4thInternationalConferenceonSoilBio-andEco-Engineering

‘TheUseofVegetationtoImproveSlopeStability’

| SBEE2016 Book of Abstracts | | 11-14 July 2016 |

| The University of Sydney, Australia |

SBEE2016ABSTRACTS

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TableofContents SESSIONTITLES&KEYNOTESPEAKERS...............................................................................................3

ORALPRESENTERS..............................................................................................................................4

POSTERPRESENTERS..........................................................................................................................7

ABSTRACTS–ORALPRESENTATIONS.................................................................................................8

DAY1-MONDAY11JULY.............................................................................................................................8 SESSION1–VegetationandSlopeStabilityI............................................................................................................8 SESSION2–SlopeStabilityModelling....................................................................................................................12 SESSION3–VegetationandSlopeStabilityII.........................................................................................................14

DAY2-TUESDAY12JULY...........................................................................................................................17 SESSION4-Eco-engineeringandlandrestorationI...............................................................................................17 SESSION5–ForestEcosystemsandWildfireManagement...................................................................................19 SESSION6–Root-SoilInteractionsI........................................................................................................................22

DAY3-WEDNESDAY13JULY.....................................................................................................................28 SESSION7-Root-SoilInteractionsII.......................................................................................................................28 SESSION8–Microbialeco-interactionswithsoils..................................................................................................32

DAY4-THURSDAY14JULY........................................................................................................................33 SESSION9-Eco-engineeringandlandrestorationII..............................................................................................33 SESSION10–Riversprotectionandcatchmentmanagement...............................................................................35 SESSION11–Hydro-geomorphicprocesses...........................................................................................................37

ABSTRACTS–POSTERPRESENTATIONS............................................................................................41

DAY1-MONDAY11JULY...........................................................................................................................41 SESSIONP1..............................................................................................................................................................41

DAY2-TUESDAY12JULY...........................................................................................................................50 SESSIONP2..............................................................................................................................................................50

SBEE2016COMMITTEES...................................................................................................................58 OrganizingCommittee................................................................................................................................58 ScientificCommittee..................................................................................................................................58

SBEE2016ABSTRACTS

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SESSIONTITLES&KEYNOTESPEAKERS

Day Session# SessionTitle KeynoteSpeakers

Mon

1 VegetationandSlopeStabilityI Prof.RoySidle

2 SlopeStabilityModelling DrMassimilianoSchwarz

3 VegetationandSlopeStabilityII -

Tues

4 Eco-engineeringandlandrestorationI -

5 ForestEcosystemsandWildfireManagement Prof.MarkAdams

6 Root-SoilInteractionsI A/ProfIanRutherfurd

Wed

7 Root-SoilInteractionsII DrFreddyRey

8 Microbialeco-interactionswithsoils Prof.DavidAirey

Thurs

9 Eco-engineeringandlandrestorationII -

10 Riversprotectionandcatchmentmanagement DrAndrewSimon

11 Hydro-geomorphicprocesses MrDavidPolster

SBEE2016ABSTRACTS

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ORALPRESENTERSPresenter Title Abstract

IDDay Session

#

MarkAdams(keynote)

BushfiresandlandscapemanagementinAustralia SBEE1 Tues 5

DavidAirey(keynote)

Bio-cementationforgroundimprovement SBEE2 Wed 8

FreddyRey(keynote)

Identificationofmulti-benefitsofbioengineeringactions

SBEE45 Thurs 9

IanRutherford(keynote)

Assumedresistance:theroleofvegetationrootsontheresistanceofriverbankstofluvialscour

SBEE3 Tues 6

MassimilianoSchwarz(keynote)

Rootreinforcementcalculations:fromsingleroottorootsystem

SBEE4 Mon 2

RoySidle(keynote) EffectsofVegetationManagementonSlopeStability SBEE5 Mon 1

AndrewSimon(keynote)

RoleofRiparianVegetationinFluvialGeomorphology SBEE6 Thurs 10

DavidPolster(keynote)

SoilBioengineeringfortheTreatmentofDrasticallyDisturbedSites

SBEE73 Thurs 11

NaziAvani EffectsofAcaciamangiumandMacarangatanariusrootsonsoilshearstrength

SBEE7 Tues 6

AgronBajraktari BiodiversityofKosovo’sForestsandIt’sEconomicValues SBEE8 Mon 1

TankaPrasadBarakoti

ImportantPlantSpeciesSupportingSoilStabilityandLandSlideControlinDifferentPhysiographicRegionsofNepal

SBEE9 Mon 3

AlexanderBast Arewoodanatomicalpropertiesandvariationsrelatedtotheroottensilestrengthoftrees?Gaininginsightsfromgreyalderandmountainmaplegrownonacoarsegrainedeco-engineeredslopeintheSwissAlps

SBEE11 Tues 6

GianBattistaBischetti

Onthepowerofstemstointerceptdebrisflowinforestedfanarea:alaboratorymodeling

SBEE12 Tues 4

DavidBoldrin DesirablePlantFunctionalTraitsforHydrologicalReinforcementofSlopes

SBEE13 Thurs 11

GianBattistaBischetti

Theroleofcultivatedgrapevinesonslopestability SBEE14 Mon 1

FranckBourrier Comparingnumericalmodellingapproachesfortheevaluationofrootreinforcement

SBEE15 Thur 9

FranckBourrier Numericalassessmentoftheprotectiveeffectofforestsandbioengineeringtechniquesagainstrockfall

SBEE16 Tues 5

SBEE2016ABSTRACTS

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WalterChen WhatIsaReasonableAmountofSoilErosion? SBEE17 Tues 4

GianBattistaBischetti

EvaluationoftheeffectsofrootelasticityonsoilreinforcementfordifferentAlpineandPre-Alpinetreespecies

SBEE18 Tues 6

MassimilianoSchwarz

SensitivityanalysisoftheSOSlopemodel:discussionontheroleofrootreinforcementandslopestability.

SBEE19 Mon 2

JulienDemenois SoilaggregatestabilityonultramaficsubstrateinNewCaledonia:untanglingtheeffectofsesquioxides,soilorganiccarbon,roottraitsandectomycorrhizainfiveplantcommunities

SBEE21 Wed 7

EwaneBasilEwane

VegetationcoverandslopeinfluencessedimentparticlesizedistributioninnaturalrainfallconditionsonpostfirehillslopeplotsinChilgok,Korea.

SBEE24 Tues 5

M.Fakig Mechanicalfeedbackbetweenagrowingrootandadeformablegranularmedium:extractingphysicallawsfromnumericalsimulations

SBEE25 Mon 1

FilippoGiadrossich

Howup-ordownslopeanchoringaffectsrootreinforcement SBEE28 Tues 6

AnnaHelfensdorfer

Roots,ShootsandRiverbankStability:Correlationsoftensilestrength

SBEE29 Tues 6

CsillaHudek Rootmorphologyandbiomechanicalcharacteristicsofhighaltitudealpineplantspeciesandtheirpotentialapplicationsinsoilstabilization

SBEE30 Tues 6

DongyeobKim LandslideHazardAssessmentConsideringSpatialUncertaintyofTreeRootReinforcementandSoilThickness

SBEE31 Tues 6

J.Kim Seasonalhydrologicalimpactsoflanduseonhillslopestability SBEE33 Thurs 11

TengLiang Realisticscalingofplantrootsystemsforcentrifugemodellingofroot-reinforcedslopes

SBEE34 Mon 2

KennethLoades Predictingrootmechanicalproperties:fibrousvs.woody,whatcontrolstheunderlyingstrength-diameterrelationshipinroots?

SBEE35 Tues 6

SherwinMervinBurtonE.Lucas

MortalityofVetiverGrassonHydrothermally-AlteredSlopesinMindanaoGeothermalProductionField

SBEE36 Thurs 11

ZhunMao Whichbioticdriverscanbetterexplainthevariabilityofrootmechanicsoftropicaltreespecies?

SBEE37 Wed 8

IanMcIvor SoiltextureinfluencesonrootdevelopmentinpoplarinNewZealand

SBEE43 Wed 7

GerritMeiger Insitumeasurementofroot-reinforcementusingthecorkscrewextractionmethod

SBEE38 Wed 7

SlobodanMickovski

Sustainabilityperformanceofecoengineringmeasures SBEE39 Tues 4

AlejandroOllauri Landslidesasdriversforslopeecosystemsevolution SBEE40 Thurs 9

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AlejandroOllauri Aproxytoquantifythehydrologicaleffectofvegetationagainstlandslides

SBEE41 Thurs 11

NormanizaOsman EcologicalParameterasIndicatorofSlopeStabilityattheGuthrieCorridorExpressway,Malaysia

SBEE42 Mon 1

AndreaRomanSánchez

Analyticalestimationofsoilerosion,depositionandbioturbationusingOSLtechniques

SBEE46 Mon 3

JunpyoSeo ComparisonandAnalysisonSedimentDischargeinDamagedandNon-damagedForests,RepublicofKorea

SBEE32 Thurs 10

IoannisSpanos Combiningbio-andeco-engineeringtechniquesinN.Greece SBEE47 Tues 5

OlivierTaugourdeau

TalVeg®:aninnovativeapproachofecosystemmanagementforenhancingmultipleecosystemservices,withafocusonsoilerosionandslopestability

SBEE48 Mon 3

WouterVannoppen

Soiltextureandrootarchitectureeffectsonconcentratedflowerosionrates

SBEE49 Mon 3

AnilYildiz Effectsofrootcharacteristicsanddilatancyontheshearstrengthofroot-permeatedsoils

SBEE50 Wed 7

SBEE2016ABSTRACTS

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POSTERPRESENTERSPresenter Title

AbstractID Day

T.BarakotiBenefitsofTerraceRiserBasedAgri-silvo-pastoralModelinSoilStability,RiserProtectionandAgriculture SBEE51 Mon

T.Barakoti BasketofAgroforestryModelsUsefulforHillsandPlainAreasofNepal SBEE52 Tues

A.Bast Mycorrhizaaspromoterineco-engineeringonmountainslopes:Inoculationeffectsonplantsurvival,aggregatestability,andfine-rootdevelopment

SBEE53 Mon

J.B.BarreAssessmentofdecayofsilverfirlogsexposedtooutdoorconditionsbynearinfraredspectroscopyandvibrationresonantmethods SBEE10 Mon

W.Chen CreatingandViewing3DModelsofRoots SBEE65 Mon

A.ErktanStabilizationofsoilaggregatesonroadsideembankmentsalonga70years-oldvegetationsuccessionalgradient SBEE54 Mon

F.Giadrossich PostfirebioengineeringremediationinPinuscanariensisforests SBEE27 Mon

F.Giadrossich ModelingbioengineeringtraitsofJatrophacurcasL. SBEE55 Tues

H.Gu EffectofheatshockonseedgerminationofthreespeciesofPinaceaeinGreatHing’anMountains

SBEE71 Mon

F.D.Hilterbrand Pull-outstrengthofPinusradiatarootsandtheircontributiontoslopestability SBEE59 Mon

Y.C.Lin Estimatingcanopyinterceptionforaspecies-richprimarytropicalforest SBEE66 Mon

I.McIvor Yoursoilisvaluable–planttreestokeepit! SBEE56 Mon

F.Preti Novelsolutionsforsoilandriverbioengineering:prefabricatedandfoldingframeworks

SBEE67 Tues

L.RossiUseofLAPSUS_LSmodeltoinvestigatevegetationinfluenceoncatchmentslopestability–AcaseofstudyinLlanoBonito,CostaRica SBEE68 Tues

M.Schwarz Rootreinforcementdynamicsincoppicewoodlandsandtheireffectonshallowlandslides:areview

SBEE57 Mon

M.SchwarzQuantifyingthestabilizingeffectofforestsonshallowlandslide-proneslopesusingSlideforNET SBEE58 Tues

M.Schwarz Anewframeworkforthequantificationofthehydrologicalconnectivityofvegetatedslopes

SBEE72 Mon

G.Z.SongSuccessionofPlantCommunitiesinLandslideSitesRemediatedwithExoticPlantSpecies SBEE69 Tues

J.PerezAnopenaccessdatabaseofplantspeciessuitableforcontrollingsoilerosionandsubstratemassmovement SBEE61 Tues

W.Vannoppen Effectivenessofplantrootsincontrollingrillandgullyerosion:Acasestudyonvegetationcommunitiesonriverdikes

SBEE70 Tues

M.WerlenAssessingtheprotectivefunctionofaforestafterafireevent:acasestudyinVallis,Switzerland SBEE60 Tues

A.Warner In-situsheartestsofsoilrootsystems SBEE62 Tues

K.ZhangExperimentalandFieldResearchonRootReinforcementandApplicationinRiverbankEcologicalProtection SBEE63 Tues

SBEE2016ABSTRACTS

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ABSTRACTS–ORALPRESENTATIONSDAY1-MONDAY11JULY

SESSION1–VEGETATIONANDSLOPESTABILITYI

Keynote–RoySidleSBEE5–EffectsofVegetationManagementonSlopeStabilityRoyC.Sidle

SustainabilityResearchCentre,UniversityoftheSunshineCoast,SippyDowns4556,Queensland,Australia

Vegetation,particularlywoodyspecies,augments thestabilityofshallowsoilmantlesbyaffecting thesoilmoisture

regime through evapotranspiration processes and providing root reinforcement within the soil mantle. Effects of

evapotranspiration on the soil moisture regime primarily include: (a) canopy interception of rainfall or snow and

subsequentevaporationlosstotheatmosphere;and(b)transpirationofinfiltratedwaterbyplantroots.Transpiration

effects are not particularly important for shallow landslides that occur during an extended winter rainy season

becausesoilsaretypicallyverywetandtranspirationprocessesarereduced,butinthetropicsandsub-tropicswhere

evapotranspirationishighthroughouttheyear,sucheffectsmaybemoresignificant.Rootreinforcementprovidesa

moresignificantcontributiontoslopestabilityby:(a)anchoringsoilmantlestounderlyingsubstrate;(b)providinga

membraneoflateralstrength;(c)lateralreinforcementacrosszonesofweakness;and(d)buttressing.Anothereffect

that is lesswell documented is theeffectofboth live anddead rootson subsurface flowpathways.Dependingon

whether rootsystemsdisperseorconcentratesubsurfacewater, theycaneither tend tostabilizeordestabilizesoil

mantles.

Because of these interacting effects of root systems, vegetation management, particularly timber harvesting and

forestconversiontoagriculturalcropsorexoticplantations,canhaveaprofoundinfluenceonslopestability.Clear-cut

timberharvestinghasbeenshowntoincreaselandslideoccurrenceby2to10-foldduringtheperiodofminimumroot

strength. This root strength minimum typically occurs from 3 to 15-20 years after woody vegetation removal

dependingonspeciescomposition,siteconditions,andstanddensity.ArecentstudyinsouthernNara,Japanshowed

thatclearcuttingsignificantlyincreasedlandslidesduringthefirst10years,whilesomeeffectscontinuedfor25years

afterharvesting.Comparedtoolderforests,landslidevolumeincreased4-foldinrecentlycutforests.Thisisoneofthe

fewstudieswherecuttingagecomparisonsweremadeacrossverysimilarsiteconditions.Modelingstudiesshowthat

uncut‘leaveareas’ingeomorphichollowsandsteepslopes(e.g.,>40°)canreduceshallowlandslides.Conversionof

nativeorsecondarytropicalforeststoexoticplantationsoragriculturalcrops(withnegligiblerootstrength),induces

longer-termslopeinstability.Knowledgeofwhichterrainismostvulnerabletolandslideinitiationfollowingvegetation

changescangreatlyassistinthesustainablemanagementofforestecosystems.

SBEE2016ABSTRACTS

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SBEE14–TheroleofcultivatedgrapevinesonslopestabilityM.Bordoni1,A.Cislaghi2,C.Meisina1,G.B.Bischetti2Institution

Rainfall-inductedshallow landslides representamajor threat forcultivatedsteep terrains.Considerabledamages in

termsofpartialortotaldestructionofcultivationstructuresand/orinfrastructures(plants,rowtillagepatterns,farm

roads) are increasingly frequent worldwide, due to intense and concentrated rainfalls and new more intensive

cultivationpractices.

In this context, a focus is required by vineyardswhich are prone to hydrogeological risk for their topographic and

climaticconditionsandwhichformasignificantportionoflocaleconomies(incomeandemployment),traditionallyin

Europebutwithanincreasingimportanceinlargeareasoftheworld.Inprinciple,infact,grapevineplantswiththeir

rootsystemsextendingdowntoadepthof1-2meterscouldprovideasignificantcontributiontosoilreinforcement

and,consequently,toslopestability.

Inspiteofthat,littleresearchhavebeencarriedoutinordertoinvestigatetheroleofgrapevineplantsonlandslides

triggering.

Within a broader framework aiming to increase our knowledge on the interaction between vineyards and slope

stability, this study objectives are: (i) to determine the root mechanical properties of grapevine roots through

laboratory tests, (ii) to evaluate the spatial distribution of grapevine root systems along the cultivated rows and

betweenthem,(iii)tocalculatethegrapevinerootcontributiontothesoilstrength,andiv)toapplyaphysical-based

slopestabilitymodeltodeterminerainfallthresholdsforshallowlandslideforecastinginvineyards.

ThestudyareaislocatedintheNorthEasternpartofOltrepòPavese,NorthernItaly,hasanextensionof250km2,and

is covered by hilly slopes cultivated from many decades with vineyards for wine production. In this area a huge

numberof landslidesoccurredduringthe last7years,withadensityof36eventsperkm2,causinggreateconomic

lossestotheagriculturalsector.

The results obtainedwill be of great help in identifying supplementary indicators for the assessment of instability

susceptibilityinthoseareaswherevineyardsarecommon,andforimprovingtheexistinghazardmapsreliability.

SBEE8–BiodiversityofKosovo'sForestsandIt'sEconomicValuesAgronBajraktari,AfrimLoku,MuhametYmeri

UniversityofAppliedSciencesinFerizaj,Kosovo

Kosovoisexceptionallyrichinplantandtreespeciesconsideringitsrelativelysmallarea.Kosovo’splantdiversityis

the result of complex interactionof physical factors creating awide variety of habitat conditions for plant growth.

Kosovo’splantdiversity is furtherenrichedby thepresenceof speciesdriven southduring iceageperiods. Forests

cover about 47%of Kosovobutonly about a thirdof this area is consideredecologically healthy andeconomically

productive.Mostoftheremainingtwo-thirdsconsistofimmaturetreesandbushylowforeststhatarecutperiodically

forfirewood.Matureoakforestsarenowhighlythreatened.Severalspeciesofplantsareknowntobeonthevergeof

extinctioninKosovoorarealreadylocallyextinct—largelyduetohumanactions.

ThefactorsthatcreatefavorableconditionsforplantdiversityinKosovoalsoexplainthehighlevelofanimaldiversity

withinthisrelativelysmallarea.Thereareanestimated46mammalspeciesinKosovo,manywithregionalorglobal

conservationsignificance.Mostoftheanimalspeciesinthecountryarethreatenedbydestructionofforesthabitats.

SBEE2016ABSTRACTS

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Aquaticecosystemsinriversarehighlythreatenedasaresultofwaterpollutionfromdomesticandindustrialsources

as well as uncontrolled sand and gravel mining in riverbeds. Much of the remaining diversity of land plants and

animalsisfoundinthehighermountainsinthesouthernandwesternregionsofKosovo.

TheSharr/SaraMountainNationalParktothesouthcovers39,000haandaproposednewparkintheAlbanianAlps

westofPejë/Pećwillprotectanadditional50,000ha.Otherprotectedareasincludetwoprotectedlandscapesand38

naturalmonuments.TourismatSharr/SaraMountainNationalParkalreadygenerates jobs intheservicesectorand

couldpotentiallybenefitfrommunicipaltaxesfromhotelsandrestaurants.Withimprovementsinthemanagementof

that park and opening of the new park, nature-based tourism could be an important source of income for local

municipalitiesandasourceofjobsfortheruralpopulation.

Kosovo’s biodiversity resources can be managed sustainably to produce economic benefits while also conserving

biodiversity.Theforestsareaneconomicallyimportantrenewablenaturalresourcewiththepotentialtosupplywood

andnon-woodproductsaswell asenvironmental services suchaswatershedprotectionandcarbon sequestration.

Kosovomust currently importmostof its construction timber andmore thanhalf of its fuelwoodbecause forests

werenotproperlymanagedinpastdecadesuptothepresenttime.AuthorsofaFoodandAgricultureOrganization

(FAO)forestsectorstudyestimatethatafterthestateforestindustriesareprivatizedandthesupplyofwoodfromthe

forestsispredictable,4,800peoplewillbeemployeddirectlyinforestryandwoodprocessing,withatotalof30,000

people employed in forest sector-related activitieswhen downstream and support jobs are included. Collection of

medicinalandherbalplantsfromtheforestsisthebasisofanindustryinKosovoandwildmushroomsandberriesare

alsocollectedforsale.

