Carbon dioxide balance assessment of the city of Florence (Italy), and implication for urban planning

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ContentslistsavailableatScienceDirect

Landscape

and

Urban

Planning

j o ur na l h o me p a g e:w w w . e l s e v i e r . c o m / l o c a t e / l a n d u r b p l a n

Carbon

dioxide

balance

assessment

of

the

city

of

Florence

(Italy),

and

implications

for

urban

planning

Francesco

Primo

Vaccari

a,∗

_,

_Beniamino

_Gioli

a

_,

_Piero

_Toscano

a,c

_,

_Camilla

_Perrone

b a_Institute_of_{Biometeorology}_(IBIMET),_National_Research_Council_(CNR),_Via_G._Caproni,_8,₅₀₁₄₅_Florence,_Italy

b_Department_of_Urban_and_Regional_Planning_(DUPT),_University_of_Florence,_Via_P.A._Micheli,_2,₅₀₁₂₁_Florence,_Italy c_Department_of_Agricultural_and_{Environmental}_Sciences,_University_of_Udine,_Via_delle_Scienze,_206,₃₃₁₀₀_Udine,_Italy

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g

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l

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g

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t

s

•Florence’sgreenareasoffsetCO2emissionsfrom2.6%(winter)to16.9%(spring).

•SpatiallyCO2emissionsdecreaseby92%alonganurbantorurallandscape.

•Carbondioxidebalanceprovidesinnovativeinformationtoolforurbanplanning.

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Articlehistory: Received9August2012

Receivedinrevisedform9August2013 Accepted10August2013

Keywords:

Carbondioxideﬂuxes Eddycovariance Urbandesign Urbantransect

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b

s

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ThecarbondioxidebalancefortheMunicipalityofFlorence(102.3km2_),_with_29.1_km2_of_green_space withinthebuilt-upcityand46.6km2_in_the_semi-rural_peri-urban_area,_shows_that_collectively_the_green spacesoffset6.2%ofthedirectcarbonemissions.Howeverthegreenspacesinthedenselybuilt-upcity onlyoffset1.1%oftheemissions.13.5ktCO2y−1aretakenupbyvegetationinthebuilt-upareasand 58.7ktCO2y−1byvegetationintheperi-urbanarea.Urbangreenspacesaremostefﬁcientinoffsetting anthropogenicCO2emissionsduringtheperiodMarchtoJunewhenplantgrowthratesarehighand emissionratesarerelativelylow.Landscapefragmentationishighlypositivelycorrelatedwithtotal CO2 emissionsandnegativelycorrelatedwithCO2uptake.Thedetailedinformationproducedduring thisinvestigationshowsthatpoliciesaimedatreducingCO2emissionsinwintermonthswillhavea greateroveralleffectontotalCO2releasetotheatmospherethanthoseaimedatincreasingCO2uptake. Nevertheless,urbandesignersshouldconsiderallthebeneﬁtsofurbangreenspacesandseektoensure thatnewsuburbandevelopmentconservesgreenspacesandaimsatsustainableurbandesign.

1. Introduction

Urbanareas, deﬁned asdensely developed residential,

com-mercialandothernon-residentialareas,cover aminuteportion

of the Earth’s land surface (<3%), but host more than 50% of

thepopulation(CIESIN,2004), thuscontributing signiﬁcantlyto

globalanthropogenicemissionsofgreenhousegases(GHG)tothe

atmosphere(Dhakal,2010).To mitigatesuchemissions,several

strategiesaimedatimprovingtheurbanenvironmentecological

performance have beenproposed and adopted duringthe past

decade:improving the energy efﬁciency of buildings (Aydin&

Cukur,2012);reducingroadtrafﬁc(Reckien,Ewald,Edenhofer,& Ludeke,2007);managinganddesigningexistingandnewurban

greenspaces(Patakietal.,2011).

∗ Correspondingauthor.Tel.:+390553033711;fax:+39055308910. E-mailaddresses:f.vaccari@ibimet.cnr.it(F.P.Vaccari),b.gioli@ibimet.cnr.it (B.Gioli),p.toscano@ibimet.cnr.it(P.Toscano),camilla.perrone@uniﬁ.it(C.Perrone).

Therole of urbangreenspaces, deﬁned asallareas covered

bylawns,shrubsandtrees,inhighlyhumanalteredecosystems,

iswellrecognized(Dobbs,Escobedo,&Zipperer,2011).Thereis

asigniﬁcantamountofscientiﬁcliteratureunderliningthe

ben-eﬁtsofurbangreenspacesinreducingtheurbanheatislandby

creatingacoolingeffect(Hu&Gensuo,2010;Ng,Chen,Wang,&

Yuan,2012;Oliveira,Andrade,&Vaz,2011;Onishi,Cao,Ito,Shi, &Imura,2010;Petralli,Massetti,&Orlandini,2011;Steeneveld, Koopmans,Heusinkveld,vanHove,&Holtslag,2011),orinterms

ofavoidedcarbonemissionsandenergyuseduetothecoolerair

temperature(Lin,Wu,Zhang,&Yu,2011);reducingairpollution,

particulatesandgases(Morani,Nowak,Hirabayashi,&Calfapietra,

2011;Nowak,Crane,&Stevens,2006;Paoletti,Bardelli,Giovannini, &Pecchioli, 2011; Tallis, Taylor,Sinnett, & Freer-Smith,2011);

ﬁlteringnoiseandenhancingthequalityoflife,intermsof

psycho-logicalwell-beingofthecitizenswholiveclosetothegreenareas

(Chiesura, 2004; Gidlöf-Gunnarsson & Öhrström, 2007; Hartig, Evans,Jamner,Davis,&Garling,2003).

Themagnitudeoftheseeffectsdependsmainlyonintrinsic

fac-torsrelatedtourbangreenspacessuchas:surfacearea,vegetation

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structure(woody,shrubs,herbaceous),speciescomposition and

locationoftreesinrelationtothebuildings(Akbari,2002;Mirzaei&

Haghighat,2010),andonextrinsicfactorssuchaslatitude,climate,

weatherandtypicalurbanforms ofthecities(Sproken-Smith&

Oke,1998;Upmanis&Chen,1999).

Onewell-recognizedeffectofurbangreenspacesistheir

contri-butiontomitigateGHGemissionsbymeansofatmosphericcarbon

dioxide(CO2)uptakethroughplantphotosynthesis.Several

stud-ieshavequantiﬁedtheCO2sequesteredandstoredbyurbangreen

spaces(Escobedo,Kroeger,&Wagner,2011;Jo&McPherson,1995;

McHale,McPherson,&Burke,2007;Nowak&Crane,2002;Zhao, Kong,Escobedo,&Gao,2010),andthelong-termdirect

measure-mentsofCO2 ﬂuxesareacknowledgedtoolstoassessthespatial

and temporal variability of CO2 uptake and emission in cities

(Grimmond,King,Cropley,Nowak,&Souch,2002).

Eddycovarianceisamicrometeorologicaltechniquethat

meas-ures the surface-atmosphere exchange of mass, energy and

momentum,and is utilized since decades toassess the carbon

exchange of natural and cultivated areas, contributing toward

understandingthespatialandtemporalvariabilityofecosystems

productivity and their role in theglobal carbon cycle (Keenan

etal.,2012).Theeddycovariancetechniquehasbeenalsorecently

applied in urban and suburban areas (Crawford, Grimmond, &

Christen,2011;Giolietal.,2012;Helfteretal.,2011;Kordowski &Kuttler,2010;Patakietal.,2009;Pawlak,Fortuniak,&Siedlecki, 2010;Velasco&Roth,2010),allowingdirectcarbonﬂuxesofcities

withdifferentlandscapeorurbancharacteristicstobeassessed.

