Middle Oroarctic Vegetation in Finland and Middle-Northern Arctic Vegetation on Svalbard

ACTA PHYTOGEOGRAPHICA SUECICA 82 EDIDIT SVENSKA VAXTGEOGRAFISKA SALLSKAPET

Risto Virtanen and Seppo Eurola

Middle oroarctic vegetation in Finland and middle-northern arctic vegetation on Svalbard

OPULUS PRESS AB UPPSALA 1997 ISBN 91-72 1 0-082-6 (paperback) ISBN 91-72 1 0-482-5 (cloth) ISSN 0084-5914

Editor: Erik Sjogren

Editorial Board:

A.W.H. Darnman, Manhattan, KS F.J.A. Daniels, MUnster L. Ericson, Umea D. Glenn-Lewin, Wichita, KS 0. Hamann, Copenhagen H. Sjors, Uppsala H. Trass, Tartu

Technical Editor: Marijke van der Maarel-Versluys

© R. Virtanen & S. Eurola 1997

Edidit: Svenska Vaxtgeografiska Sallskapet Villavagen 14, S-752 36 Uppsala

DTP: Opulus Press AB Printed in Sweden, 1997 by Fingraf, Sodertalje

Acta Phytogeogr. Suec. 82 Middle oroarctic vegetation in Finland and middle-northern arctic vegetation on Svalbard 3

Abstract. Risto Virtanen and Seppo Eurola. 1997. Middle (2) At the southwestern-western coastal region, ridges were oroarctic vegetation in Finland and middle-northern arctic veg­ occupied by communities characterized by Racomitrium etation on Svalbard - Acta Phytogeogr. Suec. 82, Uppsala, 60 pp. lanuginosum. These graded to moss and lichen-rich heaths, ISBN 91-721 0-082-6. (9 1-721 0-482-5.) while depression sites harboured snowbed communities domi­ nated by Sanionia. Plant communities of the middle oroarctic zone ofnorthwestern (3) In the Dryasregion, ridge heaths approached the vegetation Fennoscandia and middle-northernarctic areas of Svalbard were of polar deserts. The sheltered sites were characterized by studied to describe the community types and their ecological moss tundra communities and Sanionia snowbeds. relationships. The analyses were based on data sets collected both from subcontinental mountains of Finnish Lapland and from a On the mountains of northern Fennoscandia, the plant com­ geographically broad area of Spitsbergen, the main island of munities seemed to be clearly differentiated in relation to the Svalbard. Plant communities were classified by a divisive clus­ bedrock. On Spitsbergen, some edaphic differentiations exist tering method (TWINSPAN) and the ecological relationships of among plant communities, but some of the differencesobv iously the community clusters were examined by detrended corre­ reflected climatic differencesamong the areas studied. spondence analysis (DCA). For northern Fennoscandia, It was shown that the sheltered slopes and snowbed sites of edaphically differentiatedseries of community types from wind­ Spitsbergen harbour copious moss vegetation dominated by exposed ridges to depression sites with snowbed vegetation were robust (mainly pleurocarpic) mosses, whereas the corresponding described. On siliceous substrates, the types in the series con­ habitats in northern Fennoscandia seem to consist of small formed to those described earlier. On calcareous soil, the Dryas bryophytes growing together with prostrate vascular plants and octopetala-Carex rupestris type occupied exposed ridges, the lichens. One reason for this may be the absence of herbivores Cassiope tetragona-Dryas octopetala type sites with moderate (Norway lemming or brown lemming) feeding on mosses on snow cover, and the Salix polaris-Silene acaulis type moderate Spitsbergen. snowbed sites, while late snowbed sites harboured communities of the Saxifraga oppositifolia-Ranunculus sulphureus type. For Spitsbergen, the following three regionally distinguished series Nomenclature: Vascular plants (Lid & Lid 1994), bryophytes were described: (Soderstrom et al. 1992) and lichens (Santesson 1993; Andreev (1) In the inner fj ord region, wind-swept ridges were character­ et al. 1996). ized by the Saxifraga oppositifolia-Hypnum revolutum com­ munity. This community shows a gradual transition to com­ munities rich in Dryas octopetala and mosses on sheltered Risto Virtanen and Seppo Eurola, Department of Biology, Uni­ slopes. versity of Oulu, P 0. Box 333, F/N-90571 Oulu, Finland.

Acta Phytogeogr. Suec. 82 Contents

1 Introduction 5

2 Material and Methods 6

2.1 Sampling methods, sampled areas and their environmental characteristics 6

2.2 Climate 7

2.3 Grazer communities 10

2.4 Numerical analyses 10

3 Results: classification and ordination 11

3.1 Northwestern Fennoscandia 11 3.1.1 Festuca ovina-Potentilla crantzii group 14 3.1.2 Alectoria group 16 3. 1.3 ]uncus trifidus-Cassiope tetragona group 18 3.1.4 Salix herbacea group 21 3. 1.5 Ranunculus glacialis group 23 3. 1.6 Saxifraga oppositifolia group 24

3.2 Spitsbergen 25 3.2. 1 Luzula confusa group 26 3.2.2 Papaver dahlianum group 28 3.2.3 Dryas octopetala group 29 3.2.4 Alopecurus borealis-Aulacomnium turgidum group 30 3.2.5 Sanionia snowbeds 32 3.2.6 Wet moss snowbeds 32

4 Topographic patterns: series of communities in ridge-depression transects 35

4.1 Northwestern Fennoscandia 35

4.2 Spitsbergen 37

5 Vegetational differentiation in relation to edaphic factors 39

6 Abundance patterns of bryophytes in topographic and regional gradients 41

7 Acknowledgements 43

8 References 43

Appendices 47 1 Introduction

The Fennoscandian oroarctic (alpine) vegetation has been since the twenties (e.g. Summerhayes & Elton 1923, subject of study in many classic works (Wahlenberg 1812; 1928; Acock 1940; Hadac 1946; R(Zjnning 1965; Eurola Nordhagen 1928, 1943; Kalliola 1939; Gj rerevoll 1956; 1968; Hofmann 1968; Hartmann 1980; see also Elvebakk Dahl 1957) providing a comprehensive reference to veg­ 1994). The approaches used in these studies reflect the etation types and their ecology. These studies mainly ideas of many phytosociological schools. Consequently, concentrate on the vegetation of south-central Scandina­ the described vegetational noda are not always easily vian mountains and are restricted to the lower oroarctic comparable (Walker et al. 1994), and it is sometimes zone. From the middle oroarctic zone in the North, rather difficult to determine whether differences or similarities tentative descriptions are available (Fries 1913; Nordhagen in vegetation are real or whether they reflect methodo­ 1936,1 955; Hedberg et al. 1952). Most recent gradient logical differences between different authors. This has in studies of oroarctic vegetation covering a broad geo­ part hampered ecological comparisons between truly arc­ graphic area in northern Fennoscandia include main topo­ tic vegetation and the vegetation on the mountains of graphic, altitudinal and regional patterns of oligotrophic northern Fennoscandia. In the present paper, we have mountain heath vegetation with a large number of sam­ aimed to start by classifying plant communities based on ples (Haapasaari 1988; Oksanen & Virtanen 1995). These samples collected in a directly comparable way from studies outline the vegetational relationships between northern Fennoscandia and Spitsbergen, compare the de­ Fennoscandian mountain vegetation and the vegetation of scribed community types with those found in the earlier truly arctic areas. Gross climatically parallel areas for the literature, analyse the main gradients by indirect ordina­ middle oroarctic zone (Ahti et al. 1968) exist on Spitsbergen tion, and summarize the main vegetation patterns in the where we also encounter gradients to northern arctic form of mesoscale vegetation series. Thereafter, we dis­ tundra and polar desert zones (Elvebakk 1985). The veg­ cuss the role of edaphic factors in differentiating commu­ etation of Spitsbergen has been treated in several works nities and patternsin bryophyte abundance.

Acta Phytogeogr. Suec. 82 2 Material and Methods

2.1 Sampling methods, sampled areas and vegetation were not sampled. A systematic sampling along their environmental characteristics ridge-depression topographic transects was favoured when­ ever possible. Species cover was estimated with the Hult­

The material was collected during several occasions over Sernander five-unit scale, with an added symbol '+' for a long period, and consequently the procedures used by us very low abundance, or by a direct estimation of percent­ were prone to variation in sample plot size and method of age cover. The cover was noted as an estimate of the area placement of the sampling plot (Table 1). One of the main of foliage projection for each species. criteria was to sample the variation of vegetation along In northwesternFennoscandia, the vegetation was sam­ presumed main ecological gradients (soil, topography) to pled on subcontinental mountains of the northwestern a large extent. Consequently, wind-exposed sites, late Enontekio community. One part of the material was sam­ snowbeds and various heath types were analyzed both on pled at Lake Kilpisjarvi (473 m above sea level, 69° 03' N, calcareous and more or less siliceous substrates. The 20° 50' E) where mountains reach to altitudes of more sampled sites were mostly underlain by glacial till. The than 1000 m above sea level. Many of the mountains are azonal vegetation on other soil-types, e.g. coastal pla­ characterized by overthrown Caledonian nappes with rela­ teaux with deltas, moraines or clay fields with sparse tive altitudinal differences of more than 500 m (Fig. 1).

Fig. 1. View over the mountains near Kilpisjarvi. Mt. Jehk:ats,alt. 950 m, with middle oroarctic heath vegetation. August 1987. (Photo: Risto Virtanen.)

Acta Phytogeogr. Suec. 82 Middle oroarctic vegetation in Finland and middle-northern arctic vegetation on Svalbard 7

The other part of the data was sampled from mountains intercalated with marbles. The bottom of the Van northeast of Kilpisjarvi, where the valley between the Mijenfjorden area is composed of Tertiary deposits which mountain Guonjarvam (69° 07' N, 21 o 10' E) and Duolje­ are replaced by the Triassic, Jurassic and Cretaceous huhput was one of the main sampling areas. The mountain sediments in the Kjellstromdalen-Agardhdalen area. Con­ slopes are mainly gentle, shaped by continental ice sheets, sidering Elvebakk's (1982) analyses, the Hecla Hoek reaching altitudes of more than 900 m above sea level, bedrock-based substrates and those with mesozoic depos­ while the mountain tops reach altitudes of about 1100 m. its give variable reactions from acidic to alkaline. The The terrains are mostly covered by soil cover, contrasting material from Spitsbergen was chiefly collected in areas with the vast stone-block districts north of this area (the where parent material of soils is circumneutral, and sam­ Gahpperus-GoddeniSsak area). The soil formations are pling sites with clearly siliceous and strongly alkaline often modified by cryoactivity that maintains polygonal parent material were not covered by us. This differed from stone rings (Ohlson 1964 ). The sites comprise both the situation of northern Fennoscandia where parent ma­ siliceous and calcareous soil substrates (Uusinoka 1980) terial was more distinctly differentiated into siliceous and which reflect the occurrence of bedrock both with cal­ calcareous ones. cium carbonate-rich caledonic dolomites and silicate-rich mountain schists.

On Spitsbergen, the study sites were more broadly 2.2 Climate distributed in three main areas. The first of the study areas was the inner fjord region of Isfjorden 08° 10' N, 15° 40' Climatological data from the studied mountain sites at E), where most of the samples were obtained from the northwestern Fennoscandia are scarce as there are no Adventdalen-Sassendalen area. The second area extended meteorological stations at higher altitudes. To provide from the west-southwestern coastal area of Hornsund some estimates for the climatic conditions in our study or 00' N, 15° 40' E) to the mouth oflsfjorden. The exact area in northwestern Fennoscandia, we calculated mean location of the sample sites of these two subareas is given temperatures for locations at 880 m above sea level based by Eurola (1968). The third study area ranged from the on data from the weather station at Kilpisjarvi (Fig. 3). Slettvika-NordenskiOlddalen area at the bottom of Van The records were available for the subalpine forest zone Mijenfjorden or 50' N, 16° 40' E) to Agardhdalen on the (altitude 480 m a.s.l., Jarvinen 1987). The transformation southeastern coast of Spitsbergen 08° 10' N, 18° 20' E) was performed according to recommendations of the N or­ (Fig. 2). wegian Meteorological Institute to use a cooling rate for In the inner fjord area, the Triassic, Jurassic and Creta­ periods December - February of 0.5 oC/100 m, March ­ ceous sediments prevail (Major & Nagy 1972). The moun­ August 0.7°C, September - November 0.6°C. Some meas­ tains on both sides of Adventfjorden consist basically of urements were available for the alpine belt about 40 km Cretaceous sediments, overlain by lower Tertiary strata. west of the study sites (Mook & Vorren 1990). Mook & At Sassenfjorden, the bottom part of the valley is built up V orren ( 1990) gave data for the period June - October for of Permo-Carboniferous sediments (Winsnes et al. 1962). altitudes 915 m and 1110 m measured 20 cm above­ The coastal areas consist mostly of Hecla Hoek rocks ground. The mean temperatures for the station at 915 m composed of Proterozoic and older Paleozoic sediments for the months June - October were as follows: 6.2, 6.4, and they were strongly faulted and metamorphozed dur­ 8.7, 2.7 and- 2.2°C, and for 1110 m 1.3, 1.8, 3.9,- 2.4 ing the Caledonian orogeny. The studied sites at Isbjorn­ and - 4.8°C, respectively. These values indicated that hamna are composed mostly of gametiferous mica schists temperatures decreased by ea. five degrees for every 200

Table 1. Sample material from northern Fennoscandia and Spitsbergen. N = no. of samples.

Plot size (m2) N Year of sampling

Northwestern Fennoscandia Mts. at Kilpisjarvi 0.25 126 1986 Mt. Guonjarvam and Gahpperussak 4 81 1989-90

Spit bergen SW-W coast (Hornsund) - Inner fjord area 25 58 1964 * Kjellstrom-Agardhdalen area 25 56 1969

* Data from Eurola (1968)

Acta Phytogeogr. Suec. 82 8 R. Virtanen & S. Eurola

Fig. 2. View over Mt. Friedrichfjellet, midway between Agardhdalen and Bellsunddalen. Moss-rich tundra and Bjarrnebreen. July 1969. (Photo: Seppo Eurola.)

m increase in altitude. As the highest station was on the any area on Spitsbergen. In the upper altitudinal limit of peak of the mountain, it might have been climatically the zone they are equal or even colder than in the most pronouncedly extreme. Mook & Vorren (1990) also gave areas of Spitsbergen, as indicated by the data in Mook & recorded minimum temperatures in June-August. At an Vorren (1990). The majority of samples of Fennoscandia altitude of 915 m, these were - 3.8,- 0.1 and - 1.5 oc, are from altitudes over 900 m above sea level, and thus,

- while values at 1110 m were - 6.3, 4 .3 and - 6.5 oc, the actual temperature regimes are more similar than respectively. indicated by the graphs, (3) differences between maxi­ The temperature data for Spitsbergen (Fig. 3) were mum and minimum temperatures are greater in Fenno­ obtained from the records of three meteorological sta­ scandia than on Spitsbergen, (4) the values of Hopen tions encompassing the study areas (Steffensen 1982). indicate a colder climate corresponding to northern arctic Isfjord weather station was a coastal station, while Long­ or upper oroarctic zones (Mook & Vorren 1990), and 5) yearbyen represented an inland station, and the data avail­ night frosts in the summer are more infrequent at able from Hopen probably corresponded closest to condi­ Spitsbergen than on the mountains of northern Fenno­ tions prevailing at the Agardhdalen region. We found scandia. On Spitsbergen, some frosts of - 1.8°C were published data from Hornsund for a one-year-period only recorded only in July-August (Steffensen 1982). 1957-1958 (Eurola 1968). Precipitation data were taken from the meteorological The temperature curves of northwestern Fennoscandia station reports (Steffensen 1982, Finnish Meteorological and Spitsbergen show that (1) winter temperature regimes Institute) and should be considered as estimates for the are practically similar, but near-ground temperatures are actual rain fall (Fig. 3). The precipitation curves show probably lower in Spitsbergen due to thin snow cover (see more variation than the temperature does. In northwestern below), (2) the calculated values for mean temperatures of Fennoscandia (Kilpisji:irvi area) the curve shows a rela­ the growing season in the lower part of the middle oroarctic tively high amount of summer precipitation. In the inner zone of northern Fennoscandia are higher than those at fjord region of Spitsbergen the annual rainfall is the

Acta Phytogeogr. Suec. 82 Middle oroarctic vegetation in Finland and middle-northern arctic vegetation on Svalbard 9

a)

10

5 • Kilplsjarvl880 m

c i 0 --+-- Longyearbyen E • � -5 lsfjord Radio

! --o- Hopen 0 -1 0 E o. Hornsund - 1 5

-20

b)

70

60 -••- Kllplsjarvl

� 50 0 --+-- Longyearbyen E 40 c • lsfjord Radio 2 30 E --o- Hopen E 20 10 ----b- Hornsund 0 c a :; 0 a -, -, � 0

Fig. 3. Temperature (a) and precipitation (b) characteri tics of the study areas. Kilpisjarvi: the monthly mean temperatures for north we tern Fennoscandia. Calculated values for 880 m above sea level based on the data of the weather station at Kilpisjarvi ( 480 m above sea level). The transformation as performed according to lapse rates for the periods December-February 0.5° C/ 100 m, March­ August O.r C, September-November 0.6° C. Other stations on Spitsbergen and Hopen according to Steffensen (1982). The data for Homsund are from graphs in Eurola (1968), based on measurements of 1957-1958. The precipitation values ofHomsund are smoothed using running means of two successive month .

