Soil and vegetation properties on reclaimed oil sands in ...€¦ · products and services from the...
Transcript of Soil and vegetation properties on reclaimed oil sands in ...€¦ · products and services from the...
Soilandvegetationpropertieson
reclaimedoilsandsinAlberta,Canada:asyntheticreview
ShuYaoWu
TheFacultyofForestry
TheUniversityofBritishColumbia(Vancouver)
April2015
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ExecutiveSummary The oil sands resource in Alberta represents vast economic opportunities
butalsodramaticenvironmental threat.Many researcheshavebeenconductedon
thepropertiesofreclaimedoilsandssoils.Thispaperintendstoprovideasynthetic
reviewof some conducted researcheson the soil physical, chemical andbiological
propertiesandvegetationcommunitydevelopmentinAlberta.Thispaperchoosesa
totalof20researches(from2003to2014)thatrestrictedtheirstudysitesintheoil
sands extraction regions in Alberta. Five of the researchesmainly focused on soil
physicalproperties,fiveonchemicalones,sixonbiologicalonesandanotherfouron
vegetation community responses. This paper found that reclaimed soils generally
havedifferentpropertiesinallphysical,chemicalandbiologicalaspectscompareto
natural soils. Prominent physical and chemical differences exist in organicmatter
content, soil nitrogen content and nitrogenmineralization rate. These differences
also lead to significantly different microbial community structures and organic
matter accumulation rate. In addition,mitigating effects of timeon soil properties
and vegetation communities were observed in this review. In the end, this paper
addresses themanagement implicationsand future research suggestionsbasedon
researches.
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TableofContents
ExecutiveSummary............................................................................................................................2
TableofContents.................................................................................................................................3
1.Introduction......................................................................................................................................4
1.1OilSandsEnvironment....................................................................................................4
1.2OilSandsExtraction..........................................................................................................6
1.3OilSandsReclamaition....................................................................................................9
1.4StudyObjetivesandMaterials...................................................................................12
2.ResearchFindings.......................................................................................................................14
2.1SoilPhysicalProperties................................................................................................14
2.2SoilChemicalProperties..............................................................................................21
2.3SoilBiologicalProperties.............................................................................................28
2.4VegetationCommunities..............................................................................................39
3.Discussion.......................................................................................................................................43
3.1ReclamationTreatmentEffects.................................................................................43
3.2ReclamationandManagementImplications.......................................................45
3.3LimitationsandFutureReseraches........................................................................46
References...........................................................................................................................................48
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1.Introduction
1.1OilSandsEnvironment
Oil sands refer to thebacteria-processedproducts ofmigratedbitumenmixed
withsanddeposits (Anderson2014).TheprovinceofAlberta inCanadapossesses
1.6trillionbarrelsofthistypeofbitumen,whichisthesecondlargestoilreservein
the world and can supply Canada’s energy demands for next 475 years (Chastko
2004). These oil reserves spread in three regions of Alberta: the Athabasca, Cold
Lake and Peace River (Figure 1) (Canadian Boreal Initiative 2005). Among these
three,theAthabascaregionislargestinsize(graterthan48,000km2)andcontains
thelargestvolumeofbitumen.Theestimatednumbervariesfrom170billionbarrels
to700billionbarrels(FungandMacyk2000;Hrudeyetal.2010).
Figure1.Thelocationsofthreemajoroilsandsreserves(theAthabasca,ColdLakeandPeaceRiver)inAlberta,Canada.(Wikipedia2006).
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Thethreeoilsandregionsarealllocatedintheborealforestzone,whichisone
ofthelargestintactecosystemsintheworld(CanadianBorealInitiative2003).The
boreal forest in Alberta covers an area of 346.964 km2, which represents
approximately 52% of province’s land base (Alberta Environmental Protection
1998).Ahighlydiverse floraland faunalspeciescompositionandstructurecanbe
foundinthislargeecologicalbiome.Inaddition,theborealforestprovidesanarray
of ecosystem services include water filter and storage, flood mitigation, carbon
sequestration,nutrientcyclingandfoodandshelterprovisionforbothanimalsand
human (Leatherdale 2008). This forest also provide many important economic
resources such as wood products, agricultural lands and oil and gas are also
provided to humans by this forest (Canadian Boreal Initiative 2005). All of these
products and services from the boreal forest support thousands of jobs and
contributebillonsofdollarstoAlberta’seconomyannually(Leatherdale2008).For
example, the investment for oil sands industry reached $17.2 billion in 2010; the
royaltiesfromoilsandscompaniestothegovernmentofAlbertareached$3.7billion
in the same year; approximately 151,000 Albertans are directly employed in this
industry(GovernmentofAlberta2013).
Due to thehigh latitude, the climate inAlberta’s oil sands regions is generally
harsh.Theannualgrowingseasondonotstartuntilthegroundsurfacethawsinlate
MayorearlyJuneandonlylastsabout95daystillSeptember(Rowland2008).The
average temperatures range from -22 °C to +17 °C and the annual mean
precipitation is about 470 mm, 300 mm of which comes as rain (Visser 1985;
Rowland 2008). Common vegetation species that can be found in boreal forest
includeaspen (Populus tremuloides and Populusbalsamifera), spruce (Piceaglauca
andPiceamariana), jackpine(Pinusbanksiana), fir(Abiesbalsamea)andtamarack
(Larix lariana) (Rowe, 1972). Other than forest, bog and fen peatlands and
freshwaterwetlands,which cover an area of 20% to 60%of the oil sandsmining
regions,arealsomajortypesoflandscapesoftheborealecosysteminAlberta(Vittet
al.2000).
Theparentmaterialsofoilsandssoilsoriginatedfromthedeltadepositsofan
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ancient tropical sea and were compressed by glaciers during glaciation period,
whichgivesthesoilsfinetexture(Rowland2008).Thesedepositsareconsolidated
and highly sodic and saline (Purdy et al. 2005). There is no single dominant soil
order or subgroup in the oil sands regions but a range of Orthic Brunisols,Mesic
Fibrosol, Orthic or Gleyed Luvisols, and Gleysols (Table 1) (Oil Sands Vegetation
ReclamationCommittee,1998).Thiswiderangeofsoilorderiscausedbydifferent
amountofclay-impededwateranddifferentamountofleachclayinsoils(Rowland
2008). This assortment in the soil ordermakes the soilmoisture gradient to vary
from xeric to subhydric and the oxidation condition to vary from aerobic to
anaerobic.Inaddition,thepeatandpeat-likesoilusuallycanbefoundatsoilsurface
(Stolteetal.2000).
Table1.CommonlyfoundnaturalsoilsintheoilsandsregionsinAlberta.
Name GeneralDescriptionsOrthicBrunisols
Poorlydevelopedmineral-organichorizon.NoBtorBphorizon HighdegreeofbasesaturationParentmaterialsusuallyhavehighbasestatus Commonlyfoundunderforestandshrubvegetation
Orthic GrayLuvisols
Well-developed Ae and Bt horizion plus an organic surfacehorizonusually FaintmottlingmightbefoundnearorwithinBthorizon Parentmaterialsarecommonlybasesaturatedandcalcareous Solumisusuallyacid
MesicFibrosol Deep,relativelyundecomposedfabricmaterial Parentmaterialisorganicmatterandclay-richglacialtill Highpercentageoforganicmatter(>30%) Occurinbogsandfens
Gleysols Lackofwell-developedmineral-organicsurfacehorizon,suchasAhorAp GleyedBorChorizonUsuallyoccurinpoorlydrainedareas
Sources:TheCanadianSystemofSoilClassification1998;Rowland2008.
1.2OilSandsExtraction
Thehistoryofpeopleusingthebitumendepositionisquite long.Inthepast, it
was traditionally used by First Nations to patch canoes (Hrudey et al. 2010). The
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modern commercial oil sands industry in Alberta started slowly but expanded
rapidly(Chastka2004).Nowadays,therearedozensofoilsandscompaniesworking
in the Alberta oil sands regions (Canadian Oil Sands Navigator 2015). The major
three companies are Syncrude Canada Ltd, Albian Sands and Suncor Energy Inc
(Rowland2008).Open-pitminingand insituextractionarethetwomainoilsands
extractionmethodsthesecompaniesareusing.
Theopen-pitextractionmethodcanonlybeappliedinareawheretheoilsands
oreisclosetosurface(Figure2)(Anderson2014).Thefirststepofsurfaceminingis
the removalof all vegetation, soils andnon-orehorizonsabove thedeposit.These
materialsareusuallyreferredas“overburden”andhavedepthsrangefrom1mto
over70m(Hrudeyetal.2010).Thesematerialsareusuallystockpiledsomewhere
close by, sometimes formany years, before theywere used in future reclamation
(Mackenzie2011).
Figure1.Open-pitoilsandsmininginAlberta(NationalGeographic2011).
However, for approximately 80% of Alberta’s oil sands areas, the bitumen
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deposits are too deep for the open-pit mining method and the in situ extraction
methodneedtobeapplied(RAMP2015).Currently,themostcommonlyusedinsitu
methodistheSteamAssistedGravityDrainage(SAGD)(Figure3).Thismethoduses
two drilled horizontal wells, one above the bitumen deposit and one below. The
abovewellpumpsheatedsteaminordertomeltandpressbitumenintothelower
well, fromwhichthebitumenistransporteduptothesurface.Water is injectedto
replacetheextractedbitumenforstabilizationpurpose(RAMP2015).
Oncetheoilsandsdepositsareextracted,eitherfromopen-pitorinsitumethod,
they are transported to a facility that separates the bitumen and the sand before
theywereupgradedintopetroleum(Rowland2008).TheClarkhot-waterextraction
method,whichuseshotwaterwithaddedsodiumhydroxide(NaOH),isusedinthis
separation process (Rowland 2008). The ejected sands (more specifically 95±1%
sand, 4% silt and 1% clay) and water became tailings, which transformed from
moderately acid (pH 5.5-6) to alkaline (pH 7.5-8.5) due to the added chemicals
(Visser1985).Theioniccontent,suchassodium,sulfateandchlorideionsarealso
high in these tailings (Renault et al. 1998). These tailings sands will leave for
settlement and freely drained. The large particles settle out much more quickly
comparetosmallerones.Thefineparticlescantakeverylongtime,evenhundreds
of years, to settle because of thehigh ionic content (Renaultet al. 1998). Gypsum
(CaSO4) is added sometimes as a consolidation agent to accelerate the settlement
processofthefineparticles(LiandFung1998).
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Figure2.Schematicof theSteamAssistedGravityDrainage(SAGD) insitubitumenextractionmethod(thePembinaInstitute2005).
There are three main types of waste materials generated from the bitumen
extractionandproductionprocess,whichareoverburdenmaterial,tailingsandand
finetailings(FungandMacyk2000).Overburdenreferstothematerialsthatoverlay
the oil sands deposits and contain low-grade oil sand, glacial till, glacial-fluvial,
glacial-lacustrine and peat material. Tailing sands and fine tailings are both the
remainingwasteproductsafterbitumenextraction.Tailingsandsaremadeof96to
99percentsandysilicaandtheresidualbitumen.Nevertheless, finetailingsmainly
consistofclay,siltsandresidualbitumen(FungandMacyk2000).
1.3OilSandsReclamation
Itismandatoryfortheoilsandindustrytohavethedisturbedlandsreclaimed,
re-vegetatedandcertifiedbytheGovernmentofAlberta.However,thegovernment
doesnotrequireanexactidenticalconditionbutonly“anequivalentlandcapability”,
whichisdefinedbytheLandCapabilityClassificationSystem(LCCS)as“theabilityof
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the land to support various landusesafter conservation similar to theability that
existed prior to an activity being conducted on the land” (CEMA 2006). The
government regulator that is responsible for oil sand lands reclamation oversight
and final certification is the Alberta Environment and Sustainable Resource
Development.AccordingtotheLCCSfieldmanual, therearethreekeyfactorsneed
to be addressed in order to achieve high land capability, which are minimal salt
impacts(<4.0dS/msalinityEC,<8.0SodicitySARand<7.5pH),sustainednutrient
cyclingandsufficientavailablewater-holdingcapacity (CEMA2006).Furthermore,
vegetationcommunitymustalsobedevelopedinthesitesinordertobecertifiable
assuccessfulreclamation.Someindicatorsforsuccessfulvegetationreestablishment
includeplantcommunitycomposition,netprimaryproductionoftheecosystemand
soilsalinity.
