Bruca G, Marcot, USDA ForestService, Six BrversNat onal Forest, 507 F StreetEureka, California 95521'

Limnology,Vegetation, and Classificationof CoastRange Slump-formed

Abstract

Slunp-formed ponds afford scarceriparian and aquatic in north co{sral California. Thi6 study prolides i.tormarion and a classificarionsysten for their nanagement.Iourteen slunp-forned pondswere studied in rhe CoastRange ofno.th{eslern California during 1975-I9?6for linnological and vesetarion characrerisrics.The ponds areraeed 2.4 m naiimun depth and 0.56Ia sudacearea. Subsu.face conrours and hypsographiccunes suggestedvarious stages of basinfi -in. Warer quality(dissolved oxysenand t€nperature) and ih€ presenceof species(Nygaard's trophic index) provided evidencerhar the ponds wer€ typically mesotrophicto eurrophic. Algal, subnergenl, emergent,and ripa.isn vascular planr specieswere id€.tiai€d. Ponds werecla$ifi€d basedon wat€r perna.ence (eph€meral,aststic, and stable)and succ€ssionalsrase (desre€ ofbasin fill,in). classescorresponded to unique conbinations of limnological and vegetation characreristics.The pond classificarionsystern is useful for guiding nanagement acriviries to rehabilitate, naintain, and enhanceriparian and aquaric habirals associated

Introduction pondswere identified frorn aerialphotos (scale Little is known of the physical and biological l:15,840)and from field surveysand werechosen characteristicsof slump-formedponds in the to representa cross-sectionof physicaland bio- CoastRange of the Pacificstates, although rhe logical conditions.The steepslopes on which the total area of and fresh-wateraquatic pondswere found weretypically composed of un- habitatsis relativelysmall and hasbeen declin- stableregolith and mass-vastingwas fairly com- ing in recentyears in the west(e.g., Sands and mon throughout the region. Howe l9??). Specifically,the riparian in The generalstudy area is characterizedby the coastalfoothills of HumboldtCounty in the warm dry summersand cool wet .Average CoastRange of northernCalifornia comprises 0.2 annual rainfall is 64-165 cm; averagemonthly percentof the county'stotal acreage,but is the is as high as 2540 cm during mostvaluable habitat as a concentrationpoint Novemberto January,and as low as 0-2 cm dur- for many floral and faunal species(California ing July and August (data from Lower Triniry Departmentof Fishand Game1965, Thomas el RangerDistrict office,Six RiversNational Forest, al. 1979). Willow Creek,California). Mean minimum month- This study was promptedby the need for ly temperaturesrange 0-4oCduring and understandingthe limnologicaland vegetational 7-1l"C duringsummer: and maximumrempera- characteristicsof Coast Range slump-formed tuies range from 7-l3oC during winter and pon-dsas a basisfor developingmarlagemenr 30-35oCduring .Summer veather during criteria.The objectivesof the studywere to (l) the study was drier and warmer than average. describephysical and chemical limnological All ponds were within the Mixed Evergreen characteristics,(2) describeaguatic and with Chinquapir:'(Casta.n opsis chrysoplrylln) vegetation,and (3) develop a classification or Rhododendron(ft hodod.end.ron macrophyllum) system,based on limnologicaland vegetation rcgelaliontypes (Kiichler 197?). Dominant tree characteristics,for describingand predicting speciesin thesetypes arc Douglas-fir(Pseudotsuga both physicaland biologicalattributes. menziesii),tanoak (Lithocarpusdensiflora) and Study Area Pacific madrone(Arbutus menziesir. During 1975-1976,l7 pondswere located and Methods studiedon Six National Forest in the CoastRange of northwesternCalifornia. The LimnologicalSunteys. Pond maximum length (l), breadth, surface area (A), and shorelinelength 'Currenr address:USDA ForesrService, Mr. Hood National (L) weremeasured on all pondswith a planimeter Forest, 2955 N.V. Division St., Cresham,Oreson 97030 on aerialphotos or on surfacemaps developed

