Policy Forum
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POLICY FORUM ECOLOGY ing technology would have undesirable out- comes? What habitats must be protected to Ecology for a Crowded Planet ensure that key services are provided? Which agents impoverish ecological services and Margaret Palmer,1* Emily Bernhardt,2 Elizabeth Chornesky,3 Scott Collins,4 how can their impacts be mitigated or re- Andrew Dobson,5 Clifford Duke,6 Barry Gold,7 Robert Jacobson,8 Sharon Kingsland,9 versed? How do individual, corporate, and Rhonda Kranz,6 Michael Mappin,10 M. Luisa Martinez,11 Fiorenza Micheli,12 government decisions sustain or degrade eco- Jennifer Morse,1 Michael Pace,13 Mercedes Pascual,14 Stephen Palumbi,12 system services? What options can ecologists O. J. Reichman,15 Ashley Simons,16 Alan Townsend,17 Monica Turner18 provide when conservation is not possible? For some services, substantial knowl- edge already exists, yet it is neither widely ithin the next 50 to 100 years, sup- ecosystem services and the science of eco- known nor consistently applied. For exam- port and maintenance of an extend- logical restoration and design. ple, as vegetation is replaced with concrete Wed human family of 8 to 11 billion and rooftops, rainfall that once permeated people will become difficult at best. Our con- The Science of Ecosystem Services soils now moves through storm drains or as sumption rates already exceed the supply of Natural ecosystems provide great benefits to runoff directly into streams and coastal ar- many resources crucial to human health, and human societies. Clean drinking water, soil eas, causing flooding and water pollution. few places on Earth do not bear the stamp of stabilization by plants, buffering of vector- Nevertheless, development typically pro- human impacts (1, 2). Fossil fuel combustion transmitted disease outbreaks, and pollina- ceeds without greenways, protected ripari- and fertilizer production have doubled the tion are ecosystem services that in most cas- an zones, or storm drainage infrastructure global rate of nitrogen fixation, which has ex- es are irreplaceable, or the technology neces- necessary for mitigating this degradation. acerbated ongoing eutrophication while fertil- sary to replace them is prohibitively expen- Enhanced public appreciation of ecosystem izing remote portions of the planet (3). sive. For example, desalination, although of- services would help promote connections Increases in global commerce have led to the ten proposed as an alternative to conservation between science and management. In many spread of pests and diseases that do great and planned growth in areas with limited cities in Germany, rooftop gardens and oth- harm because they are divorced from their fresh water, is more than twice as expensive er techniques to decrease the impacts of natural predators and pathogens (4). as most water users are willing to pay (9). hard surfaces are gaining broad support. Studying the few and rapidly shrinking Maintenance of ecosystem services will Without greater public understanding of undisturbed ecosystems is important, but require a considerably better understanding the links between ecosystems and human now is the time to focus on an ecology for of the natural patterns and processes that sus- welfare, science will be of little use. For ex- the future. Because our planet will be over- tain them (10). Innovative research must be ample, consensus exists among stakeholders populated for the foreseeable future and nat- initiated to answer crucial questions. Which in the Chesapeake Bay watershed in the ural resource consumption shows no signs ecological services are irreplaceable or too eastern United States that water quality of slowing, human modifications of the en- expensive or whose replacement with emerg- needs improvement and that restoration of a vironment will only increase. Thus, a re- collapsed fishery, the American oyster, is de- search perspective that incorporates human sirable. Stakeholders value clean water and activities as integral components of Earth’s the oyster fishery for the material, cultural, ecosystems is needed, as is a focus on a fu- and spiritual benefits they provide. They are ture in which Earth’s life support systems willing to consider upgrading water treat- are maintained while human needs are met. ment facilities and replacing native shellfish Ecological science has been important with a non-native oyster. However, stake- in improving human life (5), and research holders need to understand risks associated addressing the sustainability and resilience with introduction of a non-native species, as of socioecological systems has begun (6, well as scientific evidence that recovery of 7). Elsewhere, we discuss partnerships and shellfish may not be possible without programs