IN 1786, the new-built bridge over Pease Dean on the Berwickshire coast was one of the wonders of the age.

From the span to the gorge below is a sheer lurching drop, 130 feet top to bottom, that deserves the word "vertiginous". On a bright winter's day you can look into the trees' canopy as the leaves whisper through a lexicon of gold, red and green, and glimpse the cold burn below.

For those who marched their armies north and south, the gorge – in fact, two gorges conjoined – was a problem for centuries. Oliver Cromwell, smarter than the locals, worked out instantly that a handful of men could have held up his invading force for weeks, there at the sea's edge. Few travellers leaving "Coldinghamshire", whether commoners or kings, looked forward to Pease Dean. Some took three days to get over or around. No-one then called it a blessing.

What you see now, stuck behind a tractor on the A1107 after Coldingham Moor and the startling sea views, is a remnant, the surviving fragment of a vast and ancient forest. The romantically-inclined call it the Wild Wood, for the native blanket that once lay over most of the island of Britain. They talk of "ancient sessile native oak woodland". They mean the oak, the hazel and the ash. They mean things that got left behind.

The 1786 bridge transformed the old Berwick-upon-Tweed to Edinburgh turnpike road. In modern times, the A1 swerves away from Pease Dean, much as the east coast rail line did before it. In no age has there been a point or a profit in trying to clear the old woodland from the precipitous gorges. Hence the surviving wood. Attempts were once made to add sycamore and conifers to what nature did unaided, but these days the Scottish Wildlife Trust prefers to clear such incomers from its 33-hectare reserve. The point now is to restore what was native and natural.

For that, some more luck will be needed. Fraxinus excelsior, the common ash, might not be common for much longer – the fungus Chalara fraxinea threatens the species with extinction. Rudyard Kipling's Puck Of Pook's Hill made his oaths and magic "by Oak, Ash and Thorn!" By means less supernatural than cloddish, Coalition ministers have allowed chalara – commonly known as "ash dieback" – out of the wood trade and into the wild. By most reckonings, 80 million trees are at risk: after the elm falls the ash.

No-one mistakes me for Mother Nature's son. I'm the sort Joni Mitchell had in mind when she sang: "You don't know what you've got 'til it's gone." It's not obvious to me why the lepidopterists, mycologists and conchologists – admirers of butterflies, mushrooms and snails – cherish Pease Dean. I know you can see buzzards around there, and grey herons, and bats. The Lesser Whitethroats and Grey Wagtails are news to me, though. My ignorance is the wrong side of sublime. That makes me part of the majority.

I know this much about ash trees, though: bluebells like them – the ash favours a stream's edge and lets plenty of sunlight through its paired leaflets. I like bluebells. Meanwhile, incompetent spluttering ministers who ignore clear warnings and cut funding for organisations best placed to deal with blight, I can take or leave. Picturing Pease Dean reduced, defeated after all those centuries of tenacity and survival, is beyond even my limited imagination. The timber always has a price, no doubt, but the wood cannot be valued.

On Friday, finally, the Government woke up to the devastation facing ash trees all over Britain. A meeting of Cobra, the emergency committee that usually worries over terrorist threats, was convened. Most of the main bodies concerned with trees – the Forestry Commission, The Woodland Trust, the Scottish Wildlife Trust and others – had already chipped in with plans to prevent chalara from wreaking havoc. Denmark, with up to 90% of its ash trees infected, was being mentioned in every report. Then some journalist would ask why all of this had escaped Whitehall's notice.

Ash dieback was first spotted in Poland in 1992. It began to appear in Denmark seven years ago. In 2009, the Horticultural Trades Association toured that country and afterwards told the Department for Environment, Farming & Rural Affairs that an import ban was required. The Coalition Government, it is now alleged, did not consider such a move "appropriate".

Last week, as a partial ban was announced – ash firewood and woodchip, presumed to be heat-treated, will still be allowed – it became obvious that Britain barely bothers to regulate the import trade in trees. While Ireland was preparing to declare itself "a fortress" against chalara, the UK Environment Minister, David Heath, could only tell the Commons that "everyone took their eye off the ball in not recognising the threat to the Danish forests".

In other words, nothing had been learned from the Dutch elm disease catastrophe. That blight was first reported in the 1920s, yet left unchecked until the 1960s, when the felling of tens of thousands of trees across Britain became unavoidable. Where the natural world is concerned, official attitudes have not improved in 80-odd years.

So who'll save the ash? Given its title, the Forestry Commission might be expected to stand in the front line. Last week, however, a leaked document compiled in 2011 showed the commission, in its English incarnation, warning ministers that funding cuts demanded in the Government's spending review would leave "no capacity to deal with costs of disease or other calamity". Those words were written, needless to say, even before chalara was identified in an East Anglia nursery.

