Biological Services Program FWS/OBS-79/31 DECEMBER 1979 Classification of Wetlands and Deepwater Habitats of the United States QH 104 h and Wildlife Service C68 c# 2 >• Department of the Interior 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, par- ticularly with respect to environmental impact assessment. 2. To gather, analyze, and present information that will aid decision- makers in the identification and resolution of problems asso- ciated 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 decisionmakers 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 arrange for contracting of Biological Services studies with States, universities, consulting 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. c- FWS/OBS-79/31 December 1979 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 Forest and Wildlife Management University of Rhode Island Kingston, Rhode Island 02881 and Edward T. LaRoe U.S. National Oceanic and Atmospheric Administration Office of Coastal Zone Management Washington, D.C. 20235 Performed for Office of Biological Services Fish and Wildlife Service U.S. Department of the Interior Washington, D.C. 20240 For sale by the Superintendent of Documents, U.S. Government Printing Office Washington. D.C. 20402 Stock Number GPO 024-010-00524-6 1 I 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 Foreword 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 functions. Increasing national and international recognition of these values has intensified the need for reliable information on the status and extent 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 developing wetland data base utilizing this system will result in ac- ceptance 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 in Contents Page Abstract 1 Wetlands and Deepwater Habitats i 3 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 9 Lacustrine System 11 Palustrine System 12 Classes, Subclasses, and Dominance Types 12 Rock Bottom 15 Unconsolidated Bottom 15 Aquatic Bed 16 Reef 17 Streambed 18 Rocky Shore 19 Unconsolidated Shore 20 Moss-Lichen Wetland 21 Emergent Wetland 21 Scrub-Shrub Wetland 22 Forested Wetland 22 Modifiers 23 Water Regime Modifiers 23 Water Chemistry Modifiers 24 Salinity Modifiers 24 pH Modifiers 25 Soil Modifiers 25 Special Modifiers 25 Regionalization for the Classification System 26 Use of the Classification System 28 Hierarchical Levels and Modifiers 29 Relationship to Other Wetland Classifications 29 Acknowledgments 32 References 33 Appendix A. Scientific and common names of plants 37 Appendix B. Scientific and common names of animals 40 Appendix C. Glossary of terms 42 Appendix D. Criteria for distinguishing organic soils from mineral soils 44 Appendix E. Artificial key to the systems 46 Artificial key to the classes 46 Tables No. 1 Systems, classes, and subclasses with examples of dominance types. 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. Figures 1 Classification hierarchy of wetlands and deepwater habitats, showing systems, subsystems, 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 Forest and Wildlife Management University of Rhode Island, Kingston, Rhode Island 02881 and Edward T. LaRoe 1 U.S. National Oceanic and Atmospheric Administration Office of Coastal Zone Management, Washington, D.C. 20235 Abstract This classification, to be used in a new inventory of wetlands and deepwater habitats of the 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. Eco- logically 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, Subtidal and Intertidal; the Riverine system has four subsystems, Tidal, Lower Perennial, Upper Perennial, and Intermittent; the Lacustrine has two, Littoral and Limnetic; and the Palustrine has no subsystem. 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 sub- systems. Six classes are based on substrate and flooding regime: (1) Rock Bottom with a sub- strate 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 substrate as Rock Bottom; (4) Unconsolidated Shore with the same substrate 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 Stream- bed 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. 'Present address: Department of Environmental Regulations, 2562 Executive Center Circle, East Mont- gomery Building, Tallahassee, Florida 32301. 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, six 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 combines 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 gathering may be prerequisite to classification. Development of rules by the user will be required for specific map scales. Dominance types and relationships of plant and animal com- munities 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 inventory of the wetlands of the United States (Shaw and Fredine 1956) in 1954. Since then, wetlands have undergone considerable change, both natural and man- related, and their characteristics and natural values have become better defined and more widely known. During this interval. 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 purpose of the 1954 inventory was to assess the amount and types of valuable waterfowl habitat, the scope of the new project is considerably broader (Mon- tanari 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 Circular has been one of the most common and most influential 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 criti- cal differences, such as the distinction between fresh and mixosaline inland wetlands but also placed dis- similar habitats, such as forests of boreal black spruce {Picea mariana) and of southern cypress-gum (Taxo- dium distiehum-Nyssa aquatica) in the same category, with no provisions in the system for distinguishing be- tween them. Because of the central emphasis on water- fowl habitat, far greater attention was paid to vege- tated 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 deepwater habitats have been developed (Stewart and Kantrud 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 would fully 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 national inventory. The new classifi- cation, 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 deci- sions about resource management; (3) to furnish units for inventory and mapping; and (4) to provide uni- formity 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 taxo- nomic dispute. Many of the terms used in this classifi- cation have various meanings even in the scientific lit- erature 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 be- tween dry and wet environments lies along a con- tinuum. Because reasons or needs for defining 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 purposes of inventory, evaluation, and management. Wetlands In general terms, wetlands are lands where satura- tion with water is the dominant factor determining the nature of soil development and the types of plant and animal communities 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 sat- urated 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. For purposes of this classification wetlands must have one or more of the following three attri- butes: (1) at least periodically, the land supports predominantly hydrophytes; 2 12) the substrate is pre- dominantly undrained hydric soil; 3 and (3) the substrate is nonsoil and is saturated with water or covered bv shallow water at some time during the growing season of each year. The term wetland includes a variety of areas that fall into one of five categories: (1) areas with hydrophytes and hydric soils, such as those commonly known as marshes, swamps, and bogs; (2) areas without hydro- phytes but with hydric soils— for example, flats where 2 The U.S. Fish and Wildlife Service is preparing a list of hydrophytes and other plants occurring in wetlands of the United States. 3 The U.S. Soil Conservation Service is preparing a pre- liminary list of hydric soils for use in this classification system. drastic fluctuation in water level, wave action, tur- bidity, or high concentration of salts may prevent the growth of hydrophytes; (3) areas with hydrophytes but nonhydric soils, such as margins of impoundments or excavations where hydrophytes have become estab- lished 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 sup- porting 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 identified under other categories in some land-use classifications. For example, wetlands and farmlands are not necessarily exclusive. Many areas that we define as wetlands 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 Deepwater Habitats are permanently flooded lands lying below the deepwater boundary of wetlands. Deepwater habitats include environments where sur- face 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 domi- nant plants are hydrophytes; however, the substrates are considered nonsoil because the water is too deep to support emergent vegetation (U. S. Soil Conserva- tion Service, Soil Survey Staff 1975). Wetlands and Deepwater Habitats are defined sepa- rately because traditionally the term wetland has not included deep permanent water; however, both must be considered in an ecological approach to classifi- cation. We define five major systems: Marine, Estua- rine, Riverine, Lacustrine, and Palustrine. The first four of these include both wetland and deepwater habitats but the Palustrine includes only wetland habitats. Limits The upland limit of wetland is designated as (1) the boundary between land with predominantly hydro- phytic cover and land with predominantly mesophytic or xerophytic cover; (2) the boundary between soil that is predominantly hydric and soil that is predominantly nonhydric; or (3) in the case of wetlands without vege- tation or soil, the boundary between land that is flooded or saturated at some time 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; permanently flooded areas are considered deep- water habitats in these systems. The boundary be- tween wetland and deepwater habitat in the Riverine, Lacustrine, and Palustrine 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 emergent plants normally grow (Welch 1952; Zhadin and Gerd 1963; Sculthorpe 1967). As Daubenmire (1968:138) stated, emergents are not true aquatic plants, but are "amphibious," growing in both perma- nently 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 domi- nance types. Figure 1 illustrates the classification structure to the class level. Table 1 lists the classes and subclasses for each system and gives an example of a dominance type for each subclass. 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 deep- water 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, chem- ical, or biological factors. We further subdivide systems into more specific categories called SUBSYSTEMS. The characteristics of the five major systems- Marine, Estuarine, Riverine, Lacustrine, and Palus- trine— have been discussed at length in the scientific literature and the concepts are well recognized; how- ever, there is frequent disagreement as to which attri- butes 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 of the 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 associated 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 %o, with little or no dilution except outside the mouths of estuaries. Shallow coastal indentations or bays without appreciable freshwater 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 emergents, trees, or shrubs; or (3) the seaward limit of the Estuarine System, where this limit is determined by factors other than vegetation. Deepwater habitats lying beyond the seaward limit of the Marine System are outside 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 sub- strate; (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. Subtidai— The substrate is continuously sub- merged. 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 freshwater runoff from the land. The salin- ity may be periodically increased above that of the System Subsystem Class go E- < 5 < OS w E- < 63" 63 Q Q z < CO D Z < ►J 63 - Marine - -Subtidal- • Intertidal - -Estuarine- -Subtidal- - Intertidal - — Riverine - - Tidal - - Lower Perennial - -Upper Perennial - -Intermittent - -Lacustrine- - Limnetic ■ - Littoral - I — Palustrine- — Rock Bottom — Unconsolidated Bottom — Aquatic Bed I— Reef — Aquatic Bed — Reef — Rocky Shore — Unconsolidated Shore -Rock Bottom -Unconsolidated Bottom -Aquatic Bed -Reef • Aquatic Bed -Reef - Streambed - Rocky Shore - Unconsolidated Shore - Emergent Wetland - Scrub-Shrub Wetland - Forested Wetland - Rock Bottom - Unconsolidated Bottom - Aquatic Bed - Rocky Shore - Unconsolidated Shore - Emergent Wetland -Rock Bottom - Unconsolidated Bottom -Aquatic Bed -Rocky Shore - Unconsolidated Shore - Emergent Wetland - Rock Bottom -Unconsolidated Bottom - Aquatic Bed - Rocky Shore -Unconsolidated Shore -Streambed ERock Bottom Unconsolidated Bottom Aquatic Bed -Rock Bottom -Unconsolidated Bottom -Aquatic Bed - Rocky Shore - Unconsolidated Shore - Emergent Wetland -Rock Bottom - Unconsolidated Bottom -Aquatic Bed -Unconsolidated Shore - Moss-Lichen Wetland -Emergent Wetland -Scrub-Shrub Wetland - Forested Wetland Fig. 1. Classification hierarchy of wetlands and deepwater habitats, showing systems, subsystems, and classes. The Palus- trine System does not include deepwater habitats. Table 1. Systems, Classes, and Subclasses with Examples of Dominance Types. System, Class, and Subclass Examples of Dominance Types Marine Rock Bottom Bedrock Rubble Unconsolidated Bottom Cobble-Gravel Sand Mud Organic Aquatic Bed Rooted Vascular Algal Reef Coral Worm Rocky Shore Bedrock Rubble Unconsolidated Shore Cobble-Gravel Sand Mud Organic Estuarine Rock Bottom Bedrock Rubble Unconsolidated Bottom Cobble-Gravel Sand Mud Organic Aquatic Bed Algal Rooted Vascular Floating Reef Mollusk Worm Streambed Cobble-Gravel Sand Mud Organic Rocky Shore Bedrock Rubble Unconsolidated Shore Cobble-Gravel Sand Mud Organic Emergent Wetland Persistent Nonpersistent Scrub-Shrub Wetland Needle-leaved Evergreen Broad-leaved Evergreen Needle-leaved Deciduous Broad-leaved Deciduous Dead American lobster {Homarus americanus) Encrusting sponge {Hippospongia gossypina) Brittle star (Amphipholis squamata) Great Alaskan tellin {Tellina lutea) Atlantic deep-sea scallop {Placopecten magellanicus) Clam worm {Nereis succinea) Turtle grass {Thalassia testudinum) Kelp {Maerocystis pyrifera) Coral {Pontes pontes) Reef worm {Sabellaria cementarium) Gooseneck barnacle {Pollicipes polymerus) California mussel {Mytilus californianus) Acorn barnacle {Balanus balanoides) Pismo clam {Tivela stultorum) Boring clam {Platyodon cancellatus) False angel wing {Petricola pholadiformis) Sea whip {Muricea californica) Tunicate {Cnemidocarpa finmarkiensis) Smooth Washington clam {Saxidomus giganteus) Sand dollar {Dendraster excentricus) Baltic macoma {Maeoma balthica) Soft-shell clam {Mya arenaria) Rockweed \Fueus vesiculosus) Eelgrass {Zostera marina) Water hyacinth {Eichhornia crassipes) Eastern oyster {Crassostrea virginica) Reef worm {Sabellaria floridensis) Blue mussel {Mytilus edulis) Red ghost shrimp {Callianassa californiensis) Mud snail (Nassarius obsoletus) Ribbed mussel {Modiolus demissus) Acorn barnacle {Chthamalus fragilis) Plate limpet {Acmaea testudinalis) Blue mussel {Mytilus edulis) Quahog {Mercenaria mercenaria) Clam worm {Nereis succinea) Fiddler crab {Uca pugnax) Saltmarsh cordgrass {Spartina alterniflora) Samphire {Salicornia europea) Sitka spruce {Picea sitchensis) Mangrove {Conocarpus erectus) Bald cypress {Taxodium distichum) Marsh elder {Iva frutescens) None Table 1. Continued. System, Class, and Subclass Examples of Dominance Types Forested Wetland Needle-leaved Evergreen Broad-leaved Evergreen Needle-leaved Deciduous Broad-leaved Deciduous Dead Riverine Rock Bottom Bedrock Rubble Unconsolidated Bottom Cobble-Gravel Sand Mud Organic Aquatic Bed Algal Aquatic Moss Rooted Vascular Floating Streambed Bedrock Rubble Cobble-Gravel Sand Mud Organic Vegetated Rocky Shore Bedrock Rubble Unconsolidated Shore Cobble-Gravel Sand Mud Organic Vegetated Emergent Wetland (Nonpersistent) Lacustrine Rock Bottom Bedrock Rubble Unconsolidated Bottom Cobble-Gravel Sand Mud Organic Aquatic Bed Algal Aquatic Moss Rooted Vascular Floating Rocky Shore Bedrock Rubble Unconsolidated Shore Cobble-Gravel Sand Mud Sitka spruce {Picea sitchtnsis) Red mangrove (Rhizophora mangle) Bald cypress (Taxodium distichum) Red ash (Fraxinus pennsylvanica) None Brook leech {Helobdella stagnalis) Water