WETLAND

摘要

Wetlands occur on every continent and in every climatic zone from the tropics to thepolar regions (even Antarctica1, depending on your definition of a wetland). Plus, wetlands are the dominant vegetated ecosystem in the circumpolar Arctic. Defining a wetland is more difficult than describing one but even that is a complex undertaking. In general,wetlands are areas of hydric soils inundated in water at least part of the time. Wetlands support plants adapted to saturated soil types, which in turn support resident and seasonal animal populations. Basically, wetlands occur where water meets land, often in naturally flat terrain.