From Issues in Ecology, No. 2, 1997. A publication of the Ecological Society of America, Washington, DC.

(This article was submitted by Dr. Jeffrey A. Simmons of West Virginia Wesleyan College. He has slightly revised it for use in the Voice. Permission has been granted from the Ecological Society of America for the use of this material)

Human societies derive many essential goods from natural ecosystems, including seafood, game animals, fodder, fuelwood, timber and pharmaceutical products. These goods represent important and familiar parts of the economy. What has been less appreciated until recently is that natural ecosystems also perform fundamental life-support services without which human civilizations would cease to thrive. These include the purification of air and water, detoxification and decomposition of wastes, regulation of climate, regeneration of soil fertility, and production and maintenance of biodiversity, from which key ingredients of our agricultural, pharmaceutical, and industrial enterprises are derived. This array of services is generated by a complex interplay of natural cycles powered by solar energy and operating across a wide range of space and time scales. The process of waste disposal, for example, involves the life cycles of bacteria as well as the planet-wide cycles of major chemical elements such as carbon and nitrogen. Such processes are worth many trillions of dollars annually.

Yet because most of these benefits are not traded in economic markets, they carry no price tags that could alert society to changes in their supply or deterioration of underlying ecological systems that generate them. Because threats to these systems are increasing, there is a critical need for identification and monitoring of ecosystem services both locally and globally, and for the incorporation of their value into decision-making processes.

Historically, the nature and value of Earth's life support systems have largely been ignored until their disruption or loss highlighted their importance. For example, deforestation has belatedly revealed the critical role forests serve in regulating the water cycle -- in particular, in mitigating floods, droughts, the erosive forces of wind and rain, and silting of dams and irrigation canals. Today, escalating impacts of human activities on forests, wetlands, and other natural ecosystems imperil the delivery of such services. The primary threats are land use changes that cause losses in biodiversity as well as disruption of carbon, nitrogen, and other biogeochemical cycles; human-caused invasions of exotic species; releases of toxic substances; possible rapid climate change; and depletion of stratospheric ozone.

* Ecosystem services are essential to civilization.

* Ecosystem services operate on such a grand scale and in such intricate and little-explored ways that most could not be replaced by technology.

* Human activities are already impairing the flow of ecosystem services on a large scale.

* If current trends continue, humanity will dramatically alter virtually all of Earth's remaining natural ecosystems within a few decades.

* Many of the human activities that modify or destroy natural ecosystems may cause deterioration of ecological services whose value, in the long term, dwarfs the short-term economic benefits society gains from those activities.

* Considered globally, very large numbers of species and populations are required to sustain ecosystem services.

* The functioning of many ecosystems could be restored if appropriate actions were taken in time.

We believe that land use and development policies should strive to achieve a balance between sustaining vital ecosystem services and pursuing the worthy short-term goals of economic development.

Many societies today have technological capabilities 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 limitations of regional growing seasons and soils. These developments have focused so much attention upon human-engineered and exotic sources of fulfillment that they divert attention from the local biological underpinnings 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 natural ecosystems, and the species that are part of them, help sustain and fulfill human life. These services maintain biodiversity and the production of ecosystem goods, such as seafood, wild game, forage, timber, biomass fuels, 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.

* 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,

* partial stabilization of climate,

* moderation of weather extremes and their impacts, and

* provision of aesthetic beauty and intellectual simulation 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 ecosystems services play in generating those ecosystem goods that are traded in the marketplace. As a result, this lack of awareness helps drive the conversion of natural ecosystems to human-dominated systems (e.g., wheatlands or oil palm fields), whose economic value can be expressed, at least in part, in standard currency. The second reason to focus on natural ecosystems is that many human-initiated disruptions of these systems -- such as introductions of exotic species, extinctions of native species, and alteration of the gaseous composition of the atmosphere through fossil fuel burning -- are difficult or impossible to reverse on any time scale relevant to society.

Third, if awareness is not increased and current trends continue, humanity will dramatically alter Earth’s remaining natural ecosystems within a few decades.

* The annual world fish catch (about 100 million metric tons), which is the leading source of animal protein, has a value of 50 to 100 billion dollars.

* About 15% of the world's energy consumption is supplied by fuelwood and other plant material.

* The more species in an ecosystem, the more stable and resilient it tends to be.

* Extractions from the "genetic library" of natural ecosystems is responsible for annual increases in crop productivity of about 1 percent.

* 118 of the top 150 most-commonly prescribed drugs are derived from natural sources.

* Living organisms have helped buffer the Earth's climate during ancient periods of drastic climate change and continue to do so.

* 50% of the mean annual rainfall in the Amazon is recycled by the forest which helps maintain its moist conditions year round.

* Vegetation greatly reduces the erosion of soil and increases the ability of soil to hold water.

* The Mississippi Flood of 1993 (and billions of dollars of damage) could have been prevented if some of the original natural wetlands along the river had not been filled in for development.

* Soil degradation may have contributed to the fall of most ancient empires including Roman, Babylonian and Mayan civilizations.

* Soils worldwide decompose and degrade about 130 billion metric tons of organic waste each year free of charge.

* About 70 percent of agricultural crop species that feed the world require an insect or animal to pollinate their flowers. Most of these pollinators live in natural ecosystems.

* About 99% of all potential crop pests are controlled (in part) by natural predators such as birds, spiders and wasps. We would be using even more pesticides if it weren't for them.

The human economy depends upon the services performed "for free" by ecosystems. The ecosystem services supplied annually are worth many trillions of dollars. Economic development that destroys habitats and impairs services can create costs to humanity over the long term that may greatly exceed the short-term economic benefits of the development. [bold and italics in this paragraph added by editor] These costs are generally hidden from traditional economic accounting, but are nonetheless real and are usually borne by society at large. Tragically, a short-term focus in land-use decisions often sets in motion potentially great costs to be borne by future generations. This suggests a need for policies that achieve a balance between sustaining ecosystem services and pursuing the worthy short-term goals of economic development.