Biodiversity...Genetic differentiation between willow populations 17 Mycology 18 Ectomycorrhizal...

Biodiversitytaxonomy, Genetics and ecologyof sub-Arctic Willow scrub

A collaborative research project by the scottish Montane Willow research Group

introduction 3

sub-arctic willows 4

sub-arctic willow scrub 6

the situation in scotland today 7

research questions 8

study sites 9

taxonomy 10

Patternsofhybridizationamongsub-arcticwillowsinScotland 11

PatternsofhybridizationbetweenS. arbusculaandS. lapponum 12

DynamicsofhybridizationbetweenS. arbusculaandS. lapponum 13

Genetics 14

Sexualversusasexualreproduction 15

Geneticdiversitywithinwillowpopulations 16

Geneticdifferentiationbetweenwillowpopulations 17

Mycology 18

EctomycorrhizalfungiassociatedwithS. herbacea 19

Sub-arcticwillowsandrustfungi(Melampsoraspp.) 20

Ectomycorrhizalcolonizationpotentialofuplandsoils 21

ecology 22

Herbivoryandseedproduction 23

PredictingthepotentialdistributionofS. arbuscula 24

Herbivoryandseedlingestablishment 25

Conservation implications 26

Taxonomy 26

Genetics 26

Mycology 28

Ecology 29

Further information 30

Contents

Allphotographicimagesincludedinthisreportweretakenbymembersoftheprojectduringthecourseoftheresearch.

Thespeciesdistributionmapsonpages4-5arereproducedfrom:Preston,C.D.,Pearman,D.A.andDines,T.D.(Eds.)(2002).NewAtlasoftheBritishandIrishFlora.OxfordUniversityPress.©Crown,2002.

Citation:ScottishMontaneWillowResearchGroup(2005).Biodiversity:taxonomy,geneticsandecologyofsub-arcticwillowscrub.RoyalBotanicGardenEdinburgh.

PrintedonReviveSpecialSilk,madefrom30%FSCfibre,30%de-inkedpost-consumerwaste,30%virginfibreand10%millwaste,byMeigleColourPrintersLimited.

� B i o d i v e r s i t y: tA x o n o M y, G e n e t i C s A n d e C o lo G y o F s u B - A r C t i C W i l lo W s C r u B

Sub-arcticwillowscrubisoneoftherarestandmostendangeredhabitatsintheUK.ItisalmostentirelyrestrictedtotheScottishmountainswhereitformsacomponentofthemontanescruboccurringabovethenaturaltreeline.

Remainingsub-arcticwillowscrubexistsasisolatedpopulationsthatareconsideredtoberemnantsofaformerlymorewidespreadpost-glacialvegetationtype.Thesesurvivingfragmentsarethesubjectsofacuteconservationconcernand,withoutintervention,manypopulationsareindangerofterminaldecline.

TherareandthreatenedstatusofthisvegetationtypeisrecognizedbyitsinclusioninAnnexIoftheEuropeanHabitatsDirectiveandsubsequentprioritizationforconservationwithintheUK.Oneofthespeciesincludedinthisvegetationtype,S. lanata,islistedintheBritishRedDataBookofVascularPlantsandisthesubjectofaSpeciesActionPlanthatsetsouttargetsforitsconservation.

Thisbookletpresentsasummaryofthefindingsofalargecollaborativeresearchprojectthatranfrom2002-2005andaimedtoprovidetheunderpinningscientificresearchrequiredfordeterminingthemostappropriatestrategiesformanagementandspeciesrecoveryprogrammesforsub-arcticwillows.

introduction

A C o l l A B o r At i v e r e s e A r C h p r o j e C t �

Salix lapponum

Willows(Salix spp.)belongtothefamilySalicaceaethatconsistsofdioecious(separatesexes),catkin-bearingtreesandshrubswithsimple,alternateleaves.Salixspeciesarebelievedtobeprimarilyentomophilous(insect-pollinated)andpartiallyanemophilous(wind-pollinated).Thesmallseedsarecharacteristicallyenvelopedinlong,soft,silkyhairsanddispersedbywind.

MontanewillowscrubcommunitiesinScotlandconsistofmixturesofspecieswhich,elsewhere,havearctic-subarctic-alpinedistributions(S. arbuscula, S. lanata, S. lapponum, S. myrsinites, S. reticulata)andwillowspeciesofgeneralnortherlydistribution(S. herbacea, S. myrsinifolia, S. phylicifolia).

Fivespeciesofsub-arcticwillowandoneofthemorecommon‘northerly’willowswereincludedinthisresearchproject.

Salix arbuscula (Mountain willow)Conservationstatus:SCARCE.

Salix herbacea (dwarf willow)Conservationstatus:COMMON.

sub-arctic willows

Recordedin3210x10kmsquaressince1970,allinScotland.

Recordedin33510x10kmsquaresinGreatBritainsince1970.

Salix lapponum (downy willow)Conservationstatus:SCARCE.

Recordedin8310x10kmsquaresinGreatBritainsince1970.

Mapkey1987-1999Native1970-1986NativePre-1970Native


S. lanata SpeciesActionPlan

S. lanataisincludedintheBritishRedDataBookofVascularPlants.Itisextantatonly14localitiesinScotlandandonlyfiveofthesepopulationsarecurrentlyconsideredtobeviable.TheSpeciesActionPlanforS. lanataincludesthefollowingtargets:

ensurethatallpopulationsarerestoredtoastatecapableofregeneratingby2008

ensurethateachpopulationwillconsistofatleast50plants(orthesustainablemaximumforthesite)by2008

reintroducethespeciestotwoformersitesby2003.Salix lanata (Woolly willow)

Conservationstatus:RARE&VULNERABLE.Recordedin1310x10kmsquaressince1970,allinScotland.

sub-arctic willows

Salix myrsinites (Whortle-leaved willow)Conservationstatus:SCARCE.

Salix reticulata (net-leaved willow)Conservationstatus:SCARCE.




sub-arctic willows

Sub-arcticwillow scrub

Underfavourableconditions,sub-arcticwillowscanformextensivescrubcommunities.InGreatBritainthesehavebeenclassifiedundertheNationalVegetationClassificationasW20–Salix lapponum–Luzula sylvaticascrub.Thistendstooccuronmoist,relativelybase-richsoilsinrockysituationswithanorthtoeastaspect,generallyataltitudesfrom600mtoover900m.Adegreeofsheltermaybefavourabletoscrubdevelopmentandtheremaybeapositiveassociationwithlatesnow-liewhichofferssomeprotectionfromspringfrostsandbrowsing.

DevelopedscrubcommunitiestendtobedominatedbyS. lapponumwhichisthecommonestandmostwidelydistributedofthesub-arcticwillowsbutcanincludesomeoralloftheotherspeciesaswellashybrids.Associatedvascularplantsincludesub-shrubssuchasVaccinium myrtillus, V. vitis-idaeaand Empetrum nigrum;tallherbssuchasAlchemilla glabra,Rhodiola rosea, Oxyria digynaandSaussurea alpina;smallherbssuchasAlchemilla alpina, Thalictrum alpinumandPolygonum viviparum.

