Environmental Engineering Reference
In-Depth Information
omy.Thus asking an ecologist to justify the value of a species or a collec-
tion of species in an ecosystem is tantamount to asking an economist to jus-
tify why we value securities such as stocks or mutual funds. I believe that
both are integral components of their respective economies and without
them it would be impossible to carry out our day-to-day business of living.
But, there are fundamentally different opportunity costs to managing port-
folios of stocks versus portfolios of
species.
Tinkering within
Economies
In a market economy, intelligent tin-
kering is done by investors who ad-
just their portfolios with the aim to
balance financial return against finan-
cial risk. Such a balancing act can be
accomplished by keeping those stocks
that perform well and letting go
those that perform poorly. But, the
performance of individual stocks changes over time so the portfolio must
be readjusted, including perhaps, buying back stocks that were once per-
forming poorly but are now performing better.Thus, in a market economy,
a security that is excluded from a portfolio can be included again later pro-
vided that the company offering the stock is still in business.That is, there
is opportunity to reverse investment choices. Moreover, one has flexibility
to make rapid adjustments by buying and selling stocks in the very short
term.
Intelligent tinkering with an ecological portfolio requires that we appre-
ciate some important differences between market and natural economies.
First, and foremost, natural economies obey classical laws of thermodynam-
ics, which means that we cannot “grow” them indefinitely. Species popu-
lations, like capital, may accrue for some time through a compound interest
process. But with financial capital, the investment interest rate does not
change because capital accrues. Unlike capital, species population growth
rate eventually does decline because species density causes negative feed-
backs on population growth rate.This then constrains ecosystem function-
ing and production within upper limits. (See chapter 4 for further discussion
of these dynamics.) Working within those limits means that sustaining
Leopold effectively argued that
society needs to change its ethical
perspective about nature from one
that views it as a magnificent col-
lection of species for our passing
enjoyment to one that recognizes
that species play integral roles in
maintaining ecological services
that make up nature's economy.
