medieval castles: preservation of cultural and natural heritage by environmentally friendly...

7/30/2019 Medieval castles: Preservation of cultural and natural heritage by environmentally friendly restoration strategies

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Medievalcastles:Preservationofculturalandnaturalheritageby

environmentallyfriendlyrestorationstrategies

ManuelJonasSteinbauerAndreasGohlkeChristineMahlerAndreasSchmiedinger

CarlBeierkuhnlein

M.J.Steinbauer([email protected],phone:+49921552211fax:+49921

552315),A.Gohlke([email protected]),C.Mahler([email protected]),A.

Schmiedinger([email protected]),C.Beierkuhnlein

([email protected]),Dept.ofBiogeography,UniversityofBayreuth,D

95447Bayreuth,Germany


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Abstract

Largehistoricbuildingsareimportantforculturalhistoryandprovideavarietyofhabitatsfor1

animalsandplants.Thespecialqualityofthesehabitatsisthelongtimeofexistenceandthe2

lowdisturbancefrequency.Inaddition,manyoldbuildingssuchascastlesarelocatedina3

matrixofnaturalsitesoratleastparks.Inculturallandscapes,historicbuildingsoffer4

extraordinarymicroclimatesandstablehabitatsforremnantpopulationsofrarespeciesthat5

haveestablishedonancientwallsinthecourseofcenturies.6

Nevertheless,intraditionalapproachesgoalsofbiodiversitypreservationandmonument7

restorationareperceivedtointerfereandtobemutuallyexclusive.Asaconsequence,priority8

isoftengiventoconstructionalrestorationacceptingthelossoflocalpopulationsand9

biodiversity.10

Atwallsofmedievalcastles,includinganexperimentalrestorationprojectwhere11

conventionalandlessintensiverestorationtechniqueswereapplied,werelatespecies12

compositionandrichnesstowallproperties.Thestudyfocusesonlichens,mossesand13

vascularplants.14

Boostedregressiontreeanalysesandnonmetricmultidimensionalscalingtechniquesare15

appliedtodetecttheinfluenceofabioticsiteconditionsonbiodiversity.16

Wefindspeciesrichnesstobepromotedbywallsurfaceheterogeneity.However,species17

compositionismoreaffectedbyrestorationapproachesthanspeciesrichness.Lichen18

compositionvariesconsiderablywhilevascularplantsandmossesarelessaffectedbywall19

properties.20

Wesuggeststrategiesthatarecombiningbothsocietaltargets,thepreservationofhistoric21

monumentsandofspeciesdiversity.Carefulrestorationiscapableofsupportingboth,the22

maintenanceofculturalheritageandofrareanduniqueanthropogenichabitats. 23


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Keywords:biodegradation,biodeterioration,Franconia,Germany,historicbuildings,1

monuments,natureconservation,protection,wallvegetation2

3

ListofAbbreviations:4

BRT:Boostedregressiontreeanalysis5

NMDS:NonmetricMultidimensionalScaling6

7

8


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Introduction1

Thepreservationofhistoricmonumentsandbuildings,whichrepresentacountryscultural2

heritage,constitutesahighsocietalpriority.Futuregenerationsmusthavetheopportunityto3

witnessformersocialstructures,theendeavour,aestheticsentimentsandarchitectural4

achievementsoftheirancestors.5

Anothersocietalpriority,evenaffirmedininternationalcontracts,istheconceptof6

maintainingbiodiversity.Manyrareandprotectedspeciesareboundtonutrientpoor7

habitatswithspecificmicroclimaticconditionssuchasrocks.Othersdependonlow8

disturbancefrequencyandlongtermstablesiteconditions.Bothpreconditionsarerarely9

foundinculturallandscapesbutgivenatcastlesandruins.InCentralEurope,manyofsuch10

anthropogenichabitatsexistsincecenturies.11

Wheneverbothsocietalambitionsmeetatthesameobject,likeanoldcastleorcitywall,they12

tendtoexcludeeachother.Frequently,prioritisationleadstowithdrawalatthesideofnature13

conservation.Itisawidelyheldbutunprovenbeliefthatallplants,fungi,lichensoranimals14

arecausingdamagetohistoricmonuments.15

Besidestheaestheticsurplus,whicholdcastlesorcitywallscangainthroughplantcover16

(Pacini1994),oldmonumentsoftenprovidehabitatsforhighlyspecialisedanimalsandplants17

(Gilbert1992,Picketal.2002).Aninfluenceofthesurfacestructureofwallsonbiological18

diversityisdocumented(Prietoetal.1999,Duchoslav2002).However,approachesarerare19

thatquantifytheinfluenceofstructuralpropertiesonbiologicaldiversity(butseeDarlington20

1981).Asoundstatisticalproofforalinkagebetweenbioticdiversityandheterogeneityof21

wallsurfacesisstillmissing.22

Modernbuildingtechniquesareavoidingopenjointsandnichesthatserveforinstanceas23

protectedhidingplacesforanimalsbutalsoasgerminationsiteforplants.Specificmural24


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vegetationishencerestrictedtooldconstructions.Despitethis,itissurprisinglyuncommon1

toseebuildingsasvaluablehabitatsforbiotathatrequireprecautionduringrestoration2

processes.3

Duringthecourseofconstructionalrestorationat(historical)buildingsdrymasonrywallsare4

oftenjointed,cracksarefilledwithgroundingmortarandthesurfacesarecleaned.In5

consequence,thecharacteristicmuralvegetationaswellashabitatsofmanyanimalspecies6

(e.g.birdsandbats)arelost.7

Here,westudyfourmedievalcastlesaccordingtoimpactsofdifferentrestorationtreatments8

onplantcommunitiesinordertoevaluatetheimpactsofrestorationtechniques.Toassesbest9

practicerestorationtechniquesforbiologicaldiversityweinvestigatedtheinfluenceofwall10

structuresonfloristicdiversity.11

12

MaterialandMethods13

Studyareaandcastles14

Thestudyarea(Figure1)islocatedinUpperFranconiaandischaracterisedbylowmountain15

ranges.ThestudiedfortressFestungRosenbergandthecastlesGiechburg,Burg16

WaischenfeldandBurgRabensteindifferinregardtohistory,climateandlandscapetraits.17

