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HomeMy WebLinkAboutAPA900(") ---=----co (") M ~g • 0 --l!) -l!) r-- (") (") CLASSIFICATION OF WETLANDS .AND DEEP-WATER HABITATS OF THE UNITED STATES (An Operational Draft) • QH 87.3 .C533 1977 October 1977 FISH AND WILDLIFE SERVICE U.S.DEPARTMENT OF THE INTERIOR .' CLASslFICATIONOFWETLANDS AND DEEP-WATER HABITATS OF THE UNITED STATES"-'-.........'-.-..... ,(An Operati.onaIDraft) By Lewis M.Cowardin,U.S.Fish and Wildlife Service,Northern Prairie Wildlife Research Center Virginia Carter,U.S.'Geological Survey,Water Resources Division Francis C.Golet,Department of Forest and Wildlife Management,University of Rhode Island Edward T.LaRoe,U.S.National Oceanic and Atmospheric Administration,Office of Coastal Zone Management , Edited by J.Henry Sather a)H ~1.'3 .C533 ''177 / .. • ~co M 1"- M ooo LO LO 1"- M M October 1977 Fi~h and Wildlife Service U.S.Department of the'lnterior ARLIS Alaska Resources Library &Information Servtces Anchorage,Alaska FOREWORD •.~j The NationalWetlimdInventoryProjectbf197S-'-/'9 has sought (as did its predecessor of 1954,th,e first N<:lt'ional Wetland Inventory ,Proj ect),a wetland classification system that could be consistently and equally applied to the varying'aspects of the wetland resources of the United States. The result of that search,"The Classification of Wetlands and Deep-Water Habitats of the United States,"has been under development for over two years,and has undergone peer review to an exteritwhich is perhaps unprecedented in the history of documents published by the Fish and Wildlif~Ser:vice.We want to acknowledg.e and thank those individuals and organizations who gave us assistance and guidance during the development of this system.' We have termed this document "An Operational Draft,"and the selection of that phrase was made for two reasons.'First,this classi- fication system needs to be used in the field for a substantial period of time so that inconsistencies can be isolated and viable alternatives be examined.Secondly,similar to the Martin.,.et al<1953)system,this system will most assuredly need revising in the~oriths and years ahead. -1._. ':.''t,''!. ,- TABLE OF ~ONTENTS Page I.INTRODUCT ION I I.WETLANDS AND DEEP-WATER HABITATS CONCEPTS . DEFINITIONS Wetland .,. .... 3 3 4 4 Systems and Subsystems HI ERARCHI CAL STRUCTURE . II I.THE CLASSIFICATION SYSTEM Deep-water Habitats 5 5 7 7 7 ., ~. ., ,. . ,. .~ 13 13 13 13 14 14 14 14 14 14 15 15 16 16 16 16 16 16.ARtis·16 Alaska Resources Library &Information Semces Anchorage,Alaska ",.. ., .. ,. ,., . ...... i i ., ., ..' Definition Limits ..• Definition Limits .. Deseri pt ion Subsystems • Subtidal. Intertidal Classes Definition Limits .. Des c rip t i on Subsystems . Subtidal. Intertidal Classes RIVERINE. MARl NE . . . . ESTUARINE LIMITS ... ... .. TABLE OF CONTENTS (c,ontinued) Classes,Subclasse~and Do~inahce Types Defi nit i on Oeser i pt ion Subclasses and Dominance Types Bedrock Boulder UNCONsoLIDATED BOTTOM ROCK BOTTOM If ,- Page 17 17 18 18 18 19 19 19 19 20 20 20 20 20..21 21 21 21 21 22 22 23 26 26 26 27 27 27 27 27 27 29 .29 •29 30 30 Types .'. .' Definition Limi ts .. Descri pt ion Subsystems Li'mnetic Li ttoral Classes Defi nit i on Limi ts .. Description Subsystems Classes Descri pti on Subsystems . Ti dal Lower Perennial Upper Perennial Intermi ttent Classes Definition. Description Subclasses and Dominance Cobble/Gravel Sand . . . Mud Organic LACUSTRINE PALUSTRINE i i j TABLE OF CONTENTS (cot'!t inued) Page AQUATIC BED ROCKY SHORE Definition Description Oefi ni t ion Descri pt ion Subclasses and Dominance TYPeS Cobble/Gravel Sand .. Mud Organ ic Defirrition . Description . Subc lasses and Domi nance Types Submergent Algal .. Submergent Vascular Submergent Moss Floating-leaved Floating . .30 30 30 30 31 32 32 33 33 33 33 34 34 34 34 35 35 35 36 36 36 36 37 37 37 37 37 38 38 38 39 39 39 39 39 ,, ., .. ,.. .. ., " .. ". ". Types " Dominance Types • Definition Descri pti on ". Subclasses and Coral Mollusc Worm Definition - - -- - Descri pt i on Subclasses and Dominance "Cobble/Gravel .• Sand .• Mud .".... Organic Vegetated Flats REEF .... FLATS STREAMBED .. • ·iv TABLE OF CONTENTS (cont i nued) FORESTED WETLAND SCRUB/SHRUB WETLAND EMERGENT WETLAND Subclasses and Dominance Typei Bedrock Boulder ... 0, .- Page 39 40 40 ..41 41 41 42 42 42 43 43 43 43 43 43 44 .44 44 44 44 45 46 46 46 46 46 46 47 ..47 47 47 47 47 48 48 .' Types .' Defi nit i on Description Subcl asses and Domi nance Cobble/Gravel Sand . De fin I t i on . . Description Subclasses and Dominance Types Moss ..' Li chen . De r i nit i on . . Description Subclasses and Dominance Types Broad-leaved Deciduous Needle-leaved Deciduous Broad-leaved Evergreen. Needle-leaved Everg~een bead .... De fin it i on . . Description Subclass~s and Dominance Types Persistent. Nonpersistent. Def i nit ion . . .Des cr i pt ion Subclasses and Dominance Types Broad~leaved Deciduous' MOSS/LICHEN WETLAND BEACH/BAR v TABLE OF CONTENTS (continued) EXCAVATED ART I FI CIAL NONTIDAL . !MPOUNDED Page 48 48 49 49 49 49 50 50 50 51 51 51 52 52 .52 52 52 52 53 53 53 54 57 58 59 60 60 60 60 61 61 .. Need Ie-I eavedDec i duous Broad-leaved Evergreen . Needle-leaved Evergreen Dead . TIDAL Subti da I Irregularly Exposed Regularly Flooded ~ Irregularly Flooded Permanently Flooded. Intermittently Exposed Semi permanently Flooded Seasonally Flooded. Saturated.... . . . . Temporarily Flooded .. Intermittently Floo.ded Artificially Flooded. pH MO DI FIE RS SALINITY MODIFIERS DIKED FARMED .• PARTIAL~Y DRAINED Water Regime Modifiers Water Chemistry Modifiers So i I Mod if ie rs Special Modifiers .MODIFIERS .. • vi IV.REGIONALIZATION TABLE OF CONTENTS (cant inued) Page 62 V.USE OF THE CLASSIFICATION SYSTEM HIERARCHICAL LEVELS AND MODIFIERS RELATIONSHIP TO OTHER WETLAND CLASSIFICATIONS LITERATURE CITED ~.. APPENDIX A -SCIENTIFIC AND COMMON NAMES OF PLANTS APPENDIX B -SCIENTIFIC AND COMMON NAMES OF ANIMALS APPENDIX C -CRITERIA FOR OIST1~GUISHING ORGANIC SOILS FROM MINERAL SOILS . vi i 67 69 71 79 90 94 97 Table LI ST OF TABLES Pilqe pH Modifiers Used in This Classification System2 Salinity Modifiers Used in This Classification System..",.......,56 58 3 4 5 Comparison of Wetland Types Described in Circular 39 with Some of the MC;ljor Components Of this Classification System . Comparison of the Zones of Stewart and Kantrud's (1971)Classification with the Water Regime Modifiers used in this Classification System Comparison of the Water Chemistry Subclasses of Stewart and Kantrud (1972)with the Water Chemistry Modifiers used in this Classification System-. . . . . . • . . . . . . . . . . • .r vi i i 72 77· 78 "L I ST OF FIGURES .Figure Page This figure is not included in this draft. 2 This fi gure is not included in th i.s draft. 3 DIAGRAM OF THE CLASSIFICATION HIERARCHY FOR THE MARINE SYSTEM ····.~..· ······8 4 DIAGRAM OF THE CLASS IFICAT ION HIERARCHY FOR THE ESTUARINE SYSTEM ·...·······.9 5 DIAGRAM OF THE CLASSIFiCATION HIERARCHY FOR THE RIVERINE SYSTEM ·.· · .•.··· ··10 6 DIAGRAM OF THE CLASSIFICATiON HIERARCHY OF THE LACUSTRINE SYSlEM ·.· · ·....· · ·····11 7 DIAGRAM OF THE CLASSIFICATION HIERARCHY OF· THE PALUSTRINE SYSTEM . ix e·• • • • •-.• • 12 ". I. I NTRODUCT ION In 1954,the U.S.Fish andWildl ife Service conducted an inventory of the wetlands of the United States (Shaw and Fredine 1956). Since then,wetlands in this country 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 wet- lands,and some statewide wetland surveys have been conducted. In 1974,the U.S.Fish and Wildlif~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 (Montanari and Townsend,..!..!!.press).It will provide basrc data on the characteristics and extent of the nation's wetlands and deep-water habitats and 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 Circular 39 (Shaw and Fredine 1956).This document has been one of the most common and most influential tools used in the continuous battle to preserve a ra~idly vanishing and critically valuable national resource (Stegman 1976).However,the shortcomings of this work are well-known and have been documented (e.g.,Leitch 1966,Stewart and Kantrud 1971). 2 In their attempt at simpl ification,Martin et ale ignored eco- logically critical di~ferences,such as the distinction between fresh and subsaline in~and wetlands;also,dissimilar habitats,such as boreal black spruce forests and southern cypress-gum forests were often placed in the same category,with no provision in the system for distinguishing between them.Because of the central emphas is on waterfowlhab i tat,far greater attention was paid to vegetated areas than tononvegetated areas. Probably the greatest single disadvantage of the Martin et al.system was the inadequate definition of types,which led to inconsistencies in application. Numerous other classifications of wetlands.and deep-water habitats have been developed,but most of these are regional systems and none would fully satisfy natibnal need~(Stewart and Kantrud 1971,Golet and Larson 1974;Jeglum et a1.1974,Odum et aL 1974,Zoltai et a1.1975, Millar 1976).Because of the weaknesses inherent in Circular 39,and because our understa·nding of wetland ecology has grown significantly since 1954,the U.S.Fish and Wildl ife Service elected to construct a new national classification system as the first step toward a new national inventory.The new classification has been designed to meet three long- range objectives:J)to group ecologically similar habitats,so that value judgments can be made;2)to furnish units·for inventory and mapping; and 3)to provide uniformity in concepts and terminology through- out the United States .. " .... 3 I I.WETLANDS AND DEEP-WATER HABITATS CONCEPTS For centuries we have spoken of marshes,swamps and bogs,but only relatively recently have we attempted to group these landscape units under the single term,"we tland.11 The need to do this has grown .out of our desire to understand and describe the characteristics and values of all types of land,and to wisely and effectively manage wetland eco- systems.There is no single,correct,indisputable,ecologically sound definition for wetland,primarily because of the diversity of wetlands and~because the gradation between dry and wet environments is continuous. The reasons or needs for defining wetland vary;as a result,a great prol iferation of definitions has arisen.Our primary task here is to impose boundaries on natural ecosystems for the purposes of inventory, evaluation and management. In general terms,wetland is land where 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.It spans a continuum of environments where terrestrial and aquatic systems intergrade.The concept of wetland embraces a number of characteristics including:1)the elevation of the water table with respect to the ground surface;2)the duration of surface water;3)the soil types that form under permanently or temporarily saturated conditions;and 4)the various kinds of plants and animals that have become adapted to I ife in a " we t"env.ironment.The single feature that most wetlands share is soil 4 that,at least periodically,is saturated with water.This creates severe physiological problems for all plants except hydrophytes,which are adapted for life in water or in soil that is at least periodically saturated. Deep-water habitats include environments where surface water is permanent and often quite deep so that water,rather than air,is the principal medium within which the dominant organisms live,whether they are attached to the substrate or not. We define five major ecological systems:Marine,Estuarine, Riverine,Lacustrine ahd Palustrine.The first four of these include both wetland and deep-water habitats while the Palustrine includes only wet landhab itat. DEFINITIONS Wet land Instead of placing arbitrary limits on the position and fluctuation of the water table for the purpose of defining wetland,we have attempted to define wetland broadly and simply,and then to place 1 imits on the concept.For thepurpose of this classification system, WETLAND is defined as land where the water table is at,near or above the land surface long enough to promote the formation of hydric soils l or to support the growth of hydrophytes.2 In certain types of wetlands, IThe U~S.Soil Conservation Service is currently preparing a preliminary list of hydric soils for use in this classification system. 2 . The U.S.Fish and Wildife Service is currently preparing a 1 ist of the hydrophytes of the nited States. 5 vegetation is lacking and soils are poorly developed or ~bsent as a result of freguent and drastic fluctuations of surface-water levels t wave action t water flow t turbidity or high concentrations of salts or other substances in the water or substrate.Such wetlands can be recognized by the presence of surface water or saturated substrate at some time during each year and their location within,or adjacent to, vegetated wetlands or deep-water habitats. Wetland as defined here includes land that is identified under other categories in some land-use classifications.For example t wetland and farmland are not necessarily exclusive.Many areas that we define as wetland are farmed during dry periods,but if they are not tilled or planted to crops,they will supporthydrophytes. DeeE-water Habitats Permanently flooded lands lying below the deep-water boundary of wetland are defined as DEEP-WATER HABITATS in this classification.As in wetlands,the dominant plants arehydrophytes;however t the sub- strates are considered "not-soil 'l because the water is too deep to support emergent vegetation (U.S.Soil Conservation Service 1975). LIMITS The upland 1 imit of wetland is designated as:1)the boundary between land with predominantly hydrophytic cover and land with pre- dominantly mesophytic or xerophytic cover;2)the boundary between soil that is predominantly hydric and soil that is predominantly nonhydric; or,in the case of wetlands without vegetation or soils;3)the boundary 6 between land that is flooded or saturated at some time during years of normal precipitation and land that is not.Areas with drained hydric soils that are no longer capable of supporting hydrophytes are not considered wetlands. The boundary between wetland and deep-water habitat in the Marine and Estuarine Systems coincides with the elevation of the extreme low water of spring tide (ELWS);permanently flooded areas are considered deep-water habitats in these systems.The boundary between wetland and deep-water habitat 1n the Riverine,Lacustrine and Palustrine Systems I ies at a depth of 2 m (6.7 ft)below low water;however,if emergents, shrubs or trees grow beyond this depth at any time,their deep-water edge is the boundary.Figures I and 2 illustrate the identifying features and limits of wetlands and deep-water habitats where tidal and nontidal forces predominate. 