The first step of reclamation is the replacement of the removedmaterials or
reconstructing the soil. As guided by the above legal requirements, an ideal
soil-formingmaterial should have 1) the ability to supply water and nutrients to
plants;2)theadequatestabilitytoresisterosionbutalsoenablerootdevelopment
and;3)theabilitytobufferenvironmentalchanges(Rowland2008).Variouskinds
ofminingresidualsarecommonlymixedandusedasreclamationmaterials,suchas
peat-mineralmix,tailingsands,topsoil,subsoil,overburden,leanoilsandandmine
by-products(Table2)(Rowland2008;Hrudeyetal2010;Mackenzie2011).
Althoughthere isnouniversalormandatoryprescriptionofhowthecompany
shouldreconstructasoil, fiveoutof thesevenpopularprescriptions includeusing
peat-mineral mix as a part of the reclaimed soil (Rowland et al. 2009). The
popularity of peat is not only because of its high abundance in the boreal forest
region inAlberta, but alsobecausepeatmay improveorganic carbon content, soil
nutrient and water retention capacity (Rowland 2008). As a pratical example,
SyncrudeCanadaLtd.spreadsapproximately15cmofpeatwith20cmofmineral
soilastop layerforplantgrowth.Beneaththis layer,anupto80cmdeepcapping
layer that contains amixture of lean oil sands and overburden is used to prevent
waterandplantpenetratingtounderneathtoxicmaterials(Figure4).
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Table 2. Descriptions of some common materials used for soil reconstruction inAlberta’s oil sands regions (Mossop, 1980; Danielson et al. 1983; Hardy BBT Ltd.1990;RungandMacyk2000;Rowland2008).
Name Originanddescription
Principlemineralcomponent
Physio-chemcialproperties
Peat-mineral Strippedandmixedfromborealbogs
Clayloamorclay 2–17%organicC;Near-neutralpH;P:Mratiovaries3:2to3:4byvolume
Tailingsands MarinesandswithsomeshalebedsfromCretaceous-era
95%sand(quartz),4%silt(feldsparandmica)and1%clay(kaolinite,illiteandmontmorillonite)
Hydrophobicafterair-dryingNilplantnutrientsErosion-proneHigherosionpotentialLowavailablewaterholdingcapacity,cationexchangecapacity,microbialactivityandorganicC
Subsoil BandChorizonofborealforestsoil
Silt-clayandclay(kaolinite,illiteandmontmorillonite)
pH5.0–8.0Non-saline<2%organicC
Overburden SedimentarydepositsfromCretaceous-eradriftedbyglacialfromPleistoceneEpoch
Silt-clayandclay(kaolinite,illiteandmontmorillonite)
pH8.0+Non-salineNilorloworganicCLowavailablewaterholdingcapacity,microbialactivity,nutrientstatus
Leanoilsand Cretaceous-eramarinesedimentswithmigratedbitumen
Sandswithsomeshales,siltsandclays
<6%bitumenbyweightpH5.5–6.0
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Figure3.Schematicrepresentationofoilsandsreclamationprescriptionsfromthreeoil sands companies in Alberta, Canada (Oil Sands Vegetation ReclamationCommittee1998;AMECandParagon2005;Rowland2008).
Intermsofvegetationrestoration,Hordeumvulgare(barley) isusuallyplanted
asacovercropinitiallytoprotectsoilandcontrolerosion.Additionally,barleycan
add organic matter and nutrients to the soil as well. Since barley is a poor
competitor, they will also be easily replaced by more desired species afterwards
(Rowland2008).Inthelate1980’s,companiesstarttoadaptnaturalre-colonization
insteadofdirect seeding.However,on somesites,particularly for those reclaimed
for forestrypurposes, treeplanting, such as jackpine, balsampoplar,white birch,
white spruce and aspen, is still used (Rowland 2008;Alberta Environment 2009).
Shrubspecies, suchas rose, low-bushcranberry,dogwood, raspberry, greenalder,
Canada buffalo-berry, Saskatoon, blueberry, bog cranberry and bearberry, are
replanted too (Alberta Environment 2009). Mixed nitrogen, phosphorous and
potassiumfertilizerareusedalmostinallsitesinthefirstonetofiveyearsinorder
toacceleratethevegetationestablishment(Hrudeyetal.2010).
1.4StudyObjectivesandMaterials
Upto theyearof2012, therewere715km2havebeenexploited foroil sands,
however, only 1 km2 of which has been successfully reclaimed and certified
(Anderson 2014). Despite the significant economic profits oil sands brought to
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Alberta,theenvironmentalcostsofexploitingoilsandsongreenhousegasemissions,
air and water quality, are also becoming more and more tremendous. In 2010,
approximately48million tonesofgreenhousegasemissions inAlbertaarecaused
by oil sands exploitation (Anderson 2014). Critiques of the effectiveness and
authenticity of oil sand reclamation are also keep arising (Grant et al. 2008). The
earliest reclaimedsiteshavealready turned intoover30-year-old.Moreandmore
researches have been conducted in order to study the reclaimed oil sands soil
properties in Alberta. This paper intends to summarize some of the conducted
researchesonphysical,chemicalandbiologicalpropertiesofreclaimedoilsandsoils
and vegetation community development status in order to provide a synthetic
review to other researchers, compare reclaimed soils with natural soils, propose
reclamationandmanagementsuggestionsandidentifysomepotential futurestudy
focuses.
A total of 20 researches that have their study sites in the oil sands extraction
regionsinAlbertawerechosen.Theseresearchesfocusedmainlyeitheronphysical
(5),chemical (5),biological (6)soilproperties(somestudiedmixedproperties)or
vegetation growth (4) on reclaimed oil sands sites. Data were utilized from 12
publishedpeer-reviewedjournalarticlesand8masterthesisworkrangefrom2003
to2014.Each study isbriefly retoldby its studyobjectives,methods, key findings
andimportantdiscussionpoints.
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2.ResearchFindings
2.1SoilPhysicalPropertiesTable 1. Summary of discovered physical properties and their descriptions ofreclaimedoilsandssoilsinAlberta,Canada. Studies(Year)
Properties Findings
Yarmuch(2003)
Texture
-Topsoilsrangefromloamtoclayloamtosiltyclayloam(siltloamtoloaminnaturalsoils)-Subsoilsrangefromsandyclayloamtoclayloamtosiltyclayloam(clayloamtoclaytoheavyclay) -Muchmoreorganicmatterintopsoillayercomparetothatofnaturalsoils-Subsoilsaremoresimilarbutcontainlessclay
Bulkdensity
-Lowerinreclaimedtopsoilcomparetonaturalsoils -Higherinyoungtopsoilandlowersubsoilthaninoldreclaimedsoils-Nosignificantdifferencesbetweenyoungandoldreclaimeduppersubsoils
Fieldsaturatedhydraulicconductivity
-Nosignificantdifferenceneitherbetweennaturalandreclaimedsoilsnoryoungandolderreclaimedsoils
Porosity
-Highermacro-,meso-andmicro-porosityinreclaimedtopsoilthanthatofnaturalsoils -Moremacroporesandlessmicroporesinreclaimedsubsoilsthanthatofnaturalsoils- Moremicroporesinyoungreclaimedsoilsthaninoldones
Leatherdale(2008)
Soilmoisture
-Slopepositionsdidnotsignificantlyaffectsoilmoistureregime-Soilsthathavehigheramountoforganicmatterholdhigherplantavailablewater
Soilnutrient(chemicalproperty)
-Ahighdegreeofvariabilityofsoilnutrientsacrossslopepositions-Seasonappearedtobemoreinfluencingthansiteconditionsonnutrientavailability
TritesandBayley(2009)
Organicmatteraccumulation
anddecompositioninwetlands
-Biomassaccumulationnegativelyrelatestopollutantsbutpositivelyrelatestowaterdepthbutstilllowerthannaturalwetlandsduetohighsalinity-Similarlitterdecayratesbetweennaturalandreclaimedwetlands
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Hunter(2011)
Waterrepellency
-Highvariabilityofwaterrepellencyexistswithinbothreclaimedandnaturalsites-Surfacereclaimedsoilsappearedtohavehigheraveragewaterrepellencythansubsurfacesoils-NosignificantdifferencesfoundbetweentheRIvaluesofsurfacereclaimedandnaturalsoils
Anderson(2014)
Organicmattercontent
-Higherorganicmatterinreclaimedsoilsthannaturalsoilsmainlyduetopeat
Sourcesoforganicmatteraccumulation
-DominanttreetypeisthemostinfluencingfactorofSOMaccumulation-Rootandmacrofaunalbioturbationdominatedassourceingrasslandtreatment-Dissolvedorganicmatterfromforestfloorandmacrofunalactivitydominatedindeciduoustreatment-Nosignofaccumulationinnaturalandreclaimedsprucesites
Organicaccumulation
rate
-Highestindeciduoussites,moderateingrasslandsitesandslowestinsprucesites-Theordercorrespondswiththediversityoforganicmatterinputandthelevelsofmacrofaunalbioturbation
Yarmuch(2003)–MeasurementofsoilphysicalparameterstoevaluatesoilstructurequalityinreclaimedoilsandssoilsAlberta,Canada: Yarmuch(2003)studiedarangeofcommonsoilphysicalpropertiesinorderto
access the structurequalityof reclaimedoil sands soils in theAthabascaoil sands
region. The author also compared the soil physical properties among naturally
disturbedsitesandreclaimedsiteswithdifferentages.Ninenaturallydisturbedsites
and27sitesindisturbedareaswereselected.Soilpitsweredugandsampleswere
collectedwithinthreesoillayers:topsoil(0-20cm),uppersubsoilandlowersubsoil
inreclaimedsoilsandLFH,A,BandBCorChorizonsinundisturbedsoils.Physical
propertiesthatwereanalyzedincludedparticlesizeanalysis(hydrometermethod),
soilbulkdensity,fieldsaturatedhydraulicconductivity(GuelphPermeameter),pore
size distribution and available water holding capacity (the water columnmethod
andpressureplateapparatus).
The texture of the upper subsoil and the lower subsoil of
peat-mineral-mix/overburdenreclaimedsoilswasfoundtorangefromsandyloam
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tosandyclayloamtoclayloam.Thecomparisonofsoilphysicalpropertiesbetween
reclaimedoilsandssoilsandnaturallydisturbedsoilsshowedthatthetextureofthe
topsoilhorizonwasmuchdifferent thanthenaturallydisturbedAehorizondueto
high organic matter from the peat amendments. However, the upper and lower
subsoilsofreclaimedsoilshadaslightlylowerproportionofclaysizeparticlesthan
thenaturallydisturbedBtandBC/Chorizonsdo,respectively.
Themean bulk density of the reclaimed topsoils was significantly lower than
thatof thenaturallydisturbedAehorizon.But thedifferenceswerenotsignificant
between the upper and lower subsoil horizons and the corresponding naturally
disturbed soil horizons. In addition, therewereno significantdifferencesbetween
the field saturated hydraulic conductivity of the topsoil, the upper and lower
subsoilsandtheircorrespondingnaturalhorizonseitherinmostinstances(fiveout
of the seven comparisons). This might be attributed to the low-impact reclaimed
techniques that the oil sands industry adopted, such as lightweight equipment,
wheeled and tracked equipment and freezing reclaimed materials beforehand to
makesoilaggregatesmorerigid.
In term of total porosity, all the macro-, meso- and micro-porosity were
significantly higher in the reclaimed topsoils than that in naturally disturbed Ae
horizons.Moremacroporesandlessmicroporeswerefoundinthereclaimedupper
andlowersubsoilscomparetothenaturallydisturbedcorrespondinghorizons.This
is likely due to the higher sand proportions in the reclaimed horizons and the
greater proportions of clay in the naturally disturbed soil horizons. In the end,
Yarmuch (2003) concluded that reclaimed soils donot possess limiting structures
comparetothatofnaturalsoils.
Soil physical properties were also compared among reclaimed soils with
differentages.Itwasfoundthatreclaimedyoungtopsoilandlowersubsoilhorizons
hadhigherbulkdensities thanoldones.Thedifferencesofbulkdensitiesbetween
youngandolduppersubsoilhorizonswerenotsignificant.Inaddition,therewasno
significant difference found in the field saturated hydraulic conductivity, total
porosityandamountofmacro-,meso-andmicroporesbetweentheoldandyoung
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reclaimed soils either. However, there were significantly higher amount of
macropores and lower amount ofmesopores in the youngupper subsoil horizons
than in theoldones. Yarmuchexplained this observationbynatural settlementof
soilmaterialovertime.Inconclusion,theauthorstatedthatthereislittlechangein
soilphysicalpropertiesinapproximately20yearsandreclaimedsoilstructuresmay
bestableorchangeveryslowly(decadestocenturies).
