Drift disseminules on Fijian beaches

Transcription

1 New Zeln Journl of otny, 1990, Vol. 28: X/90/ $2.0/0 Crown Copyright Drift isseminules on Fijin ehes J. M.. SMITH Deprtment of Geogrphy n Plnning University of New Engln Armile, NSW, 231, Austrli Astrt Drift isseminule ssemlges were stuie on nine ehes on n ner Viti Levu, Fiji. Seventythree speies were reore, lrgely elonging to eh forest n mngrove ommunities, ut inluing severl speies from freshwter hitts n severl speies introue to Fiji. Sees of mny speies h germinte. Most tx represente hve een shown elsewhere to hve isseminules ple of floting over long perios n istnes. Some isseminules from Fiji n nery islns my e rrie to estern Austrli n New Zeln. Keywors Fiji; rift isseminules; see ispersl; se urrents INTRDUCTIN The ispersl of sees y se urrents hs long intereste otnists in the tropil Pifi region, in prtiulr Guppy (1906) n Riley (1930) whose etile ounts remin fsinting n informtive reing toy. Mny of Guppy's originl oservtions, oth of see ispersl y se n of the littorl plnt ommunities minly involve, were unertken infiji. The preise sites where he worke re not reore. However, his oservtions of riverine rift were me mostly in the Rew estury, n in this se omprisons with the present work re me elow. There hs een erth of suh Reeive 19 My 1989; epte 22 Septemer 1989 stuies sine these pioneering works. Speimens ollete on Viti Levu y Mrs Cloker in 1972 hve een illustrte in glol tlogue y Gunn et l. (1976), ut for Fiji little else hs een pulishe reently. This ontrsts with the more extensive literture on tropil "rift sees" from Atlnti ehes (e.g., Gunn etl. 1976; Nelson 1978,1989). Disseminules (sees, viviprous seelings, fruits, n their frgments) were stuie on nine Fijin ehes in August 1988, s prt of roer investigtion of see ispersl y se urrents in the southwest Pifi region. Investigtion over longer perio, inluing more ehes n t other sesons, no out woul hve yiele more omplete piture. Nevertheless, in the sene of similr pulishe t.itis onsiere worthwhile presenting the results of this investigtion here. STUDY SITES ehes investigte re lote on n ner Viti Levu, lrgest isln in the Fiji group, s shown in Fig. 1. Some of their hrteristis re given in Tle 1, n they re further esrie elow. Authorities for speies nmes re given in Tle 2, or t first mention in the text for speies not nme in Tle 2. ehes on the smll isln NnnuiR were prtly sheltere y fringing reefs, n ke y eh forest (little isture in mny prts) in whih Coos nuifer, Cori suort, Erythrin vriegt, Hernni nympheifoli, Sevol t, Terminli tpp, n Thespesi populne were lolly ommon, n mny other plnts ourre; Cnvli serie A. Gry n Ipomoe pespre were the ommonest eh vines. ehes to either sie of the isln's northwest peninsul were notexpose to previling wins n wves (from the southest or est), unlike the estfing eh. Mngroves grow long the southwest shore, ut hrly t ll ner the stuie ehes. Two ehes proly reeiveriverinerift from the Rew River, s well s oeni rift ross the

2 14 New Zeln Journl of otny, 1990, Vol E N 2 km NW Nnnu o/w^e Nnnu H8 S f0 18 SH Ntol us Tunovo 178 E Deu J Mkuluv Munivtu Fig. 1 Lotions of stuy sites. fringing reef. The y Mkuluv, lying ner the ege of the reef, is well expose to the open se. It is overe y isture eh forest in whih Leuen leuoephl (Lm.) e Wit, Sevol t, n Terminli tpp re prominent, with Cnvli Tle 1 Some hrteristis of ehes stuie. : eh forest, M: Mngrove forest, : eni rift, R: Riverine rift. Site NW Nnnu E Nnnu Mkuluv Munivtu Deu Tunovo us Sigtok Ntol Aspet(s) N,S E All SE S S S sw sw Lol isseminule soure(s) M.M M Distnt isseminule soure(s),r R,,R R No. isseminule tx reore rose (Sw.) DC, Ipomoe pespre, n Vign mrin s ommoneh vines. The gretly isture vegettion long the very sheltere shore t Munivtu is minly mngrove forest. Deu n Ntol ehes oth fe wie gps in the fringing reef, n re expose to hevy wve tion. Tunovo n us reeive oen rift only ross sheltering reef, n Tunovo lso reeives rift from smll river rining through n re of mngrove forest ehin the eh. All four of these ehes re ke y isture eh forest. Sevol t is prominent t eh, lthough its popultion is pprently eing inve n reple y Chrysolnus io t Deu. Cos nuifer n Sophor tomentos re prominent t us, s re Argusi rgente (L.f.) Heine, Clophyllum inophyllwn, n Thespesi populne t Ntol. Sigtok is n esturine site, proly reeiving isseminules from riverine rift ut not from the oen to whih it is onnete y nrrow, wining hnnel. Mngrove forest lines nery shores.

