The Circumpolar Arctic Vegetationmap (CAVM)Willbe Based on Current Knowledge of Arctic Plant Communities and Their Environmental Controls

int.j. remote sensing, 2002, vol. 23, no. 21,4551– 4570

TheCircumpolar Arctic Vegetation Map: AVHRR-derived base maps, environmentalcontrols, and integrated mapping procedures

D.A.WALKER,W. A.GOULD, H.A.MAIERand M.K.RAYNOLDS Instituteof Arctic Biology, University of Alaska Fairbanks, F airbanks, AK99775–7000, USA; e-mail: [email protected]

Abstract. Anewfalse-colour-infrared image derived from biweekly 1993 and 1995Advanced V eryHigh Resolution Radiometer (A VHRR) dataprovides a snow-freeand cloud-free base image for the interpretation of vegetation as part ofa 1:7.5M-scale Circumpolar Arctic V egetationMap (CA VM).Amaximum- NDVI( NormalizedDi VerenceV egetationIndex) image prepared from the same dataprovides a circumpolarview of vegetation green-biomass density across the Arctic.This paper describes the remote sensing products, the environmental factorsthat control the principal vegetation patterns at this small scale, and the integratedgeographic information-system (GIS) methodsused in making the CAVM.

1.Introduction Remote sensing products from Earth-orbiting satellites provide the imagebase to make the rst detailed vegetationmap of anentire globalbiome, the arctic tundra. Anewvegetation map of the Arctic is needed for numerous international e Vorts, including global-changeand conservation studies, land-use planning, large-scale resource development, and education. The Circumpolar Arctic VegetationMap (CAVM)willbe based on current knowledge of arctic plant communities and their environmental controls. During the past sixyears, the CAVMparticipants have dened the project organization and methods in aseries of workshops (Walker 1995, D. A. Walker et al. 1995,W alker and Markon 1996,W alker and Lillie1997, Markon and Walker 1999,Walker 2000,Raynolds and Markon 2002).Sixgroups of collabor- ators arenow working on regionalmaps of Alaska,Canada, Greenland, Iceland, Svalbard,and Russia.This paper presents two newAVHRR-derived images of the circumpolar Arctic, the keyenvironmental variablesused for interpreting the vegetation,and the GIS framework for the mapping methods.

2.Remote-sensing products 2.1. AVHRR-derivedbase map Ahigh-resolution falsecolour-infrared (CIR)image of the circumpolar region representing the vegetationat maximum greenness is anessential element of the

Thispaper was presented at the6th Circumpolar Symposium on Remote Sensing of Polar Environmentsheld in Y ellowknife,Northwest T erritories,Canada, from 12– 14 June 2000.

InternationalJournal of Remote Sensing ISSN0143-1161 print /ISSN1366-5901 online ©2002Taylor & FrancisLtd http://www.tandf.co.uk /journals DOI:10.1080 /01431160110113854 4552 D. A. Walker et al. mapping method (gure 1).This imageis derived from AdvancedVery-High Resolution Radiometer (AVHRR)data that wereobtained from the USGeological Survey (USGS) AlaskaGeographical Science O Yce. It is composed of 1km ×1 km picture elements (pixels).The imageis acomposite of pixels,where each pixelwas selected byusing the date with highest Normalized Di Verence VegetationIndex (NDVI)for that pixelamong biweeklyimages taken during the periods from 1April to 31October in 1993and 1995.These periods cover the vegetationgreen-up-to- senescence period during two relativelywarm years when summer-snow cover was atminimum in the Arctic. This permitted the construction of animage with minimum snow and cloud cover. The white areasare glaciers that weremasked out using information from the DigitalChart of the World. The ocean icewas masked out using the coastlines from the DigitalChart of the World. The southern border of the CIRimage is clipped to tree line, which wasderived from the best available

Figure1. A VHRR-derivedfalse colour-infrared image of thecircumpolar Arctic. The image isderived from the pixels with highest NDVI amongbiweekly images from 1993 and 1995.The southern border of the CIR imageis clipped to treeline, which was derived fromthe best available vegetation maps. Sixth CircumpolarSymposium on Remote Sensing of Polar Environments 4553 vegetationmaps and the most recent information (Raynoldsand Markon 2002). The imageis used asabase for drawingvegetation map polygons. Most boundaries on the vegetationmap correspond to features that canbe seen on the AVHRRimage (see §4).

2.2. Maximum-NDVIimage Animage portraying maximum NDVI (gure 2)is used to delineate areasof high and lowvegetation biomass. This imagewas created from the same dataas the falseCIR image( gure 1). NDVI=(NIR± IR)/(NIR+IR), where IR is the spectral reectance in the AVHRRnear-infrared channel (0.725–1.1 mm), where light- reectance from the plant canopy is dominant, and R is the reectance in the red channel (0.5–0.68 mm), the portion of the spectrum where chlorophyll absorbs maxim- ally.The NDVI valueswere grouped into eight classes that meaningfullyseparate the vegetationaccording to biomass. Redand orange areasin gure 2areareas of shrubby vegetationwith high biomass, and blue and purple areasare areas with low biomass.

Figure2. Maximum NDVI for the circumpolar Arctic derived from the same data as gure5. 4554 D. A. Walker et al.

3.Environmental controls of vegetation at 1:7.5 M scale The approach used for makingthe CAVMis based on manual‘ photo- interpretation’of the AVHRRsatellite image.A map based purely on automated remote sensing procedures could not portray the details of plant communities for the entire circumpolar region because there is largevariability of tundra vegetation with similarspectral properties. Due to the smallscale of the map and lackof previous vegetationmaps for much of the Arctic, vegetationinformation must be inferred from expert knowledge of the plant communities in relation to principal landforms and other terrain features that arevisible on small-scalesatellite imagery. In the Arctic, vegetationof agivenlandscape canbe predicted on the basis of summer temperature regime( bioclimatic subzones), availableplants in the regional ora (oristic sectors), soil chemistry, and prevailingdrainage conditions (Walker 2000).