SBEE42–EcologicalParameterasIndicatorofSlopeStabilityattheGuthrieCorridorExpressway,MalaysiaO.Normaniza,H.Aimee,A.Z.NurulIzzaty,A.RMuhammadAfiq

InstituteofBiologicalSciences,FacultyofScience,UniversityofMalaya,KualaLumpur,Malaysia

MostoftheslopesoilsinthetropicalregionsuchasinMalaysiaisinfertileandlackofnutrientswhichcontributesto

reducethesurvivalandgrowthofplantsonslope.Inaddition,thereductionofplantcommunityandcoveragewould

increasetheslopeproblemsandeventuallygivesunfavourable impactonthestabilityoftheslope.Thus,thisstudy

attemptstoobservetheinfluenceofplantcoverageontheslopeplantcommunity,rateofnaturalsuccession,andthe

soilproperties.The25m2ofeachexperimentalplotweresetupwiththreedifferentcoverage;0%(TreatmentA),10%

(TreatmentB),and50%(TreatmentC) inthreereplications,attheGuthrieCorridorExpressway,Selangor,Malaysia.

Ourfindingsindicatethatspeciesrichnesscontributedtoincreasetheplantdiversity(r=0.95),indicatingthatspecies

richness would lead to the influx of new plants, and enhance the variety of plant community. In 15 months of

observation,treatmentCexhibitedthehighestincrementinspeciesrichness(Dmg)andplantdiversity(H’).Moreover,

treatment A recorded the highest succession rate which was 0.4 species influx/month. Whilst, the highest plant

coverage (50%) exhibited the highest reduction of soil saturation level and erosion rate by 81.9% and 64.5%,

respectively.Furthermore,thevalueof1.50H’hasrecordedasthecriticalvalueforthesoilsaturationlevelreduction

aswell as the soil shear strength enhancement. This critical value of plant diversity occurred in both 10% and 0%

coverageat3and12monthsofobservation,respectively.Inconclusion,higherplantcoveragewouldgiveapositive

indicatoronplantcommunityperformanceandsoilpropertiestoofferthesoilprotectionandreinforcementforthe

slopestability.

SBEE2016ABSTRACTS

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SBEE25–Mechanicalfeedbackbetweenagrowingrootandadeformablegranularmedium:extractingphysicallawsfromnumericalsimulationsM.Fakih,J.Y.Delenne,F.Radjai,andT.Fourcaud1

CIRAD,UMRAMAP,Montpellier,France

Plant roots play a key role in reinforcing soils against erosion and shallow landslides through different chemical

(formationofsoilaggregate)andphysicalprocesses(mechanicalreinforcement,waterinfiltrationandwatersuction).

Managingvegetatedslopesona longtermperspective toavoidsoil lossnecessitatesunderstandingandquantifying

thedynamicsofroot-soilinteraction.

Soil resistance to penetration is a major component that can significantly affect root growth. The impact of soil

properties on root growth has been largely studied at the root, plant and vegetation scales, mainly reducing soil

propertiestoasingleinputvariablerepresentingsoilimpedance.Howeverthemechanicalfeedbackbetweengrowing

roots andadeformable soil, is still largelyunknown. Theunderlyingquestions arehow the grains are reorganizing

undertheactionofgrowingroots,and inreturnhowtheresultingforcesactingonthegrowingroottipsmodify its

development,includingrootelongationrate,rootshapeandramification.

Westartedansweringthesequestionsinatheoreticalway,developinganumericalmodelofrootgrowthinagranular

medium. The model is based on the discrete-element method (DEM). Single roots are modelled using chains of

connectedspherolineelements.Thegrowthisinitiatedfromacircularelementplacedatthefreesurfaceofagranular

bedpreparedbyrandompluviation.Thiscircleplaystheroleofameristem,whichisconstantlyreplicatedatagiven

rateandpushedforwardundertheactionofelasticforces,generatingalineoffixedthicknessequaltothediameter

ofthecircleandwithprescribedstiffnessandbendingmoment.Theorientationofthemeristemateverygrowthstep

isdrivenbythedynamicsofthewholerootundertheactionofitsinternalelasticforcesandreactionforcesexerted

by thegrains.Thepreliminarymodel is two-dimensional,whichnotallows theporespace tobeopenedas ina3D

situation, consequently limiting root the penetration. To overcome this limitation, we introduce two different

diametersforthegrains,i.e.a“real”diameterthatisconsideredtocalculategrain-grainmechanicalinteractions,and

asmaller“virtual”diametertotakeintoaccountroot-grainsinteractions.Thedifferencebetweenthetwodiameters

correspondstothewidthofagapatcontactpointsthroughwhichtherootscanpass.Theratioofthisgaptotheroot

diameterisconsideredasamodelparameter.

Parametric studies showed the influenceof granular structureand rootmechanical propertieson root trajectories.

Theanalysisoftheevolutionofreactionforcesexertedbygrainsontheroottipexhibitedabroaddistributionofthe

forcesexperiencedbytherootapexduringagivengrowthperiod.Thisdistributionhasthesamefunctionalformfor

eachrootstiffnesswhenforcesarenormalizedbythemeanforce. It ischaracterizedbyadecreasingpowerlawfor

forcesbelowthemeanforce,andbyanexponentialfall-offforforcesabovethemeanforce,thusreflectingthebroad

distributionofforcesinsidethegranularmaterial.

Acknowledgement

This project is supported by Agropolis Fondation under the reference ID 1202-073 through the “Investissements

d’avenir”program(LabexAgro:ANR-10-LABX-001-01).

SBEE2016ABSTRACTS

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SESSION2–SLOPESTABILITYMODELLING

Keynote-MassimilianoSchwarzSBEE4–Rootreinforcementcalculations:fromsingleroottorootsystemMassimilianoSchwarz

BernUniversityofAppliedSciences,Bern,Switzerland

Root reinforcement represents a key factor in different area of engineering (slope stability, soil protection,

silviculture/treestability,stabilityofriver-banks). Inthiscontributionwereviewsomeoftheresearchdoneonroot

reinforcementquantificationandwediscusstheresultsinviewofpracticalapplications.Singlefactorsinvolvedinthe

calculationsofrootreinforcementarediscussedwithintheframeworkoftheRootBundleModelandtheapplication

ofadiscreteelementmodelforslopestabilitycalculations.

SBEE34–Realisticscalingofplantrootsystemsforcentrifugemodellingofroot-reinforcedslopesT.Liang,A.G.Bengough,J.A.Knappett,D.MuirWood,K.W.Loades,P.D.Hallett

SchoolofScience&Engineering,UniversityofDundee,Dundee,UK.

Vegetationasameansto improveslopestability iswell recognisedand incorporated ingeotechnicalandecological

engineeringpracticetoprotectslopesagainstshallowlandslides.Muchoftheresearchinthisareahasquantifiedroot

reinforcement of soil shear behaviour at prescribed soil depths in either the laboratory or the field. Costs and

practicalitylimittestingofglobalbehaviour,wherefull-scalefieldtrialscanbebroughttofailuretodetermineplant

rootimpactsonthedepthoffailureandcriticalhydrologicalconditions.Geotechnicalcentrifugemodellingoffersan

opportunity to investigate in detail the engineering performance of vegetated slopes, but its application has been

restrictedduetothechallengeofscalingplantrootsystems.Someworkhasreliedonscaledmodelroots,provided

byeitherliveplantsoranaloguematerialwithsimilarmechanicalproperties(stiffnessandstrength)andarealistic3-D

geometryatsmallscale.

For root analogues, a 3-D printing technique has recently been introduced by the authors, to reproduce

representative root morphologies with appropriate mechanical properties (Liang et al., 2015). This 3-D printing

techniquehasbeenusedincentrifugetestsofsandyslopessubjecttoearthquakeloadings,andshowedsubstantial

benefitsofanaloguerootreinforcement.

Inpreviousstudiesusingliveplants(e.g.Sonnenbergetal.,2010),modelscalingeffectshavenotbeenconsideredin

detail. Thismay have contributed to over-prediction of root reinforcement and relatively poor prediction of slope

response.Weareperformingstudiestoidentifycandidatespeciestobetterrepresentscaledrootmorphologiesand

mechanicalcharacteristicsforuse incentrifugemodelling.Threespecies(willow,gorseandgrass),correspondingto

distinctplantgroupswereselectedandcultivatedforapproximatelytwomonthsfollowingpreliminaryassessmentof

suitablespecies.Rootmorphologies,tensilestrengthsandYoung’smodulusofthesejuvenilerootsampleswerethen

measured and compared with results frommore mature field grown specimens. Results from these tests will be

discussedinrelationtotheuseofjuvenileplantrootsystemsandrootsystemanaloguesinscaledcentrifugetesting.

SBEE2016ABSTRACTS

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Reference

Liang,T.,Knappett,J.A.,Duckett,N.,2015.Modellingtheseismicperformanceofrootedslopesfromindividualroot–

soilinteractiontoglobalslopebehaviour.Géotechnique65(12),995–1009.

Sonnenberg,R.,Bransby,M.F.,Hallett,P.D.,et.al.2010.Centrifugemodellingofsoilslopesreinforcedwithvegetation.

Can.Geotech.J.47(12),1415–1430.

Acknowledgement

Funding:EPSRC(EP/M020355/1).TheJamesHuttonInstitutereceivesfundingfromtheScottishGovernment(Rural&

EnvironmentalServices&AnalyticalServicesDivision)

SBEE19–SensitivityanalysisoftheSOSlopemodel:discussionontheroleofrootreinforcementandslopestability.D.Cohen,M.Schwarz

DepartmentofGeologicalandAtmosphericSciences,IowaStateUniversity,Ames,IA50011,USA

Tree roots have longbeen recognized to increase slope stability by reinforcing the strengthof soils. Slope stability

modelsaddapparentcohesiontothesoiltosimulaterootstrength.Nomodelincludestheeffectsofrootdistribution

heterogeneity, strain-stress behavior of root reinforcement, or strength due to root compression. Recent field

observationsindicatethatshallowlandslidetriggeringmechanismsarecharacterizedbydifferentialdeformationthat

indicate localized loading of tension, compressive, and shear strength of the soil. These observations contradict

common assumptions used in present models. Here we present a newmodel for slope stability calculations that

specifically considers these effects. The model is a strain-step discrete element model that reproduces the self-

organizedredistributionofforcesonaslopeduringrainfall-triggeredshallowlandslide.Treerootsgoverntensileand

compressive force redistributionduring triggeringof shallow landslideanddetermine the stabilityof the slope, the

timing, location, and dimension of the failure mass. To fully understand the mechanisms of shallow landslide

triggering requires a complete re-evaluation of the traditional apparent-cohesion approach that cannot consider

realisticallytheeffectofrootreinforcementonslopestability.Moreoverresultsindicatethatassumptionsofconstant

elasticityandhomogeneouspropertiesasdoneintypicalFEMgeotechinalmodelcannotreproducethemechanisms

leading to the triggering of slope failure. The SOSlopemodel fills the gap of developping amechanisticmodel for

predictingshallowlandslidesizeacrosslandscapes,consideringtheeffectofrootreinforcementwithahighdegreeof

details(spatio-temporalheterogeneityofrootreinforcement).

SBEE2016ABSTRACTS

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SESSION3–VEGETATIONANDSLOPESTABILITYII

SBEE49–SoiltextureandrootarchitectureeffectsonconcentratedflowerosionratesW.Vannoppen,J.Poesen,S.DeBaets

KULeuven,DivisionofGeographyandTourism,Celestijnenlaan200E,B-3001Heverlee,Belgium

Plantrootsareveryeffectiveincontrollingconcentratedflowerosion.Severalstudiesquantifiedtheerosion-reducing

effectsofplantswithdifferentroottraits.Thisisusefulforpractitionerswhowanttoevaluatesuitableplantspecies

toimproveslopestability.Sofar,mostresearchontheerosion-reducingpotentialofplantrootsfocusedonsiltloam

soilswhereasnoor little researchexists for sand soils. These soilsare commonandarealsoveryprone to incisive

erosion processes resulting in the formation of e.g. large gullies. At present, no specific relationship between root

variablesandtheirerosion-reducingpotentialexiststoreliablyassesstheerosion-reducingpotentialofplantrootsin

sandsoils.Thereforethefirstobjectiveofthisstudywastoassesstheerosion-reducingpotentialofgrassandcarrot

roots in soils with a sand content of 94% through concentrated flow experiments. Our second objective was to

compare theerosion-reducingpotentialofplant roots insandandsilt loamsoils.Forsandsoils, theresults showa

strongerosion-reducingeffectforfibrousrootswhilethiseffectwas lesspronouncedfortaproots.Thisresults ina

negativerootdiametereffectshowingthatthickertaprootsarelesseffectiveinreducingconcentratedflowerosion

ratescomparedto thin tap rootsand fibrous roots.Newrelationshipswereestablishedbetweenthe rootvariables

rootdensity (RD) and root lengthdensity (RLD) and theerosion-reducingpotential expressedas a soil detachment

ratioof theroot-permeatedsoil samplecomparedtoabarereferencesample (SDR).Soil textureplaysasignificant

role inthisrelationshipasrevealedbycomparingresults forsandandsilt loamsoils.Thenatureof thissoil texture

effectisroot-architecturedependent.Fibrousrootsaremuchmoreeffectiveinsandsoilscomparedtosiltloamsoils

whilethiseffect isoppositefortaprootswhichare lesseffective insandsoils.The lattercanbeattributedtomore

pronouncedvortexerosionaroundthethicker taproots insandsoils.Theseresultscanbeusedbypractitioners to

assessthe likelyerosion-reducingeffectofplantspeciesbasedonrootcharacteristics (i.e. root (length)densityand

diameter)andsoiltexture.

SBEE48–TalVeg®:aninnovativeapproachofecosystemmanagementforenhancingmultipleecosystemservices,withafocusonsoilerosionandslopestabilityTaugourdeauO1,FortF2,FreschetGT3,FrominN3,HedriE1,LeBissonnaisY4,MaoZ5,Merino-MartínL5,PlassardC6,RoumetC3,StokesA5,BoukcimH1

Valorhiz,Bât6P.S.AgropolisII,196BlvddelaLironde,34980MontferriersurLez

Introduction

Vegetation has been widely used on geotechnical engineering structures (e.g., embankments) associated with

infrastructuresandindustrialsites(e.g.,terrestrialtransport,quarries,minesandurbanspaces),asaneffectivetool

against soil erosion and shallow landslides hazards. Besides such a protective role, sustainable vegetation

managementontheseengineeringstructuresisincreasinglydesiredforfavoringmultipleecosystemservices,suchas

enhancing aesthetic value, promoting public safety, biodiversity conservation and climate change mitigation via

carbon sequestration. In this context,Valorhiz (URL:http://valorhiz.com/fr) developedan innovative solution (TalVeg®)thatcomprisesaDecisionSupportSystem(DSS).ThisDSSallowsdesigningandoptimizingmulti-functionalecosystems

SBEE2016ABSTRACTS

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considering managers and customers’ requirements (considering e.g., maintenance costs, biodiversity and/or

ecosystem services enhancement). TheDSS acts at the bio-technosol scale and aids towards the selectionof plant

speciesandassociatedmicroorganisms.For thesepurposes,TalVeg® innovation iscomposedof three technological

components:

− Databasesofplant,soilandsymbioticmicro-organisms

− Mathematicalmodelsthatsimulateplantandwaterdynamicswithinsoilaccordingtoclimatescenari

− Computationofbiodiversityandecosystemfunctions

Methods

VALORHIZ started to implement, in 2015, several pilot sites in railways, highways, quarries and ski slope contexts.

Severalexperimentalmodalities(withcontrastedseedmixesandmicroorganisminocula)weresetuponthesesitesto

test the effect of TalVeg® components on vegetation success (rapid and perennial development of a dense plant

cover)andsoilfunctions(soilstructuralstability,soilshrinkageandwaterretentioncurves).

Results&Discussion

Thedynamicsofplantcommunities,soilfunctionandbiodiversityandtheirinteractions,willbemonitoredatallsites

forover3years.Thepreliminary results (after6months)willbepresentedwithanoverviewofhowdoingbest to

managenovelecosystemswithregardtosoilerosionmitigationandslopestabilitymaintenance.Potentialpathways

ofincorporatingmulti-functionalitytothedominantfunctionofnaturalhazardmitigationwillalsobediscussed.This

studyenablesustogainabetterunderstandingofsoil-vegetationinteractionsinacontextofecologicalengineering,

opennewperspectiveswith regard to themanagementof degradedecosystems, andenhancemultiple ecosystem

services.

SBEE46–Analyticalestimationofsoilerosion,depositionandbioturbationusingOSLtechniquesAndreaRománSánchez,TonyReimann,TomVanwalleghem,ArnaudJ.A.M.Temme,JuanV.Giráldez

DepartmentofAgronomy,UniversityofCordoba,Cordoba,Spain

Bioturbation,soilerosionanddepositionareimportantandsignificantprocessesthataffectthemechanismsandrate

of bedrockweathering or soil formation. The estimation of the relative fraction of bedrock grainswhich has been

mixedinthesoilandtransportedeitherverticallyorlaterallytodifferentdepthsgivesanindicationofthedegreeto

whichbedrockweathering is controlledby the latterprocesses.However,despite thegreateffortdedicated to the

analysis of these processes, little is known about the relationship between geomorphological changes and soil

formation,especiallyforlongtimescales.

Thisstudypresentsreconstructionofsoilprocessesbysinglegrainopticallystimulatedluminescencetechniques(OSL)

andananalyticalapproachtoestimatethesoilerosion,depositionandbioturbationmechanisms inseveralprofiles

sampledalongahillslope.

TheOSL analysesprovideadirectmeasurementof soil formingprocesses (e.g. bioturbation, colluviation) andwith

themamorepreciseformulationofsoilformationmodelsatlongertimescales.Single-grainOSLtechniqueshavebeen

applied to quartz and feldsparminerals whichwere extracted from different soil horizons from a hillslope catena

locatedinSierraMorena,Córdoba,inthesouthofSpain.ThesuitabilityofthreedifferentOSLsinglegrainapproaches,

SBEE2016ABSTRACTS

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quartzOSL,IRSL(infraredstimulatedluminescence)andpIRIR(post-IRSL)feldspar,wastestedonfoursamples.From

thisanalysisparameters fromsingle-grainOSLagedistributions (e.g.numberofzeroedgrains, scatterandshapeof

thedistribution)werededuced

tobeusedas indicators forbioturbationand/orsoil-relocation.Themostsuitableapproachwas theapplied to the

severalsamplesfromhillslopecatena.ThisstudyrevealsthepotentialofOSLsingle-graintechniquesinordertoshed

light on bioturbation and pedoturbation processes within soil formation and their interrelationship with

geomorphologicalprocesses.

SBEE9–ImportantPlantSpeciesSupportingSoilStabilityandLandSlideControlinDifferentPhysiographicRegionsofNepalT.P.BarakotiandB.P.Subedi

AsiaNetworkforSustainableAgricultureandBioresources

Itwas revealed thatTerai, Siwalik,MountainandHimalayanphysiographic regionsofNepalareendowedwith rich

biodiversity.Itcomprisesonly0.09%ofthegloballandbutpossesses2.7%oftheworld’sfloweringplants(morethan

6500 species). The altitudinal, topographical and climatic variations have favouredNepalmake ecologically diverse

countrywith 118 ecosystems and 35 forest types from tropical to alpine belt. As a result, a number of plants are

important for bio-engineering measure of soil conservation, erosion and landslide control; agroforestry systems;

hedgerowplanting,fencing,fodderproduction,covercropping,mulching;pole,timber,firewoodandotherhousehold

purposes.

The plant genetic diversity resource is the rich source of food, fodder, energy, construction, and other purposes.

Plantsarethecosteffectivesourceofsoilprotectionandstability.Theresourceincludestrees(>400species),shrubs

andherbs.About100foddertreespeciesinmiddlehillsandTeraiareusedbyfarmersandtechniciansinsoilstability

work.SomeincludeLeucaenasp.,Ficussp.,Bauhiniasp.,Grewiasp.,Litseasp.,Morusalba.Morecommonare:broom

grass,adozenofbamboospecies,Pennisetumsp.,Setariasp.,Brachiareasp.,Desmodiumsp.,Flemingiasp.,Chloris

gayana,andmanyspecieshavingmultipurposevalue,deepandspreadingroots,growthperformanceunderdifferent

soil conditions. Acacia sp., Albizia sp. Eucalyptus sp., Terminalia sp., Melia sp., Schima wallichii, Shorea robusta,

Dalbergiasissoo,Bassiabuttyracea,arecommonlyused in thesouthernpartof lowerelevationandTerai,whereas

Rhododendronsp.,Pinussp.,Castanopsissp.,Alnusnepalensis,Prunuscerasoides,aredeliberatelyusedinmountain

region.Theireffectivenessdependedontype,age,slope,terrace,banketc).