InthisarticlewecomputetheCO2balanceofthe

Municipal-ityof Florence(emissions-uptakes)byassessingthecapacity of

urbangreenspacesofoffsettingthedirectanthropogenicCO2

emis-sionsthroughcarbonuptake.Florencewaschosenasacasestudy,

becausehighspatialresolutioninventorialdataareavailableand

CO2 emissionsofthecitycenteraremeasuredwitheddy

covari-ancesince2005(Matese,Gioli,Vaccari,Zaldei,&Miglietta,2009).

The total direct CO2 emissions of thecity have been obtained,

combiningmeasuredCO2 emissionswiththeRegionalEmission

Inventory(IRSE).Moreover,usingdifferentweb-GISdatabaseswe

determinedthesurfaceareasofthevariouscategoriesofurban

greenspacesinthecity,andapplyingtheIPCCmethodology(IPCC,

2003,2006)weassignedanannualCO2uptakefactortoeachurban

greenspacecategory.Therelativeimportanceofabsorbedvs.

emit-tedCO2hasbeenassessedbothtemporally,bymeansofseasonal

patternsprovidedbydirecteddycovarianceﬂuxmeasurements

inurban(Florence)andinaMediterraneanforest(Lecceto,Siena)

environments,andspatially,bycomputingtheCO2 balanceover

differentareasrangingfromdenselyurbantorurallandscapes.

Thepaperaimsto:(i)estimatethemagnitudeofthe

anthro-pogenicCO2emissionsoftheMunicipalityofFlorenceandofthe

urbangreenspacesCO2uptake;(ii)investigatesourceandsink

spa-tialvariabilityathightemporalresolutionandtheirimplicationsfor

urbanplanning.

2. Materialsandmethods

2.1. Studyarea

Florence(Lat43◦46N;Long11◦ 15 E)(Fig.1),hasatypical

medievalheartandtherenaissancecitywasbuiltontheruinsofa

Romantown,inarivervalleysurroundedbyhills.The

Municipal-ityextendsover102.3km2_,_with_a_total_surface_area_of_urban_green

spacesof75.7km2_formed_by_two_main_categories:_those_in_densely

built-upzones,deﬁnedhereasUrbanGreenareas(UG)

extend-ingover29.1km2_,_and_Peri_Urban_green_areas_(PU),_deﬁned_here

asurbanareasoflow-densityhousingextendingover46.6km2_.

Inadditiontothesetwomaincategories,therearealsoatotalof

11,541isolatedUrbanTrees(UT),manyofthemalongavenuesand

streets.Theyinclude8326trees,manageddirectlybythe

Munici-pality(UTMF),and3215treesownedbyotherpublicinstitutionsor

byprivate(UTO).

TheUGareascanbeclassiﬁedintwomaincategories:those

managed by the Municipality of Florence (UGMF=7.7km2), for

whichadetaileddatabaseofmorphometricparametersisavailable,

andthoserepresentedbyparksandurbangreenspacesmanaged

byotherpublicinstitutionsandbyprivate,deﬁnedhereasother

urbangreenspace(UGO=21.4km2).

ThePUareas surroundingthecityare: agriculturalﬁeldson

thevalleyﬂoor,typicallyhorticulturalwithapredominant

com-ponentofherbaceousplants(PUH)andextendingoveratotalarea

of9.5km2_;_agricultural_ﬁelds_on_the_hills_around_Florence,_typically

orchards,vineyardsandsparseolivetreeswithapredominant

com-ponentofwoodyplants(PUW),extendingoveranareaof33.4km2;

naturalforests(PUF)extendingover3.7km2.

AccordingtotheFlorenceMasterPlanthetotal urbangreen

spaces willbeenhanced by2.3km2 _(UG

SP),and28,450isolated

urbantrees(UTSP)willbeplantedorreplaced.

Thetypesofurbangreenspacesandtreenumbershavebeen

obtainedbyoverlappingdifferentGISlayersoftheMunicipalityof

Florence(Opendatahttp://datigis.comune.ﬁ.it)(Fig.2).In

particu-lartheweb-GISsuppliedlayersfortheUGMFandUTMFcategories,

thattheywerecreatedin1990withthepurposeofmanagingthe

urbangreenspaces.Theselayersarecontinuouslyupdatedandthey

providedsomefundamentalinformationforourresearch,suchas

plantspeciescompositionineachtypeofarea,theageofthetrees,

andmorphometricinformationsuchasdiameteratbreastheight

(DBH).Theotherurbangreenspacecategoriesweredetermined

byoverlappingtheGISlayersprovidedbytheFlorenceMasterPlan

thattakealltheothercategoriesintoaccount;unfortunatelythese

GISlayersdidnotprovidedetailedinformationaboutplantspecies.

Allthemapscreatedwiththisoverlappingweresubsequently

val-idatedthroughdigitalorthophotos.

2.2. TheIRSEdata

TheIRSEemissiondatabaseisbasedontheCorinair

methodol-ogy(EEA,2007)andwasdevelopedbytheRegionalAdministration

ofTuscany(IRSE,2010).Itcontainsyearlyamountsofpollutants

emittedsince1995,spatiallydisaggregatedat1km2_resolution,_on

thebasisofspatialproxiesofemissionintensity.Emissionsources

areclassiﬁedaccordingtotheEuropeanstandardnomenclature‘97

calledSNAP(SelectedNomenclatureforAirPollution),andinclude

threecategories:(i)diffuse:thatarenotlocalized,butdistributed

ontheterritory;(ii)punctual:that aregeographicallylocalized;

(iii)linear:relatedtolinearinfrastructuresuchasroadsand

rail-waylines.Inourstudy,byoverlappingtheadministrativeborders

oftheMunicipalityofFlorencewiththeIRSEspatializeddata,we

determinedtheannualdirect CO2 emissions(Fig.3).In practice

weconsideredonlytheCO2emissionswithinthecityboundaries

(Scope1,deﬁnedbyKennedyetal.,2010)andrecentlyadoptedin

theGlobalProtocolforCommunity-ScaleGreenhouseGas

Emis-sions (C40 & ICLEI, 2012C40, ICLEI, World Resources Institute,

2012).

2.3. UrbanandforestCO2ﬂuxmeasurements

Twoeddycovariancesiteshavebeenusedinthisstudyto

mea-sureCO2ﬂuxes.TheﬁrstwasinstalledinSeptember2005atthe

Ximeniano Observatory(Lat43◦ 47 N;Long11◦ 15 E)(Fig.1),

inthecitycenterwhereﬂuxesareentirelygovernedby

anthro-pogenicemissions,consideringthelackofgreenspaceintheﬂux

footprint(Mateseetal.,2009).ObservedCO2ﬂuxesaretherefore

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Fig.1. MapofItalyshowingthelocationoftheMunicipalityofFlorenceandthemediterraneanLeccetoforest(Si).IntheaerialphotographofFlorenceareshownthered startoindicatetheXimenianoObservatorysite,andtheurbantransect,dividedinsixsectionsfromT1toT6torepresentacontinuumfromurbantorural.

