RobertJ. Lambeck
CSIRO,Divisionof Wildlifeand Ecology,LMB 4, PO
M i d l a n dW
, A,6056
INTRODUCTION
Thesuccessfulmanagement
of remnantvegetation
dependsupon the formulationof clearlydefined
goals.Broadobjectives,
management
suchas
"managementto maintain
biodiversity",havebeen
identified,
but the implications
for managers
of such
s l a l e m e nh
t sa v en o t b e e ns p e c i f i e d .
providea model
Honeyeaters
in the centralWheatbelt
for understandingthe functionalsignificanceof
biodiversity,
andfor assessing
the implications
of a
reductionin regionalbiodiversity.
ThisunderstandinS,
in turn, canprovidea frameworkfor approachingthe
dauntingtaskof "managingfor biodiversity".
Biodiversityencompasses
the variationthat occurs
between
individuals,
species,
communities,
landscapes,
andbroadbiogeographical
regions.The relationship
betweenhoneyeaters
andtheir foodplantsprovidesan
opportunityto explorethe consequences
of diversityat
all of theselevelsandto examinethe functional
significanceof this diversity.Aspollinators,honeyeaters
playan importantrole in the maintenance
of localfloral
diversity.A declinein honeyeater
numberscanaffect
plant communitiesby reducingthe distanceand
frequency
of geneflowbetween
discontinuous
populations(Lamontet al- 1993),a problemthat is
exacerbated
in fragmentedenvironments.Changesin
floraldiversiiymay.in turn.affecllhe persislence
probabilities
of otherspecies
associated
lvith,or
d e p e n d eu
np
t o n t. h a l f l o r a B
. yc o n s i d e r i nl hge s e
relationshipsbetweenplantsandanimals,we can
identifythe importance
ofvarietyat various
organisational
Ievelsin bothplantandanimal
communities.
PLANTDIVERSITY
IndividualDifferences
Althoughmostmembersofa plantspecies
in onearea
flowersynchronously,
individualdifferences
resultin
someplantsfloweringearlierin the season,
while
otherscommence
later.Thesephenological
differences
mayresultfromvariationin microenvironments
aswell
asfrom geneticdifferences
betweenindividuals.These
individualdifferences
resultin an increase
in the
amountof timethatnectaris available
for honeyeaters.
SpeciesDifferences
Differences
in the floweringphenologyof different
species
alsobroaden
the rangeof opportunities
for
honeyeaters
in a givenhabitat.An arrayof species
which flowersynchronously
in differentlocations
increases
the rangeof habitatsthat honeyeaters
can
utilise.
CommunityDifferences
Edaphic,evolutionary,disturbanceandother factors
plantsformingclear
haveresultedin Wheatbelt
associations
in a pronounced
vegetation
mosaic.The
constituent
species
within theseassociations
have
particularflo\!eringcharacteristics
whichresultin
differentpatchesproducingnectarat differenttimesof
the year.Providedthe configurationof theseresources
is favourable,
honeyeaters
canmovefrom onepatch
typeto anotherat differenttimesof the year,further
increasing
theirresource
options.
Landscape
Diversity
Thesamevegetation
communities
at differentpositions
in the landscape
oftenhavedifferentphenologiesasa
resultof regionalvariationin environmental
conditions,
againexpanding
the resource
basefor
honeyeater
species
that canrangewidelyacrossthe
landscape.
RegionalDiversity
Unfavourable
climaticconditions
in a particularregion
poor
mayresultin
floweringandhencetemporary
shortages
of nectaroversubstantialareas.At such
times,mobilespecies
areableto moveto adjoining
regionsurherea differentsuiteof plantspecies
may
providethe necessary
persistence
resources.
The
of a
species
in its preferred
habitatmaydependuponaccess
to resources
in adjoiningareasat times\rhen local
resources
aredepleted.For example,white fronted
(PhAltdongris
honeyeaters
albifrons),piedhoneyeaters
(Certhiongxuariegalus)andblackhoneyeaters
(C.
niger) irrupt sporadically
into the centralWheatbeltat
timesof low rainfallin the morearidinterior Nectarproducing
plantspecies
in theWheatbelt
mayprovidea
criticalresource
for thesebirdsat thesetimes.
HONEYEATER
DIVERSITY
Not only is a varietyof plantsimportantfor the
persistence
of pollinators,but similarlya varietyof
pollinatorsis essentialfor the maintenance
of plant
diversity.The impactof fragmentationon plantpollinatorrelationshipswill dependupon the capacity
of pollinatorsto dealwith the modifiedlandscape.
A
rangeof pollinatorswhich respondto the landscape
in
differentwayswill enhancethe prospectofplant
populationprocesses
beingmaintained.Thefunctional
significanceof honeyeaterdiversityis expressed
primarily at the specieslevel,but individualdifferences
mayalsoinfluencepatternsof pollendispersal.