lowest: the annual mean precipitation in Longyearbyen is during winter. As a rule, the snow cover is thicker on 208 mm. The coastal areas, western Isfjord and Hornsund mountains of northwestern Fennoscandia than on receive about 400-450 mm. On Hopen, the annual mean Spitsbergen. In the birch forest zone of the Kilpisjarvi is 400 mm. The inland station, Longyearbyen, shows the area, the mean maximum snow depth is about 70 cm lowest values during the winter months. In the coastal (Hiltunen 1980). Above the treeline the distribution of area, the winter precipitation is relatively high. The low snow is more variable and in depression sites the depth is winter precipitation of the inner fjord region is in accord­ usually 1-2 metres or more. The soils in the snow bed sites ance with the typical situation in the circumpolar Arctic are frozen during winter (Hiltunen 1980). The snow depth (Aleksandrova 1988; Oksanen & Virtanen 1995), while data from Svalbard are even more scanty than in north­ the relatively high values of the coastal areas indicate a western Fennoscandia. According to the records avail­ higher degree of oceanity. able, the maximum averages are about 30 cm in the inner Little information is available on snow conditions fjord region (Eurola 1968). In depressions there can be

Acta Phytogeogr. Suec. 82 10 R. Virtanen & S. Eurola

deep snow fields. The situation at Spitsbergen may corre­ 2.4 Numerical analyses spond to that recorded at Barrow, northerncoast of Alaska. According to Dingman et al. (1980), the temperature on Despite the materials containing sample plots of different the soil surface can be- 25°C in the coldest periods of the sizes and the abundance values being estimated by differ­ winter. The thin snow cover gives weak insulation, and ent methods, we found it beneficial to jointly analyze the thus the ground is exposed to extreme low temperatures. data sets in order to directly compare the vegetation units Permafrost is omnipresent on Spitsbergen and plays a (Podani 1984: 80-83). For the numerical analyses, the significant role for site conditions (Eurola 1968; R�nning cover classes were transformed to corresponding percent­ 1969; Stablein 1971). age classes (Oksanen 1976). Numerical analyses of the vegetation data were performed using these percentages. The TWINSPAN-clustering (Hill 1979) was used to pro­ duce a classification for the plant communities. In the 2.3 Grazer communities TWINSP AN run, the number of pseudospecies cut levels were set to three, with levels 0, 4, and 10. These levels The middle oroarctic zone represents an ecosystem ap­ produced a number of pseudospecies not exceeding the proaching the limits of closed vegetation cover that is computation capacity of the TWINMAX - an enlarged relatively low productive with sparse annual biomass programme version of TWINSPAN. On the other hand, production. The plant production supports a trophic sys­ these levels should not emphasize the influence of the tem with several grazers (Oksanen et al. 1996) of which dominant species, and the species occurring with low reindeer and small mammals are the most important. In cover values should affect the classification. Thus the the district studied by us the reindeer population con­ whole species composition, not only the dominant spe­ sisted of ea. 10 000 animals in the late 1980s which is cies, contributes to the classification. TWINSP AN divi­ about 1-4 individuals per km2 (Kojola et al. 1993), but sions with eigenvalue > 0.2 were employed to produce a has decreased to ea. 6000 in the 1990s (1. Kojola, pers. classification. The higher level clusters of TWINSP AN comm.). Reindeer grazing is most intense in mid-sum­ were used for arrangement of the community groups. To mer. The key-stone small mammal of the study sites is briefly convey an idea about the ecological characteristics the Norway lemming (Lemmus lemmus) showing drastic of the groups, a physiognomic-site type name was also variation in densities. It may be virtually absent for given. The subdivisions of these groups resulted in clus­ periods up to 15 years, then copiously abundant during ters that were regarded as community types or variants big outbreaks (Kalela 1961). Mountain hare (Lepus thereof. The community types were expected to have a timidus), rock ptarmigan (Lagopus mutus) and arvicolids characteristic species composition and to be ecologically (Microtus agrestis, M. oeconomus and Clethrionomys interpretable. The variants shared much of the ecology of rufocanus) occur in the oroarctic zone (Henttonen et al. the main type, but the species composition and abundance 1977), but they fluctuate in density (Laine & Henttonen relationships were likely to vary depending on local fac­ 1983). tors. We described the Fennoscandian community types On Spitsbergen, the Svalbard reindeer (Rangife r as bound to the Finnish site-type system (e.g. Haapasaari tarandus platyrhynchus) is the main grazer and totals 1988), while the vegetation units on Spitsbergen were 11000 individuals (Norderhaug & Reimers 1976). The called 'communities'. metapopulation is divided into several relatively discrete Detrended correspondence analysis (DCA) ordination populations (Punsvik et al. 1980). In the inner Isfjorden (Hill & Gauch 1980) was used to reveal the major direc­ region, the estimated density in areas close to the study tions of variation (vegetation gradients) in the community plots has been 5.6 animals per km2 (Alendal & Byrkjedal data. Since TWINSP AN clearly divided the material into 1976). A population has been observed in the Reindalen­ 'Spitsbergen' and 'Fennoscandia' as main groups of their Sveagruva-Agardhdalen area. On the west coast, reindeer own, separate ordinations were performed for northern has occurred sparsely. Another herbivore, the Svalbard Fennoscandia and Spitsbergen. The centroids (mean of ptarmigan (Lagopus mutus hyperboreus) occurs, but esti­ the ordination scores for the first two DCA axes) of the mates of the population are unknown. In the Sveagruva TWINSPAN groups (community types) were calculated area, an introduced muskox (Ovibos moschatus) popula­ and standard deviation of the mean was calculated to tion numbered 16 individuals in 1930 and some tens of indicate the dispersion of the plots. DCA scores were individuals in the 1960s (pers. observ. by S.E.). This computed by the CANOCO 3.1 computer package (ter population has obviously become extinct in the late Braak 1988, 1990) using down-weighing of rare species 1980s (Mehlum 1990). There are no lemmings on and detrending by segments. Sample plots of wet and Spitsbergen, and small populations of Microtus epiroticus rocky habitats were omitted from the ordination, because (including M. arvalis) are only found near human settle­ they behaved as outliers. ments (Mehlum 1990).

Acta Phytogeogr. Suec. 82 3 Results: classification and ordination

In the first division of the TWINSPAN run (Fig. 4), the 3.1 Northwestern Fennoscandia sample plots from northwestern Fennoscandia and Spitsbergen were practically exclusively separated from The total material of northwestern Fennoscandia was each other as only one plot from Fennoscandia was as­ firstly split by TWINSP AN into two large groups con­ signed to the cluster of Spitsbergen data. A more diffuse sisting of vegetations on wind-swept - weakly snow­ discrimination could have been expected due to the largely protected and on sheltered slopes- snowbed sites (Fig. common species pool occupying climatically relatively 4). The former group was further divided into three similar areas, especially on geologically corresponding collective clusters, of which the first, the Festuca ovina­ substrates. Nevertheless, this result indicates that commu­ Potentilla crantzii group, represents eutrophic grass­ nities in similar habitats are differentiated. This is partly rich communities with indicators of calcareous soils. due to differences in species composition between The vegetation within this cluster does not clearly corre­ Fennoscandia and Spitsbergen. The differences in species spond to any higher level vegetation unit described ear­ composition are exemplified by the preferential species lier, but it seems to be intermediate between the tradi­ list given by TWINSP AN (Table 2). A corresponding tional unit Caricetalia curvulae (Braun-Blanquet 1926; result was also obtained in an analysis of data sets from Dahl 1957, or Juncion trifidi Nordhagen 1943) and Bear Island, Jan Mayen, Spitsbergen and the mainland Seslerietalia coeruleae (Braun-Blanquet 1926, or (Virtanen et al. 1997b). Due to this dichotomy, the com­ Kobresieto-DryadionNordhagen 1943). The remaining munities of northwestern Fennoscandia and Spitsbergen material in this branch of the dendrogram was divided are treated in separate sections. into two clusters, of which the first cluster contained

0.502

FovPcrG AG JtCtG ShG RgG SoppG LeG PdG DocG AoiAtG SaS WMS

Fig. 4. Dendrogram representing the major divisions of a TWINSP AN classification of the 303 sample plots. The eigenvalues of the divisions are indicated. The community groups of northern Fennoscandia: FovPcrG - Festuca ovina-Potentilla crantzii group, AG ­ Alectoria group, JtCtG - ]uncus trifidus-Cassiope tetragona group, ShG - Salix herbacea group, RgG - Ranunculus glacialis group, SoppG - Saxifraga oppositifolia group. The community groups of Spitsbergen: LeG - Luzula confusa group, PdG - Papaver dahlianum group, DocG - Dryas octopetala group, AbAtG - Alopecurus borealis-Aulacomnium turgidum group, SaS - Sanionia snowbed communities, WMS - Wet moss snowbeds.

Acta Phytogeogr. Suec. 82 12 R. Virtanen & S. Eurola

vegetation on snow-protected sites, to be called the Alectoria group. This corresponds to the traditional higher level vegetation unit Loiseleurieto-Arctostaphylion (Kalliola 1939, Nordhagen 1943) and to the Arcto­ staphylos and Cassiope tetragona-Vaccinium groups of 3 Oksanen & Virtanen (1995). The second cluster in­ cluded vegetation of snow-protected sites and corre­ sponded to the traditional Juncion trifidi Scandinavicum (Nordhagen 1943) and the ]uncus trifidus-Cassiope tetragona group of Oksanen & Virtanen (1995). The main cluster with chionophilous-snowbed vegetation was divided into three clusters, of which one is called the Saxifraga oppositifolia group. It is a relatively heteroge­ neous group, not similar to any higher level vegetation unit described earlier, but it largely comprises a broad group of snow bed communities rich in calciphiles (Gjrere­ vo11 1956). The snow bed vegetation of siliceous substrates was subsequently divided into two main groups, called 2 3 4 5 Salix herbacea and Ranunculus glacialis groups, recog­ DCA 1 (0.651) nized also by Oksanen & Virtanen (1995). These differ ecologically from each other in duration of snow cover. In total, the northern Fennoscandian material comprises Fig. 5a. six community groups including 30 community types or variants. The ecological relationships of the community types were analysed by means of DCA ordination (Fig. Sa). The first DCA axis seems to be related to snow cover, as axis seems to reflect mainly edaphic differentiation along the snowbed communities (typical species: Anthelia gradient from heaths of siliceous substrate (typical spe­ juratzkana, Kiaeria starkei, and Polytrichastrum sex­ cies: Gymnomitrion corallioides) to communities with angulare; Fig. 5b) were placed in the left and the ridge indicators of calcium carbonate (e.g. Carex rupestris heaths were scored in the upper right of the figure (typi­ and Dryas octopetala) but also to communities on rela­ cal species: Alectoria nigricans, Empetrum nigrum ssp. tively nutrient-rich sites (Anthoxanthum odoratum ssp. hermaphroditum and Flavocetraria nivalis). The second alpinum, Poa alpina and Viola biflora).

Table 2. Preferential (NW Fennoscandia/Spitsbergen) and non-preferential vascular plants given by the first TWINSPAN division.

Species with * are encountered exclusively either in the Fennoscandian or the Spitsbergen material.

NW Fennoscandia Non-preferential Spitsbergen

Carex bigelowii* Bistorta vivipara Alopecurus borealis* Cassiope hypnoides* Dryas octopetala Cerastium arcticum Cassiope tetragona Draba alpina* Festuca ovina* Draba subcapitata* ]uncus trifidus* Luzula arctica* Salix herbacea* Luzula arcuata ssp. confusa Sibbaldia procumbens* Oxyria digyna Silene acaulis Papaver dahlianum* Vaccinium vitis-idaea* Pedicularis hirsuta Poa alpigena* Poa arctica Salix polaris Saxifraga cernua Saxifraga cespitosa Saxifraga nivalis Saxifraga oppositifolia Stellaria longipes*

Acta Phytogeogr. Suec. 82 Middle oroarctic vegetation in Finland and middle-northern arctic vegetation on Svalbard 13

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. Betnan . Gym cor Callap . .Cet niv • • Ale nig •• cetcuc • Thaver Bry div Die fus•

Cas tet. Och fri. Die elo• • Cla coc •Cia gra • • Poljun .eru lie .ste atp Gy"!con . Cas hyp .Die sco •Dry oct · .Pol pit vac vit Cet del• Cetcri . • • Lophozi Cla :.m Pti cil Ple alb .Luz con •Anamin . • .Cep sp And rup Con te t• • sat her •Jun Ki�sta •Car big tri

•Sib pro •Sal pol Cet ist• Bar flo •Sit aca •Hyl ala Tri qui .

. . Pol viv• Fes ovi •Pol alp

•Antodo -2.0 san.unc +6.0

•Poaalp . Viobif

Fig. 5. Ordination diagram of axis 1 against axis 2 using Detrended Correspondence Analysis (DCA) for the TWINSPAN groups (a, overleaf) in the Fennoscandian material. The centroids (point) are mean sample scores for the ftrst two DCA axes. Circled area indicates S.D. of the scores with respect to the axes. APsT - Antheliajuratzkana-Polytrichastrum sexangulare type, CbT - Carex bigelowii type, CbSpT - Carex bigelowii-Salix polaris type, ChJtTe/ChJtTf - Cassiope hypnoides-Juncus trifidus type, DocCrT - Dryasoctopetala­ Carex rupestris type, DocCtT - Dryas octopetala-Cassiope tetragona type, ECtTa/ECtTc - Empetrum-Cassiope tetragona type, ECtATb/ECtATc - Empetrum-Cassiope tetragona-Alectoria type, EFnT - Empetrum-Flavocetraria nivalis type, GymnT - Gymnomitrion type, FovDocC - Festuca ovina-Dryasoctopetala community, FovDocHC - Festuca ovina-Dryasoctopetala-Hylocomium community, FovPcrT - Festuca ovina-Potentilla crantzii type, FovSalpSaC - Festuca ovina-Saussurea alpina-Sanionia community, JtCtTCb - ]uncus trifidus-Cassiope tetragonatype, Carex bigelowii variant, JtCtTCd - ]uncus trifidus-Cassiope tetragona type, Cetrariella delisei variant, JtCtTe/JtCtTf - ]uncus trifidus-Cassiope tetragona type, typical variants, JtCtTg - ]uncus trifidus-Cassiope tetragona type, graminoid variant, JtCtTm - ]uncus trifidus-Cassiope tetragona type, mossy variant, JtCtTPh - ]uncus trifidus-Cassiope tetragona type, Polytrichum hyperboreum variant, KPC - Koenigia islandica-Phippsia algida community, ShChT - Salix herbacea-Cassiope hypnoides type, ShKiT - Salix herbacea-Kiaeria type, ShKiTCb - Salix herbacea-Kiaeria type, Carex bigelowii variant, SpSacT - Salix polaris­ Silene acaulis type, SoppRsT - Saxifraga oppositifolia-Ranunculus sulphureus type, TsSaT - Trisetum sp icatum-Sanionia type. DCA ordination of the most common species (b) Ale nig - Alectoria nigricans, Ana rnin-Anastrophyllum minutum, And rup - Andreaea rupestris, Ant jur - Anthelia juratzkana, Ant odo - Anthoxanthum odoratum ssp. alpinum, Bar flo - Barbilophozia floerkei, Bet nan - Betula nana, Bry div - Bryocaulon divergens, Cal lap - Calamagrostis lapponica, Car big - Carex bigelowii, Car rup - Carex rupestris, Cas hyp - Cassiope hypnoides, Cep sp - Cephalozia spp., Cet cri - Cetraria islandica ssp. crispiformis, Cet cue - Flavocetraria cucullata, Cet del - Cetrariella delisei, Cet isl - Cetraria islandica, Cet niv - Flavocetraria nivalis, Cla arb - Cladina arbuscula, Cla gra - Cladonia gracilis, Con tet - Conostomum tetragonum, Die elo - Dicranum elongatum, Die fus - Dicranum fuscescens, Die sco - Dicranum scoparium, Dry oct - Dryas octopetala, Emp her - Empetrum nigrum ssp. hermaphroditum, Fes ovi - Festuca ovina, Gym con - Gymnomitrion concinnatum, Hyl ala - Hy locomium sp lendens var. alaskanum, Jun tri- ]uncus trifidus, Kia sta - Kiaeria starkei, Lophozi - Lophozia spp., Luz con - Luzula arcuata ssp. confusa,Phy cae - Phyllodoce caerulea, Ple alb - Pleurocladula albescens, Poa alp - Poa alpina, Pol alp - Polytrichastrum alpinum, Pol jun - Polytrichum juniperinum, Pol pil - Polytrichum pi life rum, Pol sex - Polytrichastrum sexangulare, Pol viv - Bistorta vivipara, Pti cil - Ptilidium ciliare, Sal her - Salix herbacea, Sal pol - Salix polaris, San unc - Sanionia uncinata, Sib pro - Sibbaldia procumbens, Sil aca - Si le ne acaulis, Ste alp - Stereocaulon alpinum, Tha ver - Thamnolia vermicularis, Tri qui - Tritomaria quinquedentata, Vac vit - Vaccinium vitis-idaea, Vio bif - Viola biflora.