(Giolietal.,2012).ThesecondwasinstalledinJune2005inthe

Lec-cetoMediterraneanforest(Lat43◦18N;Long11◦16E)(Fig.1),a

holmoakcoppiceof20yearsage,located70kmsouthofFlorence

andextendingoveranareaofabout9km2_._Mean_canopy_height

is8.6mwithameantreeDBHof9.0cmanddensityof2948trees

ha−1,whilemeanannualNetEcosystemExchange(NEE)is−13.2

(±3.7)tCO2ha−1y−1(Magno,Gioli,Vaccari,&Canfora,2010),

rep-resentingaCO2sinkfromtheatmosphere.Bothtowers,whichare

stilloperating,usetheacquisitionprocedureindicatedbyMatese

etal.(2008)andadoptthesameﬂuxdataprocessingmethodology (Baldocchi,2003).

2.4. UrbangreenspacesandurbantreesCO2uptake

Usingthedetailedinformationaboutsurfaceareas,typeofgreen

space,species compositionandmorphometricmeasurementsof

thesingle trees, provided by the Municipality,we assigned an

annualCO2uptakefactorforUGMFandUTMF categories,through

ananalysisoftheliteratureandusingtheGuidelinesoftheIPCC

(IPCC,2003,2006),whichprovideatieredstructureofmethods

withvaryingdegreesofcomplexity.TheseCO2uptakefactorswere

thenappliedtootherurbangreenspacecategories:UGO,UTO,UGSP

andUTSP.

TheUGMFisformedbyfourcategories:Lawn,Forest,Mixed

Veg-etationandLawnwithShrubs,andforeachcategoryweassigned

aCO2 uptakefactor(Table1).ForLawncategoryweadoptedthe

valueof4.3tCO2ha−1y−1,correspondingtothevaluefortheannual

NetPrimaryProductionofGrasslandoftheWarmTemperate–Dry

ClimateZone(Chapter3.4–IPCC,2003).ForForestcategorywe

adoptedthevalue of 5.8tCO2ha−1y−1 determinedin a speciﬁc

case study using the Cascine Park in Florence (Paoletti et al.,

2011).For MixedVegetation,deﬁnedas anareawithtrees and

shrubs,and Lawn withShrubs categories, we addeda value of

0.07tCO2ha−1y−1asthecontributionoftheshrubs,accordingto

Zirkle,Lal,Augustin,andFollett(2012,chapter14,part3),tothe

previousuptakefactoridentiﬁedforLawnandForest.

Since2002,intheMunicipalityofFlorencedatabase,eachtree

hasbeenidentiﬁedand classiﬁedin termsof botanicalspecies,

geographicalpositionandmorphometricmeasurements.

TodeterminetheCO2 uptakefactorforthetreecategorywe

appliedthefollowingequation,(IPCC,2003):

CO2=

(CO2(t2)−CO2(t1))

(t2−t1)

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whereCO2=carbondioxidecontentdifference.CO2(t2)=carbon

dioxidecontentreferredtotime2.CO2(t1)=carbondioxidecontent

referredtotime1.t2=time(2011)t1=time(2006).

TodeterminetheCO2contentoftheurbantrees,asrequiredfor

inEq.(1),weusedtheStockChangeMethod(IPCC,2003)applying

thefollowingequationforeachplantgenus:

Ctot=(V×D×BEF)×(1+R)×CF (2)

where Ctot=total carbon (above+below biomass). V=tree

vol-ume,m3_._D₌_wood_density,_t_m−3_._BEF₌_Biomass_Expansion_Factor.

R=Root-to-ShootRatio.CF=carbonfractionofthedrybiomass.

Thetreevolume(V)wasdeterminedconsideringtheDBHvalues

foreachplantgenus,usingdendrometrictablesatsingleentry(CRA,

1980).Thewooddensities(D),foreachplantgenus,wereobtained

usingthevalues indicatedforItalybyFAO(2005); weusedthe

valuesof1.3forconiferspeciesand1.4forbroadleafspeciesasBEF

(IPCC,2003),whilefortheCFweusedthestandardvalueof0.5 (IPCC,2003).

TheaverageCO2uptakefactorpertree,determinedfollowing

theaboveprocedure(Table2),wasthenusedtoevaluatethetotal

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Fig.2.Urbangreenspaces(uppermap)andurbantrees(lowermap)oftheMunicipalityofFlorence.

Table1

CategoriesoftheUGMF,withindicationsaboutthetotalsurface(ha),theCO2uptakefactor(tCO2ha−1y−1)andthetotalCO2uptakeperyear(tCO2y−1).

Categories Surface(ha) (%) CO2uptakefactor(tCO2ha−1y−1) TotalCO2uptake(tCO2y−1)

Lawn 562.3 73.0 4.3 2417.9

Forest 84.79 11.0 5.8 491.8

Mixedvegetation 79.75 10.4 5.9 470.5

Lawnwithshrub 43.16 5.6 4.4 189.9

770 100 3570.1

Table2

Plantgenus,numberoftreespergenus,numberofobservationsofdiameteratbreastheight,CO2increment(tCO2y−1)andCO2incrementpertree(tCO2y−1tree−1)ofthe

10generaofthetreesmanagedbytheMunicipalityofFlorenceandusedtodeterminetheCO2uptakefactorpertree.

PlantGenus Commonname No.trees No.obs. CO2Incr.(tCO2y−1) CO2Incr.pertree(tCO2y−1tree−1)

1 Tiliaspp.L. Lindentree 8621 10,559 357.8 0.0415

2 Quercusspp.L. Oaktree 8097 9048 105.8 0.0131

3 Cupressusspp.L. Cypresstree 8034 8683 244.6 0.0304

4 Celtisspp.L. Europeannettletree 6765 8178 166.4 0.0246

5 Pinusspp.L. Pinetree 5219 6748 344.7 0.0660

6 Platanusspp.L. Planetree 4415 6580 124.2 0.0281

7 Acerspp.L. Mapletree 3626 2119 28.8 0.0079

8 Oleaspp.L. Olivetree 3539 2907 12.1 0.0034

9 Ulmusspp.L. Elmtree 2148 3303 76.6 0.0357

10 Fraxinusspp.L. Ashtree 2087 1213 16.6 0.0079

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Fig.3.DirectcarbondioxideemissionsoftheMunicipalityofFlorenceexpressedas ktCO2y−1.

The CO2 uptake factor of 5.0tCO2 ha−1y−1 was chosen for

PUHaccordingtotheresultsofCeschiaetal.(2010),who

evalu-ated,throughtheeddycovariancetechnique,thegreenhousegas

budgetsof15cropsitesacrossEurope,coveringalargeclimatic

gradientandawiderangeofagriculturalmanagementpractices.

ForthePUWweappliedaCO2uptakefactorof14.7tCO2ha−1y−1

according to Sofo et al. (2005), who evaluated the dry matter

accumulation and partitioning in the different plant organs of

Mediterranean orchards, and for the PUF, we applied the CO2

uptakefactorof13.2tCO2ha−1y−1measuredbytheeddy

covari-ancetowerinstalledontheLeccetoMediterraneanforest.