SBEE2016ABSTRACTS

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DAY2-TUESDAY12JULY

SESSION4-ECO-ENGINEERINGANDLANDRESTORATIONI

SBEE39–SustainabilityperformanceofecoengineringmeasuresS.B.MickovskiandC.Thomson

SchoolofEngineeringandBuiltEnvironment,GlasgowCaledonianUniversity,CowcaddensRoadG40BAGlasgow,Scotland,UnitedKingdom

Theassessmentofthesustainabilityeffectsofecoengineeringstrategiescanbechallengingasthetreatmentofthis

topichasbeenneglectedinthescientificliterature.Thechallengeslieinbalancingtheprojectdeliveryobjectiveswith

the sustainable design that will ensure appropriate and satisfactory environmental and financial performance and

deliver socialbenefits.Ecoengineeringhasacrucial role indefiningandachieving thesustainabilitycredentialsofa

project and, hence, better ecoengineering practices would help better in reducing the adverse impacts on the

environmentandsociety,butalsoonthe financialperformanceof theproject.However, toachievebetterpractice

andadvancetheknowledgeinthefield,thereisaneedtodevelopasuitablesetofassessmenttoolsapplicabletoall

areasofecoengineeringintermsofkeyperformanceindicators(KPIs).

The aim of this study is to develop an effective assessment system/ framework which satisfies requirements for

quantification relating toecotechnologicalaspectsbutalsocaptures, inanacceptablemanner, themoresubjective

dimensionsofsustainability.Theobjectiveofthestudyistodevelopasmall,setofcommonbenchmarks(KPIs)which

reflect the principles of sustainability andwhich are not contextual for an ecoengineering project togetherwith a

contextualKPIsubsetthroughstakeholderconsultation/engagement.

For this study, we have reviewed some of the current indicator systems used in construction and geotechnical

engineering and adopted a system thatwould closelymatch the ideas behind ecoengineering in termsof stability,

activeuseofvegetation,andlong-termsustainability.Throughareal-lifecasestudy,wedemonstratethebenefitsof

adoptionofsuchasystematanearlystageofaprojectbutalsothebenefitsstemmingfromdouble-looplearning.

The successful implementation of indicator system ultimately depends on the implementationwithin the relevant

industryand,assuch,thereisaneedofmorecasestudiesandhistoriestodemonstratetheusefulnessofthesystem

andtheeffectsofthesystemonthedecision–makingprocess.

SBEE17–WhatIsaReasonableAmountofSoilErosionWalterW.Chen,FuanTsai,andKai-JieYang

Dept.ofCivilEngineering,NationalTaipeiUniversityofTechnology,1,Sec.3,Chung-HsiaoE.Rd.,Taipei106,TaiwanROC

Soil erosiondue to typhoons and concentrated rainfall is amajorproblem for Taiwan’shilly terrains.Although the

problem is widely recognized in Taiwan, the estimates of the amount of soil erosion differ substantially. As an

example,manystudieshavebeenconductedontheShihmenreservoirwatershedinnorthernTaiwan.However,the

publishedresultsshowedthatthecalculatedamountofsoilerosionintheShihmenreservoirwatershedvariedfrom1

to3310tons/ha-year,whichwasamorethan3000timesdifferenceandwellabovethereasonablemarginoferror.

SBEE2016ABSTRACTS

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Notonlythat,thisamountofsoilerosionwasalsomuchhigherthanthereported12-121tons/ha-yearofsoilerosion

in theHimalayanMountains, famous for theirhigherodibility. Inorder tounderstand the reasonsbehind thehuge

discrepancy, this study reviewed the researches conducted in the Shihmen reservoirwatershed, and offered some

explanations.Then,anewandmorethoroughcomputationoftheamountofsoilerosionwasmadeusingthemost

up-to-datedataavailable to theauthors.Theresultwascomparedtothoseofpreviousstudies,andbelievedtobe

moreprecise.

SBEE12–Onthepowerofstemstointerceptdebrisflowinforestedfanarea:alaboratorymodelingF.Bettella,G.B.Bischetti,V.D’Agostino,T.Michelini

DepartmentTESAF,UniversitàdegliStudidiPadova,Vialedell'Università16,35020Legnaro,Padova,Italy

Debris flowsareoneof themost commongeomorphicprocesses in steepmountainousareas. The controlof their

propagation on the fan is fundamental because the valley bottom presents usually a larger exposition in terms of

goods,inhabitantsandinfrastructures.Theforestplaysaprotectivefunctions,reducingthetriggeringofdebrisflows,

hindering themotion and promoting the deposition (e.g.Miller e Burnett, 2008; Guthrie et al., 2010; Fidei et al.,

2015),butaquantitativeestimationoftheseeffectsisstilllacking.Theresearchinvestigatesontheforestcapacityto

reducedebris-flowrunoutaswellasthesizeofthedepositionalarea,providingalsopracticalrecommendationson

theforestmanagementforaprotectivefunction.LaboratoryexperimentswerecarriedoutattheDept.ofAgric.Eng.

(MilanoUniv.).Theexperimentalsetup(Figure1)iscomposedbyasmall-scalechannel(2.0mlong,0.15mwide,and

0.40mdeep),atankforthedebris-flowmixtureloadingandrelease,andarunoutareawithanadjustableslope.The

deposition plane presents threaded holes (10 cm grid spaced)where vertical elements aremounted tomimic the

stems. Three scenarios were modeled: no elements, high forest, and coppice. At the end of each tests, the

morphologicalfeaturesofthedepositweremeasured.

Figure1.Experimentalsetupused

The experiments confirms sediment concentration of the flow is a key factor in determining the geometry of the

deposits,influencingalsotheforestpowerinhinderingthedebris-flowmotion.Moreprecisely,highforestseemsto

notsignificantlyreducedebris-flowmotionatthehighestsedimentconcentrations,whileacertainreductioncanbe

achieved for the lowest concentrations. On the contrary, coppice seems to provide a notable contribution, which

increasesasthesolidconcentrationraises.Thankstotheirhigherdensity,coppicestocksseemstowarrantabetter

protectivefunctioncomparedtothehigh-forestrigidtrunks.

SBEE2016ABSTRACTS

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References

Fidej,G.,Mikoš,M.,Rugani,T.,Jež,J.,Kumelj,S.,andDiaci,J.(2015).Assessmentoftheprotectivefunctionofforests

againstdebrisflowsinagorgeoftheSlovenianAlps.Forest-BiogeosciencesandForestry,8(1),73-81.

Guthrie, R.H., Hockin, A., Colquhoun, L., Nagy, T. Evans, S.G., and Ayles, C. (2010). An examination of controls on

debrisflowmobility:EvidencefromcoastalBritishColumbia.Geomorphology,114(4),601-613.

Miller,D.J.,andBurnett,K.M.(2008).Aprobabilisticmodelofdebris-flowdeliverytostreamchannels,demonstrated

fortheCoastRangeofOregon,USA.Geomorphology,94(1-2),184-205.

SESSION5–FORESTECOSYSTEMSANDWILDFIREMANAGEMENT

Keynote-MarkAdamsSBEE1–BushfiresandlandscapemanagementinAustraliaMarkAdams

UniversityofSydney,Sydney,Australia

BushfiresinAustralia,andwildfireselsewhere,areincreasinginpublicprominence.Irrespectiveoftheircause(s),high

intensityfiresinnativevegetationcausemajorchangesinthestructure,chemistryandstabilityofsurfacesoils.These

changes contribute markedly to landscape patterns – in vegetation, in soil erosion, and in long-term ecosystem

sustainability.InthistalkIwilluserecentexamplestooutlinethecaseforincreasingeffortstomanagewildfirerisk

andintensityandmitigatelong-termcosts.

SBEE24–VegetationcoverandslopeinfluencessedimentparticlesizedistributioninnaturalrainfallconditionsonpostfirehillslopeplotsinChilgok,KoreaEwaneBasilEwaneandHeon-hoLee

DepartmentofForestResources,YeungnamUniversity,Korea

Sedimentswerecollected fromfourburnunseededplots, sixburnseededplots,and fiveunburnplotsona rainfall

event basis, and sorted for size distributions to evaluate the influence of vegetation cover and slope. Sediment

detachment and transport mechanisms and the particle size transport selectivity of the eroded sediment were

assessed based on the enrichment ratios (ER) and mean weighted diameter (MWD) methods. The most eroded

particlesizeclass inall treatmentplotswasthatof125-250μmandgenerally,erodedparticlesizesdidnot increase

withslope.Themedianerodedsedimentwascoarserthanthemedianunerodedsedimentforallrecordedeventsin

the burn unseeded plots, unlike in the burn seeded and control plots. HigherMWD of the eroded sediment was

relatedtohigherpercentbaresoilexposedandpoorsoilaggregatestability.Theenrichmentoffinerclay-siltparticle

sizes increased with varying I30 in the burn unseeded plots, and reflected increased sediment detachment and

transport selectivity,whilenogood relationshipwas found in theburnseededandunburnplotswithvarying I30.A

minimum I30of2.5mmh-1andamaximumof10.9mmh-1were foundtobethethresholdrainfall intensityvalues

necessaryforaggregatebreakdownandtransportoffinerparticlesintheburnunseededplotswhiletheresponsewas

weak in theburnseededandunburnplotsaftervarying I30.Theresultsshowedthathighervegetationcover in the

SBEE2016ABSTRACTS

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burnseededandunburnplotsreducederosiverainfallenergyby5.6and17.7folds,andrunoffenergyby6.3and21.3

folds, respectively, limiting aggregate breakdown and transport selectivity of finer particles compared to the burn

unseeded plots. The results suggest that postfire hillslopes undergoing effective vegetation recovery have the

potential to reduce the detachment and transport of finer particle sizes by both rainspash and rainflow erosion

processes to pre-fire levels within 7 years after burning. The results suggest important implications for postfire

hillslopevegetationrecoveryandlandmanagementpractices.

Keywords: Soil erosion, bare soil exposed, sediment detachment, aggregate stability, enrichment ratio, particle

transportselectivity.

SBEE16–NumericalassessmentoftheprotectiveeffectofforestsandbioengineeringtechniquesagainstrockfallF.Bourrier,D.Toe,I.Olmedo-Manich,D.Bertrand,F.Berger

Irstea,UREMGR,SaintMartind’Hères,France

Mountain forests providemany goods and services essential to human life and activities. In addition to thewood

resourcestheyrepresent,theyalsoconstituteareserveofbiodiversityandcontributetothelandscapeattractiveness

and the environmental quality. A significant proportion of mountain forests also protect human beings and

infrastructuresagainstnaturalhazardssuchasrockfall,snowavalanches,flashfloodsandsoilerosion.Anincreasing

numberofstudieshavedemonstratedthatforestscanbeanefficientandcosteffectiverockfallprotectionstructure,

especiallyforsmallmassevents(<5m3).

Inthefieldofrockfallhazardassessment,theintegrationofforesteffectonblockspropagationandtheassessmentof

forest protection function are increasingly being studied. The integration of forest effects in rockfall propagation

models ischallengingbecauseof thecomplexityof themechanicalprocesses involved intothe interactionbetween

theblocksandthetrees.Althoughtheexistingmodellingapproachespresentefficientcomputationaltimesandglobal

accountingofforesteffects,theydonotallowintegratingallthephysicalprocessesoccurringduringtheinteraction

between theblocksand the treeandaccounting for the respective contributionsof thedifferent tree components

(stem,rootsystemandcrown).

Thisresearchworkaimsatdevelopingmechanicalmodelsoftheimpactofblocksontreesandbioengineeringrockfall

protectionstructuresmadeoffelledtrees.Themodels,basedontheDiscreteElementMethod(DEM-opensource

code Yade-DEM), were developed to account for the relative contributions of the different tree components. The

interaction between the block and the tree stem ismodelled as one of a rigid spherical body - the block -with a

deformable beam - the stem. The contact between the twobodies is accounted for by applying forces to the two

bodiesdependingontheiroverlapandrelativevelocities.Thetreestemisrepresentedbyaflexibleconesubjectedto

normal, shear,bending,and twist loadings. In thecaseof impactona tree, thecrown ismodelledasanadditional

massdistributeduniformlyontheupperpartofthestem.Thecontributionoftheroot-systemisintegratedbymeans

ofrotationalnon-linearspringactingatthebottomofthetree.

Twonumericalmodelsweredevelopedtosimulateimpactsofblocksonsingletreesandcoppicestools.Thesemodels

werecalibratedusinglaboratoryimpacttests.Numericalsimulationsofblockimpactontreesallowedidentifyingthe

treeandblockparametersmanagingtheblocktrajectorychanges(treediameter, impactpoint location,andimpact

velocity,inparticular).Theintegrationofthesemodelsintoblockpropagationmodelsprovidedquantitativeresultson

SBEE2016ABSTRACTS

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forestprotectioneffect in termsofdecreaseof theblockpropagationdistanceandenergy. The comparisonof the

results to the approach classically used to assess forest protection function provides information on the potential

improvementsoftheclassicalapproaches.

ADEMmodelofthe impactofablockonastemwasalsousedtoexplorethedynamicresponseofbioengineering

structures made of felled trees to block impact for different realistic scenarii through an extensive numerical

campaign.Theresultsshowedthat,forblockdiameterslargerthan1.5timethestemone,theoccurrenceofasecond

contactduringtheblock/structureinteraction,doesnotfavorblockenergyreductionwhileitisoftenassociatedwith

stem ruptures. On the contrary, structuresmade of larger diameter trees are globally more advantageous (single

contactassociatedwithasignificantblockenergy lossandalmostnilstructuredamages).However,extremely large

stems(blockdiameterssmallerthan0.8timethestemone)arenotrecommendedasthemomentumtransferfrom

theblocktothestemisnotsignificant.

SBEE47–Combiningbio-andeco-engineeringtechniquesinN.GreeceIoannisSPANOS

HelllenicAgriculturalOrganizationDemeter,ForestResearchInstitute,57006Vassilika,Thessaloniki

Greece isaMediterraneancountry that suffered fromrepeatedwildfires forpine forests inparticularly,due to the

climate conditions prevailing in summer. In Greece, rehabilitation measures, salvage logging and eco-engineering

works are someof themost commonmanagement activities applied inburnedpine forests.Groundbio- andeco-

engineering techniques were combined depending on the particular problem and type of vegetation slope. Three

groupsofrestorationactivities(erosioncontrolworks,waterflowcontrolworksandvegetationrecoverywereapplied

byartificial reforestationsandnatural regeneration in a PinushalepensisMill. forest inN.Greece (Halkidiki region,

SithoniaandKassandrapeninsula).Themainerosionandwaterflowcontrolworksthatappliedimmediatelyafterthe

wildfireswerematchsticks, logerosionbarriers, clear felling,ploughing, furrowing, small timbereddamsand check

dams. In this research, were assessed the effects of postfire rehabilitation methods on groundcover, vegetation

structureandgrowthaswell as soilpropertiesand sedimentyield.The resultswere indicated significanteffectsof

postfireactivitiesonmeasuredecosystemvariables.Thevegetationrecoverytookplaceatarelativelyhighrate,so

until the first autumn rains, the soil of the burnt area was partly covered by vegetation, reducing the risk of soil

erosion.Naturalvegetationrecoveryandthedeadresidualscreateasurfacestratumabovesoil,andthusprotectthe

soilsfromfloodsanderosion.

Keywords:wildfires,soilerosion,Pinushalepensis,eco-engineeringworks,naturalregeneration,

SBEE2016ABSTRACTS

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SESSION6–ROOT-SOILINTERACTIONSI

Keynote-IanRutherfurdSBEE3–Assumedresistance:theroleofvegetationrootsontheresistanceofriverbankstofluvialscourIanRutherfurd

UniversityofMelbourne,Melbourne,Australia

Riverbankserodebymassfailureandbyfluvialscour.Theroleoftreerootsinstrengtheningriverbanksagainstmass

failureiswellestablished.Whilstmanagersalmostuniversallyassumethatrootswilldramaticallyreduceerosionby

hydraulic forces (fluvial scour) this is not nearly as well studied. This paper reviews how tree roots increase the

criticalshearstressofriverbanks,andmoreimportantly,howtherootsreducetheerosionrateofthosebanks.The

keyliteratureonthetopiccomesfromagriculturalerosion,butalsofromthemorerecentexperimentswithhydraulic

jets.Weconsiderscalingrelationshipsandpotentiallimitstotheeffectofrootsonfluvialscour,aswellashowscour

resistancedeclinesovertimeoncetreeshavedied.

SBEE29–Roots,ShootsandRiverbankStability:CorrelationsoftensilestrengthA.Helfensdorfer,T.Hubble

GeocoastalResearchGroup,UniversityofSydney,Sydney,NSW,Australia

Riparianvegetationcanprovide increasedstability toa riverbank through theadditionofapparent cohesion in the

soil-root matrix by root-reinforcement. The quantification of root-reinforcement is commonly determined by

conducting tensile strength tests on roots at a species-specific level. However, excavation of root systems is

operationallydifficultandpotentiallydangerous,andanestimateoftherootstrengthbasedonabove-groundplant

components is desirable. The relationship or correlation between the tensile strength of below-ground roots and

above-ground shootswas assessedusing two commonEasternAustralian riparian trees,C. cunninghamiana subsp.

cunninghamiana (River She-oak) andEucalyptus elataDehnh. (River Peppermint). Statistical analyses of laboratory

tensiletestsshowthatshootspresentanappropriatedirectrepresentationofthetensilestrengthofaspecies’roots

(C. cunninghamiana: F = 3.874, p = 0.050, ANCOVA; E. elata: F = 1.677, p = 0.197, ANCOVA). If these results are

representative of common behaviour then it should be possible to simplify the necessary tensile strength testing

regime.Thiswouldassistinimprovingtheeffectivenessofriparianrehabilitationprojects,andmorebroadlyforusein

hillslope and landslide stabilisation schemes by eliminating the need for time-consuming root excavations to

determineprobableroottensilestrengths.

SBEE2016ABSTRACTS

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SBEE30–RootmorphologyandbiomechanicalcharacteristicsofhighaltitudealpineplantspeciesandtheirpotentialapplicationsinsoilstabilizationC.Hudek,C.J.Sturrock,B.S.Atkinson,S.Stanchi,M.Freppaz1UniversityofTorino,DISAFA,LargoPaoloBraccini,2,10095Grugliasco(TO),Italy

Root system contribution to soil stabilization is a well known phenomenon. Glacial forefields are young, poorly

developed soils with highly unstable soil conditions. Identifying the functional traits and root morphology of the

different successional stages of pioneer vegetation that establish on these forefields can lead us to important

informationregardingthepracticalapplicationofplantsinthelandrestorationofhighaltitudemountainsites.

This studyaims togather informationontherootmorphologyand itsbiomechanicalcharacteristicsof the10most

dominantpioneerplantspeciesoftheforefieldofLysglacier(2100-2400ma.s.l.,NWItalianAlps).

Anon-destructiverootphenotypingtechniquewasusedtovisualiseandcomparetherootarchitectureofthestudied

species.SamplesweredirectlycoredfromtheforefieldandlateronscannedwithanX-rayMicroCTinthelaboratory.

Dataonroot traitssuchas root length, rootcount,averagerootdiameter,numberof roots in relationtodiameter

classesandrootdensityweredeterminedthencomparedbetweenspecies.Rootswerealsotestedfor their tensile

resistanceandtheresultswereusedtoquantifytheadditionalcohesiontothesoilprovidedbytheroots.

The X-ray CT technology allowedus to visualise the 3D root architecture of the species, intact in their natural soil

system. It provided a visual representation of root – soil contact and data on the exact position, orientation and

elongationoftherootsystem.Rootarchitectureshowedgreatvariabilityamongthespecies.Considerabledifferences

wererecordedinbothrootlengthandrootcount.Rootdistributionwithindiameterclassesvariedbetweenspecies

andgrowthforms.However,themajorityofrootsconsistedofrootssmallerthan1mmindiameterforallspecies.All

tensile strength results followed the power low relationship as in all cases root tensile strength decreased with

increasing rootdiameter. Thehighest tensile strengthwas recorded for graminoids suchasLuzula spicata andPoa

laxaandthelowestforEpilobiumfleischeri.

The differences in root properties among the studied species highlight the diverse adaptive and survival strategies

plants employ to conquer and thrive in the harsh and unstable soil conditions of a glacier forefield. The data

determinedanddiscoveredinthisstudyaimstoprovideasignificantcontributiontoadatabasethatallowthosewho

areworking in landrestorationandpreservationofhighaltitudemountainsitestoemploynativespecies inamore

efficient,effectiveandinformedmanner.

SBEE35–Predictingrootmechanicalproperties:fibrousvswoody,whatcontrolstheunderlyingstrength-diameterrelationshipinroots?KWLoades,JBrown,JPLynchandAGBengough

TheJamesHuttonInstitute,Invergowrie,Dundee,UK.

Keytopredictingtherelativecontributionsofplantrootstosoilstabilisationandreinforcementisunderstandingboth

stress transfer from roots to soil, and root resistance to failure under tension and bending. Models of root

reinforcementgenerallyutilisestrength-diameterpower-lawrelationships,withthinnerrootsgenerallybeingstronger

thanthickroots. Multiple factors influencerootbiomechanicalpropertiesmakingsuchrelationshipsmorecomplex

thanisapparentinmuchoftheexistingliterature.