NorthwestScience, Vol. 64, No. t, 1990 55 in the field by using an alidade and plane surface. Algae were identified to speciesand (Welch 1948,Lind 1974).Mean breadth(A/1) and trophic state of each pond was indexed by the shorelinedevelopment indices (L/2.1[zA]) were relativeproportions of variousspecies in the calculatedfor eachpond. The shorelinedevelop- samples(Nygaard 1949). ment index describesshape of eachpond by com- Submergenls.emergenls. and riparian rege- paringthe shorelinelength to a circlewith the tation weresampled during summerat six ponds samearea as the pond. The smallestpossible (Underwood,Bushwack, Primal, GreaterTwin, value is 1.0, representinga circle, and index LesserTwin, and DuckweedPonds) chosen to valuesincrcasp as the shapebecomes more ir- representa spectrumof depth, surfacearea, (Cole regular 1975,Lind 1974). degree of basin fill'in, and lrater permanence. Maximum depth and percent relatiye depth Sr.:bmergentvegetation vas sampledin each of all pondswere measured by soundingsfrom of the six pondswith B0 scoopsof a rake at even a raft. Hypsographiccurves were estimated from inteNalsalong two transectsacross each pond. benthiccontours drawn for four pondsrepresent- Frequencyof each specieswas determined(no. ing early and late stagesof basin fill-in (Bee,Red scoopsa specieswas observed in/80 total scoops) ,Onion, and BrokenRib ).Cal- and a descriptive scale for frequency of sub- culationsof morphologicpararneters followed mergentswas used(available from author). For Cole(1975) and Welch(1948). Poles marked in purposesof this study, duckweedswere con- 0.2 m intervalswere placedin eachpond and sidered as submergentsbecause they occurred \,yasmeasured by recording Permanence in the scoopsamples. Density (no. stems/m2) of changesin surface elevations biweekly during eachstand of emergentvegetation was estimated 1975 and 1976 summersand bimonthly during by averagingthe number of stemswithin a wire the l9?5-1976year. Sediment depth was probed frame(1 x I m) placedrandomly at 20 locations in all pondsduring summer1975 with a tele- within eachemergent sland. scopicpole. Riparianvegetation was sampled by use of Temperatureand dissolvedoxygen (DO) were fixed-areaplots, the sizeof whichwas determined rnonitoredat 0.3m intervalswith a portableDO from species-areacurves derived from nested andtemperature meter (Model l0l0 DeltaScien- quadrats(Dosting l95B). Plot tific Corporation)four times during late summer shapeswere rec- tangular(sides 3:1, the longerrunning parallel 1957 in four ponds representingvariable or to the shoreline),Twenty plots were distributed stablewater conditions, The meter wascalibrated evenlyaround each shoreline immediatelybefore each measurement.Five and vegetatronrtas assessedby using the Braun-Blanquetcover- watersamples were taken at randomdepths and abundancescale (Mueller-Dombois and Ellenberg locationsfrom eachpond and analyzedin the Six l9?4). Percentfrequency was calculatedand RiversNational Forest laboratory for pH, con- modalcover determined of speciesover l0 per- ductivity,and rurbidity (Model7 pH Meter, Corn- cent frequent. ing ScientificInstruments; Model R83 Conduc- tivity Meter,Bechman Instruments; Model 2100A Quantitativedescriptions of submergent, Turbidimeter,Hach ScientificEquipment). emergent,and shorelinevegetation from the six legetation Sampltng. Algae were sampled pondswere supplemented by qualitativeobserva- during summer at four ponds (Primal Pond, tionsof pondbasins and vegetation made at all BushwackPond, Sucker , and Big Lake) 17 ponds. Descriptionsincluded pond basin chosenbecause they variedgreatly in physical topography,and frequencyand coverof vegeta- characteristics(especially water permanence)and tion speciesestimated by eye. would provide a vide variety of species.The Pond Chssification.The purposeof develop- pondssampled represented the wide range of ing a classificationsystem was to identify unique ponds (except for the early successional structural and floristic attributes of different ephemeralclass) included in the classification types of ponds to help predict physicaland systemthat was ultimately developed.Three biological responsesto managementactivities algaesamples were taken from each pond by and guide managementstrategies. Classification planklonnet tow, squeezingsfrom submergent basedon vegetationcharacteristics alone was not flora (tychoplankton),and skimming the water sufficient for this purpose. The intent was to