2.5. Urbantransect

Anurbantransectof6kminlengthwasdeﬁnedfromFlorence

citycentertotheeasternperi-urbanarea,formedby6sectionsof

1kminlengthand0.5kmwidth,toassessthespatialvariability

ofsomelandscapemetricsindicesandcomparewithCO2

emis-sions(Fig.1).Thedirectionofthetransectwaschosenbecauseitis

representativeoftheaveragedistributionofthelandcoverclasses

foundintheMunicipality(datanotshown).Theﬁrstsection(T1)

wassetinthecitycenterclosetotheXimenianoObservatoryand

thelastsection(T6)intheperi-urbanarea.Foreachsection,3

land-scapemetricindiceshavebeendetermined,classifyingthelanduse

in8classes:urbanized(built-up,residential);urbaninfrastructure

(streets,communication/utilities,railwaystations,cemeteries)and

thepreviouslydeﬁnedtypesofurbangreenspaces(UGMF,UGO,

UGSP,UTMF,UTO,UTSP).Theindices,determinedineachsection

ofthetransect,are:thePlandindex(Pland),indicatingthearea

percentageofeachlandusetypewithrespecttototal area;the

Shannon’sevennessindex(SHEI),indicatingthedegreeofevenness

amongpatchtypes;thepatchrelativedensity(PRD),indicatingthe

numberofpatchesineachsection.

3. Results

3.1. CO2uptake

The total urban green spaces of the Municipality of

Flor-enceuptake 72.5(_±18.2)ktCO2y−1;ofthese,13.5ktCO2y−1 are

taken up by the UG (UGMF+UGO), 58.7ktCO2y−1 by the PU

(PUH+PUW+PUF); and 0.3ktCO2y−1 by the UT (UTMF+UTO).

-50 0 50 100 150 200 250 kt CO 2 uptakes emissions -5 0 5 10 15 20 25 30 1 2 3 4 5 6 7 8 9 10 11 12 %

Month of the year

offset capacity

A

B

Fig.4. (A)MonthlyCO2anthropogenicemissions(blackline)andurbangreen spacesuptakes(grayline)errorsbarsrepresent95%conﬁdenceintervalsofthe aver-ages;(B)Monthlyoffsettcapacity(absolutepercentagevalue)oftheurbangreen spaceswithrespecttoCO2emissions.

Almost80%ofthetotalCO2 uptakebytheurbangreenspacesis

duetothePUareas,witha predominantcontributionfromthe

orchards,olivetreesandgrapevinesonthehillsaroundthecity.

FortemporaldisaggregationoftheCO2uptakeweusedtheCO2

ﬂuxmeasurementsmeasuredattheLeccetosite(Fig.4).Ona

sea-sonalbasis,theLeccetoforestisahighercarbonsinkduringspring

andearlysummer,while itbecomesa net,smallcarbon source

duringmid-summer.Thisseasonalpatternisknowntobetypical

ofmostMediterraneanecosystemsthatarewaterlimitedduring

thesummerandonaverageabout83%oftheannualcarbonuptake

oftheLeccetoforestoccursfromJanuarytoJune.

3.2. CO2emissions

Florence’sdirectCO2emissionshavebeencomputedbymeans

oftwoinformationsources:theIRSEinventorialyearlyemission

databasespatiallydisaggregatedat1km2_resolution_and_the_eddy

ﬂuxsitelocatedinthecitycenter.Eddycovariancedatahavebeen

usedintwoways:(i)todirectlyvalidateIRSEinventorialdataat

thelocationofthetower;(ii)toprovideatemporalemission

pat-ternatmonthlyscale,whichcanbeappliedtoyearlyinventorial

datatoobtaina monthlyemission trend.Wefoundarelatively

goodagreementbetweentheCO2emissionsmeasuredattheurban

ﬂuxtower(309±42tCO2ha−1y−1),andthecorrespondingpixel

extractedbytheIRSE(255tCO2ha−1y−1),thatjustiﬁesusingIRSE

dataontheentireMunicipalityofFlorence,revealingatotaldirect

anthropogenicCO2emissionof1161.5(±136)ktCO2y−1.The

sea-sonalpatternofdirectCO2emissionsmeasuredattheXimeniano

Observatorywasusedfortemporaldisaggregationofthe

invento-rialestimates,demonstratingthatthemonthlydirectemissionsof

thecityarehighestduringthewinter(DecemberandJanuary)and

lowestduringsummer(JulyandAugust),accordingtodomestic

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Fig.5.Theurbantransectfromurbantorurallandscape.Foreachsectionsthepiechart.representthePlandIndex,wherethegreenisthepercentageofurbangreenspaces andthegrayisthepercentageoftheurbanizedareas.Plandindexwasreferredtothesectionsurfaceequalto0.5km2_.

3.3. CO2balance

Withina carbonbalanceperspective, thetotal sinkofurban

greenspacesoftheMunicipalityofFlorenceoffset6.2%ofthetotal

directanthropogenicCO2 emissions.Ofthis,1.1%ismadebythe

UGand5.1%bythePU.WhenincludingtheFlorenceMasterPlan

scenariointhebalancecomputation,theoffsetcapacityofurban

greenspacesgrowsto6.4%.Thetimedisaggregationonamonthly

scale(Fig.4),revealsthattheurbangreenspacesaremoreefﬁcient

inoffsettingthedirectanthropogenicCO2emissionsduringMarch

(11.2%),April(23.3%),May(16.3%)andJune(26.2%),asthesearethe

mostproductivemonthsassociatedtorelativelylowanthropogenic

emissions.

3.4. Urbantransect

ThePlandindexrevealsaclearpatternofthelevelof

urbaniza-tionofthecity:T1andT2havethehigherpercentageofurbanized

area,onaveragemorethan50%;T3andT4haveapproximatelythe

samepercentageofurbanizedandurbangreenspaces;whileinT5

andT6,thepercentageofurbanizedareaislessthan10%(Fig.5).

SHEIindexhasalmostthesamevaluealongtheurbantransect,

andconsideringthatitrangesfrom0(completelyunevenlandscape

distribution)to1(completelyeven),everypatchclassabundance

isofthesamemagnitude(Fig.6A).Thesectionoftheurbantransect

thatshowsthelowestvalueoftheSHEIindexisT1,whiletheone

withthehighestvalueisT5.

Thepatchrelativedensity(PRD),whichisanindicatorof

land-scapefragmentation,exhibits.

A positive correlation (r=0.89) with total CO2 emissions

(Fig. 6B), and negative correlation (r=−0.85) with CO2 uptake

(Fig.6C).PRDvaluesarehigherincorrespondancetothesectors

closertothecitycenter(T1andT2),while theyarenot

signiﬁ-cantlyaffectedbytheforecastinterventionsplannedintheFlorence

MasterPlan(Fig.6C).

4. Discussions

The total annual CO2 uptake by the urban green spaces of

theentireMunicipalityofFlorenceoffsets6.2%ofthetotaldirect

anthropogenicCO2 emissions.Thisisquitehigh,withrespectto

otherurbanareas.Escobedo,Varela,Zhao,Wagner,andZipperer

(2010),usedﬁeldmodeledandspatialdataonurbantreesto

ana-lyzetheCO2sequesteredbytreescomparedtothetotalemissions

oftwosubtropicalAmericancities,GainesvilleandMiami-Dade,

withtheresultthattheurbantreesoffsetonly3.4%and1.8%.The

highervalueofFlorenceisduetoacombinationoftwofactors:(i)

weconsideronlythedirectemissionstotheatmosphereinstead

oftotal;(ii)thedistributionoftheurbangreenspaces,the

major-ityofwhicharelocatedinthePUarea.Infact,ifwecomputethe

offsettingcapacitynotconsideringthePUcontributionweobtain

avalueof1.1%.Theseresultspointoutthatparticularattention

mustbetaken inurbanplanningtopreservePUCO2 offsetting

capacity,alsobecausenewlybuiltareaswilloccupyPUsurfaces,

asindicatedbytheFlorenceMasterPlan.Thisfollowsan

urbaniza-tionmodelfoundalsoinRome(Salvati,Munafo,GargiuloMorelli,

&Sabbi,2012),whichhasevolvedinthelastdecades,froma

“com-pactgrowthmodel”toa“dispersemodel”(Schneider&Woodcock,

2008).

