Ecological Attributes Worth Measuring

Ecological indicators are chosen to report on the state, or condition, of ecosystems. In contrast to the more familiar environmental indicators, ecological indicators are not intended to report on the quantities of pollutants or other stressors affecting ecosystems or on what government or other programs are doing (e.g., issuing permits).

Two recent initiatives have engaged hundreds of individuals in defining the condition of ecosystems: a Heinz Foundation project, which produced The State of the Nation's Ecosystems, and the global Millennium Ecosystem Assessment. Both projects have been extraordinarily successful, providing unprecedented advances in the development and use of ecological indicators and garnering substantial interest from governmental and nongovernmental institutions.

The Heinz Foundation report begins by defining six ecosystem types (coasts and oceans, forests, farmlands, fresh waters, grasslands and shrublands, and urban and suburban areas). The project's goals were to define indicators characterizing these ecosystem types - on the scale of small watersheds to the planet as a whole and at any scale in between - and to support policy debate and decision making at the national scale.

The report identifies 10 major characteristics of ecosystem condition, organized into four classes (Figure 1). Each of the four classes - system dimensions (geographic extent),

Groups of characteristics

System dimensions

Chemical and physical

Biological components

Human use

The state of the nation's ecosystems

Ecosystem characteristics

Extent landscape pattern fragmentation

Nutrients contaminants physical conditions

Plants, animals communities ecological productivity

Food, fiber water recreation other services


22 indicators

26 indicators

33 indicators

22 indicators

Figure 1 Example ecosystem characteristics and number of indicators examined in the State of the Nation's Ecosystems report. Modified from Heinz Center (The H. John Heimz III Center for Science, Economics and the Environment) (2002) The State of The Nation's Ecosystems: Measuring the Lands, Waters, and Living Resources of the United States. New York: Cambridge University Press.

chemical and physical condition, status of biological components, and goods and services that human society receives from the ecosystems being measured - comprises about 2233 specific indicators. As of 2002, the data needed to report on the 103 identified indicators in the four classes were available at a national scale for only one-third of the indicators; some data were available for an additional one-fourth of the indicators. Nearly a third were supported by inadequate data, and about one-seventh needed further development.

Two areas of indicator development have been especially active in the past two decades: the development and use of multimetric biological indexes as measures of divergence from biological integrity and the cataloging and documenting of ecosystems services, a crucial component of the fourth group of Heinz indicators. Perhaps the best framing of the ecological services concept and the importance ofthose services to human well-being was produced by the Millennium Ecosystem Assessment (Figure 2). Rather than providing a simple listing, this project carefully defined four major types of services supplied to humans by healthy ecosystems: supporting (e.g., soil formation), provisioning (e.g., food and water), regulating (e.g., climate, flood control), and cultural (e.g., esthetic and recreational values). This framework offers both a constructive way to organize ecological thinking and a means to communicate with disparate groups ofpeople.

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