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 permanently flooded and wet,nonflooded soils.In their wetland classification for Canada,Zoltai et al.(1975) include only areas with water less than 2 m deep. 7 II I~THE CLASSIFICATiON SYSTEM The structure of this classification is hierarchical,progress- ing from systems and subsystems,at the most general levels,to classes, subclasses and dominance types.Modifiers for water regime,water chemistry and soi Is are applied to classes,subclasses and dominance types.Figures 3-7 illustrate the classification structure within each of the five ecological systems.Special modifiers are also included to describe wetlands and deep-water habitats either created or highly modi- fied by man or beavers. HIERARCHICAL STRUCTURE Systems and Subsystems The term SYSTEM refers here to a complex of wetland and deep- water habitats that share the influence of one or more dominant hydro- logic,geomorphologic,chemical,or biological factors.We have chosen to subdivide systems into more specific cate~ories called SUBSYSTEMS. The characteristics of the five major systems have been discussed at length in the scientific I iterature and the concepts are well- recognized,but there is frequent disagreement as to which attributes should be used to bound the systems in space.For example,both the limit of tidal influence and the limit of ocean-derived salinity have been proposed for bounding the upstream end of the Estuarine System (Caspers 1967).As Bormann and Likens (1969)pointed out,boundaries of ecosystems are defi ned to meet pragmat ic needs. 8 l-ru CD........"~__-[~~~~I ~/~~~~:~---C_------Mya Q) CC .j..J','Mud -------------------t-iacoma~-E"Sand -----------..------Aren ico la ~'"'.'Cobble!Gravel~-~~-----Littorina -I«o ~---i w I-'z >-Q) ~l- U '0OLa::tf) .,----1=Soul der Bedrock -----.-----.--.----- Balanus ;1yti lus Lw l- I/) >- I/) w·z a:: <t: L w:r: I- di [worm ---------:----------Sabel1aria ~,Cor~l---~-------~--":"-c-Porites 't ~,worm --------,..-~-------SabellariaQ)---,a::,Coral ------~----------Acropora wz a:: <t: L -I«o l- CC :::::> I/) u .j..J -0C'Q'Q) ::JCC cr "« u .j..J -0ruQ) ::JCC cr« o E Vl 0,c .j..Jo.j..J u 0ccc :::::> -'--{Submergent Vascu Ia r ---Zostera "Submergent Algal r Submergent Vascular ---Thalassia'~Submergent Algal ------Matrocystis -i Organic" ",'Mud ----------":"--------Urechis .Sand ------------------Tell ina ,',Cobble/Gravel ---------Modiolus c:::o 1.L >-:.:uc:::: <i. 0::: W :r: zo !;: u ~ I/) I/) <t: .-I U w :r: I- ~o L<t:a:: ~<t: Cl (V'\ Q) l- ::J 01 ~ ... E ~0,r ,u.j..J~o .j..J a::0 c::l Boul der Bedrock Hippospongia St~ongylocentrotuS E Q).--.Q)V'l U V'l.j..J V'l 'Q) E III ru ~Q)~Q)>-Vl ~c OcOc +J V'l V'l U .->-E Vl -0'ru -0 EI-,ru >-::J ~::J 0 >< I/)I/)U I/)Cl ~• 9 ""QI c:~III --[Dead '~::;,--Broad~If'i1ved Evergrep.n -------Rhizophora mangle o QI"-~ '.0 -g -f Dead ,~i:~Broad-leaved Evergreen ~i5i'Q;Broad-leaved Deciduous V>3, Conocarpus ~ Iva frutescens ..."c:c~III Nonpersistent --~-------------~::;[Persistent ----~--~--~-------- ~~..... Nuphar ~ Spartlna alternlflora ~ '"« o -'2" QI ~ "01 "- ::t:..... l- V>>V> .....z e<:«:::> l- V>..... ..... :I: l- e<:o "- >:I: Ue<: ~..... :xc 5 !;: u "- V> Vl«~u ..... :I: I- "-o Macoma R;,;TITa Dendraster Acmaea C'Fithciiiia 1us Macroalgalmat Nere Isuca-MYtI ius Sabellarla Ostrea ---------------------- ---------------------- Submergent Vascular ------.---Zostera [ Worm -------------------------Sabellarla------~Mollusc ----------------------Crassostrea >-QI~~[Boulderg~.Bedrock e<:V> Vegetat~d -------------------- ~~,Organic_I'll "-S, C, ~[Worm ----------------QI --------- e<:Mollusc -----------------'----- o ..."~:l , <T« ""'QI QI e<: -Organic~,~~~~~d-=========================~£~Cobble/Gravel ----------------:::> .~-{Flo,ating ElchhornJa ~Ipes ~]Floating-leaved --------------Nymphaea odorata~~Submergent Vascular ----------~maritima « .Submergent Algal -------------Ulva ]-{organic~,Mud :::,.'Sand ~.Cobble/Gravel V> ,~~[~~~~l~/~~~:~;-----------------Emerita ~I~«o l-e<:..... I-z ~«o Iii:::> V> .....z e<:«:::> l- V>..... .. .>t ~u ...[Bou lder ~~Bedrock '" Cnem i do ca rpa Mur I cea QI 0- >-~ I-CIl QI E QI- QI CIl o 0-...CIl c E E CIl III til III QI >-CIl U c X...CIl CIl .-..... '".0 to .0 E~ >-"-",g V>V>U V> 10 >-v-j ~[Boul der o .r:.Bedrocka:VI r-z:wr-r- :>:cr:wr-z, -".r:.L. U III Ill", V '" Sand~Cobble/Gravel ....c'U V ~'".._'.~--,.._,...t-NOflp"rs!slent --------------------Equlsetum fluvlaflle ~{ uJ ' -E'Mud -..",---,------------.--------Tublfex .Sand.----,-------.,----------------Lininodrll us Cobble/Gravel ----------,;-.-------Chlronomldae -1 Float I ng --------.---------------.El chhorn Ia crass I pes .'Floating,:,leaved -.------.---..--.,,,-Nymphaeaod~ ,SUbmergent Moss --'------'.0----'-.,---FontlnaUs .',...,Submergen!'Vascu I ar u_.'----Potamcigeton ep I hydrus 'Submergent 1119 a I -------..---------Nltella 'w Z cr: w> cr: .J«cr:-' WZ Q.z Q.W::>cr:w Q.. .J« a:'~w z ~~l~C£.w Q.. , .,J.( Cl-- ,..., ~-{'OrganiC (LP,T Subsystems only) ~""Mud(LP,T Subsystems only) :',',.'~and ---~-------------~~~-~-.-----~",""..~,.',Cobble/Gravel ---------.-~------~- VI ' Vegetated ------------------------~-{MUd'Ill -Sand lJ...Cobble/Gravel U', "4-'"U III V :JO'J 0-« o E VI 0c:,~o .~ u 0 c:"":::> ,;,L 0'~Bouldergt-~Bedrock -----------.---.---------.a:o O'J Anopheles Caenis Xanthium italicum Pbdostemum eaenls :>: lJJr- Vl>-en UJz a::w>;;:: lJJ:r: I- a:: 0 LL. >-:r:ua:: ;:i lJJ-:r: z ~ I-<Cu LL. enen <C ...J U lJJ:r: l- LL. 0 ~ CI <C Q .A <I).. :J !;Il LL. ... va. >-~ r-VI <I) E flO.<I)VI ~VI c:E E VI III f'O III V >-VI U c:l( ~VI VI ••lJJ VI .l>III .l>~~>-:J -:J Vl VI U Vl 11 ...<IIc:"O Ql c: t1lfllL- ~~UJ;:- ~Nonpersistent ------------..-----PontederJa cordata ..... .c:... Vfllfllm<I)m [Sand ---------t Cobble/Gravel >-<1) ~.'"V 0o.c:a:v> [Bou Jder ----I Bedrock ]~.[:~~~:~~------------------------SponglJla m Vegetated --------------------------i Organ Ic .:;:;Mud ~Sand Cobb Ie/Grave J Organic~8 --{MUd c:~Sand B ~Cobb 1,/G,,,,1c: ~ -{ Organic . Mud ----------_------..----------Pisidlum Sand --------_------------------Physa Cobble/Gravel ----------,..-------Garilnarus -0 <I)... :I (]I .... x UJ l- V>>- V> Wz a: l- V> ~u <C ...J UJz I-....o >-zua: ;2 w z zo ~u.... v> v> ~u wz I-....o ~ CJ<C o Chenopodium rubrum -------------------Spongilla[ 0 Bou I der ------t Bedrock --1 Floating ----------------------..Lemna minor .Floating-leaved ----------------Nuphar~egatum _.Submergent Moss ----------------Fissidens adlantoides Submergent Vascular ------------~maritima ' Submergent Algal ---------------~ --1 Floating -----------------------Spirodela polyrhiza Floating-leaved ----------------Nymphoides aquatica . Submergent Moss ~---------------Orepanocladusfluitans Submergent Vascular ------------Utricularla vulgaris Submergent Algal -----..---------Nitella v o 5 <II ...c:...8~c: ~ V ..."0 fll <I) :::J'm tT <C ~5v... 0'"a:0 a:l ..."0 fll.<I) :1m :I ...J ;2 o l- I- ...J u I- UJ Z X ...J UJz a: l-v> ~u <C ...J .... E Ql... <II>-v> E Ql... 1fI>- 1fI ..Q ~ v> '"'"fll U 1fI '"fll V ..Q :I v> <I) 0- >-~ I-1fI<I)<1)-va. ~~c:l( .-UJ8....... o -------.:.-..l on p:rsi 5 ten t -------------Pe ltand ra . v i r~I n I ca L e rs I s ten t ----------------Typha I at I fo 11 a ___·r Lichen -------'--------~-----Cladonia ~Moss ----------------------Sphagnum 1F.loat in.g..---.-.":"---.--.-,..---,..--salVin.ia.r.otu.ndif..O.liaFloating-leaved -----------Brasenia schreberi -Submergent Moss -----.:.-----Fiss idens jul ianus Submergent Vascular -'------:-Ceratophyllum demersum Submerqent Algal ----------Nitella "D"D (J)c.....,ru VI_ (J)....., I-(J) ~3 Ll :J I-"D ..c c Ul ru "---- Ll +J :J OJ 1-3u Ul +J . c"D OJ cCJ)ru 1-- (J)+JE(J) LU 3 c OJ..c -0u c 0-ru -l - "---+J VI OJ Vl3o;,:: LU Z-a:::~i-+JVlru ::>~ -l LL « £L I u-+J "DruOJ :JCO r:J« o E VI 0c.j..Jo+J U 0 CCO :::::> 12 -1 Dead . ....Need 1e •.1e.a.v...e...d E.ve..rg.r.e.en ---....Broad-leaved Evergreen ---- Need Ie-leaved Decidu·ous--- Broad-leaved Deciduous -i Dead Needle-leaved Evergreen ~-- -......•....Bro.ad.-l ea.ved E.V..e...rgre.en ----Needle-leaved De ci duous--- Broad-leaved Deciduous Vegetated ------------------i Organic Mud Sand Cobble/Gravel -{ ..~:~a~~~~-------_--------_-­ .•~~·b~l:/;;~~~~l-------------- Pice a ma ria na ;:;agnQlia virginiana Taxod iuni d ist i ch i um Acer rubrum Chamaecyparis thyoides Leucothoe axillaris Larix laricina Alnus rugosa Eleocharis aci~ularis Chironomus Gammanis ;,:: UJ ~ Vl>- Ul UJz a:. ~ Ul :::J -l« £L UJ:c ~ LLo >-:cua:.«a:. UJ :c zo ~«u LL Ul U')« -l u UJ:c ~ LLo ::E:«a:. (.:i« a E .:::t.0 U +Jo+Ja:::0 co -[Bou I de r Bedrock r- (J) l:- :JCJ) LL (J) Q. >-...-- ~VI (J) (J)~ VI U Q. VI c EErururu OJ VI -C X +J VI U .-LU Vl ru Ll E---->--:J 0 VI U Ul a ". 13 1.MARl NE Definition.--The Marine System (Figure 3)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.SaHnites exceed 30%0 (parts per thousand), with little or no dilution except opposite mouths of estuaries.Shallow coastal indentations or bays without appreciable fresh-water inflow,and coasts with exposed rocky islands that provide the mainland with 1 ittle 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 to:1)the landward limit of tidal inundation (extreme high water of spring"tides:EHWS)including the splash zone from break- ing waves;2)the seaward limit of wetland emergents,trees or shrubs where they extend into open ocean waters;or 3)the seaward limit of the Estuarine System where this limit is determined by factors other than vegetation.Deep-water habitats lying beyond the seaward limit of the Marine System are outside of the scope of this classification system. 14 Subsystems (1)Subtidal.This includes that part of the Marine System in which the substrate is continuously submerged. (2)Intertidal.This includes that part of the Marine System in which the substrate is exposed and flooded by tides.It also includes the associated splash zone. Classes.--Rock Bottom,Unconsolidated Bottom,Aquatic Bed,Reef, Flat,Rocky Shore and Beach/Bar. 2.ESTUARINE Definition.--The Estuarine System (Figure 4)consists of deep- water tidal habitats and adjacent tidal wetlands which are usually semi- enclosed by land,but have open,partially obstructed,or sporadic access to the open ocean and in which ocean water is at least occasionally diluted by fresh water runoff from the land.The salinity may be periodically increased above that of the open ocean by evaporation. Along some low energy coastlines there is appreciable dilution of sea water.Those offshore areas with typical estuarine plants and animals, such as mangroves (Rhizophora mangle)and oysters (Crassostrea virginica), are also included in the Estuarine System even though they are not semi- enclosed by land.1 IThe Coastal Zone Management Act of 1972 defines an estuary as, Iithat 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 fresh water derived from land drainage.11 The Act further states that,lithe term includes estuary-type areas of the Great Lakes.11 However, in this system we will not classify areas of the Great Lakes as estuarine. 15 Limits.--Estuaries extend upstream and landward to the place where ocean-derived salts measure less than 0.5%0 during the period of average annual low flow.The seaward limit of the Estuarine System is: 1)aline clos ing the mouth of a river,bay or sound;2)aline enclos- in~an offshore area of diluted sea-water with typical estuarine flora and fauna;or 3)the seaward 1 imit of wetland emergents,shrubs or trees where these plants grow seaward of the line closing the mouth of a river,bay,or sound. Description.--The Estuarine System includes both estuaries and lagoons.It is more strongly influenced by its association with land than the Marine System.In terms of wave action,estuaries are generally considered to be low energy systems. Estuarine water regimes and water chemistry are affected by one or more of the following forces:oceanic tides,precipitation,fresh- water runoff from land areas,evaporation and wind.Estuarine salinities range from hyperhaline to oligohaline (Table 1).The salinity may be variable (poikilohaline),as in the case of hyperhaline lagoons (e.g., Laguna Madre,Texas)and most brackish estuaries (e.g.,Chesapeake Bay, Virginia-Maryland);or it may be relatively stable (homoiohaline),as in the case of sheltered euhaline embayments (e.g.,Chincoteague Bay, Maryland)or brackish embayments with partially obstructed access or small tidal range (e.g.,Pamlico Sound,North Carolina).(For an extended discussion of estuaries and l~goons ~ee Lauff [1967J). 16 Subsystems (1)Subtidal.This includes that part of the Estuarine System in which the substrate is cOhtinuously submerged. (2)Intertidal.This includes that part of the Estuarine System in which the substrate is exposed and flooded by tides.It also includes the assoii~t~d spla~h zone. Classes.--Rock Bottom,Unconsolidated Bottom,Aquatic Bed,Reef, Flat,Streambed,Rocky Shore,Beach/Bar,Emergent Wetland,Scrub/Shrub Wetland and Forested Wetland. 3.RIVERINE Definition.--The Riverine System (Figure 5)includes all wetlands and deep-water habitats contained within a channel,except:1)wetlands dominated by trees,shrubs,persistent ernergents,nonaquatic mosses or lichens,aild 2)habitats with waters containing ocean-derived salts in excess of 0.5 %°'A channel is,"an open conduit either naturally or artificially created which periodically or continuously contains moving water~or which forms a connecting 1 ink between two bodies of standing water"(Langbein and Ised '1960:5). Limits.--The Riverine System is bounded on the landward side by upland~by the channel bank (including natural o~man-made levees),or by wetland dominated by trees,shrubs,persistent emergents,honaquatic mosses or lichens.In braided streams,the system is bounded by the banks forming the outer limits of the depression within which the braid- ing occurs. 17 The Riverine System terminates at the downstream end where the concentration of ocean-derived salts in the water exceeds 0.5%0 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, whether their flow is perennial or intermittent,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 (lotic) in the Riverine System.Upland islands or Palustrine wetlands may occur ln the channel but they are not included in the Riveri~e System. Palustrine 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 occ~rring on the river flood plain 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 state, liThe floodplain is a flat expanse of land bordering an old river. Often the floodplain takes the form of a very level plain occupied by the present stream channel,and it may never,or only occasionally,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.11 Subsystems.