Kapisen - pcaseychelles.org Plant Conservation Action group Newsletter December 2006 Issue 6 The...

KapisenPlant Conservation Action group NewsletterDecember 2006 Issue 6

The roles of animals in habitat rehabilitation

K a p i s e n 2 I s s u e 6

E d i t o r i a l

ContentEditorial 2

Birds&Fruits 3

Plants&Geckos 4

Pollinators 6

RatsonIslands 9

RatsonAldabra 10

NotesfromtheField 12

Medusagyne 14

RedListProject 15

NorthIslandProject 16

PCANews 17

PCAPublications&Info 18

TheRolesofAnimals inHabitatRehabil i tat ion

DearKapisenreaders,

In Seychelles we have long been aware thatrehabilitation of habitats should serve both plantsandanimals.Rehabilitationprojectsonsmallislands,suchastheoneonNorthIsland(p.16),aimtocreateanark forendemicplantsand foranimalssuchasthe Seychelles White-eye. Less discussed are therolesthatanimalsmayplay forhabitatrehabilitation.Animalscangreatlyhelpus in thisendeavour–orposeadditionalchallenges…

An obvious example of animal involvement is thatofbirdsandfruitbatstransportingfruitsandtherebydispersing seeds. It has been calculated thatSeychelles Bulbuls may carry around several 100tonsoffruitmassperyearonMahéalone!Researchreportedonpage3indicatesthatBulbulseffectivelydispersebothnativeandinvasiveplantshowever,sotheycanbeacrucialfactorforthereestablishmentofnativevegetation,orbringtheworstinvasivespeciestoafreshlyrestoredsite…

Transport of pollen is even more important forsuccessful plant reproduction. If a plant is notpollinated, it cannot produce viable seeds oroffspring:afactthatwasexperiencedbySeychelloiswho had to hand-pollinate Vanilla flowers in order to obtain the valuable seed pods (p. 13). Pollenis often transported by animals such as insects or– particularly on oceanic islands – lizards. DennisHansenshowsinhisarticle(p.4),thatrareendemicplants profit from growing close to Vakwa shrubs (Pandanusspp.),because that iswherePhelsumageckos hide from their predator – the Kestrel.However, not only thepresenceof certain speciesbut also the overall vegetation structure can influence theactivitiesofanimalpollinators,whichmayhaveimportant implications for vegetation rehabilitation,asdemonstratedbyChristopherKaiseronpage6.

RatsareknowntoaffectvegetationinSeychelles–bothonthegraniticislands(p.12)andonAldabra(p.10).However,evenratimpactsonvegetationcanberathercomplex.ChristaMulderpresentsonpage9anexamplewherethemostrelevantratimpactsmaybeindirect,throughimpactsonseabirdcolonies.Inherexample ratsmayalsohavebothpositiveandnegative direct impacts, predating both native andinvasivespecies.Thisdualrolewasalsoobservedin Seychelles (p. 12) and mirrors that of the seeddispersingbirdsmentionedbefore.Theissueofratimpactsonvegetationisveryrelevanttotheongoing

NorthIslandRehabilitationProject,whereratshavebeensuccessfullyeradicatedforoverayearnow(p.16).

Lastbutnot least,we report frommajoradvancesin a core field of PCA: the conservation of endemic plants in Seychelles. A Red Data assessment ofallendemicwoodyplantshas justbeencompleted(p.15);andusing thecaseof theuniqueendemicJellyfish tree PCA member Denis Matatiken shows inhisMScthesishowdetailedconservationbiologystudiescancomplementtheinformationofaRedDataassessment for supporting concrete conservationactionofthemostthreatenedplants(p.14).

In 2007 PCA will celebrate its 5th anniversary: Itwill be a year to look back on achievements andto plan future actions! We are looking forward toanother successful year for plant conservation inSeychelles!

Meyervepoulannen2007!

EvaSchumacher,KatyBeaver&ChristophKueffer

Editors

The electronic version of Kapisen can be orderedfromboga@seychelles.netordownloadedfromwww.plantecology.ethz.ch/publications/books/kapisen

Photofrontcover:Plants&GeckosinMauritius:A male Phelsuma cepediana geckoapproaching a flower of Trochetia blackburniana(Malvaceae)byclimbingdownitslong,thinstalk(DHansen).


B i r d s & F r u i t s

BulbulsLoveFoodImportsFromOverseas

ByChristophKUEFFER1,LilianKRONAUER1*,PerleyCONSTANCE2,RodneyFANCHETTE2,JamesMOUGAL2,GérardROCAMORA3

1 InstituteofIntegrativeBiology(GeobotanicalInstitute), ETHZurich,Switzerland2 DivisionofEnvironment,MinistryofEnvironmentand NaturalResources,Seychelles3 IslandConservationSociety(ICS),Seychelles* correspondingauthor:[email protected]

Seeddispersalisvitalforthesurvivalofplants.Oftenjuvenileshavealowersurvivalchanceclosetotheirparentsbecausecompetitionwith themotherplantor siblings is high or the mother plant is a sourceofpathogensandherbivoresthatmayattacknearbyjuveniles. And, of course, only through dispersalcan plants colonize new areas. This is especiallyimportant for rare plants after major habitatdestruction,ashasbeen thecase for theendemicplantsoftheSeychelles.Manyofthemsurvivedonlyinsmallpockets–forinstanceoninselbergs,locallycalled ‘glacis’. Only through effective dispersal willtheybeabletoenlargetheirgrowingareasandtheirpopulationsizesagain.Similarly,effectivedispersalenablesinvasiveplantstoinvadetheforestsoftheSeychelles.Forinstance,therecentlyintroducedFoWatouk(Clidemia hirta)isspreadingveryfasteveninto remote areas such as the mountain forest ofCongoRougebecauseitisdispersedbybirds.

In Seychelles, the majority of plant species isdispersedbyanimals;todaymainlybytwoendemicandonealienbirdandoneendemicfruitbatspecies.WhileBluePigeons,IndianMynahandFruitBatsareprobably important indispersingseedsover longerdistances,itisparticularlytheSeychellesBulbul(seeFig. 1) that disperses seeds within forest patchesand from the inselbergs to the surrounding forest.Bulbuls probably disperse seeds over relativelyshortdistances. Inanexperimentdescribedbelow,ittookaseedeatenbyaBulbulanaverageofonly15minutesfromtheingestiontothemomentitwasdropped. Seychelles White-eyes are also goodseeddispersersovershortdistances(Rocamora&François,2000),buttheyarecurrentlyveryrare.

WewereinterestedtoinvestigatehowtheSeychellesBulbul may influence the composition of the vegetation. If theypreferentiallyeat (anddisperse)fruits of certain species, these species might benefit. IfBulbulsmainlyeatlocalfood(i.e.nativespecies)

it isgoodnewsforhabitatrehabilitation,but if theypreferimportedfood(i.e.invasivespecies)itmightbebadnews.Toinvestigateourquestionwecomparedthecharacteristicsoffruitsofanumberofnativeandinvasivewoodyspecies,andfedthemtoSeychellesBulbul in captivity (Kronauer 2005, Kronauer &Kueffer2004).

