Travel: The Grumpy Green: Return of the natives: Once upon a time Scotland was covered in woodland. It's about to be again. Kevin Rushby takes a walk through what will soon be a coast-to-coast forest: Helping to plant trees is a great way to see a beautiful part of the country

Standing near the head of Glen Affric as darkness falls, I listen to the creak of an old pine tree bending in the wind. There are few trees here, and those that do survive are twisted and stunted by the severity of weather conditions: it's only mid-October, but there is already plenty of snow on the ridges to add to the savage beauty of the valley.

The map labels much of this area as forest, but that is simply medieval nomenclature, a time when the word indicated a deer-hunting ground rather than trees. It is certainly not what we would call a forest now: most of the ground here is tussocks of heather and sphagnum mosses. My guide Gordon Birnie, however, points to some pale green feathery sprigs dotted among the heathers. "Scots Pines. These have self-seeded."

That makes it sound a random benefit, but it is not. The regeneration is part of a carefully orchestrated plan to join up existing patches of ancient forest. The net result for walkers is something very exciting indeed. Gordon waves his arm westwards. "Over there is a treeless stretch of two or three miles, and that is the last gap. When seedlings start growing there, there'll be forest right across Scotland."

We move on a few hundred metres more while the last of the light fades. The significance of this place is enormous: in some of the most spectacular landscapes that we have, ancient woodland will be augmented by new growth to create a forest spanning the country. Footpaths already thread through the woodland, linking the Moray Firth in the east to Kintail in the west. Accommodation exists, too, though in the wilder reaches of Glen Affric the choice is limited to the unstaffed youth hostel at Allt Beithe or a wild campsite of your own choosing (wild camping is legal in Scotland, see mcofs.org.uk/home.asp for details).

The time when Britain was last spanned by woods is a point of debate in academic circles. The Caledonian forest grew up after the last ice age ended, 10,000 years ago, and has been in decline for at least the last 2,000 years,...