--The Riverine System is divided into four subsystems: the Tidal,the Lower Perennial,the Upper Perennial,and the 18 Intermittent.Each is defined in terms of water permanence,gradient, water velocity,streambed compositlon and the extend of flood plain development.The subsystems have characteristic water temperatures, flora,and fauna (see Reid 1961,lIlies and Botosaneau 1963,Hynes 1970). All four subsystems are not necessarily present in all rivers,and the order of occurrence may be other than that given below. (1)Tidal.In this subsystem,the gradient is low and water velocity fluctuates under tidal influence.The streambed is mainly mud with occasional patches of sand.Oxygen deficits may occur at times and the fauna is similar to that in the Lower Perennial Sub- system.The flood plain is typically well-developed and water temperatures approximate those of the Lower Perennial Subsystem. (2)Lower Perennial.This includes those channels that contain nontidal flowing water throughout the year.The flow is slow and the substrate consists mainly of sand and mud.Oxygen deficits may occur at times,the fauna is composed mostly of species that reach their maximum abundance in still water,and true planktonic organisms are common.The gradient is low compared to that of the Upper Perennial Subsystem and the flood plain is well-developed.Generally,the average of mean monthly water temperatures is more than 20°C,and in tropical latitudes-,the average of the monthly means during the summerlTlaV reach 2SoC (Illies and Botosaneau 1963). (3)Upper Perennial.This includes channels that contain flowing water throughout the year.The flow is fast and the substrate consists of rock,cobbles,or gravel with occasional patches of sand. 19 The natural dissolved oxygen concentration is normally near saturation; the fauna is characteristic of running water,and there are few or no planktonic forms.The gradient is high compared to the Lower Perr~nial Subsystem,and there is very little flood plain development. Generally,the average of mean monthly water temperatures is about 20 C (Illes and Botosaneau 1963). (4)Intermittent.This includes those channels that contain flowing water only part of the time.During those periods when the water is not flowing,it may remain in isolated pools or surface water may be absent. Classes.--Rock Bottom,Unconsolidated Bottom,Aquatic Bed, Flat,Streambed,Rocky Shore,Beach/BOar,and Emergent Wetland (non- pers i stent). 4.LACUSTRINE Definition.--The Lacustrine System (Figure 6)includes wetlands and deep-water habitats with all of the following characteristics: 1)situated in a topographic depression or a dammed river channel; 2)lacking trees,shrubs,persistent emergents,nonaquatic mosses or lichens with greater than 30 percent areal coverage;and 3)greater than 8 hectares (20 acres)in size.Similar wetlands and deep-water habitats smaller than 8 ha are also included in the Lacustrine System if an active wave-formed or bedrock shoreline feature forms all or part of the boundary,or if the water depth in the deepest part of the basin is greater than 2 m at low water.Lacustrine waters may be 20 tidal or nontidal,but ocean-derived salinity is always less than 0.5%0' Limits.--The Lacustrine System is bounded by upland or by wet- land dominated by trees,shrubs,persistent emergents,nonaquatic mosses or lichens.Lacustrine systems formed by damming a river channel are bounded by the contour approximating the normal spillway elevation or normal pool elevation except where Palustrine wetlands extend lakeward of that boundary.Where a river enters a Jake,the extension of the lacustrine shoreline forms the Riverine/Lacustrine boundary. Description.--The Lacustrine System includes permanently flooded lakes and reservoirs (e.g.,Lake Superior),intermittent lakes (e.g.,playa lakes)and tidal lakes with ocean-derived sal inities below b.S % o (e.g.,Lake Maurapas,louisiana).Typically,this system contains extensive areas of deep water and exhibits considerable wave action.Islands of Palustrine wetland may lie within the boundaries of the Lacustrine System. Subsystems (1)Limnetic.·This subsystem includes all dee~-w~ter habitats within the Lacustrine System.Many small Lacustrine Systems have no Limnetic Subsystem. (2)Littoral.This subsystem includes all wetland habitats that fall within the Lacustrine System.It extends'from the 21 shoreward boundary of the system to a depth of 2 m below low water or to the maximum extent of nonpersistent emergents if these grow beyond the 2 m depth. Classes.--Rock Bottom,Unconsolidated Bottom,Aquatic Bed, Flat,Rocky Shore,Beach/Bar,and Emergent Wetland (nonpersistent). 5.PALUSTRINE Definition.--The Palustrine System (Figure 7)includes all nontidal wetlands dominated by trees,shrubs,persistent emergents, nonaquatic mosses or lichens,and all such wetlands that occur in tidal areas where salinity due to ocean-derived salts is below 0.5%0'It also includes wetlands lacking such vegetation,but with all the following characteristics:1)siz"e less than 8 hectares;2)absence of an active wave-formed or bedrock shoreline feature;3)water depth in the deepest part of basin less than 2 m at low water;and 4) salinity due to ocean-derived salts less than 0.5%0' 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 extensive vegetated wetlands traditionally called by such names as marsh,swamp,bog,fen,and prairie which are found throughout the country.It also includes small,shallow permanent or intermittent water bodies,often called ponds.Palustrine wetlands may be situat~d 22 shoreward of lakes,river channels or estuaries;on river flood plains;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 in times of severe flood. The emergent vegetation adjacent to rivers and lakes is often referred to as lithe shore zone ll or the "zone of emergent vegetat ion l' (Reid and Wood 1976),and is generally considered a separate community from that of the river itself.As an example,Hynes (1970:85)says in reference to riverine habitats,"We wi 11 not here consider the long list cf 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.--No subsystems are recognized for the Palustrine System. C1asses.--Rock Bottom,Unconsolidated Bottom,Aquatic Bed, Flat,Moss/Lichen Wetland,Emergent Wetland,Scrub/Shrub Wetland and Fo res ted Wetland . 23 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 plant life form or physiography and composition of the_sub$~rate, features which can be recognized without the aid of detailed environ-. 1mentalmeasurements. Use of life forms at the class level has two major advantages: I)it does not require a high level of biological expertise to distin- guish between various life forms,and 2)it has been established that various 1 ife forms are easi ly recognizable on a great variety of remote sensing products (e.g.,R~dforth 1962,Anderson et al.1976).If plants cover more than 30 percent of the substrate,we distinguish classes ()~ the basis of the life form of the plants which constitute the uppermost layer of vegetation and possess an areal coverage greater than 30 p~rcent. For example,an area with 50 percent areal coverage of trees over a shrub layer with a 60 percent areal coverage would be classified as a Forested Wetland;an area with 20 percent areal coverage of trees over the same (60 percent)shrub layer would be classified a Scrub/Shrub Wet- land.Finer differences in life forms are recognized at the SUBCLASS level.For example,Forested Wetland is divided into Broad-leaved Deciduous,Needle-leaved Deciduous,Broad-leaved Evergreen,Needle-leaved lOur attempts to use familiar terms such as marsh,swamp,bog, and meadow at the class level were unsuccessful primari ly because of wide discrepancies in t~e use of these terms in various regi~ns of the United States.In an effort to resolve that difficulty,we decided to base the classes upon the fundamental componehts (1 ifeform,water regime,substrate type,water chemistry)which give rise to such terms. We bel ieve that this approach wi 11 greatly reduce the inisUilderstandirigs and confusion that result from the use of the common terms. 24 Evergreen,and Dead Subclasses.Subclasses are named on the basis of the predominant life form. If plants cover less than 30 percent of the substrate,the physiography and composition of the substrate are the principal characteristics used to di~tinguish classes.The nature of the substrate reflects regional and local variations in geology and the influence of wind,waves,and currents upon erosion and deposition of substrate materials.Rocky Shore~have been recognized a~a separate class,also based on suostrate,even though these habitats may support more than 30 percent cover of macrophytic al~ae.Similarly,we decided to characterize beaches and flats on the basis ofsLibstrate,although~in some cases,macrophytic algae or I'pioneer"vegetation may cover more than 30 percent of the substrate.Reefs are a unique class in which the subst rate i tse If is composed p rima r i I y'of 1 i"i ng and dead an i rna Is. "Most classes based on substrate have been divided into subclasses a\Ccon;Hng to the texture or composition of the substrate;for example, four subcl asses of unconso 1i dated bottoms are recogn i zed:Cobb Ie/Grave 1, Sand,Mudai1d Organic.In the special case of coral reefs,subclasses are designated on the basis of the type of or~anlsm that has formed the reef. The DOMINANCE TYPE forms the taxonomic category subordinate to subclass.Dominance types are determined on the basis of dominant plant species (e.g.,Jeglum et al.1974),dominant sedentary or sessile animal species (e.g.,Thorson 1957)or dominant plant and animal species (e.g., Stephenson and Stephenson 1972)".A dominant plant species has traditionally meant one that has control over the community (Weaver and 25 Clements 1938:91),and this plant is also usually the predominant species (Cain and Castro 1959:29).When the subclass is based on life form we name the dominance type for the dominant species or combination of species (codominants)in the same layer of vegetation used to deter- mine the subclass.1 For example,a Needle-leaved Evergreen Forested Wetland with 70 percent areal coverage of Picea mariana and 30 percent areal coverage of Larix laricina would be designated as a Picea mariana Dominance Type.When the relative abundance of codominant species is approximately equal,the Dominance Type consists of a combination of species names.For example,an Emergent Wetland with approximately~qual areal coverage of broad-leaved cattail (Typha latifol ia)and hardstem bu I rush (Sci rpus acutus)wou Id be des i gnated as Typha 1at i fo 1i a/Sci rpus acutus Dominance Type. When the subclass is based on substrate material,the Dominance Type is named for the predominant plant or sedentary or sessile macro- invertebrate species without regard for 1 ife form.In the Marlne and Estuarine Systems,sponges,alcyonarians,molluscs,crustaceans,worms, ascidians and echinoderms may all be part of the community represented by the Macoma Dominance Type.Sometimes it is necessary to designate two or more codomihant species as a Dominance Type.Thorson (1957)has recommended guidelines and suggested definitions for establishing community types.and dominants on level bottoms. Ipercent areal cover will seldom be measured in the application of this system,but the term must be related to a frame of reference. We suggest 2m 2 for herbaceous and moss layers,16m 2 for shrub layers and 100m 2 for tree layers (Meuller-Dombois and Ellenberg 1974:74).When per- cent areal cover is the key for establishing boundaries between units of the classification,it may be necessary to make cover measurements occasionally on plots in order to maintain uniformity of ocular estimates made in the field,or interpretations made from aerial photographs. 26 I.ROCK BOTTOM Definition.--In the Marine and Estuarine Systems the class Rock Bottom includes all deep-water (subtidal)habitats with rock substrates. In the Lacustrine,Palustrine and Riverine Systems,Rock Bottom includes all wetlands and deep-water habitats with rock substrates and permanently flooded,intermittently exposed,and semipermanently flooded W<:lter regimes.This class does not include those habitats classified as Aquatic Beds. Description.--The solid rock substrate of the rQcky benthi~or bottom lone 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-aerat~d waters. Temperature,salinity,current and light penetration are also important factors in determining the composition of the benthic community.Animals that live on the rocky surface are generally firmly attached by hooking or sucking devices although they may mOve about over the substrate in search of food.Some may be permanently attached by cement.A few <:lnimals hide in rocky crevices and under rocks,some ~ove rapidly enough to avoid being swept away,and others burrow into finer substrates between boulders.Plants are also firmly attached (e.g.,by holdfasts) and,in the Riverine System,they are commonly streaml ined or flattened in response to high water velocities. 27 Subclasses andDominan~e Types.--Rock Bottom has been divided into two subclasses,Bedrock and Boulder.The Dominance Types for both subclasses are similar. (I)Bedrock.These bottoms consist of stable bedrock surfaces.Grooves and crevices,when present,provide shelter and microhabitats. (2)Boulder.These bottoms consist predominantly of rela- tivelystable,rock fragments larger than 256 mm (10 in)in diameter (Wentworth 1922).Often,finer material is mixed with these boulders. Examples of Dominance Types for the Marine and Estuarine Systems are Hippospongia encr~sting sponges and Cnemidocarpa~Strongylocentrotus, Pisaster,Muricea,and Laminaria.Examples of Lacustrine and Riverine Dominance Types are Spongilla,L¥l1lnaea,Caenis,ChironQmidae,and Hydrosyche. 2.UNCONSOLIDATED BOTTOM Definition.--In the Marlneand Estuarine Systems,Unconsolidated Bottom includes all deep-water (subtidal)habitats with unconsolidated substrates.In Lacustrine,Palu~trine andR1verine Systems,the class includes all unconsolidated substrates with permanently flooded,inter- mittently exposed and semi permanently flooded water regimes.This class does not include habitats classified as Aquatic Beds. Description.