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In the system of Martin et al., difference in water depth during the growing season is the primary factor used in identifying most wetland types; in the system presented here, occurrence of dominant plant associations in the central vegetational zone characterize the major wetland classes. The classification of Martin et al. is also based partly on variations in cover interspersion which are treated secondarily as cover types in this system. For example, Types 3, 4, and 5 wetlands as described by Martin et al. could correspond to cover types 1, 2, and 3 of semipermanent (Class IV) wetlands in this classification when the relation between cover and open water is considered.

Some plants listed by Martin et al. are common to several of their wetland types. For instance, bulrushes may occur in Types 3, 4, and 5 of Martin et al., whereas in this system most species of bulrush would be considered members of the plant association used to indicate the subclass of a semipermanent (Class IV) or permanent (Class V) pond or lake.

Prairie wetlands are designated in the classification of Martin et al. as either inland fresh (Types I to 5) or inland saline (Types 9 to 11). No mention is made of the important brackish-water environments that lie between the two extremes. The plant lists accompanying the descriptions for the types of Martin et al. indicate that subclasses A and B and subclasses C to E of the present classification would generally correspond to "fresh" and "saline" categories, respectively.

The shallower wetland types of Martin et al. may form peripheral borders around deeper types in the same spatial arrangement as vegetational zones listed in this classification. Thus, a Type 3 (shallow fresh marsh) wetland in the classification of Martin et al. would correspond to a shallow-marsh zone in the classification here described and could occupy the central area of a pond basin or border deep marsh on the landward side. In the former case it would be considered a Class III (seasonal) pond or lake, while in the latter situation it would be designated as one peripheral zone of a Class IV, V, or VI pond or lake.

With due regard for these qualifications, the following rough correlation of the two systems may be made: