A Matt Ridley column from the Wall Street Journal last month:
In her remarkable new book “The Rambunctious Garden,” Emma Marris explores a paradox that is increasingly vexing the science of ecology, namely that the only way to have a pristine wilderness is to manage it intensively. Left unmanaged, a natural habitat will become dominated by certain species, often invasive aliens introduced by human beings. “A historically faithful ecosystem is necessarily a heavily managed ecosystem,” she writes. “The ecosystems that look the most pristine are perhaps the least likely to be truly wild.”
In the Netherlands, for example, cattle are being used to re-create a simulacrum of a Pleistocene woodland, because their aurochs ancestors would have been vital in keeping forest patchy. To keep African national parks from deforestation, elephant control is sometimes needed. To let aspen, willow and beaver return to Yellowstone, it was necessary to reintroduce the wolf, which reduced elk numbers. To preserve Mojave Desert tortoises, it is essential to control native ravens, whose numbers have been boosted by distant landfill sites.
[. . .]
Ms. Marris’s book goes further, challenging the very idea of a balance of nature. In the first half of the 20th century, ecologists came to believe in equilibrium-that natural systems tended toward a steady state. So, for example, a bare patch of ground would be colonized by a succession of species-annual weeds, then grasses, then shrubs, then trees — until it reached its “climax” state. Conservation, therefore, was a matter of restoring this climax.
Academic ecologists have abandoned such a static way of thinking for something much more dynamic. For a start, they now appreciate that climate has always changed, and with it, ecology. Twenty thousand years ago the spot where I live was under a mile of ice. Then it was tundra, then birch forest, then pine forest, then alder, linden, elm and ash, then most recently oak, but beech was coming.
Which is its climax? We now know that oak seedlings rarely thrive under mature oaks (which rain caterpillars on them), so the oak climax was just a passing phase.