The fruit analysis showed that invasive speciesproduce fruits of higher nutritional quality than thenativespeciesoftheSeychelles.Thiswasmainlyduetoalowerwatercontent,resultinginahigherrelativecontent of valuable dry fruit flesh per total fruit weight (socalledrelativeyield),andtheyhadalsoahigherenergycontent,andatendencyforhighersugarandfatcontents.Cinnamonproducesfruitsofparticularlyhighfatandproteincontent.Thefatcontentwasabout30-timeshigher inCinnamonfruits thanafruitofatypicalendemicspecies.Itwasthereforenosurpirsetoobserve that in the foodselectionexperiment inwhichindividualsoftheBulbulwerepresentedwithachoiceoffruits(seeFig.2),thefruitsofCinnamonwerepreferredoverthoseofallnativetreesexceptone(Bwarouz,Dillenia ferruginea).So,Bulbulsseemtopreferimportedfruitsoverlocalfood.Forthesamereason,manyhumansloveBurgersandIce-Cream:fatandsugar…MoreresearchwillhavetoshowwhyBulbuls lovesomenative treessuchasBwa rouz.

Perhapsbecauseitisabundantandthebirdsknowit?Andwewillneedtocheckthepreferencefornativespecies in the field. For instance, Bwa merl (Aphloia theiformis) is often eaten by Bulbul in the field (as the namesuggests),butwasnotlikedintheexperiment.Maybe, the fruitqualitywasnotgoodenoughaftertransportation from the field to the cage. In any case, thesefavourednativefruitspeciesmaybea

Fig.1 SeychellesBulbul (Hypsipetes crassi-rostris)incaptivity(LKronauer).


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first priority for replanting in rehabilitation projects becauseoftheireffectivedispersalandutilityforthenativebirds.

ThepresenceofhighqualityfruitsofinvasivespeciesintheforestsofSeychellescanhavebothnegativeand positive impacts on native plant populations(Kueffer2006).Ifthenativeplantsareincompetition

dispersalofnativeplantsandassurethesurvivaloffrugivorousendemicbirds.Bytheearly19thcentury,muchofthegraniticSeychelleswasdeforested.Atthattime,probablythefruitproductionofCinnamonandotheralienfruittrees,thatwerequicklyinvadingthe deforested land and were planted in gardens,actedasalternativefoodsourcesandassuredthesurvivaloftheendemicfrugivorousspecies.WithoutCinnamon, Guava, Jambrosa, Ylang Ylang andotherimportedfruits,theBluePigeons,BulbulsandFruitBatsmighthavebecomeveryrare likemanyotherendemicbirdsinSeychelles…

ReferencesKronauer,L.2005.Seed dispersal of native versus

exotic plants in the Seychelles. Masterthesis.GeobotanicalInstitute,ETHZurich,Switzerland.

Kronauer,L.&C.Kueffer2004.Seed dispersal assisted by birds.Birdwatch52:3-7.

Kueffer,C.2006.Impacts of woody invasive species on tropical forests of the Seychelles.Diss.ETHNo.16602,ETHZurich,Switzerland.

RocamoraG.&J.François(coord.).Seychelles White-eye Recovery Programme. Phase 1 (May 1998-May 2000). Final Report.MinistryofEnvironment&Transports/IUCN/DutchTrustFund.

withinvasivespeciesforseeddispersers,i.e.iftheBulbulseatanddispersemainly invasive species,then thenative species could suffer from reducedseed dispersal. On the other hand, by permittinghigher densities of frugivore species, the fruitproduction of invasive species may also promote

(often) feed on nectar and fruits much more thanlizardsonmainlands(Olesen&Valido2003).Thiscouldbebecausetherearelessinsectsonislandsthanonmainlands,so theotherwise insectivorouslizards have to broaden their diet to survive – ormaybebecausetherearelesspollinatinganimalsaround,leavingthenectarunharvestedandavailablefor alternative flower visitors. Or, of course, it could beduetoacombinationofdifferentreasons.

ThissuggeststhatonsomeIndianOceanislands,Phelsuma geckos may be important pollinators orseeddispersers.Pollinationandseeddispersalaretwo very important ecosystem processes, withoutwhichmanytropicalforestswouldslowlydie.Manyplantsdependonanimalstotransferpollensothatfruitscanset,andoncethefruitsareripetheyoftenneed to be dispersed away from the mother treebefore the seeds can germinate. Most Phelsumaspeciesarerelativelysmall,whichlimitsthesizeoffruitstheycaneat,andtherebylimitswhichseedstheycandisperse.However,theincredibleclimbingskill of geckos enables them to visit all kinds of flowers for nectar, even if the flowers are at the end of a long stalk (Fig. 1).Therefore, theyarepotentiallygoodpollinators of many different flowering plants, and

Fig.2 ThesetupofthefoodselectionexperimentwithaCinnamonfruitontheleftandaBwarouzfruitontheright.(LKronauer)

PlantsandGeckos–andHowTheyInteract

ByDennisHANSEN

InstituteofEnvironmentalSciences,UniversityofZurich,Switzerland

[email protected]

The islands of the western Indian Ocean arefamousfortheirrichendemicbiodiversity.IncludingMadagascar, thereare thousandsofplantspeciesfoundnowhereelse.Also,therehasbeenaradiationofendemicdiurnalgeckosofthegenusPhelsuma,which comprises some 35–40 species. We areaware that these beautiful and colourful geckosinteractwithplantsbycrawlingonthem,feedingoninsectshidingbetweentheleaves,layingtheireggsinhollowstems,andgenerallybymakingtheplantstheirhome.However,are thereanyotherways inwhichplantsandgeckosinteract?

Arecentstudydocumented that lizardson islands


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geckos’ main predator, the Mauritius kestrel, willprobably not want to fly into the tangled mess of spiky leaves–and thegeckosare thussafer there thananywhereelse(Fig.2).Secondly,therichmosaicofsunandshadewithinapatchofPandansfacilitateseasy thermoregulation for thegeckos– if theyaretoohot,theyonlyneedtomoveafewcentimetrestobeintheshadeandviceversa.Thirdly,thedenselypackedrosettesofleavesoffersasuperbegg-layingsiteforthegeckos,andIhaveoftenfoundtheireggsglued into theverynarrow leafaxils–whereeventheomnipresentratscannotgettothem!

Pandansthereforeofferthegeckosagoodhome–fromwhichthegeckosmightnotwanttostraytoofar.Inturn,thiscouldmeanthatgecko-pollinatedplantswhicharegrowingclosetoPandanpatchesmaybevisitedmoreoften,andsoreceivemorepollenand

theirroughscalesareindeedwell-suitedtotransportpollen grains from flower to flower. However, unlike manyotherpollinatinganimals(e.g.bats,bees,birds,butterflies), geckos cannot fly. Thus, their efficiency aspollinatorsislikelytobeconstrainedtorelativelysmallerdistanceswithintheecosystem.

One of the main focuses of my PhD was to studygecko pollination and seed dispersal of severalendemic plants in Mauritius. After observing theplantsandgeckosformanyhours,Irealisedthatthegeckoswerenotevenlydistributedwithinahabitat.Just like you and me, they like to have a good,secure home. I found that dense patches of spikyPandanusplants–alsocalledPandansorVacoas–weremuchpreferredbythegeckos,andmanymoreindividualswerefoundinsuchplacesthananywhereelse. Pandans probably offer several advantagescompared to other vegetation types: firstly, the

Fig.1AmalePhelsuma cepedianageckovisiting a flower of Trochetia blackburniana(Malvaceae)(DHansen).

Fig.2 AmalePhelsuma cepedianagecko hiding between the spikyPandanusleaves(DHansen).

