There is a bent Scots pine on my cycle route into town that makes me smile every time I pass it. It is bent in an improbable manner, like it didn’t get the memo that street trees are mostly straight and restrained in their demeanour. It leans over the cycle path with one of its huge limbs stretching out horizontally before righting itself, like a seat for a giant.
On a very ordinary stretch of road, it is an unexpected character. Surrounded by boring box units and universal architecture, where every city feels more or less similar, it is urban trees like this that bring identity to our world through colour, sound and seasonal change.
This year, they are finally being celebrated as the Woodland Trust prepares to name its tree of the year. In the running, a series of city dwellers: a black poplar on a housing estate in Manchester that has thrived as industrial manufacturing polluted the soil and air, a holm oak in Exeter that survived the blitz, a walnut in Perth that, with its eye-catching boughs, is doing an excellent job of concealing a shopping centre, to name just a few.
The role of trees like these in concrete environments is often overlooked. A city without trees is a city without birds, without autumn leaves to crunch, without new green to welcome spring, without somewhere to climb, to hide, to lean, to kiss, to cry, to sleep, to make memories. There’s a growing body of evidence to show how time spent with trees improves our wellbeing, to say little of what services they provide for us, too.
A mature urban tree with a big canopy provides immediate shade on a hot day, and shelter from the rain and the wind. Well-planted trees also greatly reduce the risks of flooding. Trees and hedges capture and temporarily hold pollutants, both physical particles and gaseous ones, too.
Leaf size, texture and arrangement matter, and not all species are created equal. Rough, hairy and needle-like leaves, like those found on a pine, capture more pollutants and a wider range of particles than simpler, smoother leaves. Scale matters, too: a large belt of trees can significantly reduce pollution.
In urban areas, sweeping rows of trees are hard to come by. But exciting new planting methods show that urban forests still have a vital role to play. The Miyawaki method mimics the dense natural regeneration of a forest, with trees planted extremely closely together to encourage much faster growth. If you’re near the Horniman Museum in south-east London, then you can see head gardener Errol Fernandes’ version: a 300 sq metre microforest acting as a greenscreen to block out the view of the busy south circular road.
The right plant in the right place is important. Trees need to thrive, not just survive, and urban trees have to withstand a lot: poor soil, higher urban temperatures, being knocked and tugged at, being used as a bike stand, or a noticeboard, among many other things. But if you can get the right tree into the environment it will benefit wildlife, even if it just makes a perch for a passing bird.
The older a tree gets, the more it has to offer, with more nooks and crannies to become places to sleep, rest or nest – not just for birds, but also for moths, spiders, beetles and all manner of other insects, and fungi and lichen, too. A mature tree can be a whole ecosystem in itself – especially important in the depleted natural environment of our cities.
More than 80% of the UK population lives in a city or town, and some of these places have an impressive number of trees, but sadly all too often these trees are undervalued. They are seen as taking up too much space, blocking progress in building roads, housing or infrastructure. Another of the contenders for tree of the year is an elm in Sheffield that was destined to be felled by the local council in 2017, but was saved when a rare white-letter hairstreak butterfly was found laying its eggs on it. It is one of 1,000 remaining mature elm that have survived Dutch Elm disease, which has killed 60 million others across Britain.
We need to continue to protect these champions – the venerable and handsome elders – but also those wily, scrappy, less-than-perfect ones, too, who are working just as hard for us. Together, they make the forest we need to thrive in our cities. One of the best ways to do this is to notice them, to get to know them, to introduce other people to your favourites. The white hairstreak might have protected that elm, but it was saved because people loved it. It is a reminder of all the other creatures – the more-than-human, with whom we share our environment – who consider these urban giants part of their home, too.
Alys Fowler is a gardener and Guardian columnist
