Moira Jeffrey finds provocative sculpture in what should be a lonely forest in Aberdeenshire

On a chilly weekday in mid-December you'd expect Tyrebagger Forest, a few miles north of Aberdeen, to be a quiet place. But the car park is full, there's the hum of electricity and light-hearted banter as the employees of Forest Enterprise help locals choose a Christmas tree from the hundreds they have stacked up. By Christmas they expect to have sold 8500.

No wonder a burger van has pulled up to serve the passing trade, offering such tongue-in-cheek Scottish fare as the tartan burger, the big stag, and venison kebabs. At this time of year the forest is as busy as your local fast-food joint.

Tyrebagger is in fact a collision of cultures. There's a golf course nearby, a training centre for the offshore industry, and, in the forest and on adjacent Elrick Hill, a sculpture project, administered by Art in Partnership on behalf of a trust whose members include Forest Enterprise and Aberdeen City Council.

Artists who have worked on the site recently include Donald Urquhart and Simon Beeson. Vong Phaophanit, nominated for the Turner Prize in 1993, is currently putting the final touches to a sculpture that will be installed at the end of the month. A curtain of a dozen larch poles, each around 15m high and peppered with holes, it promises a surprising and mysterious addition to the open heath.

But the most mysterious object on the hillside at present has to be the new work by artists Matthew Dalziel and Louise Scullion. Entitled Modern Nature, it's the perfect addition to a landscape shot through with the contradictions and surprises that characterise our rural areas these days.

The couple behind The Horn - the most distinctive landmark on the dreary M8 - have created a huddle of six aluminium poles, topped with little round dishes. ''The fact that there are these strange poles makes you think of man's interaction with nature,'' Dalziel explains. ''If you look straight across from them, you'll see other poles, the mobile phone masts and that sort of thing. We wanted people to think about the appearance of all these objects in our environment and what they're for.''

But it's only as you approach the piece that you begin to realise there's more to Modern Nature than meets the eye. The guttural sound of bird life seems to be coming from the neighbouring heath: the distinctive call of the capercailzie; the rare woodland grouse that is an icon of wild Scotland and provided the feather in the cap of highland dress.

In fact, though you're convinced you've heard the real thing, it's a recording from the BBC archive, powered by solar panels in the dishes and emanating from buried speakers. There's a real fear that the Scottish population, bred from a Scandinavian reintroduction, is heading for a second extinction; the caper hasn't been seen in this vicinity for around 15 years.

''Roundabout Elrick Hill, even though you think you're up on this wild hill, you can see the airport, there's a big aggregate quarry, and there's a golf course,'' says Dalziel. ''All these things have an impact. Hearing the sound, wondering about the capercailzie, makes you think. Maybe they used to be here and why are they not here now?''

The pair, who have been working together since 1991, are fascinated by this impact of man on nature. Based in the village of St Combes near Fraserburgh, they've explored the flat, wild, yet semi-industrial landscape that surrounds them. Perceptions of the countryside are challenged by defence installations, large-scale production, and places like the gas plant at St Fergus, set among the sand dunes. ''It's like coming across Tokyo,'' says Scullion. Now 34, she was raised in Helensburgh in close proximity to the naval base. Dalziel, 43 was raised in Cumnock. Both have seen how diverse the countryside can be in the industrial age.

They have lived in their adopted home for a decade now and haven't found their location a barrier to an international career. They've just finished a millennium project in Wales, where their pavilion, Rain, designed to capture the sight and sound of rainwater, coincided with the highest rainfall since records began. They were among the recent Bafta new talent nominees with their film about local youth, The Pressure of Spring. Next year they have a December show at Fruitmarket Gallery in Edinburgh.

Most pressing is the completion in 2001 of The Bell, a sculpture at Yesnaby Head in Orkney. To reach it visitors will walk a mile-and-a-half along a cliff. When it is rung the bell will peal out across the Atlantic. ''It's a church bell first cast in 1692,'' says Dalziel ''It was cracked and later the same bell was melted down and recast. It's almost as if it has been reborn. It will have another reincarnation in Orkney.''

This idea of change and rebirth in the landscape is one aspect of a recurring interest, says Louise Scullion. ''The theme throughout our work is looking at the way human beings interact with nature. It's always going to be with us as a contemporary issue, yet it's a kind of timeless idea that people have made work about for centuries. We hope we're contributing to that discussion.''

The marvellous squawking sound of the capercailzie, a natural yet unnatural voice powered by the light of the sun, is making its own contribution. And Tyrebagger, a wild place with a burger bar and a view of Aberdeen airport, seems a perfect setting.