penny (Psephenus herricki) Mayfly (Baetis sp.) Freshwater mollusk (Anodonta implicata) Freshwater mollusk [Anodontoides ferussacianus) Sewage worm (Tubifex tubifex) Stonewort (Nitella flexilis) Moss (Fissidens adiantoides) Riverweed {Podostemum ceratophyllum) Bladderwort {Utricularia vulgaris) Mayfly {Ephemerella defieiens) Fingernail clam (Pisidium abditum) Tadpole snail {Physa gyrina) Pond snail {Lymnaea cubensis) Pouch snail {Aplexa hypnorum) Oligochaete worm (Limnodrilus hoffmeisteri) Old witch grass (Panicum capillare) Liverwort (Marsupella emarginata) Lichen {Dermatoearpon fluviatile) Freshwater mollusk (Elliptio arctata) Freshwater mollusk (Anodonta cataracta) Crayfish (Procambarus simulans) Harpacticoid copepod (Canthocamptus robertcokeri) Cocklebur (Xanthium strumarium) Horsetail (Equisetum fluviatile) Freshwater sponge {Spongilla lacustris) Brook leech (Helobdella stagnalis) Freshwater mollusk (Lampsilis ovata) Fingernail clam (Sphaerium simile) Fingernail clam (Pisidium ferrugineum) Sewage worm (Tubifex tubifex) Stonewort (Chara crispa) Moss (Fontinalis antipyretica) Widgeon grass (Ruppia maritima) Duckweed (Lemna minor) Caddisfly (Hydropsyehe simulans) Freshwater mollusk (Pisidium abditum) Leech (Erpobdella punctata) Freshwater mollusk (Elliptio dariensis) Pond snail (Lymnaea palustris) Table 1. Continued. System, Class, and Subclass Examples of Dominance Types Organic Vegetated Emergent Wetland (Nonpersistent) Palustrine Rock Bottom Bedrock Rubble Unconsolidated Bottom Cobble-Gravel Sand Mud Organic Aquatic Bed Algal Aquatic Moss Rooted Vascular Floating Unconsolidated Shore Cobble-Gravel Sand Mud Organic Vegetated Moss- Lichen Wetland Moss Lichen Emergent Wetland Persistent Nonpersistent Scrub-Shrub Wetland Broad-leaved Deciduous Needle-leaved Deciduous Broad-leaved Evergreen Needle-leaved Evergreen Dead Forested Wetland Broad-leaved Deciduous Needle-leaved Deciduous Broad-leaved Evergreen Needle-leaved Evergreen Dead Midge larvae (Chironomus spp.) Goosefoot (Chenopodium rubrum) Pickerel weed (Pontederia cordata) Horse sponge (Heteromeyenia latitenta) Pond snail {Lymnaea stagnalis) Freshwater sponge {Eunapius fragilis) Freshwater mollusk (Elliptio complanata) Fingernail clam (Pisidium casertanum) Oligochaete worm {Limnodrilus hoffmeisteri) Stonewort (Chara aspera) Moss (Fissidens julianus) White water lily {Nymphaea odorata) Water fern (Salvinia rotundifolia) Toad bug {Gelastocoris oculatus) Freshwater mollusk (Elliptio dariensis) Crayfish (Fallicambarus fodiens) Back swimmer (Notonecta lunata) Summer cypress (Kochia scoparia) Peat moss [Sphagnum fuscum) Reindeer moss (Cladonia rangiferina) Common cattail (Typha latifolia) Arrow-arum (Peltandra virginica) Speckled alder (Alnus rugosa) Tamarack (Larix laricina) Coastal sweetbells (Leucothoe axillaris) Atlantic white cedar (Chamaecyparis thyoides) None Red maple [Acer rubrum) Bald cypress (Taxodium distichum) Sweet bay (Magnolia virginiana) Black spruce (Picea mariana) None open ocean by evaporation. Along some low-energy coastlines there is appreciable dilution of sea water. Offshore areas with typical estuarine plants and animals, such as red mangroves (Rhizophora mangle) and eastern oysters (Crassostrea virginica), are also included in the Estuarine System. 1 4 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 of the Great Lakes." However, in the present system we do not consider areas of the Great Lakes as estuarine. Limits. The Estuarine System extends (1) upstream and landward to where ocean-derived salts measure less than 0.5 °/oo 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 off- shore areas of continuously 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 consid- ered 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 woanmu t-n UPLAND MARINE INTERTIDAL -« l»-i SUBTIDAL -* — — *- INTERTIDAL -^ — — *- -« — SUBTIDAL — ►— a c D Q UNCONSOLIDATED SHORE (Beach) UNCONSOLIDATED BOTTOM ii UNCONSOLIDATED SHORE (Bar) -+ — a m K => 2 ° £ o ID o z => — ►- m g Continental Slope CO a ^ — — c~^ ELWS d"~ a "d"- a IRREGULARLY FLOODED b REGULARLY FLOODED c IRREGULARLY EXPOSED d SUBTIDAL Fig. 2 Distinguishing features and examples of habitats in the Marine System. EHWS ELWS = extreme low water of spring tides. extreme high water of spring tides; 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 embay- ments 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. Subtidai— The substrate is continuously sub- merged. Intertidal— The substrate is exposed and flooded by tides; includes the associated splash zone. Classes. Rock Bottom, Unconsolidated Bottom, Aquatic Bed, Reef, Streambed, Rocky Shore, Uncon- solidated 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 channel, with two exceptions: (1) wetlands dominated by trees, shrubs, persistent emergents, emergent mosses, or lichens, and (2) habitats with water con- taining ocean-derived salts in excess of 0.5°/oo. A channel is "an open conduit either naturally or arti- ficially 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 domi- nated 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 10 UPLAND ESTUARINE UPLAND ESTUARINE INTERTIDAL -* — — ^n SUBTIDAL -^ *-i INTERTIDAL INTERTIDAL SUBTIDAL -* r EMERGENT WETLAND PERSISTENT UNCONSOLIDATED BOTTOM (Tidal Pond) z < 5 H z S UJ 1 g s UJ 2 UJ - UNCONSOLIDATED SHORE (Beach) AQUATIC BED REEF II 1 i UNCONSOLIDATED BOTTOM t ^SB*^ a ^^ *^^i& •^va^b b -—^^ #*Tr C~^» "d 4i£ ii^£^ 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 tides; ELWS = extreme low water of spring tides. extreme high water of spring end where the concentration of ocean-derived salts in the water exceeds 0.5%o 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 wetlands may occur in the channel, but they are not included in the Riverine System. Palus- trine Forested Wetlands, Emergent Wetlands, Scrub-Shrub Wetlands, and Moss-Lichen Wetlands may occur adjacent to the Riverine System, often on a floodplain. Many biologists have suggested that all the wetlands occurring on the river floodplain should be a part of the Riverine System because they 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 bordering an old river. . . . Often the floodplain may take the form of a very level plain occupied by the present stream channel, and it may never, or only occa- sionally, be flooded. ... It is this subsurface water [the ground water] that controls 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 veloc- ity, substrate, and the extent of floodplain develop- ment. The subsystems have characteristic flora and fauna (see lilies and Botosaneau 1963; Hynes 1970; Reid and Wood 1976). All four subsystems are not necessarily present in all rivers, and the order of occur- rence may be other than that given below. Tidal. —The gradient is low and water velocity fluc- tuates 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 Perennial Subsystem. The floodplain is typically well developed. Lower Perennial.— The gradient is low and water 11 UPLAND fc-i PALUSTRINE -< RIVERINE *- PALUSTRINE UPLAND -« 1 FORESTED WETLAND UNCONSOLIDATED SHORE ii UNCONSOLIDATED BOTTOM ii AQUATIC BED EMERGENT WETLAND^ NONPERSISTENT 1 n EMERGENT WETLAND PERSISTENT " SCRUB-SHRUB f WETLAND 1 ■'.'V, '■".■■ - XV/ l p v lIlM^ HIGH WATER |II\p<»A* \u ij^jt*- i c r AVERAGE WATER c * b e\ ^^, e a TEMPORARILY FLOODED b SEASONALLY FLOODED c SEMIPERMANENTLY FLOODED d INTERMITTENTLY EXPOSED e PERMANENTLY FLOODED Fig. 4. Distinguishing features and examples of habitats in the Riverine System. velocity is slow. There is no tidal influence, and some water flows throughout the year. The substrate con- sists 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 concen- tration 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 Subsystem, and there is very little floodplain development. Intermittent.— In this subsystem, the channel con- tains nontidal flowing water for only part of the year. When the water is not flowing, it may remain in iso- lated pools or surface water may be absent. Classes. Rock Bottom, Unconsolidated Bottom, Aquatic Bed, Streambed, Rocky Shore, Uncon- solidated Shore, and Emergent Wetland (nonper- sistent). Lacustrine System Definition. The Lacustrine System (Fig. 5) includes wetlands and deepwater habitats with all of the fol- lowing characteristics: (1) situated in a topographic depression or a dammed river channel; (2) lacking trees, shrubs, persistent emergents, emergent mosses or lichens with greater than 30% areal coverage; and (3) total area exceeds 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 deep- est part of the basin exceeds 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°/oo. Limits. The Lacustrine System is bounded by upland or by wetland dominated by trees, shrubs, per- 12 Table 2. Salinity modifiers used in this classification system. Coastal modifiers 3 Inland modifiers b Salinity (parts per thousand) Approximate specific conductance (/40 30.0-40 0.5-30 18.0-30 5.0-18 0.5-5 < 0.5 > 60,000 45.000-60,000 800-45,000 30,000-45,000 8,000-30.000 800- 8,000 <800 a Coastal modifiers are used in the Marine and Estuarine systems. b Inland modifiers are used in the Riverine, Lacustrine, and Palustrine systems. c The term Brackish should not be used for inland wetlands or deepwater habitats. sistent emergents, emergent mosses, or lichens. Lacus- trine systems formed by damming a river channel are bounded by a contour approximating the normal spill- way elevation or normal pool elevation, except where Palustrine wetlands extend lakeward of that bound- ary. 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 Supe- rior), intermittent lakes (e.g., playa lakes), and tidal lakes with ocean-derived salinities below 0.5°/oo (e.g., Grand Lake, Louisiana). Typically, there are extensive areas of deep water and there is considerable wave action. Islands of Palustrine wetland may he within the boundaries of the Lacustrine System. Subsystems. Limnetic. — All deepwater habitats within the Lacustrine System; many small Lacustrine systems have no Limnetic Subsystem. Littoral.— AH wetland habitats in the Lacustrine System. Extends from the shoreward boundary of the 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, per- sistent emergents, emergent mosses or lichens, and all such wetlands that occur in tidal areas where salinity due to ocean-derived salts is below 0.5%o. It also in- cludes wetlands lacking such vegetation, but with all of the following four characteristics: (1) area less than 8 ha (20 acres); (2) active wave-formed or bedrock shoreline features lacking; (3) water depth in the deep- est part of basin less than 2 m at low water; and (4) salinity due to ocean-derived salts less than 0.5°/oo. 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 during 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 generally considered separately from the river itself. As an example, Hynes (1970:85) wrote in ref- erence to riverine habitats, "We will not here consider the long list of emergent 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, Emergent Wetland, Scrub-Shrub Wetland, and Forested Wetland. Classes, Subclasses, and Dominance Types The CLASS is the highest taxonomic unit below the subsystem level. It describes the general appearance of the habitat in terms of either the dominant life form i:; a TEMPORARILY FLOODED b SEASONALLY FLOODED c SEMIPERMANENTLY FLOODED d INTERMITTENTLY EXPOSED e PERMANENTLY FLOODED Fig. 5. Distinguishing features and examples of habitats in the Lacustrine System. of the vegetation or the physiography and composition of the substrate— features that can be recognized without the aid of detailed environmental measure- ments. Vegetation is used at two different levels in the classification. The life forms— trees, shrubs, emer- gents, emergent mosses, and lichens— are used to define classes because they are relatively easy to dis- tinguish, do not change distribution rapidly, and have traditionally been used as criteria for classification of wetlands. 5 Other forms of vegetation, such as sub- merged or floating-leaved rooted vascular plants, free- floating vascular plants, submergent mosses, and 5 Our initial attempts to use familiar terms such as marsh, swamp, bog, and meadow at the class level were unsuc- cessful primarily because of wide discrepancies in the use of these 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 misunder- standings and confusion that result from the use of the fa- miliar terms. algae, though frequently more difficult to detect, are used to define the class Aquatic Bed. Pioneer species that briefly 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 advantages: (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 recognizable on a great variety of remote sensing products (e.g., Radforth 1962; Anderson et al. 1976). If vegetation (except pioneer species) covers 30% or more of the substrate, we distinguish classes on the basis of the life form of the plants that con- stitute 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 U UPLAND PALUSTRINE UPLAND PALUSTRINE UPLAND PALUSTRINE UPLAND Seepage Zone a TEMPORARILY FLOODED b SEASONALLY FLOODED c SEMIPERMANENTLY FLOODED d INTERMITTENTLY EXPOSED e PERMANENTLY FLOODED f SATURATED ■HIGH WATER VERAGE WATER LOW WATER Fig. 6. Distinguishing features and examples of habitats in the Palustrine System. 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 Deciduous, 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 variations in geology and the influence of wind, waves, and currents on erosion and deposition of substrate materials. Bottoms, Shores, and Stream- beds are separated on the basis of duration of inun- dation. In the Riverine, Lacustrine, 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 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 aerial coverage of pioneering 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 of the type of organism that formed the reef. The DOMINANCE TYPE is the taxonomic category subordinate to subclass. Dominance types are deter- mined 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 If, 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 of vegetation used to determine the subclass. 6 For example, a Needle-leaved Evergreen Forested Wetland with 70% areal cover of black spruce and 30% areal cover of tamarack (Larix laricina) would be designated as a Picea mariana Dominance Type. When the rela- tive 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 as Typha latifolia-Scirpus acutus Domi- nance Type. When the subclass is based on substrate material, the dominance type is named for the predominant plant or sedentary or sessile macroinvertebrate species, without regard for life form. In the Marine and Estuarine systems, sponges, alcyonarians, mollusks, crustaceans, worms, ascidians, 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 codominant species as a dominance type. Thorson (1957) recom- mended guidelines and suggested definitions for estab- lishing community types and dominants on level bottoms. Rock Bottom 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 determining the abundance, variety, and distribution of organisms. The stability of the bottom allows a rich assemblage of plants and animals to develop. Rock Bottoms are usually high-energy habitats with well- aerated waters. Temperature, salinity, current, and light penetration are also important factors in deter- mining the composition of the benthic community. "Percent areal cover is seldom measured in the application of this system, but the term must be defined in terms of area. We suggest 2 m 2 for herbaceous and moss layers, 16 m ! for shrub layers, and 100 m 2 for tree layers (Mueller-Dombois and EUenberg 1974:74). When percent areal cover is the key for establishing boundaries between units of the classifi- cation, it may occasionally be necessary to measure cover on plots, in order to maintain uniformity of ocular estimates made in the field or interpretations made from aerial photo- graphs. 