3 Smith Drift isseminules on Fijin ehes 1 METHDS At eh site, generl n vegettionl hrteristis were note. A reful survey ws unertken of strnline isseminules, tking hours epening on length of eh n quntity of rift mteril. Representtive speimens were ollete, n n estimte me of the unne of ll tx on fourpoint sle using the following vlues, verge ross the whole eh: t lest one per metre of strnline; t lest one per 10 m of strnline; t lest one per 100m of strnline; present t lower unne thn. Smll isseminules were speifilly serhe for t suitle ples. Nevertheless, vlues in Tle 2 shoul not e interprete too literlly. Lrge, onspiuous isseminules (e.g., Atun remos, rringtoni siti, Coos nuifer, Ent phseoloies) will hve een reore more fully n urtely thn muh smller ones, espeilly those only few millimetres in length (e.g., Colurin siti, Hiisus tilieus, Vign mrin, Vitex?n/o//fl).Timeonstrintspreluemoresystemti serhing whih prior experiene suggeste woul e timeonsuming n reltively unproutive. At some sites, espeilly on the south ost, sn movement y winlong the eh h urie muh of the strnline eris inluing isseminules, n two potentil sites were none ue to the extent of this prolem. At Mkuluv n Ntol, storm wves h pushe muh of the strnline eris into the ege of the eh forest. For these resons isseminule unnes t ifferent sites nnot e ompre losely. Common strnline rift mterils inlue woo n pumie, s well s isseminules. Plsti n other mterils of humn mnufture were generlly sre, exept t Munivtu (on the outskirts of the pitl, Suv). IDENTIFICATINS Most ommon rift isseminules of the tropil Pifi region re well known to lol otnists. Confirmtion of ientity ws me in mny ses y fining isseminules still tthe to plnts. Herrium speimens were ollete where esirle, n ientifie n eposite t the S outh Pifi Herrium, Suv. A resiue of ineterminte isseminules remins, ll eing smll n unommon. In the fl* lowing gener etermintion to speies is prolemti, n notes re provie elow in lrifition. Referene speimens of isseminules hve een inorporte into olletion hel t the uthor's ress; speimen numers re quote in Tle 2. Annon: Asingle fruit mthing thtofa. squmos ws foun. Fr ommoner were sees mthing those of A. glr illustrte in Gunn et l. (1976) n tht nme is given to them here. However, other Annon speies re grown in Fiji n their sees hve not een exmine. Cnrium: Although fruit size is vrile in C. hrveyi, speimens from Tunovo pper to elong to this ntive speies. A single, lrger fruit from Munivtu proly elongs to either C. iniuml. or C. vulgre Leenh., oth eing ommonly ultivte in Fiji. Erythrin: Most sees foun mthe speimens ollete from littorl trees of E. vriegt. A single see from Mkuluv elongs to ifferent speies (lso reore on New South Wles ehes), possily E. rusglli L. ut provisionlly lle Erythrin sp. 3. Muun: Most Muun sees foun on Fijin strnlines re rther uniform in size n shpe. They lwys hve lk hilum ut vry gretly in generl olortion from rownish pink through hestnut to lk, with vrying egrees of lk spekling. f out 80 sees ollete on the estfing eh t NnnuiR. 