It was a crisp autumn day in the vineyards of Saint Emilion, the vines asleep for the winter, as winegrowers, scientists and children planted hedges to create habitats for mites needed to prey on vine pests.

This marked the debut of an ambitious biodiversity project launched by pioneering French vintners in a bid for sustainability.

The biological diversity of Saint Emilion's 8,000-hectare vineyard landscape, intertwined with wine since Roman times and protected by UNESCO as a World Heritage site since 1999, has been precariously reduced by urbanization, chemical vine treatments, and one-crop farming.

The long-term goal of the community project, unveiled to coincide with St. Catherine's Day when "all trees take root", is an attractive and functional landscape.

It will come with dozens of kilometres of interlinking green corridors that allow animals to move between 1,100 wine estates, and reduce soil erosion, vine treatments and fertilizer and pesticide run-off.

The corridors, for the moment, however, are few, far between, and fragile. Where a variety of crops grew 50 years ago, grapevines reign supreme, often cultivated from the edge of the ditch alongside the road to within steps of the cellar door.

"In Saint Emilion, vineyard land sells for between one and three million euros per hectare, so when we let grass or poppies grow, it seems incomprehensible," said Xavier David-Beaulieu, owner of Chateau Coutet, a 14-hectare estate with one hectare of woods and prairie.

Viticulture has made the area wealthy but monoculture provides an ideal habitat for pests like spider mites and leafhoppers to colonize and infest a field, destroying the grape quality and yield.

For decades, chemicals provided the answer, but led to a vicious cycle of dependency.

"When you treat with insecticides only three percent of the bugs are a menace to the vineyards, the other 97 percent are useful," said Patrice Hateau, director of Chateau Fombrauge.

In the case of spider mites, the insecticides also kill their natural enemy, the predatory mite Typhlodromus. "Just one Typhlodromus per vine leaf means you don't have to treat for red or yellow spider mites."

Herbicides, used to make the vine rows pristine, exacerbate the problem. "Ninety percent of the bugs live at soil level."

"The more an environment is complex, the less vulnerable it is," said Maarten van Helden, a researcher in Integrated Pest Management and Biodiversity at the National School for Agricultural Engineers (ENITA) and consultant on the Saint Emilion project, which is now part of a larger biodiversity study in France, Spain and Portugal awaiting approval from the European Union.

A rare oasis for fauna and flora is 55-hectare Chateau Figeac, a legendary estate in Saint Emilion. The vineyard dates to the 2nd century AD and has been continuously inhabited ever since. Owners have fought the temptation to replant the 15-hectare greenbelt with vines.

"The trees are my luxury," said owner Thierry Manoncourt.

"Chateau Figeac is a condensed picture of everything we need to do in Saint Emilion," said Philippe Bardet, the winegrower-activist behind the project, which now has the support of 26 public organisations.

Over the last 20 years, he has planted hedges and allowed grass cover, using this "functional landscape" to produce healthy grapes with fewer chemical interventions. Natural predators attack grape worms, and grass grown between the vines reduces diseases like mildew and rot by 30 percent.

One campaign he led reduced obligatory vine treatments of the pernicious Golden Flavescence disease by 63 percent, and won the support of 1,400 vintners.

Encroaching towns on either side of Saint Emilion pose another threat. And vintners need only drive as far as the city of Bordeaux, also planted with grape vines by the Romans, to see a vineyard landscape threatened by urbanization.

At Chateau Pape Clement, a short cab ride from city hall, where Hateau is also the director, he succinctly states: "We have 385 neighbours, and 385 menaces."

Street lights attract swarms of insects and a neighbouring hospital wanted to "sanitize" a water basin that provided a friendly habitat for "good" bugs and plants.

Yet even in this "hostile" environment, Hateau has successfully reintroduced biodiversity as a substitute for insecticides.

"This year I see the difference. In 2005 we left the grass to grow in the alleys. Since the 2008-2009 season we haven't used any herbicides. We've had to use very little insecticides and what we do use is organic."

Hateau, like Bardet and many other Bordeaux vintners, eschews organic and biodynamic farming.

"We are on the third path -- we take the best of the 'lutte raisonnée' (moderate use of pesticides), the best of biodynamic and the best of organic viticulture," said Hateau. "This is sustainable viticulture, and in my opinion, the only sustainable future.

This year, Hateau planted a kilometre of nearby urban thoroughfare with "Sustainable Tom Thumb" wild flower mix, and is considering a custom-blend for Pape Clement.

He believes biodiversity will give him a competitive edge in terms that will resonate with fellow vintners.

"From the point when you limit your chemical interventions, you will reinforce the identity of your terroir. We are trying to free our terroir to express its complexity. People can share consultants, copy our methods, but no one can copy our terroir. It's the one thing that cannot be copied."