Patchanalysis指数简单对译.docx
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Patchanalysis指数简单对译
MetricDefinitions(fromMcGarigalandMarks,1994andMcGarigalandMarks,1995)
ClassArea(CA)
Sumofareasofallpatchesbelongingtoagivenclass.
Example:
ConiferClassArea(CA)=359047.844+......+65819.984
CA=69.6626hectares
Ifthemapunitsarenotspecified(i.e.,DataFrameproperties;seeSetmapunits)and"StateareasinHectares"hasnotbeenselectedinthe"AdvancedOptions"ofthe"SpatialStatistics"dialogbox,thentheresultingstatisticswillbereportedinnativemapunits(vectorlayers(themes)only).
Intheexample;CA=696626.012(mapunits).Thisisthecaseformoststatistics.
LandscapeArea(TLA)
Sumofareasofallpatchesinthelandscape.
Example:
LandscapeArea(TLA)=46872.719+359047.844+...+62423.574
TLA=184.11hectares
PercentageofLandscape(ZLAND)
Whenanalyzingbyclass,ZLANDisthepercentageofthetotallandscapemadeupofthecorrespondingclass(patchtype).
NumberofPatches(NumP)
Totalnumberofpatchesinthelandscapeif"AnalyzebyLandscape"isselected,orNumberofPatchesforeachindividualclass,if"AnalyzebyClass"isselected.
Example:
ClassLevel:
NumberofPatches(NumP)
Mixedwood=5,Conifer=4,Deciduous=5
LandscapeLevel:
NumberofPatches(NumP)=14
PatchRichness(PR)
PRisthenumberofdifferentpatchtypeswithinthelandcape'sboundary.
PatchRichnessDensity(PRD)
PRDisequaltoPRdividedbythetotalareaofthelandscape(metressquared)multipliedby10,000andthen100(toconverttohundredsofhectares).
LargestPatchIndex(LPI)
TheLPIisequaltothepercentofthetotallandscapethatismadeupbythelargestpatch.
Whentheentirelandscapeismadeupofasinglepatch,theLPIwillequal100.Asthesizeofthelargestpatchdecreases,theLPIapproaches0.
MeanPatchSize(MPS)
Averagepatchsize.
Example:
MeanPatchSizeofConiferPatches(ClassLevel)
MPS=(359047.844+139531.484...+65819.984)/4
MPS=17.42hectares
Example:
MeanPatchSizeofPatches(LandscapeLevel)
MPS=(46872.719+359047.844+...+62432.574)/14
MPS=13.15hectares
MedianPatchSize(MedPS)
Themiddlepatchsize,or50thpercentile.
Example:
MedianPatchsizeofConiferPatches(ClassLevel)
MedPS=13.22hectares
Example:
MedianPatchsizeofallpatches(LandscapeLevel)
MedPS=7.59hectares
PatchSizeStandardDeviation(PSSD)
StandardDeviationofpatchareas.
Example:
PatchSizeStandardDeviationofConiferPatches(ClassLevel)
PSSD=11.05hectares
Example:
PatchSizeStandardDeviationofallpatches(LandscapeLevel)
PSSD=9.51hectares
PatchSizeCoefficientofVariance(PSCoV)
Coefficientofvariationofpatches.
Example:
CoefficientofVariationofConiferpatches(ClassLevel)
PSCoV=PSSD/MPS=(11.05hectares/17.42hectares)*100=63
Example:
CoefficientofVariationofallpatches(LandscapeLevel)
PSCoV=(9.51hectares/13.15hectares)*100=72
TotalEdge(TE)
Perimeterofpatches.
Example:
TotalEdgeConifer(ClassLevel)
TE=Sumofperimeterofallconiferpatches.
TE=10858.88metres
Unitsareexpressedinnativemapsunits.
Example:
TotalEdgeallpatches(LandscapeLevel)
TE=Sumofperimeterofallpatches
TE=28607.27metres
Important
Inthecaseofvectorlayers(themes),edgecalculationsincludealltheedgeonthelandscapeincludingboundaryedge.Thecontrastedweightededgefeatureallowsedgeweightattheboundariestobesettozero.Inthecaseofraster(grid)layers(themes),edgecalculationsdonotincludetheedgesthatsurroundthelandscapeboundaryedgeoranyinterioredgesthatincludepixelsclassifiedasNoData.
EdgeDensity(ED)
Amountofedgerelativetothelandscapearea.
Example:
EdgeDensityConifer(ClassLevel)
ED=TE/TLA
ED=10858.88metres/184.11hectares=58.98metres/hectare
Example:
EdgeDensityofallPatches(LandscapeLevel)
ED=28607.27metres/184.11hectares=155.38metres/hectare
MeanPatchEdge(MPE)
Averageamountofedgeperpatch.
Example:
MeanPatchEdgeConifer(ClassLevel)
MPE=TE/NumP
MPE=10858.88metres/4patches=2714.72metres/patch
Example:
MeanPatchEdgeallPatches(LandscapeLevel)
MPE=TE/NumP
MPE=28607.27metres/14patches=2043.38metres/patch
ContrastedWeightedEdgeDensity(CWED)
CWEDisameasureofdensityofedgeinalandscape(metresperhectare)withauser-specifiedcontrastweight.
CWEDisequalto0whenthereisnoedgeinthelandscape,inotherwordsthewholelandscapeandit'sborderaremadeupofasinglepatch.It'svalueincreasesastheamountofedgeinthelandscapeincreasesand/orastheuserincreasesthecontrastweight.
