The magic of Dune de Pilat

IT is said “God made the world but the Dutch made Holland”.

Visiting Gascony last week it seemed to me the people there have done something similar.

The Les Landes region stretches southwards from the estuary of the Gironde to the foothills of the Pyrenees. It’s an enormous plain bordered by a magnificent beach, over 200km long, punctuated occasionally by rivers.

Rocks carried down from the mountains by melting Ice-age glaciers were dumped in the Bay of Biscay and pulverised into sand. These powdered remains are being washed onto the shoreline with the ebb and flow of the tide. For every metre-length of beach, up to eight cubic metres of sand are deposited each year. Dried by the relentless Atlantic winds, the sand is blown inland, creating the highest dune ridges in Europe.

The Dune de Pilat is 114 metres high, 2.7km long and 500 metres wide. Ridges, which can move up to 25 metres a year, spawned a massive drainage problem; rivers and streams, their exits to the sea blocked, formed lakes and marshes inside the dunes, a natural version of the polders of Holland. Up to the mid-19th century vast swamps were inhabited only by shepherds who went about on stilts.’ Les Landes’ translates as ‘the moors’.

Nicolas Brémontier was born at Tronquay in the Eure region in 1738. A teacher of mathematics he was also an engineer. In 1788 he embarked on a series of ground-breaking experiments at Les Landes. The research began with the construction of a dyke, with a wooden palisade on top of it, just beyond the reach of the tide. The trapped sand formed a mound, on which Brémontier built further palisades until an artificial dune had been created.

Next, he planted marram grass, whose rapidly spreading roots anchored the sand, keeping the dune intact. This method of ‘fixing’ dunes is still used today. There are examples of it close to my home; the ‘blowouts’, caused by crowds descending on Portmarnock’s dunes on balmy summer days, need frequent treatment.

Similar techniques had been used for centuries, but Brémontier added a new element. Just creating artificial dunes does not stop the inland march of the sand. That, Brémontier realised, could only be done with the help of appropriate trees and bushes. Mixing the seeds of gorse broom and pine, he planted them together under a layer of brushwood. The broom and gorse grew quickly into bushes which sheltered the slower-growing pines; the little ecosystem stopped the invasion of sand completely. Applying the technique along the Landes coast, a vast area of woodland developed. Brémontier’s successors continued the work and, with a million hectares under trees, this is now the largest forest in Europe. But there’s a downside. The terrain becomes bone dry, particularly in late summer. Fires, fanned by Atlantic winds, are a constant threat.

An outbreak in 1948 destroyed 140,000 hectares of trees and killed 82 fire-fighters. Firemen keep watch from observation towers, ready to go into action at the first sign of an outbreak. Aircraft can be deployed to drop water on the flames.

Walking into the forest from the tide-line, you first encounter ‘la boucle’, a series of pine trees whose barks, almost buried in the sand, run horizontally just above the ground, bent by the fierce Atlantic winds. ‘Boucler’ means ‘to imprison’ or ‘lock up’; these are the outer fortifications of the eco-system. Next, you enter great stands of maritime pine, with umbrella pine various oak species and holly intermixed.

The maritime pine is a dull-looking tree; slightly resembling a Scots pine without the red bark. However, it does its sand-barrier job brilliantly and is home to red squirrels and countless birds. Dawn choruses last week were among the finest I ever heard.

There’s another bonus; resin, extracted from the trees, supports a traditional industry known as ‘gemmage’. The ‘gemmeur’, or gum collector, bleeds the bark, collecting the resin in little earthenware cups for distilling into turpentine and pitch.

While lamenting the passing of the great 19th century swamps, the Landes forest is an extraordinary creation.