--Unconsolidated Bottoms are characterized by the lack of large stable surfaces for plant and animal attachment.They are usually found in lower energy areas than Rock Bottoms,and may be very I ., 28 unstable.Exposure to wave and current action,temperature,sa 1 in i ty and 1 ight penetration .determine the composi.tion and distribution of organisms. Most macroalgae attach to the substrate by means of basal hold- fast cells or discs;however~in sand and mud,algae penetrate the substrate and higher plants can successfully root if wave action and currents.are not too strong.The majority of animals in unconsolidated sed·iments 1 ive wi thin the substrate,e.g.,Macoma and Mellita.Some, such a~Chaetopterus,maintain permanent burrows,and others may live on the surface,especially in coarse-grained sediments. In the Marine and Estuarine Systems,Unconsolidated Bottom com- i munities 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 upon sal inity.Thorson (1957)has summarized and described characteristic types of level bottom communities in detail. In the Riverine System,the substrate type is,to a great extent, determined by current velocity,and plarit~alid animals exhibit a high degree of morphologic and behavioral adaptation to flowing water.Some species are confined to specific substrates and others are at least more abundant in one type of substrate thanth-ey are in others ..AccO ....dirigto Hynes (1970:208),liThe larger the stones,and hence the more complex the substratum,the more diverse is the invertebrate fauna.1I In Lacustrine and Palustrine Systems,there is usually a high correlation,within a given watl body,between the nature of the substrate and the number of species and individuals.For example,in the profundal bottom of "29 eutrophic lakes where 1i ght ·is absent,oxygen contenti s low and carbon dioxide concentration is high,the sediments are ooze-like organic materials and species diversity is low."Each substrate type typically supports a relatively distinct community of organisms (Reid 1961:307). Subclasses and Dominance Types.--The class Unconsol idated Bottom has been divided into four subclasses:Cobble/Gravel,Sand,Mud,and Organi~.Differences in grain size and interstitial spa~e in unconsoli- d<:lted substrates greatly affect the species composition of the benthic flora and fauna. (1)Cobble/Gravel.The substrate is predomina~tly cobble and gravel although finer sediments may be intermixed.An example of a Dominance Type fbr theMa~ine System is M6diolus and fot the Estuarine System,Dendraster.Examples for the Lacustrine,Palustrine and Riverine Systems are Diamesa~Nemoura/Eukiefferiella (Slack et al.1977). Chironomus/Hydrosyche/Physa(Krecker and Lancaster 1933),Limnea,Baetis, Spongilla,Lumbriculus,and Gammarus. (2)Sand.The substrate is predominantly sand,although finer or coarser sediments may be intermixed.The Sand Bottom has a more limited fauna and flora th~n either Mud or Cobble/Gravel Bottom. Examples of Dominance Types in the Marine System are Pecten,Tellina, Penaeus,and Spatangus and for the Estuarine System,Tellina,Ar~nicola, Dendraster,and Renilla.Examples for the Lacustrine,Palustrine and Riverine Systems are Physa,Gammarus,Chironomidae,Limnodrilus,and Ephemera. 30 (3)Mud.The substrate is predominantly silt and clay although coarser sediments or organic material may be intermixed. Organisms 1 iving in mud must often be able to adapt to rather low oxygen concentrations.Exa~ples of Dominance Types for the Marine and Estuarine Systems include Amphiura,Macoma,Echinocardium,and Urechis. Examples of Dominance Types for the Lacustrine,Palustrine and Riverine Systems are'Tubifex~Anodonta,Pisiduim,Chaoborus,~ndC~ironomus. (4)Organic.The substrate is predominantly composed of organic material.These habitats have a limited number of species and are very low in fa.una 1 product iv I ty (We 1ch 1952). 3.AQUATIC BED Defiriition.--The cl~ss Aquatic Bed represents wetlands and deep- water habitats that the major i tyof the time are dominated by submergent plants,floating-leaved plants or floating plants for the majority of the growing season in most years.Water regimes are restricted to sub- tidal,i rregu 1ar 1y exposed,permanent ly flooded,i nterm i ttent 1y exposed, and semi permanently flboded. Description.--Aquatic Beds represent a diverse group of plant communities that require surface water for optimu~growth'and repro- duction.They are best developed in relatively permanent water. Subclasses and Dominance Types (1)Submergent Algal.These habitats occur in both tidal and nontidal locations,but they are far more diverse and widespread in the Marine and Estuarine Systems.In these coastal areas,algal beds 31 oGcuPY rock substrates and unconsol idated substeates characterized by a wide range of sediment depths and textures.They may extend to ~ater depths of 30m (98 ft).Coastal algal beds are most luxuriant along the rocky shores of the northeast and the west.Macrocysti s beds are especially well-developed on the Pacific Coast.Along both coasts, Fucus and Laminaria may dominate dense SubrTlergent Algal Beds.In ~ropical regions,this subclass is characterized by green algae,includ~ in~forms containing calcareous particles;Halimeda and Penicillus are common examples.Caulerpa and Laurencia also may form large Submergent Algal Beds.Other plants,such as Enteromorpha and Ulva,are tolerant of fresh water and flourish in some estuaries. Inland SObmergent Algal Beds are represented by plants such as the Chara and Nitella which look much 1 ike vascular plants and may grow in similar situations.However,Chara meadows may be found in Lacustrine waters as deep as 40 m (131 ft)(Zhadin and Gerd 1963),where hydrostatic pressur~limits the survival of vascular submergents (Welch 1952). (2)Submergent Vascular.In the Marine and Estuarine Systems this subclass has been referred to by others as temperate grass flats (Phillips 1974);tropical marine meadows (Odum 1974);eelgrass beds, tu rt legrassbeds and seagrass beds (Aki ns and Jefferson 1973,EI euter ius 1973,Phillips 1974).Submergent Vascular Beds extend to depths greater Lhan 10 m (33ft)In clear marine waters.The greatest numbers of plant species occur in shallow,clear,tropical or subtropical waters of moderate current strength in the Caribbean and along the Florida and Gulf Coasts.Principal Dominance Types in these areas include Thalassia testudlnum~Halodule beaudettei,Syrin~odJumfiliformis,R~p~ia maritima, 32 ~aJophila and Vall isneria americana. Five major species dominate the Submergent Vascular Beds along the temperate coasts of North America:Halodule beaudettei,Phyllospadix scouleri,~.torreyi,Ruppia maritima and Zostera marina.Zostera beds have the most extensive distribution,but they are limited primarily to the more sheltered estuarine environment.In the lower sal inity zones of estuaries,stands of Ruppia,Potamogeton and Vallisneria often occur, along with Najas and Submergent Vascular Beds in the Riverine,Lacustrine and Palustrine Systems occur at all depths within the photic zone.Typical inland genera include Potamogeton,Ceratophyllum,Myriophyllum,Najas, Ruppia,Utricularia and Vallisneria. (3)Submergent Moss.These Aquatic Beds are far less abundant than Algal or Vascular Beds.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,Drepanocladus and Fontinalis.The latter may grow to depths as great as 120 m (392 ft)(Hutchinson 1975). For simpl icity,aquatic liverworts of the genus Marsupella are included inth1s subclass. (4)Floating-leaved.These Aquatic Beds are characterized by floating-leaved plants.They are found in all systems except the Marine.These beds typically occur in sheltered areas where there is little water movement (Wetzel 1975).Typical dominants include Nymphaea, Nuphar,Potamogeton natans and Brasenia schreberi.Plants such as 33 Nuphar advena andPolygorium amphibium,which may stand er~ctabove the water surface or substrate.,may be considered emergentsorfloating-Ieaved plants,depending upon·the life form adopted at a particular site. (5)Floating.Thi~subclass is chsracterized by ~~nera which float freely on the water surface,such as:Lemna,Spirodela, Pistia,Eichhornia,Trapa,Salvinia and Azolla.These plants are found primarily in protected portions of slow-flowing rivers and in the Lacustrine and Palustrine Systems."Floating Beds Sre dynamic habitats;they are easily moved about by wind or water currents.They COver a large area of water in some parts of the country,particularly the southeast. 4.REEF Definition.--The class Reef"includes ridge-or mound-like structures formed by the colonization and growth of sedentary invertebrates. Description.--Reefs are characterized by their elevation above the surrounding substrate and their interference with norm~l wave flow; they are primarily subtidal,but parts of some Reefs ~ay be intertidal as well.Although corals,oysters and tubeworms are the most visible organfs~s arid are mainly resporisible for Reef formation,other molluscs, foraminifera,corral I ine algae and other forms of life also contribute substantially to Reef growth.Frequently,Reefs contain an abundance of dead skeletal material and shell fragments,in comparison to the amount of living matter. Subcla$ses andDo~1nance Types (I)Coral.·Coral Reefs are widely distributed in shallow waters of warm sea.s.They are found in Hawaii,Puerto Rico,the Virgin Islands,and southern Florida.They ar~characterlzed 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 Marine Subtidal Subsystem;although the upper part of some reefs is sometimes exposed.Examples of Dominance Types are Porites,Acropora and Montipora;the distribution of these types primarily reflects elevation,wave exposure,and the age of the Reef. (2)Mollusc.This subclass occurs in both the Estuarin~ Intertidal and Subtidal Subsystems.These Reefs are found on the Pacific,Atlantic,and Gulf Coastsand.in Hawaii and the Carribbean. Mollusc Reefs may become extens ive ,affo·rd i ng.a substrate for sedentary and boring organisms.arid a shelter for many others.Reef molluscs are adapted to great variations in water level,salinity and temperature, and these same factors control their distrib~tion.~xamples of Dominance Types fbr this subclass are the oysters (Ostrea,trassostrea). (3)Worm.Worm·Reefs are constructed by large c610nies of sabellari id worms living in individual tubes constructed from cemented. sand 9rains.Although they do not support as diverse a biota as do Coral and Mollusc Reefs,they provide a distinct habitat which may cover large areas.Worm Reefs are generally confined to tropical waters, and are most cpmmon along the coasts of Florida,Puerto Rico,and the Virgin Islands.They occur in both the Marine and Estuarine Systems 35 where the salinity approximates that .of sea water.The Dominance Type· for this subclass isSabellarta. 5.FLATS Definition.--The class Flat refers to level landforms composed of unconsol idated sediments.Normally,Flats occur only in areaS sheltered from strong currents "and wave action.They may be irregularly shaped or elongate and continuous with the shore,whereas Bars generally are elongate,parallel to the shorel ine,and separated from the shore by water.Water regimes are restricted to irregularly ~xposed,regularly flooded,irregularly flooded,seasonally flooded,tempor-arily flooded and intermittently flooded • .Description •...;-Estuarineand Marine Flats occur in the intertidal zone.The distrib~tion of fauna is dependent on substrate texture, current and wave action,and salinity;temperature and salLnity may be extremely variable.Regularly flooded Flats support diverse populations of tube-dwell ing and burrowing invertebrates including worms,clams and crustacearis (Gray 1974).These invertebrates are mostly detritus feeders.Irregularly flooded Flats have been called salt flats,pans or pannes.They are typ i ca 11y highi n sal i h"ity and are usually surrounded by,or lie on the landward side of,Emergent Wetland (Martin et al.1953, , Type 15).Flats are also commonly colonized by algae and diatoms and there may be an algal crust or mat. The distribution of organisms in Riverine and Lacustrine Flats is .dependent upon substrate material,currelit and wave action,and the 36 frequency of inundation.Lacustrine Flats may include the entire basin of a lake.Palustrine Flats are generally the result of high salinity, removal of vegetation by man,animals,or fire,or the discharge of thermal waters or pollutants.In manOy arid areas,Palustrine and LacuStrine Flats are crusted or saturat~d with s~lt.Martin et al. (1953)called these habitats iniand saline flats (Type 9);they are also called alkali flats,salt flats,and salt pans.°Faunal diversity and abundance caries with salinity,duration of inundation and temperature. Subclasses and Dominance Types (1)Cobble/Gravel.The Flats are-composed predominantly of ° cobbles or gravel,often with shell fragments or finer sediments inter- mixed.Unlike Rocky Shores,Cobble/Gr~vel Flats are n6t ~table and communities aroe more transitory.Examples of Dominance Types in the Mar i ne and Estuari ne Systems are:Sa lanus,Patella ,Li nor i na,Thai s, and Myt il us • (2)Sand.Sand Flats are composed predominantly ~f ~and, °often with particles of other sizes intermixed.Although population density may be very high,species diversity is usually comparatively low. In the Marine and Estuarine SyStems,some examples of Dominance Types are ~,Macoma,Tellina,Arenicola,Uca,Leptosynapta,and Paractis. (3)Mud.Mud Fl ats are composed predomi nant 1y of s i It and clay,and tend to be anaerobic below the surface.They usually have a higher organic content than Cobble/Gravel and Sand Flats.In the Marine and Estuarine Sy~tems some examples of Dominance Types are:Uca, Callianassa,Nassari~s~Macoma,N~reis,Amphitrite,Cerianthiopsis and Thyone. .. 37 (4)Organic.These Flats consist of exposed organfc soils of former.y vegetated wetlands;In the Estuarine System,Organic Flats are often dominated by rriicroinvertebrates such as foraminifera or smaller snails (Cerit~ium). (5)Vegetated Flats.Some Flats are exposed for a sufficient period to be colonized by herbaceous annual~or seedling herbaceous perennials (pioneer plants).When these plants cover more than 30 percent of the substrate,the area is classified as a Vegetated Flat.This vegetation is usually ki lIed by rising water levels and may be removed before the begfnning of the next growing season.Examples of Domfnance Types are Xanthium italicum,Cheno~od~um rubrum,Ec~inochlo~ crusgalli,and Eleocharis acicularis. 