Wetland Classification

NREM 665

OutlineI. Why classify?

II. History & development of classification systems

III. Comparison of Cowardin, Canadian, & HGM systems& HGM systems

IV Cowardin system2

IV. Cowardin system

I Why Classify?I. Why Classify?Perceive order in diversityPerceive order in diversityNeed system for grouping wetlands in an orderly logicalwetlands in an orderly, logical way

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Used in other disciplinesZoology & Botany

Soil Taxonomy

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Advantages & DisadvantagesHelps to assess evolutionary & successional patternssuccessional patterns

Aids in managementAids in management

Systems can be biased regionalisticSystems can be biased, regionalistic, stagnant

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II. History & Development of W tl d Cl ifi ti i th U SWetland Classification in the U.S.

1954: USFWS conducted inventory of1954: USFWS conducted inventory of wetlands to assess waterfowl habitatMartin et al. developed Classification ofMartin et al. developed Classification of Wetlands of the United States (1953), used as a framework for inventoryResults of inventory published by Shaw & Fredine (1956)This publication Wetlands of the UnitedThis publication, Wetlands of the United States, became known as USFWS Circular 39

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Circular 39Circular 39

Emphasis: waterfowl

Limitations:

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Other Classification t d l dsystems developed1 Stewart & Kantrud 19711. Stewart & Kantrud 19712. Golet & Larson 19743. Jeglum et al. 19744. Odum et al . 19745. Zoltai et al. 19756 Millar 19766. Millar 1976

Emphasis:8

Emphasis: Limitations:

Development of new (C di )

psystem (Cowardin)

1974: USFWS directed Office of Biological Services to conduct new National Inventory of WetlandsNational Inventory of Wetlands New classification system developed as 1st step of Inventoryof InventoryGoals of the new system were to:

1. describe homogenous ecological units 2 it i t th t ill id i t2. arrange units in a system that will aid in res. mgmt.3. furnish units for inventory & mapping4. provide uniformity in concepts & terminology

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Improvements on Circular 39Cowardin broader in scopeDeveloped by multidisciplinary team

Wetlands defined as possessing 1 or more of th f ll i 3 t

Developed by multidisciplinary team

the following 3 components:a. hydrophytic vegetation b h d i ilb. hydric soilc. wetland hydrology

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Cowardin Summary & CommentaryCowardin Summary & Commentary

Emphasis: on vegetation cover →Emphasis: on vegetation cover →interpreted from aerial photos. Ecologically-related areas of deepwater, traditionally not considered wetlands, included as deepwater habitats.Limitations:

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Development of the Canadian Classification SystemClassification System

1976: National Wetlands Working Group (NWWG) formed as combination of gov’t, NGO, university, private groupsNWWG published:

Atlas: Canada’s Wetlands (1986)Reports: The Canadian Wetland Classification

System (1987)1997: Canadian Wetland Classification System V2

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‘97 version improves on ‘8797 version improves on 87Goal of new version:Goal of new version:

“to establish a common language for the wetlandlanguage for the wetland resource, usable by all Canadians”Canadians Refined terminology, d fi itidefinitions

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Basis of Canadian SystemEmphasizes conditions that have effected

wetland development such as:wetland morphologywater sourcebasin depth, shapeplant communitiesppeat/sediment characteristics

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3 Levels of Canadian System3 Levels of Canadian System1) Class

bogfenswamp marshmarshshallow water

2) Form2) Formsubform

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3) Type

Classes: based on origin of wetland & nature ofClasses: based on origin of wetland & nature of wetland environment

Forms: subdivisions of each class based on morphology, surface pattern, water type, soilsmorphology, surface pattern, water type, soils

Types: subdivisions of forms & subforms based onTypes: subdivisions of forms & subforms based on physiognomic characteristics of vegetation communities

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Summary & Assessment of C di S

yCanadian System

S stem of ke s / q estions to help separateSystem of keys w/ questions to help separate forms & subforms w/i a classSimpler more focused on WTLs than CowardinSimpler, more focused on WTLs than Cowardin

E h i d l t h d l tl dEmphasis: development, hydrology, peatlandsLimitations:

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Hydrogeomorphic (HGM) Classification System

Focused on evaluating functions of wetlands simply, rapidly, inexpensively.D l d i t CWA S ti 404Developed in response to CWA Section 404 regulations.Permit process requires assessing effects ofPermit process requires assessing effects of development on wetland functions. Available methods for assessing functions inadequate.methods for assessing functions inadequate.

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HGM emphasizesHGM emphasizes 2 abiotic controls in maintainingin maintaining wetland functions

Hydrology controls amount, source, season of water entering wetlandGeomorphology controls where water comes from & whether it leaves

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HGM i t d d tHGM intended to:

1. Classify wetlands into distinct types w/ similar functions

f f2. For specific types, evaluate which functions are performed & estimate degree to which they are performedthey are performed

3. Estimate amount of wetland area & corresponding functions lost w/ dvpt & provide mechanism for determining mitigation ratio

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3 components used to classify wetlands of similar functionwetlands of similar function

1. depressional2. riverine

{1) geomorphic setting

3. lacustrine fringe4. tidal fringe5. slope{6. mineral soil flats7. organic soil flats

{2) water source &

transport

3) hydrodynamics

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Salt marsh

Cowardin Canadian HGMRamsar

System:Estuarine

Class:Marsh

Geomorhpic Setting:

Tidal FringeWater Source:Surface water

Hydrodynamics:

BidirectionalClass:

Coastal

Subsystem:

Estuarine

Form:

Marsh Tidal Fringe Surface water Bidirectional

Type:

Coastal

Class:

Intertidal

Subform:

Tidal Marsh Intertidal Marsh

Subclass:

Emergent Wetland Tidal Bay Marsh

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Subclass: Persistent

Summary of Classification Systems

Circular 39 (1956)T Hi hi l

Canadian (1997)Type: HierarchicalEmphasis:waterfowlLimitations: not

comprehensive

Type: HierarchicalEmphasis:development

hydrol., peatlandscomprehensive

Co ardin (1979) HGM (1993)

Limitations: weak for swamps, shallow water

Cowardin (1979)Type: HierarchicalEmphasis:vegetation

HGM (1993)Type: FunctionalEmphasis:abiotic controls,

Limitations: too much deepwater not enough wetland

hydrol, geomorph.Limitations: regional

development, funding

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