Asthemonumentswereconstructedwithstonesfromlocalparentmaterial,thebuilding18

materialischaracteristicforthelandscapematrixofthemonuments.Table1providesan19

overviewonabioticfactorsandhistoriccharacteristicsoftheexaminedcastles.20

21

Vegetationdataandsampledesign22


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Vegetationandrelatedenvironmentalparametersweresampledonsevenwallsofthefour1

selectedcastles(table1)summarisingavarietyofdifferentmonumentrestorationtreatments2

(table2).OfspecialinterestisFestungRosenberg,wheredifferentrestorationtechniques3

wereappliedonthreepartsofthefrontwallofWaffenplatzPhilippin2001(Figure2).4

Impactsonwallflora,feasibilityandcostsofconservationaredepicted(Box1).5

Temperatureandwateravailabilityonawalliscloselyrelatedtoitsaspect(Werneretal.6

1989).Thus,speciescompositionofvascularplants,mossesandlichensoftenvariesstrongly7

betweennorthandsouthfacingwalls(Segal1969,Weber&Bdel2001).Evenifsome8

studiesdidnotfindaspecttosignificantlyinfluenceplantcover(Bellinzonietal.2003),inour9

studytheexaminedwallsaremicroclimaticallystandardizedtosouthorsouthwest10

orientation.11

12

Theappliedplotsizeof1misregardedtorepresentanadequateplotsizeforwallvegetation13

(includingmossesandlichens)(Darlington1981).Viastratifiedrandomsamplingthreeplots14

wereplacedontheupperandlowerpartsofeachcastlewall,respectively.Thisapproach15

enabledaseparatesamplingoftheupperwallpartthatischaracterisedbyextremedrought16

stress,aswellasofthelowerwallpartswithhighdisturbanceintensityandnutrientinputs17

(Gilbert1992).Altogether42plotswereestablished(6oneachwall)andrecordedin200618

and2007(Lichensonly2007).Speciesfrequencieswereassessed.Eachplotwasdividedin2519

subplotsof0.04m2size(Figure3)andspeciespresence/absenceforvascularplants,mosses20

andlichenswererecorded.Plantrecordsof2006and2007weresummarisedtakingthe21

meanfrequencyofaplantspeciesinaspecificplotofbothyears.Nomenclaturefollows22

Oberdorfer(1990)forvascularplants,Frahm&Frey(1992)formossesandWirth(1995)for23

lichens.24

25


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Abioticvariables1

Whileexpositionwasheldconstantatallsamplingsites,otherabioticinfluences,namely2

wateravailability,thequalityofsubstrate,andsurfacestructureofthewallwereanalysedin3

detail.4

Qualityofbuildingmaterial(stonesandmortar)isinfluencingthevegetationonwallsfor5

instanceviapH,nitrateorcalciumavailability(Segal1969,Liscietal.2003).Therefore6

substratesamples(ca.12cm)wereanalysedforeachplot.Withionchromatographythe7

contentofsodium,potassium,calcium,magnesium,ammoniumaswellasfluoride,chloride,8

nitrate,phosphateandsulphatewasmeasured.9

Toestimatetheavailablewaterelectricconductivitywasmeasuredfourtimesperplot.In10

addition,highresolutioninfraredphotosweretaken.However,detailedanalysesofthe11

resultingestimatesofmoistureindicatedthatbothmethodologiesarenotprovidingreliable12

resultsandwerethusnotincludedinfurtheranalyses.13

14

Wallstructure15

Toquantitativelyrecordthestructureofwallsurfaceagridofprofiledrawingscomparableto16

elevationprofilesinlandscapeswasfoundtobemostsuitabletoelaboratemetricsthatcould17

quantifythestructureofthewall.Theprofilesweregainedviaacontactbasedcontour18

measurementsensor(Figure4a).Thisapproachisnotbiasedbyinsolationandshadow19

(Pavlidisetal.2007).Foreachplotthreedirectionandcrossdirectionprofilesof90cmlength20

wereconductedinastandardisedprocedure.Theprofilesweredigitalisedwitharesolution21

of1mm(Figure4a,b).Basedontheseprofilesavarietyofdifferentparametersthat22

adequatelyresemblethestructuralheterogeneityofthewallsurfacewerecalculated(Table23