Leatherdale(2008)–SoilmoistureandnutrientregimesofreclaimeduplandslopesintheoilsandsregionofAlberta:
TheobjectiveofLeatherdale’sstudyistoquantifythesoilmoistureandnutrient
regimes of reclaimed soils. More specifically, the author wanted to answer how
topographical position affect soil moisture and nutrients and determine the
temporal variability of soilmoisture andnutrients at slope levels. Five study sites
were selected approximately 50-80 km north of Fort McMurrary in northeastern
Alberta.Meteorologicalparameters(weatherstation),soilmoisture(Diviner2000®
accesstubes),topsoil,uppersubsoilandlowersubsoilsampleswerecollectedinthe
field.Inlaboratory,bulkdensity,soilwatercharacteristiccurves(usepressureplate
apparatus), particle size distribution (use hydrometer method) and total organic
carbon(usedrycombustionmethod)weredetermined.
The results showed that themoisturecontentswerenot significantlydifferent
acrossthelower,midandupperslopepositionsonthereclaimeduplandsoils.This
was explained by the heterogeneity in soil properties, such as peat-mineral mix
depth and distribution, vegetation spatial patterns or relatively gradual slope
gradients(lessorequalthan25%).Soilsthathavehigheramountoforganicmatter
holdhigherplantavailablewater.Inaddition,theinfiltrationrateswerefoundtobe
higher in soils that have greater fraction of coarse textured material in their
peat-mineralmixlayer.Themoistureregimesofuppersoilprofilesinmostsiteshad
quickresponses toprecipitationevents,exceptonsites that lackofvegetationand
havehydrophobicproperties.Soilswithlessfinertexturedmaterialsaresubjectto
percolation.South-andwest- facingsites lostormaintainedsoilwateroverwinter
whilenorth-facingsitesgainedsoilmoistureoverwinter.Thismightbebecauseofa
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combination of less incoming solar radiation on north-facing slope and the
water-holdingeffectofvegetation.
In terms of soil nutrient regimes, a high degree of variability in nutrient
availabilitywasfoundacrosstheslopepositions.Theauthorexplainedthisthrough
vegetationpatchdynamicsanddifferentspatialdistributionsofvegetationspecies.
Season appeared to be amore influencing factor of nutrient availability than site
conditions. Similarity in seasonal nutrient availability was found between some
reclaimedsoilsandnaturallydisturbedsoils.
Trites and Bayley (2009) – Organic matter accumulation in western boreal salinewetlands:acomparisonofundisturbedandoilsandswetlands:
Since thewetland isalsoadominantpre-disturbance landscape type inAlbert
oil sands region, oil sands companies are required to reclaim some sites back to
wetlandsevenafterthesalinityiselevated.Therefore,TritesandBayleywantedto
measureandcomparetheproductionrates,decompositionratesandorganicmatter
(OM)accumulationpotentialinreclaimedwetlandsandinnaturalwetlandsacrossa
salinitygradientinordertoevaluatethepotentialofreclaimedplantstoaccumulate
peat under future oil sands reclamation scenarios. Three reclaimed oil sands
wetlandsandsixnaturalwetlandswereselectednearFortMcMurray,Alberta.Total
carbon, nitrogen and phosphorus of soils, aboveground wetland production,
decompositionrate(litterbagtechnique),C:N:PratioinabovegroundlitterandOM
accumulationpotentialweremeasuredorestimatedinonetotwovegetationzones
ateachwetland.
Itwasfoundthemeanannualtotalbiomassproductioninthisstudywasabout
502 g m-2 and the production rate negatively related to salinity. Negative
relationshipwas found between pollutants, such as NH4+or naphthenic acids,and
biomasswhilepositiverelationshipwasobservedbetweenwaterdepthandbiomass,
which indicated the important role of the water availability played in successful
vegetation reclamation. High water level can also decrease the oxidation rate of
accumulatedpeat.Inaddition,TritesandBayleyalsoobserveddifferentdecayrates
for different litter types but same decay rates between oil sands and natural
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wetlands.OnlyweakcorrelationwasfoundbetweendecayratesandtheC:Nratios
ofabovegroundplanttissuesandnocorrelationwasobservedbetweensalinityand
litterdecompositionrates.
After comparing the organic accumulation and decomposition rates, a net
average annual organic matter accumulation of 307 g m-2 and production to
decomposition quotients ranged from 2.0 to 3.8 were obtained across both
reclaimedandnaturalwetlands.Thequotientvaluesweremuchlowerthanaverage
borealbogs(7.1)butsimilartotheonesfrompoorandmoderate-richwoodedfens
(3.6-4.0). Peatlands that were dominated by Schoenoplectus tabernaemontani and
Trigiochinmaritimageneratedthehighestratios,whichimpliedahigherpotentialto
accumulate OM since these species had slower decomposition rates. The slower
biomass decomposition rates compensated the salinity-induced slow production
ratesandgaveoilsandswetlandsrelativelyacceptablepeataccumulationrates. In
the end, the authors concluded that reclaimed oil sands wetlands had peat
accumulation if theconditionof sufficientwater leveland lowpollutantswasmet.
However,ingeneral,thepeataccumulationratewouldstillbeataslowerlevelthan
innaturalwetlandsinthelongterm.
Hunter (2011) – Investigation of water repellency and critical water content inundisturbed and reclaimed soils from the Athabasca oil sands region of Alberta,Canada:
Hunteraimstoquantifythedegreeofnaturallyoccurringwaterrepellencyand
thepotentialof severewater repellency in reclaimedsoils. Inorder todo this, the
author selected a total of ten sites (four reclaimed and six natural sites) in the
Athabasca oil sands region and examined the mineral and organic reclamation
materials,peat,mineral soil, forest floor in these sites. Soilwater repellency index
(RI)weregatheredbyusingstandardandmini infiltrometers.Othermethodssuch
as the water droplet penetration time test (WDPT) and the molarity of ethanol
droplettest(MED)wereusedalongwiththeinsiturepellencyindextoestimatesoil
waterrepellency.Thecriticalwatercontentofreclaimedsoilswasalsodetermined
throughmeasuringthecontactangle(CA)andWDPT.
20
The results from both standard and mini inifltrometers suggested that high
variability ofwater repellency existswithin both reclaimed and natural sites. The
meanRIvaluesfromtheminiinfiltrometers(9.61)werehigherthanthosefromthe
standard ones (3.46) but the differenceswere not statistically significant inmost
sites. TheWDPT and MED tests also demonstrated similar trends of high spatial
variabilityofsoilwaterrepellency.Thesurfacereclaimedsoilsappearedtohavea
higheraverageRI than the subsurface soils.Nevertheless, therewasnosignificant
differencesfoundbetweentheRIvaluesofthesurfacereclaimedandnaturalsoils.
The results of the critical water content showed that reclaimedmineral soils
weregenerallywettableabovegravimetricwatercontentsof5 to10%.Subcritical
waterrepellencyoccurredinthematerialsthatwereaffectedbythecoarsetextured
tarball. In addition, therewas a clear positive relationship between the degree of
waterrepellencyandthedecompositionlevelsofpeatmaterials.Furthermore,peat
and LFH layers had no relationship betweenwater content andwater repellency.
Finally,Hunter concluded thatwater repellencymightnot be amajor issue in the
Athabascaoilsandsregion.
Anderson(2014)–Organicmatteraccumulation inreclaimedsoilsbeneathdifferentvegetationtypesintheAthabascaoilsands: Anderson researched three aspects of the soil organic matter (SOM) in
reclaimed oil sands soils, which were the organic matter content, the dominant
sources of organicmatter and the organicmatter accumulation rates. The author
selected five aspens sites, five spruce sites and five grassland sites that ranges
between20to36yearsoldandarelocatedintheuplandAthabascaoilsandsregion.
Five nearby natural sites with similar moisture and nutrient regimes were also
selected. The author tested and analyzed measurements include the bioturbation
levels,therootabundancesandtheorganicmattercontents.
Itwasfoundthatthereclaimedsoilshadconsiderablyhigheramountoforganic
matter than the natural soils probably due to the abundant peat used during
reclamation.Reclaimedpeat-mineralmixsoilswerefoundtohavehighercapacityto
stabilizedissolvedorganicmatters,whichledtoanincreasedresidencytimeofSOM
21
in soil profiles. This might be attributed to the higher pH and higher polyvalent
cations contents in peat. This increased residency time of SOM along with fresh
organic matter input probably both contributed to the accumulation of SOM in
reclaimedsoils.
The sources of SOM accumulation depend on the planted vegetation. For
example, root andmacrofaunal bioturbationwere the dominating SOM sources in
grassland, while in deciduous treatment sites, dissolved organic matter from the
forest floor andmacrofaunal activity dominated as sources. Therewas no sign of
activeSOMaccumulationinnaturalsitesandreclaimedsitesthatwereplantedwith
spruces.Astrong inverserelationshipbetweensoildepthandSOMconcentrations
wasfoundindeciduoussites,whichwasan indicatorofdownwardmovinghumus
compounds. It was concluded that dominant tree type was the most influencing
factorofSOMaccumulation.
In terms of the forest floor development, grassland and deciduous sites had
significantly thicker forest floorandmoremacrofaunalactivities thansprucesites.
Theseprobablyattributedtothehigherquantitiesandbetterqualityoftheorganic
matterinputinthesetwotypesofsites.Lastbutnotleast,itwasfoundthattheSOM
accumulation ratewashighest indeciduous sites,moderate in grassland sites and
lowestinsprucesites,whichcorrespondwiththediversityoforganicmatterinput
andthelevelsofmacrofaunalbioturbation.
2.2SoilChemicalProperties
Table 2. Summary of discovered chemical properties and their descriptions ofreclaimedoilsandssoilsinAlberta,Canada.Studies(Year)
Properties Findings
Rowland(2008)
SoilpHlevel-Almostallsites,exceptforonehadhigherpHthannaturalecotypesbecauseofthenatureofreclamationmaterials
Insitubio-availablenutrients
-HighamountofNO3—NandlowC:Nratiowasfoundinallreclaimedsitesdespiteagesandfertilizerapplication-MicronutrientNawaslowonallreclaimedsites
22
becauseofdispersalofNafromclaysbytheadditionofgypsumandleaching
Litterinputandorganiclayerdevelopment
-LitterdecompositionrateandtheFHlayerdevelopmentrateweresloweronreclaimedsitescomparethoseofnaturalsites-Approximatelyatleast25yearswasrequiredtohavereclaimedplantcommunitiessimilartonaturalones
Moisturecontent(physicalproperty)
-Thepresenceoftailingsandsdecreasemoisturecontent.-Thepresence/absenceofplantrootactivitydidnotaffectmoisturecontent
Plantcommunitydevelopment(vegetationresponse)
-Treatmentsthatusepeat-mineralmixplacedaboveoverburdenandtailingsandsandinitiallyfertilizedwithP,KandelementssuchasMngeneratedecotypesmoresimilartothenaturalones
Turcotteetal.(2009)
Soilorganicmatterquality
-LowerAURresidue,alkyl/O-alkyratioandorganicmatterintheorganicmatterheavysandfractionwerefoundinoldreclaimedsites-Carbonconcentrationinthelow-densityfractioncanbeusedasindicatorofSOMqualityinreclaimedsites
Hemsley(2012)
Nitrogenavailabilityandecologicalresponses
-Higheratmosphericnitrogendeposition(mainlyasNH4+)inreclaimedsites-AmountofwetNdepositionnegativelyrelatetocanopycover-PinestandsshowedmorecloseNcycle,highertotalinorganicNandhighersensitivitytoNdeposition
MacKenzieand
Quideau(2012)
Nitrogenmineralization
-Nitrogenmineralizationrateinpeatmineralsoilfromlaboratoryincubationwasmuchhigherthannaturalforestsoils-TherateinforestfloormineralsoilwasatasimilarlevelasinnaturalLFHlayers-Theratesobtainedlaboratorywasmuchhigherthanfieldmeasurementandmodeleddecompositionrates
Microbialcommunitystructure
-Highmetabolicquotient(basalrespiration/totalmicrobialbiomass)butfeweramountsoffungiandfungi/bacteriainpeatmineralsoil-Forestfloormineralmixshowedmoresimilarmicrobialcommunitystructureasinnaturalsoils-TheeffectofNPKfertilizationonmicrobial
23
structurewasnotprominentwithoutvegetationpresence
Plantnutrientavailability
-Muchmorehighernitrogen(mainlyinnitrateform)contentwasfoundinpeatmineralandmixsoilsthaninforestfloormineralsoils-Astrongassociationbetweenrespirationandnutrientavailability
Quideauetal.(2013)
NutrientAvailability
-HigherNandSconcentrationsinreclaimedsitesbutstillsomesimilaritieswithnaturalsites
Organicmattercomposition
-Higheramountoforganicmatterinreclaimedsoils.-Verydifferentorganicmatterchemicalcompositionbetweennaturalandreclaimedsites
Microbialcommunities(biologicalproperty)
-Someuniquemicrobesfoundinreclaimedsitescomparetonaturalsitesbutalsowithsomeoverlapswithnaturalsites
Rowland (2008) – Recreating a functioning forest soil in reclaimed oil sands innorthernAlberta: InRowland’sstudy,arangeofvariablesweremeasuredwithintheWoodBuffalo
region of northern Alberta in order to determine whether reclaimed and natural
systemsdifferinsoilpropertiesandhowthereclaimedsystemschangeovertime.A
totalof47naturalandreclaimedsoilplotswereestablished.Variablesthatcollected
includemoisturecontent,pH,C:Nratio,littermasslossrate,litterinputandorganic
layer development status, in situ bio-available nutrients, nitrate and ammonium
productionandplantcommunitydevelopment.Rowlandstudiednotonlychemical
butalsomanyphysicalandbiologicalproperties.
