Technical Bulletin No. 0606: Forested Wetlands Classification and Mapping: A Literature Review

Classification and mapping of forest wetlands facilitates communication, understanding, and management of a resource steeped in social, economic, and environmental concern. A broad spectrum of classification systems exists; this review attempts to portray their advantages, disadvantages, and inter-relationships. Included is a review of classification theory for resource management and the historical development of national wetland inventories and wetland classification schemes.

Diagnostic criteria for wetland classification vary widely and are a function of the intended application of the classification and the variability of the forested wetlands resource. Chemical, hydrologic, vegetative, soil, physiographic, ecosystem/ecological, and management criteria commonly distinguish wetland classes.

Approaches to forested wetlands classification are single-factor or multifactor, hierarchical or unstructured, and physiographic or parametric. Multifactor approaches are favored since they have the potential to integrate ecological properties. Hierarchical classifications enable finer, low-level associations among diagnostic characteristics to be absorbed into broader, high-level relationships. Physiographic classifications are commonly small-scale and based on natural units of the earth's surface. Parametric approaches are objective, measurement-derived classifications for detailed applications. Hierarchical physiographic classifications may contain a parametric approach at lower, refined levels. Regional approaches to forested wetlands classification (based on unique diagnostic characteristics of the local resource or accepted convention) can be retained at the lowest hierarchical levels. New approaches to classification should be cognizant of existing systems.