Fraxinus Latifolia

Home , Fraxinus latifolia

Robert E. Frenkel, Deparlmentof Geography, OregonState Universty, Corval s Oregon97331 and Eric F. Heinitz,Lt, (i.9.), U.S CoastGuard, Marine Inspecton Otfice BaneryPark Building, New York,New York 10004

Compositionand Stru,ctureof OregonAsh (Fraxinuslatifolia) Forest in WilliamL. FinleyNational Wildlife Refuge, Oregon

Abstract Ve describetwo 0regon ash(Fruinus latifolia)plant conmuniiies ar William L. Finiey National Wildlife Refugein the central Willamette Valley shich differ in habitar, composition,and structur€.The Ft*inus latifolie/Care' olazprd community type, rirh many young tr€es(arerage core age 59 years)of snall diameter(average l4 cm dbh), has an open understory of scattered C. olnapra patchesand occupiesmoist overflowsites. The nore florisrically rich Fruinus latiftlia./Synphoricarposolbus com nunity type, with large dianete. (average20 cn dbh) and older trees(averase core age 72 )ears),has a rhick shrub understo.y and occupiesbetier drained, but still noist, sites.Both forest comnunity types are young; hoverer, $e C. obnupla conf':rniry has rec€ntly expanded into forner ser prairie with cessationof aboriginal burning and hisloric grazing. lntroduction anaerobicconditions may occur assuggested by gleyingin soil profiles.A brief droughtperiod Oregon ash (Fraxinus latifulia Benth.) ranges ensuesduring the summermonths when soils from northern Washington to the San Bernar, may desiccatefor short periods;bur, exrensrve dino Mountains,California. Forests dominated droughtis not present. by Oregonash are particularly well developedin the interiorvalleys of westernOregon where the Soils of central Willamette Y alleyFrarinus forests are most commonly grouped in the speciesoccupies riparian strips and adjacent Waldo-Bashawassociation, poorly poorlydrained bottom lands.Associated moist drainedsilty clay loams and clays. The principal soil series site trees are lcer macrophyllum,Alnus rubra, related forests Populustrichocarpa, and Salir spp.,while l6ies to the Refugeash is Bashawsilty clay, a deep, poorly drained soil with mont- grandis, Pseudotsugamenziesii, and Quercus morilloniteclays classified as a Typic Pelloxerert. garryana maybe presenton drier sites(Franklin The black,hear,1, silty clay loam surfacelayer and Dyrness1973,Owston in press).Although reachesdepths of between25 and 40 cm. seldomextensive, Fratin&s forestsare prominent Underlyinghorizons are black to verydark gray landscapefeatures, providing a major forestcom- with a layerof silty clayabove clay. When wet, ponent to riparian habitat and benefitting fish, the soil becomesvery stickyand plastic.Upon wildlife,and recreationalresources (Frenkel et drying it cracks and becomes very hard ol l9B5),Surprisingly, characteristics of these (Knezevich1975). forestshave not previouslybeen exarnined. Oneof the bestexamples of Oregonash forest A rnodifiedmaritime climateprevails over the is in William L. Finley NationalWildlife Refuge, WillametteValley with wet, mild wintersand l6 km southof Corvallisin the centralWillamette narm, relativelydry summers,and a slightrain Valley. where Frorinus span. a strip appror- shadoweffect. Representativeclimatic data, imately400 m wideadjacent to Muddy Creekand following the standardizedsystem of Walter and Gray Creek and nearby shallowswales and Lieth (1967),are summarizedin Figure I for overflow lands (Figure 2). The trees are thickly HyslopAgronomy Farrn, Corvallis. Based on pre- draped by foliose lichens Eaerniaprunastri (L.) cipitation and temperaturecriteria, surplus Ach..Ranalina menziesii Tayl.. ( snpacptutina moistureoccurs from Septemberto June. In Ach., and U, sublloridana reflecting moist at- riparianand bottom land habitatstypically oc- mosphericconditions. crpietJ.hy Fraxinus, this surplus is accentuated Vegetationin the Refugeis typicalof the in- by seasonalflooding from Decemberto April and terior valleysof westernOregon (Franklin and by high watertables in earlysummer. Potential Dyrness 1973); several physiognomictypes