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 sub- strates between boulders. Plants are also firmly at- tached (e.g., by holdfasts), 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 combi- nation with bedrock, cover 75% or more of the surface. Examples of dominance types for these two sub- classes in the Marine and Estuarine systems are the encrusting sponges Hippospongia, the tunicate Cnemi- docarpa, the sea urchin Strongylocentrotus, the sea star Pisaster, the sea whip Muricea, and the American lobster, Homarus americanus. Examples of Lacus- trine, Palustrine, and Riverine dominance types are the freshwater sponges Spongilla and Heteromeyenia, the pond snail Lymnaea, the mayfly Ephemerella, various midges of the Chironomidae, the caddisfly Hydropsyche, the leech Helobdella, the riffle beetle Psephenus, the chironomid midge Eukiefferiella, 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 in- cludes all wetland and deepwater habitats with at least 25% cover of particles smaller than stones, and a vege- tative cover less than 30%. Water regimes are re- stricted to subtidal, permanently flooded, intermit- tently exposed, and semipermanently flooded. Description. Unconsolidated Bottoms are charac- terized 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. Exposure to wave and current ac- tion, temperature, salinity, and light penetration determine 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, how- ever, algae penetrate the substrate and higher plants 16 can successfully root if wave action and currents are not too strong. Most animals in unconsolidated sedi- ments live within the substrate, e.g., Macoma and the amphjpod 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, Uncon- solidated Bottom communities are relatively stable. They vary from the Arctic to the tropics, depending largely on temperature, and from the open ocean to the upper end of the estuary, depending on salinity. Thorson (1957) summarized and described charac- teristic types of level bottom communities 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 beha- vioral adaptation 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 invertebrate fauna." In Lacus- trine 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 sup- ports 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 dominance types for the Marine and Estuarine systems are the mussels Modiolus and Mytilus, the brittle star Amphipholis, 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-Eu- kiefferiella (Slack et al. 1977), chironomid midge- caddisfly- snail Chironomus-Hy dropsy che-Physa (Krecker and Lancaster 1933), the pond snail Lym- naea, the mayfly Baetis, the freshwater sponge Eunap- ius, the oligochaete worm Lumbriculus, the scud Gam- marus, 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. Examples for the Lacus- trine, 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 inter- mixed. Organisms 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 Platv- odon, the deep-sea scallop Placopecten, the quahog Mercenaria, the macoma Macoma, the echiurid worm Urechis, the mud snail Nassarius, and the sea cucum- ber Thyone. Examples of dominance types for the Lacustrine, Palustrine, and Riverine systems are the sewage worm Tubifex, freshwater mollusks Anodonta, Anodontoides, and Elliptio, the fingernail clams Pisi- dium 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 Estua- rine 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, Palustrine, and Riverine systems are the sewage worm Tubifex, the snail Physa, the harpacticoid copepod Canthocamptus, and the oligo- chaete worm Limnodrilus. Dominance types for Unconsolidated Bottoms in the Marine and Estuarine systems were taken predomi- nantly from Miner (1950), Smith (1964), Abbott (1968), and Ricketts and Calvin (1968). Dominance types for unconsolidated bottoms in the Lacustrine, Riverine, and Palustrine 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 include subtidal, irregularly exposed, regu- larly flooded, permanently flooded, intermittently exposed, semipermanently flooded, and seasonally flooded. Description. Aquatic Beds represent a diverse group of plant communities that require s lrface water for optimum growth and reproduction. They are best developed in relatively permanent water or under conditions of repeated flooding. The plants are either IT 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 substrates characterized by a wide range of sediment depths and textures. They occur in both the Subtidal and Intertidal 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. Domi- nance types such as the rockweeds Fucus and Asco- phyllum and the kelp Laminaria are common along both coasts. In tropical regions, green algae, including forms containing calcareous particles, are more characteristic; Halimeda and Penicillus are common examples. The red alga Laurencia, and the green algae Caulerpa, Enteromorpha, and Ulva are also common Estuarine and Marine dominance types; Entero- morpha and Ulva are tolerant of fresh water and flour- ish near the upper end of some estuaries. The stone- wort Chara is also found in estuaries. 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 intermittently exposed parts of some Lacustrine Systems. The most important dominance types include genera such as Fissidens, Drepano- cladus, and Fontinalis. Fontinalis may grow to depths as great as 120 m (394 feet) (Hutchinson 1975). For simplicity, aquatic liverworts of the genus Marsupella are included in this subclass. Rooted Vascular.— Rooted Vascular beds include a large array of vascular species in the Marine and Estuarine 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 Jeffer- son 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. Prin- cipal dominance types in these areas include turtle grass (Thalasia testudinum), shoalgrass (Halodule wrightii), manatee grass (Syringodium filiformis), widgeon grass (Ruppia maritima), sea grasses (Halo- phila 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 eelgrass (Zostera marina). Eelgrass beds have the most extensive distribution, but they are limited primarily to the more sheltered estuarine environment. In the lower salinity 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 pondweeds, horned pondweeds (Zannichellia), ditch grasses (Ruppia), wild celery, and waterweed (Elodea). The riverweed (Podo- sternum ceratophyllum) is included in this class despite its lack of truly recognizable roots (Sculthorpe 1967). Some of the Rooted Vascular species are charac- terized by floating leaves. Typical dominants include water lilies (Nymphaea, Nuphar), floating-leaf pond- weed (Potamogeton natans), and water shield (Bra- senia 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 considered either emer- gents 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 System. 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 (Eich- hornia crassipes), water nut (Trapa natans), water fern (Salvinia rotundifolia), and mosquito 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 (Wolffiella) (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 18 restricted to subtidal, irregularly exposed, regularly flooded, and irregularly flooded. Description. Reefs are characterized by their ele- vation 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 sub- stantially 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 Pontes, Acropora, and Montipora. The distribution of these types reflects primarily their ele- vation, wave exposure, the age of the Reef, and its exposure to waves. Mollusk.— This subclass occurs in both the Inter- tidal and Subtidal subsystems of the Estuarine System. These Reefs are found on the Pacific, Atlantic, and Gulf coasts and in Hawaii and the Carib- bean. 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 tempera- ture, and these same factors control their distribution. Examples of dominance types for this subclass are the oysters Ostrea and Crassostrea (Smith 1964; Abbot 1968; Ricketts and Calvin 1968). Worm.— Worm Reefs are constructed by large colonies of Sabellariid worms living in individual tubes constructed 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 of Florida, Puerto Rico, and the Virgin Islands. They occur in both the Marine and Estuarine systems where the salinity approximates that of sea water. The reef worm 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 Riverine 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, irregularly flooded, seasonally flooded, temporarily flooded, and intermittently flooded. Description. Streambeds vary greatly in substrate and form depending on the gradient of the channel, the velocity of the water, and the sediment load. The substrate material frequently changes abruptly be- tween riffles and pools, and complex patterns of bars may form on the convex side of single channels or be included as islands within the bed of braided streams (Crickmay 1974). In mountainous 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 Unconsolidated Shores, they may be colonized by "pioneering" an- nuals 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 Emergent 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 exposed. Examples of dominance types are the mollusk Ancylus, 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 flowing 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 of braided streams. Examples of dominance types in the Intermittent Subsystem of the Riverine System are the snail Physa, the oligochaete worm Limnodrilus, the mayfly Caenis, the midge Chironomus, and the mosquito Anopheles. Examples of dominance type in the Estuarine System or Tidal Subsystem of the Riv- erine System are the mussels Modiolus and Mytilus. Sand.— In this subclass, sand-sized particles predominate among the particles smaller than stones. Sand Streambed often contains bars and beaches interspersed with Mud Streambed or it may be inter- spersed 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 Chiron- L9 omus; in the Estuarine System the ghost shrimp Callianassa is a common dominance type. Mud. — In this subclass, the particles smaller than stones are chiefly silt or clay. Mud Streambeds are common in arid areas where intermittent flow is characteristic of streams of low 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 Estuarine System and the Tidal Sub- system of the Riverine System. Examples of domi- nance types for Mud Streambeds include the crayfish Proeambarus, the pouch snail Aplexa, the fly Tabanus, the snail Lymnaea, the fingernail clam Sphaeri um, 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 Wetlands with organic soils. Examples of dominance types are the mussel Modiolus in the Estuarine System and the oligochaete worm Limno- drilus in the Riverine System. Vegetated Streambeds.— These streambeds are exposed long enough 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 or sudden flooding. A typical dominance type is Panicum capillare. Dominance types for streambeds in the Estuarine System were taken primarily from Smith (1964), Abbott (1968), and Ricketts and Calvin (1968) and those for streambeds in the Riverine System from Krecker and Lancaster (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 environments characterized by bedrock, stones, or boulders which singly or in combination have an areal cover of 75% or more and an areal coverage by vege- tation 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 exposed 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 sedentary invertebrates and attached algae or lichens. Rocky Shores usually display a vertical zonation that is a function 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 combination 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 inver- tebrates, 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 lit- torine-lichen zone) is dominated by periwinkles (Lit- torina and Nerita) 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 dominanted by mollusks, green algae, and barnacles of the balanoid group. The zone appears white. Domi- nance types such as the barnacles Balanus, Chtha- malus, and Tetraclita 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 replace- ment 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 charac- terized by dominant genera. Mytilus and gooseneck barnacles (Pollicipes) form communities exposed to strong wave action. Aquatic Beds dominated by Fucus and Laminaria 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 ex- posed at least once daily. The Lithothamnion domi- nance type forms the transition to the Subtidal Sub- system and is exposed only irregularly. In the Palustrine, Riverine, and Lacustrine systems various species of lichens such as Verrucaria spp. and Dermatocarpon fluviatile, as well as blue-green algae, frequently form characteristic zones on Rocky Shores. The distribution of these species depends on the dura- tion of flooding or wetting by spray and is similar to the zonation of species in the Marine and Estuarine 20 systems (Hutchinson 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. If aquatic 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 Hydropsyche and the fingernail clam Pisidium. Unconsolidated Shore Definition. The class Unconsolidated Shore includes all wetland habitats having three characteristics: (1) unconsolidated 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, season- ally flooded, temporarily flooded, intermittently flooded, saturated, or artificially flooded. Intermittent or intertidal channels of the Riverine System or inter- tidal channels of the Estuarine System are classified as Streambed. Description. Unconsolidated Shores are charac- terized 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. Uncon- solidated Shores are found adjacent to Unconsolidated Bottoms in all systems; in the Palustrine and Lacus- trine systems, the class may occupy the entire basin. As in Unconsolidated Bottoms, the particle size of the substrate and the water regime are the important factors determining the types of plant and animal com- munities present. Different substrates usually support characteristic invertebrate fauna. Faunal distribution is controlled by waves, currents, interstitial moisture, salinity, 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 that have been transported away from Cob- ble-Gravel shores by waves and currents. Shell fragments, sand, and silt often fill the spaces between the larger particles. Stones and boulders may be found scattered 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 Estuarine systems are: the acorn barnacle Balanus, the limpet Patella, the periwinkle Littorina, the rock shell Thais, the mussels Mytilus and Modio- lus, and the Venus clam Saxidomus. In the Lacustrine, Palustrine, and Riverine systems examples of domi- nance types are the freshwater mollusk Elliptio, the snails Lymnaea and Physa, the toad bug Gelastocoris, the leech Erpodella, and the springtaiMgrem'a. Sand.— The unconsolidated particles smaller than stones are predominantly sand which may be either calcareous or terrigenous in origin. They are promi- nent features of the Marine, Estuarine, Riverine, and Lacustrine 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 of dominance types in the Riverine, Lacustrine, and Palustrine systems are the copepods Paras tenocaris and Phvllognathopus; 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 conditions 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 fre- quently called flats. Mud Shores support diverse popu- lations of tube-dwelling and burrowing invertebrates that include worms, clams, and crustaceans (Gray 1974). They are commonly 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 sur- rounded by, or lie on the landward side of, Emergent Wetland (Martin et al. 1953, Type 15). In many arid areas, Palustrine and Lacustrine Mud Shores are crusted 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 vege- tation by man, animals, or fire, or from the discharge of thermal waters or pollutants. Examples of dominance types in the Marine and Estuarine systems include the fiddler crab Uca, the ghost shrimp Callianassa, the mud snails Nassarius and Macoma, the clam worm Nereis, the sea anemone Cerianthus, 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 Cantho- camptus and Bryocamptus, 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 21 than stones is predominantly organic soils of formerly vegetated wetlands. In the Marine and Estuarine systems, Organic Shores are often dominated by microinvertebrates such as foraminifera, and by Nas- sarius, Littorina, Uca, Modiolus, Mya, Nereis, and the false angel wing Petricola pholadiformis. In the Lacus- trine, Palustrine, and Riverine systems, examples of dominance types are Canthocamptus, Bryocamptus, Chironomus, and the backswimmer Notonecta. Vegetated. — Some nontidal shores are exposed for a sufficient period to be colonized by herbaceous an- nuals 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 hydro- phytes but are weedy mesophytes that cannot tolerate wet soil or flooding. Examples of dominance types in the Palustrine, Riverine, and Lacustrine systems are cocklebur {Xanthium strummarium) and barnyard grass (Echinochloa crusgalli). Dominance types for unconsolidated shores in the Marine and Estuarine systems were taken primarily from Smith (1964), Morris (1966), Abott (1968), Ricketts and Calvin (1968), and Gosner (1971). Domi- nance types for unconsolidated shores in the Lacus- trine, Riverine, and Palustrine systems were taken pri- marily 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 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 30% of the areal cover. The only water regime is saturated. Description. Mosses and lichens are important com- ponents of the flora in many wetlands, especially in the north, but these plants usually form a ground cover under a dominant layer of trees, shrubs, or emergents. In some instances 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 fre- quently. 