Effects of Rubber-Tired Cable Skidder on Soil Compaction ...
Transcript of Effects of Rubber-Tired Cable Skidder on Soil Compaction ...
Originalscietificpaper–Izvorni znanstveni rad
Croat. j. for. eng. 34(2013)1 123
EffectsofRubber-TiredCableSkidder
onSoilCompactioninHyrcanianForest
BarisMajnounian,MegdadJourgholami
Abstract – Nacrtak
The use of skidders equipped with rubber tires is a well accepted practice for the extraction of timber from the forest, but the application also causes considerable environmental problems. The aim of the study was to evaluate the effects of different slope gradient, number of machine passes on skid trails and soil depth on soil compaction. The study was designed as an experi-ment with the factors including slope gradient, soil moisture, and soil depth on various skid trails and with different number of machine passes. The effects of four slope classes (flat, 10%, -10% and -20%), three soil depth classes (5, 15 and 25 cm), and different compaction levels based on various number of machine passes (0, 1, 5, 8, 10, 15, 20, 25 and 30) were evaluated. A Timberjack cable skidder was used and the study location was in the Kheyrud Educational and Research Forest located in the Hyrcanian forest in northern Iran. The increased number of machine passes increased soil bulk density, but the highest rate of compaction occurred after the initial few passes. Uphill skidding increases soil compaction more than downhill skidding. The increases in bulk density were still significant at the maximum sampling depth of 20–30 cm. Soil bulk densities at 5, 15 and 25 cm depth averaged 35, 22 and 17% higher than densi-ties of undisturbed soil.
Keywords: soil compaction, soil bulk density, rubber-tired cable skidder, Hyrcanian forest.
1. Introduction – UvodForestsoils,ingeneral,aresusceptibletocompac-
tionastheyareloosewithhighorganic-matter,andaregenerallylowinbulkdensity,highinporosity,andlow in strength (Froehlich et al. 1985;Kolkaa andSmidt2004).Theimpactofskiddingoperationsonfor-estsoilscanbedividedintothreemajorcategories:soilprofiledisturbance,soilcompactionandsoilpuddlingandrutting(Rabetal.2005).Whenamechanicalloadisappliedtothesoil,soil
particlesarerearrangedclosertogetherresultinginin-creasedbulkdensity(massperunitvolume)(Cullen1991;Eliasson2005;Graceetal.2006),reductionofthetotalporosityassociatedwithareductionofmacro-pores(GayosoandIroume1991;Gomezetal.2002;Aresetal.2005),increaseinsoilstrength;exceptforsoilwithlowbearingcapacities(Hornetal.1994),decreasedin-filtrationcapacity(Hornetal.1994,2004),decreasedgaseousexchangeandsoilaeration(Hornetal.1994),anincreaseinresistancetopenetration(Ampoorteretal.2007),decreaseinsaturatedhydraulicconductivity
(GreacenandSands1980;Hornetal.1994;Graceetal.2006),andincreasedmicroporeproportion(KolkaaandSmidt2004).Oneofthemajorimpactsofharvestingoperationsissoilprofiledisturbance.Soildisturbanceisusuallydefinedintermsofmixingand/orremovaloflitterandsoil,whichmaychangethephysical,chemicalorbiologicalpropertiesofsoil(Rabetal.2005).Depend-ingontheequipmentused,thesurfacesoilsarevari-ouslymixed,buriedorinverted.Duringtimberharvestingthedegreeofsoilcompac-
tiondependsonvariousfactorsincluding:siteandsoilcharacteristics(AdamsandFroehlich1984;Ampoorteretal.2007)suchassoiltexture(Froese2004;Rohandetal.2004),soilmoisture(Johnsonetal.2007),thenumberofmachinepasses(Eliasson2005;Šušnjaretal.2006;Ampoorteretal.2007;EliassonandWasterlund2007;Wangetal.2007)andharvestingsystem.Inaddition,themachinecharacteristicsaffectingthedegreeofsoilcompactionincludetypeofmachine(Šušnjaretal.2006;Wangetal.2007),massofvehicleandload(Rab1996;Saarilahti2002;Šušnjaretal.2006;Hornetal.2007),type,numberofwheelsandinflationpressureofthe
B.MajnounianandM.Jourgholami EffectsofRubber-TiredCableSkidderonSoilCompaction...(123–135)
124 Croat. j. for. eng. 34(2013)1
tires(Ziesak2006),amountofloggingslash(WronskiandMurphy1994;EliassonandWasterlund2007).Acoupleofstudiesreportedbyseveralresearchersshowthatoneofthecriticalfactorsaffectingthedegreeofsoilcompactionisthenumberofmachinepassesoveraspecificpoint.Thesestudiesshowthatmostcompac-tionoccursduringthefirsttenpassesofavehiclewiththemostoccurringinthefirstthreepasses.Subsequentpassesgenerallyhavelittleadditionaleffect(Ampoort-eretal.2007).Mostcompactionoccurredaftertheinitialfewpasses(MatangaranandKobayashi1999),butbulkdensityalsoincreasedsignificantlyaftermorethan3passes(GayosoandIroume1991;Eliasson2005;Elias-sonandWasterlund2007).MatangaranandKobayashi(1999)foundthatthebulkdensityincreasedmarkedlybythefirstandsecondpassofthetractor,butdidnotchangeafterthefifthpass.Fewstudieshavedocumentedslopegradientof