NorthwestScience. Vol. 61. No. 4. 1987 203 cORVALLIS (69m) 12.5' 1024 mm fsol 200 [rean monthly precrpIalron 100 > 10Omm

PeriodoJ 80 relat iv e morstu re .9 = Periodof .g relativ e drou ght 40 0 Mean monthly E precrprraron

Mean monthly temperature

Month

FigureL Clinograph{or HyslopAgronomy tarm, Corvallis,0regon,following the standardizedWalter and Lierh sysren. mappedbv Exler(1982) are generalized in Figure The Frainus latifolia forest is transitionalin 2. Oak woodland,dominated by Quercusgar moisturestatus between oak woodlandand wet ryana, has been describedand classifiedby prairie. Prior to earh settlement,-FrzLainas forests Thilenius(1968) and is the closestof thesetypes fringed almostall watercourses in the Willamette in structureand compositionto the ashforest. Vallev.The GeneralLands 0ffice townshipand Thileniusidentified four oak communitvtypes rangesurvey conducted in the Refugearea in in the interiorvallevs of westernOregon vhich, 1853,documents a 100m widestrip of Frat:inus in orderof increasingmoisture, are: RAas dioer- forestalong Muddy Creek. Survey notes and plat siloba; Amelanchier alnifolia/Symphori.carpos mapsare availableand were examinedat the albus;Prunus ad.um/Symphoricarposalbus; and OregonState Office of the Bureauof LandMan- Corylus cornuta var. californica"/Polystichum agement.Additionally, historic accounts of the munitum.All are regardedas seraland occupy Refugearea and old aerialand groundphoto- well drainedslopes and ridges. graphsshow many of the presentstands more Wet prairie, maintainedas grasslandby limitedin extentthan present. Aboriginal burn- historicfire and grazing,is alsoconsidered seral, ing apparentlykept I'ra:tinusfrom expandingin- b:ur to Fratinus forest (Moir and Mika 1972, to prairie(Habeck 1961, Johannessen et al 1971, Franklinand Dyrnessl9?3, Towle 1982,Marshall Towle 1982).In the late-l9th century,inrense l9B5).These heavily disturbed prairies, dr.rmi- grazingby livestockreplaced fire asa dominant nated by Deschampsia caespitosa,Hordeum influencein the Refugearea (Tovle 1982).Cradu. brachlantherumancl Carex spp.. conlain man) ally, grazing intensitydiminished and, in the alien speciesand bear little structuralresem- early 1960's,ceased altogether (personal com- blanceto ash forest. municationJohn Cornely,Refuge Biologist).

204 Frenkeland Heinitz Figure2. Vegetationof W. L. Finler NationalWildlife Refusegeneralized after Exler(1982) and locationin Oreson.

Uncheckedby fire and cattle,ash invaded prairie, the structureand compositionof ,I'nulnzs forests settingthe stagefor the presentvegetation. in the FinleyRefuge? (2) How does the distribu- The questionsaddressed in this paper are tion oI Frarina.forest. relale lo the moisture basedon the aboverelationships: (l) What are gradient?(3) What is the relationshipbetween