Fig.3 A male Phelsuma cepediana geckolicking the sweet nectar of Roussea simplex(Rousseaceae),therebypollinatingit(DHansen).

therefore get a higher fruit set. But how far awayfrom Pandans would this positive effect extend?OnIleauxAigrettes,asmallisletoffthesouth-eastcoastofMauritius,arecentstudyshowedthatwithinone day, Phelsuma ornata geckos were observedat different places up to 80 metres apart, but thatthevastmajorityofgeckoswereobservedatspotsnomorethan5to10metresapart(Nyhagenetal.2001).

Wecouldthereforeexpectgecko-pollinatedplantstodobetter in termsof fruitset if theygrowwithin5-10metresofPandanpatches.ThisisindeedwhatIfoundfortwogecko-pollinatedendangeredendemicplants in the upland heath areas in Mauritius –Trochetia blackburniana (Malvaceae) (Fig. 1) and

interactions will also find their way back into these areas. In particular, pollination and seed dispersalareessential for natural plant regenerationbut, sofar, there is little information on the effect of therestoration management on such plant–animalinteractionsinMauritiusandelsewhere(Fig.1).

At Pétrin, a 6-ha CMA harbours a part of theremnants of highly diverse heathland-type habitat,which was formerly widespread in the uplands ofMauritius.About 40% of plant species in the CMAare either endangered or critically endangered.Regularweedingof invasiveplantswithintheCMAhascreatedahabitatstructurewhichishighlydistinctfrom thesurroundingdegradedplantassemblages(Fig 2). Invasive species form an impenetrablethicket with a uniform, dense vegetation structure,whichdominatestheunrestoredareadespitehavinga similar native plant species composition to therestoredarea.However, it isunclearwhethersuchdifferencesinhabitatstructurealsoaffectpollinatordiversity.Ifso,doesthelatterresultinincreasedplantreproduction?Areallanimalsandtheir interactionsaffected equally? And finally, because we are interested in restoring native communities, are thepollinatorsnativeorintroducedtoMauritius?

Tounderstandtheseprocesses,Iobservedpollinatorsof all flowering plant species in Pétrin CMA and in


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HabitatRestorationinMauritius:AddingPollinatorstotheEquation

ByChristopherN.KAISER,

EcosystemManagement,ETHZurich,[email protected]

The unique fauna and flora of Mauritius have beensubjecttoawaveofextinctionssincehumancolonisation about 400 years ago. To counteractthecontinuousdegradationofnativehabitatandtopreserve the highly endangered flora of the island, thegovernmentalNationalParksandConservationService (NPCS) and a local NGO, the MauritianWildlifeFoundation(MWF)restorethenativehabitatbyhand-weedinginvasivealienplantspecieswithin11 fencedplots (ConservationManagementAreas,CMAs), totalling an area of approximately 44 ha.Recent surveys have reported a slow but gradualregenerationofnativeplantspecies in theseareas(Mauremootooet al. inpress).However,ashabitatrestoration in Mauritius aims to restore wholeecosystems, it iscrucial tounderstandwhether,byrestoring the original flora, native animals and their

Roussea simplex (Rousseaceae) (Fig. 3) (Hansen2006, Hansen et al. in press). Both plant speciesreceivedfarmorevisitsbygeckosiftheygrewwithin10metresofPandanpatches,thaniftheygrewmorethan20metresaway.Consequently,theplantsthatgrewclosetoPandanshadamuchhigherfruitsetthanplantsgrowingfarfromPandans.

These results highlight that indirect interactionsbetweenplantsviapollinatorsarejustasimportantas the direct interactions between a plant and itspollinator. Furthermore, these results demonstratethatPandansareimportantinstructuringecologicalinteractions by being favoured microhabitats fordaygeckos–andthatweneedtounderstandandpreserve the interactions between species just asmuchasthespeciesthemselves.

Acknowledgements

I want to thank the Mauritius National Parks andConservation Service and the Mauritian WildlifeFoundation,andmysupervisorChristineMüllerandmy colleague Chris Kaiser, for help, support andfriendshipduringthelastmanyyears!

ReferencesOlesenJ.M.&ValidoA.(2003)Lizardsaspollinators

andseeddispersers:anislandphenomenon.Trends in Ecology & Evolution,18,177-181

NyhagenD.F.,KragelundC.,OlesenJ.M.&JonesC.G.(2001) Insular interactions between lizards and flowers: flower visitation by an endemic Mauritian gecko. Journal of Tropical Ecology,17,755-761

HansenD.M.(2006)Ecology,evolution,andconservationofplant-animalinteractionsonislands.PhDthesis,UniversityofZurich,Zurich

HansenD.M.,KiesbüyH.C.,JonesC.G.&MüllerC.B.(inpress)Positiveindirectinteractionsbetweenneighbouringplantspeciesviaalizardpollinator.American Naturalist


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a neighbouring invaded area. Pollinator speciesrichness was 25% higher in the restored habitatandthenumberof interactionsbetweenpollinatorsand flowering plants was almost double that of the unrestoredarea.Ofseveralcommonplantspeciesinbothsites,57%performedbetter in therestoredsite, suggesting that habitat restoration improvedreproductive success, possibly partly due to anincreaseinpollinationquantityandquality.

Wefoundafewverycommonpollinatorsandmanyrelatively rare ones, i.e. approximately half of thepollinator species visited less than two flowers. This patternwasevenmoreprominentwhencomparingthetwosites.Forexample,theendemicdaygeckoPhelsuma cepediana was a frequent flower visitor in the CMA (Fig. 1A, C), but visited only a total of five flowers of three plant species in the unrestored area. Thiswasalso thecase for introducedspecies: theinvasive yellow-footed ant Technomyrmex albipesvisited flowers of twice as many plant species in the

restored compared to the unrestored area (Kaiser2006).

Overall, the vast majority of common pollinatorspecies observed in our study are not native toMauritius. Species introductions have occurredboth deliberately, for example the honey bee Apis mellifera, or accidentally, such as the widespread fly Stomorhina lunata.Whataretheimplicationsofourfinding for the native plant and pollinator community of Mauritius? The lack of co-evolved adaptationbetween native plants and introduced pollinatorsmay result in less effective pollination. In addition,introduced flower visitors which successfully compete with native pollinators for floral resources may cause their displacement to lower quality resources andultimatelytheirextinction.

Mutualistic partners benefit from each other. For example pollinators act as pollen carrier betweenflowers and, in return, receive floral resources, such as pollen and nectar, as reward. Similarly,

Fig.1FlowervisitorsofnativeplantspeciesinMauritius,primarilyinPétrinCMA.A:Phelsuma cepediana,blue-taileddaygecko,onMolinaea alternifolia(Sapindaceae);B:Apis mellifera,honeybee,onPsiadia terebinthina (Asteraceae);C:Paragus borbonicus, hover fly, on Dodonaea viscosa;D:Eurytonidae sp 1,parasiticwasp,onPhyllanthus phillyreifolius (Euphorbiaceae)E:Phelsuma cepediana onLabourdonnaisia calophylloides (Sapotaceae,photographbyD.Hansen)F:SpideronSyzygium coriaceum (Myrtaceae)G:Phelsuma ornata,ornateday-gecko,onGastonia mauritiana (Araliaceae,onIleauxAigrettes)H:Eristalinus flaveolus (Syrphidae)onStillingia lineata (Euphorbiaceae)(C.Kaiser).


