Environmental Engineering Reference
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premises of natural order. He says there is no such thing as a balance of nature. After many years of
monitoring local ecosystems like Isle Royale in Lake Superior, he concluded in his topic
Discordant
Harmonies
, and later in
The Moon in the Nautilus Shell
, that nature is constantly out of balance, con-
stantly changing.
4
This argument is central to our story about alien species. If nature is, and should be, in balance, then
there is no place for alien species. The carpetbaggers from different ecosystems should be sent home.
But if there is no balance, no natural order—and no original sin in disturbing nature—then aliens may
have a place in the scheme of things. They are not, of themselves, bad things. They may be good. They
may deliver. They may, to borrow Darwin's ideas of natural selection, be worthy victors in the survival
of the fittest. Much of the rest of this topic will explore this idea, what it means for alien species, and
what it should mean for the conduct of conservation. Botkin called it the new ecology; I call it the new
wild.
How did the notion of balance in nature take such a hold among ecologists—and why does it continue to
spellbind most in the conservation community? Marsh didn't talk about ecology or ecosystems. But his
ideas about nature's propensity for “unchanging permanence” encouraged his successors to look for the
ecological processes that delivered this state of balance. The most influential was the Nebraska botanist
Frederic Clements. After years exploring nature in his prairie home state in the late nineteenth century,
the tall, upright, and devoutly religious Clements concluded that balance arose from plant species form-
ing tight “associations” that we would today call ecosystems. For every type of climate in the world, he
said, there was a matching permanent association of vegetation. He called it a “climax.” If something
intervened to disturb the balance of that association—whether hurricane or ice age or clear-cutting for-
esters—the association would attempt, through a process he called “succession,” to re-create its former
steady state.
5
On the face of it, Clements's picture of nature as a finely tuned machine fits Charles Darwin's in-
sights on natural selection. Darwin had proposed in
On the Origin of Species
that many species evolved
in harmony to maximize their survival chances. He called it “coevolution.” Insects specialized to live
off and pollinate plants, while the plants evolved to help them, to ensure their reproduction. Most fam-
ously, having been sent an orchid from Madagascar,
Angraecum sesquipedale
, with nectar hidden down
a foot-long narrow tube, Darwin predicted that there must somewhere be an insect with a proboscis long
enough to reach the nectar. Half a century later, just such an insect,
Xanthropan morganii praedicta
, was
found. Much later, it was shown to feed on the orchid.
6
From the idea of coevolution, it was but one step to suggest that evolution would act as some kind
of optimizing force, creating entire ecosystems in which every species had its tightly defined role. Cle-
ments and the early ecologists argued just that. They saw natural selection as creating an evolutionary
path to perfected nature. Darwin himself had never suggested any such thing. For him, “survival of the
fittest” was just that. Species evolved and adapted to meet their own needs and gain ascendancy over
rivals. But the idea had been proposed by one of Darwin's predecessors in evolutionary theory. The late-
eighteenth-century French naturalist Jean-Baptiste Lamarck saw the changes induced by evolution as
“the accomplishment of an immanent [inherent] purpose to perfect the creation.” Clements was a great
fan of Lamarck.
7
Through the early twentieth century, Clements's idea of associations of plants was refined into the
concept of ecosystems—communities of organisms in which, in ways that have proved hard to define,
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