EPA's Report on the Environment (ROE)

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Ecological Condition

“Ecological condition” refers to the state of ecological systems, which includes their physical, chemical, and biological characteristics and the processes and interactions that connect them. Understanding ecological condition is crucial, because humans depend on healthy ecological systems for food, fiber, timber, flood control, and many other benefits.1 Many Americans also attribute deep significance and important intangible benefits to ecological systems and their diversity of plants and animals.2 EPA, other federal agencies, and state agencies collectively bear responsibility for ensuring that ecological systems are conserved. Learn more »

An “ecological system” (ecosystem) is a biological community consisting of all the living organisms (including humans) in a particular area and the nonliving components, such as air, water, and mineral soil, with which the organisms interact. Ecosystems do not always have clear-cut boundaries. For example, where does a forest end and a meadow begin, or the coastal saltmarsh end and the freshwater marsh begin? Many ecosystems are defined based on their predominant species (e.g., forested ecosystem) or physical characteristics (e.g., stream ecosystem), with the boundaries established to follow a set of scientific or management rules or protocols. Examples of ecological systems3 include forests, grasslands, agricultural systems, lakes, streams, wetlands, estuaries, and coral reefs. Ecosystem processes cycle water and nutrients, build soils, produce the oxygen we breathe, remove carbon dioxide and other greenhouse gases from the atmosphere, and perform many other functions that are important for the health of people and the planet.
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EPA's mission is “to protect human health and the environment.”4 The ROE indicators of ecological condition address five fundamental questions about the state of the nation's ecological systems, providing insight into the degree to which the natural environment is being protected:

Exhibit 1. This exhibit shows a simple paradigm for understanding ecological condition. The exhibit shows five interconnected elements: extent and distribution; diversity and biological balance; ecological processes; physical/chemical attributes; and exposure to contaminants. Each of these five elements interacts with all the other elements. Stressors, depicted as arrows, are shown affecting all five attributes directly, and also indirectly through feedback and interaction among the attributes.

Each of these questions relates to a specific element in the ecological condition paradigm depicted in Exhibit 1. Ecological condition results from the interactions of these ecological elements with each other, and with different stressors. Stressors are factors that perturb the ecosystem; they can be natural (e.g., hurricanes, floods) or human-induced (e.g., toxic chemicals or introduced invasive species).

While the indicators presented in Air, Water, and Land focus on trends in individual media, the indicators presented to answer the five ecological condition questions focus on trends affected simultaneously by contaminants or other stressors in multiple media.

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