Environmental Engineering Reference
In-Depth Information
roadrunner abundances by foxes would now create opportunity for the
other bird species to become established. Let's suppose that this led to the
rich diversity of birds in a more modern chaparral ecosystem. Let's suppose
now that foxes began to build their own populations by diminishing the
abundance of roadrunners. Hungry foxes then might switch to preying on
the other bird species. But, suppose also that because foxes became suffi-
ciently abundant so that coyotes could become established by preying on
foxes.This would release predation pressure on the bird species. So coyotes
now indirectly maintain bird species diversity in the ecosystem.The direct
and indirect lines of dependence leading to the maintenance of species di-
versity and function in this ecosystem became established through a specific
order of priority from roadrunner to fox to other bird species to coyote.
Any restoration sequence that deviates from the original assembly process,
including reintroducing species en masse, could very well lead to failure—
a Humpty Dumpty effect.
Some might dismiss all this by saying that in the grand scheme of things
it is just a few insignificant little birds and mammal varmints that are found
in other places anyway—the triage ethic. But, what if the loss of these pu-
tatively insignificant species and varmints lead to ecosystem conditions that
fuel more frequent and intensive chaparral wildfires that annually damage
expensive real estate? Right now we do not have the scientific knowledge
to speak to this issue nor to many other issues concerning the role of hu-
mans in natural economies. Resolving this is one of the major challenges in
the next generation of ecological science (Lubchenco et al. 1991; Ludwig
et al. 2001). On the other hand, the prospect of Humpty Dumpty effects
could be eliminated altogether by ensuring that we cause minimal risk to
species when developing or exploiting ecosystems. In this respect, it is wise
to revisit the insight of Aldo Leopold that was presented above:“If the biota,
in the course of aeons, has built something we . . . do not understand, then
who but a fool would discard seemingly useless parts? To keep every cog
and wheel is the first
precaution
[my emphasis] of intelligent tinkering.”
Ecological Science, Uncertainty, and Precaution
Sustaining natural economies, like market economies, involves making de-
cisions in the face of uncertain knowledge. Ecological science tries to dimin-
ish this uncertainty through a systematic process of induction, deduction, and
experimentation (chapter 2); but ecological science cannot eliminate uncer-