1% were lk n. 10% h some egree of lk spekling on rown kgroun. Proly they ll elong to M. gignte. A herrium speimen of M. gignte in the South Pifi Herrium, ollete on NnnuiR y J. E. Ash, ers pinkish rown sees of this type, lthough the speies is usully esrie s hving sees tht re lk (Gunn et l. 1976), or either lk or rown mottle with lk (Verourt 1979). lk sees on Fijin strnlines ommonly were more shrunken n foun further up the eh thn pler ones, n it ppers tht sees ten to rken with ge n exposure to sunshine. Less ommon is nother type of Muun see, somewht lrger n less onsistently irulr in outline thn M. gignte, n usully with onspiuous entrl ulge. Most re lk, with either lk or prtly tn hilum; rrely sees of the sme shpe n size re foun whih re right rerown with tn hilum: these mth sees ollete t Swin Reefs, Queensln, n nme Muun sp. 1 n Muun sp. 6, respetively (Smith et l. 1990). The former might represent either or oth of the two other Fijin ntive Muun speies (M. pltyphyll A. Gry, M. stnleyi C.T. White; Smith 198) n the ltter might ediole sp. (Smith 198) ut in

4 16 New Zeln Journl of otny, 1990, Vol. 28 the sene of suitle herrium speimens or esriptions this nnot e heke. Pnnus: The txonomy of this lrge genus is omplex. Stone (1976) hs propose tht numerous littorl tx from the tropil Pifi region nnot properly e seprte, n ought to e groupe within the single speies P. tetorius. Pyrenes from strnlines in the present stuy re given this nme. Cnvli, Eninr, Merremi, Psiium, Rhizophor, Xylorpus: In eh of these gener more thn one speies grows in Fiji, n isseminules ollete on strnlines oul not e ientifie to speies level. In these ses only the genus nme is use here. RESULTS Drift isseminules reore t the nine stuie ehes re liste in Tle 2. Seventythree tx were reore overll. Eight were foun t every eh, n further eight were sent from only one Tle 2 Disseminules reore n nine Fijin ehes. *1: Alien; 2: serve germinting on strnline; 3:Reore t Swin Reefs; 4: Reore t Cnton Isln; : Known to e ple offloting one month. See Disussion for etils of 3, 4,. For efinition of unne sle see Methos. Txon Alizi smn (Jq.) Muell. Aleurites molun (L.) Will. Annon glr L. Annon squmos L. Atun remos Rf. rringtoni siti (L.) Kuiz rringtoni remos (L.)Spreng. ruguier gymnorrhiz Ceslpini onu (L.) Rox. Clophyllum inophyllum L. Cnrium hrveyi Seem. Cnrium sp. Cnvli sp./spp. Csurin equisetifoli L. Cerer mnghs L. Chysolnus io L. Cleroenrum inerme (L.) Gertn. Coos nuifer L. Colurin siti (L.) rongn. Cori suort Lm. Cys rumphii Knehir Dlergi nentensis (Dennst.) Prin Delonix regi (Hook.) Rf. Derris trifolit Lour. Diosore ulifer L. Eninr sp./spp. Enl phseoloies (L.) Merr. Erythrin vriegt L. Erythrin sp. 3 Guettr speios L. Gyrorpus merinus Jq. Heritier liltorlis Dryner Hernni nympheifoli (Presl) Kuitzki Heve rsiliensis Muell. Arg. Hiisus tilieus L. Ref. Spe " Notes* NW E Nnnu Nnnu Aunne Deu us Mkuluv Munivtu Tunovo Sigtok Ntol. ontinue next pge

5 Smith Drift isseminules on Fijin ehes 17 of the nine sites. At lest 36 plnt fmilies re represente, of whih Fee hs y fr the highest iversity with out 14 speies. All other fmilies re represente y two tx or fewer, exept Convolvulee n Euphoriee with three eh. The most unntly reore isseminule overll ws the oonut Coos nuifer. This my e prtly ue to the fruits' lrge size, mking them onspiuous. Most eh oonuts h een ut open y people (though mny others were intt, n frequently sprouting); in some ses the nuts h proly eliertely een rrie to the ehes, espeilly green ones for rinks, n nnot e onsiere rift fruits. ther isseminules (e.g., Mngifer ini) might lso hve een rrie to ehes y people, ut in ll speies this soure is likely to e less importnt thn river n/or se rift In severl tx (Cnvli, Colurin siti, Cori suort, Hernni nympheifoli, Ipomoe pespre, Phleri isperm, Sophor tomentos,terminlitpp,ximenimerin, et.), lol unne on strnlines ws frequently Tle 2 (ontinue) Txon Inorpus fg ifer (Prkinson) Fos. Intsi