Environmental Engineering Reference
In-Depth Information
en to extinction by the Dutch sailors. But at least now there are alien substitutes to do the housekeeping.
Wildlife managers have introduced giant tortoises (
Geochelone gigantean
) from Aldabra twelve hun-
dred miles away to spread the seeds of native trees. The newcomers have, says science author Sharon
Levy, “rescued at least one endangered plant—
Diospyros egrettarum
, a species of ebony endemic to
Mauritius.”
22
Other islands show similar commendable novelty. Take the Seychelles, another vacation idyll in the
Indian Ocean. The islands were largely deforested by French and British colonists who replaced the
trees with plantations of spices like cloves, nutmeg, and cinnamon (
Cinnamomium verum
) from India.
But the farmers stopped bothering with their fields when an international airport opened and tourism
took off in the 1970s. As on Puerto Rico, the forests grew back. More than 90 percent of the island's 325
known native plant species were still around, and they began to move back onto their old terrain. But
what is emerging across the islands is a forest novel ecosystem, in which ancient endemics grow side by
side with the spice trees. Cinnamon trees proved the best colonists and are now the most abundant on
the lowlands.
Some conservationists want to get rid of the cinnamon and other alien trees, to give the natives a
chance to flourish once more. But James Mougal of the Seychelles National Park Authority says cin-
namon and the others represent nature's best shot at a resilient new ecosystem. They provide excel-
lent forest cover and leaf litter for native amphibians, snakes, insects, snails, and plants. The endemic
Seychelles fruit bat roosts primarily in alien trees, whose fruit and seeds are a major food source. In
any case, eradication would likely fail. Mougal's compromise is to reestablish more patches of natives
among the cinnamon trees to ensure that they have the best chance of taking their place in the novel
ecosystem. That seems smart.
23
The recognition that novel ecosystems are the future—the new wild—is often painful for conservation-
ists. Nowhere is that more true than on the volcanic archipelago of the Galapagos Islands, a thousand
miles west of Ecuador. The islands are famous for conservation. They are the home of giant iguanas, sea
lions, and numerous endemic bird species such as the Galapagos hawk, dove, flycatcher, rail, and martin,
as well as the thirteen species of finches that Darwin investigated for their adaptation to local environ-
ments, and the only tropical penguin. And until his death in 2012, there was also Lonesome George, the
last surviving individual from the Pinta Island subspecies of giant tortoise. The islands are also import-
ant for science. It was after visiting here that Charles Darwin developed many of his ideas on evolution.
Probably more time and money has been spent on conserving the biodiversity of these remote islands
than anywhere of comparable size on the planet. So it came as a shock when in 2011 Mark Gardener,
after two decades working to preserve the islands' unique species, seemed to haul up the white flag.
The head of restoration at the Charles Darwin Research Station, which is in charge of most conservation
activity on the archipelago, told
Science
magazine: “It's time to embrace the aliens. As scientists and
conservationists, we need to recognize that we've failed. Galapagos will never be pristine.”
24
The Galapagos Islands are volcanic lava flows that surfaced in the past five million years. The cli-
mate is cool and dry, since for most of the year the islands are bathed in the cool Humboldt Current
coming up from Antarctica. There are frigatebirds, boobies, petrels, mockingbirds, flightless cormor-
ants, and other endemic birds. There are a wide variety of iguanas and the finches—with different beaks
to eat different foods on different islands—that so fascinated Darwin.
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