When a tree that stands in the city’s way is designated for the chop, many of us just stand by and watch it fall. We shouldn’t be so resigned
IT BEGAN with three large letters: R.I.P. Normally on such a freezing night I’d have rushed straight by in my hurry to get home, but something caught my eye. Pinned to the trunk of a tree I had passed countless times was a scrap of paper – and those three letters.
I hadn’t taken much notice of the tree before. It stood tall and solitary at the edge of a notorious roundabout, a welcome living thing in a sea of tarmac. It was a large elm with deeply fissured bark and sturdy upswept branches. I stretched my arms around its trunk: they scarcely reached half way. What did that ominous message mean?
Back home I discovered what the anonymous note-writer already knew: in two days the tree would be gone, felled as part of a scheme to reconfigure the roundabout to make it safer and more attractive. Streets first laid out in the mid-19th century, when traffic was light and horse-drawn, would be updated to comply with 21st-century standards, including broad, smooth pavements with no lumps, bumps – or large vertical obstacles. The elm, planted about 130 years ago, did not fit this new streamlined vision.
The thought of a fine mature tree consigned to the chipper for the sake of an extra-wide walkway and a computer-generated kerb line was shocking. What made it worse was that it seemed to fly in the face of current thinking on the value of urban trees. City authorities usually can’t get enough of them. “Green infrastructure” – trees to you and me – is a central component in plans to future-proof towns and cities.
As well as pumping out oxygen and mopping up carbon dioxide, trees help counter some of the most immediate impacts of climate change. They keep us cool by casting shade and providing a natural form of air conditioning as water evaporates through their leaves. They soak up rainwater, reducing the risk of flash floods. They make city life healthier, cleaning the air of pollutants, encouraging people to go outdoors and take more exercise, and making the streets quieter, more pleasant places. They even help cut crime. And, of course, trees also provide habitat for urban wildlife (see “Five things urban trees do for us“).
“People know trees are important, but we are increasingly able to put figures on the benefits they provide,” says Roland Ennos, whose team at the University of Manchester in the UK has just completed a three-year study of some of those benefits. “Rather than saying ‘trees are marvellous’ you need numbers, so you can tell politicians that if you have x number of trees they provide y amount of benefits,” he says. “In New York City, models show that for every dollar spent on looking after trees you get $5 in benefits.” Figures such as these persuaded mayor Michael Bloomberg to promise New Yorkers 20,000 extra trees a year. London’s mayor, Boris Johnson, has promised 10,000 by 2015.
Like London and New York City, my home city of Brighton and Hove is keen on planting trees. Politically, it is the greenest place in the UK, with the country’s first and only Green Member of Parliament and its first Green-led local authority. Best known as a seaside resort and party town, it has another, less raffish side: it is a refuge for elm trees (see “The sheltering streets“).
The city’s Victorian elders chose elms to beautify the streets because they cope with its poor chalky soil and salt-laden winds. When Dutch elm disease swept Europe in the 1960s and 1970s, some 30 million of the UK’s elms died. But Brighton’s were protected by their location, sandwiched between the sea and relatively treeless hills, and by the city’s farsighted policy of destroying any trees that showed early signs of infection.
Today, Brighton has more than 17,000 elms, which have been designated as the UK’s National Elm Collection. “There are few mature elms left in the countryside to remind us of the magnificent stature of truly large native trees, and even in botanic gardens they are few and far between,” says Tony Kirkham, head of the arboretum at London’s Royal Botanic Gardens, Kew. “If you want to see elms you have to go to Brighton or find one of the last enclaves in hidden corners of the English countryside.” And the tree at the roundabout wasn’t just any elm, I discovered, it was a Wheatley elm, a rare subspecies.
The following day, a Sunday, I hurried back to the tree to find that it had sprouted more messages and bows of green ribbon. At first light on Monday, I returned to witness the felling and joined a knot of people who had gathered to mourn the loss. Passers-by stopped to ask what was happening. Almost without exception, they were shocked and upset that “their tree” was about to go. The most frequent question was: “What can we do to save it?”
At midday there was still no sign of a tree-felling gang. Then word came that work had been postponed for three days. By now the little knot of people had grown larger and more purposeful. We began to think that maybe, just maybe, it was possible to save the tree, which had become known affectionately as Elmo. We had the support of local MP Caroline Lucas and a burgeoning protest by local residents, but what we needed most was time – enough to persuade the decision-makers to change their minds.
Almost everywhere big trees are vanishing from city streets. Some attrition is inevitable, especially in nations like the UK where many urban trees were planted 150 years ago or more. Disease, lightning strikes and old age take their toll. But healthy trees are disappearing too. Many are victims of development and new road schemes. “Planners consistently fail to appreciate the real value of trees when they make decisions, and highway authorities usually see trees as more of a problem than a benefit,” says Jeremy Barrell, one of the UK’s most eminent arborists.
Some mature trees are felled because they pose risks more perceived than real. Cash-strapped and risk-averse, authorities equate big and old with potentially dangerous, and fell rather than risk claims for injury or death. “There’s an attitude of better safe than sorry,” says Barrell, “but often pruning is all that’s needed to lower the level of risk.” Insurers, too, are reluctant to risk claims for damage to buildings, and press for the removal of trees on the flimsiest of evidence. To make matters worse, some authorities readily approve the removal of traditional large woodland species and their replacement with smaller species. These “lollipop trees” are cheaper and easier to maintain, but they will never reach the stature, nor provide the benefits, of an elm, beech or London plane.
