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9-1 What are the four categories of ecosystem
services?

Ecosystem services include provisions,
regulating services, support systems,
and cultural services

Given that we rely on a relatively small number of species
for our essential needs, why should we care about the mil-
lions of other species that live in various ecosystems? To
understand the value of entire ecosystems, we need to con-
sider both intrinsic values and instrumental values.
Many people believe that ecosystems have intrinsic value —
that is, that ecosystems are valuable independent of any benefit
to humans. These beliefs may grow out of religious or phil-
osophical convictions. People who believe that ecosystems are
inherently valuable may argue that we have a moral obligation
to preserve them. They may equate the obligation of protect-
ing ecosystems with our responsibility toward people or ani-
mals that might need our help to survive. People who argue that
ecosystems are valuable independent of any benefit to humans
generally believe that environmental policy and the protection
of ecosystems should be driven by this intrinsic value.
As mentioned in the module introduction, ecosystems
also have ecosystem services, of which we will consider four
categories: provisions, regulating services, support systems,
and cultural services.

Provisions FIGURE 9.1 Provisions. Scientists discovered that the bark of

Goods produced by ecosystems that humans can use directly the Pacific yew contains a chemical that has anticancer proper-
are called provisions. Examples include lumber, food crops, ties. (Ray Pfortner)
medicinal plants, natural rubber, and furs. Of the top 150 pre-
scription drugs sold in the United States, about 70 percent
come from natural sources. For example, Taxol, a potent of carbon to the atmosphere annually (1gigaton = 1trillion
anticancer drug, was originally discovered by a botanist in kilograms), but only about 4 gigatons of carbon remain in the
the bark of the Pacific yew (Taxus brevifolia), a rare tree that atmosphere. The rest is removed by natural ecosystems, such
grows in forests of the Pacific Northwest (FIGURE 9.1). Once as tropical rainforests and oceans, which provide us with more
approved by the FDA, the synthetic version of this single time to address climate change than we would otherwise
drug has had annual sales of over $1.5 billion and has helped have. As we have already learned in Unit 1, ecosystems also
more than a million cancer patients. There is no way to esti- are important in regulating nutrient and hydrologic cycles.
mate the potential value of natural pharmaceuticals that have An important aspect of regulating services is the ability of
yet to be discovered, but currently more than 800 natural an ecosystem to be resilient, ensuring that it will continue to
chemicals have been identified as having potential uses to exist in its current state in the face of environmental change.
improve human health. Therefore, our best strategy may be A resilient ecosystem also ensures it can continue to pro-
to preserve as much biodiversity as we can to improve our vide benefits to humans. You may recall that in the previous
chances of finding the next critical drug.
module we discussed the importance of maintaining high
species diversity for maintaining ecosystem resilience. For
Regulating Services example, several different species may perform similar func-

Natural ecosystems help to regulate environmental condi- tions in an ecosystem but differ in their susceptibility to dis-
tions. For example, humans currently add about 8 gigatons turbance. If a pollutant kills one plant species that contains
nitrogen-fixing bacteria but does not kill other plant species
that contain nitrogen-fixing bacteria, the ecosystem can still
Provision A good produced by an ecosystem that humans can continue to fix nitrogen, so there is built-in resilience when
use directly.
we maintain the natural level of biodiversity (FIGURE 9.2).

106 UNIT 2 ■ The Living World: Biodiversity
Uncorrected proofs have been used in this sample.
Copyright © Bedford, Freeman & Worth Publishers.
Distributed by Bedford, Freeman & Worth Publishers. Not for redistribution.

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