56 Marcot devisea systemby which vegetation character- ly and late stages)of ephemeralponds correlated isticscould be predicted from other, physicalat- with diagnosticcharacteristics. Limnological and tributesof the ponds. vegetationcharacteristics were related to each To devisethe classificationsystem, results of of the pond classes. the vegetationsamples and qualitative descrip- tionsof all pondswere related to the chemical, Resultsand Discussion physical,and trophic attributesof the ponds. Lirnnology Sincemost ponds were mesotrophic to eutrophic, trophic state was not a helpful criterion to dis- The ponds were likely formed by the mass- tinguishamong ponds. Water quality(pH, con- wastingprocess of creep,a slumpagethat ductivity, , dissolved oxygen content) created small basinsthat filled with snow-melt, seemedto vary in responseto physicalconditions seepsprings, or runoff. On average,the ponds of thepond basins and associatedvegelation. measured133 m maximumlength, Tl m maxi Ultimately,the pondswere classified based mum breadth,and 38 m averagebreadth (Table on \,raterpermanence and successionalstage 2). Surfacearea averaged0.56 ha and shoreline (Table l). FollowingCole (1975),successional length averaged328 m. Most pondswere roughly (average stagewas defined as degreeof basin fill,in. Suc- oval in shape shorelinedevelopment in- cessionalstage was described qualitatively as dex of 1.33). "early" if the pond basinwas relatiyely steep and Waterpermanence varied among the ponds, "late" had only a shallowmuck depth,and if the although maximum depth averagedonly 2.4 m. pond basinwas gently slopedand had a deep Sevenponds were relatively stable over the sum- amountof muck and sediment.In this classifica- mer,varying less than l0 percentfrom their max- tion, degree of basin fill-in did not necessarily imum depth.Four pondswere more astatic and correlatewith trophic condition.Water per- varied in surface elevationover the year by as manenceclasses included stable, astatic, and much as 55 percentfrom their maximum depth. ephemeralponds. Also, successional stages (ear- For example,Sucker Lake varied 2.5-5.6m

TABLE L Classificationcharacteristics of Coast Range slunp-forned ponds.

Slumppond cla$

Epheneral

Earhsucce$ional Latesuccessional

Surfaceelevation r iation < l0% fron max. dries regularly d€pihi dries infrequentll Emergent stands little o. none Floating mats peripheral few or none Shorelineevaporation zone broad; with an- lery narrov or nuals, lush sedse absent with shrubs recenrly flooded o.

Substrate hoderately deep steep; mud or shallow; gently nud and peat gravel sloped or lerel;

Floating logr lypically nanY, severali sparse to fe{; no yeg. gro{th with lush veg. mod. veg. growth nod. veg.gro{th growrh

Inflow srasonal; ru noff.fed -fed seasonali spnng- or runoff-fed

Limnology, Vegetation, and Classificationof Slump-formedPonds 57 TABLE 2. Physical limnological characteristicsof Coast Range slump-forned ponds.

subsu.facemeasures

Maximum Mean Surface Shoreline Shoreline Marinun Percent length Breadth breadth l€ngth derelopoent Pond Pond (.) (.) (.) (h") (.) index (.) slop€

Broken Rib L. 81 30 I5 0.12 189 1.51 3.5 l8 EarlJ Stable Blue L. 175 75 54 0.94 4',14 t.37 5.6 I EadYStable Bee L. 279 t52 27 0.74 369 1.21 1.8 4 Laie Stable Red Mi. L. 213 68 3? 0.78 503 1.60 2.0 4 LateStable 0nion L. 124 7l 47 0.59 318 Lt? 2.0 5 LateSrable Pinal Pond I0l 64 39 0.39 t.52 5.0 14 LateStable BushwackPond t13 50 3l 0.35 280 1.34 2.4 ? Late Stable SuckerL. t76 50 23 0.41 402 t.71 2.5 7 Eaflt Astatic DuclweedPond 84 64 43 0.36 213 1.00 1.5 Unden"oodPond 56 39 27 0.r5 156 l.t4 3.0 14 Late Aslalic CreaterTwin P. ?0 48 40 0.28 195 t.04 1.1 HiddenPond ?0 40 250 4.0 nd larty lphemeral LesserTrin Pond 66 39 29 0.19 175 t.14 1.8 ? [arly lpheme.al Big L. 25t 201 81 2.04 ?31 1.45 1.5 2 Late [phemeral

MIANS

"Succesional srage(earlv,late) or degreeof basinfill-in and degree of{ater pemanence(stable, astatic, epheneral). See text fof descnplions.