The results of moisture showed that the presence of tailing sands at depth
generallyreducemoisturecontent,however,apeat-mineralmixcapusuallyhelped
storingmoistureunless tailingsands isdirectlybelow it.Thepresence/absenceof
plantrootactivitydidnotaffectmoisturecontentaccordingtotheexperiment.This
mightbeattributedtothemicrobialproliferationinsiteswithoutplantroots.ForpH
level,almostallsites,exceptforone,hadhigherpHthannaturalecotypesbecauseof
the clay-rich, calcium-absorbing mineral soil in the peat-mineral mix and the
windblowndepositsfromnearbyexposedtailings.
24
Intermsofnutrientstatus,abundantNO3—Nwerefoundinallsitesdespiteages
andfertilizerapplication.MicronutrientNawaslowonallreclaimedsitesbecauseof
dispersalofNafromclaysbytheadditionofgypsumandleaching.Furthermore, it
wasfoundthat litterdecompositionrateandtheFHlayerdevelopmentrateswere
sloweronreclaimedsitescomparethoseofnaturalsites.Approximatelyatleast25
yearswasrequiredtohavereclaimedplantcommunitiessimilartonaturalones.
In the end, the author concluded that the treatment types, which place
peat-mineral mix above overburden and tailing sands both generated ecotypes
similartothetargetnaturalones.Butthesesiteswithapeat-mineralmixcapneed
to be initially fertilized with P, K and elements such as Mn for successful early
ecosystemdevelopment.RowlandchallengedtheuseofNfertilizer,cleanpeatand
glacial tills as reclamation materials since abundant nitrogen was also found in
unfertilizedsoilsandthepeatandtillresourcesarenon-renewable.Healsoargued
large-scalereclamationshouldfocusmoreonecologicallandscaperestorationthan
achievingexactoriginalstate. Turcotte et al. (2009) – Organic matter quality in reclaimed boreal forest soilsfollowingoilsandsmining: Turcotteetal.assessedthereclaimedsoilqualitythrougharangeofsoilorganic
matter(SOM)parametersandcomparedtheseparameterswithnaturalsoilsinthe
FortMcMurrayoilsandsregion.TheytriedtoanswerwhethertheSOMparameters
evolvedwithtimetowardsthoseofnaturalsoilsandwhichreclamationprescription
performedthebest.Atotalof45studysites(18naturalsitesand27reclaimedsites)
were selected within an 86 km radius from the town of Fort McMurray, Alberta.
Surfacesoils(0to10cm),excludingtherawlitterlayer,werecollectedineachsite.
ThesampleswerefurtherdividedintoclayandsiltOM,lowdensityOMandheavy
sandOMfractions.Inlaboratory,theacid-unhydrolyzableresidue(AUR)(proximate
analysis),totalC(drycombustion),valueofalkylC,O-alkylC,aromaticC,phenolicC
andcarbonylC(spectrometer)andcarbonisotopiccomposition(δ13C)(isotoperatio
massspectrometer)weredetermined.
Theresultsdemonstratedthatthereclaimedsoilsandthenaturalsoilshadboth
25
similarities anddifferences in SOMparameters.The amountof total carbon in the
low-density fraction was similar in disturbed and natural sites. However,
significantly higher O-alky, lower alkyl C and lower carbon concentrations in the
low-density organicmatter fractionswere found in reclaimed soils. Turcotteet al.
explainedthesebytheusageofpeatamendmentsduringreclamation.Fortheheavy
sand and finer mineral particle (SiC) pools, it was not surprising to find the
reclaimedsiteshadsignificantlylessamountofhumifiedorganicmatter.Lastly,the
carbonconcentrationsintheAURwerealsohigherinreclaimedsoilsthaninnatural
soils, which suggested that the organicmater in the reclaimed soils has not been
stronglyaffectedbymicrobialdegradation.
In terms of the SOM parameters between young and old reconstructed soils,
Turcotteetal. foundthattheAURresidue,alkyl/O-alkyratioandorganicmatterin
theorganicmatterheavysand fractiondecreasedwith timesincereclamationand
couldbeusedasindicatorofSOMformationprocessesforreclaimedsoils.Another
goodindicatorforgeneralSOMqualitythattheyfoundwasthecarbonconcentration
inthelow-densityfractionsinceitcorrelatedwithmanySOMparameters. Hemsley (2012) – Ecological response of atmospheric nitrogen deposition onreconstructedsoilsintheAthabascaoilsandsregion: InHemsley’sstudy,heaimedto firstlydeterminetheseasonalamountsofwet
nitrogen(N)deposition,soilnitrogenavailabilityandtheirpotentialrelationshipsin
reconstructed soils and then assess the ecological responses and potential
implications of atmosphericN depositions. A total of 27 siteswith three different
tree canopy coverage (0-30%, 31-65% and 66-100%) and two species types
(trembling aspen and Jack pine) were selected 40 km north of Fort McMuaary,
Alberta. At each site, the author measured and collected atmospheric wet N
deposition (atmospheric deposition collectors), soil N availability (plant root
simulatorprobes),soils,foliageandrootsamples.
The atmospheric N deposition appeared to be <1 kg N ha-1yr-1 greater than
naturalsitesandmainlyweredepositedasNH4+.Canopycoverhadaclearnegative
relationship with the amount of wet N deposition received by reclaimed soils.
26
Although NH4+ precipitated more, it was found that NO3- was the dominant
N-availableforminreconstructedsoilsinthisstudy.Apositiverelationshipbetween
NdepositionandNavailabilitywasalsofound.
Whencomparingaspenandpineecosystems,agreateramountoftotalinorganic
Nwasfoundinpinesitesacrossallthreecanopycoverage.Thiswasexplainedbythe
physiological differences between aspen and jack pine, such as different N
requirement and uptake rates. Further experiments showed that the pine
ecosystemswerealsomoresensitivetotheadditionalNdeposition.AmoreopenN
cyclewasidentifiedinthepinestandsthanintheaspenstandsduetotheexcessive
soilNinputs.Intheend,HemsleyconcludedthatNisnota limitingnutrientinhis
reclaimed sites and more N demanding species should be planted to avoid N
leaching. Mackenzie and Quideau (2012) – Laboratory-based nitrogen mineralization andbiogeochemistryoftwosoilsusedinoilsandsreclamation: The objectives of this study include 1) determination and comparison of
nitrogenmineralizationrateconstantsbetweenpeatmineralmixedsoilandnatural
forest floor mineral mixed soil, which are two types of oil sands reclamation
materials,aswellas2)determinationoftheeffectofNPKfertilizationonmicrobial
communitystructureandnutrientprofiles.Peatandforestfloorsamplesweretaken
from a sphagnum (Sphagnum angustifolium) dominated peatland and an aspen
(Populusttremuloides)standintheAthabascaoilsandregiontocreatepeatmineral
soiland forest floormineral soil, respectively.Theauthorsmixed the two typesof
mixedsoils tocreateanothersample typeandaddedNPK fertilizer insomeof the
threesoiltypes.Nitrogenmineralizationratewasestimatedthroughmeasuringsoil
ammonium and nitrate nitrogen concentration (nitroprusside/salicylate and
cadmium reductionmethods). Phospholipid fatty acid analysis, ion exchange resin
analysis and MicroResp system were used to evaluate microbial community
structure,soilnutrientprofileandmicrobialrespirationrate,respectively.
Thenitrogenmineralizationrateinpeatmineralsoilfromlaboratoryincubation
was much higher than that in natural forest soils, while the rate in forest floor
27
mineralsoilwasatasimilarlevelasinnaturalLFHlayers.Themineralizationrates
ofallthreetypesofmixedsoilsinthisstudywereapproximatelyastwiceasfaster
than model estimated fast decomposition rate (84 mg N kg-1 yr-1). The
mineralizationratesofpeatmineralmixedsoilfromlaboratorytestwerewayfaster
thanthereportedfieldnitrogenmineralizationrates.
After four week of incubation in aerobic conditions, peat mineral soil
demonstrated the highest metabolic quotient (basal respiration/total microbial
biomass)but feweramountsof fungi inmicrobial compositioncompare tonatural
soils.Forestfloormineralmixshowedmoresimilarmicrobialcommunitystructure
as in natural soils. The effect of NPK fertilization on microbial structure was not
prominentwithoutvegetationpresencebutmightbearesultoftheshortincubation
time.
Basedontheresultsofionicexchangeresinanalysis,threetimeshighernitrogen
(mainly in nitrate form) content was found in peat mineral and peat forest floor
mixed soils than in forest floormineral soils. This large amount of nitrate in peat
mineralandmixedsoilsservesasanindicatorofhighernitrifieractivity,asreflected
bymoregram-negativebacteriafoundinthesesoils,butalsoimplieshighNleaching
potential. In contrast, additional N was retained as less leachable ammonium in
forestfloormineralsoil.Furthermore,astrongassociationbetweenrespirationand
nutrient availability was also found. In conclusion, Mackenzie and Quideau
recommendtheuseofbothpeatmineralandforestsoilandlayeringtheminsteadof
mixinginfutureoilsandsreclamationprocess,especiallyinN-deficientareas. Quideauetal.(2013)–Comparingsoilbiogeochemicalprocessesinnovelandnaturalborealforestecosystems: Quideau et al. studied a range of key soil biogeochemical attributes, such as
nutrient availability, organic matter composition and microbial communities in
reclaimed oil sand soils. A total of 41 sites (15 natural and 26 reclaimed) were
sampled for topsoils (top 0-10cm). In laboratory, nutrient bioavailability, soil
microbial communities andorganicmatter characterization in these topsoilswere
measuredbyusing incubatingplant root simulatorprobes,phospholipid fattyacid
28
analysisandNMRspectroscopy,respectively.
Inthisstudy,vegetationcoverwasthemostimportantfactorthatinfluencedthe
keybiogeochemical processes such asnutrient availability,microbial communities
andorganicmatter characteristics innatural sites, especially in coniferous stands.
After comparing the natural and reconstructed sites, Quideau et al. found much
greater amount of soil organic matter and dramatically different organic matter
chemicalcompositionsinreclaimedsitescomparetonaturalsites.Somedifferences
inthemicrobialcommunities(twouniqueunsaturatedPLFAs)andsomedifferences
in nutrient availability such as higher N and S concentrationswere also found in
reclaimed soils. The authors explained these differences mainly by the
characteristicsofmaterialsusedduring reclamationandabovegroundvegetation.
Inaddition,thecontentofbasecations(Ca,Mg,K)werefoundtobegoodindicators
of some specific ecosite groupings. In the end, since the responses of soil
biogeochemical attributes are very variable, Quideau et al. emphasized the
importance of considering the range of natural landscape variability and testing
more than a few soil biogeochemical attributes for effective reclaimed soils
assessment.