3.1. Bioclimaticzonation Afundamental problem for the CAVMis how to characterize the transitions in vegetationthat occur across the roughly 10 °Cmean Julytemperature gradient from the tree line to the coldest parts of the Arctic. The important role of summer temperature has been noted with respect to awidevariety of ecologicalphenomena, including phenology (Sorensen 1941),species diversity (Young 1971,Rannie 1986 ), plant community composition (Matveyeva1998 ),biomass (Blissand Matveyeva 1992,Bazilevich et al. 1997),and invertebrate and vertebrate diversity(Chernov and Matveyeva1997 ).Various authors, working with di Verent geobotanical traditions, havedivided the Arctic into bioclimatic regions using avarietyof terminologies (table 1).The origins of these di Verent terms and approaches havebeen reviewed for the PanarcticFlora ( PAF)initiative( Elvebakk1999 ).The PAFand CAVMhave accepted ave-subzone version of the Russian zonal approach (gure 3).The subzone boundaries aresomewhat modied from the phytogeographic subzones of Yurtsev (1994)based on recent information from avarietyof sources (Raynoldsand Markon 2002).Abrief description of eachsubzone follows:

3.1.1. SubzoneA: Herb subzone Subzone Aincludes mostly fog-shrouded islands within the permanent arctic ice pack where Julymean temperatures areless than about 2–3 °C,such asEllefRingnes, Amund Ringnes,King Christian, northern Prince Patrick and nearby islands in the northwest corner of the CanadianArchipelago. It alsoincludes the coastalfringe of northernmost Greenland and northern Ellesmere and northern AxelHeiberg islands, the northeastern portion of Svalbard,Franz Josef Land,Severnaya Zemlya, the northern tips of the TaimyrPeninsula, and northern tip of NovayaZemlya. The summer temperatures inthese areasare near freezing allsummer due to acombination of nearlycontinuous cloud and fogcover, which limits solar radiation, and the close proximity to the ice-covered ocean (Bay1997, Razzhivin 1999 ).More continental inland areasof the largerislands areoften considerably warmer.Permanent ice covers largeareas of the land. Major parts of the nonglacialland surfaces are largelybarren, often with <5%cover of vascularplants, however, meadow-like plant communities arenot uncommon on mesic ne-grained soils, where there is suYcient moisture provided bythe cold humid oceanic climate. Woody plants areabsent on zonal sites. Zonalsites are ator gentlysloping, moderately drained sites with ne-grained soils that arenot inuenced byextremes Sixth CircumpolarSymposium on Remote Sensing of Polar Environments 4555 of soil moisture, snow, soil chemistry, or disturbance and which fullyexpress the inuence of the prevailingregional climate. Lichens, bryophytes, cyanobacteria,and scattered forbs (e.g. Papaver, Draba, Saxifraga and Stellaria)arethe dominant plants. Manyof the forbs, lichens and mosses havea compact cushion growth form. In midsummer, the arctic poppy, Papaverradicatum ,isthe most conspicuous plant over largeportions of this subzone. Other important low-growingcushion-forb genera include Minuartia and Cerastium.Soil lichens, mosses, and liverworts cancover a high percentage of the surface, particularlyin more maritime areassuch asNovaya Zemlya(Alexandrova 1980 ).Rushes ( L uzula and Juncus)and grasses( Alopecurus, Puccinellia , Phippsia, and Dupontia)arethe main graminoid groups. Sedges (Cyperaceae)are rare, and wetlands lackorganic peat layers.There is little contrast in the composition of vegetationon mesic sites, streamside sites, and snowbeds. The vascularplant ora isextremelydepauperate, consisting of only about 50–60 species (Young 1971).On ne grainedsoils, the extremelycold temperatures and the thin sparse plant canopy induce intense frost activity,which forms networks of small (<50cm diameter) nonsorted hummocks and polygons, and plants arecon ned mainlyto the depressions between the hummocks (Chernov and Matveyeva1997 ).

3.1.2. SubzoneB: Prostrate dwarf-shrubsubzone Subzone Bincludes parts of the southern Queen Elizabeth Islands, the eastern fringeof Ellesmere Island, much of PearyLand in Greenland, the eastern portion of Svalbard,central NovayaZemlya, the northern coast of the TaimyrPeninsula, and the NewSiberian Islands. Becauseof its smallsize and weaklyde ned distin- guishing characteristics, Subzone Bcould be characterized asa transition zone to Subzone C.Severaltreatments of arctic zonation include subzones Band Cin a singlesubzone (Matveyeva1998, Yurtsev 1994).The mean Julytemperature atthe southern boundary of Subzone Bis approximately5 °C.This subzone has scattered prostrate (creeping)dwarfshrubs on zonal soils. Erect shrubby vegetationis lacking. Mesic, low-elevation surfaces with ne-grained soils generallyhave open, patchy plant cover, generallywith 5–25% cover of vascularplants. Well-di Verentiated snowbed and riparian plant communities arelacking. Nonsorted circles, stripes, and ice-wedgepolygons arecommon. Vascularplant vegetationis often conned to cracks and depressions in the polygonalnetwork, and areasirrigated byruno V from snow patches. The dominant growth forms on mesic sites areprostrate dwarfshrubs (e.g. Dryas, Salix arctica and S. polaris),forbs (e.g. Draba, Saxifraga, Minuartia, Cerastium and Papaver),graminoids, (e.g. Carex stans, Carexrupestris , Alopecurus alpinus, Deschampsiaborealis and Luzulaconf usa ),mosses and lichens. Rushes (L uzula)arealso an important component of manymesic vegetationtypes. Sedges (Carex, Eriophorum)often aredominant in wetareas.

