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Contributions A Transient Soil Seed Bank for the Yam-daisy Microseris scapigera Ian D. Lunt1 Abstract An experiment was undertaken to assess the longevity of Microseris scapigera seeds in the soil. Seeds were buried in small bags of nylon mesh in a long ungra/ed and long-unburnt Themeda grassland in Canberra. Keplieale seed bags were unearthed alter 3, X and 12 months. M. scapigera was found to have a transient soil seedbank, since virtually all seeds germinated rapidly, and no viable seeds persisted for longerthan 3 months. The implications ofthese results for the eonscrva- lion management ol M. scapigera in remnant grasslands are discussed. {Ttu Victorian Naturalist 113 (I) 1996, IS 19) Introduction enables a population to re-establish after Two centuries ago, Yam-daisies dig. mature plants are killed (e.g. by fire or I), or Murnong (Microseris scapigera), grazing). By contrast, if all seeds germi- were abundant across the grassy plains of nate quickly, the population cannot recov- SOUth-eastertl Australia, providing a nutri- er if all existing plants die before flower- tious food supply for many Aboriginal ing, unless new seeds migrate intothe site. tribes (Ciott I983). One European settler reported 'millions of murnong or yam, all Methods over the plain', and the wheels of KM. Microseris scapigera seeds (propagules (nil's dray 'used to turn them up by the of Microseris scapigera are technically bushel' (Gott 1983). called 'achenes', but are here called However, Yam-daisies proved extreme 'seeds' lor simplicity) were collected in ly palatable to sheep and rabbits November 1993 from a remnant Thanccla (Fan inglon and Mitchell 1966; grassland in Canberra, ACT. They were Cunningham et al. 1981; Ciott 1983), as dried and stored indoors until early 1994, noted by Cum 'several thousand sheep not when they were placed in bags of fine only learnt to root up these vegetables nylon mesh (mesh size 0.85 mm x 0.95 [murnong] with their noses, but they for mm). Twenty filled seeds were placed in the most part lived on them lor the first each bag, and broken and unfilled seeds year, after which the root began to gel scarce' (Curr IXX6, inGotl 1983). Microserisscapigera is now uncommon to rare in lowland grasslands and grassy woodlands, and most large grassland pop illations occur in ungra/cd remnants on roadsides, rail lines ami cemeteries (Prober and Thick- 1993; McDougall and Kirkpatrick 1994). Fortunately, the species remains common in other, less disturbed ecosystems, such as dry sclerophyll forests. Recently, as part ofa largerexper- iment with ten grassland species, I invesli gated the longevity ofM, scapigera seeds m the soil. Seed longevity is a critical fac- tor in plant ecology, as long-lived seeds can form a buried seed bank, which 'School ol Botany, L»Trobe University, Bundoora Fig. l. Microseris scapigera (Photograph Victorid J083, courtesyofJames Ross). 16 The Victorian Naturalist Contributions lwwaeenrrdeeidnbiustrchiaeerMddaedji.nurOaancVl2aol7sleMedyaynTehx1et9m9te4o,dCatahnegbrebarasgrssa- epwereterrdiedbaifrstohe.wrnAeiingfsheitwdeaianntndadct1o2bsvemieoodunsstlwhyesr,ienvbiruaetbcloaevl.