TheapplicationoftheIPCCmethodologytoestimatethe

mag-nitudeof CO2 uptake enablestherole ofurbangreen spacesin

theurbancarbonbalancetobequantiﬁed.ThemeanannualCO2

uptakeforurbanlawnsusedinthisstudyiscomparablein

magni-tudetothatindicatedbyConant,Paustian,andElliott(2001)and

QianandFollett(2002),whoestimatedthatlawnshaveapotential

CO2 uptakerateof3.6tCO2ha−1y−1anditisalsocomparableto

theuptakefactorspublishedbyJoandMcPherson(1995).

The mean CO2 uptake factor per tree appliedin this study

(26kgCO2tree−1y−1)iscomparablewiththeﬁndingsofNowakand

Crane(2002),whoreportedaCO2uptakefactorrangingfrom12.2

to21.2kgCO2tree−1y−1.Moreoverinarecentstudydoneonthe

CascinePark,thelargestgreenareainFlorencethatcovers118ha,

usingtheUFOREmodel, ameanannual uptakefactor hasbeen

determinedof33.8kgCO2tree−1y−1(Paolettietal.,2011).TheDBH

datausedinourstudy,providedbytheMunicipalityofFlorence,

allowedtoustoruleouttheeffectoftheinter-annualvariability

oftreegrowth.Infact,eveniftheexactdatesoftheDBHdata

sam-plingsarenotknown,ourcalculationsarebasedonalargenumber

ofsamplestakenduringeachyearfrom2006to2011,withmore

than9800DBHmeasurementsperyearonaverage.

Thetemporaldisaggregationoftheemissionsanduptakesof

thecity(Fig.4)representsanewlevelofinformationthatmaybe

usedtoestimatetheefﬁcacyofinterventionsandpoliciesaimedat

reducingCO2emissionsandenhancingCO2uptakes.Themaximum

efﬁciencyofurbangreenspacestooffsetemissionsisduringspring

anditisverylowduringwinterandsummermonths.Theinefﬁcacy

ofthegreenspacesduringthesetwoseasonsisrelated:forthe

wintermonths,tohighCO2emissionsduetothedomesticheating

andthelowerairtemperaturethatlimitsplantcarbonuptake,and

forthesummerperiod,tolackofwaterandhighairtemperatures

thatinhibitcarbonuptake,eventhoughtheCO2emissionsduring

summerarelowerthaninotherseasonsoftheyear.Withinthis

perspective,policiesaimedatdecreasingCO2emissionsinwinter

monthswillbemoreefﬁcientthanthoseaimedatincreasingCO2

uptake,whichstillremaincontrolledbyenvironmentalfactorssuch

asairtemperatureandprecipitation.

Weextractedasub-setofourCO2balanceresultsonanurban

transect taking into account a recent application of the

tran-secttheorydeveloped byurbandesignersnamed “SmartCode”

(www.smartcodecentral.org).Thishasrecentlybeenadoptedasthe

cornerstoneofarenewedsustainabledesignvariouslyaddressed

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Fig.6. (A)Shannon’sevennessindex(SHEI)calculatedforeachsectionsoftheurban transectconsideringtheactualpatchesdistribution(SHEI,grayssymbols)andthe patchesdistributionifalltheinterventionsforecastbyMasterPlanwillbedone (SHEI+PS,blacksymbols).(B)Actualpatchrichnessindex(PRD)graybars,andthe totalCO2emissions(tCO2y−1)blacksymbols,foreachsectionsoftheurbantransect. (C)ActualPRDindexgraybars,andfuturePRDindex(PRD+PS,whitebars)with thenewpatchesoftheMasterPlanandtheactualCO2uptake(tCO2y−1)(Uptakes, blacksymbols),andthefutureCO2uptake(tCO2y−1)(Uptakes+PS,graysymbols anddottedline).

GrowthManual(Duany,Speck,&Lydon,2009),Landscape

Urban-ism (Waldheim, 2006), New Urbanism (Katz, 1994); Ecological

Urbanism(Mostafavi&Doherty,2010)andSustainableUrbanism

(Farr,2007).TheanalysisofFlorence’surbantransectrepresents

an attempt to merge a landscape analysis with a quantitative

carbonbalanceanalysis.SHEIindexalong thedifferentsections

indicatesthatthecitycenterisunbalancedcomparedtotheT5,

whichexhibitsthebestperformanceswithhighestSHEIindex.The

FlorenceMasterPlanwillenhancetheSHEIindexinmostofthe

sec-tions,contributingtobalancethedistributionofclasspatchesinthe

urbantransect(Fig.6A).Thefragmentationofpatchesinthe

vari-oussectionsshowsagoodagreementwiththetotalCO2emissions

y = 0.098x + 34.461 R = 0.77 y = 0.0177x + 73.985 R = 0.03 0 100 200 300 400 500 600 700 0 20 40 60 80 100 120 0 100 200 300 400 500 600 700 800

Number of tree per section (n°)

Urban green area per section (%)

CO2 uptakes (tCO2 y-1_{) per section}

Urban green area Tree y = 0.1055x + 31.551 R = 0.81 y = -0.2776x + 300.73 R = 0.16 0 100 200 300 400 500 600 700 0 20 40 60 80 100 120 0 100 200 300 400 500 600 700 800

Number of tree per section (n°)

Urban green area per section (%)

CO2 uptakes (tCO2 y-1) per section

Urban green area + UPS Tree + UPS y = 0.0068x - 8.4953 R = 0.91 0 10 20 30 40 50 60 70 80 0 2000 4000 6000 8000 10000 12000 14000

Urbanized area per section (%)

CO2 emissions (tCO2 y-1) per section

C

A

B

Fig.7.Directcarbondioxideemissionsanduptakepersectionoftheurbantransect. (A)Actualurbangreenspaces(blacksymbolsandline),vsactualCO2uptakes(tCO2 y−1₎_on_left_axis_and_actual_total_number_of_urban_trees_(open_symbols,_dotted_line); (B)ForecasturbangreenspacesassumoftheactualandforecastareaoftheMaster Plan(blacksymbolsandline),vsforecastCO2uptake(tCO2y−1)onleftaxisand forecasttotalnumberofurbantreesassumofUTMF,UTOandUTPS(opensymbols, dottedline);C)Urbanizedareapersection(graysymbolsandblackline)vsthedirect carbondioxideemissions(tCO2y−1).

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(Fig.6B),conﬁrmingthatthisfragmentationisrelatedtotheCO2

emissions,probablythroughthepercentageofbuilt-upareas.The

relationsreportedinFig.7A–CbetweenCO2uptake/emissionand

green/urbanizedareasrepresentaninnovativeapproachtomerge

alandscapeanalysiswithaquantitativeenvironmentalanalysis,

capableofevaluatingtheefﬁcacyoftheFlorenceMasterPlan,and

thatcouldbeappliedinotherurbanareasofthecity.