6.STREAMBED Definition.--The class Streambed is restricted to the Riverine. and Estuarine Systems.I·t includes all p~rts of channels that are not included in any of the oth~r classes.Streambed may have the classes Beach/Bar and Flat included within it,but in the Intermittent Subsystem of the Riverine System the entire channel frequently contains only the c I ass S tr'eamb~d. Description.--Streambedsvary greatly in substrate and form depending on the gradient of the channel and the velocity of the water. In the Rfveririe Sys~em,material on the bed is continually being moved downstream;in Estuarine streambeds,material may be moved upstream or downstream according to the direction of tidal flow.Frequently Bars occur on the convex side of single channels or they may be included as 38 islands within the bed of braided streams (Crickmay 1974}.Flats and Beaches are particularly common adjacent to Streambed,particularly in the Lower Perennial and Tidal Subsystems of larger rivers and in estuarine streams where wave action is especially strong.In estuarine areas, Streambed is the proper class for the entire channel of tidal creeks that are dewatered at low tide.In most cases,Streambeds are not vegetated because of the scouring effect of the moving water,but,I ike Flats,they may be colonized by "p ioneering"annuals during periods of low flow or they may have perennial emergents and shrubs that are too scattered to classify as Emergent Wetland or Scrub/Shrub Wetland. 39 13)Mud.This subclass is characteristic of the Lower Perennial and Tidal Subsystems of the Riverine.Mud Streambeds are frequently associated~ith l~rge Mud Flats~ (4)Organic.This is not a common sub~lass in the Riverine System but it occurs along the edge of streams flowing over deep peat deposits,usually in the Lower Perennial Subsystem.Organic Streambeds are common in creeks draining Estuarine Einergent Wetlands with orga"nic soi Is. 7.ROCKY SHORE Definition.--The class Rocky Shore includes wetland environments characterized by stable bedrock surfaces or relatively stable,large rock fragments.Water regimes ate ~e~tticted to irregularly exposed, regul ar Iy flooded,i rregu 1ar 1y flooded,seasona I ly flooded,temporar i ly flooded and intermittently flooded. Description.--I~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 which is a function of tidal range, wave action and degree of exposure to the sun.In the Lacustrine ahd Riverine Systems,Rocky Shores support sparse plant and animal communities. SUbclasses and Dominance Types.--The class Rocky Shore is divided into two subclasses,Bedrock and Boulder.The Dominance Types are 40 similar for both subclasses. (1)Bedrock.These wetlands consist of stable bedrock surfaces .. (2)Boulder.These wetlands consist of relatively stable rock fragments larger than 256 mm in diameter. Communities or zones of Marin~ana Estuarine Rocky Shores have been studied in detail (Lewis 1964,Ricketts and Calvin 1968,Stephenson and Stephenson 1972).Each zone supports a rich assemblage of invertebrates and algae.Dominance Types of the Rocky Shore often can be characterized by one or two dominant genera from these zones. The uppermost zone (termed the Littorine/Lichen Zone)is dominated by periwinkles (Littorina 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 semi-marine genera such as Lygia. The next lower zone (the BalanoidZone)is commonly dominated by molluscs,green algae and barnacles of the bi:l1anoid group.From a distance,the zone appears white~Dominance Types such as BalanUS, Chthamalus and Tetrac1ita may form an almost pure sheet of barnacles,or these animals may be interspersed with molluscs,tubeworms and algae such as Pelvetia. The transition between the littorine/lichen and balanoid zones is frequently marked by the replacement of the periwinkles with both true and false 1 impets such as Acmaea and Siphonaria.The limpet band approximates the upper limit of the regularly flooded intertidal zone. 41 In lhc middle and lower intertidal areas,which are flooded and exposed by tides at least once daily,lie a number of other communities which can be characterized by dominant genera.Mussels (Mytilus)and gooseneck barnacles (Mitella)form communities exposed to strong wave action.The Fucus and Laminaria Dominance Types liesl ightly lower, just above the coralline algae (Lithothamnion)Dom.inance Type.The Laminaria Domin~nce Type approximates the lower end of the Intertidal Subsystem;it is generally exposed at least once daily.The Lithothamnion' Dominance Type forms the transition to the Subtidal Subsystem and is exposed only i~regularly. We have not identifled DomlnanceTypes foithe Lacustrine and Riverine Systems. 8.BEACH/BAR Definition.--The class Beach/Bar consists of sloping landforms generated by waves and currents and composed predomi nant lyof unconso 1 i-. dated sand,gravel or cobbles.'They have less than 30 percent vegetative cover.Beaches are generally continuous with the shore,extending landward to a distinct break in landform ~r substrate type (e.g.,a foredune,cl iff or bank)or to the point where vegetation covers 30 per- cent or more of the substrate.Bars are elongate ridges,banks or mounds which are bordered by water on at least two sides.Water regimes are restricted to irregularly exposed;regularly flooded,irregularly fiooded, seasonally flooded,temporarily flooded and intermittently flooded. Description.--Beaches and Bars are characterized by a shifting, unstable substrate with high permeability~variable surface moisture, 42 and relatively low organic niatter content.The surface layer has a high oxygen content and there is a deeper anaerobic layer (Hedgpeth 1957, Ranwell 1972).They may be sparsely vegetated and populated by a diversity of specialized burrowing invertebrates such as molluscs, crustaceans and polychaetes.Faunal distribution is controlled by waves, currents,interstitial moisture,sal inity and sediment grain size.In Marine and Estuarine Beaches and Bars the fauna is usually more diverse. than in Lacustrine Of Riverine Beaches and Bars (Hedgpeth 1957,Riedl and McMahan 1974). Subclasses and Dominance Types (I)Cobbl~/Gravel.Cobble/Gravel Beaches and Bars typically form where wave action is especially strong so that sand .and silt particles are largely eroded and .transported from the Beach or Bar and ~eposited in deeper waters.While cobbles and gravel predominate, sand is usually mixed with these larger particles.Some of the larger cobbles and occasional boulders found on these Beaches may support sedentary organisms such as Balanus. (2)Sand.Sand Beaches and Bars are composed predominantly of calcareous or terrigenous sand.Examples of Dominance Types in the Marine and Estuarine Systems are Donax,Mya,Tivela,Oliva,Thoracophelia, Haustorius,Orchestia,Chiredotea,EmeritajOcypode (Hedgpeth 1957,Riedl and McMahan 1974).Examples of Dominance Types in the Riverine, Lacustrine,and PalOstrine Systems are Parastehocaris,Phyllognathus,and Pristina (Neel 1948). 43 9.MOSS/LICHEN WETLAND Definition.--The Moss/Lichen ·Wetland class includes areas where mosses or I ichens cover the substrate and where other plants such as emergents,shrubs or treestomprise less than·30 percent of the areal. cover. Description~-~Mosses and lichens are important components of the· flora in many wetlands,espetially 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 a re uncommon and mosses or lichens dominate the flora.Such Moss/Lichen wetlands are not common, even in the northern United States where they occur ~ost frequently. Subclasses abd Dominance Types (I)Moss.These wetlands are most abundant in the far north.Areas.covered wi th Sphagnum spp.are usual 1y ca lIed bogs (Go let and Larson 1974,Jeglum et al.1974,Zoltai et al.1975),whether Sphagnum or higher plants are dominant.In Alaska,mosses such as Drepanocladus and the liverwort Chiloscyphus fragilis may dominate shallow pools with impermanent water;Sphagnum,Campyl ium stellatum,Desmatodon heimi i,Aulacomnium palustre and Oncophorus wahlenbergii are typical of wet soil in this region (Britton 1957,Drury 1962). (2)Lichen.These wetlands are also a northern subclass. Cladonia forms the most important Dominance Type.Pollett and Bridgewater (1973)described areas with mosses and lichens as bogs or fens,the distinction being based on the availabhity of nutrients and the 44 panicularp1ant species present.Sj8rs (1959)and Jeg1um et a1.(1974) mentioned the presence of Lichen Wetlands in the Hudson Bay Lowlands and in Ontario,respectively. 10.EMERGENT WETLAND Definition.--The Emergent Wetland class is characterized 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. 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 cl imatic fluctuations cause Emergent Wetlands to revert to an open water phase in some years (Stewart and Kantrud 1972).They are found throughout the United States and occur in all systems except the Marine.Emergent Wetlands are known by many names including marsh,meadow,fen,prairie pot hote,and slough.Areas that are dominated by pioneer plants that become estab1 ished during periods of low water are not Emergent Wetlands ~nd should be classified as Vegetated Flats. Subclasses and Dominance Types (1)Persistent.Wetlands in this subclass 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 Palustrine Systems. 45 Persistent Emergent Wetlands dominated bySpartina alterniflora J S.patens,.?:cynosuroides J Juncus roemerianusJTypha angustifolia,and Zizaniopsis mili.:kea are major components of the Estuarine Systems of the Atlanti~and Gulf Coasts of the United States.On the Pacific Coast, Sal icornia pa~ifica,Suaeda cal ifornicaJ Triglochin maritima and Spartina foliosa are common dominants. Palustrine Persistent Emergent Wetlands contain a vast array of grass-like plants such as Typha spp.,Scirpusspp.,Cladium jamaicens Carex spp.,and true grasses such as Phragmites communis,Glyceria spp., Beckmania syzigachne and Scolochloa festucacea.There is also a variety of broad-leaved persistent emergentssuch as Lythrum salicaria,Rumex mexicanus,Decodonvertfcillatus,and many species of Polygonum. (2)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 J at certain seasons of the year,there is no obvious trace of emergent vegetation.For example,Zizania aquatica in the north central states does not become apparent until mid-summer and fail when it forms dense emergent stands. Nonpersistent emergents also include species such as Peltandra virginica, Pontederia cordata and Sagittaria spp.Movement of ice in Riverine and Lacustrine Systems often removes all traces of emergent vegetation during the winter.Where this occurs,the area should be classified as Non- persistent EmeigentWetland. 46 11.SCRUB/SHRUB WETLAND befinition.--The class Scrub/Shrub Wetland includes areas domi- nated by woody vegetation less than 6 mm (20 ft)in height.The species include true shrubs,young trees,and trees or shrubs that are small or stunted betauseof environmental conditions. Descripti6n.--Scr~b/$hrubWetlands 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 widesp"read classes in the country (Shaw and Fredine 1956).Scrub/Shrub Wetlands are known by many names such as shrub swamp (Shaw and Fredine 1956),shrub carr (Curtis 1959),bog (Heinselman 1970),and pocosin (Kologiski 1977).For practical reasons we have also included forests composedbf young trees lessthah 6 m tall in this class. Subclasses and Dominance Types (1)Broad-leaved Declduous.These are wetlands where deciduous trees or shrubs less than 6 m high represent more than 50 per- cent of the total areal cover.In the Estuarine System they are dominated by such plants as Baccharis halmifolia,and Iva frutescens. Alnus spp.,Salix spp~,Cephal~nthus occidental is,Zenobia pulverulenta, BcLulapulilila and young trees such as Acerrubrum are typical Dominance Types in the Palustrine System. (2)Needle-leaved Deciduous.This subclass is found only in the Palustrine System where it is represented by young or stunted trees 47 such as Larix laricina or Taxbdium distichium. (3).Broad-leaved Evergreen.These wetlands are found in both the Estuarine and Palustrine Systems.In the Estuarine System,vast acreages are dominated by mangroves (R~izophora mangle,~anguncularia racemose,Conocarpus erecta,Avicennia germinans)~h~t are less than 6 m in height.In the Palustrine System,the broad-leaved evergreen species are typically found on organic soils.In the north,typical representa- ·tives are Ledum groenlandicum,Andromeda glaucophylla,Kalmia polifolia, ~nd the semi-evergreen Chamaedaphnecalyculata.In the south,Lyon1a lucida and Leucothoe axillaris are characteristic broad-leaved evergteen species. (4)Needle-leaved Evergreen.These wetlands are found only in the PalUstrine System.The dominant species are young or stunted trees such as Pice~mariana or Pinus setotina. (5)Dead.These wetlands ~redominated by dead woody vegetation less than 6 m in height.They are usually produced by a prolonged rise in the water table,which often results from the activities of man or beaveis,but they may result from other natural causes such as fire,salt spray which often accompanies severe coastal storms,and insect infestations;and from air pollution or man's use of herbicides. 12.FOR~ST~D WETLAND Definition.--The class Forested Wetland is characterized by woody vegetation that is 6 m or more in height. Descriptibn.--Forested Wetlands are most common in the eastern United States and in those sections of the west where moisture is ----------~ 48 relatively abundant,particularly along rivers and in the mountains. They occur only in the Palustrine and Estuarine Systems.Palustrine Forested Wetlands normally possess an overstory of trees,an understory of young trees or shrubs and an herbaceous layer.Forested Wetlands in the Estuarine System are restricted to the mangrove forests of Florida, Puerto Rico and the Virgin Islands. Subclasses and Dominance Types (1)Broad-leaved Deciduous.These wetlands are found throughout the country,but reach their greatest abundance in the south and east.Dominant trees typical of this subclass include:Acer rubrum, Ulmus americana,Fraxinus pennsylvanica,~.nigra,Nyssa sylvatica,~. aquatica,Quercus bicolor,..9:..lyrata,and Q.michauxii.Wetlands in this subclass generally occur on mineral soils or highly decomposed organic soils. (2)Needle-leaved Deciduous.These wetlands are represented by a limited group of species.Larix laricina is characteristic of the Boreal Forest Region where it occurs as a dominant on organic soils.The southern representatives of this subclass include Taxodium distichum and T.ascendens which are noted for their abil ity to tolerate long periods of surface inundation. (3)Broad-leaved Evergreen.These wetlands reach their greatest development in the southeast where Persea borbonia,Gordonia lasianthus and Magnolia virginiana are prevalent,especially on organic soils.This subclass also includes Rhizophora mangle,Avicennia nitida and Laguncularia racemosa which are adapted to varying levels of salinity. 