3.1.3. SubzoneC: Hemiprostratedwarf-shrub subzone Subzone Cincludes northern Banks Island, northern VictoriaIsland, Devon Island, Prince of WalesIsland, Somerset Island, northern Ba YnIsland, most of Ellesmere Island, AxelHeiberg Islands, the west coast of Greenland, and inner ord regions of northeast Greenland, southern NovayaZemlya, some coastalareas of Yakutiaand Chukotka, and the northernmost coast of Alaska( Yurtsev 1994).The mean Julytemperature atthe southern boundary of Subzone Cis about 7 °C. Mesic zonal surfaces in this subzone havemore luxuriant plant growth than that in Subzone B.Zonalsites aregenerally well vegetated, but vascular-plant cover is still open, and 4556 D. A. Walker et al. c a i a r b t e e r r k e c a ) u n n d d k l r n r 9 o o a n n o n a n o h 9 z z r b u u r p s z t t 9 e e e e l a a 1 t c c v h a r h r c c i i l ( d i r t i t i t e e t d d e r t t d d E c u c i s n n c n c n o r r n e o r r o o u u a A d N a z M t S a z A t c s ) ) ) ) 5 o ) ° ° ° ° n c ° 5 0 5 5 i . . . n n 0 r t 7 . r 0 1 . 2 e e c ) a e e . 0 a l 1 r F n l 6 n n a n o = = a = n i a o 8 o o r = r = p k C C C d 9 z z p e e e ( ( ( l C h C 1 r n h ( h r c c ( ( d t e u i t i e e e a e t r t t d u c T n n i n n c c u o s o r r o o o n I z O z N a M z S a o n n ) e 7 F c 9 c i i 9 t d t c 1 c n ( r r a a s a s , i h l a w g c i B o i r H L e , , , , ) ) ) ) 4 m ) b C C C C e C D D D ° u ° ° t ° A ° D r 3 4 6 a 7 ) 0 D D D r h D – – – – h 1 6 t T T T s d t ) b 1 3 4 5 d s 9 – T r b n ( ( ( ( 0 0 0 9 e u 9 n o 7 0 a t u 5 5 5 r o ( 8 r 1 a r 5 a ( 2 3 3 9 h p d r 1 s h N s – – 1 t s n ( d – u d > s 0 0 , t a m u n 0 o n e n c t 5 5 o a c l a l t i i e 5 u r e o 1 2 a r d l g i s c a r p A t f e r s d e a o - E i r t t b s u b b E s m a p u r r n w o r R A e y e w a r o r h r H c H t P D s L h n t i r e o ) c n i N 0 3 t o 6 c n c c i i 9 r i Z t t n 1 a c c u r c , r l i e a 1 l a t o 5 d c h P 9 r d w g i 1 i o ( A H M L e h ) ) ) 2 t e ) C C C n f b - C ° ° ° r f o b ° o 7 9 2 r r ) z o b ( ( 3 u 1 f e a s 0 r b - u – e – k t r 0 h w u l n n e 2 e e 0 s s a 0 ( h d a o n n n o - 1 r s i 2 f i ( t o o t - o b ( r s h W s z z c z i u s a w o e b b r b v u r r o w i u u h u C s P d s E s L s d b ) ) ) 1 a u ) r s C C C a a C ° ° ° d t r t ° v r 6 0 2 d n ) e e 2 n 1 1 – u n s 8 y – e t – – 5 n e u l 9 e ( 5 r t l 8 0 . d v 9 a ( e a 1 a t 1 1 c v ( r h r ( c i a ( i i t t a d l u p c u n M r o y o q u e P A T S t e t a a a a v t t r r m r r o ) d d i r e e 0 s s n n x a n n n d c c c n n n i 8 e e i i i r r r u u r r r o s n t t t 9 t t e e e e d d e e e r s a c a l c a c a 1 h h h h h r r r r h r r u c c p x r r ( d t t t t i t i t a a a e d d d r a a r r t t p d R l l u l u u i b b b c c n n n o o o o o o o o r r A A u u u u u u N p S p N a S a N s t M s t S s t . t t 1 n n e – – a a l i i a a r r b r r v ) a a a e c d d 4 i c c s v v T i i t n n t 9 t t n c n r 9 u u n n r c c r r t t r r u 1 e r r e a ( a e e a a c c a a Y h r r h r i i h h t t o o h t t t t d d d r g c r c u p p u n n n i o r r o y o y o u u u H t A n A s N h t S h t e n o z b u S A B C D E Sixth CircumpolarSymposium on Remote Sensing of Polar Environments 4557 interrupted byfrost scars and other periglacialfeatures. The main features distin- guishing Subzone Cfrom Subzone Barethe presence of the hemiprostrate shrub Cassiopetetragona and well-diVerentiated plant communities inmires, snowbeds and creek sides. Cassiope covers largeareas on mesic sites in areaswith acidicparent material,such ason Svalbard,Ba YnIsland, and interior portions of Greenland. However, Cassiope is lackingon mesic alkalinesurfaces in the western Canadian Islands. In these areas, Cassiope is generallycon ned to snow accumulation areas. Subzone Chas much greaterspecies diversity than Subzone B.Sedges, such as Kobresiamyosuroides , Carexbigelowii and Carexrupestris , arecommon on upland surfaces, and numerous forbs, such asmembers of the Fabaceae(e.g. Oxytropis, Astragalus)areimportant in nonacidic regions. Communities in intrazonal habitats (snowbeds and creek sides) arewell developed. Wetland communities aremuch better developed than in Subzone B.Creek sides havedistinctive Epilobiumlatifolium communities. 3.1.4. SubzoneD: Erect dwarf-shrubsubzone Subzone Dcovers the southern parts of Banks Island and VictoriaIsland, much of Keewatin, southern Ba YnIsland, most of southern Greenland, and abroad band across Siberia and Chukotka. Climatically,Subzone Dperiodically receives relatively temperate airfrom the south during the summer whileSubzone Creceives predomin- atelyarctic airmasses. The mean Julytemperature atthe southern boundary of Subzone Dis about 9 °C.The boundary between subzones Cand Dis considered of highest rank because it separates the northern drier tundras on mineral soils from the southern relativelymoist tundras with moss carpets and peatysoils (Alexandrova 1980).This is approximatelyequivalent to the boundary between Bliss’High and LowArctic (Bliss1997 ).The major di Verence inpedology causes dramatic changes to the vegetation.The plants in Subzone Dhavestrong hypoarctic (boreal forest) aYnities (Yurtsev et al. 1978).Important hypoarctic species such asbirch (e.g. Betula nana), alder (Alnus), willow (Salix)and heath plants (Ericaceaeand Empetraceae) extend their rangesfrom the lower layerof subarctic woodlands, but arenot dominant asthey arein Subzone E.Lowshrubs ( >40cm tall)occur alongstreams. Overall, the role of shrublands ismuch less prominent than in Subzone E.The plant canopy is usuallyinterrupted bypatches of bare soil caused bynonsorted circles, stripes, and avarietyof other periglacialfeatures (‘spotty tundra’in the Russian literature). Vascularplants generallycover about 50–80% of the surface. Zonalvegetation on gentlysloping upland surfaces consists of sedges (e.g. Carexbigelowii , Carex mem- branacea, Eriophorumtriste , E. vaginatum and Kobresiamyosuroides) ,prostrate and erect dwarf( <40cm tall)shrubs (e.g. Salix planifolia , S. lanata ssp. richardsonii ,

Footnoteto T able1. 1Mateveyeva( 1998):Rangeof meanJuly temperature at southern boundary of subzone. 2Walker( 2000):Approximatemean July temperature at the southern boundary of the subzone. 3Polunin( 1951):Zonesbased roughly on openness of ground cover. High arctic, very sparselyvegetated; middle arctic, open vegetation carpet; low arctic, closed vegetation carpet. 4Edlundand Alt (1989):Zonesde ned on the bases of mean July temperature and sum ofmean temperature of daysexceeding 0 °C(thawingdegree days, TDD). 5Tuhkanen( 1986):Southernboundary of zones de ned by Holdridge biotemperature as thesum of mean monthly temperatures >0°Cdividedby 12. 4558 D. A. Walker et al.

Figure3. Bioclimatic subzones in the Arctic. Modi ed from Elvebakk et al. (1999).