Compositionand Structureof OregonAsh Forest 205 lcroriaas forests anrJ Quercus forests? (4) How ing a Bray'Curtisdissimilarity measure and a doesthe presentdistribution reflect historic prac- flexiblcfusion slratcgy, B - 0.25(Bocsch l9?7, tices of burning and grazing? Kenistonl97B); and TWINSPAN,an rteratrve polytheticdivisive technique based on reciprocal METHODS avcraging(Hill 1979a).Additionally, we analyzed floristicdata with DECORANA,an ordination gain To familiarity with the range in composr- achicvedby dctrcndedcorrcspondence analysis general tion and structure of ash forests, a survev (Hill 1979b).Within-communit,v similarity was was of Fraxinus forest distribution first con- determinedby an abundance'weightedsimilar- ducted throughout the Willamette Valley. In ity ratio (Maarcl et al. l9i8). 1982,l9 standswere selectedin the W. L. Finley National Wildlife Refuge basedon their relative Speciesdiversit,v was analyzed by PRHILL, homogeneityin habitat, composition,srrucrure, an unpublishedcomputer program developed by jackknife and adequacy of stand size. Becauseof its ac- B. C. Smithlhal caiculale. estimates cessibilityand extent, one additional stand was of M. O. Hill's diversit,rnumbers (Hill l9?3, located at The Nature Conservancy Cogswell- Alatalo1981, Heltsche and Forrester1983) for Foster Preservc,l9 km southeastof the Refuge. eachcommunilv typc. By simulation,Heltsche and Forrester have shown that jackknife Circular, 12.6m radius macroplotsof500 m'? estimatesof diversitvpermit comparison of com. werelocated randomly within sclectedstands, one munitiesunder a widevariety of plot sizes.Four macroplot per stand, and the following data measuresof diversity are displayed:mean recorded for livc and dead lrecs: total percent numberof speciesper macroplot;expected total canopy coveri percent canopYcover by species; numberof speciesin a communitytype (No); in- diameter at breast height (dbh) of all trees by verseof Simpson'sdiversity index (NJ; and M. "reproductive" species)5 cm dbh; number of O. Hill's evennessratio (N:/N'). per (stems (5 stems macroplot cm dbh)l number Tree diameterdata weregrouped in 5 cm and dbh of downed dcad wood >5 cm dbh; vigor diameter classesand plotted by frequcncy (vigorous, class impaired, dead);and height and histogramsfor eachmacroplot and subsequent- increment core-ageof two-to-fourof the largest ly aggregatedby communitytype. Basal area and in macroplot. Core.ages diameter ash trees each densitywere determined from measuredtrees in were dcterrnincdin the field with the aid of hand eachplot. An age-sizerelationship, calculated lens. Onl,v in a few caseswerc multiple cores from 60 trees,was used to characterizethe age talFn from lh. samelree. Underotorr',"omp".i. structureof plantcommunity t,vpes. A varietyof tion was recorded from 12, one m' microplots averagecommunity characteristics nere assessed placed at four, seven, and ten mctcr intervals !.ithStud"nr's t-teil in $hi.h.ignifi.anc'r'as in directions along four transects set cardinal judged at p =0.05. within the macroplot. Cover was cslimated for (1959) eachspecies by Daubenmire canopycover RESULTS classes. Taxonomy and nomcnclature follow Hitchcockand Cronquist(19?3). We use the term P ant Communites 'community'to define a general assemblagcof 'communitl The Frainus Latlfulia/Carexobnupta and the plants and t,vpe'or'type'for the Frainus latifuliofSymphortcarpos albus com- abstract classificator_'-unit comparable to the munity typesare identifiedbased on floristic plant association. classification(Table 1 and Figure3). Both com- Prior to anailsis, mean percent cover lvas munity typesshow a relativelylow levelof within- transformed to octave valucs (Cauch l9B2). community similarity, averaging6l percent Floristic data were used to classify macroplots (Table2). This heterogeneityis further demon- into communitv tvpes with the aid of several stratedbJ spread'outplot distributionin thc or- multivariate programs including: TAB0RD, dination(Figure 4), thc typesbeing distinguished rvhich structures phytosociologicaldata in the moreby differencesin speciesabundance than form of an association table based on sample by speciespresence-absence. Since classifications similarity (Maarcl et al. l97B); CLUSTER, a basedon TAB0RD andCLUSTER were in close pol-ytheticagglomerative clustering program us' agreement,onlv the CLUSTERclassification is

206 Frenkeland Heinitz TABLE 1. Percent constanc-rand mean per.enr cove. in Ir@inus lattfolid comnunity tvpes. only speciessith at least two percenr.or.r i. a communirJ rype are inctuded-

Comnunit,- Iype Fn'itus lattfolial Symphoricarposalbus ("=s) {n= ) Slratum and Species consl./meancov.