traileffects(longitudinalandtransversalslopeoftrail)ontheextentanddegreeofsoilcompactionanddis-turbance.Kragetal.(1986)showedthatduringtimberharvesting,slopesteepnesshadastrongereffectthanseasonofloggingonsoildisturbance.Understeepter-rainconditions,themachineslippedcontinuouslyandremainedinagivenplaceforalongerperiodoftime,puddlinganddraggingthesoil(GayosoandIroume1991).SidleandDrlica(1981)foundthattheslopedidnotsignificantlyaffectbulkdensity,buttheyconclud-edthatitcanbeanimportantfactorinthepotentiallevelofcompaction.Jamshidietal.(2008)foundthattherewasnodetectabledifferenceincompactionbe-tweenmachineskiddingonflattrailsandtrailswithlongitudinalgradientortransversalslope.Compactedlayersareoftenfoundatdifferentsoildepths.How-ever,thedeeperlayersofmanysoilsarecompactedfurtherafterafewpasses.Thevaluesofthesoilbulkdensitymostlydependonthequantityoforganicmat-ter.Inthesurfacehorizons,thesoilbulkdensityislow,andaswiththeincreaseofdepth,organicmatterisrapidlydecreased,thebulkdensityincreasesinsub-soil(FroehlichandMcNabb1984).Increasesinorgan-icmatterreducesoilcompactibility(Kozlowski1999).Astrongincreaseinbulkdensityismostdistinctintheupper20cmofthesoil,sincetheexertedpressureismaximalatthesoilsurfaceanddeclineswithincreas-ingdepthasthetotalpressureisspreadoutoveranenlargingarea(GentandMorris1986;Ampoorteretal.2007).Johnsonetal.(2007)notedthatsoilcompac-tionwasgenerallylimitedtoskidtrailsandtopsoillayers(<30cm).EliassonandWasterlund(2007)re-portedthatanincreasednumberofmachinepassagesincreasedsoildrydensityintheupper20cm.TheHyrcanianmountainous forest innorthern
Iranisrichinbiologicaldiversity,withendemicand
endangeredspecies,andadiverserangeofeconomicandsocialconditions.IntheHyrcanianforest,afewstudieshavebeencarriedoutabouttheeffectsofforestoperationsonsoilcompactionandbulkdensity.Jam-shidietal.(2008)measuredthechangesinbulkden-sityinthetop10cmofsoilfollowingmachineandanimalskiddingintheHyrcanianforest.Theyfoundthattheaveragesoilbulkdensityinthetracksofma-chineskidtrailswassignificantlygreaterthanthesoildensity outside the tracks, but the increase in bulk densitywasnotsignificantontheanimaltrails.Theextentoftheseveredisturbancefromground-
basedharvestingsystemsvariesdependingonslopeandsteepterrain,althoughtheeffectsofslopeonsoildisturbanceandbulkdensityhavereceivedlessatten-tion.Thespecificobjectiveswereto:quantifytheex-tentoftrailareaandwinchingline(disturbancearea)throughouttheharvestunit,tocharacterizeandestab-lishthethresholdlevelsforthemachinetrafficwithrespecttobulkdensityandslopegradientordirectionofskiddingforthreedifferentsoildepths.
2. Materials and methods – Materijal i metode
2.1 Study site – Područje istraživanjaAbout65%oftheHyrcanianforestsarelocatedin
mountainousareaswithterrainslopeofmorethan27%(Fig.1),whereforestlandsarenotreadilyacces-
Fig. 1 Proportion of the Hyrcanian forest area based on terrain slopeSlika 1. Udio nagiba terena šumskih zemljišta Hirkanijske šume (Golestan)
EffectsofRubber-TiredCableSkidderonSoilCompaction...(123–135) B.MajnounianandM.Jourgholami
Croat. j. for. eng. 34(2013)1 125
siblewith ground-based logging equipments. Thecableyardingtechnologiesarestillundevelopedinthisforestarea.TheresearchwascarriedoutincompartmentNo.
220,whichislocatedinNamkhanehDistrictwithinKheyrudEducationalandResearchForestintheHy-rcanianforestofnorthernIran(Fig.2).Thealtituderangesfrom1000to1135mandtheforestliesonasouthwesternaspect.Theaveragerainfallrangesfrom1420to1530mm/year,withtheheaviestprecipitationoccurringinthesummerandfall.Theaveragedailytemperaturerangesfromafewdegreesbelow0°C in December, January,andFebruary,andup to+25°C duringthesummer.Thisareaisdominatedbynaturalforestscontainingnativemixeddeciduoustreespeciessuch as Fagus orientalis Lipsky, Carpinus betulus L.,Acer velutinum Boiss.andAlnus subcordata.Themanage-mentmethodismixedun-evenagedhighforestwithsingleandgroupselectivecuttingregime.Thesoilofthestudysiteisclassifiedasabrownforestsoil(Alfi-
sols)andwell-drained.Thetextureofthesoilrangesfromsiltloamtoloamy.Treestoberemovedwerefelled,limbedandtopped
motor-manually.Felled treeswerebuckedandpro-cessedwith chainsaws into logs, sawn-lumber andpulpwood.Thelogsof5–15meterlengthwereextract-edbyrubber-tiredskidderstotheroadsidelandings.Thefuelwoodwasextractedbymules.Also,insteepterrain that could not be reached by skidders, logs were processedtosawn-lumberandthenhauledbymules.Animportantstrategyistolimittrafficondesignatedskid trails, hence, landings and skid trails were clearly flaggedonthegroundbeforeharvesting.Theintensionwas to require the skidder to stay on the skid trail and winchlogsonthetrail.Downhillanduphillskiddingtothelandingwasplannedwithoutanyexcavationandtheskiddingoperationsweredoneonnaturalground.Theextractiondistancestotheroadsidelandingwas780m.Theskidtrailsloperangesfrom0to35%.Table1presentssomecharacteristicsofthestudysite.
