Law of profit: What can two grass changes 40 years apart tell us about Britain's biodiversity crisis?

In 1983, David Nash dug up part of Kensington Gardens and replaced it with a Welsh meadow. Four decades later, Mike Perry's reverse trade-off marked a dramatic shift in the fortunes of urban and rural nature. In 1983, an open-top truck loaded an unusual cargo into Kensington Gardens: 83 pieces of grass cut from Cae'n y Coed, a wooded hillside in Fest. A circle of grass with a diameter of eight meters, which goes from the park next to the Serpentine Gallery in the west of Lon

In 1983, an open-top truck loaded an unusual cargo into Kensington Gardens: 83 pieces of grass cut from Cae'n y Coed, a wooded hillside in the Ffestiniog Valley. The eight-metre-diameter ring of grass, which was removed from the park next to the Serpentine Gallery in west London to make room for Welsh grass, was then moved from London to North Wales.

Nash, who is 80 and still works with wood, says it all started with his own "coolness." He was invited to contribute to a new Serpentine Gallery show of British sculpture. He came up with the idea of ​​wooden sculptures for an indoor gallery because he felt that too many outdoor sculptures "came and went like UFOs," as he puts it. But the gallery said, "Oh, David, you're an outside artist, so we'd like you to participate in the outdoors."

Nash, who had built his very exterior ash and slate dome a few years earlier, ruffled his hair. He actually created an outdoor piece for the Serpentine show in 1970 when he was a graduate student at the Chelsea School of Art. When he tried to secure it in the ground he was told he couldn't touch the Kensington Gardens lawn because it belonged to the Queen.

So, this time, he planned to rough up the pristine lawns of a London park by installing a ring of wild meadows from North Wales, while also challenging definitions of 'sculpture'. "Bright red metal" was huge in the early '80s, says Nash wryly. "I wanted to create something that didn't need to be cleaned."

He says that the benefit of the swap was his declaration of identity. I was very keen that what I put in had a sense of where it came from, where I am, which is North Wales. When he realized he had to dig up a load of Kensington turf, he decided to take it to Wales. “It became a trade-off and I liked the concept of being a puss. "It didn't really have anything to do with the environment, but it turned out to be that."

Nash waited for a reaction and took a picture. After several anxious meetings about digging, and head-scratching from council officials over the risk of "invasive" Welsh plants contaminating Kensington Gardens, the Sod Swap went ahead. "He's very disruptive, David," Perry says. “He doesn't look at it, but it's there. Serpentine expected him to bring a large wooden statue. And he said, "No, I want to mow your lawn." He wanted to show who he was, but he also wanted a sculpture that could be—it didn't have to be a solid object on a plinth. It can be an ephemeral piece of organic matter.

In 2023, when Perry began a restoration and art project on 4.9 hectares (12 acres) of farmland in West Wales, he wondered if he might revisit Nash's concept after four decades. A little nervous, he called Nash and was relieved when the sculptor said an enthusiastic "yes." A week later, Perry traveled to North Wales, where Nash took him to see the site of Kensington Gardens. Amazingly, 40 years later, they could still detect a faint circle in the mossy grass now dotted with mature trees.

Welsh turf did not last long in London. After the show ended, the gallery planned to simply remove the grass, but, luckily for Nash, "outdoor art angels" Sue Clifford and Angela King stepped in. The two founders of the environmental arts charity Common Ground were quick to find another unlikely home in London for Nash Welch's lawns: the lawns of Hump Condest.

Clifford and King also had the brilliant idea of inviting ecologists to count the species in each grass circle. Welsh lawns contained 28 different species, including grasses, wildflowers, brambles and even nettles, while the manicured lawns of Kensington Gardens consisted of a paltry three grass species. Suddenly, Nash's little challenge to the art world had an ecological message that highlighted the biodiversity found in rural pastures and the sterile quality of urban parks.

While Nash's little patch of Wales suited Hampstead Heath, the artist dutifully watered London's lawn at Cae'ny Coed, even buying a second-hand lawnmower to keep it in the condition he was used to. The original plan was to return it to Kensington Gardens, but Nash says the Arts Council told him they had run out of money for the project and could not return it. Sod Swap became permanent.

Finally, after 10 years at Kenwood House, English Heritage removed Wales from Wales. "London turf stayed in Wales," Nash recalls. The chestnut trees I planted grew and grew and overshadowed the lawn, and the moss came in. There were daisies from London that grew for about five years but then disappeared. "I carried them on for 20 years as if they were in London until it was almost all moss and then I thought I'd give it up." Over the years, artists, curators and students have made pilgrimages to visit it.

Perry says that Reverse Sod Swap "was kind of a biographical piece for me." He lived in London for 20 years before moving to an old farm by the sea in north Pembrokeshire. "My parents retired here, so I was always going back and forth between East London and West Wales," he says. The scenery and seascapes of the Pembrokeshire Coast National Park still look beautiful, but "it's so sad to walk down to the sea because there's nothing in the hedgerows. They're literally stripped and the grass is just being mowed 24/7 by lots of sheep. To die for," said the head of the RSPB [for the National Wildlife Society].

Perry hoped the Reverse Sod Swap would make an environmental statement, but he couldn't have guessed how much it would make. In Wales, he took grass from pasture that was still heavily grazed by sheep belonging to a tenant farmer. At the London end, he was given a "really poor" piece in Springfield Park, with "bad bits of dirt all over the place and a bit of grass of all sorts of rough stuff". But I loved it because there were giant goblins and weeds and thistles. "I loved that combination."

Perry's first challenge was repeating dimensions. Nash could not recall the exact size of his 1983 turf circles, but Perry discovered an old catalog statement, which noted that there were 83 turfs measuring 90x30 cm (35x12 in). He then followed Nash's idea of ​​building small wooden "pullers" to carry any dirt from the ground to waiting trucks. On their trip to Wales, they stopped twice at motorway services to water the precious lawns.

In the two and a half years since the reverse sodium exchange, Perry has been amazed at how the project has continued for him. David put his hand on my shoulder, looked me in the eye, and said, "Mike, things happen when you're out there working." I really didn't know what he meant. "But what's amazing is that the work is constantly living and changing – it gives me new images and discoveries."

After the reverse graft, the botanists examined the grafted grass and surprisingly found the Nash exchange photo from 1983. Grass taken from Springfield Park contained a total of 39 species, while grass grazed by Welsh sheep contained only four species. And so, over the course of four decades, these two works vividly capture the loss of rural biodiversity – a loss often obscured by the seemingly immutable character of the British landscape, with its hedgerows, fields and woodlands. But Reverse Sod Swap also shows a more promising trend in London, where the species has been revived by urban regeneration efforts, from creating wildflower areas in parks to building new sustainable urban drainage areas.

Perry is encouraged by what he sees when he returns to London and walks along the Grand Union Canal. It seems there are butterflies, there are rough things. "It's not scientific because obviously there are areas in Wales that can't be farmed and there's amazing biodiversity, but I was really trying to make a point through art."

Nash is impressed with the longevity of his Sod exchange and the environmental message he received. "What Mike has done is an amazing bonus," he says. "My Sod Swap highlighted the lack of plant species in London, not that that was my original intention. Sod Swap is much more ecologically appropriate because it highlights the scarcity of rural land. We are artists doing our work there and we hope people see it and make something of it - be inspired or accept it as part of their consciousness."

Reverse Sod Swap by Mike Perry and David Nash is published by Little Toller on October 16 (£25). To support The Guardian, order your copy. Delivery charges may apply.