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considerthepossibilitythatintroducedanimalsmaysubstitutenowextinctnativepollinators.MuchmoreeffortisrequiredintohabitatrestorationinMauritius,preferablyintorestorationschemeswhichpreservehabitatstructure tosustainhigh levelsofpollinatordiversity. Finally, the success of such restorationschemescanonlybeassessedbymonitoringspeciesdiversity of both plant and animal species and byensuring the long term sustainability of ecologicalinteractions.

Acknowledgements

IamgratefultotheNationalParksandConservationService in Mauritius for permission to work in theNationalParkandtotheMauritianWildlifeFoundationforlogisticsupport.IthankChristineMüllerandJaneMemmottforsupervision.

ReferencesKaiser,C.N.2006.Functionalintegrityofplant-pollinator

communitiesinrestoredhabitatsinMauritius.PhDthesis.UniversityofZurich,Zurich.

Mauremootoo,J.R.,I.Watt,andC.V.Towner-Mauremootooinpress.Mauritiusinstitutionalconservationcapacity.InV.BachrazandR.Atkinson(Eds.).ThebiodiversityhotspotofMauritius;past,presentandfuture.NationalParksandConservationServiceMauritius,Reduit.

Chittka,L.,andS.Schürkens2001.Successfulinvasionof a floral market. Nature 411: 653.

avianseeddispersersfeedonfruitsandseedsandtransport themawayfromthemother treeeither intheir beaks or guts, allowing the plant to dispersepropagules over a large distance. Both processesensure natural plant reproduction and maintainviable plant population size. However, the roleof pollinators and other mutualists, such as seeddispersers, in habitat restoration has been largelyneglected. The results of this study suggest thatrestoration schemes may act on several levels:first, through reducing direct competition for natural resourcesbetweennativeand invasiveplants,andsecond, through reducing indirect competition forpollinatorsbetweenneighbouringplants.Flowersofinvasiveplantscanbeveryattractivetopollinators,whichcanresultinfewervisitsofthesamepollinatorsto flowers of neighbouring native plants (Chittka & Schürkens 2001). By eradicating invasive plants,theriskofsuchcompetitionbetweenplantspeciesisreducedandnaturalregenerationofnativeplantsislikelytoincrease.Consequently,conservationistshave to account for such interactions and have to

Fig.2 Heathland habitat in (A) Pétrin ConservationManagementArea(CMA)withoutinvasiveplantspecies,and (B) adjacent to Pétrin CMA, heavily degraded byinvasiveplants.NotetheopenstructureintheCMAandthe dense thicket of mainly Psidium cattleianum in theunrestoredhabitat(C.Kaiser).


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R a t s

AftertheSweep:WillRemovingRats from IslandsResultinRestoration?

ByChristaMULDER,

Institute of Arctic Biology, University of AlaskaFairbanks,[email protected]

Rats have been and continue to be extremelyeffectiveinvadersofoceanicislands.Overthepasttwodecadestherehasbeenanenormousincreasein the number of islands on which introducedpredators, particularly rats, have been eradicated.Thesesuccessfuleradicationsgiverisetohopethatsuchislandscanberestoredtoastateresemblingthat prior to invasion – but is that realistic? Ourstudy of seabird islands in New Zealand focusesondetectingtheeffectsofratsonislandvegetationand soil processes, including what happens whenrats are removed. Here I describe what we havediscovered to date about the role that rats play inchangingislandecosystems.WetookadvantageofthefactthatNewZealandhasaverylargenumberofoffshoreislands;onsomeoftheseratshaveneverbeenpresent,onsometheyarestill found,andonsometheyhavebeeneradicated(usuallyinthepastdecade)or arebeing controlledandmaintainedatlowdensities.Intotalweincluded21islandsinthestudy,alllocatedofftheeastcoastofthenorthislandofNewZealand.

The islands we work on are or were home topopulationsofburrowingseabirdssuchaspetrels,andshearwaters.Thesebirdsfeedatseaandthencomebacktotheislandsintheeveningduringthenestingseasontobuildburrows,layeggsandraisechicks. While digging burrows to lay their eggs in,theycompletelymixup thesoil, incorporating litterandanyseedsintothesoildownto30cm.Theyalsodepositvastquantitiesofguano,aswellasleavingbehind feathers, regurgitated food, eggshells anddeadeggsandchicks.Havingmillionsof seabirds(literally!)runningoverthesoilsurfacemakesitprettydifficult for any little seedlings to survive. Figure 1 shows what happens when you prevent seabirdsfromtrampling:asmallforestofseedlingsemerges!

Fig.1 ImpactsofseabirdsonMiddleIsland,anislandwithveryhighseabirddensitiesandnohistoryofrats.The exclosure on the left shows high densities ofseedlingswhenseabirdsarekeptout.Thestructureontherightisacontrolplotwithaccesstoseabirds(noticethewiredoesnotreachtheground)andnoseedlings(N.Grant-Hoffman).

Fig.2 Destruction of Pittosporum crassifoliumfruitsbyrats(C.Mulder).

Itiswellknownthatrats,particularlythelargerspecies(Rattus rattus, theshiprat,andRattus norvegicus,the Norway rat) kill seabirds as eggs, chicks, andsometimes adults, resulting in a reduction of theirpopulations or their local extinction. We expectedmanyoftheeffectsofratstobe“indirect”–i.e.theresult of lower seabird populations. But we alsoexpected that ratsmight impact vegetationdirectlybyeatingseedsandseedlings (Fig.2),bymovingseedsabout,andbyeatinglargerinvertebratessuchassnailsandcaterpillarsthatinturnconsumeplantsor detritus. We wanted to know which of the rateffectsweredirectandwhichwereindirect(throughseabirds)becausethattellsussomethingaboutwhatislikelytohappentoislandswhenratsareremovedbutseabirdshavenotreturned(yet).

Ingeneral,mostof theeffectsof ratswere indeedduetoseabirds.Forexample,seabirddensity(ratherthanratpresenceper se)explainedwhathappenedwithsoilandplantnutrientcontentandinvertebratepopulations. However, the results weren’t exactly

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whatwehadexpected.Belowground(inthesoilandlitter),ratshadmostlynegativeimpacts:whentheywere present and seabirds were absent, soils hadmuchlowernutrientcontent(particularlynitrogenandphosphorus) and much lower populations of litter-andsoil-dwellinginvertebratessuchasherbivorousnematodes, minute land snails, and collembolans.However,effectsofratsonvegetationandanimalsliving on the vegetation were mostly positive orneutral: islands with rats had higher tree biomassand shrubs produced more leaves, while averageseedlingdensityanddiversityanddamagelevelsbyinvertebrate herbivores were not different betweenislands with rats and those which never had rats.We are still trying to figure out why we don’t see the muchhigherproductivitythatwesawbelowgroundreflected in the vegetation and associated fauna, butitmaybethatforplantsthedamagingeffectsofburrowingoutweightheadvantagesofhavingmorenutrientsinthesoil.

So what happens when rats are removed? Well,itdependsonwhatwe lookat.Forsoilsandadultplantstheansweris:“Notmuch!”.Wecouldn’ttellthedifferencebetweenislandswithratsandthosewhereratshadrecentlybeenremovedforsoilstructureandnutrient content. However, there was one aspectof the vegetation that was affected strongly by ratremoval: seedling populations. Islands with ratsremovedorcontrolledhadmorethantwiceasmanyseedlingsperm2asislandswithratsorthosewhichhadneverhadany rats,butmostof theseedlingswere of only one or two species, so that diversitywas actually lower on these islands. Whether thisdifferencewill bemaintainedas the seedlingsageisunclear.