Therelationsbetweenthesumofthepercentageof

continu-ousgreenareas(sumofthecategoriesUGMF,UGO,PUH,PUWand

PUF)andthetotalCO2uptakebyeachsectionoftheurban

tran-sectforboththeexisting(Fig.7A;R2₌_0.77)_and_future_green_area,

accordingtotheFlorenceMasterPlan(Fig.7B;R2₌_0.81),_clearly

demonstratethatthemaindriverfortheCO2uptakeineachsector

isrepresentedbythecontinuousgreenareasinsteadofthetotal

numberoftrees(Fig.7A;R2₌_0.03_and_Fig.₇_B;_R2₌_0.16)._Moreover,

thecorrelationbetweenthetotalurbanizedarea,deﬁnedhereas

thesumofthepatchesclassiﬁedasurbanized(built-up,

residen-tial),urbaninfrastructure(streets,railwaystationsandcemeteries)

andthetotalCO2 emissions(tCO2y−1)foreachsection(Fig.7C;

R2₌_0.91),_demonstrates_that_the_percentage_of_urbanized_area_in

eachsectoristhemaindriverfortheCO2emissions.

5. Conclusions

Thereisageneralneedtoincreaseknowledgeabouttheroleof

urbangreenspacesinoffsettingGHGemissions,inparticularwith

thedirectmeasurementsofcarbonuptakeandemissioninurban

environments,asrecentlypointedoutbyPatakietal.(2011).The

approachappliedinthisstudyisa combinationofeddy

covari-anceobservationsinurbanandnaturalenvironments,inventorial

emissiondataandcarbonstockassessmentmethodsprovidedby

IPCC(2003,2006)thatmighteasilybeappliedinothercities.The

totalCO2emissionsoffsettingcapacityoftheurbangreenspaces

oftheMunicipalityofFlorence,excludingthecontributionofthe

PUareas,isverylow(1.1%).Withinacarbonbalanceperspective,

insteadofincrementingtheefﬁcacyofurbangreenspacesto

bal-anceCO2emissions,theimplementationofmeasuresforreducing

theCO2emissionscouldprovidebetterresults.Moreoverour

cal-culationsonlyconcernthedirectCO2emissions,andifconsidering

alsoindirectemissionsinafullcarbonbalanceperspectivethe

off-settingcapacitywouldbeevenlower.TooffsetthetotaldirectCO2

emissionsofthecitymorethan880km2_of_natural_forest_would

benecessarywiththesameecophysiologicalcharacteristicsasthe

LeccetoMediterraneanforest,correspondingtoapproximately8

timestheentiresurfaceareaoftheMunicipality.Thisfactmight

encouragere-thinkingtheroleofurbangreen spaces,thathave

alotofbeneﬁcialeffects,suchasreducingtheurbanheatisland,

reducingairpollution,particulatesandgases,ﬁlteringnoiseand

enhancingthewell-beingofthecitizenswholiveclosetothegreen

areas.QuantiﬁcationoftheCO2uptakebyurbangreenspacesmight

beusefultotheurbanplannerformanagingthe“freecityspace”

concept(Odum,1971),deﬁnedasspaceintheurbanterritory

cov-eredbygreen.Theargumentsofthisworkmightofferscientiﬁc

supporttothoseurbanpoliciesaimedatlimitingthedemandfor

land,ontheonehand,andcontainingthedensiﬁcationofsuburbs,

ontheother.Theurbangreenspaceshaveseveraldifferentroles,

includingtheoffsettingcapacityofanthropogenicCO2emissions

analyzedinthisstudy,thatshouldbecarefullyconsideredbyurban

plannersanddesignerstoeffectivelycontributetothedevelopment

ofasustainableurbandesign.

Acknowledgements

The authors would like to acknowledge the contributions

of:AlessandroMatese,FrancescoSabatiniandAlessandroZaldei

(IBIMET-CNR),fortheirvaluabletechnicalassistanceinthe

man-agement of the eddy covariance ﬂux towers. Ramona Magno

(ConsorzioLaMMA)isacknowledgedforprovidingtheIRSE

Inven-tory data. A special thanks to: Emilio Borchi and Renzo Macii

of the Fondazione Osservatorio Ximeniano (Fi); Emanuela Lupi

and Marisa Sabbia of the Municipality of Florence; the

Lab-oratory on Climate, Sustainability and Security Infrastructure

(CEST)forproviding somefundamentalinstrumentsinstalledin

theurbanﬂux tower.Thispapercontributes toBRIDGEProject

(www.bridge-fp7.eu), fundedbytheEuropeanCommission.The

authorswouldliketothanktheanonymousreviewersfortheir

valuablecommentsandsuggestionstoimprovethequalityofthe

paper.

References

Akbari,H.(2002).ShadetreesreducebuildingenergyuseandCO2emissionsfrom powerplants.EnvironmentalPollution,116,119–126.

Aydin,M.B.S.,&Cukur,D.(2012).Maintainingthecarbon–oxygenbalancein resi-dentialareas:Amethodproposalforlanduseplanning.UrbanForestry&Urban Greening,11(1),87–94.

Baldocchi,D.(2003).Assessingtheeddycovariancetechniqueforevaluatingcarbon dioxideexchangeratesofecosystems:Past,presentandfuture.GlobalChange Biology,9,479–492.

C40, ICLEI, World Resources Institute. (2012). Global protocol for community-scale greenhouse gas emissions. , http://www.ghgprotocol.org/ ﬁles/ghgp/GPCPilotVersion1.0May201220120514.pdf

Ceschia,E.,Béziat,P.,Dejoux,J.F.,Aubinet,M.,Bernhofer,C.h.,Bodson,B.,etal. (2010).ManagementeffectsonnetecosystemcarbonandGHGbudgetsat Euro-peancropsites.Agriculture.EcosystemsandEnvironment,139,363–383. Chiesura,A.(2004).Theroleofurbanparksforthesustainablecity.Landscapeand

UrbanPlanning,68(1),129–138.

CIE (Center for International Earth Science Information Network). (2004). GlobalRural-UrbanMappingProject (GRUMP)alpha version:Urban extents., http://sedac.ciesin.columbia.edu/gpw.

Conant,R.T.,Paustian,K.,&Elliott,E.T.(2001).Grasslandmanagementand conver-sionintograssland:Effectsonsoilcarbon.AppliedEcology,11,343–355. CRA. (1980). Annali dell’Istituto Sperimentale per l’Assestamento Forestale

e per l’Alpicoltura, (Annals of the Institute for Experimental Forestry Management and Alpine farming, Agricultural Research Council). Con-siglio per la Ricerca e la Sperimentazione in Agricoltura (CRA). http://mpf.entecra.it/ﬁles/annali/Volume6.pdf.

Crawford,B.,Grimmond,C.S.B.,&Christen,A.(2011).Fiveyearsofcarbondioxide ﬂuxesmeasurementsinahighlyvegetatedsuburbanarea.Atmospheric Environ-ment,45,896–905.

Dhakal,S.(2010).GHGemissionsfromurbanizationandopportunitiesforurban carbonmitigation.CurrentOpinioninEnvironmentalSustainability,2,277–283. Dobbs,C.,Escobedo,F.,&Zipperer,W.(2011).Aframeworkfordevelopingurban

forestecosystemservicesandgoodsindicators.LandscapeandUrbanPlanning, 99,196–206.

Duany,A.,Speck,J.,&Lydon,M.(2009).Thesmartgrowthmanual.NewYork: McGraw-HillProfessional.

EEA.(2007).EMEP/CORINAIREmissionInventoryGuidebook–2007.InTechnical reportNo.16/2007.

Escobedo,F.,Varela,S.,Zhao,M.,Wagner,J.,&Zipperer,W.(2010).Theefﬁcacyof subtropicalurbanforestsinoffsettingcarbonemissionsfromcities. Environmen-talScienceandPolicy,13,362–372.

