PRBO Conservation Science
Quarterly Journal of PRBO Conservation Science, Number 150, Fall 2007: Units of Conservation: Single Species to Ecosystems


Ecosystem Services

Ellie M. Cohen

Units of Conservation
Glossary of Terms
CEO's column
Snowy Plovers and Sandy Coastline
Sierran Forest Focal Birds
Marine Ecosystem Research
Ecosystem-based Management
PRBO News and Highlights
Remembering Bob Mayer
Focus on Black Rail Habitat
Latin American Intern Story
Bird-A-Thon 2007
The Grand List

Taylor Ricketts, Conservation Science Director for the World Wildlife Fund, recently visited PRBO and shared his vision for the dynamic field of ‘ecosystem services'—the benefits that humans receive from nature including clean air, clean water, food, flood management, carbon absorption and climate regulation, as well as bird watching and ecotourism!

Taylor last visited PRBO in the 1990s, when his wife was an intern at Palomarin, the Farallones, and other field sites! This fall, he visited after attending a meeting of the innovative Natural Capital Project that he cofounded. As explained on their website: "Traditional ways of calculating Gross Domestic Products consistently omit the trillions of dollars of benefits that nature provides, and on which our lives depend."
Ecosystem services such as those provided by healthy riverbank systems are valuable. PRBO photo

What if we could assign dollar amounts to all that nature provides us and incorporate those values into policy making? Decisions in California about water management, for example, would change dramatically.

California's 36 million human residents, its $40 billion per year agricultural industry (that supplies more than half of the nation's produce), and tens of millions of birds and other wildlife all rely on a gradual spring and summer Sierra snow melt. Billions of dollars have been invested in dams to store water and convey it in channels lined by vegetation-free levees from the mountains across the state. Yet climate change models predict that the Sierra snow pack will be virtually gone by 2075 and that we will experience more intense rainfall (but not necessarily more rain), deadly floods, and extreme water shortages, even with this extensive infrastructure.

Imagine the different choices that might be made to address this pending catastrophe if the true economic value of the services healthy riparian (i.e., vegetated river bank) ecosystems provide—e.g., clean water, reduced flood damage, replenished groundwater, fish nurseries, and diverse, abundant wildlife—were incorporated into water management decision making!

Why Consider Costs and Gains

In their 1982 book Extinction, Paul and Anne Ehrlich compare ecosystems to airplanes and species to rivets. They suggest that we might lose a few rivets here and there but the plane could keep flying; what we don't know is when the one tiny rivet would fail that would cause the entire plane to come crashing down.

"What if we could assign dollar amounts to all that nature provides us and incorporate those values into policy making?" —Ellie M. Cohen, PRBO

Twenty-five years later, we are observing quite a few species under severe stress; several recent studies predict that more than 25% of all species will be lost in the decades ahead. Different parts of ecosystems respond in different ways to ‘global change'—i.e., to habitat loss, natural resource extraction, invasive species, and ever accelerating global warming. Some species will become extinct; others will persist only by interacting in novel ways with the rest of the ecosystem.

Our concern is that the loss of species will lead to instability of what remains and that ecosystems will become less resilient—less able to withstand inevitable future change.

Global change of this magnitude requires solutions of similar scale. Taylor and his colleagues are proposing just that, by linking nature conservation with the global marketplace. PRBO has much to contribute to this natural economics approach through our innovative research and outreach, whether focused on single species, multiple species or entire ecosystems, as highlighted in this Observer.

The fate of birds, other wildlife, and humanity may well depend on how quickly we humans can slow down our impacts on nature while simultaneously accelerating biodiversity and ecosystem preservation. Adding ecosystem services to the conservation toolbox, and thus motivating changes in behavior and policy, may be just what is needed to help ensure the sustainable use of Earth's bounty.

Many thanks to Nadav Nur, Tom Gardali, and Claire Peaslee for contributions to this perspective. For more information see

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