TREES 100a4 t00/80 27i 6 SHRUBS CrdtdcCusdousLasii 56iT 2it 1 41t 2 36t 2 33/T 91t22 331T 646 Synpltar atpos albus tT 82126 Lani.erd in,^olu.rata l8/ 3 HERBS 89i36 45/10 CaLiunt.ilidun 89t 2 64i 4 ?8i 1 73i10 Eleacttotis a.icutars 6it 1 55/2 Ranunculus uncinotus 6it 2 l00i 'l Stelloria calycantha 56iT 82t 4 0enanthe sarmentosa 33'l2 2713 33/4 4511 33/ 3 45/ 8 33i 2 l8iT Iteronica scutellata 33iT 'St 2 22iT 6,11t4 Te ina srandilora 22iT 5511 22iT 22iT 9t 2 Ceun nacrophyLlun lli T 82i 3 l1iT 6415 lliT 6,! 4 Pobsti.un nunitum 55i ,1 P. ri.lc ri.lia saidne ri 55i 3

TABLE 2- Selected fioristic chafacteristics ol FtuainLs LdtifoLia communitr tvoes.a

CornnrunityType s,ymphoticdrposatbus (n=e) (n=ll)

Within.ConmunitySimilaril' (%) 66.1 56.8 NteanNo. Speciesper Macroplot t3.7 22.5 Total No. SpeciesExpected in Type (NJ 50.8 66.9 s.e.= 3.2 Inverseof Sinpson'sDiversit) Index (N,) tl.7 32.9

Erennss rnder q! 0.525 0.743 (N,)

"Within community similaritv is based on an abundance-weighiedsimilariiy fatio (Maarel e, dl. 1978).Diversiry indexes are based on PRHILL Gee nethods).

Compositionand Structureof OregonAsh Forest 207 conspicuous,averaging 23 percent of the plot area (Table 3). Speciesrichness is lower than in the Symphoricarpos albus type, averaging 13.7 speciesper macroplot (Table 2). The jackknife estimateof communitv richness,or total number E of speciesexpected in a community type, is 50.8 speciesand is lessthan in the S. ol6zs type. The inverse of Simpson's diversity index is 14.?and evennessindex is 0.525 suggestinga relatively simple community with high dominanceby a few sper"ie..The Fraxina"orer.lor) canop\ i! commonly closed, reducing summer insolation at ground level. Although no measurementswere Figxre 3. Ctusrerdendrograrn based on CLUSTER(Keniston made, we observed extended periods of spring l9?8) usirg rbe Brar Curtis dissimilarilyildex and flooding, depressedtopography, and soils with flexibleclustering stratega, B= 0.25. high clay contentand low permeability.This community type is usuall,vsituated awav from main waler courses in overflow lands. The F ratinus latifu lio./Symphoricarpos albus community t_vpehas a prominent shrub cover (Tables I and 3) with Symphoricarpos aLbus, Rubus ursinus, and Rosa eglanteria having high constanc]and or cover(Table I). Chara"t"ri'ti. herbs with high constancy or cover include i Ranunculus uncinatus, Stellaria calycantha, Montia sibirica, anil Galium aparine (Table l), Quercus garryana occurs in three plots as a codominant.The S. o16ascommunity type, with a within-type similarity of 57 percent (Table 2), is lessfloristicall,v homogeneous than the C. o6- nupta rype (within-type similarity 66%). Mean speciesrichness per macroplot is 22.5 species. Zt A jackknife community richnessestimate of 66.9 speciessuggests a richer type than the C o6' Figure4. Detrendedcorrerpondence analysis ordination of napta type and the inverseof Simpson's diversi- \L L. Finley National Sildlife Refuge -Fra:iaus tv index of 32.9 and an evennessindex of 0.737 lat{olio macroplots.CLLSTER and lABORD com. indicates that dominance is shared by several by sj"mbol. nunity dassificationis sLiperimposed 'pe.ie' and thprr i. more erennes.in sperie" abundance than in the C. obnupta community. displayed.Several floristically different macro' The 5. al6as communitv, with a more open plotswere classified differently by TWINSPAN canopy and less flooding than the C. obnupta nhencompared to the TABORDand CLUSTER community, has a mean bare ground cover per classifications. plot of 2 percent (Table 3). The S. al6zs com- The Irorinas LatifoLia/Carerobnupta community often occupiesnatural leveesadjacent to munitytype is markedby low shrubcover (3%) streams and margins of the ash forest where it andhigh coverand constancy of Corcrobnupta. abuts agricultural fields. Both locations are Other common speciesinclude C. deaeyana, associatedwith somewhatcoarser teltured soils. ELeocharisacicularis, and Calium trifdum (Tahle -Frarinzs forest plots are ordinated by l\, Carexobnupta typically grows in densepatch. detrended correspondenceanalysis (DCA) yield. es rangingin size from one to severalsquare ing four eigenvalues (0.34, 0.1?, 0.09, 0.05). metersand exhibitstotal macroplotcover often The principal two ordination axesare displayed in excessof 60 percent.Bare groundis usually in Figure 4 together with the superimposed