S. lanatawithOxyria digyna S. arbusculawithSaxifraga aizoides

WelldevelopedwillowscrubatCorrieSharroch,GlenDoll


sub-arctic willows

The situation in Scotland today

BasedoncomparisonswithScandinaviaandthedistributionofsuitableterrain,itisgenerallyconsideredthatsub-arcticwillowscrubwasoncemorewidespreadinScotlandthanitistoday.Cuttingforfirewoodandcharcoal-burningcoupledwithmorerecentintensificationofgrazingpatternsinuplandareashasresultedinasituationwheremontanewillowcommunitiesarenowlargelyrestrictedtoinaccessibleledges.Consequently,willowpopulationsaretypicallysmallandisolatedandofacuteconservationconcern.

Remainingwillowscrubisconfinedlargelytoinaccessibleledges

Samplinginaccessiblewillows


Conservationactionrequiresunderpinningscientificresearch.Attheoutsetofthisprojectitwasapparentthatthereareanumberofknowledgegapsthatneedtobeaddressedifconservationtargetssetforsub-arcticwillowinScotlandaretobeachieved.Examplesoftheseareasfollows.

WillowsarenotoriousfortheirtaxonomiccomplexityandnumeroushybridcombinationshavebeenrecordedintheUK.Dosub-arcticwillowsexistasseparatewell-definedtaxonomicentitiesforwhichconservationplanscanbedevisedorishybridizationsoextensivethatthesewillowsshouldeffectivelybetreatedasonelargeaggregate?

Smallandisolatedplantpopulationsareoftenfoundtobelowingeneticdiversity.Thistendstolimittheircapacitytorespondtobothacuteandchronicenvironmentalchange.Furthermore,smallnumbersofindividualsinpopulationscanleadtoproblemsthroughinbreedingdepression.Therefore,hasthefragmentationofwillowscrubresultedingeneticallydepauperatepopulationsthatmaybelackinginvigourandill-equippedtorespondtofutureconditions?

Inattemptingtorestorewillowscrub,isenoughknownaboutassociatedorganismssuchasfungi?Forexample,itisknownthatspeciesofSalicaceaeformmycorrhizalassociations.Isthissomethingthatshouldbetakenintoaccountwhenwillowsarebeingplanted?

Grazingofwillowseedlingsandsaplingsbyherbivoresinhibitsnaturalregenerationofwillowscrub.However,herbivoresmayaffectthereproductivecapacityofwillowsinotherways.Forexample,howdoesremovalofshootsbysheepandreddeerinfluencecatkinproduction,seedsetandhencepopulationviability?

research questions

Researchaims:Ourresearchwascarriedoutunderfourbroadheadings:taxonomy,genetics,mycologyandecology.


Sampleswerecollectedfrommanysitesrepresentingthefullrangeofsub-arcticwillowdistributionacrossScotland.However,intensivecross-cuttingresearchwascarriedoutatfourfocalstudysites.

study sites

BenLawersEffectoflargeandsmallmammalherbivoryonreproductivebiologyofS. arbuscula,seeddispersal,potentialestablishmentsites,ectomycorrhizalcolonizationpotentialofsoils.

MeallnanGabhar,BenLuiHybridizationstudiesofS. lapponumandS. arbuscula.

CorrieSharrochAssessmentofclonalgrowthofS. lanataandS. lapponum,assessmentsoftaxonomicstatus,rustinfection,insectherbivoryandphytochemistryofS. lanata,S. lapponumandS. myrsinites.

MeallGhaordiadhAssessmentofclonalgrowth,ectomycorrhizalcolonizationandinsectherbivoryofS. herbaceaontheridge-top.HybridizationstudiesofS. lapponumandS. arbusculaonthecragsbelow.


1 0 B i o d i v e r s i t y: tA x o n o M y, G e n e t i C s A n d e C o lo G y o F s u B - A r C t i C W i l lo W s C r u B

Willowsarewell-knownfortheirtendencytohybridise.Therearecurrently64willowhybridcombinationsrecordedintheUKbutwedonotknowtheextenttowhichhybridizationoccurswithinnaturalpopulations.Dowillowspecieslimitsremainwell-definedwithonlyoccasionalhybridizationeventsorishybridizationinfactmuchmorefrequentandwidespread?Underwhatcircumstancesdoeshybridizationoccur?

Thisisimportantfromaconservationperspectiveasthedevelopmentofappropriatestrategiesandtargetsrequiresasoundunderstandingofthetaxonomicstatusoftheplantswewishtoprotect.Forexample,ifonestrategyforconservationistoaugmentexistingpopulationsorestablishnewonesbyplanting,shouldeffortsbemadetoavoidinclusionofhybridsamongplantingstock?Orarehybridsinfactsocommoninnaturethatinclusionofhybridsinrestorationprogramsisinevitable?

Astherangeofphenotypicvariationinwillowhybridsispoorlyunderstoodwedevelopedmoleculartoolsthatwouldenableustodiscriminatebetweenspeciesanddetecthybrids.Toprovidecomplementarydatawealsoemployedphytochemicaltechniquesthatwerefoundtosuccessfullydistinguishspecies.Wethenusedthesetoolstogetherwithmorphologicalmethodstoinvestigatethreetopics.

1. Patternsofhybridisationamongsub-arcticwillowsinScotland.2. PatternsofhybridizationbetweenS. lapponumandS. arbuscula.3. DynamicsofhybridizationbetweenS. lapponumandS. arbuscula.

taxonomy

SamplingS. lapponumatDrumochterPass

S. lapponum

S. x pseudoglauca

S. arbuscula

LeafmorphologyofS. lapponum,S. arbusculaandtheirhybrid,S. x pseudoglauca

A C o l l A B o r At i v e r e s e A r C h p r o j e C t 1 1

Whatcanmolecularstudiestellusaboutthepatternsofhybridizationamongsub-arcticwillowsinScotland?Ishybridizationcommonorrare?

ManysamplesofelevenspeciesofwillowwerecollectedfromsitesacrossScotlandaswellasexamplesofhybridsidentifiedbytheirmorphology.Wealsocollectedsamplesfrommorphologicalhybridspecimensfromanextensiveex-situcollectionofnativewillows.DNA-fingerprintingtechniqueswereappliedanddataanalysedtodetectpatternsofhybridization.

Theextentofhybridizationappearstobelimitedwithmosthybridsoccurringonlyoccasionally.AnexceptiontothisishybridizationbetweenS. arbusculaandS. lapponumwhichoccursfreelyatsomesites.

