Wetlands provide habitat for many species of plants and animals, as well as ecological functions such as nutrient cycling (Level 1 in figure below). They also provide valuable "ecosystem services" to the human environment, such as water purification, flood mitigation, boating, hunting, fishing, and scenic enjoyment (Level 2 in figure below). "Ecosystem services" is shorthand for the "goods" and "services" that link the biological functions and the social values of wetlands. These services are quantified through a variety of methods (Level 3 in figure below).

The valuation of these ecosystem services can be used to help prioritize wetlands for decisions on effective mitigation of the impacts of human activities.

Ecology of Wetlands
Adapted from Hein, et al (2006), and Turner and Daily (2008)