SBEE2016ABSTRACTS

24

Inwoodyrootsmanyfactorsmayinfluencetherelationshipbetweenrootstrengthanddiameter.Controllingfactors

may include tissue density, root age, and root turnover – all of which may have some diameter dependency.

Experimentstostudythesepropertiesinthreecontrastingwoodyspecieswillbedescribed,togetherwithastudyof

theeffectsofdecompositiononrootmechanicalproperties.

Strengthdiameterrelationshipshavealsobeenfoundformanyfibrousrootsystems,andthispaperconsiderswhich

roottissuemostinfluencesrootstrength.Laserablationandimageanalysiswasperformedonmaizerootsfollowing

mechanicaltestingtoinvestigatemechanicalpropertiesinrelationtointernalrootstructures.Stelediameterwasthe

strongest predictor of root tensile strength and a total of seven further internalmeasureswere found to improve

predictionsofbendingresistance.

SBEE11–Arewoodanatomicalpropertiesandvariationsrelatedtotheroottensilestrengthoftrees?Gaininginsightsfromgreyalderandmountainmaplegrownonacoarsegrainedeco-engineeredslopeintheSwissAlpsA.Bast,D.Kink,H.Gärtner

SwissFederalInstituteforForest,SnowandLandscapeResearch(WSL),LandscapeDynamics/Dendroecology,Zürcherstrasse,Birmensdorf,Switzerland

Rootsystemssupportplantgrowthaswellassoiland/orslopestability,andmodifysubsurfaceparameters likesoil

aggregation,soil(bulk)densityorsoilmoisture.Saturatedsoil,as inducedbyconstantortorrentialrainfalls,exertsa

downward pressure on the plants, and in particular on their root systems. As long as the root system supports

anchorage the concerning, adjacent slope area remains stable and prevents superficial mass movements or soil

erosion. Here, the tensile strength of the roots is a critical measure, since it is rather more likely that a single

supportingroottear,thantheentirerootsystemispulledoutofthesoilcompletely.Asaconsequence,roottensile

strengthisanimportantpropertytocharacterizethepotentialoftreesandshrubsgoverningsoil/slopestabilization

andfixation.

Sincetreerootsshowahighvariability intheiranatomicalstructureweassumethatthesestructuralchangesaffect

thetensilestrengthofeverysingleroot.Toconfirmthisassumption,weexcavatedandanalysedtherootsystemsof

threealder(Alnusincana(L.)MOENCH)andfourmaple(AcerpseudoplatanusL.)trees.Theseventreeswereplanted

in1997withinaneco-engineeringmeasureintheArieschbachcatchment,easternSwissAlps.Thesite(1000ma.s.l.,

E-exposed,inclinationof~40°)ischaracterizedbyacoarse-grainedsoil(~60–65%gravel,~20–25%sand)andsub-

oceanicclimate(meanannualairtemperature:4.64°C,meanannualprecipitation:1170mm).

Therootsystemsweremappedandsplitinto~500sampleshavingalengthofca.10cm.Attheheadandbottomof

each specimen,micro sectionswere prepared forwood anatomical analyses,which included the determination of

rootage,numberandsizeofvessels,fibresizeandcellwallthickness.Tensilestrengthtestswerecarriedoutusinga

Zwick/Roell 100 universal testing machine. Additional to these properties root diameter and root moisture were

determined.

Inourcontributionwepresenttheinitialresults,whichshowedforbothgroupsthat(i)tensilestrengthincreaseswith

decreasing diameter, (ii) number of vessels correlates positively with the tensile strength, (iii) vessel lumen area

correlatesnegativelywithtensilestrength,and(iv)agecorrelatednegativelyuntilacertainrootageisreached.

SBEE2016ABSTRACTS

25

SBEE18–EvaluationoftheeffectsofrootelasticityonsoilreinforcementfordifferentAlpineandPre-AlpinetreespeciesA.Cislaghi,G.B.Bischetti

Dep.Agric.Env.Sci.,UniversitàdegliStudidiMilano,ViaCeloria2,20133Milano,Italy

Root systems are recognized to play a fundamental role in increasing the soil shear resistance and stabilizing

hillslopes. Therefore, quantifying the reinforcement of soils by root is an essential challenge to evaluate the

contributionofvegetationagainstthetriggeringofshallowlandslides.

Duringthelastdecades,differentsoil-rootmodelshavebeendevelopedtoevaluatethereinforcement.Mostofthem

quantify themobilized tensile strength under the assumption that the root is a linear elastic fiber that breaks at

ultimatestress.ThisisthecaseofthepioneeringmethodofWuetal.(1979),andthemorerecentFiberBundleModel

(Pollen and Simon, 2005). Suchmodels neglect the displacement effect on themobilized tensile strength,which is

insteadconsideredby thecompleteequationsproposedbyWaldron (1977)andmore recentlyby theRootBundle

Model(Schwarzetal.,2013)thatincorporatesastrain-steploadingapproach.Thesemodels

Modelsbasedonultimate tensile stress valuesare simplerandcanbeapplied rathereasilybecause themaximum

tensilestrengthatruptureismainlyrelatedtotherootdiameterbyasimplerelationship(generallyapowerlaw)and

itsvalueshavebeenextensivelystudiedformanyspecies.Onthecontrary,modelsaccountingfordisplacementtake

into account both the geometry (diameter, length and tortuosity) and mechanical properties of roots (maximum

tensileforceandYoung’smodulus),buttheiradoptionishinderedbyasubstantiallackofavailabledata,especiallyfor

forestspecies,whichcalculationismorecomplexandcontroversial.Young’smodulus,orelasticitymodulus,infact,is

simplydefinedastheproportionalitybetweenstressandstrainandrepresentsthelinearelasticportionofthestrain-

stress curve, but some interpretations are necessary to obtainmeaningful results. Commandeur and Pyles (1991)

identifiedtwodifferentbehavioursduringthetensiletest:aninitialstraight-lineportionduetotheroottortuosityand

a following segmentdue to thewood fibresof the rootmaterial.Otherauthorsused the secantYoung’smodulus,

namely the ratio of root strength over strain at failure reduced proportionately by application of a reduction

coefficientduetothetortuosity(thatrangesfrom0.3and0.5).

The objective of the study is to estimate the Young’s modulus adopting different approaches and to evaluate its

influenceonrootreinforcement.Basingonalargedatabaseoftensiletestcurvefordifferenttreespeciestypicalof

Alpine and Pre-Alpine territory (Sweet chestnut, Beech, European larch, Spruce and Black locust), we aim to

contributeto identifydifferentorsimilarbehaviourofmechanicalproperties inthesameenvironmentalconditions.

Theresultsarerelevanttoincludedisplacementwithintheroot-soilmodelsinordertoimprovetheidentificationof

themoresusceptibilityareas,thelandplanningandtheforestmanagement.

References

Commandeur,P.R.,Pyles,M.R.,1991.ModulusofelasticityandtensilestrengthofDouglas-firroots.Can.J.For.Res.

21,48–52.

Pollen,N.,Simon,A.,2005.Estimatingthemechanicaleffectsofriparianvegetationonstreambankstabilityusinga

fiberbundlemodel.WaterResour.Res.41,n/a–n/a.doi:10.1029/2004WR003801

Schwarz, M., Giadrossich, F., Cohen, D., 2013. Modeling root reinforcement using a root-failure Weibull survival

function.Hydrol.EarthSyst.Sci.17,4367–4377.doi:10.5194/hess-17-4367-2013

SBEE2016ABSTRACTS

26

Waldron,L.J.,1977.Theshearresistanceofroot-permeatedhomogeneousandstratifiedsoil.SoilSci.Soc.Am.J.41,

843–849.

Wu,T.H.,McKinnell III,W.P.,Swanston,D.N.,1979.Strengthof treerootsand landslidesonPrinceofWales Island,

Alaska.Can.Geotech.J.16,19–33.

SBEE7–EffectsofAcaciamangiumandMacarangatanariusrootsonsoilshearstrengthN.Avani,H.Lateh

PhDStudent,LandslideStudies,UniversitiSainsMalaysia,Penang,Malaysia.

Inordertoevaluatetheeffectsofrootsonsoilshearstrength,directsheartestwascarriedoutonplainsoilsample

androotpermeatedsoilofAcaciamangiumandMacarangatanariusinPeninsularMalaysia.Theresultsshowedthat

rootsincreasethesoilshearstrengthbyincreasingsoilcohesionratherthansoilinternalfrictionangle.Regardstosoil

shearstrength,M.tanariusroots(VHrootsystempattern)canincreasetheshearstrengthofsoilabout11%to44%

andA.mangiumroots(Hrootsystempattern)canincreaseabout7%to26%.TheresultsindicatedthatA.mangium

rootsarenotabletoresistshearstresswithincreasingnormalstress.

SBEE31–LandslideHazardAssessmentConsideringSpatialUncertaintyofTreeRootReinforcementandSoilThicknessDongyeobKim,ChangwooLee,ChoongshikWoo,SangjunIm,KunWooChun

NationalInstituteofForestScience,57Hoegi-ro,Dongdaemun-gu,Seoul,02455,RepublicofKorea

This study was aimed to suggest the methodology which could generate relatively reliable results after utilizing

existing database on a physically-based landslide modelling. Especially, the study introduced a scenario-based

approach to consider two representative factors effectively, i.e. root reinforcement and soil thickness with high

uncertainty and sensitivity. It could be summarized as follows; 1) Some different scenarios on the value of root

reinforcementwere prepared by conducting reference review, 2) A series of simulations under the assumption of

same value of soil thickness on the entire study areaswere carried out repeatedly by some different level of soil

thickness in each root reinforcement scenario, and 3) Simulated resultswith FS<1 by levels of soil thicknesswere

overlaidineachrootreinforcementscenariomap.

Thestudysitewas168km2ofChungyanginBonghwa-gun,Gyeongsangbuk-do,RepublicofKoreawithvastdamages

causedbyanumberofshallowlandslideslastJuly,in2008.TRIGRS2,developedbyUSGSlandslidehazardprogram,

was employed after partly revised to consider tree surcharge and root reinforcement. Design rainfall amountwas

derivedwithrainfalldurationof24hoursandreturnperiodof5yearsstatisticallyinthestudysiteandthedetermined

rainfallamountwastemporarilyallocatedbythecharacteristicsofstormrainfalleventsinKorea.Topographicaldata

waspreparedas30m-DigitalElevationModel(DEM)generatedbyNationalGeographicInformationInstituteofKorea

and inputdata for soil strengthandhydraulicpropertieswereextracted fromexistingnationaldigital soil property

map.Treepropertiesweredeterminedafterusinginformationofnationaldigitalvegetationmap.

Simulated results showed that 55% to 66% of the entire study site was prone to landslide by root reinforcement

scenarios. It was hoped that comparing the simulated results with landslide inventory in 2008 could ensure the

SBEE2016ABSTRACTS

27

current status of root reinforcement and soil thickness at specific places. Alongwith this, three types of landslide

mapsderivedfromeachdifferentscenarioshallbevaluableresourcesforafforestationplanninginthefuture.Atthe

conclusion, we think that the methodology for input data preparation in this study would be cost-effective for

assessinglandslidehazard.

SBEE28–Howup-ordownslopeanchoringaffectsrootreinforcementF.Giadrossich,M.Schwarz,D.Cohen,M.Niedda

DepartmentofAgriculture,UniversityofSassari,viaEnricodeNicola1,07100Sassari,Italy

Root reinforcement is important for slope stability. In addition to the important contribution of roots to shear

strengthalongtheslipsurface, rootnetworksarealsorecognizedto impartstabilizationthrough lateral (parallel to

slope)redistributionof forcesundertension.Themostcommonmethodtomeasure lateralrootreinforcement isa

pullout testwhereone rootor abundleof root ispulledoutof the soilmatrix. This condition represents the case

whererootswithinthemassofalandslideslipoutfromtheupperstablepartoftheslope.Thereisalso,however,the

situationwhererootsanchoredintheupperstablepartoftheslopeslipoutfromtheslidingmass.Inthelatteritis

difficult toquantifyrootreinforcementandnostudyhasdiscussedthismechanism.Wecarriedoutanewseriesof

laboratoryand fieldexperimentsusingDouglas fir (Pseudotsugamenziesii) roots toquantifyhowup-ordownslope

anchoringaffectsrootreinforcement.Inaddition,wecarriedoutnewfieldpullouttestsoncoarseroots(largerthat2

mm in diameter, up to 47 mm). Then, considering the state-of-the-art of root reinforcement modeling (the Root

BundleModel),weintegratedresultsfromourmeasurementsintothemodeltoverifythemagnitudeofthiseffecton

overallrootreinforcementatthestandscale.

Resultsindicatethattheratiobetweenpulloutforceandforcetransferredtotherootduringsoilsliprangesbetween

0.5and1.Thisindicatesthatmeasuredpulloutforcealwaysoverestimatethecontributionoflateralslippingoutroots

insituationswherethesoilslidefromanchoredroots.Thisisgeneralthecaseforrootwithdiameterupto3-4mm.

Root-sizedistributionisalsoakeyfactorinfluencingrootreinforcementattheforest-standscale.Asmostcoarseroots

breakalongtensioncrackswhilefinerootsslipout,theeffectdiscussedinthisstudyonrootreinforcementmodeling

isnegligiblewhencoarse-rootdiameterclassesarerepresented.Ourresultscontributetoimprovethequantification

ofrootreinforcementmechanismsandareimplementedinthe„RootBundleModel“ approachassumingamodified

functionfittingtherootforce-diametermeasurements.

SBEE2016ABSTRACTS

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DAY3-WEDNESDAY13JULY

SESSION7-ROOT-SOILINTERACTIONSII

SBEE38–Insitumeasurementofroot-reinforcementusingthecorkscrewextractionmethodG.J.Meijer,A.G.Bengough,J.A.Knappett,K.W.Loades,B.C.Nicoll

SchoolofScienceandEngineering,UniversityofDundee,Dundee,UK

Mechanical root-reinforcementcanbeacost-effectiveandecologically friendly

waytostabilizeslopes.However,thecontributionofrootsisdifficulttomeasure

in-situ.

Meijer et al. (2016) developed new in-situ root-reinforcement measurement

devices.Thesedevicesaresmall,easytotransport,quickandsimpletouse.One

ofthesedevicesisbasedonacorkscrew(Fig.1).Rotationalinstallationensures

that roots and soil are disturbed minimally, which is a major advantage over

moretraditionalstrengthquantificationmethodslikeshearvanetesting.Vertical

extractionmobilizestherootedsoilshearstrengthalongtheinterfaceofthesoil

cylinder caught within the helix. The method gives very similar peak shear

strengthvaluescomparedwiththeconventionalfieldshearvaneinnon-rooted

soil(Meijeretal.2015).

Herewedescribetests intwodifferentrootedsoils,upto500mmdepth.One

site isamatureSitkaspruce (Piceasitchensis)plantation,andthesecondsite isanagricultural fieldplantedwith4

yearoldblackcurrant shrubs (Ribesnigrum).The resultsare compared to theWu/Waldronmodeland fibrebundle

models(FBM)withvariousrulesonloadsharing.Estimatesofthesoilstressandgravelcontentweremadeforeach

test.

The results show positive correlations between root quantity

and shear strength in theheavily rooted top layer of the soil.

Below 250 mm however, local variations in soil strength and

gravel content had a stronger influence on the peak strength

than roots, making the effect of the roots impossible to

accurately quantify. Interestingly, negative correlations were

found between root quantity and soil stress – possibly

indicating that rootsmight preferentially growwhere the soil

hasowerstrength.

Root reinforcement estimates in surface layer are lower than

model predictions. The most likely cause is that the residual

strength of the fallow soil is significantly lower than the peak

strength.Themeasuredpeakstrengthfortherootedsoilwillbe

lower than the sum of the fallow soil peak strength and root

peakstrengthbecauserootsmobilizetheirmaximumstrengthatrelativelylargedisplacements.

Fig2:Experimentalresultsandmodelpredictions

Fig1:Corkscrew

SBEE2016ABSTRACTS

29

Insummary, thecorkscrewdevice isapotentiallyusefulandeasy tool forsite reconnaissance.Ourstudy indicates

thattwo-wayinteractionsbetweensoilstrengthandrootreinforcementmayoccur,andthatitisimportanttostudy

rootandsoilmobilizationmechanismsinsteadofmerelyfocussingonpeakstrength.

References

Meijer, G.J., Bengough, A.G., Knappett, J.A., Loades, K.W. & Nicoll, B.C. (2015). Comparison of new in situ root-

reinforcement measuring devices to existing techniques. In Proceedings of the 16th European conference on soil

mechanicsandgeotechnicalengineering(XVIECSMGE),Edinburgh(ed.M.Winter),vol.4,pp.1621–1626.London,UK:

ICEPublishing

Meijer,G.J.,Bengough,A.G.,Knappett,J.A.,Loades,K.W.&Nicoll,B.C.(2016).Newinsitutechniquesformeasuring

thepropertiesofroot-reinforcedsoil–laboratoryevaluation.Géotechnique66(1):27-40

SBEE43–SoiltextureinfluencesonrootdevelopmentinpoplarinNewZealandI.McIvor,G.Douglas,M.Marden,C.Phillips

LandcareResearch,NewZealand

Thereislittleinformationonhowsoiltextureinfluencesthedevelopmentofcoarsestructuralroots(i.e.those>1mm)

insoilconservationtreesestablishedfrompoles(unrootedcuttings).Thisprojectaimedtodeterminetheinfluenceof

soil texture on the growth attributes of Populus × euramericana, a hybrid poplar, commonly used to provide soil

reinforcement and protection against shallow landslides on pastoral hill country in New Zealand. Trial plots were

establishedon3slopingpastoralsites(Otoi,Paihiatua,Bideford)ondifferentgeologiesandsoiltexturesandarange

of above- and below-ground attributes assessed annually. Dead trees were replaced in the year following

establishment. Trees from the original plot of 25 trees were excavated at sites Otoi, Pahiatua and Bideford

respectivelyafter1and2years,withrootdistributionlaterallyandverticallybeingdeterminedandroot lengthand

massrecordedforroots>1mmdiameter.Totalrootlength(roots>1mm)rangedfrom3to19mafteroneyear,and

from12to87maftertwoyears.Totalrootmassrangedfrom8to58gafteroneyear,andfrom28to699gaftertwo

years.Rootdevelopmentwasgreatestinallophanicsoil,withrootdevelopmentinclayloamslightlyinadvanceofthat

insandyloam.Thispaperpresentsresultsofthefirst2yearssincecuttingswereplanted.

SBEE50–Effectsofrootcharacteristicsanddilatancyontheshearstrengthofroot-permeatedsoilsAnilYildiz,FrankGraf,ChristianRickli,SarahM.Springman

WSLInstituteforSnowandAvalancheResearchSLF,DavosDorf,Switzerland

Theeffectsofvegetationonthehydrologicalandmechanicalaspectsofslopeswithrespecttotriggeringmechanisms

of shallow landslides are well recognized and have been investigated extensively. However, there is still a lack of

understandingontheunderlyingprocessesthatcontributetotriggeringsuperficialsoilfailureinroot-permeatedsoil.

Thus,quantificationofthevegetationeffects,inparticularrootreinforcement,ontheshearstrengthofsoiliscrucial

tobeabletoevaluatethecontributionofrootreinforcementtoslopestability.Rootsystems,asthemainmechanical

agent of vegetation contributing to the stability of slopes, have been widely investigated and studied, through

SBEE2016ABSTRACTS

30

differentapproaches,includinglaboratoryorin-situsheartestsofroot-permeatedsoil,andanalyticalmodelsofsoil-

rootinteraction.Directsheartesting,amongotherapproaches,servesasacommonlyemployedmethodtoevaluate

thecontributionofrootstotheshearstrengthofsoil.Inordertostudytheshearingbehaviourofroot-permeatedsoil,

a newly developed Inclinable Large-scale Direct Shear Apparatus (ILDSA) was used. A total number of 6 planted

specimenswasprepared in shearboxeswithdimensionsof500x500x400mmwithmoraine (SP-SM) froma recent

landslide area in Central Switzerland, and planted with Alnus incana, Trifolium pratense, Poa pratensis, Salix

appendiculata,Achilleamillefolium,Anthyllis vulneraria, representingdifferent root characteristics. Theboxeswere

maintained at an angle of 30o inclined from horizontal axis in a climate-controlled chamber for 12months. Direct

sheartestswereconductedonspecimensataconstantrateofsheardisplacementof1mm/minuptoamaximum

sheardisplacementof190mm,andunderthreedifferentappliednormalstresses:6,11and16kPa.Artificialrainfall

was applied at a constant intensity (100mm/h) prior to shearing. Tensiometers were installed close to the shear

surfaceandmonitoredcontinuouslytoobtainthematricsuctionduringthesaturationprocess.Suctionswerereduced

ascloseto0kPaaspossible,inordertosimulatethelossofstrengthafteraheavyperiodofrainfall.Subsequentto

shearing,thespecimensweredugouttounearththebelowgroundbiomass.Therootswerewashed,andseparated

into four groups:woody roots in top (TW) and bottomboxes (BW), and non-woody roots in top (TN) and bottom

boxes (BN).Therootswerescannedwitha flat-bedscannerandthetotal length,aswellas theroot lengthdensity

(RLD)wereobtainedusingthesoftwareWinRhizo®,andtheirdryweightwasdetermined.Itwasestablishedthatthe

totallengthofthenon-woodyrootsisoneorderofmagnitudehigherthanthatofthewoodyroots.Thedryweightof

thewoodyrootsissignificantlycorrelated(p<0.05)withtheirRLD,howeverthereisnocorrelationbetweenthedry

weightof thenon-woodyrootsandtheirRLD.Thiscanbeexplainedbythecharacteristicsof thenon-woodyroots,

whicharehighlyentangledand fine,while thewoodyplants tendtoproducethicker rootswith lessentanglement.

