To walk alone in a wood is like trespassing in a fairytale. The whirr of hidden wings; the heliogram flickers of light; the strange rustlings that may or may not be the work of the wind; the sensation of being watched from every angle by a multitude of eyes.

It is no illusion. Life is everywhere. In the branches above our heads, in the rotting hulks of fallen trees, in the compost beneath our feet, the place seethes with creatures driven by instincts older and deeper than human intelligence.

Not even science can destroy the feeling of wonder. The more we understand how all these fragments of life add up to the vastness of “nature”, the more miraculous it seems. If we could make a map of the woodland world, it would look remarkably similar to the human world with which it intersects. No surprise really: both are products of the same creative endeavour. Both are under extreme pressure and both need and deserve our care.

This is why the Woodland Trust, with the support of The Sunday Times, is planning to plant 600,000 trees and create 850 acres of woodland at Sandridge, near St Albans, Hertfordshire. This newspaper has donated 100 trees and is inviting readers to give — £15 will buy land for a tree and pay for its planting and five years of nurture. Supporters include the broadcasters Sandi Toksvig and Eamonn Holmes and Sian Lloyd, the ITV weather presenter, who calls the plan “wonderful”.

For many threatened species, a treescape is nothing less than the gift of life.

Woodlands are like cities, packed metropolitan centres that rely on complex networks of interdependent enterprise. Bacteria, insects, arachnids, fungi, lichens, plants, birds, reptiles and mammals coexist like tradesmen in supply chains, everything feeding something else. Also like cities, they are transport hubs. Residents travel in and out; strangers arrive and settle; refugees come seeking shelter.

As climate change takes effect and the seasons creep forward in the calendar, so migration becomes more important. None of this can happen unless there are routes for creatures to travel along. “Wildlife corridors” take many forms — verges, railway embankments, power lines, stream banks — but the most important, the most evocative and treasured, are hedges. Without these a woodland is not part of a wider world: it is an island.

A particular pleasure of mine is to manage a short section of such a corridor — a length of hedgerow around a small parcel of land in Norfolk. It is a thing of glorious muddle — in part a classic, double-planted stock-proof barrier of hawthorn; elsewhere a tangle of blackthorn and briar, heavily mantled with ivy. As hedges should be, it is dotted with standard trees — holly, maple, bullace, oak — which exponentially increase the volume and diversity of life it supports. An oak may be home to 350 species of insect and 30 lichens.

The hedge is never silent. Ahead of me during the day, mobs of yellowhammers billow in and out. Wood pigeons panic and clap their wings. At night a torch picks out hedgehogs and I know from the din of owls that there are teeming populations of mice and voles.

You don’t have to be an ecologist to recognise that such places are the veins and arteries of our fauna and that the subsidy-driven loss of 120,000 miles of hedgerow over the past 30 years has been a catastrophe. In creating habitats and growing food for humans, we have fragmented the environment and laid un-navigable concrete and asphalt barriers in the paths of other species and marooned them.

Sandridge Wood will be more than an oasis in this desert: it will be a reservoir, its mix of native trees a cauldron of fertility. Deer will haunt the dusk; nightingales will score the night. In the leaf litter, stag beetles will square up like rhinos; white admirals will flicker along the rides and turtle doves lay down their soundtrack of mesmeric calm. Hare will dice with fox; dormice, voles and shrews will dodge blitzkriegs of beak and fang. Spring will lay carpets of bluebells.

“Over the years,” says Nick Collinson, head of conservation policy at the Woodland Trust, “the new wood will become a huge stepping stone for wildlife to move across the countryside.”

The essence of a corridor, of course, is that it leads somewhere. It needs welcoming habitats along its length and at either end and this is exactly what Sandridge will provide, as both a haven and a conduit.

The benefits are immense. Slow-moving species vulnerable to predators do not like to cross open ground — for them the corridors quite literally are lifelines. And, like human highways, the hedgerows are not just routes of passage but also linear conurbations along which residents as well as migrants pass through every stage of their lives from conception to decomposition.

For the “urban” populations of the woods, they are like shopping malls. Wood mice, for example, may commute for as much as 300 yards to find food or a safe place to breed. It is where bats find insects to survive. Many butterflies depend on them absolutely.

Woods and hedgerows are not panaceas. On their own they will not save wildlife — open-ground habitats are just as important and even more vulnerable to modern agriculture. But there is hope. A reformed common agricultural policy will place less emphasis on maximised yields and agri-environment schemes will encourage farmers to be more sympathetic to wildlife.

Wherever you find it, a tree remains the most visible beacon of hope. As a guarantee of an enduring legacy that will bring pleasure to generations of our species and life to multitudes of others, 15 quid must be the bargain of the century.

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