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3).Ifnotmentioneddifferently,themeanvalueofthoseparametersperplotwastakenfor1

furthercalculations.2

3

Calculations4

Environmentalvariableswerestandardised(scaledtozeromeanandunitvariance).All5

analyseswereperformedinthestatisticalprogramR(RDevelopmentCoreTeam2010)6

Boostedregressiontreeswereusedtodetectdriversofspeciesrichnessforallgroups7

(vascularplants+mosses+ferns)jointlyaswellasseparately.Allenvironmentalvariables8

wereincludedaspredictors.Boostedregressiontreeswerecalculatedusingfunction9

gbm.step(gbm1.63)asprovidedinElithetal.(2008).Modelsettingsaswellassummary10

statisticscanbedepictedfromtable4.11

NonmetricMultidimensionalScaling(NMDS)wasusedtovisualisethesimilarityinspecies12

abundanceandcompositionoftheplots.TheappliedBrayCurtisindexisindependentfrom13

thedatadistributionandthusidealfornonnormaldistributeddata(McCuneandGrace14

2002).ByusingNMDSthenumberofdimensionsintheordinationspacehastobedefineda15

priori.Twodimensionswerechosentofacilitatevisualisation.QualityofaNMDScanbe16

estimatedbythestressvalue.Lowstressvaluesindicateagoodfitofthedistancesbetween17

thesamplestothedissimilaritiesofspeciesassemblages.Stressvaluesbelow20are18

consideredtoyieldacceptableresults(McCune&Grace2002).Stressvalueswere15forall19

vegetation,13forvascularplants,12forbryophytesand11forlichens.Theappliedfunction20

metaMDS(vegan1.171)choosesastartingconfigurationclosetoalocalstressoptimum.21

Iterativelynewconfigurationsarecalculatedandcomparedtopreviousresultsusing22

Procrustestesttoobtainanoptimalvalue(Oksanenetal.2010).Correlationbetween23

measuredenvironmentalvariables(abioticandstructural)andthefirsttwoNMDSaxeswas24


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assessedwithsquaredcorrelationcoefficientasthegoodnessoffitstatistic.Apermutation1

testwith10,000iterationswasappliedtoassesssignificance.Onlyrelevantvariables(p2

0.01)werevisualised.Toevaluatethecontributionofsinglespeciesgroups(vascularplants,3

bryophytes,lichens)totheoverallpatternofcombinedvegetation,NMDSaxesscoresof4

combinedandseparatedanalyseswerecorrelatedusingPearsoncorrelation.5

6

Results7

Environmentalcharacteristicsofwallsubstrate8

Amongtheinterrelationsofvariablesmeasuringwallchemistryandthosemeasuringwall9

structure(Figure:Overviewintheappendix)thePearsonproductmomentcorrelationofpH10

with"surfaceheterogeneity"(r2=0.54***,negative)aswellas"5cmsurfacefluctuations"11

(r2=0.50***,positive)isofspecialinterest.12

ThepHvaluesofthestonesvarybetweenpH6.5andpH9.6.AttheGiechburgandtheBurg13

WaischenfeldvaluesofpH8weremeasured.WhilethepHvalueof8.5atBurgRabensteinis14

slightlyhigher.ThepHvalueatthecastlesbuildfromsandstoneshowedvaluesbetweenpH15

6.7andpH7.9(meanvalue:pH7.2).ThepHofmortarwasaroundpH8.16

TheammoniumconcentrationofconstructionstonescorrelatesnegativelywiththepH17

(r2=0.17**).18

Chloride,sodiumandsulphaterelatetothecorrespondingsaltionsNaSO4andNaCl.The19

correspondingcontentsinmortarandstonesarehighlycorrelatedwithr2upto0.80.The20

highestsaltcontentswerefoundattheGiechburg.Thevaluesoftheothercastlesdidnot21

differsignificantly.22

23


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Speciesrichnessandcomposition1

Ingeneralthespeciesrichnessofallvegetationattheinvestigatedwalls(figure5)ishighon2

surfaceswithahighnumberofjoints(BRTresultsinfigure6,table4forsummarystatistics).3

However,incontrasttoourexpectations,largerirregularitiesareassociatedwithlowspecies4

numbers.Thevascularplantsaremainlyresponsibleforthisresult."5cmsurface5

fluctuations"isoneofthemostimportantpredictorsforthisgroupofspecies.Theindex"56

cmsurfacefluctuations"hasanegativePearson'sproductmomentcorrelationwith"surface7

heterogeneity"(r2=0.37***)andapositivecorrelationwith"finestructure"(r2=0.21**).The8

negativePearson'sproductmomentcorrelationof"5cmsurfacefluctuations"ismuch9

strongerwithcumulativeabundance(r2=0.24***)thanwithspeciesrichness(r2=0.06notsig.).10

Increasing"surfaceheterogeneity"isfollowedbyanincreaseinrichnessofbryophyteswhile11

thenumberoflichensdecreases.12

RichnessofthewholevegetationseemstobeindependentfrompHdespiteasuddendropin13

speciesnumbersbetweenpH7.5and8.Theoppositepatterncanbeidentifiedforcalcium14

andmagnesium,whereanincreaseisalignedwithmorespecies.Hereagainbryophytes15

behavediametricallytolichenswiththelaterincreasinginrichnesswithcalciumavailability16

whilethenumberofmossesdeclines.Interestinglyanincreaseincalciumcontentofthe17

mortar(notshownforlichens)enhancesspeciesrichnessinbothgroups.Sulphateinbuilding18

stonesisconnectedwithlowspeciesdiversity.19

Both,variablesofwallchemistryaswellasthenewdevelopedindicesforwallheterogeneity20

areappropriatetodifferentiatetheinvestigatedcastlesaccordingtotheirspecies21

composition(NMDSinfigure7).Bothvariablegroupscontributealargefractionof22

explainablevariationasrevealedbyvariationpartitioningusingRDAwithconstrained23

predictors(figure8).24


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Vascularplantsandbryophytesaremorescatteredinordinationspace(theirspecies1

compositionislessuniform)andplotsofthedifferentcastlesarenotseparated(figure7).2

Onlyafewenvironmentalvariablesareexplainingthepatternwithinthesegroups.Lichens3

seemtobemostrelevantforthedistinctionintheoverallNMDS.Comparedtotheother4

groups,theydependmoreonstructureandenvironmentthantheothergroups.Thefirstaxis5

oftheNMDSanalysisforthecompletevegetationiscorrelatingwiththefirstaxisoflichens(r:6

