Interview: Isabella Tree on some wild ideas

21st July 2022

Isabella Tree talks to Chris Seekings about the amazing success of the Knepp Wildland project, and the vast array of ecosystem services that rewilding can provide for the UK and beyond

Across 3,500 acres lies a plot of land where large herds of free-roaming animals live side by side, surrounded by an abundance of rare species, overarching trees and dynamic, natural watercourses. While this may conjure up images of the Serengeti or the Amazon rainforest, this hotspot of biodiversity can actually be found in a quiet corner of West Sussex, where a pioneering rewilding project has turned traditional ideas of conservation on their head.

Once an unprofitable arable and dairy farm, Knepp Wildland is now recognised worldwide as an outstanding example of landscape-scale restoration, where an abundance of plant and animal species thrive and provide numerous ecosystem services. One of the UK’s most famous rewilders, Isabella Tree, explains how she and her husband, Charlie Burrell, turned some of south-east England’s most depleted land into a haven for wildlife – and how others can follow their unconventional path.

A brave decision

Tree, an accomplished author and travel journalist, explains that her early childhood and experiences abroad inspired her interest in the natural world. “I am lucky enough to be of a generation when it was quite normal for children to run feral and just disappear from home for hours with their friends, building dens and dams and things, so for me, growing up in nature was completely normal – my parents called it ‘the school of benign neglect’,” she says. “When I began as a journalist in my twenties I did a lot of travel writing and wrote for a geographical magazine with an environmental angle, so I’ve always had an interest in wildlife and nature.”

In 2000, Burrell was struggling to make a profit from a 3,500-acre farm just south of Horsham that he had inherited from his grandparents, and eventually decided to sell its herd and farm equipment to clear mounting debts. “We’re on marginal land with very heavy clay, and it took about 17 years to realise that we could never actually be profitable, so he made this decision for financial reasons,” says Tree.

Two years later, inspired by the Netherlands’ Oostvaardersplassen nature reserve, the couple decided to establish a ‘hands-off’ naturalistic grazing system across the estate. “It was a brave decision because it went politically against the grain, as it was so instilled in our culture and in Charlie’s family that we should be farming,” Tree says. “We met the Dutch ecologist Frans Vera, whose theory of using free-roaming large herbivores to drive habitat creation completely clicked with us.”

“We knew we had to do something with the land that was going to work with it, rather than battling against it”

They introduced herds of old English longhorns, Exmoor ponies and Tamworth pigs, as well as red and fallow deer – and watched as a transformation unfolded over 20 years. “People thought we were mad, and plenty of local farmers and neighbours thought we were being irresponsible and lazy,” Tree recalls. “We were even called unpatriotic for not doing our bit for Britain by stopping food production, but we were very attracted to this idea that, in a rather low-cost, straightforward way, you could introduce free-roaming animals onto depleted post-agricultural land, and they could start regenerating the soil and creating habitat if you just sat back and left them alone.”

Total transformation

The Knepp Wildland has since seen an extraordinary increase in wildlife, with rare species such as turtle doves, nightingales, peregrine falcons and purple emperor butterflies now breeding, and more common species seeing their numbers rocket. “When I was growing up, we had 250,000 turtle doves in Britain; now we have just a few thousand, and the RSPB believes that it’s going to be one of the next species of bird to go extinct from our shores in the next 10 or so years,” Tree says. “We have lost them because of our loss of habitat, and so to suddenly find one of our rarest birds breeding at Knepp within 10 years was astonishing. We’re probably the only place in the UK where turtle dove numbers are rising.”

In 2009, ravens nested at Knepp for the first time in hundreds of years, and 13 out of a total of 18 UK bat species were recorded that summer, along with 60 invertebrate species of conservation importance and 76 additional species of moths. In 2016, a black stork (one of the rarest birds in Western Europe) was spotted, while white storks were observed raising chicks at the site in 2020 following a reintroduction project – the first time this had been seen in the UK for 600 years.

“We’re sequestering carbon, cleaning the air and water, and mitigating events like floods”

These are merely a few of the highlights recorded during the past couple of decades; just comparing historic footage of the site to aerial photos today shows the scale of the transformation. “We knew we had to do something with the land that was going to work with it, rather than battling against it all the time,” Tree says. “This idea was to see whether we could increase biodiversity across the board, with free-roaming animals transporting nutrients and seeds around the landscape to kickstart these natural processes.”

Despite wanting to ‘let nature do its thing’, there are times when it is necessary to intervene. Too many browsing and grazing animals and you end up with ubiquitous grassland; too few, and you get tree recruitment and eventually close-canopy woodland, which is also bad for biodiversity. “You have to cull animals so you get the right numbers to allow vegetation to carry on growing, and create a battle with the herbivores that neither side wins. That’s when you get that complexity and mosaic of habitats, which is what benefits wildlife.”