Whereitispossibletodistinguishmorphologicalhybrids,hybridizationinsub-arcticwillowsappearstofollowoneofthreepatternsA,BorC(Figures1and2):

taxonomy

Patterns of hybridization among sub-arctic willows in Scotland

Figure 1/PatternA.Morphologicalhybridsaremolecularlyintermediate(e.g.,S. auritaxS. repens).

Figure 1/PatternB.Morphologicalhybridsareeitherintermediateoraremorecloselyalliedtoeitheroftheparentspecies,suggestingback-crossing(e.g.,S. herbaceaxS. lapponum).

Figure 1/PatternC.Morphologicalhybridsalwaysfallwithintherangeofmolecularvariationofoneorbothparentspecies(e.g.,S. capreaxS. lapponum).Asnogeneticallyintermediateindividualsoccur,itiscurrentlydifficulttosaywhethertheobservedpatternisduetoback-crossingorextrememorphologicalvariationintheparentspecies.

Figure �.Patternsofhybridizationbetweensub-arcticandmontanewillowspecies.SeeFigure1fordescriptionofpatterns.

Figure 1.Threepatternsofhybridizationamongsub-arcticwillows.Distancebetweenpointsapproximatestherelativegeneticsimilarityofpairsofsamples.Seelegendtextfordescriptions.

1 � B i o d i v e r s i t y: tA x o n o M y, G e n e t i C s A n d e C o lo G y o F s u B - A r C t i C W i l lo W s C r u B

taxonomy

Patterns of hybridization

betweenS. arbuscula and

S. lapponum

Arethepatternsofhybridizationthatwerevealedforparticularhybridcombinationsconsistentacrosssitesorcanwedetectdifferencesbetweensitesthatmightthenoffersomeinsightsintofactorsthatinfluencethisprocess?

TwositeswereselectedwhereS. arbusculaandS. lapponumgrowtogether(MeallGhaordiadhandMeallnanGabhar,BenLui).Patternsofhybridizationatthetwositeswerecomparedusingacombinationofmorphologicalandmoleculartechniques.

Thepatternsofhybridizationatthetwositesweredifferent.AmuchhigherincidenceofmorphologicalhybridswasrecordedatMeallGhaordiadhthanatMeallnanGabhar.

AtMeallnanGabhar,themorphologyofthetwohybridsfoundwasclearlyintermediatebetweentheparentspecies.However,theirmolecularfingerprintsclusteredwithintheparentspecies(Figure3).Thisindicatesthatthesehybridindividualsareprobablyderivedfromback-crossingofhybridstoeitherparentwiththetransmissionofmorphologicalcharacterstatesfromtheotherparent.

AtMeallGhaordiadh,themorphologyofmostofthehybridswasalsointermediate.However,themoleculardataweremorecomplexwithsomehybridsfallingwithintherangeoftheparentsandsomebeingintermediate(Figure3).Thepresenceofintermediateindividualsleadstomoreofageneticcontinuumbetweenthetwospeciesatthissite.

Thesedataindicatethatpatternsofhybridizationbetweenthesametwospeciescanvarybetweensites.

Figure �.Comparisonofmorphological(A)andmolecular(B)variationinS. arbusculaandS. lapponumandhybridsbetweenthematMeallnanGabhar(1)andMeallGhaordiadh(2).

A1 B1

A2 B2

A C o l l A B o r At i v e r e s e A r C h p r o j e C t 1 �

taxonomy

Dynamics of hybridization between S. arbuscula and S. lapponum

HavingdetecteddifferentpatternsofhybridizationatMeallGhaordiadhandMeallnanGabhar,weaimedtoinvestigatefactorsinvolvedinmaintainingspeciesbarriersandthecircumstancesunderwhichhybridizationbetweenS. lapponumandS. arbusculaoccurs.

Atthetwositeswecountedtherelativenumbersofplantsofthetwospeciesandrecordedthefloweringtimeofalargenumberoftaggedplantsatweeklyintervalsduringthefloweringseason.

Relativeabundancesofthetwospeciesweredifferentatthetwosites.AtMeallnanGabhar,thenumberswereroughlyequal.However,atMeallGhaordiadhthereweremanymoreindividualsofS. arbusculathanofS. lapponum (ca.30:1).

TheassessmentoffloweringdatesshowedacleartendencyforS. lapponumtoflowerbeforeS. arbusculaatbothsites(Figure4).

AtMeallnanGabharneitherofthehybridsfloweredduringthetwoyearsofobservation.AtMeallGhaordiadh,morphologicalhybridsweredetectedthatfloweredatintermediatedatesbetweenthetwospeciesaswellasoutwiththerangeofoverlapbetweenthefloweringtimesbetweenthetwospecies(Figure4).Thiscouldincreasetheprobabilityofintrogressionthroughback-crossingineitherdirectioniftherewasnoselectionagainsthybridgenotypes.

Thesedataareconsistentwithhybridizationtheorythatpredictsthatwheretwospecieswiththepotentialtohybridizeco-occurindisproportionatenumbers,hybridizationismorelikelytotakeplace.Wherefertilehybridsaregeneratedasinthepresentcase,introgressionofgenesbetweenspeciesmayaccentuatethebreakdownofspeciesbarriers.

Figure �.FloweringdateofS. arbuscula,S. lapponumandtheirhybrid,S. x pseudoglauca,attwosites.


GeneticsFragmentationofvegetationcoverintosmallandisolatedpopulationscanresultinseriouslossesofgeneticdiversitywhichcanhinderaspecies’abilitytorespondtobothacute(short-term)andchronic(long-term)environmentalchange.Smallpopulationscanalsobeaffectedbyinbreedingdepressionduetotheincreasedchanceofmatingamongrelatedindividuals.Subsequentexpressionofdeleteriousrecessiveallelescanresultinreducedvigourandfitness.

Itisbelievedthatsub-arcticwillowpopulationsintheUKareremnantsofapreviouslymorewidespreadvegetationtype.Giventhesmallsizesandpatchydistributionofmanyoftheremainingpopulations,itispossiblethattheyconsistofrelatedindividualswithlowlevelsofgeneticdiversity.Suchpopulationswouldbeapoorsourceofdonormaterialforreintroductionprogrammes,andmaythemselvesbepoorcandidatesforconservationmanagementduetointrinsiclowlevelsoffitness.

Theamountofgeneticdiversityavailableinremainingpopulationsisrelatedtotheamountofsexualreproductionoccurringwithinandbetweenthem.Willowsarealsocapableofreproducingasexuallyviathespreadofclonalsuckersandattheoutsetofthisprojectwedidnotknowwhethersub-arcticwillowsreproduceprimarilysexuallyorasexually.Anunderstandingofthiscrucialaspectofwillowbiologyisnecessaryifrestorationprogrammesaretosuccessfullyimitatenaturalpopulations.

Wedevelopedmoleculartoolsthatwouldenableustodifferentiateindividualwillowgenotypes.Thesetoolswerethenappliedtonaturalpopulationsofsub-arcticwillowsacrossScotlandtoinvestigatethreetopics.