0.73),thefirstaxisofvascularplants(r:0.65)andthefirstaxisofbryophytes(r:0.37).The7

secondaxisofallvegetationiscorrelatedtothesecondaxisoflichens(r:0.48)andtothe8

firstaxisofvascularplants(r:0.42).Othercorrelationsamongaxesshowedanrbelow0.2.9

10


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Discussion1

Ifcastlewallsaredifferentiatedbasedontheirnaturalcover,thenlichensarethespecies2

groupofchoice.Lichensarecloserassociatedwithbuildingmaterialthanotherspecies(Segal3

1969,Gilbert1992).Theyaredirectlyaffectedbymoistureandchemicalconditionssuchas4

pH(Prietoetal.1999,Weber&Bdel2001,Liscietal.2003,Sparriusetal.2007).5

6

Mossesandlichensadherelikeasecondskintothecastlewallsurfaces.Oftenthefirst7

colonizersonmonumentalwallsarelichensbutdifferonthedifferenttypesofsubstratum8

theyliveon.Weber&Bdel(2001)showthatlichenspecieswhichwherefoundonalkaline9

substratumlikemortararecolonizingonthehabitatfasterthanspeciesonacidicsubstrate.10

Theirgrowthisnotdependentongroutsorcracksbuttheirgrowthspeedvariesconsiderably11

betweenspecies.Somelichenspecieswithbroadecologicalamplitude,suchasCaloplaca12

citrinaorLecanoradispersa,werefoundonallstudiedcastles.13

14

Lichens,especiallycrustoselichens,canpenetratethewallsurfaceandareinveryclose15

contacttothewallsubstrate.Thereforetheycanonlyberemovedwithalastingeffectby16

aggressivemethodsthataffectalsothebuildingmaterials.17

18

TheuseofcalcareousmortarexplainstheoccurrenceofcalcicolelichensatFestung19

Rosenberg(seePrietoetal.1999).Themortarissoftanderodesmuchfasterthanthestones.20

Thusthedilutionofprecipitationandthealkalineerodedmaterialispreferredespeciallyby21

fastestablishingspecieslikeCollemacrispum.22

23

Boostedregressiontreeresultssupportacertaindegreeofinteraction(namelycompetition)24

betweenmossesandlichens,whichcannotbedetectedforvascularplants.Mossesand25


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lichensgrowdirectlyonthestonesurfacewhichisnotsuitableforrootingvascularplants.In1

ourstudy,speciesrichnessinlichensincreaseswithcalciumcontentofthestoneswhilethe2

numberofmossesdecreases.Interestingly,anincreaseincalciumcontentofthemortar(not3

illustratedforlichensinfigure6)supportsspeciesrichnessinbothgroups.4

5

Nitratecontentisexpectedtohaveaneffectonwallvegetation(Werneretal.1989).Wefind6

theammoniumcontentatFestungRosenbergtobemuchhigherthanatothercastles.The7

elevatedvaluesatthe"environmentalfriendly"renovatedpartindicatethattheoriginally8

usedmortarorsubstrateintheopenjointsisstilleffective(compareWerneretal.1989).9

Vascularplantsaredependentonstructureslikejointsorgapswheretheycanroot10

mechanicallyandhaveaccesstoasubstratethatsupportswaterandnutrients(Duchoslav11

2002).Thus,roughsurfacesshouldhostmorespecies.Ingeneralthisexpectationis12

confirmed,butinterestingcasesweredetected.Especiallythedecayinvascularplantrichness13

with"5cmsurfacefluctuations"(largerirregularities)wassurprising.Thenegative14

relationshipwith"surfaceheterogeneity"indicatesthat"5cmsurfacefluctuations"mightbe15

associatedtobuildingstylewithregularandthuslessheterogenicstonearrangementhaving16

morealternations."5cmsurfacefluctuations"areespeciallylowatFestungRosenberg.17

FestungRosenbergis,likepartsoftheGiechburg,buildfromsandstone.Stonearrangementis18

thusmoreregularthanattheothercastles.FestungRosenbergisexceptionalrichinvascular19

plans.Differentiatingtheeffectofbuildingstonesandstonearrangementwillneedthe20

extensionofthestudytofurthercastles.Thereishardlyanydifferenceinspeciescomposition21

betweenFestungRosenbergandBurgRabenstein.Thebuildingmaterialhasonlylittleeffect22

viathepHasplantswillgrowoncalciumenrichedmortar(Werneretal.1989,Gilbert1992).23

SpeciesthatprefercalciumrichhabitatslikeAspleniumruta-murariaarealsogrowingat24

FestungRosenbergasthemortarisproducedfromdolomite.25


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1

Eventhoughthereisnonegativecorrelationbetweenthenumberoflichenandmossspecies,2

theincreaseofmosseswith"surfaceheterogeneity"andthedecayoflichenspeciesrichness3

canbetheresultofcompetitionbetweenbothgroups.Mossspeciesareprobablynotasgood4

adaptedtosmoothsurfacesthanlichens,aninstancethatwouldbeexpectedowingthetight5

spatialarrangementoflichenspeciesonthewallsurface.6

Whatcanwelearnfornatureandmonumentrestoration?Ithasbeenshownthattheassumed7

"environmentalfriendly"restorationreallyresultsindifferentspeciescomposition.8

Dependingonsurfacestructure,buildingstonesand(veryimportant!)thechemistryofthe9

usedmortar,differentspeciesgroupswillbesupported.Thisdoesnotinterferewith10

monumentrestorationgoals.11

Theassumptionthatwallvegetationisdamaginghistoricbuildingsisstillwidelyaccepted12