ijug (Coler.) Kuntze Ipomoe l L. Ipomoe pespre (L.) R.r. Mngifer ini L. Merremi sp./spp. Metroxylon vitiense (H. Wenl.) enth. et Hook.f. Muun gignte (Will.) DC. Muun sp. 1 Muun sp. 6 hrosi opposilifoli (Lm.) Ref. Spe Notes* NW E Nnnu Nnnu Aunne Deu us Mkuluv Munivtu Tunovo Sigtok Ntol Pnnus telorius Prkinson Pssiflor eulis Sims Pssiflor mliformis L. Phleri isperm (Forsti.) illon Pongmi pinnt (L.) Pierre Psiium sp./spp. Rhizophor sp./spp. Riinus ommunis Sevol t (Gertn.) Rox. Smylhe lnet (Tul.) Summerh. Sophor tomentos L. Sponis ulis Prkinson Slrongyloon luius (Forst.f.) Seem. Terminli lpp L. Terminli litorlis Seem. Thespesi populne (L.) Corre Triurnfett proumens Forst.f. Vign mrin (urm.f.) Merr. Vilex trifoli L. Xnthium oientle ertol. Ximeni merin L. Xylorpus sp./spp. Inet 1 Inet. 2 Inet. 3 Inet. 4 Inet ạ ċ

6 18 New Zeln Journl of otny, 1990, Vol. 28 ue to isseminules hving fllen on to the eh iretly from overhnging plnts. This ws often onfirme y the uneroe onition of the isseminules (e.g., Ipomoe sees still with test hirs, Hernni n Sophor sees still within intt fruits). See viility ws not investigte expliitly. However, sees of mny speies were note s hving germinte fter uril y sn on ehes, s inite in Tle 2. The list of germinte sees might well hve een muh longer h the investigtion followe perio of riny rther thn ry wether. Sees of some other speies, when ollete from strnlines, pprently were lwys e. These inlue Aleurites molun, Cnrium, Eninr, Heve rsiliensis, Mngifer ini, Metroxylon vitiense, Psiium, n Riinus ommunis, none of whih is regulr memer of littorl plnt ommunities. nly hlfpos, lking sees, were foun in the se of Delonix regi. DISCUSSIN There pper to e few ler orreltions, wherey ssemlges might e "expline", etween isseminule ssemlges n site hrteristis. Aswellseingresultofiverseftorsmentione uner Methos ove, this no out is lrgely euse of the sustntil ontriution to ssemlges me y plnts of the eh forest, whose isseminules n reh ll ehes (exept Sigtok) either from lol soures or in oen rift. The smllest vriety of isseminules ws reore t Sigtok, whih lke severl otherwise ommon n wiespre types. The lrgest vriety ws reore t est NnnuiR n Mkuluv, the sites most expose to the previling win n urrent from the southest n est. A smll suite of speies n e istinguishe, whose isseminules tene to our more ommonly on ehes reeiving riverine rift. This inlues Cnrium, Metroxylon vitiense, Xnthium oientle, n perhps Aleurites molun, Annon glr, n Psiium. None of these ontriutes regulrly to littorl vegettion, n most (exepting A. glr nx. oientle) hve sees thtpper never to e vile when foun on ehes. A omprison n e me etween presently reporte isseminule ssemlges on ehes expose to riverine rift, n isseminules reore from rift in the Rew n other Fijin rivers y Guppy (1906). Mny types our on oth lists. Guppy inlue severl tx not note here, mostly with smll sees n often from hereous plnts. In some ses these might e proue only t ifferent seson, or hve sunk efore rehing the se ehes stuie here. A lrger numer of types reorehere ws not liste y Guppy, who proly i not inlue ll unommon ones; it is of interest, however, tht mong these re nine speies not ntive in Fiji (in Annon,Cnrium.Chrysolnus, Delonix, Heve, Mngifer, Psiium, Riinus, n Xnthium) whih proly were not s wiely estlishe there lte lst entury s they now re. Sees oserve germinting fter ispersl y se urrents lso inlue those of some speies not ntive in Fiji (in Annon, Chrysolnus n Xnthium, the lst eing