species. Other plants most frequently found with heather are Sand Sedge, various grasses:- Sheep’s Fescue, Wavy Hair Grass, Common Bent and Yorkshire Fog, the mosses Hypnum cupressiforme and Dicranum scoparium, Gorse and a range of species of the lichen genus Cladonia. All of these species are able to cope with the acidic conditions found in these communities; values as low as pH3.31 were recorded, with most samples from under the Heather canopy being in the range of pH 3.5-4.5. These conditions do not favour intrinsically rich plant communities; however this vegetation is so unlike any other on the dunes, that it adds an extra element of diversity to the Sefton coast . These surviving areas of Dune Heath also show one of the final stages in sand dune succession, providing a valuable scientific and educational resource. Dune heath communities provide a home for a range of plant species found only in acidic habitats. As well as the species listed above, other plants usually found nowhere else in the Sefton dunes include :- Common Bird’s Foot, Heath Rush, Heath Bedstraw, Heath Grass, Moor Matgrass, Grey Hair-grass, Early Hair-grass and Tormentil. It is highly likely, also, that the Heather stands support populations of insects and other invertebrates not found in any other dune vegetation community. Following this article a study has been completed by the National Museums and Galleries on Merseyside. Data from the dune heath vegetation survey has been collated and analysed with a view to formulating detailed management proposals. Already it has been found that significant areas of Dune Heath are being shaded out by developing scrub and woodland, also the occurrence of of Heather stands in the various stages of development adds to diversity. It is apparent that co-ordination of management is desirable on a coast-wide basis to enhance chances of continued survival of this interesting community, with all stages of development represented within the Sefton dune system. Home Page - Top www.seftoncoast.org.uk

-previous page-