The Princeton Guide to Ecology

Ecosystem services have not been traditional targets of biodiversity conservation efforts. Researchers, practitioners, and policy makers have focused their attention on genes, populations, species, or ecosystems. As societal interest in ecosystem services grows, however, these may provide an improved platform for communicating and quantifying their value to humans and thus improving our understanding of the dependence of our well-being on nature and ecosystem services. Once this link is firmly established, conservation of ecosystem services should be a more natural societal choice.

biological diversity. The variety and variability of all forms of life on Earth, encompassing the interactions among them and the processes that maintain them.

ecosystem services. The benefits people obtain from ecosystems. They can be of four primary types: provisioning, regulating, cultural, and supporting ecosystem services.

ecosystem service trade-off. Reduction of the provision of one ecosystem service as a consequence of increased use of another ecosystem service. They arise from management choices made by humans, which can change the type, magnitude, and relative mix of services provided by ecosystems.

Millennium Ecosystem Assessment. A global assessment carried out between 2001 and 2005 that involved more than 1360 experts worldwide and had the objectives of assessing the consequences of ecosystem change for human well-being and establishing the scientific basis for conservation and sustainable use of ecosystem services.

systematic conservation planning of ecosystem services. A scientific process for integrating social and biological information, to support decisionmaking about the location, configuration, and management of areas designated for the conservation and sustainable use of ecosystem services.

The visibility of the term ecosystem services recently exploded in the scientific literature: the total number of references accumulated by the late 1990s is smaller than the figure for 2005 or 2006 alone (figure 1). Attempts to preserve, restore, or enhance ecosystem services, however, clearly predate this. The first national park of the world, Yellowstone National Park, located in the northwestern United States, was established in 1872. A remarkable combination of unique geological features, striking landscapes, and abundant wildlife were preserved “for the benefit and enjoyment of the people”—in other words, for the cultural ecosystem services (ES) provided to humans. As an even earlier example, the entire global herd of Père David’s deer (Elaphurus davidianus) descends from a few animals kept for recreation in the Imperial Hunting Park south of Beijing (a cultural ES)—the deer is believed to have become extinct in the wild during the Ming Dynasty (1368–1644). The Inca empire arose in Peru in the thirteenth century and thrived in part because of its effective management of provisioning ES, such as maize (Zea mays) cultivation and herding of llamas (Lama glama). Soils, a supporting ES, were conserved by terracing the mountainside. Between 300 BC and AD 200, Rome built 11 major aqueducts, developed by the Roman Empire to service its roughly 1 million inhabitants. Major engineering achievements allowed the

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