ML18019A904

Cowardin Et Al 1979 - TN5186 - Cowardin 1979

ML18019A904
Person / Time
Site:	Clinch River
Issue date:	12/31/1992
From:	US Dept of Interior, Fish & Wildlife Service
To:	Office of New Reactors
Fetter A
References
Download: ML18019A904 (142)

Text

FWS/OBS-79/31 DECEMBER 1979 Reprinted 1992 Classification of Wetlands and Deepwater Habitats of the United States U.S. Department of the Interior Fish and Wildlife Service

The Biological Services Program was established within the U.S. Fish and Wildlife Service to supply scientific information and methodologies on key environmental issues which have an impact on fish and wildlife resources and their supporting ecosystems. The mission of the Program is as follows :

1.

To strengthen the Fish and Wildlife Service in its role as a primary source of information on natural fish and wildlife resources, particularly with respect to environmental impact assessment.

2 To gather, analyze, and present information that will aid decisionmakers in the identification and resolution of problems associated with major land and water use changes.

3.

To provide better ecological information and evaluation for Department of the Interior development programs, such as those relating to energy development Information developed by the Biological Services Program is intended for use in the planning and decisionmaking process, to prevent or minimize the impact of development on fish and wildlife. Biological Services research activities and technical assistance services are based on an analysis of the issues, the decision-makers involved and their information needs, and an evaluation of the state-of-the-art to identify information gaps and determine priorities. This is a strategy to assure that the products produced and disseminated will be timely and useful.

Biological Services projects have been initiated in the following areas :

Coal extraction and conversion Power plants Geothermal, mineral, and oil shale development Water resource analysis, including stream alterations and western water allocation Coastal ecosystems and Outer Continental Shelf development Systems and inventory, including National Wetlands Inventory, habitat classification and analysis, and information transfer The Program consists of the Office of Biological Services in Washington, D.C.,

which is responsible for overall planning and management ; National Teams which provide the Program's central, scientific, and technical expertise, and which ar range for contracting of Biological Services studies with States, universities, con-sulting firms, and others ; Regional staff who provide a link to problems at the operating level ; and staff at certain Fish and Wildlife Service research facilities who conduct inhouse research studies.

CLASSIFICATION OF WETLANDS AND DEEPWATER HABITATS OF THE UNITED STATES By Lewis M. Cowardin U.S. Fish and Wildlife Service Northern Prairie Wildlife Research Center Jamestown, North Dakota 58401 Virginia Carter U.S. Geological Survey Reston, Virginia 22092 Francis C. Golet Department of Natural Resources Science University of Rhode Island Kingston, Rhode Island 02881 and Edward T. LaRoe U.S. National Oceanographic and Atmospheric Administration Office of Coastal Zone Management Washington, D.C.

20235 Performed for U.S. Department of the Interior Fish and Wildlife Service Office of Biological Services Washington, D.C.

20240 For sale by the Superintendent of Documents, U.S. Government Printing Office Washington, D.C.

20402 FWS/OBS-79/31 December 1979

Library of Congress Cataloging in Publication Data United States, Fish and Wildlife Service Classification of wetlands and deepwater habitats of the United States.

(Biological services program

FWS/OBS-79/31) 1. Wetlands-United States-Classification.

2. Wetland ecology-United States.

3. Aquatic ecology-United States. I. Cowardin, Lewis M. II. Title.

III. Series: United States. Fish and Wildlife Service. Biological services program

FWS/OBS-79/31.

QH76.U54a 79/31

[QH104]

574.5'0973s

[574.5'2632]

79-607795

Foreward Wetlands and deepwater habitats are essential breeding, rearing, and feeding grounds for many species of fish and wildlife. They may also perform important flood protection and pollution control funtions. Increasing National and international recognition of these values has intensified the need for reliable information on the status and ex-tent of wetland resources. To develop comparable information over large areas, a clear definition and classification of wetlands and deepwater habitats is required.

The classification system contained in this report was developed by wetland ecologists, with the assistance of many private individuals and organizations and local, State, and Federal agencies. An operational draft was published in October 1977, and a notice of intent to adopt the system for all pertinent Service activities was published December 12, 1977 (42 FR 62432).

The Fish and Wildlife Service is officially adopting this wetland classification system. Future wetland data bases developed by the Service, including the National Wetlands Inventory, will utilize this system. A one-year transition period will allow for training of Service personnel, amendment of administrative manuals, and further development of the National Wetlands Inventory data base. During this period, Service personnel may continue to use the old wetland classification described in Fish and Wildlife Service Circular 39 for Fish and Wildlife Coordination Act reports, wetland acquisition priority determinations, and other activities in conjunction with the new system, where immediate conversion is not practicable.

Upon completion of the transition period, the Circular 39 system will no longer be officially used by the Fish and Wildlife Service except where applicable laws still reference that system or when the only information available is organized according to that system and cannot be restructured without new field surveys.

Other Federal and State agencies are encouraged to convert to the use of this system. No specific legal authorities require the use of this system-or any other system for that matter. However, it is expected that the benefits of National consistency and a devel9ping wetland data base utilizing this system will result in acceptance and use by most agencies involved in wetland management. Training can be provided to users by the Service, depending on availability of resources. Congressional committees will be notified of this adoption action and will be encouraged to facilitate general adoption of the new system by amending any laws that reference the Circular 39 system.

This is a new system and users will need to study and learn the terminology. The Service is preparing a document to aid in comparing and translating the new system to the Service's former classification system. In the coming year, the Fish and Wildlife Service, in conjunction with the Soil Conservation Service, also plans to develop initial lists of hydrophytic plants and hydric soils that will support interpretation and use of this system.

We believe that this system will provide a suitable basis for information gathering for most scientific, educational, and administrative purposes ; however, it will not fit all needs. For instance, historical or potentially restorable wetlands are not included in this system, nor was the system designed to accommodate all the requirements of the many recently passed wetland statutes. No attempt was made to define the proprietary or jurisdictional boundaries of Federal, State, or local agencies. Nevertheless, the basic design of the classification system and the resulting data base should assist substantially in the administration of these programs.

This report represents the most current methodology available for wetland classification and culminates a long-term effort involving many wetland scientists. Although it may require revision from time to time, it will serve us well in the years ahead. We hope all wetland personnel in all levels of government and the private sector come to know it and use it for the ultimate benefit of America's wetlands.

Lynn A. Greenwalt, Director U.S. Fish and Wildlife Service

Preface Since its publication in 1979, Classification of Wetlands and DeepwaterHabitats ofthe United States has been used in the National inventory of wetlands conducted by the U.S. Fish and Wildlife Service. The system has been widely used throughout the United States and is often cited in the scientific literature. There has also been considerable international interest in use of the classification.

Copies from the first printing have been expended and demand requires this reprinting. We have taken this oppor-tunity to correct a number of minor typographical errors, bring plant names into conformity with the National List ofScientific Plant Names (U.S. Dept. Agriculture 1982), and to upgrade the quality of plates as well as furnish addi-tional plates. No changes have been made that either alter the structure of the classification or the meaning of the definitions. Such major revisions must be deferred until certain prerequisite tasks are accomplished.

Completion of the list of hydrophytes and other plants occurring in wetlands and the list of hydric soils (see page

3) has been a task of far greater complexity than we envisioned when writing the classification. These lists have received extensive review and are being prepared as computer data bases. In addition, the lists will contain a great deal of ancillary information that will make possible the development of methodologies for their use in both the delinea-tion and classification of wetlands. When the lists and methodologies are completed, reviewed, and tested we will revise the classification and use the lists to add precision to the definitions. At the same time, we will address specific technical problems that have arisen during application of the classification.

The plates at the end of this publication are included primarily to illustrate a variety of examples of wetland classifica-tion. We have attempted to include photographs from various regions of the country insofar as possible ; however, final selection of plates was based on the availability of both high-quality photographs and the detailed field data required for accurate classification. While on sabbatical leave from the University of Rhode Island in 1985, Dr. Frank Golet took numerous photographs of Alaskan wetlands. Addition of many of these and several photographs from other regions helps somewhat to correct a regional imbalance.

We acknowledge the assistance of Dr. J. Henry Sather who served as editor for the reprinting. He spent many hours compiling minor errors and inconsistencies and preparing final copy for the printer. We thank Mr. Jon Hall, National Wetlands Inventory Coordinator for the Alaska region, for his assistance to Dr. Golet during his stay in Alaska.

Lewis M. Cowardin Virginia Carter Francis C. Golet Edward T. LaRoe September 24, 1985

Contents Page Abstract 1

Wetlands and Deepwater Habitats Concepts and Definitions 3

Wetlands..

3 Deepwater Habitats..

3 Limits 3

The Classification System 4

Hierarchical Structure..

4 Systems and Subsystems...

4 Marine System.

4 Estuarine System 4

Riverine System 7

Lacustrine System 9

Palustrine System 10 Classes, Subclasses, and Dominance Types.

10 Rock Bottom 13 Unconsolidated Bottom.

14 Aquatic Bed 15 Reef.

16 Streambed 16 Rocky Shore.

17 Unconsolidated Shore 18 Moss-Lichen Wetland...

19 Emergent Wetland 19 Scrub-Shrub Wetland.

20 Forested Wetland 20 Modifiers 21 Water Regime Modifiers 21 Water Chemistry Modifiers 22 Salinity Modifiers...

22 pH Modifiers..

23 Soil Modifiers...

23 Special Modifiers.

24 Regionalization for the Classification System 24 Use of the Classification System..

26 Hierarchical Levels and Modifiers 27 Relationship to Other Wetland Classifications.

27 Acknowledgments..

31 References 31 Appendix A. Scientific and common names of plants 35 Appendix B. Scientific and common names of animals 38 Appendix C. Glossary of terms 40 Appendix D. Criteria for distinguishing organic soils from mineral soils 42 Appendix E. Artificial key to the Systems 44 Artificial key to the Classes 44

No.

1 Distribution of Subclasses within the classification hierarchy.

2 Salinity modifiers used in this classification system.

3 pH modifiers used in this classification system.

4 Comparison of wetland types described in U.S. Fish and Wildlife Service Circular 39 with some of the major components of this classification system.

5 Comparison of the zones of Stewart and Kantrud's (1971) classification with the water regime modifiers used in the present classification system.

No.

Tables Figures 1

Classification hierarchy of wetlands and deepwater habitats, showing Systems, Sub-systems, and Classes. The Palustrine System does not include deepwater habitats.

2 Distinguishing features and examples of habitats in the Marine System.

3 Distinguishing features and examples of habitats in the Estuarine System.

4 Distinguishing features and examples of habitats in the Riverine System.

5 Distinguishing features and examples of habitats in the Lacustrine System.

6 Distinguishing features and examples of habitats in the Palustrine System.

7 Ecoregions of the United States after Bailey (1976) with the addition of 10 Marine and Estuarine Provinces proposed in our classification.

8 Comparison of the Water Chemistry Subclasses of Stewart and Kantrud (1972) with Water Chemistry Modifiers used in the present classification system.

Classification of Wetlands and Deepwater Habitats of the United States by Lewis M. Cowardin U.S. Fish and Wildlife Service Northern Prairie Wildlife Research Center Jamestown, North Dakota 58401 Virginia Carter U.S. Geological Survey, Reston, Virginia 22092 Francis C. Golet Department of Natural Resources Science University of Rhode Island, Kingston, Rhode Island 02881 and Edward T LaRoe U.S. National Oceanographic and Atmospheric Administration Office of Coastal Zone Management Washington, D.C. 20235 Abstract This classification, to be used in a new inventory ofwetlands and deepwater habitats ofthe United States, is intended to describe ecological taxa, arrange them in a system useful to resource managers, furnish units for mapping, and provide uniformity of concepts and terms. Wetlands are defined by plants (hydrophytes), soils (hydric soils), and frequency of flooding. Ecologically related areas of deep water, traditionally not considered wetlands, are included in the classification as deepwater habitats.

Systems form the highest level of the classification hierarchy; five are defined-Marine, Estuarine, Riverine, Lacustrine, and Palustrine. Marine and Estuarine Systems each have two Subsystems, Sub-tidal and Intertidal ; the Riverine System has four Subsystems, Tidal, Lower Perennial, Upper Peren-nial, and Intermittent ; the Lacustrine has two, Littoral and Limnetic; and the Palustrine has no Subsystems.

Within the Subsystems, Classes are based on substrate material and flooding regime, or on vegetative life form. The same Classes may appear under one or more of the Systems or Subsystems. Six Classes are based on substrate and flooding regime : (1) Rock Bottom with a substrate of bedrock, boulders, or stones ; (2) Unconsolidated Bottom with a substrate of cobbles, gravel, sand, mud, or organic material ;

(3) Rocky Shore with the same substrates as Rock Bottom ; (4) Unconsolidated Shore with the same substrates as Unconsolidated Bottom ; (5) Streambed with any of the substrates ; and (6) Reef with a substrate composed of the living and dead remains of invertebrates (corals, mollusks, or worms).

The bottom Classes, (1) and (2) above, are flooded all or most of the time and the shore Classes, (3) and (4), are exposed most of the time. The Class Streambed is restricted to channels of intermittent streams and tidal channels that are dewatered at low tide. The life form of the dominant vegetation defines the five Classes based on vegetative form : (1) Aquatic Bed, dominated by plants that grow principally on or below the surface of the water; (2) Moss-Lichen Wetland, dominated by mosses or lichens ; (3) Emergent Wetland, dominated by emergent herbaceous angiosperms ; (4) Scrub-Shrub Wetland, dominated by shrubs or small trees ; and (5) Forested Wetland, dominated by large trees.

The Dominance Type, which is named for the dominant plant or animal forms, is the lowest level of the classification hierarchy. Only examples are provided for this level ; Dominance Types must be developed by individual users of the classification.

Modifying terms applied to the Classes or Subclasses are essential for use of the system. In tidal areas, the type and duration of flooding are described by four Water Regime Modifiers : subtidal, irregularly exposed, regularly flooded, and irregularly flooded. In nontidal areas, eight Regimes are used : permanently flooded, intermittently exposed, semipermanently flooded, seasonally flooded, saturated, temporarily flooded, intermittently flooded, and artificially flooded. A hierarchical system

of Water Chemistry Modifiers, adapted from the Venice System, is used to describe the salinity of the water. Fresh waters are further divided on the basis of pH. Use of a hierarchical system of soil modifiers taken directly from U.S. soil taxonomy is also required. Special modifiers are used where appropriate : excavated, impounded, diked, partly drained, farmed, and artificial.

Regional differences important to wetland ecology are described through a regionalization that com-bines a system developed for inland areas by R. G. Bailey in 1976 with our Marine and Estuarine provinces.

The structure of the classification allows it to be used at any of several hierarchical levels. Special data required for detailed application of the system are frequently unavailable, and thus data gather-ing may be prerequisite to classification. Development of rules by the user will be required for speck map scales. Dominance Types and relationships of plant and animal communities to environmental characteristics must also be developed by users of the classification. Keys to the Systems and Classes are furnished as a guide, and numerous wetlands and deepwater habitats are illustrated and classified.

The classification system is also compared with several other systems currently in use in the United States.

The U.S. Fish and Wildlife Service conducted an inven-tory of the wetlands of the United States (Shaw and Fredine 1956) in 1954. Since then, wetlands have under-gone considerable change, both natural and man related, and their characteristics and natural values have become better defined and more widely known. During this inter-val, State and Federal legislation has been passed to protect wetlands, and some Statewide wetland surveys have been conducted.

In 1974, the U.S. Fish and Wildlife Service directed its Office of Biological Services to design and conduct a new National inventory of wetlands. Whereas the single pur-pose of the 1954 inventory was to assess the amount and types of valuable waterfowl habitat, the scope of the new project is considerably broader (Montanari and Townsend 1977). It will provide basic data on the characteristics and extent of the Nation's wetlands and deepwater habitats and should facilitate the management of these areas on a sound, multiple-use basis.

Before the 1954 inventory was begun, Martin et al.

(1953) had devised a wetland classification system to serve as a framework for the National inventory. The results of the inventory and an illustrated description of the 20 wetland types were published as U.S. Fish and Wildlife Service Circular 39 (Shaw and Fredine 1956). This cir-cular has been one of the most common and most influen-tial documents used in the continuous battle to preserve a critically valuable but rapidly diminishing National resource (Stegman 1976). However, the shortcomings of this work are well known (e.g., see Leitch 1966 ; Stewart and Kantrud 1971).

In attempting to simplify their classification, Martin et al. (1953) not only ignored ecologically critical differences, such as the distinction between fresh and mixosaline in-land wetlands but also placed dissimilar habitats, such as forests of boreal black spruce (Picea mariana) and of southern cypress-gum (Taxodium distichum-Nyssa aquatica) in the same category, with no provisions in the system for distinguishing between them. Because of the central emphasis on waterfowl habitat, far greater atten-tion was paid to vegetated areas than to nonvegetated areas. Probably the greatest single disadvantage of the Martin et al. system was the inadequate definition of types, which led to inconsistencies in application.

Numerous other classifications of wetlands and deep-water habitats have been developed (Stewart and Kan-trud 1971 ; Golet and Larson 1974 ; Jeglum et al. 1974 ;

Odum et al. 1974 ; Zoltai et al. 1975 ; Millar 1976), but most of these are regional systems and none wouldfully satisfy National needs. Because of the weaknesses inherent in Circular 39, and because wetland ecology has become significantly better understood since 1954, the U.S. Fish and Wildlife Service elected to construct a new National classification system as the first step toward a new Na-tional inventory. The new classification, presented here, has been designed to meet four long-range objectives : (1) to describe ecological units that have certain homogeneous natural attributes ; (2) to arrange these units in a system that will aid decisions about resource management ; (3) to furnish units for inventory and mapping ; and (4) to pro-vide uniformity in concepts and terminology throughout the United States.

Scientific and common names of plants (Appendix A) and animals (Appendix B) were taken from various sources cited in the text. No attempt has been made to resolve nomenclatorial problems where there is a taxonomic dispute. Many of the terms used in this classification have various meanings even in the scientific literature and in some instances our use of terms is new. We have provided a glossary (Appendix C) to guide the reader in our usage of terms.

WETLANDS AND DEEPWATER HABITATS Concepts and Definitions Marshes, swamps, and bogs have been well-known terms for centuries, but only relatively recently have attempts been made to group these landscape units under the single term "wetlands." This general term has grown out of a need to understand and describe the characteristics and values of all types of land, and to wisely and effectively manage wetland ecosystems. There is no single, correct, indisputable, ecologically sound definition for wetlands, primarily because of the diversity of wetlands and because the demarcation between dry and wet environments lies along a continuum. Because reasons or needs for defin-ing wetlands also vary, a great proliferation of definitions has arisen. The primary objective of this classification is to impose boundaries on natural ecosystems for the pur-poses of inventory, evaluation, and management.

Wetlands In general terms, wetlands are lands where saturation with water is the dominant factor determining the nature of soil development and the types of plant and animal com-munities living in the soil and on its surface. The single feature that most wetlands share is soil or substrate that is at least periodically saturated with or covered by water.

The water creates severe physiological problems for all plants and animals except those that are adapted for life in water or in saturated soil.

WETLANDS are lands transitional between terrestrial and aquatic systems where the water table is usually at or near the surface or the land is covered by shallow water.

Forpurposes ofthis classification wetlands must have one or more of the following three attributes: (1) at least periodically, the land supports predominantly hydro-phytes;' (2) the substrate is predominantly undrained hydric soil;2 and (3) the substrate is nonsoil and is saturated with water or covered by shallow water at some time during the growing season ofeach year.

The term wetland includes a variety of areas that fall into one offive categories : (1) areas with hydrophytes and hydric soils, such as those commonly known as marshes, swamps, and bogs ; (2) areas without hydrophytes but with hydric soils-for example, flats where drastic fluctuation in water level, wave action, turbidity, or high concentra-

'The U.S. Fish and Wildlife Service is preparing a list of hydro-phytes and other plants occurring in wetlands of the United States.

'The U.S. Soil Conservation Service is preparing a preliminary list of hydric soils for use in this classification system.

tion of salts may prevent the growth of hydrophytes; (3) areas with hydrophytes but nonhydric soils, such as margins of impoundments or excavations where hydro-phytes have become established but hydric soils have not yet developed; (4) areas without soils but with hydrophytes such as the seaweed-covered portion of rocky shores; and (5) wetlands without soil and without hydrophytes, such as gravel beaches or rocky shores without vegetation.

Drained hydric soils that are now incapable of support-ing hydrophytes because of a change in water regime are not considered wetlands by our definition. These drained hydric soils furnish a valuable record of historic wetlands, as well as an indication of areas that may be suitable for restoration.

Wetlands as defined here include lands that are iden-tified under other categories in some land-use classifica-tions. For example, wetlands and farmlands are not necessarily exclusive. Many areas that we define as wet-lands are farmed during dry periods, but if they are not tilled or planted to crops, a practice that destroys the natural vegetation, they will support hydrophytes.

Deepwater Habitats Limits DEEPWATER HABITATS are permanentlyflooded lands lying below the deepwater boundary of wetlands. Deep-water habitats include environments where surface water is permanent and often deep, so that water, rather than air, is the principal medium within which the dominant organisms live, whether or not they are attached to the substrate. As in wetlands, the dominant plants are hydro-phytes ; however, the substrates are considered nonsoil because the water is too deep to support emergent vegeta-tion (U.S. Soil Conservation Service, Soil Survey Staff 1975).

Wetlands and deepwater habitats are defined separately because traditionally the term wetland has not included deep permanent water ; however, both must be considered in an ecological approach to classification. We define five major Systems : Marine, Estuarine, Riverine, Lacustrine, and Palustrine. The first four of these include both wetland and deepwater habitats but the Palustrine includes only wetland habitats.

The upland limit of wetland is designated as (1) the boun-dary between land with predominantly hydrophytic cover and land with predominantly mesophytic or xerophytic cover ; (2) the boundary between soil that is predominant-ly hydric and soil that is predominantly nonhydric ; or (3) in the case of wetlands without vegetation or soil, the boundary between land that is flooded or saturated at some time during the growing season each year and land that is not.

The boundary between wetland and deepwater habitat in the Marine and Estuarine Systems coincides with the elevation of the extreme low water of spring tide ; per-manently flooded areas are considered deepwater habitats in these Systems. The boundary between wetland and deepwater habitat in the Riverine and Lacustrine Systems lies at a depth of 2 m (6.6 feet) below low water; however, if emergents, shrubs, or trees grow beyond this depth at any time, their deepwater edge is the boundary.

The 2-m lower limit for inland wetlands was selected because it represents the maximum depth to which emer-gent plants normally grow (Welch 1952 ; Zhadin and Gerd 1963 ; Sculthorpe 1967). As Daubenmire (1968:138) stated, emergents are not true aquatic plants, but are "amphib-ious," growing in both permanently flooded and wet, nonflooded soils. In their wetland classification for Canada, Zoltai et al. (1975) also included only areas with water less than 2 m deep.

THE CLASSIFICATION SYSTEM The structure of this classification is hierarchical, progressing from Systems and Subsystems, at the most general levels, to Classes, Subclasses, and Dominance Types. Figure 1 illustrates the classification structure to the class level. Table 1 lists the Classes and Subclasses for each System and Subsystem. Artificial keys to the Systems and Classes are given in Appendix E. Modifiers for water regime, water chemistry, and soils are applied to Classes, Subclasses, and Dominance Types. Special modifiers describe wetlands and deepwater habitats that have been either created or highly modified by man or beavers.

Hierarchical Structure Systems and Subsystems The term SYSTEM refers here to a complex of wetlands and deepwater habitats that share the influence of similar hydrologic, geomorphologic, chemical, or biological fac-tors. We further subdivide Systems into more specific categories called SUBSYSTEMS.

The characteristics of the five major Systems-Marine, Estuarine, Riverine, Lacustrine, and Palustrine-have been discussed at length in the scientific literature and the concepts are well recognized ; however, there is fre-quent disagreement as to which attributes should be used to bound the Systems in space. For example, both the limit of tidal influence and the limit of ocean-derived salinity have been proposed for bounding the upstream end ofthe Estuarine System (Caspers 1967). As Bormann and Likens (1969) pointed out, boundaries of ecosystems are defined to meet practical needs.

Marine System Definition. The Marine System (Fig. 2) consists of the open ocean overlying the continental shelf and its asso-ciated high-energy coastline. Marine habitats are exposed to the waves and currents of the open ocean and the water regimes are determined primarily by the ebb and flow of oceanic tides. Salinities exceed 30°loo, with little or no dilution except outside the mouths of estuaries. Shallow coastal indentations or bays without appreciable fresh-water inflow, and coasts with exposed rocky islands that provide the mainland with little or no shelter from wind and waves, are also considered part of the Marine System because they generally support typical marine biota.

Limits. The Marine System extends from the outer edge of the continental shelf shoreward to one of three lines : (1) the landward limit of tidal inundation (extreme high water of spring tides), including the splash zone from breaking waves ; (2) the seaward limit of wetland emer-gents, trees, or shrubs; or (3) the seaward limit of the Estuarine System, where this limit is determined by fac-tors other than vegetation. Deepwater habitats lying beyond the seaward limit of the Marine System are out-side the scope of this classification system.

Description. The distribution of plants and animals in the Marine System primarily reflects differences in four factors : (1) degree of exposure of the site to waves ; (2) texture and physicochemical nature of the substrate; (3) amplitude of the tides ; and (4) latitude, which governs water temperature, the intensity and duration of solar radiation, and the presence or absence of ice.

Subsystems.

Subtidal.-The substrate is continuously submerged.

Intertidal.-The substrate is exposed and flooded by tides ; includes the associated splash zone.

Classes. Rock Bottom, Unconsolidated Bottom, Aquatic Bed, Reef, Rocky Shore, and Unconsolidated Shore.

Estuarine System Definition. The Estuarine System (Fig. 3) consists of deepwater tidal habitats and adjacent tidal wetlands that are usually semienclosed by land but have open, partly obstructed, or sporadic access to the open ocean, and in which ocean water is at least occasionally diluted by fresh-water runofffrom the land. The salinity may be periodical-ly increased above that of the open ocean by evaporation.

Along some low-energy coastlines there is appreciable dilu-tion of sea water. Offshore areas with typical estuarine plants and animals, such as red mangroves (Rhizophora

Fig. 1. Classification hierarchy of wetlands and deepwater habitats, showing Systems, Subsystems, and Classes. The Palustrine System does not include deepwater habitats.

System Subsystem Class Rock Bottom Subtidal Unconsolidated Bottom Aquatic Bed Reef Marine Aquatic Bed Intertidal -

Reef Rocky Shore Unconsolidated Shore Rock Bottom Subtidal Unconsolidated Bottom Aquatic Bed Reef Estuarine Aquatic Bed Reef Streambed Intertidal Rocky Shore Unconsolidated Shore Emergent Wetland Scrub-Shrub Wetland Forested Wetland Rock Bottom Unconsolidated Bottom H

Aquatic Bed Tidal Streambed x

Rocky Shore Unconsolidated Shore W

Emergent Wetland a

Rock Bottom W

Unconsolidated Bottom WQ Lower Perennial Aquatic Bed Q

Rocky Shore z

Riverine Unconsolidated Shore Emergent Wetland Qz Rock Bottom Unconsolidated Bottom H

Upper Perennial Aquatic Bed W

Rocky Shore Unconsolidated Shore Intermittent Streambed Rock Bottom Limnetic Unconsolidated Bottom Aquatic Bed Lacustrine Rock Bottom Unconsolidated Bottom Littoral Aquatic Bed Rocky Shore Unconsolidated Shore Emergent Wetland Rock Bottom Unconsolidated Bottom Aquatic Bed Unconsolidated Shore Palustrine Moss-Lichen Wetland Emergent Wetland Scrub-Shrub Wetland Forested Wetland

Table 1. Distribution ofSubclasses within the classification hierarchy.

Class/Subclass Marine ST IT Estuarine ST IT TI System and Subsystema Riverine LP UP IN Lacustrine LM LT Palustrine Rock Bottom Bedrock X

X X

X X

X X

Rubble X

X X

X X

X X

Unconsolidated Bottom Cobble-Gravel X

X X

X X

X X

X Sand X

X X

X X

X X

X Mud X

X X

X X

X X

X Organic X

X X

X X

X Aquatic Bed Algal X

X X

X X

X X

X X

X Aquatic Moss X

X X

X X

X Rooted Vascular X

X X

X X

X X

X X

X Floating Vascular X

X X

X X

X X

X Reef Coral X

X Mollusk X

X Worm X

X X

X Streambed Bedrock X

X X

Rubble X

X X

Cobble-Gravel X

X X

Sand X

X X

Mud X

X X

Organic X

X X

Vegetated X

Rocky Shore Bedrock X

X X

X X

X Rubble X

X X

X X

X Unconsolidated Shore Cobble-Gravel X

X X

X X

X X

Sand X

X X

X X

X X

Mud X

X X

X X

X X

Organic X

X X

X X

X X

Vegetated X

X X

X X

Moss-Lichen Wetland Moss X

Lichen x

Emergent Wetland Persistent X

X Nonpersistent X

X X

X X

X Scrub-Shrub Wetland Broad-leaved Deciduous X

X Needle-leaved Deciduous X

X Broad-leaved Evergreen X

X Needle-leaved Evergreen X

X Dead X

X

mangle) and eastern oysters (Crassostrea virginica), are also included in the E stuarine System. 3 Limits. The Estuarine System extends (1) upstream and landward to where ocean-derived salts measure less than 0.5 01oo during the period of average annual low flow ; (2) to an imaginary line closing the mouth of a river, bay, or sound; and (3) to the seaward limit of wetland emergents, shrubs, or trees where they are not included in (2). The Estuarine System also includes offshore areas of contin-uously diluted sea water.