S. reticulata, S. arctica, Betulaexilis and Dryasintegrifolia )and mosses. Prostrate- dwarf-shrub communities, which werecommon on zonal surfaces in Subzone C,are conned mainlyto wind-swept sites. The moss layer,consisting primarilyof Tomentypnum , Hylocomium, Aulacomnium and Sphagnum,contributes to the development of organicsoil horizons on ne-grained soils. Soils in Subzone Dhavethin peatyhorizons, and ne-grained soils areoften nonacidic, whereassoils in Subzone Eareusually acidic regardless of texture. There is more regionalvariation in the zonal vegetationthan in subzones A,B, and C.Tussock tundra consisting of cottongrass tussocks ( Eriophorumvaginatum ) and dwarfshrubs is common on ne-grained acidicsoils over much of northeastern Siberia and northern Alaska( Walker et al. 1994),particularlyin areasthat were unglaciatedduring the lastpart of the Pleistocene. In transitional areasto Subzone Cand on nonacidic loess, Dryas spp. and Cassiopetetragona areimportant (Walker and Everett 1991).Some continental areasof Russiahave dry steppe tundras that arerelicts of cold dry Pleistocene vegetation( Yurtsev 1982). Sixth CircumpolarSymposium on Remote Sensing of Polar Environments 4559

3.1.5. SubzoneE: Low-shrubsubzone Subzone Eis the warmest part of the Arctic Tundra Zone with mean July temperatures of 10–12 °C.In Subzone E,the zonal vegetationis dominated byhypo- arctic lowshrubs that areoften greaterthan 40cm tall(e.g., Betula nana, B. exilis, B. glandulosa, Salix glauca , S. phylicifolia , S. planifolia, S. richardsonii and Alnus spp.). True shrub tundra with dense canopies of birch, willows,and sometimes alder (Alnus)occur in manyareas. Birch or willowthickets 80to 200cm talloccur on zonal sites in some moister areassuch aswest Siberia and northwest Alaska.In more continental areasand areaswith less snow cover, the shrubs areshorter and form amore open canopy. Tussock tundra is common in northern Alaskaand eastern Siberia and contains more shrubs than in Subzone D(Alexandrova1980 ). Lowand tall( >2m)shrubs areabundant in most watercourses. Towardthe southern part of Subzone E,in atareas that arecontinuous with the boreal forest, patches of open forest penetrate into this areaalong riparian corridors. These woodlands consist of avarietyof species of spruce ( Picea), pine (Pinus),cottonwood ( Populus), and larch (L arix)and tree birches ( Betula).Peatplateaus (palsas)up to 1.5m tall occur in lowlandareas. 3.1.6. Altitudinalzonation Adiabaticcooling of airmasses athigher elevations causes altitudinal zonation. For continental areas,the environmental adiabaticlapse rate is about 6 °C per 1000 m (Barry1981 ).This is equivalent to ashift in bioclimatic subzone for about every 333-melevation gain.A topographic map wasmade with elevation isolines at333, 667,1000, 1333, 1667, and 2000m(gure 4).These show roughly where altitudinal zonation shifts canbe expected.

3.2. Floristicvariation within the zones Russian geobotanists havedescribed longitudinal subdivisions within the subzones, which arebased primarilyon oristic di Verences (Alexandrova1980, Yurtsev 1994).These divisions areuseful for characterizing the considerable east–west oristic variationwithin the subzones, particularlyin subzones C,D,and E.In the more northern two subzones, the Arctic has arelativelyconsistent core of circumpolar arctic plant species that occur around the circumpolar region. Further south, local east-west variationis related to avarietyof factors, including di Verent paleo-histories and the greaterclimatic heterogeneity. Largenorth-south trending mountain ranges, primarilyin Asia,have also restricted the exchangeof species between parts of the Arctic (Alexandrova1980 ).Yurtsev (1994)delineated six oristic provinces and 22 subprovinces and has discussed their characteristics. These haverecently been revised bythe PanarcticFlora Project (gure 5)(Elvebakk et al.1999).The Northern Alaska subprovince is used below in anexample for aframework for acircumpolar arctic vegetationmap (see table 2).This areacovers the region north of the Brooks Range, from the Mackenzie Riverwestward to about Point Lay.

3.3. Therole of parent material Vegetationpatterns related to parent materialdi Verences areextensive and there- fore important to globaland regionalscale modelling e Vorts. There isarich literature describing the peculiarities of oras and vegetationon carbonate and ultramac rocks, salinesoils, and ne vs.coarse textured soils in the Arctic (Edlund 1982, Elvebakk1982, Cooper 1986,Walker et al. 1998).These di Verences in parent material 4560 D. A. Walker et al.

B e rin g ia S Chu kotka n A la s otka k E C h uk a W C hukotka ska - Yuk la o W A n ra ngel Isl N Yana - Ko ula k h lym a Khara N

C - Olenyek an nabar C a A e da n t ra l C a H n T a i m y r u a d E llesm d er a e s - P o e a n ry La P n o an - al - G yd d la Ya m L r a U b ra r l - a e a N ov a y Z m l d - y a o ard r d b n Sva l nd la L a n . J. Ka nin- Pechor a ee F G r osc andia W enn N F N d Iceland- nlan J E Gre e a n May en

Figure4. Floristic sectors within the Arctic. From Elvebakk et al. (1999). haveimportant e Vects on ecosystem patterns and processes. Some of the most important vegetatione Vects arerelated to substrate pH. SylviaEdlund’ s diagramin gure 6illustrates welldi Verences in plant communities on alkalineand acidic substrates across zonal boundaries in the CanadianHigh Arctic. Similar patterns havebeen described on Svalbard( Elvebakk1985 )and northern Alaska( Walker et al.1994).Vegetationon nonacidic and acidicparent materialscan be determined for most regions of the Arctic using availablesoil and surcial-geology maps in a GIS context. Extensivesaline areas occur in parts of the Russian arctic. Other parent materialsubdivisions could be made for globalmapping ifthey werefound to be regionallyextensive and important to ecosystem processes.

3.4. Therole of topography Atlandscape scales( 1–100km 2),topography strongly inuences soil moisture, which is animportant control of patterns of tundra plant communities and tundra ecosystem processes (Webber 1978).The e Vect of topography canbe portrayed along hill-slopes asa mesotopographic gradient (gure 7and Billings1973 ).Generally, Sixth CircumpolarSymposium on Remote Sensing of Polar Environments 4561

Figure5. Topography of the circumpolar Arctic showing colour breaks corresponding to approximatealtitudinal zonation boundaries. The environmental adiabatic lapse rate of 6°Cper1000 m createsa shiftin equivalent bioclimatic subzone about every 333-m elevationgain. only extensivewetlands and dry mountainous areasare large enough to be displayed atthe 1:7.5M scale.Plant communities in snowbeds and alongstreams areusually too smallto map, but areimportant components of regionalvegetation mosaics and areused to help di Verentiate the vegetationin di Verent landscape units and complexes of plant communities in di Verent bioclimate subzones.