Acta Phytogeogr. Suec. 82 14 R. Virtanen & S. Eurola

Nordhagen's types, sustained by cattle grazing (the 'Festuca ovina-Potentilla crantzii sosiasjon'), are more comparable to those in our material in which the relatively heavy reindeer trampling has probably reduced the abun­ dance of lichens. In part, this vegetation shows affinities to the Kobresieto-Dryadion (Nordhagen 1943, 1955) due to a relatively rich occurrence of calciphilous species. However, the species composition of the typical Kobresieto-Dryadion communities is somewhat differ­ ent. This may reflect a situation where the Festucetum ovinae alpicolum and the Kobresieto-Dryadion commu­ nities coexist on mountain slopes where soil properties are heterogeneous which also contributes to large vege­ tational heterogeneity (Nordhagen 1943: 579-580). In a broader geographical context, Nordhagen (1943) consid­

FovDocC FovDoHC FovPcrT FovSalpSaC JtCtTm ers the association Festucetum ovinae alpicolum (as part of the Juncetum trifidi) analogous with the Caricetum curvulae Braun-Blanquet in the Alps, but their ecological Fig. 6. TWINSPAN division of the Festuca ovina-Potentilla or phytosociological relationships have not yet been fully crantzii group. FovDocC - Festuca ovina-Dryas octopetala understood (DierBen 1992). community, FovDocHC - Festuca ovina-Dryas octopetala­ In the DCA ordination, this group formed a relatively Hylocomium community, FovPcrT - Festuca ovina-Potentilla well separated cluster (Fig. Sa). The communities seem to crantzii type, FovSalpSaC - Festuca ovina-Saussurea alpina­ Sanionia community, JtCtTm - June us trifidus-Cassiope be differentiated in respect to duration of snow cover and tetragona type, mossy variant. nutrient status. Consequently, the first four community clusters can be arranged in the following order with in­ creasing snow cover: FovDocC, FovDocHC, FovPcrT, and FovSalpSaC. Apart from these, cluster JtCtTm seems to be close to the oligotrophic ]uncus trifidus-Cassiope 3.1.1 Festuca ovina-Potentilla crantzii group tetragona heaths placed in the central part of the ordina­ Chionophobous-chionophilous steppe-like heath vegeta­ tion space. This community might be equally well in­ tion on moderately calcium carbonate-rich substrate; cluded in the ]uncus trifidus-Cassiope tetragona group Appendix 1, Fig. 6 (described below). In our material, vegetation of the Festuca ovina­ This community group consists of vegetation character­ Potentilla crantzii group occurs only on the easternslopes ized by Festuca ovina together with a variable eo-occur­ of Mt. Saana, just below the grand vertical mountain walls rence of indicators of (at least weakly) carbonate-rich at an altitude of about 900 m above sea level. Such substrate (e.g. Dryasocto petala, Potentilla crantzii, Salix landscape qualities obviously generate special ecological reticulata, Saxifraga spp. and Viola biflora) and grasses conditions. The slope is steep and chiefly south-facing, such as Anthoxanthum odoratum ssp. alpinum and Poa thus it receives much solar radiation. Therefore, soils are alpina. Physiognomically, the vegetation looks like grassy relatively dry and warm as compared to the middle oroarctic meadows, or maybe better, cold steppes consisting of a zone in general. Warmth can last overnight due to stored large number of vascular plants (more than 50 altogether). heat in the soil (oven effect), and warm air masses are This vegetation may represent an ecological counterpart uplifted by inversion. Soil substrates are only weakly to cold steppes typical of continental mountain regions. acidic due to calcareous bedrock and steep topography. These communities develop into arctic dwarf shrub heaths, Moreover, reindeer grazing may enhance nutrient turno­ and in this respect such relations as conveyed by Lloyd et ver, as it delays the development of dense dwarf shrub al. (1994) in Alaska might play a certain role also in vegetation and promotes the growth of graminoids subcontinental northernFennoscandia (see also Nordhagen (Kalliola 1939: 172-173; Dah1 1957: 106). 1943:183). Within this community group, five clusters were pro­ This group shows affinities with the traditional asso­ duced by TWINSPAN. The composition of these clusters ciation Festucetum ovinae alpicolum thoroughly described did not suggest that they would represent any distinct type by Nordhagen (1943) from Sikilsdalen, southernNorway. of vegetation, rather they might be best regarded as fixed The cover of lichens, in some communities those of points in a vegetational continuum. Moreover, as the data bryophytes, are many times greater in Nordhagen's (1943) of this vegetation came from one locality (slope of Mt. material than in ours. On the other hand, lichen cover in Saana), we refrained from describing them all as new

Acta Phytogeogr. Suec. 82 Middle oroarctic vegetation in Finland and middle-northern arctic vegetation on Svalbard 15

community types and mainly dis cuss their species com­ Salix polaris and Viola biflora) and species typical of position and ecological characteristics. mesic sites (Bistorta vivipara and Carex vaginata) and species typical of dry ridges (Vaccinium vitis-idaea). This Festuca ovina-Dryas octopetala community (FovDocC) community probably represents a transition between dwarf This community is characterized by the occurrence of shrub heaths and the meadow-like heath patches charac­ in dicators of calcium carbonate mixed with patchily grow­ terized by Festuca ovina. Like the community above, this ing Festuca ovina and Dryas octopetala. Calciphilous community resembles the 'Festuca ovina-Potentilla plants are found both among cryptogams (e.g. Cladonia crantzii -sosiasjon' (Nordhagen 1943: 200-201) and the pocillum and Lescuraea saxicola) and vascular plants Potentilleto-Festucetum ovinae of Dahl (1957: 106-109) . (e.g. Carex rupestris and Draba daurica). Most of the In Nordhagen's (1943) sample data, there is aHylocomium­ species have a low frequency, but as a whole , the species variant with a large cover of Hy locomium sp lendens. In number of the community is high. The species richness of our material, the cover of Hylocomium is not large, but the community may be partly attributable to the presence some ecological similarity may exist between these two of many small mosses (e.g. Bryumargenteum and To rtula communities. This somewhat mixed vegetation supports norvegica) which occupy mineral soil gaps created by the assertion above that the F estuca ovina heaths show small-scale disturbances. Probably, the open gaps also transitions to dwarf shrub heaths without any distinct favour coexistence of many saxifrages. borders. Natural grazing may be one of the structuring This community resembles the 'Carex rupestris­ mechanisms within these gradients (Oksanen 1990). Encalypta rhaptocarpa-sosiasjon' typical of calcareous rock ledges in Sikilsdalen, Norway (Nordhagen 1943). F estuca ovina-Saussurea alpina-Sanioniauncinata com­ The Dryas octopetala-Carex rupestris type, described munity (FovSalpSaC) below, is ecologically related to this community but rep­ This community represents the most chionophilous veg­ resents vegetation on more extremely wind-swept sites. etation in this community group. The characteristic spe­ The material in this community stems partly from similar cies are Sanionia uncinata and Saussurea alpina. Dwarf exposed rock ledges at the basis of the vertical rock walls shrubs are missing or are very scarce. Otherwise, the field of Mt. Saana. layer is relatively heterogeneous in its composition : some plots have a large cover of Viola biflora while some other Festuca ovina-Potentilla crantzii type (FovPcrT) plots contain Cerastium alpinum, due to variation in snow­ This community has a fairly dense cover of Festuca ovina duration. V. biflora-characterized communities emerge giving a meadow-like appearance. The indicators of cal­ later from snow than the ones characterized by C. alpinum. cium carbonate are fewer than in the community FovDocC Like the FovPcrT and FovDocHC described above, described above, but e.g. Cerastium alpinum, Dryas this community resembles the 'Festuca ovina-Potentilla octopetala, and Silene acaulis are frequently present. This crantzii sosiasjon' of Nordhagen (1943). Especially, the community is prevalent on sheltered slopes. It resembles sample plots representing the Polytrichum juniperinum­ the 'Festuca ovina-Potentilla crantzii -sosiasjon' (Nord­ Cetraria islandica variant (Nordhagen 1943: 200-201) hagen 1943) which is regarded by Nordhagen (1943) as a seem to have a relatively similar species composition. secondarily arisen Festuca ovina heath, i.e. a dwarf shrub Also some of the samples of 'arktische Festuca ovina­ heath changed to a Festuca ovina dominated community Wiesen' in Kalela (1939) from Kalastajansaarento at the by the grazing of horses. This corresponds to the Potentillo­ NE coast of Fennoscandia are floristically relatively simi­ Festucetum ovinae (Dahl 1957) which is sustained by lar, suggesting an affinity to vegetation found normally in grazing, while without any grazing, a shrub heath or a the lower oroarctic zone. In our material, the closest shrub heath with herbs would prevail. community type is the Trisetum spicatum-Sanionia type For practical purposes (e.g. for needs of vegetation (see below) that occupies sites with more late-lying snow. mapping) this vegetation is provisionally described as a new type to be called the Festuca ovina-Potentilla crantzii ]uncus trifidus-Cassiope tetragona type, mossy variant type (FovPcrT) with the ecological characteristics of this (JtCtTm) community group. This community is characterized by patchily occurring Cassiope tetragona and F estuca ovina. The bottom layer Festuca ovina-Dryasoctopeta la-Hylocomium alaskanum is rich in mosses (Dicranum scoparium and Hy locomium community (FovDocHC) splendens var. alaskanum). In the ordination, this com­ This community has a bottom layer with a relatively high munity cluster is placed relatively close to a community total moss cover including Dicranum spp. and Hylocomium belonging to the ]uncus trifidus-Cassiope tetragona group sp lendens var. alaskanum. The field layer consists of a [the ]uncus trifidus-Cassiope tetragona type, graminoid mixture of plants typical of various habitats. There are variant JtCtTg (Fig. Sa)]. This variant has Polytrichum species of snow-protected sites (Phyllodoce caerulea, species as most the prominent in the bottom layer, few

Acta Phytogeogr. Suec. 82 16 R. Virtanen & S. Eurola

Dicranum spp. and/or Hylocomium. These two variants can nities differ, however, from the Loiseleurieto-Arctosta­ hardly be regarded as similar. The 'm' variant community phylion by the total absence of Arctostaphylos alpina and differs from the community types in the ]uncus tri.fidus­ Loiseleuria procumbens. This is probably due to the fact Cassiope tetragonagroup (see below) by the occurrence of that our plots lie above the altitudinal limit for common e.g. Saxifraga nivalis or more rarely S. cespitosa and S. occurrence of these species (wide-spread in the lower oppositifolia, indicating calcareous soil substratum. These oroarctic zone). The four types of this group can be communities most likely represent an intermediate vegeta­ described as follows: tion between the Festuca ovina-Potentilla crantziiand the ]uncus trifidus-Cassiope tetragona heaths. Dryas octopetala-Carex rupestris type (DocCrT) A distinct community identified by TWINSP AN consists of six plots with calciphilous plants and a bottom layer with indicators of chionophobous conditions. Dryas 3.1.2 Alectoria group octopetala dominates and another xeric calcicole species, Chionophobous vegetation rich in dwarf-shrubs. Appen­ Carex rupestris, is common. The vegetation of this type is dix 2, Fig. 7 patchy due to frostheav ing, wind abrasion and accumula­ tion of weathered material. Also rare species, such as This community group includes vegetation with an abun­ Arnica angustifolia ssp. alpina, Carex glacialis and among dant occurrence of chionophobous species: Alectoria mosses e.g. Campylophyllum halleri, Hypnum bambergeri nigricans and A. ochroleuca occur constantly, along with and Schistidium tenerum were observed. These habitats at other lichens typical of wind-swept sites (e.g. Bryocaulon Kilpisjarvi are typically found on the steep slopes of Mt. divergens, Cetraria nigricans, Flavocetraria nivalis, Saana and on wind-exposed sites on the dolomite peak of Sp haerophorus globosus, and Thamnolia vermicularis) Mt. Guonjarvam. This type appears to be restricted to a (Fig. 5b). Otherwise, the species composition differs quite few topographically rugged localities which are less ac­ drastically among the community clusters. One of the cessible for reindeer. On these sites, Dryas octopetala communities is characterized by calciphilous species, while often forms a nearly closed cover. in the other communities, species typical of siliceous This community corresponds to some sample plots in substrates are prevalent. The former community resem­ Nordhagen's (1936) 'artenarme Dryas-Carex rupestris­ bles the associations included in the Kobresieto-Dryadion Soziation', and his (1955) Dryadetumoctopetalae rich in (Nordhagen 1943) and the latter shows affinities to the Carex rupestris, Bringer's (1961) Ep ibryo-Dryadetum Loiseleurieto-Arctostaphylion (Kalliola 1939) and to the (Dryas-Carex rupestris-fazies). It can also be regarded as Loiseleurio-Vaccinietea (Daniels 1994 ). These commu- the middle oroarctic counterpart of Kalliola's (1939) 'Dryas-Alectoria-Flavocetraria nivalis-Soziation', and Kalela's (1939) 'Carex rupestris-Wiese'. On Spitsbergen, the corresponding noda are the Rupestri-Dryadetum (R�nning 1965) and the Carici rupestris-Dryadetum (Hartmann 1980), with as characteristic species Draba subcapitata and Schistidium apocarpum. Our data from Spitsbergen do not contain sample plots which clearly represent this type of vegetation .

Empetrum-Cassiope tetragona-Alectoria type (ECtA Tb, ECtATc) These two community clusters, ECtATb and ECtA Tc, show affinities to the Cassiope tetragona-Cetraria nivalis type (CtCnT), the Vaccinium-Alectoria type (V AT) and the Empetrum-Phyllodoce-Alectoria (EPAT) of Oksanen & Virtanen (1995). One of them (ECtATb) can be regarded as an intermediate type between the Cassiope tetragona-Flavocetraria nivalis type and the DocCrT ECtATb ECtATc GymnT Vaccinium-Alectoria type, while the other (ECtATc) resembles the Empetrum-Phyllodoce-Alectoria type, Fig. 7. TWINSP AN divisions of the Alectoria group. DocCrT - except for the scanty occurrence of Phyllodoce caerulea. Dryas octopetala-Carex rupestris type, ECtA Tb/ECtAc - The three community types, CtCnT, EPAT and VAT, Empetrum-Cassiope tetragona-Alectoria type, GymnT - form a relatively diffuse pattern of variation where Gymnomitrion type. local conditions and stochastic processes influence the

Acta Phytogeogr. Suec. 82 Middle oroarctic vegetation in Finland and middle-northern arctic vegetation on Svalbard 17

abundance relationships between ericaceous plants. scribed from Greenland ( Cassiopetetum tetragonae; Vaccinium vitis-idaea seems to thrive best in contact Bocher 1933; Daniels 1982). with pure rock, probably because its strong vegetative reproduction makes it sensitive to cryoperturbation. Gymnomitrion type (GymnT) Empetrum nigrum ssp. hermaphroditum reproduces also This community is character ized by chionophobous spe­ vegetatively (Soyrinki 1939) which makes it sensitive cies that are common in the community group. However, to uprooting in sites with intense cryoperturbation. now Gymnomitrion corallioides occupies relatively large Phyllodoce caerulea has only weak adventitious roots, areas in the wind-exposed centres of elevated polygons, and it is thus resistant to cryoperturbation (Soyrinki while the hollows are rich in Dicranum and Polytrichum 1939 ; Dahl 1957). The same appears to apply to C. moss species. The hollows are also occupied by vascular tetragona (Warming 1908) which, moreover, is better plants demanding protection from strong abrasive winds adapted to the middle arctic and middle oroarctic con­ (e.g. Betula nana, Cassiope tetragona, Empetrum nigrum ditions, and thus tends to replace P. caerulea, if present ssp . hermaphroditum and Vaccinium vitis-idaea). Th is in the species pool. It seems thus reasonable to regard community prevails on mountain top plateaux where soil the Cassiope tetragona-Cetraria nivalis type and the conditions are suitable for the development of polygons. Empetrum-Phyllodoce-Alectoria type as local variants In these habitats, slow-rate cryoperturbation, relatively of a single type; the latter variant being mainly encoun­ oceanic climate (Haapasaari 1988) and/or reindeer tram­ tered outside the range of C. tetragona. The Vaccinium­ pling (Nordhagen 1943) seem to maintain frost boils Alectoria type, in turn, occurs locally and changes colonizable for hepatics . These frost boils seem to favour gradually into the other types so that it is impractical to especially G. corallioides. When the polygons are more distinguish it as a type of its own. We thus propose that intensely frost-heaved, the plant cover becomes extremely these three vegetation noda, along with the clusters sparse. On the other hand, when they are stable, then ECtATb and ECtATc in our material, will be regarded wind-hardy lichens, such as Alectoria nigricans, as variants of a more inclusive community type, to be A. ochroleuca, and Flavocetraria nivalis, occur with a referred to as the Empetrum-Cassiope tetragona­ high cover (if not decimated by reindeer). This type seems Alectoria type (ECtAT). Closest counterparts are de - to represent a parallel type for the ECtA T that prevails on

0.235

ECtTa EFnT ECtTc JtCtTCb JtCtTe JtCtTf JtCtTg JtCtTPh

Fig. 8. TWINSPAN divisions of the ]uncus trifidus-Cassiope tetragona group. ECtTa/ECtTc - Empetrum-Cassiope tetragona type, EFnT - Empetrum-Flavocetraria nivalis type, JtCtTCb - ]uncus trifidus-Cassiopetetragona type, Carex bigelowii variant, JtCtTe/JtCtTf - ]uncus trifidus-Cassiope tetragona type, typical variant, JtCtTg - ]uncus trifidus-Cassiope tetragona type, graminoid variant, JtCtTPh - ]uncus trifidus-Cassiope tetragona type, Polytrichum hyperboreum variant.