that are required (8). Here, we changes in current land-use practices. recommend a research agenda centered on Designer ecosystem. In the desert southwest, 1 2 University of Maryland, College Park, MD; Duke natural stream flow (top) varies but may in- University, Durham, NC; 3University of California, Santa Cruz, CA; 4University of New Mexico,Albuquerque, NM; crease substantially after large summer rainfall 5Princeton University, Princeton, NJ; 6Ecological Society events. A common engineering solution has of America, Washington, DC; 7David and Lucile Packard been to convert stream channels to concrete Foundation, Los Altos, CA; 8U.S. Geological Survey, culverts (middle). This reduces economic loss 9 Columbia, MO; Johns Hopkins University, Baltimore, from flooding but provides few other ecological, MD; 10University of Calgary,Alberta, Canada; 11Instituto de Ecologia, Xalapa, Mexico; 12Stanford University, social, or economic benefits. An alternative to Pacific Grove, CA; 13Institute of Ecosystem Studies, concrete is a designer ecosystem, such as Indian Millbrook, NY; 14University of Michigan, Ann Arbor, MI; Bend Wash in Scottsdale,AZ (bottom), in which 15University of California, Santa Barbara, CA; 16COM- vegetated pathways and wetlands minimize PASS, Washington, DC; 17University of Colorado, flood damage, improve water quality, enhance 18 Boulder, CO; University of Wisconsin, Madison, WI. surrounding land values, and create a park-like *Author for correspondence. E-mail: [email protected] environment for recreational activities. www.sciencemag.org SCIENCE VOL 304 28 MAY 2004 1251 P OLICY F ORUM Determining how natural systems pro- Ecological design approaches will need include annual migrations and floods that, vide ecological services entails measuring to combine ecological principles with ideas when halted, cause negative impacts on fish- services and exploring their dynamics at or technology from other disciplines. For eries, agriculture, and biotic diversity (15). We scales that match ecosystem properties. New example, wastewater engineers and ecolo- need to identify ecological commerce routes spatial, analytical, and other quantitative ap- gists share strong scientific interests yet and the impacts that changes in the routes or proaches will be needed to understand how rarely enter into dialogue. Engineering rate of material exchange will have; to con- ecological responses depend on space and process design could benefit from new mo- sider the potential to use ecological commerce time (11). Interdisciplinary frameworks that lecular-based advances in our understand- in designing solutions for environmental incorporate multivariate causality, nonlinear ing of nutrient transformations, and ecolo- problems; and to develop principles that can feedback, and individual-based decision- gists could benefit by using engineered be used to diminish negative impacts. making are critical to research that explicit- biosystems as research tools (13). ly incorporates humans in ecosystems. There is a particularly urgent need for re- Pragmatic Ecological Science search to design ecological solutions for Our future environment will largely consist of Designed Ecological Solutions problems related to three issues: urbaniza- human-influenced ecosystems, managed to Restoration of ecological systems has already tion, the degradation of fresh water, and the varying degrees, in which the natural services become a booming business; billions of dol- movement of materials between ecosystems. that humans depend on will be harder and lars are spent annually to restore polluted wa- Shortages of clean surface water, overextrac- harder to maintain. The role of science in a terways and to revegetate lands that have tion of groundwater, and long-distance trans- more sustainable future must involve an im- been degraded, fragmented, or paved over fers of water are increasing at alarming rates proved understanding of how to design eco- (see the figure on page 1251). However, “de- (9). Research priorities must include an in- logical solutions, not only through conserva- signing” ecosystems goes beyond restoring a creased understanding of how to restore the tion and restoration, but also by purposeful in- system to a past state, which may or may not natural services provided by waterways, to vention of ecological systems to provide vital be possible. It suggests creating a well-func- restore or design ways to naturalize flow in services. Shifting from a focus primarily on tioning community of organisms that opti- regulated rivers, and to slow the high extinc- historical, undisturbed ecosystems to a per- mizes the ecological services available from tion rates of freshwater species. Upland wa- spective that acknowledges humans as com- coupled natural-human ecosystems. tershed use is