2.3SoilBiologicalProperties
Table3.BiologicalpropertiesanddescriptionsofreclaimedoilsandssoilsinAlberta,Canada.
Studies(Year)
Properties Findings
McMillanetal.(2007)
Microbialactivity
-LowerMBCandMBNwerefoundinreclaimedsoils-PositiverelationshipbetweendissolvedorganicN(DON)concentrationandinsituMBCandMBN-LowerDON,totalN,MBNfoundinreclaimedsites-Forestfloormixinreclamationmaterialhelpincreasingmicrobialactivity
Nitrogenmineralization(chemicalproperty)
-Similarlevelofgrossammonificationratesinreclaimedandnaturalsites-Lowernetammonificationratesinreclaimedsites
29
SoilpHlevel(chemicalproperty)
-Acidicinbothreclaimedandnaturalsoils,rangefrom5.38to5.95
Bulkdensity(physicalproperty)
-Highbulkdensityinreclaimedtopsoil
Soilmoistureand
temperature(physicalproperties)
-Lowersoilmoistureandhighertemperatureinreclaimedtopsoil
MacKenzieandQuideau(2009)
Microbialcommunitystructure
-Seasonandsiteconditionsappearedtobethemostandsecondmostinfluentialfactorofmicrobialcommunitystructure-Slopedidnotshowasignificanteffect-Totalsoilmicrobialbiomass(TMB)andsoilfungaltobacterialratio(FBR)weresignificantlyaffectedbytheinteractionoftimeandsitebutwithoutcleartrend
Nutrientavailability
-Siteconditionsandseasonwerefoundtobethemostandthesecondmostinfluentialfactorbyordinationanalysis-Slopedidnotshowsignificanteffectsonnutrientavailability -Ammoniumandnitrateconcentrationsweresignificantlyaffectedbytime,siteandtheirinteraction -Boronasanimportantmicronutrientincreasedlaterinthegrowingseason
Dimitriuetal.(2010a)
Microbialcommunitycompositionandfunctionin
peat
-Negativerelationshipbetweenrespirationratesandmicrobialabundance(dilutionlevel)-Positiverelationshipbetweenenzymeactivityandmicrobialabundance -Norelationshipbetweenmicrobialrichnessandmicrobialabundance-Highdegreeofmicrobefunctionalredundancy-Bothtaxonomicdiversityandtheinteractionsbetweenmicroorganismsintheinoculumsourcesandpeattypewouldaffecttherelationshipbetweenmicrobialcommunitycompositionandfunction
Dimitriuetal.(2010b)
Enzymeactivities
-Soilreconstructionmaterialinsteadoftime-since-reclamationaffectedenzymeactivitiesthemost
30
-Overburdenandtailingsandscausedsignificantdecreaseinphenoloxidaseactivity
Microbialcommunitycomposition
-Theuseofoverburdenandtailingsandsincreasedthedissimilaritiesofmicrobialcommunitywithnaturalsites-Fungal-to-bacterial-biomassratio,pHandwoodydebrisallsignificantlyinfluencemicroorganismsdistributioninreclaimedsites-Reclaimedsitesweregram-negativebacterialdominatedwhilenaturalssiteswereectomycorrhizaefungidominated-Successfuldevelopmentofmicrobialcommunityonreclaimedsoilsdependedindirectlyonvegetationregrowthconditionanddirectlyonsoilabioticproperties,suchaspHandreclamationmaterial
DimitriuandGrayston(2010)
Soilbacterialdiversity
-Similarbacterialcommunitycompositiondespitedifferentabovegroundvegetationcover-α-Proteobacteria,acidobacterialandbetaproteobacterialsequenceswerethetopthreedominatingbacterialsequences-SoilpHandsoilmoisturewerethemostregulatingfactorandindicatorofsoilbacterialcommunitycompositioninreclaimedandnaturalsoils,respectively-Reductioninthediversityofactivebacterialcommunitiescouldfurthercausedeclinesinbothrichnessandevennessofdominanttaxa.
Sorensonetal.(2011)
Soilorganicmatter
composition
-Carbonaccumulationoccurredsignificantlyonlyinreclaimedaspenstandsbutnotinpineandsprucestands
Microbialcommunities
-Verylowpresenceofvisiblefungalmyceliaandfinerootsoccurredinmostreclaimedsites,indicatinglowmicrobialactivities-Whencanopycoverwasbelow30%,soilmicrobialcommunitycompositionchangedaccordingtousedreclamationsubsoiltexture-Above30%,theeffectsofstandtypesoncompositionbecamemoreapparent
Forestfloordevelopment
-Reclaimedaspenandsprucestandshadthinnerforestfloorwhilereclaimedjackpinestandshadreachedsimilarthicknessasinnaturalstands-VerythinHlayerinallreclaimedstands-Canopycover(includeshrubcover)played
31
importantroleininfluencingforestfloorthicknessandsoilcarbonconcentration-StandAgewasalsobutonlyimportantinaspenstands
Onwuchekwa(2012)
Mycorrhizalcomposition
-Peat-mineralmixhadthehighestamountofEctomycorrhizal(ECM)colonizationbutquitelowArbuscularmycorrhizal(AM)colonization-TailingsandhadlowpotentialtosupportbothAMandECMmycorrhizalfungigrowth-Naturalforestsoilshadintermediateamountsofbothfungaltypes-OverburdenhadrelativelyhighamountofECMcolonizationbutlowAMcolonization-Pleosporalessp.,HelotialestypeandaspeciesthatcorrespondstothePyronemataceaewerethemostfrequentlyrecordedfungitaxa-ArtificialECMinoculationexperimentshowedincreasedstemvolumeforpineandspruce,increasedheightgrowthofpinebutnosuchheightresponseinspruceandincreasedsurvivalrateofsprucewhilenosuchresponseinpine.
McMillan et al. (2007) –Nitrogenmineralization andmicrobial activity in oil sandsreclaimedborealforestsoils: Theobjectiveof thisstudywas tocompare themicrobialactivityandnitrogen
mineralization among soils reclaimed with forest floor-mineral mix (LM),
peat-mineral mix (PM), a combination of the two (L/PM) and natural soils from
northernAlberta.Soilcoresweretakeninsiteswiththreedifferenttreatmentsand
natural sites. Net nitrification, ammonification, and N mineralization rates were
sampledfromfieldincubationsusingburiedbagsandestimatedby15Nisotopepool
dilutiontechnique.Inlaboratory,soilmicrobialbiomassC(MBC)andN(MBN)were
measuredbythechloroformfumigation-extractionmethod. Inaddition,amoisture
manipulationexperimentwasalsoconductedtofurtherinvestigatetherelationships
between soil moisture and respiration rates, MBC and MBN. Other basic soil
chemicalandphysicalproperties, suchasbulkdensity,moisture, temperatureand
pHlevelwerealsorecordedinthefield.
For basic soil properties, it was found that soil bulk density was higher in
32
reclaimed topsoil and explained by the compaction during reclamation process.
Lowertopsoilmoisturecontentandhighersoiltemperaturewasfoundinreclaimed
sites,whichmightbe causedby the lackof forest canopycover.All reclaimedand
naturalsiteshadacidicpHconditions(rangefrom5.38to5.95).
In terms ofmicrobial dynamics in reclaimed sites, lowerMBC andMBNwere
foundinreclaimedsoilscomparedtothenaturalsoils.Thismaybeattributedtothe
lower moisture content in reclaimed soils and/or differences in organic matter
compositions. A positive relationship between dissolved organic N (DON)
concentration and in situMBC andMBNwas also observed. However, despite the
higher DON, total N, MBN found in natural sites, gross ammonification rates in
reclaimed sites did not appear to be affected by reclamation disturbance. On the
otherhand,netammonificationdecreasedinreclaimedsites,whichindicatedeither
astrongerimmobilizingenvironmentorfasternitrificationrateatreclaimedsites.
The results ofmoisturemanipulation experiment confirmed that natural sites
hadmore activemicrobial activates than reclaimed sites did based on the higher
MBC and respiration rates (but similar MBN value as in the LM treatment). The
forest floor-mineralmix treatment generated the secondhighest respiration rates,
MBC and MBN, which made the author concluded that forest floor was a good
stimulatorofmicrobialactivitytohaveforoilssandsreclamation.MacKenzie and Quideau (2009) – Microbial community structure and nutrientavailabilityinoilsandsborealsoils: In this study, MacKenzie and Quideau tried to 1) determine the relationship
between microbial community structure changes and vegetation, seasonal and
annualvariability;2)understandtheeffectsoftopographyonmicrobialcommunity
structureandnutrientprofilesinreclaimedoilsandssoils.Threereclaimedsiteson
threedifferent slopes (upper,mid and lower)were selected for sampling in three
different years in approximately 60km north of Fort McMurray, northeastern
Alberta. Basic chemical and physical properties, microbial community structure
(PLFA analysis) andnutrient availability (PRSprobes)weremeasured for the soil
samplesfromeachsite.
33
Other thansiteorslopepositions, seasonsappeared tobe themost influential
factorofmicrobial communitystructuremost likelybecauseof thechanges in soil
moisture levels. For samples that were taken in the same season, site condition
became the second most important factor that influences microbial community
structurebecauseoftheeffectsofdifferentamountofvegetationcoveronsites. In
addition,both total soilmicrobialbiomass (TMB)and soil fungal tobacterial ratio
(FBR) were significantly affected by the interaction of sampling time and site
conditions but without clear trend. The effects of site and time interaction were
mainly explained by substrate differences, time since peat-mineralmix placement
and re-vegetation status. Surprisingly, slope did not have consistent effects on
reclaimedmicrobial community structure in this study,whichmight be causedby
undevelopedsoilstructure.
Intermsofnutrientavailability,sitesandseasonswerefoundtobethemostand
thesecondmostinfluentialfactorbyordinationanalysis.Again,slopehadnoeffects
on nutrient availability. Thesewere also explained by time since reclamation and
re-vegetation status. Ammonium and nitrate concentrations were significantly
affected by time, sites and their interaction because of the associated effects of
different vegetation cover on soil microbial communities. Boron, which is an
important micronutrient increased later in the growing season as a result of
continuingmicrobialactivities. Dimitriu et al. (2010a) – An evaluation of the functional significance of peatmicroorganismsusingareciprocaltransplantapproach:
Inordertoexaminetherelationshipbetweenmicrobialcommunitycomposition
andfunctionsuchasrespiration,nutrientacquiringandlignin-degradationinpeat,
Dimitriuetal. conducteda reciprocal transplantexperiment.Twodistinct typesof
sterile peat samples, humified (sedge) and coarse plant material (fibric) were
inoculatedwithserially-dilutedsuspensions(10-1,10-3,10-5and10-8)fromthesame
or reciprocal peats. After fivemonths of incubation, all active bacterial taxawere
labeled (nucleotide-analog technique), the peat’s functional potential and the
structures of active and total bacterial communities (PCR-DGGE) were also
34
measured.
In general, the findings showed a negative relationship between respiration
ratesanddilution levelsbutapositiveonebetweenenzymeactivitiesanddilution
levels. Bacterial richness was insensitive to dilution levels since most
microorganismscanregroweasilywhentheconditionisright.Furthermore,itwas
found that not only the inoculum source but also the peat type significantly
influenced the bacterial community structure and richness. Nevertheless, the
inoculum source and peat type did not influence active bacterial populations and
respiration rates, which implied a high degree of functional redundancy.
Furthermore, the authors also found that nutrient acquisition enzyme and
lignin-degrading activities were mainly affected by soil types and microorganism
community composition, respectively. It was concluded that both taxonomic
diversityandtheinteractionsbetweenmicroorganismsintheinoculumsourcesand
peattypeswouldaffecttherelationshipbetweenmicrobialcommunitycomposition
andfunction. Dimitriuetal.(2010b)–Impactofreclamationofsurface-minedborealforestsoilsonmicrobialcommunitycompositionandfunction: This study researched the impacts of soil reclamation and
time-since-reclamationonenzymeactivitiesandmicrobialcommunitycomposition
intheAthabascaoilsandsregion.Bulksoilinbothnaturalandreclaimedsitesthat
ranged from5 to 30 years old andused sevendifferent reclamationprescriptions
were sampled for extracellular enzyme activities (microplate assays) and
communitystructureanalysis(PLFAandDGGEanalysis).Inthefield,measurements
suchascarbon,nitrogen,pHandmoisturewere takenusingstandardmethods. In
addition,nutrientavailability(plantrootsimulatorprobes)andvegetationstructure
werealsorecorded.