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 Sphag- num or higher plants are dominant. In Alaska, Drepanocladus and the liverwort Chiloscyphus fragilis 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 sub- class. Reindeer moss {Cladonia rangiferina) forms the most important dominance type. Pollett and Bridge- water (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 Hudson 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, excluding 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 conditions, Emergent Wetlands maintain the same appearance 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, in- cluding marsh, meadow, fen, prairie pothole, and slough. Areas that are dominated by pioneer plants that become established during periods of low water are not Emergent Wetlands and should be classified as Vegetated Unconsolidated Shores or Vegetated Streambeds. Subclasses and Dominance Types. Persistent.— Persistent Emergent Wetlands are dominated 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 Palus- trine systems. Persistent Emergent Wetlands dominated by salt- marsh cordgrass (Spartina alterniflora), saltmeadow cordgrass (S. patens), big cordgrass (S. cynosuroides), needlerush IJuncus roemerianus), narrow-leaved cat- tail {Typha angustifolia), and southern wild rice (Zi- zaniopsis 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 cali- fornica), arrow grass (Triglochin maritima), and Cali- fornia cordgrass (Spartina foliosa) are common domi- nants. Palustrine Persistent Emergent Wetlands contain a vast array of grasslike plants such as cattails (Typha spp.), bulrushes (Scirpus spp.), saw grass (Cladium jamaicense), sedges (Carex spp.); and true grasses such 2 2 as reed {Phragmites communis), manna grasses (G/v- ceria 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), waterwillow {Decodon vertieillatus), and many species of smartweeds {Polygonum). Nonpersistent.— Wetlands in this subclass are dominated by plants which fall to the surface of the substrate or below the surface of the water at the end of the growing 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 emergents also include species such as arrow arum {Peltandra virginica), pickerelweed (Pontederia cordata), and arrowheads (Sagittaria spp.). Movement of ice in Estuarine, Riverine, and Lacus- trine 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 subtidal 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 Wet- lands are known by many names, such as shrub swamp (Shaw and Fredine 1956), shrub carr (Curtis 1959), bog (Heinselman 1970), and pocosin (Kologiski 1977). For practical reasons we have also included forests com- posed of young trees less than 6 m tall. Subclasses and Dominance Types. Broad-leaved Deciduous.— In Estuarine System wetlands the predominant deciduous and broad-leaved trees or shrubs are plants such as sea-myrtle (Bacchar- is halimifolia) and marsh elder (Iva frutescens). In the Palustrine System typical dominance types are alders (Alnus spp.), willows (Salix spp.), buttonbush (Ceph- alanthus occidentalis), 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, consist- ing of wetlands where trees or shrubs are pre- dominantly deciduous and needle-leaved, is repre- sented 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 race- mosa, Conocarpus erectus, and Avicennia germinans) that are less than 6 m tall. In the Palustrine System, the broad-leaved evergreen species are typically found on organic soils. Northern representatives are labra- dor tea {Ledum groenlandicum), bog rosemary {An- dromeda glaucophylla), bog laurel {Kalmia polifolia), and the semi-evergreen leatherleaf {Chamaedaphne calyculata). In the south, fetterbush (Lyonia lucida), coastal sweetbells (Leucothoe axillaris), inkberry {Ilex glabra), and the semi-evergreen black ti-ti (Cyrilla racemiflora) 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 (Pinus serotina). Dead— Head woody plants less than 6m tall dominate dead scrub-shrub wetlands. These wetlands are usually produced by a prolonged rise in the water table resulting from impoundment of water by land- slides, man, or beavers. Such wetlands may also result from various other factors such as fire, salt spray, insect infestation, air pollution, and herbicides. Forested Wetland Definition. The class Forested Wetland is charac- terized 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, par- ticularly along rivers and in the mountains. They occur only in the Palustrine 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 Estuarine 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 repre- sented throughout the United States, are most common in the South and East. Common dominants are species such as red maple, American elm (Ulmus americana), ashes (Fraxinus 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 repre- sentatives of the Needle-leaved Deciduous subclass include bald cypress and pond cypress {Taxodium ascendens), which are noted for their 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 development. Red bay {Persea borbonia), loblolly bay (Gordonia lasianthus), and sweet bay {Magnolia vir- giniana) are prevalent, especially on organic soils. This subclass also includes red mangrove, black mangrove {Avicennia germinans), and white mangrove (Lagun- cularia 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 (Chamae- cyparis thyoides) is one of the most common domi- nants on organic soils. Pond pine is a common needle- leaved evergreen found in the southeast in association with dense stands of broad-leaved evergreen and decid- uous 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 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 of hydrologic characteristics requires detailed knowledge of the duration and timing of surface inundation, both yearly and long-term, as well as an understanding of groundwater fluctuations. Because such information 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 major 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 Riv- erine systems. The Tidal Subsystem of the Riverine System and tidally influenced parts of the Palustrine and Lacustrine systems require careful selection of water regime modifiers. We designate subtidal and irregularly exposed wetlands and deepwater habitats in the Palustrine, Riverine, and Lacustrine systems as permanently flooded-tidal rather than subtidal, and Palustrine, Riverine and Lacustrine wetlands regu- larly flooded by the tide as regularly flooded. If Palustrine, Riverine, and Lacustrine wetlands are only 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 dif- ferent 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 are usually two unequal high tides and two unequal low tides (mixed semi- diurnal). 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 un- common in Louisiana. 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 intertidal zone is deter- mined by the tidal range, the slope of the shoreline, and the degree of exposure of the site to wind and waves. 24 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. Department of Interior National Atlas 1970:110-111 for generalized regional delin- eation). 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 development 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 surface water is absent, the water table is usually at or very near the land surface. Seasonally Flooded. Surface water is present for extended 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 exposed, but surface water is present for variable periods without detectable seasonal periodicity. Weeks, months, or even years may intervene between periods of inundation. The dominant plant com- munities under this regime may change as soil mois- ture conditions change. Some areas exhibiting this regime do not fall within our definition of wetland because they do not have hydric soils or support hydrophytes. Artificially Flooded. The amount and duration of flooding is controlled by means of pumps or siphons in combination 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 manage- ment 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, therefore, must be an essential part of this 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 fresh- water habitats are further subdivided by pH levels. Salinity Modifiers Differences in salinity are reflected in the species composition of plants and animals. Many authors have suggested 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 seawater 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 of inland water is dominated by four major cations, calcium (Ca), magnesium (Mg), sodium (Na), and potassium (K); and three major anions, car- bonate (C0 3 ), sulfate (S0 4 ), and chloride (CI) (Wetzel 1975). Salinity is governed by the interactions between precipitation, surface runoff, groundwater flow, evap- 25 oration, and sometimes evapotranspiration by plants. The ionic ratios of inland waters usually differ appre- ciably from those in the sea, although there are excep- tions (Bayly 1967). The great chemical diversity of these waters, the wide variation in physical conditions such as temperature, and often the relative imperma- nence of surface water, make it extremely difficult to subdivide the inland salinity range in a meaningful way. Bayly (1967) attempted a subdivision on the basis of animal life; Moyle (1945) and Stewart and Kantrud (1971) have suggested two very different divi- sions on the basis of plant life. We employ a sub- division that is identical with that used in the Estua- rine and Marine systems (Table 2). The term saline is used to indicate that any of a number 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 Kantrud 1971), but is not universally accepted (see Bayly 1967:84); therefore, mixosaline is used here. In some inland wetlands, high soil salinities control the invasion or establishment of many plants. These salinities are expressed in units of specific con- ductance as well as percent salt (Ungar 1974) and they are also covered by the salinity 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 concen- trations of hydrogen ions from low base content, and many studies suggest that acidity may never be the major factor controlling the presence or absence of particular plants and animals. Nevertheless, some re- searchers have demonstrated a good correlation be- tween pH levels and plant distribution (Sjors 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 influences the types of plants that occupy the site. For this reason, many authors subdivide fresh- water, organic wetlands into mineral-rich and mineral- poor categories (Sjors 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 dif- ference 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 (197 1 ), 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. Table 3. pH modifiers used in this classification system. Modifier pll ol Water Acid Circumneutral Alkaline <5.5 5.5-7.4 >7.4 Soil Modifiers Soil is one of the most important physical com- ponents of wetlands. Through its depth, mineral com- position, 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 construction 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 terres- trial situations and shallow waters; however, "areas are not considered to have soil if the surface is perma- nently covered by water deep enough that only float- ing 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 equi- valent to the waterward limit of wetland, according to our definition. Wetlands can then be regarded as having soil in most cases, whereas deepwater 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 their taxonomy. Their classification is hierarchical and permits the description of soils at sev- eral levels of detail. For example, suborders of Histo- sols are recognized according to the degree of decom- position of the organic matter. We use the modifiers mineral and organic in this classification. Mineral soils and organic soils are dif- ferentiated on the basis of specific criteria that are enumerated in soil taxonomy (U. S. Soil Conser- vation 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 Service classification system should be used. Special Modifiers Many wetlands and deepwater habitats are man- 26 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 modifiers 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 purposefully or unintentionally obstructs the outflow of water. Both man-made dams and beaver dams are included. Diked 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, Unconsolidated Bottom, Rocky Shore, and Uncon- solidated Shore that were emplaced by man, using either natural materials such as dredge spoil or syn- thetic materials such as discarded automobiles, tires, or concrete. Jetties and breakwaters 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 particular regional alliance; its representatives may be found in one or many parts of the United States. However, regional variations in climate, geology, soils, and vegetation 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 dif- ferences. Regionalization is designed to facilitate three activities: (1) planning, where it is necessary to study management problems and potential 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 subcontinental 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 vegetation at the level of Kuchler'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 a detailed discussion and description 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 estuarine habitats. Many workers have divided marine and estuarine realms into series of biogeographic prov- inces (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 of Newfoundland (Avalon Peninsula), northward around Canada to the west coasts of the Arctic Ocean, Bering Sea, and Baffin and Labrador basins. It is charac- terized by the southern extension of floating ice, the 4°C summer isotherm, and arctic biota. • Acadian Province extends along the northeast Atlantic 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 fre- quently rocky. It has a large tidal range and is strongly influenced by the Labrador Current. • Virginian Province extends along the middle Atlantic coast from Cape Cod to Cape Hattaras. The province is transitional between the Acadian and Caro- linian provinces (which follow). The biota is primarily temperate, but has some boreal representatives. The Labrador Current occasionally extends down to Cape Hattaras and winter temperatures may approach 4°C. The tidal range is moderate. • Carolinian Province is situated along the south Atlantic coast from Cape Hattaras to Cape Kennedy. It contains extensive marshes and well-developed barrier islands. Waters are turbid and productive. The 27 ,,,-.. <>■£> 9. BOUNDARIES OF MARINE AND ESTUARINE PROVINCES PROVINCE Fig. 7. Ecoregions of the United States after Bailey (1976) with the addition of 10 marine and estuarine provinces proposed in our classification. "Domains, 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 1320 Yukon Forest Ml. 51 n 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 M21 10 Columbia Forest M2111 Douglas-fir Forest M2112 Cedar-Hemlock- Douglas-fir Forest 2200 Hot Continental 2210 Eastern Deciduous Forest 221 1 Mixed Mesophy tic 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-Pine-Oak 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 lin Alaska) 2500 Prairie 2510 Prairie Parkland 251 1 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 M2610Sierran Forest M2620 California Chaparral 3000 Dry 3100 Steppe 31 10 Great Plains-Shortgrass Prairie 3111 Grama-Needlegrass-Wheatgrass 3112 Wheatgrass-Needlegrass 3113 Grama-Buffalo Grass 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 Jumper-Pinyon Woodland + Sagebrush Saltbush Mosaic P3132 Grama-Galleta Steppe + Juniper- Pinyon Woodland Mosaic 3140 Mexican Highland Shrub Steppe A3 140 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 28 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 tem- peratures 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 corals 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 Aransas, 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 temperate and the tidal range is small. . Californian Province extends along the Pacific coast from Mexico northward to Cape Mendocino. The shoreland 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 influ- enced by the California Current. The biota is tem- perate, 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. Mountainous shorelands with rocky foreshores are prevalent. Estuaries are strongly influenced by freshwater runoff. The biota is primarily temperate with some boreal components, and there are extensive algal communities. The province is influenced by both the Aleutian and California 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 estu- aries (some with glaciers), and a heavily indented shoreline subject to winter icing are typical of the coast. The biota is boreal to subarctic. 