Description. The Estuarine System includes both es-tuaries and lagoons. It is more strongly influenced by its association with land than is the Marine System. In terms of wave action, estuaries are generally considered to be low-energy systems (Chapman 1977 :2).

Estuarine water regimes and water chemistry are affected by one or more of the following forces : oceanic tides, precipitation, freshwater runoff from land areas, evaporation, and wind. Estuarine salinities range from hyperhaline to oligohaline (Table 2). The salinity may be variable, as in hyperhaline lagoons (e.g., Laguna Madre, Texas) and most brackish estuaries (e.g., Chesapeake Bay, Virginia-Maryland); or it may be relatively stable, as in sheltered euhaline embayments (e.g., Chincoteague Bay, Maryland) or brackish embayments with partly obstructed access or small tidal range (e.g., Pamlico Sound, North Carolina). (For an extended discussion of estuaries and lagoons see Lauff 1967.)

Subsystems.

Subtidal.-The substrate is continuously submerged.

Intertidal.-The substrate is exposed and flooded by tides ; includes the associated splash zone.

'The Coastal Zone Management Act of 1972 defines an estuary as "that part of a river or stream or other body of water having unimpaired connection with the open sea, where the sea-water is measurably diluted with freshwater derived from land drainage." The Act further states that "the term includes estuary_

type areas ofthe Great Lakes." However, in the present system we do not consider areas of the Great Lakes as Estuarine.

aST= Subtidal, IT = Intertidal, TI = Tidal, LP = Lower Perennial, UP = Upper Perennial, IN = Intermittent, LM= Limnetic, LT= Littoral.

Classes. Rock Bottom, Unconsolidated Bottom, Aquatic

Bed, Reef, Streambed, Rocky Shore, Unconsolidated Shore, Emergent Wetland, Scrub-Shrub Wetland, and Forested Wetland.

Riverine System Definition. The Riverine System (Fig. 4) includes all wetlands and deepwater habitats contained within a chan-nel, with two exceptions : (1) wetlands dominated by trees,

shrubs, persistent emergents, emergent

mosses, or lichens, and (2) habitats with water containing ocean-derived salts in excess of 0.501oo. A channel is "an open conduit either naturally or artificially created which periodically or continuously contains moving water, or which forms a connecting link between two bodies of standing water" (Langbein and Iseri 1960 :5).

Limits. The Riverine System is bounded on the land-ward side by upland, by the channel bank (including natural and man-made levees), or by wetland dominated by trees, shrubs, persistent emergents, emergent mosses, or lichens. In braided streams, the system is bounded by the banks forming the outer limits of the depression within which the braiding occurs.

The Riverine System terminates at the downstream end where the concentration of ocean-derived salts in the water exceeds 0.5 01oo during the period of annual average low flow, or where the channel enters a lake. It terminates at the upstream end where tributary streams originate, or where the channel leaves a lake. Springs discharging into a channel are considered part of the Riverine System.

Description. Water is usually, but not always, flowing in the Riverine System. Upland islands or Palustrine wet-lands may occur in the channel, but they are not included in the Riverine System. Palustrine Moss-Lichen Wet-lands, Emergent Wetlands, Scrub-Shrub Wetlands, and Forested Wetlands may occur adjacent to the Riverine System, often on a floodplain. Many biologists have sug-gested that all the wetlands occurring on the river flood-plain should be a part of the Riverine System because they Table 1. Continued.

System and Subsystema Marine Estuarine Riverine Lacustrine Palustrine Class/Subclass ST IT ST IT TI LP UP IN LM LT Forested Wetland Broad-leaved Deciduous X

X Needle-leaved Deciduous X

X Broad-leaved Evergreen X

X Needle-leaved Evergreen X

X Dead X

X

Fig. 2. Distinguishing features and examples of habitats in the Marine System. EHWS = extreme high water of spring tides; ELWS = extreme low water of spring tides.

consider their presence to be the result of river flooding.

However, we concur with Reid and Wood (1976:72,84) who stated, "The floodplain is a flat expanse of land border-ing an old river.... Often the floodplain may take the form of a very level plain occupied by the present stream chan-nel, and it may never, or only occasionally, be flooded.

It is this subsurface water [the ground water] that con-trols to a great extent the level of lake surfaces, the flow of streams, and the extent of swamps and marshes."

Subsystems. The Riverine System is divided into four Subsystems : the Tidal, the Lower Perennial, the Upper Perennial, and the Intermittent. Each is defined in terms of water permanence, gradient, water velocity, substrate, and the extent of floodplain development. The Subsystems have characteristic flora and fauna (see Illies and Botosa-neau 1963; Hynes 1970 ; Reid and Wood 1976). All four Subsystems are not necessarily present in all rivers, and the order of occurrence may be other than that given below.

Tidal.-The gradient is low and water velocity fluctuates under tidal influence. The streambed is mainly mud with occasional patches of sand. Oxygen deficits may sometimes occur and the fauna is similar to that in the Lower Peren-nial Subsystem. The floodplain is typically well developed.

Lower Perennial.-The gradient is low and water veloc-ity is slow. There is no tidal influence, and some water flows throughout the year. The substrate consists mainly of sand and mud. Oxygen deficits may sometimes occur, the fauna is composed mostly of species that reach their maximum abundance in still water, and true planktonic organisms are common. The gradient is lower than that of the Upper Perennial Subsystem and the floodplain is well developed.

Upper Perennial.-The gradient is high and velocity of the water fast. There is no tidal influence and some water flows throughout the year. The substrate consists of rock, cobbles, or gravel with occasional patches of sand. The natural dissolved oxygen concentration is normally near saturation. The fauna is characteristic of running water, and there are few or no planktonic forms. The gradient is high compared with that of the Lower Perennial Sub-system, and there is very little floodplain development.

Intermittent.-In this Subsystem, the channel contains flowing water for only part of the year. When the water is not flowing, it may remain in isolated pools or surface water may be absent.

Seaward LieMt of Marine System -mss" UPLAND MARINE INTERTIDAL SUBTIDAL INTERTIDAL SUBTIDAL w

w w

w ea0 p

W t C

p W

p M

m M

V J 0 M Q J 1 r

p

(~

S m

v) m to ~m t!)

=

m v) fo F"

m o~

O O

O O

Z 2

2 Z

0 EHWS b

ELWS d

d d

a IRREGULARLY FLOODED b REGULARLY FLOODED c IRREGULARLY EXPOSED d SUBTIDAL

Fig. 3. Distinguishing features and examples of habitats in the Estuarine System. EHWS = extreme high water of spring tides ;

ELWS = extreme low water of spring tides.

Classes. Rock Bottom, Unconsolidated Bottom, Aquatic Bed, Streambed, Rocky Shore, Unconsolidated Shore, and Emergent Wetland (nonpersistent).

Lacustrine System Definition. The Lacustrine System (Fig. 5) includes wet-lands and deepwater habitats with all of the following characteristics : (1) situated in a topographic depression or a dammed river channel ; (2) lacking trees, shrubs, per-sistent emergents, emergent mosses or lichens with greater than 30°10 areal coverage ; and (3) total area ex-ceeds 8 ha (20 acres). Similar wetland and deepwater habitats totaling less than 8 ha are also included in the Lacustrine System if an active wave-formed or bedrock shoreline feature makes up all or part of the boundary, or if the water depth in the deepest part of the basin ex-ceeds 2 m (6.6 feet) at low water. Lacustrine waters may be tidal or nontidal, but ocean-derived salinity is always less than 0.5 0/oo.

Limits. The Lacustrine System is bounded by upland or by wetland dominated by trees, shrubs, persistent s IRREGULARLY FLOODED b REGULARLY FLOODED c IRREGULARLY EXPOSED d SUSTIDAL emergents, emergent mosses, or lichens.

Lacustrine Systems formed by damming a river channel are bounded by a contour approximating the normal spillway elevation or normal pool elevation, except where Palustrine wet-lands extend lakeward of that boundary. Where a river enters a lake, the extension of the Lacustrine shoreline forms the Riverine-Lacustrine boundary.

Description. The Lacustrine System includes perma-nently flooded lakes and reservoirs (e.g., Lake Superior),

intermittent lakes (e.g., playa lakes), and tidal lakes with ocean-derived salinities below 0.50 1oo (e.g., Grand Lake, Louisiana). Typically, there are extensive areas of deep water and there is considerable wave action. Islands of Palustrine wetland may lie within the boundaries of the Lacustrine System.

Subsystems.

Limnetic. -All deepwater habitats within the Lacus-trine System ; many small Lacustrine Systems have no Limnetic Subsystem.

Littoral.-All wetland habitats in the Lacustrine System. Extends from the shoreward boundary of the

10 Table 2. Salinity Modifiers used in this classification system.

,Coastal Modifiers are used in the Marine and Estuarine Systems.

'Inland Modifiers are used in the Riverine, Lacustrine, and Palustrine Systems.

'The term Brackish should not be used for inland wetlands or deepwater habitats.

system to a depth of 2 m (6.6 feet) below low water or to the maximum extent of nonpersistent emergents, if these grow at depths greater than 2 m.

Classes. Rock Bottom, Unconsolidated Bottom, Aquatic Bed, Rocky Shore, Unconsolidated Shore, and Emergent Wetland (nonpersistent).

Palustrine System Definition. The Palustrine System (Fig. 6) includes all nontidal wetlands dominated by trees, shrubs, persistent emergents, emergent mosses or lichens, and all such wet-lands that occur in tidal areas where salinity due to ocean-derived salts is below 0.5 0 1oo. It also includes wetlands lacking such vegetation, but with all of the following four characteristics : (1) area less than 8 ha (20 acres) ; (2) ac-tive wave-formed or bedrock shoreline features lacking ;

(3) water depth in the deepest part of basin less than 2 m at low water ; and (4) salinity due to ocean-derived salts less than 0.5 01oo.

Limits. The Palustrine System is bounded by upland or by any of the other four Systems.

Description. The Palustrine System was developed to group the vegetated wetlands traditionally called by such names as marsh, swamp, bog, fen, and prairie, which are found throughout the United States. It also includes the small, shallow, permanent or intermittent water bodies often called ponds. Palustrine wetlands may be situated shoreward of lakes, river channels, or estuaries ; on river floodplains; in isolated catchments ; or on slopes. They may also occur as islands in lakes or rivers. The erosive forces of wind and water are of minor importance except dur-ing severe floods.

The emergent vegetation adjacent to rivers and lakes is often referred to as "the shore zone" or the "zone of emergent vegetation" (Reid and Wood 1976), and is gen-erally considered separately from the river or lake. As an example, Hynes (1970:85) wrote in reference to riverine habitats, "We will not here consider the long list of emer-gent plants which may occur along the banks out of the current, as they do not belong, strictly speaking, to the running water habitat." There are often great similarities between wetlands lying adjacent to lakes or rivers and isolated wetlands of the same class in basins without open water.

Subsystems. None.

Classes. Rock Bottom, Unconsolidated Bottom, Aquatic Bed, Unconsolidated Shore, Moss-Lichen Wetland, Emer-gent Wetland, Scrub-Shrub Wetland, and Forested Wetland.

Classes, Subclasses, and Dominance Types The CLASS is the highest taxonomic unit below the Sub-system level. It describes the general appearance of the habitat in terms of either the dominant life form of the vegetation or the physiography and composition of the substrate-features that can be recognized without the aid of detailed environmental measurements. Vegetation is used at two different levels in the classification. The life forms-trees, shrubs, emergents, emergent mosses, and lichens-are used to define Classes because they are relatively easy to distinguish, do not change distribution rapidly, and have traditionally been used as criteria for classification ofwetlands. 4 Other forms of vegetation, such as submerged or floating-leaved rooted vascular plants, free-floating vascular plants, submergent mosses, and algae, though frequently more difficult to detect, are used 40ur initial attempts to use familiar terms such as marsh, swamp, bog, and meadow at the Class level were unsuccessful primarily because of wide discrepancies in the use ofthese terms in various regions of the United States. In an effort to resolve that difficulty, we based the Classes on the fundamental components (life form, water regime, substrate type, water chemistry) that give rise to such terms. We believe that this approach will greatly reduce the misunderstandings and confusion that result from the use of the familiar terms.

Coastal Modifiers,

Inland Modifiers' Salinity (parts per thousand)

Approximate specific conductance (uMhos at 25°C)

Hyperhaline Hypersaline

>40

>60,000 Euhaline Eusaline 30.0-40 45,000-60,000 Mixohaline (Brackish)

Mixosalinel 0.5-30 800-45,000 Polyhaline Polysaline 18.0-30 30,000-45,000 Mesohaline Mesosaline 5.0-18 8,000-30,000 Oligohaline Oligosaline 0.5-5 800- 8,000 Fresh Fresh

<0.5

<800

a TEMPORARILY FLOODED b SEASONALLY FLOODED c SEMIPERMANENTLY FLOODED d INTERMITTENTLY EXPOSED a PERMANENTLY FLOODED Fig. 4. Distinguishing features and examples of habitats in the Riverine System.

to define the Class Aquatic Bed. Pioneer species that brief-ly invade wetlands when conditions are favorable are treated at the Subclass level because they are transient and often not true wetland species.

Use of life forms at the Class level has two major advan-tages: (1) extensive biological knowledge is not required to distinguish between various life forms, and (2) it has been established that various life forms are easily recog-nizable on a great variety of remote sensing products (e.g.,

Radforth 1962 ; Anderson et al. 1976). If vegetation (ex-cept pioneer species) covers 30% or more of the substrate, we distinguish Classes on the basis of the life form of the plants that constitute the uppermost layer of vegetation and that possess an areal coverage 30% or greater. For example, an area with 50% areal coverage of trees over a shrub layer with a 60% areal coverage would be classified as Forested Wetland ; an area with 20% areal coverage of trees over the same (60%) shrub layer would be classified as Scrub-Shrub Wetland. When trees or shrubs alone cover less than 30% of an area but in combination cover 30% or more, the wetland is assigned to the Class Scrub-Shrub. When trees and shrubs cover less than 30%

of the area but the total cover of vegetation (except pioneer species) is 30% or greater, the wetland is assigned to the appropriate Class for the predominant life form below the shrub layer. Finer differences in life forms are recognized at the SUBCLASS level. For example, Forested Wetland is divided into the Subclasses Broad-leaved Decid-uous, Needle-leaved Deciduous, Broad-leaved Evergreen, Needle-leaved Evergreen, and Dead.

Subclasses are named on the basis of the predominant life form.

If vegetation covers less than 30% of the substrate, the physiography and composition of the substrate are the principal characteristics used to distinguish Classes. The nature of the substrate reflects regional and local varia-tions in geology and the influence ofwind, waves, and cur-rents on erosion and deposition of substrate materials.

Bottoms, Shores, and Streambeds are separated on the basis of duration of inundation. In the Riverine, Lacus-trine, and Palustrine Systems, Bottoms are submerged all or most of the time, whereas Streambeds and Shores are exposed all or most of the time. In the Marine and Estuarine

Systems, Bottoms are

Subtidal, whereas Streambeds and Shores are Intertidal. Bottoms, Shores, and Streambeds are further divided at the Class level on the basis of the important characteristic of rock versus

12 UPLAND LITTORAL Fig. 5.

LACUSTRINE unconsolidated substrate. Subclasses are based on finer distinctions in substrate material

unless, as with Streambeds and Shores, the substrate is covered by, or shaded by, an areal coverage ofpioneering vascular plants (often nonhydrophytes) of 30% or more ; the Subclass is then simply "vegetated." Further detail as to the type of vegetation must be obtained at the level of Dominance Type. Reefs are a unique class in which the substrate itself is composed primarily of living and dead animals.

Subclasses of Reefs are designated on the basis ofthe type of organism that formed the reef.

The DOMINANCE TYPE is the taxonomic category sub-ordinate to Subclass. Dominance Types are determined on the basis of dominant plant species (e.g., Jeglum et al.

1974), dominant sedentary or sessile animal species (e.g.,

Thorson 1957), or dominant plant and animal species (e.g.,

Stephenson and Stephenson 1972). A dominant plant species has traditionally meant one that has control over the community (Weaver and Clements 1938 :91), and this plant is also usually the predominant species (Cain and Castro 1959:29). When the Subclass is based on life form, we name the Dominance Type for the dominant species or combination of species (codominants) in the same layer LIMNETIC a TEMPORARILY FLOODED b SEASONALLY FLOODED c SEMIPERMANENTLY FLOODED d INTERMITTENTLY EXPOSED e PERMANENTLY FLOODED Distinguishing features and examples of habitats in the Lacustrine System.

PALUSTRINE UPLAND of vegetation used to determine the Subclass. 5 For exam-ple, a Needle-leaved Evergreen Forested Wetland with 70% areal cover of black spruce (Picea mariana) and 30%

areal cover of tamarack (Larix laricina) would be desig-nated as a Picea mariana Dominance Type. When the relative abundance of codominant species is nearly equal, the Dominance Type consists of a combination of species names. For example, an Emergent Wetland with about equal areal cover of common cattail (Typha latifolia) and hardstem bulrush (Scirpus acutus) would be designated a Typha latifolia-Scirpus acutus Dominance Type.

When the Subclass is based on substrate material, the Dominance Type is named for the predominant plant or SPercent areal cover is seldom measured in the application ofthis system, but the term must be defined in terms of area. We sug-gest 2 m2 for herbaceous and moss layers, 16 m 2 for shrub layers, and 100 m2 for tree layers (Mueller-Dombois and Ellen-berg 1974:74). When percent areal coveris the key for establishing boundaries between units of the classification, it may occasion-ally be necessary to measure cover on plots, in order to maintain uniformity ofocular estimates made in the field or interpretations made from aerial photographs.

UPLAND PALUSTRINE UPLAND PALUSTRINE UPLAND f

Seepage Zone Rock Bottom 0Z W

W sedentary or sessile macroinvertebrate species, without regard for life form. In the Marine and Estuarine Systems, sponges, alcyonarians, mollusks, crustaceans, worms, asci-dians, and echinoderms may all be part of the community represented by the Macoma balthica Dominance Type.

Sometimes it is necessary to designate two or more co-dominant species as a Dominance Type. Thorson (1957) recommended guidelines and suggested definitions for establishing community types and dominants on level bottoms.

Definition. The Class Rock Bottom includes all wetlands and deepwater habitats with substrates having an areal cover of stones, boulders, or bedrock 75% or greater and vegetative cover of less than 30%. Water regimes are restricted to subtidal, permanently flooded, intermittently exposed, and semipermanently flooded.

Description. The rock substrate of the rocky benthic or bottom zone is one of the most important factors in deter-mining the abundance, variety, and distribution of organ-isms. The stability ofthe bottom allows a rich assemblage I 4 W., e s--,--*

0WH O O O H Z O O m 0Z b

b a TEMPORARILY FLOODED b SEASONALLY FLOODED c SEMIPERMANENTLY FLOODED d INTERMITTENTLY EXPOSED e PERMANENTLY FLOODED f SATURATED PALUSTRINE UPLAND 0W m

U f-<

a 0Z J

F-W3 ZW W

W h-ZW I.-co d1¢WaZOZ m

Fig. 6. Distinguishing features and examples of habitats in the Palustrine System.

0Z J

F-W ZW0¢W W

I.-ZW Wa 13 HIGH WATER AVERAGE WATER LOW WATER

ofplants and animals to develop. Rock Bottoms are usually high-energy habitats with well-aerated waters. Tempera-ture, salinity, current, and light penetration are also im-portant factors in determining the composition ofthe ben-thic community. Animals that live on the rocky surface are generally firmly attached by hooking or sucking devices, although they may occasionally move about over the substrate. Some may be permanently attached by cement. A few animals hide in rocky crevices and under rocks, some move rapidly enough to avoid being swept away, and others burrow into the finer substrates between boulders. Plants are also firmly attached (e.g., by hold-fasts), and in the Riverine System both plants and animals are commonly streamlined or flattened in response to high water velocities.

Subclasses and Dominance Types.

Bedrock.-Bottoms in which bedrock covers 75% or more of the surface.

Rubble.-Bottoms with less than 75% areal cover of bedrock, but stones and boulders alone, or in combination with bedrock, cover 75% or more of the surface.

Examples of Dominance Types for these two Subclasses in the Marine and E stuarine Systems are the encrusting m

J H 0

0 H Z

¢2 Z

W Z

W W y

3 H J

W J

y m

H

¢ H

N w

W Z ¢

¢ 3

OW W W 0

0¢ a

14 sponges Hippospongia, the tunicate Cnemidocarpa, the sea urchin Strongylocentrotus, the sea star Pisaster, the sea whip Muricea, and the American lobster Homarus americanus. Examples of Lacustrine, Palustrine, and Riverine Dominance Types are the freshwater sponges Spongilla and Heteromeyenia, the pond snail Lymnaea, the mayfly Ephemerella, various midges of the Chirono-midae, the caddisfly Hydropsyche, the leech Helobdella, the riffle beetle Psephenus, the chironomid midge Eukief-feriella, the crayfish Procambarus, and the black fly Simulium.

Dominance Types for Rock Bottoms in the Marine and Estuarine Systems were taken primarily from Smith (1964) and Ricketts and Calvin (1968), and those for Rock Bottoms in the Lacustrine, Riverine, and Palustrine Systems from Krecker and Lancaster (1933), Stehr and Branson (1938), Ward and Whipple (1959), Clarke (1973),

Hart and Fuller (1974), Ward (1975), Slack et al. (1977),

and Pennak (1978).

Unconsolidated Bottom Definition. The Class Unconsolidated Bottom includes all wetland and deepwater habitats with at least 25°70 cover of particles smaller than stones, and a vegetative cover less than 30°70. Water regimes are restricted to subtidal, permanently flooded, intermittently exposed, and semi-permanently flooded.

Description. Unconsolidated Bottoms are characterized by the lack of large stable surfaces for plant and animal attachment. They are usually found in areas with lower energy than Rock Bottoms, and may be very unstable. Ex-posure to wave and current action, temperature, salinity, and light penetration determines the composition and distribution of organisms.

Most macroalgae attach to the substrate by means of basal hold-fast cells or discs ; in sand and mud, however, algae penetrate the substrate and higher plants can suc-cessfully root if wave action and currents are not too strong. Most animals in unconsolidated sediments live within the substrate, e.g., Macoma and the amphipod Melita. Some, such as the polychaete worm Chaetopterus, maintain permanent burrows, and others may live on the surface, especially in coarse-grained sediments.

In the Marine and Estuarine Systems, Unconsolidated Bottom communities are relatively stable. They vary from the Arctic to the tropics, depending largely on temper-ature, and from the open ocean to the upper end of the estuary, depending on salinity. Thorson (1957) summarized and described characteristic types of level-bottom com-munities in detail.

In the Riverine System, the substrate type is largely determined by current velocity, and plants and animals exhibit a high degree of morphologic and behavioral adap-tation to flowing water. Certain species are confined to specific substrates and some are at least more abundant in one type of substrate than in others. According to Hynes (1970:208), "The larger the stones, and hence the more complex the substratum, the more diverse is the inverte-brate fauna." In the Lacustrine and Palustrine Systems, there is usually a high correlation, within a given water body, between the nature of the substrate and the number of species and individuals. For example, in the profundal bottom of eutrophic lakes where light is absent, oxygen content is low, and carbon dioxide concentration is high, the sediments are ooze-like organic materials and species diversity is low. Each substrate type typically supports a relatively distinct community of organisms (Reid and Wood 1976:262).

Subclasses and Dominance Types.

Cobble-Gravel.-The unconsolidated particles smaller than stones are predominantly cobble and gravel, although finer sediments may be intermixed. Examples of Domi-nance Types for the Marine and Estuarine Systems are the mussels Modiolus and Mytilus, the brittle star Am-phipholis, the soft-shell clam Mya, and the Venus clam Saxidomus. Examples for the Lacustrine, Palustrine, and Riverine Systems are the midge Diamesa, stonefly-midge Nemoura-Eukiefferiella (Slack et al. 1977), chironomid midge-caddisfly-snail Chironomus-Hydropsyche-Physa (Krecker and Lancaster 1933), the pond snail Lymnaea, the mayfly Baetis, the freshwater sponge Eunapius, the oligochaete worm Lumbriculus, the scud Gammarus, and the freshwater mollusks Anodonta,

Elliptio, and Lampsilis.

Sand.-The unconsolidated particles smaller than stones are predominantly sand, although finer or coarser sediments may be intermixed. Examples of Dominance Types in the Marine and Estuarine Systems are the wedge shell Donax, the scallop Pecten, the tellin shell Tellina, the heart urchin Echinocardium, the lugworm Arenicola, the sand dollar Dendraster, and the sea pansy Renilla. Ex-amples for the Lacustrine, Palustrine, and Riverine Systems are the snail Physa, the scud Gammarus, the oligochaete worm Limnodrilus, the mayfly Ephemerella, the freshwater mollusks Elliptio and Anodonta, and the fingernail clam Sphaerium.

Mud.-The unconsolidated particles smaller than stones are predominantly silt and clay, although coarser sediments or organic material may be intermixed. Organ isms living in mud must be able to adapt to low oxygen concentrations. Examples of Dominance Types for the Marine and Estuarine Systems include the terebellid worm Amphitrite, the boring clam Platyodon, the deep-sea scallop Placopecten, the quahogMercenaria, the macoma Macoma, the echiurid worm Urechis, the mud snail Nassarius, and the sea cucumber Thyone. Examples of Dominance Types for the Lacustrine, Palustrine, and Riverine Systems are the sewage worm Tubifex, fresh-water mollusks Anodonta, Anodontoides, and Elliptio, the fingernail clams Pisidium and Sphaerium, and the midge Chironomus.

Organic.-The unconsolidated material smaller than stones is predominantly organic. The number of species is limited and faunal productivity is very low (Welch 1952).

Examples of Dominance Types for Estuarine and Marine Systems are the soft-shell clam Mya, the false angel wing Petricola pholadiformis, the clam worm Nereis, and the mud snail Nassarius. Examples for the Lacustrine, Palus-trine, and Riverine Systems are the sewage worm Tubifex, the snail Physa, the harpacticoid copepod Canthocamptus, and the oligochaete worm Limnodrilus.

Dominance Types for Unconsolidated Bottoms in the Marine and Estuarine Systems were taken predominant-ly from Miner (1950), Smith (1964), Abbott (1968), and Ricketts and Calvin (1968). Dominance Types for Uncon-solidated Bottoms in the Lacustrine, Riverine, and Palus-trine Systems were taken predominantly from Krecker and Lancaster (1933), Stehr and Branson (1938), Johnson (1970), Brinkhurst and Jamieson (1972), Clarke (1973),

Hart and Fuller (1974), Ward (1975), and Pennak (1978).

Aquatic Bed Definition. The Class Aquatic Bed includes wetlands and deepwater habitats dominated by plants that grow principally on or below the surface of the water for most of the growing season in most years. Water regimes in-clude subtidal, irregularly exposed, regularly flooded, permanently flooded, intermittently exposed, semiperm-anently flooded, and seasonally flooded.

Description. Aquatic Beds represent a diverse group of plant communities that requires surface water for opti-mum growth and reproduction. They are best developed in relatively permanent water or under conditions of re-peated flooding. The plants are either attached to the substrate or float freely in the water above the bottom or on the surface.

Subclasses and Dominance Types.

Algal.-Algal Beds are widespread and diverse in the Marine and Estuarine Systems, where they occupy sub-strates characterized by a wide range of sediment depths and textures. They occur in both the Subtidal and Inter-tidal Subsystems and may grow to depths of 30 m (98 feet).

Coastal Algal Beds are most luxuriant along the rocky shores of the Northeast and West. Kelp (Macrocystis) beds are especially well developed on the rocky substrates of the Pacific Coast. Dominance Types such as the rockweeds Fucus and Ascophyllum and the kelp Laminaria are com-mon along both coasts. In tropical regions, green algae, including forms containing calcareous particles, are more characteristic; Halimeda and Penicillus are common ex-amples. The red alga Laurencia, and the green algae Caulerpa, Enteromorpha, and Ulva are also common Estuarine and Marine dominance types ; Enteromorpha and Ulva are tolerant of fresh water and flourish near the upper end of some estuaries. The stonewort Chara is also found in estuaries.

15 Inland, the stoneworts Chara, Nitella, and Tolypella are examples of algae that look much like vascular plants and may grow in similar situations. However, meadows of Chara may be found in Lacustrine water as deep as 40 m (131 feet) (Zhadin and Gerd 1963), where hydrostatic pressure limits the survival of vascular submergents (phanaerogams) (Welch 1952). Other algae bearing less resemblance to vascular plants are also common. Mats of filamentous algae may cover the bottom in dense blankets, may rise to the surface under certain conditions, or may become stranded on Unconsolidated or Rocky Shores.

Aquatic Moss. -Aquatic mosses are far less abundant than algae or vascular plants. They occur primarily in the Riverine System and in permanently flooded and inter-mittently exposed parts of some Lacustrine systems. The most important Dominance Types include genera such as Fissidens, Drepanocladus, and Fontinalis. Fontinalis may grow to depths as great as 120 m (394 feet) (Hutchinson 1975). For simplicity, aquatic liverworts of the genusMar-supella are included in this Subclass.

