In some parts of the world deserts stretch for miles and are a pitiless wilderness of parched days, cold nights and storm-blown sand mountains. With a temperate British climate it is hard to believe that such severe conditions can apply here but, in miniature, this is exactly what happens to coastal sand dunes.
The dune systems at Holkham are formed on old shingle ridges. With the interplay of wind and water the landscape can change very quickly. To the east, the coast is eroding whilst elsewhere shingle banks are building above the tideline and gathering windblown sand. The tall dune islands on the foreshore in Holkham Bay have appeared from nowhere in the last sixty years. And sometimes after severe storms whole sculptured ridges have vanished overnight.
In this harsh environment pioneer dune plants have to be tough. Among the first colonists are sand Couch Grass and Sea Sandwort, then Marram Grass which is renowned for its ability to bind the loose sand and start the dune-building process. The young dune and shingle systems create important nesting areas for shore birds. Oystercatchers and Ringed Plovers lay pebble-patterned eggs among tideline flotsam and Marram roots. Little Terns, often seen hovering and diving for fish just offshore, are a special summer visitor to Holkham: the reserve accounts for 7% of the British population. Unfortunately sandy beaches with patches of shingle are in short supply and the birds have to compete with holiday-making humans. To give them a fair chance to raise their young the most vulnerable colonies at Holkham are cordoned off with notices explaining to people how they can help the terns by giving them plenty of space.
Mature dunes, often rich in lime because of the shell fragments in the sand, soon grow a mat of vegetation. Cropped by rabbits and subject to surface temperatures of over 30 degrees, flowers like Bee Orchid and Carline Thistle thrive in the extreme conditions. So do solitary wasps and bees and butterflies such as the Grayling, Small Heath and Common Blue. In the evenings Natterjack Toads emerge from their burrows and join a noisy chorus at the spawning pools.
Sand dunes are fragile and the plant communities are easily destroyed by trampling, leading to disastrous wind erosion. Boardwalks and steps help visitors to cross the beach without damaging the hard-pressed vegetation.
A few dunes flowers
- Marsh Helleborine
- Pyramidal Orchid
- Southern Marsh Orchid
- Rue-leaved Saxifrage
- Early-flowering Forget-me-not
- Corn Salad
- Hounds Tongue
- Lady’s Bedstraw
- Sea Holly
- Sea Bindweed
- Lesser Centaury
- Carline Thistle
- Ploughman’s Spikenard
- Bird’s-foot Trefoil
One of our rarest amphibians. Recognised by light yellow stripe down centre of back.
Runs, does not leap or hop. Has far-carrying call or 'song'. Lays spawn in shallow pools where water warms up quickly allowing rapid growth of tadpoles.
The main predators of tadpoles are dragonfly larvae and diving beetles, but these prefer permanent pools, therefore tadpoles benefit from pools that dry out.
Habitat management is to provide shallow, profiled pools, with short turf in the surrounding dune grassland to feeding areas.