Acta Phytogeogr. Suec. 82 18 R. Virtanen & S. Eurola

more stable ridge sites. The frequent and relatively in ­ snow cover at winter time . In the ordination ECtTa is tense cryoactivity counteracts leaching and enables the placed among the luncus trifidus-Cassiope tetragona type occurrence of calciphilous plants, e.g. Dryas octopetala, suggesting that the dwarf shrub heaths and the vegetation in the centres of polygons (see also Jonasson & SkOld of the gramino id-rich vegetation of Juncion trifi di 1983) . scandinavicum are intermingled. The community clusters ECtTa and ECtTc do not clearly correspond to any of the types of Oksanen & Virtanen (199S). The Cassiope tetragona-Dicranum 3.1.3 ]uncus trifidus-Cassiope tetragona group fuscescens association of Nordhagen (19SS) is similar, Chionophilous vegetation rich in graminoids and/ordwarf­ except in our material Diapensia lapponica is missing, shrubs; Appendix 3, Fig. 8 Dicranum fuscescens and Flavocetraria nivalis occur in lower and Salix herbacea in higher abundance than in The core of the material in this community group con­ Nordhagen ' s material. The closest community types are sists of TWINSP AN clusters with vegetation correspond­ the continental ]uncus trifidus-Cassiope tetragona type ing to the traditional alliance Juncion trifidi scandi­ and the oceanic Salix herbacea-Empetrum type, that have navicum (Nordhagen 1943) and the ]uncus trifidus­ less Cassiope tetragona. The occurrence of such mosses Cassiope tetragona group in Oksanen & Virtanen (199S). as Racomitrium lanuginosum creates affinities to the oce­ In the ordination space, most of the types assigned to this anic Empetrum heaths which in the middle oroarctic zone group take an intermediate position between the of oceanic sectors develop into a vegetation of the Salix chionophobous heath types (the Alectoria group) and herbacea-Empetrum type (Oksanen & Virtanen 199S). Festuca ovina-Potentilla crantzii heaths (the Festuca On these grounds we suggest that these community clus­ ovina-Potentilla crantzii group), while clusters EFnT ters collectively represent a new transitional subcontinen­ and ECtTc overlap with the chionophobous heaths (Fig. tal-suboceanic type, to be called the Empetrum-Cassiope Sa) . These two latter community clusters are rich in tetragona type (ECtT). Relatively similar counterparts dwarf shrubs, and they also have a species composition are reported from West Greenland (Bocher 19S4, 1963; characterized by chionophobous species and thus resem­ Daniels 1982 : heaths rich in Cassiope tetragona). ble the vegetation types in the Cassiope tetragona­ Vaccinium group of Oksanen & Virtanen (199S). How­ Empetrum-Flavocetraria nivalis type (EFnT) ever, the group mainly represents slightly-moderately Th is community cluster represents chionophobous heath chionophilous middle oroarctic heath vegetation in ac­ vegetation, as indicated by the occurrence of Alectoria cordance with the ]uncus trifidus-Cassiope tetragona spec ies together with Flavocetraria nivalis. Betula nana group in Oksanen & Virtanen (199S) . is creeping over ground and occurs with a relatively high cover. Th is community corresponds rather well to the Empetrum-Cassiope tetragona type (ECtTa, ECtTc) Empetrum-Cetraria nivalis type of Oksanen & Virtanen The pair of clusters (ECtTa and ECtTc) are characterized (199S). However, the occurrence of Racomitrium by Cassiope tetragona occurring with a relatively high lanuginosum suggests that the communities at Kilpisjarvi cover. The other of them (ECtTc) has Empetrum nigrum show intermediate features between the oceanic Salix ssp . hermaphroditum as eo-dominant, while among li­ herbacea-Ochrolechia type and the subcontinental chens chionophobous Sphaerophorus globosus and Empetrum-Cetraria nivalis type (Oksanen & Virtanen Thamnolia vermicularis are typical . Among mosses 199S). Aulacomnium turgidum, Hylocomium splendens var. alaskanum, and Racomitrium lanuginosum are relatively ]uncus trifidus-Cassiope tetragona type (JtCtT); constant and give some oceanic character . This commu­ mossy, Carex bigelowii, typical (in two clusters), nity is chiefly encountered on westerly slopes of the graminoid, Polytrichum hyperboreum, and Cetrariella mountains at Kilpisjarvi exposed to maritime north Atlan­ delisei variants tic winds (Fig. 9). The cryptogam layer of the other cluster The community clusters JtCtTm, JtCtTCb, JtCte, JtCtTf, (ECtTa) is rich in lichens, but also Hy locomium sp lendens JtCtTg, JtCtTPh and JtCtTCd lie in the centre of the var . alaskanum is relatively abundant. Festuca ovina oc­ ordination space (Fig. Sa), together, they seem to corre­ curs scattered and ]uncus trifidus is totally absent. The spond to the ]uncus trifidus-Cassiope tetragona type of clusters ECtTa and ECtTc are not very close to each other Oksanen & Virtanen (199S). These communities share in the or dination (Fig. Sa), which suggests an ecological largely the same diagnostic features: i.e. the field layer differentiation: ECtTc takes a quite extreme position near dominated by ]uncus trifidus, alone or together with the types of the Alectoria group. However, the commu­ Cassiope tetragona, Festuca ovina, and/or Salix herbacea. nity is not confmed to the most wind-exposed sites, but The bottom layer is rich in Cetraria ericetorum, C. rather occupies concave slopes retain ing a continuous islandica, and/or Flavocetraria nivalis. The clusters over-

Acta Phytogeogr. Suec. 82 Middle oroarctic vegetation in Finland and middle-northern arctic vegetation on Svalbard 19

Fig. 9. Middle oroarctic Empetrum-Cassiope tetragona heath vegetation. Mt. Jehkats W-slope 900 m. In the centre Racomitrium lanuginosum fairly abundant. June 1988. (Photo: Risto Virtanen.)

lap with each other showing some ecological variation the dwarf shrub heaths and the grarninoid-rich communi­ with respect to the fust two ordination axes. Cluster ties of the ]uncus trifidus-Cassiope tetragona type JtCtTg is more distant from the other clusters and are (Oksanen & Virtanen 1995). The intermediate commu­ placed relatively close to eutrophic Festuca ovina­ nity may represent a successional stage developed under Potentilla crantzii heaths (the Festuca ovina-Potentilla influence of reindeer trampling, as suggested by a rela­ crantzii group). We are apt to retain a collective classifi­ tively high cover of Carex bigelowii as well as by rich eo­ cation and use the separate community clusters mainly for occurrence of small hepatics mixed within a thinned the ecological characterization. lichen cover. This community is referred to as the Carex bigelowii variant of the ]uncus trifidus-Cassiope tetragona ]uncus trifidus-Cassiope tetragona type, Carex bigelowii type. variant (JtCtTCb) This community is characterized by patchily occurring ]uncus trifidus-Cassiope tetragona type, typical vari­ Cassiope tetragona and ]uncus trifidus,occasionally also ant (JtCtTe, JtCtTf) Empetrum, while Carex bigelowii is found more con­ These two community clusters produced by TWINSPAN stantly with a cover of 2-3%. In the bottom layer charac­ are relatively similar in their species compositions . Both teristic lichens include Cetraria ericetorum, Cladina arbus­ clusters have Salix herbacea with relatively high cover cula (mainly C. arbuscula ssp. mitis), and Stereocaulon values, with at least some Cassiope tetragona (Fig. 1 0) . spp. A typical hepatic species is Anastrophyllum minutum. One of the clusters, JtCtTe, is rich in ]uncus trifidusand In the ordination, this community cluster is relatively the other, JtCtTf, rich in Festuca ovina. These communi­ close to the Empetrum-Flavocetraria nivalis type (EFnT) ties resemble the ]uncus trifidus-Cassiope tetragona type and could represent an intermediate community between in Oksanen & Virtanen (1995). However, none of the

Acta Phytogeogr. Suec. 82 20 R. Virtanen & S. Eurola

Fig. 10. ]uncus trifidus-Cassiope tetragona type heath vegetation. Mt. Guonjarvam. Alt. 960 m. July 1989. (Photo: Risto Virtanen.)

variants described there is conspicuously similar in spe­ tain influence of calc ium carbonate. In the ordination cies abundance re lationships. These two communities (Fig. 15a), this community is about intermediate between show more clearly affinities to the northern and oceanic the clusters of the Festuca ovina-Potentilla crantzii group counterpart of Juncion trifidi, i.e. the Salix herbacea­ and the other clusters of this group. Th is community is Empetrum type (Oksanen & Virtanen 1995). On the other also placed close to cluster JtCtTm in the ordination but hand, the luncus trifidus-richcommun ity (JtCtTe) is much has a lower cover of Cassiope tetragona. This community like the ']uncus trifidus-grashei ' described by Nordhagen cluster could be regarded as a grarninoid variant of the (1943: 219-220) from Rastigaissa at interior Finnmark. JtCtT between the typical variants of the type and the Th is suggests that these two clusters may represent the Festuca ovina-Potentilla crantzii group. typical, but locally variable, elements of ch ionophilous vegetation on subcontinental mountains of northwestern ]uncus tri.fidus-Cassiope tetragona type, Polytrichum Fennoscandia. hyperboreum variant (JtCtT Ph) This community is re latively open and characterized by ]uncus tri.fidus-Cassiope tetragona type, graminoid Cassiope tetragona and ]uncus trifidus growing in spaced variant (JtCtTg) patches. The cryptogam layer is rich in Cetrariella delisei, Th is community has a relatively sparse field layer with Cetraria ericetorum, and C. islandica ssp. crispiformis, about equally abundant Festuca ovina and luncus trifidus. Polytrichum hyperboreum, often encrusted with Ochro­ Evergreen dwarf shrubs are only sporadically present. In lechiafrigida (mean cover 25 %). In its species composi­ the cryptogam layer, Polytrichaceae mosses (Polytri­ tion this community resembles fairly well the Trientalis chastrum alpinum and Polytrichum piliferum) are rela­ variant of the ]uncus trifidus-Cassiope tetragona type in tively abundant. In Oksanen & Virtanen (1995), the clos­ Oksanen & Virtanen (1995). However, in our material est counterpart is the Festuca ovina variant of the ]uncus Trientalis europaea is absent, and chionophobous lichens trifidus-Cassiope tetragona type. However, scattered such as Alectoria nigricans and A. ochroleuca occur with Erigeron uniflorus and Minuartia biflora indicate a cer- lower covers than in the Trientalis variant. The sample

Acta Phytogeogr. Suec. 82 Middle oroarctic vegetation in Finland and middle-northern arctic vegetation on Svalbard 21

ShKIT ShChT ShKITCb CbT ChJtT ChJtT CbSpT JtCtTCd TsSaT

Fig. 11. TWINSPAN divisions of the Salix herbacea group. CbT - Carex bigelowii type, CbSpT - Carex bigelowii-Salix polaris type, ChJtTe/ChJtTf - Cassiope hypnoides-Juncus trifidus type, JtCtTCd - ]uncus trifidus-Cassiope tetragona type, Cetrariella delisei variant, ShChT - Salix herbacea-Cassiope hypnoides type, ShKiT - Salix herbacea-Kiaeria type, ShKiTCb - Salix herbacea-Kiaeria type, Carex bigelowii variant, TsSaT - Trisetum spicatum-Sanionia type.

plots assigned to this cluster were encountered on sloping 3.1.4 Salix herbacea group sites with gravelly soil where reindeer trampling is in­ tense. The relatively high cover of Polytrichum Moderate-late snowbed vegetation; Appendix 4, Fig. 11 hyperboreum is regarded as an indication of reindeer trampling (Oksanen & Virtanen 1995). Thus, this variant This group comprises a series of snowbed communities community obviously represents a trampled stage of the apparently from a wide array of ecological conditions }uncus trifidus-Cassiope tetragona type on relatively high related to the length of a snow-free period. Three of the altitudes and on nutrient-poor hill slopes. community clusters, ShK.iT, ShChT, and ShK.iTCb, are characterized by Salix herbacea and Cassiope hypnoides, ]uncus trifidus-Cassiope tetragona type, Cetrariella corresponding to the traditional Cassiopeto-Salicion delisei variant (JtCtT Cd) herbaceae (Nordhagen 1943) and the Salix herbacea­ This cluster characterized by Cassiope tetragona with Kiaeria group in Oksanen & Virtanen (1995). These Cetrariella delisei was assigned to the group of moderate communities seem to be differentiated regarding the length snowbed communities. However, in its species composi­ of the snow-free period and moisture conditions. One of tion this community resembles more closely the vegeta­ the remaining clusters, CbT, includes snowbeds domi­ tion of the }uncus trifidus-Cassiope tetragona group than nated by Carex bigelowii, and thus corresponds to the snowbeds. The high cover of Cetrariella delisei may be vegetation found in the traditional group Nardeto-Caricion related to its tolerance to freezing in solid ice (Dahl 1957; rigidae (Nordhagen 1943). Some of the communities, Oksanen & Virtanen 1995). Such ice formation is likely to ChJtTe and ChJtTf, seem to change gradually towards the occur in relatively level habitats, in which this community upper oroarctic vegetation resembling the Luzuleto­ was encountered on Mt. Guonjarvarri. The formation of Cesietum (Dahl 1957: 169-176) or the Luzula confusa ice lenses may explain the sparse field layer. Cassiope group in Oksanen & Virtanen (1995) . The positive branch tetragona itself can elevate shoots several centimetres of the TWINSP AN tree includes two clusters where the above the ground, and thus partially avoid freezing dam­ communities have many indicators of nutrient-rich site age. The freezing in solid ice is probably an important conditions. The first of them, cluster TsSaT, might be best ecological factor, but as yet little known (cf. Oksanen & characterized as eutrophic snowbed vegetation . This veg­ Virtanen 1995). Due to the occurrence of Cetrariella etation shows affinity with the Ranunculeto-Oxyrion delisei this type is described as the Cetrariella delisei (Nordhagen 1943) or with the Ranunculus glacialis group variant of the }uncus trifidus-Cassiope tetragona type. in Oksanen & Virtanen (1995). The second cluster, CbSpT,

Acta Phytogeogr. Suec. 82 22 R. Virtanen & S. Eurola

resembles to a large degree the herb-rich vegetation of 'mosrik Salix herbacea-sosiasjon ' Nordhagen 1943: 266), Carex bigelowii-Salix polaris type (Oksanen & Virtanen but no samples with a conspicuously similar community 1995). The vegetation types of this group can be described composition were found. Indeed, this may represent an as follows : intermediate community between the Salix herbacea and Carex bigelowii snowbeds. Thus, we consider the type as Salix herbacea-Kiaeria type (ShKiT) a Carex bigelowii variant of the Salix herbacea-Kiaeria This community is characterized by Salix herbacea and type, where the abundance of Carex bigelowii indicates Kiaeria starkei occurring with high cover. Gnaphalium moister site conditions than in the sites of the main type. supinum and Sibbaldia procumbens are regular constitu­ ents with low cover. The cryptogam layer is rich in Carex bigelowii type (CbT) hepatics (Barbilophozia subgenus Orthocaulis, Lophozia This community is characterized by a rather uniform spp.) and snowbed mosses (e.g. Conostomum tetragonum). cover of Carex bigelowii (mean cover about 13 %); Salix This cluster occurs at the relatively extreme end of the herbacea has a relatively low cover giving a more meadow­ snow gradient (Fig. Sa). This community cluster corre­ like appearance. Other characteristic species in the field sponds to the 'Salix herbacea-Kiaeria starkei-Polytrichum layer are Bistorta vivipara and Cassiope hypnoides. In the sexangulare-sosiasjon ' of Nordhagen (1943) and the Salix cryptogam layer Anthelia juratzkana and Conostomum herbacea-Kiaeria starkei-sociation of Gjrerevoll ( 1956). tetragonum are frequent indicating true snowbed condi­ This community is similar to the Salix herbacea-Kiaeria tions. This type is often encountered in sites periodically type described in Oksanen & Virtanen (1995). irrigated by melt water of snow fields. This vegetation corresponds to the 'Carex rigida -Ass.' (Nordhagen 1928), Salix herbacea-Cassiope hypnoides type (ShChT) the 'Carex rigida-Wiese' (Kalliola 1939) and the 'Carex This type differs from the Salix herbacea-Kiaeria type rigida-Lachenalii-sosiasjon' of Nordhagen (1943: 250- above by having a relatively high coverage of Cassiope 260). In Gjrerevoll 's (1956) material, the closest counter­ hypnoides (almost lacking in the Salix herbacea-Kiaeria parts are found among Carex bigelowii -sociations, but type). The bottom layer is richer in lichens (Cetraria none of his samples resembles ours. This type was not ericetorum, C. islandica ssp. crispiformis, and Cladonia encountered in the data of Oksanen & Virtanen (1995). A coccifera), while Kiaeria starkei is almost absent, and reason may be that the Carex bigelowii snowbeds prevail Polytrichum spp. are more common than in the Salix on relatively level ground in mountain valley bottoms and herbacea-Kiaeria type. The Salix herbacea-Cassiope usually they are not fo und in sloping ridge-depression hypnoides type prevails on sites with a longer snow-free topographic transects. period than on the sites of the Salix herbacea-Kiaeria type. The Salix herbacea-Cassiope hypnoides type corresponds Cassiope hypnoides-Juncus trifidus type (ChJtTe, well to some samples of 'moselyngsnOleier ' ( Cassiopetetum ChJtTf) hypnoidis) in Nordhagen (1943: 262) and the Salixherbacea­ There is a pair of clusters, ChJtTe and ChJtTf, character­ Cassiope hypnoides type in Oksanen & Virtanen (1995). It ized by a relatively high abundance of Cassiope hypnoides, also resembles the Cassiope hypnoides-Antheliajuratzkana­ Luzula arcuata ssp. confusa and/or ]uncus trifidus in the Gymnomitrion varians-sociation in Gjrerevoll (1956), but field layer, while the cryptogam layer is covered chiefly the cover values of the small hepatics are remarkably lower by Gymnomitrion spp. Among the lichens Cetrariella than in Gjrerevoll 's material. delisei is relatively abundant. In our material, the samples are from relatively level plateaux with polygon fields, chiefly on Mt. Gahpperus. The polygons are more or less Salix herbacea-Kiaeria type, Carex bigelowii variant active which may increase the vegetational heterogeneity. (ShKiTCb) Overall, these communities resemble much the Cassiope hypnoides-Juncus trifidus type in Oksanen & Virtanen This community cluster is dominated by Salix herbacea, (1995). The other community, ChJtTe, resembles in its and also Carex bigelowii is relatively abundant, too. This species composition the 'Ranunculus glacialis-Luzula differs fromthe Salix herbacea-Cassiope hypnoides type confusa-Anthelia-Cesia-sosiasjon' of Nordhagen (1943: in having a low coverage of Cassiope hypnoides. The 27 1 -278). The abundance of R. glacialis is lower in our cryptogam layer is characterized by a thin hepatic layer material than in Nordhagen 's. The other community, (total cover 15-20 % ). The typical species include Anastro­ ChJtTf, resembles the Luzuleto-Cesietum (Dahl 1957), phyllum minutum, Gymnomitrion apiculatum, G. concin­ but it has a conspicusously higher cover of Cassiope natum and Lophozia spp. A typical lichen is Cetrariella hypnoides (almost lacking in Dahl 's material) and lesser delisei, but its cover is low (about 2 % ). It seems that the Polytrichastrum sexangulare than is found in Dahl' s de­ community is related to Salix herbacea snowbeds (asso­ scriptions. The variations in the abundance relationships ciation Salicetum herbaceae Gjrerevoll 1956: 106, the of species may reflect a patchy plant cover typical at