Individual Differences
Within somespecies,someindividualsestablish
territoriesin which they remainfor extendedperiodsof
time. Otheryounger,or lessdominant,individualsare
unableto establishor maintainterritories.Theyare
more mobile,andthis resultsin differentpatternsof
pollendispersal.
significance
ofa speciesin a systemis inverselyrelated
to the numberof its functionalanalogues.
Lossofbiotic
diversityreducesthe numberofalternative,functional
pathwaysandhencereducesthe probabilitythat a
processwill occur Speciesthat haveno functional
analogues
but makea major contributionto a given
functionmaybecome"keystone"species,
andtheir loss
couldhaveseriousimplicationsfor otherassociated
organlsms.
Theacornbanksia(Banksiaprionotes)flowersin early
autumnin the centralWheatbelt.No other nectarproducingplantsflowerin the Durokoppinareaat this
time - it hasno functionalanalogues.
It is heavily
exploitedby honeyeaters
and,becauseit appearsto be a
Iimiting resource,it mayinfluencetotal honeyeater
numbersin the regionfor the remainderof the year.
For thesereasons,
this speciesis a keystonespecies.
It
doesnot playthe samerole in otherpartsof its range
whereotherspecies(for example,.B.
m enziesii)flower
at the sametime.
MANAGEMENT
IMPLICATIONS
SpeciesDifferences
Differences
existbetweenspeciesin the waytheymove
aroundthe landscape.
Somespecies,
suchaswhite(lichenostomusleucotis),are
earedhoneyeaters
relativelysedentaryandtendto remainin territories
(L. uiriscens)
within remnants.Singinghoneyeaters
commonlymovebackandforth betweenremnantsand
adjoiningroad-verge
vegetation.Brownhoneyeaters
(Lichmeraindistinclal movewidelyaroundthe
landscape,
commonlymovingbetweenremnants,and
white-fronted,piedandblackhoneyeaters
invadefrom
morearid regionsto the north andeast.Somespecies
remainin closeproximityto vegetation,while others,
such asyellow-throated minerc (Manorina flauigula),
routinelymakeextendedflightsoveropenpaddocks.
Thisarrayof differentstrategiesfor exploitingresources
providesvariousopportunitiesandscalesfor pollen
transferthroughoutthe landscape,
IMPLICATIONS
OF REDUCED
DIVERSITY
Thevalueof greaterbiodiversitylies in the increased
numbersofspeciesthat mediateimportantprocesses,
therebyincreasingthe areaandtime overwhich a given
processproceeds.
Specieswhich playequivalentroles
canbeviewedasfunctionalanalopues.
Thefunctional
Honeyeaters
havebeenusedhereto explorethe
functionalsignificanceof biodiversity.This modelmay
hold for a wideyangeofspeciesandcommunities,
althoughthe scaleandnumberof participantsmay
vary.Severalimplicationsflow from this perspective.
Managementfor Function and Repres€ntation
Representation
of biodiversityis a necessary
objective
for the management
of nativebiota,but it aloneis not
sufficient.It is alsoessentialto considerhow different
levelsof representation
contributeto ecosystem
function.Thegreaterthe functionalcontributionof a
speciesor community,the morewidelyshouldit be
represented.
Honeyeaters
are not a high priority for
conservation
in their own right, but maybe essential
for the achievement
of other objectives.Consequently,
theymust bewell represented
in the landscape.
For
species
that contributelessto communityprocesses,
representation
in a fewlocationsmaybe adequate.
The Importanceof Scaleand Conliguration
Management
must be plannedat an appropriatescale
for the speciesandprocesses
beingmanaged.Because
biodiversityencompasses
all scales,from individualsto
landscapes,
it is necessary
to havestrategiesthat reflect
this diversity.Whilelarge-scale,
regionalassessments
of
conservation
valuemust be made,thesemustthen be
combinedwith localstrategieswhich identifythose
actionsthat needto be implementedat particular
locations.Attemptsto achievean objectivewithin a
singleremnantwill fail ifthat objectiveis dependent
uponprocesses
that operateat a scalegreaterthan that
of the remnant.Management
of remnantsmustbe
guidedby their role in landscape
processes
andin
achievingregionalconservation
objectives.
The Importanceof Objectives
The abovepoint presupposes
that regionalconservation
objectivesandstrategiesexist.Conservation
objectives
must be identifiedat catchment,regionalandnational
Ievels,with localactionstargetedtowardsthose
objectiveswhich are relevantfor the areabeing
managed.For example,someareasmaynot encompass
speciesor communitiesthat are recognised
asregional
or nationalpriorities.This cannotbetakento mean
that natureconservationis not an importantissuefor
suchan area.It simplymeansthat specificobjectives
haveto be identifiedwhich addressthosevaluesthat do
remainin that region.