49 (4)Needle~leaved Evergreen.These wetlands are widespread in the north where Picea mariana,growing on organic soils,represents a major dominant.Whereas~.mariana is common on nutrient-poor soils, Thuja occidentalis dominates northern wetlands on more nutrient-rich sites.Along the Atlantic Coast,Chamaecyparis thyoides is one of the most common dominants on organic soils.Pinus serotina is a common needle-leaved evergreen found in the southeast in association with dense stands of broad-leaved evergreen and deciduous shrubs. (5)Dead.These wetlands are dominated by dead woody vegetation greater than 6 m in height.Like Dead Scrub/Shrub Wetlands, they are most common In,or around the edges of,man-made impoundments and in beaver ponds.The same factors that produce Dead Scrub/Shrub Wetlands also produce Dead Forested Wetlands. MODIFIERS In order to fully describe wetlands and deep-water habitat~, certain modifiers must be appl ied 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.Modifiers for water regime,water chemistry,soil,and special modifiers for disturbed wetlands are defined in this section. Waie~Regime Modifiers Precise description of hydrologic parameters requires detailed knowledge of the duration and timing of surface inundation on both a yearly and long-term basis,as well as an understanding of ground-water 50 fluctuations.Because such information is seldom available,the water regimes that,in part,determine characteristic wetland and deep-water plant and animal communities are described here in only general terms. Water regimes are defined under two major headings,Tidal and Nontidal. ~iheseterms are not intended as modifiers. Tidal water regime modifiers should be used for wetlands and deep-water habitats in the Estuarine and Marine Systems and nontidal modifiers should be used for all nontidal parts of the Palustrine, Lacustrine and Riverine Systems.The Tidal Subsystem of the Riverine System and tidally-influenced parts of the Palustrine and Lacustrine Ecological Systems require careful selection of water regime modifiers. Subtidal and irregularly exposed wetlands and deep-water habitats.in the Palustrine,Riverine,and Lacustrine Systems should be called permanently flooded-tidal rather than subtidal.Palustrine,Riverine, an9 Lacustrine wetlands regularly flooded by the tide should be \ designated regularly flooded.Palustrine,Riverine and Lacustrine wet- lands which are only irregularly flooded by tides should be designated by the appropriate nontidal water regime modifier with the word tidal added,as in seasonally flooded-tidal. 1.TI DAL: 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~ .. ~'. -----~~~------~~---~-~-----------~ 51 Regularly Flooded.--Tidal water alternately floods and exposes the land surface at least once daily. Irregularly Flooded.--Tidal water floods the land surface less often than daily. The periodicity and amplitude of tides vary in different parts of the United States,mainly because of differences in latitude and geomorphology.On the Atlantic Coast,two approximately 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).The usual pattern on the Pacific Coast is two unequal high tides and two unequal low tides (mlxed semidiur~al). Individual tides range in height from approximately 9.5 m (31 ft) at St.John,New Brunswick (U.S.National Oceanic and Atmospheric Administration 1973)to less than 1 m (3.3 ft)along the Louisiana coast (Chabreck 1972).Tides of only 10 cm (25 in)are not uncommon in Louisiana.Therefore,while there can be no hard and fast rules,the division between regularly flooded and irregularly flooded water regimes would probably occur approximately at:mean high water on the Atlantic Coast,lowest higher high tide on the Pacific Coast,and just-above mean tide level of the Gulf Coast.The width of the intertidal zone is determined by the tidal range,the slope of the shoreline,and the degree of exposure of the site to wind and wave. 2.NONT I DAL These water regimes are not influenced by oceanic tides,although they may be affected by wind or seiches in lakes.Water regimes are -------------------------------------------- 52 -------------------------------------------------- defined in terms of the growing season which we equate to t'he frost-free period (see the U.S.Department of Interior National Atlas 1970:11 for generalized regional delineation).The remainder 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 at all times of 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. Semi permanently 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 except during severe drought. Seasonally Flooded.--Surface water is present for extended periods 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 usually 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 53 and wetlands are characteristic of the temporarily flooded regime. f~ter~itteritly 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 communities under this regime may change as soil·moisture 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 under the direct and purposeful control of man;it does not depend just on normal variatiori in precipitation or riverflow.The vegetation growing in these areas cannot be considered a reliable predictor of water regimes. Agricultural l~nds managed under a rice-soybean rotation and wildlife .management areas where crops or forests may be flooded or dewatered to attract wildlife are typical of this regime. Water Chemistry Modifiers The accurate characterization of water chemistry in wetlands and deep-water habitats is a very difficult task,both because of problems in meastirement and because values tend to vary wtth 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 dramatic influence on the types of plants or animals that inhabit an area.We feel that a description of water chemistry must be an essential part of this classification system. The two key parameters employed in this system are sal inity and hydrogen ion concentration (pH).All habitats are classified according to salinity,and fresh-water habitats are further subdivided by pH levels. I.SALINITY MODIFIERS Differences in sal inity 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 the inland salinity spectrum (Moyle 1946,Bayly 1967,Stewart and Kantrud 1971).Since the gradation between fresh and hypersaline or hyperhaline waters is continuous,any boundary will be artificial,and few classification systems agree completely.In inland environments,salinity is usually expressed in specific conductance, milligrams per liter (mg/l),milliequivalents per liter (meq/l),percent salt or total dissolved solids. Estuarine and marine waters are a complex solution of salts;these are dominated by sodium chloride (NaCl).The term haline is used to indicate the domihance of ocean salt.The relative proportions of the various major ions are usually similar to those found in sea water,even if the water is diluted below sea strengtho 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 IISymposium on the Classification of Brackish Waters"in 1958,for use in the Marine and 55 Estuarine Systems (Table I).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 waters is dominated by four.major cations: calcium (Ca),magriesium (Mg),sodium (Na),and potassium (K),and the major anions:carbonate (C0 3),sulfate (S04)and chloride (Cl)(Wetzel 1975).Salinity is governed by the interactions between precipitation, surface runoff,ground-water flow,evaporation,and,in some cases, evapotranspiration by plants.The ionic ratios of inland waters usually differ appreciably from those found in the sea,although there are some exceptions (Bayly"196]).The great chemical diversity of these waters, the wide variation in physical conditions such as temperature,and the relative impermanence of surface water in many cases,make it extremely difficult to subdivide the inland salinity range in a meaningful way. Bayly (196])has attempted a subdivision on the basis of animal life; Stewart and Kantrud (1971)and Moyle (1945)have suggested two very different divisions on the basis of plant I ife.We have decided to employ a subdivision which is identical t.o that used in the Estuarine and Marine Systems (Table I). The term saline is used to indicate that any of a number of ions may be dominant or co-dominant.The term brackish has been applied to inland waters of intermediate salinity (R~mane and Schlieper 1971, Stewart and Kantrud 1971),but is not universally accepted (see Bayly j 1967:84).;therefore,mixosaline will be used here.In some inland wet- lands high soii salinities control the invasion or establ;ishment of many Table J.Salinity Modifiers Used in This Classification System. Coastal Modifiers l Hyperha line Euha.1 ine Mixohaline (Brackish) Polyhaline Hesohaline 01 igohaline Fresh Approximate Specific Inland Sal inity Conductance Hodifiers 2 (%0)(llHhos at 25°C) Hypersal i ne >40 >60,000 Eusal ine 30 -40 45.000-60.000 Mixosal ine3 0.5-30 800-45,000 Polysal ine 18 -30 30,000-45.000 Hes.osa line 5 -18 8.000-30.000 01 i gosa I i.ne 0.5-5 800-8,000 Fresh <0.5 <800 ICoastal modi·f.iers are employed in the Marine and Estuarine Systems. 21nland,modifiers are employed in the Riverine •.lacustrine and Palustrine Sy stems. 3The term Brackish should not be used for inland wetlands or deep-water habitats. 57 plants.These salinities are expressed in units of specific conductance as well as percent salt (Ungar 1974),and they are also covered by the salinity classes in Table 1. 2.pH MODIFIERS Acid waters are,almost by definition,poor in calcium and often generally low in other ions,but some very soft waters may have a neutral pH (Hynes 1970).It is difficult to separate the effects of high concentrations of hydrogen ions from low base content,and many studies suggest that acidity may never be the major factor control 1 ing the presence or absence of particular plants and animals.Nevertheless,some researchers have demonstrated a good correlation between pH levels and plant distribution (SjHrs 1950,Jeglum 1971).Jeglum (1971)showed that plants can be used to predict the hydrogen ion concentration 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 freshwater, organic wetlands into mineral-rich and mineral-poor categories (SjHrs 1950,Heinselman 1970,Jeglum 1971,Moore and Bellamy 1974).We have instituted pH modifiers for freshwater wetlands (Table 2)because pH has been widely used to indicate the difference between mineral-rich and mineral-poor sites,and because it is relatively easy to determine.The ranges presented here are similar to those of Jeglum (1971),except that the upper limit of the circumneutral level (Jeglum's mesotrophic)was 58 raised to bring it into line 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 2 pH Modifiers Used in This Classification System Modifier Acid Circumneutral Al ka 1 i ne pH of Water <5.5 5.5-7.4 >7.4 So i 1 Mod i fie rs Soil is one of the most important physical components of wetlands. Through its depth,mineral composition,organic matter content,moisture regime,temperature regime and chemistry,it exercises a strong influence over the types of plants that live on its surface and the kinds of organisms that dwell within it.In addition,the nature of soil ina 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 (U.S.Soil Conservation Service,Soi 1 Survey Staff 1975:1-2),soil is limited to terrestrial situations and shallow waters;however,"areas are not con- sidered to have soil if the surface is permanently covered by water deep 59 enough [50]that only floating plants are present.II Since emergent plants do not grow beyond a depth of approximately 2 m in inland waters, thewaterward limit of soil is virtually equivalent to thewaterward limit of wetland,according to our definition.In marine and estuarine areas,subtidal lands do not have soil.Wetlands can then be regarded as having soil in most cases,while deep-water habitats are never considered to have soi 1. 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 soi 15 (Histosols)in.their taxonomy.Their classification is hierarchical and permi ts the description of soi Is at several levels of detai 1.For example,.suborders of Histosols are recognized according to the degree of decomposition of the organic matter. We have chosen the modifiers mineral and organic for use in this classification.Mineral soils and organic soils are differentiated on the basis of very specific criteria which are enumer~ted in the Soil Taxonomy (U.S.Soil Conservation Service,Soil Survey Staff 1975:13-14, 65).These criteria have been restated in Appendix C of this classifi- cation for ready referen.ce.If more detail is desired,the U.S.Soil Conservation Service classification system should be used. Special MOdifiers Many wetlands and deep-water habitats are man-made,and natural ones have been modified to some degree by the activities of man or 60 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 deep-water habitats. 1.EXCAVATED Lies within a basin or channel excavated by man. 2.IMPOUNDED Created or modified by a barrier or dam designed to obstruct the outflow of water.Both man-made and beaver dams are included. 3.DI KED Created or modified by a man-made barrier or dike designed to obstruct the inflow of water. 4.PARTIALLY DRAINED Water level has been artificially lowered,but the area is sti 11 classified as wetland because soil moisture is sufficient to support hydrophytes.Included under this heading also are lands where low water levels are maintained by continuous pumping;although such areas may not support hydrophytes presently,they could if pumping ceased.Permanently drained areas are not considered wetland. 61 5.FARMED The soil surface-has been mechanically or physically altered for production of crops,but wetlandplahts will become reestabl ished if· farming is discontinued. 6.ART!FICIAL Refers to substrates classified as Bottom;Rocky Shore,Flat or Beach/Bar that were emplaced by man using either natural materials such as dredge spoil or synthetic materials such as discarded automobiles, tires or concrete.JettIes and breakwaters are examples of Artificial Rocky Shores.Man-made reefs are ah example of Artificial Rock Bottoms. 