Significantcorrelations,intermsofthedryweight,betweenthewoodyrootsandrootsinthebottombox,aswellas,

the non-woody roots and roots in the topbox illustrate also the different characteristics of the twodifferent root

types. No relationships were found between the stress ratio and either woody, non-woody or total root length

densities.Howevermultiple linear regressionanalyses showeda significant relationshipbetween thestress ratioof

thespecimenswiththetotaldryweightofrootsandmaximumdilatancyangle.Itcanbeconcludedthat,althoughthe

root reinforcement is, mostly, correlated with the amount of roots in the specimen, it is not the only controlling

factor. In particular, in presence of an excess amount of fine to very fine, highly entangled, and shallow-rooting

herbaceousspecies,dilatancyisalsoanimportantmechanismandacontributingfactortotheshearingbehaviourof

theroot-permeatedspecimen.

SBEE2016ABSTRACTS

31

SBEE21–SoilaggregatestabilityonultramaficsubstrateinNewCaledonia:untanglingtheeffectofsesquioxides,soilorganiccarbon,roottraitsandectomycorrhizainfiveplantcommunitiesJ.Demenois,F.Carriconde,F.Rey,A.Stokes

AgroParisTech,INRA(UMRAMAP)–Irstea(UREMGR)–IAC(Axe2),CentreIRDdeNouméa,BP18239,98800Nouméa,NewCaledonia.

NewCaledoniaisanarchipelagolocatedintheSouthWestPacific.Withameanannualrainfallabove2000mminthe

Southof themain island, frequentstormsandsteepslopes,combinedwithdeforestation, firesandminingactivity,

watererosiononultramaficsoilsisveryfrequent.Soilmicroorganismsincreasesoilaggregationandhencedecrease

soil erodibility. Plant roots also increase soil cohesion through exudation and decomposition processes. To our

knowledge,interactionsbetweenfungi,rootsandtheerodibilityofultramaficsoilshaveneverbeenstudied.

Theobjectiveofourstudyistoassesstheerodibilityofferraliticferriticsoilsonultramaficsubstrateindifferentplant

communitiesandtountangletheeffectofabioticandbioticfactors.

Weselected20plotsinfiveplantcommunitiesintheSouthofthemainisland:degradedligno-herbaceousshrubland,

ligno-herbaceous shrubland with dominance of ectomycorrhized Tristaniopsis glauca, degraded humid forest with

dominance of ectomycorrhized Arillastrum gummiferum, dense humid forest with dominance of ectomycorrhized

Nothofagusaequilateralis,andfinallymixeddensehumidforest.Thesetypesofvegetationarelikelytocorrespondto

differentsuccessionalphases.Ineachplot,wemeasuredsoilaggregatestability,soilcharacteristics(i.e.claycontent,

soilorganiccarbon,sesquioxides),roottraits,plantandsoilmicoorganismsdiversityindices.

ThesoilaggregatestabilityishighwithMWDabove2.9mmforallplantcommunities.Significativelylowestvaluesare

observedfordegradedligno-herbaceousshrublandanddensehumidforestdominatedbyNothofagusaequilateralis.

WithcontentofFesesquioxideabove10%forallplantcommunities,thisfactorislikelytobethemaincontributorto

highMWD.Yet,soilorganiccarbonandrootmassdensitycanincreaseitscontributionasobservedformixeddense

humidforest.Thosepreliminarydatawillbecompletedwithamorethoroughanalysisofroottraitsandafocuson

fungaldiversityandbiomass.

This study is the first of its kind inNewCaledonia andwill givenew insights toourunderstandingof erodibilityof

ultramafic soils. It will contribute to the development of ecological restoration of degraded ligno-herbaceous

shrubland.

Soilaggregatestabilityinfivedifferentplantcommunitiesandassessmentofabioticandbioticparameters

SBEE2016ABSTRACTS

32

SESSION8–MICROBIALECO-INTERACTIONSWITHSOILS

Keynote-DavidAireySBEE2–Bio-cementationforgroundimprovementD.W.Airey,Y.Duraisamy

SchoolofCivilEngineering,UniversityofSydney,NSW2006,Australia

Bio-cementationhasbeensuggestedasanenvironmentallysafemethodofgroundimprovementthatmakesuseof

in-situsoilandcanavoiddisruptiontoexistinginfrastructure.Theconceptistousebacteriawithsuitablenutrientsto

precipitatecementingagentswithinthesoil,aprocessknownasmicrobiallyinducedcalciteprecipitation(MICP).The

mostwidely investigatedapproachhasbeen touse thebacteriumsporosarcina pasteurii in combinationwithurea

and a calcium source to precipitate calcium carbonate. Several laboratory studies have confirmed that substantial

increasesinsoilstrengthandstiffnessarepossibleinsandysoils.Theviabilityofthetechniqueandthemethodsfor

creatingbio-cementationinfinergrainedsoilshavereceivedmuchlessattention.Thepaperwillprovideareviewof

thebio-cementationprocess,discussproceduresforcreatingbio-cementedsoilanddiscussthestrengthsthatcanbe

achieved.

SBEE37–Whichbioticdriverscanbetterexplainthevariabilityofrootmechanicsoftropicaltreespecies?ZhunMao,YanWang,JérômeNespoulous,RoyC.Sidle,AlexiaStokesetal.

INRA,UMRAMAP,BoulevarddelaLironde,34398MontpellierCedex5,France

BackgroundandAims

Littlequantitative information is availableon theprotective roleof tropical specieson slope sitesprone toerosive

phenomena.One of the key parameters to evaluate of species’ capabilities in erosionmitigation is root individual

scalemechanicaltraits.Weexplored,forthefirsttime,thevariabilityofrootmechanicsofseveraldominantspeciesin

tropicalecosystems.

Methods

Wecarriedoutexsituexperimentaltestsonrootsoffourcommontropicaltreespecies,i.e.BarringtoniafusicarpaHu,

Pometiapinnata J.R.Forst.&G.Forst.,BaccaurearamifloraLour.andPittosporopsiskerriiCraibasmodelspecies in

Xishuangbannaforests,Yunnan,China.Tensilestrengthandmodulusofelasticity,astwoofthemostimportant

rootmechanictraitswereestimated.

ResultsandConclusions

Rootmechanicsvarygreatlydependingonrootsizeandtreespecies.Androotsizetheprimordialfactordetermining

thevariabilityofrootmechanics,especiallyforveryfineroots.Thesignificantdisparityofrootmechanicsbetweenthe

fourtreespeciessuggeststhattheuseofgenericequationsinsoilstabilitymodellingproceduresmaynotberelevant

in tropical ecosystems that possess a high species richness level. General discussions are provided concerning the

disparityofgeomorphologicalmodellingbetweentemperateandtropicalforests.

Keywords:rootmechanics,tensilestrength,modulusofelasticity,tropical,forest.

SBEE2016ABSTRACTS

33

DAY4-THURSDAY14JULY

SESSION9-ECO-ENGINEERINGANDLANDRESTORATIONII

Keynote–FreddyReySBEE45–Identificationofmulti-benefitsofbioengineeringactionsFreddyRey,RenaudJaunatre,MaxBruciamacchie

UniversitéGrenobleAlpes,Irstea,UREMGR,St-Martin-d'Hères,France

WithintheseverelyerodedDurancecatchmentintheFrenchSouthernAlps,underamountainousandMediterranean

climate,severalstakeholderslaunchedapromisingresearch-actionprogramme15yearsago.Theideawastodevelop

abioengineeringstrategythatfavoursfinesedimentdepositionintheupstreampartofthecatchmentbasinandthus

decreasesthefinesedimentdeliveryintheriverdownstream,withoutrevegetatingthewholeerodedcatchment.This

minimalapproachrepresentsaninnovativeandsustainablenature-basedsolution.Itconsistsinimplantingvegetation

barriersingullyfloorsonly.Itisbasedontheuseofstructuresintheformofbrushlayersandbrushmatsofcuttings

ondeadwoodmicrodams.PurpleandwhiteWillows(SalixpurpureaandS.incana)areusedhereastheyprovedtheir

efficiencytoresproutandsurviveinsuchenvironment.Toevaluateactionefficiency,weevaluatedbothitsecological

andeconomicperformances.First,we investigatedhowtheecosystemunderrevegetationperformstwoecological

functions:sedimenttrappingandsoilformationinthegullybeds.ResultsshowthatSalixcuttingsandtheirtillersare

able to trap sediment. Then, we conducted a cost-beneficial analysis of this real-size experimental programme, in

termsofeconomic,socialandecologicalissues.Forthis,weinvestigatedthevariouscostsofdifferentbioengineering

actionsscenarii,aswellas thebeneficialandpositiveexternalities.Wearediscussing thesocial (protectionagainst

floods and inundations), economic (reducing of silting in hydroelectric dams) and ecological (restoration of the

physicalqualityof rivers) trade-offof this innovativebioengineeringstrategyandhow itcanbeoptimised,adapted

andexpandedtootherregions.For this,wetestedanewframework forecologicalengineeringprojectassessment

(ASPIRE application). It has three hierarchical levels: 1/the project: it is composed with weighted objectives, the

weightsaregivenbystakeholdersandaprojectscorecanbecalculatedforeachstakeholder;2/theobjectives:they

arecomposedwithweightedvariables;and3/thevariableswhicharestandardizedinordertobecomparabletoeach

other’s. Inamoregeneralway, the idea is todraw theattentionof stakeholderson themulti-benefitsofbio- and

ecological- engineering projects, in order to incite them to favour this kind of projects instead ofmono-objectives

ones.

SBEE40–LandslidesasdriversforslopeecosystemsevolutionA.Gonzalez-OllauriandS.B.Mickovski

SchoolofEngineeringandBuiltEnvironment,GlasgowCaledonianUniversity,CowcaddensRoadG40BAGlasgow,UnitedKingdom

Landslidesarenormallyseenascatastrophicgeomorphologicalprocessesthatleadtodramaticlossesofsoil,human

property and life globally. From an ecological perspective, this picture could be very different. Supported by the

‘EcosystemTheories’,small-scalelandslides,forinstance,maybeseenaslocaldisturbancesthatfostertheevolution

SBEE2016ABSTRACTS

34

ofslopeecosystemsandlandscapesaspartoftheirself-regulatingcapacity.Gaininginsightintohowslopeecosystems

functionandevolvecouldmakeeco-engineeringinterventionsevenmoresuccessful.

The aim of this study was to detect traits of ecosystem evolution in a landslide-prone coastal slope in Northeast

Scotland.Todoso,westudiedplantdiversityandbiomass,alongwithcertainsoilproperties,atdifferentlocationson

the slope. Results indicated that shallow landslides and mass instability encourage plant diversity, enhancing

ecosystem’sself-organization.Contrariwise,slopezoneswhicharelessdiverse,andhavehigherbiomass,maybethe

oneswithbetterstability.

SBEE15–ComparingnumericalmodellingapproachesfortheevaluationofrootreinforcementF.Bourrier,Z.Mao,M.Yang,T.Fourcaud

Irstea,UREMGR,SaintMartind’Hères,France

Toquantifyandevaluatetheeffectofrootreinforcementonslopestability,itisofprimaryimportancetounderstand

the mechanical interaction between roots and soil. At the slope scale, root reinforcement is a key input when

performingstabilityanalysisusingeitherLimitEquilibriumMethodorFiniteElementMethodbasedmodels.Innearly

allthepreviousapproaches,soilmechanicalreinforcementbytherootswasmodelledasasingleadditionalcohesion

tothesoileffectivecohesion.Thismodellingapproachallowedsimplifiedintegrationofrootsimpactonslopestability

andmadestabilitymodelseasytocompute.

Nevertheless,thehypothesisofconsideringtheeffectofrootsasanadditionalcohesiontermhasbeenincreasingly

challengedbystudiesconductingsoil-rootssheartestsatalocalscale,i.e.thescaleoftherootsystemorrootbundle

embeddedinsoil.Althoughtheexperimentalapproachesprovideaneffectivewaytostudyroot-soilinteraction,they

are usually time-consuming and laborious, especially for generating replicates, considering complex, multiple, and

correlatedroottraits,andcontrollingenvironmentalfactors.

Comparedtoexperimentaltests,numericalsimulationsattheplantscaleconstituteapromisingalternativetostudy

roots-soilinteraction.Despitedifficultiesinmodelvalidationusingfielddata,simulationsbasedontheFiniteElement

Methodcanbe consideredas reliablenumerical approachesgenerating very comparable resultswithexperimental

tests. Recently, a rooted soilmodelling approach based on the Discrete ElementMethodwas also developed and

showedpowerfulpotentialstoexplorecomplexroot-soilinteractions.

Inthisresearchwork,wesimulated3DdirectsheartestsusingthestandardimplicitFiniteElementMethod(FEM)and

the Discrete Element Method (DEM), aiming at (i) comparing the two numerical approaches and (ii) evaluating

classicalsoilreinforcementmodels.

For that purpose, in homogeneous soil with low cohesion, 36 straight, non-branched and thin root models were

implantedinthreeparallellines.Roottraits,includingorientationwithregardstotheshearstraindirection(45°,90°

and -45°), longitudinalmodulusofelasticity (10MPaand100MPa), andbendingandcompressive rootbehaviours

(beam,trussandcable)wereinvestigated.Theresultsfromthisanalysisclearlyshowedthat,comparedtotheFEM,

theDEMachievedconsistentresults,avoidedconvergenceproblems,butrequiredlongercomputationtimeandused

parameterspotentiallydifficulttoidentify.Inaddition,theDEMpresentstheadvantageofamoredetailedmodelling

of the root soil local interaction and, thus of root slippage into the soil. Both advantages and drawbacks of each

approachtendtoshowthenecessityofusingbothofthemascomplementarytoolsinfuturestudies.

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The results also showed that root reinforcement varied as a function of soil strain andwas closely related to root

geometry, location in the sample, andmechanical traits. In addition, existing root reinforcementmodels tended to

provide higher root reinforcement estimates than those achievedby numerical direct shear tests. As suggestedby

other recent research studies, the results highlight thenecessity to take into account theeffect of soil strain, root

orientation,position,roottypeandconfiningnormalpressure intheexistingrootreinforcementmodels inorderto

enhanceboththeiraccuracyofpredictionandtheirclosenesstothemodelledorobservedprocesses.

SESSION10–RIVERSPROTECTIONANDCATCHMENTMANAGEMENT

Keynote–AndrewSimonSBEE6–RoleofRiparianVegetationinFluvialGeomorphologyAndrewSimon

Cardno,Oxford,MS,USA

Riparianvegetationisafundamentalcomponentof landscapesystems. Itseffectsrangeacrossabroadspectrumof

geomorphic processes and scales relating to the hydrologic cycle, water budgets, and soil moisture as well as

resistancetooverlandandconcentratedflowsinchannelsandonfloodplains.Mostgermanetothisconferenceisthe

importantrolevegetationplaysinstreambankstability.Theinteractionandcontrolsofriparianvegetationonfluvial

processes can be separated into three general areas where it can often be regarded both as independent and

dependentvariables.Theseare:(1)hydrauliccontrolssuchasflowresistance,velocityandturbulence,(2)mechanical

controlseffecting initiationofmotion(criticalshearstress)andbank-failureprocessesbyrootreinforcement(shear

strength),and(3)hydrologiccontrolsoninfiltration,evapotranspirationandpore-waterpressure.

Riparianvegetationcanexert strong,direct influencesonerosion ratesbyprovidinggreater resistance tohydraulic

forces, reducing the effective stress acting on bank surfaces and enhancing geotechnical strength by root

reinforcement. For these reasons, vegetation has become a major component in designing stream-rehabilitation

measures.Riparianbufferstripsmadefromnativevegetationalongstreamchannelsreducehydraulicshearandtrap

sediment. A by-product of this application is the reduction of pore-water pressures in streambanks through

interceptionofprecipitationandremovalofwaterfromthebankmassbyevapotranspiration.Largewoodydebrisis

usedinchannels,ofteninmeanderbendstoprotectbanktoes,inducedeposition,andhaltlateralmigration.Aspects

of the role of vegetation in controlling hydraulics, bank stability, sediment transport and channel adjustment have

beguntobe incorporated intoquantitativeanalysesandnumericalmodelsofstreamchannels.Fieldand laboratory

studiestoquantifysomeoftheseimportantprocesseshaveledtoadvancesinnumericallyaccountingforvegetative

effectsandconsequentfluvialprocesses.Examplesofstudiesandapplicationofnumericalmodellingtoolssuchasthe

Bank-StabilityandToe-ErosionModel(BSTEM)willbeprovided.

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SBEE32–ComparisonandAnalysisonSedimentDischargeinDamagedandNon-damagedForests,RepublicofKoreaJ.P.Seo,C.Woo,D.Kim,C.Lee

NationalInstituteofForestScience,57Hoegi-ro,Dongdaemun-gu,Seoul02455,RepublicofKorea

Thisstudywasconductedtobeusedasbasicmaterialsindevelopingmethodsforrestoringandmanagingdamaged

forestsbasedon comparisonandanalysis on sedimentdischarge inbothdamagedandnon-damaged forests. Four

areaswereselectedforthestudy(forestdamagedbyforestfireanditscontrol;forestdamagedbylandslideandits

control).AnnualsedimentdischargeinallfourareaswascalculatedbyusingterrestrialLiDARimageswhichcaptured

time-periodicsedimentsattheerosioncontroldamslocatedattheoutletofeachwatershed.Theresultshowsthat

from2010to2014,theamountofsoillossinlandslidedamagedforestwas8.41m3/haandthatofitscontrol(1)was

4.79m3/ha.However,significantchangesinyearlysedimentdischargeduetoprecipitationcouldnotbefound(Fig.1).

On theotherhand,when it comes to forestdamagedby fire, soil loss indamaged forest amounted to5.11m3/ha

whilethelossinthecontrol(2)was1.22m3/hainthesamefiveyears(2010to2014).Itwasfoundthatyearlysoilloss

amountstartedtodecreasethreeyearsafterthedamage(Fig.1). Intermsoftotalsoil lossdifferencebetweenthe

twodamagedwatersheds,landslide-damagedwatershedwasassumedtogothroughbiggersoillossbecauseitsarea

waslargerthantheareaoffire-damagedwatershedby90haapproximately.Managingsoillossisimportantespecially

topreventsecondarydamagearisingfromsoillossincaseofmassivedeforestation.Importantly,forestdamagedby

fireisdeemedtoberestoredintheearlystageofdamagesoastopreventsoilloss.

Fig.1.Yearlysedimentdischargeduetoprecipitation

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SESSION11–HYDRO-GEOMORPHICPROCESSES

Keynote–DavidPolsterSBEE73-SoilBioengineeringfortheTreatmentofDrasticallyDisturbedSitesDavidPolster

PolsterEnvironmentalServicesLtd.

Soilbioengineeringistheuseoflivingplantmaterialstoperformanengineeringfunction.Soilbioengineeringcanbe

used to establish vegetation on steep and unstable sites. The use of pioneering species in soil bioengineering

treatments initiates the natural successional processes that will ensure the site remains vegetated. Soil

bioengineeringsystemsworkwithnaturalprocessestorestoredrasticallydisturbedsites.Treatmentssuchaswattle

fencesandmodifiedbrush layers canbeusedonover-steepened slopes (average slopeup to70degrees). Where

excessmoistureiscausingslopeinstabilities,livepoledrainscanbeinstalledtodrainthemoisture.Shorelineerosion

canbesolvedinmostcasesbytakingtheenergyoutofthemovingwater,eitherwavesorstreamcurrent.Denselive

stakingcanbeusedtoprotectshorelinesascandenseplantingsofemergentaquaticvegetation.Livesiltfencinguses

thissameprincipletoremovesedimentfromwater.Slowingtheflowallowssedimenttobedepositedandbyusing

livecuttingstodotheslowing,adenseshrubbywetlandcanbeconstructed.Livegravelbarstakingcanbeusedto

removeexcesssandandgravelfromriversthatwouldotherwisecauseavulsions. Theplantsusedinlivegravelbar

stakingcantoleratestemburialwhilecontinuingtogrow.Thiscreatesaconditionwherethegravelbarcontinuesto

collectsedimentwhilethevegetationstartstheprocessofsuccession. Thiswill result inrichalluvial forestsonthe

floodplain. There are a variety of techniques that can be used to re-build riparian vegetation including joint and

pocket planting and live palisades. Soil bioengineering systems provide an excellent tool for the restoration of

damagedsites.Byusingnativespecies,thesetreatmentscanbuildecosystemresilience.

