The Eden Project in Cornwall is more than a botanical garden. Rooted in science, it aims to show the public the fragility of life on earth. Anne Sebba reports

If you stand on the ridge above the Eden Project's new visitor centre and look out beyond the farmland and scattered sheep towards the bay of St Austell, you see two dramatically huge, half-finished domes. In a few months, these will be conservatories housing thousands of beautiful plants from all over the world. But they will be much more than a showcase for pretty and unusual flowers, says Sir Ghillean Prance, former director of the Royal Botanic Gardens at Kew and Eden's scientific director.

"Anyone who visits the Eden Project will leave with the clear message that if we don't find a way to manage and conserve plants, the whole of life on earth will collapse," he asserts. It is a statement made in different ways by other botanical gardens over the years, but Eden begins with a scientific agenda based on raising public awareness.

The Pounds 73.4 million Landmark Millennium initiative, whose vast conservatories will house the biggest enclosed area of rainforest anywhere in the world, opens its visitor centre this month, the first Eden fellowship PhD student should begin research soon after, and the project should be in full swing next year. Sir Ghillean is trying to raise Pounds 250,000 to fund five, three-year, full-time fellowships.

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He says Eden should provide an abundance of good research topics because scientists will be able to track plants from their arrival, watch the build-up and interaction of pests, monitor the dynamics of soil and plant growth under the conservatory structure and see how it affects flowering and fruiting. For him, the sheer size of the undertaking makes it a great opportunity.

But what makes it truly awe-inspiring is the vision behind it and the location. Eden was conceived largely by entrepreneur Tim Smit, who pioneered the development of the lost gardens of Heligan in Cornwall, Philip McMillan Browse, Eden's horticultural director, and Peter Thoday, former senior lecturer in horticulture in the department of applied sciences in Bath. All wanted to create not just a new type of botanical gardens but a scientific institute that would address the conflict between conserving plants and using agricultural land economically, without being allied to either camp. They believed there was no existing forum where these challenges could be examined.

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"It is the institute - more a philosophical concept than a building - that is at the core of what we're doing, and our policy is to hire young people, who come without any baggage saying 'this can't be done'," says McMillan Browse.

They took two years to identify the perfect site for Eden - a china clay pit in Cornwall abandoned as a 50m-deep crater. This offered the natural advantages of Cornwall's mild climate, clean air, ample water and steep, south facing walls that catch the sun. There was also a powerful symbolic attraction in the pit's lunar landscape dereliction. This allowed them to create their own soil for a "living laboratory" in the hollow - something that particularly excites Peter Whitbread-Abrutat, Eden's scientific officer, because it means they will know exactly what has gone into the 85,000 tonnes of artificial soil. "It gives us a real opportunity to look at the nutrients and the microbial flora from a known starting point," he says.

Work on clearing the site began in October 1998, and building will continue to take place over the next year. The conservatories, or biomes, have a lightweight, galvanised steel frame that forms an enormous self-supporting shell. The roof is a series of interlinked hexagonal panels filled not with glass but with a triple-glazed plastic known as ETFE (ethyl tetra fluouro ethylene) chosen largely because it is highly transparent to UV light and not degraded by sunlight.

The larger of the two controlled environments, big enough to house the Tower of London, will reconstruct plant life in the humid tropics (Rainforests and Oceania); the other will house plants from the warm temperate regions (Mediterranean, South African Cape area and California). The third climatic area, a roofless biome, is the Temperate Zone, which will thrive on the natural climatic advantages of Cornwall. This is where many of the more familiar crops that have shaped our lives will be grown, and there are plans for a children's biodiversity trial in this sector to illustrate by experience fields supporting diverse flora.

It is in the humid biome, where giant teak and mahogany trees will flourish alongside rubber, cocoa, bamboo and vanilla, that the creators of Eden hope to demonstrate most forcefully how fragile is the balance between exploitation and conservation as man adapts his environment to satisfy the demands of the global market.

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"Education is not just a bolt-on for us," says McMillan Browse. "Our concept is that everything is integrated - for example, our gardeners will be scientific horticulturists. They won't just have practical skills in weeding, they'll also learn to evaluate them and have some instruction in communication."

As part of this holistic approach, all students and staff will need some understanding of the retailing and commercial side of Eden (a non-profit organisation). In particular, PhD students will be expected to spend up to six months on communication activities, perhaps guiding the public as well as developing accessible displays of their work.

The intention is to use neither huge story boards nor video screens but to educate by telling a story wherever possible. This will often involve three stages - from wilderness, to clearing, to cornucopia, or out and out cultivation by man. One of the most obvious stories will be how cultivation of important crops such as cotton and sugar cane resulted in migrations of whole populations. But the scientists at Eden also hope to contribute to the debate about genetically modified plants, considering whether GM crops could be the answer to help feed a rapidly growing population.

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McMillan Browse says some of the displays - especially at the wilderness stage - will have to be pastiche. Having mammals wandering around would be impossible, and even pollinating bees could be a problem because of the potential danger to the public. Some trees will also need to be dried out to make them look brown and natural rather than too green.

In addition to informing the public, Eden has designed a special syllabus, to be delivered by the local Duchy College, that will take ten students a year on a two-year national diploma course, concentrating on plant genetics, the implications of soil and other concepts that affect plant growth, as well as a higher national diploma course. It is committed to the continued development of its staff and expects many of them to undertake postgraduate degrees on a part-time basis over five years.

Eden has developed symbiotic relations with the nearby University of Plymouth, the University of Kent at Canterbury, which boasts the only department of ethno-botany in the country, and the University of Reading, which has a strong soil science department. Several universities are expected to use Eden as a field station for undergraduate students, and Whitbread-Abrutat is also trying to develop links with the University of Exeter's specialist Cornwall offshoot, Camborne School of Mines, where he did his postgraduate and postdoctoral research.

Eden's Andrew Ormerod, responsible for plant procurement, has been amazed at the supportive response he has had from academics in the horticultural community, providing advice or material. "Scientists have always had problems getting their message across. They are often frustrated because they don't have the time or the ability to generate a public airing of their best experiments or results. Even though really interesting things happen, they're not sexy enough to be published anywhere beyond scientific journals." He hopes Eden's high profile - its sheer scale has already earned its structure a place in the Guinness Book of Records - will help overcome this.

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