Rooted Vascular.-Rooted Vascular Beds include a large array of vascular species in the Marine and Estu-arine Systems. They have been referred to by others as temperate grass flats (Phillips 1974); tropical marine meadows (Odum 1974) ; and eelgrass beds, turtlegrass beds, and seagrass beds (Akins and Jefferson 1973 ;

Eleuterius 1973 ; Phillips 1974). The greatest number of species occur in shallow, clear tropical, or subtropical waters of moderate current strength in the Caribbean and along the Florida and Gulf Coasts. Principal Dominance Types in these areas include turtle grass (Thalassic testu-dinum), shoalgrass (Halodule wrightii), manatee grass (Cymodoceafliformis), widgeon grass (Ruppia maritima),

sea grasses (Halophila spp.), and wild celery (Vallisneria americana).

Five major vascular species dominate along the tem-perate coasts of North America : shoalgrass, surf grasses (Phyllospadix scouleri, P. torreyi), widgeon grass, and eel-grass (Zostera marina). Eelgrass beds have the most ex-tensive distribution, but they are limited primarily to the more sheltered estuarine environment. In the lower salin-ity zones of estuaries, stands of widgeon grass, pondweed (Potamogeton), and wild celery often occur, along with naiads (Najas) and water milfoil (Myriophyllum).

In the Riverine, Lacustrine, and Palustrine Systems, rooted vascular aquatic plants occur at all depths within the photic zone. They often occur in sheltered areas where there is little water movement (Wetzel 1975) ; however, they also occur in the flowing water of the Riverine System, where they may be streamlined or flattened in response to high water velocities. Typical inland genera include pondweds, horned pondweed (Zannichellia palustris), ditch grasses (Ruppia), wild celery, and water-weed (Elodea). The riverweed (Podostemum ceratophyl-lum) is included in this class despite its lack of truly recognizable roots (Sculthorpe 1967).

16 Some of the rooted vascular species are characterized by floating leaves. Typical dominants include water lilies (Nymphaea, Nuphar), floating-leafpondweed (Potamoge-ton natans), and water shield (Brasenia schreberi). Plants such as yellow water lily (Nuphar luteum) and water smartweed (Polygonum amphibium), which may stand erect above the water surface or substrate, may be con-sidered either emergents or rooted vascular aquatic plants, depending on the life form adopted at a particular site.

Floating Vascular.-Beds of floating vascular plants occur mainly in the Lacustrine, Palustrine, and Riverine Systems and in the fresher waters of the Estuarine Sys-tem. The plants float freely either in the water or on its surface. Dominant plants that float on the surface include the duckweeds (Lemna, Spirodela), water lettuce (Pistia stratiotes), water hyacinth (Eichhornia crassipes), water nut (Trapa natans), water ferns (Salvinia spp.), and mos-quito ferns (Azolla). These plants are found primarily in protected portions of slow-flowing rivers and in the Lacustrine and Palustrine Systems. They are easily moved about by wind or water currents and cover a large area of water in some parts of the country, particularly the Southeast. Dominance Types for beds floating below the surface include bladderworts (Utricularia),

coontails (Ceratophyllum), and watermeals (Wolffia) (Sculthorpe 1967 ; Hutchinson 1975).

Reef Definition. The Class Reef includes ridge-like or mound-like structures formed by the colonization and growth of sedentary invertebrates. Water regimes are restricted to

subtidal, irregularly exposed, regularly flooded, and irregularly flooded.

Description. Reefs are characterized by their elevation above the surrounding substrate and their interference with normal wave flow ; they are primarily subtidal, but parts of some reefs may be intertidal as well. Although corals, oysters, and tube worms are the most visible organisms and are mainly responsible for reef formation, other mollusks, foraminifera, coralline algae, and other forms of life also contribute substantially to reef growth.

Frequently, reefs contain far more dead skeletal material and shell fragments than living matter.

Subclasses and Dominance Types.

Coral.-Coral Reefs are widely distributed in shallow waters of warm seas, in Hawaii, Puerto Rico, the Virgin Islands, and southern Florida. They were characterized by Odum (1971) as stable, well-adapted, highly diverse, and highly productive ecosystems with a great degree of internal symbiosis. Coral Reefs lie almost entirely within the Subtidal Subsystem of the Marine System, although the upper part of certain Reefs may be exposed. Examples of Dominance Types are the corals Porites, Acropora, and Montipora. The distribution of these types reflects prim-arily their elevation, wave exposure, the age of the Reef, and its exposure to waves.

Mollusk.-This Subclass occurs in both the Intertidal and Subtidal Subsystems of the Estuarine System. These Reefs are found on the Pacific, Atlantic, and Gulf Coasts and in Hawaii and the Caribbean. Mollusk Reefs may become extensive, affording a substrate for sedentary and boring organisms and a shelter for many others. Reef mollusks are adapted to great variations in water level, salinity, and temperature, and these same factors control their distribution. Examples of Dominance Types for this Subclass are the oysters Ostrea and Crassostrea (Smith 1964 ; Abbott 1968 ; Ricketts and Calvin 1968).

Worm.-Worm Reefs are constructed by large col-onies of Sabellariid worms living in individual tubes con-structed from cemented sand grains. Although they do not support as diverse a biota as do Coral and Mollusk Reefs, they provide a distinct habitat which may cover large areas. Worm Reefs are generally confined to tropical waters, and are most common along the coasts ofFlorida, Puerto Rico, and the Virgin Islands. They occur in both the Intertidal and Subtidal Systems of the Marine and Estuarine Systems where the salinity approximates that of sea water. The reefworm Sabellaria is an example of a Dominance Type for this Subclass (Ricketts and Calvin 1968).

Streambed Definition. The Class Streambed includes all wetland contained within the Intermittent Subsystem of the River-ine System and all channels of the Estuarine System or of the Tidal Subsystem of the Riverine System that are completely dewatered at low tide. Water regimes are restricted to irregularly exposed, regularly flooded, irreg-ularly flooded, seasonally flooded, temporarily flooded, and intermittently flooded.

Description. Streambeds vary greatly in substrate and form depending on the gradient of the channel, the veloc-ity of the water, and the sediment load. The substrate material frequently changes abruptly between riffles and pools, and complex patterns ofbars may form on the con-vex side of single channels or be included as islands within the bed of braided streams (Crickmay 1974). In mountain-ous areas the entire channel may be cut through bedrock.

In most cases streambeds are not vegetated because of the scouring effect of moving water, but, like Uncon-solidated Shores, they may be colonized by "pioneering" annuals or perennials during periods of low flow or they may have perennial emergents and shrubs that are too scattered to qualify the area for classification as Emer-gent Wetland or Scrub-Shrub Wetland.

Subclasses and Dominance Types.

Bedrock.-This Subclass is characterized by a bedrock substrate covering 75% or more of the stream channel.

It occurs most commonly in the Riverine System in high mountain areas or in glaciated areas where bedrock is ex-posed. Examples of Dominance Types are the mollusk An-cylus, the oligochaete worm Limnodrilus, the snail Physa, the fingernail clam Pisidium, and the mayflies Caenis and Ephemerella.

Rubble.-This Subclass is characterized by stones, boulders, and bedrock that in combination cover more than 75% of the channel. Like Bedrock Streambeds, Rubble Streambeds are most common in mountainous areas and the dominant organisms are similar to those of Bedrock and are often forms capable of attachment to rocks in flow-ing water.

Cobble-Gravel.-In this Subclass at least 25% of the substrate is covered by unconsolidated particles smaller than stones; cobbles or gravel predominate. The Subclass occurs in riffle areas or in the channels ofbraided streams.

Examples of Dominance Types in the Intermittent Subsys-tem of the Riverine System are the snail Physa, the oligo-chaete worm Limnodrilus, the mayfly Caenis, the midge Chironomus, and the mosquito Anopheles. Examples of Dominance Types in the Estuarine System or Tidal Sub-system of the Riverine System are the mussels Modiolus and Mytilus.

Sand.-In this Subclass, sand-sized particles predom-inate among the particles smaller than stones. Sand Streambed often contains bars and beaches interspersed with Mud Streambed or it may be interspersed with Cobble-Gravel Streambed in areas of fast flow or heavy sediment load. Examples of Dominance Types in the Riverine System are the scud Gammarus, the snails Physa and Lymnaea, and the midge Chironomus; in the Estuarine System the ghost shrimp Callianassa is a com-mon Dominance Type.

Mud.-In this Subclass, the particles smaller than stones are chiefly silt or clay. Mud Streambeds are com-mon in arid areas where intermittent flow is character istic of streams oflow gradient. Such species as tamarisk (Tamarix gallica) may occur, but are not dense enough to qualify the area for classification as Scrub-Shrub Wetland. Mud Streambeds are also common in the Estu-arine System and the Tidal Subsystem of the Riverine System. Examples of Dominance Types for Mud Stream-beds include the crayfish Procambarus, the pouch snail Aplexa, the fly Tabanus, the snail Lymnaea, the finger-nail clam Sphaerium, and (in the Estuarine System) the mud snail Nassarius.

Organic. -This Subclass is characterized by channels formed in peat or muck. Organic Streambeds are common in the small creeks draining Estuarine Emergent Wet lands with organic soils. Examples of Dominance Types are the mussel Modiolus in the Estuarine System and the oligochaete worm Limnodrilus in the Riverine System.

Vegetated.-These streambeds are exposed long enough to be colonized by herbaceous annuals or seedling herbaceous perennials (pioneer plants). This vegetation, 17 unlike that of Emergent Wetlands, is usually killed by rising water levels or sudden flooding. A typical Domi-nance Type is Panicum capillare.

Dominance Types for Streambeds in the Estuarine Sys-tem were taken primarily from Smith (1964), Abbott (1968), and Ricketts and Calvin (1968) and those for streambeds in the Riverine System from Krecker and Lan-caster (1933), Stehr and Branson (1938), van der Schalie (1948), Kenk (1949), Cummins et al. (1964), Clarke (1973),

and Ward (1975).

Rocky Shore Definition. The Class Rocky Shore includes wetland en-vironments characterized by bedrock, stones, or boulders which singly or in combination have an areal cover of 75%

or more and an areal coverage by vegetation of less than 30%. Water regimes are restricted to irregularly exposed, regularly flooded, irregularly flooded, seasonally flooded, temporarily flooded, and intermittently flooded.

Description. In Marine and Estuarine Systems, Rocky Shores are generally high-energy habitats which lie ex-posed as a result of continuous erosion by wind-driven waves or strong currents. The substrate is stable enough to permit the attachment and growth of sessile or seden-tary invertebrates and attached algae or lichens. Rocky Shores usually display a vertical zonation that is a func-tion of tidal range, wave action, and degree of exposure to the sun. In the Lacustrine and Riverine Systems, Rocky Shores support sparse plant and animal communities.

Subclasses and Dominance Types.

Bedrock.-These wetlands have bedrock covering 75%

or more of the surface and less than 30% areal coverage of macrophytes.

Rubble.-These wetlands have less than 75% areal cover of bedrock, but stones and boulders alone or in com-bination with bedrock cover 75% or more of the area. The areal coverage of macrophytes is less than 30%.

Communities or zones of Marine and Estuarine Rocky Shores have been widely studied (Lewis 1964 ; Ricketts and Calvin 1968; Stephenson and Stephenson 1972). Each zone supports a rich assemblage of invertebrates and algae or lichens or both. Dominance Types of the Rocky Shores often can be characterized by one or two dominant genera from these zones.

The uppermost zone (here termed the littorine-lichen zone) is dominated by periwinkles (Littorina andNerita) and lichens. This zone frequently takes on a dark, or even black appearance, although abundant lichens may lend a colorful tone. These organisms are rarely submerged, but are kept moist by sea spray. Frequently this habitat is invaded from the landward side by semimarine genera such as the slater Ligia.

The next lower zone (the balanoid zone) is commonly dominated by mollusks, green algae, and barnacles of the balanoid group. The zone appears white. Dominance Types

18 such as the barnacles Balanus, Chthamalus, and Tetra-clita may form an almost pure sheet, or these animals may be interspersed with mollusks, tube worms, and algae such as Pelvetia, Enteromorpha, and Ulva.

The transition between the littorine-lichen and balanoid zones is frequently marked by the replacement of the periwinkles with limpets such as Acmaea and Siphonaria.

The limpet band approximates the upper limit of the regularly flooded intertidal zone.

In the middle and lower intertidal areas, which are flooded and exposed by tides at least once daily, lie a number of other communities which can be characterized by dominant genera. Mytilus and gooseneck barnacles (Pollicipes) form communities exposed to strong wave action. Aquatic Beds dominated byFucus andLaminaria lie slightly lower, just above those dominated by coralline algae (Lithothamnion). The Laminaria Dominance Type approximates the lower end of the Intertidal Subsystem ;

it is generally exposed at least once daily. The Lithotham-nion Dominance Type forms the transition to the Subtidal Subsystem and is exposed only irregularly.

In the Palustrine, Riverine, and Lacustrine Systems various species of lichens such as Verrucaria spp. and Der-matocarpon fluviatile, as well as blue-green algae, fre-quently form characteristic zones on Rocky Shores. The distribution of these species depends on the duration of flooding or wetting by spray and is similar to the zona-tion of species in the Marine and Estuarine Systems (Hut-chinson 1975). Though less abundant than lichens, aquatic liverworts such as Marsupella emarginata var. aquatica or mosses such as Fissidens Julianus are found on the Rocky Shores of lakes and rivers. Ifaquatic liverworts or mosses cover 30% or more of the substrate, they should be placed in the Class Aquatic Bed. Other examples of Rocky Shore Dominance Types are the caddisfly Hydro-psyche and the fingernail clam Pisidium.

Unconsolidated Shore Definition. The Class Unconsolidated Shore includes all wetland habitats having three characteristics : (1) uncon-solidated substrates with less than 75% areal cover of stones, boulders, or bedrock ; (2) less than 30% areal cover of vegetation other than pioneering plants ; and (3) any of the following water regimes : irregularly exposed, regularly flooded, irregularly flooded, seasonally flooded, temporarily flooded, intermittently flooded, saturated, or artificially flooded. Intermittent or intertidal channels of the Riverine System and intertidal channels of the Estu-arine System are classified as Streambed.

Description. Unconsolidated Shores are characterized by substrates lacking vegetation except for pioneering plants that become established during brief periods when growing conditions are favorable. Erosion and deposition by waves and currents produce a number of landforms such as beaches, bars, and flats, all of which are included in this Class. Unconsolidated Shores are found adjacent to Unconsolidated Bottoms in all Systems ; in the Palus-trine and Lacustrine Systems, the Class may occupy the entire basin. As in Unconsolidated Bottoms, the particle size of the substrate and the water regime are the impor-tant factors determining the types of plant and animal communities present. Different substrates usually support characteristic invertebrate fauna. Faunal distribution is controlled by waves, currents, interstitial moisture, salin-ity, and grain size (Hedgpeth 1957 ; Ranwell 1972 ; Riedl and McMahan 1974).

Subclasses and Dominance Types.

Cobble-Gravel.-The unconsolidated particles smaller than stones are predominantly cobble and gravel. Shell fragments, sand, and silt often fill the spaces between the larger particles. Stones and boulders may be found scat-tered on some Cobble-Gravel Shores. In areas of strong wave and current action these shores take the form of beaches or bars, but occasionally they form extensive flats.

Examples of Dominance Types in the Marine and Estu-arine Systems are: the acorn barnacle Balanus, the limpet Patella, the periwinkle Littorina, the rock shell Thais, the mussels Mytilus and Modiolus, and the Venus clam Sax-idomus. In the Lacustrine, Palustrine, and Riverine Sys-tems examples of Dominance Types are the freshwater mollusk Elliptio, the snails Lymnaea and Physa, the toad bug Gelastocoris, the leech Erpodella, and the springtail Agrenia.

Sand.-The unconsolidated particles smaller than stones are predominantly sand which may be either cal-careous or terrigenous in origin. They are prominent features of the Marine, Estuarine, Riverine, and Lacus-trine Systems where the substrate material is exposed to the sorting and washing action of waves. Examples of Dominance Types in the Marine and Estuarine Systems are the wedge shell Donax, the soft-shell clam Mya, the quahog Mercenaria, the olive shell Oliva, the blood worm Euzonus, the beach hopper Orchestia, the pismo clam Tivela stultorum, the mole crab Emerita, and the lugworm Arenicola. Examples ofDominance Types in the Riverine, Lacustrine, and Palustrine Systems are the copepods Parastenocaris and Phyllognathopus, the oligochaete worm Pristina, the freshwater mollusks Anodonta and

Elliptio, and the fingernail clams Pisidium and Sphaerium.

Mud.-The unconsolidated particles smaller than stones are predominantly silt and clay. Anaerobic condi-tions often exist below the surface. Mud Shores have a higher organic content than Cobble-Gravel or Sand Shores. They are typically found in areas of minor wave action. They tend to have little slope and are frequently called flats. Mud Shores support diverse populations of tube-dwelling and burrowing invertebrates that include worms, clams, and crustaceans (Gray 1974). They are com-

monly colonized by algae and diatoms which may form a crust or mat.

Irregularly flooded Mud Shores in the Estuarine System have been called salt flats, pans, or pannes. They are typically high in salinity and are usually surrounded by, or lie on the landward side of, Emergent Wetland (Mar-tin et al. 1953, Type 15). In many arid areas, Palustrine and Lacustrine Mud Shores are encrusted or saturated with salt. Martin et al. (1953) called these habitats inland saline flats (Type 9) ; they are also called alkali flats, salt flats, and salt pans. Mud Shores may also result from removal of vegetation by man, animals, or fire, or from the discharge of thermal waters or pollutants.

Examples of Dominance Types in the Marine and Estu-arine Systems include the fiddler crab Uca, the ghost shrimp Callianassa, the mud snails Nassarius and Macoma, the clam worm Nereis, the sea anemone Cerian-thus, and the sea,cucumber Thyone. In the Lacustrine, Palustrine, and Riverine Systems, examples of Dominance Types are the fingernail clam Pisidium, the snails Aplexa and Lymnaea, the crayfish Procambarus, the harpacticoid copepods Canthocamptus andBryocamptus, the fingernail clam Sphaerium, the freshwater mollusk Elliptio, the shore bug Saldula, the isopod Asellus, the crayfish Cam-barus, and the mayfly Tortopus.

Organic.-The unconsolidated material smaller than stones is predominantly organic soils of formerly vege-tated wetlands. In the Marine and Estuarine Systems, Organic Shores are often dominated by microinvertebrates such as foraminifera, and by Nassarius, Littorina, Uca, Modiolus, Mya, Nereis, and the false angel wing Petricola pholadiformis. In the Lacustrine, Palustrine, and River-ine Systems, examples of Dominance Types are Cantho-camptus, Bryocamptus, Chironomus, and the backswim-mer Notonecta.

Vegetated.-Some nontidal shores are exposed for a sufficient period to be colonized by herbaceous annuals or seedling herbaceous perennials (pioneer plants). This vegetation, unlike that of Emergent Wetlands, is usually killed by rising water levels and may be gone before the beginning of the next growing season. Many of the pioneer species are not hydrophytes but are weedy mesophytes that cannot tolerate wet soil or flooding. Examples of Dominance Types in the Palustrine, Riverine, and Lacus-trine Systems are cocklebur (Xanthium strumarium) and barnyard grass (Echinochloa crusgalli).

Dominance Types for Unconsolidated Shores in the Mar-ine and Estuarine Systems were taken primarily from Smith (1964), Morris (1966), Abbott (1968), Ricketts and Calvin (1968), and Gosner (1971). Dominance Types for Unconsolidated Shores in the Lacustrine, Riverine, and Palustrine Systems were taken primarily from Stehr and Branson (1938), Kenk (1949), Ward and Whipple (1959),

Cummins et al. (1964), Johnson (1970), Ingram (1971),

Clarke (1973), and Hart and Fuller (1974).

Moss-Lichen Wetland 19 Definition. The Moss-Lichen Wetland Class includes areas where mosses or lichens cover substrates other than rock and where emergents, shrubs, or trees make up less than 3007o of the areal cover. The only water regime is saturated.

Description. Mosses and lichens are important compo-nents ofthe flora in many wetlands, especially in the north, but these plants usually form a ground cover under a domi-nant layer of trees, shrubs, or emergents. In some in-stances higher plants are uncommon and mosses or lichens dominate the flora. Such Moss-Lichen Wetlands are not common, even in the northern United States where they occur most frequently.

Subclasses and Dominance Types.

Moss.-Moss Wetlands are most abundant in the far north. Areas covered with peat mosses (Sphagnum spp.)

are usually called bogs (Golet and Larson 1974 ; Jeglum et al. 1974 ; Zoltai et al. 1975), whether Sphagnum or higher plants are dominant. In Alaska, Drepanocladus and the liverwort Chiloscyphusfragilis may dominate shallow pools with impermanent water; peat moss and other mosses (Campylium stellatum, Aulacomnium palustre, and Oncophorus wahlenbergii) are typical of wet soil in this region (Britton 1957 ; Drury 1962).

Lichen.-Lichen Wetlands are also a northern Subclass. Reindeer moss (Cladina rangiferina) forms the most important Dominance Type. Pollett and Bridgewater (1973) described areas with mosses and lichens as bogs or fens, the distinction being based on the availability of nutrients and the particular plant species present. The presence of Lichen Wetlands has been noted in the Hud-son Bay Lowlands (Sjors 1959) and in Ontario (Jeglum et al. 1974).

Emergent Wetland Definition. The Emergent Wetland Class is charac-terized by erect, rooted, herbaceous hydrophytes, ex-cluding mosses and lichens. This vegetation is present for most of the growing season in most years. These wetlands are usually dominated by perennial plants. All water regimes are included except subtidal and irregularly exposed.

Description. In areas with relatively stable climatic con-ditions, Emergent Wetlands maintain the same appear-ance year after year. In other areas, such as the prairies of the central United States, violent climatic fluctuations cause them to revert to an open water phase in some years (Stewart and Kantrud 1972). Emergent Wetlands are found throughout the United States and occur in all Systems except the Marine. Emergent Wetlands are known by many names, including marsh, meadow, fen, prairie pothole, and slough. Areas that are dominated by

20 pioneer plants which become established during periods of low water are not Emergent Wetlands and should be classified as Vegetated Unconsolidated Shores or Vege-tated Streambeds.

Subclasses and Dominance Types.

Persistent.-Persistent Emergent Wetlands are domi-nated by species that normally remain standing at least until the beginning of the next growing season. This Subclass is found only in the Estuarine and Palustrine Systems.

Persistent Emergent Wetlands dominated by saltmarsh cordgrass (Spartina alternifora), saltmeadow cordgrass (S. patens), big cordgrass (S. cynosuroides), needlerush (Juncos roemerianus),

narrow-leaved cattail (Typha angustifolia), and southern wild rice (Zizaniopsis miliacea) are major components of the Estuarine systems of the Atlantic and Gulf Coasts of the United States. On the Pacific Coast, common pickleweed (Salicornia virginica),

sea blite (Suaeda californica), arrow grass (Triglochin maritimum), and California cordgrass (Spartinafoliosa) are common dominants.

Palustrine Persistent Emergent Wetlands contain avast array of grasslike plants such as cattails (Typha spp.),

bulrushes (Scirpus spp.), saw grass (Cladium jamaicense),

sedges (Carex spp.) ; and true grasses such as reed (Phragmites australis), manna grasses (Glyceria spp.),

slough grass (Beckmannia syzigachne), and whitetop (Scolochloa festucacea). There is also a variety of broad-leaved persistent emergents such as purple loosestrife (Lythrum salicaria), dock (Rumex mexicanus), water-willow (Decodon verticillatus), and many species of smart-weeds (Polygonum).

Nonpersistent.-Wetlands in this Subclass are domi-nated by plants which fall to the surface of the substrate or below the surface of the water at the end of the grow ing season so that, at certain seasons of the year, there is no obvious sign of emergent vegetation. For example, wild rice (Zizania aquatica) does not become apparent in the North Central States until midsummer and fall, when it may form dense emergent stands. Nonpersistent emer-gents also include species such as arrow arum (Peltandra virginica), pickerelweed (Pontederia cordata), and arrow-heads (Sagittaria spp.). Movement of ice in Estuarine, Riverine, or Lacustrine Systems often removes all traces of emergent vegetation during the winter. Where this occurs, the area should be classified as Nonpersistent Emergent Wetland.

Scrub-Shrub Wetland Definition. The Class Scrub-Shrub Wetland includes areas dominated by woody vegetation less than 6 m (20 feet) tall. The species include true shrubs, young trees, and trees or shrubs that are small or stunted because of environmental conditions. All water regimes except sub-tidal are included.

Description. Scrub-Shrub Wetlands may represent a successional stage leading to Forested Wetland, or they may be relatively stable communities. They occur only in the Estuarine and Palustrine Systems, but are one of the most widespread classes in the United States (Shaw and Fredine 1956). Scrub-Shrub Wetlands are known by many names, such as shrub swamp (Shaw and Fredine 1956),

shrub carr (Curtis 1959), bog (Heinselman 1970), and poco-sin (Kologiski 1977). For practical reasons we have also included forests composed of young trees less than 6 m tall.

Subclasses and Dominance Types.

Broad-leaved Deciduous.-In Estuarine System Wet-lands the predominant deciduous and broad-leaved trees or shrubs are plants such as sea-myrtle (Baccharis halimi folia) and marsh elder (Iva frutescens). In the Palustrine System typical Dominance Types are alders (Alms spp.),

willows (Salix spp.), buttonbush (Cephalanthus occiden-talis), red osier dogwood (Cornus stolonifera), honeycup (Zenobia pulverulenta), spirea (Spiraea douglasii), bog birch (Betula pumila), and young trees of species such as red maple (Acer rubrum) or black spruce (Picea mariana).

Needle-leaved Deciduous.-This Subclass, consisting of wetlands where trees or shrubs are predominantly deciduous and needle-leaved, is represented by young or stunted trees such as tamarack or bald cypress (Taxodium distichum).

Broad-leaved Evergreen.-In the Estuarine System, vast wetland acreages are dominated by mangroves (Rhizophora mangle, Languncularia racemosa, Conocar pus erectus, and Avicennia germinans) that are less than 6 m tall. In the Palustrine System, the broad-leaved ever-green species are typically found on organic soils. North-ern representatives are labrador tea (Ledum groenlan-dicum), bog rosemary (Andromeda glaucophylla), bog laurel (Kalmia polifolia), and the semi-evergreen leather-leaf(Chamaedaphne calyculata). In the south, fetterbush (Lyonia lucida), coastal sweetbells (Leucothoe axillaris),

inkberry (Ilex glabra), and the semi-evergreen black ti-ti (Cyrilla racemifora) are characteristic broad-leaved evergreen species.

Needle-leaved Evergreen.-The dominant species in Needle-leaved Evergreen Wetlands are young or stunted trees such as black spruce or pond pine (Pines serotina).

Dead.-Dead woody plants less than 6 m tall dominate Dead Scrub-Shrub Wetlands. These wetlands are usual-ly produced by a prolonged rise in the water table resulting from impoundment of water by landslides, man, or beavers. Such wetlands may also result from various other factors such as fire, salt spray, insect infestation, air pollu-tion, and herbicides.

Forested Wetland Definition. The Class Forested Wetland is characterized by woody vegetation that is 6 m tall or taller. All water regimes are included except subtidal.

Description. Forested Wetlands are most common in the eastern United States and in those sections of the West where moisture is relatively abundant, particularly along rivers and in the mountains. They occur only in the Palus-trine and Estuarine Systems and normally possess an overstory of trees, an understory of young trees or shrubs, and a herbaceous layer. Forested Wetlands in the Estu-arine System, which include the mangrove forests of Florida, Puerto Rico, and the Virgin Islands, are known by such names as swamps, hammocks, heads, and bottoms.

These names often occur in combination with species names or plant associations such as cedar swamp or bottomland hardwoods.

Subclasses and Dominance Types.

Broad-leaved Deciduous.-Dominant trees typical of Broad-leaved Deciduous Wetlands, which are represented throughout the United States, are most common in the South and East. Common dominants are species such as red maple, American elm (Mmus americana), ashes (Frax-inus pennsylvanica and F. nigra), black gum (Nyssa sylvatica), tupelo gum (N. aquatica), swamp white oak (Quercus bicolor), overcup oak (Q. lyrata), and basket oak (Q. michauxii). Wetlands in this subclass generally occur on mineral soils or highly decomposed organic soils.

Needle-leaved Deciduous.-The southern representa-tive of the Needle-leaved Deciduous Subclass is bald cypress (Taxodium distichum), which is noted for its ability to tolerate long periods of surface inundation. Tamarack is characteristic of the Boreal Forest Region, where it occurs as a dominant on organic soils. Relatively few other species are included in this Subclass.

Broad-leaved Evergreen.-In the Southeast, Broad-leaved Evergreen Wetlands reach their greatest develop-ment. Red bay (Persea borbonia), loblolly bay (Gordonia lasianthus), and sweet bay (Magnolia virginiana) are prevalent, especially on organic soils. This Subclass also includes red mangrove, black mangrove (Avicennia ger-minans), and white mangrove (Languncularia racemosa),

which are adapted to varying levels of salinity.