What does this mean for restoration? Without thereturnof seabird colonies it isunlikely that islandsfromwhichratsareremovedwillreturntoapre-ratstate,sincemostoftheimpactsofratsarereallytheresultofreductionsinseabirdpopulations.However,plantcompositionwillprobablychangefollowingrateradication;whetheritwilleventuallybecomemoresimilartothatofseabird(non-rat)islandsorwhetherthecompositionwillbeverydifferentfromeitherratorseabirdislandsisstillunclear.Wealsohavesomeworrisome observations suggesting that invasiveplant species,uncommonon islandswith seabirdsorrats,maybebecomingmorecommononislandswhere rats have been removed, possibly becausethey are no longer being trampled or consumed.Whilewecan’tyetpredictexactlywhatwillhappen,one thing is clear: without the restoration of theseabirdcoloniesontheseislands,thelegacyofratinvasionsontheseislandswillpersistforaverylongtime.

This project is a collaboration between the University of Alaska Fairbanks (Christa Mulder, Nikki Grant-Hoffman and Mel Durrett), Landcare Research in New Zealand (David Wardle, Peter Bellingham, Tad Fukami and others) and the New Zealand Dept. of Conservation (Dave Towns); see http://users.iab.uaf.edu/~christa_mulder/RASP%20webpage.htm.

We established a Research Conservation Network on impacts of introduced predators and their removal on seabird islands. If you are interested in finding out more about the project or network, please contact Christa Mulder.

TheImpactofRatsontheVegetationofAldabra

ByAlexUNDERWOODRanger,Aldabra,[email protected]

The vegetation on Aldabra atoll (Republic ofSeychelles)evolvedintheabsenceofrodents,untilthe relatively recent introduction of rats by visitingships,probably in the19thcentury.Theseratsmaytherefore have a negative impact on the uniquevegetationcommunitiesonAldabra.

Icarriedoutageneralsurveytoidentifyplantspeciesbeingtargetedbyratsanddocument the impactofratson thesespecies.Being fairlynew toAldabra,I started by questioning the staff to find out whether theyknewoforhadencounteredanyplantspeciesthat are being affected by rats. Throughout thisexerciseIdraftedalistoftheseplantstofacilitatemyfield observation. Then, one day in September (during thedryseason)IwalkedfromtheResearchStationon Picard to the Main Channel (Grande Passe)keeping along the coast. During the observation Iwasassistedbyanotherranger,CatherinaOnezia.Photos were taken to illustrate the impact beinginflicted on several species.

Species being affected varied along the pathdependingontheirabundanceandlifestage.Mostof


R a t s


R a t s o n A l d a b r a

Catharanthus roseus (roz anmer), Solanum aldabrense (zangiv), Stachytarpheta jamaicensis(zepi ble), Pisonia grandis (mapou), Guettarda speciosa (bwa kasan), Cordia subcordata (porse),Maytenus senegalensis (tir bonnen), Polysphaeria multiflora (pti kafe maron), Hibiscus tiliaceus (var),Scaevola sericea(vouloutye).

Waterhasavitalroletoplayinthesurvivaloffaunaand flora in any ecosystem. During the dry season, theonly rodent,Rattus rattus, present onAldabra,may struggle to find water. Maybe through the peeling off of the epidermis rats are able to maintain theirwaterintakethroughoutthedryseason,butaffectingtheplantatthesametime.Insomecasesthewholestemiscutoffwhichprobablymakesthemlosewaterunless they are able to seal the gap. If plants arecontinuouslyaffectedinthiswayitwillhaveaneffectontheirregenerationormightkillthemcompletely.

Fig.2 Vakwa (Pandanus tectorius)damagedbyrats(C.Onezia).

Fig.1 Affectedstemofbwasantal(Acalypha claoxyloides) (C.Onezia).

theplantsbeingchewedwereyoungorthegrowingshoots of mature plants. Rats were seen in broaddaylight eating flowers of Cocos nucifera and alsoimmature fruits were found perforated. Acalypha claoxyloides andColubrina asiatica wereseentobethemostaffectedaroundtheOldSettlement.Insomecasestheprotectiveouterepidermiswaspeeledoffexposingthevascularbundleswhichconductwater,sugar and other substances around the plant. Inothercasesthestemitselfwaschewed(Fig.1&3).Severalspecieswerecoppiced,including Pandanus (Fig 2). Close inspection of damaged branchesrevealed that rats had almost certainly inflicted the damage as there were bite marks, so that it wasunlikely that crabs, birds or insects had producedtheeffects.

We found rat damage on the following plantspecies:

Cocos nucifera (coconut), Acalypha claoxyloides(bwasantal), Casuarina equisetifolia(sed), Apodytes dimidiata (bwa none), Moringa oleifera (bredmouroung),Pandanus sp. (vakwa),Colubrina asiatica(bwa savon), Terminalia catappa (bodanmyen)

Fig.3 Affectedbranchofbwasavon (Colubrina asiatica)(C.Onezia).

Atthemomentwearenotsureiftheratsarehavingthesameeffectintherainyseason.Iftheyareusingplantsforwaterwewouldexpectlessdamageintherainyseason.Asrodentteetharecontinuallygrowing,it is also possible that rats could be chewing onvegetationtoweardowntheirteeth.Ifthishypothesisiscorrecttheratswouldneedtocontinuouslygnawonplants year round, including in thewet season.As rats are clearly having a significant impact on thevegetationofAldabra,whichisofmanagementconcern, I plan to extend the observations into arigorous seasonal sampling protocol, and searchfor other signs that rats are indeed the culprits bylookingfordroppingsbeneathaffectedtreesandbyexaminingstomachcontentsfromtrappedrats.

Acknowledgements

Catherina Onezia for photos provided and field assistance. Sam Bostock and Pierre Pistorius,Research Officer, for help in compiling the report.

A.NegativeeffectsofratsinSeychelles

InaseedsowingexperimentwithCinnamon(kannel)inthemontaneforestofCongoRouge,ChristophKuefferfoundthatin4outof6positions,100%ofseveral100seedswhereremovedorshowedsignsofratpredationwithinaweek.Inthiscase,theimpactofratsmaybepositivebecausetheregenerationcapacityofaninvasivespeciesisreduced,butitindicatesthatseedpredation may also be very high for the rare endemic plants in the mountain forests of theSeychelles.

Willy Andre had a similar experience during the 1960s on Curieuse, where Cocoplum(Prindfrans)wasbeingplantedtostopsoilerosion.Ratsatethegerminatingseedsofthisshrub,thus reducing the efficacy of the erosion control programme. It took 5 years to get rid of the rats usingpoisonedCoconut.ThefactthatCocoplumisnowconsideredinvasiveisbesidethepoint–atthetimeCocoplumwasaveryeffectivetoolforerosionreduction.