1.Theextentofsexualversusasexualreproduction.2.Theamountofgeneticdiversitywithinwillowpopulations.3.Theamountofgeneticdifferentiationbetweenwillowpopulations.

DNAmicrosatellite‘fingerprints’ SamplingS. lapponumatCreagMegaidh


Genetics

Sexual versus asexual reproduction

Sexualrecruitmentinwillowpopulationsoftenappearstobeverylimitedandweknowthatwillowshavetheabilitytospreadvegetativelyviasuckers.Whatproportionoftheindividualbushesthatweobserveinapopulationisderivedfromsexualreproductionandwhatproportionfromasexual,vegetativegrowth?

Leafsampleswerecollectedfromover400closelyspacedbushesofS. lanataandS. lapponumatCorrieSharrochandfromS. herbaceaat90pointsonanexposedridge-topatMeallGhaordiadh.Samplesweregenotypedusingmoleculartechniques.

99%ofS. lanataand95%ofS. lapponumsamplesrepresenteduniquegeneticindividuals.

28%oftheS. herbaceasamplesrepresenteduniquegeneticindividuals.Sampleswithidenticalgenotypesshowedstrongspatialaggregationwithonegenotypebeingatleast8macross(TransectF,Figure5).

DespitefieldobservationsofsexualreproductioninS. lanata andS. lapponumbeingrare,thisappearstobetheirmainmechanismofreproductionanddispersal.ThepatternobservedinS. herbaceasuggestsgreaterlevelsofclonalgrowthandpatchformation.Thismatcheswellwiththematformingrhizomatousgrowthofthespeciesandthemoreopenhabitatinwhichitoccurs.

Figure �. DistributionofS. herbaceagenotypesalongsixtransectsof8mlengthatMeallGhaordiadh(nottoscale).Circlesofthesamecolouraresampleswiththesamegenotype.Thephotographshowsflagsmarkingoneofthetransects.

S. lanataandS. lapponumatCorrieSharroch.Ourresultssuggestthattherearemanygeneticindividualsresultingfromsexualreproductionratherthanfewindividualsresultingfromclonalgrowth.


Geneticdiversity(A)

Aisthemeannumberofallelesperlocus(ie,thenumberofvariantsofeachgeneticmarker).Thisisasensitiveindicatorofgeneticbottlenecks.

Genetics

Genetic diversity within willow

populations

Manyoftheremainingpopulationsofsub-arcticwillowsinScotlandaresmallandisolated.Suchpopulationscanlackgeneticdiversityduetolownumbersofindividualsandinsufficientgeneflowtoensurenewgeneticcombinations.AreScottishsub-arcticwillowpopulationsgeneticallydepauperate?

LeafsamplesofS. lanata(rare),S. lapponum(scarce)andS. herbacea(common)werecollectedfromatotalof19sitesacrossScotlandandsubjectedtoDNA-fingerprinting.

Therewasnodifferencebetweenthethreespeciesindiversitylevelswithinpopulationsinspiteoftheirdifferentabundance.

Thedatasetsshowedverylittlecorrelationbetweenpopulationsizeandlevelsofgeneticdiversity.InS. lanata,thelargestpopulationcontainsthehighestdiversity(CoireCheap),butsomesmallerpopulationsalsohavehighdiversity.Forexample,thesmallpopulationof12individualsatCaenlochanhasthesamelevelofdiversityasthelargerpopulationof243individualsatCorrieSharroch(Figure6).

Thelevelsofgeneticdiversityandthelackofcorrelationbetweenpopulationsizeanddiversitysuggesteitherhighlevelsofgenefloworlimiteddivergencesincefragmentation.

Figure �.Relationshipbetweenpopulationsizeandgeneticdiversity(A)inS. lanata.


Geneticdistance(Fst)

Fstisameasureofgeneticdifferentiationbetweenpopulations(ie,theproportionoftotalgeneticdiversityattributabletobetweenpopulationvariation).Avalueof1indicatesthatpopulationsarecompletelydifferentandavalueofzeroindicatesthatpopulations areidentical.

Genetics

Genetic differentiation between willow populations

Inadditiontogeneticdiversitywithinpopulations,anothercomponentofinter-andintraspecificgeneticdiversityisthelevelofgeneticdifferentiationbetweenpopulations.Thisisimportantbecauseweneedtoknowtowhatextentthefullrangeofgeneticdiversitywithinaspeciesisrepresentedwithinanyonepopulation.Thishasimplicationsforthetargetingofconservationresourceswheretheaimistoconservegeneticdiversity.Measuringpopulationdifferentiationalsoallowsustoassesstheimpactofisolationbyofferingimportantinsightsintolevelsofpollenandseeddispersalbetweenpopulations.

UsingthesameDNAfingerprintdataasfortheanalysisofgeneticdiversitywithinpopulationsofS. lanata,S. lapponumandS. herbacea,weexaminedthelevelofgeneticdifferentiationbetweenpopulations.

Allthreespeciesshowedsomeevidenceoflowbutsignificantpopulationdifferentiation.

ThehighestpopulationdifferentiationwasfoundinS. herbaceaandthiswassignificantlygreaterthanthatfoundinS. lapponum(Figure7).S. lanatahadasimilarlevelofdifferentiationtoS. herbacea,thoughthiswasnotsignificantlydifferenttoeitheroftheotherspecies.ItisunclearwhythecommonspeciesS. herbaceashowshigherpopulationdifferentiationthanthemorescarcespeciesS. lapponum.

WhatcanbeconcludedisthattherarityofS. lanataisnotassociatedwithhighpopulationdifferentiation.Thissuggestseitherhighgenefloworlimiteddivergencesincefragmentation.Itisnotpossibletodistinguishbetweenthetwoatpresent,butthelatterseemsmostlikely.Thelongevityofwillowsmayhaveledtolimitedgenerationssincethepopulationshavebeenfragmentedandhencelimitedopportunitiesfordifferentiationviageneticdrift.

Figure �.Meanpercentagevariationbetweenpopulationsforthreespeciesofsub-arcticwillow.

Associatingwithmycorrhizalfungibenefitsplantsbyenhancingtheircapacitytoacquirelimitednutrients.Onetypeofmycorrhizalassociation,theectomycorrhiza(seebox)isconsideredtobeparticularlyimportantinuplandenvironmentswheredecompositionprocessesareslowandmuchofthesoilnitrogenisboundinorganicmatter.Communitiesofectomycorrhizalfungiareoftenverydiverse.Isthisdiversityrelatedtodiversityofhostgenotypes?Understandingthisrelationshipisimportantifwearetomimicnaturalpopulationsinrestorationprogrammes.Furthermore,successfulestablishmentofplantedwillowsmayrelyontheabilityofyoungplantstoformectomycorrhizalassociations.Douplandsoilstargetedforrestorationhavesufficientectomycorrhizalinoculum?