Escobedo,F.,Kroeger,T.,&Wagner,J.(2011).Urbanforestsandpollution mitiga-tion:Analyzingecosystemservicesanddisservices.EnvironmentalPollution,159, 2078–2087.

FAO.(2005).Globalforestresourcesassessmentupdate2005:Italypilotcountry report.InFAOworkingpaper76.Roma.

Farr,D.(2007).SustainableUrbanism:Urbandesignwithnature.SanFrancisco:Wiley. Gidlöf-Gunnarsson,A.,&Öhrström,E.(2007).Noiseandwell-beinginurban residen-tialenvironments:Thepotentialroleofperceivedavailabilitytonearbygreen areas.LandscapeandUrbanPlanning,83(1–2),115–126.

Gioli,B.,Toscano,P.,Lugato,E.,Matese,A.,Miglietta,F.,Zaldei,A.,etal.(2012). Methaneandcarbondioxideﬂuxesandsourcepartitioninginurbanareas:The casestudyofFlorence,Italy.EnvironmentalPollution,164,125–131.

Grimmond,C.S.B.,King,T.S.,Cropley,F.D.,Nowak,D.J.,&Souch,C.(2002). Local-scaleﬂuxesofcarbondioxideinurbanenvironments:Methodological challengesandresultsfromChicago.EnvironmentalPollution,116,243–254. Hartig,T.A.,Evans,G.W.,Jamner,L.D.,Davis,D.S.,&Garling,T.(2003).Tracking

restorationinnaturalandurbanﬁeldsettings.JournalofEnvironmental Psychol-ogy,23,109–123.

Helfter,C.,Famulari,D.,Phillips,G.J.,Barlow,J.F.,Wood,C.R.,Grimmond,C.S.B., etal.(2011).Controlsofcarbondioxideconcentrationsandﬂuxesabovecentral London.AtmosphericChemistryandPhysics,11,1913–1928.

Hu,Y.,&Gensuo,J.(2010).Inﬂuenceoflandusechangeonurbanheatislandderived frommulti-sensordata.InternationalJournalofClimatology,30(9),1382–1395.

(9)

IPCC(International Panel onClimate Change). (2003).Good practiceguidance for LULUCF (Land Use, Land Use Change andForestry). , http://www.ipcc-nggip.iges.or.jp/public/gpglulucf/gpglulucf.html.

IPCC(International Panel onClimate Change). (2006). Guidelinesfor National GreenhouseGasInventories.AFOLU(Agriculture,ForestryandOtherLandUse)., http://www.ipcc-nggip.iges.or.jp/public/2006gl/vol4.html.

IRSE. (2010). Regional Emission Inventory of the Tuscany Region. , http://www.osservatoriokyoto.it/userfiles/file/irse.pdf(in@@press). Jo,H.K.,&McPherson,E.G.(1995).Carbonstorageandfluxinurbanresidential

greenspace.JournalofEnvironmentalManagement,45,109–133.

Katz,P.(1994).NewUrbanism.Towardsanarchitectureofcommunity.NewYork: McGraw-Hill.

Keenan,T.F.,Baker,I.,Barr,A.,Ciais,P.,Davis,K.,Dietze,M.,etal.(2012).Terrestrial biospheremodelperformanceforinter-annualvariabilityofland-atmosphere CO2exchange.GlobalChangeBiology,18(6),1971–1987.

Kennedy,C.,Steinberger,J.,Gasson,B.,Hansens,Y.,Hillman,T.,Havranek,M.,etal. (2010).Methodologyforinventoringgreenhousegasemissionsfromglobal cities.EnergyPolicy,38,4828–4837.

Kordowski,K.,&Kuttler,W.(2010).Carbondioxideﬂuxesoveranurbanparkarea. AtmosphericEnvironment,44,2722–2730.

Lin,W.Q.,Wu,T.H.,Zhang,C.G.,&Yu,T.(2011).Carbonsavingsresultingfromthe coolingeffectofgreenareas:AcasestudyinBeijing.EnvironmentalPollution, 159(8-9),2148–2154.

Magno, R., Gioli, B., Vaccari, F. P., & Canfora, E. (2010). Inﬂuence of water availability on carbon uptake of two Mediterranean Holm oak forests. Geophysical Research Abstracts, 12. EGU2010-12249-2, 2010 (http://adsabs.harvard.edu/abs/2010EGUGA.1212249M).

Matese,A.,Alberti,G.,Gioli,B.,Toscano,P.,Vaccari,F.P.,&Zaldei,A.(2008).Compact Eddy:Acompact,lowconsumptionremotelycontrollededdycovariancelogging system.ComputersandElectronicsinAgriculture,64,343–346.

Matese,A.,Gioli,B.,Vaccari,F.P.,Zaldei,A.,&Miglietta,F.(2009).Carbon diox-ideemissionsofthecitycenterofFirenze,Italy:Measurement,evaluation, andsourcepartitioning.JournalofAppliedMeteorologyandClimatology,48(9), 1940–1947.

McHale,M.R.,McPherson,E.G.,&Burke,I.C.(2007).Thepotentialofurbantree plantingstobecosteffectiveincarboncreditmarkets.UrbanForestryandUrban Greening,6,49–60.

Mirzaei,P.A.,&Haghighat,F.(2010).Approachestostudyurbanheatisland.Abilities andlimitations.BuildingandEnvironment,45,2192–2201.

Morani,A.,Nowak,D.J.,Hirabayashi,S.,&Calfapietra,C.(2011).Howtoselectthe besttreeplantinglocationstoenhanceairpollutionremovalintheMillionTrees NYCinitiative.EnvironmentalPollution,159,1040–1047.

Mostafavi,M.,&Doherty,G.(2010).EcologicalUrbanism.Boston:HarvardUniversity. Ng,E.,Chen,L.,Wang,Y.,&Yuan,C.(2012).Astudyonthecoolingeffectsofgreening inahigh-densitycity:AnexperiencefromHongKong.BuildingandEnvironment, 47,256–271.

Nowak,D.J.,&Crane,D.E.(2002).Carbonstorageandsequestrationbyurbantrees intheUSA.EnvironmentalPollution,116,381–389.

Nowak,D.J.,Crane,D.E.,&Stevens,J.C.(2006).Airpollutionremovalbyurbantrees andshrubsintheUnitedStates.UrbanForest&UrbanGreening,4,115–123. Odum,E.P.(1971).Fundamentalsofecology(3rded.).Philadelphia,London,Toronto:

W.B.SaundersCompany.

Oliveira,S.,Andrade,H.,&Vaz,T.(2011).Thecoolingeffectofgreenspacesasa contributiontothemitigationofurbanheat:AcasestudyinLisbon.Building andEnvironment,46,2186–2194.

Onishi,A.,Cao,X.,Ito,T.,Shi,F.,&Imura,H.(2010).Evaluatingthepotentialfor urbanheat-islandmitigationbygreeningparkinglots.UrbanForestry&Urban Greening,9(4),323–332.

Paoletti,E.,Bardelli,T.,Giovannini,G.,&Pecchioli,L.(2011).Airqualityimpactofan urbanparkovertime.ProcediaEnvironmentalSciences,4,10–16.

Pataki,D.E.,Emmi,P.C.,Forster,C.B.,Mills,J.I.,Pardyjak,E.R.,Peterson,T.R.,etal. (2009).Anintegratedapproachtoimprovingfossilfuelemissionsscenarioswith urbanecosystemstudies.EcologicalComplexity,6,1–14.