208 Frenkeland Heinitz TABLE 3- Selected structural characteristics of Fratinus ldrt/oltd planr communil) rypes.

Srntphornarpos ntbus Chara.teristi. (n=e) (n=1l)

]{ean Toral l rec Core. (9/,) 83.9 i9.1 1.66 Mean Total Shrul Covcr (qo) 3.1 70.5 4.01 Mean Bare Cround (%) 22.6 2.q 3.51 Mran l,ixcr (%) 53.8 6 t'.9 l_80 Nean No. Down Dead Trees (ha ') 218 136 Ilean Dens. Total Trees (ba') 2146 t358 3.46 Mean Dens. Live Trees (ha-1) ta24 1012 3..1,1 Mean Dens. Vigorous Trees (ha') t484 818 3.l9 Mean Dens. DvingrDead Trees (ha') 962 5lI 3.01 trlean Dens. Stand. Dead Irees (ha ') 626 346 2.38 MeaD Dens. Reprod. Sten,s (ha-') 22i4 s54 2.98 Mean Srem Diameter (cm) 14.I 19.t- 1.96 trlean Stand Basal Area (m'ba'') 32.2 31.4 0.25 Ilean tro:trus Core Age ()rs) 59.3 i2.2 3.52 a' indicares!ienificance at p=0.05

TAB0RD and CLUSTER community classifica. tion. Lacking quantitative environmental measurementsJit is difficult to interpret these ares.Plols in the Caretobnupta.ommunity lJpc are on the left of the ordination and S'larpioricar pos community type plots on the right. The prin- cipalaxi" IDCA axis l) mal indicateper.istenr"e of moisture. Symphoricarpos dl6&s stands are associatedwith drier and more coarsetextured soils characteristicof natural leveesand gently sloping margins of bottomlands.Figure 5 shows 0 so 100 150 20o 25o (r.0.53. a relativelrr.eak po.itive relation DCAAxsl Score p - 0.020)between ash core-ageand DCA axis I score,suggcsting corrcspondcnce between older Figure 5. Relation betreen detrended correspondenceanal. ash stands and assumed drier sites. ysis ordination principal aris score (DCA Aris 1) nnd core age of largesl Fro:irzs rrees rn each Structure macroplot. Thr' trno, ommunit]lyp"s ar. di.linct in trec communities(about 6l:13:26 respectively),there diameter,density, number of "reproductive are more standing dead and dovn trees in the stems,"and sizestructure (Table 3 and Figure Core.r type than in the Symphoricarpos type.The 6). The Frarinus Latifulio./Carer(,bnupta com- Corel plots also have a large number of reproduc- munitytype exhibits many trees less than l5 cm tive stems (a mean of 2274 stems ha-'). dbh, few treesgreater than 30 cm dbh, and a The ll plots allocated to the Fraxinus moderatenumber of standingdead trees 5-15 cm latilolia SynphorirarpoJ d16us,ommunity tlpc. dbh.This structuralpattcrn is shownin Figure on the other hand, exhibit a more even distribu- 6 aggregatedfor all nine Cai,e,community type tion of stem diameters, fewer trees with diameters plots. Mean total tree density is 2446 ha'. lessthan 5 cm dbh, a larger number of trees ex- Althoughthe proportionofvigorous to impaired ceeding 30 cm dbh (Figure 6), a slightly more to deadtrees remains about the samein the two open canopy,and a fewer standing impaired and