'Based o! 17 ponds(rhree additional ponds measured0.8, lJ, and 1.1 m maximumdeptb). maximum depth from summer to winter. One pond (Hidden Pond,Table 2) measured4.0 m maximumdepth during spring but dried in a periodof24 days(17 June to l0 July).Water per- l manencevaried probably becauseof differences o in watersources and permeabilityof substrates. Becauseof the shallowness,all pondsstudied are 6 probablypolymictic, i,e,, characterized by many or continualoverturn periods (Cole 1975). c o' The percenthypsographic curves of the three latesuccessional, stable ponds (Bee, Red Moun- c tain, and Onion Lakes) were concavein form (Figurel). This shaperepresented gently slop- ing shorelinesand broad,shallow, bottoms, 01234 characteristicof pondsin late stagesof basinfill- in, The curveof the early successional,stable Deplh (m pond (BrokenRib Lake) r4acmore convexin Figrre l. Percentvolume hvpsographic curves of four sralte, shape,representing steeper basin walls and a slump-formedponds in rhe north CoastRange of more angularbottom. Over all ponds,basin slope California. Broken Rib Lake is in an early succes- sional stageo{ basin fill-in; the others are in late ryasmoderately gentle; relative slope of the bot- tom averaged7 percent(Table 2). Basinshapes werelikely a resultof (l) topographiccontours or fill-in (successionalstage). In general,the of the slump concavityand (2) degreeof ponds that were in a later stage of fil-in (e,g.,

58 Marcot Dissolvedoxygen (mg/l O2)

458 2468 2468

r-

.l-

O

'1 5 20 25 15 20 t3 15 20 25 15 20 25

remperoTure(uJ/^\ -

Figure 2. Temperature(T) and dissohed oxygen(DO) profiles o{ pond classesduring sumner. (a) Late'successionalstable pond (29 June, Prinal Pond lseeTab]e 2 for oth€r pond characteristicsl).(b) Lare succ€ssionalstable pond with subsurface 'nat of MrtiophyUum enlbescens ssp.eralbes.ens (22 lvlr, BvshwackPond). (c) Early successionalastatic pond (5 August, Sucker Lake). (d) Late-successionalephemeral pond (24 A,.rgust,Big Laxel.

Big Lake, CreaterTwin Pond and Duckweed Both temperatureand DO curvesin one pond Pond.Tablc 2) rere shallower(lo!rer maximum (BushwackPond; Figure 2b) resultedfrom the depth),more gently sloped (lower percent mean presenceof a sub-surfacevegetation mat of water slope),and had greatersediment depths than rmilfoil (MyiophyLlum spicatum ssp.exalb escens\ pondsin an earlier stage(e.g., Primal Pond, and an underlyingorganic matter bed, The DO BrokenRib Lake).Late successionalponds ac- curveexhibited a clinogradeprofile, characteriz- cumulatedsediments of up to 1.8m depth,where- ing a stiatified eutrophiclake with a largevegeta- asearly successional ponds had sediment depths tion biomassin the and a stagnant of 0-0.5 m. (Cole 1975).However, the near- Temperatureand D0 profiles (Figure 2) linearlemperalure curve and shallon marimum revealedmarked differencesamong the four depth (2.4 rn) suggestedthat thermal stratifica- pondssampled. oning to variousmal.imum tion wasunlikely. depths, vegetation composition, and basin shapes.None of the pondsthat weremeasured Temperatureand DO curvesin one pond exhibitedthermal stratification.DO levelsvaried (SuckerLake) that lackedemergent rooted vege- from 8 mg/l at the surfaceto lessthan 2 mg/l at tation were nearly vertical (Figure 2c). This was the bottom. DO curvestypically exhibited an or- probablybecause of the lake's shallowdepth (2.5 thogradeprofile (Figures 2a, 2c), characterizing m) and opennessto variablewinds (located on an even oxygen distribution during overturn a ridge)and thus continualoverturn. DO levels (Cole1975). werequite low.The temperaturecurye was nearly

