Definitions

Wetlands contain unique vegetation and soils, driven by hydrology—depth, duration, frequency, and seasonality of inundation or soil saturation—that create anaerobic soil conditions and that act as an environmental sieve, favoring those who can adapt and weeding out those who cannot. Wetlands are defined based on their hydrology and source of water, precipitation, surface flow and subsurface flow, and vegetation type. Classification systems based on hydrology, vegetation, and soils have been developed by a number of countries, including the United States, Canada, and China. Ramsar, the Convention on Wetlands of International Importance, developed a classification system used by many countries and guides protection and wise use of wetlands. Protection and regulation of wetlands varies enormously among nations. The United States is one of a handful of countries where wetlands are regulated by national laws and where restoration is a tool to mitigate for their loss. A major reason for wetland protection is their ability to deliver key ecosystem services to people. Such services include provisioning (food, water), regulating (waste assimilation), supporting (biodiversity), cultural services (recreation), and carbon sequestration.