Conservationist Isabella Tree: ‘Rewilding is vital for the UK’s agricultural future’

<span>Illustration: Lyndon Hayes/The Observer</span>
Illustration: Lyndon Hayes/The Observer

At lunch in Hove, a block back from the seafront, on the first summery day of the year, Isabella Tree is explaining the phrase that best describes her work: “Don’t just do something, stand there.”

The phrase captures the philosophy behind rewilding, the movement that the happily named Tree has done so much to pioneer, with her husband, Charlie Burrell, on the 1,400 acres of land they own at Knepp in Sussex. The essence of their project has been to undo the damage of decades of intensive farming by working with the environment, rather than against it.

In 2001, with mounting debts, falling subsidies and thinning soils, the couple cashed in their tractors and harvesters and dairy herd and milk quota, and did something different: they let loose wild Exmoor ponies and Longhorn cattle and Tamworth pigs on their estate and then stood back, watching and waiting.

The result of that inaction was nothing short of revolutionary. In her bestselling 2018 book, Wilding, Tree described how the animals transformed the soil, and how the soil transformed the whole ecology. Very quickly the farm became colonised by an extraordinary diversity of plants and insects, bats and small mammals, attracted to the scrubland and water meadows and wood pasture that re-formed on previously ploughed and fertilised and pesticided fields. Nightingales and turtle doves, whose numbers have declined catastrophically, thrived; a colony of storks has been established, returning a species that bred here for tens of thousands of years. The magic of that transformation is now captured in a documentary made by David Allen, whose award-winning films most recently include The Serengeti Rules, which explored remote and untouched ecologies. The remarkable thing about Allen’s Knepp film is that it seems like a natural next chapter of that project, filmed a few miles from the A23 and Brighton.

Tree was a travel writer before she was a rewilder, author of books about Papua New Guinea and Kathmandu, and she gives the bright-eyed impression, at 60, of having found a way to bring all of that adventuring spirit home. She has chosen to have lunch, appropriately, at a restaurant called Wild Flor, which advertises the local provenance of its menu on a blackboard: “Fruit and vegetables: George’s allotment, Alison’s foraging; whole beast local meat and game: Calcot Farm, Ashurst”, and so on. In the past, the team here has bought meat from Knepp’s wild herds, but this is the first time Tree has eaten here. As we make our way through a fabulous, seasonal three-course lunch, nettle soup and mutton and hazelnut and apricot custard, she relives some of the challenges of Knepp that are recreated in the film.

Some of those obstacles have not gone away; government, lobbied hard by agribusiness and the conglomerate food industry, remains at best agnostic about the possibilities of wilding, and licences have been hard to come by. (“They talk about food security,” she says, “but if they really cared about it, they would do something about the third of food that is wasted each year.”)

Local barriers have proved a little easier to negotiate. To begin with, some of the farms that bordered the Knepp land were hostile to the idea of nature taking its course, fearful of the spread of ragwort and other pernicious weeds. Slowly, many have been won over.

Tree suggests you can measure that progress in dung beetles. Her husband, Charlie, who inherited the estate from his grandparents, spent a lot of time in the early years crawling in the dirt collecting insects from cow pats. A recent study showed that even compared to a nearby organic livestock farm, Knepp supports something like 30 times as many dung beetles. The beetles, all but wiped out by pesticides in some areas, are crucial to soil health and fertility. And the key thing is this: because the livestock at Knepp do not overwinter inside, the beetles are present in large numbers all year. When the cattle at neighbouring farms return to pasture, the insects are primed to spread out and colonise.

Another success is the significant rise in local bird populations, which means there is far less need locally for insecticides; the recreation of natural river meanders and the introduction of beavers on the estate offers age-old lessons in flood management. Counterintuitively, Tree suggests, the estate is also making money. Because overheads are so much lower, their beef, pork and venison turn a profit; farm buildings can be rented out to small businesses; and there is a growing wilderness-safari market. Their hope is to create corridors and networks of wilded land across the country, making farming sustainable.

“The way we see it,” she says, “is that you need that rewilding to build a sustainable future for agriculture. We can’t carry on [with intensive methods] … Rewilding can provide the life-support systems for regenerative farms. It can help you restore your water tables, put an end to the nitrates and chemicals that pollute our rivers day in and day out much more than human sewage.” She points to the fact that species such as scarce chaser dragonflies and water violets and water shrews are newly abundant at Knepp because of the purity of the ponds and streams.

In some ways, it feels as though Tree was born to this somewhat fairytale life. She was adopted as a child by aristocratic parents – her mother was Lady Anne Tree, daughter of the Duke of Devonshire, and a noted prison reformer and plant hunter. She grew up at Shute House – where Sir Geoffrey Jellicoe created a famous garden at her parents’ instruction – with a lot of freedom. “My parents’ idea of bringing up children,” she says, “was benign neglect. I had my spaniel and my Chopper bike and cycled miles to meet friends and make dens and light campfires.” Given the fact that her mother’s idea of landscape design was to recreate the Shalimar gardens in Kashmir, I wonder what she would have made of Tree’s approach – tipping 400 tons of crushed brick on to the croquet lawn, for example (“nature doesn’t like flat lawns”) – to change what was a “biodiversity desert”?

“My mother loved flowers, she would go on plant expeditions in Nepal or Crete or wherever. She died in 2010 so she saw the beginning of our rewilding, but I would love to see her reaction to the garden as it looks now.”

Talking to Tree it is hard not to be pollinated by her cheerful enthusiasm, which is backed up by years of hands-on research. She and her husband were never natural evangelists but she has, it seems to me, become a rare purveyor of genuine hope in a depleted environment.

As we get to our puddings, before she heads off to her (inevitable) yoga class, she talks me through some of the ways in which their ideas are quietly taking hold, without a government minister in sight. The Help Our Kelp project, for example, 300 square kilometres off the coast here, which is aiming to restore the diversity of the seabed and save the livelihoods of small fishing boats. Or the Weald to Waves programme, which is pushing to create a wildlife corridor 100 miles long from Knepp to the Ashdown Forest, a model for what might be possible country-wide.

That latter idea, like all the best ones, evolved organically. In lockdown, she and Charlie got a call from a local farmer called James Baird, who had read Tree’s book, and came to see for himself the health of the cattle at Knepp. He was a convert. He told them “at the end of the book you said your dream is to connect Knepp in a corridor with the sea – well, I own that land between Brighton and Bognor, so let’s do it”. And then, she says: “Ashdown Forest to the north-east got to hear about this and said, ‘Can we join you?’ So we said, OK, sure. And then the people who look after the River Arun said: ‘Why are you concentrating on the River Adur, not us?’ And then the Ouse said: ‘You’ve got to have us too.’” The dots are now nearly all joined up. “There will be a few gaps,” she says, “but, basically, you will be getting wildlife flowing through river catchments, restoring floodplains. And what’s become wonderful about this project is it’s now run by a charity set up so anyone can join in. If your property is on that notional corridor, your private garden or allotment, or if you are looking after the local churchyard say, you can be a part of it.”

“Like the opposite of HS2?” I suggest

“Exactly like that,” she says.

Wilding, based on Isabella Tree’s bestselling book, is in UK cinemas now