Limnology, Vegetation, and Classificationof Slump-formedPonds 59 isothermal, with a surface-bottomgradient of 25 from the surfaceskim samples,and 59 from only 1.2"C. all sarnplescombined. The temperature profile in one shallow Sampleswere taken during late summer, ac- ephemeralpond (Big Lake) vas quite steep countingfor the high numberof taxa(27) of blue- (Figure2d). The presenceof a thick mat of yellow green algae present. The presenceof Aphani- pond-lily (Nuphar p olysepalum)extending from zomcnonlosaquap and Microcystisaeruginosa the surfaceto the maximumtestable depth of 0.6 in the samplesat low levels of abundancein- m wasthe probablecause of a temperaturegra- dicated fairly healthyenvironments. Monitoring dient of ll.5oC over that depth. theseeutrophic indicators as well as the desmids The pH varied from neutral to slightly basic and flagellatesover the yearcould reveal much (mean7.1, range 7.0 to 7.4\.Conductivity values aboutthe arnual trophic healthof eachpond and ranged 130-500(mean 274) rnicromhos/cm. Tur- degreeof input of organicmaterial from the local bidity valuesranged widely amongthe ponds, watershed.The abundanceof Mougeotia and populations 68-560JTUs (mean217) (Table 3). Spirogya, and of epiphytic and tychoplanktonicdiatoms which accompanythem, also indicatedhealthy environments with a mod- TABLE 3. Vater quality characterisricsoffour CoasiRange erate diversity denoting mesotrophy or early slunp-forned pondF. Fire nater samples were taken fron each pond during Auguat and eutrophy,Values of Nygaard'sTrophic Index Septenber1975. (Nygaard 1949)also suggestedmesotrophic to eutrophic conditions (Table 4). Conductivity (micromhos/ Turbidity TABLE 4. Trophic nate ofCoast Ranseslump,forrn€d ponds pH cn) (JrU'') (result! of applying Nygaard's Trophic Ind€x lNysaa.d 19491).All ponds were sanpled on I Primal Pond Septenber 1975. range: 6.95-7.05 370,500 68,110 ?.00 406 86 BushvackPond range: 6.95-7.15 230.260 7l-t40 7.06 250 87 Prinai 2.5 E 0.5-E 0.1-M 0.2-M 4.0-E SuckerLake Pond 7.20.7.30 260-300 230.420 7.24 290 284 Bushwack1.0 E 3.0-E 0/5-M 0.1-M 4.5-E Pond Big Lake rang€: ?.05,?.35 130-180 240.560 Sucker J.0-E 5.0 t 0 r0 \{ 0/8-M 8.0-L 7.t7 149 4t0 Lale BigLake 0/l-M 0/l-M 0/6-M 0/0-M 0/l M "MYX Vegetation : Myxophyc€an = Myxophyceae/D€smideae CHL = Chlorophycean = Chlorococcales/Desmideae Algoe species.Although the pondswere sampled DIA = Diaton = Centralei/Pennales = = during summer-a seasonwhich exhibits the EUG Euglenine Euclinea€(Myxophyceae+ Chloro- coccares/ greatestnumber of eutrophicindicators (e.g., COM = Compound= (MFophyceae + Chlorococcales+ blue-greensand Chlorococcales)-andpulses of Centrales + Euglenineae)/Desnideae differentalgae groups only a few daysapart could M = rnesotropbic greatlyalter the indices. some gcneralizations can E = eurrophic be made. The presence of Eremoshaera oirid.is in All four ponds sampledexhibited a well- Primal Pondmay be a newrecord for the western roundedseries of algal communities(list of algae U.S. This range extensionis previouslyun- speciesis availablefrom the author upon re- documented.Also, it ras noticeablysmaller in quest).A total 105species were directly identified sizethan thosefound in easternU.S. and Europe. or inferred,The totalnumber of speciesin an1 one pond rangedas high as 25 frorn the Submergents.A total of nine submergent tow samples,36 from the tychoplanktonsamples, vascularspecies and two submergentrooted