Acta Phytogeogr. Suec. 82 Middle oroarctic vegetation in Finland and middle-northern arctic vegetation on Svalbard 23

altitudes of about 1000- 1100 metres where the middle nivalis, and Sibbaldia procumbens) and graminoids (Carex oroarctic zone is connected to the upper oroarctic zone. lachenalii and Trisetum spicatum). The abundance of C. lachenalii is high compared to that of C. bigelowii. In the Carex bigelowii-Salix polaris type (CbSpT) bottom layer Sanionia uncinata is abundant. In the ordi­ This community is characterized by Carex bigelowii, nation (Fig. Sa) it has a position close to the Festuca Festuca ovina, and Salix herbacea which are frequently ovina-Potentilla crantzii heaths. As compared to Gj rere­ mixed with indicators of calcareous substrate (e.g. Silene voll's (19S6) classification, this community falls between acaulis and Salix polaris). The field layer includes a the alliances Deschampsio-Anthoxanthion and Ranunculo­ conspicuously large number of arctic-alpine herbs (e.g. Anthoxanthion, and no similar sociation can be found in Antennaria canescens, A. porsildii, Cerastium arcticum, his material. Rather, this community can be regarded as Erigeron uniflorus, and Ranunculus nivalis). The similarto the Trisetum spicatum-Sanionia type in Oksanen cryptogam layer is rich in lichens, but only Cladina & Virtanen (199S). arbuscula ssp. mitis, has a re latively high cover. Cetra­ riella delisei and Cladonia uncialis are characteristic species. The cover of lichens is obviously decimated by 3.1.5 Ranunculus glacialis group reindeer grazing. In the ordination (Fig. Sa), the commu­ nity is close to the heath-like Salix herbacea snowbeds Oligotrophic late snowbeds; Appendix 5, Fig. 12a (ShChT, ShKiTCb). This community has some affinity with the Cassiope tetragona-Dryas heaths described as This group embraces a pair of community types repre­ the Cassiopetum tetragonae dryadetosumby Nordhagen senting separate higher level vegetation units. One of the (19SS). This community also resembles some of the communities, cluster APsT, is a cryptogam-dominated sample plots of the Polygoneto-Salicetum herbaceae snowbed which could be included in the traditional alli­ (Dahl 19S7: 178- 1 88). Dahl (19S7) describes this veg­ ance Polytrichion norvegici (Gjrerevoll 19S6) or Ranun­ etation type as eutrophic, seasonally wet and late culus glacialis group of Oksanen & Virtanen (199S). The snowbed, frequently with signs of solifluction. This other community, cluster KPC, resembles the meadow­ characterization is fairly similar to the description of a like snowbed communities in the alliance Ranunculeto­ species-rich type described by Oksanen & Virtanen OxyrionofNo rdhagen ( 1 943) or the Oppositifolio-Oxyrion (199S) near the limit of continuous plant cover: The of Gj rerevoll (19S6). Carex bigelowii-Salix polaris type was characterized as 'alpine garden' owing to soil conditions enriched by Anthelia juratzkana-Polytrichastrum sexangulare type nutrient supply from (periodic) surface water flush or (APsT) groundwater. Aesthetically attractive communities can This community is dominated by cryptogams, of which be found at such places. The community cluster can be Anthelia juratzkana and Polytrichastrum sexangulare are regarded as a well-drained and relatively lichen-rich the most prominent species. Vascular plants include (continental) variant of the Carex bigelowii-Salix pola­ Gnaphalium supinum and Ranunculus nivalis (more rarely ris type. R. glacialis), and e.g. Salix herbacea is absent. This community is encountered near the latest snow fields Trisetum spicatum-Sanionia type (TsSaT) emerging from snow in late July or August and changes This community cluster represents meadow-like snow bed into the less extreme snowbed communities where also vegetation with herbs (Ranunculus acris ssp. pumila, R. vascular plants, e.g. Oxyria digyna and Ranunculus

b)

Fig. 12. TWINSPAN divisions of the

Ranunculus glacialis group (a) APsT - 0.316 Anthelia juratzkana-Polytrichastrum sexangulare type, KPC - Koenigia islan­ dica-Phippsia algida community, and Saxifraga oppositifo lia group (b) DocCtT APsT KPC - Dryas octopetala-Cassiope tetragona type, SpSacT - Salix polaris-Silene acaulis type, SoppRsT - Saxifraga oppo­ sitifolia-Ranunculus sulphureus type. SpSacT SoppRsT DocCtT

Acta Phytogeogr. Suec. 82 24 R. Virtanen & S. Eurola

glacialis, become more abundant. The community cluster scribed by R�nning (1965) from Spitsbergen is the resembles the association Ranunculetum glacialis in Tetragono-Dryadetum.R�nning considers this type simi­ Gj rerevoll (1956:136) or the Ranunculus glacialis­ lar to Nordhagen's Cassiopetetum tetragonae drya­ Gymnomitrion type ofOksanen & Virtanen (1995). How­ detosum. In the numerical TWINSPAN classification, ever, this cluster represents the most extreme snowbeds the vegetation of this group of northern Fennoscandia that are virtually devoid of vascular plants and is thus and Spitsbergen is well differentiated. The difference is described as the Anthelia juratzkana-Polytrichastrum distinct in the cryptogam layer: on Spitsbergen, mosses sexangulare type, also found at relatively high altitudes in such as Aulacomnium turgidum, Hylocomium sp lendens the oceanic sectors of northern Norway (Virtanen et al. var. alaskanum, Oncophorus wahlenbergii, Sanionia unpubl. data). uncinata and Tomentypnum nitens are frequent and of­ ten also abundant. Koenigia islandica-Phippsia algida community (KPC) This community cluster represents a distinct community Salixpolaris-Silene acaulis type (SpSacT) characterized by a hydrophilous moss Wa mstorfia exan­ In this community, the most abundant species are Salix nulata growing in mats on which e.g. Saxifraga stellaris polaris and Silene acaulis. Other characteristic species frequently flourishes. Anthelia juratzkana and Pleuro­ include Cerastium arcticum, Oxyria digyna and Saxifraga cladula albescens are characteristic hepatics. This com­ cemua. In the field layer, there are small herb species that munity resembles Gj rerevoll' s (1956: 356) Phippsia do not typically occur in the latest snow beds (e.g. Anten­ algida-sociation, but the coverage of herbs in the field naria porsildii, Erigeron uniflorus and Gnaphalium layer is lower in his material. Due to scanty material (only supinum). The cryptogam layer is rich in moss and lichen two sample plots in this cluster), our characterization has species, and none of the species has a dominant position. to be regarded as tentative. The closest counterpart in Gj rerevoll's material is found in the association Oppositifolietum. Some sample plots from Swedish Tome Lappmark (Gjrerevoll 1956: table 59, column 8) are rather similar, but such species as 3.1.6 Saxifraga oppositifo lia group Sauteria alpina are missing in our material. This commu­ Moderate-late snowbeds on calcareous substrates; nity, overall, does not conform with the Oppositifolietum Appendix 6, Fig. 12b of Gj rerevoll (1956). It thus appears that this community could then be described as a new vegetation type in order This community group represents vegetation on calcare­ to characterize the vegetation on moderate snowbed sites ous soils along a gradient from the sites with moderate on calcareous substrates. This type of vegetation occurs in snow cover to the sites with late snow. In the TWINSPAN concave terrains in typical snow accumulation sites, but at analysis, three community clusters were recognized. One higher altitudes also on relatively convex mountain slopes of the community clusters, DocCtT, is placed relatively (e.g. on the southernslopes of Mt. Pihkahistama, northern close to the Dryasocto petala-Carex rupestris type (Fig. Norway, own observations). 5a). The two remaining community clusters, SpSacT and SoppRsT, are noted among the sites with late-lying snow. Saxifraga oppositifolia-Ranunculus sulphureus type In terms of species composition, these snowbed commu­ (SoppRsT) nities are related to Gj rerevoll' s (1956: table 59) alliance At first sight, this vegetation may give an impression of Oppositifolio-Oxyrion. a barren ground devoid of any higher plants. Indeed, the field layer is poor, but after close examination many Dryas octopetala-Cassiope tetragona type (DocCtT) species can be found (Fig. 13). The most characteristic This community is clearly dominated by Dryasoctopetala species are Equisetum variegatum, Ranunculus sulphu­ and Cassiope tetragona. In smaller amounts, but con­ reus, and Saxifraga oppositifolia. The moss cover is not stantly, Salix polaris, S. reticulata, Saussurea alpina thick, but many small acrocarpic species occur and may and Thalictrum alpinum occur. Cetraria ericetorum and reach covers of a few percentages (e.g. Distichium C. islandica are relatively abundant while Mnium blyttii capillaceum, Fissidens osmundoides, Meesia uliginosa is one example of many calciphilous mosses. This com­ var. arctica, Tortella fragilis and To rtula norvegica). munity resembles the association Cassiopetum tetragonae Among the mosses there may be some rare species (e.g. dryadetosum of Nordhagen (1955), but in Nordhagen's Tayloriafroelichiana). The calcicolous lichen Solorina sample material Hylocomium splendens dominates the bispora is rather constant. This community is clearly ground layer (not at all in our material). This community calcitrophic and usually found in terrain with calcareous can be interpreted as a middle oroarctic counterpart of outcrops. The closest counterparts in Gj rerevoll' s (1956) Bringer's (1961) Tetragono-Dryadetum alectorietosum descriptions are found among the associations Oppositi­ described from northern Sweden. The counterpart de- fo lietum and Ranunculetum nivalis. However, the units

Acta Phytogeogr. Suec. 82 Middle oroarctic vegetation in Finland and middle-northern arctic vegetation on Svalbard 25

Fig. 13. A snowbed of Saxifraga oppositifolia-Ranunculus sulphureus type. Mt. Guonjarvarri. Alt. 950 m. July 1989. (Photo: Risto Virtanen.)

of Gj rerevoll are relatively narrow. It seems that this Papaver dahlianum group and the Dryasoctopetala group. cluster can be described as a new type. This type, to be The latter main group was divided into three groups: wet called the Saxifraga oppositifolia-Ranunuculus sulphu­ moss snowbeds, snowbed communities dominated by reus type, is relatively broad, containing both snowbeds Sanionia (the Sanionia snowbed communities) and moss characterized by Ranunculus sulphureus and by Saxifraga tundra communities dominated by robust mosses other oppositifolia. This community type shows a transition to than Sanionia. Consequently, the Spitsbergen material is the Salix polaris-Silene acaulis type without any distinct summarized in six community groups containing alto­ border; it also shows a transition to the most extreme gether 16 community types or variants. snowbed community characterized by scattered Sagina The main gradient structure of the Spitsbergen mate­ nivalis and Saxifraga tenuis, or by cryptogams only. rial resembles that of northern Fennoscandia (Fig. 14). The first DCA axis can be related to unequal snow distri­ bution, as the snowbed sites with copious moss communi­ ties are placed to the left and the deflation heaths with 3.2 Spitsbergen poor plant cover lie to the right. On Spitsbergen, the In the Spitsbergen data, the first TWINSPAN division topographic gradient is related except for differential snow allocated the material into two main groups: (1) heath-like depth and permafrost, as the depth of the active layer vegetation characterized by Dryas octopetala, Luzula varies along the topography (Eurola 1968; R0nning 1969; arcuata ssp. confu sa and/or Salix polaris, and (2) moss­ SUiblein 1971). This influences the temperatures in dominated tundra and snowbed vegetation (Fig. 4). The rhizosphere and moisture conditions: on slopes the melt former main group was then divided into three groups water seeps to grounds irrigating the soil surface during differentiated along topographic and edaphic gradients, the vegetation period. The second gradient is not easy to and to some extent along a regional (climatic) gradient. interpret. The communities at the other end of the gradient The divisions result in the Luzula confusa group, the are characterized by Cassiope tetragona, Dryasoctopetala

Acta Phytogeogr. Suec. 82 26 R. Virtanen & S. Eurola

and Bistorta vivipara. The mosses Hy locomium sp lendens 4 ,3------�.------.------�------. var. alaskanum and Tomentypnum nitens indicate nutri­ ent-rich soil conditions relatively favourable conditions of the inner fj ord region. The other end of the second gradient is occupied by communities characterized by 3 Cetrariella delisei and Racomitrium lanuginosum. The community clusters with copious occurrence of R. lanu­ + C\1 ginosum originate from the southwestern coastal region, 1.{) V and Papaver dahlianum communities prevail in climati­ e, 2 cally cold areas (Kjellstrom-Agardhdalen area). Conse­ N quently, the second gradient can be expected to reflect < } 0 !I both climatic and edaphic differentiation (gradient termed 0 j 'edaphic favourableness'). Due to regional differentiation "i of the vegetation on Spitsbergen, the number of sample plots in each of the three subareas (west-southwestern coastal region, inner fj ord region and Dryas region) are indicated in the community descriptions. The regions are abbreviated as C:I:D, respectively, followed by the number of sample plots. 2 3 4 DCA 1 (0.539)

Fig. 14a. 3.2.1 Luzula confusa group

Chionophobous-chionophilous heaths rich in bryophytes and lichens; Appendix 7, Fig. 15a closed plant cover. In its floristic composition this com­ This community group consists of three community clus­ munity seems to correspond partly to the Luzulo confusae­ ters that are characterized by relatively high covers of Salicetum polaris Hadac (Hadac 1989). However, the Cetrariella delisei, Luzula arcuata ssp. confusaand Salix character species mentioned by Hadac (1989) include polaris. The moss layer is strongly fragmented with Anastrophyllum minutum, Kiaeria glacialis and Racomitrium canescens, R. lanuginosum, and Sanionia Tritomaria quinquedentata which are not characteristic uncinata as chief constituents with varying abundances in in our material. This type vegetation is wide-spread on the community types. This group of communities is diffi­ Spitsbergen C:I:D=1 :4:2. cult to compare with any of the traditional alliances re­ viewed by Elvebakk (1994). In Eurola (1968) this group Luzulacon fusa-Racomitrium lanuginosum community represents chiefly the 'Flechtenheide' vegetation of the (LcRIC) western coast (Cladina mitis region). The closest counter­ This community is characterized by patches of Raco­ parts can be found in the alliance Luzulion arcuatae mitrium lanuginosum and a more uniformly developed representing vegetation on moderate ridges with acidic vegetation of Cetrariella delisei. In the field layer, substrates. The clusters LcGC and LcRlC seem to repre­ Saxifraga oppositifolia is the most prominent species, sent chionophobous communities, and LcSaC occupies while Cardamine bellidifo lia is a characteristic subdomi­ more sheltered sites (Fig. 14). nant. In the ordination this community is placed among chionophobous clusters with infertile soils (Fig. 14). In its Luzulacon fusa-Gymnomitrion corallioides community species composition, this community seems to resemble (LcGC) the Cetrariella delisei-Saxifraga oppositifo lia tundra This community is characterized by Luzula arcuata ssp. (Nimis 1985), included in snowbed communities of the confusa and Salix polaris occurring with about equal Luzulion nivalis by Elvebakk (1994), but Racomitrium cover (11-12 %, on average). The bottom layer is chiefly lanuginosum occurs only scarcely. Elvebakk regarded it characterized by Cetrariella delisei and Sanionia unci­ ecologically as moderate snowbed. However, the occur­ nata. Moreover, Gymnomitrion corallioides is relatively rence of Racomitrium lanuginosum suggests that this abundant. The total number of species is high, but many community is chionophobous. On these grounds, this of them occur irregularly which may partly be due to a community seems to correspond to vegetation in the Sphae­ mosaic vegetation structure created by polygon activity rophoro-Racomitrietum lanuginosi (Hofmann 1968). It is (Fig. 18a). The less active polygon centres are colonized ecologically related to the R. lanuginosum dominated by G. corallioides, and the interspaces have a more communities which on Spitsbergen seem to be confined

Acta Phytogeogr. Suec. 82 Middle oroarctic vegetation in Finland and middle-northern arctic vegetation on Svalbard 27

.. Dry oct

• cyanoba .. Tom nit ..ste riv Pol viv• •Hyl ala •Cas tet •Hyp rev •Poa arc

.. Aul tur • ..Luz arc Alo alp

.Pti cil .. •Oxy dig •Die fus Pol arp • Rac can

.. L� con .. ..Psoh yp Ste alp Bry sp

.. •Sax ces Cer arc Och fri• .. Sax opp .. Cet isl

GyDJ cor -.].5 +4.5

Rac lan + .. Cet del

Fig. 14. Ordination diagram of axis 1 against axis 2 using Detrended Correspondence Analysis (DCA) for the TWINSPAN groups (a: overleaO in the material of Spitsbergen. The centroids (points) are mean sample scores for the first two DCA axes. Circled areas indicate S.D. of the scores with respect to the axes. AtAbC - Aulacomnium turgidum-Alopecurus borealis community, AtHC - Aulacomnium turgidum-Hylocomium community, DocSaC - Dryas octopetala-Sanionia community, DocSpC - Dryas octopetala-Salix polaris community, DocTC - Dryas octopetala-Tomentypnum community, LcGC - Luzula confusa-Gymnomitrion corallioides community, LcRlC - Luzula confusa-Racomitrium lanuginosum community, LcSaC - Luzula confusa-Sanionia community, PdP - Papaver dahlianum polar desert, PdRpC - Papaver dahlianum-Racomitrium panschii community, RcOxC - Racomitrium canescens-Oxyria community, SaC - Sanionia snowbed community, SaPalpC - Sanionia-Poa alpigena community, SaShypC - Sanionia-Saxifraga hyperborea community, SoppHrC- Saxifraga oppositifolia-Hypnum revolutum community. DCA ordination of the species (only most common shown) (b) Alo alp -Alopecurus borealis, Aul tur -Aulacomnium turgidum, Bry sp - Bryumspp., Cas tet - Cassiope tetragona, Cer arc - Cerastium arcticum, Cet del - Cetrariella delisei, Cet isl - Cetraria islandica, Cyanoba - Cyanobacteria, Die fus - Dicranum fuscescens, Dry oct - Dryasoctopetala, Gym cor - Gymnomitrion corallioides, Hyl ala - Hylocomium sp lendens var. alaskanum, Hyp rev - Hypnum revolutum, Luz arc - Luzula arctica, Luz con - Luzula arcuata ssp. confusa, Och fri - Ochrolechiafrigida, Oxy dig - Oxyria digyna, Poa alg - Poa alpigena, Poa alp - Poa alpina, Poa arc - Poa arctica, Pol alp - Polytrichastrum alpinum, Pol viv - Bistorta vivipara, Pso hyp - Psoroma hypnorum, Pti cil - Ptilidium ciliare, Rac can - Racomitrium canescens, Rac lan - Racomitrium lanuginosum, San unc - Sanionia uncinata, Sar sar - Sarmentypnumsarmentosum, Sax ces - Saxifraga cespitosa, Sax opp - Saxifraga oppositifolia, Ste alp - Stereocaulon alpinum, Ste riv - Stereocaulon rivulorum, Tom nit - Tomentypnum nitens.

