Prefer a different platform? Listen on Spotify or Apple Podcasts.
Recorded in the heart of Tilburg—a Dutch city that has transformed from one of Europe’s hottest heat islands into a showcase of regreening—I met arborist Erwin van Herwijnen of New Urban Standard. We stood in the City Hall square, surrounded by paving stones and a few big trees. To the casual observer, it looked like any other plaza. But Erwin smiled as he gestured underfoot: “Right here, we can handle three and a half million liters of water.”
Beneath us lay a hidden world of plastic crates, pipes, and carefully engineered soil—an underground system designed to keep trees alive, healthy, and resilient while protecting the city from floods. In 2018, Tilburg was named the hottest city in Europe, hotter even than Seville (a city in southern Spain). Its paved-over streets baked in summer and flooded in winter. Today, thanks to a massive regreening, it’s cooler, greener, and even attracting tourists. The secret isn’t just more trees. It’s the underground world Erwin designs for them.
The golden trifecta
Erwin has dedicated his career to what most people never think about: the invisible foundations of urban trees. He calls it the “growing place,” and he insists that nearly everything about a tree’s fate—whether it thrives for centuries or dies in its teenage years—depends on it.
For him, tree care comes down to a “golden trifecta”: water, oxygen, and organic matter. Without them, trees in cities are chronically stressed. They might leaf out in spring, but underground they are suffocating, gasping for air, drowning in one season and parched the next. That stress weakens their immune system, making them vulnerable to pests, disease, and premature death.
“Eighty to ninety percent of issues urban trees face,” Erwin told me, “come from problems in the growing place.”
Even the tree itself contributes. Every six weeks, small feeder roots die back, adding new organic matter to the soil. That cycle of decay and renewal feeds the underground ecosystem—if, and only if, cities give trees enough space and oxygen to function naturally.
Trees as the new sewer system
For decades, cities have announced ambitious planting campaigns: 10,000 trees here, 50,000 there, a million for climate action. Erwin is blunt about the flaw in this approach.
“In the Netherlands, we are planting a new variety and calling them ‘climate trees.’ But it’s not the tree that saves us. It is the climate-adaptive growing place that saves us.”
In Tilburg, his team proved it. By designing underground growing places that capture stormwater, they made expensive new sewer pipes obsolete. Instead of rushing water into overloaded drains, they divert it to the trees.
“The tree is the new sewer system,” Erwin said, grinning.
It’s not just greener—it’s cheaper. Sewer upgrades cost millions, but growing places intercept the same water at a fraction of the price. The benefits multiply: healthier trees, cooler streets, less flooding, and even tourism. Since the redesign, Tilburg has seen visitors boom from 50,000 bed-and-breakfast bookings a few years ago to 2.5 million today. People are drawn to a city that feels alive, shaded, and green.
And crucially, Erwin points out, the money came not from parks budgets, but from water boards. “I am not only the green man,” he told me, “I am also the water man. And in the Netherlands, the water boards have money.” By aligning trees with water management, he elevated their political importance.
Why city trees live fast and die young
And yet, most city trees never get the chance to become adults. A tree is only considered mature after 60 to 80 years, but the average Dutch city tree is cut down at age 27.
Why? Because every 30 years, streets are ripped up to replace pavement—and the trees are taken with them. Erwin calls this cycle of canopy loss wisselgroen: literally “swap-out green,” but better understood as “disposable green.”
It’s tragic. Adolescent trees provide only a fraction of the cooling, carbon storage, and biodiversity benefits of mature ones. Worse, they are cut down just as they begin to flourish.
Even well-meaning policies sometimes miss the point. Some Dutch municipalities now require homeowners who cut a tree to plant one to twelve new ones in its place. But Erwin pushes back: “If you cut an 80-year-old tree, planting twelve saplings doesn’t replace it. What matters is canopy volume. Sometimes one tree is worth 400 little ones.”
“We are obsessed with stems,” he said, “counting how many we plant. But what we need is space for trees to live long lives.”
The Lorax with a spreadsheet
Erwin has some tough love for his peers. “Tree professionals are softies,” he told me, shaking his head. For too long, green advocates accepted compromises—less soil volume, fewer resources, shorter timelines. Erwin decided to change that.
He became what he calls the “Lorax lawyer.” Like Dr. Seuss’s character, he speaks for the trees—but his language is Excel.
“If you asked for 50 cubic meters for sewer pipes or internet cables, no one argues. But for trees, suddenly it’s negotiable. I say no. If you don’t give the tree what it needs, it won’t work. And when you show the numbers, they listen.”
His advice to the next generation of tree professionals is clear: make civil engineers happy. That means designing pavements that don’t buckle, calculating precise water balances, and backing every request with data. It’s advocacy through spreadsheets—and it works.
Planting for a future you’ll never see
A Dutch proverb says: “Boompje groot, plantertje dood.” By the time the tree is grown, the planter is gone. Planting is always an act of faith, a gift to future generations.
Erwin designs growing places for 80-year lifespans, not election cycles. He fights for existing trees, not just new ones. And he measures success not in press releases about how many saplings go into the ground, but in the shade and shelter that mature giants provide decades later.
His motivation is deeply personal. “My children will come here in the future,” he told me, looking out over the square, “and they will see the trees growing.”
For him, the city only truly comes alive when its people can sit in the shade of a tree, feel the breeze rustle its leaves, and hear birdsong overhead.
Why this matters for the Internet of Nature
What struck me most in Tilburg was how invisible all of this is. Tourists snap photos in the square, locals stroll across its stones, and few realize the careful choreography happening underground. Yet this hidden layer determines whether the city’s trees live long enough to cool its summers, clean its air, and hold its rain.
That’s why Erwin’s work is the Internet of Nature in action. It’s about making the unseen visible, valuing what’s taken for granted, and blending natural and technological solutions to reimagine urban life. Sometimes that means sensors and data dashboards. Sometimes it means plastic crates buried under a plaza. But always, it starts with the growing place.
Because in the end, a city is only as resilient as the soil it builds for its trees.
Happy trails,
Nadina
Prefer a different platform? Listen on Spotify, Apple Podcasts, or wherever you get your podcasts.