The results from reclaimed sites with different ages suggested that soil
reconstructionmaterialinsteadoftime-since-reclamationaffectedenzymeactivities
themost.Theuseofoverburdenandtailingsands,whichhavelowcarboncontent,
caused significant decrease in phenoloxidase activities and increased the
35
dissimilarities of microbial community with natural sites (based only on PLFA
results)andconsequentlywerenotrecommendedforreclamationuse.Furthermore,
itwas foundthatdifferent factorscontrolledthedistributionofmicroorganismsin
reclaimedsitesandnaturalsites,whichwerefungal-to-bacterial-biomassratioand
soilnitrogen,respectively.However,ifallsiteswereanalyzedtogether,soilpHand
woody debris accumulation also played significant roles of shaping microbial
distribution in general, which implied vegetation development could influence
microbial community growth indirectly. Another difference between
microorganisms in reclaimed and natural soils was that reclaimed sites were
gram-negative bacterial dominatedwhile natural siteswere ectomycorrhizal fungi
dominated. Finally, the authors concluded that the successful development of
microbial community on reclaimed soils depended indirectly on vegetation
regrowth condition and directly on soil abiotic properties, such as pH and
reclamationmaterial. DimitriuandGrayston(2010)–Relationshipbetweensoilpropertiesandpatternsofbacterialβ-diversityacrossreclaimedandnaturalborealforestsoils: Dimitriu and Grayston tried to quantify the phylogenetic and compositional
diversity patterns of soil bacteria in reclaimed and natural siteswith two distinct
edaphiccharacteristics(xeric-poorandmesic-rich)intheAthabascaoilsandsregion.
Six sites (two xeric-poor, two mesic-rich and two reclaimed sites one with
vegetationandonewithout)werechosenforbulksoilsampling.Bacterialdiversity
under phylogenetic and species-based frameworks (16S rRNA-sequence-based
approach)andthecompositionofactivetaxa(nucleotideanalog)inreclaimedsites
weredetermined.
The two types of natural sites had more similar phylogenetic and taxonomic
diversities among bacterial communities compare to the reclaimed sites. The
composition of the bacterial communities in two reclaimed sites was also similar
despite contrasting vegetation covers. The α-Proteobacteria, acidobacterial and
betaproteobacterial sequenceswere the top three dominating bacterial sequences
foundinmostsites.Innaturalsites,soilmoisturewasthemostregulatingfactorthat
36
of soil bacterial community composition and explained 32% of the variance in
phylogenetic structure. However, in disturbed sites, soil pH, instead of vegetation
cover,wasfoundtobethemostinfluentialfactorofbacterialcommunitystructure,
which explained16 to34%of thevariability. In addition, soil pHwas also a good
indicator of soil bacterial richness (Chao1) and diversity (Shannon). In the end, it
was concluded that a reduction in the diversity of active bacterial communities,
whichwascloselylinkedto“master”variables(e.g.pH,moisture)inthisstudy,could
furthercausedeclinesinbothrichnessandevennessofdominanttaxa.
Sorenson et al. (2011) – Forest floor development and biochemical properties inreconstructedborealforestsoils:
Inthisstudy,Sorensonetal.evaluatedtheinfluencesofdifferentcanopycover
and three reclaimed stand types on novel soil organic matter composition, soil
microbial communities and forest floor development. The three stand typeswere
tremblingaspen(Populustremuloides),jackpine(Pinusbanksiana)andwhitespruce
(Piceaglauca)locatedinnorthofFortMcMurray,Albertaandallrangedbetween16
to 33 years old. A total of 32 sites (11 aspen, 11 spruce and 10 pine sites) were
established and surveyed for vegetation composition and forest floor parameters
suchas thicknessandmorphology.Soil sampleswerealsocollected for laboratory
analysisofcarbonandnitrogencontentsinmineralsoilsandforestfloor.Microbial
community composition was also estimated by various methods such as
phospholipid fatty acid (PLFA), ramped-cross-polarization (RAMP-CP) and 13C
nuclearmagneticresonance(NMR)analysis.
In contrast to aspen and spruce stands, which had thinner forest floor
development than reference natural stands, pine stands had already reached the
thickness similar to nearby natural pine stands at the time of study but mainly
becausetheaverageforest floorthickness innaturalpinestands is thinnerthan in
natural aspen and spruce stands. Morphologically, very low presence of visible
fungalmyceliaandfinerootsoccurredinmostsites,whichledtoabsentorverythin
H layers.Thesevery thinH layers indicated lowmicrobial activities. In aspenand
37
spruce stands, canopy cover played an important role in influencing forest floor
thicknessand soil carbonconcentration. Standagewasalsobutonly important in
theaspenstands,whichmaybearesultofthefasterestablishmentofcanopycover
in time. In addition to tree canopy, shrub canopy also had a positive relationship
withforestfloordevelopmentinconiferousstands.
Although carbon and nitrogen concentration increased in the aspen and pine
stands,thesignofnaturalcarbonaccumulation(changeinthelightfractioncarbon
composition) from regrown canopy was only clear in the aspen stands. Another
discoveryofthisstudywastherelationshipsamongreclamationprescription,stand
type,canopycoverandsoilmicrobialcommunitycomposition.Whencanopycover
was below 30%, soil microbial community composition changed according to
reclamationsubsoiltexture.However,above30%,theeffectsofstandtypesbecame
moreapparent.Therefore, theauthorssuggestedthatachieving30%canopycover
shouldbeacriticalthresholdpointduringsoilreclamationinoilsandsregions.
Onwuchekwa(2012)–EnhancedrevegetationandreclamationofoilsandsdisturbedlandusingMycorrhizae: Sincemycorrhizal fungi has the ability to increase vegetation reestablishment
success, Onwuchekwa assessed the natural mycorrhizal inoculum potential in
various oil sands reclamation materials, identified and characterized the fungal
strainsinreclamationmaterialsandconductedanotherexperimenttoevaluatethe
potential benefits of artificial ectomycorrhizal (ECM) fungi inoculation on white
spruce and jack pine seedling growth and survival. For the natural mycorrhizal
(Arbuscularmycorrhizal andectomycorrhizal) inoculumpotential assessment, five
different reclamation materials, including peat-mineral mix, overburden, tailing
sands,topsoilandintactforestsoil,werecollectedintheoilsandsminingareasnear
FortMcMurray, Alberta. Red clover (Trifoliumpretense) andwhite spruce (Picea
glauca)seedswereselectedastestingspeciesforthenaturalmycorrhizalinoculum
potential assessment. For artificial mycorrhizal inoculation (grow from Glucose
yeast) experiment, white spruce and jack pine (Pinus banksiana) were inoculated
with three different ECM species (Hebeloma crustuliniforme, Laccaria bicolor and
38
Suillus tomentosus). Seedling shoot and diameter growths and survival rateswere
collectedfromfieldobservation;biomasswasobtainedbycombustionmethod;and
mycorrhizal type was determined by DNA extraction and PCR amplification
methods.
The results of natural mycorrhizal inoculum potential reported very low
presencesofbotharbuscularmycorrhizal(AM)andECMfungiintailingsands.The
peat-mineral mix had the highest amount of ECM colonization but quite low AM
colonization probably because ECM can produce ectoenzymes to absorb excess
nitrogen in peat. Intact forest soil did not have the expected high amount of
mycorrhizal colonization but intermediate amounts of both types probably due to
the low diversity of replanted vegetation species. Overburden had relatively high
amountofECMcolonizationbut lowAMcolonization.Topsoilwas foundtobe the
most acceptable reclamation substrate since the amount of colonization of both
specieswasrelativelyhigh.
Inthisstudy,Pleosporalessp.,Helotialestypeandaspeciesthatcorrespondsto
the Pyronemataceae were the most frequently recorded fungi taxa and could be
found in topsoil, overburden, forest soil and tailing sands.These three species are
non-host specific in most cases. However, the author reminded us that the
developmentofmycorrhizalcouldbedramaticallydifferentingreenhouseandfield.
The results of artificial ECM inoculation experiment showed increased stem
volume for both species, increased height growth of jack pine but no such height
incrementinwhitespruce.Thismightbeattributedtositecharacteristicsandbetter
cooperationbetweenjackpinerootsandfungi.Inaddition,thesurvivalrateofwhite
spruceseedlingsdid improvedbymorethan10%possiblyduetohighermoisture
access. But no such increased survival rate was observed for jack pine possibly
because of non-indigenous fungi specie selection or site climatic conditions
favouring certain type of fungal species. In general, Onwuchekwa concluded that
re-introductionofmycorrhizalfungiduringreclamationprocesshasthepotentialto
becomeaneffectiveapproachtoimprovevegetationdevelopment.
39
2.4VegetationCommunities
Table 4. Some characteristics of vegetation community development on reclaimedoilsandssoilsinAlberta,Canada. Studies(Year)
Properties Findings
Cooper(2004)
Wetlandvegetation
-Planthealthandrootingdepthsinthereclaimedwetlandswereacceptable-Similarvegetationabundancebutdifferentspeciescompositionbetweenreclaimedandreferencewetlands-Salinityinsurfacewaterandsubsoils,wetlandisolationandharshclimaticconditionarethreelimitingfactorsofvegetationdevelopmentinreclaimedwetlandsandmayevenalterspeciesreplacementsequences
Lillesetal.(2009)
Aspenandwhitesprucegrowthonnatural
salinesoils
-Whitesprucegrowthwasunaffectedbythedifferentsalinitylevels -Aspengrowthwasreducedwithhighsalinity-Neitherwhitesprucenoraspenshowedevidenceofsalinity-relatedeffectsonrootdistributionandnutrientstressinfoliagedevelopment
Pinnoetal.(2012)
Aspengrowthanddevelopment
-Soiltype(mainlyorganicmattercontent)hadthelargestimpactonaspengrowthwhennofertilizerwasapplied.Buttheimpactdiminishedafterfertilization-Noimpactofsoiltypewasfoundonseedgerminationandseedlingestablishment-AspengrowthwasonlypositivelyrelatedtoincreasingKavailability-Incompletefertilizationmightgiveaspenanevenlowerbudsetthannofertilization
Kovalenkoetal.(2013)
Wetlandfoodwebstructure
-Reclaimedwetlandswerelowinmacrophytebiomass,microbialbiomass,trophicdiversityandinvertebraterichnessbuthighintheconcentrationofnaphthenicacidscomparetoreferencewetlands-Wetlandageandpeat-mineralmixdidnotsignificantlymitigatetheeffectsofoilsandswastematerialsontheaquaticbiotabutstillsomeimprovementinbiomassofmajorbioticcompartments-LowC:Nratiosinreclaimedwetlands
Copper(2004)–Vegetationcommunitydevelopmentofreclaimedoilsandswetlands: InCopper’sstudy,hetriedtoanswerwhetherchemicalandphysicalconditions
of reclaimedwetlandswould intervenewith vegetationdevelopment andwhether
natural colonization of local plant species would occur in reclaimed wetlands in
40
order to assess the effectiveness of natural recovery. He studied and compared
speciesrichness,aerialpercentcoverandsimilarityofthevegetationamonganewly
constructedconsolidated/compositetailings(CT)wetland,anaturalwetlandandan
opportunisticwetland for two years. Othermeasurements such asmetals, anions,
electricalconductivity,pHandtemperatureinwaterwerealsotaken.
The resultsofvisual assessmentsofplanthealthand rootingdepths in theCT
wetlandindicatedthatthephysicalandchemicalconditionsoftailingsdidnotlimit
plant growth and survival for most species. However, despite the similar species
abundances, the species compositions between reconstructed CT wetland and
referencewetlandswerequitedifferent.Thispartiallymightbecausedbythehigh
natural variability in water regimes in the reference wetlands. Some species
emergencewasinhibitedfromreclaimedwetlandsubsoilsduetohighsalinity.The
authorproposed that salinity in surfacewater and subsoils,wetland isolation and
harsh climatic conditions were the three most important limiting factors of
vegetation development in reclaimed wetlands and may even alter species
replacementsequences.Lilles et al. (2012) – Growth of aspen and white spruce on naturally saline sites innorthern Alberta: implications for development of boreal forest vegetation onreclaimedsalinesoils: Sincealotofreclaimedoilsandssoilshavehighsalinity,Lillesetal.investigated
theheightandbasalareagrowthsofmaturetremblingaspenandwhitespruceon
sixnaturalsitesacrossasalinegradient(high,medium,lowandcontrol)inorderto
predictfutureforestproductivityonreclaimedsalinesoilsinnorthernAlberta.Tree
growthratesofheightandbasalarea,rootdistributionsandfoliarparameterswere
collectedinthesesites.