Acta Phytogeogr. Suec. 82 28 R. Virtanen & S. Eurola b) op c) � I I 0.363 I 0.305 4 I I 8 [I]

PdP PdRpC SoppHrC

le GC lcRIC Le SaC

DocTC Docsac DoeS pC

Fig. 15a-c. TWINSPAN divisions �fa) the Luzula confusa group. LcGC - Luzula confusa-Gymnomitrion corallioides community, . . LcRlC - Luzula confusa-Racomltrzum lanugmosum community, LcSaC - Luzula confusa-Sanionia community. b) the Papaver . dahlzanum. group. PdP - Papaver dahlzanum polar desert, PdRpC - Papaver dahlianum-Racomitrium panschii community. c) Dryas octopetala group. DocSaC - Dryas octop�tala-Sanionia community, DocSpC - Dryas octopetala-Salix polaris community, DocTC _ Dryas octo?etala-Tomentypnum commumty, SoppHrC - Saxifraga oppositifolia-Hypnum revolutum community. Numbers of sample plots and e1genvalues of the divisions are indicated.

to stable bouldery sites (Hartmann 1980) and to more 3.2.2 Papaver dahlianum group oceanic parts of SW Spitsbergen (Triloff 1944; Kuc 1963; Polar deserts and associated ridge communities; Appendix Dubiel & Olech 1990), occurring sporadically in the inner Fig. 15b fj ord region (Hartmann 1980) and northern parts of 8, Spitsbergen (Summerhayes & Elton 1928; Brattbakk This community group with two community clusters repre­ 1983). In our material, this community was encountered sents the vegetation approaching vegetation of polar deserts solely in the Homsund area (C:I:D=7:0:0) which further (Bliss et al. 1984; Aleksandrova 1988). At fr rst sight, the strengthens its affinity to the oceanic Racomitrium species composition and abundance relationships of the lanuginosum heaths (see also Virtanen et al. 1997b). two clusters seem to differ clearly from the rest of the Spitsbergen material, thus it is surprising that they do not Luzula confusa-Sanionia community (LcSaC) fall into any extreme position in the ordination, but that they In the field layer of this community, Luzula arcuata ssp. lie between the Luzula con fusa group and the Dryas confusa is the most conspicuous species, and Salix polaris octopetala group. Soil movements combined with abrasive reaches a mean cover of about 10%. In the cryptogam winds are probably responsible for the sparse vegetation, layer Cetrariella delisei is only a minor constituent, while and these sites are also exposed to the coldest winter Sanionia uncinata has a relatively high cover. Among conditions. At certain places in winter time, reindeer is other mosses, Dicranum angustum and Hylocomium searching for food from sites with a thin snow cover, and sp lendens var. alaskanum are common. The community therefore grazing can also have a local impact on these seems to be more mesic in its species composition than the communities. The two clusters in this group are differenti­ two other communities in this group, and it is also placed ated alike with regard to soil stability (intensity and fre­ close to the moss tundra communities in the ordination quency of cryoperturbation). These two clusters are best (Fig. 14). This community has a distribution with a centre understood as fixedpoints in a continuum frommore or less of occurrence in the coastal areas (western Isfjorden and barren ridges to more closed communities on hill slopes. Homsund). C:I:D=3:3:0.

Papaver dahlianum polar desert (PdP) The total vegetation cover of this community cluster is

Acta Phytogeogr. Suec. 82 Middle oroarctic vegetation in Finland and middle-northern arctic vegetation on Svalbard 29

about 10% on average. The plant debris consists of Draba The three clusters rich in Dryas octopetala can be spp., Luzula arcuata ssp. confusa, Papaver dahlianum, related to R�nning's (1965) classification scheme of the Poa arctica, and Potentilla hyparctica. Scatteredly grow­ Dryadion. He recognizes four communities: Nardino­ ing Tortula ruralis is a typical moss, while this commu­ Dryadetum,Rupestri-Dryadetum, Polari-Dryadetum, and nity is devoid of any robust mosses. The occurrence of Tetragono-Dryadetum, differentiated chiefly in relation such mosses is probably prevented by a high disturbance to topographic position. The Nardino-Dryadetum and rate. Among lichens, Cladonia pocillum is characteristic. Rupestri-Dryadetumcommunities appear to be missing in This community corresponds quite well to the Papaveretum our data. Community clusters resembling only the dahliani typicum (Hofmann 1968) or to the Papaverion chionophilous communities, the Polari-Dryadetum and da hliani (Hadac 1946). It is similar to the Papaver the Te tragono-Dryadetum, can be recognized. However, dahlianum polar desert described from altitudes of 400- the TWINSPAN analysis produced compositionally some­ 600 m above sea level in the Adventdalen region (Virtanen what different communities as compared to the descrip­ et al. 1997b). The nature of this community conforms tions of R�nning (1965). largely to that reported from polar deserts of Devon Is­ land, Arctic Canada (Bliss et al. 1994). The sample plots Dryas octopetala-Tomentypnum community (DocTC) in this cluster were encountered in the Kj ellstromdalen­ This community has a well-developed moss layer with Agardhdalen region. C:I:D=0:0:4. Aulacomnium turgidum, Hy locomium splendens var. alaskanum and Tomentypnum nitens as the main constitu­ Papaver da hlianum-Racomitrium panschii community ents (Fig. 16). The most prominent vascular plants are (PdRpC) Dryas octopetala, Luzula arcuata ssp. confusa and Salix This community has a more closed plant cover than the polaris. The community roughly corresponds to the asso­ Papaver dahlianum polar desert type described above. ciation Cassiopo tetragonae-Dryadetum octopetalae Here, Salix polaris, Saxifraga cespitosa, and S. opposi­ (Hadac 1946; R�nning 1965), partly to the Tomenthyp­ tifolia are somewhat more abundant, in addition Cerastium netum involuti (Hadac 1946) and to the Homalothecium arcticum, Festuca hyperborea, and Minuartia rubella are nitens-Dryastype ofElvebakk (1994). This community is frequent. Hypnum revolutum and Racomitrium species relatively wide-spread on Spitsbergen C:I:D=0:3:4. (Racomitrium canescens and R. panschii) occur rather regularly. Lichen cover is also better developed than in Dryas octopetala-Sanionia community (DocSaC) the Papaver dahlianum polar desert: e.g. Ochrolechia This community resembles the DocTC in its species com­ spp. have a relatively high cover. This community repre­ position, but Sanionia uncinata dominates the bottom sents vegetation on exposed ridges showing a gradual layer and Tomentypnum nitens is a subdominant. As sug­ transition to polar desert vegetation and it corresponds to gested by the abundance of S. uncinata and its position in the Papaveretum dahliani salicetosum polaris (Hofmann the ordination (Fig. 14), this community seems to repre­ 1968). This is included in the alliance Caricion nardinae sent an intermediate type between moss tundra communi­ comprising vegetation on exposed ridges on alkaline and ties and communities of the Dryas octopetala group. circumneutral substrates (Nordhagen 1936; Elvebakk There seems to be no counterpart described earlier. This 1985, 1994). This community is confined to the Dryas community is largely restricted to the inner fj ord region region (Slettvika-Agardhdalen), C:I:D=0:0:4. (the Adventfjorden-Sassendalen areas). C:I:D=0:9: 1.

Dryas octopetala-Salix polaris community (DocSpC) Dryas octopetala and Salix polaris characterize the field 3.2.3 Dryas octopetala group layer. Some of the sample plots have Cassiope tetragona Xeric Dryas-bryophyte heaths; Appendix 9, Fig. 15c with a relatively high cover. Cerastium arctic urn occurs with a cover of 0.5 %, and Poa arctica is frequent in The three community clusters, DocTC, DocSaC and small numbers. The moss carpet is fragmented and none DocSpC, assigned to this group embrace chionophobous­ of the species is very constant. Sanionia uncinata and chionophilous vegetation characterized by Dryasoctopetala Tomentypnum nitens are the most abundant species. On occurring with a relatively high cover of 15-25%. The three the basis of the ordination (Fig. 14), this community is clusters overlap broadly in the ordination (Fig. 14), while slightly more chionophobous than the Dryas octopetala­ the fourth cluster, SoppHrC, is recorded in the relatively Tomentypnum and D. octopetala-Sanionia communities extreme position along the first DCA axis indicating its described above. This community resembles the 'Salix chionophobous nature. In this community, D. octopetala polaris-Dryas octopetala -Soziation' of Hofmann has a low cover. Instead, many calciphilous plants thriving (1968:29), and partly also the Tetragono-Dryadetum on exposed ridges, e.g. Minuartia rubella, Saxifraga (R�nning 1965). It is similar to the Dryas octopetala­ jlagellaris and Silene furcata are characteristic. Salix polaris community described in Virtanen et al.

Acta Phytogeogr. Suec. 82 30 R. Virtanen & S. Eurola

Fig. 16. Dryas octopetala-Tomentypnum tundra. Adventdalen, Mt. Louisfjellet. July 1990. (Photo: Risto Virtanen.)

(1997b). It may be regarded as a community occupying moss communities reported from Truelove Lowland (Muc slopes with thin snow cover, chiefly in the inner fj ord & Bliss 1977), the ridge communities from Bathurst Is­ region of Spitsbergen. C:I:D = 0:4:2. land (Sheard & Geale 1983) and the Saxifraga opposi­ tifolia-Luzula confusabased community type on Alexandra Saxifraga oppositifolia-Hypnum revolutum community Fiord uplands, Canadian High Arctic (Batten & Svoboda (SoppHrC) 1994). This is the only community assigned to this group having Dryas octopetala in low abundance and frequency. This community resembles to a large degree the Papaver 3.2.4Alopecurus borealis-Aulacomniumturgidum group dahlianum-Racomitrium panschii community (see above) in its species composition. However, in comparison, Moss tundra vegetation; Appendix 11, Fig. 17a Racomitrium canescens and R. panschii are lacking, while indicators of calcium carbonate-rich substrate are fre­ This community group consists of four community clusters quent (e.g. Distichium capillaceum, Ditrichum flexicaule representing moss-dominated tundra vegetation. The char­ and Encalypta spp.). The plant cover is more closed and acteristic moss species include Aulacomnium turgidum, e.g. Saxifraga oppositifolia has a relatively high cover. Hy locomium sp lendens var. alaskanum, Sanionia uncinata This community can be equaled with the Saxifraga and Tomentypnum nitens. In the field layer such species as oppositifolia-Hypnum revolutum community in Virtanen Alopecurus borealis, Luzula arctica, L. arcuata ssp. confusa et al. (1997b) occupying ridges on moderately cryoactive and Salix polaris are characteristic. The abundance rela­ sites. It is widespread on Spitsbergen (C:I:D=0:3:2) in tionships of mosses vary between community types. The transitions from closed vegetation to open screes. It mosses reach a closed cover. This vegetation is showing a resembles the cushion plant-lichen and cushion plant- transition to the Sanionia dominated snowbeds and to the

Acta Phytogeogr. Suec. 82 Middle oroarctic vegetation in Finland and middle-northern arctic vegetation on Svalbard 31

a) b)

SaC SePalpC

SaShypC AtAbC AtHC RcOxC

Fig. 17a-b. TWINSPAN divisions of: a) the moss tundra communities. AtAbC - Aulacomnium turgidum-Alopecurus borealis community, AtHC - Aulacomnium turgidum-Hylocomium community, RcOxC - Racomitrium canescens-Oxyria community, SaShypC

- Sanionia-Saxifraga hyperborea community; b) the Sanionia snowbed communities. SaC - Sanionia snowbed community, SaPalpC ­ Sanionia-Poa alpigena community.

mossy Dryas octopetala tundras (the Dryas octopetala­ uncinata, and hydrophilous Sarmentypnum sarmentosum. Sanionia community). This is visible in the ordination (Fig. In addition, characteristic bryophyte species include 14), where one of the clusters, SaShypC, is close to the Conostomum tetragonumand Gymnomitrion concinnatum. Sanionia snowbed communities, and cluster RcOxC is The field layer is sparse: characteristic species are Phippsia placed between the Dryas octopetala group and the moss algida and Saxifraga hyperborea indicating snow bed con­ tundra communities. The boundary between Sanionia ditions. In the ordination, this community is placed close snowbeds and moss tundra communities is diffuse. The to the Sanionia snowbeds (Fig. 14). This is probably an Luzula confusa-Sanionia community also lies close to those intermediate community between the moss tundra com­ in the ordination (Fig. 14). The clusters SaShypC, AtAalC munities and the Sanionia snow beds (the 'Drepanocladus

and AtHC prevail in the Sveagruva-Kjellstromdalen area. uncinatus-Schneeboden ' Hofmann 1968; Philippi 1973). The communities dominated by Tomentypnum nitens are This community is encountered in the Slettvika-Kj ellstrom­ central among the moss tundra communities described dalen area, C:I:D=0:0:6. earlier from Spitsbergen (Hadac 1946; Hofrnann 1968; Philippi 1973). In our material, none of the communities is Aulacomnium turgidum-Alopecurus borealis commu­ clearly dominated by T. nitens. In our plots, T. nitens nity (AtAbC) abounds in communities of the Dryas octopetala group. In this community, the most abundant moss is Aula­ This may be due to the fact that T. nitens does not thrive in comnium turgidum. Dicranum majus, Sanionia uncinata prolonged wet conditions (Hofrnann 1968). These condi­ and Tomentypnum nitens are found less frequent. Some tions favour hydrophytic mosses such as Scorpidium hydrophilous mosses such as Sarmentypnumsarmentosum revolvens. It seems better not to emphasize the presence or and Scorpidium revolvens are relatively frequent. This absence of T. nitens in the moss tundra communities. In this community is likely to show a transition to the wet snow bed respect, the collective treatment of moss tundra communi­ communities (see below and Fig. 18) and is characteristic ties [following Eurola (1968): the 'frischeMoosheiden '] is in the Dryasregion (C:I:D=0:0:4). justifiable. Aulacomnium turgidum -Hylocomium community Sanionia-Saxifraga hyperborea community (SaShypC) (AtHC) In this community prevalent mosses include Dicranum This community resembles the Aulacomnium turgidum­ angustum, Polytrichastrum alpinum, especially Sanionia Alopecurus borealis community in its species composi-

Acta Phytogeogr. Suec. 82 32 R. Virtanen & S. Eurola

tion. These communities are also close to each other in the and to the 'Schneebodenstellen' (Eurola 1968). Elvebakk ordination (Fig. 14). In this community, hydrophilous ( 1994) included these vegetation units in the alliance species are almost absent, instead Hy locomium sp lendens Drepanoclado-Poion alpinae (Hadac 1946). Relatively simi­ var. alaskanum and Polytrichastrum alpinum occur with a lar communities dominated by Sanionia are found on Bear cover of 2-3%. This community, like the Aulacomnium Island (Virtanen et al. 1997b). turgidum-Alopecurus borealis community, do not corre­ In the ordination (Fig. 14), these two communities lie spond well to the earlier descriptions of mossy tundras, at an extreme position along the first DCA axis. They i.e. Tomentypnum nitens dominated tundras (Hadac 1946; show regional allopatry: the first (SaC) is present mainly Hofmann 1968; Philippi 1973) or dry or moist moss at the southwest-west coast area (Homsund), while the heaths (Eurola 1968). This community resembles the other (SaPalpC) prevails chiefly in the Dryas region. The Luzula confusa-Sanionia community (LcSaC, see above), two communities can thus be suggested to represent re­ but has a relatively high cover of Tomentypnum nitens. gional variants of a single community type. Moreover, the Luzula confusa-Sanionia community has its main distribution in the coastal areas of westernIsf jorden Sanionia snowbed community (SaC) and Homsund, whereas this community is restricted to the The mean cover of Sanionia uncinata is about 60%, often Slettvika-Kjellstromdalen area (C:I:D=O: 1 :9). reaching 80- 100 %. Aulacomnium palustre, A. turgidum and Calliergon stramineumare often present with a cover Racomitrium canescens-Oxyria community (RcOxC) of a few percentages. The field layer typically includes This community is also bryophyte-dominated, and now Cerastium arcticurn, Salix polaris, Saxifraga oppositifolia Racomitrium canescens is the most abundant species. In and S. rivularis. This community prevails chiefly in the addition, Aulacomnium turgidum, Sanionia uncinata, and coastal areas of the Homsund region and in the mouth of Tomentypnum nitens are relatively abundant. This type of Isfjorden (C:I:D=6:2:0). vegetation includes sample plots with abundant Cassiope tetragona (mean cover 20 % ). Otherwise, the field layer is Sanionia-Poa alpigena snowbed community (SaPalpC) scarce: typical species are Luzula arcuata ssp. confusa, This community is closely similar to the Sanionia snowbed Oxyria digyna and Stellaria longipes. Irregularly also community described above. The cover of Sanionia Draba alpina, Pedicularis lanata ssp. dasyanthaand Sile ne uncinata is slightly lower (mean 45 % ). Tomentypnum furcata are found. This community cannot be equaled nitens is present with a mean cover of about 4 %. The field with the 'Racomitrium canescens-Gesellschaft ' described layer is somewhat richer in its species composition: Bistorta by Philippi (1973) from SE Spitsbergen. The community vivipara, Equisetum arvense and Poa alpigena and are described by Philippi is poorer in vascular plants and typical species. The dominance of Sanionia is lower, and represents a community on calcium-poor, dry substrate at a grarninoid, Poa alpigena, is distinctly more abundant. relatively high altitudes. This Racomitrium canescens­ One reason for the higher abundance of Poa alpigena in Oxyria community cluster partly contains early succes­ the inland may be reindeer grazing. This community sional communities near river shores on valley bottoms prevails in the Slettvika-Kjellstromdalen region (C:I:D (one of the plots is situated on a glacier foreland) and =0:0:8) where also reindeer occur, whereas in the SW partly relatively mesic chionophilous heaths on nutrient­ coastal area grazing is negligible (Punsvik et al. 1980). rich sites. In the ordination, this community lies at an intermediate position between the Dryas octopetala and moss tundra communities (Fig. 14). It is mainly found in 3.2.6 Wet moss snowbeds the inner fj ord region (C:I:D=0:6: 1). Appendix 12, Fig. 4

Scorpidium revolvens-Tomentypnum snowbedcommunity 3.2.5 Sanionia snowbeds This community cluster distinguished by TWINSPAN is Appendix 11, Fig. 17b dominated by Scorpidium revolvens and Tomentypnum nitens. Campylium stellatum, Sanionia uncinata and There are two community clusters recognized by TWIN­ Sarmentypnum sarmentosum are also relatively abun­ SPAN that are heavily dominated by Sanionia, whereas dant. The field layer is characterized by Bistorta vivipara, other mosses rarely occur with covers of over 5 %. The Equisetum arvense and E. variegatum, and with some field layer is scarce: prostrate plants typical of snowbed Saxifraga hirculus and S. oppositifolia. These wet sites are creeping on the moss mat (Fig. 18d). Cerastium snowbeds can be expected to show a transition to the regelii and Poa alpigena are the most characteristic spe­ arctic mire vegetation (Eurola 1971). Such gradients cies. Both of these clusters correspond to the 'Drepanocladus have been described in northern Spitsbergen (Reindeer uncinatus-Schneeboden ' (Hofmann 1968; Philippi 1973) Peninsula) by Dahle (1983): Sanionia communities occur

Acta Phytogeogr. Suec. 82 Middle oroarctic vegetation in Finland and middle-northern arctic vegetation on Svalbard 33

a

b

Fig. 18. Tundra vegetation NE of van Mijenfjorden, near Darnesmorena. (a) Wind-exposed Luzula confusa-Gymnomitrion tundra. Polygon centres mostly plantless. (b) Aulacomnium turgidum-Hylocomium-rich tundra, with raised polygon centres. (c; overleaf) Alopecurus borealis-Aulacomnium-rich tundra, with reticulate frost patterns. (d; overleaf) W of Darnesmorena, topographic ridge­ depression transect. Above Barren communities approaching polar desert, depression Sanionia snowbed communities and wet moss communities. July 1969. (Photos: Seppo Eurola.)

