Issues in Ecology Number 2 Spring 1997 Ecosystem Services:Benefits Supplied to Human Societies by Natural Ecosystems by Gretchen c daily susan alexander paul r fhrlich enco.Pamela A.Matson.Harold A.Moon INTRODUCTION purification of air and water mitigation of droughts and floods Many societies today have technological capa- generation and preservation of soils and renewal of bilities undreamed of in centuries past.Their citizens their fertility. have such a global command of resources that even foods detoxification and decomposition of wastes flown in fresh from all over the planet are taken for pollination of crops and natural vegetation. pled from the limita dispersal of seeds. nd soils.These de 。and moy sed so much attention upor men t of nutrients e vast majority of potential agricultura human-engineered and exotic sources of fulfillment that pests. they divert attention from the local biological underpin- maintenance of biodiversity. nings that remain essential to economic prosperity and protection of coastal shores from erosion by waves other aspects of our well-being. protection from the sun's harmful ultraviolet rays These biological underpinnings ar enc mpassed artial stabilization of climate. in the system s services. ather extremes and thei acts d proce through whic 0 ral ecosystems,and the species that are part of them help sustain and fulfill human life.These services main Although the distinction between "natural"and tain biodiversity and the production of ecosystem goods "human-dominated"ecosystems is becoming increasingly such as seafood,wild game.forage.timber,biomass fu- blurred,we emphasize the natural end of the spectrum els,natural fibers,and many phar naceuticals.industrial for three related reasons.First,the services flowing from oducts and thei The ha cosystems are grea ndervalued by P tant partsof For the most part. they are not tra ded in forr market: the human economy.In addition to the production of and so do not send price signals that wam of changes in goods,ecosystem services support life through(Holdren their supply or condition.Furthermore,few people are and Ehrlich 1974;Ehrlich and Ehrlich 1981): conscious of the role natural ecosystem services play in forest in Colorado,filtering and pu- rifying air and water.12 Issues in Ecology Number 2 Spring 1997 Ecosystem Services: Benefits Supplied to Human Societies by Natural Ecosystems by Gretchen C. Daily, Susan Alexander, Paul R. Ehrlich, Larry Goulder, Jane Lubchenco, Pamela A. Matson, Harold A. Mooney, Sandra Postel, Stephen H. Schneider, David Tilman, George M. Woodwell INTRODUCTION Many societies today have technological capa￾bilities undreamed of in centuries past. Their citizens have such a global command of resources that even foods flown in fresh from all over the planet are taken for granted, and daily menus are decoupled from the limita￾tions of regional growing seasons and soils. These de￾velopments have focused so much attention upon human-engineered and exotic sources of fulfillment that they divert attention from the local biological underpin￾nings that remain essential to economic prosperity and other aspects of our well-being. These biological underpinnings are encompassed in the phrase ecosystem services, which refers to a wide range of conditions and processes through which natu￾ral ecosystems, and the species that are part of them, help sustain and fulfill human life. These services main￾tain biodiversity and the production of ecosystem goods, such as seafood, wild game, forage, timber, biomass fu￾els, natural fibers, and many pharmaceuticals, industrial products, and their precursors. The harvest and trade of these goods represent important and familiar parts of the human economy. In addition to the production of goods, ecosystem services support life through (Holdren and Ehrlich 1974; Ehrlich and Ehrlich 1981): • purification of air and water. • mitigation of droughts and floods. • generation and preservation of soils and renewal of their fertility. • detoxification and decomposition of wastes. • pollination of crops and natural vegetation. • dispersal of seeds. • cycling and movement of nutrients. • control of the vast majority of potential agricultural pests. • maintenance of biodiversity. • protection of coastal shores from erosion by waves. • protection from the sun’s harmful ultraviolet rays. • partial stabilization of climate. • moderation of weather extremes and their impacts. • provision of aesthetic beauty and intellectual stimu￾lation that lift the human spirit. Although the distinction between natural and human-dominated ecosystems is becoming increasingly blurred, we emphasize the natural end of the spectrum, for three related reasons. First, the services flowing from natural ecosystems are greatly undervalued by society. For the most part, they are not traded in formal markets and so do not send price signals that warn of changes in their supply or condition. Furthermore, few people are conscious of the role natural ecosystem services play in Figure 1-Aspen (Populus tremuloides) forest in Colorado, filtering and pu￾rifying air and water. Photo by J. Robert Stottlemeyer/Biological Photo Service