RustfungiinthegenusMelampsora(seebox)canhavedevastatingeffectsonwillowsgrowninplantations.Infectionepidemicscanleadtoseriousreductionsinbiomassproductionwhichmaylimitreproductivepotential.Wesoughttoassesslevelsofinfectioninwildpopulationsofsub-arcticwillowandtoexaminethedistributionofMelampsoraspeciesamongdifferentwillowspecies.

Identificationofectomycorrhizalfungionplantrootsandrustfungionleavesisextremelydifficultusingmorphologyalone.Weusedmoleculartechniquestoidentifythesefungiandtherebyinvestigatethefollowingthreetopics.

1.TherelationshipbetweenS. herbaceagenotypediversityandtheectomycorrhizalfungi thatcolonizetheirroots.

2. TherelationshipbetweenwillowspeciesandthediversityofMelampsorarustfungithat infecttheirleaves.

3. Theectomycorrhizalcolonizationpotentialofsoilstargetedforplantingofsub-arctic willowsforrestoration.

Ectomycorrhizas

Ectomycorrhizasaremutuallybeneficialrelationshipsbetweenplantsandsoilfungithatformasheatharoundroottips.Thefungiobtaincarbonassimplesugarsfromtheplantsandinreturnprovideplantswithnutrientsabsorbedfromthesoilthroughextensivenetworksofthread-likecells(hyphae).

Mycology

Melampsora rustfungi

MelampsorarustfungiarepathogenicBasidiomycetesthatinfectplants.Theyhavecomplicatedlifecyclesthatinvolveuptofivedifferentsporestages.

EctomycorrhizasofaCortinariusspecieswithS. herbaceaMelampsorarustinfectingS. myrsinites


Mycology

Ectomycorrhizal fungi associated with S. herbacea

Whatistheectomycorrhizalfungaldiversityassociatedwithmontanewillowroots?Doeswillowgeneticdiversityinfluenceectomycorrhizalfungaldiversity?

WeusedDNAfingerprintingtechniquestoidentifyS. herbaceagenotypesandtheectomycorrhizalfungiassociatedwiththeirrootsat90samplingpointsontheridge-topatMeallGhaordiadh.

Wefound20speciesofectomycorrhizalfungiontherootsofS. herbaceaatMeallGhaordiadh(Figure8)andanadditional13specieswerecollectedthereasfruitbodies.

Bycomparingthedistributionofwillowgenotypesandfungiwefoundthatovershortdistances(1-2m)therewasaslightlyhigherprobabilitythatroottipsfromthesamewillowgenotypewouldbecolonizedbythesamefungalspeciescomparedtoroottipsfromdifferentwillowgenotypes.

Ectomycorrhizalfungaldiversityappearstobehighgiventheunproductivenatureofthehabitat.Thisdiversitymaybepromotedbywillowgeneticdiversityatsmallspatialscales.

Montane ectomycorrhizal fungi in Scotland

Thetotalnumberofectomycorrhizalfungirecordedinassociationwithsub-arcticandmontanewillowspeciesinGreatBritainnowstandsat105.Ofthese,24speciesareconsideredtobearctic-alpinespecialistsfoundonlyinthishabitat.Therestcanbefoundinlowlandsituationsaswell.DuringthisprojectwediscoveredtwonewBritishrecords(Cortinarius phaeopygmaeusandCortinarius inconspicuous)andonenewScottishrecord(Cortinarius subtorvus).

Amanita nivalis Russula nana

Figure �.PercentageofsoilcoresinwhichectomycorrhizalfungiwererecordedonroottipsofS. herbacea(n=90).

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WillowsarepronetoinfectionbypathogenicrustfungiinthegenusMelampsora.Thesecanhavedevastatingeffectsinuniclonalplantationsofwillowgrownforfuel.Arenaturalpopulationsofsub-arcticwillowsalsoaffected?Areallspeciesequallysusceptibletoinfection?Whatistherelationshipbetweensub-arcticwillowspeciesdiversityanddiversityofrustfungi?

Wescoredanumberofwillowspeciesfromonesiteforrustinfectiononaten-pointscale.WealsocollectedrustsamplesfromawidersetofwillowspeciesfromacrossScotlandformolecularidentification.

Mycology

Sub-arctic willowsand rust fungi

(Melampsora spp.)

Figure 10.PhylogenetictreeshowingtherelationshipbetweenrustDNAsequencesandhostidentity.EachterminalpointonthetreerepresentsauniquerustDNAsequence.Linesbetweenterminalpointsrepresentgeneticdistancebetweensequences.

Figure �.RustinfectionscoresrecordedatCorrieSharrochinSeptember2003.Theboxesinthegraphrepresenttheinterquartilerangecontaining50%ofthevalues.Thehorizontallineintheboxesisthemedianvalue.Thewhiskersextendtothemaximaandminima.

WefoundthatdifferentrustDNAsequencestendedtoclusterondifferentspeciesorgroupsofspeciesofwillows(Figure10).

Thesedataprovideanimportantframeworkwithwhichtocarryforwardourunderstandingofthetaxonomyandecologyofthisgroupofpathogensinnaturalpopulationsofwillows.

WillowspecieswerefoundtovaryintheirsusceptibilitytoinfectionbyrustfungiinthegenusMelampsora(Figure9).S. lanatawasmuchlesssusceptiblethanS. lapponumandS. myrsinites.

SusceptibilitytoinfectionvariedgreatlyamongindividualsofS. lapponumandS. myrsinitesatthesamesite(Figure9).Thissuggeststhattheremaybeastronggeneticinfluenceonrustsusceptibility.

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Mycology

Ectomycorrhizal colonization potential of upland soils

Itisknownthatwillowsformectomycorrhizasandnumerouslaboratorytrialshaveshownthatectomycorrhizasarebeneficialtoplants.Sowhenwillowsareplantedduringrestorationprojectsistheresufficientectomycorrhizalinoculumavailableinsoilsorshouldwillowsbeinoculatedbeforeplanting?

ToassesstheectomycorrhizalcolonizationpotentialofuplandsoilsweusedabaitingtechniqueinwhichuncolonizedS. lapponumcuttingswereplantedintouplandsoilsanddugupafter14monthstoassesstheirectomycorrhizalcolonization.Wecomparedthecolonizationpotentialassociatedwithtwodifferentuplandplantcommunities:onedominatedbygrassandtheotherbyVaccinium myrtillus.

70%ofcuttingswerecolonizedtosomeextentbutanaverageofonly20%ofroottipspercuttingwascolonized.

Onlyfivetaxaofectomycorrhizalfungiwereidentified.

Thetwoplantcommunitiesdifferedinthecompositionofinocula(Figure11).ThegrasscommunitywasdominatedbyLaccaria proximaandanunidentifiedspeciesintheorderPezizaleswhiletheVacciniumcommunitywasdominatedbyThelephora terrestriswhichwasentirelyabsentfromthegrasscommunity.Therewasnodifferenceinwillowperformanceintermsofleafbiomassproductionbetweenthetwoplantcommunities.