(Mishraetal1995;Liscietal.2003;LeeandYi2007;Ciceketal.2009).Inthe19thcentury13

wallvegetationhasbeennamed"greenvandalism"(Scheiger1857).Today'swordinghas14

changedto"biodeterioration"andacleaningofthebuildingfromvegetationisarrogated15

(Mishraetal1995;Liscietal.2003;Lee&Yi2007).Infact,thelateralgrowthofwoodyplants16

(rootsandshoots)hasthepotentialtobreakwalls.17

18

However,itisstillunderdebatewhetherbelowgroundpartsoflichens,herbsandgrassesdo19

imposeharmfulpressure(Liscietal.2003)ornot(Honeyborne1998).Detailedanalysesof20

stonemicrostructureconductedatFestungRosenbergbyDrewello&Schmiedinger(2007)21

haveshownthatneitherhigherplants(withtheexceptionofwoodyplants)normosses22

acceleratebiodeteriorationofthesandstone.Thevegetationhaseithernoneoraprotective23

effect.Theabundanceoflichensmaysupportasealingofstonesurfacesandpreventserosion.24

Constructiveandbiogenicinducedcarbonateaccumulationunderneaththesurfaceofthe25


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sandstonehasadecelerationeffectonthecorrosivedegradation.Onlythecrustoselichen1

Lecanoracampestrismaycausepermanentdamagesinsingularcasesatsouthfacingwallsat2

FestungRosenberg.GranitechurchesincoastalGaliciaindicatethatlichencoverprotects3

wallsfromsaltinduceddisaggregation(Carballaletal.2001).Theauthorsproposeadirect4

protectionoftherockagainstsaltoradecreaseinthenumberofharmfulwetdrycyclesbya5

balancinginfluenceoflichens(alsoproposedinHoneyborne1998).Thereareindicationsfor6

chemicalerosionpotentialofsubstances(oxalicacids)emittedfromlichens(Ciceketal.7

2009),whichvariesinrespecttospeciesandsubstrate(Liscietal.2003).However,the8

erosionpotentialoflichensissuspectedtobeminimalincomparisontoabioticerosion9

(Honeyborne1998).10

11

Moistureisapreconditionfortheestablishmentofwallvegetation(Werneretal.1989).Asa12

positivefeedback,vegetationissuspectedtoincreasewallmoisturebyshieldingthesurface13

frominsolation.However,thisisnotnecessarilyaproblemasplantcoveralsopreventsheat14

lossbyradiationanddecreasesthenumberofharmfulfrostevents(Honeyborne1998).15

Theeffectivenessofrestorationworkisquestionedbythespeedoflichenrecolonisation16

whichmayoccurwithinfewyears(Silvaetal.1997,Nascimbene&Salvadori2008,17

Nascimbeneetal.2009).Duetospeciesspecificreactions,thesuccessfuluseofherbicidesis18

notguaranteedandregrowthisnotprevented(Mouga&Almeida1997,Nascimbeneetal.19

2009).Asspeciescompositionvariesbeforeandafterrecollonisation,itmightbepreferable20

toretainamoreoriginalanddiversecommunitiesonwallsthantoapplyonlyshortlasting21

restorationwork(Nascimbeneetal.2009).Theremovalofvegetationis,withtheexceptionof22

woodyplants,questionableformonumentrestoration.Aneffectivecleaningwouldalterthe23

wallsurfaceandisalignedwithaconsiderablelossofmaterialwhilebeingnonsustainable24


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(DrewelloandSchmiedinger2008).Both,natureconservationandmonumentconservation1

goalscanbeachieved.2

ThetypeofhabitatthatisprovidedbyhistoricmonumentshasbecomerareintheEuropean3

culturallandscape.Butdespitethisvaluefornaturepreservation,thespecificvegetationof4

wallsisalsoofculturalandhistoricimportance.Alargefractionoftheplantsstillgrowing5

nearcastleshavealreadybeenusedinthemedievaltimesforfoodorhealing(Dehnen6

Schmutz2004).Othershadamoreornamentalorevenmagicpurpose.Inmanycases7

knowledgeontheoriginalusehasbeenlost.Notwithstandingwallvegetationhas8

characterisedthehistoricpictureofmonasteries,churches,citywallsandcastlesforcenturies9

andtheirconservationisthusalsointheinterestofhistoricconservation(DehnenSchmutz10

2004).11

Spreadingrandomplotsonthesamecastlewallsdoesnotresultintruerepetitions.The12

resultingplotsarespatiallyautocorrelatedandviolatetheassumptionofindependence.The13

aggregatedarrangementoftheplotsbelongingtoonecastleintheNMDSresultsshowsthe14

similaritybetweenplotsbelongingtoonecastle.Outofpracticalreasonsastatisticallyperfect15

samplingdesignisoftennotfeasible.Anindependentdistributionofseveralplotspercastle16

wallisacompromisethatisnotuncommoninpraxis(Leps&Smilauer2003).Extendingthe17

studytofurtherlocationswouldenhancestatisticalcertainty,butiscostlyintermsoftime18

andmoney.Thechosenschematicapproachisreplicableandresultsarecaneasierbe19

comparedandtransferredthansubjectiveassessments.20

Theindicesusedtocharacterisethewallstructurewheredevelopedbasedontheoretical21

considerations.Theaimwastogainmeaningfulvaluesthatcouldbeassociatedtospecies22

richnessandcompositiononthewall.Theindicesshouldmirrorthecharacteristicsurface23

settingsoftheinvestigatedwalls.Untiltoday,nootherinvestigationofhistoricbuildingshas24

includedwallstructureinsuchdetail.Ithasbeenshownthatheterogeneityonwalls(orother25