Fig. 2 Location of study site within the Hyrcanian ForestSlika 2. Područje istraživanja
Table 1 Characteristics of the study siteTablica 1. Značajke istraživanoga područja
Area, ha
Površina, ha
Tree per ha
Broj stabala po ha
Volume, m3/ha
Obujam, m3/ha
Total removed trees
Ukupno posječeno stabala
Total volume of removed trees, m3
Ukupni drvni obujam, m3
DBH of removed trees, cm
Raspon prsnih promjera posječenih stabala, cm
17 173 504270
(10 tree/ha – 10 stabala/ha)872.3 (32 m3/ha) 20–135
B.MajnounianandM.Jourgholami EffectsofRubber-TiredCableSkidderonSoilCompaction...(123–135)
126 Croat. j. for. eng. 34(2013)1
2.2 Experimental design and data collection Plan istraživanjaFellingofmarkedtreeswascarriedoutinMarch
andskiddingoperationsweredoneinAugust2008.Atthetimeofharvesting,weatherconditionswereverydryandwarmformorethan5weeksandtheseconditionsremainedconstantduringskiddingopera-tions.Fig.3presentsthe4WDTimberjack450Crub-ber-tiredskidderusedinthestudy.Thismachineisnormally an articulated, four-wheel-drive vehicleweighing10.3ton(55%onthefrontand45%ontherearaxle)withenginepowerof177hp(132kW)andenginemodelof6BTA5.9.Itisequippedwithabladeforlightpushingofobstaclesandstackingoflogs.Theskidderwasfittedwith24.5–32tiresinflatedto220kPaon both front and rear axles, and it had a ground clear-anceofapproximately0.6mwithoverallwidthof3.1m.Timberbunchingwascarriedoutbythewinchin-stalledintherearpartoftheskidderfromthestumpto the skidder and one end of the round wood was draggedontheground.Inthestudyareas,theaverageloggedvolumeineachpasswas3.5cubicmeters(1and3logs,respectively).Twelvesamplingtransectswereselectedatdiffer-
entslopegradientsalongthedesignatedskidtrailforbulkdensitymeasurements(Fig.4).Organichorizonswereremovedfromthesoilsurfacepriortodensitymeasurements,sothatdepthreadingswerereferencedtothemineralsoilsurface.Inordertoensurethatthemeasurementsweremadeinthesameplaceafteracertainnumberofpasses,wehaveputthepaintedsticksinthecenterofskidtrails.Thepaintedsticksindicatedthecentersoftheexperimentalskidtrailsattheskidtrial,sothatthemachineswouldfollowthe
sametracksatsubsequentpasses.Beforeskidding,fourslopegradientswereestablishedintheskidtrailwith3replicationsindisturbedareasat0–10cmsoilprofiledepth,andthedifferentlevelsofcompactionwereappliedbyvaryingthelevelsofmachinetraffic:0(undisturbed),1,5,8,10,15,20,25and30machinepasses.Apassimpliesadrivebackandforththese-lectedtrail.Fourslopegradientsofskidtrailwere0(flattrail),10%,–10%and–20%.Also,priortoanyskiddingoperationsandafter20machinepasses,bulkdensitywasmeasuredatthisfourslopegradienttrail(flattrail,10%,–10%and–20%)atthe5cm,15cmand25cmsoilprofiledepthsinwheelrut(AandB)andcontrolsamplepoint(Fig.4)ontheadjacentskidtrail
Fig. 3 Timberjack skidder, equipped with rubber-tires while extract-ing timberSlika 3. Skider Timberjack prilikom privlačenja drva
Fig. 4 Sketch of study layout for soil samplingSlika 4. Shema rada za uzimanje uzoraka tla
EffectsofRubber-TiredCableSkidderonSoilCompaction...(123–135) B.MajnounianandM.Jourgholami
Croat. j. for. eng. 34(2013)1 127
(C).Thesoilsamplecoreswereobtainedfromthelay-ersofthemineralsoilusingathinwalledsteelcylin-der,40mmlongand56mmindiameter,insertedintothesoilbyahammer-drivendevice.Afterextractingthesteelcylinderfromthesoilwithminimaldistur-bance to thecontents, thesoil coreswere trimmedflushwiththecylinderendandextrudedintoaplasticbagfortransportingittothelaboratory.Sampleswereweighed on the day they were collected and again af-terovendryingat105°Cfor24htodeterminewatercontentandbulkdensity.Inordertodeterminetheextentofdisturbancefrom
skidderoperations,disturbedwidthsweremeasuredat25mintervalsalongtheskidtrails.Skidtrailsoildisturbancewasclassedas:A-horizonpuddledandmixedwithforestfloororganicdebris,andsomeA-horizonremovedandtherestmixedwithB-horizon.Alsolandingareasweremeasuredinthecompartment.Log winching, however, cause the excavation of the line betweenstumpsnearthevehicle,hence,fordetermin-ingthisdisplacement,totallengthandwidthofwinch-inglinesinbothsidesoftrailsweremeasured.
2.3 Statistical analysis – Statistička obrada podatakaTheexperimentaldesignwasafactorialarrange-
mentoftreatmentsconductedinacompletelyran-domizeddesign.Generallinearmodeling(GLM)wasappliedtorelatebulkdensityandrutdepthtoma-chinepasses,slopegradient,anddepthinrelationtotheskidtrails.Post-hoccomparisonofmeanswasper-
formedusingDuncan’smultipledesigns tomean-basedgroupingwitha95%confidencelevel.AnalysisofvarianceofthedatawasconductedinSPSS(release15.0)toidentifydifferencesbetweenbulkdensityval-uesoffourslopegradientsinskidtrails.TreatmenteffectswereconsideredsignificantifP<0.05.Soilbulkdensitybeforeandafterskiddingoperationswascom-paredusingindependentsamplest-test.Also,one-wayANOVAwasperformed.
3. Results – Rezultati
3.1 Soil disturbance – Oštećenje tlaA detailed survey of the harvested unit following
extractionwithacableskidderindicatedthat5.8%ofthetotalarea(17ha)wascoveredwithskidtrailsandanadditional0.8%oftheunitwasoccupiedbythelanding(Table2).In this study,ground-basedwinchingof timber
fromthefellingsitetotheskidderhadsubstantialef-fectonsoildisplacementthatoccupied0.9%ofthetotalarea.Withthewholeloadlyingontheground,duringwinchingitremovedandpushedalayerofsoilinfrontofitself.Finally,inthisstudy7.5%ofthehar-vestingtotalareawasdisturbedandcompacted.Thedisturbancewidthofthetrailwassignificantlyinflu-encedbytransversalslopegradientsoftrails.There-fore,thehighertransversalslope,thewideristhetrailwidth.Therewerethreemainskidtrailsintheharvestareawithatotallengthof1971meters.Theaverage
Table 2 Compartment disturbance area due to rubber-tired skidder operationTablica 2. Oštećenje tla nastalo pri radu skidera
Factor
Mjesto
Trail length, m
Duljina vlake, m
Trail average width, m
Prosječna širina vlake, m
Disturbed area, m2
Oštećena površina tla, m2
Landing area, m2
Pomoćno stovarište, m2
Winching line, m
Duljina privitlavanja, m
Line width, m
Širina traga privitlavanja, m
Winching disturbed area, m2
Površina tla oštećena skupljanjem drva, m2
Total disturbed area, m2
Ukupno oštećena površina tla, m2
Trail 1
Vlaka 1324 4.8 1555.2 1150 241 0.32 77.12 –
Trail 2
Vlaka 21387 5.1 7073.7 – 3752 0.34 1275.68 –
Trail 3
Vlaka 3260 4.95 1287 180 380 0.29 110.2 –
Total area
Uk. površina1971 – 9916 1330 4373 – 1463 12709
Area, %
Površina, %– – 5.8 0. 8 – – 0.9 7.5
B.MajnounianandM.Jourgholami EffectsofRubber-TiredCableSkidderonSoilCompaction...(123–135)
128 Croat. j. for. eng. 34(2013)1
was5meters,andsooccupied5.8%ofthetotalarea.4373metersofwinchlinedisturbancewasrecordedwithanaveragewidthof0.315metersforatotalof0.9%ofthearea.