3.5. Hierarchicaltables summarizing regional plant commu nities The plant community summary table and associated look-up tables arethe foundation of vegetationknowledge for the CAVM.Separate tables havebeen compiled for each oristic province. Anexample from northern Alaskais shown in table 2.The major columns of the tables arethe subzones, and the subcolumns are the various parent materialtypes. The rows arethe major habitats alongthe mesotopographic gradient. Plantcommunities arelisted with aunique identication (ID) 4562 D. A. Walker et al. s n d e a i n t i t s y a i e i g r o n m s n – D A i e a m e u ( t e ( s r a a a a i s ) ) , e e c l l l m r ) e i e 4 t ) a o r b k 4 B f s t i 9 a n i m a a e 9 b r b i 9 r t i o p 9 e u L o d g 1 s w s s z o 1 ( e c n i h o t k t . . l o ) t i b c u c h l l l n l i s e t t l t i o l a a ( u d o g i r e , i i n o t t o n o s S 6 c b o m i e e s d a f 2 u a T . u g l a t r r n ( o t y a m y e e p e i l l E e o g u l r r e d k k n e c l l N n E a i a t S D d i v a a r U c y . . l a n s e r a n 8 s r 9 a s W W n a a i 3 D ( a g 3 C ( c o n z i m b r D ) e e r u e m s e , ) e t h h – l – S i s t t r o a e l e e m i C o i i f f a ) a ) ) ) , a ) r s t t w a s s l ) ) ) ) o ) ) D c l o i o l e k a s s i a s a r . 4 4 4 4 7 t e a ) c n g h y a r e n n s n s e i t w . i s t a 9 9 9 9 9 e i i i t h o n m d e b e l e ) e r r n s b 9 9 9 9 9 i , g g m n p s s e a t o i u a n p a a l a r 1 1 1 1 m 1 5 n o a a e i s a a C s o r n o n o ( ( ( r ( ( g s a i a v v b 4 i a o b b o o t h o D t r z . . . d . a . o a c i e p n s i u c m l l l l l t w l y r l l o r – – o n c c n i s . l b l m m a a o u a a a a i a i s i g s r l h a d g e o o i v u n u u n t l n t e c – 5 u c e e e t t t t t i p t i t t n n n . n d c i a a a s a d e m i i e v e e e e r d e e U m i d g g u S e d n a s , l ) 5 m n r u n g i r k r a i t m m c u i a a s d s t r r r r r s a a u a r c i i i c o o c m a t l m i l v l l e e l e h e h e e c l s i l l a n I n g e a b h o h o l i i i c s c H i e d a p p ) A n k k k c o k k s s ( r n o p p u t l l l l l i l h e h o k e e o a S y S t y S s S C u p r d t l a t o o s a a a u a a 1 s s d c r r y c p i i . . . u . . n i i t n m v h e o b e o s r r a l r r 6 7 8 c 9 e 0 e r a a y W D W D W T W r W a S o O o e l 2 D ( ( 2 A ( ( 2 E ( ( a 2 E b ( ( m f t 3 d A ( s t ( s m f t o e a t r a t . - a ; s ) s a m m c e e k d l c i b e l i i – i t p s n m d b s x u h a i a y a o i a a e l s r p c l . l o t c r T t n o a o 3 r e s i f M ) s c e y a n A i ( i b k t i , i p r ) 5 U r l l o s u h ) y s b i 8 a g f d t p ) s o n e s a r i f ) 9 e s e i t 5 a o t p s c i 8 c W B 1 y r i 8 o e n y ( p r l . i g t t a d s 9 m e t i i o i T e i r 1 D s u c o r s r n t D c n e ( i ( t r d a d a n . a s o k y d y i o U ) u r y l l l i n n ) r l h p x r i e n c s a o a M e ( 0 p = t k a P a o O D l v 9 N o ( W ; S D o d y n s i . . a a 9 s r e 1 r o 8 l r 9 n e 1 = = c c 1 D ( B a ( g 1 E ( W n n a i n o i d z c i . i v ) b r d c s - e m o d u , e . e a i i a t b r S 2 a – z i m c c n i b s m i s s p l o k p e e a u i n n o c t s t b a y o d e b a a W n , ) d a b a u p a n n r l l n 8 M t t k n p a i l d m s S o s , u d a t a y g ) u A i n l ´ b s a s c a t h c n a i 0 n u a v a v p e a s s y 8 n q a n i o ´ o r d a e U t k 9 s e r c k b m v s , i i n 1 c A r e D e u M ( m o i 2 e d ( ( l ´ a a ( d r i h u l k p h r ) d c o ) a t p r d . m a i p e ) ) 6 h i ´ r r e a a A A o s c b p 0 m t x g D L o d b i m 8 i o a K M l i . . m e h n n o 9 n r c a 3 4 t o a 1 i = = n 1 S ( W U 1 E c ( K ( s r o e h o t e p ) r e N a . w l s r t a y ) s e b u m l t - l e g l . e e i s a p o a r t t e l m e a b y o h e i – m a v r o o t m s r h T a k p i a i c a c i l t m p k . r l c ) s s h a o ) , l o o s a t g o n a b t i f y c a 5 y i l i e u W e w c a c r 8 8 o r s i s o r . o b 1 i b f 9 s g B s i d l c 2 c d i e i i b 1 e r t s i e t t 1 e ( i s a i c i o g d e n a o e p n a i t e t e r i m U u i h t c o n e m h U M r s q d a n e o k n e ( t i d l a a u l n p n T y e r = a u h y s a o ] y t ) x r x t ; . a P y 5 s s e T N m C W r 2 m y ( O D 8 a e a r r g 1 t . . 9 u e a o i D = k = m 8 D ( B ( s 9 c [ 1 c n s n s s o o o a l z a c l . ) – b a . 8 s m ) A e t u s 7 ) , u d e s e r m . l S ) t m n s 9 i t n p p s n a s 7 , o o 1 m i m o a a y a y d e r ( – c 7 7 l r s b t t o o t t e = = = r e a m 9 e d o i c ) h ) ) b r b r a p e a l d d 1 u c o b e e r ) M h u 6 s 6 6 u n b g ( b e t a s t c n n ( a s t s b b w i 9 o 9 9 s r r a b n a e u a l l n e s r r ) s o 9 9 b 9 i e b r e a e ) a i o o b e o r u h ) e a 1 1 l 1 f i c s 6 o u o s c e f r r W i 7 i s l ( ( k ( r s - u W t h u l y o c a e d o , 7 r e W a g . . . f f r h f p a a , N l c l l - h c 9 n e g p n . n B n I g V o i u o e a a a l a ) p 1 i i u D a j ( o I a 1 I y – o r d W r s q ( t n ( o r n i t t t c h s b c g v r e T a , a r n f i o c e e e ) r i e u a a e a r m m m ) 5 c ) o a o t a s r e i h x A l t s s x s l c a m u u u r f g 8 8 g o s i k e e x r p i a u a a a u p l d 7 d y d 7 i e i i i b r d p z e s p l n l S x S l l l S a i n 9 9 y o o o o i a v u u y a a o i . l . c b . i E 1 E E 1 r M s I L S ( N ( r 2 g L S ( N T ( p 3 C ( N ( W a u s a g i S n m i m a r s m c s r e e k i e t u r s i t u h i s a S c a p g s l a c n d l r e o a o B A g l s . n a o o 2 o t p t p z n o e a x t e l t c e i i i o s b d b s y e a a e r a r T H m g D M Sixth CircumpolarSymposium on Remote Sensing of Polar Environments 4563 ) ) ) . 4 6 2 9 c m 9 2 s 9 i . g 9 e 1 . d t m n t l i 1 ( i m i – – o a t c ) a n . . ) l a r c a l l e m x a s i i t e t l l a a U k e e o s n a e r o o a c h m b t t f o f n o a s i r i e e u L t o n . s r e r e d s i C t g l r r a g k r n k m g m – a l e a e i e c a a u u i l t r n m a v l k k t L r m i m t i i o d l l n ( t ) ) i o o i e r u o c l o a a W s s i i t r c m ) h c e l i s a . d e d a T d p s o W e W l i a s x e e g ( n ( f m o i i c p D i b . . - y i l l b a b o ) t i a r o f r . a y a s t i i D D l t 9 N n E s r E D S u a r w w . . 8 s M o s x a . g u . . o o e i 9 a a 0 n q 1 2 n n n M N M E 1 h = 4 a a ( ( 4 C ( ( s 4 S ( ( t s o z . b 2 u . . g m s 2 – n – S i i e n e m . m t e t i r m l i l i t a s ) e s o l s – – t m a a m c n e z r r e k c e ) i t e s t e o n o t o i t e h e e i i s r n a d l U ) 4 c c a c s a e e m i k k e c s n h a 9 - r l l r i i u a n c o e o s t c v a r d e 9 r a r a e r i o a i t s C e t n n o l m n c 1 o h d g n b e i e r a k r o t a W W g l c . l n a c c f i l u l d a s L i i a r n m t m s s a l a u e ( a i d d t i d e g t u m n v s t m ) t e c n n l ) i n m t a e ) n u W s t i a e w ) m i c e r a a a e s c u u i g i n . d n e d ) c f t r s s i e l d c i i a g e s r W d r R r m i o o u c m l r i p e D ; b ( ( - h . e a e e x b l f r I ) d h c i a o b . a y p p i a A k ) k ) k i ( l 9 t p m a l l l h c s x x S S C S 6 6 r w w t 8 o i i a a a s M t a s i l l a . m 9 . 