To Britain
Elena Marsh looks at efforts to bring the greybeam back to Britain
A
ASome 28 million greybeams - nearly 85 percent of all those in Britain - were lost across the 1970s and early 1980s to a fungal disease. Once it had passed, the greybeam, for so long a familiar giant of the countryside, slipped almost from public memory. There are grounds for optimism now that the species might be coaxed back into the woods and fields of central and southern England, though any recovery would begin from almost nothing. "Unless you saw the countryside as it once was, the scale of what happened is hard to take in," says Marek Sobol of the Native Woodland Alliance. "It's only in old photographs that it really hits you: these were huge, commanding trees, and then they were gone."
B
BFor centuries only beech was ranked above greybeam among the hardwoods British craftsmen preferred, and across much of the country it was the most conspicuous tree of all. Nor was it tied to one habitat: besides forming its own stands, it wove itself into the oak, birch and hazel woods of the lowlands. People had used it since the Bronze Age, when its timber was shaped into simple tools, and it became the favoured wood for shields and early swords. By the eighteenth century it was planted far more deliberately, its timber going into everyday goods such as packing cases and household furniture. Because it withstood repeated blows so well, it was also chosen for anything that had to absorb heavy impact - mining machinery among them, along with the hull of the nineteenth-century clipper the Silver Petrel.
C
CWhat does the damage is a fungus that clogs the greybeam's vascular system - the network carrying water, nutrients and food through the tree - so that its branches dry out and die. An earlier outbreak in the 1930s flared briefly before fading, but a second, far deadlier wave broke out in the 1980s, brought in on consignments of greybeam timber imported from the Baltic. Shipped as logs bound for furniture-making, the wood still carried its bark, and that intact bark made an ideal refuge for the greybeam bark beetle, the insect that ferries the fungus from tree to tree. Far more aggressive than anything before it, the strain the beetles brought this time killed off most of Britain's greybeams.
D
DGreybeams have not disappeared from the southern counties, but what remains is mostly stunted specimens tucked into the low hedgerows between fields. "There are still millions of little greybeams in the hedges, but the beetle finds them the instant they grow past a certain size," explains Dr Ingrid Halloran, who helped compile the recent survey The State of the Greybeam. As soon as a trunk thickens to between twelve and eighteen centimetres across, it becomes just the right home for the beetle to breed in and the fungus to take hold. Even so, a scattering of ancient trees, some several centuries old, have been logged in counties such as Shropshire, having somehow escaped the epidemic. The way forward, Halloran maintains, is to find these survivors and work out what set them apart when so many others died - though the effort is held back by how few old trees remain to study. "Is it avoidance, tolerance, or real resistance?" she asks. "We don't yet know how the three balance out. What I cannot accept is that it all comes down to chance."
E
EWhether the greybeam can ever come back rests heavily on trees that either fight off the disease or tolerate it, so any large-scale reintroduction would lean on existing or new hybrids bred from resistant species, most of them not native. A fresh generation of saplings has been raised and deliberately put to the test: a narrow cut is opened in the bark and a trace of the pathogen slipped inside. "What strikes you is the sheer speed of it," Halloran says. "Come back after four to six weeks and the resistant trees look untouched, while the vulnerable ones have already dropped their leaves - some have died outright."
F
FSo bound up is the greybeam with British life that it has never wanted for champions. One is Tomas Ashworth, keeper of the National Greybeam Collection in the Norfolk town of Cromer. "I watched the disease take hold when I was a boy," he recalls. "The greybeam felt like part of the English countryside, and then I stood watching the trees shed their leaves - it never left me." Cromer now counts near 12,000 greybeams, and their survival seems to owe much to where they grow: stiff winds off the sea make it hard for the beetle to gain a foothold in this exposed coastal town. The position is far from safe, all the same. "The beetles could move straight in the moment we drop our guard; the danger is right on our doorstep," Ashworth warns.
G
GAll this, Halloran concedes, raises the question of whether the public will accept it. "If we put the greybeam back and part of what we plant isn't strictly native, does that trouble us?" To her mind the ecological case is powerful: the trees would shelter wildlife, which she counts among the gains. Others are less convinced. Marek Sobol sees a snag. "On the surface it sounds fine," he says, "but you're trading a native tree for a horticultural analogue. In effect, you're cloning." He points, too, to the risk of importing new diseases with the fresh stock. Rather than plant afresh, his organisation would sooner safeguard the greybeams that have pulled through on their own. "Sometimes the wisest thing is to step back and let nature take its time; leave the survivors be, and resistance may come of its own accord," he says.
H
H* horticultural analogue: a cultivated plant that is genetically very close to a naturally occurring species
Kéo chỉnh
Question 1 - 5
Which paragraph contains the following information?
A
B
C
D
E
F
G
H
1.
how the small number of old trees still standing holds back research
2.
contrasting views on whether bringing the tree back to Britain is worthwhile
3.
an account of the way the infection first reached the country
4.
the particular circumstances that have spared one place from the disease
5.
the point in a young tree's growth at which it begins to be at risk