BothoftheaboveexamplesareintroducedspeciesbutsuchobservationsarebackedupbyBrendonGrimshaw,whosaysratswilltakefreshlyplantedseedsofnativeplantsfromthesoil(presumablychewingthemupsothattheywillthennotgerminate).Ontheotherhand,hesaysTourtreldezil(Turtledoves)alsotakenewlyplantedseeds,butinthiscaseitispossiblethattheseedscanpassthroughthegutsothatthesebirdsactuallyhelptodisperseplants…

SeveralPCAmembershavereportedendemicspeciesaffectedbyratdamageintheforest,forexampleLatannyenoban(Roscheria),Palmis(Deckenia) andBwabannann(Gastonia spp.)butseveralotherspeciesareknowntobeaffectedinforestareasonMahé(e.g.CongoRouge,Mare aux Cochons) and in the firebreaks on Praslin. The growing tips of plants are eaten and theratschewthebaseofpalmleavestogetsap,sothattheleavesfallordeadleavesarelefthangingontheplant.Ratsmayevengnawthroughthegrowingheartsothatthepalmdies.Theliquid-containingpitchersofpitcherplants(potao)aresometimesfoundwithlargeirregularholesatthebase,indicatingratshavelearnedthatthesealsoareasourceofmoisture.

Inthepast,whentheeconomicallyimportantcoconutindustrywasvitalforSeychelles,ratswereanenormousproblemforplantationownersbecausetheyatetheyoungcoconutsonthetrees.Notonlydidtheownersputpiecesofslipperymetalaroundthecoconuttrunkstopreventratsfromclimbingthetrees,theyalsosometimesplantedavarietyof‘wild’pineapplethatcangrowinpoorsoilandwasteareasinthehopethattheratswouldbeattractedawayfromthecoconutplantations.However,themainformofremovingratsintheolddayswasbytrapping,usinga trapcalleda ‘lasonmwar’madefrombambooandnativeshrubspecies.According toWillyAndre,thesewereusedbythehundreds,laidoutinlonglinesandcheckedeveryday.Inthe1960s,thegovernmentoffered10cperrattail,laterincreasedtoSR1.Thephotosonpage13illustratethemakingofa‘lasonmwar’usingbamboo,‘bwadir’andstring(maker=LindsayChong-Seng)andshowshoweffectiveitcanbeatcatchingrats!

Anotheranimalthataffectsnativevegetationinthewild istheintroducedTenrec(Tang),asmallanimalsimilarinappearancetoaEuropeanhedgehog,whichdigsintoloosesoillookingforinvertebratesandplantmaterialtoeat.AccordingtoWillyAndre,tenrecscausedmuchdisturbancetoseedlingsofTakamakaandMahoganyplantedout inforestryplantations,soforvegetationrehabilitationprojectstheymightalsoproducenegativeeffectsandreducetheeffectivenessoftherehabilitation.


N o t e s f r o m t h e F i e l d

NotesfromtheField

B.PositiveinteractionsbetweenplantsandanimalsinSeychelles

In the days of the first settlement of the granitic Seychelles, giant tortoises were abundant and as their digestive process is rather inefficient, seeds from many species would have been dispersedinthefaeces.OnAldabraAtollthisstillhappensandaresearchprojectinthe1970sshowedthatatleast28plantspeciescanbegerminatedfromtortoisefaeces.Infact,asBrendonGrimshawsays,tortoisesnotonlyspreadtheseedsbutprovideanicepackageoffertilizerforthegrowingseedlingsatthesametime!InhisrehabilitationprojectonMoyenneIslandheusestortoisemanurewhenplantingoutnativeseedlings.

Fruitbatsareimportanttonativeplantsintwoways–asdispersersofseeds(e.g.Kapisen,Takamaka,Bwa-d-nat,Vakwamaron,Bwasousouri)andalsoaspollinators(e.g.Bonnenkarebordmer and Bonnen kare larivyer, Mangliye fler). Of course, fruit bats also spread seeds of introducedspecies,suchasMango,CashewandPonmgouvernman,aswellaspollinatingtheir flowers (e.g. Bwa ber, Kapok, Zanbroza).

InsectsareessentialforthepollinationofverymanyplantspeciesanditissurprisinghowlittleweknowaboutthespeciesinvolvedinthepollinationofSeychelles’nativespecies.JamesMougalandothershavereportedthedestructiveeffectsofanativehawkmothcaterpillaronaveryrareplant–Benzamensovaz–butitisprobablythesamespeciesthatalsopollinatesthe long-spurred flowers! The importance of such specific relationships is illustrated by the caseofVanilla,aplantwhichwasonceimportantasaneconomiccropinSeychelles.Initsnativehabitat,vanilla ispollinatedbyaparticularmoth.Noother insectcando this job,sowherever in the world vanilla is cultivated for the flavoured vanilla pods, the flowers have to be artificially pollinated. In Seychelles, a ‘zig’ is used to lift the flower’s top lip and the flower is pressed vertically with the fingers to bring the pollen into contact with the stigma. Marcel Rosaliecommentedthatwhenhewasaboyheremembersthatthishastobedoneearlyinthemorning when the flower is fresh. Very occasionally Willy Andre has found a vanilla pod in the forest, possibly after a lizard by chance pollinated the flower.

Katy Beaver made a special effort recently to observe the insects visiting an endemicspecies planted in her home garden - Bwa sagay, the small flowers of which have a beautiful but delicate perfume. She reports that many honey bees visited the flowers and also a number of small native bees, various wasp species and a hover fly. Some ants were also crawling over a few flowers. These kinds of observations are needed for allofournativeplantspecies–westillknowsolittleabouttherelationshipsbetweenournativeinsectsandnativeplants,andalsoabouttheroleofgeckosaspollinators.


N o t e s f r o m t h e F i e l d

LindsayChong-Sengmakinga‘lasonmwar’rattrapusingbamboo,‘bwadir’andstringanditshowshoweffectiveitcanbeatcatchingrats(K.Beaver).


M e d u s a g y n e

Using Population Studies to SetConservationPriorities:ACaseStudyinSeychellesUsingthe Critically Endangered Bwamediz(Medusagyne oppositifolia)

ByDenisMATATIKEN

Director,BotanicGardens,[email protected]

Plantscanbenaturallyrareorhaveraritiesimposedupon them. Medusagyne oppositifolia (Bwa medizor Jellyfish tree) is a naturally rare endemic plant of theSeychelles,restrictedtofoursmallpopulationsatintermediatealtitudeonthegraniticislandofMahé.The populations have been said to consist of nomorethan50matureindividualtrees,withnonaturalregenerationrecordedinthewild.Molecularstudiesby Fay et al. (1997) showed that Medusagyneis a very distinct species, the sole member of itsfamily. Hence, it has been identified as a relict of Gondwanaland flora that should be considered a priority for conservation (Vane-Wright et al., 1991)– a flagship species for Seychelles in fact - and currentlylistedascriticallyendangered.

AspartofmyMScstudiessponsoredbytheBritishCouncil, I carried out a field survey of MedusagyneatBernica,Copolia,MontJasminandMontSebertto establish the demography (population size,range and population structure) and distribution ofMedusagyne in order to use these for prioritisingconservationofthespecies.Theglacisareaswherethis species grows are often difficult to access, full of largebouldersandnoteasytoexplore,sothestudyprovedquiteadventurous!

The results of my detailed field survey showed that thepopulationofMedusagyne waslargerthanhadbeen thought,withmore than80mature treesanda large number of seedlings. But of the four sub-populations, only that at Bernica was apparentlyregenerating.Intheotherthreeplacestherewereafew mature flowering trees but with no regeneration at all.Moreover,evenatBernicamostoftheseedlingswerearound20cmwithveryfewseedlingsreaching1metre,sothereisnoguaranteethatanywillreachmaturity.