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 moun- tains and wave action is stronger than in most of the other provinces. The biota is largely endemic and com- posed of tropical and subtropical 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 organizations with varied interests and objectives. The classification employs 5 system names, 8 sub- system names, 11 class names, 28 subclass names, and an unspecified number of dominance types. It is, of necessity, a complex system when viewed in its en- tirety, but use of the system for a specific purpose at a local site should be simple and straightforward. Arti- ficial keys to the systems and classes (Appendix E) are furnished to aid the user of the classification, but ref- erence 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 poten- tial 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 information may be in the form of historical data, aerial photographs, 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 information 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 man- datory. (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 modification 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 deepwater habitats. A classification used in 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 example, there are a number of possible mapping conventions for a small wetland basin 50 m (164 feet) in diameter with con- centric rings of vegetation about the deepest zone. At 29 a scale of 1:500 each zone may be classified and mapped; at 1:20,000 it might be necessary to map the entire 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 neces- sary 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 of each will vary among users. The systems and sub- systems 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 recog- nizable 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 placement of a wetland in its proper place 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 interested in detailed regional studies. It may be neces- sary 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 presence and distribution of plants or animals (e.g., Stephenson and Stephenson 1972; Stewart and Kantrud 1972; Chapman 1974). Similarly, we do not intend that salinity measure- ments be made for all wetlands except where these data are required; 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., 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., Penfound 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 chemistry conditions have not been identified, detailed regional studies will be required before the classifi- cation can be applied 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 observations of water regime or water chemistry. Such measurements 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 modi- fiers 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 published classifications that have gained widespread acceptance. It is not possible to equate these systems directly for several reasons: (1) The criteria selected for establishing categories differ; (2) some of the classifi- cations 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 Larson (1974) refined the freshwater wetland types of Circular 39 by writing more detailed descriptions and subdividing classes on the basis of finer differences in plant life forms. Golet and Larson's classes are roughly equivalent to Types 1-8 of Circular 39, except that they restricted Type 1 to river floodplains. The ■M) Table 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. Classification of wetlands and deepwater habitats Circular 39 type, and references for examples of typical vegetation Classes Water regimes Water chemistry Type 1— Seasonally flooded basins or flats Wet meadow (Di.x and Smeins 1967; Stewart and Kantrud 1972) Bottomland hardwoods (Braun 1950) Shallow-freshwater swamps (Penfound 1952) Emergent Wetland Temporarily Flooded Fresh Forested Wetland Intermittently Mixosaline Flooded Type 2 — Inland fresh meadows Fen (Heinselman 1963) Fen, northern sedge meadow (Curtis 1959) Emergent Wetland Saturated Fresh Mixosaline Type 3— Inland shallow fresh marshes Shallow marsh (Stewart and Kantrud 1972; Golet and Larson 1974) Type 4 — Inland deep fresh marshes Deep marsh (Stewart and Kantrud 1972; Golet and Larson 1974) Type 5— Inland open fresh water Open water (Golet and Larson 1974) Submerged aquatic (Curtis 1959) Type 6— Shrub swamps Shrub swamp (Golet and Larson 1974) Shrub-carr, alder thicket (Curtis 1959) Type 7— Wooded swamps Wooded swamp (Golet and Larson 1974) Swamps (Penfound 1952; Heinselman 1963) Type 8 -Bogs Bog (Dansereau and Segadas-vianna 1952; Heinselman 1963) Pocosin (Penfound 1952; Kologiski 1977) Type 9— Inland saline flats Intermittent alkali zone (Stewart and Kantrud 1972) Type 10— Inland saline marshes Inland salt marshes (Ungar 1974) Type 1 1 —Inland open saline water Inland saline lake community (Ungar 1974) Type 12— Coastal shallow fresh marshes Marsh (Anderson et al. 1968) Estuarine bay marshes, estuarine river marshes (Stewart 1962) Fresh and intermediate marshes (Chabreck 1972) Emergent Wetland Emergent Wetland Aquatic Bed Aquatic Bed Unconsolidated Bottom Scrub-Shrub Wetland Forested Wetland Scrub-Shrub Wetland Forested Wetland Moss-Lichen Wetland Unconsolidated Shore Emergent Wetland Unconsolidated Bottom Emergent Wetland Semipermanently Flooded Seasonally Flooded Permanently Flooded Intermittently Exposed Semipermanently Flooded Permanently Flooded Intermittently Exposed All nontidal regimes except Permanently Flooded All nontidal regimes except Permanently Flooded Saturated Seasonally Flooded Intermittently Flooded Temporarily Flooded Seasonally Flooded Semipermanently Flooded Permanently Flooded Intermittently Flooded Regularly Flooded Irregularly Flooded Semipermanently Flooded-Tidal Fresh Mixosaline Fresh Mixosaline Fresh Mixosaline Fresh Fresh Fresh (acid only) Eusaline Hypersaline Eusaline Eusaline Mixohaline Fresh 31 Table 4. Continued. Classification of wetlands and deepwater habitats Circular 39 type, and references for examples of typical vegetation Classes Water Water regimes chemistry Type 13— Coastal deep fresh marshes Marsh (Anderson et al. 1968) Estuarine bay marshes, estuarine river marshes (Stewart 1962) Fresh and intermediate marshes (Chabreck 1972) Type 14— Coastal open fresh water Estuarine bays (Stewart 1962) Type 15-Coastal salt flats Panne, slough marsh (Redfield 1972) Marsh pans (Pestrong 1965) Type 16— Coastal salt meadows Salt marsh (Redfield 1972; Chapman 1974) Type 17— Irregularly flooded salt marshes Salt marsh (Chapman 1974) Saline, brackish, and intermediate marsh (Eleuterius 1972) Type 18— Regularly flooded salt marshes Salt marsh (Chapman 1974) Type 19— Sounds and bays Kelp beds, temperate grass flats (Phillips 1974) Tropical marine meadows (Odum 1974) Eelgrass beds (Akins and Jefferson 1973; Eleuterius 1973) Type 20— Mangrove swamps Mangrove swamps (Walsh 1974) Mangrove swamp systems (Kuenzler 1974) Mangrove (Chapman 1976) Emergent Wetland Regularly Flooded Semipermanently Flooded-Tidal Mixohaline Fresh Aquatic Bed Unconsolidated Bottom Subtidal Permanently Flooded-Tidal Mixohaline Fresh Unconsolidated Shore Regularly Flooded Irregularly Flooded Hyperhaline EuhaUne Emergent Wetland Irregularly Flooded Euhaline Mixohaline Emergent Wetland Irregularly Flooded Euhaline Mixohaline Emergent Wetland Regularly Flooded Euhaline Mixohaline Unconsolidated Bottom Aquatic Bed Flat Subtidal Irregularly Exposed Regularly Flooded Irregularly Flooded Euhaline Mixohaline Scrub-Shrub Wetland Forested Wetland Irregularly Exposed Regularly Flooded Irregularly Flooded Hyperhaline Euhaline Mixohaline Fresh 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 cate- gories, 6 site types giving a wetland's hydrologic and topographic location; 8 cover types (modified from Stewart and Kantrud 1971) expressing the distri- bution 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 compare the Golet and Larson system with the one described 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 classifi- cation system to better serve the needs of researchers and wetland managers in the glaciated prairies. Their system recognizes seven classes of wetlands which are distinguished 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 cover type, which represents differences in the spatial relation 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 classification of this part separate from the rest is done for practical rather than for ecological reasons 32 STEWART AND KANTRUD (1972) APPROXIMATE SPECIFIC CONDUCTANCES (pMhos) THIS CLASSIFICATION SALINE SUBSALINE BRACKISH MODERATELY BRACKISH SLIGHTLY BRACKISH FRESH 60,000 45.000 30.000 2,000 800 500 HYPERSALINE EUSALINE POLYSALINE 1 5.000 MESOSALINE 8.000 5,000 OLIGOSALINE MIXOSALINE FRESH Fig. 8. Comparison of the water chemistry subclasses of Stewart and Kantrud (1972) with water chemistry modifiers used in the present classification system. (Cowardin 1978). Recently there has been a flurry of interest in a holistic approach to land classification (in Table 5. Comparison of the zones of Stewart and Kantrud's (1971) classification with the water regime modifiers used in the present classification system. Zone Water regime modifier Wetland-low-prairie Wet meadow Shallow marsh Deep marsh Intermittent-alkali Permanent-open- water Fen (alkaline bog) Non-wetland by our definition Temporarily flooded Seasonally flooded Semipermanently flooded Intermittently exposed Intermittently flooded (with saline or hypersaline water) Permanently flooded (with mixo- haline water) Saturated Land Classification Series, Journal of Forestry, vol. 46, no. 10). A number of classifications have been developed (e.g., Radford 1978) or are under develop- ment (e.g., Driscoll et al. 1978). Parts of this wetland classification can be incorporated into broader hier- archical 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 deepwater habitats of the United States (Plates 1-56; pages 48-103). ACKNOWLEDGMENTS The breadth and complexity of preparing this classification caused us to solicit help and advice from individuals too numerous to list here. Frequently the recommendations were in conflict and we take respon- 33 sibility for the decisions we have made but acknowl- edge all suggestions including those not accepted. Sev- eral 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 distri- bution of the operational draft. Special credit is due the regional coordinators of the National Wetland Inventory and P. B. Reed, who have furnished contin- uing consultation 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 O. Carter on soil taxonomy, R. P. Novitzki on hydrology, and R. H. Chabreck on coastal wetland ecology. M. L. Heinsel- man and R. H. Hofstetter helped with difficult prob- lems of peatland ecology and terminology. R. L. Kolo- giski aided with botanical problems. J. H. Montanari, W. O. Wilen, and the entire National Wetland Inven- tory staff furnished encouragement and logistic support. The staff of the Northern Prairie Wildlife Re- search Center contributed substantially to completion of the classification. Art work and graphics were pre- pared by J. Rodiek, R. L. Duval, and C. 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 Commission, Florence, Oregon. 159 pp. Anderson, J. R., E. E. Hardy, J. T. Roach, and R. E. Witman. 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, and R. D. Rappleye. 1968. Water quality and plant distribution along the upper Patuxent River, Maryland. Chesapeake Sci. 9:145-156. Bailey, R. G. 1976. Ecoregions of the 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. Pages 78-104 in A. H. Weatherley, ed. Aus- tralian 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 of eastern North America. Hafner Publishing Co., New York and London. 596 pp. Brinkhurst, R. O., and B. G. M. Jamieson. 1972. Aquatic oligochaetes of the world. University of Toronto Press, Toronto. 860 pp. Britton, M. E. 1957. Vegetation of the Arctic tundra. Oreg. State Univ. Biol. Colloq. 18:26-61. Burbank, W. D. 1967. Evolutionary and ecological impli- cations 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 of vegetation analysis. Harper & Brothers, New York. 325 pp. Carriker, M. R. 1967. Ecology of estuarine benthic inver- tebrates: 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 bio- logical considerations. Pages 6-8 in G. H. Lauff, ed. Estuaries. Am. Assoc. Adv. Sci. Publ. 83. Chabreck, R. H. 1972. Vegetation, water and soil charac- teristics of the Louisiana coastal region. La. Agric. Exp. Stn. Bull. 664. 72 pp. Chapman, V. J. 1974. Salt marshes and salt deserts of the world. 2nd supplemented edition. J. Cramer, Lehre. 392 pp. Chapman, V. J. 1976. Mangrove vegetation. J. Cramer, Leuterhausen. 447 pp. Chapman, V. J. 1977. Introduction. Pages 1-30 in V. J. Chapman, 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 Interior Basin. Malacologia 13U-2):l-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., and R. T. Hartman, editors. 1964. Organism— substrate relationships in streams. Pymatuning Lab. Ecol., Univ. Pittsburg Spec. Publ. 4. 145 pp. Curtis, J. T. 1959. The vegetation of Wisconsin. The Uni- versity 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. den Hartog, C. 1960. Comments on the Venice-system for the classification of brackish water. Int. Rev. gesamten Hydro- biol. 45:481-485. Dillon, O. W. 1966. Gulf coast marsh handbook. U. S. Soil Conservation Service, Alexandra, Louisiana, n.p. Dix, R. L., and F. E. Smeins. 1967. The prairie, meadow, and marsh vegetation of Nelson 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 Moun- tain 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. Harv. Univ. Gray Herb. Contrib. 190. Ill 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 halo- phytes. Academic Press, Inc., New York. Eleuterius, L. M. 1972. The marshes of Mississippi. Castanea 37:153-168. 34 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 Laboratory, Ocean Springs. Golet, F. C, and J. S. Larson. 1974. Classification of fresh- water wetlands in the glaciated Northeast. U. S. Fish Wildl. Serv.. Resour. Publ. 1 16. 56 pp. Gosner. K. L. 1971. Guide to identification of marine and estuarine invertebrates: Cape Hattaras 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 Conservation 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 peatland types in the Glacial Lake Agassiz Region, Minne- sota. Ecol. Monogr. 33(41:327-374. Heinselman, M. L. 1970. Landscape evolution, peatland types, and the environment in the Lake Agassiz Peatlands Natural Area, Minnesota. Ecol. Monogr. 40(21:235-261. 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. Uni- versity of Toronto Press, Toronto. 555 pp. lilies, J., and L. Botosaneau. 1963. Problems et methodes de la classification et de la zonation ecologique des aux cour- antes, 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(31:84-87. 