Needle-leaved Evergreen. -Black spruce, growing on organic soils, represents a major dominant of the Needle-leaved Evergreen Subclass in the North. Though black spruce is common on nutrient-poor soils, Northern white cedar (Thuja occidentalis) dominates northern wetlands on more nutrient-rich sites. Along the Atlantic Coast, Atlantic white cedar (Chamaecyparis thyoides) is one of the most common dominants on organic soils. Pond pine is a common needle-leaved evergreen found in the South-east in association with dense stands of broad-leaved evergreen and deciduous shrubs.

Dead.-Dead Forested Wetlands are dominated by dead woody vegetation taller than 6 m (20 feet). Like Dead Scrub-Shrub Wetlands, they are most common in, or around the edges of, man-made impoundments and beaver ponds. The same factors that produce Dead Scrub-Shrub Wetlands produce Dead Forested Wetlands.

Modifiers 21 To fully describe wetlands and deepwater habitats, one must apply certain Modifiers at the Class level and at lower levels in the classification hierarchy. The Modifiers described below were adapted from existing classifications or were developed specifically for this system.

Water Regime Modifiers Precise description ofhydrologic characteristics requires detailed knowledge of the duration and timing of surface inundation, both yearly and long-term, as well as an under-standing of groundwater fluctuations. Because such in-formation is seldom available, the water regimes that, in part, determine characteristic wetland and deepwater plant and animal communities are described here in only general terms. Water regimes are grouped under two ma-jor headings, Tidal and Nontidal.

Tidal Water Regime Modifiers are used for wetlands and deepwater habitats in the Estuarine and Marine Systems and Nontidal Modifiers are used for all nontidal parts of the Palustrine, Lacustrine, and Riverine Systems. The Tidal Subsystem of the Riverine System and tidally in-fluenced parts of the Palustrine and Lacustrine Systems require careful selection ofWater Regime Modifiers. We designate subtidal and irregularly exposed wetlands and deepwater habitats in the Palustrine, Riverine, and Lacus-trine Systems as permanently flooded-tidal rather than subtidal, and Palustrine, Riverine, and Lacustrine wet-lands regularly flooded by the tide as regularly flooded.

If Palustrine, Riverine, and Lacustrine wetlands are on-ly irregularly flooded by tides, we designate them by the appropriate nontidal Water Regime Modifier with the word tidal added, as in seasonally flooded-tidal.

Tidal The water regimes are largely determined by oceanic tides.

Subtidal. The substrate is permanently flooded with tidal water.

Irregularly Exposed. The land surface is exposed by tides less often than daily.

Regularly Flooded. Tidal water alternately floods and exposes the land surface at least once daily.

Irregularly Flooded. Tidal water floods the land surface less often than daily.

The periodicity and amplitude of tides vary in different parts of the United States, mainly because of differences in latitude and geomorphology. On the Atlantic Coast, two nearly equal high tides are the rule (semidiurnal). On the Gulf Coast, there is frequently only one high tide and one low tide each day (diurnal) ; and on the Pacific Coast there

22 are usually two unequal high tides and two unequal low tides (mixed semidiurnal).

Individual tides range in height from about 9.5 m (31 feet) at St. John, New Brunswick (U.S. National Oceanic and Atmospheric Administration 1973) to less than 1 m (3.3 feet) along the Louisiana coast (Chabreck 1972). Tides of only 10 cm (4.0 inches) are not uncommon in Louisi-ana. Therefore, though no hard and fast rules apply, the division between regularly flooded and irregularly flooded water regimes would probably occur approximately at mean high water on the Atlantic Coast, lowest level of the higher high tide on the Pacific Coast, and just above mean tide level of the Gulf Coast. The width of the inter-tidal zone is determined by the tidal range, the slope of the shoreline, and the degree of exposure of the site to wind and waves.

Nontidal Though not influenced by oceanic tides, nontidal water regimes may be affected by wind or seiches in lakes. Water regimes are defined in terms of the growing season, which we equate to the frost-free period (see the U.S. Depart-ment of Interior National Atlas 1970:110-111 for gen-eralized regional delineation). The rest of the year is defined as the dormant season, a time when even extended periods of flooding may have little influence on the devel-opment of plant communities.

Permanently Flooded. Water covers the land surface throughout the year in all years. Vegetation is composed of obligate hydrophytes.

Intermittently Exposed.

Surface water is present throughout the year except in years of extreme drought.

Semipermanently Flooded. Surface water persists throughout the growing season in most years. When sur-face water is absent, the water table is usually at or very near the land surface.

Seasonally Flooded. Surface water is present for ex-tended periods especially early in the growing season, but is absent by the end of the season in most years. When surface water is absent, the water table is often near the land surface.

Saturated. The substrate is saturated to the surface for extended periods during the growing season, but surface water is seldom present.

Temporarily Flooded. Surface water is present for brief periods during the growing season, but the water table usually lies well below the soil surface for most of the season. Plants that grow both in uplands and wetlands are characteristic of the temporarily flooded regime.

Intermittently Flooded. The substrate is usually ex-posed, but surface water is present for variable periods without detectable seasonal periodicity. Weeks, months, or even years may intervene between periods of inunda tion. The dominant plant communities under this regime may change as soil moisture conditions change. Some areas exhibiting this regime do not fall within our defini-tion of wetland because they do not have hydric soils or support hydrophytes.

Artificially Flooded. The amount and duration of flood-ing is controlled by means of pumps or siphons in com-bination with dikes or dams. The vegetation growing on these areas cannot be considered a reliable indicator of water regime. Examples of artificially flooded wetlands are some agricultural lands managed under a rice-soybean rotation, and wildlife management areas where forests, crops, or pioneer plants may be flooded or dewatered to attract wetland wildlife. Neither wetlands within or resulting from leakage from man-made impoundments, nor irrigated pasture lands supplied by diversion ditches or artesian wells, are included under this modifier.

Water Chemistry Modifiers The accurate characterization of water chemistry in wetlands and deepwater habitats is difficult, both because of problems in measurement and because values tend to vary with changes in the season, weather, time of day, and other factors. Yet, very subtle changes in water chemistry, which occur over short distances, may have a marked influence on the types of plants or animals that inhabit an area. A description of water chemistry, there-fore, must be an essential part ofthis classification system.

The two key characteristics employed in this system are salinity and hydrogen-ion concentration (pH). All habitats are classified according to salinity, and freshwater habitats are further subdivided by pH levels.

Salinity Modifiers Differences in salinity are reflected in the species com-position of plants and animals. Many authors have sug-gested using biological changes as the basis for subdividing the salinity range between sea water and fresh water (Remane and Schlieper 1971). Others have suggested a similar subdivision for salinity in inland wetlands (Moyle 1946 ; Bayly 1967; Stewart and Kantrud 1971). Since the gradation between fresh and hypersaline or hyperhaline waters is continuous, any boundary is artificial, and few classification systems agree completely.

Estuarine and Marine waters are a complex solution of salts, dominated by sodium chloride (NaCl). The term haline is used to indicate the dominance of ocean salt. The relative proportions of the various major ions are usually similar to those found in sea water, even if the water is diluted below sea water strength. Dilution of sea water with fresh water and concentration of sea water by evaporation result in a wide range of recorded salinities in both surface water and interstitial (soil) water.

We have modified the Venice System, suggested at a "Symposium on the Classification of Brackish Waters" in 1958, for use in the Marine and Estuarine Systems (Table 2). The System has been widely used during recent years (Macan 1961, 1963 ; Burbank 1967 ; Carriker 1967 ;

Reid and Wood 1976), although there has been some criticism of its applicability (den Hartog 1960 ; Price and Gunter 1964).

The salinity ofinland water is dominated by four major cations, calcium (Ca), magnesium (Mg), sodium (Na), and potassium (K) ; and three major anions, carbonate (C0 3 ),

sulfate (S04 ), and chloride (Cl) (Wetzel 1975). Salinity is governed by the interactions between precipitation, sur-face runoff, groundwater flow, evaporation, and some-times evapotranspiration by plants. The ionic ratios of inland waters usually differ appreciably from those in the sea, although there are exceptions (Bayly 1967). The great chemical diversity of these waters, the wide variation in physical conditions such as temperature, and often the relative impermanence of surface water, make it extreme-ly difficult to subdivide the inland salinity range in a mean-ingful way. Bayly (1967) attempted a subdivision on the basis of animal life ; Moyle (1945) and Stewart and Kan-trud (1971) have suggested two very different divisions on the basis of plant life. We employ a subdivision that is identical to that used in the Estuarine and Marine Systems (Table 2).

The term saline is used to indicate that any of a num-ber of ions may be dominant or codominant. The term brackish has been applied to inland waters of intermediate salinity (Remane and Schlieper 1971 ; Stewart and Kan-trud 1971), but is not universally accepted (see Bayly 1967:84) ; therefore, mixosaline is used here. In some in-land wetlands, high soil salinities control the invasion or establishment of many plants. These salinities are ex-pressed in units of specific conductance as well as percent salt (Ungar 1974) and they are also covered by the salin-ity classes in Table 2.

pH Modifiers Acid waters are, almost by definition, poor in calcium and often generally low in other ions, but some very soft waters may have a neutral pH (Hynes 1970). It is difficult to separate the effects of high concentrations of hydrogen ions from low base content, and many studies suggest that acidity may never be the major factor controlling the pre-sence or absence of particular plants and animals. Never-theless, some researchers have demonstrated a good correlation between pH levels and plant distribution (Sj6rs 1950 ; Jeglum 1971). Jeglum (1971) showed that plants can be used to predict the pH of moist peat.

There seems to be little doubt that, where a peat layer isolates plant roots from the underlying mineral substrate, the availability of minerals in the root zone strongly in-fluences the types of plants that occupy the site. For this reason, many authors subdivide freshwater, organic wet-Soil Modifiers Table 3. pH Modifiers used in this classification system.

23 lands into mineral-rich and mineral-poor categories (Sj6rs 1950 ; Heinselman 1970 ; Jeglum 1971 ; Moore and Bellamy 1974). We have instituted pH modifiers for freshwater wetlands (Table 3) because pH has been widely used to indicate the difference between mineral-rich and mineral-poor sites, and because it is relatively easy to determine.

The ranges presented here are similar to those of Jeglum (1971), except that the upper limit of the circumneutral level (Jeglum's mesotrophic) was raised to bring it into agreement with usage of the term in the United States.

The ranges given apply to the pH of water. They were converted from Jeglum's moist-peat equivalents by adding 0.5 pH units.

Soil is one of the most important physical components of wetlands. Through its depth, mineral composition, organic matter content, moisture regime, temperature regime, and chemistry, it exercises a strong influence over the types of plants that live on its surface and the kinds of organisms that dwell within it. In addition, the nature of soil in a wetland, particularly the thickness of organic soil, is of critical importance to engineers planning con-struction of highways or buildings. For these and other

reasons, it is essential that soil be considered in the classification of wetlands.

According to the U.S. Soil Conservation Service, Soil Survey Staff (1975 :1-2), soil is limited to terrestrial situa-tions and shallow waters ; however, "areas are not con-sidered to have soil if the surface is permanently covered by water deep enough that only floating plants are present...." Since emergent plants do not grow beyond a depth of about 2 m in inland waters, the waterward limit of soil is virtually equivalent to the waterward limit of wetland, according to our definition. Wetlands can then be regarded as having soil in most cases, whereas deep-water habitats are never considered to have soil.

The most basic distinction in soil classification in the United States is between mineral soil and organic soil (U.S.

Soil Conservation Service, Soil Survey Staff 1975). The Soil Conservation Service recognizes nine orders of mineral soils and one order of organic soils (Histosols) in its taxonomy. Their classification is hierarchical and per-mits the description of soils at several levels of detail. For example, suborders of Histosols are recognized according to the degree of decomposition of the organic matter.

Modifier pH of Water Acid

<5.5 Circumneutral 5.5-7.4 Alkaline

>7.4

24 We use the Modifiers mineral and organic in this classification. Mineral soils and organic soils are differen-tiated on the basis of specific criteria that are enumerated in soil taxonomy (U.S. Soil Conservation Service, Soil Survey Staff 1975:13-14, 65). These criteria are restated in our Appendix D for ready reference. If a more detailed classification is desired, the U.S. Soil Conservation Ser-vice classification system should be used.

Many wetlands and deepwater habitats are man-made, and natural ones have been modified to some degree by the activities of man or beavers. Since the nature of these modifications often greatly influences the character of such habitats, special modifying terms have been included here to emphasize their importance. The following Mod-ifiers should be used singly or in combination wherever they apply to wetlands and deepwater habitats.

Excavated Lies within a basin or channel excavated by man.

Impounded Created or modified by a barrier or dam which pur-posefully or unintentionally obstructs the outflow ofwater.

Both man-made dams and beaver dams are included.

Diked Special Modifiers Created or modified by a man-made barrier or dike designed to obstruct the inflow of water.

Partly Drained The water level has been artificially lowered, but the area is still classified as wetland because soil moisture is sufficient to support hydrophytes. Drained areas are not considered wetland if they can no longer support hydrophytes.

Farmed The soil surface has been mechanically or physically altered for production of crops, but hydrophytes will become reestablished if farming is discontinued.

Artificial Refers to substrates classified as Rock Bottom, Uncon-solidated Bottom, Rocky Shore, and Unconsolidated Shore that were emplaced by man, using either natural materials such as dredge spoil or synthetic materials such as dis-carded automobiles, tires, or concrete. Jetties and break-waters are examples of Artificial Rocky Shores. Man-made reefs are an example of Artificial Rock Bottoms.

REGIONALIZATION FOR THE CLASSIFICATION SYSTEM In this classification system, a given taxon has no par-ticular regional alliance ; its representatives may be found in one or many parts of the United States. However, regional variations in climate, geology, soils, and vegeta-tion are important in the development of different wetland habitats ; and management problems often differ greatly in different regions. For these reasons, there is a need to recognize regional differences. Regionalization is designed to facilitate three activities: (1) planning, where it is necessary to study management problems and poten-tial solutions on a regional basis ; (2) organization and retrieval of data gathered in a resource inventory; and (3) interpretation of inventory data, including differences in indicator plants and animals among the regions.

We recommend the classification and map (Fig. 7) of Bailey (1976) to fill the need for regionalization inland.

Bailey's classification of ecoregions is hierarchical. The upper four levels are domain (defined as including sub-continental areas of related climates), division (defined as including regional climate at the level of Koppen's [1931]

types), province (defined as including broad vegetational types), and section (defined as including climax vegeta-tion at the level of Kdchler's [1964] types). On the map, the boundaries between the different levels are designated by lines of various widths and the sections are numbered with a four-digit code ; digits 1 through 4 represent the first four levels in the hierarchy. The reader is referred to Bailey (1976, 1978) for detailed discussion and descrip-tion of the units appearing on his map, reproduced in our Fig. 7.

The Bailey system terminates at the ocean, whereas the present wetland classification includes Marine and Estu-arine habitats. Many workers have divided Marine and Estuarine realms into series of biogeographic provinces (e.g., U.S. Senate 1970 ; Ketchum 1972). These provinces differ somewhat in detail, but the broader concepts are similar. Figure 7 shows the distribution of 10 Marine and Estuarine provinces that we offer for North America.

" Arctic Province extends from the southern tip ofNew-foundland (Avalon Peninsula), northward around Canada to the west coasts of the Arctic Ocean, Bering Sea, and Baffin and Labrador basins. It is characterized by the southern extension of floating ice, the 4°C summer iso-therm, and Arctic biota.

" Acadian Province extends along the Northeast Atlan-tic Coast from the Avalon Peninsula to Cape Cod and is characterized by a well developed algal flora and boreal biota. The shoreline is heavily indented and frequently rocky. It has a large tidal range and is strongly influenced by the Labrador Current.

" Virginian Province extends along the Middle Atlan-tic Coast from Cape Cod to Cape Hatteras. The province

Qf M2a zaz 0

J QU M2 M282 M2a1 taro LO-0 m

C M 415

9. FJORD U

U R

e 1220 r

gFJOR D M2410 3 c vi z LOU ISIA,Vl 700 Km 4110

~ I. ARCTIC GP 0

v

?~

INLAND ECOREGIONS za 02 WES' e

0 BOUNDARIES OF DOMAIN DIVISION PROVINCE SECTION BOUNDARIES OF 10 MARINE AND ESTUARINE PROVINCES oROVINCE Fig. 7. Ecoregions of the United States after Bailey (1976) with the addition of 10 Marine and Estuarine Provinces proposed in our classification.

aDomains, Divisions, Provinces, and Sections used on Bailey's (1976) map and described in detail in Bailey (1978). Highland ecoregions are designated M mountain, P plateau, and A altiplano.

1000 Polar 1200 Tundra 1210 Arctic Tundra 1220 Bering Tundra M1210 Brooks Range 1300 Subarctic 1310 Yukon Parkland 1320 Yukon Forest M1310 Alaska Range 2000 Humid Temperate 2100 Warm Continental 2110 Laurentian Mixed Forest 2111 Spruce-Fir Forest 2112 Northern Hardwoods-Fir Forest 2113 Northern Hardwoods Forest 2114 Northern Hardwoods-Spruce Forest M2110 Columbia Forest M2111 Douglas-fir Forest M2112 Cedar-Hemlock-Douglas-fir Forest 2200 Hot Continental 2210 Eastern Deciduous Forest 2211 Mixed Mesophytic Forest 2212 Beech-Maple Forest 2213 Maple-Basswood Forest + Oak Savanna 2214 Appalachian Oak Forest 2215 Oak-Hickory Forest 2300 Subtropical 2310 Outer Coastal Plain Forest 2311 Beech-Sweetgum-Magnolia-PineOak 2312 Southern Floodplain Forest 2320 Southeastern Mixed Forest 2000 Humid Temperate 2400 Marine 2410 Willamette-Puget Forest M2410 Pacific Forest (in conterminous U.S.)

M2411 Sitka Spruce-Cedar-Hemlock Forest M2412 Redwood Forest M2413 Cedar-Hemlock-Douglas-fir Forest M2414 California Mixed Evergreen Forest M2415 Silver fir-Douglas-fir Forest M2410 Pacific Forest (in Alaska) 2500 Prairie 2510 Prairie Parkland 2511 Oak-Hickory-Bluestem Parkland 2512 Oak + Bluestem Parkland 2520 Prairie Brushland 2521 Mesquite-Buffalo Grass 2522 Juniper-Oak-Mesquite 2523 Mesquite-Acacia 2530 Tall-Grass Prairie 2531 Bluestem Prairie 2532 Wheatgrass-Bluestem-Needlegrass 2533 Bluestem-Grama Prairie 2600 Mediterranean (Dry-summer Subtropical) 2610 California Grassland M2610 Sierran Forest M2620 California Chaparral 3000 Dry 3100 Steppe 3110 Great Plains-Shortgrass Prairie 3111 Grama-Needlegrass-Wheatgrass 3112 Wheatgrass-Needlegrass 3113 Grama-Buffalo Grass 25 3000 Dry 3100 Steppe M3110 Rocky Mountain Forest M3111 Grand-fir-Douglas-fir Forest M3112 Douglas-fir Forest M3113 Ponderosa Pine-Douglas-fir Forest 3120 Palouse Grassland M3120 Upper Gila Mountains Forest 3130 Intermountain Sagebrush 3131 Sagebrush-Wheatgrass 3132 Lahontan Saltbush-Greasewood 3133 Great Basin Sagebrush 3134 Bonneville Saltbush-Greasewood 3135 Ponderosa Shrub Forest P3130 Colorado Plateau P3131 Juniper-Pinyon Woodland + Sagebrush Saltbush Mosaic P3132 Gram-Galleta Steppe + Juniper-Pinyon Woodland Mosaic 3140 Mexican Highland Shrub Steppe A3140 Wyoming Basin A3141 Wheatgrass-Needlegrass-Sagebrush A3142 Sagebrush-Wheatgrass 3200 Desert 3210 Chihuahuan Desert 3211 Grama-Tobosa 3212 Tarbush-Creosote Bush 3220 American Desert 3221 Creosote Bush 3222 Creosote Bush-Bur Sage 4000 Humid Tropical 4100 Savanna 4110 Everglades 4200 Rainforest M4210 Hawaiian Islands

26 is transitional between the Acadian and Carolinian Provinces. The biota is primarily temperate, but has some boreal representatives. The Labrador Current occasionally extends down to Cape Hatteras and winter temperatures may approach 4°C. The tidal range is moderate.

" Carolinian Province is situated along the South Atlan-tic Coast from Cape Hatteras to Cape Kennedy. It con-tains extensive marshes and well developed barrier islands. Waters are turbid and productive. The biota is temperate but has seasonal tropical elements. The Gulf Stream is the primary influence, and winter temperatures reach a minimum of 10°C ; summer temperatures are tropical (in excess of 20°C)

. The tidal range is small to moderate.

" West Indian Province extends from Cape Kennedy to Cedar Key, Florida, and also includes the southern Gulf of Mexico, the Yucatan Peninsula, Central America, and the Caribbean Islands. The shoreland is usually low-lying limestone with calcareous sands and marls, except for volcanic islands. The biota is tropical and includes reef cor-als and mangroves. Minimum winter temperatures are about 20°C and the tidal range is small.

" Louisianian Province extends along the northern coast of the Gulf of Mexico from Cedar Key to Port Aran-sas, Texas. The characteristics of the province are similar to those of the Carolinian, reflecting the past submergence of the Florida Peninsula. The biota is primarily temper-ate and the tidal range is small.

" CalifornianProvince extends along the Pacific Coast from Mexico northward to Cape Mendocino. The shore-land is strongly influenced by coastal mountains and the coasts are rocky. Freshwater runoff is limited. In the southern part volcanic sands are present; marshes and swamps are scarce throughout the province. The climate is Mediterranean and is influenced by the California Cur-rent. The biota is temperate, and includes well developed offshore kelp beds. The tidal range is moderate.

• Columbian Province extends along the northern Pacific Coast from Cape Mendocino to Vancouver Island. Moun-tainous shorelands with rocky foreshores are prevalent.

Estuaries are strongly influenced by freshwater runoff.

The biota is primarily temperate with some boreal com-ponents, and there are extensive algal communities. The province is influenced by both the Aleutian and Califor-nia Currents. The tidal range is moderate to large.

" Fjord Province extends along the Pacific Coast from Vancouver Island to the southern tip of the Aleutian Islands. Precipitous mountains, deep estuaries (some with glaciers), and a heavilyindented shoreline subject to winter icing are typical of the coast. The biota is boreal to sub-Arctic. The province is influenced by the Aleutian and Japanese Currents, and the tidal range is large.

• Pacific Insular Province surrounds all the Hawaiian Islands. The coasts have precipitous mountains and wave action is stronger than in most of the other provinces. The biota is largely endemic and composed of tropical and sub-tropical forms. The tidal range is small.

Use of Bailey's sections for the Riverine, Lacustrine, and Palustrine Systems and the Provinces defined above for the Marine and Estuarine Systems provides a regional locator for any wetland in the United States.

USE OF THE CLASSIFICATION SYSTEM This System was designed for use over an extremely wide geographic area and for use by individuals and organ-izations with varied interests and objectives. The classi-fication employs 5 System names, 8 Subsystem names, 11 Class names, 28 Subclass names, and an unspecified number of Dominance Types. It is, of necessity, a com-plex System when viewed in its entirety, but use of the System for a specific purpose at a local site should be sim-ple and straightforward. Artificial keys to the Systems and Classes (Appendix E) are furnished to aid the user of the classification, but reference to detailed definitions in the text is also required. The purpose of this section is to illustrate how the System should be used and some of the potential pitfalls that could lead to its misuse.

Before attempting to apply the System, the user should consider four important points:

(1) Information about the area to be classified must be available before the System can be applied. This informa-tion may be in the form of historical data, aerial photo-graphs, brief on-site inspection, or detailed and intensive studies. The System is designed for use at varying degrees of detail. There are few areas for which sufficient infor-mation is available to allow the most detailed application of the System. If the level of detail provided by the data is not sufficient for the needs of the user, additional data gathering is mandatory.

(2) Below the level of Class, the System is open-ended and incomplete. We give only examples of the vast number of Dominance Types that occur. The user may identify additional Dominance Types and determine where these fit into the classification hierarchy. It is also probable that as the System is used the need for additional Subclasses will become apparent.

(3) One of the main purposes of the new classification is to ensure uniformity throughout the United States. It is important that the user pay particular attention to the definitions in the classification. Any attempt at modifica-tion of these definitions will lead to lack of uniformity in application.

(4) One of the principal uses of the classification system will be the inventory and mapping of wetlands and deep-water habitats. A classification used in the mapping is scale-specific, both for the minimum size of units mapped

and for the degree of detail attainable. It is necessary for the user to develop a specific set of mapping conventions for each application and to demonstrate their relationship to the generalized classification described here. For ex-ample, there are a number of possible mapping conven-tions for a small wetland basin 50 m (164 feet) in diam-eter with concentric rings ofvegetation about the deepest zone. At a scale of 1:500 each zone may be classified and mapped ; at 1:20,000 it might be necessary to map the en-tire basin as one zone and ignore the peripheral bands ;

and at 1:100,000 the entire wetland basin may be smaller than the smallest mappable unit, and such a small-scale map is seldom adequate for a detailed inventory and must be supplemented by information gathered by sampling.

In other areas, it may be necessary to develop mapping conventions for taxa that cannot be easily recognized ; for instance, Aquatic Beds in turbid waters may have to be mapped simply as Unconsolidated Bottom.

Hierarchical Levels and Modifiers We have designed the various levels of the system for specific purposes, and the relative importance ofeach will vary among users. The Systems and Subsystems are most important in applications involving large regions or the entire country. They serve to organize the Classes into meaningful assemblages of information for data storage and retrieval.

The Classes and Subclasses are the most important part of the system for many users and are basic to wetland mapping. Most Classes should be easily recognizable by users in a wide variety of disciplines. However, the Class designations apply to average conditions over a period of years, and since many wetlands are dynamic and subject to rapid changes in appearance, the proper classification of a wetland will frequently require data that span a period of years and several seasons in each of those years.

The Dominance Type is most important to users in-terested in detailed regional studies. It may be necessary to identify Dominance Types in order to determine which modifying terms are appropriate, because plants and animals present in an area tend to reflect environmental conditions over a period of time. Water regime can be determined from long-term hydrologic studies where these are available. The more common procedure will be to estimate this characteristic from the Dominance Types.

Several studies have related water regimes to the pres-ence and distribution of plants or animals (e.g., Stephen-son and Stephenson 1972 ; Stewart and Kantrud 1972 ;

Chapman 1974).

Similarly, we do not intend that salinity measurements be made for all wetlands except where these data are re-quired; often plant species or associations can be used to indicate broad salinity classes. Lists of halophytes have been prepared for both coastal and inland areas (e.g.,

27 Duncan 1974; MacDonald and Barbour 1974; Ungar 1974),

and a number of floristic and ecological studies have described plants that are indicators of salinity (e.g., Pen-found and Hathaway 1938 ; Moyle 1945 ; Kurz and Wagner 1957 ; Dillon 1966 ; Anderson et al. 1968 ; Chabreck 1972 ;

Stewart and Kantrud 1972 ; Ungar 1974).

In areas where the Dominance Types to be expected under different water regimes and types of water chem-istry conditions have not been identified, detailed regional studies will be required before the classification can be ap-plied in detail. In areas where detailed soil maps are available, it is also possible to infer water regime and water chemistry from soil series (U.S. Soil Conservation Service, Soil Survey Staff 1975).

Some of the Modifiers are an integral part of this system and their use is essential; others are used only for detailed applications or for special cases. Modifiers are never used with Systems and Subsystems ; however, at least one Water Regime Modifier, one Water Chemistry Modifier, and one Soil Modifier must be used at all lower levels in the hierarchy. Use of the Modifiers listed under mixosaline and mixohaline (Table 2) is optional but these finer categories should be used whenever supporting data are available. The user is urged not to rely on single observa-tions of water regime or water chemistry. Such measure-ments give misleading results in all but the most stable wetlands. If a more detailed Soil Modifier, such as soil order or suborder (U.S. Soil Conservation Service, Soil Survey Staff 1975) can be obtained, it should be used in place of the Modifiers, mineral and organic. Special Modifiers are used where appropriate.

Relationship to Other Wetland Classifications There are numerous wetland classifications in use in the United States. Here we relate this system to three pub-lished classifications that have gained widespread accep-tance. It is not possible to equate these systems directly for several reasons : (1) the criteria selected for establish-ing categories differ ; (2) some of the classifications are not applied consistently in different parts of the country; and (3) the elements classified are not the same in various classifications.

The most widely used classification system in the United States is that of Martin et al. (1953) which was republished in U.S. Fish and Wildlife Service Circular 39 (Shaw and Fredine 1956). The wetland types are based on criteria such as water depth and permanence, water chemistry, life form of vegetation, and dominant plant species. In Table 4 we compare some of the major components of our system with the type descriptions listed in Circular 39.

In response to the need for more detailed wetland classification in the glaciated Northeast, Golet and Lar-son (1974) refined the freshwater wetland types of

28 Table 4. Comparison ofwetland types described in U.S. Fish and Wildlife Service Circular 39 with some ofthe major components of this classification system.