Inaddition, I collected informationonwhere in theworld(BotanicGardens)thespecieswasbeinggrownex situandalsothemethodsusedforitspropagation.

It turns out that plants in ex situ collections weremostly derived from the population at Bernica andpropagationbyseedswasmostsuccessful,althoughmany plants failed to survive beyond the seedlingstage.

The categorisations used by IUCN for classifyinghowendangeredaplantspecies is(seep.15)arenowverysophisticated,butwhatdotheytellusabouttheconservationofaspecies?Basicdemographicknowledgeisneededforthecategorisationbutoncewehavethisinformation,isitenoughtoknowthataspeciesisforexamplecriticallyendangered?Canit help us to actually conserve the species? Sinceresources for conservation are always limited can

detaileddemographicstudieshelpusprioritise?

I believe that this study has shown us thatdemographicstudiescanindicatewhereweneedtoputoureffortsintermsofconservation,inthiscaseofMedusagyne oppositifolia.ThepopulationofBernicais more likely to survive without any human influence than are the much smaller populations at higheraltitudewhichhavenonaturalregenerationandnospecimens ex situ.These tiny sub-populations aremorevulnerabletoextinctionandshouldbeprioritisedforconservation.Ex situconservationinthecaseofMedusagynemaybetheonlywaytoconservethegeneticdiversityofthewholepopulation.

ReferencesFay,M.,Sensen,S.andChase,M.(1997).

Taxonomic affinities of Medusagyne oppositifolia(Medusagynaceae).Kew Bulletin52,111–120.

Vane-Wright,R.I.,Humphries,C.J.andWilliams,P.H.(1991).Whattoprotect?-Systematicsandtheagonyofchoice.Biological Conservation55,235–254.

Bwamediztree(L.Kronauer)andimmaturefruits(inset,E.Schumacher).


R e d L i s t P r o j e c t


M e d u s a g y n e

Suggested IUCN Red List StatusfortheEndemicWoodyPlantsoftheInnerSeychelles

ByMichaelHUBERandSaschaISMAIL

InstituteofIntegrativeBiology(formerGeobotanicalInstitute)[email protected];[email protected]

For the Seychelles, no recently updated Red Listfor flowering plants exists.The assessment for Seychelles registered at the moment with IUCN isnotverydifferentiated, i.e.mostof thespeciesareclassified as ‘vulnerable’ due to their restricted range andafewspeciesarenotassessedatall.Themostcomprehensive, but not officially acknowledged, Red Lists of Seychelles were compiled by Procterin 1971 and by Carlström in 1996. Therefore, thepreparationandpublicationofanewRedListwasstatedassub-target2bintheNationalStrategyforPlantConservation2005-2010(seep.18).Alreadyin 2004, PCA started a project with the aim toproducesuchanupdatedRedDataassessmentofall flowering plants with the scientific support of the Instituteof IntegrativeBiology (ETHZurich, formerGeobotanicalInstitute)(seeBollier&Tanner2004).In this project, thus far, data on the abundance ofendemic woody plants had been collected fromunderstudiedareas (Bollier&Tanner2004),andadatabasewaspreparedthatisinlinewiththeIUCNassessmentmethodology(Burgeretal.2005).

ForthethirdphaseoftheRedListproject,westayedinSeychellesfromMayuntilAugust2006todoourmaster thesis in environmental sciences at ETHZurich.Inourstudy,the55woodyspeciesendemicto the inner Seychelles were classified based on the availableinformationandknowledge(applyingIUCNRedListcriteriaVersion3.1).AccuratedataontheendemicplantsofSeychellesusefulforaquantitativeassessment was scarce. The perfect assessmentshould certainly be based on recent field data.However, a research project for the determinationof the threat categories for all the endemic plantsof Seychelles based on new field data would need a huge amount of resources. Therefore availableinformation for each plant was compiled andanalysed. Reports on plants and vegetation, backto 1877, were incorporated in this study. Becausethedatausedwasoftenoutofdate,theprocessedinformation for the assessment had to be verified

andupdated.AveryeffectivewayofimprovingandupdatinginformationwastheincorporationofexpertknowledgewithaworkshopheldinAugust2006andwithinterviews.Thisevaluationrevealedforinstancethat the presence of Campnosperma on Praslinreportedintheliteratureisimprobable.

For one species, Bwa de Fer (Vateriopsis seychellarum), we conducted a population survey.This was the first entire survey of this extremely rare and evolutionary unique species. The surveyrevealedthatthespeciesisstillpresentinahighernumber of individuals and in more sites than haspreviouslybeenthought.Intotal58trees(diameteratbreastheight>10cm),59saplings(height>50cm)and385seedlings(height<50cm)wererecordedinninesitesonMahé.

As a result of our project, for each species a factsheet was prepared in which the five IUCN criteria are discussed. Of the 55 endemic woody species,two were classified as ‘extinct’, 14 as ‘critically endangered’,sixas‘endangered’,22as‘vulnerable’,andtenspeciesas‘nearthreatened’or‘leastconcern’.One species has to be regarded as ‘data deficient’ (forthedetailsoftheassessmentseeHuber&Ismail2006). It is important to note that many endemicspecies apparently occur only on one island (e.g.MahéorSilhouette),andonlysomecoastalspeciessuchasVakwabord-d-mer(Pandanus balfourii)andLafousptifey(Ficus reflexa)arewidespreadalsoonthesmallislands.

Compared with the present IUCN Red List forSeychelles, this classification represents an improvementforthewoodyendemicspeciesoftheinnerSeychelles,becausetheassessmentwasmadewith enhanced differentiation. Additionally, speciesthat are missing on the present official IUCN Red List werealsoassessed. Insummary,wecompiled the

AyoungleafofBwadeFer(Vateriopsis seychellarum) (S.Ismail).


N o r t h I s l a n d P r o j e c t

datanecessaryforthesubmissionofanewRedListassessment to IUCN.Although such a submissionwouldbeagreatstepforplantconservationeffortsinSeychelles,onehastokeepinmindthattheIUCNRedListisbasedonamethodologyforassessingtheextinctionriskofaspeciesfromaglobalpointofview.That means that the classification is quite coarse. On a national level the IUCN Red List could serve asaroughorientationtofocusconservationeffortsonthe most threatened plants, but, additionally, moredetailedstudiesareneededonthemostthreatenedspecies(seep.14).

ReferencesHuberM.&S.Ismail2006.SuggestedIUCNRed

ListstatusoftheendemicwoodyplantsoftheinnerSeychelles,Masterthesis,InstituteofIntegrativeBiology,ETHZurich,Switzerland.

BollierR.&I.Tanner2004.SeychellesplantRedListproject,Kapisen1,p.8.

Burger M., N. Stampfli & J. Mougal 2005. Red Data list project–Phase2.Kapisen3,p.14-16.