Thesedatasuggestthatectomycorrhizalinocula,probablyspores,arewidespreadintheseuplandsoilsbutlowindiversity(e.g.,comparethefivetaxaofEMfungiherewithFigure8)andabundance.Thedifferencesinthespeciesoffungipresentinthetwoplantcommunitiesmaybeinfluencedbythevegetationitselfortheedaphicconditionsofthesoil.

Figure 11.Frequency(percentageofcuttingscolonized)andabundance(averagepercentageofrootspercutting)ofectomycorrhizalfungiingrass-dominated(G)andVaccinium-dominated(V)habitats.Errorbarsforabundance=standarderrorwheren>2.

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ecology

Theecologicalfactorsleadingtothecurrentrestricteddistributionofmanymontanewillowspeciesneedtobeassessedifthedownwardtrendinrangeandnumbersistobepreventedorreversedthroughrestorationprojects.Thisrequiresinformationonallaspectsofthelifecyclefromgrowthandreproductiontoseeddispersalandseedlingestablishment.

Aparticularemphasisofthisareaofresearchwasaninvestigationoftheroleofherbivoryonkeystagesinthelife-cycleofmontanewillows.Theroleofsheepanddeerinpreventingregenerationofwoodyperennialsbyremovingseedlingshasbeenwelldocumented.However,largeherbivoresmayimpactwillowsinotherways.Forexampletowhatextentdoesthebrowsingofwillowshootslimittheresourcesavailableforseedproduction?

Oneoftheproblemsassociatedwithremovinglargeherbivoresaltogetheristhatadenseswardofrankgrasscandevelop.Thismayreducethenumberofsuitablegerminationandestablishmentsitesforregeneratingplants.Whensuitablemicrositesarelimited,thenseedproductionanddispersal,sufficienttoensurethattheyareexploited,becomescrucial.Developmentoftallgrassmayalsoencouragegrowthofpopulationsofsmallherbivoressuchasvolesandslugs.Towhatextentiswillowregenerationlimitedbydispersal,suitableestablishmentsitesandseedlinglossestosmallherbivores?

Understandingtheserelationshipsbetweenherbivoresandwillowgrowthandreproductionmayhelpusindevelopingstrategiesforthemanagementoflargeherbivoresinordertoencourageregeneration.

S. lapponumPollination

S. lapponumSeedset

S. lapponumSeedlingestablishment

A C o l l A B o r At i v e r e s e A r C h p r o j e C t � �

ecology

Herbivory and seed production

Aswillowsaredioecious,successfultransferofpollenbetweenmaleandfemaleplantsiscrucial.Pollentransferiscarriedoutprimarilybyinsectsthatareattractedbyflowers.Browsingbylargeherbivoreshasthepotentialtoremovelargeproportionsoffloweringshoots.Howdoesthisaffectthereproductivepotentialofthewillowsbothintermsoftheabilitytoattractinsectsandintheeffectoftheresultingresourcelimitationonviablefruitproduction?

WecomparedindividualsofS. arbusculathatwereprotectedfrombrowsinginexclosureswithunprotectedindividuals.Catkinsfromsomeindividualsineachtreatmentwereprovidedwithsupplementalpollen.Plantswerescoredfornumberofcatkinsproduced,numberofripeandunripefruitspercatkinandnumberofseedsperripefruit.

Wefoundthat,irrespectiveofbrowsing,seedproductionvariedsignificantlyfromyeartoyearprobablyduetovariationintheweather(Figure12).

Browsingreducedtheamountofseedproducedperplot,particularlyinyearswhentheweatherwasbad(Figure12).

Overall,handpollinationresultedinagreaterproportionofripefruitcomparedtonaturallypollinatedcontrols.Thiseffectwasgreaterinbrowsedindividualsthanunbrowsedindividualssuggestingthatbrowsedplantsaremorepollenlimitedthanunbrowsedplants(Figure13).

ThedatasuggestthatbrowsingofadultplantshasanegativeimpactonthereproductivesuccessofS. arbusculathroughareductioninattractivenesstopollinatinginsects.

Figure 1�.Meannumberofseedproducedperplotinbrowsed(control)andunbrowsed(exclosure)plots(errorbars=95%confidenceintervals).

Figure 1�.Meanproportionofripefruitunderdifferentbrowsingtreatments(errorbars=95%confidenceintervals).HPrepresents‘handpollinated’.

S. arbusculamale S. arbusculafemale


ecology

Predicting the potential distribution

of S. arbuscula

WeaimedtoassessthepossibilityofusinginformationonassociatedspeciesandenvironmentalconditionstopredictthepotentialdistributionofS. arbusculaatthelargerscaleswithinasiteasawayofassessingthepotentialforpopulationexpansion.

Vegetationandenvironmentalvariablessuchasaltitude,aspect,slope,swardheightandsoildepthwererecordedinover200quadratsintheLochannaLairigecatchmentatBenLawers.SomequadratswerelocatedclosetoorwithinexistingS. arbusculastandsandothersrandomlydistributedwithinthecatchment.Thesedatawerethenusedtomodeltheexistingdistributionandpredictpotentialdistribution.

Populationexpansionwillonlybepossiblewhereseedisdispersedawayfromparentplantstosuitablesitesforgermination,establishmentandgrowth.WeaimedtoquantifytheamountofS. arbusculaseedbeingdispersedawayfromparentplants.

Inboth2003and2004,over300stickytrapsweresystematicallyarrangedwithinandupto80mawayfromastandofS. arbusculaatBenLawers,andleftinplacefor2monthsfrommid-Junetomid-August.

InspiteofabundantseedproductionbythestandofS. arbusculaoverthetwoyears,only11seedswerecaught,allononetrapat20mawayfromthestandin2003.Observationssuggestthatmuchofthefertileseedremainedwithinthebushandwaswashedintothegroundbeforethesilkyhairsthataiddispersalwerefullydriedout.

Limitedseeddispersalmaybeafactorinhibitingpopulationexpansion.

ThedistributionofS. arbusculaisdeterminedbythepresenceofopen,moderatelyfertileareasonsteepslopes.

Ifotherreproductivefactorsarefavourable,thereispotentialfortheexpansionofS. arbusculaduetothepresenceofsuitablehabitatwithincurrentstandsandelsewhereintheLochannaLairigecatchment(Figure14).

Figure 1�.PredicteddistributionofS. arbusculainonecatchmentatBenLawers.‘Predicted’referstoquadratspresentlywithoutS. arbusculawhereconditionsaresuitable.‘Willow’referstoquadratscurrentlywithS. arbuscula,‘Notwillow’referstoquadratswherenowillowcurrentlygrowsandareunlikelytobesuitableforwillowestablishment.MapreproducedfromOrdnanceSurveydatabypermissionofOrdnanceSurvey,©Crowncopyright.MLURIGD27237X2005.

seed dispersal


ecology

Herbivory and seedling establishment

Figure 1�.EffectofslugsonproportionofS. arbusculaseedlingssurvivingindisturbedmicrosites(errorbars=95%confidenceintervals).