-l Airport. Microseris scapigera germination was The study site supportedalong-unburnt not inhibited by a dense grass cover or and long-ungrazed natural grassland with extremely low soil moisture levels. In a dense, closed canopy of Themeda trian- August 1994, when the first seeds were dra. Associated species includedAsperula unearthed, the topsoil was completely dry conferta, Desmodium various, Eragrostis and dusty, and few seeds of the other trachycarpa, Flantago varia, Tricoryne species studied had germinated (Lunt. elatior and the exotic herbs, Conyza unpubl.). Drought conditions persisted species, Hypochoeris radicata and throughout 1994, and there seems little Tragopogon porrifolius. The soil was a doubt that all M. scapigera seedlings dark brown, silty clay loam ofpH 6.1 (S. wouldhaveperished. Sharp 1995,pers. comm.). Weathercondi- Little information is available on seed tions during most of the experiment were persistence in Australian grassland herbs. extremely dry, as the region was experi- M. scapigera was the only species, of the encingaseveredrought. ten studied in Canberra, for which no The bags were arranged (with more seeds remained viable after a year in the bags containing seeds ofother species) at soil (Lunt, unpubl.). At least 20% of the regularintervals on agrid measuring 19 m seeds of each of the other species x 19.5 m. Half of the seed bags were remained viable after 12 months. Indeed, pinned to the soil surface, beneath the more than 70% of Vittadinia muelleri closed grass canopy, and the other half seeds, and over 80% of surface seeds of were buried approximately 1 cm deep. Brizamaxima remained viableaftera year Eight surface and eight buried bags were in the field (Lunt, unpubl.). Seeds of the unearthed after approximately 3, 8 and 12 grassland daisies, Chiysocephalum apicu- months. In total, 160 buried and 160 sur- latum and Leucochrysum albicans, can faceseeds were unearthedateachdate. remain viable inthe soil forat least a year (Gilfedder and Kirkpatrick 1993; Lunt Resultsand discussion 1995), whereas most seeds ofspeciessuch Virtually all M. scapigera seeds germi- as Burchardia umbellata, Craspedia vari- nated rapidly, and no viable seeds persist- abilis and Rutidosis leptorrhynchoides ed for longer than 3 months (Table 1). rapidly germinate in native grasslands, Two intact and visually healthy seeds with few seeds remaining viable after 6 wererecovered at 3 months (Table 1), but months (Lunt 1995; Morgan 1995). Like theirviability remains questionable as nei- M. scapigera, R. leptorrhynchoides has ther could be induced to germinate in a declined dramatically in abundance since Europeansettlemeni. Table1.PercentageofMicroserisscapigera froTmhesedeadtsafprroemseonnteedpohpeurleatwieorne, gorbtoawinneadt seedsremainingviableaftervariousperiodsin one place injust one year, and it remains thesoil. tobe seen whetherseeds from otherpapu- Date Event Surface Buried lations behave similarly. The grassland seeds seeds habitat at Canberra is structurally similar 27May seedssown 100.00 100.00 to any unburntand ungraded grasslands in 1994 south-east Australia (e.g. Lunt 1990; 29August firstrecovery 1.00 0.00 McDougall and Kirkpatrick 1994). 1994 (3months) Microseris scapigera is a variable species 11999J5anuary sec(o8nmdornetchosv)ery 0.00 0.00 pswoiepteuhdlmabtaeihnoaynvsid,iosuatrsincmotcacfyuorrwsmesliln(GdLoietftufecr1o9cb8h3e)rt,ywseauenmnd 6May thirdrecovery 0.00 0.00 albicans(GilfedderandKirkpatrick 1994). 