It seemed that white spruce growth was unaffected by the different salinity
levelswhilematureaspengrowthwasreducedwithhighsalinity.Althoughmedium
andlowsalinesoilsprovidedfastaspengrowth,aspeninthehigh-salinitysiteshad
similargrowthratesinpest-andpathogen-stressedstands.Theeffectsofsalinityon
aspengrowthmight get even strongerwith time.Thedifferences inplantbiology,
41
such as shade-tolerance ability and natural growth rate variability, explained the
differencesbetweenaspenandwhitesprucegrowthsinresponsetosalinity.Neither
white spruce nor aspen showed evidences of salinity-related effects on root
distribution and nutrient stress in foliage development. In the end, the authors
concluded that aspen and white spruce could establish on saline soils with the
presence of organic matter layer and appropriate nutrient and moisture levels.
However, these stands shouldnot beused for forestryproductionpurposedue to
thelowproductivity. Pinnoetal.(2012)–Tremblingaspenseedlingestablishment,growthandresponsetofertilizationoncontrastingsoilsusedinoilsandsreclamation: This study used a greenhouse experiment to examine the complete cycle of
aspen growth and development on awide range of soil types. These soils all had
beenusedassurfacematerialsduringoilsandsreclamation.Eightdistinctsalvaged
stockpiles of soilwith a range in fertility, pH, organicmatter content and Pwere
used,whichwerepeat-mineralmix,forestfloor-mineralmix,Bhorizon-veryhighP,
Bhorizon-lowPandlowpH,Bhorizon-highPandlowpH,Bhorizon-lowPandhigh
pH, subsoils and tailing sands. Variables that were measured include seed
germinationandsurvivalratesaswellasheightgrowthbeforeandafterfertilization.
The results suggested that soil type had the largest impacts on aspen growth
whenno fertilizerwas applied. But the impacts diminished after fertilization. The
bestandworstaspengrowthwasfoundonsoilswithabundantorganicmatter,such
aspeat-mineralandforestfloor-mineralmix,andsoilswithloworganicmatter,such
assubsoilandtailingsands,respectively.Noimpactofsoiltypewasfoundonseed
germinationandseedlingestablishmentsinceconsistentwatersupplywasprovided
inthegreenhouse.
AlthoughN,PKappearedtoallbelowtheoptimal foliarconcentrations,aspen
growth was only positively related to increasing K availability. This is probably
becauseof the large imbalanceswithinthe internalN:Pratios.Surprisingly,aspen
growth did not response significantly to PK fertilization given the very low P
availability insomesoilsandthepositiverelationshipwithK.Anothernoteworthy
42
finding was that incomplete fertilizationmight give aspen an even lower bud set
thananofertilizationtreatment. Kovalenkoetal.(2013)–Foodwebstructureinoilsandsreclaimedwetlands: Kovalenko et al. aimed to firstly characterize the effects of oil sands process
materials(tailingsandwater)andpeat-mineralmixonfoodwebcompartmentsand
carbon flows in reconstructed wetlands and then evaluate the effects of
time-since-reclamation on wetland trophic structure. In order to do these, 17
naturallyformedreferencewetlandsand12oilsands-affectedwetlands,whichwere
constructedin1970to2004withtailingsandwater,wereselectedforaccessingthe
composition and biomass of aquatic plants and invertebrates (sweep nets and
floating hoop traps), microbial biomass (chlorophyll a concentrations and
combustionmethod),andfoodwebstructure(stableisotopedata).
The results indicated that reclaimed wetlands were significantly low in
macrophytebiomass,microbialbiomass,trophicdiversityandinvertebraterichness
but high in the concentration of naphthenic acids, which is a toxic constituent,
comparedwithreferencewetlands.Severalotherinorganiccompoundsinoilsands
process water, such as AL, AS, Cd, Mo and Se, also contributed to the observed
reduction in major biotic compartments but can be detoxicated with time more
easily compare to the naphthenic acids. Additionally, high salinity also interacted
with other stressors and propagated throughout the food web, causing lower
invertebrateandmacrophytebiomassesinreclaimedwetlands.
In terms of the effects of time-since reclamation and peat-mineral mix
amendment,therewasinsufficientevidencetoconcludethatwetlandageandpeat
couldmitigate theeffectsofoil sandswastematerialson theaquaticbiotadespite
peat’scomplexdirectandindirecteffectsonwaterquality.Buttheolderreclaimed
wetlandstendedtohaveslightlyhigherbiomassofmajorbioticcompartments,such
as benthic and planktonic invertebrates, and emergent macrophytes than the
youngerones.Lastly,theauthoralsopointedoutthatthelowerC:Nratiosfoundin
reclaimedwetlandscouldbeasignofnitrogenlimitation.
43
3.Discussion
3.1ReclamationTreatmentsEffects
Ingeneral,thereclaimedoilsandssoilsarequitedifferentfromnaturalsoilsin
many soil physical, chemical and biological properties. For starters, compare to
naturalborealforestsoils,highersoiltemperatureandlowermoisturecontentcould
be found in recently reclaimedsitesdue to lackof layer (McMillanetal. 2007). In
addition,organicmattercontentandorganicmatteraccumulationratewerefound
significantly different between reclaimed and natural forest sites in several
examinedstudiessuchasTritesandBayley2009,Quideauetal.2013andAnderson
2014. They all found much higher organic matter content and lower organic
accumulation rates in reclaimed soils compare to natural soils. These findings are
not surprising since large amount of peat was commonly used during the
reclamation process and many reclamation materials such as tailing sands and
overburdenpossessedadversechemicalproperties.However,inreclaimedwetlands,
Trites and Bayley (2009) found that input litter type instead of reclamation
materialswasthestrongerinfluencingfactorofdecompositionrate.Thecausesfor
thisdifferentresponsebetweenwetlandsandforestsrequirefurther investigation.
Possible candidates of the causes might be different microbial communities
compositionand/ordifferentmicrobialactivitieslevels.
Bulkdensitywas also found to be higher in reclaimed soils due to equipment
compactionduringreclamationbyMcMillanetal.2007.Surprisingly,Yarmuch2003
found a contrasting result of lower bulk density in reclaimed topsoil compare to
natural Ae horizon. This could be attributed to some low-impact reclaimed
techniques that the oil sands companies adopted, such as lightweight equipment,
wheeled and tracked equipment and letting the reclaimed materials be frozen
beforehand.Thesecontrastingresultsofbulkdensitydemonstratedthepotentialof
preventingsoilcompactionwithcareful low-impactmanagementandthenecessity
ofpromotingthesetechniques.
Forchemicalproperties,thehighernitrogen(N)contentinreclaimedsoilisthe
44
mostprominentdifferencecomparetonaturalsoilsassupportedbyRowland2008,
Hemsley2012,MacKenzieandQuideau2012andKovalenkoetal.2013.Thismight
be attributed to the higher atmospheric nitrogen deposition in reclaimed soils,
whichiscausedbythelowercanopycovers(Hemsley2012;MacKenzieandQuideau
2012). Nevertheless, in contrast to those studies, McMillan et al. (2007) found a
lower totalN and lowernetnitrogenmineralization rate in reclaimed forest soils.
The reason might be that MacKenzie and Quideau (2012) obtained the N
mineralizationratesresultsonly forpeat-mineralmixandforest-floormineralmix
soils. And these results were from laboratory inoculation instead of filed
measurements. The real field Nmineralization rate can be suppressed due to the
adverse chemical conditions created by other reclamation materials such as
overburdenandtailings.
Intermsofmicrobialcommunities,morebacterialandlessfungiwerefoundin
reclaimedsoilscomparetonaturalsoils(Dimitriuetal.2010b;Sorensonetal.2011).
McMillanetal.(2007)foundlowermicrobialbiomassCandmicrobialbiomassNin
reclaimedsoils,which implied lowermicrobialactivity.Thismightbe theresultof
theslightlyhigherpHlevelinreclaimedsoils(Rowland2008)sincemultiplestudies
showedthatsoilmoistureandpHarethetwomostimportantfactorsthatshapesoil
microbial community structure in reclaimed soils (Mackenzie and Quideau 2009;
Dimitriuetal.2010b;DimitriuandGrayston2010).Amoreconcerning fact is that
the negative effects of reclamation materials on microbial enzyme activities can
persistevenafterthesitesbecameold(Dimitriuetal.2010b).
The vegetation communities of reclaimed forest andwetlands appeared to be
growingbutnotas goodas innatural sites. Inwetlands,different compositionsof
species were found between natural wetlands and reclaimed wetlands (Cooper
2004). Kovalenko et al. (2013) also found low macrophyte biomass, microbial
biomass, trophic diversity and invertebrate richness due to the relatively high
chemicalpollutantlevelsinreclaimedwetlands.
Lastly, somemitigatingeffectsof timewereobserved in a fewstudies suchas
Rowland2008,Sorensonetal.2011andKovalenkoetal.2013.Althoughvegetation
45
communitiesand forest floor inaspenappear tobeable toachievesimilarnatural
stages approximately 25 years after reclamation, some more resistant soil
propertiesliketextureandtheforestfloorinconiferforests,whichhavelessorganic
matterinputs,willnotbeabletorecovertothepre-disturbancestateevenafter20
years.
3.2ReclamationandManagementImplications
Otherthantheaforementionedlow-impactreclamationtechniques,manyother
reclamationandmanagementlessonscanbelearnedbasedontheresearchresults,
namely:
1. Topsoil was found to be themost acceptable reclamation substrate in
terms of mycorrhizal fungi growth supporting ability. The use of
overburden and tailing sands should be minimized and/or carefully
planneddue to their lowability to supportenzymeactivitiesand fungi
growthaswellastheirpotentialtoincreasedissimilaritiesofmicrobial
communitycompositionsbetweennaturalandreclaimedsoils(Dimitriu
etal.2010b;Onwuchekwa2012)
2. Theuseofforestfloorduringreclamationasanorganicamendmentcan
improve soil nitrogen mineralization rate (McMillan et al. 2007;
MacKenzieandQuideau2009).Layeringthepeat-mineralmixandforest
floor mineral mix soil instead of mixing them is also recommended
(MacKenzieandQuideau2009).
3. Complete fertilization is necessary for aspen stands growth since
incomplete fertilizationmight give reclaimed aspen stands even lower
budsetthananofertilizationtreatment(Pinnoetal.2012).Goodaspen
growthrequiresbothorganicmatterandKfertilization.
4. Aspenandwhitesprucecouldestablishonsalinesoilswiththepresence
of organic matter layer and appropriate nutrient and moisture levels.
However, these stands will not be suitable for commercial forestry
productionpurposebecauseofthelowproductivity(Lillesetal.2009).
46
5. For faster organic quality improvement, aspen can be planted in
reclaimed sites since reclaimedaspen standshad fasterdecomposition
ratesandbettercarbonaccumulationthanreclaimedjackpineandwhite
sprucestands (Sorensonetal.2011).However, forareasneeds thicker
forestfloor,jackpineispreferredthanaspenandwhitespruceduetoits
lowdecompositionrate(Sorensonetal.2011).
6. Sincenitrogenisexcessive inmanyreclaimedsites,moreNdemanding
speciescanbeplantedtoavoidNleaching(Hemsley2012),
7. The results of artificial ecotomycorrhizal fungi inoculation experiment
showed increased stem volumes for pine and spruce, increased height
growth for pine and increased survival rate of spruce (Onwuchekwa
2012).Therefore,assistingthereintroductionofecotomycorrhizalfungi
inreclaimedsitesshouldbeencouragedifcommerciallyavailable.
8. Bettersalinitycontrolmightbeneededinwetlandreclamationbecause
salinityisstillanimportantlimitingfactorofvegetationdevelopmentin
reclaimedwetlandsandmayevenalter species replacementsequences
(Cooper2004).
9. Reclamationmonitoring programmayuse carbon concentration in the
low-density fraction as indicator of SOM quality in reclaimed sites
because of it relates to many other organic attributes (Turcotte et al.
2009).