SBEE33–SeasonalhydrologicalimpactsoflanduseonhillslopestabilityJ.H.Kim,A.deRouw,T.Fourcaud,J.L.Maeght,Z.Mao,J.Metayer,L.Meylan,A.Pierret,B.Rapidel,M.VillatoroSanchez,Y.Wang,A.Stokes

AMAP,Inra,Cirad,Ird,Cnrs,BddelaLironde,TAA-51/PS234398MontpellierCedex5,France

Shallow landslidescanposeamajor threat tohuman livesand infrastructureoversignificantportionsof thegloballand surface and occur primarily from weakened soil shear resistance due to water infiltration. Although there isgrowing interest in using vegetation to stabilize hillslopes against landslides, we noted the scarcity of studiesexaminingtemporalvariations inslopestability,particularlywithregardtodifferent landuses. Inthreetropicalandtemperatelandslide-proneregions(Laos,CostaRicaandFrance),wecombinedsoilmoisturemonitoringto1.2-1.8mdepths in the field, soil shear resistancemeasurements and numerical modeling to compare slope stability undercompeting land uses for 2-3 years. Slope stability tracked temporal changes in soil moisture, with smallercontributionsfromrootmechanicalreinforcement.Landuseswithdenservegetationhadgreaterstabilizingimpactsthan thosewith sparser vegetation,which lasted for six to twelvemonths per year and coincided temporallywithgrowingorrainy/dryseasons.Greaterstabilityunderdenser landusepersisted intowetseasons inoneofthesitesandwereminimized or reversed in the other two sites. Site-specific factors such as climate, soil and speciesmayexplainthesedifferencesinthevegetationalcontrolonslopestability.Areviewofthedataintheliteraturefoundthat

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woody vegetation increased slope stability and decreased temporal variation in stability compared to herbaceousvegetation.However,whilevariations inslopestabilitydecreased in increasinglyhumidclimates, indicatingthatthelargestfluctuationsinstability,andhencepotentialtoimproveslopeintegritywithland-usechanges,willbefoundinarid tosub-humidregions.Our results showthatdensevegetationprovidesgreaterstabilityandprotectionagainstlandslidesfromrainfall.Landmanagersneedtotakeintoaccountthisbiologicalcontrolonhydrologywhenmanagingvegetatedslopes.Incorporatingthevegetation-drivendeepsoilmoisturedynamicswillalsoimprovepredictiveutilityofmodelsofspecificevents.

SBEE41–AproxytoquantifythehydrologicaleffectofvegetationagainstlandslidesA.Gonzalez-OllauriandS.B.Mickovski

SchoolofEngineeringandBuiltEnvironment,GlasgowCaledonianUniversity,Glasgow,UnitedKingdom

Thequantificationofthehydrologicaleffectofvegetationagainstlandslidesischallengingandscarceinthescientificliterature. Relatively high soil matric suctions induced by plant evapotranspiration could enhance significantly theslopestabilityconditionsfromahydrologicalaspect.However,plant-soil-water interactionsarefarfrombeingclearand there is no consensus upon how the vegetation’s hydrological effect can be included within slope stabilityanalyses. In this sense, the suction stress characteristic function (SSCF), accounting for all the soil inter-particlestresses,couldbeusedasaproxytoquantifythevegetation’shydrologicaleffectagainstshallowlandslides.

In the present study we aim to set the basis for defining a simple, reproducible and straightforward laboratoryprotocoltoobtainthesuctionstresscharacteristicfunctionofthesoilbymeansofdirectsheartests.Additionally,weexplore SSCF deviations induced by vegetated soil and the possibility of inclusion of these results in an integratedmodelthatwouldaccountfortheeffectsofvegetationonslopestability.TheresultsfromourinvestigationwillshedlightonthepotentialuseoftheSSCFasaproxytoquantifythehydrologicaleffectofvegetationagainstlandslidesandwillenhanceourunderstandingonthetopic.

SBEE2016ABSTRACTS

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SBEE36–MortalityofVetiverGrassonHydrothermally-AlteredSlopesinMindanaoGeothermalProductionFieldReynaldoG.Añabieza,DemiIsabellaD.Abaniel,SherwinMervinBurtonE.Lucas,MSCE

EDC-MAGBU,Brgy.Ilomavis,KidapawanCity,9400,Philippines

Mosthydrothermally-alteredslopes,especiallysituatedingeothermalproductionfields,arepronetoinstabilitysuch

aslandslidesanddebrisflow.Oneparticularcaseoccurredon2009inMindanaoGeothermalProductionField(MGPF)

whereinmassivemasswastingresultedtothedestructionofrevenue-generatingsteamlinesandotherproperties.1

The subsurface investigations on the reconfigured slope revealed acceptable engineering property values for slope

stability model inputs.2 This lead to the recommendation of using Chrysopogon Zizanioides ("Vetiver grass") for

mitigationduringdesigndevelopmentandearlyimplementationstages.

The principles of slope stability modeling for both natural and hydrothermally-altered slopes have no variance.3

Likewise,inclusionofvegetationinthemodelswouldalsoleadtohighersafetyfactors,increasingtheconfidenceof

engineering judgment in using such.4However, an immediate finding on themitigation conducted on 2013 for the

2009masswastingincidentshowsthatroughly30%ofthevetivergrassplantedon1,650squaremeterareasurvived

inspiteofpresenceofothervegetation,promptingthemanagementtochangethemitigationplanmidwaybyshifting

todrymixreinforcedshotcrete.

A separate geologic study understanding the mineral and chemical compositions, together with a slope stability

analysisconsideringvadozezonebehaviorbeconductedrigorouslywhenbio-engineeringmeasuresareconsidered.

There is also a need to further understand the conditional requirements for a certain vegetation to survive a

hydrothermally-alteredprofilepriortoapplication.5MGPFutilizesitssitegeologisttoconductmineralogyevaluations

on retrievedborehole samples in addition to the installationofmoisture sensors, rain gauges, andpiezometerson

selectedhydrothermally-altered slopes to furtherunderstandhydrolgicalmovementneeded todevelop thedesign,

economics,andapplicabilityofacertainbio-engineeringmeasure.

References

1. W. P. C. Pioquinto, “Geohazard Assessment of Pad G, Mindanao Geothermal Production Field”, EDC Internal

Report.March2009

2. O.A.Manigosetal.,"GeotechnicalInvestigationofLandslideAreatoPadG",IndustrialInspection(International),

Inc.,MakatiCity,FactualReportRef.#002/10/DS-6May2010

3. M. E. Reid et al., "Preliminary Slope-Stability Analysis of Augustine Volcano", The 2006 Eruption of Augustine

Volcano,Alaska,USGSProfessionalPaper1769,eds.2010,pp.321-334

4. Y. H. Chok et al., "Modelling the Effects of Vegetation on Stability of Slopes", 9th Australia New Zealand

ConferenceonGeomechanics,Auckland,2004,pp.391-397

5. F. B. Salisbury, "Soil Formation and Vegetation on Hydrothermally Altered Rock Material in Utah" [Online].

Available:http://www.jstor.org/stable/1937102,DOI:10.2307/1937102

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SBEE13–DesirablePlantFunctionalTraitsforHydrologicalReinforcementofSlopesD.Boldrin,A.K.LeungandA.G.Bengough

SchoolofScienceandEngineering,UniversityofDundee,Dundee,UK

Vegetation provides slope stabilisation via mechanical reinforcement through root anchorage and hydrological

reinforcementthroughtranspiration-inducedsuction.Thereisrelativelylittleinformationaboutplanttraitsaffecting

hydrologicalreinforcement.Thisstudyaimstoidentifyplanttraitsthatcorrelatewiththehydrologicalreinforcement

ofsoil,providingengineerswithmeasurableplantparametersforimprovedspeciesselection.

TenspeciesnativetoEuropewereinvestigatedinglasshouseexperiments.ThespeciesincludeBuxussempervirensL.;

CorylusavellanaL.;CrataegusmonogynaJacq.;Cytisusscoparius(L.)Link;EuonymuseuropaeusL.;IlexaquifoliumL.;

Ligustrum vulgare L.; Prunus spinosa L.; Salix viminalis L. and Ulex europaeus L. These species were planted in

individualpotsofsandyloamsoilwithadrybulkdensityof1.2Mg/m3.Threepotswereleftbareasfallowcontrols.

Evapotranspiration(plantedpots)andevaporation(fallowpots)weremonitoredfor13daysfollowingsoilsaturation.

Matric suction and soil penetration resistance induced by the hydrological reinforcement were also recorded.

Candidateaboveandbelow-groundplantfunctionaltraitsweremeasuredforeachspecies.

The ten species had large differences in water uptake, which

translated to significant differences in matric suction and

penetrationresistance(Fig.1A&B).Specieswiththehighestwater

uptake(e.g.,U.europaeus) increasedsoilstrengthtomorethan10

timesthatinfallowsoil.

Specific leaf area was an important above-ground trait correlated

withthehydrologicalreinforcement.Thistraitisalsoanindicatorof

plant competivity in harsh environments such as man-made road

slopes (Bochet & García-Fayos, 2015). Root length density, also

beneficialformechanicalreinforcement(Ghestemetal.,2014),was

agoodpredictorofhydrologicalreinforcementinducedbydifferent

species.Theroot:shootratio,showedthebestcorrelationwiththe

hydrological reinforcement. In fact, this ratio explained 95% and

85%of thevariability inmatric suctionandpenetration resistance,

respectively.Theimportanceofconsideringthecombinedeffectsof

both below- and above- ground organs for the hydrological

reinforcementwillbediscussed.

References

Bochet E, García-Fayos P, 2015. Identifying plant traits: A key aspect for species selection in restoration of eroded roadsides in semiarid environments. Ecological Engineering 83, 444-51.

Ghestem M, Cao K, Ma W, et al., 2014. A Framework for Identifying Plant Species to Be Used as 'Ecological Engineers' for Fixing Soil on Unstable Slopes. Plos One 9.

Bs Ca Cm Cs Ee Ia Lv Ps Sv Ue

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Figure 1 Mean matric suction (A) and soil penetration resistance (B) in planted pots. Acronyms of species are reported on X axis. Dashed line represents mean value in fallow pots. Letters indicate significant differences (ANOVA - post hoc Tukey's test).

SBEE2016ABSTRACTS

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ABSTRACTS–POSTERPRESENTATIONSDAY1-MONDAY11JULY

SESSIONP1

SBEE51–BenefitsofTerraceRiserBasedAgri-silvo-pastoralModelinSoilStability,RiserProtectionandAgricultureT.P.Barakoti

NepalAgriculturalResearchCouncil,Nepal

Anewagri-silvo-pastoralmodelwasdeveloped for themountainagro-ecological conditionofNepalwitha view to

utilizetheone-thirdlandsleft intheterraceriserandprotectsoilfromerosionandlandslides.Twodozenoffodder

treesandforagecropsweretestedatdifferentlocationsofhillsin2009-2014.Identificationofsuitablemultipurpose

trees, quantification of shade effects on growth and yield of major crops verified employing innovative idea of

cultivating fodder species in the terrace riser of cropping land. All the tested fodder species preferred by farmers

survived (85-100%) with good growth and yield and less shade effect on crop. The trees and forage crops in the

terraceriserfoundcompatible.Foddertreeswereloppedatbreastheightin2ndand3rdyearaspernewmodeland

gaverisegoodcoppicesandbranches.

The grain and biomass yields ofmaize andmillet depended upon tree species however the yieldswere notmuch

decreasedclosetotherisercomparedtotraditionaltree-cropinterfacewithtallandbigtrees.Ficussemicordatahad

fast growth and more fodder yield followed by Grewia oppositifolia but caused more shade effect to the crops.

Bauhinia purpurea and Litsea monopetala had positive effect on maize. Leucaena diversifolia had the excellent

growth,coppicesandfodderyield.ThepromisingforagespeciesforplantinginterraceriseridentifiedasPennisetum

purpureum, Thysalonaemamaxima, Setaria anceps,Desmodium intortum,Melinis minutiflora, Brachiareamutica,

Lolium perenne, Dactylis glomerata, Chloris gayana, Stylosanthis guianensis. The model was useful to utilize the

terrace riser with fodder species. The tree roots and forage covers served as good bio-engineering measure to

conserve soil andprotect riser from landslide. It supported year round supplyof fodder for livestock, enhance soil

fertilityandcropproduction.Replicationofthisagroforestrymodelinsimilarpartsissuggestedforbeneficialimpact

tosoil,cropandfarm.

SBEE53–Mycorrhizaaspromoterineco-engineeringonmountainslopes:Inoculationeffectsonplantsurvival,aggregatestability,andfine-rootdevelopmentA.Bast,H.Gärtner

SwissFederalInstituteforForest,SnowandLandscapeResearch(WSL),LandscapeDynamics/Dendroecology,Zürcherstrasse111,8903Birmensdorf,Switzerland

Highmountainenvironments,characterizedbysteeptalusslopeswithalackingvegetationcoverandLeptosolsasthe

dominant soil type, entail a certain risk potential through superficial slope failures and surface erosion. Eco-

engineeringmeasuresprovedtobeadvantageousforriskmitigationandhence,toavoidslopeinstabilities.Basedona

SBEE2016ABSTRACTS

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uniqueeco-engineeringfieldexperiment,weestablishedmycorrhizalandnon-mycorrhizaltreatedresearchplotsand

discussed the biophysical contribution to small scale soil fixation. We analyzed whether mycorrhizal inoculation

impactsplantsurvival,aggregatestabilityandfinerootdevelopment.Herewepresentplantsurvivalanalyses(ntotal=

1248)andanalyzedsoilcores(ntotal=108)takenwithinamonitoredperiodofthreeconsecutivegrowingseasonsin

theSwissAlps.Thecoreswereassayedforasoilaggregatestabilitycoefficient (ASC), root lengthdensity (RLD)and

meanrootdiameter(MRD).Inoculationimprovedplantsurvivalsignificantly,butitdelayedsoilaggregatestabilization

relative to the non-inoculated site. Inoculation resulted in a higher aggregate stability only after three growing

seasons. At the end of the third growing season RLD tended to be higher andMRD increased significantly at the

mycorrhizaltreatedsite.TherewasapositivecorrelationbetweenRLDandASC.Roots<0.5mmweightedmostinsoil

aggregation.Ourresultsrevealedatemporaloffsetbetweeninoculationeffectstestedinlaboratory/greenhouseand

field experiments. Before applying laboratory/greenhouse results to field scale we recommend to establish an

intermediatetolong-termfield-experimentalmonitoringtoguarantyasuccessfulpracticalimplementation.

SBEE10–AssessmentofdecayofsilverfirlogsexposedtooutdoorconditionsbynearinfraredspectroscopyandvibrationresonantmethodsJ.B.Barré,F.Bourrier,D.Bertrand,F.Rey

UniversitéGrenobleAlpes,Irstea,UREMGR,France

Ecological engineering structures devoted to mitigation of natural hazards are often embedding inert timber

structures.Thesestructuresarebuiltfromalayoutoflogsandmostlymadeoflocalsoftwoodsuchaslarch,Douglas

fir,pineor silver fir.They require specificattention frompractitioners tomonitor thedecaystageof the logs since

woodisnotprotectedagainstdecomposers.But,practitionersarefacedwithalackofknowledgeinquantifyingthe

decayextentinsuchstructures.

Twonon-destructivemethodsforquantifyingtheextentindecayoflogsareparticularlyadaptedgiventheconstraints

imposed by ecological engineering structures. The first method is the near infrared spectroscopy (NIRS) allows

measuring infrared absorption of sample molecules for wavelengths in the range 4000 - 10000 cm-1. The second

methodisthevibrationresonantmethod(VRMallowsdynamicallymeasuringthemechanicalpropertiesofthelogs.

Bothmethods have been already tested on silver fir stems decayed under artificial conditions. On the one hand,

modelshavebeendevelopedfromNIRSspectratopredictlossinmechanicalpropertiesusingpartialleastregression

andmechanicalpropertiesasreferencesvalues.Ontheotherhand,specificindicatorsofthedecreaseinmodulusof

elasticityanddampingratiohavebeendevelopedfromVRMmeasurements.Resultshaveconfirmedthecapacityof

theseindicatorstoquantifydecaywhosepotentialshavebeenfinallytestedinnaturalconditions.

From2013to2016,anexperimenthasbeenimplementedintheGrésivaudanvalley(Isère-France),wheresilverfir

logshavebeenputingroundcontactinfourdifferentsites.MeasurementsbyNIRSandVRMhavebeenperformedat

sound (2013) and decayed (2016) stages. The results of bothmethodswere analysed and compared to determine

theiraccuracyonroughlogsdecayedinnaturalconditions.Specificattentionhasbeendevotedtotheirsensitivityon

thedifferentconditionsofdegradationcorrespondingtothefourstudiedsites.Bothmethodsconfirmtheirabilityto

quantify decay. This study confirms the potential of these twomethods to help practitioners in appraising timber

structuresusedinecologicalengineering.

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SBEE65–CreatingandViewing3DModelsofRootsWalterW.Chen,FuanTsai,Kai-JieYang,Dong-HuangLi,andJing-YuanLi

Dept.ofCivilEngineering,NationalTaipeiUniversityofTechnology,Taipei,Taiwan

Vegetationplaysacriticalroleinstabilizingnaturalslopes.Forexample,thecanopyoftreesandtheleafsofgrasses

protect the soils on the ground from raindrop splashes, and the root of vegetation (particularly trees and bushes)

reinforcessoilandpreventsmasssliding.Inregardstoroots,differenceintheshapesanddiametersoftherootswill

affect their tensile strength and change the effect of soil reinforcement. To study and compare reinforcement

behaviors of different roots, it is important to be able to characterize individual roots bymeasuring not only the

diametersoftheroots,butalsotheoverallshapeandbendoftheroots.Toachievethispurpose,theauthorsstudied

new photogrammetric tools in this project to create virtual three-dimensional (3D) models of roots. The models

lookedrealisticandhadaccuratedimensions.Afterthecreationofthe3Dmodels,the“virtual”rootscanbeviewed

and examined on a computer screen in great details and shared instantly by researchers at different geophysical

locations.Moreover,theoriginalrootscanbeduplicatedphysicallyby3Dprintersbasedonthe3Dmodels.Ifproper

materialwithequivalentmechanicalpropertiesoftherootscanbefoundandusedinprinting,the3Dprintedroots

canfurtherbeusedassubjectsoflaboratorytesting.

SBEE54–Stabilizationofsoilaggregatesonroadsideembankmentsalonga70years-oldvegetationsuccessionalgradientA.Erktan1,C.Roumet,F.Pailler,T.Fourcaud,Y.LeBissonnais,A.Stokes

INRA,UMRAMAP,BlddelaLironde,Montpelliercedex5,34398,France

The stabilization of roadside embankments is amajor challenge for landmanagersworldwide.Whilemost studies

focusedontheshort-terminfluenceofrevegetationmeasures(suchasplantingorhydroseeding)onsoilstabilization,

little isknownaboutthe long-termeffectofsuccessionaldynamicsoccurringalongroadsides.Ouraimistoexplore

the influenceof a vegetation successional dynamic on the stabilizationof soil aggregates, a proxy for soil stability,

alonga70-yearsroadsidechronosequence.Weselected24plots(16x4m)onembankmentsalongroadsidesinthe

Mediterraneanregion(SouthFrance),spreadinto5age-classes(0-10;11-20;21-30;31-40and>40years-old,Fig.1).

Wemeasured soil aggregate stability and several soil (soil organic carbon, soil nitrogen, soil texture, pH, CEC) and

vegetation (rootmorphology, rootmass density, plant community composition) characteristics.We found that soil

aggregatestabilityvariedsignificantlyalongthesuccessionalgradient,fromunstableinearly-successionalplots(0-10

years-old)toverystableinlate-successionalplots(>40years-old).Moreprecisely,soilaggregatesfirstappearedstable

in the 31-40 years-old age class, reflecting that efficient stabilization of soil embankments by vegetation dynamics

requiredabout3decades(Fig.2).Wenoticethatthemostcriticalperiodforembankmentstabilityisrestrictedtothe

SBEE2016ABSTRACTS

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0-10 years-old class, characterized by unstable aggregates and thus high erosive risk, while moderate stability is

reachedfrom11-20years-oldclass.

This highlights the importance to invest in revegetation measures in the first decade after roadside construction.

