Peterpatcha

Example:TimeseriesfromBaden-Wurttembergsince1930Theeffectivemeshsizehasdecreasedby40%since1930.
TheseresultshavebeencalculatedattheUniversityofStuttgartincollaborationwiththeCenterofTechnologyAssessmentinBaden-WurttembergandtheStateInstituteforEnvironmentalProtectionBaden-Wurttemberg(seeJaegeretal.
2001,Essweinetal.
2002).
Thedegreeoffragmentationcanalsobeexpressedastheeffectivemeshdensity,s,(i.
e.
,theeffectivenumberofpatchesper100km2)whichincreaseswithincreasinglandscapefragmentation(eff1ms=).
LiteratureOnthemethod:Esswein,H.
,Jaeger,J.
,Schwarz-vonRaumer,H.
-G.
2003.
DerGradderLandschaftszerschneidungalsIndikatorimNatur-schutz:unzerschnitteneverkehrsarmeRume(UZR)odereffektiveMaschenweite(meff)–In:NNA-Berichte16(2):53-68Jaeger,J.
A.
G.
2000.
Landscapedivision,splittingindex,andeffectivemeshsize:Newmeasuresoflandscapefrag-mentation.
–Landscapeecology15(2):115-130Jaeger,J.
2002.
Landschaftszerschneidung.
VerlagEugenUlmer,StuttgartJaeger,J.
2004.
VII-12ZerschneidungderLandschaftdurchVer-kehrswegeundSiedlungsgebiete.
–In:W.
Konoldetal.
(Hrsg.
).
HandbuchNaturschutzundLandschaftspflege.
Ecomed-Verlag,LandsbergSchupp,D.
2005.
UmweltindikatorLandschaftszerschneidung.
–GAIA14(2):101-106Casestudiesapplyingthemethod(selection):Esswein,H.
,J.
Jaeger,H.
-G.
Schwarz-vonRaumer,M.
Müller2002.
LandschaftszerschneidunginBaden-Württemberg.
Zer-schneidungsanalysezuraktuellenSituationundzurEntwicklungderletzten70JahremitdereffektivenMaschenweite.
–Arbeits-berichtderAkademiefürTechnikfolgenabschtzungNr.
214,StuttgartJaeger,J.
,H.
Esswein,H.
-G.
Schwarz-vonRaumer,M.
Müller2001.
LandschaftszerschneidunginBaden-Württemberg.
-NaturschutzundLandschaftsplanung33(10):305-317Jaeger,J.
,S.
Grau,W.
Haber(Hrsg.
)2005:Landschaftszerschnei-dung:VonderProblemerkennungzumHandeln.
Themen-schwerpunktheft.
–GAIA14(2):98-185Peter,U.
,S.
Meier2003.
ZerschnitteneLandschaft–einProblemimKantonAargau-UmweltAargauNr.
22:29-32Roedenbeck,I.
A.
,Esswein,H.
,Khler,W.
2005.
Landschafts-zerschneidunginHessen.
–NaturschutzundLandschafts-planung37(10):293-300ContactIfyouhavequestionsorwouldliketoreceivecopiesoftheabovearticlespleasecontactDr.
JochenJaeger:E-mail:jochen.
jaeger@env.
ethz.
chPhone:+41(0)16320826Mail:ChairofNatureandLandscapeProtectionETH-Zentrum,CHNE21.
1CH–8092Zurich,Switzerlandwww:http://www.
nls.
env.
ethz.
ch/staff/jaeger.
htmlZurich,April2004,revisedversionJanuary2006MeasuringLandscapeFragmentationwiththeEffectiveMeshSizemeffbyJochenJaeger,HeideEssweinundHans-GeorgSchwarz-vonRaumerWhatissoproblematicaboutlandscapefragmentationFragmentationoflandscapesisamajorcauseofthealarminglossofspeciesinEurope(e.
g.
,duetotheisolationofpopulationsandtheseparationofcomple-mentarytypesofhabitat).
Inaddition,transportationinfrastructure,aleadingcauseoffragmentation,detri-mentallyaffectstherecreationalqualityoflandscapes(e.
g.
,duetonoisepollutionandthereductioninsizeandqualityofrecreationareas).
Asearlyas1985,theGermanGovernmentsetthepoliticalgoalofpreservinglargeun-fragmentedlow-trafficareas.
However,landscapefragmentationhasincreasedasrapidlyasbeforeduetonewroadsandrailroads,enhancedtrafficvolume,andurbandevelopment.
13.
0113.
6613.
9919.
4622.
9217.
819.
5820.
2420.
5122.
1424.
2631.
605101520253035192019401960198020002020withoutmunicipalroadswithmunicipalroadsmeff[km2]YearWhyistheeffectivemeshsizebetterthanothermethodsFormermeasuresoflandscapefragmentationareseverelylimitedintheirsensitivity(e.
g.