3.3LimitationsandFutureResearches
Althoughmostofthestudies(15outof20)inthisreportwasconductedby(or
involvedwith)UniversityofAlberta,universities inneighboringprovinces suchas
University of British Columbia (UBC) and University of Saskatchewan are also
conducting or conducted many researches about the soil properties in Albert’s
reclaimed oil sands regions. Therefore,manymore studies are being finished and
publishedeveryyear.Forinstance,onemasterthesisthatstudiestherelationships
betweenvegetation types and soil carbon is just about to finish inUBC.Given the
47
large amount of researches, this paper definitely will not be able to cover all
publishedstudiesandfuturepublicationsonthepropertiesofreclaimedsoils.
Another major limitation of this study is the absence of statistical analysis.
Researchesofreclaimedsoilspropertiesvaryinmethodsandresults.Thecausesof
thesevariancesandsomeevencontradictingresultscanonlybespeculatedwithout
properstatisticalanalysis.Both limitationscall forthenecessityofameta-analysis
on reclaimed soils properties since meta-analysis allows researchers to
simultaneouslystudymultiplefactorsofaparticularissueacrossabroadscaleand
findthehiddentrends(ArnqvistandWooster1995).
Other thanmeta-analysis, sincemany researches have built the foundation of
basicphysical,chemicalandbiologicalpropertiesofreclaimedoilsandssoils,more
researches may start to shift toward some second- and third-order effects of
reclaimedsoils.Forexample,more indepth investigationonvegetationresponses,
localhydrologychangeandwildlifepopulationbehaviorandrecoveryinreclaimed
standsallcanberesearchedinthenearfuture.
Lastbutnotleast,Ifoundthatmanyresearchesthatstudiedtheeffectsoftime
on reclaimed soil properties used earlier sampled soils as their reference soils.
Includingtheoriginalsamplesofreclamationmaterialsattimezerowhenpossibleis
recommended for future time-effect researches since the time-zero samples may
providemoresoundandeffectiveevidencesof for theeffectsof timeonreclaimed
soilproperties.
48
ReferencesAlbertaEnvironmentalProtection.1998.Thefinalfrontier:protectinglandscapeand
biologicaldiversitywithinAlberta'sborealforestnaturalregion.ProtectedAreasReportNo.13.AlbertaEnvironmentalProtection.Edmonton,AB.
AMECEarthandEnvironmentalandParagonSoilandEnvironmentalConsultingInc.,
2005.Resultsfromlong-termsoilandvegetationplotsestablishedintheoilsandsregion,OilSandsSoilandVegetationWorkingGroup.
Anderson,J.2014.Organicmatteraccumulationinreclaimedsoilsbeneathdifferent
vegetation types in theAthabascaoil sands,M.Sc.Thesis,FacultyofForestry,UniversityofBritishColumbia.
Arnqvist,G.andD.Wooster.1995.Meta-analysis:synthesizingresearchfindings in
ecologyandevolution.TrendsinEcology&Evolution10:236-240.CanadianBorealInitiative.2003.Theborealforestatrisk:aprogressreport.Fourth
anniversaryofcompetingrealities:theborealforestatriskbytheSenatecommitteeonagricultureandforestry.
CumulativeEnvironmentalManagementAssociation(CEMA)2009.Guidelinesfor
reclamationtoforestvegetationintheAthabascaoilsandsregion,2ndEdition.AlbertaEnvironment,Edmonton,Alberta.
CanadianBorealInitiative.2005.Theborealinthebalance:securingthefutureof
Canada'sborealregion.http://www.borealcanada.ca/documents/Boreal_in_the_Balance_Full.pdf(Accessed02/13/2015).
CanadianOilSandsNavigator.2015.Keyoilsandsprojects.
http://navigator.oilsandsreview.com/listing(Accessedon02/01/2015).Chastko,P.A.2004.DevelopingAlberta’soilsands:fromKarlClarktoKyoto.
UniversityofCalgaryPress,Calgary,Alberta.CumulativeEnvironmentalManagementAssociation(CEMA).2006.Landcapability
classificationsystemforforestecosystemsintheoilsands,3rdEdition.AlbertaEnvironment,Edmonton,Alberta.
Cooper,N.J.2004.Vegetationcommunitydevelopmentofreclaimedoilsands
wetlands.M.Sc.Thesis,DepartmentofRenewableResources,UniversityofAlberta.
49
Danielson,R.M.,S.VisserandD.Parkinson.1983.Plantgrowthinfouroverburdentypesusedinthereclamationofextractedoilsands.CanadianJournalofSoilScience63:353–361.
DimitriuP.A.,D.LeeandS.JGrayston.2009.Anevaluationofthefunctional
significanceofpeatmicroorganismsusingareciprocaltransplantapproach.SoilBiology&Biochemistry42:65-71.
Dimitriu,P.A.andS.JGrayston.2010a.Relationshipbetweensoilpropertiesand
patternsofbacterialβ-diversityacrossreclaimedandnaturalborealforestsoils.MicrobialEcology59:563-573.
Dimitriu,P.A.,C.E.Prescott,S.A.QuideauandS.J.Grayston.2010b.Impactof
reclamationofsurface-minedborealforestsoilsonmicrobialcommunitycompositionandfunction.SoilBiology&Biochemistry42:2289-2297.
Fung,M.Y.P.andT.M.Macyk,2000.Reclamationofoilsandsminingareas.In:R.I.
Barmhisel,R.G.DarmodyandW.L.Daniels(Eds.).Reclamationofdrasticallydisturbedlands.AgronomyMonographno.41.AmericanSocietyofAgronomy.Madison,WI.
GovernmentofAlberta.2013.Oilsands-factsandstatistics.
http://www.energy.alberta.ca/OilSands/791.asp(Accessedon02/13/2015).Grant,J.,S.DyerandD.Woynillowicz.2008.Factorfiction:oilsandsreclamation.
ThePembinaInstitute. HardyBBTLtd.1990.Naturalplantinvasionintoreclaimedoilsandsminesites.
AlbertaLandConservationandReclamationCouncilReportRRTAC90-3.Hemsley,T.2012.Ecologicalresponseofatmosphericnitrogendepositionon
reconstructedsoilsintheAthabascaoilsandsregion.M.Sc.Thesis,DepartmentofRenewableResources,UniversityofAlberta.
HrudeyS.E,P.Gosselin,M.A.Naeth,A.Plourde,R.Therrien,G.V.D.KraakandZ.Xu.
2010. Environmental and health impacts of Canada’s oil sands industry. TheRoyalSocietyofCanada.
Hunter, A. 2011. Investigation of water repellency and critical water content in
undisturbedandreclaimedsoilsfromtheAthabascaoilsandsregionofAlberta,Canada,M.Sc.Thesis,DepartmentofSoilScience,UniversityofSaskatchewan.
50
Leatherdale,J.D.,2008.SoilmoistureandnutrientregimesofreclaimeduplandslopesintheoilsandsregionofAlberta,M.Sc.Thesis,DepartmentofRenewableResources,UniversityofAlberta.
Li,X.andM.Y.P.Fung.1998.Creatingsoil-likematerialsforplantgrowthusing
tailingssandandfinetails.JournalofCanadianPetroleumTechnology37:44–47.
Liles,E.B.,B.G.Purdy,S.E.MacdonaldandS.C.Chang.2012.Growthofaspenand
whitespruceonnaturallysalinesitesinnorthernAlberta:implicationsfordevelopmentofborealforestvegetationonreclaimedsalinesoil.CanadianJournalofSoilScience92:213-227.
Mackenzie D. 2011. Best management practices for conservation of reclamation
materials in the mineable oil sands region of Albert. Best ManagementPractices Task Group of the Reclamation Working Group of the CumulativeEnvironmentalManagementAssociation,FortMcMurray,AB.
MacKenzie, M.D. and S.A. Quideau. 2010. Microbial community structure and
nutrientavailabilityinoilsandsreclaimedborealsoils.AppliedSoilEcology44:32-41.
NacKenzie,M.D. andS.A.Quideau.2012.Laboratory-basednitrogenmineralization
and biogeochemistry of two soils used in oil sands reclamation. CanadianJournalofSoilSciences92:131-142.
McMillan, R., S.A. Quideau, M.D. MacKenzie and O. Biryukova. 2007. Nitrogen
mineralizationandmicrobialactivityinoilsandsreclaimedborealforestsoils.JournalofEnvironmentalQuality36:1470-1478.
Mossop,G.D.1980.GeologyoftheAthabascaoilsands.Science207:145-152. OilSandsVegetationReclamationCommittee.1998.Guidelinesforreclamationto
forestvegetationintheAthabascaoilsandsregion.AlbertaEnvironmentalProtection–EnvironmentalService,Edmonton.
Onwuchekwa,N.E.2012.Enhancedrevegetationandreclamationofoilsand
disturbedlandusingMycorrhizae,M.Sc.Thesis.DepartmentofRenewableResources,UniversityofAlberta.
Pinno,B.D.,S.M.Landhausser,M.D.MacKenzie,S.A.QuideauandP.S.Chow.2012.
Tremblingaspenseedlingestablishment,growthandresponsetofertilizationoncontrastingsoilsusedinoilsandsreclamation.CanadianJournalofSoilScience92:143-151.
51
Quideau,S.A.,M.J.B.Swallow,C.E.Prescott,S.J.Grayston,andS.W.Oh.2013.
Comparingsoilbiogeochemicalprocessesinnovelandnaturalborealforestecosystems.Biogeosciences10:5651-5661.
RegionalAquaticsMonitoringProgram(RAMP).2015.Insitumethodsusedintheoil
sands.http://www.ramp-alberta.org/resources/development/history/insitu.aspx(Accessedon01/27/2015).
RenaultS,C.Lait,J.J.ZwiazekandM.MacKinnon.1998.Effectofhighsalinitytailings
watersproducedfromgypsumtreatmentofoilsandstailingsonplantsoftheborealforest.EnvironmentalPollution102:177–184.
Rowe, J. S. 1972. Forest regions of Canada. Department of the
Environment/CanadianForestServicePublicationNo.1300.Information. Rowland, S.M., 2008. Recreating a functioning forest soil in reclaimed oil sands in
northern Alberta, M.Sc. Thesis, Faculty of Forestry, University of BritishColumbia.
Rowland, S.M., 2008. Recreating a functioning forest soil in reclaimed oil sands in
northern Alberta, M.Sc. Thesis, Faculty of Forestry, University of BritishColumbia.
Rowland, S.M., C.E. Prescott, S,J, Grayston, S.A. Quideau and G.E. Bradfield. 2009.
RecreatingafunctioningforestsoilinreclaimedoilsandsinnorthernAlberta:an approach for measuring success in ecological restoration. Journal ofEnvironmentQuality38:1580-1590.
Sorenson,P.T., S.A.Quideau,M.D.MacKenzie, S.N. Landhausser andS.W.Oh.2011.
Forest floordevelopmentandbiochemicalproperties inreconstructedborealforestsoils.AppliedSoilEcology49:139-147.
Stolte,W.J.,S.L.BarbourandC.D.Boese.2000.Reclamationofsaline-sodicwaste
dumpsassociatedwiththeoilsandsindustry.In:Globallandreclamation/remediation2000andbeyond.ProceedingsoftheCanadianLandReclamationAssociation's25thAnnualMeeting,September17-20th2000,EdmontonAlberta.
Trites,M.andS.E.Bayley.2009.Organicmatteraccumulationinwesternboreal
salinewetlands:Acomparisonofundisturbedandoilsandswetlands.EcologicalEngineering35:1734-1742.
52
Turcotte,I.,S.A.QuideauandS.W.Oh.2009.Organicmatterqualityinreclaimedborealforestsoilsfollowingoilsandsmining.OrganicGeochemistry40:510-519.
Visser,S.1985.Managementofmicrobialprocessesinsurfaceminedland
reclamationinwesternCanada.InTateIII,R.andD.A.Klein(Eds).Soilreclamationprocesses:microbialanalysesandapplications,MarcelDekker,Inc.
Vitt,D.H.,L.A.Halsey,I.E.Bauer,andC.Campbell.2000.Spatialandtemporaltrends
incarbonstorageofpeatlandsofcontinentalwesternCanadathroughtheHolocene.CanadianJournalofEarthScience37:583-693.
Yarmuch,M.2003.Measurementofsoilphysicalparameterstoevaluatesoil
structurequalityinreclaimedoilsandsoils,Alberta,Canada,M.Sc.Thesis.DepartmentofRenewableResources,UniversityofAlberta.