3.2Soilcompaction:influenceofslopesandmachine passes – Zbijanje tla: utjecaj nagiba terena i broja prolazaka vozilaTable3showstheanalysisofthesoilbulkdensity
datainfluencedbymachinepassesandslopegradient
forthecableskidder.Theresultsshowedthatmachinepassesandslopegradient,andtheinteractioneffectsofmachinepasses×slopegradientwereallsignificantvariables(P<0.05).Theindependentsamplest-testindicatedthatskid-
dinghadastatisticallysignificanteffectonthebulkdensityofsoilontrailsbeforeandaftermachinepassesineachtrailwithdifferentslopegradientsandbyinde-pendentsamplest-testandDuncan’stest(b).Thevaluesaremean.Differentletterswithineachslopetreatmentshowsignificantdifferences(P<0.05)(Fig.5).Theresultsshowthatbulkdensitysignificantly
increasedasthenumberofmachinepassesincreased(Fig.6).Regardlessoftheslopegradient,thedegreeandlevelofcompactiondifferedamongtrailslopeus-ingDuncan’smultiplerangetest(Fig.7andTable4).InTable4,foreachsoilintervalmeansarecomparedagainsteachotherafterANOVAusingDuncan’stest.Valuesaremean.Thedifferencebetweenvaluesinacolumnfollowedbydifferentsuperscriptsissignifi-cant at P<0.05.Intheotherhand,generally,trailswithfourslopes
showasimilartrendofincreasingsoilbulkdensitywithincreasingamountsofmachinepasses.Inflattrail,thebulkdensityinthetop0–10cmofsoil(1.06g/cm3)in-creasedby5%after1pass,19%after5passes,25%after8passes,31%after15machinepasses.Intrailwitha10%slopeoruphillskidding,thesoilbulkdensityin-
Table 3 Analysis of variance (ANOVA) for the effect of number of machine passes (NP) and slope gradient (SG) on bulk density in 0–10 cm soil depthTablica 3. Analiza varijance za prolazak vozila (NP) i nagib terena (SG) na dubini tla do 10 cm
Source
Izvor podataka
Sum of Square
Zbroj kvadrata
df
Mean Square
Srednja kvadratna vrijednost
F-value
F vrijednost
P-value
P vrijednost
NP 1.77 8 0.221 829.34 0.00
SG 0.17 3 0.058 216.36 0.00
NP × GS 0.06 24 0.003 9.67 0.00
Fig. 5 Average bulk density (a) and its relative changes before and after skidding in each slope gradient of the trail and by independent samples t-test and Duncan’s test (b)Slika 5. Prosječne vrijednosti (a) i relativne promjene gustoće tla nakon privlačenja drva (b)
Fig. 6 Relationship between the increase of bulk density (%) and machine passesSlika 6. Odnos povećanja u gustoći tla (%) ovisno o prolasku vozila
EffectsofRubber-TiredCableSkidderonSoilCompaction...(123–135) B.MajnounianandM.Jourgholami
Croat. j. for. eng. 34(2013)1 129
creasedby19%after1pass,43%after5passes.Subse-quentincreaseofthenumberofpasses(upto30turns)didnotincreasethebulkdensitysignificantly.Highlevelofincreaseinbulkdensityoccurredafter5ma-chinepassesandadditionalincreaseofpassesdidnotincreasethebulkdensitysignificantly.Intheareawith-10%,bulkdensityincreasedby9%after1pass,25%
after5passes,34%after8turnsandintrailwith-20%slope,by9%after1pass,22%after5passes,29%after8turnsand34%after10passes.Inflattrail,thehighestrateof compaction, asbulkdensity increased, tookplaceduringthefirst15passesby1.37g/cm3.Intrailwith10%slopegradient,incontrast,highincreasewasobservedinbulkdensity(1.44g/cm3)anditoccurred
Fig. 7 Relationship between the increase of bulk density and machine passes on different slope gradientsSlika 7. Odnos povećanja u gustoći tla s prolaskom vozila na vlakama različitih nagiba
B.MajnounianandM.Jourgholami EffectsofRubber-TiredCableSkidderonSoilCompaction...(123–135)
130 Croat. j. for. eng. 34(2013)1
after5machinepasses.Also,indownhillskiddingwith–10%and–20%,bulkdensitieswereincreasedsignifi-cantlyafter8and10machinepasses,respectively.Then,soilbulkdensityfor–10%and–20%was1.41and1.41g/cm3,respectively.Bulkdensityinthe10%trailshowedthehighestvalueincomparisonwithotherslopegradientsofthetrail(Fig.5).Skiddingoperationsalongflattrailhadthelowestcompaction(Duncan’s).