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. O-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(61:263-450. Kenk, R. 1949. The animal life of temporary 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. Koppen, W. 1931. Grundriss der Klimakunde. Walter de Gruyter & Co., Berlin. 388 pp. Krecker, F. H., and L. Y. Lancaster. 1933. Bottom shore fauna of western Lake Erie: a population study to a depth of six feet. Ecology 14:79-83. Kuchler, 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., and K. 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., and K. 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 Uni- versities Press Ltd., London. 323 pp. Liu, T. K. 1970. A review of engineering soil classification systems. Pages 361-382 in Special procedures for testing soil and rock for engineering purposes. 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., and M. B. Barbour. 1974. Beach and salt marsh vegetation of the North American Pacific coast. Pages 175-233 in R. J. Reimold and W. H. Queen, eds. Ecology of halophytes. Academic Press, Inc., New York. Martin, A. C, N. Hotchkiss, F. M. Uhler, and W. S. Bourn. 1953. Classification of wetlands 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 of the Prairie Provinces. Can. Wildl. Serv. Rep. Ser. 37. 38 pp. Miner, R. W. 1950. Field book of seashore life. G. P. Put- nam's Sons, New York. 888 pp. Montanari, J. H., and J. E. Townsend. 1977. Status of the National 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 distribution of aquatic plants in Minnesota. Am. Midi. Nat. 34(21:402-420. Moyle, J. B. 1946. Some indices of lake productivity. Trans. Am. Fish. Soc. 76:322-334. Mueller-Dombois, D., and H. 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, and E. A. McMahan, eds. Coastal ecological systems of the United States. Vol. 1. The Conservation Foundation, Washington, D. C. Odum, H. T., B. J. Copeland, and E. A. McMahan, editors. 1974. Coastal ecological systems of the United States. The Conservation Foundation, Washington, D. C. 4 Vols. Penfound, W. T. 1952. Southern swamps and marshes. Bot. Rev. 18:413-436. Penfound, W. T., and E. S. Hathaway. 1938. Plant com- munities 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 of the United States. Vol. 2. The Conservation Foundation, Washington. D. C. Pollett, F. C, and P. B. Bridgewater. 1973. Phytosociology of peatlands in central Newfoundland. Can. J For Res 3(31:433-442. Price, J. B., and G. Gunter. 1964. Studies of the chemistry of fresh and low salinity waters in Mississippi and the bound- ary between fresh and brackish water. Int. Rev. gesamten Hydrobiol. 49:629-636. Radford, A. E. 1978. Natural area classification systems: a standardized scheme for basic inventory of species, com- munity 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., and R. D. Wood. 1976. Ecology of inland waters and estuaries. D. Van Nostrand and Co., New York. 485 pp. Remane, A., and C. 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., and E. A. McMahan. 1974. High energy beaches. Pages 180-251 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. 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. Sjors, H. 1950. On the relation between vegetation and electrolytes in north Swedish mire waters. Oikos 2:241-258. Sjors, 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 of the Woods Hole Region. Contribution No. 11 of the Systematic- Ecology Program, Marine Biological Laboratory, Woods Hole, Massachusetts. 208 pp. Stegman, J. L. 1976. Overview of current wetland classifi- cation 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 proceedings— 1975, University of Maryland. U. S. Fish and Wildlife Service, Washington, D. C. Stehr, W. C, and J. W. Branson. 1938. An ecological study of an intermittent stream. Ecology 19(l):294-354. Stephenson, T. A., and A. Stephenson. 1972. Life between tidemarks on rocky shores. W. H. Freeman and Co., San Francisco. 425 pp. 35 Stewart, R. E. 1962. Waterfowl populations in the upper Chesapeake Region. U. S. Fish Wildl. Serv., Spec Sci Rep.-Wildl. 65.208 pp. Stewart, R. E., and H. A. Kantrud. 1971. Classification of natural 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 paleo- ecology. Geol. Soc. Am. Mem. 67. Vol. 1. Ungar, I. A. 1974. Inland halophytes of the 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 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 and low predictions 1974: East coast of North and South America. U. S. Government Printing Office, Washington, D. C. 288 pp. U. S. Senate. 1970. The National Estuarine Pollution Study. Report of the Secretary of Interior to the United States Congress pursuant to Public Law 89-753, The Clean Water Restoration Act of 1966. U. S. Senate Doc. No. 91-58. U. S. Government Printing Office. Washington, D. C. 633 pp. U. S. Soil Conservation Service, Soil Survey Staff. 1975. Soil Taxonomy: a basic system of soil classification for making and interpreting soil surveys. U. S. Soil Conservation Service. Agric. Handb. 436. 754 pp. van der Schalie, H. 1948. The land and freshwater mollusks of Puerto Rico. Univ. Mich. Mus. Zool. Misc. Publ. 70. 134 pp. Walsh, G. E. 1974. Mangroves: a review. Pages 51-174 in R. J. Reimold, and W. H. Queen, eds. Ecology of halo- phytes. 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 northern Colorado trout stream: 1945 and 1974. Ecologv 56:1429-1434. Weaver, J. E., and F. 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 670/4-73-001. Welch, P. S. 1952. Limnology, 2nd ed. McGraw-Hill, New York. 538 pp. Wetzel, R. G. 1975. Limnology. W. B. Saunders Co., Phila- delphia. 658 pp. Zhadin, V. I., and S. V. Gerd. 1963. Fauna and flora of the rivers, lakes and reservoirs of the U. S. S. R. Oldbourne Press, London. 626 pp. Zoltai, S. C, F. C. Pollett, J. K. Jeglum, and G. D. Adams. 1975. Developing a wetland classification for Canada. Proc. N. Am. For. Soils Conf. 4:497-511. APPENDIX A 37 Scientific and Common Names of Plants Scientific name Acer rubrum L. Alisma plantago-aquatica L. Alnus spp. Alnus rugosa (Du Roi) Spreng. Alopecurus aequalis Sobol. Andromeda glaucophylla Link Aristida stricta Michx. Ascophyllum spp. Ascophyllum nodosum L. Aulacomnium palustre (Hedw.) Schwaegr. Avicennia germinans (L.) Stearn Azolla spp. Baccharis halimifolia L. Beckmannia syzigachne (Steud.) Fern. Betula pumila L. Brasenia schreberi Gmel. Calamagrostis canadensis (Michx.) Beauv. Calopogon spp. Campylium stellatum (Hedw.) C. Jens. Carex spp. C. aquatilis Whlent. C. atherodes Spreng. C. lacustris Willd. C. lasiocarpa Erhr. C. lyngbyei Hornem. C. rostrata S. J. Stokes Caulerpa spp. Cephalanthus occidentalis L. Ceratophyllum spp. C. demersum L. Chamaecyparis thyoides (L.) BSP Chamaedaphne calyculata (L.) Moench Chara spp. C. crispa Wallman C. aspera Detharding ex Willdenow Chenopodium glaucum L. Common name 8 Red maple (Water plantain) Alders Speckled alder Foxtail Bog rosemary (Three-awn) Rockweeds (Rockweed) (Moss) Black mangrove Mosquito ferns Sea-myrtle Slough grass Bog birch Water shield Bluejoint Grass pinks (Moss) Sedges (Sedge) Slough sedge (Sedge) (Sedge) (Sedge) Beaked sedge (Green algae) Buttonbush Coontails (Coontail) Atlantic white cedar Leatherleaf (Stoneworts) (Stonewort) (Stonewort) (Goosefoot) Scientific name Common name 8 a General common names that refer to a higher taxon and names for which there is little agreement on common name are shown in parentheses. C. rubrum L. Chiloscyphus spp. C. fragilis (Roth) Schiffn. Cladium jamaicense Crantz Cladonia rangiferina (L.) Wigg. Cladophora spp. C. glomerata Kutzing Colocasia esculenta Shott. Conocarpus erectus L. Cornus stolonifera Michx. Cyperus spp. Cyrilla racemiflora L. Decodon verticillatus (L.) Ell. Dermatocarpon aquaticum (Weiss) A. Zahlbruckner D. fluviatile (G. Web) Desmatodon heimii Distichlis spicata (L.) Greene D. stricta (Torr.) Rydb. Drepanocladus spp. D. fluitans (Head w.) Warnet. Echinochloa crusgalli (L.) Beauv. Eichhornia crassipes (Mart.) Solms. Eleocharis acicularis (L.) R&S E. palustris (L.) R&S Elodea spp. Empetrum nigrum L. Enteromorpha spp. Equisetum fluviatile L. Eriophorum spp. Fissidens spp. F. adiantoides Hedew. F. julianus (Mont.) Schimper Fontinalis spp. F. antipyretica L. Fraxinus nigra Marsh. F. pennsylvanica Marsh. Fucus spp. Fucus vesiculosus C. L. And. Glyceria spp. Gordonia lasianthus (L.) Ell. Habenaria spp. Halimeda spp. Halodule wrightii Aschus Halophila spp. (Goosefoot) (Liverworts) (Liverwort) Saw grass Reindeer moss (Green algae) (Green algae) Taro (Mangrove) Red ozier dogwood Nut grasses Black ti-ti Water willow (Lichen) (Lichen) (Moss) (Salt grass) (Salt grass) (Moss) (Moss) Barnyard grass Water hyacinth (Spike rush) (Spike rush) Water weeds Crowberry (Green algae) (Horsetail) Cotton grasses (Moss) (Moss) (Moss) (Moss) (Moss) Black ash (Red ash) (Rockweeds) (Rockweed) Manna grasses Loblolly bay (Orchids) (Green algae) Shoalgrass (Sea grass) 38 Scientific name Hippurus vulgaris L. Ilex glabra (L.) Gray I. verticillata (L.) Gray Iva frutescens L. Juneus spp. J. gerardii Loisel. J. militaris Bigel. J. roemerianus Scheele Kalmia angustifolia L. K. polifolia Wang. Kochia scoparia (L.) Schrad. Laguncularia racemosa (L.) Gaertn. f. Laminaria spp. Larix laricina (Du Roi) K. Koch Laurencia spp. Ledum groenlandicum Oeder Lemna spp. L. minor L. Leucothoe axillaris (Lam.) D. Don Lithothamnion spp. Lycopodium alopecuroides L. Lyonia lucida (Lam.) K. Koch Lythrum salicaria L. Macrocystis spp. M. pyrifera (L.) C. A. Ag. Magnolia virginiana L. Marsupella spp. M. emarginata (Ehrenberg) Dumortier Myrica gale L. Myriophyllum spp. M. exalbescens Fern. Najas spp. Nelumbo lutea (Willd.) Pers. Nitella spp. N. flexilis (L.) Agardh. N. ofefusa T. F. Allen Nuphar spp. TV. /ufeum (L.) Sibth. & Smith N. variegatum Engelm. Nymphaea spp. N. odorata Ait. Nymphoides spp. JV. aquatica (Walt.) O. Kuntze Nyssa Aquatica L. N. sylvatica Marsh. Oncophorus wahlenbergii Brid. Panicum eapillare L. Peltandra virginica (L.) Kunth Pelvetia spp. Penicillus spp. Persea borbonia (L.) Spreng. Common name 3 Mare's tail Inkberry Winterberry Marsh elder Rushes Black grass Bayonet rush Needlerush Sheep laurel Bog laurel Summer cypress White mangrove (Kelps) Tamarack (Red algae) Labrador tea (Duckweeds) Common duckweed Coastal sweetbells Coralline algae Foxtail clubmoss Fetterbush Purple loosestrife (Kelps) (Kelp) Sweet bay (Liverworts) (Liverwort) Sweet gale Water milfoils (Water milfoil) Naiads American lotus (Stoneworts) (Stonewort) (Stonewort) Yellow water lilies (Yellow water lily) (Yellow water lily) (Water lilies) (White water lily) Floating hearts (Floating heart) Tupelo gum Black gum Moss Old witch grass Arrow arum (Rockweed) (Green algae) Red bay Scientific name Phragmites communis Trin. Phyllospadix scouleri Hook. P. torreyi Wats. Picea mariana (Mill.) BSP P. sitchensis (Bong.) Carr. Pinus contorta Dougl. P. palustris Mill. P. serotina Michx. Pistia stratiotes L. Podostemum ceratophyllum Michx. Polygonum spp. P. amphibium L. P. coccineum Muhl. Pontederia cordata L. Potamogeton spp. P. epihydrus Raf. P. gramineus L. P. natans L. Potentilla spp. Quercus bicolor Willd. Q. lyrata Walt. Q. michauxii Nutt. Ranunculus trichophyllus Chaix Rhizophora mangle L. Rhododendron maximum L. Rhynchospora spp. Rubus chamaemorus L. Rumex maritimus L. R. mexicanus Meisn. Ruppia spp. R. maritima L. Sagittaria spp. Salicornia spp. S. europaea L. S. virginica L. Salix spp. Salvinia rotundifolia Willd. Sarcobatus vermiculatus (Hook.) Torr. Schizothrix spp. Scirpus spp. S. acutus Muhl. S. americanus Pers. S. olneyi Gray S. paludosus Nels. Scolochloa festucacea (Willd. Link Spartina alterniflora Loisel. S. cynosuroides (L.) Roth Common name 3 Reed (Surfgrass) (Surfgrass) Black spruce Sitka spruce Lodgepole pine Longleaf pine Pond pine Water lettuce Riverweed Smartweeds Water smartweed Marsh smartweed Pickerelweed Pondweeds Ribbon-leaf pond- weed (Pondweed) Floating-leaf pond- weed Cinquefoils Swamp white oak Overcup oak Basket oak White water crowfoot Red mangrove Great laurel Beak rushes Cloudberry Golden dock (Dock) Ditch grasses Widgeon grass Arrowheads Glassworts Samphire (Common pickle- weed) Willows Water fern Greasewood (Blue green algae) Bulrushes Hardstem bulrush Common three- square (Bulrush) Alkali bulrush Whitetop Saltmarsh cordgrass Big cordgrass 39 Scientific name S. foliosa Trin. S. patens (Ait.) Muhl. Sphagnum spp. S. fuscum (Schimp.) Klinggr. Spiraea douglasii Hook. Spirodela spp. S. polyrhiza (L.) Schleid. Suaeda californica Wats. Syringodium filiformis Kuetz Tamarix gallica L. Taxodium ascendens Brogn. T. distichum (L.) Rich. Thalassia testudinum Koenig Thuja occidentalis L. Tolypella spp. Trapa natans L. Triglochin maritima L. Typha spp. T. angustifolia L. T. la ti folia L. Ulmus americana L. Common name 3 California cordgrass Saltmeadow cord- grass Peat mosses (Peat moss) Spiraea Big duckweeds (Big duckweed) (Sea blite) Manatee grass Tamarisk Pond cypress Bald cypress Turtle grass Northern white cedar (Stoneworts) Water nut Arrow grass Cattails Narrow-leaved cattail Common cattail American elm Scientific name Viva sp. U. lactuca L. Utricularia spp. U. vulgaris L. Vaccinium atrococcum (Gray) Hell. V. corymbosum L. Vallisneria spp. V. americana Michx. Verrucaria spp. Wolffiella spp. Woodwardia virginica (L.) Smith Xanthium strumarium L. Xyris spp. X. congdoni Small Zanichellia spp. Zenobia pulverulenta (Bartr.) Pollard Zizania aquatica L. Zizaniopsis miliacea (Michx.) Doell & Ascherson Zostera marina L. Common name" Sea lettuce (Sea lettuce) Bladderworts (Bladderwort) Black highbush blueberry Highbush blueberry Wild celeries Wild celery (Lichens) Watermeals Virginia chain-fern (Cocklebur) Yellow-eyed grasses (Yellow-eyed grass) Horned pondweeds Honeycup Wild rice Southern wild rice Eelgrass 1(1 APPENDIX B Scientific and Common Names of Animals Scientific name Acmaea spp. A. testudinalis Mull. Acropora spp. Agrenia spp. Amphipholis spp. A. squamata (Delle Chiaje) Amphitrite spp. Ancylus spp. Anodonta spp. A. cataracta Say A. implicata Say Anodontoides spp. A ferussacianus (Lea) Anopheles spp. Aplexa spp. A hypnorum (L.) Arenieola spp. Asellus spp. Baetis spp. Balanus spp. B. balanoides L. Bryocamptus spp. Caenis spp. Callianassa spp. C. californiensis Dana Cambarus spp. Fallicambarus fodiens (Cottle) Canthocamptus spp. C robertcokeri M. S. Wilson Cerianthus spp. Chaetopterus spp. Chironomus spp. Chironomidae Chthamalus spp. C. fragilis Darwin Cnemidocarpa spp. C. finmarkiensis (Kiaer) Crassostrea spp. C. virginica (Geml.) Dendraster spp. D. excentricus (Eschscholtz) Diamesa spp. Donax spp. Echinocardium spp. Co mmon name 3 Limpets Plate limpet Staghorn corals Springtails Brittle stars Brittle star Terebellid worms Freshwater mollusks Freshwater mollusks Freshwater mollusk Freshwater mollusk Freshwater mollusks Freshwater mollusk Mosquitos Pouch snails Pouch snail Lugworms Isopods Mayflies Acorn barnacles Acorn barnacle Harpacticoid cope- pods Mayflies Ghost shrimp Red ghost shrimp Crayfishes Crayfish Harpacticoid cope- pods Harpacticoid cope- pod Sea anemones Polychaete worms Midges Midges Acorn barnacles Acorn barnacle Tunicates Tunicate Oysters Eastern oyster Sand dollars Sand dollar Midges Wedge shells Heart urchins Scientific name a Most common names refer only to general groupings. Elliptio spp. E. arctata (Conrad) E. complanata (Lightfoot) E. dariensis (Lea) Emerita spp. Ephemerella spp. E. defieiens Morg. Erpobdella spp. E. punctata Leidy Eukiefferiella spp. Eunapius spp. E. fragilis (Leidy) Euzonus spp. Gammarus spp. Gelastocoris spp. G. oculatus Fabr. Helobdella spp. H. stagnalis L. Heteromeyenia spp. H. latitenta (Potts) Hippospongia spp. H. gossvpina (Duch. and Mich.) Homarus americanus Milne-Edwards Hydropsyche spp. H. simulans Ross Lampsilis spp. L. ovata (Say) Ligia spp. Limnodrilus spp. L. hoffmeisteri Clap. Littorina spp. Lumbriculus spp. Lymnaea spp. L. cubensis Pfieffer L. palustris (O. F. Miller) L. stagnalis L. Macoma spp. M balthica (Linne) Melita spp. Mercenaria spp. M. mercenaria (L.) Modiolus spp. M. demissus (Dill) Montipora spp. Muricea spp. M. californica Aurivillius Mya spp. Co mmon name 3 Freshwater mollusks Freshwater mollusk Freshwater mollusk Freshwater mollusk Mole crabs Mayflies Mayfly Leeches Leech Midges Freshwater sponges Freshwater sponge Blood worms Scuds Toad bugs Toad bug Leeches Brook leech Horse sponges Horse sponge Encrusting sponges Encrusting sponge American lobster