Britain is not alone in having an "unnatural" landscape. It exists in just about every place on Earth where human beings have lived. Budiansky believes this is not just an aspect of the recent explosion in the global human population, swelling from one billion in 1800 to over five billion today, but stems from a much older interaction between nature and its most inquisitive species, Homo sapiens.
In fact he believes this goes back as far as the end of the last Ice Age, 12,000 years ago. Nature has never really been left to its own devices, he argues, but has been "managed" on a mass scale by generations of people down the millennia. His message is that if we fail to recognise this, there will be little chance of solving some of the dire environmental problems we now face.
Budiansky argues that the whole idea of "balance of nature", which pervades environmental thinking today, is a myth. It stems from the Romanticism that began two centuries ago, when poets and artists such as Wordsworth and Constable began revering nature as an antidote to the rise of industrial squalor. In his book Nature's Keepers, Stephen Budiansky writes: "A belief in nature's inherent perfection has for more than a century been almost inseparable from a love and appreciation of nature; the love and the belief rose hand in hand in a flush of romantic revulsion against the Industrial Revolution."
Far from being in balance, nature is in constant turmoil, either from great natural disasters, or from less dramatic disruptions such as climate changes and human activity. As Budiansky says: "The 'normal' state of nature is not one of balance and repose; the 'normal' state is to be recovering from the last disaster."
The concept of nature has attained such strong spiritual, aesthetic, ideological and even nationalistic connotations that it has become divorced from any sensible scientific meaning. "Today," says Budiansky, "many nature lovers innocently believe that the 'balance of nature' - the notion that every species is interconnected in a delicate 'web of life' that will collapse if a single strand is cut - or the idea that 'nature knows best' how to manage itself, are scientific statements of fact derived from modern ecological research. Ecologists have tried for over half a century to disabuse the public of these ideas, and they seem to have almost given up." Wise nature makes good poetry, he says, but bad science.
The "natural" landscapes of Europe and the Mediterranean are the most obvious examples of what Budiansky means by the artificial nature of nature. It was here that the arrival of the axe and the plough in Neolithic times caused such devastating and long-term changes to the countryside. "Lest anyone repeat the mistake of underestimating the destructive prowess of the noble savage, by underestimating the industry of the Stone Age farmers of Europe, experiments in Denmark have shown just what a few determined axemen can do. Using nothing but stone axes, three men were able to clear a 5,000sq ft birch forest in four hours. One hundred trees were felled, using an original Neolithic stone axe head which had not been sharpened for 4,000 years."
From the decidedly artificial banks of the lower Nile to the unnatural British chalk downs, which were completely cleared of their forests with the arrival of the Roman iron plough, there is now little left in Europe and the Mediterranean of what could be truly described as natural wilderness. Even the vast, treeless tracts of the Scottish heather moors - a prime contender for British wilderness if ever there was one - are mostly the result of human activity. "Burning and grazing have kept the heaths from reverting to forests for thousands of years," Budiansky says.
He points to the "ancient" forests of North America to further illustrate what he means by unnatural nature. In the US, it is common to assume there was a vast primeval forest stretching across much of the continent, until the arrival of European settlers from the 16th century onwards. The reality, according to Budiansky, is very different. In fact, many of the earliest explorers remarked at how open the forests were. "If there is one point on which the early European settlers who set down their observations of the New World agree, it is that the forests of eastern North America reminded them of nothing so much as the carefully tended parks of the great estates of their homelands."
Why should this be the case? Budiansky argues that these lands were managed by native American Indians who routinely burnt huge areas of forest, constantly creating new ecological niches in which grassland species could flourish. Thomas Morton, an English explorer and fur trader, was one of the first to write about the practice in 1632: "The Savages are accustomed to set fire of the country in all places where they come; and to burn it, twize a yeare, vixe, at the Spring, and at the fall of the leafe. The reason that moves them to do so, is because it would be all a copice wood, and the people could not be able in any wise to passe through the country out of a beaten path."
Budiansky believes there is also scientific evidence of native Americans managing the land on a grand scale by setting fire to it regularly. Ecologists have long known about the importance of forest fires in regenerating the flora of a forest ecosystem, but have assumed these fires to be caused by lightning strikes.
"When tree rings of old-growth stands in western Montana were analysed," Stephen Budiansky says, "it became clear that fires were much more frequent in areas that had been heavily used by Indians than they were in similar but more remote areas. The areas frequented by the local Salish and Kootenai Indians had burned on average every nine years, compared to 18 years for the more remote sites."
With the arrival of the first Europeans, who displaced the native Americans and actively suppressed fires, the forests made a comeback. "One of the great ironies in the myth of the forest primeval is that the dense, thick woods that later settlers did indeed encounter and arduously clear were not remnants of the forest primeval at all. They were the recent, tangled second growth that sprung up on the once-cleared Indian lands only after the Indians had been killed or evicted and the Europeans began to suppress fire. What later settlers took to be the forest primeval was nothing more than an abandoned ranch."
Suppressing fires has, Budiansky says, contributed to the demise of some animal species. The heath hen, originally found on the plains of Massachusetts, had vanished from mainland Massachusetts and Connecticut by the mid- 19th century because of the reforestation of the American north-east. Even the beleaguered Californian condor has suffered from a lack of the open spaces caused by regular burning of the chaparral.
The condor, Budiansky says, has the habit of gorging itself to the point where it needs a long, clear runway in order to get airborne after feeding. Without such open spaces, it has to digest its food overnight near the site of its quarry instead, leaving its nestlings to go hungry for dangerously long periods - and so hastening the demise of the species.
Budiansky, who has a farm in Virginia and enjoys fox hunting with hounds, eschews the belief that nature knows best; he believes humans have to take an active role in the management of ''wilderness''. This, he says, may result in unpopular decisions. The culling of elk in Yellowstone National Park is an example (the practice was abandoned after public protest, but other wildlife suffered as a result of the rise in the elk population).
Such views will be hard for most environmentalists to stomach. Where Budiansky is likely to meet most vocal opposition, however, is in the position he takes on species extinction. Many prominent experts have argued that human activity is helping to make extinct a huge number of species over a very short timescale. Edward O Wilson, the eminent Harvard biologist, has calculated that human activity is resulting in the loss of three species an hour in the tropical rainforests. ''Humanity has pushed the pace of extinction worldwide to thousands of times faster than the natural rate,'' he said earlier this year.
Budiansky believes the calculations used by Professor Wilson and others are flawed. He claims the only serious study into species extinction has found evidence for just a single species being lost each year. ''There are clearly species that are endangered as a result of human development,'' he says, but exaggerating the situation with ''wildly inaccurate'' estimates will not help.
These "overestimates" of species extinction, Budiansky believes, are an integral part of the romanticising of nature in which humans have no role to play. "We have, in enshrining nature, alienated ourselves from her," he says. "Our relationship is that of the voyeur, at best. Environmentalism has bequeathed us with a paralysing sense of species guilt. This has left us believing that the only proper way to approach nature is not at all."
! 'Nature's Keepers' by Stephen Budiansky is published by Weidenfeld and Nicolson at pounds 18.99.Reuse content