LandscapeShapeIndex(LSI)
LSIisthetotallandscapeboundaryandalledgewithintheboundarydividedbythesquarerootofthetotallandscapearea(squaremetres)andadjustedbyaconstant(circularstandardforvectorlayers,squarestandardforrasters).TheLSIwillincreasewithincreasinglandscapeshapeirregularityorincreasingamountsofedgewithinthelandscape.
DoubleLogFractalDimension(DLFD)
DLFDisameasureofpatchperimetercomplexity.Itnears1whenpatchshapesare'simple',suchascirclesorsquaresanditapproaches2aspatchshapeperimetercomplexityincreases.
MeanPerimeter-AreaRatio(MPAR)
ShapeComplexity.
Example:
Meanperimeter-arearatioConifer(ClassLevel)
MPAR=Sumofeachpatchesperimeter/arearatiodividedbynumberofpatches.
MPAR=(132m/ha+112m/ha+201m/ha+84m/ha)/4patches
MPAR=182metres/hectare
Example:
Meanperimeter-arearatioallpatches(LandscapeLevel)
MPAR=(200m/ha+132m/ha+...+175m/ha)/14patches
MPAR=185metres/hectare
MeanShapeIndex(MSI)
ShapeComplexity.
MSIisequalto1whenallpatchesarecircular(forpolygons)orsquare(forrasters(grids))anditincreaseswithincreasingpatchshapeirregularity.
MSI=sumofeachpatch'sperimeterdividedbythesquarerootofpatcharea(inhectares)foreachclass(whenanalyzingbyclass)orallpatches(whenanalyzingbylandscape),andadjustedforcircularstandard(forpolygons),orsquarestandard(forrasters(grids)),dividedbythenumberofpatches.
AreaWeightedMeanShapeIndex(AWMSI)
AWMSIisequalto1whenallpatchesarecircular(forpolygons)orsquare(forrasters(grids))anditincreaseswithincreasingpatchshapeirregularity.
AWMSIequalsthesumofeachpatch'sperimeter,dividedbythesquarerootofpatcharea(inhectares)foreachclass(whenanalyzingbyclass)orforallpatches(whenanalyzingbylandscape),andadjustedforcircularstandard(forpolygons),orsquarestandard(forrasters(grids)),dividedbythenumberofpatches.ItdiffersfromtheMSIinthatit'sweightedbypatchareasolargerpatcheswillweighmorethansmallerones.
MeanPatchFractalDimension(MPFD)
ShapeComplexity.
Meanpatchfractaldimension(MPFD)isanothermeasureofshapecomplexity.Meanfractaldimensionapproachesoneforshapeswithsimpleperimetersandapproachestwowhenshapesaremorecomplex.
AreaWeightedMeanPatchFractalDimension(AWMPFD)
ShapeComplexityadjustedforshapesize.
Areaweightedmeanpatchfractaldimensionisthesameasmeanpatchfractaldimensionwiththeadditionofindividualpatchareaweightingappliedtoeachpatch.Becauselargerpatchestendtobemorecomplexthansmallerpatches,thishastheeffectofdeterminingpatchcomplexityindependentofitssize.Theunitofmeasureisthesameasmeanpatchfractaldimension.
MeanNearestNeighbor(MNN)
Measureofpatchisolation.
Thenearestneighbordistanceofanindividualpatchistheshortestdistancetoasimilarpatch(edgetoedge).Themeannearestneighbordistanceistheaverageofthesedistances(metres)forindividualclassesattheclasslevelandthemeanoftheclassnearestneighbordistancesatthelandscapelevel.
InterspersionJuxtapositionIndex(IJI)
Measureofpatchadacency.
Approacheszerowhenthedistributionofuniquepatchadjacenciesbecomesunevenand100whenallpatchtypesareequallyadjacent.
Interspersionrequiresthatthelandscapebemadeupofaminimumofthreeclasses.Attheclasslevelinterspersionisameasureofrelativeinterspersionofeachclass.Atthelandscapelevelitisameasureoftheinterspersionoftheeachpatchinthelandscape.
MeanProximityIndex(MPI)
Measureofthedegreeofisolationandfragmentation.
Meanproximityindexisameasureofthedegreeofisolationandfragmentationofapatch.MPIusesthenearestneighborstatistic.Thedistancethresholddefaultis1,000,000.IfMPIisrequiredatspecificdistances,selectSetMPIThresholdfromthemainPatchpull-downmenuandenterathresholddistance.
BothMNNandMPIusethenearestneighborstatisticofsimilarpolygonsintheiralgorithm.OccasionallyablankorzerowillbereportedinMNNandMPIfields.Thishappenswhenonepolygonvertextouchesanotherpolygonsborderbutthetwosimilarpolygonsdonotshareacommonborder.Whenthishappensamanualedit(move)ofthetouchingvertexwillcorrecttheprobleminthelayer(theme).Thisproblemwillnothappenwhenanalyzingraster(grid)layers(themes).
Shannon'sDiversityIndex(SDI)
Measureofrelativepatchdiversity.
Shannon'sdiversityindexisonlyavailableatthelandscapelevelandisarelativemeasureofpatchdiversity.Theindexwillequalzerowhenthereisonlyonepatchinthelandscapeandincreasesasthenumberofpatchtypesorproportionaldistributionofpatchtypesincreases.
Simpson'sDiversityIndex(SIDI)
Measureofrelativepatchdiversity.
Si