60 Marcot algae(Chara spp.) were identified (list of species and poisonoak (Toricodendrondirtersiloba). The and vegetationassociations is availablefrom the dominant herbs were {ater hemlock (Cicuta author upon request). Submergent vegetation d,ouglasii\,mint (Mentha aroensis),and sedge richnessraried from 3 to 7 speciesin an) one (Carer ersiccata). Sedge often formed lush pond.Frequency and dominancevaried among shorelinebelts around pondsthat vaied season' submergentspecies within and among ponds. ally in warerlevel more than l0 percentof mar' The pondweedPoromogeton natatls, lotrLd ir all imum depth. 0ther shrubs and herbs occurred pondssurveyed for vegetation,rlas never domi as subdominantsin the shoreline zo[e. Panic nant in frequencyor density.The dominant sub- grass (Panicun capilare) was found only at mergentswere star duckweed(Lemna trisulca), ephemeralponds which typically lackedriparian lesserduckweed (tr. minol), stonewolt,and water shrubs.Several riparian specieswere found only milfoil.0thersubmergents occured assubdom' at stable ponds: cinquefoil, sedge(Carex hind' inants and at lower frequenciesand densities. sir), sundew (Drosera rotundifolia), water Buttercup (Ranunculusagaatilis) was observed hemlock,poison oak, and berry (Rubzsarsizus). only in pondsthat varied at least l0 percentftom One riparian species (Dulichium arun' marimumdepth over a yFar'!lime. d,inaceum\was fowrd in a late'successionalpond Onespecies of bulrush(Scirpus subterminalis) (Big Lake)on a muddyfloating mat. This species wasobserved in a stablepond. The species!tas is rare in California (Mason 1969,Munz 1968) growingerect as a submergentin up to 0.3 m Only two previous specimensfrom Humboldt water and as an emergent in as little as 6 cm County and l0 specimensin other California water,This is the first specimenfrom the Coast counties were discovered in four herbaria Range of California (herbaria searched: UC, searched(UC, HSC, CAS,JEPS). (Voucher speci' HSC,CAS, JEPS). men6 of Sci/pus subterminalis and Dulichium arundinaceum$e depositedat Humboldt State Four emergentmacrophytes were Emergents. University, Arcata, California herbarium.) recorded.The richest emergentflora at any one pond of three species.Densities of consisted Classification emergentstands varied amongthe ponds.Yellow pondJilywas as denseas 20-50 stems/m' and soft- Pondsrrere classifiedbased on degreeof water stemrnedbulrush (Scirpasoolidas) was as dense permanenceand degreeof basinfill-in, asfollows as50-300 stems/m'?. Dominance of emergentsalso (Table l). varied considerably,Ponds in advancedstages Stable ponds. Surface level varied approx' pond-lily, of fil-in typically had lush stands of imately l0 percentor lessfrom maximumdepth. (T1pha bulrush,or broadleafed cattail latifulia); Stable ponds can be recognizedby discrete these stands were widely dispersedacross sur- standsof bulrush, cattail, and other emergents; facesof ponds that varied considerablyin sur' peripheralfloating mats;an intempersionof open faceelevation, and werein discretestands in the water and submergentvegetation; a substrateof more stableponds. deep.soft muck: a narro!1shoreline Ptaporalion "feather Also creating an interspersionwith open zonewith little edge" exposedmud; waterin stableponds were floating logswith lush lush vegetationalgrowth on numerousfloating vegetationalgrowth of grasses,sedges (Carer logs; and by being perennially spring-fed' spp.),and sundryherbs. Among all speciesof Astaticponds. Surface level varied more than macrophytes, cinquefoil (Potentillo sp.) was l0 percentfrom maximum depth; the ponds observedonly in stable ponds, whereasfoxtail dried infrequently. Astatic ponds can be recog' (Alopecurussp.) was observed only in ephemeral nizedby little or no perennialemergent vegeta- ponds. tion; few or no floating mats;a recently flooded Shoreline eoapordtion zoze. Shoreline or exposedshoreline belt of vegetation;a sub' riparian vegetationshowed high variationamong strateof moderatelydeep mud and peat;a broad ponds.Riparian vegetationwas floristically rich. shorelineevaporation zone with annualspecies, The dominant shrubswere nine'bark (Piysocar- lush sedge,and/or exposed mud; floating Iogsbe- pus capitatus),willow (Salir sitc,lrensisand S. ing lessnumerous than in stableponds and with lasiandravar. lancifolia),red alder(Alnus rubra), sparseto moderatevegetational growth; and by