LinkfortheIUCNquestionnaire:http://app.iucn.org/webfiles/doc/SSC/RedList/Red_List_Assessment_Datasheet.doc

NorthIslandVegetationRehabilitationUpdate

ByLindaVanherck,NorthIsland&KatyBeaver,PCA

[email protected]@seychelles.net

After the purchase of North Island by WildernessSafaris in 1997, and a thorough initial impactassessment, North Island initiated a vegetationrehabilitation programme in 2003. Several expertswereactivelyconsultedforadviceonhowtotaketheprocessforward.Considerableprogresswasmadein 2005 when the island joined the ICS-led FFEMproject on Rehabilitation of Island Ecosystems, inwhichPCAhasanactiveadvisoryrole(Kapisen4,p. 6). During 2006, another two masters students(MartinHertachandClaudiaFarrér,fromPCApartnerInstituteofIntegrativeBiology,ETHZurich)spent11weeksontheislandcarryingoutthesecondannualmonitoring,improvingthemonitoringprotocolssetinplace by their predecessors in 2005, and devisinga new methodology for monitoring the freshwaterwetlands. They also worked on the island’s digitalherbarium, increasing the number of speciesrepresentedto110.

Meanwhile theEnvironmentandLandscape teamsontheislandwerehardatworkin2005,alongwithICSpersonnelandotherexperts,riddingtheislandof rats. Intensive post-eradication monitoring fromSeptember 2005 to September 2006 has confirmed that the islandhasnowbeen rat-free forwelloverone year. However, the island has to continue

preventinganyre-introductionsofalien invaders tomaintain its rat-free status, a demanding task withboatarrivalsonadailybasis.Protocolsareinplaceand actively adhered to for ensuring that rats donotreturnorotheralieninvadersenter.Removalofratsisgoodnewsforallthenativeplantsthathavebeenplantedaspartofthevegetationrehabilitationon the island. More than 9 ha have now beenrehabilitated,withcontinuingmaintenanceandextraplanting as necessary. Much of the restored area

Removalofcoconuttrees(L.Vanherck).

is on the western plateau, together with an areaalong thesaddlebetween thewestbeachand theeastern plateau. Hundreds of alien species havebeenremoved,particularlyinvasivespeciessuchasVyey fiy (Lantana)andPokPok(Passiflorafoetida),small Kalis dipap (Tabebuia), Bwa zonn (Alstonia)and Rousay (Eugenia uniflora), and also manycoconut seedlings. Many of the coconut palms onNorth Islandarenowold, theremainsofextensiveplantations that were once very productive, and


N o r t h I s l a n d P r o j e c t


P C A N e w s

manyofthesewillgraduallyberemovedinselectedareas.Intheplaceofthealienspecies,almost3000nativetreesandshrubshavealreadybeenplantedand the North Island nursery still has plenty moreready toplantout.Thisall representsagreatdealofworkanddedication, including support from theBiodiversity Centre on Mahé via the supplying ofseedsandcuttings.

A major step forward will be the finalisation of the Vegetation Management Plan 2007-2011, withPCAandNorthIslandcollaborating,alongwithICSinput.Aholisticecosystemapproachisbeingtaken,acknowledgingthatvegetationisnotonlyimportantinitsownrightbutalsoformsthebasisofanyislandecosystem and creates habitats for the island’sanimals. Indeed we cannot just remove all alienspecieswithouttakingintoconsiderationforexampletheeffectsuchadrasticinterventionmighthaveonanimals,whichnowusethemforroostsandnestingsites.WhenchoosingthenativeplantspeciesmostsuitablefortheparticularconditionsonNorthIsland,itisalsonecessarytoplanforthefutureintroductionofanimalspeciessuchastheSeychellesWhite-eyeandSeychellesterrapins.Itisalsonecessaryforthemanagementplan to take intoconsideration insectpestsanddiseasesthatareontheisland.

PlantingofendemicplantsonNorthIsland(L.Vanherck).

PCANEWS

Firstly we are very proud to report that two more PCA members have achieved further qualifications. DenisMatatikenhascompletedaMastersdegree(withdistinction)inBotanicalConservationatPlymouthUniversity(UK)(seep.14),andEvaSchumacheraDoctorateinPlantEcologyatETHZurich,Switzerland.Congratulationstothemboth!

Terrence Mahoune showing Angraecum eburneum onAldabra(L.Chong-Seng).

Lindsay Chong-Seng and Didier Dogley have recentlyreturnedfromashorttriptoAldabrawheretheywereabletoinitiatesomevegetationmonitoring.Monitoringofsomeofthemost commonplant specieswill help to reveal environmentalchanges that may result from global climate fluctuations, and knownpopulationsofafewrarespecieswillalsobemonitored.A search for several plants that had been recorded in specific areasbyFosbergandRenvoize in theirFloraofAldabrawasunsuccessful. However, Lindsay and Didier did find 5 new populations of Angraecum eburneum orchid in a locationwhereonlyonepopulationhadpreviouslybeenrecorded–andthese were found in a period of only 20 minutes, so furthersearchingcould turnupmore.Didieralso returnedwithmoreseedstogrowintheAldabrasectionoftheBiodiversityCentreonMahé,whichwillenablepeopletogettoknowtheverydifferentvegetationoftheAldabragroupofislands.

Anotherbookletistobepublishedverysoon,thistimebytheBotanicalGarden.AcolourfulandinterestingguidetotheGardenitself,itwillhelptofocusattentiononthemanyusesofplantsinourlivesaswellastheirbeauty,atalocation,whichisvisitedbytouristsandlocalsalike.

Lastbutnot least,anewprojectcollaboration isbeing initiatedbetweenProfessorJabouryGhazoulandChristopherKaiseratETHZurich/ImperialCollegeLondonandDidierDogleyandDenisMatatiken(MinistryofEnvironmentandNaturalResources)andseveralmembersofthePCA.ChristopherdidhisPhDinMauritius(seep.6)andwillcontributewiththisexperiencetotheproject.TheaimofthiscollaborationistounderstandsomeoftheecologicalandgeneticbarrierstoregenerationandviabilityofsomeofthefascinatingbutrareplantspeciesendemictoMahé.Induecourse,theworkwillincludeeducationandoutreach,andrestorationofsomeinselbergplantpopulationswiththehelpofexpertsfromtheEdenProject,UK.


P C A P u b l i c a t i o n s

SeychellesNationalStrategyforPlantConservation2005-2010

GuidetoEndemicPalmsandScrewpinesoftheSeychellesGraniticIslands

byDenisMatatikenandDidierDogley

PublishedbythePlantConservationActiongroup(PCA)

Thisprintedguidegivesyoualltheinformationandpho-tographsyouneedtoidentifythesixendemicpalmsandfourendemicvakwa(pandans)ofthegraniticSeychelles.It is the first in a series of booklets to be published on the endemicandindigenousspeciesoftheSeychellesgrani-ticislands.

ThepaperbackisonsaleatAntigonebookshop,VictoriaandValleedeMaishop,PraslinandotheroutletsatapriceofSR75.

Overseas orders: Now available on the Natural HistoryBookServicewebsitehttp://www.nhbs.com

AnyindividualororganisationwantingacopyshouldcontactJamesMougalatBotanicalGardens:Phone:670500Email:[email protected]

JoinPCA!AnypersoninterestedinplantconservationintheSeychelles,eitherfromtheSeychellesorsomewhereelseintheworld,isinvitedtojointhePlantConservationActiongroup(PCA).AsamemberyousupportplantconservationintheSeychelles,getKapisen-thePCAnewsletter-twiceayearsenttoyoubye-Mail, and get regular invitations to events and field excursions.

ForjoiningPCA,contactDidierDogley(Chairman)orDenisMatatiken(Secretary)at

E-Mail:[email protected]

Phone&Fax:(+248)266903

Kapisen - pcaseychelles.org Plant Conservation Action group Newsletter December 2006 Issue 6 The...

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