Composition and Structure of Oregon Ash Forest 209 communitieswith a meancore age of 59.3years for the oldestash trees, are significantly younger than the Symploricdrposcommunities with a meancore age of at least72.2 years. Because of the difficultyin agingtrees older than 100years, the relationshipspresented above are conserva' tive;in otherwords, the distinctionbased on age betweencommunity types is at leastas greatas presented. Discussion a € Thevegetation mosaic in the WillametteValley, consistingof prairie, deciduousforest, and 5 evergreenforest, has been heavily modified by rian, both histo call,vand presently(Johannessen et al. 1971,Towle l9B2).Published studies of theset\pes are fern and their chara,"leri.tic.. en. vironmentaland successionalrelationships are onlyprovisionally known (Franklin and Dyrness 1973).Both temporaland environmentalgra- dientsare evident.Temporally, wet prauresuc- ceedsto deciduousFraxinus foresl on poorly drainedmoist sites (Moir and Mika 1972,Mar- shall1985). Furthermore, following disturbance, Figure 6. Tree size distribution in lirdrlnes latiftlidCaret prairie, obnupta atd Fratinus htifulia.lSymphoricarpos dry sites are occupiedserally by dry albzsplant communitx types. Asterisl (')indicates deciduous Quercus garryana forest, and ulti- significantl)different (p=0.05) size crass between mately by Pseudotsuga menziesii foresl-a the t{o communities. somewhatindeterminant successional sequence (Spragueand Hansen1946, Franklin and Dyrness deadtrees than are presentin the C, obnupta 1973).Environmentally, a moisture gradient may communitytype (Table 3). A total densityof l35B alsobe recognizedin which the sequencewrth ha I is significantlyless than the densityof the decreasingmoisture is marsh,wet prairie, Frar- C. obnuptacommunity. Although the two com- inas forest, Qzerczs forest (Boss 1983, Moir and muniticsare structurall)distinct. communit) Mika 1972,Thilenius 1968). In the Willamette basalarea, reflecting both diameterand densi- Valley,ash forest appears to havea terminalposi- gradient posi- ty, is not significantly different, 32.2 m2 ha- l tion alongthe seral and a central for the Carex and 31.4 rn2 ha-l for the tion alongthe moisturegradient. Our studyof Slmphoricarpos community. the compositionand structure of Frarinus latifulia forest in the Finley Refugerelates this Coring ashtrees is extremelydifficult because moist foresttype to thesetwo gradients. of the toughnessof thewood; furthermore, trees With respectto the moisturegradient, cen- older than 100 years frequently had rotted tral Willamette Valley ash communitiesare as- centersand couldnot be aged.Because of these sumedto respondto differencesin inundationand problems,only two-to-fourof the largest,and drainage.Of the two identifiedcommunity types, presumablyoldest, ash trees in eachplot were the Carer obnuptatype occupiespoorly drained cored.Age samplingnas not representativeof bottom lands, is dense,and exhibits strong the total forestage structure.A weakpositive dorninanceby smalldiameter and relativelyyoung relationexists between age and diameterfor all Frotinus tees. The Symphori,carposol6as type plots(r=0.49, p-0.000). There is a somewhat is found on natural leveesand gentleslopes adja- strongerage-diameter relationship for the Corer cent to overflow areas, is more open, and is plots (r=0.60, p=0.0000) than for the Sym- dominatedby largerand olderFrcrinas lrees phoricarposplots (r =0.4?, p = 0.010).The Carer than in the Carer lNpe.Lower species diversity

