#80: Wilding at Knepp

Wilding is Isabella Tree’s account of how she and her husband Charlie Burrell gave their 3,500-acre arable and dairy farm back to nature. They started in 2001, initially since they could not make traditional farming pay, but discovered there was government funding for conservation. The subsequent transformation of the land has made Knepp one of the most important spaces for wildlife in Britain.

The book mixes delightful observation of the ever-changing activity of animals, plants, soil and insects, with information about the various species, as well as detailing the couple’s efforts wrestling with various bureaucracies to convince government of the importance of the project.

Purple emperors

Knepp is the site of the largest breeding population of purple emperor butterflies, for example, which, explains Tree, was always thought to prefer woods, because woodland was the only habitat humans had left to it. On the evidence of its behaviour at Knepp, it prefers the sallow, a type of willow – itself given space at Knepp by patches of earth thrown up by the rootling of pigs which were introduced in lieu of the wild boar which would have been present in the true wild. The video below shows a purple emperor emerging.

The ‘magic of rewilding’, she says, shows us how little we sometimes know about species:

… We forget that our landscape is so changed, so desperately impoverished, we may be recording a species not in its preferred habitat at all, but at the very limit of its range. Naturalists believe the purple emperor was a woodland butterfly only because – with no significant areas of sallow left – that is where it has clung on.… And we can dwell on the delightful thought that, in times past, purple emperors would have been a feature of the English summer, present in huge numbers in every sallow-strewn county.

If they had set out to create a perfect habitat for purple emperors, says Tree, they would never have achieved the same numbers as flit among the trees now.

The episode shows the interconnectedness of plant and animal species – it is plainly difficult for Tree to describe one species without showing how others interact with it, as the pigs do here in preparing the ground for sallow, which nurtures the purple emperors.

‘Lettuce from hell’

The couple had to learn to leave nature to its own devices – to work with it, not against it. One of the most striking episodes for me was a spectacular outbreak of creeping thistle (also known as ‘cursed’ or ‘lettuce from hell’ thistle) in 2007, 2008 and 2009. Tree describes how the dusky pink flowered plant heads covered acres of the park. She says:

It was the biggest challenge yet to our rewilding ethos. We looked out on the day of the Triffids and knew what our neighbours would be saying and the threat the thistles could pose to our Countryside Stewardship Scheme funding with their unashamed invasion of the Repton Park. Less than a decade earlier, under the old regime, we would have been out with the toppers and weedkiller for all we were worth. It took all the courage we could muster to hold our nerve and do nothing.

But in May 2009 there was a ‘bonanza’ of painted lady butterflies migrating from Africa. They descended on the thistles:

That summer, spiky black caterpillars swarmed over the thistles, spinning silken webs like tents, which soon filled with frass and inedible leaf spines. The whole area took on the appearance of a chaotic army encampment. By autumn, after the caterpillars had wolfed down the leaves, pupated and flown, our creeping thistle fields were in tatters, their stalks draped in dirty silk, the pink flower-heads nodding on skeleton stems – easy pickings for the ponies.

The thistles did not return, perhaps because the caterpillars’ devastation had admitted a virus or other pest. ‘Now,’ says Tree ‘when people stand shaking their heads in our fields of ragwort or – latterly – acres of the pioneer fleabane, we smile benignly and shrug off their concerns. Not even plagues of injurious weeds last for ever.’

Tree and Burrell also found that the thistles’ prickly cover had protected other butterflies, moths, lizards and insects: ‘gravid females with dark stripes scuttled between the thistle stems along tracks made by field mice, hunting for insects in preparation for the birth of their wriggling young.’ Anthills appeared, protected from animals’ hooves by the thistles. ‘Charlie watched for hours as, mandible by mandible, the worker ants cut down thistle and grass stalks to add structure to the new mounds. By the time the thistles died back in autumn the anthills had gained height and stabilised, capped by a coating of living moss and grass like the rind of a cheese.’

So they were able to observe nature’s natural boom and bust, ‘thanks to sitting on our hands and keeping the diphosphate under lock and key’.

Horses at twilight on the estate

Wrestling with bureaucracies

She comments that management of nature to keep it static in order to benefit a particular species may miss the larger picture, only available when nature is allowed to take its dynamic course. Indeed, this was a long-term frustration for the couple in trying to get important funding. English Nature, she says, wanted ‘computer modelling, targets, safeguards, setting parameters for the number of animals and vegetation cover, and lots and lots of further research’. But targets and parameters made no sense: ‘the only way to test the impact of freeroaming grazing animals in a landscape was to put them into action…The idea of constructing a computer model to identify the outcomes of self-willed land seemed like trying to predict the lifetime achievements of an unborn child.’

Throughout the book a bewildering plethora of organisations, departments and schemes pops up – Natural England, English Nature, the Countryside Stewardship Scheme, the Environment Agency, Rewilding Britain. It is clear that rewilding needs subsidies. But then farming itself is heavily subsidised, as are other estate parks. One wonders about the rewilding potential of other grand estates. Knole Park in Kent, for example, is maintained carefully for its deer populations. What would it look like under a scheme like this?

Help from others

It is clear from the book how much the couple depended on others’ expertise and leverage to advise on developments, gain influence and assess and argue for Knepp’s importance in Britain, Europe and worldwide. Naturalists and academics gave the project credibility and boosted morale. Tree singles out naturalist Ted Green, who visited them early on to advise on tree care and pointed out how a tree’s life-support system includes a vast underground network of fungal filaments which may even span entire continents, and Frans Vera, who had started a pioneering rewilding project in the Netherlands which had attracted, among other creatures, white tailed eagles.

Beavers

One of the most moving passages is when Tree describes seeing beavers released into the wild in Scotland:

Two of the beavers slid down river and disappeared within seconds but the largest, a pregnant female, after a lap of honour, emerged onto the sand-spit in front of us to preen. The size of a portly spaniel, she sat up, whiskers diagnosing the air and, balanced by the flat scaly tail on the ground behind her, began to comb through her long, slick fur with a back claw. Perhaps the dream of having beavers at Knepp was not so far away.… Our concrete dams and Lego block slipways would be things of the past, the floodplains punctuated with woody debris blockages not of our own making, our clumsy, artificial scrapes a staircase of pools, Spring Wood a resurgence of copies. And with this watery refinement a whole habitat would spring to life, and aqueous kingdom such as Knepp has not seen since the early Middle Ages, a place of vegetative complexity where even water voles would have a sporting chance to outwit the mink. 245

Knepp does indeed now have beavers, introduced in 2020, two years after the book was published. Not only that, but stork chicks hatched that year for the first time, and 45 hatched in 2025. Some of these will be transferred to an open aviary in Dagenham this year.

Words such as ‘ecosystem’, ‘sustainable’, ‘diversity’ are so common these days as to be unremarkable, but Wilding shows how delightful, unpredictable and essential they are in practice. Rewilding is spreading, partly thanks to Knepp and Tree’s optimistic, joyful, skilful writing.

Knepp offers safaris, tours and workshops as well as accommodation and events. There are also public footpaths through the estate.

The kitchen garden