1995 (12 months) 17 Vol. 113 (1)1996 ('ontrlhutlons However, in a concurrent experiment in ing Europeancolonisation.Theunearthing the Melbourne area, Watson ( 1995) found <>l mature plains, selective grazing of sur- th.ii less than 2% "I M. scapigera seeds vivingplants,andabsenceofburiedseeds, remained viable aftei being buried for 6 led tothe irretrievabledemiseofthisonce- months in a recently burnt native grass abundantspecies.Thisscenarioechoesthe land, and no seeds remained viable alter conclusion of many writers (e.g. Groves being buried rot 6 months in an unburnl and Williams l"Kl: Kirkpatrick et. al. grassland, which accords with the results I98K), that the most dramatic changes to found here, grassland ecosystems occurred extremely The absence ol ,i persistent seed hank quickly, within the lirst lew yearsofoccu foi M ficapigeru has three major implies pationby Europeansandtheirsheep, lions for conservation management, espe eialiv in productive grassland remnants Acknowledgments which rupidly accumulate a (hick grass This projeel was funded by the Australian cov1e.tI.I11imiiatiun,r-e M scapigera plants are rNeasteuarrech<CgornasnetrvaadtmiionniAsgteernecdy,byuntdheeraacgrtasPsalraknsd absent before a hie oi othei distnihanee. ^andConservation Service Considerable thanks Hi... no seedling rccruitmenl can be duetoSarahSham,whocollectedtheseeds, expected aftei the disturbance, unless "cl?cted '"' *,ud* Slle and i""1'"'1''1 •klom"1" s,M,se,.esdSc,ls'atlia,'pyiieg'ta'iln'ndtltiolsiea,hecuikl,sesil,h.ea,Ianvte,th,heaeryl,saiitjae*.pep/(peaAainlp.dlipa,hugosen,se,hiit de„doniiehioniili,n(iiH,a.»|i||nie-|di-i^1anidtlm,'ii;aiiil,iMi.s.Is.weineiilndl.lMi.lavo.entsdasaKsniads/.ltlasn,Mneh.icwiee|r>dll;,il|ni|t,Mi.iho|,hei|emslls,n'^peieenddt, aisnodlasteeeddrseamrneanutnslibkeylywitnod)h,e dispersed into ssc„ri;pllt,aShn;d|1J|a,mkie|s|(|R|yoscsompmroevnitdee<d|t„h,e„„p,ho„tuo.g,r„a.,p.,h.., 2, II mature plains do occur at the silo, then substantial recruitment can only References aofnclyco)uw.ervriiaamb.nlm,ededssieeaeetd,deslpwyirlo,ald1f,tuheceitipuorneys,oeanajts. i•olnfeowht.i,h(geihrf ' miSS"oneudutthgUhhW[Waaa>m'll,ueessG'.SM"y.(dS,on(ileMly"u)sCllob1nesme,rlv'lWa'"t.,iBto.'n,'"SMeiWrlevtishctoerepruenl,NNPe.eLww. years(Lunt 1994) Curr, E.M (1886) 'The Australian Race', 1, II mature plants do occui ai the sue. (Government Printer: Melbourne), otmchoecsnutrs(iielmemdneoltdiin.aagltl)er.leseye.reiadifstielrwmieslnlplunhi,as-veubnuglreinrkimenilgny,alatso F«T(IV|uiirncn.tgip/otnurio)ib'na.l.IP'MVeRMalenbpudoovurmMrtin,tjeici)ihSieolliKlla.liCAlounlss(e1m9r6v,6ia)tViiio-flntoeiiAiEuifntfheIoc'ntrisivvtolyl. ed earlier in the year. Small seedlings are Olifedder.l endKirkpatrick, l.fl (1993) Qemtinable (,l,iS,keeeld"y.l..itnogbereckirlulietdmebny•tamahiyghocicnutrensi,int*yfutfiurree ,rw,al,r1,e,,sn„"„a'•t1i',v„e'""ts'hpee"c"Mi"eiisd"'la"an"nd,dvse''xo»TtJia«cs«sm«a»in™ni*aa«.Ps»eBmbiieotlnwoaegiiencniaalli years though), ConstivaitanM, m * 119, tl.hoerI.efsptrhiwiinstc.ti.mi'poatdlreainlsmipp'earncotivesoosilltofsierbeeedoCnohrar*gn~erkcasts,slmtahaneydn GUfe,a!enmTdidadmnoogrre,prTheo'dilVo'pgeyra'e'non"df!n"it,ao"Klu"ir"rdpka'oi"ppsauy"t,lTraitLc^iekou.nllcs"o"o'c)l".h"aBr:,yT"as1su-(m1m>a9"n9"ai4l"ba)"l,n' he (0 enable existing plants to produce eani AustralianJournalofBotany41,A3] 440, more (lowers and seeds liom which new <;""^' "J|I"L,SM ^MurXnong^M^lcrosteris scapigera! a seedlings can grow in the following yea, * """ tins scenario ol delayed post Ine recruit Oroves, Kit. ami Williams, u it. (1981), Natural ineni differs from the model ofdirect, fire grasslands, '» 'Australian Vegetation' Bd R.H. promoted recruitment from a sod seed Qreves.