noxious wee). This suggests possily unexpete wy in whih these inving plnts might e eing spre into new hitts n res following initil humn introution into Fiji. For instne, forx. oientle this oservtion represents n ition to wht generlly is known of its reproutive eology. Fruits of this speies re urrs, well known for eoming entngle in mmml fur, ut lso isperse y floowter n lolly in other wys (Lile & Elgr 1984). Dispersl of X. oientle fruits ross the Rew estury n fringing reef to Mkuluv is merely n extension of ispersl y freshwter. However the ourrene thereof fruiting plnts (mittely of low stture) growing from strnline eris shows, pprently for the first time, tht the sees re unhrme y rift over severl kilometres of se, n n then estlish new popultion in littorl hitt. In mny other ses, suh ispersl n germintion re unlikely to le to estlishment euse the eh hitt is inpproprite (see lso Degener & Degener 1974; Smith etl. 1990). In the present stuy for exmple, reore eh seelings of Annon glr, rringtoni remos, n Inorpus fgifer re, unlikely to survive euse mture plnts of these speies grow in moist, inln hitts (Ash & Ash 1984). In suh ses, se ispersl of sees ppers to e "ientl" n not ptively evolve. Even some of the most spetulrly suessful tropil rift sees, whih n e rrie in vile onition for thousns of kilometres, elong to speies whih nnot epen wholly on this mens of see ispersl. For exmple, vile see of Ceslpini onu hs een ollete on Mqurie Isln icos\m\96);&n&entphseoloies sees

7 Smith Drift isseminules on Fijin ehes 19 foun on estern Austrlin ehes s fr south s southern New South Wles n lso e germinte (E. C. Nelson, pers. omm.). oth speies grow in Fijin forests up to 900 m ltitue (Smith 198), oviously well eyon the reh of see ispersl y the se. As Lile & Elgr (1984) remrk, the rnge of ispersl pthwys open to sees is proly wier thn usully onsiere; this my even e the se in speies suh s these where single mehnism is superly evelope. Not ll isseminules here reore on ehes n e onsiere true "rift sees", ple of flottion in the se for mny weeks n potentilly trvelling hunres of kilometres. For exmple, pos ofalizi smn were foun only on ehes ner trees of the speies; they re rittle n esily roken, n seprte sees nnot flot. Nevertheless, the mjority n e so onsiere. Those speies whose isseminules hve een reore on sprsely vegette orl islns remote from fertile plnts (Swin Reefs, 190 km off the Queensln ost on the southest Gret rrier Reef, Smith et l. 1990; Cnton Isln, Phoenix Group.Degener & Degener 1974, vn Zwluwenurg 1942), n whih hve een shown to e ple of floting in sewter for t lest one month (Gunn et l. 1976; Guppy 1906), re note in Tle 2. Disseminules of Cnrium, Cnvli, Muun, Pnnus, Sevol, n Xylorpus whih might e onspeifi with Fijin isseminules, lso ourre t Cnton Isln; n of Cnrium, Erythrin, Ipomoe, Muun, Pnnus, Rhizophor, n Xylorpus, t Swin Reefs. Gunn et l. (1976) lso list s "true rift sees" speies of Cnrium, Cnvli, Merremi, Muun, Pnnus, Pssiflor, Psiium, Rhizophor, n Xylorpus whih my e onspeifi with isseminules foun in the present stuy. Fiji lies in the pth of the westflowing south Equtoril Current. It is likely tht mny sees rehing Fijin ehes, espeilly those fing est or south, ome from Tong or elsewhere. However, they elong to wiespre speies whih lso our in Fiji, so suh istnt origins nnot e ertin. Further to the westmjorprtofthesouthequtoril Current is iverte southwr to eome the Est Austrlin Current (Churh 1987), whih in turn is swept est n northest