Three redwood trees tower like skyscrapers above Wakehurst’s Elizabethan mansion. But at 40 meters (131 ft) high, these are almost saplings; They are not even 150 years old and are almost twice as high as Cleopatra’s Needle.
“They are now some of the tallest trees in the UK and are starting to rise above the forest canopy. But if they reach their full potential they will be three times taller than most trees,” says Dr. Phil Wilkes. One or two of these Californian imports may be curiosities, such as the 100-foot-tall redwood that was debarked in 1854 and displayed to Victorian crowds at the Crystal Palace in southeast London until it was destroyed by fire in 1866. .
But there’s more to the UK than just a handful of alders, and Wakehurst has many more than just these three trees. The Victorians were so impressed that they brought so many seeds and seedlings back from the US that there are now around 500,000 in Britain. California has about 80,000 giant sequoias, which is the official name for giant sequoias, as well as coast redwoods and dawn redwoods.
When Wilkes and his fellow researchers at Kew and University College London highlighted the numbers last week, they sparked a wave of interest and visitors to Wakehurst’s gardens didn’t talk much about it otherwise.
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“People often worry that these are an invasive species, but they seem pretty benign,” says Wilkes. “There is no evidence that they self-seed.”
This may be because they are babies that are not yet ready to reproduce (redwoods live up to 3,000 years) or because their cones often open in the heat of a forest fire. This means that every single one of the trees in the UK has probably been planted. It also explains how half a million giants manage to hide in plain sight.
“They were valuable items,” Wilkes adds. “They were often planted on a mansion and a driveway lined with rows of redwood trees. These houses burned or were destroyed, but the redwoods are still there.”
Redwood enthusiasts have mapped places from people’s backyards to parks to suburban streets where homes are built around the trees. However, as redwood trees grow, opportunities for conflict arise; As on Canons Drive in Edgware, north London, some residents here are fighting to keep the street with giant redwood trees under threat from insurers worried the roots will undermine homes.
There are no such concerns at Wakehurst, where redwood trees dot the vast landscape and are arranged phytogeographically, placing plants and trees according to their continent of origin, so visitors can walk North through Australia’s gum trees. American valley.
In a redwood forest clearing interspersed 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 unique,” he says. Their work involves using satellite data and Lidar (light detection and radar) to create 3D laser images of trees; This is a way to measure the size and mass of trees more precisely than the traditional method of measuring the circumference of their trunks.
“You go out into these vast forest areas and it’s off the beaten path, once you get under the canopy it’s a whole different world. It really draws you in. It is so fascinating; “It is one of the most complex environments you can work in and it is truly rewarding.”
Trees have an enduring appeal to people. Last year, researchers at the University of Derby found that people value trees more than their neighbours, while forest bathing is a Western interpretation of the Japanese relaxation practice. shinrin-yoku – increased in popularity.
Perhaps the unique appeal of redwood trees is their scale; The oldest of these predates the English language and the tallest is 115 meters higher than St Paul’s Cathedral. And if they had been discovered by the Elizabethans who built Wakehurst and believed that man’s duty was, as historian Keith Thomas put it, “to level the forest, to till the soil,” they would probably have been cut down, like most forests in England. “Remove predators, kill vermin, plow ferns, and drain swamps.”
In the more ecologically enlightened 21st century, Wilkes identifies a different risk: The desire to find solutions to the climate crisis will lead to hasty choices.
“In Wales they are planting these as a way of offsetting your carbon emissions. They are building a redwood plantation in the Brecon Beacons [Bannau Brycheiniog] Is it the right thing to do?”
He is skeptical, saying native broadleaf woodland has many more benefits than being a carbon sink.
“Trees in the city are undervalued, but they actually have a lot of value,” he says. “Carbon is one way of giving them value, but it’s probably one of the least important things they provide; they cool cities, flood reduction, health effects, biodiversity. They are not a way to offset carbon. “Decarbonization is the only way.”
California’s swinging giants
For millions of years, the world’s tallest trees have graced California’s peaks and coasts, growing through centuries of change. First established in groves along the Sierra Nevada mountain range, towering redwood trees are as durable as they are stunning.
However, the past century has seen significant changes in these landscapes and damage to forests. Devastating droughts and scorching temperatures triggered by the climate crisis have added new stressors for redwoods, especially the famous giant sequoias, which are now struggling to recover from massive fires.
Part of the problem stems from California’s gold rush; Settlers come here with an inordinate appetite 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 fire suppression has created excess vegetation that paves the way for larger, more destructive fires.
Stripped of their toughest ancient trees, forests now face a devastating cycle: Dying trees leave more fuel for dangerous fires. Vulnerable trees are also increasingly subject to attack by native bark beetles, which feed on their spongy red trunks until they fall over. Scientists estimate that roughly one-fifth of California’s remaining giant sequoias have died in recent years due to a combination of these factors, including a particularly severe wildfire in 2020 that destroyed up to 10,000 mature trees.
Efforts to preserve them are underway in California as federal agencies, states and indigenous communities work to bring good fire to the land and seed vanished landscapes with new trees. Threats from global warming continue to increase, and changes are outpacing mitigation efforts.
In addition to their picturesque nature, trees are also vital in maintaining healthy ecosystems in California by capturing carbon dioxide, providing a cooling effect when temperatures rise, and providing vital habitat for other forest creatures. When they disappear, landscapes will be changed forever, along with the plants, animals, and people who depend on them.
Gabrielle Canon, San Francisco