210 Frenkeland Heinitz and higher dominance in the Corentype than in diameterwoody debris, indicates greater stand the Symphoricarpos type agrees with observa- agebut still stabilityin dominance,since arar- tions that overflow areashave greater anaerobic inzs continuesto dominateboth reproduction conditions leading to stressed vascular plants and overstorycanopy. (Lee et al. 1985). As recentlyas 70 yearsago, the ashforest in Compositionallv.the Frarinus community the Refugearea was limited to the immediate types were heterogeneous and shared many riparianstrip of Muddyand Gray Greek. In com- species.These types occupv habitats intermediate bination, burning and grazing historically in moisture status between clrier Quercus gar restrictedthe ash forest to a narrow riparian ryana forest sites (Thilenius 1968) and more forestalong natural levees within which Quer- hvdric wet prairie and palustrine marsh sites cus garryana also flourished(Habeck 1961, (Moir and Mika 1972,Marshall 1985,Boss 1983). Johannessenet ol. I97l). The Frurinus Lat{olial Understorycomposition of the more mesicQaer- Symphoricarposalbus type along the Muddy cusgarryana communities shows some, but not Creektoday represents historic continuity with close,resemblance to lhe Symphoricarposalbus the earlierforested riparian strip. The present communitv type. The lack of similarity is prob- Carer communitytype, representing more recent ably becausea full range of intermediate stands encroachmentinto prairie,does not appearto betweenthose examined by Thilenius (1968)and havethis historiccontinuity. those reported upon here were nol sampled. Floristicand structuralanalysis of Fru.xinus Likewise, ash stands share many species with latifulia forest in William L. Finley National nearby rvet prairies, irLduding Spiraea clougLasii, Wildlife Refugesheds light on history of the ash Crataegus douglasii, Rosa eglanteria, ELeocharis forestin the centralWillamette Valley and its posi- acicular;s, arrd Carer unilate ralts. tion with respectto temporaland environmental With respect to a seral gradient, ash forest gradients.The present extensiveash forest on appears to have a terminal position. Fraxinus moist sites in the Refugearea is a relativelyre- latlfulia is the major reproducing tree in each cent feature resulting from successionfollowing community. A dioecious species,L latifulia is a the cessationof burningand grazing. prolific seederin open standsbut reproductive- ly more limited in closedstands. Stump sprouts Acknowledgments are common, especiall-vwhere stems have been We wishto thankPalmer Sekora, Refuge Com- damaged(Owston in press).Ash is recognizedas plex Manager,and John Cornely,Biologist at intolerant to moderately tolerant of shade, yet Williarn L. Finley National Wildlife Refuge,for the distribution of Frainus throughout all size their logisticassistance throughout this project. classesin both community types suggests a multi- SherryPittman identified lichen specimens for ple age canopy with self replacement.Detailed whichwe aregrateful. Particular thanks are ex- age structure, however,was not examined. The tendedto BradleyG. Smith who providedpro- relatively young age and high densitv of the ,I'rat- gram PRHILL for an analysisof diversityand inut latifolia/Car.xobnapla communitl lrpe sug- many goodsuggestions for the paper.We also gests recent occupancy of the sites. There was appreciatereadings by Diana Bodker and no evidence of cut stumps or rotting logs. The CharlesHalpern. We areespecially thankful for more open and older Symphoricarposlrpe,uith many constructiveand helpful suggestionsfrom severalash treesin excessof 100years and large two anonymousand very dedicatedrevlewers.

LiteratureCited Bo*. T. R. 1o83.\-Fs, ldtron F. ulupl drd nerpriTdr\ pro. ductivity of selecledf.eshwarer wetlands in 0regon. Oregon Alatalo,R. V. 1981.Problems in the measurementof even- StatcUniversi,l*, Conallis. Ph.D.Dissertation. Daubennire,R. F. 1959.,{canopy-coverage nerhod ofvegera. nessin ecologl.0ikos 37:199-204. tion analysis.Norths. Sci. 33:43-66. Boesch,D. F. 197?.Application of nune.ical classification Erler, R. 1982.Willian L. Finler National Wildlife Refuse in ecologicalinvesligations ofwater pollution.Virg. Vegelalion.A colormap designedbr the Cartographic Inst. NlarineSci. Spec. Sci. Rcp. ?7.EPA, Environ. Scrrice, Dept. Geogr., Oregon State Universitl, Res.Center, Corvallis, Oreson. Conallis.