Acta Phytogeogr. Suec. 82 34 R. Virtanen & S. Eurola

Fig. 18c

d

between Dryas heaths and wet snowbeds. The Sanionia area. The wet moss snow beds are obviously wide-spread snowbeds are more hydrophytic in nature, approaching on Spitsbergen in the inner fj ord and Dryas regions the wet snowbeds with the mosses Pseudocalliergon (C:I:D=0:2:3). Comparable moss communities are re­ turgescens ( = Scorpidium turgescens) and Scorpidium ported from Bathurst Island, Arctic Canada (Miller & revolvens ( = Drepanocladus revolvens) as prominent Alpert 1984) and from Barrow, Alaska (Rastorfer 1978). species. The latter species is frequent and abundant also in the wet moss snowbeds in the Kj ellstrom-Agardhdalen

Acta Phytogeogr. Suec. 82 4 Topographic patterns: series of communities in ridge-depression transects

Both in northwestern Fennoscandia and on Spitsbergen, When the snow cover increases, cryoactivity decreases, the topographic variation and consequent uneven distri­ as well as the impact of abrasive winds; snow cover gives bution of snow cover and moisture account for the pri­ protection against drought in early spring. At these weakly mary pattern of vegetational variation at a given altitude chionophobous sites, the conditions are relatively favour­ as is generally observed in the arctic and alpine environ­ able, and the vegetation occupying these sites represent ments (e.g. Vestergren 1902; Nordhagen 1928; Dahl 1957; the Empetrum-Flavocetraria nivalis type, wide-spread in

R�nning 1969). The topographic variation gives rise to the subcontinental lower oroarctic zone ( = Empetrum­ series of communities (=community complex) from wind­ Cetraria nivalis type in Haapasaari 1988; Oksanen & exposed ridges to depressions with more or less late-lying Virtanen 1995: fig. 26). In our study area, the communi­ snow fields. In many earlier works, the community series ties characterized by Empetrum nigrum ssp. herma­ have been illustrated using transect data (e.g. Dah1 1957; phroditum reach altitudes of about 950 m, extending only Gj rerevoll 1956; R�nning 1969; Brossard et al. 1984; sporadically to higher elevations. In northerly exposed Oksanen & Virtanen 1995), which makes it possible to slopes, Empetrum heaths are confinedto markedly lower characterize the small-scale variation in vegetation. In altitudes. Thus, E. nigrum ssp. hermaphroditum might be this study, focusing on larger scale patterns,the essential regarded as a thermophilic species in the middle oroarctic features can be idealized based on ordination and classifi­ zone, where the presence of Cassiope tetragona suggests cation schemes. Moreover, field notes and comparisons a further narrowing of the habitat range. with earlier literature have been used to increase the The Empetrum-Flavocetraria nivalis type shows a understanding of the data. transition to the ]uncus trifidus-Cassiope tetragona type, which represents the core of the weakly chionophilous vegetation of the middle oroarctic zone (e.g. Nordhagen 1943; Oksanen & Virtanen 1995). The type is broad 4.1 Northwestern Fennoscandia including a wide array of ecologically differentiated vari­ In the middle oroarctic zone of northwesternFennoscandia, ant communities. In the Kilpisjarvi district, a community two major series of communities are recognized along a with eo-occurring Cassiope tetragona and ]uncus trifidus ridge-depression transition: in the field layer, described as the typical variantof JtCtT, (1)1heseries on siliceous substrate. In the DCA ordination, is prevalent. The mixed community probably indicates this series makes a cross-section fromthe communities of the site conditions in which various factors maintain a dy­ Alectoria group to the latest snowbed communities of the namic equilibrium between these two species, which in Ranunculus glacialis group (Fig. 5, Fig. 19a). On wind­ principle, occupy partially overlapping ecological niches. exposed ridges, heaths of the Empetrum-Cassiope tetragon,a­ Both of the species are chionophilous, but C. tetragona is Alectoria type or the Empetrum-Cassiope tetragona type are weakly calciphilous (Nordhagen 1955) and J. trifidus found. The former type represents communities with their strongly acidophilous (Nordhagen 1943; Dahl 1957). How­ main distribution on continental mountains (the Empetrum­ ever, in the ordination (Fig. 5b), a reverse pattern is Phyllodoce-Alectoriatype and the Vaccinium-Alectoria types observed: C. tetragona is noted in the acidophilous area of in Oksanen & Virtanen 1995), while the latter type has the ordination space, while J. trifidus is closer to the affinity with the suboceanic-oceanic heaths dominated by calciphilous communities. Some other factors may thus Empetrum nigrum ssp. hermaphroditum (Haapasaari 1988). underlie this pattern. First, there are differences in eco­ The occurrence of both types in the Kilpisjarvi district is not logical amplitude with respect to snow cover: J. trifidus surprising since this district is transitional between continen­ tolerates relatively late-lying snow conditions well (Nord­ tal and oceanic climate (Hamet-Ahti 1963). Both types are hagen 1943; Bocher 1963; Oksanen & Virtanen 1995), encountered on relatively stable soil substrates where dwarf whereas C. tetragona has the highest abundance on stable shrubs are able to reach a relatively high cover. The top weakly snow-protected and/or sheltered slopes at lower plateaux with patterned ground are characterized by the parts of the middle oroarctic zone. Only at such sites, Gymnomitrion type. In polygonal terrain, the frost boils are C. tetragona can monopolize the space. In extreme cases, often largely devoid of higher plants and colonized by the only coexisting species can be mosses such as Hy lo­ Gymnomitrion spp. and the hollows betweenelevations may comium splendens var. alaskanum. C. tetragona may be harbour chionophilous or even hydrophilous plants. sensitive to the reindeer trampling, because its stems lie

Acta Phytogeogr. Suec. 82 36 R. Virtanen & S. Eurola

on the surface as do the stems of Empetrum nigrum ssp. In sites adj acent to the latest snow fields, still existing hermaphroditum (Callaghan & Emanuelsson 1985). In­ in the turn ofJuly- August, the abundance of cryptogams stead, J. trifidustolerates trampling well due to its tussock increases and vascular plants become scattered. In our growth form with rhizomes forming a tightly packed material, the vegetation of the latest snowbeds represents network of short branches. It may be that the ordination the Anthe lia ju ratzkana-P olytric hastrum sexang ulare type also reflects community differentiation imposed by graz­ corresponding to the snowbed communities without a ing pressure. field layer of Gj rerevoll (1956). At Kilpisjarvi, the other major element of the tradi­ Overall, the series on siliceous substrates corresponds tional Juncion trifidi (Nordhagen 1943), the oligotrophic to the pattern introduced from subcontinental mountains Festuca ovina heaths are missing. In our material, heaths of northern Fennoscandia (Oksanen & Virtanen 1995). rich in F. ovina are found at Mt. Saana, where they occupy This study suggests that on level plateaux and in wide relatively nutrient-rich sites (the Festuca ovina-Potentilla depressions there are communities that are not members crantzii group). Thus, the cooccurrence of F. ovina and J. in the mesoscale topographic ridge-depression series. The trifidus heaths at Kilpisjarvi cannot be used as a straight­ series on siliceous substrate is distinctly different from forward indication of climatic differentiation in the same any of the community series of Spitsbergen. way as in the southern part of Norway where ]uncus (2) The series on calcareous substrate. This parallel series trifidus heaths are considered as a more oceanic vegeta­ of communities along a ridge-depression transition can be tion than F. ovina heaths (Nordhagen 1943). abstracted. The series lies in the middle of the second Into the direction of delayed snow-melt, the ]uncus gradient of the DCA ordination (Fig. 5, 19b). The ridges trifidus-Cassiope tetragona heath vegetation gradually are occupied by heaths of the Dryas octopetala-Carex changes into heath-like snow beds of the ]uncus trifidus­ rupestris type which shows a transition to chionophilous Cassiope hypnoides type (Oksanen & Virtanen 1995). communities of the Cassiope tetragona-Dryasoctopetala This type seems to become wide-spread at higher alti­ type. The ridge communities and weakly chionophilous tudes and it is not a typical member of the community heaths are relatively similar to vegetation encountered in series. It is likely that intensified soil cryoactivity and the corresponding sites of Spitsbergen. These heaths of solifluction fragments ]uncus trifidus and Cassiope northwestern Fennoscandia thus represent a link to tetragona clones leaving space for better disturbance­ circumpolar arctic vegetation (Gjrerevoll 1954; Bocher adapted species such as Luzula arcuata ssp. confusa. 1963; R�nning 1965; Eurola 1974). The Salix polaris­ This type prevails in the gradient fromthe middle oroarctic Silene acaulis type represents early snowbeds, and the zone to the upper oroarctic vegetation and it often coexists latest snowbeds are occupied by the vegetation of the with the Cassiope tetragona-Ranunculus glacialis type Saxifraga oppositifolia-Ranunculus sulphureus type. Over­ found on upper oroarctic ridges (Oksanen & Virtanen all, this series is similar to the one described by Gj rerevoll 1995). (1956:33) from Swedish Tome Lappmark. In the latest The persistence of snow cover up to late June or early snowbeds on calcareous substrates, communities domi­ July, gives rise to true snowbed vegetation, which is nated by Distichium capillaceum have been found by represented by two types: the Salix herbacea-Cassiope Gj rerevoll (1956), but such communities were not en­ hypnoides type and the Salix herbacea-Kiaeria type with countered by us. The peculiar Koenigia-Phippsia com­ its Carex bigelowii variant. The Salix herbacea-Kiaeria munity is found close to melting snow-fields maintaining type prevails on sites with later-lying snow (Oksanen & continuous irrigation (Pililsson 1994: fig. 1:9). The Virtanen 1995), while the Salix herbacea-Cassiope hyp­ chionophilous-snowbed communities of northern Fenno­ noides type emerges earlier from the snow and changes scandia have little in common with corresponding com­ directly to a heath vegetation of the ]uncus trifidus­ munity types on Spitsbergen. Fennoscandian snowbeds Cassiope tetragona type and to the snow bed vegetation of show at least physiognomic resemblance to the corre­ lower altitudes (the ]uncus trifidus-Deschampsiaflexuosa sponding communities on Alaskan mountains (Gjrerevoll type and the ]uncus trifidus-Cladina mitis type, Oksanen 1980), although in Alaska the mosses appear to be rela­ & Virtanen 1995). The snowbed vegetation characterized tively abundant as compared to hepatics (AIpert & Oechel by Salix herbacea is found on sites that are drained during 1982). the growing season. On sites that are irrigated by melt A third series, encountered only on the slopes of Mt. water or are otherwise moist, as in some depressions with Saana, is clearly different from the twomajor ones: the more or less level ground, the Carex bigelowii type (CbT) community series of the Festuca ovina-Potentilla crantzii prevails. Moreover, these Carex bigelowii snowbeds heaths appears in the lower part of the ordination space emerge earlier from snow as they usually are situated (Fig. 5, 19c). The series is characteristic of sites with away from the latest snow-fields (Nordhagen 1928). On moderately calcareous substrates on slopes with rela­ intermediate sites, one can encounter the Carex bigelowii tively favourable climate. On the ridges, we encounter a variant of the Salix herbacea-Kiaeria type. Festuca ovina and Dryasoctopetala dominated community

Acta Phytogeogr. Suec. 82 Middle oroarctic vegetation in Finland and middle-northern arctic vegetation on Svalbard 37

that shows affinity with the Dryas octopetala-Carex a) Gymnomitrion type (on plateaux) rupestris type. At the chionophilous sites, communities Empetrum-Cassiopetetragona-Aiectoria t. (on smaller ridges) belonging to the Festuca ovina-Potentilla crantzii type Empetrum-Fiavocetraria nivalis t. are prevalent. These communities show a transition to the Ridge Juncus trifidus-Cassiope tetragona early-melting snowbeds characterized as the Festuca t ovina-Saussurea alpina-Sanionia snowbed communities. Salix herbacea-Kiaeria t. The relatively late snowbed sites harbour a vegetation of Antheliajuratzkana-Poly- . the Trisetum spicatum-Sanionia type, also a member in trum sexangulare t

the suboceanic series of communities of Oksanen & Depression Virtanen (1995). b)

Dryas octopetala-carex rupestris type

4.2 Spitsbergen

As in northwestern Fennoscandia, the community series of Spitsbergen, can be abstracted along the ridge-depres­ sion transitions. The gradient analysis (Fig. 14) suggests that the communities of Spitsbergen do not fall into dis­ tinct edaphic series, as is the case in northernFennoscandia. c) Instead, the series can be idealized for each climatically different subareas. Consequently, we distinguish three Festuca ovina-Dryas octopetala community series (Fig. 20): (1) the inner fj ord region; (2) the west­ southwesterncoast region; and (3) the Dryasregion. In the inner fj ord region, two types of ridge heaths prevail (Fig. 20a): ridges with often active patternedground are occupied by relatively open communities, character­ ized by Saxifragaop positifolia (the Saxifraga oppositifolia­ Hypnum revolutum community). This vegetation extends to mountain slopes up to the limits of more or less continu­ Fig. 19a-c. Generalized community series along ridge-depres­ ous plant cover (Virtanen et al. 1997b). Corresponding sion topographic sequences in the middle oroarctic zone of communities are reported also from the Ny Alesund area northwesternFennoscandia: a) siliceous substrate, b) calcareous (Brossard et al. 1984) and from the Dryas region (this substrate, c) eutrophic (slightly calcareous) substrate. study). The Saxifraga oppositifolia-Hypnum revolutum community is relatively broad and contains sample plots approaching the Potentilla pulchella community, so far only anecdotally described (Elvebakk 1994). On slightly less extreme ridges with largely stable substrates, the nated by mosses. The Dryas octopetala-Tomentypnum Dryas octopetala-Carex rupestris community prevails community occupies sites of moderately late-lying snow (Virtanen et al. 1997b). This community is also reported while the Dryas octopetala-Sanionia community occurs from the Ny Alesund area (R�nning 1965; Brossard et al. on late-lying snow beds. The latest snowbeds of the inner 1984 ). On ridges in areas between the inner fj ord region fj ord region are poorly represented in our material. Some and the western coast, the Luzula confusa-Gymnomitrion of them are assigned to the Racomitrium canescens-Oxyria community is encountered. community and some to the Sanionia-Poa alpigena The most outspoken chionophobous communities de­ snow bed community, chiefly encountered in the Dryas scribed above show a transition to Dryasoctopetala-Salix region. These moss-dominated communities occur more polaris communities. The Cassiope tetragona heaths did sporadically in the inner fj ord region (Eurola 1968) where not form any distinct community clusters in our numerical frost churning often breaks the moss carpet and also classification. These communities are, however, rather reindeer trampling may have similar effects. In wet de­ regularly encountered in the inner fj ord region (see also pressions, snowbed communities with hydrophilous Eurola 1968; Virtanen et al. 1997b). Into the direction of mosses, e.g. Scorpidium revolvens, are found. These com­ increasing snow cover, C. tetragona abruptly vanishes, munities are often characterized by Dupontia .fisheri and probably due to a too short snow-free period and/or too Eriophorum scheuchzeri. shallow active layers (cf. Nams & Freedman 1987). In the On the west-southwesterncoast of Spitsbergen (Fig. depression sites, the abundance of vascular plants further 20b ), a somewhat different series of communities is diminishes and the communities become heavily domi- found. A community with relatively abundant Raco-

Acta Phytogeogr. Suec. 82 38 R. Virtanen & S. Eurola

mitrium lanuginosum, the Luzula confusa-Racomitrium In the Dryasregion (Fig. 20c) (Summerhayes & Elton lanuginosum community, is characteristic for stable 1928; Eurola 1968) which largely corresponds to the north­ ridges, whereas on unstable substrates the moss carpet is ern arctic tundra zone (Elvebakk 1985), the exposed ridges fragmented (the Luzula confusa-Gymnomitrion commu­ are characterized by the Papaver dahlianum polar deserts nity, Eurola 1968). These vegetation types grade to and associated less extreme Papaver dahlianum-Raco­ lichen and moss-rich Luzula confusa-Sanionia commu­ mitrium panschii communities. With increasing snow depth nities, while depression sites harbour the Sanionia these show a transition to communities of the Dryas snowbed communities (Kuc 1963; Eurola 1968). This octopetala group, of which the Dryas octopetala­ series is characteristic of southwestern Spitsbergen, but Tomentypnum community from innerfj ord region is also Luzula confusa-Gymnomitrion community is widespread found. These are accompanied by moss tundra communi­ and extends to Dryasre gion, where this type of vegeta­ ties (theAulacomnium turgidum-Alopecurus borealis com­ tion shows a transition to polar deserts. In the Ny Alesund munity, the Aulacomnium turgidum-Hylocomium commu­ area, the northern part of the west coast, the typical nity and the Sanionia-Saxifraga hyperborea community) community series resembles more that of the inner fj ord which correspond to the Luzulion arcticae vegetation region and the Dryas region. As shown by R�nning (Elvebakk 1985). The depressions are occupied by the (1969) and Brossard et al. (1984), ridge communities are Sanionia-Poa alpigena snowbed communities. Similar com­ characterized by Carex rupestris and Dryas octopetala, munities as in our material from the Dryas region are which show a transition to a community with tufts of reported from SE Spitsbergen, e.g. on Barents Island Deschampsia alpina and a cryptogam layer with dark (Hofmann 1968) and in northernmost Spitsbergen (Rein­ bryophytes. deer Peninsula, Dahle 1983).

a)

Sadfragaoppos itifolia-Hyprum revolutum commt.rity

(Dryas octopetaa-CEI'ex rupestris c.) Ridge Dryasoctopetaa-Salix pdaris c.