Circular 39 type and references for examples of typical vegetation Classification of Classes wetlands and deepwater habitats Water Water regimes chemistry Type 1-Seasonally flooded basins or flats Wet meadow (Dix and Smeins 1967 ; Stewart and Emergent Wetland Temporarily Flooded Fresh Kantrud 1972)

Forested Wetland Intermittently Mixosaline Bottomland hardwoods (Braun 1950)

Flooded Shallow-freshwater swamps (Penfound 1952)

Type 2-Inland fresh meadows Fen (Heinselman 1963)

Emergent Wetland Saturated Fresh Fen, northern sedge meadow (Curtis 1959)

Mixosaline Type 3-Inland shallow fresh marshes Shallow marsh (Stewart and Kantrud 1972 ; Golet and Emergent Wetland Semipermanently Fresh Larson 1974)

Flooded Mixosaline Seasonally Flooded Type 4-Inland deep fresh marshes Deep marsh (Stewart and Kantrud 1972 ; Golet and Emergent Wetland Permanently Flooded Fresh Larson 1974)

Aquatic Bed Intermittently Mixosaline Exposed Semipermanently Flooded Type 5-Inland open fresh water Open water (Golet and Larson 1974)

Aquatic Bed Permanently Flooded Fresh Submerged aquatic (Curtis 1959)

Unconsolidated Intermittently Mixosaline Bottom Exposed Type 6-Shrub swamps Shrub swamp (Golet and Larson 1974)

Scrub-Shrub All nontidal regimes Fresh Shrub-carr, alder thicket (Curtis 1959)

Wetland except Permanently Flooded Type 7-Wooded swamps Wooded swamp (Golet and Larson 1974)

Forested Wetland All nontidal regimes Fresh Swamps (Penfound 1952 ; Heinselman 1963) except Permanently Flooded Type 8-Bogs Bog (Dansereau and Segadas-vianna 1952 ; Heinselman 1963)

Scrub-Shrub Saturated Fresh Pocosin (Penfound 1952 ; Kologiski 1977)

Wetland (acid only)

Forested Wetland Moss-Lichen Wetland Type 9-Inland saline flats Intermittent alkali zone (Stewart and Kantrud 1972)

Unconsolidated Seasonally Flooded Eusaline Shore Temporarily Flooded Hypersaline Intermittently Flooded Type 10-Inland saline marshes Inland salt marshes (Ungar 1974)

Emergent Wetland Semipermanently Eusaline Flooded Seasonally Flooded Type 11-Inland open saline water Inland saline lake community (Ungar 1974)

Unconsolidated Permanently Flooded Eusaline Bottom Intermittently Exposed Type 12-Coastal shallow fresh marshes Marsh (Anderson et al. 1968)

Emergent Wetland Regularly Flooded Mixohaline Estuarine bay marshes, estuarine river marshes Irregularly Flooded Fresh (Stewart 1962)

Semipermanently Fresh and intermediate marshes (Chabreck 1972)

Flooded-Tidal

Table 4. Continued.

Circular 39 type and references for examples of vegetation Type 13-Coastal deep fresh marshes Circular 39 by writing more detailed descriptions and sub-dividing classes on the basis of finer differences in plant life forms. Golet and Larson's classes are roughly equi-valent to Types 1-8 of Circular39, except that they restrict Type 1 to river floodplains. The Golet and Larson system does not recognize the coastal (tidal) fresh wetlands of Circular 39 (Types 12-14) as a separate category, but classifies these areas in the same manner as nontidal wetlands. In addition to devising 24 subclasses, they also created 5 size categories, 6 site types giving a wetland's hydrologic and topographic location ; 8 cover types (modified from Stewart and Kantrud 1971) expressing the distribution and relative proportions of cover and water; 3 vegetative interspersion types ; and 6 surrounding habitat types. Since this system is based on the classes of Martin et al. (1953), Table 4 may also be used to com-pare the Golet and Larson system with the one described Classification of wetlands and deepwater habitats Water Classes Water regimes chemistry 29 here. Although our system does not include size categories and site types, this information will be available from the results of the new inventory of wetlands and deepwater habitats of the United States.

Stewart and Kantrud (1971) devised a new classifica-tion system to better serve the needs of researchers and wetland managers in the glaciated prairies. Their system recognizes seven classes of wetlands which are distin-guished by the vegetational zone occupying the central or deepest part and covering 5% or more of the wetland basin. The classes thus reflect the wetland's water regime ;

for example, temporary ponds (Class II) are those where the wet-meadow zone occupies the deepest part of the wetland. Six possible subclasses were created, based on differences in plant species composition that are correlated with variations in average salinity of surface water. The third component of classification in their system is the Marsh (Anderson et al. 1968)

Estuarine bay marshes, estuarine river marshes (Stewart 1962)

Fresh and intermediate marshes (Chabreck 1972)

Emergent Wetland Regularly Flooded Semipermanently Flooded-Tidal Mixohaline Fresh Type 14-Coastal open fresh water Estuarine bays (Stewart 1962)

Aquatic Bed Subtidal Mixohaline Unconsolidated Permanently Fresh Bottom Flooded-Tidal Type 15-Coastal salt flats Panne, slough marsh (Redfield 1972)

Unconsolidated Regularly Flooded Hyperhaline Marsh pans (Pestrong 1965)

Shore Irregularly Flooded Euhaline Type 16-Coastal salt meadows Salt marsh (Redfield 1972 ; Chapman 1974)

Emergent Wetland Irregularly Flooded Euhaline Mixohaline Type 17-Irregularly flooded salt marshes Salt marsh (Chapman 1974)

Emergent Wetland Irregularly Flooded Euhaline Saline, brackish, and intermediate marsh (Eleuterius 1972)

Mixohaline Type 18-Regularly flooded salt marshes Salt marsh (Chapman 1974)

Emergent Wetland Regularly Flooded Euhaline Mixohaline Type 19-Sounds and bays Kelp beds, temperate grass flats (Phillips 1974)

Unconsolidated Subtidal Euhaline Tropical marine meadows (Odum 1974)

Bottom Irregularly Exposed Mixohaline Eelgrass beds (Akins and Jefferson 1973 ; Eleuterius 1973)

Aquatic Bed Regularly Flooded Unconsolidated Irregularly Flooded Shore Type 20-Mangrove swamps Mangrove swamps (Walsh 1974)

Scrub-Shrub Irregularly Exposed Hyperhaline Mangrove swamp systems (Kuenzler 1974)

Wetland Regularly Flooded Euhaline Mangrove (Chapman 1976)

Forested Wetland Irregularly Flooded Mixohaline Fresh

30 cover type, which represents differences in the spatial rela-tion of emergent cover to open water or exposed bottom soil. The zones of Stewart and Kantrud's system are readily related to our water regime modifiers (Table 5),

and the subclasses are roughly equivalent to our Water Chemistry Modifiers (Fig. 8).

Wetlands represent only one type of land and the classi-fication ofthis part separate from the rest is done for prac-tical rather than for ecological reasons (Cowardin 1978).

Recently there has been a flurry of interest in a holistic approach to land classification (in Land Classification Series, Journal of Forestry, vol. 46, no. 10). A number of classifications have been developed (e.g., Radford 1978) or are under development (e.g., Driscoll et al. 1978). Parts STEWART AND KANTRUD FRESH APPROXIMATE SPECIFIC CONDUCTANCES Table 5. Comparison ofthe zones ofStewart andKantrud's (1971) classification with the Water Regime Modifiers used in the present classification system.

Zone Water Regime Modifier Wetland-low-prairie Non-wetland by our definition Wet meadow Temporarily flooded Shallow marsh Seasonally flooded Deep marsh Semipermanently flooded Intermittently exposed Intermittent-alkali Intermittently flooded (with eusaline or hypersaline water)

Permanent-open-Permanently flooded (with mixo-water haline water)

Fen (alkaline bog)

Saturated THIS CLASSIFICATION FRESH Fig. 8. Comparison of the water chemistry subclasses of Stewart and Kantrud (1972) with Water Chemistry Modifiers used in the present classification system.

(1972)

SALINE (pMhos)

HYPERSALINE 60,000 EUSALINE 45,000 POLYSALINE 30,000 SUBSALINE 15,000 MESOSALINE BRACKISH 8,000 MIXOSALINE 5,000 MODERATELY BRACKISH OLIGOSALINE 2,000 SLIGHTLY BRACKISH 800 500

of this wetland classification can be incorporated into broader hierarchical land classifications.

A classification system is most easily learned through use. To illustrate the application of this system, we have classified a representative group of wetlands and deep-water habitats of the United States (Plates 1-86 ; pages46-131).

ACKNOWLEDGMENTS The breadth and complexity of preparing this classifica-tion caused us to solicit help and advice from individuals too numerous to list here. Frequently the recommenda-tions were in conflict and we take responsibility for the decisions we have made but acknowledge all suggestions including those not accepted. Several meetings were crucial in formulating the present classification and in modifying earlier drafts. We thank those who attended the formative meeting at Bay St. Louis, Mississippi, January 1975 ; The National Wetland Classification and Inventory Workshop at College Park, Maryland, July 1975 ; and the review panels assembled at Sapelo Island, Georgia, and at St. Petersburg, Florida. We also thank those individuals and agencies who responded to distribu-tion of the operational draft. Special credit is due the regional coordinators of the National Wetlands Inventory and P. B. Reed, who have furnished continuing consulta-tion on application of the system. Martel Laboratories field-tested the system and furnished specific criticisms.

We were advised by J. Everett on geomorphology, K. K.

Young and 0. Carter on soil taxonomy, R. P. Novitzki on hydrology, and R.H. Chabreck on coastal wetland ecology.

M. L. Heinselman and R. H. Hofstetter helped with dif-ficult problems of peatland ecology and terminology. R. L.

Kologiski aided with botanical problems. J. H. Montanari, W. 0. Wilen, and the entire National Wetlands Inventory staff furnished encouragement and logistic support. The staffof the Northern Prairie Wildlife Research Center con-tributed substantially to completion of the classification.

Art work and graphics were prepared by J. Rodiek, R. L.

Duval, andC. S. Shaiffer. J. H. Sather worked closely with us and served as editor on previous drafts.

REFERENCES Abbott, R. T. 1968. Seashells of North America. Golden Press, New York. 280 pp.

Akins, G. J., and C. Q. Jefferson. 1973. Coastal wetlands of Oregon. Oregon Coastal Conservation and Development Com-mission, Florence, Oregon. 159 pp.

Anderson, J. R., E. E. Hardy, J. T. Roach, and R. E. Witmer.

1976. A land use and land cover classification system for use with remote sensor data. U.S. Geol. Surv. Prof. Pap. 964. 28 pp.

Anderson,R. R., R. G. Brown, andR. D. Rappleye. 1968. Water quality and plant distribution along the upper Patuxent River, Maryland. Chesapeake Sci. 9:145-156.

31 Bailey, R. G. 1976. Ecoregions ofthe United States, U.S. Forest Service, Ogden, Utah. (Map only; scale 1:7,500,000.)

Bailey, R. G. 1978. Ecoregions of the United States. U.S. Forest Service, Intermountain Region, Ogden, Utah. 77 pp.

Bayly, I. A. E. 1967. The general biological classification of aquatic environments with special reference to those of Australia. Pages78-104 in A. H. Weatherley, ed. Australian inland waters and their fauna. Australian National University Press, Canberra.

Black, C. A. 1968. Soil plant relationships. John Wiley & Sons, Inc., New York. 792 pp.

Bormann, F. H., and G. E. Likens, 1969. The watershed-eco-system concept and studies of nutrient cycles. Pages 49-76 in G. M. VanDyne, ed. The ecosystem concept in natural resource management. Academic Press, New York.

Braun, E. L. 1950. Deciduous forests ofeastern North America.

Hafner Publishing Co., New York and London. 596 pp.

Brinkhurst, R. 0., andB. G. M. Jamieson. 1972. Aquatic oligo-chaetes of the world. University of Toronto Press, Toronto. 860 PP.

Britton, M. E. 1957. Vegetation of the Arctic tundra. Oregon State Univ. Biol. Colloq. 18:26-61.

Burbank, W. D. 1967. Evolutionary and ecological implications of the zoogeography, physiology and morphology of Cyanthura (Isopoda). Pages 564-573 in G. H. Lauff, ed. Estuaries. Am.

Assoc. Adv. Sci. Publ. 83.

Cain, S. A., and G. M. de Oliveira Castro. 1959. Manual ofvege-tation analysis. Harper & Brothers, New York. 325 pp.

Carriker, M. R. 1967. Ecology of estuarine benthic invertebrates :

a perspective. Pages 442-487 in G. H. Lauff, ed. Estuaries. Am Assoc. Adv. Sci. Publ. 83.

Caspers, H. 1967. Estuaries : analysis of definitions and biological considerations. Pages 6-8 in G. H. Lauff, ed. Estuaries. Am.

Assoc. Adv. Sci. Publ. 83.

Chabreck, R. H. 1972. Vegetation, water and soil characteristics of the Louisiana coastal region. La. Agric. Exp. Stn. Bull. 664.

72 pp.

Chapman, V. J. 1974. Salt marshes and salt deserts ofthe world.

2nd supplemented edition. J. Cramer, Lehre. 392 pp.

Chapman, V. J. 1976. Mangrove vegetation. J. Cramer, Leuter-hausen. 447 pp.

Chapman, V. J. 1977. Introduction. Pages 1-30 in V. J. Chap-man, ed. Wet coastal ecosystems. Ecosystems of the world 1.

Elsevier Scientific Publishing Co., New York.

Clarke, A. H. 1973. The freshwater mollusks of the Canadian In-terior Basin. Malacologia 13(1-2):1-509.

Cowardin, L. M.1978. Wetland classification in the United States.

J. For. 76(10) :666-668.

Crickmay, C. H. 1974. The work of the river. The MacMillan Press, Ltd., London. 271 pp.

Cummins, K. W., C. A. Tryon, Jr., andR. T. Hartman, editors.

1964. Organism-substrate relationships in streams. Pyma-tuning Lab. Ecol., Univ. Pittsburg Spec. Publ. 4. 145 pp.

Curtis, J. T. 1959. The vegetation ofWisconsin. The University of Wisconsin Press, Madison. 657 pp.

Dansereau, P., and F. Segadas-vianna. 1952. Ecological study of the peat bogs of eastern North America. I. Structure and evolution of vegetation. Can. J. Bot. 30:490-520.

Daubenmire, R. 1968. Plant communities. Harper & Row, New York. 300 pp.

32 den Hartog, C. 1960. Comments on the Venice-system for the classification ofbrackish water. Int. Rev. gesamten Hydrobiol.

45:481-485.

Dillon, 0. W. 1966. Gulf coast marsh handbook. U.S. Soil Con-servation Service, Alexandria, Louisiana. n.p.

Dix. R. L., and F. E. Smeins. 1967. The prairie, meadow, and marsh vegetation ofNelson County, North Dakota. Can. J. Bot.

45:21-58.

Driscoll, R. S., J. W. Russell, and M. C. Meier. 1978. Recom-mended national land classification system for renewable resource assessments. U.S. Forest Service, Rocky Mountain Forest and Range Experiment Station, Fort Collins, Colorado.

(Unpublished manuscript)

Drury, W. H., Jr. 1962. Patterned ground and vegetation on southern Bylot Island, Northwest Territories, Canada. Harvard Univ. Gray Herb. Contrib. 190. 111 pp.

Duncan,W. H. 1974. Vascular halophytes of the Atlantic and Gulf coasts of North America north of Mexico. Pages 23-50 in R.

J. Reimold and W. H. Queen, eds. Ecology of halophytes.

Academic Press, Inc., New York.

Eleuterius, L. M. 1972. The marshes of Mississippi. Castanea 37:153-168.

Eleuterius, L. M. 1973. The distribution of certain submerged plants in Mississippi Sound and adjacent waters. Pages 191-197 in J. L. Christmas, ed. Cooperative Gulf of Mexico estuarine inventory and study. Mississippi Gulf Coast Research Labora-tory, Ocean Springs.

Golet, F. C., and J. S. Larson. 1974. Classification of freshwater wetlands in the glaciated Northeast. U.S. Fish Wildl. Serv.,

Resour. Publ. 116. 56 pp.

Gosner, K. L. 1971. Guide to identification of marine and estu-arine invertebrates : Cape Hatteras to the Bay of Fundy. John Wiley & Sons, Inc., New York. 693 pp.

Gray, I. E. 1974. Worm and clam flats. Pages 204-243 in H. T.

Odum, B. J. Copeland, and E. A. McMahan, eds. Coastal ecological systems of the United States. Vol. 2. The Conserva-tion Foundation, Washington, D.C.

Hart, C. W., Jr., and S. L. H. Fuller, editors. 1974. Pollution ecology of freshwater invertebrates. Academic Press, Inc., New York. 389 pp.

Hedgpeth, J. W. 1957. Classification of marine environments.

Pages 17-28 in J. W. Hedgpeth, ed. Treatise on marine ecology and paleoecology ; Vol. 1-Ecology. Geol. Soc. Am. Mem. 67.

Heinselman, M. L. 1963. Forest sites, bog processes, and peat-land types in the Glacial Lake Agassiz Region, Minnesota. Ecol.

Monogr. 33(4):327-374.

Heinselman, M. L. 1970. Landscape evolution, peatland types, and the environment in the Lake Agassiz Peatlands Natural Area, Minnesota, Ecol. Monogr. 40(2):235-261.

Hutchinson, G. E. 1975. A treatise on limnology. Vol. 3. Lim-nological botany. John Wiley & Sons, New York. 660 pp.

Hynes, H. B. N. 1970. The ecology of running waters. Univer-sity of Toronto Press, Toronto. 555 pp.

Illies, J., andL. Botosaneau. 1963. Problems et methodes de la classification et de la zonation ecologique des aux courantes, considerees surtout du point de vue faunistique. Int. Assoc.

Theor. Appl. Limnol. Commun. 12. 57 pp.

Ingram, W. M. 1971. Survival of fresh-water mollusks during periods of dryness. Nautilis 54(3):84-87.

Jeglum, J. K. 1971. Plant indicators of pH and water level in peatlands at Candle Lake, Saskatchewan. Can. J. Bot. 49:1661-1676.

Jeglum, J. K., A. N. Boissonneau, and V. G. Haavisto. 1974.

Toward a wetland classification for Ontario. Can. For. Serv.

Inf. Rep. 0-X-215. 54 pp.

Johnson, R. I. 1970. The systematics and zoogeography of the Unionidae (Mollusca: Bivalvia) of the Southern Atlantic Slope Region. Harvard Univ. Mus. Comp. Zool. Bull. 140(6):263-450.

Kenk, R. 1949. The animal life oftemporary and permanent ponds in southern Michigan. Univ. Mich. Mus. Zool. Misc. Publ. 71.

66 pp.

Ketchum, B. H., editor. 1972. The water's edge : critical problems of the coastal zone. MIT Press, Cambridge, Mass. 393 pp.

Kologiski, R. L. 1977. The phytosociology of the Green Swamp, North Carolina. N.C. Agric. Exp. Stn. Tech. Bull. 250. 101 pp.

K6ppen,W. 1931. Grundriss der Klimakunde. Walter de Gruyter

& Co., Berlin. 388 pp.

Krecker, F. H., andL. Y. Lancaster. 1933. Bottom shore fauna of western Lake Erie : a population study to a depth of six feet.

Ecology 14:79-83.

Kiichler, A. W. 1964. Potential natural vegetation of the con-terminous United States. Am. Geogr. Soc. Spec. Publ. 36. 116 PP.

Kuenzler,E. J. 1974. Mangrove swamp systems. Pages 346-371 in H. T. Odum, B. J. Copeland, and E. A. McMahan, eds.

Coastal ecological systems of the United States. Vol. 1. The Conservation Foundation, Washington, D.C.

Kurz, H., andK. Wagner. 1957. Tidal marshes of the Gulf and Atlantic coasts of northern Florida and Charleston, South Carolina. Fla. State Univ. Stud. 24. 168 pp.

Langbein,W. B., andK. T. Iseri. 1960. General introduction and hydrologic definitions manual of hydrology. Part 1. General surface-water techniques. U.S. Geol. Surv. Water-Supply Pap.

1541-A. 29 pp.

Lauff, G. H., editor. 1967. Estuaries. Am. Assoc. Adv. Sci. Publ.

83.

Leitch, W. G. 1966. Historical and ecological factors in wetland inventory. Trans. N. Am. Wildl. Nat. Resour. Conf. 31:88-96.

Lewis, J. R. 1964. The ecology of rocky shores. English Univer-sities Press Ltd., London. 323 pp.

Liu, T. K. 1970. A review of engineering soil classification systems. Pages 362-382 in Special procedures for testing soil and rock for engineeringpurposes. Am. Soc. Test. Mater. Spec.

Tech. Publ. 479. 630 pp.

Macan, T. T. 1961. Factors that limit the range of freshwater animals. Biol. Rev. 36:151-198.

Macan, T. T. 1963. Freshwater ecology. John Wiley & Sons. Inc.,

New York. 338 pp.

MacDonald, K. B., andM. B. Barbour. 1974. Beach and saltmarsh vegetation ofthe North American Pacific coast. Pages 175-233 in R. J. Reimold andW. H. Queen, eds. Ecology of halophytes.

Academic Press, Inc., New York.

Martin, A. C., N. Hotchkiss, F. M. Uhler, andW. S Bourn. 1953.

Classification ofwetlands of the United States. U.S. Fish Wildl.

Serv., Spec. Sci. Rep.-Wildl. 20. 14 pp.

Millar, J. B. 1976. Wetland classification in western Canada: a guide to marshes and shallow open water wetlands in the grasslands and parklands ofthe Prairie Provinces. Can. Wildl.

Serv. Rep. Ser. 37. 38 pp.

Miner, R. W. 1950. Field book of seashore life. G. P. Putnam's Sons, New York. 888 pp.

Montanari, J. H., and J. E. Townsend. 1977. Status of the Na-tional Wetlands Inventory. Trans. N. Am. Wildl. Nat. Resour.

Conf. 42:66-72.

Moore, P. D., and D. J. Bellamy. 1974. Peatlands. Springer-Verlag, Inc., New York. 221 pp.

Morris, P. A. 1966. A field guide to shells of the Pacific Coast and Hawaii. Houghton Mifflin Company, Boston. 297 pp.

Moyle, J. B. 1945. Some chemical factors influencing the distribu-tion of aquatic plants in Minnesota. Am. Midl. Nat. 34(2):402-420.

Moyle, J. B. 1946. Some indices of lake productivity. Trans. Am.

Fish. Soc. 76:322-334.

Mueller-Dombois, D., andH. Ellenberg. 1974. Aims and methods of vegetation ecology. John Wiley & Sons, New York. 547 pp.

Odum, E. P.1971. Fundamentals of ecology.W. B. Saunders Co.,

Philadelphia. 544 pp.

Odum, H. T. 1974. Tropical marine meadows. Pages 442-487 in H. T. Odum, B. J. Copeland, andE. A. McMahan, eds. Coastal ecological systems of the United States. Vol. 1. The Conserva-tion Foundation, Washington, D.C.

Odum, H. T., B. J. Copeland, andE. A. McMahan, editors. 1974.

Coastal ecological systems of the United States. The Conser-vation Foundation, Washington, D.C. 4 Vol.

Penfound, W. T. 1952. Southern swamps and marshes. Bot. Rev.

18:413-436.

Penfound, W. T., andE. S. Hathaway. 1938. Plant communities in the marshlands of southeastern Louisiana. Ecol. Monogr.

8:1-56.

Pennak, R. W. 1978. Fresh-water invertebrates of the United States. 2nd Edition. John Wiley & Sons, New York. 803 pp.

Pestrong, R. 1965. The development of drainage patterns on tidal marshes. Stanford Univ. Publ. Geol. Sci. 10:1-87.

Phillips,R. C. 1974. Temperate grass flats. Pages 244-314 in H.

T. Odum, B. J. Copeland, and E. A. McMahan, eds. Coastal ecological systems ofthe United States. Vol. 2. The Conserva-tion Foundation, Washington, D.C.

Pollett, F. C., and P. B. Bridgewater. 1973. Phytosociology of peatlands in central Newfoundland. Can. J. For. Res. 3(3):433-442.

Price, J. B., and G. Gunter. 1964. Studies of the chemistry of fresh and low salinity waters in Mississippi and the boundary between fresh and brackish water. Int. Rev. gesamten Hydro-biol. 49:629-636.

Radford, A. E. 1978. Natural area classification systems: a stand-ardized scheme for basic inventory of species, community and habitat diversity. Pages 243-279 in Proceedings of the National Symposium, Classification, Inventory, and Analysis of Fish and Wildlife Habitat. U.S. Fish and Wildlife Service, Washington, D.C.

Radforth, N.W. 1962. Organic terrain and geomorphology. Can.

Geogr. 6(3-4):166-171.

Ranwell, D. S. 1972. Ecology of salt marshes and sand dunes.

Chapman and Hall, London. 258 pp.

Redfield, A. C. 1972. Development of a New England salt marsh.

Ecol. Monogr. 42(2):201-237.

Reid, G. K., andR. D. Wood. 1976. Ecology ofinland waters and estuaries. D. Van Nostrand and Co., New York. 485 pp.

Remane, A., andC. Schlieper. 1971. Biology of brackish water.

Wiley Interscience Division, John Wiley & Sons, New York.

372 pp.

Ricketts, E. F., and J. Calvin. 1968. Between Pacific tides, 4th ed. Revised by J. W. Hedgpeth. Stanford University Press, Stanford, California. 614 pp.

Riedl, R., andE. A. McMahan. 1974. High energybeaches. Pages 180-251 in H. T. Odum, B. J. Copeland, and E. A. McMahan, 33 eds. Coastal ecological systems of the United States. Vol. 1.

The Conservation Foundation, Washington, D.C.

Sculthorpe, C. D. 1967. The biology of aquatic vascular plants.

Edward Arnold Ltd., London. 610 pp.

Shaw, S. P., and C. G. Fredine. 1956. Wetlands of the United States. U.S. Fish Wildl. Serv., Circ. 39. 67 pp.

Sj6rs, H. 1950. On the relation between vegetation and elec-trolytes in north Swedish mire waters. Oikos 2:241-258.

Sj6rs, H. 1959. Bogs and fens in the Hudson Bay lowlands. J.

Arctic Inst. Am. 12(1):2-19.

Slack, K. V., J. W. Nauman, and L. J. Tilley. 1977. Benthic invertebrates in an arctic mountain stream, Brooks Range, Alaska. J. Res. U.S. Geol. Surv. 5:519-527.

Smith, R. I. 1964. Key to marine invertebrates ofthe Woods Hole Region. Contribution No. 11 of the Systematic-Ecology Pro-gram, Marine Biological Laboratory, Woods Hole, Massachu-setts. 208 pp.

Stegman, J. L. 1976. Overview of current wetland classification and inventories in the United States and Canada : U.S. Fish and Wildlife Service. Pages 102-120 in J. H. Sather, ed.

National wetland classification and inventory workshop pro-ceedings-1975, University of Maryland. U.S. Fish and Wild-life Service, Washington, D.C.

Stehr, W. C., and J. W. Branson. 1938. An ecological study of an intermittent stream. Ecology 19(1):294-354.

Stephenson, T. A., andA. Stephenson. 1972. Life between tide-marks on rocky shores. W. H. Freeman and Co., San Francisco.

425 pp.

Stewart, R. E. 1962. Waterfowl populations in the upper Ches-apeake Region. U.S. Fish Wildl. Serv., Spec. Sci. Rep.-Wildl.

65. 208 pp.

Stewart, R. E., andH. A. Kantrud. 1971. Classification ofnatural ponds and lakes in the glaciated prairie region. U.S. Fish. Wildl.

Serv., Resour. Publ. 92. 57 pp.

Stewart, R. E., and H. A. Kantrud. 1972. Vegetation of prairie potholes, North Dakota, in relation to quality of water and other environmental factors. U.S. Geol. Surv. Prof. Pap. 585-D. 36 pp.

Thorson, G. 1957. Bottom communities. Pages 461-534 in J. W.

Hedgpeth, ed. Treatise on marine ecology and paleoecology.

Geol. Soc. Am. Mem. 67. Vol. 1.

Ungar, I. A. 1974. Inland halophytes ofthe United States. Pages 235-305 in R. J. Reimold and W. H. Queen, eds. Ecology of halophytes. Academic Press, New York. 605 pp.

U.S. Department of Agriculture. 1982. National list of scientific plant names. Vol. 1, List of plant names; Vol. 2, Synonymy.

U.S. Soil Conservation Service, SCS-TP-159, Washington, D.C.

Vol. 1-416pp., Vol. 2-438 pp.

U.S. Department of Interior. 1970. National atlas of the United States. U.S. Geological Survey, Washington, D.C. 417 pp.

U.S. National Oceanic and Atmospheric Administration. 1973.

Tide tables-high andlowpredictions 1974 : East coast of North and South America. U.S. Government Printing Office, Wash-ington, D.C. 288 pp.

U.S. Senate. 1970. The National Estuarine Pollution Study.

Report of the Secretary of Interior to the United States Con-gress pursuant to Public Law 89-753, The Clean Water Restora-tion Act of 1966. U.S. Senate Doe. No. 91-58. U.S. Government Printing Office, Washington, D.C. 633 pp.

U.S. Soil Conservation Service, Soil Survey Staff. 1975. Soil Tax-onomy: a basic system of soil classification for making and inter-preting soil surveys. U.S. Soil Conservation Service. Agric.

Handb. 436. 754 pp.

34 van der Schalie, H. 1948. The land and freshwater mollusks of Puerto Rico. Univ. Mich. Mus. Zool. Misc. Publ. 70. 134 pp.