,thedensityoftrafficlinesneglectsthestructureofthetrafficnetworkwhichmaybeevenlydistributedorbundled;thetotalareaoflargeun-fragmentedlow-trafficareas>100km2neglectswhathappenstopatchesthataresmaller).
Thenewmethodhasimportantadvantages.
Itfulfilsallscientific,functional,andpragmaticrequirementsofenvironmentalindicators(Essweinetal.
2003),itissimpleandtransparentandhasanintuitiveinterpretation(seebelow).
Ittakesintoaccountallpatchesaccordingtotheirsize.
Furthermore,testingtheeffectivemeshsizeagainstasystematicsetofninescientificcriteriahasprovenitsaccuracyandsuitability(e.
g,lowsensitivitytosmallpatches,monotonousreactiontodifferentfrag-mentationphases,detectionofstructuraldifferences,andadvantageousmathematicalcharacteristics;seeJaeger2000,2002,2004).
Theeffectivemeshsizeissuitableforcomparingthedegreeoffragmentationoflandscapeswithdifferingtotalsizeandwithdifferingproportionsofurbandevelopmentandtrafficarea.
WhatdoesthevalueoftheeffectivemeshsizemeanTheeffectivemeshsizeisbasedontheprobabilityoftwopointschosenrandomlyinaregionwillbeconnected.
Themorebarriersinthelandscape,thelowertheprobabilitythatthetwopointswillbeconnected,andthelowertheeffectivemeshsize.
Ifalandscapeisfragmentedevenlyintopatchesallofsizemeff,thentheprobabilityofbeingconnectedisthesameasforthefragmentationpatternunderinvestigation.
Itcanalsobeinterpretedastheexpectedsizeofthepatchapointwillbelocatedinthatischosenrandomlyanywhereintheregion,orastheabilityoftwoanimalsofthesamespecies–placedrandomlyinaregion–tofindeachother.
Theprobabilityisconvertedintothesizeofapatch–theeffectivemeshsize–bymultiplyingitbythetotalsizeoftheregioninvestigated.
Thus,theunitofmeffisthatofarea(e.
g.
haorkm2).
Thevalueofmeffisbetween0(entirelyfragmentedordeveloped)andthesizeoftheregioninvestigated(un-fragmented).
Inthecasethatallpatchesareofthesamesize,theeffectivemeshsizeassumesthesizeofthepatchesand,therefore,oftheaveragepatchsize.
However,asthesizeofpatchesusuallydiffers,theeffectivemeshsizeisgenerallynotequaltotheaveragepatchsize.
ThemeasuremeffhasbeendevelopedbyJochenJaegerattheCenterofTechnologyAssessmentinBaden-Wurttemberg,Stuttgart,andattheETHZurich(Jaeger2000,2002,2004).
HowaretheseresultsusefulThedegreeoflandscapefragmentationisanimportantenvironmentalindicatorinthefieldsofbiodiversityandrecreationalqualityand,moregenerally,sustainability.
Inaddition,informationonthedegreeoflandscapefragmentationisrelevantinregionalplanningandfordecisionsaboutinfrastructureplacementorremoval.
Timeseriesshowhowstrongthecurrenttrendsareandwhattheirdirectionis.
WherehastheeffectivemeshsizebeenusedsofarmeffhasalreadybeenusedinBaden-Wurttemberg(seeexampleonotherside),Bavaria,Hesse,Thuringia,Saxony,Schleswig-Holstein,andSouthTyrol(Italy).
In2004,theGermanConferenceoftheMinistersoftheEnvironmentadoptedtherecommendationbytheGermanStateCommitteeCoreIndicatorstouseastandardizedprocedureforcalculatingmeffinallGermanstates.
ThemeffmethodhasalsobeenusedbytheEuropeanEnvironmentalAgency.
Currently,meffisbeingcalculatedinSwitzerlandandCanada.
Exampleofhowtocalculatetheeffectivemeshsize()222221totaleff.
.
.
.
.
.
1niAAAAAm+++++=wheren=numberofpatches,Atotal=totalareaoftheregioninvestigated,andAi=sizeofpatchi(i=1,…,n).
Example:Alandscapeisfragmentedbyhighwaysintothreepatches.
Theprobabilitythattworandomlychosenpointswillbeinpatch1(and,therefore,willbeconnected)is.
25.
05.
05.
02total1==AAThecorrespondingprobabilityis0.
252=0.
0625forbothpatches2and3.
Theprobabilitythatthetwopointswillbeinpatch1or2or3isthesumofthethreeprobabilitieswhichresultsin0.
375.
Multiplyingthisprobabilitybythetotalareaoftheregionfinallygivesthevalueoftheeffectivemeshsize:0.
375·4km2=1.
5km2.
A1A3A2Atotal=4km2