Natural services

Culling these animals is what’s responsible for the small quantity of food still produced at Knepp, which Tree describes as a “by-product of nature”. “We’ve moved from producing food intensively to producing different things that the public desperately needs,” she says. “We’re sequestering carbon, cleaning the air and water, and mitigating events like floods. These are ecosystem services, or ‘public goods’. Another public good, of course, is access to nature. And we know, especially post-COVID-19, how important this is for human health and wellbeing. Rewilding is about the production and restoration of nature, with food production as a by-product. We produce meat because we cull these free-roaming animals to keep a low stock density in order to maximise conditions for biodiversity.”

One of the most obvious examples of how the restoration of natural habitats at Knepp Wildland has provided ecosystems services has been shown this year through the introduction of beavers. While a previous attempt in 2020 was unsuccessful, a pair was introduced in March this year, and both are thriving. “They’ve already built three dams and increased the open surface water area by an acre, at least. There are rivulets and channels, and huge examples of hydrological engineering going there, and we’ve already had a turtle dove in their pen – it’s amazing how much they can do in just a few months.”

Dams are important for flood mitigation because they hold water in times of floods and then release it slowly throughout the year. “It’s protecting farmland downstream from us, and also holding onto the water and replenishing the water table,” she explains. “Beaver ponds also start cleaning pollutants out of the water, which is extraordinary, and can save water companies huge costs by removing the nitrates and the pollutants. You also have a lot of woody debris in the water that the beavers collect, which provides a protective habitat for places where aquatic invertebrates and fish can live without predation. Then you’ve got all the knock-on effects for wildlife, with kingfishers, heron and other birds eating the insects that are being regenerated by those static water pools. So beavers are a completely extraordinary keystone species.”

Around 350 acres of land was never used for rewilding due to its proximity to a nearby village. Tree and her husband recently decided to start a regenerative agriculture project on the land to show how it can work in tandem with rewilding. “Particularly on marginal land like ours, rewilding can provide the life support system that agriculture needs for the future in the UK so it’s going to be sustainable and productive,” she says. “We know that if you have areas of nature around even our intensive chemical farmed areas, that actually increases yields because you’re providing the pollinators for the crops and you’re also providing natural pest control.”

Rewilding for all

There are around 85,000 hectares of rewilding projects in the UK, many inspired by Knepp, while others are looking to replicate its success abroad. However, Tree says that funding is a big issue for people who are looking to start projects, and explains how government support for the environment always gets slashed in times of political and economic crisis. “It’s very short-term thinking,” she says. “But I think the new farming subsidy scheme will help because farmers will be rewarded for regenerative farming, soil restoration and other positive things for nature. But the game changer is going to be the private sector, because there is now going to be money from biodiversity credits and carbon credits as companies look to offset the damage they do. Rewilding Britain wants to see 300,000 hectares of land rewilded by 2030, and that’s actually not a big ask – it’s the same amount of land currently used by golf courses!”

“Rewilding can provide the life support system that agriculture needs for the future so it’s going to be sustainable and productive”

As for future projects, Tree has recently become involved with the London Rewilding Taskforce, which intends to deliver rewilding projects on the outskirts of London, potentially including microparks and nature corridors alongside train lines. She is also has a book due to come out in April 2023, The Book of Wilding, which includes a chapter on urban rewilding. “If you’re thinking about rewilding a river that goes through a city, for example, then you have to think about the landscape at scale, and how raindrops fall on the mountains, and all the farmland that goes along the river before it even reaches the city, which may be in

an estuary on the coast – it’s thinking about how to connect all these areas together. We have lots of nature reserves in London, but they’re very isolated, and if we can use green space to connect them and start to have green roofs and green sides on our buildings as the default for architectural design, it’s going to have enormous benefits for insects, birds and small mammals, as well as clean the air and lower the street temperatures in summer.”

Tree is keen to emphasise that rewilding can also have benefits for people, not least in returning a sense of engagement with nature, and agency over our future. “In this age of eco-anxiety, doom and gloom, and all these massive problems we’re facing, it’s catastrophic. As an individual, you think: how can I do anything? You go into a tunnel and feel impotent and meaningless. But what excites people when they come to see Knepp is that positive message of hope, with what was virtually a biological desert 20 years ago, springing back to life so quickly. It really galvanises people to think of what they could do, because rewilding really is for everyone.”

Image credits: Lia Brazier - Charlie Burrell - Jack Hill


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