62 IV.REGIONALIZATION In this classification system,a giveh 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 wet- land habitats;and,often,different regions have bery different management problems.For these reasons,we felt the need to recognize regional differences.Regionalization is designed to facilitate:1) planning at th~national level,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~nimals among the regions. We have recommended the classification ahd map of Bailey (1976) to fill the need for reglonallzation inland.Bailey's classification of ecoregions is hierarchical.The upper four levels are:domain,defined as including.subcontinental areas of related climates;division,defined II ()as including regional climate at the level of Koppen's 1931 types; province,defined as including broad vegetational types;arids~ction, defined as including climax vegetation at the level of ~chler's (1964) types.On the map,the boundaries between the different levels are designated by various 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's map for a discussion and description of the units appearing on the map. 63 The Bailey system terminates at the ocean,whereas this wetla~d classification includes .marine and estuarine habitats.Many workers have divided marine and estuarine realms into series of biogeographic provinces·(e.g.,U.S.Senate 1970,Ketchum 1972).These provinces differ somewhat in detail,but the broader concepts are similar.We have developed the following marine and estuarine provinces for North America: ARCT i C PROV I NCE· Arctic Province extends from the southern tip of Newfoundland (Avalon Peninsula),~orthward around Canada to the west coasts of the Arctic Ocean,Bering Sea,and Baffin and Laborador Basins.It is characterized by the southern extension of floating ice,the 4°C summer isotherm,and arctic bJbt~~ ACADIAN PROVINCE 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 very indented and frequently rocky.It has a large tidal range and is ~trongly influenced by the Laborador Current. VIRGINIAN PROVINCE Virginian Province extends along the middle Atlantic coast from Cape Cod to Cape Hatteras.The province is transitional between Acadian and Carolinian.The biota is primarily temperate with some boreal representatives.The Laborador Current occasionally extends down to Cape 64 Hat teras and wi nter temperatures may approach 4°C •The t ida I range is moderate. CAROLINIAN PROVINCE Carolinian Province is situated along the south Atlantic coast from Cape Hatteras to Cape Kennedy •.It contains extensive marshes and well-developed barrier islands.Waters are turbid and productive.The biota is temperate with seasonal tropical elements.The Gulf Stream is the primary influence and winter temperatures reach a minjmum of 10°C; summer temperatures are tropical (in excess of 20°C).The tidal range is small to moderat~~ WEST INDIAN PROVINCE West Indian Province extends from Cape Kennedy to Cedar Key, Florida and also includes the southern Guif of Mexico,the Yucatan Peninsula,Central America and the C~rribbean Islands.The shdreland is usually low lying 1 imestone with calcareous sands and marls except for volcanic islands.The biota is tropical and includes reef c6rals and .."" °mangroves.Minimum winter temperatures are about 20e and the tidal range is small. LOUISIANIAN PROVINCE 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 bi6ta is prImarily temperate and the tidal range is small. 65 CAL1FORNIAN PROVINCE Cal lforriian Provirice ext~nds al~ng the Pacifit coast from Mexico northward to Cape Mendocino~The sho~eland is strongly influenced by coastal mountains and the coasts are rocky with I imited freshwater runoff. In the southern part volcanic sands are present;marshes and swamps are scarce throughout the province.The climate is Mediterranean and influenced by the California Current.The biota is temperate,and includes well-developed offshore kelp beds.The tidal range is moderate. COLUMBIAN PROVINCE Columbian Province extends along the northern Pacific coast from Cape Mendocino to Vancouver Island.Mountainous shore land with rocky foreshores are prevalent.Estuaries are strongly influenced .by fresh- water runoff.The biota is primarily temperate wit~some boreal components,and there are extensive algal communities.The province is influenced by both the Aleutian and ·CaliforniaCurrents.The tidal range is moderate to large. FJORD PROVINCE Fjord Province extends along the Pacific coast from Vancouver Island to the southern tip of the Aleutian Islands.Precipitous mountains,deep estuaries (some with glaciers),and a 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. 66 PACIFIC INSULAR PROVINCE Pacific Insular Province·surrounds all of the Hawaiian Islands. The coasts h~ve pfecipit6us mount~ins and wave action is stronger than in most of the other provinces.The biota is largely endemic and composed of tropical and subtropical forms.The tidal range is small. Use of Bailey's sections for the rive~ine,lacustrine and palustrine systems and the provinces defined above for the marine and estuarine systems provide a regional locator for any wetland in the United States. 67 v.USE OF tHE CLAsSIFICATION SYSTEM This system was desi~nedfor use Over an extremely wide geographic area and for use by individuals and Qrganization~with varied interests and objectives.The classification employs 5 system names,8 subsystem names,12 class names,24 subclass names and an uhspecified number of dominance types.It is,of necessity,a complex system when viewed in its entirety,but use of the system·for a speci~lc purpose at a local site should be simple and straightforward.The purpo.se of this section is to illustrate how the system should be used and some of the potential pit- falls that courd lead to its misuse. Before attempting to apply the system,·the user should consider certain important points: 1)Information about the area to be classified must be available before the system can be appl ied.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 will be few areas where sufficient information is available to allow the most detailed application of the system.If the level of detail provided by the classifica- tion is not sufficient for the needs of the user,additional data gathering is mandatory. 2)Below the level of class,the system is open-enoed and incomplete.We give only examples of the vast number of Dominance Types that occur.The user may idehtify additional ·68 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 may become apparent. 3)One of the main purposes of the new classification is,to assure uniformity throughout the United States~It is important that the user pay particular attention to the definitions in the classification.Any attempt at modifica- tion of these definitions will lead tb lack bf uniformity in application. 4)One of the principal uses of the classification system will be the inventory and mapping of wetlands and deep-water habitats.A classification used in 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 arid 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 ft)in diameter with concentric rings of vegetation about the deepest zone.At a scale of 1:500 each zone may be classified and mapped;at 1:200,000 it might be nec~ssary to map the entire basin as one 20ne and ignore the peripheral bands;at 1:100,000 the entire wetland bas in may be sma 11 er than the sma 11 est mappab 1e un i t.In the latter case,maps will seldom be adequate for a detailed 69 inventory and must be supplemented by detailed information gathered by sampling.In other cases ,i t may be necessary to develop mapping conventions for taxa that cannot be easily recognized;for instance,submergent aquatic beds in turbid waters may have to be mapped simply as water. 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 subsystems are most important in applications involving large regions or the entire country.They serve to organize the classes into meaningful assemblages of information for data storage and retrieval. The classes and subclasses are the most importaht part of the system for many users and are basic to wetland mapping.Most classes should be easi1y recogniz~ble by users in a wide variety of disciplines. However,the c;lass designations apply to average conditions over a period of years,and since many wetlands are dynamic and subject to rapid changes in appearance,it will frequently be necessary to have data that span a per)od of years and several seasons in each of those years in order to place a wetland in its proper class. The dominance type is most important to users interested in detailed regional studies.It may benecessa rytoidentifydom i nance 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 70 procedure will be to estimate this parameter from the dominance types. Several studies have related water regimes to the presence and distribu- tion of plants or animals (e.g.,Chapman 1960,Stephenson and Stephenson 1972,Stew~rt and Kantrud 1972). Similarly,we do not intend that salinity measurements be made for all wetlands except where these data are required;in many cases,plant species or associations can be used to indicate broad sal inity 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 ~hat are indicators of salinity (e.g.,Penfound and Hathaway 1938,Moyle 1945, Kurz and Wagner 1957,Dillon 1966,Anderson 1968,Chabreck 1972,Stewart and Kantrud 1972,Ungar 1974). In some areas the dominance types to be expected under different wate·r regimes and types of water chemistry conditions have not been identified,and detailed regional studies will be required before the classification can be applied in detail.In areas where detailed s6il ~aps are available,it is also possible to infer water regime and water chemistry from soil s~ries (U.S.Soil Conservation Service,Soil Survey Staff 1975). Some of the modifiers are an integral part of this system and their useisessential;othersare-Lisedonlyfor 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 1)is 71 optional but these fihercategories should be used where data are avail- able.The user is cautioned not to rely on single observations of w~ter regime or water chemistry.Such measUrements will give misleading results in all but the most stable wetlands.The soil modifiers,mineral or organic,must also be used.If a more detailed 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 orgariic.Sp~cial modifiers are ~sed 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 establ ishing categories differ,2)some of the classifications are not applied consistently in different parts of the country,and 3)the elements classified are not the same in various classifications. The most widely used classification system in the United States is that of Martin et al.(1953)which was republ ished in IICircular 39 11 (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.Table 3 compares 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 fresh water wetland types of CirCUlar 39 by writing more detailed descriptions Table 3.Comparison of Wetland Types Described in Circular 39 with Some of the Kajor Components of this Classification Sy:stem. Classification of Wetlands and Deep-Water Habitats Circular 39 Type Type Type 2 Type 3 Type 4 Type 5 Type 6 Type 7 References for Examples Typical Vegetation Wet Meadow (Stewart &Kantrud 1972,Dix &S~ins 1967 Bottomland Hardwoods (Braun 1950) Sha 11ow-FreshNater Swamps (Pen found 1952) Fen (Heinselman 1963) Fen,Northelin Sedge Meadow (Curt is 1959) Shallow Marsh (Golet &Larson 197~,Stewart &Kantrud 1972) Deep Marsh (Golet &Larson 1974,Stewart &Kantrud 1972) Open.Water (Golet &Larson 1974) Submerged Aquatic (Curtis 1959) Shrub Swamp (Golet &Larson 1974) Shrub-Carr,Alder Thicket (Curtis 1959) Wooded S10IiIlIlp (Golet &Larson 1974) SwaIlIPS (Penfound 1952. Heinsehaan 1963) Classes Emergent Wetland Forested Wet land Emergent Wetland Emergent Wetland Emergent Wet I and Aquat ic Bed AquiJtic Bed Unconso II dated Bot tom Scrub/Shrub Wet I and Forested Wetland Water Regimes Te.porarily Flooded Intermittently Flooded, Saturated S_ipermanently Flooded Seasonally Flooded Perwanent I y Flooded Intermittently Flooded Senlpermanently Flooded Pe~nently Flooded Intermittently Exposed All Nontldal Regimes Except Permanently Flooded All Nontldal Regimes Except Permanently Flooded Wate'r Chemistry Fresh Mlxosallne Fresh Mi,xosal ine Fresh, Mixosal ine Fresh Mlxosa 1'1 ne Fresh Mlxosaline Fresh Fresh -.....J N Table 3.(continu~d) Circular 39 Type Type 8' Type 9 Type 10 Type II Type 12 Type 13 Type I" Type 15 References for Examples Typical Vegetation' Bog (Heinselman 1963, Dansereau &Segadasvianna 1952) Pocosin (Kologiski 1977) Peaty Fresh-Water Swamps (Pen found 1952) Intermittent Alkali Zone (Stewart &Kantrud,1972) Inland Salt Marshes (Ungar 197%) InIand Sa line.Lake COIIIlIUn i ty (Ungar 197%) Marsh (Anderson 1968) Estuarine Bay Marshes,Estuarine River Marshes (Stewart 1962) Fresh &Inter1llediate Marshes (Chabreck 1972) Harsh (Anderson 1968) Estuarine Bay Marshes,Estuarine River Marshes (Stewart 1962) Fresh &Iiltermediate Marshes (Chabreck 1972) Estuarine B3ys •(Stewart &Kantrud,1972) Panne,Harsh Slough (Redfield 1972) Marsh Pans (Pestrong 1965) Classes Scrub/Shrub Wetland Forested Wetland Moss/Lichen Wet land Flat Emergent Wetland Aquatic Bed Unconsolidated Bottom Emergent Wetland Emergent Wetland Aquatic:Bed Unconsolidated Bottom Flat Water Reg imes Saturated Seasonal Iy Flooded Intermittently Flooded Temporarily Flooded Seasona II y FJ,ooded Semipermanently Flooded Permanently Flooded Intermittently Flooded Regularly Flooded I rregularly Flooded Semipermanently Flooded- Tidal Regularly Flooded Semlpermanently Flooded- Tidal Subtidal Permanently Flooded-Tidal ReguJarly Flooded Irregularly Flooded Water."Chemi st ry Fresh (acid only) Eusal ine Hypersal ine Eusal ine Eusal i ne Mi xoha I ine Fresh '. Mixoha.1 ine Fresh Hixohallne Fresh Hyperha line Euhal ine Table 3.(continued) Ci rcular 39 Type Type 16 Type 17 Type 18 Type 19 Type 20 References for Examples Typical Vegetation Salt Karsh (Chapman 1960, Redfield 1972) Sal'tKarsh (Chapman 1960) Saline,Brackish &Intermediate (Ele~terfus 1972) Salt·Karsh (Chapman 1960) Kelp Beds,Temperate Grass Flats (Phillips 1974) Trop'i ca I Kar i ne Meadows (Odin 1974) Eelgras·sBeds (Akins &Jefferson 1973. E.leuterius 1973 KanQrove Swamps (Wa Ish 1974) Kangrove Swamp Systems (Kuenzler 1974) Kangroves(Chapman 1976) Classes Water Regimes Water Chemistry .Emergent Wetland I rregu I ar Iy Flooded Euhal ine "ixohal i ne Emergent Wet land I rregu lar Iy Flooded tuhal ioe "ixohal ine Emergent Wetland.Regularly Flooded Euhaline "ixohaline Unconsolidate~Bottom.Subti dal Euha.line Aquatic Bed I rregul'arly ExpOsed.Hixohal ine Flat Regu lady Floc;>ded Irregularly Flooded """"-'='" Scrub/Shrub Wetland Irregularly Exposed Hyperha line Forested.Wetland Regularly Flooded Euhal ine Irregularly FloOded "i xohal i ne· .. 