Figure 1�.EffectofmicrositetreatmentonproportionofS. arbusculaseedssurvivingasseedlings(errorbars=95%confidenceintervals).

Forseedthatdoesmanagetogetdispersed,whatarethefactorsthatdeterminethesuccessfulestablishmentofnewseedlings?Isseedandearlyseedlingmortalityaproblemandifsowhatiscausingit?

Anexperimentwascarriedoutinwhichsmallmammalswereexcludedfromsomeplotsbutnotothersandinwhichsub-plotswereeithermown(clippedto5cm),disturbed(allvegetationremovedtoleavebareground)orleftascontrols.Someofthedisturbedplotswereprotectedfromslugswithpellets.SeedofS. arbusculaandS. lapponumwassetoutintheplotsandtheirgerminationandsurvivalwasfollowedfor90days.Inaseparateexperimentone-year-oldseedlingswereplantedintoplotswiththesametreatments.

Disturbancestronglyfavouredgerminationandsurvivalofbothspecies.Noseedlingssurvivedinthecontrolplotsandonlyveryfewinthemownplots(Figure15).

Slugsstronglyreducedsurvivalduringtheearlystageofestablishment(Figure16).

Inspiteofanabundanceofbankvoles(Clethrionomys glareolus)inthearea,therewasnoeffectofsmallmammalsduringtheearlystageofestablishment.However,wefoundthattheycausedsignificantdamageto40%ofone-year-oldseedlings.

Successfulregenerationofwillowseedlingswasinfluencedbysluggrazingandavailabilityofsuitablemicrositeswithbaregroundforseeds.Smallmammalsreducegrowthofone-year-oldseedlings.

Conservation implications

Taxonomy

Theoverarchingaimofthisprojectwastoprovidescientificunderpinningfortheconservationofsub-arcticwillows.Hereweseektosummarisethespecificimplicationsofourresultsfortheconservationofwillows.

Despitetheirformidablereputationfortaxonomiccomplexity,sub-arcticwillowsappeartohybridizeinfrequently.Ingeneral,whilehybridizationcanbeviewedasaprocessthatdoesoccurwithinthegenus,inthemajorityofcasesspeciesbarriersaremaintained.OneexceptiontothisisseeninpatternsofhybridizationbetweenS. arbusculaandS. lapponumwhichoccursfreelyatsomesites.

Whenconsideringtheconservationofagivenspecies,careshouldbetakentoavoidplantingmaterialderivedfromhybridizingpopulations.Tothisend,collectionofmaterialforplantingshouldbetargetedwherepossibletositesatwhichparentspeciesaregrowingaloneorwithfewotherwillowspecies.

Hybridizationisparticularlylikelytooccurwherethereareseriousimbalancesinspeciesabundance.DuetothefragmentarynatureofmontanewillowdistributioninScotland,differencesinrelativeabundancemightbemorepronouncedbetweencertainpairsofspeciesthanmighthavebeenthecaseinthepastwhenwillowscrubandthespecieswithinitweremorewidespreadandmorenumerous.Furtheraccelerationofthisprocessshouldbediscouragedbyavoidingthecreationofextremeimbalancesofspeciesabundanceinrestorationprogrammes.

Evidencesuggeststhatfloweringhybridsmayencouragefurtherhybridizationbetweentheparentspeciesincertaincircumstances,andassuch,knownhybridsshouldnotbedeliberatelyincludedinre-introductionprogrammes.Ifhybridlineagesaretobeactivelyincreasedinfrequency,thisshouldbedoneex-situwherenoeffectonthenaturalpopulationbalancewouldoccur.

S. x obtusifolia(S. lapponumxS. aurita)



Genetics

Despitetheirobviousabilitiesforclonalgrowthandthelackofobservedseedlingrecruitment,montanewillowspecieslikeS. lanataandS. lapponumreproducepredominantlybysexualreproduction.Thusrestorationprogrammesshouldfocusonlargenumbersofdifferentgenotypesiftheyaretomatchnaturalpopulations(ratherthanmultiplereplicatesofvegetativelypropagatedindividuals).

Managementtofacilitatesexualreproduction(e.g.,byavoidingexcessivelargemammalgrazing)andseedlingrecruitment(e.g.,creatingsuitableareas/conditionsforestablishment)isanecessarycomponentofwillowconservation.Willowpopulationsareunlikelytoexpandviavegetativegrowthanddispersal.

Evensmallwillowpopulationsshowhighlevelsofgeneticdiversityandlowlevelsofpopulationdifferentiation.Thereisnoevidenceofthembeingaffectedbymajorgeneticbottlenecksandhighlevelsofgeneticdrift.Althoughgeneflowbetweenfragmentedpopulationsispossible,itisunlikely.Morelikelyisthepossibilitythatthegeneticconsequencesofreducedpopulationsizesandphysicalisolationhavebeenlimitedbythelongevityofwillowsandalimitednumberofgenerationssincefragmentation.

Thepositiveaspectofthisisthateventhesmallestfragmentsrepresentausefulgeneticresource.Thesepatchesshouldnotbeconsidered‘dead-ends’beyondhope.Theyrepresentbothpotentiallyusefulsourcesasdonorsfornewpopulations/exsitucollections,aswellasreservoirsofdiversityfortheexpansionofexistingsites.Inthisrespect,itisnottoolatetorestoreandexpandpopulationsofthesespecies.However,thosefragmentswithpopulationsizesoflessthan50areofconservationconcernanditwouldtakefewgenerationsorenvironmentalcatastrophestolosediversityorwholeplants.Thusconservationactionintheneartomidtermisappropriate.

S. lapponum



Mycology

S. herbacea supportsahighdiversityofectomycorrhizalfungi.Manyofthesearearctic/alpinespecialistsfoundonlyinthesehabitats.S. herbacea shouldthereforebeviewedasanimportantcomponentofScottishbiodiversity.

Thebelow-groundECMcommunityassociatedwithS. herbacea wasdominatedbyspeciesthateitherdonotproducefruitingstructuresabove-groundorelseproducefruitingstructuresthatarecryptic.Thishighlightstheimportanceoflookingbelow-groundinordertoproperlyassessfungalbiodiversity.

TherewassomeevidencetosuggestthatovershortdistancesinS. herbacea bedsthecompositionoftheECMcommunitymaybeinfluencedbythegenotypeofthehost.Althoughitisnotpossibletoextrapolatedirectlytootherwillowspecies,thesedatatendtosupporttheprincipleofmaintaininggeneticdiversitywithinwillowpopulationsinordertomaintaindiversityofassociatedorganisms.

