Environmental Engineering Reference
In-Depth Information
posed to happen like that. Conventional ecology says their complex interactions emerge only as a result
of long-term evolution of species. As Stroud put it, in a paper with David Catling of the University of
Washington, the species on Green Mountain “have bucked the standard theory that complexity emerges
only through coevolution.”
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Stroud had been tending the mountain for a decade, ever since he came here from St. Helena to be
the island's conservation officer. He admitted that, as a conservationist, he should probably be rooting
out all those foreign trees in order to allow the natives to regain their terrain. But if he did, there would
be almost nothing left. And in any case, he said, he was presiding over something profoundly interesting.
This confected cloud forest was prime evidence in a growing movement among ecologists to reconsider
many of their nostrums about how ecosystems function. It suggested that species with no previous con-
tact can get along with each other much more intimately than assumed. It suggested that perhaps many
more forests and other complex ecosystems around the world are the result of chance meetings rather
than complex coevolution. If that is true, it may hold vital clues for regenerating nature in the twenty-
first century.
Ascension Island, which is almost twice the size of Manhattan, erupted from the Atlantic floor a
million years ago. It was not barren for long. Remote as it was, some life soon arrived. Millions of
seabirds occupied the lowlands, their spattered excretions turning the piles of black clinker white. Green
turtles swam thousands of miles to nest on its sandy beaches. And the island's mysterious land crabs
arrived from who knows where—and who knows how—to make a life scuttling on the slopes of the vol-
cano. But—apart from a few ferns and mosses on the mountain, and an endemic shrub called Ascension
spurge along the shore—the black desert for a long time remained almost entirely devoid of vegetation.
The first known human visitors to Ascension Island were early Portuguese mariners who dropped
anchor on Ascension Day 1503, on their way to the Indian Ocean. Hence the island's name. But the
first permanent occupation was by the British Royal Navy. It set up a garrison in 1815 to patrol the sur-
rounding oceans and prevent the rescue of the most famous international prisoner of the day. Britain had
captured and incarcerated the former French emperor Napoleon Bonaparte on St. Helena, its equivalent
of Guantánamo Bay, nine hundred miles to the south. After Napoleon's death, the British used the island
as a base for hunting down transatlantic slave ships and to store fuel for warships heading to India, the
“jewel” in the British imperial crown.
Ascension Island has kept coming in handy. At the end of the nineteenth century, it became a hub
for transatlantic telecommunications, with cables stretching to Europe, South Africa, Brazil, and Argen-
tina. These days, the island is peppered with antennae that allow tracking of orbiting spacecraft, com-
munication with crews of nuclear submarines, and eavesdropping on cable and satellite-relayed commu-
nications. The electronic spies of Britain's Government Communications Headquarters, usually called
GCHQ, are the biggest employers. The island's band of temporary residents, who number about eight
hundred, say it has more antennae than people. It also has one of the longest airstrips in the world, built
by the US Air Force during World War II to provide a secure stopping-off point for flights into Africa.
When I arrived in early July 2013, I was amazed to see nine large US military aircraft on the tarmac, all
busy protecting President Obama during a visit to that continent.
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Inevitably, such human traffic has brought alien species, both accidental and deliberate. Recent ar-
rivals on the lowlands include fast-spreading tobacco plants and Mexican thorn, or mesquite, which the
BBC shipped here in the 1960s to brighten up gardens in a new settlement for operators of a transmission
station serving Africa. But much more was deliberately introduced. From the first, the naval garrison
brought in species to make the remote outpost as self-sufficient as possible. Documents in Ascension's
archive, in the toy-town capital of Georgetown, show how it first established a farm on one of the few
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