3.3Soilcompaction:influenceofslopesandsoildepths – Zbijanje tla: utjecaj nagiba terena i dubine tlaTable5showstheanalysesofthesoilbulkdensity
dataas influencedbyposition, slopegradientanddepthafter20machinepasses.Theresultsshowedthatposition,depth,slopegradient,andtheinteractionef-fectsofposition×slopegradientandposition×depthwereallsignificantvariables(P<0.05).GeneralLinear
Model (GLM) indicated twosignificant interactionterms,andnamelyposition×slopegradient(p<0.01)andposition×depth(p<0.01).Itcanbenoticedthatbulkdensityvaluesofcontrolsamplepoints(nopass)infourslopegradientsareclearlylessthancompactedvalues.Theinteractionbetweenpositionanddepthwasalsosignificant.Averagepre-harvestbulkdensitiesforthreesoil
depthclasses,0–10cm,10–20cm,and20–30cmwere1.06g/cm3,1.27g/cm3,and1.42g/cm3,respectively.After20machinepasses,bulkdensity increased indepthundertheskidtrailsinallslopegradientsoftrails,butthemajorincreaseoccurredinthetopofthesoilprofileat0–10cm.Inflattrail,bulkdensityin-creasedby30%in0–10cmdepth,by20%in10–20cm,andby17.5%in20–30cm,after20machinespasses.Intrailswitha10%slope,theincreaseinbulkdensityforalldepthswassignificantlyhigherascompared
Table 4 Mean bulk density values (± standard deviation) as influenced by machine passes and slope gradientTablica 4. Srednje vrijednosti gustoće tla (± vrijednost standardne devijacije) pod utjecajem prolazaka vozila i nagiba terena (SG)
SG (%)Number of machine passes – Broj prolazaka vozila
0 1 5 8 10 15 20 25 30
-10 1.08±0.01a* 1.17±0.01b 1.33±0.01b 1.42±0.02b 1.42±0.01b 1.43±0.01b 1.43±0.02b 1.44±0.02b 1.44±0.02b
-20 1.05±0.03ab 1.14±0.01c 1.27±0.02c 1.34±0.01c 1.39±0.03b 1.39±0.02c 1.4±0.01c 1.4±0.02c 1.41±0.01c
0 1.06±0.03ab 1.11±0.01d 1.25±0.02c 1.31±0.02c 1.34±0.02c 1.37±0.02c 1.38±0.01c 1.39±0.01c 1.39±0.01c
10 1.03±0.01b 1.22±0.01a 1.46±0.02a 1.46±0.02a 1.47±0.01a 1.47±0.03a 1.47±0.01a 1.48±0.01a 1.48±0.01a
Table 5 Analysis of variance (ANOVA) for the effect of sample position, slope gradient, and depth on bulk density in skid trialsTablica 5. Analiza varijance (ANOVA) podataka nagiba terena, dubine tla, gustoće tla i mjesta uzimanja uzoraka na traktorskim vlakama
Source
Izvor podataka
Sum of Square
Zbroj kvadratadf
Mean Square
Srednja kvadratna vrijednost
F-value
F vrijednost
P-value
P vrijednost
Slope – Nagib terena 0.012 3 0.004 3.78 0.02
Position – Položaj 1.611 1 1.611 1528 0.00
Depth – Dubina tla 1.035 2 0.518 491 0.00
Slope * Position
Nagib terena * Položaj0.021 3 0.007 6.59 0.00
Slope * Depth
Nagib terena * Dubina tla0.003 6 0.001 0.48 0.82
Position * Depth
Položaj * Dubina tla0.046 2 0.023 21.7 0.00
Slope * Position * Depth
Nagib terena * Položaj * Dubina tla0.001 6 0.00 0.21 0.97
EffectsofRubber-TiredCableSkidderonSoilCompaction...(123–135) B.MajnounianandM.Jourgholami
Croat. j. for. eng. 34(2013)1 131
withthoseobservedintrailswith–10%,–20%slope,andflattrail.Fig.8showshowtherelativechangeinbulkdensityvariedwithslopetrailinsoildepth.Intrailwith10%slope,bulkdensityincreasedby42%in0–10cmdepth,by28%in10–20cm,andby20%in20–30cm,after20machinepasses.Theindependentsamplest-test indicated that skidding had a statisti-callysignificanteffectonthesoilbulkdensityontrailsbeforeandaftervehiclepassesinsoildepth(p<0.05).Deeperinthesoilprofile,differencesbetweencontroland the treatments in four slope gradient becamesmaller.Thehighestlevelofincreaseinbulkdensitywasfoundin the trailwith10%slopegradientbe-tweencontrolandthetreatments.Forthesoilbulkdensitysamplesinfourslopegra-
dient,one-wayanalysisofvariance (ANOVA)andDuncan’stestwereusedtoseeifthereweresignificantdifferences(P<0.05)betweenthesoildepths.Inflattrailbeforeandafterskidding,bulkdensityincreasedsignificantlyinalldepths(Fig.9),buttherewerenosignificantdifferencesbetweensoildepthsat10–20cmand20–30cmintrailswithuphill(10%)anddownhill(–10%and–20%)slopegradient.Withrespecttothebulkdensityvaluesfordifferenttrails,smallervaluesweregenerallyobservedcomparedwithuphillanddownhillskiddingforflattrail.However,apeakcanalsobeseeninthedepthintervalof20–30cm.Also,10%trailresultedinthehighestbulkdensityvaluesforalldepths,whileflattrailshowedthesmallestde-greeofcompaction.
4. Discussion – Rasprava
4.1 Soil disturbance – Oštećenje tlaOncethesamplingmethodwasestablished,the
soil disturbance survey was both quick and easy to complete.Inthisforestwhereskiddingiscommon,theskidtrailpatternisdistributedunevenlybecauseofterrainsteepness.Usingadifferentsamplingmethodin this situation did not result in an exactly accurate surveyandhadmanyoverestimations.Comparedtootherstudies(FroehlichandMcNabb1984;Rabetal.2005;Šušnjaretal.2006),soildisturbanceinthisstudyoccupiedlessthan8percents.ThisagreedwithElias-son(2005)whofoundthatsoildisturbancewillbeaf-fectedbyseveralfactorssuchaswheelslip,vibrationandnumberofvehiclepasses.
4.2Soilcompaction:influenceofslopesandmachine passes – Zbijanje tla: utjecaj nagiba terena i prolaska vozilaTheresultsshowthattheaveragebulkdensitysig-
nificantlyincreasedaftertheoperationofrubber-tiredskidders.However, indifferentslopegradientper-centages, the increased bulk densities were statisti-callydifferent.Theresultsofmoststudieswerecon-sistent with our results (Sidle and Drlica 1981;FroehlichandMcNabb1984;GayosoandIroume1991;Eliasson2005;Šušnjaretal.2006;Ampoorteretal.2007;EliassonandWasterlund2007;Hornetal.2007;Jamshidietal.2008).Also,Hornetal.(2007)showedthateachstressappliedatthesoilsurfaceisalwaystransmittedthree-dimensionallyandcausesnotonlysoilcompactionbutalsosheareffects.Theresultsshowthatbulkdensitysignificantly
increasedwiththeincreaseofvehiclepasses.Ingen-eral,trailswithfourslopesshowasimilartrendofincreasingsoilbulkdensitywiththeincreasingnum-berofvehiclepasses.Formosttreatments,thehighestrates of increase in bulk density were achieved in the first5to15vehiclepasses.Beyond15vehiclepasses,therewasusuallyverylittleincreaseinbulkdensity(MatangaranandKobayashi1999).Intheflattrail,theskidderoperatorusedthewholewidthoftheroadinsteadoftravelinginthesamewheeltracks.Impactsofthefrequencyofvehiclepassesonsoilcompactionshowedsimilarresultsinmanyresearches(SidleandDrlica1981;GayosoandIroume1991;Ampoorteretal.2007;Jamshidietal.2008).ThisagreedwithWangetal.(2007)andHornetal.(2007)whobothclaimedthatsubsequentvehiclepassesincreasedthesoilcom-pactionatalesserextentuntilthereislittleornomorecompactionassociatedwithfurthervehiclepasses.