Objectives,
at anyscale,will not be achievedin a short
periodof time. It is thereforenecessary
to identifya
sequence
of actionsthat will achievenominated
objectives.It is alsoimportantto identilythose
objectivesthat needmosturgentattention,andactions
that will providemaximumconservation
valuefor
minimum effort.
BIODIVERSITY
AS A MODELFOR
SOCIALMANAGEMENT
Ifa regionalconservationstrategyis developed,
its
implementationwill requirea coordinatedeffortby a
wide rangeof individualsandorganisations.
Diversityat
differentlevelswithin the humancommunitymust also
be recognised,
andthe functionalsignificanceof each
cultural group identifiedin orderto developan effective
socialprocessfor achievingbiodiversityconserration.
In termsof the biodiversitymodelpresentedabove,
importantcomponentsof diversityin the human
communityareasfollows:
.!. Individualdifferences:
Differentindividualswill have
differentcapacitiesto contributetowards
managementof the nativebiotain a region,
dependingupon inclination,financialresources,
othercommitments,etc.Localfarm plansor
communityprojectsshouldbe designedto recognise
thesedifferences,
andshouldenableall individuals
to feelthat their contribution,no matterhow large
or small,is an integralpart of a largerconservation
effort.
.i. Speciesdifferences:
Sometimesit appearsthat the
variousgroupswith vestedinterestsin regionsare
indeeddifferent"species".
These"species"comprise
the land-holders,
andthe widearrayof government
andnon-government
agencies
that are involved.The
differentperspectives
andaspirationsof these
groupsmust be acknowledged
and incorporatedinto
planning.The functionalrole of eachgroupmust be
clearlyidentifiedandtheir effortscoordinatedso as
to maximiseconservation
return.
.i. Communitydifferences:
Differentareasmayhave
priorities,dependingupon
differentconservation
their particularproblems.If regionaltargetscanbe
identified,localcommunities,togetherwith other
groupswith appropriateinformationandexpertise,
mustwork jointly towardsidenti[ring how those
targetscanbestbe achievedin a mannerwhich
maximisesboth conservation
return andprimary
productivity.
The useof "biodiversity"asa metaphorfor social
organisation
will clearlyhaveits limitationsif takento
exttemes.For example,while a rangeof functional
performingsimilarrolesin a natural
analogues
ecosystem
mayenhancethe stabilityof that system,the
presence
of a numberof governmentagenciesall
fulfilling equivalentfunctionswill simplyresult in
unnecessary
duplicationandconflict.Giventhat
governmentagenciesrarely"becomeextinct",the need
for functionalequivalentsis clearlynot desirable.
In contrast,at the levelof individualswho are
implementingrecommendations,
it is importantto
ensurethat multiplerepresentation
exists.Giventhe
magnitudeof the problemsin agriculturallandscapes,
managernent
actionswill needto be implementedover
a largepropodionof the landscape.
This requiresa
clearstatementof objectives,
identificationof the
actionsto be taken,andthe involvementof many
individualsin implementingtheseactions.In the
absence
of an integratedmanagement
strategy,there
will be onlysmalllocalised
responses
whichwill
generatelimited benefitat a landscape
scale.
The comparisonof socialorganisational
structureswith
biodiversitymay be more appropriatewhenconsidering
the functionalrolesoftheseorganisations.
Thevalueof
the analogylies in the recognitionthat a complex
systemcomprisinga numberof interdependent
componentsneedsto retainall of the essential
functionsif that systemis to persist.In orderto achieve
sustainable
agricultureandmaintainbiological
diversity,it will be necessary
to integratesocial,
agricultural,land conservation
andnatureconservation
objectives.
Only by recognisingthe diversitywithin the community
andthe differentcontributionsthat differentsectors
canmakewill natureconservation
succeedin what is
predominantlya freeholdlandscape.
Ownershipof, and
responsibilityfor, localconservation
must be devolved
to the community,with governmentorganisations
managing
specifically
identified,
high-priority
targets
which are beyondthe materialandknowledgeresources
of localcommunities.
REFERENCES
Lamont,8.B., Klinkhamer,PG.L.,andWtkowski,
E.TR, 1993.Populationfragmentationmayreduce
ferlility to zero in Banksia goodii - a demonstrationof
the Alleeeffect.Oecologia94: 446450.
Notethat RobertLambeck'swork on honeyeaters,
referredto extensively,
hasnot yet beenpublished.
REMNANTNATIVEVEGETATION
TENYEARSON
A DECADEOF RESEARCH
ANDMANAGEMENT
PROCEEDINGS
OFTHE
DRYANDRA
WORKSHOP
1993
SEPTEMBER
g
DEPARTMENTOF CONSERVATION
AND LAND MANAGEMENT
lq15