75 and subdividing classes on the basis of finer differences in plant life forms.Golet ahd Larson's classes are roughly equivalent to Types 1-8 of Circular 39,except that they restricted Type 1 to river floodplains. The Golet and Larson system does not recognize the coastal (tidal)fresh wetlands of Circular 39 (Types 12-14)as a separate cate~ory,but classifies these areas in the same manner as nontidal wetlands.In addition to devising 24 subclasses,they also created five size categories; six site types,giving a wetland's hydrologic and topographic location; eight cover types (modified from Stewart and Kantrud 1971)expressing the distribution and relative proportions of cover and water;three vegetative interspersion types;and six surrounding habitat types.Since this system is based on the classes of Martin et aL (1953),Table 3 may also be used to compare the Golet and Larson system to the one described here. Although our system does not include size categories and size types,this information will be available fro~the results of the new inv~ntory of wetlands and deep-water habitats of the United States. Stewart and Kantrud (1971)devised a new classification 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 five percent or more of the wetland basin.The classes thus reflect the wetland's water regime;for example,temporary ponds (Class I I)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 76 classification in their system is the cover type which represents di ffercnc~5 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 4),and the 5ub- classes are roughly equivalent to our·water chemistry modifiers (Table 5). A classification system is most easily learned through use.To illustrate the application of this system,we have classified a repre- sentative group of wetlands and deep-water habitats of the United States.1 l The final pubilcation wl11 include a classification of a repre-· sentat ive group ofwe.t 1ands and.deep-water habi tats of the Un i ted States. Photographsofth~sehabitats wIll also be provided. 77 Table 4..Comparisoll of the Zones of Stewart and Kan rud1s (1971) Classification with the Water Regime ·Modif ersused in this Classification System Zone (Stewart and Kant rud) Wetland-I ow-pra i de zone Wet Meadow Zone Shallow Marsh Zone Deep Marsh Zone Permanent Deep Water Zone Intermlttent-alkaliZone Fell (Alkaline Bog)Zone Water Regime Modi fier non wetland by one definition Temporarily Flooded Seasonally Flooded Semipermanently Flooded Intermittently Exposed Permanently Flooded Intermittently Flooded (with saline or hypersaline water) Saturated 78 Tab le 5 Cbmparisonofthe Water Chemistry Subclasses of Stewart and Kantrud (1972)with the Water Chemistry Modifiers used in thts Classification System This c111ssif ieation Approximate sp'ecific conductances (Mh Stdwart and Kantrud (·972),..'I ~J os) 100.000 Saline 60.000 H }'persal ine 45.000 Eusaline Pol}saline Subsaline 30.000 15.000 Mesosalint" Brack;sh 8.000 Mixosaline 5.000 Modeiately Brackish Oligosaline 2.000 Slightly Brackish 800 500 Fresh Fresh 40 n 79 .LITERATURE CITED Akins,G.J.,and C.Q.Jefferson.1973.Coastal wetlands of Oregon. 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Azolla spp. Baccharis halmifolia L. Beckmannia syzigachne (Steud.)Fern. Betula pumila L. Brasenia schreberi Campyliu~stellatum (Hedw.)C.Jens. Carex spp. Cephalanthus occidental is L. Ceratophyllum spp. C.demersum L. Chamaecyparis thyoides (L.)BSP. Chamaedaphne caljculata (L.)Moench Chara spp. Chenopodium rubrum L. Chi losyphus fragi 1 is (Roth)Schiffn. Cladium jamaicens Crantz Cladonia spp. Conocarpus erecta L. Decodon verticillatus (L.)E11- Desmatodon heimii (Hedw.)Mi tt. Drepanocladus (C.Mue 11 . )Roth COMMON NAME Red Maple Alders Speckled Alder Bog-rosemary Black Mangrove Mosquito-fern Sea-myrtle Ameri~an Sloughgrass Swamp Birch Water;-sh ie ld Sedges Buttonbush Hornwort Coonta i1 White Cedar Leather-leaf Stonewort Coast-bl ight Sawgrass Reindeer Moss Buttonwood Water-wi 11 ow Aquatic Moss 91 APPENDIX A (continued) SCI ENT I Fie NAME Echinochloa crusgalli (L.)Beauv .. Eichhornia crassipes (Mart.)Solms. Eleocharis aclcularis (L.)R.&S. Equisetum fluviatile L. Fissidens spp. f.jul ianus (Mont.)Schimp. Fontinalis Fraxinus nigra Marsh f.pennsylvanica Marsh Glyceri a spp. Go rdon ia I as i an th us (L.)EI lis Halodule beaudettei (de~Hartog)den Hartog Halophi la spp. Iva frutescens L. Juncus roemerianus Scheele Kalmia polifolia Wang. Laguncularia racemosa Gaertn.f. Ledum groenlandicum Oeder Larix laricina (Du Roi)K.Koch Lemna spp. Leucothoe axillaris (Lam.)D.Don Lyonia lucida (Lam.)K.Koch Lythrum salicaria L. Macrocystis spp. Magnolia virginiana L. Marsupella spp. Myriophyllum spp. Najas spp. Nitella spp. Nuphar spp. N.advena (Ait.)f. N.variegatum COMMON NAME Wild Millet Water-hyacinth Sp i ke-rush Water Horseta i I Water Moss Water Moss Water Moss Black Ash Red Ash Manna-grasses Loblolly Bay Shoal grass Sea-grass Marsh Elder Needle Rush Pale or Bog-laurel White Mangrove Labrador-tea American Larch or Tamarock Duckweeds Leucothoe Tetter-bush Purple Loosestrife Brown Algae Sweet Bay Li verwort Water-mi I foi I Naiads Nitella Spatter-dock Ye I low Pond-lily Variegated Pond-lily 92 APPENDIX A (continued) SCIENTIFIC NAME Nymphaea spp. Nymphoides aquatica (Walt.)o.Kuntze Nyssa aquatica L. ~.sylvatica Marsh Peltandra virginica (L.)Kunth Pelvetia spp. Persea borbonia (L.)Spreng. Phragmites communis Trin. Phyllospadix scouleri Hook. ~.torreyi Wats. Picea mariana (Mill.)BSP Pinus serotina Michx.f. Pistia stratiotes L. Podostemum ceratophyllum Michx. Polygonum spp. ~.amph i bi urn L. Pontederia cordata L. Potamogeton spp. ~.epihydrus Raf. P.natans L. Quercus bicolor Willd. Q.lyrata Wal t. Q.michauxii Nutt. Rhizophora mangle L. Rumex mexicanus Meisn. Ruppia maritima L. Sagi ttari a spp. Sa~icornia pacifica StandI. Sal ix spp. Salvinia spp. S.rotund i fo I ia Will d. COMMON NAME Water-lily Floating-heart Water Gum or Tupelo Gum Black Gum Arrow-arum Slim Brown Rockweed Red Bay Reed Surf Grass Surf Grass Black or Bog-spruce Pond or Marsh-pine Water-lettuce Threadfoot Smartweeds Water-smartweed Pickerelweed Pondweeds Ribbonleaf Pondweed Floating-leaf Pondweed Swamp White-oak Ove r-cup Oak Basket Oak Red Mangrove Widgeon-grass Arrowhead Glasswort or Common Pickleweed Wi llow Water Fern Water Fern .... 93 APPENDIX A (continued) SCIENTIFIC NAME Scirpus acutus Muhl. Scolochloa festucacea (Willd.)Link Spartina alterniflora Loisel. S.cynosuroides (L.)Roth S.foliosa Trln. S.patens (Ait.)Muhl. Sphagnum spp. Spirodela polyrhiza (L.)Schleid. Suaeda californica Wats. Syringodium filiformis Kuetz Taxodium ascendens Brogn. T.distichium (L.)Richard Thalassia testudinum Koenig &Sims Thuja occidentalis L. Trapa spp. Triglochin maritima L. Typha angustifolia L. T.I at i fo I i a L. Ul mus arne r i cana Ulva spp; Utricularia vulgaris L. Vallisneria americana Michx. Xanthium italicum Moretti Zenobia pulverulenta (Bartr.)Pollard Zizania aquatica L. Zostera marina L. Zizaniopsis miliacea (Michx.)Ddl &Asch. COMMON NAME Hard-stem Bulrush White-top Salt-water Cordgrass Big Cordgrass Cordgrass Saltmeadow Cordgrass Peat Moss Big Duckweed Sea-b lite Manatee-grass Pond Cypress Bald Cypress Turt Ie-grass White Cedar or Arbor Vitae Water-nut Arrow-grass Narrow-leaved Cat-tail Common Cat-tail American or White Elm Sea lettuce Bladderwort Wi Id Ce lery Cocklebur Zenobia Wi Id Rice Grass-wrack or Eelgrass Water Mi llet SCIENTIFIC NAME Acmaea Acropora Amphitrite Amphiura Anodonta Anopheles Arenicola Baetis Balanus Caenis Callianassa Cerianthiopsis Cerithium Chaeopterus Chaoborus Chiredotea Chironomus Chthamalus Cnemidocarpa Crassostrea Dendraster Diamesa Donax Echinocardium Emeri ta Ephemera Eukiefferiella Gammarus 94 APPENDIXB SCiENTIFIC AND COMMON NAMES OF ANIMALS COMMON NAME'" Fa 1se Li mpet Coral Terebellid Polychaete Starfi sh Freshwater Clam Mosqui to Lugworm Mayfly Barnacle Mayfly Burrowing Shrimp Sea Anemone Sna i1 Polychaete Diptera Isopod Midge Barnacle Ascidian Oyster Sea Star Dipte ra Wedge She 11 Sea Urchin Sand Bug May Fly Diptera Amphipod .. 95 APPENDIX B (continued) SCIENTIFIC NAME Haustori us Herpobdella Hi ppospong ia . Hydropsyche Leptosynapta Limnea Li mnodr i 1us Littorina Lumbriculus Lygia Lymnaea Macoma Me 11 ita Mitel1a Modio Ius Montipora Muri cea Mya Mytilus Nassar ius Nemoura Nereis Ned ta Ocypode 01 iva Orchest ia Paract is Parastenocaris Patella Pecten Penaeus "" ",',,: COMMON NAME'" .{\mp~ipo? Leech Encrusting Sponges Caddis Fly Holothurian 01 i gochaete Periwinkle 01 i gochaete Isopod Freshwater Snail Te 11 in She 11 Amphipod,. Barnacle Mussel Coral Al cyonari an Long Neck Clam Mussel Mud Sna i 1 Plecoptera Polychaete Periwinkle Gho?t -Crab Amph i pop" Oyster Sea Anemone Cope pod Limpet Sea llop Shrimp 96 APP~NDI X B (cont i m.ted) SCIENTIFIC NAME Phyllognathus Physa Pi sas ter, Pisidium Pori tes Pri st ina Renilla Sabellaria Siphonaria Spatangus Spongi I la Strongy 19centrotus Tel Ii na Tet racJ ita Thais Thyone Thoracophel ia Tivela Tubifex Uca Urechis COMMON NAME'" Capepod Freshwater Snail Seastar Mo 11 usk Coral 01 i gochaete Sea Pansy Reefworm False limpet Heart Urchin Sponge Sea Urchin Tellin Shell Barnacle Rock She 11 Sea Cucumber Bamboo Worm Pismo"Clam Sewage Worm Fiddler Crab Echivrid *Organisms are identified only to genus,so the common name refers to general groupings. .. 97 APPENDIX C CRITERIA FOR DISTINGUISHING ORGANIC SOILS FROM MINERAL SOILS The criteria for distinguishing organic soils from mineral soils in the United States (U.S.Soil Conservation Service,Soil Survey Staff 1975:13-14,65)are quoted here so that those without ready access to a copy of the Soil Taxonomy may employ this information in the classification of wetlands: For purposes of taxonomy,it is necessary,first,to define the limits 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 wi th 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 arti- ficially 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.A full definition of : organic soil materials is given in Chapter 4. 98 DISTINCTION BETWEEN MINERAL SOILS AND ORGANIC SOILS Most soils,are dominantlymineri:ll material,but many mineral soils have horizons of organic material.For simplicity in writing definitions of taxa,a distinction between what is meant by a mineral soil and an organic soil is useful.In a mineral soil,the depth of each horizon is measured from the top of the first horizon of mineral material.In an organic soil,the depth of each horizon is measured from the base of the aerial parts of the growing plants or,if there is no continuous plant cover,from the surface of the layer of organic materials.To apply the definitions of many taxa,therefore, one must first decide whether the soil is mineral or organic. If a soil has both organic and mineral horizons,the relative thickness of the organic and the mineral soil materials must be con- sidered.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 thick- ness of layers in the field than it is to determine tons of organic matter per hectare.The definition 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 material~.The definition that follows is intended to classify as mineral soils those that have no more organic material than the amount permitted in the histic epipedon,which is defined later in this chapter. To determine whether a soil is organic or mineral,the thickness of horizons is measured from the surface of the soil whether that is the surface of a mineral or an organic horizon.Thus,any 0 horizon at the surface is considered an organic horizon,if 'it meets the requirements 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 <2mm in diameter (the fine-earth fraction) makes up more than-half the thickness of the upper 80 cm (31 in.)CsicJ; 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 mated a 1;or 3.The depth to bedrock is >40 cm,the mineral soil material immediately above the bedrock is 10 cm or more thick,and either a.Organic soil material is <40 cm thick and is decomposed (consisting of hemic or sapric materials as defined later)or has a bulk density of 0.1 or more;or l' • 99 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 artificially drained and t excluding live roots t (a)have 18 percent or more organic carbon if the mineral fraction is 60 percent or more clay, (b)have 12 percent or more organic carbon if the mineral fraction has .no clay,or (c)have a proportional content of organic carbon between 12 and 18 percent if the clay content of the mineral fraction is between zero and 60 percent;or 2.Are never saturated with water for more than 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 a horizons.Not all organic soil materials accumulate in or under water.Leaf litter may rest on a lithic contact and support a forest.The only soil in this situation is organic in the sense that the mineral fraction is appreciably less than half the weight and is only a small percentage of the volume of the soil. DEFINITION OF ORGANIC SOILS Organic soils (Histosols)are soils that 1.Have organic soil materials that extend from the surface to one of the following: a.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 fragmental material (gravel t stones,cobbles)and the interstices are filled with organic materials t 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 Ibs per cubic foot); (2)40 cm or more if (a)The organic soil material is saturated with water for long periods (>6 months)or is artificially drained; and (b)The organic material consists of sapric or hemic materials or consists of fibric materials that are less than three-fourths moss fibers by volume and have a moist bulk density of 0.1 or more;and 100 b.Have organic soil materials that (1)Do not have a mi nera 11 ayer as much as 40 cm th i ck 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 wi th in the upper 80 cm.. It is a general rule that a soil is classed as an organic soil (Histosol)either if more than half of the upper 80 cm (32 in.)[sic]of soil is organic or if organic soil material of any thickness rests on rock or on fragmental material having interstices filled with organic materials. Soils that do not satisfy the criteria for classification as organic soils are mineral soils. ..