Caddisflies Caddisfly Freshwater mollusks Freshwater mollusk Slaters Oligochaete worms Oligochaete worm Periwinkles Oligochaete worms Pond snails Pond snail Pond snail Pond snail Macomas Baltic macoma Amphipods Quahogs Quahog Mussels Ribbed mussel Corals Sea whips Sea whip Soft-shell clams il Scientific name M. arenaria (L.) Mytilus spp. M. californianus Conrad M. edulis Linne Nassarius spp. N. obsoletus (Say) Nemoura spp. Nereis spp. N. succinea (Frev and Leuckart) Nerita spp. Notonecta spp. N. lunata Hung Oliva spp. Orchestia spp. Ostrea spp. Parastenocaris spp. Patella spp. Pecten spp. Petricola pholadiformis Lam. Phyllognathopus viguieri Maryek Physa spp. P. gyrina Say Pisaster spp. Pisidium spp. P. abditum Holdeman P. casertanum (Poli) P. ferrugineum Prime Placopecten spp. P. magellanicus (Gmelin) Platyodon spp. P. cancellatus (Conrad) Pollicipes spp. P. polymerus Sowerby Common name 3 Soft-shell clam Mussels California mussel Blue mussel Mud snails Mud snail Stone flies Clam worms Clam worm Nerites Back swimmers Back swimmer Olive shells Beach hoppers Oysters Copepods Limpets Scallops False angel wing Copepods Snails Tadpole snail Sea stars Fingernail clams Fingernail clam Fingernail clam Fingernail clam Deep-sea scallops Atlantic deep-sea scallop Boring clams Boring clam Gooseneck barnacles Gooseneck barnacle Scientific name Porites spp. P. porites (Pallas) Pristina spp. Procambarus spp. P. simulans (Faxon) Psephenus spp. P. herricki (DeKay) Renilla spp. Sabellaria spp. S. cementarium Moore S. floridensis Hartman Saldula spp. Saxidomus spp. S. giganteus (Deshayes) Simulium spp. Siphonaria spp. Sphaerium spp. S. simile Say Spongilla spp. S. lacustris (L.) Strongylocentrotus spp. Tabanus spp. Tellina spp. r. lutea Wood Tetraclita spp. Thai's spp. Thyone spp. Tivela stultorum (Mawe) Tortopus spp. Tubifex spp. T. tufeifejc (O.F.M.) f/ca spp. £7. pugnax (Smith) Urechis spp. Common n ame 3 Corals Coral Oligochaete worms Crayfish Crayfish Riffle beetles Water penny Sea pansies Reef worms Reef worm Reef worm Shore bugs Venus clams Smooth Washington clam Black flies False limpets Fingernail clams Fingernail clam Freshwater sponges Freshwater sponge Sea urchins Flies Tellin shells Great Alaskan tellin Acorn barnacles Rock shells Sea cucumbers Pismo clam Mayflies Sewage worms Sewage worm Fiddler crabs Fiddler crab Echiurid worms 12 APPENDIX C Glossary of Terms 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 pre- dominantly 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, generated by waves and currents and extending from the water to a distinct break in landform or substrate type (e.g., a foredune, 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 sufficient quantities to effervesce carbon dioxide visibly when treated with cold 0.1 normal hydrochloric acid. Cal- careous sands are usually formed of a 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 usually 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 in- ches) 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 of the year when frosts occur (see U. S. Department of Interior, National Atlas 1970:110- 111 for generalized regional delineation). emergent hydrophytes Erect, rooted, herbaceous angio- sperms 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 gen- erally not covered by water. eutrophic lake Lakes that have a high concentration of plant nutrients such as nitrogen and phosphorus. evergreen stand A plant community where evergreen trees or shrubs represent more than 50 c t 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 sedi- ments—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 sepa- rated 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 (Pota- mogeton natans). Plants such as yellow water lily {Nuphar luteum) which sometimes have leaves raised above the surface are considered 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 °/oo dissolved salts. gravel A mixture composed primarily of rock fragments 2 mm (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 of an 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 influencing the growth of plants. hydrophyte Any plant growing in water or on a substrate that is at least periodically deficient in oxygen as a result of excessive water content (plants typically found in wet habitats). hyperhaline Term to characterize waters with salinity greater than 40 °/oo, due to ocean-derived salts. hypersaline Term to characterize waters with salinity greater than 40 °/oo, due to land-derived salts. macrophytic algae Algal plants large enough either as indi- viduals or communities to be readily visible without the aid of optical magnification. mean high water The average height of the high water over 19 years. 13 mean higher high tide The average height of the 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 A plane midway between mean high water and mean low water. mesohaline Term to characterize waters with salinity of 5 to 18 °/oo, due to ocean-derived salts. mesophyte 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 °/oo, 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 °/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 °/oo, due to land-derived salts. mud Wet soft earth composed predominantly of clay and silt— fine mineral sediments less than 0.074 mm in diam- eter (Black 1968; Liu 1970). needle-leaved deciduous Woody gymnosperms (trees or shrubs) with needle-shaped or scale-like leaves that are shed during the cold or dry season; e.g., bald cypress (Taxo- dium 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 stems break down at the end of the growing season so that most above-ground portions of the plants are easily transported by currents, waves, or ice. The breakdown may result from normal decay or the physical force of strong waves or ice. At certain seasons of the year there are no visible traces of the 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 ubiq- uitous species that grow either in wetland or on upland— e.g., red maple {Acerrubrum). oligohaline Term to characterize water with salinity of 0.5 to 5.0 °/oo, due to ocean-derived salts. oligosaline Term to characterize water with salinity of 0.5 to 5.0 °/oo, 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 remain 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 respiration. 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 °/oo, 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 con- tained 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 sediments 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 (Cepha- lanthus 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 60.9 cm (24 inches). submergent plant A vascular or nonvascular hydrophyte, either rooted or nonrooted which lies entirely beneath the water surface, except for flowering parts in 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, un- branched to about 1 m above the ground, and a more or less definite crown; e.g., red maple (Acer rubrttm), northern white cedar (Thuja occidentalis). water table The upper surface of a 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 dries to the wilting coefficient at frequent intervals. (Plants typically found in very dry habitats.) 44 APPENDIX D Criteria for Distinguishing Organic Soils from Mineral Soils The criteria for distinguishing organic soils from mineral soils in the United States (U. S. Soil Conser- vation 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 infor- mation in the classification of wetlands: For purposes of taxonomy, it is necessary, first, to define the limits that distinguish 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 properties that are more nearly those of mineral than of organic soils. Even with this separation, the volume of organic 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 percent 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 carbon between 12 and 18 percent if the clay content of the mineral fraction is between 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 soils have horizons of organic material. For sim- plicity in writing definitions of taxa, a distinction be- tween 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 of the 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 and depends in part on the nature of the 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 of layers in the field than it is to determine tons of organic matter per hectare. The defi- nition of a mineral soil, therefore, is based on thickness of the horizons or layers, but the limits of thickness must vary with the kinds of materials. The definition that follows is intended to classify as mineral soils those that have no more organic material than the amount per- mitted 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 horizon at the surface is considered an organic horizon, if it meets the requirements of organic soil material as defined later, and its thickness is added to that of any other organic horizons to determine the total thickness 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 upper 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 of the thickness of the overlying organic soil material; or 3. The depth to bedrock is a 40 cm, the mineral soil material immediately above the bedrock is 10 cm or more thick, and either a. Organic soil material of < 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 undecomposed sphagnum or moss fibers or has a bulk 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 frac- tion is between zero and 60 percent; or 2. Are never saturated with water for more than a few 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 horizons. Not all organic 45 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. A depth within 10 cm or less of a lithic or paralithic contact, provided the thickness of the organic soil materials is more than twice that of the mineral soil above the contact; or b. Any depth if the organic soil material rests on frag- mental material (gravel, stones, cobbles) and the inter- stices are filled with organic materials, or rests on a lithic or paralithic 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 density is <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 arti- ficially 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 frag- mental material having interstices filled with organic materials. Soils that do not satisfy the criteria for classification as organic soils are mineral soils. 46 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 °/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 oceanic tides, or if influenced by oceanic tides, salinity less than 0.5°/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 percent of substrate but non- persistent 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 1. 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 and Marine Systems) 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% of the 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. 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) 17 Vegetation composed of algae, bryophytes, lichens, or vascular plants that are usually hydrophytic perennials. 9. Vegetation composed predominantly of nonvascular species. 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. Vegetation herbaceous 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 48 Plate 1.— Classification: system Marine, subsystem Subtidal, class Rock Bottom, subclass Bedrock, water regime Subtidal, water chemistry Euhaline. (Monroe County, Florida; Date unknown; Photo courtesy of Florida Department of Natural Resources) 49 Plate 2.— Classification: system Marine, subsystem Subtidal, class Reef, subclass Coral, water regime Subtidal, water CHEMISTRY Euhaline. This is an underwater photograph showing corals (Acropora and Pontes) as well as alcyonarians. (Monroe County, Florida; Date unknown; Photo courtesy of Florida Department of Natural Resources) ;-,(! T^ - ^'^— ~C_ : Plate 3.— Classification: system Marine, subsystem Intertidal, class Rocky Shore and Aquatic Bed, water regime Regularly Flooded and Irregularly Flooded, water chemistry Euhaline. In this photo taken at low tide, the dominant organisms are rockweed (Fucus spp.) and acorn barnacles {Balanus spp.l. (Newport County, Rhode Island; July 1977) r,i Plate 4.— Classification: system Marine, subsystem Intertidal, class Rocky Shore and Aquatic Bed, subclass Rubble and Algal, water regime Regularly Flooded, water CHEMISTRY Euhaline. The dominant organisms are rockweed (Fucits spp.) and acorn barnacles (Balanus spp.). Most stones are larger than 30.5 cm (12 in.) in diameter. (Washington County, Rhode Island; July 1977) 52 Plate 5.— Classification: SYSTEM Marine, subsystem Intertidal, class Unconsolidated Shore, water regime Regularly Flooded and Irregularly Flooded, water chemistry Euhaline. Estuarine system wetland is shown at left of the beach. (Tillamook County, Oregon; August 1977; Photo courtesy of P. B. Reed) 53 Plate 6.— 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 grass {Spartina patens) is shown in the right background. (Washington County, Rhode Island; July 1977) 54 Plate 7.— Classification: system Estuarine, SUBSYSTEM Subtidal, class Aquatic Bed, SUBCLASS Submergent Vascular, water regime Subtidal, water chemistry Oligohaline, SOIL Mineral. The dominant plant is water milfoil {Myriophyllum exal- bescens) and the most common subordinates are pondweeds {Potamogeton spp.). (Nansemond County, Virginia; July 1973) :,:, k/f->>^' Plate 8.— Classification: system Estuarine, subsystem Intertidal, class Reef, subclass Mollusk, water regime Regularly- Flooded, water chemistry Mixohaline. The dominant animals are oysters {Crassostrea spp.). An individual red mangrove (Rhizophora mangle) has become established on the reef. (Collier County. Florida; January 1978) -,l, Plate 9.— Classification: system Estuarine, subsystem Intertidal, CLASS Rocky Shore and Aquatic Bed, subclass Rubble and Algal, water regime Regularly Flooded and Irregularly Flooded, WATER chemistry Euhaline, special modifier Artificial. The dominant organisms shown are rockweed {Fucus spp.) and acorn barnacle {Balanus spp.). (Washington County, Rhode Island; July 1977) 57 »■>* * <»t^^l^JTOFW^^V^ M gg«^ - ^j fat a tap »^%\«w^ ■fifc- * '* Plate 10.— Classification: system Estuarine, subsystem Intertidal, class Unconsolidated Shore, subclass Mud, water regime Regularly Flooded, water CHEMISTRY Polyhaline, SOIL Mineral. The dominant animal is the eastern oyster (Crassostrea virginica). An emergent wetland dominated by saltmarsh cordgrass (Spartina alterniflora) is shown in the background. (Accomac County, Virginia; June 1972) 58 Plate 11.— Classification: system Estuarine, subsystem Intertidal, CLASS Unconsolidated Shore and Streambed, subclass Mud, water regime Regularly Flooded, water chemistry Mixohaline. (Anchorage County, Alaska; July 1977) r,9 Plate 12.— Classification: SYSTEM Estuarine, SUBSYSTEM Intertidal, class Scrub-Shrub, subclass Broad-leaved Evergreen, water regime Regularly Flooded and Irregularly Flooded, water chemistry Oligohaline, SOIL Organic. The dominant plant is red mangrove {Rhizophora mangle). This wetland is part of the Florida Everglades. (Dade County, Florida; December 1975) 60 Plate 13.— Classification: system Estuarine. SUBSYSTEM Intertidal, class Scrub-Shrub Wetland, SUBCLASS Broad-leaved Deciduous, WATER regime Irregularly Flooded, water chemistry Mixohaline, soil Mineral. The dominant plant is marsh elder [Iva fruteseens). Subordinate species are black grass (Juncus gerardii), salt grass {Distichlis spicata), and saltmeadow cordgrass [Spartina patens). This wetland lies toward the landward edge of an estuarine irregularly flooded persistent- emergent wetland dominated by Spartina alterniflora, Spartina patens, and Distichlis spicata visible at the left and in the background. (Washington County, Rhode Island; July 1977) 6] vm /Mtf„*l»ji V' Plate 14.— Classification: system Estuarine, subsystem Intertidal, class Emergent Wetland, subclass Persistent, water REGIME Regularly Flooded, water chemistry Mixohaline, soil Mineral. The dominant plant is California cordgrass (Spartina foliosa). The most common subordinate is glasswort [Salicornia spp.). This wetland borders an irregularly flooded emergent wetland dominated by Salicornia spp. (San Mateo County, California; August 1976) 62 Plate 15.