Northern Prairie Wildlife Research Center
Fen (alkaline bog) zone.
In each zone, characteristic plants may be found as a general mixture or may be represented by one or more distinct associations, each composed of one or more species. These zones are closely related to differences in water permanence, modified by permeability of bottom soils and influence of ground water. Certain wetlands contain only one zone; others contain two, three, or more zones. In wetlands with two or more zones, one zone usually occupies the central, deeper part of the pond basin, while the others occur as concentric peripheral bands. The presence or absence and the distributional pattern of the zones are the primary factors used in distinguishing the major classes of wetlands.