s prt of the West Win Drift towrs n eyon New Zeln. Floting isseminules my e rrie from islns in the tropil southwest Pifi region n from tropil Queensln in these urrents, in some ses s fr s New Zeln where they hve een reore prtiulrly from Ninety Mile eh (Gunn et l. 1976; Mson 1961). nly the most roust rifters presumly trvel so fr. Mson (1961) reore from NinetyMile eh, Aleurites, rringtoni siti, Ceslpini, Coos nuifer, Ent, Muun gignte, possily two other Muun speies, y, n two unknown tx one of whih might hve een Cnvli or Erythrin. Ipomoe pespre hs estlishe smll popultion there (Sykes 1980), no out from strne rift sees. New South Wles ehes, upurrent from New Zeln, reeivelrgervriety. My ollortors n I hve ollete isseminules of Atun remos, Clophyllum inophyllum, Hernni nympheifoli, Intsi ijug, Muun sp. 1, Muun sp. 6, hrosi oppositifoli, n Strongyloon luius there, in ition to possily ll the ove tx reore from New Zeln. However, even in those ses where sees remin vile, suh extrtropil ispersl nnot usully exten the rnges of these tropil tx ey on their mostly lrey ro limits. Its emonstrtion nevertheless shows how suh wie rnges my hve een hieve in the pst. ACKNWLEDGMENTS This work ws unertken uring perio of stuy leve supporte y the University of New Engln. I thnk Milik Nqsim, Julin Ash, Py Nunn, n Chrles Eton for logisti vie n help; Sul Voonivlu n Rny Thmn for ssistne with ientifitions; Dvi Rihrsonfor filities t Trinity College, Dulin, where the pper ws written; n Chrles Nelson, ill Sykes, Nigel We, n rr Wterhouse for ritilly reing the mnusript. REFERENCES Ash, J. E.; Ash, W. 1984: Freshwter wetln vegettion of Viti Levu, Fiji. New Zeln journl of otny 22: Churh, J. A. 1987: Est Austrlin Current jent to the Gret rrier Reef. Austrlin journl of mrine n freshwter reserh 38: Costin, A.. 196: Longistne see ispersl to Mqurie Isln. Nture (Lonon) 206: 317. Degener,.; Degener, I. 1974: Flotsm n jetsm of Cnton Isln, South Pifi. Phytologi 28: Gunn, C. R.; Dennis, J. V.; Prine, P. J., 1976: Worl guie to tropil rift sees n fruits. New York, Qurngle/The New York Times ook Co. Guppy, H.., 1906: servtions of nturlist in the Pifi etween 1896 n 1899, Vol. 2. Plnt ispersl. Lonon, Mmilln.

8 20 New Zeln Journl of otny, 1990, Vol. 28 Lile, M. J.; Elgr, M. A. 1984: Multiple pthwys in ispore ispersl exemplifie y stuies of Noogoor urr Qinthium oientle ertol., Composite). otnil journl of the Linnen Soiety 88: Mson, R. 1961: Dispersl of tropil sees y oen urrents. Nture (Lonon) 191: Nelson, E. C. 1978: Tropil rift fruits n sees on osts in the ritish Isles n Western Europe. I. Irish ehes. Wtsoni 12: : Exoti rift fruits n sees from osts of ritin n jent islns. Proeeings of the Royl Institution of Cornwll (in press). Riley, H. N. 1930: Dispersl of plnts throughout the worl. Lonon, Reeve. Smith, A. C. 198: Flor Vitiensis Nov, Vol. 3. Lwi, Kui, Hwii, Pifi Tropilotnil Gren. Smith, J.M..; Hetwole, H.; Jones, M.; Wterhouse,. M. 1990: Drift isseminules on ys of the Swin Reefs, Gret rrier Reef, Austrli. Journl of iogeogrphy 17: 17. Stone,. C. 1976: The PnneeoftheNew Heries, with n essy on intrspeifi vrition in Pnnus tetorius. Kew ulletin 31: Sykes, W. R. 1970: Ipomoe pespre (L.) R.r. ssp. 6r«7ierow(L.)ostr.intheNewZelnregion. New Zeln journl of otny 8: Verourt, A mnul of New Guine legumes. otny ulletin 11: Le, ffieof Forests, Division of otny. vn Zwluwenurg, R. H. 1942: Notes on the temporry estlishmentof inset n plnt speies oncnton Isln. TheHwiinplnters' reor46:492.