218 CHAPTER 10 Sustaining Terrestrial Biodiversity: The Ecosystem Approach
Cleared plots Highway
for grazingCleared plots
for agricultureOld growthNew highwayFigure 10-5 Natural capital degradation: Building roads into previously inaccessible forests paves the way to
fragmentation, destruction, and degradation.SCIENCE FOCUS
Putting a Price Tag on Nature’s Ecological Services
regulations and taxes that discourage bio-
diversity degradation and through subsidies
that protect biodiversity—the world’s forests
and other ecosystems will continue to be
degraded. For example, the governments of
countries such as Brazil and Indonesia provide
subsidies that encourage the clearing or burn-
ing of tropical forests to plant vast soybean
and oil palm plantations. This sends the pow-
erful message that it makes more economic
sense to destroy or degrade these centers of
biodiversity than it does to leave them intact.Critical Thinking
Some analysts believe that we should not
try to put economic values on the world’s ir-
replaceable ecological services because their
value is infinite. Do you agree with this view?
Explain. What is the alternative?he long-term health of an economy
cannot be separated from the health
of the natural systems that support it. Cur-
rently, forests and other ecosystems are
valued mostly for their economic services
(Figure 10-4, right). But suppose we took into
account the monetary value of the ecological
services provided by forests (Figure 10-4, left).
In 1997, a team of ecologists, economists,
and geographers—led by ecological econo-
mist Robert Costanza of the University of
Vermont—estimated the monetary worth of
the earth’s ecological services and the bio-
logical income they provide. They estimated
the latter to be at least $33.2 trillion per
year—close to the economic value of all of
the goods and services produced annually
throughout the world. The amount of money
required to provide such interest income,
and thus the estimated value of the world’s
natural capital, would have to be at least
$500 trillion—an average of about $73,500
for each person on earth!
According to this study, the world’s forests
provide us with ecological services worth at
least $4.7 trillion per year—hundreds of times
more than their economic value. And these
are very conservative estimates.
Costanza’s team examined many studies
and a variety of methods used to estimate
the values of ecosystems. For example, some
researchers estimated people’s willingness
to pay for ecosystem services that are not
marketed, such as natural flood control and
carbon storage. These estimates were added
to the known values of marketed goods
like timber to arrive at a total value for an
ecosystem.
The researchers estimated total global
areas of 16 major categories of ecosystems,
including forests, grasslands, and other ter-T
restrial and aquatic systems. They multiplied
those areas by the values per hectare of vari-
ous ecosystem services to get the estimated
economic values of these forms of natural
capital. Some of the results for forests are
shown in Figure 10-A. Note that the collec-
tive value of these ecosystem services is much
greater than the value of timber and other
raw materials extracted from forests (Con-
cept 10-1A).
These researchers hope their estimates
will alert people to three important facts: the
earth’s ecosystem services are essential for all
humans and their economies; their economic
value is huge; and they are an ongoing source
of ecological income as long as they are used
sustainably.
However, unless such estimates are in-
cluded in the market prices of goods and
services—through market tools such asEcological serviceWorth (billions of dollars)Nutrient
cyclingClimate
regulationErosion
controlWaste
treatmentRecreation Raw
materials500100150200250300350400Figure 10-A Estimated annual global economic values of some
ecological services provided by forests compared to the raw materials
they produce (in billions of dollars).