Books and Arts; Book Review;The constant gardener;The future of wilderness

The journey begins in Hawaii, where biologists are toiling to remove species that have been introduced to the islands over the centuries since James Cook's party landed there in 1778. Invaders such as purple-flowered Asian melastome and strawberry guava threaten to overrun delicate Hawaiian natives such as thornless roses and delicate tree ferns. Yet even if all the invaders were removed, it would only return the islands to the state into which the Polynesians, who inhabited them for at least 1,000 years before Cook's arrival, had shaped them.

Even theoretically, returning Hawaii to a prehuman existence would be impossible. Ecosystems change over time, with or without the involvement of mankind, so no one can tell what Hawaii “should” look like. And mankind's influence on his environment is now such that he has changed the composition of the atmosphere over the past few centuries, so the effects of humanity can never be completely removed.

Ms Marris traces the emergence of a “wilderness cult” that she believes affects efforts to restore habitats to a previous form. She argues that early American environmentalists, such as Ralph Waldo Emerson and Henry David Thoreau, have been misread as its champions. Although Emerson described “essences unchanged by man; space, the air, the river, the leaf”, he also wrote of the “perfect exhilaration” of “crossing a bare common, in snow puddles at twilight, under a clouded sky”. And when Thoreau became determined to get away from it all in 1845, he retired to Walden Pond, a mere mile-and-a-half away from the nearest village. Preserving nature, Ms Marris writes, is a relatively recent preoccupation.

Perhaps, but it has a longer history than the author fully acknowledges. A struggle between those who would remove man from a landscape and those who think we should actively manage the environment has existed since at least the 1930s. When the first global environmental organisation was established in 1948, it was called the International Union for the Protection of Nature: the organisation renamed itself in 1956, replacing “protection” with “conservation” in its title, because its members had grasped that people play an important role in shaping the natural world.

Ms Marris's book is an insightful analysis of the thinking that informs nature conservation. The author outlines the concepts of “re-wilding” habitats by introducing species that have been lost, of the “assisted migration” carried out by foresters who prepare for climate change by planting trees at the current limits of their ranges (and, indeed, the gardeners who transplant cuttings and seedlings from one part of the planet to another). She describes how ecosystems can be designed: nesting birds can be encouraged to breed on a site by manipulating it to suit them, for example. And nature can flourish in areas that are not wild, such as city roof-gardens.

There are many reasons to value the natural world. Some people want to prevent certain species from becoming extinct, others to ensure the diversity of an ecosystem, to make use of clean air and water or to revel in the beauty of a landscape. Happily for both mankind and the natural world, Ms Marris concludes, many such causes can be aligned.