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Classification of Natural Ponds and Lakes
in the Glaciated Prairie Region

Subclasses of Natural Ponds and Lakes

Distinct subclasses may be recognized within several of the major classes of wetlands, including temporary, seasonal, semipermanent, and permanent ponds and lakes. These subclasses are based on differences in species composition of plant communities within wet-meadow, shallow-marsh, or deep-marsh zones that are correlated with variations in average salinity of surface water. The subclasses are designated as follows:

Subclass A-fresh
Subclass B-slightly brackish
Subclass C-moderately brackish
Subclass D-brackish
Subclass E-subsaline

Normal and extreme ranges in specific conductance (micromhos/cm³) of surface water in plant communities that characterize these varying degrees of salinity are shown in the section on Plant Species Composition and Differences in Salinity of Surface Water.

Subclasses represented (prevalent subclasses in bold face) in the four major classes referred to are as follows:

Class II-temporary pondsA, B
Class III-seasonal ponds and lakes A, B, C
Class IV-semipermanent ponds and lakesA, B, C, D, E
Class V-permanent ponds and lakesB, C, D, E

Plant communities of each subclass differ with respect to occurrence or abundance of various plant species. The principal species in each subclass for temporary (Class II), seasonal (Class III), semipermanent (Class IV), and permanent (Class V) ponds and lakes are listed in appendix A. Subclasses are also indicated for many of the illustrations of major classes of wetlands (plates 2 to 26).

Recognition of subclasses requires a visual appraisal of the abundance of various wetland plants, especially primary emergent species in the wet-meadow, shallow-marsh, and deep-marsh zones. The prevalent species of these zones in a particular pond or lake may be compared with the principal species listed under each subclass for the zones being considered. A subclass designation can then be assigned on the basis of similarity.

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