Walker, D. A. 1983. A hierarchical tundra vegetation classifica-tion especially designed for mapping in northern Alaska. Pages 1332-1337 in Permafrost : Fourth International Conference Pro-ceedings, 17-22 July, 1983, University of Alaska, Fairbanks, Alaska. National Academy Press, Washington, D.C.

Walsh, G. E. 1974. Mangroves : a review. Pages51-174 in R. J.

Reimold and W. H. Queen, eds. Ecology of halophytes.

Academic Press, Inc., New York.

Ward, H. B., and G. C. Whipple.1959. Freshwater biology. John Wiley and Sons, Inc., New York. 1248 pp.

Ward, J. V. 1975. Bottom fauna-substrate relationships in a north-ern Colorado trout stream : 1945 and 1974. Ecology 56:1429-1434.

Weaver, J. E., andF. E. Clements. 1938. Plant ecology, 2nd ed.

McGraw-Hill Book Company, Inc., New York. 601 pp.

Weber, C. I., editor. 1973. Biological field and laboratory methods for measuring the quality of surface waters and effluents. U.S.

Environmental Protection Agency, Office of Research and Development, Environmental Monitoring Series. EPA 67014-73-001.

Welch, P. S. 1952. Limnology, 2nd ed. McGraw-Hill, New York.

538 pp.

Wetzel, R. G. 1975. Limnology. W. B. Saunders Co., Philadel-phia. 658 pp.

Zhadin, V. I., and S. V. Gerd. 1963. Fauna and flora of the rivers, lakes and reservoirs ofthe U.S.S.R. Oldbourne Press, London.

626 pp.

Zoltai, S. C., F. C. Pollett, J. K. Jeglum, andG. D. Adams. 1975.

Developing a wetland classification for Canada. Proc. N. Am.

For. Soil s Conf. 4:497-511.

Scientific namea Acer rubrum L.

Alisma plantago-aquatica L.

Alnus spp.

A. rugosa (DuRoi) Spreng.

A. tenuifolia Nutt.

Alopecurus aequalis Sobol.

Andromeda glaucophylla Link Arctophila fulva (Trin.)

Anderss.

Aristida stricta Michx.

Ascophyllum spp.

A. nodosum (L.) LeJol.

Aulacomnium palustre (Hedw.) Schwaegr.

Avicennia germinans (L.) L.

Azolla spp.

Baccharis halimifolia L.

Beckmannia syzigachne (Steud.) Fernald Betula nana L.

B. pumila L.

Brasenia schreberi J. F. Gmel.

Calamagrostis canadensis (Michx.) Beauv.

Calopogon spp.

Caltha palustris L.

Campylium stellatum (Hedw.)

C. Jens Carex spp.

C. aquatilis Wahlenb.

C. atherodes Spreng.

C. bipartita All.

C. lacustris Willd.

C. lasiocarpa Ehrh.

C. lyngbyei Hornem.

C. paleacea Schreb.

ex Wahlenb.

C. plurifora Hulten C. ramenskii Kom.

C. rarifora (Wahlenb.)

J. E. Smith C. rostrata J. Stokes Scientific and Common Names of Plants Common nameb Red maple (Water plantain)

Alders Speckled alder Thinleaf alder Foxtail Bog rosemary Pendent grass (Three-awn)

(Rockweeds)

Knotted wrack (Moss)

Black mangrove Mosquito ferns Sea-myrtle Slough grass Dwarf birch Bog birch Water shield Bluejoint Grass pinks Marsh marigold (Moss)

Sedges (Sedge)

Slough sedge (Sedge)

(Sedge)

(Sedge)

(Sedge)

(Sedge)

(Sedge)

(Sedge)

(Sedge)

Beaked sedge aTaxonomy of vascular plants is according to the National List of Scientific Plant Names (U.S. Dept. Agriculture 1982).

'General common names that refer to a higher taxon and names for which there is little agreement are shown in parentheses.

APPENDIX A Scientific namea Cassiope tetragona (L.)

D. Don Caulerpa spp.

Cephalanthus occidentalis L.

Ceratophyllum spp.

Chamaecyparis thyoides (L.)

B.S.P.

Chamaedaphne calyculata (L.)

Moench Chara spp.

Chenopodium glaucum L.

Chiloscyphus fragilis (Roth)

Schiffn.

Chondrus crispus Stackhouse Cladina spp.

C. rangiferina (L.) Harm Cladium jamaicense Crantz Colocasia esculenta (L.) Scott Conocarpus erectus L.

Cornus stolonifera Michx.

Cymodocea filiformis (Kuetz)

Correll Cyperus spp.

Cyrilla racemifora L.

Decodon verticillatus (L.)

Elliott Dendranthema arcticum (L.)

Tzvel.

Dermatocarpon fuviatile G. H. Web) Th. Fr.

Distichlis spicata (L.) Greene Drepanocladus spp.

Dryas integrifolia Vahl Echinochloa crusgalli (L.)

Beauv.

Eichhornia crassipes (Mart.)

Solms Eleocharis sp.

E. palustris (L.) Roem. &

J. A. Schultes Elodea spp.

Elymus arenarius L.

Empetrum nigrum L.

Enteromorpha spp.

Eriophorum spp.

E. russeolum Fr.

E. vaginatum L.

Fissidens spp.

Common nameb Lapland cassiope (Green algae)

Buttonbush Coontails Atlantic white cedar Leatherleaf (Stoneworts)

(Goosefoot)

(Liverwort)

Irish moss Reindeer mosses (Reindeer moss)

Saw grass Taro Buttonwood Red osier dogwood Manatee grass Nut sedges Black ti-ti Water willow Arctic daisy (Lichen)

(Salt grass)

(Moss)

(Dryas)

Barnyard grass Water hyacinth (Spike rush)

(Spike rush)

Water weeds (Lyme grass)

Crowberry (Green algae)

Cotton grasses (Cotton grass)

(Cotton grass)

(Moss) 35

36 Scientific namea Common nameb Scientific namea Common nameb F. julianus (Mont.) Schimper (Moss)

Nuphar luteum (L.) Sibth. &

Fontinalis spp.

(Moss)

J. E. Smith (Yellow water lily)

Fraxinus nigra Marshall Black ash Nymphaea spp.

(Water lilies)

F. pennsylvanica Marshall (Red ash)

N. odorata Soland. in Ait.

(White water lily)

Fucus spp.

Rockweeds Nyssa aquatica L.

Tupelo gum F. spiralis L.

(Rockweed)

N. sylvatica Marshall Black gum F. vesiculosus L.

(Rockweed)

Oncophorus wahlenbergii Glyceria spp.

Manna grasses Brid.

(Moss)

Gordonia lasianthus (L.)

Panicum capillare L.

Old witch grass J. Ellis Loblolly bay Pedicularis sp.

(Lousewort)

Habenaria spp.

(Orchids)

Peltandra virginica (L.)

Halimeda spp.

(Green algae)

Kunth Arrow arum Halodule wrightii Aschers.

Shoal grass Pelvetia spp.

(Rockweeds)

Halophila spp.

(Sea grass)

Penicillus spp.

(Green algae)

Hippuris tetraphylla L.f.

(Mare's tail)

Persea borbonia (L.) Spreng.

Red bay Hydrilla verticillata Royle (Hydrilla)

Phragmites australis (Cav.)

Ilex glabra (L.) Gray Inkberry Trin. ex Steud.

Reed I. verticillata (L.) Gray Winterberry Phyllospadix scouleri Hook.

(Surfgrass)

Iva frutescens L.

Marsh elder P. torreyi S. Wats.

(Surfgrass)

Juncus spp.

Rushes Picea mariana (Mill.) B.S.P.

Black spruce J. gerardii Loiseleur Black grass P. sitchensis (Bong.) Carriere Sitka spruce J. militaris Bigel.

Bayonet rush Pinus contorta Dougl.

J. roemerianus Scheele Needlerush ex Loudon Lodgepole pine Kalmia angustifolia L.

Sheep laurel P. palustris Mill.

Longleaf pine K. polifolia Wangenh.

Bog laurel P. serotina Michx.

Pond pine Kochia scoparia (L.) Schrad.

Summer cypress Pistia stratiotes L.

Water lettuce Languncularia racemosa (L.)

Plantago maritime L.

Seaside plantain C. F. Gaertn.

White mangrove Podostemum ceratophyllum Laminaria spp.

(Kelps)

Michx.

Riverweed Larix laricina (DuRoi)

Polygonum spp.

Smartweeds K. Koch Tamarack P. amphibium L.

Water smartweed Laurencia spp.

(Red algae)

P. bistorta L.

Bistort Ledum decumbens (Ait.)

Narrowleaf Labrador Pontederia cordata L.

Pickerelweed Small tea Potamogeton spp.

Pondweeds L. groenlandicum Oeder Labrador tea P. gramineus L.

(Pondweed)

Lemna spp.

(Duckweeds)

P. natans L.

Floating-leaf L. minor L.

Common duckweed pondweed Leucothoe axillaris (Lam.)

Populus balsamifera L.

Balsam poplar D. Don Coastal sweetbells P. deltoides W. Bartram Ligusticum scothicum L.

Beach lovage ex Marshall Cottonwood Lithothamnion spp.

Coralline algae Potentilla anserina L.

Silverweed Lycopodium alopecuroides L.

Foxtail clubmoss P. fruticosa L.

Shrubby cinquefoil Lyonia lucida (Lam.) K. Koch Fetterbush P. palustris (L.) Scop.

Marsh cinquefoil Lythrum salicaria L.

Purple loosestrife Puccinellia grandis Swallen (Alkali grass)

Macrocystis spp.

(Kelps)

Quercus bicolor Willd.

Swamp white oak Magnolia virginiana L.

Sweet bay Q. lyrata Walter Overcup oak Marsupella spp.

(Liverworts)

Q. michauxii Nutt.

Basket oak M. emarginata (Ehrenberg)

Ranunculus pallasii Schlecht.

(Crowfoot)

Dumortier (Liverwort)

R. trichophyllus D. Chaix White water Myrica gale L.

Sweet gale crowfoot Myriophyllum spp.

Water milfoils Rhizophora mangle L.

Red mangrove M. spicatum L.

(Water milfoil)

Rhododendron maximum L.

Great laurel Najas spp.

Naiads Rhynchospora spp.

Beak rushes Nelumbo lutea (Willd.) Pers.

American lotus Rubus chamaemorus L.

Cloudberry Nitella spp.

(Stoneworts)

Rumex maritimus L.

Golden dock

Scientific name' Common nameb Scientific name' 37 Common nameb R. mexicanus Meisn.

(Dock)

Suaeda californica S. Wats.

(Sea blite)

Ruppia spp.

Ditch grasses Tamarix gallica L.

Tamarisk R. maritima L.

Widgeon grass Taxodium distichum (L.)

Sagittaria spp.

Arrowheads L. C. Rich.

Bald cypress Salicornia spp.

Glassworts Thalassia testudinum S. europaea L.

(Samphire)

K. D. Koenig Turtle grass S. virginica L.

(Common pickleweed)

Thuja occidentalis L.

Northern white cedar Salix spp.

Willows Tolypella spp.

(Stoneworts)

S. alaxensis (Anderss.) Coville Feltleaf willow Trapa natans L.

Water nut S. fuscescens Anderss.

Alaska bog willow Triglochin maritimum L.

Arrow grass S. ovalifolia Trautv.

Ovalleaf willow Typha spp.

Cattails S. planifolia Pursh Diamondleaf willow T. angustifolia L.

Narrow-leaved cattail S. reticulata L.

Netleaf willow T. latifolia L.

Common cattail Salvinia spp.

Water ferns Ulmus americana L.

American elm Sarcobatus vermiculatus Ulva spp.

Sea lettuce (Hook.) Torr.

Greasewood Utricularia spp.

Bladderworts Scirpus spp.

Bulrushes U. macrorhiza LeConte (Bladderwort)

S. acutus Muhl. ex Bigel.

Hardstem bulrush Vaccinium corymbosum L.

Highbush blueberry S. americanus Pers.

Common threesquare V. oxycoccos L.

Small cranberry S. robustus Pursh (Bulrush)

V. uliginosum L.

Bog blueberry Scolochloa festucacea V. vitis-idaea L.

Mountain cranberry (Willd.) Link Whitetop Vallisneria americana Michx.

Wild celery Solidago sempervirens L.

Seaside goldenrod Verrucaria spp.

(Lichens)

Sparganium hyperboreum Wolffia spp.

Watermeals Laest.

(Bur-reed)

Woodwardia virginica (L.)

Spartina alternijlora J. E. Smith Virginia chain-fern Loiseleur Saltmarsh cordgrass Xanthium strumarium L.

(Cocklebur)

S. cynosuroides (L.) Roth Big cordgrass Xyris spp.

Yellow-eyed grasses S. foliosa Trin.

California cordgrass Xyris smalliana Nash (Yellow-eyed grass)

S. patens (Ait.) Muhl.

Saltmeadow Zannichellia palustris L.

Horned pondweed cordgrass Zenobia pulverulenta Sphagnum spp.

Peat mosses (W. Bartram) Pollard Honeycup Spiraea beauverdiana Zizania aquatica L.

Wild rice C. K. Schneid.

Alaska spiraea Zizaniopsis miliacea (Michx.)

S. douglasii Hook.

(Spiraea)

Doell & Aschers.

Southern wild rice Spirodela spp.

Big duckweeds Zostera marina L.

Eelgrass Stellaria spp.

(Chickweed)

Zosterella dubia (Jacq.) Small Water stargrass

38 APPENDIX B Scientific and Common Names of Animals Scientific name Common namea Scientific name Common namea Acmaea spp.

Limpets Homarus americanus Acropora spp.

Staghorn corals Milne-Edwards American lobster Agrenia spp.

Springtails Hydropsyche spp.

Caddisflies Amphipholis spp.

Brittle stars Lampsilis spp.

Freshwater mollusks Amphitrite spp.

Terebellid worms Ligia spp.

Slaters Ancylus spp.

Freshwater mollusks Limnodrilus spp.

Oligochaete worms Anodonta spp.

Freshwater mollusks Littorina spp.

Periwinkles Anodontoides spp.

Freshwater mollusks Lumbriculus spp.

Oligochaete worms Anopheles spp.

Mosquitos Lymnaea spp.

Pond snails Aplexa spp.

Pouch snails Macoma spp.

Macomas Arenicola spp.

Lugworms M. balthica (Linne)

Baltic macoma Asellus spp.

Isopods Melita spp.

Amphipods Baetis spp.

Mayflies Mercenaria spp.

Quahogs Balanus spp.

Acorn barnacles Modiolus spp.

Mussels Bryocamptus spp.

Harpacticoid Montipora spp.

Corals copepods Muricea spp.

Sea whips Caenis spp.

Mayflies Mya spp.

Soft-shell clams Callianassa spp.

Ghost shrimp Mytilus spp.

Mussels Cambarus spp.

Crayfishes Nassarius spp.

Mud snails Canthocamptus spp.

Harpacticoid Nemoura spp.

Stone flies copepods Nereis spp.

Clam worms Cerianthus spp.

Sea anemones Nerita spp.

Nerites Chaetopterus spp.

Polychaete worms Notonecta spp.

Back swimmers Chironomus spp.

Midges Oliva spp.

Olive shells Chironomidae Midges Orchestia spp.

Beach hoppers Chthamalus spp.

Acorn barnacles Ostrea spp.

Oysters Cnemidocarpa spp.

Tunicates Parastenocaris spp.

Copepods Crassostrea spp.

Oysters Patella spp.

Limpets C. virginica (Geml.)

Eastern oyster Pecten spp.

Scallops Dendraster spp.

Sand dollars Petricola pholadiformis Lam.

False angel wing Diamesa spp.

Midges Phyllognathopus viguieri Donax spp.

Wedge shells Maryek Copepod Echinocardium spp.

Heart urchins Physa spp.

Snails Elliptio spp.

Freshwater mollusks Pisaster spp.

Sea stars Emerita spp.

Mole crabs Pisidium spp.

Fingernail clams Ephemerella spp.

Mayflies Placopecten spp.

Deep-sea scallops Erpobdella spp.

Leeches Platyodon spp.

Boring clams Eukiefferiella spp.

Midges Pollicipes spp.

Gooseneck barnacles Eunapius spp.

Freshwater sponges Porites spp.

Corals Euzonus spp.

Blood worms Pristina spp.

Oligochaete worms Gammarus spp.

Scuds Procambarus spp.

Crayfish Gelastocoris spp.

Toad bugs Psephenus spp.

Riffle beetles Gordonia ventalina L.

Common sea fan Renilla spp.

Sea pansies Helobdella spp.

Leeches Sabellaria spp.

Reef worms Heteromeyenia spp.

Horse sponges Saldula spp.

Shore bugs Hippospongia spp.

Encrusting sponges Saxidomus spp.

Venus clams Simulium spp.

Black flies Siphonaria spp.

False limpets

'Most common names refer only to general groupings.

Sphaerium spp.

Fingernail clams

Scientific name Common names Scientific name Common names Spongilla spp.

Freshwater sponges Thyone spp.

Sea cucumbers Strongylocentrotus spp.

Sea urchins Tivela stultorum (Mawe)

Pismo clam Tabanus spp.

Flies Tortopus spp.

Mayflies Tellina spp.

Tellin shells Tubifex spp.

Sewage worms Tetraclita spp.

Acorn barnacles Uca spp.

Fiddler crabs Thais spp.

Rock shells Urechis spp.

Echiurid worms

40 acid Term applied to water with a pH less than 5.5.

alkaline Term applied to water with a pH greater than 7.4.

bar An elongated landform generated by waves and currents, usually running parallel to the shore, composed predominant-ly of unconsolidated sand, gravel, stones, cobbles, or rubble and with water on two sides.

beach A sloping landform on the shore of larger water bodies, generatedbywaves and currents and extending from the water to a distinct break in landform or substrate type (e.g., a fore-dune, cliff, or bank).

brackish Marine and Estuarine waters with Mixohaline salin-ity. The term should not be applied to inland waters (see page

25).

boulder Rock fragments larger than 60.4 cm (24 inches) in diameter.

broad-leaved deciduous Woody angiosperms (trees or shrubs) with relatively wide, flat leaves that are shed during the cold or dry season; e.g., black ash (Fraxinus nigra).

broad-leaved evergreen Woody angiosperms (trees or shrubs) with relatively wide, flat leaves that generally remain green and are usually persistent for a year or more ; e.g., red man-grove (Rhizophora mangle).

calcareous Formed of calcium carbonate or magnesium car-bonate by biological deposition or inorganic precipitation in suf-ficient quantities to effervesce carbon dioxide visibly when treated with cold 0.1 normal hydrochloric acid. Calcareous sands are usually formed ofa mixture of fragments of mollusk shell, echinoderm spines and skeletal material, coral, foraminifera, and algal platelets (e.g., Halimeda).

channel "An open conduit either naturally or artificially created which periodically or continuously contains moving water, or which forms a connecting link between two bodies of standing water" (Langbein and Iseri 1960:5).

channel bank The sloping land bordering a channel. The bank has steeper slope than the bottom of the channel and is usual-ly steeper than the land surrounding the channel.

circumneutral Term applied to water with a pH of 5.5 to 7.4.

codominant Two or more species providing about equal areal cover which in combination control the environment.

cobbles Rock fragments 7.6 cm (3 inches) to 25.4 cm (10 inches) in diameter.

deciduous stand A plant community where deciduous trees or shrubs represent more than 50% of the total areal coverage of trees or shrubs.

dominant The species controlling the environment.

dormant season That portion ofthe year when frosts occur (see U.S. Department of Interior, National Atlas 1970:110-111 for generalized regional delineation).

emergent hydrophytes Erect, rooted, herbaceous angiosperms that may be temporarily to permanently flooded at the base but do not tolerate prolonged inundation of the entire plant ;

e.g., bulrushes (Scirpus spp.), saltmarsh cordgrass.

emergent mosses Mosses occurring in wetlands, but generally not covered by water.

eutrophic lake Lake that has a high concentration of plant nutrients such as nitrogen and phosphorus.

APPENDIX C Glossary of Terms evergreen stand A plant community where evergreen trees or shrubs represent more than 50% of the total areal coverage of trees and shrubs. The canopy is never without foliage ;

however, individual trees or shrubs may shed their leaves (Mueller-Dombois and Ellenberg 1974).

extreme high water of spring tides The highest tide occurring during a lunar month, usually near the new or full moon. This is equivalent to extreme higher high water of mixed semidiurnal tides.

extreme low water of spring tides The lowest tide occurring during a lunar month, usually near the new or full moon. This is equivalent to extreme lower low water of mixed semidiurnal tides.

flat A level landform composed of unconsolidated sediments-usually mud or sand. Flats may be irregularly shaped or elongate and continuous with the shore, whereas bars are generally elongate, parallel to the shore, and separated from the shore by water.

floating plant A non-anchored plant that floats freely in the water or on the surface ; e.g., water hyacinth (Eichhornia crassipes) or common duckweed (Lemna minor).

floating-leaved plant A rooted, herbaceous hydrophyte with some leaves floating on the water surface ; e.g., white water lily (Nymphaea odorata), floating-leaved pondweed (Potamoge-ton natans). Plants such as yellow water lily (Nuphar luteum) which sometimes have leaves raised above the surface are con-sidered floating-leaved plants or emergents, depending on their growth habit at a particular site.

floodplain "a flat expanse of land bordering an old river... "

(see Reid and Wood 1976 :72, 84).

fresh Term applied to water with salinity less than 0.5°loo dissolved salts.

gravel Amixture composed primarily of rock fragments 2mm (0.08 inch) to 7.6 cm (3 inches) in diameter. Usually contains much sand.

growing season The frost-free period of the year (see U.S.

Department of Interior, National Atlas 1970:110-111 for generalized regional delineation).

haline Term used to indicate dominance of ocean salt.

herbaceous With the characteristics ofan herb ; a plant with no persistent woody stem above ground.

histosols Organic soils (see Appendix D).

hydric soil Soil that is wet long enough to periodically produce anaerobic conditions, thereby influencingthe growth of plants.

hydrophyte, hydrophytic Any plant growing in water or on a substrate that is at least periodically deficient in oxygen as a result of excessive water content.

hyperhaline Term to characterize waters with salinity greater than 40°loo, due to ocean-derived salts.

hypersaline Term to characterize waters with salinity greater than 40°loo, due to land-derived salts.

macrophytic algae Algal plants large enough either as individ-uals or communities to be readily visible without the aid of optical magnification.

mean high water The average height ofthe high water over 19 years.

mean higher high tide The average height ofthe higher of two unequal daily high tides over 19 years.

mean low water The average height of the low water over 19 years.

mean lower low water The average height of the lower of two unequal daily low tides over 19 years.

mean tide level Aplane midway between mean high water and mean low water.

mesohaline Term to characterize waters with salinity of 5 to 180/oo, due to ocean-derived salts mesophyte, mesophytic Any plant growing where moisture and aeration conditions lie between extremes. (Plants typically found in habitats with average moisture conditions, not usually dry or wet.)

mesosaline Term to characterize waters with salinity of 5 to 18° loo, due to land-derived salts.

mineral soil Soil composed of predominantly mineral rather than organic materials (see page 44).

mixohaline Term to characterize water with salinity of 0.5 to 30 0 /oo, due to ocean salts. The term is roughly equivalent to the term brackish.

mixosaline Term to characterize waters with salinity of 0.5 to 30 °loo, due to land-derived salts.

mud Wet soft earth composed predominantly of clay and silt-fine mineral sediments less than 0.074 mm in diameter (Black 1968 ; Liu 1970).

needle-leaved deciduous Woody gymnosperms (trees or shrubs) with needle-shaped or scale-like leaves that are shed duringthe cold or dry season ; e.g., bald cypress (Taxodium distichum).

needle-leaved evergreen Woody gymnosperms with green, needle-shaped, or scale-like leaves that are retained by plants throughout the year ; e.g., black spruce (Picea mariana).

nonpersistent emergents Emergent hydrophytes whose leaves and stemsbreak down at the end of the growing season so that most above-ground portions ofthe plants are easily transported by currents, waves, or ice. The breakdown may result from nor-mal decay or the physical force of strong waves or ice. At cer-tain seasons of the year there are no visible traces ofthe plants above the surface of the water ; e.g., wild rice (Zizania aquatica),

arrow arum (Peltandra virginica).

obligate hydrophytes Species that are found only in wetlands-e.g., cattail (Typha latifolia) as opposed to ubiquitous species that grow either in wetland or on upland-e.g., red maple (Acer rubrum).

oligohaline Term to characterize water with salinity of 0.5 to 5.0 01oo, due to ocean-derived salts.

oligosaline Term to characterize water with salinity of 0.5 to 5.0 °loo, due to land-derived salts.

organic soil Soil composed of predominantly organic rather than mineral material. Equivalent to Histosol (see page 44).

persistent emergent Emergent hydrophytes that normally re-main standing at least until the beginning of the next growing season ; e.g., cattails (Typha spp.) or bulrushes (Scirpus spp.).

photic zone The upper water layer down to the depth of effec-tive light penetration where photosynthesis balances respira-41 tion. This level (the compensation level) usually occurs at the depth of 1% light penetration and forms the lower boundary of the zone of net metabolic production.

pioneer plants Herbaceous annual and seedling perennial plants that colonize bare areas as a first stage in secondary succession.

polyhaline Term to characterize water with salinity of 18 to 30°/oo, due to ocean salts.

polysaline Term to characterize water with salinity of 18 to 30°loo, due to land-derived salts.

saline General term for waters containing various dissolved salts.

We restrict the term to inland waters where the ratios of the salts often vary; the term haline is applied to coastal waters where the salts are roughly in the same proportion as found in undiluted sea water (see page 25).

salinity The total amount of solid material in grams contained in 1 kg of water when all the carbonate has been converted to oxide, the bromine and iodine replaced by chlorine, and all the organic matter completely oxidized.

sand Composed predominantly of coarse-grained mineral sedi-ments with diameters larger than 0.074 mm (Black 1968) and smaller than 2 mm (Liu 1970 ; Weber 1973).

shrub A woody plant which at maturity is usually less than 6 m(20 feet) tall and generally exhibits several erect, spreading, or prostrate stems and has a bushy appearance ; e.g., speckled alder (Alnus rugosa) or buttonbush (Cephalanthus occidentalis).

sound A body of water that is usually broad, elongate, and parallel to the shore between the mainland and one or more islands.

spring tide The highest high and lowest low tides during the lunar month.

stone Rock fragments larger than 25.4 cm (10 inches) but less than 60.4 cm (24 inches).

submergent plant A vascular or nonvascular hydrophyte, either rooted or nonrooted, which lies entirely beneath the water sur-face, except for flowering partsin some species; e.g., wild celery (Vallisneria americana) or the stoneworts (Chara spp.).

terrigenous Derived from or originating on the land (usually referring to sediments) as opposed to material or sediments produced in the ocean (marine) or as a result of biologic activity (biogenous).

tree A woody plant which at maturity is usually 6 m (20 feet) or more in height and generally has a single trunk, unbranched for 1 m or more above the ground, and a more or less definite crown; e.g., red maple (Acer rubrum), northern white cedar (Thuja occidentalis).

water table Theupper surface ofa zone of saturation. No water table exists where that surface is formed by an impermeable body (Langbein and Iseri 1960 :21).

woody plant A seed plant (gymnosperm or angiosperm) that develops persistent, hard, fibrous tissues, basically xylem; e.g.,

trees and shrubs.

xerophyte, xerophytic Any plant growing in a habitat in which an appreciable portion of the rooting medium driesto the wilt-ing coefficient at frequent intervals. (Plants typicallyfound in very dry habitats.)

42 The criteria for distinguishing organic soils from mineral soils in the United States (U.S. Soil Conservation Service, Soil Survey Staff 1975:13-14, 65) are quoted here so that those without ready access to a copy of the Soil Taxonomy may employ this information in the classification of wetlands:

For purposes of taxonomy, it is necessary, first, to define the limits thatdistinguish mineral soil material from organic soil material and, second, to define the minimum part of a soil that should be mineral if the soil is to be classified as a mineral soil.

Nearly all soils contain more than traces of both mineral and organic components in some horizons, but most soils are dominantly one or the other. The horizons that are less than about 20 to 35 percent organic matter by weight have prop-erties that are more nearly those ofmineral than of organic soils. Even with this separation, the volume oforganic matter at the upper limit exceeds that of the mineral material in the fine-earth fraction.

MINERAL SOIL MATERIAL Mineral soil material either

1. Is never saturated with water for more than a few days and has <20 percent organic carbon by weight ; or

2. Is saturated with water for long periods or has been artificially drained, and has

a. Less than 18 percent organic carbon by weight if 60 per-cent or more of the mineral fraction is clay;

b. Less than 12 percent organic carbon by weight if the mineral fraction has no clay ; or

c. A proportional content of organic cabon between 12 and 18 percent if the clay content of the mineral fraction is be-tween zero and 60 percent.

Soil material that has more organic carbon than the amounts just given is considered to be organic material.

DISTINCTION BETWEEN MINERAL SOILS AND ORGANIC SOILS Most soils are dominantly mineral material, but many mineral soilshave horizons of organic material. For simplicity in writing definitions of taxa, a distinction between what is meant by a mineral soil and an organic soil is useful. In a mineral soil, the depth of each horizon is measured from the top of the first horizon of mineral material. In an organic soil, the depth of each horizon is measured from the base of the aerial parts of the growing plants or, if there is no continuous plant cover from the surface of the layer of organic materials. To apply the definitions of many taxa, therefore, one must first decide whether the soil is mineral or organic.