(CambridgeUniversityPress:Cambridge). hhmiainentsk.i euwich,o,i.sc.yih,st,ie,smcso(memgo,nPluiyrdireeplolr>t/.7e;diW,farrokm KirGk.rp&aat,srsilc(a.kln,irdkJss„,aO„nladlfeCGderdmaeesrts,eyrIiWeosaonddlTFaaensndmssahn'aima,'(sTRa.Rsem(m1a9nn8ai8na)tn. eta], l')X7). ConservationTrust:Hobart), The absence ofa persistent seed hank in ' '""' ' " ||,""') A Hortotk survey ol the Derrlmut tthh«.ea vsr.oanpdiidi,n,d,a.esmi,p„rs,oe,\.;oiidie.ma..n.sacdaidlpi.it'igotnraali fcoliluleowt-o Gn,.r„a„ms,s,l,a,,n„d,, „R,es,„e,rv«e,,„„/M,i„-,ii„.i,mvn(n1/c.VhV„i„c,t„or,i»a2. 18 The Victorian Naturalist Contributions Lunnitmi,pnleIi.cDga.rtai(so1sn9ls9a4fn)od.rsgVrpaaerscisialetasinodnwimitanhnfatlgioemwemeersniptnrcoaednudfcitrreie,sotnoarnoadf- Nrgaeetnluearttaiilcoisnstotf1or10et,mhen3ia0rn-t3c6og.rnassesryvawthiitoen.boTxhweooVdilcatnodrsiainn LMucnDtJat'ioo,Cocuuonllrg.n.onasDPsa.leaelrlcd(vi,o1faf9Tit9KBhci5.oeo)Ct.nmoaanennSosddyefeear4KdLv3ito,arlrtwok4iilnp3aogaan9netd-nvrr4Bdiai4itc9oyNgk.lra,ooatfgsiJys.vslBie1ax.,nGn3d(ar.5eta9disA-svsu3)e6sl6taf(.orn1ra9dbl9ssi4)aii.nnn WPuarrJdbMRikoaueeru,gr,rreninnRiMoate.n.ltrWgC,oa..ft,PBi(i.n1ooHW9tn.h7ad7inr(b)ty1.yye92,E8s5a7s,er)cMel.3l.yd5eDR-rs.ge4ot,e6gap.reghnmeRyseiolrnbloaaefttriirvtoeoesgnngeo.ennotef,AaruathtDsiei.toaoJrntn.a,hlaaifatnIaneIdnd.r South-eastern Australia.' (World Wide Fund for heath woodlandinthenorth-easternOtway Ranges Nature:Sydney). following the wild-fire of February 1983. Morgan,J.W.(1995).Ecologicalstudiesoftheendan- ProceedingsoftheRoyalSocietyofVictoria99,51- gered Rutidosis leptorrhynchoides. I. Seed produc- 88. tion, soil seed bank dynamics, population density Watson, S. (1995). Seed Ecology Of Five Native andtheireffectsonrecruitment.AustralianJournal Forbs.In'ABasaltPlainsGrassland'.(Unpublished ofBotany43, 1-11. thesis, Victorian College of Agriculture and Prober,S.M.andThiele,K.R.(1993).Theecologyand Horticulture,Burnley:Melbourne). Mueller - Commemorative Issue The Victorian Naturalist August 1996 1996 is thecentenary ofthedeathofBaron Ferdinand von Mueller. A special issue ofThe VictorianNaturalistwill bepublished in August 1996tocommem- orate Mueller's involvementwith theFNCV as afoundation member, andasits firstpatron. For this issue we have invited a number ofauthors to write on a variety of topics including Mueller's collecting work, his and theclub's involvementwith Wilsons Promontory, the FNCV's contribution towards his monument in St Kildacemetery, aswell asotheraspectsofhis widernatural history interests. We inviteYOUtocontributetothiscommemorativeissuebywritingonany- thing you know about Mueller. Ifyou do not want to write, perhaps you have some suggestions for topics or articles that you would like to see included? Please letus know,assoon aspossible, ifyou haveanysuggestionsorare able to write for the journal. Written material will be needed by the end of May 1996. Theeditors arelookingforwardtohearingfromyou. Allrepliesto:TheEditors, The VictorianNaturalist, LockedBag 3, POBlackburn3130, orphone(home)0394359019. 19 Vol. 113(1)1996