Compositionand Structureof 0regon Ash Forest 211 Franklin,J. F., and C. T. Dyrness.1973. Narural regetation Keniston,J. A. 19?8.Progran CLUSTER:an aid to numerical of 0reson and Sashington.USDA For. Serv.Gen. classificarionusing the CDCCYBER computer. Un Tech. Rep. PNW 8, Pacific Northn. for. Rarge Exp. publishedreport. I'leuroncctid Proj. Tech.Rep.2, Sta.,Portland, Orcgon. OregonState University Sea Crant Progr., Corvallis. Knezevich,C. ,{. l9?5.Soil Survey of BentonCounty Area, Frenkel,R. E., S. N. Wickranaratne. and E. F. HeiDitz.1985. Oregon.USD,{ Soil Cons.Serv., Washingron, D.C. Vegetalionand Land Corer Changein the Willamette Lee,L. C., T. M. Hinckley,and tr{. L. Scon. 1985.Plart warer River in Benton Creen*ay andLinn Counties,0regon: statusrelationships among major floodplain sites of 1972-1981.Yearbook Asoc. PacificCoasr Ceogr. lhe FlatheadRiver, !lontana. setlands 5:1534- 46:63.77. Nlaarel,E. !an der,J. G. Nl.Janssen, and J. IL W. Louppen. Cauch,H. C., Jr. 1982.Multrariatc Analrsis in Communiti 1978. TAB0RD, a proeram for strucruring Ecologl. Cambridge Unirersity Press,Cambridge. phytosociologicaltables. Vegetatio 83:143'156. Habect, J. R. i961. The original legetationof the nid- Marshall,J. L. 1985.Value assessmentof JacksonFrazier Willanette \rallev, Oregon. Northw. Sci. 35:65?7. Wetland.Oregon State Lnirersity, Corrallis. M.S. Thesis. Heltsche,J. F.,and N. E. Forrest€..1983. Eslinaring species Nloir, W., and P. !1ika. l9?2. Prairie vegerarioDof the richnessusing the jackknileproccdure. Bionerrics WillametreValle), Benton County, Oregon.Ln 39:1-11. O publishedreport on file at USDA For. Serr. Foresrv Hili, M. O. l9?3. Diversig and e!enne$: a uni{ying nota- Sci. Latr.,Corvallis, 0regon. tion and its consequences.Ecol.54:421.432. 0wston, P. W. In press. ole.rceae,.,live family, a/art,zs . 1979a.TWINSP,{N a FORTMN progran for lalr,roliaBenth.,0regon alh. Editorial draft for Silrics ar.angingnultiya.istc data in an orderedl{o-wav Manualon file at the USDAFor. Serr.Forestrr Sci. tableby classificationofthe ind'v'dualsand aitributes. Lab.,CorvalJis, 0regon. Ecol.and Systematics,Comell University, Irhaca, New Thilenius, J. F. 1968.The Quercussarryaaa fatesis ol ie WillametteVailey, 0regon. Ecol. 49:1124.1133. Towle,J. C. 1982.Changing geography c,f Willamette Vallev 1979b.DEC0RANA-a F0R fRAN program voodland.0regon Hist. Qudrr.83:66-87. for detrendedcorrespondence analysis and reciprocal Sprague,F. L. and H. P. Hansen.19'16. forest succession averasing. Ecol. and Syslemarics,Cornell Univerei- in the McDonald lorest, Villamette Valley, Oregon ty, Irhaca,New York. locality. t\-orth{. Sci. 20:89.98. Hitchcock,C. L., and A. S. Cronquist.1973. Flora of rhe Valter, H., and H. Lielh. 1967.Klimadiagramm-Weltatias. Pacific Northwesl. University of Washington Press, VEB CustavFischer Verlag, Jena. Seattle. Johannesen,C. L., W. A. Davenport,,{. Nlillet,and S. !lcVilliams. 19?1.The vegetationofthe WilJanette Vatley.Ann. Assoc.,{mer. Geogr.6l:286"302.

Receiued, 2l Notember 1986 Acceptedfor publication8 July 1987

2I2 Frenkeland Heinitz