If a soil has both organic and mineral horizons, the relative thickness ofthe organic and the mineral soil materials must be considered. At some point one must decide that the mineral horizons are more important. This point is arbitrary APPENDIX D Criteria for Distinguishing Organic Soils from Mineral Soils and depends in part on the nature ofthe materials. A thick layer of sphagnum has a very low bulk density and contains less organic matter than a thinner layer of well-decomposed muck. It is much easier to measure thickness oflayers in the field than it is to determine tons of organic matter per hec-tare. The definition of a mineral soil, therefore, is based on thickness of the horizons or layers, but the limits of thick-ness must vary with the kinds of materials. The definition thatfollows is intended to classify as mineral soils those that have no more organic material than the amount permitted in the histic epipedon, which is defined later in this chapter.

To determine whether a soil is organic or mineral, the thickness of horizons is measured from the surface of the soil whether that is the surface of a mineral or an organic horizon. Thus, any 0 horizon at the surface is considered an organic horizon, if it meets the requirements oforganic soil material as defined later, and its thickness is added to that of any other organic horizons to determine the total thick-ness of organic soil materials.

DEFINITION OF MINERAL SOILS Mineral soils, in this taxonomy, are soils that meet one of the following requirements:

1. Mineral soil material <2 mm in diameter (the fine-earth fraction) makes up more than half the thickness of the up-per 80 cm (31 in.);

2. The depth to bedrock is <40 cm and the layer or layers of mineral soil directly above the rock either are 10 cm or more thick or have half or more ofthe thicknessofthe over-lying organic soil material ; or

3. The depth to bedrock is 240 cm, the mineral soil material immediately above the bedrock is 10 cm or more thick, and either

a. Organic soil material is <40 cm thick and is decomposed (consisting of hemic or sapric materials as defined later) or has a bulk density of 0.1 or more ; or

b. Organic soil material is <60 cm thick and either is un-decomposed sphagnum or moss fibers or has abulk density that is <0.1.

ORGANIC SOIL MATERIALS Organic soil materials and organic soils

1. Are saturated with water for long periods or are arti-ficially drained and, excluding live roots, (a) have 18 percent or more organic carbon if the mineral fraction is 60 percent or more clay, (b) have 12 percent or more organic carbon if the mineral fraction has no clay, or (c) have a proportional content of organic carbon between 12 and 18 percent if the clay content of the mineral fraction is between zero and 60 percent; or

2. Are never saturated with water for more than afew days and have 20 percent or more organic carbon.

Item 1 in this definition covers materials that have been called peats and mucks. Item 2 is intended to include what has been called litter or 0 horizons. Not all organic soil

materials accumulate in or under water. Leaf litter may rest on a lithic contact and support a forest. The only soil in this situation is organic in the sense that the mineral fraction is appreciably less than half the weight and is only a small percentage of the volume of the soil.

DEFINITION OF ORGANIC SOILS Organic soils (Histosols) are soils that

1. Have organic soil materials that extend from the surface to one of the following :

a. Adepth within 10 cm or less of a lithic or paralithic con-tact, provided the thickness of the organic soil materials is more than twice that of the mineral soil above the con-tact ; or

b. Any depth if the organic soil material rests on frag-mental material (gravel, stones, cobbles) and the interstices are filled with organic materials, or rests on a lithic or para-lithic contact ; or

2. Have organic materials that have an upper boundary within 40 cm of the surface and

a. Have one of the following thicknesses :

(1) 60 cm or more if three-fourths or more of the volume is moss fibers or the moist bulk densityis <0.1 g per cubic centimeter (6.25 lbs per cubic foot) ;

(2) 40 cm or more if (a) The organic soil material is saturated with water for long periods (>6 months) or is artificially drained; and (b) The organic material consists of sapric or hemic materials or consists of fibric materials that are less than three-fourths moss fibers by volume and have a moist bulk density of 0.1 or more ; and

b. Have organic soil materials that (1) Do not have a mineral layer as much as 40 cm thick either at the surface or whose upper boundary is within a depth of 40 cm from the surface ; and (2) Do not have mineral layers, taken cumulatively, as thick as 40 cm within the upper 80 cm.

It is a general rule that a soil is classed as an organic soil (Histosol) either if more than half of the upper 80 cm (32 in.) [sic] of soil is organic or if organic soil material of any thickness rests on rock or on fragmental material having interstices filled with organic materials.

Soils that do not satisfy the criteria for classification as organic soils are mineral soils.

43

44 APPENDIX E Artificial Keys to the Systems and Classes Key to the Systems 1. Water regime influenced by oceanic tides, and salinity due to ocean-derived salts 0.5 0 /oo or greater.

2. Semi-enclosed by land, but with open, partly obstructed or sporadic access to the ocean. Halinity wide-ranging because of evaporation or mixing of seawater with runoff from land

. ESTUARINE 2.

Little or no obstruction to open ocean present. Halinity usually euhaline ; little mixing of water with runoff from land..

....3 3. Emergents, trees, or shrubs present

. ESTUARINE 3. Emergents, trees, or shrubs absent..

. MARINE 1. Water regime not influenced by ocean tides, or if influenced by oceanic tides, salinity less than 0.50/oo.

4. Persistent emergents, trees, shrubs, or emergent mosses cover 30% or more of the area

... PALUSTRINE 4. Persistent emergents, trees, shrubs, or emergent mosses cover less than 30% of substrate but nonpersistent emergents may be widespread during some seasons of year

. 5 5. Situated in a channel ; water, when present, usually flowing.

. RIVERINE 5. Situated in a basin, catchment, or on level or sloping ground; water usually not flowing

. 6 6. Area 8 ha (20 acres) or greater

. LACUSTRINE 6. Area less than 8 ha.

..7 7. Wave-formed or bedrock shoreline feature present or water depth 2 m (6.6 feet) or more

..LACUSTRINE 7. No wave-formed or bedrock shoreline feature present and water less than 2 m deep

. PALUSTRINE Key to the Classes l. During the growing season of most years, areal cover by vegetation is less than 30%.

2. Substrate a ridge or mound formed by colonization of sedentary invertebrates (corals, oysters, tube worms)

...REEF 2. Substrate of rock or various-sized sediments often occupied by invertebrates but not formed by colonization of sedentary invertebrates

..3 3. Water regime subtidal, permanently flooded, intermittently exposed, or semipermanently flooded. Substrate usually not soil..

..4 4. Substrate of bedrock, boulders, or stones occurring singly or in combination covers 75% or more of the area

...ROCK BOTTOM 4. Substrate of organic material, mud, sand, gravel, or cobbles with less than 75% areal cover of stones, boulders, or bedrock.

... UNCONSOLIDATED BOTTOM 3. Water regime irregularly exposed, regularly flooded, irregularly flooded, seasonally flooded, temporarily flooded, intermittently flooded, saturated, or artificially flooded. Substrate often a soil..

.. 5 5. Contained within a channel that does not have permanent flowing water (i.e., Intermittent Subsystem of Riverine System or Intertidal Subsystem of Estuarine System)

. STREAMBED 5. Contained in a channel with perennial water or not contained in a channel

.. 6 6. Substrate of bedrock, boulders, or stones occurring singly or in combination covers 75% or more of the area

..ROCKY SHORE 6. Substrate of organic material, mud, sand, gravel, or cobbles; with less than 75% ofthe cover consisting of stones, boulders, or bedrock

. UNCONSOLIDATED SHORE 1. During the growing season of most years, percentage of area covered by vegetation 30% or greater.

7. Vegetation composed of pioneering annuals or seedling perennials, often not hydrophytes, occurring only at time of substrate exposure

....8 8. Contained within a channel that does not have permanent flowing water.

. STREAMBED (VEGETATED) 8. Contained within a channel with permanent water, or not contained in a channel.

.. UNCONSOLIDATED SHORE (VEGETATED)

45 7. Vegetation composed of algae, bryophytes, lichens, or vascular plants that are usually hydrophytic perennials..

..9 9. Vegetation composed predominantly of nonvascular species...

. 10 10. Vegetation macrophytic algae, mosses, or lichens growing in water or the splash zone of shores

..AQUATIC BED 10. Vegetation mosses or lichens usually growing on organic soils and always outside the splash zone of shores

...MOSS-LICHEN WETLAND 9. Vegetation composed predominantly of vascular species.

. 11 11. Vegetation herbaceous

....12 12. Vegetation emergents

. EMERGENT WETLAND 12. Vegetation submergent, floating-leaved, or floating

.... AQUATIC BED 11. Vegetation trees or shrubs.

....13 13. Dominants less than 6 m (20 feet) tall

.. SCRUB-SHRUB WETLAND 13. Dominants 6 m tall or taller

... FORESTED WETLAND

46

47 Plate 2.-Classification : SYSTEM Marine, SUBSYSTEM Subtidal, CLASS Reef, SUBCLASS Coral, WATER REGIME Subtidal, WATER CHEMISTRY Euhaline. This underwater photograph shows corals (Acropora and Porites) as well as several species of gorgonians.

(Monroe County, Florida; August 1970 ; Photo by E. T. LaRoe)

Plate 3.-Two habitats are shown here. Classification of landward (lighter) zone : SYSTEM Marine, SUBSYSTEM Intertidal, CLASS Rocky Shore, SUBCLASS Bedrock, WATER REGIME Irregularly Flooded, WATER CHEMISTRY Euhaline. Classification of seaward (darker) zone : SYSTEM Marine, SUBSYSTEM Intertidal, CLASS Aquatic Bed, SUBCLASS Algal, DOMINANCE TYPE Fucus spiralis, WATER REGIME Regularly Flooded, WATER CHEMISTRY Euhaline. Subordinate plants in the aquatic bed include rockweed (Focus vesiculosus), knotted wrack (Ascophyllum nodosum), and Irish moss (Chondrus crispus). This photo was taken at low tide. (Newport County, Rhode Island ; July 1977 ; Photo by F. C. Golet)

Plate 4.-Two habitats are shown here. Classification of landward (lighter) zone : SYSTEM Marine, SUBSYSTEM Intertidal, CLASS Rocky Shore, SUBCLASS Rubble, WATER REGIME Irregularly Flooded, WATER CHEMISTRY Euhaline. Classification of seaward (darker) zone : SYSTEM Marine, SUBSYSTEM Intertidal, CLASS Aquatic Bed, SUBCLASS Algal, DOMINANCE TYPE Fucus vesiculosusAscophyllum nodosum, WATER REGIME Regularly Flooded, WATER CHEMISTRY Euhaline. Most stones are larger than 30.5 cm (12 in) in diameter.

(Washington County, Rhode Island ; July 1977 ; Photo by F. C. Golet)

Plate 5.-Classification : SYSTEM Marine, SUBSYSTEM Intertidal, CLASS Unconsolidated Shore, SUBCLASS Sand, WATER REGIMES Regularly Flooded (seaward from the woman to the breaking waves) and Irregularly Flooded (landward from the woman to the base ofthe sand dunes), WATER CHEMISTRY Euhaline. Lines ofwrack (dead Fucus spp., Ascophyllum nodosum, and Zostera marina) on the beach mark the landward limit ofvarious high tides during the past several days. The photo was taken at low tide. (Parker River National Wildlife Refuge, Essex County, Massachusetts ; September 1985 ; Photo by F. C. Golet)

Plate 6.-Classification : SYSTEM Marine, SUBSYSTEM Intertidal, CLASS Unconsolidated Shore, SUBCLASS Sand, WATER REGIMES Regularly Flooded (lower two-thirds of beach) and Irregularly Flooded (upper one-third of beach near base of cliffs), WATER CHEMISTRY Euhaline. (Point Reyes National Seashore, Marin County, California; August 1975 ; Photo by V. Carter)

52 Plate 7.-Classification : SYSTEM Estuarine, SUBSYSTEM Subtidal, CLASS Unconsolidated Bottom, SUBCLASS Sand, WATER REGIME Subtidal, WATER CHEMISTRY Mixohaline. An irregularly flooded persistent-emergent wetland dominated by saltmarsh cordgrass (Spartina alterniflora) and saltmeadow cordgrass (Spartina patens) is shown in the right background (Washington County, Rhode Island ; July 1977 ; Photo by F. C. Golet)

Plate 8.-Classification : SYSTEM Estuarine, SUBSYSTEM Subtidal, CLASS Unconsolidated Bottom, SUBCLASS Mud, WATER REGIME Subtidal, WATER CHEMISTRY Mixohaline. This site lies within the Fjord Biogeographic Province. Glacier-mantled mountains plunge steeply into water more than 180 m (600 ft) deep. (Lynn Canal, Haines Borough, Alaska; June 1985 ; Photo by F. C. Golet)

Plate 9.-Classification : SYSTEM Estuarine, SUBSYSTEM Subtidal, CLASS Aquatic Bed, SUBCLASS Rooted Vascular, DOMINANCE TYPE Myriophyllum spicatum, WATER REGIME Subtidal, WATER CHEMISTRY Mixohaline. Subordinate plant species include mare's tail (Hippuris tetraphylla) and crowfoot (Ranunculus pallasii). This pond is located on coastal tundra ; it is flooded with tidal water only during exceptionally high tides (less often than monthly). Plants characterizing the aquatic bed are shown in the photo-inset.

(Between Azun and Narokachik Rivers, Yukon-Kuskokwim Delta, Alaska; July 1985 ; Photo by F. C. Golet)

55 Plate 10.-Classification: SYSTEM Estuarine, SUBSYSTEM Intertidal, CLASS Reef, SUBCLASS Mollusk, DOMINANCE TYPE Crassostrea virginica, WATER REGIME Regularly Flooded, WATER CHEMISTRY Mixohaline. An individual red mangrove (Rhizophora mangle) has become established on this oyster reef. (Rookery Bay Sanctuary, Collier County, Florida ; January 1978 ; Photo by E

. T. LaRoe)

Plate 11.-Classification : SYSTEM Estuarine, SUBSYSTEM Intertidal, CLASS Streambed, SUBCLASS Mud, WATER REGIME Regularly Flooded, WATER CHEMISTRY Mixohaline. This photo was taken at low tide ; at high tide, the entire channel is flooded. The channel is flanked by irregularly flooded persistent-emergent wetland supporting such plants as

lyme grass (Elymus arenarius), beach lovage (Ligusticum scothicum), silverweed (Potentilla anserina), sedges (Carex ramenskii, C. bipartita), ovalleaf willow (Salix ovalifolia), and Arctic daisy (Dendranthema arcticum). This site lies 100 mfrom Angyoyaravak Bay, on the Bering Sea. (Tutakoke River area, Yukon-Kuskokwim Delta, Alaska ; July 1985 ; Photo by F. C. Golet)

57 Plate 12.-Two habitats lie at the edge of this manmade breakwater. Classification of upper (lighter) zone : SYSTEM Estuarine, SUB-SYSTEM 1ntertidal, CLASS Rocky Shore, SUBCLASS Rubble, WATER REGIME Irregularly Flooded, WATER CHEMISTRY Euhaline, SPECIAL MODIFIER Artificial. Classification of lower (darker) zone : SYSTEM Estuarine, SUBSYSTEM Intertidal, CLASS Aquatic Bed, SUBCLASS Algal, DOMINANCE TYPE Fucus vesiculosus, WATER REGIME Regularly Flooded, WATER CHEMISTRY Euhaline, SPECIAL MODIFIER Artificial. (Washington County, Rhode Island ; July 1977 ; Photo by F. C. Golet)

58 Plate 13.-Classification : SYSTEM Estuarine, SUBSYSTEM Intertidal, CLASS Unconsolidated Shore, SUBCLASS Cobble-Gravel, WATER REGIMES Regularly Flooded (darker zone at edge of water) and Irregularly Flooded (remainder of shore), WATER CHEMISTRY Euhaline. Mean tidal range in this area ofthe Arctic Ocean is approximately 15 cm (6 in). (Mikkelsen Bay, North Slope Borough, Alaska; July 1985 ; Photo by F. C. Golet)

Plate 14.-Classification

SYSTEM Estuarine, SUBSYSTEM Intertidal, CLASS Unconsolidated Shore, SUBCLASS Mud, WATER REGIME Regularly Flooded, WATER CHEMISTRY Mixohaline. Turnagain Arm, a large bay off Cook Inlet, is 4-7 km (2.5-4 mi) wide at this location. Mean tidal range is 9.2 m(30 ft), and the entire area shown here is dewatered at low tide. (Municipality of Anchorage, Alaska; June 1985 ; Photo by F. C. Golet)

60 Plate 15.-Classification: SYSTEM Estuarine, SUBSYSTEM Intertidal, CLASS Unconsolidated Shore, SUBCLASS Mud, WATER REGIME Irregularly Flooded, WATER CHEMISTRY Mixohaline, SOIL Mineral. Alkali grass (Puccinellia grandis) grows in widely scattered clumps at the right-hand edge of the photo. Mean tidal range at Fire Island (background left) is 7.4 m (24.4 ft). The cracks on these mud flats are evidence of the irregularly flooded tidal regime. (Municipality of Anchorage, Alaska

June 1985 ; Photo by F. C. Golet)

61 Plate 16.-Classification: SYSTEM Estuarine, SUBSYSTEM Intertidal, CLASS Emergent Wetland, SUBCLASS Persistent, DOMINANCE TYPE Spartina alterniflora, WATER REGIME Regularly Flooded, WATER CHEMISTRY Mixohaline, SOIL Mineral. Saltmarsh cord-grass is the only plant growing in the regularly flooded zone of this salt marsh. Saltmeadow cordgrass (Spartina patens), seaside goldenrod (Solidago sempervirens), and the sedge, Carex paleacea, grow at the landward edge of the marsh. The photo was taken at high tide. (Essex County, Massachusetts ; September 1985 ; Photo by F. C

. Golet)

Plate 17.-Classification: SYSTEM Estuarine, SUBSYSTEM Intertidal, CLASS Emergent Wetland, SUBCLASS Persistent, DOMINANCE TYPE Spartina foliosa, WATER REGIME Regularly Flooded, WATER CHEMISTRY Mixohaline, SOIL Mineral. The most common sub-ordinate plants are glassworts (Salicornia spp.). This wetland borders an irregularly flooded emergent wetland dominated by glasswort. The photo was taken at high tide. (San Mateo County, California ; August 1976 ; Photo by V. Carter)

63 Plate 18.-Classification: SYSTEM Estuarine, SUBSYSTEM Intertidal, CLASS Emergent Wetland, SUBCLASS Persistent, DOMINANCE TYPE Carex lyngbyei, WATER REGIME Regularly Flooded, WATER CHEMISTRY Mixohaline, SOIL Organic. The photo was taken at low tide. (Coos County, Oregon ; May 1977

Photo by D. D. Peters)

Plate 19.-Classification : SYSTEM Estuarine, SUBSYSTEM Intertidal, CLASS Emergent Wetland, SUBCLASS Persistent, DOMINANCE TYPE Triglochin maritimum, WATER REGIME Irregularly Flooded, WATER CHEMISTRY Mixohaline, SOIL Mineral. Subordinate plants include samphire (Salicornia europaea) and seaside plantain (Plantago maritima). This stand is located at the seaward edge of the irregularly flooded zone where it is inundated by most, but not all, high tides. Water depth is less than 5 cm (2 in). Slightly more elevated stands of Triglochin maritimum contain little or no standing water between periods of inundation. (Municipality of Anchorage, Alaska; June 1985 ; Photo by F. C. Golet)

Plate 20.-Classification

SYSTEM Estuarine, SUBSYSTEM Intertidal, CLASS Emergent Wetland, SUBCLASS Persistent, DOMINANCE TYPE Phragmites australis, WATER REGIME Irregularly Flooded, WATER CHEMISTRY Mixohaline, SOIL Mineral. Saltmeadow cord-grass (Spartina patens) and saltmarsh cordgrass (Spartina alterniflora) are subordinate species. (Washington County, Rhode Island ; July 1977 ; Photo by F. C. Golet)

66 Plate 21.-Classification: SYSTEM Estuarine, SUBSYSTEM Intertidal, CLASS Emergent Wetland, SUBCLASS Persistent, DOMINANCE TYPE Scirpus americanus, WATER REGIME Regularly Flooded, WATER CHEMISTRY Mixohaline, SOIL Organic. Subordinate species include saltmeadow cordgrass (Spartina patens) and saltmarsh cordgrass (Spartina alterniflora) ; these appear as a fringe at the water's edge. (Dorchester County, Maryland ; June 1974 ; Photo by V. Carter)

Plate 22.-Classification: SYSTEM Estuarine, SUBSYSTEM Intertidal, CLASS Emergent Wetland, SUBCLASS Persistent, DOMINANCE TYPE Carex lyngbyei, WATER REGIME Irregularly Flooded, WATER CHEMISTRY Oligohaline, SOIL Mineral. Subordinate species in-clude sedge (Carex pluriflora), silverweed (Potentilla anserina), arrow grass (Triglochin maritimum), and mare's tail (Hippuris tetraphylla). Located on the floodplain of a tidal river, this site receives freshwater runoff from the Chugach Mountains and the Twenty-mile Glacier (center background), and is also inundated by exceptionally high tides. Soil salinity during October 1985 was 30loo. (Muncipality of Anchorage, Alaska; June 1985

Photo by F. C

. Golet)

68 Plate 23.-Classification : SYSTEM Estuarine, SUBSYSTEM Intertidal, CLASS Emergent Wetland, SUBCLASS Nonpersistent, DOMINANCE TYPE H2pp2Gr2S tetraphylla, WATER REGIME Regularly Flooded, WATER CHEMISTRY Mixohaline, SOIL Mineral. This stand of mare's tail lies at the landward limit of the regularly flooded zone, where the substrate is covered with several centimeters of water at high tide. The Azun River, source of the tidal water, is just visible at the right-hand edge of the photo. (Mouth of Azun River, Yukon-Kuskokwim Delta, Alaska; July 1985 ; Photo by F. C. Golet)

Plate 24.-Classification : SYSTEM Estuarine, SUBSYSTEM Intertidal, CLASS Scrub-Shrub Wetland, SUBCLASS Broad-leaved Deciduous, DOMINANCE TYPE Ivafru.tescens, WATER REGIME Irregularly Flooded, WATER CHEMISTRY Mixohaline, SOIL Mineral. Subordinate plants growing beneath the marsh elder are black grass (Juncos gerardii), salt grass (Distichlis spicata), and saltmeadow cord-grass (Spartina patens)

. This wetland lies toward the landward edge of an irregularly flooded persistent-emergent wetland dominated by saltmarsh cordgrass (Spartina alterniflora), saltmeadow cordgrass, and salt grass (background). (Washington County, Rhode Island ; July 1977 ; Photo by F. C. Golet)

Plate 25.-Classification : SYSTEM Estuarine, SUBSYSTEM Intertidal, CLASS Scrub-Shrub Wetland, SUBCLASS Broad-leaved Evergreen, DOMINANCE TYPE Rhizophora mangle, WATER REGIMES Regularly Flooded (along waterways) and Irregularly Flooded (at some distance from waterways), WATER CHEMISTRY Oligohaline, SOIL Organic. This mangrove swamp is located in the southern part of the Florida Everglades. (Dade County, Florida ; December 1975 ; Photo by V. Carter)

Plate 26.-Classification : SYSTEM Riverine, SUBSYSTEM Tidal, CLASS Aquatic Bed, SUBCLASS Rooted Vascular, DOMINANCE TYPE Myriophyllum spicatumHydrilla verticillata-Heteranthera dubia, WATER REGIME Permanently Flooded-Tidal, WATER CHEMISTRY Fresh-Circumneutral. (Prince Georges County, Maryland ; October 1985 ; Photo by V. Carter)

72 Plate 27.-Two habitats are shown here. Classification of nonvegetated zone : SYSTEM Riverine, SUBSYSTEM Tidal, CLASS Uncon-solidated Shore, SUBCLASS Mud, WATER REGIME Regularly Flooded, WATER CHEMISTRY Fresh-Circumneutral. Classification of vegetated zone : SYSTEM Riverine, SUBSYSTEM Tidal, CLASS Emergent Wetland, SUBCLASS Nonpersistent, DOMINANCE TYPE Peltandra virginica, WATER REGIME Regularly Flooded, WATER CHEMISTRY Fresh-Circumneutral, SOIL Mineral. The photo was taken at low tide. (Cecil County, Maryland ; July 1972 ; Photo by V. Carter)

73 Plate 28.-Classification: SYSTEM Riverine, SUBSYSTEMLower Perennial, CLASS Unconsolidated Bottom, SUBCLASS Cobble-Gravel, WATER REGIME Permanently Flooded, WATER CHEMISTRY Fresh. The channel bottom is composed primarily of gravel and sand.

The stream meanders through a grassy annual floodplain which is flanked by a more elevated floodplain supporting cottonwoods (Populus deltoides). (Crook County, Wyoming; May 1985 ; Photo by F. C. Golet)

Plate 29.-Classification : SYSTEM Riverine, SUBSYSTEM Lower Perennial, CLASS Unconsolidated Bottom, SUBCLASS Sand, WATER REGIME Permanently Flooded, WATER CHEMISTRY Fresh. Channel meanders, a typical feature of lower perennial streams, are especially well developed along this section of the Yellowstone River. (Yellowstone National Park, Park County, Wyoming; May 1985 ; Photo by F. C. Golet)

75 Plate 30.-Classification : SYSTEM Riverine, SUBSYSTEM Lower Perennial, CLASS Aquatic Bed, SUBCLASS Rooted Vascular, DOMINANCE TYPE Nymphaea odorata, WATER REGIME Permanently Flooded, WATER CHEMISTRY Fresh-Circumneutral, SPECIAL MODIFIER Excavated. This channel was dug by man in an unsuccessful attempt to drain the wetland. Plants in the Palustrine wetland bordering the channel include sedge (Carex lasiocarpa), sweet gale (Myrica gale), leatherleaf(Chamaedaphne calyculata), and Atlantic white cedar (Chamaecyparis thyoides). (Washington County, Rhode Island ; July 1977 ; Photo by F. C. Golet)

Plate 31.-Classification : SYSTEM Riverine, SUBSYSTEM Lower Perennial, CLASS Unconsolidated Shore, SUBCLASS Cobble-Gravel, WATER REGIME Temporarily Flooded, WATER CHEMISTRY Fresh. Feltleaf willow (Salix alaxensis) grows along the edge of the stream. The entire channel is flooded for only a few weeks after snowmelt each year. (Kavik River, North Slope Borough, Alaska; July 1985 ; Photo by F. C. Golet)

77 z

Plate 32.-Classification : SYSTEM Riverine, SUBSYSTEM Lower Perennial, CLASS Unconsolidated Shore, SUBCLASS Sand, WATER REGIME Seasonally Flooded, WATER CHEMISTRY Mixosaline, SOIL Mineral. Young tamarisk (Tamarix gallica) plants are scattered over this sand flat. (Socorro County, New Mexico ; April 1978 ; Photo by P. B. Reed)

78 Plate 33.-Classification : SYSTEM Riverine, SUBSYSTEM Lower Perennial, CLASS Emergent Wetland, SUBCLASS Nonpersistent, DOMINANCE TYPE Peltandra virginica-Pontederia cordata, WATER REGIME Semipermanently Flooded, WATER CHEMISTRY Fresh-Circumneutral, SOIL Mineral. This wetland lies in a bay ofthe Chicopee River. (Hampden County, Massachusetts ; July 1970 ; Photo by R. C. Smardon)

79 Plate 34.-Two habitats are shown here. Classification of channel: SYSTEM Riverine, SUBSYSTEM Upper Perennial, CLASS Rock Bottom, SUBCLASS Bedrock, WATER REGIME Permanently Flooded, WATER CHEMISTRY Fresh. Classification of shore: SYSTEM Riverine, SUBSYSTEM Upper Perennial, CLASS Rocky Shore, SUBCLASS Bedrock, WATER REGIME Seasonally Flooded, WATER CHEMISTRY Fresh. (Penobscot County, Maine; October 1977 ; Photo by R. W. Tiner)

80 Plate 35.-Classification : SYSTEM Riverine, SUBSYSTEM Upper Perennial, CLASS Rock Bottom, SUBCLASS Rubble, WATER REGIME Permanently Flooded, WATER CHEMISTRY Fresh. Many of the boulders in this river exceed 1 m (3.3 ft) in diameter. (Matanuska-Susitna Borough, Alaska ; June 1985 ; Photo by F. C. Golet)

81 Plate 36.-Classification : SYSTEM Riverine, SUBSYSTEM Upper Perennial, CLASS Unconsolidated Bottom, SUBCLASS Cobble-Gravel, WATER REGIME Permanently Flooded, WATER CHEMISTRY Fresh-Circumneutral. (Washington County, Rhode Island ; July 1977; Photo by F. C. Golet)

82 Plate 37.-Classification : SYSTEM Riverine, SUBSYSTEM Upper Perennial, CLASS Unconsolidated Shore, SUBCLASS Cobble-Gravel, WATER REGIME Temporarily Flooded, WATER CHEMISTRY Fresh. This high-gradient mountain stream arises in the Alaska Range.