Along the gradient, the accumulationof soil organic carbon related toplant communitydynamics appearedas the

major factor driving the stabilization of soil aggregates. The increase in root density also enhanced soil aggregate

stability.Remarkably,thereplacementofherbsspeciesbyshrubsandtreespeciesasthesuccessionproceededwas

not related to any destabilization of the soils, even though the direct soil coverage is usually reduced by

encroachment. To conclude, vegetation successional dynamics are responsible for the long-term stabilization soil

aggregatesonroadsideembankments.

SBEE27–PostfirebioengineeringremediationinPinuscanariensisforestsF.Giadrossich,G.Tardio,S.Mickovski

DepartmentofAgriculture,UniversityofSassari,viaEnricodeNicola1,07100Sassari,Italy

CanaryIslandspine(Pinuscanariensis) isanendemicconiferspeciesthatregeneratesbothbyseedandbyepitomic

shoots growing form the lower trunk after a perturbation like cutting or wildfire. Even though the ecological

adaptation to fire allows for a relatively rapid regenerationof the soil cover,wildfiremay causedisasters inducing

abruptecologicalchangesandsoillosses.OnCanaryIslands,duringthewildfirebetween30Julyand2August2007,

about18.000hectaresofforestweredestroyed.

Inthisworkwedescribethepost-bioengineeringtechniquesusedtomitigatesoillossesduetoheavyrainfallduring

theCanary Islandswetseason.Aseriesofmixeddykes (woodenelementsandstoneswithacore filledwith forest

residues)werebuiltinthegulliescreatedbythesurfacerunoffandthesoilssusceptibletoerosion.Weanalysedthe

soilpropertiesandmeasuredplantheights,diameters,landcover,litter,plantabundanceandspeciesrichnessindices

nearthemixeddykesincomparisonswithsurroundingareas.

FireadaptationsoftheCanaryIslandsvegetation(pyrophyteplants)coupledwithselectedbioengineeringtechniques

facilitated the seedling germination and allowed the restoration of the forest ecosystem while reducing the soil

erosionrates.

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SBEE71–EffectofheatshockonseedgerminationofthreespeciesofPinaceaeinGreatHing’anMountainsHuiyanGu,KeyanJiang

SchoolofForestry,NortheastForestryUniversity,HeilongjiangProvince,P.R.China

The rootmorphologicaldistributionand theenhancementeffectsonsoilanti-scouribilityandsoilanti-erodibilityof

roots ofAmorpha fruticose, Tamarix chinensis,Hippophae rhamnoides andCaraganamicrophylla were conducted.

The soil anti-scouribility was identified by using the undisturbed soil trough scouring method while the soil anti-

erodibilitywasidentifiedbyhydrostaticcollapsemethod.Theresultshowed:Therootbiomassaremainlydistributed

in 0-20 cm layer of soil and the root biomass decreases with the increasing of the soil depth． The thin roots is

important in the composition of root biomass. Roots have significantly positive enhancement effects on soil anti-

scouribility． Biomass of ≤1 mm roots，1-3 mm roots，and the organic matter content of soil are significantly

positivecorrelationwithsoilanti-scouribilityvalues.Rootshavesignificantlypositiveenhancementeffectsonsoilanti-

erodibility.Biomassof≤1mmrootsandtheorganicmattercontentofsoilaresignificantlypositivecorrelationwith

soilanti-erodibilityvalues.RootsofAmorphafruticosaandTamarixchinensishavesignificantlypositiveenhancement

effectsonsoilerosionresistance.

Keywords:Rootdistributioncharacteristics;Rootbiomass;Soilanti-scouribility;Soilanti-erodibility

SBEE59–Pull-outstrengthofPinusradiatarootsandtheircontributiontoslopestabilityF.D.Hiltebrand,M.Marden,J.Ekanayake,M.Schwarz,PhillipsC.J.

HAFLBern,Switzerland

InthefaceofwidespreaderosionproblemsinNewZealand’sNorthIsland,qualitativeandquantitativeknowledgeofthe contribution of trees to slope stability is recognised as key priority to informerosion control. Determining the

contributionoftreestoslopestabilitythroughrootreinforcementrequiresdataontensilestress-relatedbehaviourof

rootsand the distributionof rootsat thehillslopescale.Pinus radiata is thedominant forestplantation species in

NewZealandandrootpull-outdataforthisspecieshavenotbeengatheredtodate.Measurementsofin-situpull-out

testsofPinusradiatarootsintheGisborneDistrict(EastCoastRegion)wereperformed,andtherelationshipbetween

rootdiameterandpull-outstrengthwerefittedbyanon-linearregression.Atotalof31rootswithdiametersbetween

9 and 55mmwere tested. The pull-out strength varied between 0.4 and 25 kN. The correlation between pull-out

strength and root diameter is highly variable and needs to be considered in root reinforcement calculations. The

residualsbetweenmeasuresandnon-linearregressiontendedtoincreasewithincreasingdiameter.Nevertheless,the

resultssuggestthatcomparedtothelaboratorytensiletestsforotherspecies,theforcevaluesforrootslargerthan5

mmindiametertendtobeconsiderablylower.TheimplementationoftheresultsintoaRootBundleModel(RBMw)

that includes rootdistributiondata indicates that the contributionof coarse rootswithdiameter≤10mm to slope

stabilityisnegligiblecomparedtothecontributionofrootdiameterclasses>10mm.Theresultsofthisstudyarean

importantbasisforthefurtherquantificationofrootreinforcementcontributionofPinusradiatatoslopestabilityin

NewZealand. Inaddition,thefieldpull-outtestsperformedwithcoarseroots,contributesconsiderablytoclarifying

theroleofdifferentrootclassdiameterstothetotalrootreinforcementintermsofforce-displacementbehaviours.

Keywords:Rootreinforcement,Pinusradiata,in-situpull-outtest,slopestability,RBMw

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SBEE2016ABSTRACTS

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SBEE66–Estimatingcanopyinterceptionforaspecies-richprimarytropicalforestLin,Y.-C,Song,G.-Z.M,Tu,S.-Y,Chao,K.-J

DepartmentofSoilandWaterConservation,NationalChungHsingUniversity,TaichungCity,Taiwan

Most studies for canopy interception are conducted in species-poor vegetation. The main aim of our study is to

establishanempiricalmodelforestimatingcanopyinterceptioninaspecies-richprimarytropicalforestwithmultiple-

layeredcanopies.Thisprimaryforest,whichdominanttreespeciesareFicusbenjaminaandDendrocnidemeyeniana,

is located in theKentingNationalParkofTaiwan.Thenumberof treespecies inour2.1-haplot (140mby150m) is

101.Thereareat leastthree layersofcanopies(canopy,sub-canopyandunderstory layers).Theoverstoreycanopy

height of this forest ranges from 15m to 20m. Thirty sites in the 2.1-ha plot are sampled systematically (interval

between sites is20m) tomeasure throughfall.Among the30 sites, three sitesare installedwithbothmanualand

automaticraingauges;onlyamanualraingaugeisinstalledforeachoftheother27sites.Incidentrainfallismeasured

with an automatic rain gauge placed in an open area. Rain gauges are all installed 1.3m above the ground. The

accumulated rainfall collected inmanual rain gauges will bemeasured at least once every threemonths. Canopy

hemisphericalphotographs(CHPs)aretakenat fiveheights (1.3m,3m,5m,7mand9m)foreachofthethirtysites.

Leaf area index (LAI) estimatedwith canopyhemisphericalphotographswill beusedas the independent factors to

estimate rainfall intercepted by canopies. Although the preliminary regression analyses showed that LAI ring 4

estimatedwithCHPstakenatheightof3mcanprovidebestestimationforthethroughfallamount,thecoefficientof

determinationwasrelativelylow(R2=0.16).InadditiontotheheightfortakingCHPs,weplantoincreaseestimation

accuracybyvaryingLAIviewringandthefrequencyofthroughfallmeasuring.

SBEE56–Yoursoilisvaluable–planttreestokeepit!IanMcIvor,GrantDouglas

Plant&FoodResearch,PrivateBag11600,ManawatuMailCentre,PalmerstonNorth4442,NewZealand.

Soil is a finite resource, and needs to be conserved. Soils on pastoral hill slopes need tree protection. Particular

attributes (ease of establishment, quick growth, extensive lateral root system, response to management, fodder

value, deciduous character) of poplars and willows make them very suitable for soil conservation in pastoral hill

country.

Asageneralrule,thebiggerthetree,themoresoilitprotectsfromslipping.Atreeprotectsmoresoilwhenitisclose

toothertrees.Evidenceof theeffectof trees inreducingslippingonhill sitescomparedtopasture-onlyhill sites is

given.Evidencethatlargertreesprovidemoreprotectionfromslippingthansmallertreesisalsopresented

Bigger trees have bigger root systems and protectmore soil. The intermeshing of root systems of adjoining trees

increasesthereinforcementofsoilandprovidesgreaterresistancetoslippageofsaturatedsoilonslopes.

Treesplantedforsoilconservationshouldbeplantedclosetogether,andthespacingincreasedasthetreesgrow,by

theremovalofexcesstrees.

Conservation trees can bemanaged so that the loss of pasture through tree shading isminimised. Trees can be

pollarded to reduce the canopy size and increase light topasture. Trees canbepruned so that the shadow is cast

furtherawayfromthetreeallowingmorelighttothepasture.Thisalsodispersescampingstockandanimalmanure.

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Inthelongterm,reductionofpastureproductionduetothepresenceofconservationtreesisthoughttobeoffsetby

thebenefitsoferosionreduction,stockshading,shelterandfodder.

SBEE57–Rootreinforcementdynamicsincoppicewoodlandsandtheireffectonshallowlandslides:areviewSchwarzM,VerganiC,GiadrossichF,ConderaM,BuckleyP,PiussiP,SalbitanoF,LovreglioR

BernUniversityofAppliedSciences,Zollikofen,Switzerland

InEuropeanmountainregions,forestsplayanimportantroleinthemitigationoftheriskduetonaturalhazardssuch

as landslides, rockfall, floods and avalanches. In these areas the amount given over to protection forest cover can

accountforupto50%ofthetotalforestarea.

Conifer species usually provide a protective effect at higher altitude,while at lower altitude broadleaf species are

dominant.EspeciallyinthesouthernsideoftheEuropeanAlps,theseforestwereoftenmanagedascoppicesystems.

The high stem density of coppice stands, the rapid growth which forms a complete cover in few years and the

permanenceoftherootsysteminthesoilcanbeconsideredasassetsintermsofprotectivefunction.

However, these considerations are poorly researched and there is generally a lack of studies investigating the

suitabilityofcoppiceasprotectionforests.Thisisparticularlytrueifthelandslidehazardisconsidered.

The issue is relevant considering thatmany coppice stands inmountain regionshavebecomeuneconomicandare

nowabandonedandoveraged.Overaged coppice stools displayoversizedaerial biomass and limited root systems,

andthismayleadtounstablestoolstructuresandeventuallytouprooting.

Howtomanage(ornotmanage)theseforeststandsisakeyquestionforpractitioners.

Inthiscontributionweanalyzethe implicationsofcoppicemanagement forslopestabilityand inparticularshallow

landslides,focusingonrootreinforcement,themainmechanismbywhichvegetationcanreinforceslopes..

We review available studies concerning root distribution and temporal dynamics in coppice stands, distinguishing

betweenspeciesandtypeofcoppicemanagement.Thenweformulatehypothesesabouttheircontributioninterms

ofrootreinforcementbyapplyingexistingnumericalmodels.

Theoutcomesofthereviewsuggeststhatthemanagementofcoppicestandshouldaimatincreasingtheextensionof

rootsystemandinparticularthepresenceofcoarserootsonhillslopespronetoshallowlandslides.Toreachthisgoal,

it is important todifferentiate themanagement strategydependingon the species considered,asdifferent species

havedifferentstrategiesconcerningtherenewaloftherootsystemaftercoppicing.

Finallywehighlightthelackofknowledgeandthefurtherstepsneededtoproperlyevaluatetheeffectivenessofthe

coppicesysteminprotectingagainstshallowlandslides.

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SBEE72–AnewframeworkforthequantificationofthehydrologicalconnectivityofvegetatedslopesM.Schwarz

BernUniversityofAppliedSciences,Zollikofen,Switzerland

Vegetationstronglyinfluencesthehydrologyofhillslopesthroughdifferentprocessesandthehydrologicaleffectsof

vegetationareconsideredimportantforthemitigationoffloodrisksinmanysituations.Thecomplicatedinteractions

ofmechanisms that contribute to the formation of runoff at different spatial and temporal scales represent a big

challengeforcatchmenthydrology.However,itisrecognizedthatstoragecapacityandinfiltrationareoneofthemost

importantprocessespositivelyinfluencedbyvegetation.Moreover,numericalstudieshavediscussedtheimportance

of preferential subsurface flow as dominant processes contributing to fast runoff inmountain catchments.While,

previousstudieshaveshowntheimportanceofbedrocktopographyontheconnectivityanddrainageofshallowsoil

mantledhillslopes,nostudiesdiscussedtheroleofheterogeneousrootdistributiononthedrainageofhillslopewith

stagnic soils so far. In this work we present a conceptual model that aims to link modelling approaches of root

distribution combined to hydrological modelling of preferential flow, and the quantification of hydrological

connectivityofforesthillslopes.Weuseaspatialdistributedrootdistributionmodeltocalculatethenumberoffine

rootsbasedonthestructureofforestcover(treepositionanddimension).Theresultsofrootdistributionareusedas

inputparameter for thequantificationofpreferential flowpatchesusinganumericalapproach.Finally,weuse the

spatial distributed values of preferential flow to calculate the hydrological connectivity of a vegetated hillslope

considering topography and soil profile characteristics. The new proposed framework is calibrated through field

experiments at the soil profile scale, and the first results of the numerical simulations considering different

combinationofparametersarediscussedinthecontextofprotectionforestsmitigationeffectsagainstfloodrisks.

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DAY2-TUESDAY12JULY

SESSIONP2

SBEE52–BasketofAgroforestryModelsUsefulforHillsandPlainAreasofNepalT.P.BarakotiandS.R.Katuwal

PakhribasAgricultureCentre,Dhankuta,Nepal

Existing models of agroforestry systems were assessed across Nepal to identify viable models for the farming

communities and formaintaining ecological environment. The outcomes of the study revealed a number of useful

agri-silviculture, silvo-pastoral and agri-silvo-pastoral models adapted in different physiographic regions. Overall

traditional agroforestry comprising of homestead garden, tree-crop interface, agri-silvo-pastoral and silvo-pastoral

models and new models are common. The importance of the models lies behind fodder/biomass production for

livestock,poleand firewoodproduction, soilerosion/ landslidecontrol,nitrogen fixation/soil fertilitymaintenance,

farmproductivitysustenanceandecosystembalance.

In theTeraibelt,agri-silviculturewithcereals (eg.paddyundermangotree)andvegetables (underdifferent trees),

horto-pastoralwith fruit trees (mango, litchi, jackfruit) andbanana, silvo-pastoralwith fodder trees, andDalbergia

sissoo, tectona grandis, eucalyptus spp., shorea robusta, pig-fishery-banana, beekeeping,multi-story croppingwith

coconutandarecanut trees, tea-albizia sp.arecommonlyadopted. In themidhills, agri-silvo-pastoral systemwith

citrus trees (mandarin,orange, lime),homesteadgarden,andsilvo-pastoral systemswithgrazingwere identifiedas

commonmodels.Inthemountainregion,commonmodelisthesilvo-pastoralwithrangeland(mixedtreespeciesand

forages). The Taungya model borrowed from Burma in Terai plain and shifting cultivation in the hills are still in

practice.Theresultofthestudyhassignificanceastheselectedmodelswouldbeusefultoreplicateinsimilaragro-

ecologicalzonesofthehillsandplainareaswheresuchmodelsarelacking.Thebasketagroforestrymodelsmightbe

usefulinAsiaandothercontinents.

SBEE55–ModelingbioengineeringtraitsofJatrophacurcasL.F.Giadrossich,D.Cohen,M.Schwarz,G.Seddaiu,N.Contran,M.Lubino,O.A.Valdés-Rodriguez,M.Niedda

DepartmentofAgriculture,UniversityofSassari,viaEnricodeNicola1,07100Sassari,Italy

ThewidedistributionofJatrophacurcasL. intropicalareasprovidestheopportunitytousethisplantfor improving

slopestabilityandcontrollingerosion.TodeterminetheeffectivenessofJatrophacurcasL.asabio-engineeringplant

wemeasuredstemdiameterandheightof1,3,5,6,18,and36month-oldplants,androotdistributionat6,18,and

36 months by full excavation of the root system. We also measured in the laboratory the elastic modulus and

maximum tensile force of 50 roots. These data were used to calibrate a weighted log-likelihood root distribution

modelandarootreinforcementmodel.Modelswerecoupledtoestimaterootreinforcementatstandscaleovera

three year period as a function of the plantation’s tree density. Our results of root distribution indicate a rapid

decreaseofrootdiameteralongtherootlengthleadingtorapidlydecreasingrootreinforcementwithdistancefrom

thestem.Minimalrootreinforcementat0.5mfromthestemisabout1and11kPafor18and36-montholdplants,

respectively.At1mfromthestemonly36-montholdplantsprovideanysignificantrootreinforcement.Despite its

SBEE2016ABSTRACTS

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relatively lowrootreinforcementrelativetoother largertreespeciesJatrophacurcasL. isasuitablebioengineering

plantbecauseiteasilypropagates,growsfast,andisresilient.Rootreinforcementinthefirststageofgrowthneeds

high-densityplantationofupto40,000plantsperhectare.Thisshouldthenbefollowedbythinningdownto10,000

plantsperhectaretooptimizerootreinforcementat3yearsage.

SBEE67–Novelsolutionsforsoilandriverbioengineering:prefabricatedandfoldingframeworksF.Brucalassi,E.Guastini,L.Mazzanti,F.Preti

EvintechS.r.l.,viaBotriolo9/b-52020CastelfrancodiSopra(AR),Italy-www.evintechsrl.it

Thisstudyaimstopresentframeworksfororiginalandcheapsoilandriverbioengineeringtechniques.Wedeveloped

prefabricated structures made of logs jointed with threaded rods; such patented feature allows to fold the

frameworksinordertooptimisethecarriage.Oncethestructureisinplace,itcanbeunfoldedandfilledwithvegetal

soilandrocks,reducingthesetuptime;cuttingsorrootedplantscanbeinsertedeveneasierthanfortraditionalsoil

bioengineeringstructures(seefollowingFigures).

WeshowsolutionsdevelopedbyEvintechS.r.l.(e.g.GabBiole,Palifi-grataFirenze,etc.)thatwehavetestedforstress

onlogsandjointsandthestabilityoftheindividualmodulesaccordingtotheEuropeanandItalianregulations.

In-situ experiments areongoing to test the application in comparisonwith traditional structures (i.e. live cribwalls,

gridwalls,palisades,log’n’rockweirs,etc.),andtoassessthepracticaladvantagederivedfromthemodularityofthe

solutionandtheadoptionofnon-lineardisposition(archingofconsolidationline,pilingofmodules).

References:

AA.VV. CNR (2007) – Istruzioni per la Progettazione, l’Esecuzione ed il Controllo delle Strutture in legno – CNR-DT

206/2007

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Cornelini,P.,Preti,F.(2005)–Elementidigeotecnicaapplicataall’I.N.:aspettigenerali,criterididimensionamentoe

verifichedistabilità,capitolo10delVol.2delManualediI.N.dellaRegioneLazio

Regione Lazio (2013) – Dimensionamento delle opere di ingegneria naturalistica – aspetti innovativi e verifiche

preliminari,Assessoratoperl'AmbienteDipartimentoAmbienteeProtezioneCivile

SBEE68–UseofLAPSUS_LSmodeltoinvestigatevegetationinfluenceoncatchmentslopestability–AcaseofstudyinLlanoBonito,CostaRicaRossiLMW,RapidelB,RoupsardO,VillatoroM,RoumetC,MaoZ,MetselaarK,SchoorlJM,ClaessensL,StokesA

INRA,UMRAMAP,34398,MontpellierCedex5,France,

Root-soil interactions provide several ecosystem services in terms of natural geo-engineering; among them, slope

stability enhancement by additional root cohesion is one of the most important and recognized. Upscaling the

processes of root-soil interactions in terms of additional root cohesion presents several issues due to the

heterogeneity of the root development and of the soil properties. This study aims to explore the potential of the

LAPSUS_LSmodeltoup-scaleandmodeltheeffectsofthevegetationonsoilstabilityatcatchmentlevel.Themodel

allowsmodification of catchment properties in aGIS environment (with particular attention to the additional root

cohesion)anddelivers(asanoutput)anerosionandsedimentationmapofshallowlandslides,otherthanthetotalm3

ofsoilmoved.Wesimulatedtwodifferentscenarios inacatchment inLlanoBonito,CostaRica,tounderstandhow

themodelreactstodifferentvegetationpatterns.Sinceagroforestryhasbeenproposedasamethodtoincreasethe

stabilityofslopingagriculturallandsweaimedtocompareanagroforestrysystemofcoffee(CoffeeArabica)andthe

treeErythrina(poppigeana),withacoffeemonoculture.Sensitivityanalyseswereperformedonalltheinputdatato

understand the importance of additional root cohesion for the model compared with soil characteristics, and its

suitability to investigate vegetation influence. Moreover, the model was further modified to include the biomass

surchargeofvegetation in thesimulation.The figurebelowprovidesanoverviewof thesteps taken in thepresent

researchinordertoassessthevalidityofthemodel.Resultsshowthatadditionalrootcohesionisakeyfactorforthe

model.However,shearplanedepthhastobecarefullyselectedtohavevalidoutputs.Atashearplanedepthof100

cm the catchmentwasoverall stable.At150 cmdepth, agroforestry slopes showedhigher stability comparedwith

monoculture (highly unstable). Biomass surcharge had no significant effect on slope stability. LAPSUS_LS seems

suitable to understand the influence of vegetation on landslide risk, however further calibration and validation is

required.More research could allow stakeholders to use themodel as a decision-making tool (e.g. planning a re-

vegetationapproachtoincreaseslopestability).

