Goals of Classification

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Goals of Classification ? To describe ecological
units that have certain homogeneous natural
attributes ? To arrange these units in a unified
frame work for the characterization and
description of wetlands, that will aid decisions
about resource management ? To identify
classification units for inventory and
mapping. ? To provide uniformity in concepts and
terminology Mitsch and Gosselink 2000
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USFWS Circular 39 (Shaw and Fredine 1956) 20
types of wetlands under 4 major categories ?
Inland fresh areas ? Inland saline areas ? Coast
fresh areas ? Coastal saline areas Sub-categorie
s were determined by water depth and duration of
flooding National Wetland Inventory (Cowardine
et al. 1979)
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History of classification ? Peatland
classifications ? Circular 39 ? NWI (Cowardin
et al.1979)
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NWI began in 1974 "Classification of Wetlands
and Deepwater Habitats of the United States"
Cowardine et al. 1979 Hierarchy similar to plant
or animal taxonomy and keys
System subsystem class subclass
(modifiers) dominance type
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System Marine open ocean overlying continental
shelf Estuarine ocean water is at least
occasionally diluted by fresh water
runoff Riverine water systems contained within
a channel with 2 exceptions (1) wetlands
dominated by trees, shrubs, persistent
emergents, emergent mosses, or lichens and (2)
deepwater habitats with salts greater than 0.5
ppt
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Lacustrine wetlands and deepwater habitats with
characteristics including ? situated in
topographic depression or dammed river channel
? less than 30 aerial vegetative cover ? gt8
ha. ? lt 8 ha included when an active
wave-formed or bedrock shoreline makes up all
or part of the boundary ? water gt 2m at low
water
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palustrine ? all vegetation dominated
wetlands with water ocean derived salinity lt
0.5 ppt ? lt 8 ha ? lacking wave-formed or
bedrock shoreline features ? water depth lt 2m at
deepest part during low water
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(Subsystems) Subtidal substrate
continuously submerged Intertidal substrate
exposed during low tide, including splash
zone Tidal water velocity fluctuates
under tidal influence Lower Perrenial
continuous flow, low gradient, no tidal
influence Upper Perrennial continuous
flow, high gradient, no tidal influence Intermitt
ent water does not flow for part of the
year Limnetic deepwater habitats in
lakes Littoral shore to 2 m below low water
or maximum existent of nonpersistent emergent
plants
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Classes (general appearance) When gt 30
vegetative cover vegetation class is used, lt
30 substrate class Below the level of class,
the system is open ended ? Subclasses
(persistent, nonpersistent) ? Dominance types
(plant or animals) ? Modifiers (water regime,
salinity, pH, and soil)
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Modifiers (never used at the system or subsystem
level) ? Water regime modifiers Tidal (estuarine
and marine) - subtidal - irregularly exposed -
regularly flooded - irregularly
flooded Nontidal (riverine, palustrine,
lucastrine) - permanently flooded -
intermittently exposed extreme drought -
semipermanently flooded growing season most
years - seasonally flooded water absent end of
growing season - saturated saturated during
growing season rarely flooded - temporarily
flooded brief periods of growing season -
intermittently flooded unpredictable and not
annual - artificially flooded -
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Water chemistry modifier ? Salinity
modifiers Conductivity Coastal Inland s
alinity (ppt) µMhos at 25c Hyperhaline Hypersa
line gt 40 gt 60,000 Euhaline Eusaline 30
40 45 60,000 Mixohaline (brackish) Mixosaline
0.5 30 800 45,000 Polyhaline
Polysaline 18 30 30 45,000 Mesohaline
Mesosaline 5 - 18 8 30,000 Oligohaline
Oligosaline 0.5 5 800 8,000 Fresh Fresh lt
0.5 lt800 ? pH modifiers Acidic lt
5.5 Circumneutral 5.5 7.4 Alkaline gt7.4
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Special modifiers ? Excavated in basin or
channel ? Impounded manmade or beaver dams
obstructing outflow ? Diked manmade dikes
obstructing inflow ? Partly drained water
level decreased but still a wetland ? Farmed
altered and supporting crops but hydrophytes
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