In consequence, the specific conductance of semipermanent wetlands ranges from less than 500 to over 70,000 micromhos. The dominant plants in the central or deepest zones of semipermanent wetlands are usually tall, robust emergent bulrushes or cattails or, in the open water phase, pondweeds, milfoil, and other submerged aquatics. In addition to their great vegetative diversity, the great value of semipermanent wetlands to birds stems from their production of amphipods, snails, and other invertebrate animal life during the summer and fall when other wetlands are often dry. Semipermanent wetlands form the principal nesting areas for all of North Dakota's overwater nesting waterfowl and most of our other marsh and aquatic birds, including the black-crowned night heron, American coot, and black tern. They are also the principal habitat for the mink and muskrat and provide wintering areas for deer and upland game birds.
Fens are palustrine wetlands characterized by the surficial exposure of alkaline groundwater.
These wetlands average about 10 acres in area. Water in most fens ranges in specific conductance from 1,000 to 3,000 micromhos. Coarse emergents such as phragmites and common cattail, and several shrubby species of willow usually dominate the central zones of fen wetlands. Muskgrass, a large alga, can usually be found in the small open water seepage areas of fens. Fens have boggy or quaking bottom soils.