SBEE58–Quantifyingthestabilizingeffectofforestsonshallowlandslide-proneslopesusingSlideforNETM.Schwarz,LuukDorren

BernUniversityofAppliedSciences,Zollikofen,Switzerland

Shallow landslides canpose significant risks tohuman livelihoodsand infrastructurebydirectly impactingbuildings

andtrafficways.Inaddition,shallowlandslidesandsoillossintheupperpartofstreamcatchmentscanleadtohigh

sedimentyieldsdownstreamincreasingthedamageintensityoffloodsanddebrisflows.Thepresenceofforestshasa

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stabilizingeffectsof hillslope.Althoughhydrological effectsof vegetation still bedifficult toquantify, some studies

suggest that theseeffectsarenotdominant forhighquantityofcumulative rainfall (Pollenetal.,2004);moreover,

theseeffectsarehighlyheterogeneous inspaceandtime.So far, rootreinforcementmaybeconsidered locally the

main stabilizing effect due to vegetation. The actual degree of stabilization depends very much on the spatial

distribution of tree roots. The current practice of assessing the hazard posed by shallow landslides, as being

undertakenbymostnaturalhazardengineerstoday,rarelyaccountsforthestabilizingeffectofforests,nottheleast

because the quantification of the slope stabilizing effect of forests remains complicated without suitable and

accessibletools.Thispaperpresentsatoolwedeveloped,calledSlideForNET(www.slidefor.net),forquantifyingthe

stabilizingeffectofrootreinforcementonshallowlandslide-proneslopes,aswellassomerealcaseapplications.

The stability calculation in SlideforNET is based on a 3D force balance that assumes an elliptical shape of shallow

landslides.Thelandslidemassisconsideredperfectlyrigid,allowingsomeofthelateralforcestoactsimultaneously.

Additionalweightduetovegetationisconsideredinthecalculations.

Root reinforcement is implemented in thecalculationby considering1) the roots crossing theuppermarginof the

landslide (lateral root reinforcementalong thepotential tensioncrack)and2) the rootscrossing thebasal shearing

plane (basal root reinforcement). The latter is calculated using an exponentially decreasing cumulative density

function, approachingabasal root reinforcementof0 kPaat adepthof2m.Basedon the inputparameters stand

density,mean stem diameter at breast height (DBH) and species composition, themodel calculates theminimum

lateralrootreinforcementassumingameantreedistancebasedonatreedistributionfollowingaregulargrid.Recent

data of root distribution of themain alpine tree species (Spruce - Picea abies, Fir - Abies alba, and Beech - Fagus

sylvatica)allowtheattributionofarootreinforcementvalue(5,10,or15kN/m),basedonthemeantreedistance,

themeanstemdiameterandtreesspecies.Stiffeningoftheunstablesoilmantleisnotconsidered.

Agammaprobabilityfunctionisusedtodescribethefrequency-magnitudedistributionofpotentialshallowlandslide

volumes followingMalamudet al. (2004). The resultingnumberof unstable landslides is not related to a specified

eventmagnitudeorreturnperiod,itratherrepresentsthepartialprobabilitythatlandslideswithacertainareamay

occurunderfullysaturatedconditions.

In total, 10’000 potential shallow landslide calculations using combinations of the randomly generated values are

carried out.One of themain outputs is the “degree of protection”,which is the reduction of the total number of

landslidesduetothepresenceofforestexpressedinpercentage.

WetestedSlideforNETonthreeforestedsitesintheSwisspre-alpswhereshallowlandslidesoccurred(seeSchwarzet

al.,2013).On thesesites,wecompared the“present”conditionswith the“optimal” targetprofileaccording to the

swissnationalguidelinesforthemanagementofprotectionforests.

SlideforNETconfirmed that landslidesmightoccuron the threesites,even though thecalculatedprobabilityat the

Gantrischsiteisverylow.Accordingtotheresults,theprotectiveeffectattheSpisibachsiteiscurrentlyabsent,but

withanoptimalspeciescompositionthelandslideprobabilitywoulddecreaseby31%.Thisaccountsforallthreesites

(Schangnau38%;Gantrisch27%).Theresultsshowlateralrootreinforcementisespeciallyeffectiveforlandslideswith

releaseareasupto500m2.Detailedresultswillbepresentedanddiscussedinafullpaper.

Keywords:Shallowlandslides,protectionforest,SlideforNET,slopestability

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SBEE69–SuccessionofPlantCommunitiesinLandslideSitesRemediatedwithExoticPlantSpeciesG.-Z.M.Song,S.-W.Fan,S.-H.Lin,Y.-F.Chang

DepartmentofSoilandWaterConservation,NationalChungHsingUniversity,TaichungCity,Taiwan

Exoticplant speciesareoftenused toprotectexposedsoilon slopes fromerosion.Therearealwaysconcerns that

exotic species used in such kind of practices may raise the risk of species invasion and retard plant succession

afterwards.Inthepresentstudy,weasked:1)howlongcanexoticspeciesusedforremediationpersist;2)howlong

cannative treespeciescolonise remediatedsitesand3)do the remediationpracticeencourage thecolonisationof

invasivespecies?Ninelandslidesitesremediatedwithexoticspecies(mainlyPaspalumnotatum,Axonopusfissifolius,

LoliummultiflorumandCynodondactylon)weresampledintheNantouCounty,centralTaiwan.Theelevationofthese

sitesrangedfrom89mto2055mabovesealevel.Onetothree10mby10mplotswerelaidoutineachsite.Inthese

plots,diameteratbreastheight(DBH)andspeciesofeverytreewithDBH≥1cmwererecorded;coverageandspecies

ofherbaceousspeciesandtreespecieswithDBH<1cmwererecorded.Theninesiteswerefirstcensusedconducted

in2010(0.5yrto2yrsaftertheremediation)andrecensusedeighttimesfrom2010to2014.Exoticspeciesplantedin

theremediationvanishedwithin3yrs.Meanwhile,oursiteswerecolonisedbynativewoodyspecies(e.g.Macaranga

tanarius,Broussonetiapapyrifera,Boehmeriadensiflora,Alnusformosana)in3yrs.Although,insevensiteslocatedin

remoteareas,thecoverageofinvasivespeciesaccountedforagreatproportionoftotalcoverage(10%to70%)inthe

first1.5yrs,theircoveragedecreasedtolowerlevels(5%to30%)attheendofthisstudy.Thecoverageof invasive

species (e.g.Bidens pilosa var. apiifolia,Mikaniamicrantha) in two sites frequently disturbed by local peoplewas

raised to or kept at the level of more than 80% in 2014, indicating that the colonisation of invasive species is

encouraged by subsequent human disturbances rather than the use of exotic species in remediation. Our results

showedthatremediationwithexoticspeciescanbarelyretardsuccessionandencouragethecolonisationofinvasive

species.

SBEE61–AnopenaccessdatabaseofplantspeciessuitableforcontrollingsoilerosionandsubstratemassmovementJérômePerez,R.Condesalazar,AlexiaStokes

IRD,UMRAMAP,Montpellier,34000,France

The risk of shallow landslides and erosion has increased enormously over the last decade, often due to poor

management or a lack of understanding of basic soil instability processes. Although the planting of vegetation is

widelyacknowledgedasimprovingsoilconservationonslopes,howtoplantandmanageavegetatedslopeovertime

canbeproblematic.Correct identificationof themass-wastingprocessandsitecharacterization isnecessarybefore

choosingtheplantspeciesbestsuitedtoasite.Toaidthesitemanagerchoosethemostappropriatespecies,wehave

developed anopen access database ‘Stability,’ containing species sortedby their utility for retaining soil on slopes

subject to shallow landslides, wind and water erosion. The list of species was compiled from the literature and

suitabilityisbasedonecologicalattributes,shootandroottraits.Thedatabaseisopentoexpertswhocanaddnew

information via a website, whereas the general public can access the data freely: http://publish.plantnet-

project.org/project/stability_en

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SBEE70–Effectivenessofplantrootsincontrollingrillandgullyerosion:AcasestudyonvegetationcommunitiesonriverdikesW.Vannoppen,J.Poesen,S.DeBaets,M.Vanmaercke,P.Peeters,B.Vandevoorde4

DivisionofGeographyandTourism,KULeuven,Belgium

An important ecosystem service of plant roots is their potential to control concentrated flow erosion rates. The

objectivesofthisstudyare:i)toexploretheoveralltrendsinsoilerosionreductionasafunctionofrootdensity(RD,

kgm-3) and root lengthdensity (RLD, kmm-3)basedonameta-analysisof experimental data and ii) touse these

trends to assess the effectiveness of 5 dike vegetation communities in controlling soil erosion rates during

concentratedrunoff.Thelatterisofgreatimportanceaspredictedclimatechange,andtheassociatedsealevelrise,

poses an increased threat of flooding due towave overtopping events at sea and river dikes, possibly resulting in

erosionofthesedikes.

Thedecreaseinsoildetachmentratios(SDR;i.e.theratioofsoilerosionratesofaroot-permeatedsoilsampleanda

baresoilsample)asafunctionofRDandRLDcouldbebestdescribedbyaHillcurvemodel.Asalargescatterinthe

experimentaldataisobserved,uncertaintyrangeswerecalculatedusingaMonteCarloapproach.Theapplicationof

theresultingrelationshipbetweenRLDandSDRtotheselecteddikevegetationcommunitiesshowedthattherewere

largedifferencesintheerosion-reducingpotentialofthesevegetationcommunities.Thesecanbeattributedtolarge

differences inRLDdue to thepresenceorabsenceofU.dioicawhichhas thick rhizomes.Asa result, concentrated

flowerosionratesofthetopsoil(0-0.05m)arelikelytobereducedtoonly22-30%oftheerosionratesforroot-free

topsoils ifU.dioica (i.e.nettles) ispresentcompared to13-16%forvegetationcommunitieswithoutU.dioica.This

study illustratesthattheoverall trends insoilerosionreductionbasedonrootcharacteristicscanbeusedtoassess

thelikelyerosion-reducingeffectsofvegetationcommunities.

SBEE60–Assessingtheprotectivefunctionofaforestafterafireevent:acasestudyinVallis,SwitzerlandWerlenM,VerganiC,SchwarzM

BernUniversityofAppliedSciences

Forestsarewellknowntoprotectagainstnaturalhazardssuchas landslides,rockfallandfloods.Nevertheless, they

aredynamicecosystemswhichareexposed toa varietyofdisturbances suchaswindstorms, fires,barkbeetleand

pathogenoutbreaks.Catastrophicdisturbanceslikewindstormsandfiresusuallyremovelargeportionsofthecanopy,

starting a succession process which lead to a complete stand regeneration. Disturbances belong to the natural

dynamic of forests, however they are highly undesirable in the case where forest protect infrastructure or

settlements.Quantifying the decay and recovery of the protection effect of forests after disturbances is therefore

importanttoevaluaterisksandimplementappropriatemanagementtechniques,whenneeded.

ThisworkanalyzesthedynamicofaScotsPine(Pinussilvestris)protectionforestsnearVisp(Vallis)afterafireevent,

focusingonrootreinforcement,whichisthekeyfactorinpreventingshallowlandslides.Forestcover,rootdistribution

and rootmechanical propertiesweremeasured 4 years after the fire event, and the root reinforcement has been

quantified.Furthermore,thecontributionofnaturalregenerationhasbeenevaluated.

ResultsshowthattherootreinforcementofScotspinehasdeclinedmassivelyintheforestfirearea.Atadistanceof

1.5mfromthetreestemthereisareductionof60%comparedwiththelivestand.Withincreasingdistancefromthe

SBEE2016ABSTRACTS

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stem,thereductioninthereinforcementisevenbigger.Atadistanceof2.5metersitis12%andat3.5meters,only

5%oftheoriginalrootreinforcement.Thisdecreaseisduetothedecompositionofrootsandassociatedchangeinthe

mechanicalpropertiesofthewood.Thereinforcementofthedeadrootsintheforestareaisestimatedbetween0.36

kPaand2.64kPa.Thecontributionoftheemergingregenerationisestimatedonaverage0.01kPa.Overallthestand

providesareinforcementbetween0.37kPaand2.65kPa.

Fromtheresultsitcanbeconcludedthatthedyingrootscanstillprovideacertainrootreinforcement;however,the

contributionof rejuvenation is too little to compensate the continuously decreasing protective effect in the future

time.

Thetimeinwhichaforestcanreturnintheinitialstateplaysthereforeadecisiveroleforcontrastingtheformationof

landslides,whichafteraforestfirecanbetriggeredatlowerprecipitationevents.

Toupscaletheresultsatthestandscale,arootdistributionmodelhasbeencalibratedbothfordeadScotsPinetrees

andregenerationsaplings(birch,poplarandwillow).

TheresultsobtainedareimplementedinslopestabilityanalysisapplyingthetoolSlideforNetinordertocomparethe

protectiveeffectofvegetationbeforeandafterthedisturbance.

Thisworkcontributestoprovideafirstframeworktoevaluatetheefficiencyofprotectionforestsbeforeandaftera

catastrophicevent,inordertosupportriskevaluationandplanpossiblemanagementactions.

Animportantoutlookwouldbedevelopingaprotectiveeffectevaluatoinforthedifferentregenerationscenariosat

differenttimestepafterthedisturbance, inordertohavea longtermassessmentoftheprotectivefunctionofthe

forest.

SBEE62–In-situsheartestsofsoilrootsystemsR.KatzenbachandA.Werner

TechnischeUniversitätDarmstadt,InstituteandLaboratoryofGeotechnics,Darmstadt,Germany

Itiswidelyacceptedthattherootsystemofgrasses,shrubsortreeshaveagreatimportanceinslopestabilizationand

erosioncontrol.Themainbeneficialeffectsincludetherootreinforcement.Rootfibresincreasetheshearstrengthof

soil primarily by transferring shear stresses that develop in the soil matrix into tensile resistance in the fibres via

interface friction along the imbedded fibres. In addition anchored and embedded stems can act as buttress piles.

Furthermore the vegetation growing on slopes contributed to slope stability by soil moisture depletion from

interceptionandtranspiration.

The paper presents results of experimental studies in the laboratory and in-situ focused on the quantitative

determinationoftheroottensilestrengthandtheincreaseinsoilshearstrengthduetorootsystems.Theinfluenceof

rootreinforcementonshearstrengthisdeterminedbydirectsheartestsinthefieldandinthelaboratory.Thetensile

strength of rootswas determinedby testing root systems in the laboratorywith the new testing apparatus at the

InstituteandlaboratoryofGeotechnics.

Thefieldstudieswerecarriedoutusingourlargenewdesignedshearapparatustoidentifytheincreaseinsoilshear

strengthduetorootsystems.Intheresearchwefocusonsoilmaterialsconsistingoffine-grainedmaterial.Inorderto

quantifythecontributionofrootstosoilmechanicalproperties,directsheartestsonundisturbedsamplesofrootless

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soilandrootpermeatedsoil,respectively,werecarriedout.Fortheinvestigation,threeyearsbeforetestingthereare

plantedupto5birch(Betulapendula)andmaple(Acerplatanoides)saplingsinthetestingfield.Thesizeofthebox

measured 520 cm x 520 cmwith the height of 25 cm. Thenormal loadwas applied bymeans of steel-plates. The

horizontalshearforce,appliedbyahydraulicpress.Load(stress)anddisplacement(strain)wereplottedthroughout

thedurationofthetestprocedure.ThetestingmethodologyfollowedDIN18137.

After thecompletionofeachtest therootswereexcavatedandphotographsweretaken.Therootswerecollected

andthediametersoftherootsweremeasuredintheshearplanetodeterminethebiomassandrootarearatio(RAR).

Afterwards the relationship between the shear strength t and the shear displacement of the field shear tests are

carried out. The increase in the shear strength of the root permeated soil (birch roots) is identifiable; the shear

strengthofallfieldtestsisabovetheshearstrengthofrootlesssoils.

SBEE63–ExperimentalandFieldResearchonRootReinforcementandApplicationinRiverbankEcologicalProtectionZhangKunyong,CharkleyNaiFrederick,ShiJiangyong

KeyLaboratoryofMinistryofEducationforGeomechanicsandEmbankmentEngineering,Nanjing,China

Fieldinvestigation,laboratoryexperiments,sitetestsandfiniteelementnumericalanalysiswerecarriedouttostudy

theeffectofdifferentplantsappliedinpracticalriverbankecologicalprotectioninJiangsuProvince,China.

Typical existing ecological protections of riverbank in northern Jiangsu Province, China, were investigated. It was

foundthattherewillbedifferentprotectionseffectswhendifferentecologicalretainingstructureswith localplants

were applied in different areas. The applicability and limitations of ecological revetments were compared and

analyzedbasedonsiteinvestigation.Shearingtestsonplantrootwerecarriedoutbyusingimprovedtraditionaldirect

shearapparatus.Largescalefielddirectsheartestswerecarriedouttogetthefieldstrengthofdifferentplantroots.

Basedonbothabovetests,thereinforcementmechanismoftheplantrootonstrengthcharacteristicswasanalyzed.

Anequationtodescribetherootreinforcedsoilshearstrengthwaspresented,inwhichboththerootdiameterand

rootdistributiondirectionsweretakenascalculationparameters.Seriesexperiments,includingionconcentrationof

localriverbanksoil,corrosionresistance,salttoleranceanddurabilityofdifferentplants,werealsobeencarriedoutin

laboratory. Based on above research, reed and osier were suggested as the ecological protection plants in the

northernareaof Jiangsuprovince.Also, thecorrosion resistancegradeof the retainingwoodstakesand long-term

strengthweregiven.

Basedonallabovelaboratoryexperiments,sitetests,theoreticalresearchandsafetycalculation,mechanicalmodelof

plantrootsonsoil reinforcementeffectwasestablished.Theeffectofecologicalprotectionstructurewithdifferent

plant species, planting location, structure types and slope gradient was analyzed. Then the model was applied in

practical engineering.Different typesof ecological protectionswere constructed in thepractical testing sectionsof

riverbank. Numerical safety evaluation of the riverbank slopewith the consideration of root reinforcementmodel

werecomparedwithtraditionalmethod.Longterminfieldmeasurements,includingslopedeformationanderosionof

theslopeface,werecarriedouttoverifytheproposedtheoryandcalculation.

Keywords:rootreinforcement,ecologicalprotection,riverbankslope,mechanicalmodel,fieldapplication

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SBEE2016COMMITTEESOrganizingCommitteeT.C.T.HUBBLE UniversityofSydney,AustraliaC.PHILLIPS LandcareResearch,NewZealandA.STOKES INRA,FranceS.L.CLARKE UniversityofSydney,Australia

ScientificCommittee

G.BISCHETTI UniversityofMilan,ItalyW.CHEN NationalTaipeiUniversityofTechnology,TaiwanG.BATTISTACHIRICO UniversityofNaplesFedericoII,ItalyS.DEVKOTA FEED(P)Ltd.,NepalT.FOURCAUD CIRAD,FranceF.GRAF WSLInstituteforSnowandAvalancheResearchSLF,SwitzerlandT.C.T.HUBBLE UniversityofSydney,AustraliaK.LOADES JamesHuttonInstitute,UKZ.MAO IRSTEA,FranceS.B.MICKOVSKI GlasgowCaledonianUniversity,UKO.NORMANIZA UniversityofMalaya,MalaysiaJ.E.NORRIS CH2MHILLC.PHILLIPS LandcareResearch,NewZealandJ.POESEN LeuvenUniversity,BelgiumD.POLSTER PolsterEnvironmentalServicesLtd,CanadaF.PRETI UniversityofFlorence,ItalyP.RAYMOND TerraErosionControlLtd.,CanadaF.REY IRSTEA,FranceM.SCHWARZ BernUniversityofAppliedSciencesA.SIMON CARDNO-ENTRIX,USA

R.SOTIR RobbinB.Sotir&Associates,Inc.

A.STOKES INRA,FranceA.TARANTINO UniversityofStrathclyde,UK