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surfaces)canbeassessedinarepresentativewaynotonlyqualitativelybutalso1

quantitatively.Thisnovelapproachenabledustorelatesurfaceheterogeneityofwallstothe2

associatedvegetation.Anextensionofthemethodologyfroma2Dlinemeasurementtoa3D3

surfaceassessmentmight(e.g.vialaserscanning)beafeasible(albeitexpensive)taskfor4

futurestudiesinthisdirection.Atheoreticalbaselineforthisapproachhasbeenprovided5

here.6

7

8

Acknowledgements:9

ThisprojecthasbeensupportedbytheDeutscheBundesstiftungUmwelt(DBU)and10

Oberfrankenstiftung.EduardHertelandVolkmarWirthgavevaluablehelpindeterminingthelichens.11

WeappreciatedthecooperationwithRainerDrewello,RolfSnethlage,UrsulaDrewelloandLutz12

Tpfer.WealsothankDieterBrggemannfortheinfraredcamera,AlexUlmerfordatacollectionand13

photosaswellasReinholdStahlmannforgraphicalsupport.14

15


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ElithJ.,LeathwickJ.R.&HastieT.(2008):Aworkingguidetoboostedregressiontrees3

Journalofanimalecology77(4):802813.4

FrahmJ.P.&FreyW.(1992):MoosfloraUlmerVerlag,Stuttgart.5

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HoneyborneD.B.(1998):WeatheringanddecayofmasonryIn:AshurstJ.&DimesF.G.7

(eds)Conservationofbuildinganddecorativestone:part1,2nded.Butterworth8

Heinemann,Oxford.9

KraheF.(1994):BurgendesdeutschenMittelaltersGrundrisslexikon,Verlag10

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KremerH.(1974):FhrerdurchdieFestungRosenbergobKronachCarlLinkVerlag,12

Kronach.13

KunstmannH.(1965):DieBurgenderstlichenfrnkischenSchweizKommissionsverlag14

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Bunhwangsatemplestonepagoda,Gyeongju,RepublicofKoreaEnvironmentalgeology17

52(6):11931205.18

LepsJ.&SmilauerP.(2003):MultivariateanalysisofecologicaldatausingCANOCO19

UniversityPress,Cambridge.20

LisciM.,MonteM.&PaciniE.(2003):Lichensandhigherplantsonstone:areview21

InternationalBiodeteriorationandBiodegradation51(1):117.22


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MishraA.K.,JainK.K.&GargK.L.(1995):Roleofhigherplantsinthedeteriorationof3

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MougaT.&AlmeidaM.(1997):NeutralisationofherbicidesEffectsonwallvegetation5

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NascimbeneJ.,SalvadoriO.&NimisP.L.(2009):Monitoringlichenrecolonizationona9

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OksanenJ.,BlanchetF.G.,KindtR.,LegendreP.,O'HaraR.G.SimpsonG.,SolymosP.,14

StevensM.H.&WagnerH.(2010):vegan:CommunityEcologyPackageRpackage15

version1.170.http://CRAN.Rproject.org/package=vegan.16

PaciniE.(1994)PurposesandmannersofrepresentationofplantsintheEuropeanartof17

13th17thcenturyPactJournal42:172180.18

PavlidisG.,KoutsoudisA.,ArnaoutoglouF.,TsioukasV.&ChamzasC.(2007):Methodsfor19

3DdigitizationofculturalheritageJournalofCulturalHeritage8:9398.20

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WeimannR.(2002):DenkmalpflegeundkologieInstandhaltungvonkologisch22

bedeutsamemMauerwerkamBeispielderWallmauernderFestungRosenberginKronach23

BayerischesLandesamtfrDenkmalpflege,Mnchen.24


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PrietoB.,RivasT.&SilvaB.(1999):Environmentalfactorsaffectingthedistributionof1

lichensongraniticmonumentsintheIberianpeninsulaTheLichenologist31(291305).2

ScheigerJ.(1857):VondemEinflussederPflanzenaufdieZerstrungderRuinen3

BerichteundMitteilungendesAltertumsVereineszuWien2:16.4

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SilvaB.,PrietoB.,RivasT.,SanchezBiezmaM.J.,PazG.&CarballalR.(1997):Rapid6

BiologicalColonizationofagraniticbuildingbylichensInternationalBiodeterioration7

andBiodegradation40(263267).8

SparriusL.B.,AptrootA.&HerkK.v.(2007):Diversityandecologyoflichensonchurches9

intheNetherlandsNovaHedwigia85(35):299316.10

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computingRFoundationforStatisticalComputing,Vienna,Austria.ISBN3900051070,12

URLhttp://www.Rproject.org.13

WalterE.(2003):1000JhrigesKronachStadtundUmgebungHeimatbeilagezum14

OberfrnkischenSchulanzeiger,Nr.308,Bayreuth.15

WeberB.&BdelB.(2001):Mappingandanalysisofdistributionpatternsoflichenson16

ruralmedievalchurchesinnortheasternGermanyLichenologist33:231248.17

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WirthV.(1995):DieFlechtenBadenWrttembergsUlmerVerlag,Stuttgart.20

21

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FIGURELEGENDS1

Figure1:StudyareasituatedinUpperFrankonia.ReinholdStahlmann,adaptedfromBayerischesLandesamtfr2

