The Holme timber circle is situated between high and low water marks on the beach at NWT Holme Dunes Nature Reserve. This article puts the circle into context relative to coastal processes and the nature reserve. Holme Dunes is a site of great importance for wildlife and this is reflected in the designations which have been conferred on it - National Nature Reserve, Site of Special Scientific Interest, Wetland of International Importance under the Ramsar convention, Special Protection Area (for its bird interest) and candidate Special Area for Conservation. Some of these designations provide legal protection for the habitats, mainly regarding land-use and planning law. Additionally, some of the species found on the reserve such as Little Terns and Natterjack Toads are specially protected under National and European law. It is managed by a nature conservation charity, Norfolk Wildlife Trust.

The two greatest threats to the site's integrity are from the sea itself and from visitor pressure. Sand, shingle and mud have been transported by sea and wind action to form the substrates of the site and dune and saltmarsh vegetation have developed on these over many years. Now the same processes that built up these deposits are working to remove them. Beach levels have dropped by 1-2 metres in the past 10 years allowing larger waves to impact higher up the beach and directly on the dunes during storm tides.

One theory explaining this is rather complex, but points to the construction of a mile long sea wall in the 1860's. This shut the sea out of the vast saltmarsh behind the dunes and allowed it to be 'reclaimed' for grazing and, later, agriculture. Water flowed out of this saltmarsh into the open sea and interrupted the drift of sediment along the coast to create a large area of deposits as a delta bulging out from the shore.

Factbox
The height and therefore the energy of waves depend on the depth of water.

The water was shallower over this delta which protected the coast on either side from the damaging attacks of storm tides. This allowed the balance of coastal processes to shift towards accretion (deposition). Shutting the sea out of the saltmarsh by construction of the seawall meant that this delta was no longer so well fed by sediments and it reduced in size. As it has reduced so has the protection it offered to the coastline to east and west - particularly to the west as the damaging storm direction is the Northeast. This lack of sediment input and impact of storm tides has caused the beach levels to drop so exposing the dunes to direct attack by the sea. Even if the man-made sea-wall were to be removed and natural processes allowed to build up the delta again, it could be very many years before the system started to go into reverse.

Peat is laid down where soil is waterlogged. Lack of air inhibits the organisms that cause vegetation to decay, and peat is consequently a very good preservative medium. In this case, the lower part of the timber circle has been protected by peat for 4,000 years. Rapid erosion of the beach has caused the protective peat to be stripped off the timber circle. The erosion is likely to continue, possibly causing the dunes to be breached and lowering the beach even further. The natural processes have responded to the construction of the sea wall by tending to create another stable system. We may not like what natural processes are doing but it is likely that our predecessors' actions in the last century have caused them to respond in this way.

Key wildlife species that depend on the beach habitat, and in particular the area around the timber circle, are the waders such as knot, bar-tailed godwit, grey plover and sanderling. All of these are regularly present in internationally important numbers. They overwinter on the site from late summer until May, as they breed in Arctic and Northern regions. During the breeding season (April-July), much lower numbers of birds are actually breeding on the beach - mainly ringed plover, oystercatcher and little tern.

As the terns and plovers are breeding it is vital that they do not suffer from disturbance at this time. Their two main threats are the coastal weather and disturbance from visitors. Increased numbers of visitors usually bring increased numbers of nest failures. The reserve staff erect cordons to protect the main concentrations of breeding pairs, but isolated nests are exposed to disturbance. In a normal year, June and early July are quiet for visitors and there is fair chance that some nests will hatch young.

Norfolk Wildlife Trust has requested that the press respect the sensitivity of the site and its significance for internationally important species, but the popular press has continued to hype the story of the circle.
Although the peat deposits that protected the remains of the timber circle have completely eroded away, very extensive areas of peat survive on either side of the circle. These deposits are an important wildlife feature in their own right, as a variety of specialised invertebrates live in the peat. These in turn are the filling in the seafood sandwich for the knot and other waders and may be the reason that the beach at Holme Dunes is so attractive to these birds. The largest flock of waders ever recorded in the UK was of 180,000 knot at Holme in autumn 1993.

Visitors and the media coming to the beach to look at the circle have walked on the fragile peat beds and this accelerates their destruction. In the long term the peat beds that we see now will probably be destroyed by erosion, but it is not desirable to hasten the process.

During the winter months, when the waders were present, visitors to the timber circle were a source of disturbance to the waders. When the knot flocks arrive in early September, a very large proportion of the east Greenland population can be feeding and roosting on Holme beach. The birds can be in poor condition after their long migration and need to feed up quickly before the winter. Freedom from disturbance and the good condition of their feeding grounds is critical at this time, as it is also during harsh winter conditions.

On a coastline that is busy with human leisure activity, wildlife is under great pressure even on nature reserves. The primary purpose of NWT Holme Dunes National Nature Reserve is to maintain populations of the key plants and animals and to maintain the habitats in good condition.

Norfolk Wildlife Trust knows that people and groups have different views on the future of the timber circle, but needs to point out that there is something else extremely valuable at stake here, in particular the waders which have been visiting this shore to breed, rest or feed for centuries, and which may be damaged by even well-intentioned visitors, whether they are for or against the excavation or merely curious.

To those people who respect nature - the Earth and its ecological systems - there is much to be concerned about in the current disagreements over the circle timbers. These must be quickly resolved if the natural human interest in the ancient circle is not to interfere with the continued operation of these waders' strategies for migration and survival - which are also fascinating and mysterious. Knot and other waders spend their lives on an energetic knife-edge - a balance between the availability of quality undisturbed feeding areas and the need for energy to undertake great migration flights and to survive freezing weather; the beach at Holme is part of the chain of sites that sustain them.

Bill Boyd
Norfolk Wildlife Trust
19.06.99