9 . . o o i 9 o e a r a a 1 9 2 9 3 4 o n n W W W E 1 h o n = 3 E c ( 1 w f 3 S ( 1 i 3 C ( ( s 3 S ( ( t s . - . . - e m , a ) s c m m D s i d n e u r – m y – . t n , o l r d m g ) e e a o s r a r x a t d t o s t i n o n , i c l r M e l i s , a , l e w n a c h d a t 2 i t n o , k s 6 r 7 t a e c l e s i p r o a E f l t i x a u W c i t a e ( . b S S o b n , d i i a M e e ( U U r i d d l l u t o ; ) ; y i r a r m w m n g ) . ) ) ) s a o e m o e e c a g W e l a f ) e f e o o E 5 5 i 0 u 5 p i a e t a p p s c m . c B p g r r – t C n m t i 8 8 9 8 y d n y n y o n o s o i o y e g a a i d – 9 9 9 n 9 D e i ) n c T s l o i t i T T e h s g l 1 1 s 1 1 s o u . L c s a t c u o n ( r ( ( ( i s s p u t ( o e d d d a d d p i n a i f o p a a o o d l i l p e i ) u r r r g r M e n y n i n i n e r ) a r o r r e o e e e d e b r a r C n , c m s o a a f t i i 0 t i t t n k g k k k e P a a s a x D D E t . a w s l l l l e t 9 N v e i l c s S S u ( d D ) y n l . u . . s a l a a o a e t 9 p e k e a r i a o 0 r q 1 2 = a e n o d y r 1 a = = 2 b a J W c w l 2 C ( W t D W m s 2 S ( W r t ( n n e o u . z n – b r r i i m i e e t u . n b b m S n ) g o s b s b o m o o s n e e e e c t i d t , , t ) m h r C l a r a W W 6 s 1 e ( ) o r a e l r a n 1 1 t k c l h d a d b o i s m u t t c s a i n g i n - b s i . i m m t m – l r a a a y n n u a i i u l 2 r t s s s q t r r m t ´ ´ a i a a U e U t a i ; o e a u e c v v h , , s i t i n u l A h t l W i E o o 2 2 d d ( q p ( ( , i o e b k k k e f a o c 3 p i ) ) p r y p r i a b ) ) t 3 ´ ´ o r a o a a a A x s i 0 0 T t e s E B u w m m i 8 8 r s M M . g . o 9 9 o o n a a 5 n 6 n 1 1 = = 1 a C ( K ( 1 C ( K ( s U s i l i s ) s t s t u i y e s a l r t o h a u e b t a e o q r k r a , l c t a a s b ) 1 s a , c s u 2 o b l x y r d u e W a w t a i s a r c P , o l B a n 0 . c t d c i 1 e a e o C a U t d - e o n i s a W M h a c o u ( m d t d a p i e l ) l e u . n r ) o o p r r a o f a t 5 m y i l e P D N s i l 8 N v C T ( . m a . e 9 b m 0 r 1 o o e i 1 a = 1 b c ( ( c 1 s t n o z ) . s t b r s d m r u t , e . a e e e . S 9 m b o r b k m s l c e o g e m b W – e c a ( e k n x , p t w m ) t a e l m i I ) e ) i a y – m s t o o u l h a ) W o W r i l r ) 6 a t u c V T n r t c o o e , a 6 . r w f 9 s . d s , , W ) a i I r h i 5 9 i o ) s o d ) 9 l C t r m b i I . i d a t g 1 9 r m i g - h – 1 u l e s I n 8 l u – s e 3 r i n 1 t ( e p n v e s a 7 a e t w n i m ( a i t 1 m l V n a u a m . o t 9 r a t p o l i e a o u . o c l s u a B s i i l 1 w V d r u g o y c d a c i e e s l L m ( ( a r a r d d s q t n ( o E T i o t i s g a g u e e e a m f p t a r i a t c i s i e ; ; ) i - x a l n d d l h b p n e ) e ) ) t i r i i l r t i y l A 2 x c s e t o s o b l a f 7 8 7 a i d h s e a i 1 a r a u r r w b 7 7 7 m i r a d n N N t C S P x u , g l a a e i i o r 9 9 9 a a e l e a . q 0 n c . . a t n 1 E E 1 1 = = 4 s a ( W 1 ( a C E a s 5 C ( ( n 6 S ( ( ( s c i h p g a n r o s g l d a o s e t p e t b t n o a i t e t s i i o w d t b s o e a a e n r H m g W S 4564 D. A. Walker et al. - e ) — s k – y s k s r e a . e u l f r s s D d s ) o p e s i ( . s n t a s o ) ) s – A n n o a m ) r ) ) i ( e q a u r - o e . d r i ) i s 7 7 t i t l m i s k s o n s s V p l ) 9 9 i d m o s o a r e n s e b s – f A o 9 9 o n i c e i d f d n u r L n n o m 1 1 k i a r ; i a i v s i n e l ( ( t l c a a o g a k h a h m a x u b . . c ) p l c i e c V l c b l l l i s l c s i u t a a u l d p t o l u l a b a s e e ) d o r S n i a i o c o r d a i i i a k g s c c u i o t t h r i d c r o h o n a c v a i n b s e e s w a h s i a T r r o h o m m o o t i a c m r r a r n ( l s s l r s i u u l i w v l y e e e e S l u o t t d — u p t l r r p p o a r v k k e e e . s l n e o e i . l l N l E d i l c c a r E T C D v t u s i i i d a a b e p k h o l l l c s l . . . n . o e a l c u v a r a o 3 4 5 6 a a i t i W W W n A A A i 4 S p ( 4 S r ( ( s 4 A ( ( 4 L ( r o L c z a b s . ) l f s u s k d l g s i o e s S – a n i l d r A e a s d n i n ( t ) ) l o i ) s a i s ) s o r u u t b e k i i ) o e x 4 n t e e a i s m u V v i o a 7 l t m a 9 r e n r T i a s i a o n l 9 e r a r – e s u 9 l e h I t p d k 9 r o r m S v u r o 1 s ; . p s i C f a . t n o ( 1 i c u t a b d c h m s t b a l V h n m . c u . l — c i c w u l m l o l i , r p u l a o a s o i a t s S o u a A a b l l m m o r ) o i l k c v n a e i – i p k g . l s u u c i o t h t i a r i c i a s c r c l n s v c n i h l e e o e d n a i e a r o h E t m c m o i o a l W d r r r a s f a s e r i c m u u m i S w ( l i t l b . r e e c i — d t t I t = p c o i l r , o p a ; ) a t h r A e k e k . s r ( r e t l . m l s s d a c d s c c a V e L C v u i s s d s l s l i i d a a t h o l c l s l . g r . . m a o e e n a g c a r r a r n o 5 n u 6 7 e o i W W A A A o 3 S p p a p ( ( w 3 S r ( p o 3 d c ( ( c e , n f y ) e ] o a s 8 . c ) s s s . d w e n B o n s e U – ) t i n r o ) t o a e m a – l a i a l e i e s i p l 7 ) l r s l V i s i i b p m s t r 9 l i n o o o e s i e n y a s e – f o 9 o i t l W i c f c b k h c n , v o T 1 i i s i ( r a u e ( y t c P d V d g h ) r s a b i a a x u d . n - c e r e o l c l 5 c u t a a n i c e o B r S a d l k l i r 8 a ) ) t t i n i a o i i a s g i . s c d s i t 9 h e n t P i h r r n s v n n b 1 e d S o s o c c e i i m ( ; o a m m o o d n a a n S a a r v l s s r u u l w l i i u = r a s y e l n [ d t t l i r p r e r e p p o p c ; r o e e k e . n b i v . l s k d d P i c c a E L D y i . v s l s v N i i u a t ( r D p d ) o h o l l s . . . o e a r i c a c u a r o a r o 3 4 5 e i h W D d A a r c 2 S p ( 2 S r ( p W s 2 L ( ( n e g a o u z d n b — r i e n t u k b S a n e s b s x y i e o i s e e l l k h r t , b a t d C a n W 7 ( ) a S , r C a n 1 t k b 3 – d b s a u t 2 o a i n t b s s . t r i m a t n u a a p i 2 a s a q e n ´ e a ; n U t v r a s e c n v , l i t l A U i d a o s 2 d ( s r ( i b n x i k o i c s ) a p r a m t l a ) l ´ n a a a A ) l b e 0 T m e m S a m l 8 u x M I . u r o 9 b a c 7 l q h i 1 a = ; 1 a ( K ( s e t d s i s c e a – e o ) l s v t i m e s t — s t u a i c s a n l o i w . r o A u o i c t f ( a v o l s i b o m , . o t r b p o y u r e a a l p r t u d l i a c r p e s e i a p r o t . B c a i c m s p o c E l B c i s e r u ) l d a i : o a n a t i = i a b S s c s h c y s i o a c – a l i d a e l i V d s i a t u o s b i n i o i i n r p c l c o s m — s e k o a P E s i r e f N x C d t i n ( . o h a e t a r c o e 2 l n e P a v 1 A ( l a S n n i n a t l o s z a s i t b n r o r i u n t e e g y S e b l r k s s a l a b a s e a e e i u t B l m r a – q a ) W W r ) e a p n e t , , e i l m w d s e I i y 5 c o b a l r o b I g 1 r e a I l u b Y r r h t i s e a e t o V a s s d s p s h c i a B a i y i t o u i e h m ( d s l ) r t r T p i u t t p b a c , ; , s . d p P e ) ) a a 7 i t l a t A o l 8 7 s h h t o s i ; 7 7 i c N n c t t P s 9 9 n i o . t 1 1 U l s d = 7 C ( ( ( U ( a a n o i a p c s e a l d c i g n h e a e p g c i l a n a n r s f o o e e g l r c c d a o i u t p s o t n S c t o a i t e m t 1 s i i i a o d d b e s i e a r l a e c t r H m g S a P Sixth CircumpolarSymposium on Remote Sensing of Polar Environments 4565