Umwelt(2007)3

Figure2:TestingwallwiththreedifferentrestorationtechniquesatWaffenplatzPhilipponFestung4

Rosenberg.PhotoAlexUlmer.5

Figure3:Plotof1msizeatcastleRabensteinwith25subplotsforfrequencyassessment.6

Figure4:Surfacestructureofeachplotisgainedviathreedirectionandcrossdirectionprofilesof90cmlength.7

Aframesupportsstandardisedmeasurement(a).Comparisonofprofilesfromaplot(b)attheFestung8

Rosenberg(compromisesolution)andanotrenovatedplotatBurgRabenstein(c).9

Figure5:Speciesrichnessattheinvestigatedsamplingsites.Refertotable2foranexplanationofthe10

abbreviations. 11

Figure6:Boostedregressiontreesforspeciesrichness(vascularplants+mosses+ferns).Percentagesvaluesin12

parenthesesdemonstratetherelativeamountofpredictivevariationexplainedbythesevariablesitselffromthe13

totalvariation.Rugplotsinsetattopofplotsshowdistributionofsitesacrossspecificvariableindeciles(asin14

Elithetal.2008).Soilvariablestendtohavelargerangeofvalueswithoutrepresentationinthedataset(norug15

plotinsets).Thesegapsshouldnotbeinterpreted.16

Figure7:SampledwallsareseparatedbyanNMDSforallspeciesgroups(a).Ananalysisofvascularplants(b)17

andbryophythes(c)revealsmuchmorescattered(dissimilar)speciescomposition.Thepatternforlichens18

indicatesthatthisgroupisprimarilyresponsibleforthecleardistinguishingofsampledwallsintheanalysisof19

allspeciesgroupscombined.Environmentalvariableswerefittedtotheaxisscoresandtestedonsignificance20

usingpermutationtest.Onlyvariableswithp>0.01aredisplayed.21

Figure8:VariationpartitioningusingRDAexplainingvariationinspeciescompositionwithconstrained22

predictors.23


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BOXANDTABLES1

Box1:

DifferentrestorationtechniquesatFestungRosenberg

Inordertoinvestigatethe(dis)advantagesofmonumentrestorationactivities

intermsofimpactonwallfloraandfauna,feasibilityandcostsofrestoration,

threedifferentrestorationtechniqueswereconductedin2001onawallat

WaffenplatzPhilipponthenorthernsideofFestungRosenberg.Waffenplatz

Philippbelongstothepartofthefortressthatwaserectedaround1750.Each

restorationtechniquewasappliedona11x4msizedpartofthewall(Figure

2).

Duringtheenvironmentalsoundrestorationonlywoodyplantswere

removed.Allfascularplants,mossesandlichenswereleftonthestonesand

withingaps.Thehumuslayeronthewallcopingwasliftedandrefittedafter

restorationwork.Wallsurfacewasonlycleanedonthoseplaceswere

restorationwasconducted.Groutingwasreducedtoanecessaryminimum.

Fortheconventionalrestorationallplantcoveronthewallandthehumus

layeronthewallcopingwasremoved.Thewallsurfaceandgapswerecleaned

entirelywithsuperheatstream.Gapslargeronecentimetreweregrouted.

Surfacedefectswereclosedusingepoxideresinwhileimbuedandvulnerable

areaswereclosedusingcommonlimecementmortar.

Thethirdapplicationwasacompromisesolutionbetweenthetwoformer

mentionedmethods.Whilemossesandlichenswereleftinthegaps,woody

plants,herbsandgrasseswereremoved.Thehumuslayerwasliftedand


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refittedafterrestorationwork.Onlythoseplaceswererestorationwas

conductedwerecleanedwithsuperheatstream.Groutingwasreducedtoa

necessaryminimum.(Picketal.2002)

1


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1

Table1:Abioticconditionsandsomehistoryoftheexaminedcastles.Sampledwallsare

indicatedinblue.Mapssources:Rosenberg:Walter2003;Rabenstein:adaptedfrom

Kunstmann1965;Giechburg:Neundorfer1976;Waischenfeld:Krahe1994.

Rabenstein(limestone,390ma.s.l.,688mmannualprecipitation,

7.9Cmeantemperature).FirstmentionedAD1188wasfoundedby

theEdelfreienvonWaischenfeldtoprotectthetradingroadscoming

fromthePegnitzvalleyinthesouth(Kunstmann1965).Thecastlewas

heavilydamagedordestroyedandrebuildseveraltimes(Stdtekrieg

of1388,Frstenkrieg146062,ThirtyYears'War16181648)andits

holderschanged.Since1976itisusedasahotel.(Eckertetal.1992)

Waischenfeld (limestone,401ma.s.l.,688mmannualprecipitation,

7.9Cmeantemperature)firstmentionedAD1122,belongedtothe

EdelfreienvonWaischenfeldbeforeitchangedholdersseveraltimes.

Thecastlewasdestroyedin1430(HussiteWars)andplunderedin

1553(MargraveWar)butenduredtheThirtyYears'Warundamaged.

