Outdoors: A date with a hedge

A bit of hawthorn, a dash of ash: what does it mean?

It looked like any ordinary hedge, but Peigi Wallace knew it was something special. She stared at it for some time before sticking her head between two bushes for a closer examination.

"Aha, it's a double hedge, very interesting," came her muffled voice from the undergrowth.

Reluctantly I joined her, thrusting my head past the thorns and brambles. The winter had eaten away a lot of foliage and left two distinct, parallel lines of tangled, brown sticks about 4ft apart, leading north.

"This gives us a vital clue," Dr Wallace said, with a sparkle in her eye. I was still none the wiser.

We were hedge-dating, playing rural detectives to trace the history of this south-western corner of Oxfordshire. This spring you are likely to see a lot more people with their heads stuck in hedges looking for clues.

Since the Council for the Protection of Rural England (CPRE) launched a campaign last year to save hedgerows, in response to widespread destruction, hundreds of volunteers have been out, scrambling along field boundaries investigating hedges in order to build up a historical map of the English countryside. Over the winter, trees and bushes are harder to identify because of the lack of leaves and flowers, but with spring upon us local CPRE groups are expecting lots more volunteers.

Hedgerows have become a highly contentious issue in recent years. According to the CPRE, they are being deliberately removed to the order of 3,600km (more than 2,200 miles) every year, and even more are being damaged by neglect. About a third of the hedges in England and Wales are estimated to have been removed in the decade between 1984 and 1994.

Hedgerows are important for a number of reasons. Aesthetically, they are picturesque and historic characteristics of the English countryside which add to our enjoyment of views. Practically, they mark the boundaries between parishes and estates. And ecologically, they are havens for wildlife. Hedgerows provide wildlife corridors along which small mammals can forage, protected from aerial predators by thick brambles and branches. Small birds use the same protection of the hedgerows to build their nests. Take away the hedge, and the diversity of species is bound to suffer.

Under the Hedgerow Regulations brought in last summer, anyone who wants to remove a hedge must get permission from the local planning authority, and hedgerows deemed "important" will be protected. Anyone flouting the law could be fined pounds 5,000. The CPRE was critical of the laws, fearing they would save fewer than one in five hedgerows, but was relieved at the Government's proposed increase in protection.

Their cause is helped considerably by the information collected by hedge- daters, which is passed to local authorities to ensure that as many hedgerows as possible are saved. Thanks to Dr Wallace, hedgerow co-ordinator of the CPRE's Oxfordshire branch, the county is ahead of the game, with roughly a quarter of its hedges already surveyed.

"I think the tide has turned here. We are certainly not losing any more hedgerows here in Oxfordshire, but we are only getting a very few new ones built," she said. "That's why we have to keep dating. If we lost our hedgerows, it would not be the English countryside any more."

She had picked for me a hedge near the small town of Grove in the Vale of the White Horse, unknown even to her, so I would have to start from scratch. "Have you ever dated a hedge before?" Dr Wallace asked. I had heard of Hooper's rule. Max Hooper, who worked with the Nature Conservancy in the Sixties, discovered that you could estimate a hedge's age by counting the number of species in a 30-metre stretch: one species, he reckoned, equals 100 years. "That's not enough. That's just a starting-point. There are days of research after you have done that," said Dr Wallace.

My hedge contained hawthorn, elder, sycamore, ash and hazel, and it had clearly been planted as a double hedge. Hooper might have left it at that, estimating it to be a hedge from the 15th century, and moved on to the next one, but I had been bitten by the hedge-dating bug and wanted to know more. I was tempted to drop in at the National Monuments Record in Swindon, to view their unique collection of aerial reconnaissance photographs taken by the RAF and the US Air Force during the war. They show every field, road, barn and, crucially, every hedge. If I'd had the time and money I could also have taken a trip to Maryland in the US, to view sets of photographs taken by the German Luftwaffe which were claimed by American troops at the fall of Berlin.

But these records would take me back only 50 years. I needed to go back much farther into the past, so instead I paid a visit to the Royal Geographical Society's map room in west London and got my hands on an original 1875 chart of the area.

There, along the route Dr Wallace and I had walked, was marked a Green Lane, an abandoned track just wide enough for a horse and cart. It even had a name, Windsor Lane. I had at least partly solved our mystery.

Of course, the dedicated hedge dater could add to this, consulting tithe and enclosure maps and early Ordnance Surveys to find out where the lane led, when it was planted and who might have used it. The lane's straightness could suggest Roman influence, and it is close enough to the Marlborough Downs to have been, possibly, a more recent branch of the Ridgeway.

One thing was for sure. Peigi and I had discovered that it was important enough to have been named and given status on a map. That, the CPRE would argue, is ample evidence that this hedge is also important enough to save today.