CraigA. Steele,lEdmund D.Brodie, Jr., Departmentof B ology,Utah State Univers ty. 5305 Old Ma n H Logan UIah 84322 and JamesG. Maccracken, T .nberDepartrnent 300 F breWay, Longv ew F bfeCompany Longv ew Washngton 98632 Influenceof ForestAge on Densitiesof Cope'sand Pacific Giant Salamanders Abstract We suNeled flrst-order streamsin forcst sunds 0 94 )r old on industrial timberlandsin the CascedeNlountains of southcm Washingtonduring the summerof 1998and 1999 ro determinehow short-temrchangcs in lbrest age can rffect rhe abundanccof the \lream-bfeedingCope's and Pacilic giant salananders.Based on resultsfrom cross validatedregression trees, dcnsirics of both specieswere unrelatedto changcsin lbren rge or any othef habitatvariablc mcasured. There was also no differenccin any ofthe measuredhabitat variables bctwccn sreans in $ hich a species$'as present and strcamsin which it wasnot detected.Hou'c\,cr. dcnsiliesof the Pacific giant salamanderr crc ncgalively conelaled to pefcentof riparjan canopy cover in one of the vears. lntroduction old growth statusand are subjectto rcgular, in- tenslveharvest management. Thestream-breeding giant salamanden (DicdnpLr- don spp.) havereceiyed rruch attentionwith re- Many prcvious studies did not differentiate (D. spcctb their habitatassociations (Hawkins ct al. betweenCope's giant salamander copel) and (.D. 19U3,Corn and Bury 1989,Parker 1991, Wilkins Pacific giant salamander tertebrosus)when andPeterson 2000). Several studies correlated the examininghow this genusresponds to changes presenceof giant salamanderswith streamhabi- in tbrestage or other habitatvariables. It is often tat charactedsticssuch as high gradient riftles difficult to differentiatebetween Cope's giant (Hawkinset al. 1983.Com andBury 1989)and salamanderand larval Pacitic giant salamanders coarsc substrates(Parker 199l, Wilkins and in the field. and there is generally an unstated Peterson2000) or haveshown increasesof giant assumptionthat, despitedilferetces in molphol- salamande$in streamsrunning throughrecently ogy and lile history,the two speciesrespond simi clearcuttimber stands (Muryhy et al. 19ltl, Murphy larly to changesin environmental pammeters. andHall 1981,Hawkins et al. l9U3).Other stud- Cope'sgiant salamanderwas not distinguished ieshave concludedthat girnt salamandersare most trom larval Pacific giant salamandersuntil its oftenfound in ornear streamssurrounded by older descriptionin 1970(Nussbaum l970). Cope's giant .alamander ohligate forest stands(Corn and Bu[y 1989) or in stands is an neonare.remaining in that haveold growth charecteristicssuch as large an aquaticlarval stagethroughout its life. Meta- conifers(Gomez andAnthony 1996).This knowf moryhosedindividuals are lbund rarely.whercas edgeof old growth associationis valuable.how neotony is only occasionallyexhibited in some cver, little old growth exists today in National populationsof the Pacific giant salamander.Thc Forests or on private timberlands.Because the diIficultl oi Ji.tinguishingbel$ecn neotcni(' current rangesof theseamphibians occur panly Cope's giant salamandersand sympatric larval on industrial titnberlandsit is also impofiant to Pacific giant salamandersin the tield is likely study habitat associationsand populationdistri- preventingcomparative tield studieson thesetwo bution ofthese animalsin fbreststhat rffely reach species.Morphological diff'erencesbetween the speciesare slight. making field identificationdif- llcult.lt hasheen us.umed that the turr speeies respondsirnilarly to changesin streamsubstrate (Wilkins Aulhor 10 !rhom correspondenceshould be addrcssed. and Peterson2000), but it has not been Curren!addrcss:School of Biological Sciences.\Vashing!on determinedhow Cope'sgiant salamander responds Sratc Univcrsill. Puilmar. WA 9916,1-.1236.E mail: to chrnge.in lbrestage and whether their response. steele@ mail.\\'su.cdu are similar to thoseof Pacific giant salamanders. Northwest Science,Vol. 76, No. 4, 2002 31'1 (il00lb)_deNodhrcsSr'.ntili.A*ocilion A l.ighRreselrd This study, perfbrmed in areasof regenerat- commonly plantcdafter timberhan'est. Noble fir ing recondgrouth [ore.t'. intenJeJ li, e\rminc (Abies procer.t), western hemlock (Tsirga how the abundanceof Cope's giant salamander hetercphy-lLa). westem redcedar (Z/ruja p licatu), and sympatriclarval Pacitic giant salamandersare and red alder (A1,,rrisrrlrr.r) also contdbuteto the associatcdwith changesin forestage. This study o\ er\lor) al mosl.ite\. The underlt,r) I unrpri'es alsointended to examinestream habital associa huckleberriesl.Vaccittium spp.). devil's club tionsof cachspecies. (.Opk4tottu horridun), blackberries(Rlbns spp.), salal(Gouhheriu shallor). andwestern sword lem Methods ( PoI y.t t i ch um mtoi turn). The studytook placeon cor?oratetimberlands in We locatedull llr.l-order:.lrerm..u.inB mrl. southemSkami]uria County, Washington. between of the study area,across the mnge of forest ages ,15'46'b 45o38'Nlatirude and l22'l.