InoculaofECMfungiavailabletoplantedS. lapponum werefrequentintheuplandsoilsstudied.However,thediversityofinoculaandthecolonizationpotentialwerelowcomparedtootherstudiesofmontanehabitats.Trialstoassessthebenefitsofinoculumenhancementforwillowestablishmentshouldbecarriedout.

Althoughthereweredifferencesbetweengrass-dominatedandVaccinium-dominatedhabitatsinthecompositionofinoculaavailabletoplantedS. lapponum cuttings,nodifferenceinwillowperformancewasdetected.GiventhatwedonotatpresentunderstandtherelativebenefitsofdifferentECMfungitowillowsitisrecommendedthatchoiceofplantingsitecontinuestobedrivenbyconsiderationofedaphicconditionsthatareknowntobeimportanttowillowestablishment;forexamplesoilmoisture.

Therewasconsiderablevariationwithinspeciesinthedegreeofrustinfection.Susceptibilitytoinfectionislikelytohaveastronggeneticbasisandthesedatafurthersupporttheprincipleofmaintaininggeneticdiversitywithinwillowpopulations,inthiscasetominimisethechancesofcatastrophicpathogenepidemics.

Willowspeciesdiversitypromotesrustdiversity.Thistendstosupporttheviewthatthediversityoforganismsassociatedwithsub-arcticwillowscrubwillbeenhancedbyhavingmixturesofwillowspecieswhereenvironmentalconditionsallow.

Inocybe praetervisawithS. herbacea



Ecology

AllconclusionsbelowareforS. arbuscula.Extensionofthesepointsasgeneralitiestootherspeciesaretobeconsideredastentative,butshouldbepossibleaslongasspeciesdifferencesinecology,andsitedifferences,aretakenintoaccount.

Thelowfrequenciesofseedproductionand/orpoordispersalrecordedoverthecourseoftwoyearssuggestthatregenerationfromseedislikelytorequirecollectionandtranslocationofseedtonewsitesorwithinorclosetoexistingsiteswhicharealreadycolonised.

Moresuccessfulestablishmentfromseedwasrecordedinareaswheregroundwasexperimentallydisturbed.Scarificationormechanicalgrounddisturbancetorevealbaresoilcouldbeusedtopromoteestablishment.Thisisparticularlynecessaryinareaswhereagrassyormossymatformsthemainvegetationcommunity,andwouldbeunnecessarywherethesoilorothersubstrateisnaturallymobile,suchasflushedareasonsteeperslopes.Itissuggestedthatlarger(c.1m2)disturbedareaswouldreduceseedlinglossesduetopredationasthiswouldrenderalargerareaunsuitableforsmallmammalsandslugs.

Smallmammalsdidnothaveagreatinfluenceonveryearlyseedlingestablishmenteveninyearsofpeakabundance.However,smallmammalherbivorydidresultingreaterdamageofone-year-oldseedlingsalthoughthisdidnotnecessarilycauseseedlingmortality.Managersattemptingtoestablishwillowsmayconsiderplantingyear-oldseedlingsinbarepatchestoreducecompetitionandcoincidingplantingwithyearsoflowvoleabundance.

Exclusionoflargeherbivores(sheepanddeer)permittedmorevigorousvegetativegrowthofshoots,floweringandpollenandseedproduction.Limitingthenumbersoftheseherbivoresinareaswheretheirimpactsonthevegetationissignificantwouldpromotegrowthandsexualreproduction.However,thismeasurealonewouldresultinlittleornonewestablishmentfromseedgiventheotherfactorsreferredtoabove.

S. lapponumcatkins


Further information

Inevitably,giventhenatureofthispublicationandspaceconstraints,theworkpresentedhereishighlysummarised.Ifyouwouldliketoknowmoreaboutthisprojectpleasevisitourwebsitewhichhasadditionalinformation,resourcesandphotographs.

http://rbg-web2.rbge.org.uk/willow/index.html

Foradditionalinformationpleasecontacttheprojectco-ordinatorsinthefirstinstance.

Dr.PeteHollingsworth Dr.GlennIason RoyalBotanicGardenEdinburgh MacaulayInstitute 20AInverleithRow Craigiebuckler EdinburghEH35LR AberdeenAB158QH tel+441312482883 tel+441224498200 Fax+441312482901 Fax+441224311556 [email protected] [email protected]

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AcknowledgementsScottish Montane Willow Research Group

royal Botanic Garden edinburgh Dr.PeteHollingsworth Dr.StephanHelfer DouglasMcKean AlanForrest Dr.JeremyMilne

Macaulay institute Dr.GlennIason Prof.RobinPakeman RosShaw

scottish Crop research institute Dr.JohnBrown Dr.JoanneRussell KonstantinaStamati

Biomathematics and statistics scotland Prof.DavidElston

scottish Agricultural College Prof.DaleWalters

university of edinburgh Dr.RichardEnnos

university of Aberdeen Dr.MarkYoung

Thanks

WewouldliketothanktheScottishExecutiveEnvironmentandRuralAffairsDepartmentforfundingthisprojectthroughtheCollaborativeFlexibleFund(SEERADCommissionNo.RBG/837/01).

Ourthanksareextendedtothefollowingindividualswhocontributedtotheprojectinavarietyofways:Prof.RoyWatling,Prof.RiittaJulkunen-Tiitto,DavidTennant,Dr.ChrisSydes,KenSlater,DavidMardon,AndrewWarwick,DianaGilbert,RobSoutar,Dr.IanAnderson,Prof.IanAlexander,SandieBlackie,RosAnderson,SvenRasmussen,VimiLomax,CatherineDickison,Dr.MichelleHollingsworth,AlexClark,Dr.ChrisWalker,KeithWatson,LynneTorvell,DavidSim,VeraThoss,JoanBeaton,KennyHood,BettyDuff,Dr.JaneSquirrell.

FinallywewouldliketothankthenumerouslandownersandstaffofScottishNaturalHeritagewhograntedusaccesstothewillowsandpermissiontoresearch.

GroupmembersonanearlyreconnaissancetriptoBenLawers

A C o l l A B o r At i v e r e s e A r C h p r o j e C t � 1

Thisbookletsummarisessomeofthekeyfindingsfromacollaborativeresearchprojectentitled“Biodiversity: taxonomy, genetics and ecology of sub-arctic willow scrub”thattookplaceduring2002-2005.

TheprojectwasfundedbytheScottishExecutiveEnvironmentandRuralAffairsDepartment(SEERADCommissionNo.RBG/837/01).

Itinvolvedresearchersfrom:

RoyalBotanicGardenEdinburgh

MacaulayInstitute

ScottishCropResearchInstitute

BiomathematicsandStatistics Scotland

ScottishAgriculturalCollege

UniversityofEdinburgh

UniversityofAberdeen.

Biodiversity...Genetic differentiation between willow populations 17 Mycology 18 Ectomycorrhizal...

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