Fig. 8 Average decrease in bulk density with soil depth on skid trails of four slope gradientsSlika 8. Prosječno smanjenje gustoće na različitoj dubini tla
B.MajnounianandM.Jourgholami EffectsofRubber-TiredCableSkidderonSoilCompaction...(123–135)
132 Croat. j. for. eng. 34(2013)1
Inthisstudy,flattrailshadthelowestbulkdensity,thetrailswith-10%and-20%slopegradient(downhillskidding)hadintermediatebulkdensityandthetrailswith10%slopegradient(uphill)hadthehighestcom-paction.Thisresultcanbeexplainedbasedontheun-evenloaddistributionbetweenthedownhillandup-hilltiresoftheskidder(Jamshidietal.2008).Anotherreasonforlowerbulkdensityatthedownslopetrack
Fig. 9 Mean bulk density depending on different sampling placesSlika 9. Srednje vrijednosti gustoće tla ovisno o mjestu uzimanja uzorka
mightbethedraggingofthelogsonorclosetothistrack.Draggedbehindtheskidder,thelogsandespe-ciallythelogheadsmighthaverippedandloosenedupthesurfaceofthehighlycompacteddownslopewheeltrack(Jamshidietal.2008).However,GayosoandIroume(1991)statedthatthismaybeaconse-quenceof theproblemthat theskiddermight facewhenlogginginsteepterrains.Undertheseconditions
EffectsofRubber-TiredCableSkidderonSoilCompaction...(123–135) B.MajnounianandM.Jourgholami
Croat. j. for. eng. 34(2013)1 133
thevehicleslippedcontinuouslyandremainedinagivenplaceforalongerperiodoftime,puddlinganddragging the soil. In uphill skidding, rubber tiresslippedonsurfacesoil,thenthiswheelslippage,thevibrationappliedandshearstrengthcausedtheexpo-sureofmineralsubsoil,whichhashigherdensitythansurfacelayer.Also,highersoilcompactionintheup-hillskiddingcanbeexplainedbythehigherloadoftheskidderrearaxle.Intheotherhand,uphillskid-dingresultedinseverdisturbanceandcompactionininitialvehiclepass,howeverbulkdensityinthiscondi-tionhadthehighestamountincomparisontodown-hillskiddingandflatskidtrail.Also,Jamshidietal.(2008)foundthattherewasnodetectabledifferenceincompactionbetweenvehicleskiddingonflattrailsandtrailswithlongitudinalgradientortransversalslope.Theyconcludedthatthedifferentsiteconditionsandskiddingfrequenciesmighthaveaffectedtheimpactsofthedifferentgradients/slopes.
4.3Soilcompaction:influenceofslopesandsoildepths – Zbijanje tla: utjecaj nagiba terena i dubine tlaTheresultsshowedthataveragepre-harvestbulk
densities significantly increased as soil depth in-creasedforallslopegradients.Thewheelortrackslipdirectlyaffectedthesoilstructureandalteredphysicalsoilpropertiesdowntodeeperdepths.Intheotherhand, the values of the undisturbed soil bulk density mostlydependsonthequantityoforganicmatter,andincreasingsoildepth;theorganicmatterrapidlyde-creases,andthebulkdensityincreasesinsubsoil.Intheuppersoil,biologicalactivity(rootsandanimals)can act to reduce resistance and soil bulk density while atlowerdepthssoiltexture,gravelcontentandstruc-turemayincreasesoilresistanceandsoilbulkdensity(GreacenandSands1980;AdamsandFroehlich1984;Froese2004;Johnsonetal.2007).Inthisstudy,withincreasing soildepth the compaction level also in-creased,which is in agreementwith the results ofotherresearchers(GreacenandSands1980;SidleandDrlica1981;GentandMorris1986;GayosoandIroume1991;Aresetal.2005;EliassonandWasterlund2007;Johnsonetal.2007).Theresultsshowthatdeeperinthesoilprofile,differencesbetweencontrolandthetreatmentsinfourslopegradientbecamesmaller.Thehighest level of increase in bulk density was found in thetrailwith10%slopegradient(uphill)betweencon-trolandthetreatments.Inflattrail,bulkdensityin-creasedsignificantlyinalldepths.Thisisrelatedtotheratherhomogeneousweightdistributionoftheskid-deronflatskidtrails.Compactioneffectismostdis-tinctintheupper20cmofthesoil,sincetheexertedpressureismaximalatthesoilsurfaceanddeclines
withincreasingdepthasthetotalpressureisspreadoutoveranenlargingarea.Thus,anincreasegener-allyoccursespeciallyintheuppersoillayers(GreacenandSands1980).Itcouldalsobesuggestedthatthebearingcapacityofthesoil(maximumloadwithoutsoilstructurefailure)growswithincreasingbulkden-sity.Inthiswaythesurfacelayerisprotectedagainstfurthercompactionwhentraffic iscontinued(Am-poorteretal.2007).