Limnology, Vegetation, and Classificationof Slump-formedPonds 6l being fed perenniallyor seasonallyby springsor if a pond has characteristicsof an ephemeral runoff. system,objectives for habitatmanagement or use Ephemeralponds. Theseponds dry regular- of the pond as a watersource may differ than ly. Those in an early successionalstage can be if the characteristicssuggest a stable system. recognizedby the absenceof emergentvegeta- Natural draw-downsof unstableponds are prob- tion; no floating mats; a very narrordor absent ably beneficialfor seedingdesirable food or cover shoreline evaporation zone; a steeply-walled plant speciesfor wildlife, for consolidatingoozy substrateof mud or gravel;few floating logswith bottomsfor a bettersubstrate to supportrooted no vegetationalgrowth; and by usuallybeing fed vegetation,tbr exposingan aquaticprey basefor seasonallyby runoff.Epherneral ponds in a late wildlife predators,and for encouragingbeneficial successionalstage can be recognizedby emergent changesof water and soil (Marcot vegetationoccurring in more or lessdispersed 1978). stands;central floating mats; a narro1yto broad shorelineevaporation zone and exposedmud Acknowledgments areas;a shallowand genrly sloped or level bot- This study was conductedunder contractNo. tom of deep mud; floating logs being less l0'472-77with USDA ForestService, Six Rivers numerousthan in stableponds and with sparse National Forest. I am grateful to the folloiring to moderatevegetational growth; and by usually personnelfor their assistance:N. Brown, M. being fed seasonallyby runoff. Delamore,R. Hill, J. Kahl,B. Klipfel,D. LaVen, Indicator plant specieswere identifiedfor C. Liesten,S. Loe, D. Osmundson,E. Payne,and each pond class by growth form (submergent, D. Solis.I am gratefulalso ro J. Hilgert of the emergent,and shoreline riparian) (Table 5). The Environmental Protection Agency for his iden- recognitionof pond classesin the field, based rificationand discussionof algaedistributions, on physiognomicand floristic features,may aid Conmentsfrom K. V. Kardongand three anony- in forrnulatingmanagement plans. For example, moucrevie\^ers improved the manuseripl.

TABLE 5. Indicato. plant speciesidenrified for pond classes(see Tabt€ I fo. descriptionsof pond classes).

Pond Clas Epheneral

Submergenls Ranunculus aquatitas" Ranunculusaquatilus" Emergent (no indicatore)

Rorippd curuisiliquq" Drosen rotundifulia Cdrer ath.osta.\o" Trichostemaluum" Roippa cuftisiliqua" To,i co de nd.ro n d.ixeI sito b a Carex athronachya" E upht b iar.e rpyilifotiab In general, forest inl'luence Trichostemaltun"b in the thin shorelinezone. In general, dry site speciesin the receding shoreline zone. "lndicator .pecie. lor pirherabrari, ur pphemFratpondr. 'lndicaror.pe.i's ior "srl)-u.,?sroral pphcmpralpund".

LiteratureCited Lind, O. T. 1974.Handbook of commonnerhods in limnology. C. V. Mosby Cornpany,Saint Louis. California Deparrm€nt of and Came. 1965.California Marcot, B. G. 1978.Flors and fauna of fish and wildlife plan, Vol. IIL Supportins dara.The exisring and pot€n- Iish and Game Connission, California. 679 p. rial slump pond sires in Sia Riyers Narional Forest Cole,C. A. 1975.Textbook of limnolost. C. V. Mosby Con- with reconmendations fo. managemenr.School of pany, S8inr Louis. Natural Resources,Humboldl Srare Universiry, Ar. Kiichler, A. W. I977. Tbe nap of the natural vegelation of cata, California. M.S. Thesis. Calilornia. Map plus explanarorybooklei. Uniyersity Mason,H. 1969.A flo.a of the marehesof California.Univer- of Kansas,Lawrence. sity of Calilornia Press,Berkeley.

62 Marcot Mueller-Donbois, D., and H. Ellenberg. 1974. Ains and Sands,A., and G. Howe.1977. An overiew ofriparian {orests methodsof vegetationecology. John Wiley & Sons, in California: their ecolog) and conserration.In R. . R. Johnsonand D. A. Jones(technical coordinators). Munz, P. A. 1968.A Califorria flora. Univereity of Califor- Importance,preservation and nanagenent of riparian nia Press,Berk€ley. habitar a synposiun. USDA ForestS€rvic€ Ceneral Nygaard,G. I949. Hydrobiological studies of some Danish TechnicalRepon RM'43. Pp. 98-1I5. ponds and laker II. [K. danskeVidensl. Selsk.]Biol. Thonas, J. V., C. Maser, and J. f,. Rodiel I9?9. Ripstian Skr. 7, 293 p. zones./n J. V. Thons Gd.). Wildlife habitats in 0osting,H. S. 1958.A studyof plant communities.W. H. managedforests the Blu€ of Otegon and Freeman and Conpany, San Francisco. Washington.USDA ForestSerrice Agricultural Hand- book No. 553. Pp. 40-47. Receited 27 April 1989 Welch, P. S. 1948.Limnological nethods. McGraw-Hill,New York. Acceptedfor publication I September 1989

Limnology,Vegetation, and Classificarionof Slump-formedPonds 63