Differential preservation of anthracological material and mechanical properties of wood charcoal: an experimental approach of fragmentation

National audienceDifferential preservation of anthracological material and mechanical properties of wood charcoal: an experimental approach of fragmentatio

Impact of post-depositional processes on charcoal fragmentation and archaeobotanical implications: Experimental approach combining charcoal analysis and biomechanics

International audienceGenerallyspeaking,charcoalanalysisisbasedonidentifyingandcountingcharcoalfragmentsinordertocalculatetherelativevariationsintaxafrequency.Allpost-depositionalprocessesarelikelytoinducefragmentationoftheanthracologicalmaterial,raisingthequestionoftherepresentativenessoftaxa.Basedonaninnovativeexperimentalapproachcombiningbothcharcoalanalysisandbiomechanics,thispaperexploreshowthemechanicalpropertiesofcharcoalcaninfluencethefragmentationandthequantificationofspeciesinanthracologicalassemblages.Wecarriedoutstandardizedlaboratorycompressiontestson302samplesissuedfrom10taxa,charredatthreedifferenttemperatures,inordertocharacterizethemechanicalpropertiesofcommonspeciesintemperateandMediterraneanEurope.Ourresultshighlightthedifferentialresponsesofthetestedspeciesintermsofresistancetocompressionandfragmentation,twoprocesseswhichdonotappeartobecorrelated.Charcoalisveryresistanttopressure(upto22.5MPa).Ourresultsshowthatsignificantfragmentationdifferencesexistbetweentaxa.Thetotalnumberoffragmentsaftercompressionislargelydependentonthespecies,regardlessofthecharringtemperature.However,thisinterspecificvariabilityismoresignificantforsmallfragments[1e2mm],thanforlargerfragments[2e4mm]and>4mm,withtheexceptionofQuercus,whichdisplaysdifferentialreactionstocompression.Finally,amultifactorialanalysisbringstolighttheimpactofthephysicalandanatomicalcharacteristicsofthedifferentspeciesoncharcoalfragmentatio