Some 100,000 ash trees have already burned, many of them in Scotland. The latter fact is no mere detail. Scotland has more trees, of all sorts, than any other part of Britain. A "Scottish Forestry Strategy" was launched in 2006 with the aim of increasing the land area covered by woodland from 17.1% of the total to 25% in the second half of the century. Nor was this intended to come through an expansion of dreary pine plantations. Central to the scheme, even now, is the restoration of native woodland.

Chalara fraxinea was not anticipated, however. If it is wind-borne, the burnings might not help. If a supposedly "promising" possible treatment to prevent the fungus from rotting leaves and killing trees fails to live up to its billing, modern forests and ancient woodlands alike might be beyond saving. But so what? Surely we can always plant more trees? Does the species matter much in a country whose population is mostly urban and generally ignorant of nature?

Where I live, place names tell the story. In the borderlands, there are Ashtrees, Ashiebank, Ashieburn and Ashkirk. At Berwick, on the Tweed, anglers try at Atlantic salmon at Ash Tree Pool. Old books will remind you that once upon a time every farm implement imaginable was formed from well-tended ash. Life depended on it. The nature of places, the continuity of their identities, has also depended on it. Inevitable change only becomes comprehensible if some things, living things above all, can endure.

Sometimes, at Pease Dean, the sight of bluebells combines with the smell of wild garlic. This isn't an urbanite romance: in this house, we eat the latter. And it isn't a townie fantasy to say that while I couldn't identify the mating song of a budgie, I can tell that certain combinations of birdsong happen most often in singular places. Remove one thing and the rest collapses. Take a tree from the landscape and the landscape changes.

Better-informed people report that lots of mosses, lichens, bugs and such depend on the ash. There's a moth, the Tawny pinion, that exists entirely because of this tree. There are half-a-dozen other rare, unregarded and tiny beasties with no other reason to live than the ash. Still: does even that make the threat of devastation a big deal?

It probably depends on what you mean by a big deal. Norse legend invokes Yggdrasil, the Tree of the World, of rebirth and healing. Nine worlds were said to rest on the great green plant, and it united heaven and earth. If it was threatened, thought ancient Scandinavia, all existence would be put in peril. Yggdrasil was an ash tree, "the world-ash". The first man, one Ask by name, was shaped by Odin from an ash. The Norsemen believed, if you like, that humankind really did come out of the trees.

You don't need religion, new age or old, to sense a connection with these plants. Others can argue that people raised in Britain have an almost atavistic feeling, a kind of collective memory, for the almost-gone Wild Wood. I wouldn't know. But I do know that I feel better, in country or in town, with trees around. AE Housman put it like this: "Give me a land of boughs in leaf, / A land of trees that stand; / Where trees are fallen there is grief; / I love no leafless land."

Poets are never done finding metaphors for human affairs in the lives of trees. How long will it be before someone works Government neglect and blind stupidity into a verse on the dying ash? Ironically – poetically? – enough, its logs burn well, and give out little smoke. Not far from where I sit and write this, you can fill a pick-up with logs cut from ash for £120. That's someone's livelihood, but for how much longer? The ash burns more sweetly than all the carcasses incinerated amid foot-and-mouth: another blight, another metaphor.

In one sense, there are no natural woodlands left. How could there be? Even in inaccessible places such as Pease Dean they would not stay safe for long without guardianship. The modern world would fell those valuable trees in a moment. No doubt saplings would be planted in return, in the name of "sustainability". But there is nothing sustainable when the likes of chalara is abroad. You could chance another metaphor and say that nothing natural is sustainable when witless governments abhor "regulation".

Chalara fraxinea is loose, at the time of writing, in 32 locations across the UK. Burning aside, the Forestry Commission's best effort thus far is to threaten landowners who fail to destroy diseased trees with fines of up to £5000. The sanction might have some effect, but it speaks of desperation. Does the commission propose to check every park and garden? Besides, how exactly will a fine after the fact prevent the blight from spreading?

Ash dieback was first discovered in Scotland at Knockmountain, near Kilmacolm. It has since been discovered in Moray, at the 240-hectare nursery owned by Christies of Fochabers. Other outbreaks have been mentioned, but not yet disclosed publicly. That situation is liable to change by the day. Statutory plant health notices and Cobra committees count as too little, attempted too late.

At Pease Dean, little has changed since Longshanks came into Scotland. Only the surrounding landscape, once thick with trees, has altered. That woodland was burned or felled or nibbled clear by sheep.

The oak and hazel and others in the Pease Dean gorges will survive, no doubt. Perhaps the ash too will be lucky once again.

Still, on a clear winter's day when the leaves begin to fly, you can't help but wonder why mere luck should still be needed.