— Classification: SYSTEM Estuarine, SUBSYSTEM Intertidal, CLASS Emergent Wetland, SUBCLASS Persistent, WATER REGIME Irregularly Flooded, water chemistry Mixohaline, SOIL Mineral. Dominant plants are reed (Phragmites communis) and saltmeadow cordgrass [Spartina patens). Saltmarsh cordgrass {Spartina alterniflora) is a subordinate species. (Washington County, Rhode Island; July 1977) 63 *&&* Plate 16.— Classification: system Estuarine, subsystem Intertidal, class Emergent Wetland, subclass Persistent, water REGIME Irregularly Flooded. WATER chemistry Mixohaline, SOIL Organic. The dominant plant is bulrush (Scirpus olneyi). Subordinate species are saltmeadow cordgrass (Spartina patens) and saltmarsh cordgrass (Spartina alterniflora) which appear as a fringe at the water's edge. (Dorchester County, Maryland; June 1974) 1,4 Plate 17.— Classification: system Estuarine, SUBSYSTEM Intertidal, CLASS Emergent Wetland, SUBCLASS Persistent, water regime Regularly Flooded, water chemistry Mixohaline, SOIL Organic. The dominant plant is the sedge Carex lyngbyei. The photo was taken at low tide. (Coos County, Oregon; May 1977) 65 '^m M ■ ■■ ■■ Plate 18.— Classification: system Estuarine, subsystem Intertidal, class Emergent Wetland, subclass Persistent, water regime Irregularly Flooded, water CHEMISTRY Mixohaline. Dominant plants are sedges {Carex lyngbyei and C. aquatilis). Subordinate plants are bulrush {Scirpus spp.), mare's tail [Hippurus vulgaris), cinquefoils {Potentilla spp.), and bluejoint (Calamagrostis canadensis). (Anchorage County, Alaska; July 1977) <;<; Plate 19.— Classification: system Riverine, SUBSYSTEM Tidal, class Unconsolidated Shore, and Emergent Wetland, subclass Mud and Nonpersistent, water regime Regularly Flooded, water chemistry Fresh-Circumneutral, soil Mineral. The emergent wetland on the right is dominated by arrow arum {Peltandra virginica). (Cecil County, Maryland; July 1972) (17 Plate 20.— Classification: system Riverine, subsystem Lower Perennial, class Aquatic Bed, subclass Vascular, water REGIME Permanently Flooded, water chemistry Fresh-Circumneutral, SOIL Organic, SPECIAL MODIFIER Excavated. The dominant, plant is the white water lily Nymphaea odorata. 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) (is Plate 21.— Classification: system Riverine, SUBSYSTEM Lower Perennial, CLASS Emergent Wetland, SUBCLASS Nonpersistent, water regime Semipermanently Flooded, water CHEMISTRY Fresh-Circumneutral, SOIL Mineral. Dominant plants are arrow arum (Peltandra virginica) and pickerelweed (Pontederia cordata). (Hampden County, Massachusetts; July 1970) i;n Plate 22.— Classification: SYSTEM Riverine, SUBSYSTEM Lower Perennial, CLASS Unconsolidated Shore, SUBCLASS Sand, WATER REGIME Seasonally Flooded, water CHEMISTRY Mixohaline, SOIL Mineral. Young tamarisk (Tamarix gallica) plants are scattered over the flat area. (Socorro County, New Mexico; April 1978; Photo courtesy of P. B. Reed) 70 Plate 23.— Classification: system Riverine, subsystem Upper Perennial, class Rock Bottom, subclass Bedrock, water regime Permanently Flooded, WATER CHEMISTRY Fresh. (Penobscot County, Maine; October 1977; Photo courtesy of R. W. Tiner) 71 Plate 24.— Classification: SYSTEM Riverine, subsystem Upper Perennial, CLASS Unconsolidated Bottom, SUBCLASS Cob- ble-Gravel, water regime Permanently Flooded, water CHEMISTRY Fresh-Circumneutral. (Washington County, Rhode Island; July 1977) 7 'J Plate 25.— Classification: system Riverine, subsystem Intermittent, class Streambed, subclass Sand, water regime In- termittently Flooded, water chemistry Mixosaline. This stream flows at 4,200 m J /s (150,000 cfs) each year. (Socorro County. New Mexico; April 1978) 73 4"' l '1p& ! lflS7 n - Plate 26.— Classification: system Lacustrine, subsystem Limnetic, class Aquatic Bed, subclass Vascular, water regime Permanently Flooded, water chemistry Fresh-Circumneutral. The dominant plant is white water lily (Nymphaea odorata). Subordinate species are bladderworts [Utricularia spp.). (Washington County, Rhode Island; July 1977) 74 Plate 27.— Classification: SYSTEM Lacustrine, SUBSYSTEM Limnetic and Littoral, class Unconsolidated Bottom and Un- consolidated Shore, subclass Mud, WATER REGIME Permanently Flooded and Semipermanently Flooded, water chemistry Fresh, special modifier Impounded. The photo shows Foster reservoir at full pool. The semipermanently flooded area is inundated in this photograph but would be drawn down from October through March. (Linn County, Oregon; July 1975; Photo courtesy of U. S. Corps of Engineers) 75 Plate 28.-Classification: system Lacustrine, subsystem Littoral, class Unconsolidated Shore, subclass Mud, water regime Seasonally Flooded, waterchemistry Hypersaline, SOIL Mineral. (Salt Lake County, Utah; June 1973) 76 •^- . .> *, -' %? .- ■ ■•"■■;■ ... -*y* Plate 29.— Classification: system Lacustrine, SUBSYSTEM Littoral, class Emergent Wetland, SUBCLASS Nonpersistent, water regime Semipermanently Flooded, water chemistry Fresh-Circumneutral, soil Mineral. The dominant plant is bayonet rush IJuncus militaris). The subordinate species are common threesquare {Scirpus americanus) and pickerelweed [Pontederia cordata). The photo shows a gravel beach on the landward edge of the wetland. (Washington County, Rhode Island; July 1977) 77 Plate 30.— Classification: SYSTEM Lacustrine, subsystem Littoral, class Emergent Wetland, SUBSYSTEM Nonpersistent, water REGIME Permanently Flooded, WATER chemistry Fresh, SOIL Unknown. The dominant plant is pickerelweed [Pontederia cordata). (Washington County, Maine; June 1978; Photo courtesy of P. B. Reed) 7.s Plate 31.— Classification: system Lacustrine, subsystem Littoral, class Emergent Wetland, subclass Nonpersistent, water regime Permanently Flooded, WATER chemistry Fresh-Circumneutral, SOIL Mineral, special modifier Impounded. The dominant plant is American lotus (Nelumbo lutea). Subordinate plants are duckweeds {Lemna spp.) and bald cypress [Taxodium distichum). (Obion County. Tennessee; September 1975) 7 V) fc^te Plate 32.— Classification: system Palustrine, CLASS Unconsolidated Bottom, subclass Mud, water regime Permanently Flooded, water chemistry Fresh-Circumneutral, SOIL Mineral. SPECIAL modifier Impounded. This beaver pond is situated in the San Juan Mountains. (Gunnison County, Colorado: Date unknown; Photo courtesy of R. M. Hopper) 80 i' *.v c : Plate 33.— 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-aquatiea) appears along the edge of the impoundment. (Billings County, North Dakota; July 1970; Photo courtesy of J. Lokemoenl si Plate 34.— Classification: SYSTEM Palustrine, CLASS Unconsolidated Bottom, SUBCLASS Mud, water regime Semipermanently Flooded, water CHEMISTRY Mesosaline, soil Mineral. The dominant plant is summer cypress (Kochia scoparia). The subordi- nate plants are golden dock \Rumex maritimus) and goosefoot [Chenopodium glaucum). This wetland is pictured during drouth conditions when the bottom is being invaded by pioneer species. (Stutsman County, i-Iorth Dakota; August 1961; Photo courtesy of R. E. Stewart) S2 »■.*•«**»-..■-.-.». Plate 35.— Classification: system Palustrine, class Aquatic Bed, SUBCLASS Vascular, water regime Semipermanently Flooded, water CHEMISTRY Oligosaline, soil Mineral. The dominant plant is white water crowfoot {Ranunculus tricho- phyllus). (Stutsman County, North Dakota; August 1966; Photo courtesy of R. E. Stewart) *:; - i * — »-*-V^" CW'fcii rs* ^ » £~J -«»-»- •!&"**■ aO»- "*- n^^HHmn Plate 36.— Classification: system Palustrine, class Unconsolidated Shore, subclass Mud, water regime Seasonally Flooded and Intermittently Flooded, water CHEMISTRY Mixosaline, soil Mineral. The dominant plant is greasewood {Sareobatus vermieulatus). Subordinate species are rushes {Juncus spp.) and salt grass {Distichlis stricta). Some areas of the photo are semipermanently flooded unconsolidated bottom. Because annual precipitation averages only about 18 cm (7 in. I, these wetlands are heavily dependent on snowpack in the surrounding mountains as a source of water. (Saguache County, Colorado; Date unknown; Photo courtesy of R. M. Hopper) 84 »***&. ?^"% PUPf Hi Plate 37.— Classification: system Palustrine, class Moss-Lichen Wetland, water regime Saturated, water chemistry Fresh- Acid; SOIL Sphagnofibrist. The dominant plant is peat moss {Sphagnum spp.). Subordinate species include reindeer moss {Cladonia spp.), leatherleaf {Chamaedaphne calyculata), crowberry [Empetrum nigrum), and cottongrass (Eriophorum spp.). (Campabello Island International Park Maine-Canada; June 1976) 85 Plate 38.— Classification: system Palustrine, class Emergent Wetland (Foreground), subclass Persistent, water REGIME Saturated, WATER CHEMISTRY Fresh-Acid, SOIL Paleudult. The dominant plants are three-awn {Aristida strieta) and beak rushes {Rhynchospora spp,). Subordinate species include longleaf pine {Pinus palustris), orchid {Habenaria spp), yellow-eyed grass (Xyris spp.), grass pink {Calopogon spp.), and foxtail clubmoss {Lycopodium alopecuroides). (Brunswick County, North Carolina; December 1975) Sfi Plate 39.— Classification: SYSTEM Palustrine, class Emergent Wetland, subclass Persistent, water regime Permanently Flooded, water chemistry Fresh, soil Unknown. The dominant plant is common cattail [Typha latifolia). This palustrine emergent wetland borders a lacustrine system that is still ice covered. Note that the persistent vegetation remains standing. (Knox County, Maine; April 1978) 87 mlt&iL&kik Plate 40.— Classification: system Palustrine, class Emergent Wetland, subclass Persistent, water regime Semipermanently Flooded, water CHEMISTRY Fresh-Circumneutral, SOIL Organic. The dominant plant is saw grass (Cladium jamaicense). (Dade County, Florida; December 1975) 88 Plate 41.— Classification: system Palustrine, CLASS Emergent Wetland, subclass Persistent, water regime Seasonally Flooded, water chemistry Fresh-Circumneutral, SOIL Organic. The dominant plant is sedge (Carex lasiocarpa). Subordi- nate plants include sedges {Carex lacustris and C. rostrata), marsh smartweed {Polygonum coccineum), bladderwort {Utri- cularia vulgaris), bluejoint {Calamagrostis canadensis), and pondweed {Potamogeton gramineus). (Beltrami County, Min- nesota; June 1972; Photo courtesy of J. H. Richmann) 89 m ettffiXHI Plate 42.— 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 courtesy of H. A. Kantrud) ')() * -.,.. ■.■■■■■;■ h: s . v. <* . ■ <•• ' ■ ■■■. Y \ .-.' \: «■ '.*•.'. ; . \ S€H^ Plate 43.— Classification: system Palustrine, class Emergent Wetland, water regime Temporarily Flooded, water chemistry Fresh, son. Mineral, special modifier Farmed. Dominant species include nut sedge {Cyperus sp.), arrow arum {Peltandra virginica), and barnyard grass [Echinochloa crusgalli). (Dade County, Florida; January 1978; Photo courtesy of P. B. Reed) 91 f \CwrnL I r i Plate 44.— Classification: system Palustrine, CLASS Emergent Wetland, SUBCLASS Persistent, water regime Semipermanently Flooded, water chemistry Mixosaline, SOIL Mineral. Dominant plants are alkali bulrush {Scirpus paludosus) in foreground and hardstem bulrush {Scirpus acutus) in background. (Stutsman County, North Dakota; August 1962; Photo courtesy of R. E. Stewart) 92 Plate 45.— Classification: SYSTEM Palustrine, CLASS Emergent Wetland, subclass Persistent, water regime Seasonally Flooded, water chemistry Polysaline, SOIL Mineral. The dominant plant is spike rush (Eleoeharis palustris). Subordinate plants include marsh smartweed (Polygonum coccineum), slough sedge (Carex atherodes), and foxtail (Alopecurus aequalis). (Stutsman County, North Dakota; August 1962; Photo courtesy of R. E. Stewart) 93 4M Plate 46.— Classification: SYSTEM Palustrine, CLASS Emergent Wetland, SUBCLASS Persistent, water regime Seasonally Flooded, water CHEMISTRY Mixosaline, soil Mineral. The dominant plants are sedge (Carex spp.), bulrush {Scirpus spp.), rush IJuncus spp.), and foxtail (Alopecurus aequalis). This wetland is typical of irrigated hay in the West. Water mav be diverted from rivers or may be from artesian wells as in this plate. (Saguache County, Colorado; Date unknown; Photo courtesy of R. M. Hopper) 94 Plate 47.— Classification: system Palustrine, CLASS Emergent Wetland, SUBCLASS Persistent, water regime Seasonally Flooded Tidal, water chemistry Fresh, SOIL Unknown. Dominant vegetation includes cattail [Typha sp.), grasses {Gramineae), alder [Alnus sp.), and spiraea (Spiraea sp.). (Knox County, Maine; April 1978; Photo courtesy of P. B. Reed) 95 Plate 48.— Classification: SYSTEM Palustrine, class Emergent Wetland, subclass Persistent, water regime Saturated, water chemistry Fresh, soil Unknown. The dominant plants are sedges (Carex spp.). (Lassen County, California; August 19751 "Vi >M tt'.BB Plate 49.-Classification: SYSTEM Palustrine, CLASS Emergent Wetland, SUBCLASS Persistent, water REGIME Seasonally Flooded, water chemistry Fresh, soil Mineral, special modifier Farmed. The dominant plant is taro (Colocasia esculenta). (Kauai County, Hawaii; September 1972; Photo courtesy of E. Krider) 97 1 Plate 50.— Classification: SYSTEM Palustrine, class Scrub-Shrub, 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 [Pinus contorta). (Coos County, Oregon; May 1977; Photo courtesy of D. Peters) ys Plate 51.— Classification: system Palustrine, CLASS Scrub-Shrub, subclass Broad-leaved Evergreen, water regime Saturated, water chemistry Fresh-Acid, SOIL Sphagnofibrist. The dominant plants are Labrador tea (Ledum groen- landicum), sheep laurel (Kalmia angustifolia), and leatherleaf (Chamaedaphne calyculata). Subordinate species include peat moss {Sphagnum spp.), crowberry {Empetrum nigrum), cloudberry {Rubus chamaemorus), and black spruce (Picea mariana). (Washington County, Maine; June 1976) 99 r tim Plate 52.— Classification: SYSTEM Palustrine, CLASS Scrub-Shrub, SUBCLASS Broad-leaved Evergreen, water regime Saturated, water CHEMISTRY Fresh- Acid, SOIL Medisaprist. The dominant plants are black ti-ti (Cyrilla racemiflora) and honeycup (Zenobia pulverulenta). Subordinate species include leatherleaf {Chamaedaphne calyculata), peat moss (Sphagnum spp.), highbush blueberry [Vaccinium corymbosum), loblolly bay {Gordonia lasianthus), pond pine (Pinus serotina), and black highbush blueberry (Vaccinium atrococcum). (Brunswick County, North Carolina; December 1975) 100 IF .---= Plate 53.— Classification: system Palustrine, class Forested Wetland, subclass Broad-leaved Deciduous, water regime Saturated, WATER CHEMISTRY Fresh- Acid, soil Organic. The dominant plant is red maple {Acer rubrum). Subordinate species include black gum [Nyssa sylvatica), highbush blueberry {Vaccinium corymbosum), great laurel [Rhododendron maximum), and winterberry (Ilex verticillata). (Washington County, Rhode Island; June 1977) 101 Plate 54.— Classification: system Palustrine, class Aquatic Bed (foreground). Forested Wetland (background), subclass Floating (foreground) and Needle-leaved Deciduous (background), water regime Permanently Flooded, water CHEMISTRY Fresh. The dominant plant in the foreground is water lettuce (Pistia stratiotes) and in the background bald cypress (Taxodium distichum). The subordinate species is arrowhead {Sagittaria spp.). (Collier County, Florida; January 1978) 102 Plate 55.— Classification: system Palustrine, CLASS Forested Wetland, SUBCLASS Needle-leaved Evergreen, water regime Seasonally Flooded, water CHEMISTRY Fresh-Acid, SOIL Organic. The dominant plant is Atlantic white cedar (Chamae- cyparis thyoides). Subordinate plants include highbush blueberry (Vaccinium corymbosum), peat moss (Sphagnum spp.), winterberry {Ilex verticillata), and red maple {Acer rubrum). Low vegetation in the foreground includes leatherleaf (Chamae- daphne calyculata) and Virginia chain-fern {Woodwardia virginiea). (Washington County, Rhode Island; July 1977) 103 Plate 56.— 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) i,- U.S. GOVERNMENT PRINTING OFFICE: 1981 - 338-687 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 en- vironmental and cultural values of our national parks and historical places, and providing for the enjoyment of life through outdoor recre- ation. The Department assesses our energy and mineral resources and works to assure that their development is in the best interests of all our people. The Department also has a major responsibility for American In- dian reservation communities and for people who live in island territories under U.S. administration. t> vi*S» Office of Biological Services Fish and Wildlife Service U.S. Department of the Interior Washington, DC. 20240 THIRD CLASS BOOK RATE