Figure6. Vegetation on acidic and alkaline substrates in subzones A andB. Modied from Edlundand Alt (1989).Speciesshown are: 1, Luzulaconf usa ; 1b, L . arctica; 2, Papaver radicatum; 3, Potentillahyparctica ; 4, Alopecurusalpinus ; 5, Phippsiaalgida ; 6, Saxifraga oppositifolia ; 7, Poaabbreviata ; 8, Draba sp.; 11, Carexaquatilis var. stans ; 12, Pleuropogonsabinei ; 14, Eriophorumtriste ; 15, E.scheuchzeri ; 17, Dryasintegrifolia ; 18, Cassiopetetragona ; 19, Arctophilaf ulva ; 20, Hippurisvulgaris ; 21, Oxytropisarctobia ; 22, Hierochloealpina .

Figure7. Conceptual mesotopographic gradient for arctic landscapes. number, atwo-species plant community name, and the publication where the community is described. Plantcommunities that areonly described locallyare given ‘plant community type’(comm.) designations. Those that have‘ association’(su Yx -etum)names havebeen compared globallyto types described from other areasand havebeen incorporated into the Braun–Blanquet syntaxonomic nomenclature system (WesthoV and vander Maarel1978 ).This European phytosociological approach has manyadvantages as aninternational classication system atthe plant community levelbecause of its well-established procedures, long history, and wideapplication throughout the Arctic (Daniels 1994,Elvebakk 1994, Dierssen 1996,M. D.Walker et al. 1995,Matveyeva 1998 ).Anexample table is shown for the Alaska oristic province (table 1). More detailed information for the plant communities is contained in separate 4566 D. A. Walker et al. look-up tables that arelinked to this table viathe plant community identication (ID)number. The linked tables contain information such asdominant plant growth forms, plant species, horizontal structure, verticalstructure, primaryproduction, and biomass (see look-up table 2in Walker 1999).

