Britain has always loved trees.
That’s why, whatever else you think of the Prime Minister, he united almost the entire nation yesterday with his pledge to plant 30,000 hectares of them a year ‘to enchant and re-energise the soul’.
Wouldn’t it be fantastic if large swathes of this country were once more covered with the mighty oak, beech, yew and other native species which make our countryside the wonderful, leafy patchwork it still so often is?
How marvellous, too, if Boris Johnson’s promise helped line our urban streets with more flowering cherries and plane trees.
But the reality, I fear, might not be so rosy.
For if the Government isn’t scrupulous about which species are planted, Britain could be smothered by invasive aliens that could cripple entire ecosystems.
The reality of Boris Johnson’s pledge to plant 30,000 hectares of trees a year might not be so rosy, writes ROSS CLARK. Pictured: The eucalyptus tree, native to Australia, has a destructive impact on surrounding trees and plants
Such an invasion wouldn’t be the first.
After all, it is exactly what happened a century ago when, facing a shortage of wood to make pit props after the Great War, the government founded the Forestry Commission to re-establish a native timber industry.
From Cornwall to Caithness, the British countryside disappeared under thick plantations of non-native conifers that deprive surrounding plants of water and often leave ecological deserts in their wake.
Now it is happening again.
This time, though, the threat does not come from Scandinavian conifers — but from the Australian eucalyptus, an increasingly popular fuel for wood stoves and power stations.
Not even the most quintessential of stately homes, Chatsworth House, whose oak forest was once so large that it was said that a squirrel could travel from the Severn to the Humber without once touching the ground, is immune to its ruthless charm.
Just this week the Duke and Duchess of Devonshire announced that they intend to plant 6,750 eucalyptus trees in the grounds of their Derbyshire estate.
It is part of a project, they say, to heat Chatsworth House and its greenhouses on renewable energy with biomass boilers that burn 2,000 tons of wood every year.
Of course, it is easy to see why eucalyptus may seem appealing at first. It grows extremely quickly — adding as much as 6ft to its height every year.
Acre for acre, a eucalyptus plantation can produce ten times as much wood as one filled with oak, and twice as much as Scandinavian conifers.
But if that sounds too good to be true, that’s because it is.
For ultimately, the eucalyptus, like any interloper, provides an extremely poor habitat for native wildlife such as butterflies and woodland birds. It also has a destructive impact on surrounding trees and plants.
Having adapted to living in the parched soil and droughts of Australia, the eucalyptus has evolved roots which are very efficient at seeking out water — even if it means depriving surrounding trees.
In South Africa, for example, invasive eucalyptus outside plantations absorb 230 million cubic metres of water every year.
Just this week the Duke and Duchess of Devonshire announced that they intend to plant 6,750 eucalyptus trees in the grounds of their Derbyshire estate
As forester Hugh Davis, who has planted 25,000 eucalyptus on his Cornish estate to feed the insatiable demand from log-burner owners, this week admitted: ‘Underneath … it’s just a desert’.
Moreover, despite being treasured by luvvies and yogis for its soothing properties, eucalyptus oil — found in the wood, leaves and bark — is highly flammable.
The devastating fires which raged in South Eastern Australia in December and January were in part fuelled by eucalyptus trees.
The high oil content in the eucalyptus has become a serious problem in the East Bay area near San Francisco, in the U.S., where early 20th-century landowners planted large numbers of the trees in the hope of establishing a forestry industry.
The trees proved useless as a timber source because the wood often splits, but the abandoned trees have proliferated, rising to heights of 100ft or more.
Realising the fire hazard they pose, the University of California at Berkeley recently had to chop down 19,000 of them for fear of a conflagration on its campus.
Not quite as dangerous, though still worrying, is the tendency of eucalyptuses to shed branches suddenly — owing to a fungus which attacks the trees’ insides.
It is part of a project, they say, to heat Chatsworth House and its greenhouses on renewable energy with biomass boilers that burn 2,000 tons of wood every year
That was one reason I was prepared to pay £600 a few years’ ago for my neighbour to remove a eucalyptus tree which was overhanging a part of my garden where we frequently sit and eat.
All of which begs the question, why on earth are we willing to embark on such a ghastly affair with the eucalyptus?
As so often, the cause of this madness is a blinkered effort to combat climate change by burning wood for electricity.
And the Duke and Duchess of Devonshire are far from the first to be seduced by this ‘renewable energy’.
In fact, entire power stations such as Drax in North Yorkshire generate power this way.
While Drax sources most of its wood pellet from North America to make electricity, it recently published a report praising eucalyptus plantations in Uruguay, where the tree is not native.
The Duke and Duchess of Devonshire are far from the first to be seduced by burning eucalyptus to generate ‘renewable energy’. In fact, entire power stations such as Drax in North Yorkshire generate power this way
Disgracefully, much of this polluting activity is inspired by taxpayer subsidies.
Homeowners who install wood-fired boilers can qualify for thousands of pounds worth of payments.
But that is where its ‘green’ credentials end.
For while trees are certainly renewable in that you can chop them down, burn them and then grow another tree, setting fire to wood actually releases more carbon dioxide into the atmosphere than burning gas.
In fact, given the great amount of time that it takes for a sapling to grow and capture carbon dioxide, a recent Canadian study concluded that if you plant a tree for every one that is burnt, it could take at least 100 years before burning wood could be said to have resulted in fewer carbon emissions than simply by burning fossil fuels.
And that’s before you factor in the fact that wood burning is horribly polluting, emitting large quantities of PM2.5s — microscopic particles which, according to the European Environment Agency, cause 37,800 premature deaths in Britain each year.
All in all, according to an Australian study published in the British Medical Journal in 2015, wood-burning is responsible for 2.4 times as many PM2.5 emissions in Britain as is road traffic.
This is particularly damning for open fires and wood-burners, which are less efficient than large power stations that can burn wood at higher temperatures, which in turn produces less air pollution.
None of this is to say that we shouldn’t plant more forests in the UK.
But we simply must not let this country’s centuries-old fascination with and love of trees serve as an excuse to plague our countryside with lifeless eucalyptus plantations, solely to feed a dirty, voracious wood-burning industry.
To allow this to happen would see all of our noble, eco-driven, tree-planting intentions go up in smoke.