5. Conclusion – ZaključakAccordingtoourfindings, itmaybeconcluded
thatthehighestrateofcompactionoccurredaftertheinitialfewpassesandreducingthenumberoftripsmadeoverthesametrailhadnoeffectinreducingsoilcompaction. In theotherhand, subsequentvehiclepasseswillresultindiminishingextrasoilcompaction.Hence,evenonepassisalreadysufficienttoinduceastrongincreaseinbulkdensity.So,skiddingopera-tionsshouldbelimitedtopre-plannedskidtrails,be-causevehicletrafficawayfromskidtrailscansignifi-cantlyaffecttheincreasingofthesoilbulkdensity.Theresultsofthisresearchconfirmedthatpreplanningofskid trails and directional felling will reduce ground disturbance.Slopegradienthasasignificanteffectonsoilcompaction.Basedontheresults,itcanbecon-cludedthatuphillslopegradientsontrailsshouldbeaslowaspossible,particularlywhenvehiclesaretrav-eling loaded.The studyshowed that the skid trailslopeandvehiclepasseshadasignificanteffectonsoilcompaction.Severecompactionofsoiladverselyaf-fectsthegrowthofplantsbyacombinationofphysicalsoil changesandplantphysiologicaldysfunctions.Skiddingoperationsshouldbeplannedwhensoilcon-ditionsaredrysoastominimizesoilcompaction,butifskiddingmustbedoneunderwetconditions,theoperationsshouldbestoppedwhenthevehicletrafficcreatesseversoilcompaction.Thedistancebetweenthesetrailsmustdependonthelengthofthefelledtreeandmayrangebetween50and70mdistanceinordertoreducethewinchingdistance.Theimpactoffellingoflargetreesisanothersourceofcompactionbutthisaspecthasnotbeenstudiedinthisresearch.
Acknowledgements – ZahvalaThispaperisoneoftheresultsofaresearchproject
thatwascarriedoutintheperiod2010–2012intheHyrcanianforestinnorthernIran.TheauthorswouldliketoacknowledgethefinancialsupportofIranianNationalScienceFoundation(INSF)fortheresearchprojectNo.88001084.
B.MajnounianandM.Jourgholami EffectsofRubber-TiredCableSkidderonSoilCompaction...(123–135)
134 Croat. j. for. eng. 34(2013)1
6. References – LiteraturaAdams,P.W.,Froehlich,H.A.,1984:Compactionofforestsoils.USDAPacificNorthwestExtensionPublication.PNW217,13p.
Ampoorter,E.,Goris,R.,Cornelis,W.M.,Verheyen,K.,2007:Impactofmechanizedloggingoncompactionstatusofsandyforestsoils.ForestEcologyandManagement241(1–3):162–174.
Ares,A.,Terry,T.A.,Miller,R.E.,Anderson,H.W.,Flaming,B.L.,2005:Ground-BasedForestHarvestingEffectsonSoilPhysicalPropertiesandDouglas-FirGrowth.SoilScienceSo-cietyofAmericaJournal69(6):1822–1832.
Cullen,S.J.,1991:TimberHarvestTraffickingandSoilCom-pactioninWesternMontana.SoilScienceSocietyofAmericaJournal55(5):1416–1421.
Eliasson,L.,2005:Effectsofforwardertirepressureonrutformationandsoilcompaction.SilvaFennica39(4):549–557.
Eliasson,L.,Wasterlund,I.,2007:Effectsofslashreinforce-mentofstriproadsonrutting andsoilcompactiononamoistfine-grainedsoil.ForestEcologyandManagementJournal252(1–3):118–123.
Froehlich,H.A.,McNabb,D.H.1984.Minimizingsoilcom-pactioninnorthwestforests.Proceedings6thNorthAmericanforestsoilsconference,June19–23;1983,Knoxville,TN,USA.UniversityofTennessee,DepartmentofForestry,WildlifeandFisheries:159–192.
Froehlich,H.A.,Miles,D.W.R.,Robbins,R.W.,1985:SoilbulkdensityrecoveryoncompactedskidtrailsincentralIdaho.SoilScienceSocietyofAmericaJournal49(4):1015–1017.
Froese,K.,2004:Bulkdensity,soilstrength,andsoildistur-banceimpactsfromacut-to-lengthharvestoperationinnorthcentralIdaho.MasterThesis,UniversityofIdaho,USA,72p.
Gayoso,J.,Iroume,A.,1991:Compactionandsoildisturbanc-esfromlogginginSouthernChile.AnnalsofForestScience48(1):63–71.
Gent,J.A.,Morris,L.A.,1986:SoilCompactionfromHarvest-ingandSitePreparationintheUpperGulfCoastalPlain.SoilScienceSocietyofAmericaJournal50(2):443–446.
Gomez,A.,Powers,R.F.,Singer,M.J.,Horwath,W.R.,2002:SoilCompactionEffectsonGrowthofYoungPonderosaPineFollowingLitterRemovalinCalifornia’sSierraNevada.SoilScienceSocietyofAmericaJournal66(4):1334–1343.
Grace,J.M.,Skaggs,R.W., Cassel,D.K.,2006:SoilPhysicalChangesAssociatedwithForestHarvestingOperationsonanOrganic.SoilScienceSocietyofAmericaJournal70(2):503–509.
Greacen,E.L.,Sands,R.,1980:CompactionofForestSoil,AReview.AustralianJournalofSoilResearch18(2):163–189.
Horn,R.,Taubner,H.,Wuttke,M.,Baumgartl,T.,1994:Soilphysicalpropertiesrelatedtosoilstructure.SoilandTillageResearch30(2–4):187–216.
Horn,R.,Vossbrink,J.,Becker,S.,2004:Modernforestryve-hiclesandtheirimpactsonsoilphysicalproperties.SoilandTillageResearc79(2):207–219.
Horn,R.,Vossbrink,J.,Peth,S.,Becker,S.,2007:Impactofmodern forestvehiclesonsoilphysicalproperties.ForestEcologyandManagement248(1–2):56–63.
Jamshidi,R.,Jaeger,D.,Raafatnia,N.,Tabari,M.,2008:Influ-enceofTwoGround-BasedSkiddingSystemsonSoilCom-pactionunderDifferentSlopeandGradientConditions.In-ternationalJournalofForestEngineering19(1):9–16.
Johnson,L.R.,Page-Dumroese,D.,Han,H.S.,2007:EffectsofMachineTrafficonthePhysical PropertiesofAsh-CapSoils.ProceedingsofU.S.DepartmentofAgriculture,ForestSer-vice,RockyMountainResearchStation:Volcanic-Ash-De-rivedForestSoilsoftheInlandNorthwest:PropertiesandImplicationsforManagementandRestoration.March2005,Coeurd’Alene,FortCollins,CO,USA,p.69–83.
Kolkaa,R.K.,Smidt,M.F.,2004:Effectsofforestroadamelio-ration techniques on soil bulk density, surfacerunoff,sedi-menttransport,soilmoisture andseedlinggrowth.ForestEcologyandManagement202(1–3):313–323.