4.Integrated mapping methods Vegetationis interpreted on the basis of ‘integrated vegetationcomplexes’ ( IVC). These IVCsare derived from acombination of information on satellite-derived imagesand information from existingsource maps, such asbedrock geology,sur cial geology,soils, hydrology, and previous vegetationmaps. The procedures for dening these complexes aresummarized in gure 7and described briey below. Supplementary information canbe found inWalker (1999). First levelgeological features (mountains, hills, plains, tablelands) are rst interpreted directly from the AVHRRimage (see step 1,and layer1 in gure 8).

(a) (b)

Figure8. Six-step procedure for making the CA VM. Seetext for brief synopsis of each step. Summarizedfrom Walker ( 1999). Sixth CircumpolarSymposium on Remote Sensing of Polar Environments 4567

Information from other simplied source maps, such asbedrock geology,sur cial geology,per cent watercover, and soils, areused to create additional map boundaries (steps 2and 3in gure 8).These procedures arebased on the principle that geo- morphic features arethe primarycontrols of vegetationboundaries. This process considers waterand landform boundaries asunalterable (hard)boundaries. Boundaries controlling variablessuch assoils, and vegetation,which changeacross ecotones or gradients, areconsidered soft boundaries, which aremade to conform to landscape boundaries whereverpossible. The number of additional polygons is minimized through the integrated mapping procedures. The result is the ‘integrated land-unit map’( ILUM).This map has allthe essential terrain information. Atthe next step vegetationinformation from avarietyof sources is used to create additional vegetationboundaries on the integrated map (step 4, gure 8).The NDVI map (gure 2)and other vegetationmaps areused to help delineate other features that maybe visibleon the AVHRRimagery. Where possible the polygon boundaries aremade to conform to those of the ILUM. This newmap is calledthe ‘integrated vegetationcomplex’ map (IVCM).The names of the complexes generallycorrespond to landscape features such as‘ acidicmountain complex’, ‘acidicmire complex with less than 25%lakes’ , ‘nonacidic plateau, basin or plain complex’, ‘nunatak complex’, ‘island complex’or ‘largeriver oodplain complex’. The IVCMis the only map that needs to be digitized in the mapping procedures. Eachpolygon on the map is given aunique IDnumber. Anattribute table contains eachpolygon IDnumber, followed bya series of codes that describe the polygon’s attributes (vegetationcomplex, bedrock geology,sur cial geology, per cent watercover, etc.). Step 5of the mapping procedures has alreadybeen described in the creation of the plant community summary table (see table 2),which contains the basic plant- community information for agiven oristic region. Alook-up table contains detailed information for eachcommunity (plant species, growth forms, production, biomass, etc.). This table is not shown here, but anexamplecan be found in table 3of Walker (1999).The creation of the nalmaps assumes that similarvegetation complexes within agivencombination of oristic region and bioclimatic subzone willall have the same suite of plant communities. If there areknown exceptions that do not conform to this logic,these map polygons canbe selected out and recoded. Primary, secondary and tertiary (dominant and subdominant)plant communities arelisted for eachcombination of subzone, oristic region, and vegetationcomplex. Atstep 6,awidevariety of vegetation-related maps canbe created byreference to the linked tables that list growth forms, production and dominant species (Walker 1999).

5.Conclusion Circumpolar AVHRR-derivedfalse (CIR) and maximum NDVI imagesare the rst products from the Circumpolar Arctic VegetationMapping project. Theyprovide the keymeans of makingan image-interpreted vegetationmap of the arctic tundra biome. The CAVMis essentiallya GIS databasethat uses expert knowledge of the relationship of plant communities to climate, parent materialand topographic factors, to predict vegetationwithin landscape units that canbe delineated on 1:7.5Mscale AVHRRimages. The databasewill be asource for creatinga widevariety of map products that willbe useful for manyaspects of arctic research and education. The rst draft of the CAVMis expected in 2002.The methods outlined in this paper could be applied to vegetationmaps of other biomes. The imagesin this paper are 4568 D. A. Walker et al. availablethrough the UCAR /Joint OYce for Science Support, Boulder, CO,USA; e-mail:[email protected].

Acknowledgments Allthe present and past participants in the CAVMproject havecontributed a greatdeal to the ideas presented here. Listed alphabeticallythey areGalina Ananieva, NancyAuerbach, Christian Bay,Larry Bliss, Udo Bohn, Fred Daniels, Nickolai Denisov, Dmitri Drozdov, SylviaEdlund, Eythor Einarsson, ArveElvebakk, Helmut Epp, Mike Fleming,Gudmundur Gudjonsson, ElenaGolubeva, Irina Ilyina,Bernt Johansen, Seppo Kaitala,Andrei Kapitsa, AdrianKatenin, Sergei Kholod, Yuri Korostelev, CarlMarkon, NadyaMatveyeva, Evgeny Melnikov, LiaMeltzer, Dave Murray,Nataly Moskalenko, ValentinaPer lieva, Alexei Polezhaev, Raisa Schelkunova, Christopher Smith, MarthaRaynolds, Irina Safronova, Steve Talbot, Svein Tveitdal,Maike Wilhelm, Steve Young, Konstantin Volotovskyi, Tatyana Yurkovskaya,Boris Yurtsev, and Steve Zoltai.Special thanks to Kent Lethcoe and Steve Muller for help in preparation of the AVHRRimages and to Fred Daniels, ArveElvebakk, Dave Murray, and Boris Yurtsev for their thoughts on vegetation zonation. Funding for much of the CAVMwork and this paper camefrom the National Science Foundation OPP-9908829.

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