Thewallanda1754buildpalacehavebeenrestoredwhileremainsof

theoriginalpalacewereremovedin1876.Thecastlenowbelongsto

thecityofWaischenfeldandhostsgastronomyandamuseum.(Eckert

etal.1992)

Giechburg(limestone/sandstone,530ma.s.l.,701mmannual

precipitation,7.6Cmeantemperature)firstmentionedAD1125is

buildonahillalreadypopulatedinprehistorictimes.Thecastlewas

destroyedandrebuildseveraltimes(1430HussiteWars,1525

GermanPeasants'War,1553secondMargraveWar).Thecurrent

wallsandtowersdatebacktofortificationsofFrstbischofJohann

PhilippvonGebsattelin15991609.TheGiechburgtwithstoodthe

ThirtyYearswarbutwasnearlydestroyedaround1800byaroyal

Bavarianinspectorwhowantedtocreatearomanticruinby


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removingtheroof.Now,theGiechburgbelongstothecountyof

Bambergandhostsgastronomyandexhibitions.(Eckertetal.1992)

FestungRosenberg (sandstone,378ma.s.l.,660mmannual

precipitation,7.8Cmeantemperature)wasthenorthwardstronghold

oftheBistumBambergandprotectedthestrategicallyimportant

tradingrouts.FirsttowerswerebuildAD11281130andlateron

fortified.ThenameRosenbergisfirstmentionedAD1249.Itbecamea

bishop`sdistrictcastleinthe14thcentury.Thesecondwallwasbuild

endofthe15thcentury.NeithertheHussits,theenemiesofthe

MargravenortheSwedishforcesintheThirtyYearsWarwereableto

conquerthestronghold.Thepentagonshapedpresentouterwallwas

buildAD16561700.ThefortresswasunderusebyNapoleonsarmies,

Bavarianmilitary,andservedinthefirstworldwar19151918asa

prisonhostingamongothersCharlesdeGaulle.Concreteandsteel

workwasdoneinpartsofthefortressduringsecondworldwar.

TodaytheRosenberghostsayouthhostel,gastronomyandamuseum.

(Kremer1974;Walter2003)

1

2


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1

2

3

Table2:Sizeofsampledcastlewallsandassociatedrestorationtechniques.Oneachwallsix

plotsof1mwhereestablished.

Castle Restorationtype Wallsize Abbreviation

Waischenfeld conventionalrestoration3040

yearsbeforesampling

11x4m Wfd

Giechburg conventionalrestoration 11x4m Gbg

Rabenstein conventionalrestoration 3x2.80m Rsncr

Rabenstein norestoration 11x3m Rsnnr

Rosenberg conventional

restorationrestoration

11x4m Rbgcr

Rosenberg environmentalsound

restorationrestoration

11x4m Rbger

Rosenberg compromisesolution 11x4m Rbgcs


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1

Table3:Thebelowdescribedcoefficientswereusedtomeasurethestructuralheterogeneityofthewallsurface.Foreachplotsixprofilesof90cmlengthweremeasured(threedirectionandthreecrossdirection).Themeanofthecoefficientvaluesofallsixprofilesweretakenastheplotvalueforcalculation.Thelengthsoftheprofilelinewasnotsuitableforacomparisonasmany

smallscalevariationsinsurfacestructureleadtocomparablevaluesasfewlargescalevariations.

name description formula

surfaceheterogeneity

(variation

coefficient)

Thevariationcoefficientindicatesvariationindepths.Itisanormalisedmeasureofdispersion.

Thelargerthevalue,themoredifferentarethedepthsvaluesfromtheirmean.

:standarddeviation:meanvalueofdepths

5cmsurface

fluctuation

(DeltaT5)

DeltaT5measuresthechangeindepthper5

cm:Thelargerthevalue,thedeeperarethejoints,themoreheterogenicisthesurface.

xi:valueofdepthsmaximumjointdepths

Maximumpositivedeviancefromthemean:thedeepestjointorgabinthewall.

xi:valueofdepths

:meanvalueofdepthsJointfrequency

(intersection

points)

Thenumberofintersectionpoints withthefictivemeanline.Aflatwallwithfewjointswillhavelessintersectionpointsthanarubblemasonry.

xi:valueofdepths

:meanvalueofdepthssurfacesmoothness

(autocorrelation)

Theautocorrelationmeasurestheprobabilitythatjoints,gabsandothersurfaceirregularitiesonlyvarywithinacertainrange.Lagvaluesof1,3,5and10cm(seeequation)wereapplied.

xi:valueofdepths(1mmdifference):lagvalue(here1,3,5or10cm)

:meanvalueofdepthsfinestructure

(periodicity)

Slopeofthelogtransformedperiodogram(functioninfrequencyspaceafterFouriertransformation).

Measuresrecurringfineandcoarse

structuresofthewallsurface.Thelargerthevaluethefinerthestructuresandthelesslargescalesurfacefluctuations.

F():Fourierfunctionxi:valueofdepths(1mmdifference):frequence

2

3


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1

Table4:Summarystatisticsofboostedregressiontreeanalysisforspeciesrichness.In

allmodelrunsbagfractionwassetto0.75andtreecomplexityto5.

allvegetation vascularplants mosses lichens

Learningrate 0.0015 0.005 0.0015 0.005

Stepsize 50 50 50 25

Numberoftrees 1850 1700 1550 1600

Meantotaldeviance 8.642 5.812 2.738 1.27

Meanresidualdeviance 2.232 0.269 1.210 0.165

EstimatedCVdeviance 5.389

(se:1.314)

2.761

(se:0.637)

2.429

(se:0.571)

1.120

(se:0.213)

Trainingdatacorrelation 0.905 0.980 0.814 0.953

CVcorrelation 0.670

(se:0.096)

0.789

(se:0.064)

0.424

(se:0.168)

0.420

(se:0.171)

2

3


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1

FIGURES2

Figure1:3

4

5


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Figure2:1

2

Figure3:3

4

Figure4:5

6


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Figure5:1

2

3


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Figure6:1

2

3


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Figure7:1

2

Figure8:3

4

5

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