Three redwoods tower like skyscrapers above the Elizabethan mansion of Wakehurst. But at 40 meters tall, these are almost saplings – less than 150 years old and already almost twice as tall as Cleopatra’s needle.
“They are currently among the tallest trees in Britain and are starting to rise above the canopy. But if they reach their full potential they will grow three times taller than most trees,” says Dr Phil Wilkes, part of the research team at Wakehurst, West Sussex, an outpost of Kew Gardens. One or two of these California imports are said to be curiosities, such as the 100-foot sequoia that was stripped of its bark in 1854 and put on display to the Victorian public at the Crystal Palace in south-east London until it was destroyed by fire in 1866 . .
But there are more than just a handful of redwoods in Britain, and Wakehurst has many more than these three. The Victorians were so impressed that they brought seeds and seedlings from the US in such large numbers that there are now around 500,000 in Britain. California has about 80,000 giant sequoias, the official name for giant sequoias, as well as coast redwoods and a few decorative dawn redwoods imported from China.
When Wilkes and his fellow researchers from Kew and University College London highlighted the figures last week, they caused a wave of interest, and visitors to Wakehurst gardens have spoken of little else.
Related: Plantwatch: Sequoias are making a great recovery after a wildfire in California
“People often worry that it’s an invasive species, but they seem quite benign,” says Wilkes. “There is no evidence that they sow themselves.”
This could be because they are young specimens that are not yet ready to reproduce – redwoods live up to 3,000 years – or because their cones usually only open in the heat of a forest fire. That means all the trees were probably planted in Britain. It also explains how half a million giants have managed to hide in plain sight.
“They were valuable assets,” Wilkes adds. “Very often they were planted near a country house and in a driveway with rows of redwoods. And these houses have been burned down or demolished, but the redwoods still exist.”
Redwood enthusiasts have mapped a number of locations, from people’s backyards to parks and suburban streets where houses are built around the trees. But as the redwoods have grown, there have also been opportunities for conflict, such as in Canons Drive in Edgware, north London, where some residents are fighting to protect an avenue of giant redwoods threatened by insurance companies concerned about the roots that undermine the houses.
No such concerns exist at Wakehurst, where the redwoods are located in different parts of the extensive grounds and are arranged phytogeographically, with plants and trees classified according to their continent of origin, allowing visitors to walk through the gum trees from Australia to a northern area . American Valley.
In the clearing in the redwoods, sprinkled with sunlight, rain and birdsong, Wilkes’ semi-permanent smile turns into a beam. “The feeling of being in a forest anywhere in the world is unparalleled,” he says. His work involves using satellite data and Lidar – light detection and radar – to create 3D laser images of trees, a way to measure the size and mass of trees more accurately than the traditional method of measuring the circumference of their trunks.
“You go into these vast forests and it’s just a different world when you get under the canopy, off the beaten track. It really draws you in. It’s so fascinating; it is one of the most complex environments you can work in, and it is truly rewarding.”
Trees have a lasting appeal to people. Last year, researchers from the University of Derby found that people value trees more highly than their neighbors, while forest bathing – a Western interpretation of the Japanese practice of relaxation known as shinrin yoku – has increased in popularity.
Perhaps the redwoods’ unique appeal is their scale; the oldest existed before the English language and the tallest, at 115 metres, higher than St Paul’s Cathedral. And possibly they would have been felled, like most English forests, had they been discovered by the Elizabethans who built Wakehurst and believed that man’s job was, as the historian Keith Thomas put it, to “level the woods, till the ground, drive away the beasts of prey, kill the vermin, plow the ferns, and drain the fens.”
In the more ecologically enlightened 21st century, Wilkes identifies another risk: that the desire to find solutions to the climate crisis will lead to hasty choices.
“In Wales they plant them as a way to offset carbon emissions. Establishes a redwood plantation in the Brecon Beacons [Bannau Brycheiniog] the right thing to do?”
He doubts that native deciduous forests have many benefits beyond just carbon storage.
“City trees are not appreciated, but they actually have a lot of value,” he says. “Carbon is one way you can give them value, but it’s probably one of the least important things they provide: they cool cities, there’s flood mitigation, health impacts, biodiversity. They are not a way to offset carbon. Decarbonizing is the only way.”
The tottering giants of California
For millions of years, the world’s tallest trees graced California’s peaks and coastlines, growing through centuries of change. The towering redwoods that first took root in the forests of the Sierra Nevada Mountains are as resilient as they are stunning.
But those landscapes have undergone significant changes over the past century, and the forests have suffered. Spurred by the climate crisis, devastating droughts and scorching temperatures have created new stressors for redwoods, especially the famous giant sequoias, which are now struggling to bounce back from major wildfires.
Part of the problem stems from California’s gold rush era, when settlers descended with an overzealous hunger for good timber, cutting down much of the old-growth forests. They also suppressed indigenous land management techniques, including setting “healthy” fires that cleared the forest. A century of firefighting created an abundance of vegetation that set the stage for larger, more catastrophic fires.
Deprived of the most resilient ancient trees, forests now face a cycle of destruction: The trees that die leave behind more fuel for dangerous fires. Vulnerable trees are also increasingly attacked by native bark beetles, insects that feed on their spongy red trunks until they fall over. Scientists estimate that about a fifth of California’s remaining giant sequoias have died in recent years due to this combination of factors, including a particularly severe wildfire in 2020 that wiped out up to 10,000 mature trees.
In California, efforts are underway to protect them as federal agencies, states and indigenous communities work to bring good fire back to the land and seed decimated landscapes with new trees. Threats from global warming continue to increase and changes are outpacing mitigation work.
In addition to their scenic stature, the trees are also critical to maintaining healthy ecosystems in California by capturing carbon dioxide, which has a cooling effect when temperatures rise, and they provide essential habitat for other forest animals. When they disappear, the landscapes will be changed forever, along with the plants, animals and people that have come to depend on them.
Gabrielle Canon, San Francisco