The gravel piled at the left-hand edge of the photo had accumulated in the channel during flood stage and was bulldozed to its present position to prevent flooding of a highway just downstream. (Fairbanks North Star Borough, Alaska ; July 1985 ; Photo by F. C. Golet)

Plate 38.-Classification : SYSTEM Riverine, SUBSYSTEM Intermittent, CLASS Streambed, SUBCLASS Sand, WATER REGIME Inter-mittently Flooded, WATER CHEMISTRY Mixosaline. The average annual discharge for this river, the Rio Salado, is 14.6 hm3/yr (11,880 acre-ft/yr). (Socorro County, New Mexico ; April 1978 ; Photo by P. B. Reed)

Plate 39.-Classification: SYSTEM Riverine, SUBSYSTEM Intermittent, CLASS Streambed, SUBCLASS Mud, WATER REGIME Intermit-tently Flooded. Streambeds such as this are common throughout the arid West. They carry water for briefperiods after snowmelt and following rainstorms which are irregular and unpredictable in occurrence. (Badlands National Monument, Jackson County, South Dakota ; May 1985; Photo by F. C. Golet)

Plate 40.-Classification : SYSTEM Lacustrine, SUBSYSTEM Limnetic, CLASS Unconsolidated Bottom, SUBCLASS Mud, WATER REGIME Permanently Flooded, WATER CHEMISTRY Fresh. In the narrow Littoral zone of Yellowstone Lake, where water is less than 2 m (6.6 ft) deep, the bottom consists primarily of gravel and sand. (Yellowstone National Park, Teton County, Wyoming; May 1985 ; Photo by F. C. Golet)

86 Plate 41.-Classification : SYSTEM Lacustrine, SUBSYSTEM Limnetic, CLASS Aquatic Bed, SUBCLASS Rooted Vascular, DOMINANCE TYPE Nymphaea odorata, WATER REGIME Permanently Flooded, WATER CHEMISTRY Fresh-Circumneutral. Subordinate plants in the Aquatic Bed include bladderworts (Utricularia spp.). Yellow-eyed grass (Xyris smalliana) grows on floating mats of peat along the shore (foreground). Water depth in this 0.8-ha (2-acre) bog lake exceeds 3 m (10 ft). (Washington County, Rhode Island ;

July 1977; Photo by F. C. Golet)

Plate 42.-Classification : SYSTEM Lacustrine, SUBSYSTEM Littoral, CLASS Unconsolidated Shore, SUBCLASS Cobble-Gravel, WATER REGIME Seasonally Flooded, WATER CHEMISTRY Fresh. At the time of photography, the level of Yellowstone Lake was near its seasonal low point. Due to snowmelt, the level of the lake rises to a peak in early July and then slowly declines until the following spring. This entire beach is inundated each summer. (Yellowstone National Park, Teton County, Wyoming; May 1985 ; Photo by F. C. Golet)

Plate 43.-Classification : SYSTEM Lacustrine, SUBSYSTEM Littoral, CLASS Unconsolidated Shore, SUBCLASS Sand, WATER REGIME Intermittently Flooded, WATER CHEMISTRY Fresh. Water levels in the Great Lakes generally fluctuate little during a single year, but they may rise and fall considerably over a period of several years. The water level in Lake Michigan was at an all-time high when this photo was taken. As a result of long-term changes in lake levels and seiches produced by storms, lake waters inundate part or all of this beach on an irregular basis. (Indiana Dunes National Lakeshore, Porter County, Indiana; May 1985 ; Photo by F. C. Golet)

89 Plate 44.-Classification : SYSTEM Lacustrine, SUBSYSTEM Littoral, CLASS Uncoi:solidated Shore, SUBCLASS Mud, WATER REGIMES Temporarily Flooded and Seasonally Flooded, WATER CHEMISTRY Fresh, SOIL Mineral, SPECIAL MODIFIER Impounded. The flats exposed along the shore of this reservoir are temporarily flooded ; the seasonally flooded zone is still inundated at the time of this spring photograph. (Park County, Wyoming; May 1985 ; Photo by F. C. Golet)

Plate 45.-Classification : SYSTEM Lacustrine, SUBSYSTEM Littoral, CLASS Unconsolidated Shore, SUBCLASS Mud, WATER REGIME Seasonally Flooded, WATER CHEMISTRY Hypersaline. (Salt Lake County, Utah ; June 1973 ; Photo by V. Carter)

Plate 46.-Two habitats are shown here. Classification of exposed areas: SYSTEM Lacustrine, SUBSYSTEM Littoral, CLASS Uncon-solidated Shore, SUBCLASS Mud, WATER REGIMES Intermittently Flooded (light-colored soil) and Seasonally Flooded (darker soil along water's edge), WATER CHEMISTRY Mixosaline, SOIL Mineral. Classification of inundated areas: SYSTEM Lacustrine, SUB-SYSTEM Littoral, CLASS Unconsolidated Bottom, SUBCLASS Mud, WATER REGIME Semipermanently Flooded, WATER CHEMISTRY Mixosaline, SOIL Mineral. Greasewood (Sarcobatus vermiculatus), salt grass (Distichlis spicata), and rushes (Juncos spp.) are scattered across the flats. Because annual precipitation averages only about 18 cm (7 in) here, these wetlands are heavily dependent upon snowpack in the surrounding mountains as a source of water. (Saguache County, Colorado ; Photo by R. M. Hopper)

Plate 47.-Classification : SYSTEM Lacustrine, SUBSYSTEM Littoral, CLASS Unconsolidated Shore, SUBCLASS Organic, WATER REGIME Seasonally Flooded, WATER CHEMISTRY Fresh. This beach is only 15 m (50 ft) long and 2 m (6-7 ft) wide. Such organic shores are common in certain areas of the Yukon-Kuskokwim Delta, and many are considerably larger than the one shown here. Evidence of the decline in lake levels over the summer can be seen in the series of low ridges in the peat. Surrounding vegetation includes sedge (Carex lyngbyei), bluejoint (Calamagrostis canadensis), and willows (Salix spp.). (Talik River area, Yukon-Kuskokwim Delta, Alaska; July 1985 ; Photo by F. C. Golet)

Plate 48.-Classification : SYSTEM Lacustrine, SUBSYSTEM Littoral, CLASS Emergent Wetland, SUBCLASS Nonpersistent, DOMINANCE TYPE Nelumbo lutea, WATER REGIME Permanently Flooded, WATER CHEMISTRY Fresh-Circumneutrai, SOIL Mineral, SPECIAL MODIFIER Impounded. Subordinate plants are duckweeds (Lemna spp.) and bald c;gpress (Taxodium distichum). (Obion County, Tennessee ; September 1975 ; Photo by V. Carter)

94 Plate 49.-Classification: SYSTEM Lacustrine, SUBSYSTEM Littoral, CLASS Emergent Wetland, SUBCLASS Nonpersistent, DOMINANCE TYPE Juncus militaris, WATER REGIME Semipermanently Flooded, WATER CHEMISTRY Fresh-Circumneutral, SOIL Mineral. Subor-dinate plants include common threesquare (Scirpus americanus) and pickerelweed (Pontederia cordata). During the spring, emergent vegetation is not evident at this site, and waves break on the gravel shore visible in the foreground. (Washington County, Rhode Island ; July 1977 ; Photo by F. C. Golet)

95 Plate 50.-Classification : SYSTEM Palustrine, CLASS Unconsolidated Bottom, SUBCLASS Sand, WATER REGIME Intermittently Ex-posed, WATER CHEMISTRY Fresh-Alkaline. Rushes (Juncos spp.), spike rush (Eleocharis sp.), and smartweed (Polygonum sp.) grow in shallow water along the shore of this 0.4-ha (1-acre) pond which occupies a depression amidst sand dunes on the southern shore of Lake Michigan. (Indiana Dunes National Lakeshore, Porter County, Indiana; May 1985 ; Photo by F. C

. Golet)

96 Plate 51.-Classification : SYSTEM Palustrine, CLASS Unconsolidated Bottom, SUBCLASS Mud, WATER REGIME Permanently Flooded, WATER CHEMISTRY Fresh-Circumneutral, SPECIAL MODIFIER Impounded. This beaver pond is situated in the San Juan Moun-tains. (Gunnison County, Colorado ; Photo by R. M. Hopper)

97 Plate 52.-Classification: SYSTEM Palustrine, CLASS Unconsolidated Bottom, SUBCLASS Mud, WATER REGIME Semipermanently Flooded, WATER CHEMISTRY Mesosaline, SOIL Mineral. This photo was taken during drouth conditions ; the bottom is being in-vaded by pioneer species including summer cypress (Kochia scoparia), golden dock (Rumex maritimus), andgoosefoot (Chenopodium glaucum). (Stutsman County, North Dakota ; August 1961 ; Photo by R. E. Stewart)

98 Plate 53.-Classification : SYSTEM Palustrine, CLASS Unconsolidated Bottom, SUBCLASS Mud, WATER REGIME Semipermanently Flooded, WATER CHEMISTRY Fresh-Alkaline, SOIL Mineral, SPECIAL MODIFIER Impounded. A sparse stand of water plantain (Alisma plantago-aquatica) appears along the edge of the impoundment. (Billings County, North Dakota; July 1970 ; Photo by J. T. Lokemoen)

Plate 54.-Classification : SYSTEM Palustrine, CLASS Aquatic Bed, SUBCLASS Rooted Vascular, DOMINANCE TYPE Ranunculus trichophyllus, WATER REGIME Semipermanently Flooded, WATER CHEMISTRY Oligosaline, SOIL Mineral. (Stutsman County, North Dakota ; August 1966 ; Photo by R. E. Stewart)

100 Plate 55.-Classification: SYSTEM Palustrine, CLASS Moss-Lichen Wetland, SUBCLASS MOSS, WATER REGIME Saturated, WATER CHEMISTRY Fresh-Acid, SOIL Organic. The dominant plant is peat moss (Sphagnum spp.). Subordinate plants include reindeer moss (Cladina spp.), leatherleaf(Chamaedaphne calyculata), crowberry (Empetrum nigrum), and cottongrass (Eriophorum spp.).

(Campobello Island International Park, Maine-Canada ; June 1976 ; Photo by V. Carter)

Plate 56.-Classification: SYSTEM Palustrine, CLASS Moss-Lichen Wetland, SUBCLASS Moss, WATER REGIME Saturated, WATER CHEMISTRY Fresh. Peat moss (Sphagnum spp.) is the dominant plant. Subordinate plants include sedges (Carex rariflora, C. aquatilis),

cottongrass (Eriophorum russeolum), and reindeer moss (Cladina spp.). While sedges are present, their combined cover is less than 30%. Mosses cover 100% of the area. (Narokachik-Azun Rivers area, Yukon-Kuskokwim Delta, Alaska ; July 1985 ; Photo by F. C. Golet)

Plate 57.-Classification : SYSTEM Palustrine, CLASS Emergent Wetland, SUBCLASS Persistent, DOMINANCE TYPE Typha latifolia, WATER REGIME Permanently Flooded, WATER CHEMISTRY Fresh, SPECIAL MODIFIER Impounded. Persistent emergents such as these cattails remain standing at least until the beginning of the next growing season. Note that the adjacent lake is ice-covered at the time of photography. (Knox County, Maine; April 1978 ; Photo by P. B. Reed)

Plate 58.-Classification : SYSTEM Palustrine, CLASS Emergent Wetland, SUBCLASS Persistent, DOMINANCE TYPE Scirpus robustus-Scirpus acutus, WATER REGIME Semipermanently Flooded, WATER CHEMISTRY Mixosaline, SOIL Mineral. (Stutsman County, North Dakota; August 1962 ; Photo by R. E. Stewart)

Plate 59.-Classification: SYSTEM Palustrine, CLASS Emergent Wetland, SUBCLASS Persistent, DOMINANCE TYPE Cladiumjamaicense, WATER REGIME Semipermanently Flooded, WATER CHEMISTRY Fresh-Circumneutral, SOIL Organic. This photo was taken in the Florida Everglades. (Dade County, Florida; December 1975 ; Photo by V. Carter)

105 Plate 60.-Classification: SYSTEM Palustrine, CLASS Emergent Wetland, SUBCLASS Persistent, DOMINANCE TYPE Carex lasiocar-pa, WATER REGIME Seasonally Flooded, WATER CHEMISTRY Fresh-Circumneutral, SOIL Organic. Subordinate plants include sedges (Carex lacustris, C. rostrata), water smartweed (Polygonum amphibium), bladderwort (Utricularia macrorhiza), bluejoint (Calamagrostis canadensis), and pondweed (Potamogeton gramineus). (Chippewa National Forest, Beltrami County, Minnesota ;

June 1972 ; Photo by J. H. Richmann)

Plate 61.-Classification : SYSTEM Palustrine, CLASS Emergent Wetland, SUBCLASS Persistent, DOMINANCE TYPE Eleocharis palustris, WATER REGIME Seasonally Flooded, WATER CHEMISTRY Polysaline, SOIL Mineral. Subordinate plants include water smartweed (Polygonum amphibium), slough sedge (Carex atherodes), andfoxtail (Alopecurus aequalis). (Stutsman County, North Dakota ;

August 1962 ; Photo by R. E. Stewart)

Plate 62.-Classification : SYSTEM Palustrine, CLASS Emergent Wetland, SUBCLASS Persistent, WATER REGIME Seasonally Flooded, WATER CHEMISTRY Mixosaline, SOIL Mineral. The principal plants are sedges (Carex spp.), bulrushes (Scirpus spp.), rushes (Jun-cus spp.), and foxtail (Alopecurus aequalis). This wetland is typical of irrigated hay in the West. Water may be diverted from rivers or may come from artesian wells as in this photo. (Saguache County, Colorado ; Photo by R. M. Hopper)

Plate 63.-Classification : SYSTEM Palustrine, CLASS Emergent Wetland, SUBCLASS Persistent, DOMINANCE TYPE Carex rarifora-Eriophorum russeolum, WATER REGIME Seasonally Flooded, WATER CHEMISTRY Fresh. Subordinate plants include marsh cinque-foil (Potentilla palustris), bluejoint (Calamagrostis canadensis), Alaska bog willow (Salixfuscescens), crowberry (Empetrum nigrum),

dwarf birch (Betula nana), and peat moss (Sphagnum sp.). This type of patterned wetland is commonly referred to as "string bog" or "strangmoor." Seasonally flooded troughs alternate with elongated bog-like ridges or "strings." Strings here rise only 30-45 cm (12-18 in) above the troughs. (Manokinak River area, Yukon-Kuskokwim Delta, Alaska

July 1985 ; Photo by F. C. Golet)

Plate 64.-Classification : SYSTEM Palustrine, CLASS Emergent Wetland, SUBCLASS Persistent, DOMINANCE TYPE Colocasia esculenta, WATER REGIME Seasonally Flooded, WATER CHEMISTRY Fresh, SOIL Mineral, SPECIAL MODIFIER Farmed. This photograph il-lustrates a Hawaiian taro field. (Kauai County, Hawaii ; September 1972 ; Photo by E. Krider)

Plate 65.-Classification (foreground) : SYSTEM Palustrine, CLASS Emergent Wetland, SUBCLASS Persistent, DOMINANCE TYPE Aristida stricta, WATER REGIME Saturated, WATER CHEMISTRY Fresh-Acid, SOIL Mineral. Subordinate plants include beak rushes (Rhyn-chospora spp.), longleaf pine (Pines palustris), orchids (Habenaria spp.), yellow-eyed grasses (Xyris spp.), grass pinks (Calopogon spp.), and foxtail clubmoss (Lycopodium alopecuroides). (Brunswick County, North Carolina ; December 1975 ; Photo by V. Carter)

Plate 66.-Classification: SYSTEM Palustrine, CLASS Emergent Wetland, SUBCLASS Persistent, WATER REGIME Saturated, WATER CHEMISTRY Fresh. The dominant plants in this montane meadow are sedges (Carex spp.). (Lassen County, California; August 1975

Photo by V. Carter)

Plate 67.-Classification : SYSTEM Palustrine, CLASS Emergent Wetland, SUBCLASS Persistent, DOMINANCE TYPE Eriophorum vaginatum, WATER REGIME Saturated, WATER CHEMISTRY Fresh, SOIL Mineral. Subordinate plants include: netleaf willow (Salix reticulate), diamondleaf willow (S. planifolia), dryas (Dryas integrifolia), bistort ( Polygonum bistorta), lousewort (Pedicularis sp.), chickweed (Stellaria sp.), and lapland cassiope (Cassiope tetragona). This type of wetland, referred to by Walker (1983) as "moist tussock sedge dwarf shrub tundra," covers much of the North Slope of Alaska. At this site, permafrost lies within 15 cm (6 in) ofthe surface. All of the land in this photo is wetland. (Franklin Bluffs, North Slope Borough, Alaska ; July 1985 ; Photo by F. C. Golet)

Plate 68.-Classification : SYSTEM Palustrine, CLASS Emergent Wetland, SUBCLASS Persistent, DOMINANCE TYPE Carex aquatilis, WATER REGIME Saturated, WATER CHEMISTRY Fresh. Subordinate plants include : narrowleaf Labrador tea (Ledum decumbens),

dwarf birch (Betula nana), small cranberry (Vaccinium oxycoccos), crawberry (Empetrum nigrum), peat moss (Sphagnum spp.),

and foliose lichens. (Narokachik River area, Yukon-Kuskokwim Delta, Alaska; July 1985 ; Photo by F. C. Golet)

Plate 69.-Classification: SYSTEM Palustrine, CLASS Emergent Wetland, SUBCLASS Persistent, WATER REGIME Temporarily Flooded, WATER CHEMISTRY Oligosaline, SOIL Mineral, SPECIAL MODIFIER Farmed. All natural vegetation in this wetland has been removed, and water stands in stubble from the previous year's wheat crop. (Stutsman County, North Dakota; March 1967; Photo by H. A.

Kantrud)

Plate 70.-Classification : SYSTEM Palustrine, CLASS Emergent Wetland, SUBCLASS Persistent, WATER REGIME Temporarily Flooded, WATER CHEMISTRY Fresh, SOIL Mineral, SPECIAL MODIFIER Farmed. Principal plants include nut sedge (Cyperus sp.), arrow arum (Peltandra virginica), and barnyard grass (Echinochloa crusgalli). (Dade County, Florida; January 1978 ; Photo by P. B. Reed)

Plate 71.-Two habitats are shown here. Classification of darker zone (edge of water body): SYSTEM Palustrine, CLASS Emergent Wetland, SUBCLASS Nonpersistent, DOMINANCE TYPE Arctophila fulva, WATER REGIME Permanently Flooded, WATER CHEMISTRY Fresh. Classification of lighter zone (foreground): SYSTEM Palustrine, CLASS Emergent Wetland, SUBCLASS Persistent, DOMINANCE TYPE Carex aquatilis, WATER REGIME Seasonally Flooded, WATER CHEMISTRY Fresh. Marsh marigold (Caltha palustris) is also present in the seasonally flooded zone. This wetland lies on coastal tundra within 2 km (1.2 mi) of the Arctic Ocean. (Between Canning and Kavik Rivers, North Slope Borough, Alaska ; July 1985 ; Photo by F. C. Golet)

Plate 72.-Classification : SYSTEM Palustrine, CLASS Emergent Wetland, SUBCLASS Nonpersistent, DOMINANCE TYPE Hippuris tetraphylla, WATER REGIME Permanently Flooded, WATER CHEMISTRY Fresh. A semipermanently flooded persistent-emergent wetland dominated by sedge (Carex lyngbyei) surrounds the Hippuris marsh. Burreed (Sparganium hyperboreum) grows in shallow water between the Hippuris and the sedges. (Narokachik River area, Yukon-Kuskokwim Delta, Alaska; July 1985 ; Photo by F. C

. Golet)

Plate 73.-Classification : SYSTEM Palustrine, CLASS Emergent Wetland, SUBCLASS Nonpersistent, DOMINANCE TYPE Nuphar luteum, WATER REGIME Semipermanently Flooded, WATER CHEMISTRY Fresh. The principal subordinate plant is common duckweed (Lemna minor). (Cass County, Michigan; May 1985 ; Photo by F. C. Golet)

Plate 74.-Classification : SYSTEM Palustrine, CLASS Scrub-Shrub Wetland, SUBCLASS Broad-leaved Deciduous, WATER REGIME Seasonally Flooded, WATER CHEMISTRY Fresh-Acid, SOIL Organic. The dominant plants are willows (Salix spp.). Subordinate species include Sitka spruce (Picea sitchensis) and lodgepole pine (Pines contorta). (Coos County, Oregon ; May 1977 ; Photo by D. D

. Peters)

Plate 75.-Classificaton: SYSTEM Palustrine, CLASS Scrub-Shrub Wetland, SUBCLASS Broad-leaved Deciduous, DOMINANCE TYPE Betula nana, WATER REGIME Saturated, WATER CHEMISTRY Fresh, SOIL Mineral. Subordinate plants include cotton grass (Eriophorum vaginatum), peat moss (Sphagnum spp.), cloudberry (Rebus chamaemorus), mountain cranberry (Vaccinium vitis-idaea), and narrowleaf Labrador tea (Ledum decumbens). Shrubs here are less than 20 cm (8 in) tall. This area of moist tundra is underlain by permafrost at a depth of 45 cm (18 in). (Vicinity of Toolik Lake, North Slope Borough, Alaska ; July 1985 ; Photo by F. C. Golet)

Plate 76.-Classification : SYSTEM Palustrine, CLASS Scrub-Shrub Wetland, SUBCLASS Broad-leaved Deciduous, DOMINANCE TYPE Alnus tenuifolia, WATER REGIME Temporarily Flooded, WATER CHEMISTRY Fresh, SOIL Mineral. Subordinate plants include feltleaf willow (Salix alaxensis) and balsam poplar (Populus balsamifera). Shrubs are nearly 6 m (20 ft) tall, the height that separates Scrub-Shrub from Forested Wetland. This site is flooded only for brief periods after snowmelt and during times of most rapid melting of nearby glaciers. (Tanana River, Fairbanks North Star Borough, Alaska ; July 1985 ; Photo by F. C. Golet)

122 Plate 77.-Classification : SYSTEM Palustrine, CLASS Scrub-Shrub Wetland, SUBCLASS Needle-leaved Deciduous, DOMINANCE TYPE Larix laricina, WATER REGIME Seasonally Flooded, WATER CHEMISTRY Fresh. The tamarack saplings are 2-3 m (6.6-10 ft) tall and cover 40-45% of the site. Subordinate plants include : dwarf birch (Betula nana), bluejoint (Calamagrostis canadensis), black spruce (Picea mariana), leatherleaf (Chamaedaphne calyculata), diamondleaf willow (Salix planifolia), narrowleaf Labrador tea (Ledum decumbens), cotton grass (Eriophorum sp.), bog blueberry (Vaccinium uliginosum), marsh cinquefoil (Potentillapalustris),

and shrubby cinquefoil (P. fruticosa). (Vicinity of Big Delta, Alaska ; July 1985 ; Photo by F. C

. Golet)

Plate 78.-Classification : SYSTEM Palustrine, CLASSScrub-Shrub Wetland, SUBCLASS Broad-leaved Evergreen, DOMINANCE TYPE Ledum groenlandicum-Kalmia angustifolia-Chamaedaphne calyculata, WATER REGIME Saturated, WATER CHEMISTRY Fresh-Acid, SOIL Organic. Subordinate plants include peat moss (Sphagnum spp.), crowberry (Empetrum nigrum), cloudberry (Rubes chamaemorus), and black spruce (Picea mariana). (Washington County, Maine; June 1976 ; Photo by V. Carter)

124 Plate 79.-Classification : SYSTEM Palustrine, CLASS Scrub-Shrub Wetland, SUBCLASS Broad-leaved Evergreen, DOMINANCE TYPE Ledum decumbens, WATER REGIME Saturated, WATER CHEMISTRY Fresh, SOIL Mineral. Subordinate species include : cloudberry (Rubes chamaemorus), mountain cranberry (Vaccinium vitis-idaea), craneberry (Empetrum nigrum), dwarf birch (Betula nana),

reindeer moss (Cladina spp.), sedge (Carex aquatilis), bluejoint(Calamagrostis canadensis), and Alaska spiraea (Spiraea beauver-diana). Shrubs are less than 20 cm (8 in) tall

. Although this site looks like a dry heath, permafrost at a depth of only 15-20 cm (6-8 in) keeps the soil saturated near the surface throughout the growing season. (Talik River area, Yukon-Kuskokwim Delta, Alaska ; July 1985 ; Photo by F. C

. Golet)

Plate 80.-Classification : SYSTEM Palustrine, CLASS Scrub-Shrub Wetland, SUBCLASS Broad-leaved Evergreen, DOMINANCE TYPE Cyrilla racemiflora, WATER REGIME Saturated, WATER CHEMISTRY Fresh-Acid, SOIL Organic. Subordinate plants include : honeycup (Zenobia pulverulenta), leatherleaf (Chamaedaphne calyculata), peat moss (Sphagnum spp.), highbush blueberry (Vaccinium corym-bosum), loblolly bay (Gordonia lasianthus), pondpine (Pines serotina), and highbush blueberry (Vaccinium corymbosum). Locally, these wetlands are referred to as evergreen shrub bogs or "pocosins." (Brunswick County, North Carolina; December 1975 ; Photo by V. Carter)

126 Plate 81.-Classification: SYSTEM Palustrine, CLASS Scrub-Shrub Wetland, SUBCLASS Needle-leaved Evergreen, DOMINANCE TYPE Picea mariana, WATER REGIME Saturated, WATER CHEMISTRY Fresh. Subordinate plants include : dwarf birch (Betula nana), cotton grass (Eriophorum vaginatum), bog blueberry (Vaccinium uliginosum), Labrador tea (Ledum groenlandicum), and peat moss (Sphagnum spp.). This wetland type, commonly known as "muskeg," is abundant in the forested regions of Alaska ; it also occurs in northern New England and in the Great Lakes States

. (Vicinity of Coldfoot, Alaska ; July 1985 ; Photo by F. C. Golet)

127 Plate 82.-Classification: SYSTEM Palustrine, CLASS Forested Wetland, SUBCLASS Broad-leaved Deciduous, DOMINANCE TYPE Acer rubrum, WATER REGIME Saturated, WATER CHEMISTRY Fresh-Acid, SOIL Organic. Subordinate plants in this red maple swamp include black gum (Nyssa sylvatica), highbush blueberry (Vaccinium corymbosum), great laurel (Rhododendron maximum), and winterberry (Ilex verticillata). (Washington County, Rhode Island ; June 1977 ; Photo by F. C. Golet)

128 Plate 83.-Two habitats are shown here. Classification ofthe forested area : SYSTEM Palustrine, CLASS Forested Wetland, SUBCLASS Needle-leaved Deciduous, DOMINANCE TYPE Taxodium distichum, WATER REGIME Permanently Flooded, WATER CHEMISTRY Fresh.

Classification of the open area : SYSTEM Palustrine, CLASS Aquatic Bed, SUBCLASS Floating Vascular, DOMINANCE TYPE Pistia stratiotes, WATER REGIME Permanently Flooded, WATER CHEMISTRY Fresh. Emergent plants growing in the bed of water lettuce are arrowheads (Sagittaria spp.). (Corkscrew Swamp Sanctuary, Collier County, Florida ; January 1978 ; Photo by E. T. LaRoe)

129 Plate 84.-Classification : SYSTEM Palustrine, CLASS Forested Wetland, SUBCLASS Needle-leaved Evergreen, DOMINANCE TYPE Chamaecyparis thyoides, WATER REGIME Seasonally Flooded, WATER CHEMISTRY Fresh-Acid, SOIL Organic. Subordinate plants in this Atlantic white cedar swamp include : highbush blueberry (Vaccinium corymbosum), winterberry (Ilex verticillata), red maple (Acer rubrum), and peat moss (Sphagnum spp.). Low vegetation in the foreground includes leatherleaf (Chamaedaphne calyculata) and Virginia chain-fern (Woodwardia virginica). (Washington County, Rhode Island ; July 1977 ; Photo by F. C. Golet)

Plate 85.-Classification : SYSTEM Palustrine, CLASS Forested Wetland, SUBCLASS Needle-leaved Evergreen, DOMINANCE TYPE Picea mariana, WATER REGIME Saturated, WATER CHEMISTRY Fresh, SOIL Mineral. Subordinate plants in this black spruce forest in-clude Labrador tea (Ledum groenlandicum), mountain cranberry (Vaccinium vitis-idaea), crawberry (Empetrum nigrum), and peat moss (Sphagnum sp.). Permafrost is present within 45 cm (18 in) of the surface. (Vicinity of Glennallen, Alaska ; July 1985 ;

Photo by F. C. Golet)

Plate 86.-Classification : SYSTEM Palustrine, CLASS Forested Wetland, SUBCLASS Dead, WATER REGIME Permanently Flooded, WATER CHEMISTRY Fresh-Circumneutral, SOIL Mineral, SPECIAL MODIFIER Impounded. (Humphreys County, Tennessee ; September 1975 ; Photo by V. Carter)

U.S. GOVERNMENT PRINTING OFFICE : 1992-318-224

As the Nation's principal conservation agency, the Department of the Interior has responsibility for most of our nationally owned public lands and natural resources. This includes fostering the wisest use of our land and water resources, protecting our fish and wildlife, preserving the environmental and cultural values of our national parks and historical places, and providing for the enjoyment of life through outdoor recreation. The Department assesses our energy and mineral resources and works to assure that their develop-ment is in the best interests of all our people. The Department also has a major responsibility for American Indian reservation communities and for peo-ple who live in island territories under U.S. administration.

U.S. Department of the Interior Fish and Wildlife Service Washington, D.C. 20240 POSTAGE AND FEES PAID U. S. DEPARTMENT OF THE INTERIOR INT-423 U.&MAIL