Pataki,D.E.,Carreiro,M.M.,Cherrier,J.,Grulke,N.E.,Jennings,V.,Pincetl,S.,etal. (2011).Couplingbiogeochemicalcyclesinurbanenvironments:Ecosystem ser-vices,greensolutions,andmisconceptions.FrontiersEcologyEnvironment,9, 27–36.

Pawlak,W.,Fortuniak,K.,&Siedlecki,M.(2010).Carbondioxideﬂuxinthecentre ofLodz,Polandanalysisofa2-yeareddycovariancemeasurementdataset. InternationalJournalofClimatology,31,232–243.

Petralli,M.,Massetti,L.,&Orlandini,S.(2011).Fiveyearsofthermalintra-urban monitoringinFlorence(Italy)andapplicationofclimatologicalindices. Theoret-icalandAppliedClimatology,104(4),349–356.

Qian,Y.,&Follett,R.F.(2002).Assessingsoilcarbonsequestrationinturfgrass sys-temsusinglong-termsoiltestingdata.AgronomyJournal,94,930–935. Reckien,D.,Ewald,M.,Edenhofer,O.,&Ludeke,M.K.B.(2007).Whatparameters

inﬂuencethespatialvariationsinCO2emissionsfromroadtrafﬁcinBerlin? ImplicationsforurbanplanningtoreduceanthropogenicCO2emissions.Urban Studies,44,339–355.

Salvati,L.,Munafo,M.,GargiuloMorelli,V.,&Sabbi,A.(2012).Low-density settle-mentsandlandusechangesinaMediterraneanurbanregion.Landscapeand UrbanPlanning,105,43–52.

Schneider,A.,&Woodcock,C.E.(2008).Compact,dispersed,fragmented,extensive? Acomparisonofurbangrowthintwenty-ﬁveglobalcitiesusingremotelysensed data,patternmetricsandcensusinformation.UrbanStudies,45(3),659–692. Sofo,A.,Nuzzo,V.,Palese,A.M.,Xiloyannis,C.,Celano,G.,Zukowskyj,P.,etal.

(2005).NetCO2storageinMediterraneanoliveandpeachorchards.Scientia Horticulturae,107,17–24.

Sproken-Smith,R.A.,&Oke,T.(1998).Thethermalregimeofurbanparksintwo citieswithdifferentsummerclimates.InternationalJournalofRemoteSensing, 19,2085–2104.

Steeneveld,G.J.,Koopmans,S.,Heusinkveld,B.G.,vanHove,L.W.A.,&Holtslag,A. A.M.(2011).Quantifyingurbanheatislandeffectsandhumancomfortforcities ofvariablesizeandurbanmorphologyintheNetherlands.Journalof Geophysi-calResearchAtmospheres,116http://dx.doi.org/10.1029/2011JD015988,article number:D20129

Tallis,M.,Taylor,G.,Sinnett,D.,&Freer-Smith,P.(2011).Estimatingtheremovalof atmosphericparticulatepollutionbytheurbantreecanopyofLondon,under currentandfutureenvironments.LandscapeandUrbanPlanning,103,129–138. Upmanis,H.,&Chen,D.(1999).Inﬂuenceofgeographicalfactorsand meteorologi-calvariablesonnocturnalurban-parktemperaturedifferences-acasestudyof summer1995inGoteborg,Sweden.ClimateResearch,13,125–139.

Velasco,E.,&Roth,M.(2010).CitiesasnetsourcesofCO2:Reviewofatmospheric CO2exchangeinurbanenvironmentsmeasuredbyeddycovariancetechnique. GeographyCompass,4(9),1238–1259.

Waldheim,C.E.(2006).LandscapeUrbanismreader.NewYork:Princeton Architec-turalPress.

Zhao,M.,Kong,Z.,Escobedo,F.,&Gao,J.(2010).Impactsofurbanforestson offset-tingcarbonemissionsfromindustrialenergyconsumptionforHangzhou,China. JournalofEnvironmentalManagement,91(4),807–813.

Zirkle, G., Lal, R., Augustin, B., & Follett, R. (2012). Modeling car-bon sequestration in the U.S. residential landscape. In R. Lal, & B. Augustin (Eds.), Carbon sequestration in urban ecosystems (pp. 265–276). http://dx.doi.org/10.1007/978-94-007-2366-514.ISBN978-94-007-2365-8

Perrone(1970),Architect,PhDonUrban,LandscapeandEnvironmentalDesign (2002),iscurrentlyassistantprofessoronUrbanandRegionalPlanningat Depart-ment of Urban and Regional Planning–University of Florence. She has just concludedasemesterasvisitingprofessor(fullposition)onUrbanandRegional PlanningandParticipatoryPlanning,atInstituteofGeography(Geographisches Institut)–UniversityofTübingen.Shecollaborateswithsomeinternationalresearch networks,suchasAesop(AssociationofEuropeanSchoolsofPlanning)withinwhich sheisnational(Italy)representative(asalternatemember).Shehaspublished numerousacademicarticlesandhascontributedchapterstoseveralpublications onurbanpoliciesformanagingdiversity,urbanandregionalplanningwithregard tolandconsumptioncontainment,urban-ruralfringere-design,publicspace re-design,localdevelopmentpoliciesandplanningtools,participatoryplanning.

Vaccari(1967),AgriculturalSciencedegreein1994,PhDinEcologyand Envi-ronmentalSystems.ResearchscientistattheInstituteofBiometeorologyNational ResearchCouncil,since2002.Scientiﬁcinterestsandhighlights:EffectsofhighCO2 oncropsandnaturalecosystems;Biosphereatmosphereinteractions;Urbancarbon ﬂuxes;Precisionagriculture;Biochar.Hehas36peerreviewedpapers,h-index=11.

Gioli(1971),EnvironmentalEngineeringdegreein1998.PhDinEcologyand Envi-ronmentalSystems.AdvancedresearchscientistattheInstituteofBiometeorology NationalResearchCouncil,since2004.Majorscientificresults:Developmentand extensivevalidationoftheaircraftfluxmeasurementsmethodology;Development ofupscalemethodstoderiveregionalscalecarbonbalance;Usingregionalfluxes asavalidationtollforatmosphericandecosystemmodeling:Studyofinteractions betweensurfaceandPBLfluxes.Hehas36peerreviewedpapers,h-index=11.

Toscano(1980),Sciencesandtechnology(OceanographyandMeteorology)degree in2005.MasterinAppliedMeteorologyin2006.PhDstudentinEcologyand EnvironmentalSystems.Excellentexperiencegainedduringmanynationaland internationalcampaign,planningandoperatingdataacquisitionofresearch air-craftthathadtobeoperatedinsynergywithseveralotheraircraftsandextensive groundactivities(atmosphericmeasurements,carbondioxidefluxes,boundary layercharacterization,environmentalpollutionsampling,remotesensing). Excel-lent experience gained during nationaland internationalshipboard missions (morpho-bathymetry,biostratigraphy,oceanographicsampling,carbondioxideand acetoneair-seafluxesmeasurements).Experienceinremotesensingtechniques, instrumentsandapplicationswithopticaldatagainedinthelastfiveyearsofwork experience.Experienceonsatellitedataproducts,processingandfinalapplications. Managementofmeteorologicalandmicro-meteorologicalinstrumentations,data acquisition,analysisanddataprocessing.Cropmodeling,experimentaland mod-elingdurumwheatgrowthstages,qualityandvulnerabledevelopmentalstages. Currentposition:ResearchscientistattheInstituteofBiometeorologyNational ResearchCouncil.Hehas9peerreviewedpapers,h-index=4.