Mapping and data-gathering are proving to be valuable new weapons in preserving these arboreal defenders of the eco-system, writes Catherine Slessor
Some years ago, a mature plane tree in London’s Berkeley Square was ‘valued’ at £750,000, making it the most expensive specimen in the city. Factors in the calculation of its worth included its size, location, condition and age; it formed part of a stand of trees originally planted in 1789. Commodifying a tree may seem absurd, but it makes the point that the presence of nature in cities is precious. And if putting a price tag on it is the only way to bring this home to landowners, developers and councils, all shiftily eyeing their chainsaws, then perhaps it does not seem so unhinged.
A report produced in 2016 by the London i-Tree Eco Project went further, calculating that London’s 8.5 million trees were worth £6.1 billion in terms of replacement cost. Benefits to the ecosystem included storm water alleviation, carbon storage and pollution removal. In this respect, the London plane, ‘discovered’ by botanist John Tradescant, head gardener to Charles I, is an arboreal miracle. Requiring little root space, it can survive in a range of soil types. Its leaves are especially effective at absorbing noxious emissions and its distinctive camouflage-patterned bark flakes off so that the tree can cleanse itself of pollutants.
Berkeley square web
Yet urban trees of all kinds are still under assault, still being consigned to municipal wood chippers by councils that see them as either a public nuisance or potential liability. On one level this could be seen as encapsulating the increasingly strained relationship between humanity and nature. But the taming of landscape, whether for agriculture, building or recreation has always been deeply contested, inflected by power, money and politics.
The wellbeing of urban trees has never been more important
In the current struggle to green the city, initiatives that focus on mapping and data-gathering are proving to be valuable new weapons in the ecologists’ armoury. For instance, London now has a digital database of street trees produced by the GLA, recording the location and species of trees on public roads and paths. From this it is apparent that the London plane does not have the field entirely to itself, sharing pavements with over 20 species, from alder to willow.
More recently, the Massachusetts Institute of Technology has launched Treepedia, an innovative metric that uses Google Street View panoramas to produce the Green View Index, through which cities can evaluate and compare green canopy coverage. Rather than count the individual number of trees, it analyses the amount of green perceived when walking down the street, elevating the experiential over the quantifiable.
London mayor street trees map
Initially encompassing 10 cities, including London, Boston, Geneva and Tel Aviv, the aim is to roll out Treepedia to map other conurbations around the world.
‘The wellbeing of urban trees has never been more important,’ says Carlo Ratti, director of MIT’s Senseable City Lab, which devised the programme. ‘Our index allows direct comparisons between cities, encouraging local authorities and communities to take action to protect and promote the green canopy.’ Treepedia effectively enables city dwellers or other interested parties to view the location and size of trees within their communities. Armed with this information, they can submit input to help tag and track existing specimens, as well as advocate the planting of new ones.
With its overtones of 70s eco-protests, ‘tree hugger’ was always regarded as a pejorative term, but a new generation of digital tree huggers can now leverage technology to explore and interact with the green canopy of their city. And in reclaiming tree planting from the dead hand of municipal strategising, it suggests a more agile and responsive way of making the bucolic dream of rus in urbe a tangible reality.
London plane leaf042 crop