Leaving aside the beauty of mature trees and the emotional attachment people have to them, big trees provide more benefits than small ones. They have a greater cooling effect. “A bigger crown means more shade and more water loss by the leaves,” says Ennos. They are more effective when it comes to flood prevention. One study found that a tree’s capacity to intercept rainfall doubles with every 10 years of growth. And a large healthy tree can remove 70 times as much pollution as a slender young one.
“Mature tree loss is a real problem in cities,” says Ennos. But it is one that’s hard to quantify. “The loss is slow, so no one really notices – an odd tree here and there arouses local dissatisfaction, but it is not joined up, so the scale of the problem remains hidden,” says Barrell. “It’s not just in the UK. Internationally, lots of old trees are being lost. Some of the oldest, and ones with cultural associations, are irreplaceable.”
Growing recognition of the importance of urban trees has forced governments to take steps to make cities leafier. Yet when it comes to decisions on individual trees, the message seems to get lost among conflicting policies and priorities. “At the moment we take them for granted,” says Kirkham. “But they deserve their space in the urban environment and we must fight to preserve them.”
As in Brighton, protesters are increasingly taking matters into their own hands. In California, students stripped off and perched naked in a threatened grove of oaks as part of a two-year protest. Campaigners in Charleston, South Carolina, are on the verge of victory after a five-year struggle to prevent the destruction of the monumental Angel oak, one of the most historic trees in the US.
With the tree’s three-day reprieve almost up and the authorities sticking resolutely to their plan, two protesters decided to take radical action. A little before midnight and in sub-zero temperatures, they climbed into the branches and settled into a makeshift camp high above the street. It was risky, but it bought more time. On the ground, campaigners organised a petition, fired off emails and wrote blogs. By now the protest had grown so large it included legal experts, tree experts, seasoned battlers against bureaucracy, artists to make posters and banners, and volunteers to deliver leaflets. The heroic tree-sitters endured two very unpleasant nights made bearable by a stream of well wishers offering hot food and hot water bottles. Then the authorities agreed to talk.
The next few weeks were a whirl of campaigning. Soon there were over 4000 names on a petition, more than enough to trigger a debate by the council – and a vote on a rethink. The media milked the story, and opposition politicians seized the opportunity to appear greener than Green. By the time the vote came around, not one local politician was prepared to raise a hand against the tree. A month later, with continued pressure from campaigners, an alternative road plan was approved, complete with stately elm. In the end, what probably helped most was the irony of a Green local government presiding over the felling of a fine specimen of a species that the city had put so much effort into saving.
The elm is still standing and safe for the foreseeable future. The newly widened pavement sweeps out around it – a solution so simple it is hard to imagine why it took such efforts to achieve it. But one saved tree doesn’t change the big picture. Until there are tougher policies to protect big old trees, often the only thing standing between tree and chainsaw is a knot of very determined people.
This article appeared in print under the headline “Saving Elmo”
Five things urban trees do for us
CLEAN THE AIR Trees save lives by trapping pollutants including PM10s and PM2.5s, small particles that cause respiratory disease. In a study of 10 US cities, David Nowak of the US Forest Service found that trees removed between 4.7 and 64.5 tonnes of PM2.5s a year, preventing one death per year on average, but eight deaths in New York City.
REDUCE FLOODING Their leaves intercept rainwater, and with planting pits that improve drainage, trees can reduce surface runoff from asphalt by as much as 60 per cent. Large trees with dense canopies, such as elms, planes and limes offer the best protection against flooding.
KEEP US COOL Water evaporating from leaves cools the air, while shade reduces the amount of solar radiation reaching the ground. Researchers at the University of Manchester, UK, found that tree shade lowered surface temperatures by up to 19 °C and that a person standing in the shade feels as much as 7 °C cooler. They estimate that a 10 per cent increase in tree cover in Manchester city centre would reduce the summer heat by 4 °C.
CUT CRIME In Baltimore, Maryland, a 10 per cent increase in tree canopy was associated with a 12 per cent reduction in robberies, theft, burglaries and shootings. Austin Troy at the University of Vermont in Burlington, who made the connection, suggests trees foster a stronger sense of community and encourage people to spend more time outdoors, making it harder for criminals to go unnoticed.
LOWER ENERGY BILLS By protecting buildings from summer sun and winter wind, trees can reduce the amount of energy used for air conditioning and heating by up to 30 per cent. Taller, more mature trees with a larger canopy offer more shade and shelter.
The sheltering streets
Brighton and Hove is the UK’s stronghold for mature elm trees. By rigorously defending its trees against Dutch elm disease – a battle that continues to this day – the seaside city is one of the few places in the world with elm-lined streets.
City streets seem an unlikely refuge for trees. With roots confined by concrete and asphalt and leaves surrounded by polluted air, these are tough places for trees to survive. Yet Brighton is not so unusual. Today, some rare and threatened species are more at home in the urban jungle than their original habitat.
Take the ancient and much revered ginkgo. Wild populations – thought to be relics of a time when the tree was widespread – hang on in just a few remote locations in China. Yet it is a familiar sight on city streets around the world, equally popular in New York and Berlin as it is in Asian cities such as Tokyo (see photo, left). “Ginkgos won’t go extinct because they are so widely grown. Street trees are an insurance,” says Peter Crane, former director of London’s Royal Botanic Gardens, Kew, and author of Ginkgo: The tree that time forgot (Yale, 2013).
Likewise, another survivor from the age of the dinosaurs, the dawn redwood, is endangered in its natural habitat in central China, with fewer than 6000 wild trees. However, since the discovery of this “living fossil” 70 years ago, millions have been planted in China and elsewhere. In Pizhou, a city with some 5 million of the trees, one avenue of dawn redwoods stretches 47 kilometres.
Stephanie Pain climbed her first elm at the age of 8. Today she leaves it to younger, more nimble climbers
Article from New Scientist