Kozlowski,T.T.,1999:SoilCompactionandGrowthofWoodyPlants.ScandinavianJournalofForestResearch14(6):596–619.
Krag,R.,Higgingbotham,K.,Rothwell,R.,1986:Loggingandsoildisturbance in southeastBritishColumbia.CanadianJournalofForestResearch16(6):1345–1354.
Matangaran,J.R.,Kobayashi,H.,1999:TheEffectofTractorLoggingonForestSoilCompactionandGrowthofShoreaselanicaSeedlingsinIndonesia.JournalofForestResearch4(1):13–15.
Rab,M.A.,1996:Soilphysicalandhydrologicalpropertiesfollowing logging and slash burning in the Eucalyptus regnans forestofsoutheasternAustralia.ForestEcologyandManage-ment84(1–3):159–176.
Rab,M.A.,Bradshaw,F.J.,Campbell,R.G.,Murphy,S.,2005:Reviewoffactorsaffectingdisturbance,compactionandtraf-ficabilityofsoilswithparticularreferencetotimberharvestingintheforestsofsouth-westWesternAustralia,ConsultantsReporttoDepartmentofConservationandLandManage-ment,WesternAustralia,SustainableForestManagementSeries,SFMTechnicalReportNo.2,146p.
Rohand,K.,Kalb,A.A.,Herbauts,J.,Verbrugge,J.C.,2004:ChangesinsomemechanicalpropertiesofaloamysoilundertheinfluenceofmechanizedforestexploitationinabeechforestofcentralBelgium.JournalofTerramechanics40(4):235–253.
Saarilahti,M.,2002SoilInteractionModel.Developmentofaprotocolforecoefficientwoodharvestingonsensitivesites(ECOWOOD).ProjectdeliverableD2(WorkPackageNo.1),UniversityofHelsinki,DepartmentofForestResourceMan-agement,December2002,1–87.
Sidle,R.C.,Drlica,D.M.,1981:SoilCompactionfromLoggingwithaLow-GroundPressureSkidderintheOregonCoastRanges.SoilScienceSocietyofAmericaJournal45(6):1219–1224.
Šušnjar,M.,Horvat,D.,Šešelj,J.,2006:Soilcompactionintim-berskiddinginwinterconditions.CroatianJournalofForestEngineering27(1):3–15.
EffectsofRubber-TiredCableSkidderonSoilCompaction...(123–135) B.MajnounianandM.Jourgholami
Croat. j. for. eng. 34(2013)1 135
Wang,J.,LeDoux,C.B.,Edwards,P.,2007:ChangesinSoilBulkDensityResultingfromConstructionandConventionalCableSkiddingUsingPreplannedSkidTrails.NorthernJour-nalofAppliedForestry24(1):5–8.Wronski,E.B.,Murphy,G.,1994:Responsesofforestcropstosoilcompaction.SoilCompactioninCropProduction.Else-vierScience,Amsterdam,p:317–342.
Ziesak,M.,2006:Avoidingsoildamages,causedby forest machines.IUFROProceedings:InternationalPrecisionFore-strySymposium»PrecisionForestry inPlantations,Semi-naturalandNaturalForests«.5–10March2006,StellenboschUniversity,SouthAfrica,p.9.
Sažetak
Utjecaj broja prolazaka kotačnoga skidera na zbijanje tla
Upotreba je kotačnih skidera vrlo česta za privlačenje drva iz šume, ali pritom vozilo negativno utječe na okoliš. Cilj je istraživanja bio ispitati kako različiti nagibi terena (odnosno traktorskih vlaka), broj prolazaka vozila po trak-torskoj vlaci i dubina tla utječu na zbijanje tla. Istraživano je zbijanje tla na četiri nagiba traktorskih vlaka: ravan teren, nagibi od +10 %, -10 %, -20 %; na tri različite dubine tla: 5, 15 i 25 cm te s obzirom na broj prolazaka vozla po vlaci: 0, 1, 5, 8, 10, 15, 20, 25 i 30 (slika 7). Uzorci su tla uzimani unutar traktorske vlake i izvan nje (slika 4) svakih 25 m duž vlake kako bi se vidio utjecaj natovarenoga vozila na tlo. Istraživanje je provedeno u Nastavno-po-kusnom šumskom objektu Kheyrud, koji se nalazi unutar Hirkanijske šume u sjevernom Iranu, a drvo je privučeno skiderom Timberjack. Traktorske su vlake zauzimale 5,8 % ukupne površine istraživanoga područja (17 ha) uz do-datnih 0,8 % površine potrebne za pomoćno stovarište. S povećanjem broja prolazaka vozila povećala se i gustoća tla, ali je ipak najveće zbijanje tla ustanovljeno u prvih nekoliko prolazaka vozila. Privlačenje drva uzbrdo (+10 % nagi-ba terena) više je zbijalo tlo (slike 5 i 6) nego privlačenje drva nizbrdo (nagibi terena -10 % i -20 %). Povećanje je gustoće tla i na dubini od 20 do 30 cm bilo značajno (slika 8). Gustoća je tla na dubini od 5, 15 i 25 cm bila veća za 35, 22 i 17 % od gustoće tla na netaknutom tlu (slika 9). Kako bi se smanjilo zbijanje tla, potrebno je privlačiti drvo po unaprijed planiranim i za to predviđenim traktorskim vlakama te usmjereno obarati stabla kako bi se smanjilo kretanje vozila po šumskom bespuću jer već i nakon prvoga prolaska vozila dolazi do povećanja gustoće tla i njegova zbijanja. Također, privlačenje se drva treba odvijati u uvjetima suhoga tla kako bi se smanjila oštećenja na šumskom tlu.
Ključne riječi: zbijanje tla, gustoća tla, kotačni skider, Hirkanijske šume
Received(Primljeno):February12,2012Accepted(Prihvaćeno):Jaqnuary11,2013
Authors’address–Adresa autorâ:
Prof.BarisMajnounian,PhD.e-mail:[email protected],PhD.*e-mail:mjgholami@ut.ac.irUniversityofTehranFacultyofNaturalResourcesDepartmentofForestryandForestEconomicsP.O.Box:31585–431KarajIRAN*Correspondingauthor–Glavni autor