+' to l2 l'53'w available.Ages of sufounding timber standswere longitudetFigure I t.Annurl prccipit:rtion occur. calculatedfrom the time of replanting.Stands < mostly asruins fiom Octobcr throughMarch and 70 yr had been clearcutup to the streambanks rangesfrom 229 to 305 cm (Daly et al. 1994). and replantedwith Douglas-fir seedlings.S|ands Geology ofthe arcais mostly basaltand andesite > 70 yr were rare and likely regeneratednatu- flows with their associatedbreccias and tulTs rally atier one of the rcgional fires. While timber (Franklinand Dymess 1988).Elevations range hanestwas rot theprimary disturbance fi)rstreams from 2,+0to 800 m. Thc rcgion experiencednine in theseoldest stands, t\\"o streams were sampled localizedsland-replacing fires between1902 and to provide additional data fronr older agcd lbr- 1952(Felt l9?7).The areais managedprimarily eststhat areuncommon on industrialtimberlands. lbr the production of wood pulp and small sau- Streamswith continuouspennanent flow were logs with evenaged silvicultureand 50-70 yr locatedin the field to confirm their presenceand rotations.Dominint vegetationvaries with har- to determineif they mct the selectioncriteda for vest management,but Douglas-flr (P.r"r.,i.rtrrg4 siunpling.Streams selected for samplingmeasured neirr:lesil)is usually the dominantconifer as it is (2 m wide, had a rnarimum depthof (15 cm, and A lN T 30 Km - Figure 1. Locadon of strcainssampled in SkamaniaCount]. \'ashinglon. 348 Steele,Brodie. and MacCracken had an unembeddedsubstrate that was visually aticallyplacing a squareframed dip net in the estimatedto comprisemorc than halfcobble and plot. removing all cover items. raking the sub glarel.The.e criterir en.ured thrl appropriirte stratetbr approximately0.5 m in fiont of the dip streamhabitat fo[ giant salamanders(i.e., unsilted net,and repeating the processwith the intention rocky substrates)was sampledin strcamsof a that all salamanderswould either be caught by manageablesize while mininizing vadation of hand or swept into the dip net. Periodically dur- physicalstream characte.istics. Because of thc ing the sample.the large net spanningthe stream high gradientand smallsizc of theseheadwater was searchedfor salamanders.Because large larvae streams,sampling was precludedin slow-u'ater will leavea streamduring intensive sampling, a habitatssuch as pools. runs, or glides.All streams l-m wide plot on the streambank on eitherside meetingthese criteria in the study area were of the slream was also intensively searchedfor sampled.Twenty-nine streamsthat met the se- amphibiansthat had either Ieft the streamduring lectioncriteria were survcycdin 1998.ln 1999 samplingor were associatedwith streamedges. thcsc samestreams were resampledalong with This l-m wide tenestdal plot was subjectedto a an additional four streams.AII streiuls were within \) .lemJli(al :'eJr(hin u hi,.h rll corer itctn. u crc 29 km ol eachothcr. tumed over and the substratewas raked. Cover Three plots in each strean were sampledbe- itenrswere replaccdin all plots at &e end of the tweenJune and Augustduring 1998and 1999. search. Selectionof plots within a streambegan 10 m Becauselarlae are often difficult to identify beloll, thc immcdiate headwaters(i.e.. wherethe to speciesin the field, it was necassffy to pre- headwatersfirst fomed a recognizablechannel). serve! l capturedlllrvae in fbrmalin forlater iden- Plotswere 2 m long,as wide as the wcttcd widlh. tification in the laboratory.Using criteria estab and scparatedliom each other by at least l0 m. Iishedby Nussbaum( 1970,1976). preserved lawae All plots were locatedupstream from roads.We were identified as cither Cope's or Pacilic giant measuredthese stream and riparian habitatchar- salamander.The Pacific giant salamandcr usually rcteristicsat eachplot bcforesampling for sala has6 7 gill rakerson the first and secondgill arches mandersbegan: water temperature. stleam depth, whileCope's giant salamander has 4-5. Also, thc width,gradicnt. aspect, elevation, and percent cover Pacific giant salamanderusually has 5-6 rakers of treesand tall shrubs.A singlemeasurement of on the tilih and sixth gill arches*hile Cope's sh'eamdepth for eachplot was obtainedby aver- gianthas 3-,1 (Nussbaum 1976). Gill rakerswere a-singnine depth measurementsto the neargst countedtbr each specimento determinethe centineter: depth of the thalweg (deepestchan- species. nel of the strean) at the middle. upstrcam,and Salamanderabundance and habitat dataofeach do\\'nstrcamedges olthe plot. and depthsat mid strcamwere averagedftom the threeplots to give points between each thalweg measurementand