Depression b)

Luzula coofusa-Gymnomitrion corai Uoides community

Luzulacoofusa-Racom itrium laruginosum c.

Luzula coofusa-SGiliooiac.

c)

Papaver d81�arum pdEI' desert ------Papaverd81Narum-Ra comitrium panschii community

(Dryasoctopetala- Tomertypm1n c.)

Auacannium turgidllll-Hylocomium c.

SGiliona-SaiCifraga t?,tperborea c.

Fig. 20a-c. Generalized community series along ridge-depres­ sion topographic sequences on Spitsbergen: a) the inner fj ord region, b) the west-southwestern coast region, c) the Dryas region.

Acta Phytogeogr. Suec. 82 5 V egetational differentiation in relation to edaphic factors

In northwestern Fennoscandia, a division into types on Northern Fennoscandia differs from Spitsbergen in calcareous soils and oligotrophic types on calcium-poor that on Spitsbergen the whole range of communities in­ soils seems to be clear along the topographic ridge-de­ cludes species that can be regarded as calciphilous in pression gradients. This conforms to earlier studies from northern Fennoscandia. Communities with solely other mountains of Fennoscandia (e.g. Nordhagen 1928; acidophilous species seem to be missing in our material 1943; Kalliola 1939; Gj rerevol1 1956), or the Alps (Gigon from Spitsbergen, and the floristic element confined to 1971) and Alaska (Cooper 1986). Although the podzol acidic soils is rare on Spitsbergen (cf. Table 2). This profile is weakly-developed in the middle oroarctic zone, probably reflects presence of base-rich bedrock on leaching is probably a process contributing to the distinct Spitsbergen, but some other factors, such as omnipres­ division into siliceous and calcareous soils. Precipitation ence of permafrost, a high frequency of cryoperturbation is high; there is no permafrost layer counteracting water as well as low precipitation, counteract leaching and percolation, and the plant cover includes edificator plants, prevents formation of as acidic soils as on mountains of e.g. Betula nana, Cassiope tetragona, and Empetrum northern Fennoscandia. nigrum ssp. hermaphroditum. On siliceous soil parent On Spitsbergen, plants possess edaphic preferences material, these acidophilous plants may decrease base (Elvebakk 1982), but the relationship between climatic exchange capacity and base saturation in the soil, and conditions, soil and vegetation have not been much dis­ exudate compounds promoting soil acidification (e.g. cussed. The present analysis provides some evidence that Lundegardh 1957; Miles 1987). On the contrary, on cal­ the relationship may vary depending on the geographic careous bedrock, supply of cations is continuous enough scale. In the inner fj ord region of Spitsbergen, the valleys to maintain base status and pH values close to the soil receive little precipitation (Hisdal 1976). The precipitation surface. Although the edaphic gradient is mostly distinct, per evaporation ratio is low, and even arid conditions can there are circumstances where this distinctness becomes prevail. Under such conditions, soils especially on well­ weak or disappears. drained ridges are amphipercolative, and the upper soil tend (1) The species composition of the Carex bigelowii-Salix to become enriched by calcium carbonate and the soil will polaris type includes about equally both acidophilous become basic. This is supported by the soil analyses of ( Cassiope hypnoides, Luzula arcuata ssp. confusa, Salix Federoff(1 966). On such ridges, the edaphic tolerances of herbacea) and calciphilous plants (e.g. Salix polaris and many common species may be exceeded, and instead a Silene acaulis) and it seems to represent intermediate rather specialized group of exacting calcitrophic species vegetation between acidophilous and calciphilous ones. It can be found regularly (e.g. Potentilla pulchella). Similar may be that the chemical properties of the underlying soil edaphic processes prevail also on the continental Rocky are intermediate, as a consequence of weak leaching. Mountains (Bamberg & Major 1968). More closed vegeta­ Furthermore, melt water may provide an extra cation tion prevail in the surroundings of the exposed ridges. The addition and wash the humic acids off. One more factor soils are also more acidic (Federoff 1966) especially that may contribute to coexistence of edaphically differ­ Cassiope tetragona and Hylocomium (Rszsnning 1965; entiated species is reindeer grazing. Grazing can decimate Federoff 1966). It is possible that acidification takes place. the cover of ericaceous dwarf shrubs and robust lichens Consequently, edaphic differentiation of vegetation exist in ( Cladina arbuscula ssp. mitis and/or C. stellaris) (see also the inner fj ord region, but the differences may also reflect Manseau et al. 1996). Consequently, space is created for an impact of vegetation on the soil and not only differences calciphilous species that are normally excluded through in soil parent material. competition. In a regional scale, climatic factors can play a signifi­ (2) On polygonal sites where soils of polygon centres cant role. The vegetational series from the coastal region have higher concentrations of extractable plant nutrients (Fig. 20b) indicates the relatively acidophilous nature of and higher pH values than in the surrounding stable ground vegetation (the Luzula confusa-Racomitrum lanuginosum on otherwise siliceous substrates (Rintanen 1970; Jonasson community, for example), although soil substrates in­ & Skold 1983; Jonasson 1986). These polygonal soils clude calcareous ones. Nevertheless, indicators of cal­ may thus provide substrate for plants growing normally cium carbonate tend to be infrequent. One reason may be, on calcareous soils. One example is the occurrence of that the precipitation is relatively high, promoting leach­ Dryasoctopetala in heaths of the Gymnomitrion type. ing of polyvalent cations from upper soil layer. Moreover,

Acta Phytogeogr. Suec. 82 40 R. Virtanen & S. Eurola

the moist climate favours acidophilous moss, Racomitrium towards polar deserts. Along this gradient, cryoperturbation lanuginosum and such lichens as Cetrariella delisei and can be expected to become more intense and the active Cladina arbuscula ssp. mitis. It can be supposed that R. soil layer to become thinner (cf. SHiblein 1971). Moreo­ lanuginosum functions to some extent like Sphagnum ver, precipitation decreases. These factors counteract leach­ causing considerable changes in their local environment ing. Plant cover is sparse and the nutrient demands can be by absorbing available cations. Its ability to form exten­ supposed to be more or less saturated. Cation exchange of sive moss carpets is also a property that can be regarded as plants is slow and it hardly leads to excess of H+ ions and a competitive mechanism that may result in the exclusion soils do not become acidic. Therefore, it can be expected of other mosses and vascular plants. In short, the observed that in the climatically colder areas soil parent material (at least weakly) acidophilous nature of vegetation on the plays a less significant role for plants, and the plants most southwest-west coastal area of Spitsbergen results from frequent on the cold areas can be regarded as circumneutral climatic reasons directly promoting soil leaching and (Sumrnerhayes & Elton 1928; Eurola 1968, 1974). This is indirectly favouring acidophilous plants. also reflected in our data: the species composition in the The third pattern in vegetation-soil relationships re­ Dryas region gives impression of a higher proportion of flects the cooling down of climate from favourable areas calciphilous or neutrophilous mosses and vascular plants.

a)

c:::J Vascular plants � Robust mosses � Other bryophytes fl'll!l Lichens + black crust

GymnT ECtAT JtCtT ShKiT APsT

b)

100

'# 80 (].) C) CO 60

0� u (].) 40 > � 05 20 er:

OocCrT OocCtT SpSacT SoppRsT

c) 100

0 � 80 Fig. 21a-c. Relative coverages (%) of vascu­ Q) O'l CO lar plants, robust mosses, other bryophytes 60 and lichens in generalized community series �0 u along ridge-depression topographic se­ Q) 40 quences in the middle oroarctic zone of north­ -� (i5 western Fennoscandia: 05 20 er: (a) silicaceous substrate; (b) calcareous substrate; (c) eutrophic (slightly calcareous) substrate. FovOocC FovPcrT FovSalpSaC TsSaT See text for further explanation.

Acta Phytogeogr. Suec. 82 6 Abundance patterns of bryophytes in topographic and regional gradients

In terms of general vegetation composition the chiono­ (Aulacomnium, Brachythecium turgidum, Cirriphyllum, phobous and weakly chionophilous heath vegetation of Hylocomium, Orthothecium chryseum,Pleurozium, Raco­ the middle oroarctic zone in northern Fennoscandia is mitrium, Rhytidium, Sanionia, Sphagnum and Tomen­ composed of communities in which the ericaceous and typnum spp.). graminaceous plants are the two major groups of vascu­ (2) all other bryophytes that are different in these lar plants. The cryptogam layer is characterized by a characters (hepatics, e.g. Anastrophyllum, Gymnomitrion, large number of bryophytes and lichens (App. 2 and 3). Lophozia spp. and small mosses, e.g. Dicranum, Disti­ These heaths show a transition to the upper oroarctic chium, Tortula spp.). It seems that in northern Fenno­ vegetation consisting of relatively open Luzula arcuata scandia, most of the communities are dominated by ssp. confusa and Ranunculus glacialis communities (Du vascular plants and by other bryophytes (the second Rietz 1925; Oksanen & Ranta 1992; Oksanen & Virtanen group above) and lichens (Fig. 21). In contrast, on 1995). Communities of ridge and snowbed sites of the Spitsbergen (Fig. 22), robust mosses consistently domi­ middle oroarctic zone are rich in prostrate plants, small nate chionophilous and snowbed sites. Furthermore, moss mosses and hepatics (App. 4). The most extreme dominance increases towards depression sites and from snowbeds are characterized mainly by small mosses and the inner fj ord region towards the coastal and Dryas hepatics (e.g. the Anthelia juratzkana-Polytrichastrum region (Fig. 22). sexangulare type, App. 5). It has been suggested that reduced competition by In the inner fj ord region ofSpitsb ergen, sparsely snow­ vascular plants is one of the causes for the moss abun­ covered ridges are replaced by communities rich in grasses dance in the middle-northern arctic areas (Tallis 1958; and prostrate plants (the Dryasoctopeta la-Carex rupestris Vitt & Pakarinen 1977). Indeed, it is possible that abiotic and open Saxifraga oppositifolia-Hypnum revolutum com­ conditions are favourable to mosses rather than to vascu­ munities). Dwat-f shrub communities, i.e. heaths rich iil lar plants in these areas. Soils are more unstable due to Cassiope tetragona are confined to narrow zones on shel­ solifluction and cryoturbulence, thus roots of vascular tered slopes. Lower parts of hill slopes and depressions plants are broken, and low temperatures due to permafrost are occupied by the moss-rich tundra communities (e.g. reduce root development (Bell & Bliss 1978). Permafrost the Dryasoctopeta la-Tomentypnum community, App. 9). impedes drainage and maintains a high concentration of In the west-southwesterncoastal area, dwarf shrub heaths mineral elements in the soil, which in turn may favour are missing and moss and lichen-rich communities pre­ mosses. However, a copious moss vegetation is found in vail on wind-swept and depression sites. In the Dryas the uplands of the Faeroe Islands and Iceland where there region, a large proportion of the landscape is sparsely is no permafrost (Bocher 1937; Bjamason 1991). 1t can be vegetated and ridge heaths approach polar desert vegeta­ readily noticed that these areas are more oceanic and tion with scattered Papaver dahlianum (App. 8) On shel­ receive high precipitation which contributes to abundant tered sites the moss-rich communities of the Dryas moss vegetation (Du Rietz 1925). However, a copious octopetala group cover a larger proportion of the terrain moss vegetation is not only confined to areas with high and moss tundra communities become prevalent (App. precipitation, as such vegetation is also found in continen­ 10). Both in the coastal and Dryas region, and locally in tal parts of the circumpolar high arctic with remarkably the inner fj ord region, the snowbed sites are occupied by low precipitation (Vitt & Pakarinen 1977; Sumina 1986). mosses forming thick carpets, such as Sanionia (App. 11). As the mountains of northern Fennoscandia receive an The distribution pattern of communitiesoutlined above amount of precipitation which is comparable to oceanic suggests that the plant composition of chionophilous and areas (Waiter & Lieth 1975) and the mountains are often snowbed communities differ distinctly between northern covered by clouds which provide further irrigation in the Fennoscandia and Spitsbergen. One of the main differ­ form of fog, it is surprising that no similar copious moss ences concerns the abundance of bryophytes. This is communities are commonly found. Actually, such veg­ shown in the Figs. 14 and 15 where relative abundances etation is not totally missing from Fennoscandia. In the of: upper oroarctic habitats, patches of thick moss carpets (1) robust mosses, building thick carpets by means of occur as isolated oases in sterile boulder fields (e.g. on the vegetative growth, are loosely attached to the ground and upper slope of Skuvgilrassa in interior Finnmark, Oksanen are susceptible to trampling or other physical disturbance & Virtanen 1995) and at the highest altitudes on

Acta Phytogeogr. Suec. 82 42 R. Virtanen & S. Eurola

Fennoscandian mountains (Vestergren 1902; Du Rietz creates space for small hepatics and mosses and prostrate 1925). Consequently, mere physical constraints do not vascular plants. A reverse change in vegetation cover has seem to provide a sufficient explanation for the absence of taken place as a consequence of experimental exclusion moss banks below the altitudinal limit of continuous of grazing on a snowbed (Virtanen et al. 1997a; see also vegetation in northwestern Fennoscandia. It has been Batzli et al. 1980): the plant cover has shown signs of suggested that one cause for that is the Norwegian lem­ succession towards moss dominance as in communities ming (Oksanen 1988; Lundberg et al. manuscr.). The encountered on lemming-free arctic islands (Virtanen et Norwegian lemming is able to deplete the moss vegeta­ al. 1997b). Thus, existence of copious moss vegetation in tion quite efficiently from snowbed habitats (e.g. Kalela conditions comparable to middle ( oro)arctic zones may 1961; Moen et al. 1993). Depletion of moss vegetation also depend on the absence of moss-eating lemmings.

a)

c::J Vascular plants FrA Robust mosses FrA Other bryophytes FrA Lichens + black crust

Sopp-irC OocSpC DoeSaC b) 100

80 � a; 60 > 0 (,) � 40 � � 20

LcRIC LeSaC SaC

c) 100

80

a; 60 > 0 (,) -� 40 -ro Fig. 22a-c. Relative cover (%) of vascular plants, robust mosses, � 20 other bryophytes and lichens in generalized community series along ridge-depression topographic sequences on Spitsbergen: a) inner fj ord region; b) coastal region; c) Dryasregion. See text P�pC AtHC SaPalpC for furtherexplanation.

Acta Phytogeogr. Suec. 82 7 Acknowledgements

We thank A. Hakala for help with the field work on Spitsbergen and L. Oksanen for reading an earlier version of the manuscript. We also thank A. Elvebakk and an anonymous referee for comments. The study was fm ancially supported by the Research Council for Environment and Natural Resources of Finland and the University of Oulu.

8 References

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Acta Phytogeogr. Suec. 82 Middle oroarctic vegetation in Finland and middle-northern arctic vegetation on Svalbard 47

Appendix 1. Mean percentage cover of plants in community types of the Festuca ovina-Potentilla crantzii group. l - Festuca ovina-Dryas octopetala community, 2-Festuca ovina-Potentilla crantzii type, 3-Festuca ovina-Dryas octopetala-Hylocomium community, 4- Festuca ovina-Saussurea alpina-Sanionia community, 5- ]uncus trifidus-Cassiope tetragona type, mossy variant. The frequenciesof the taxa are indicated as fo llows: bold, f>66.7, underlined, 33.3

2 3 4 5 2 3 4 5

Alchemilla sp. 0.9 2.9 Andreaea rupestris 0.3 0.9 Antennaria alpina 0.3 0.2 0.3 Bartramia ithyphylla 0.3 0.3

Antennaria canescens 0. 1 0.3 Dicranoweisia crispula 0. 1 0.2 Anthoxanthum odoratum 0. 1 1.8 0.2 6.0 Dicranum fu scescens u 0.4 Arabis alpina 0.4 0.5 Dicranum scoparium 0. 1 0.3 0.8 11.2 Bartsia alpina 0. 1 0.2 Distichium capillaceum 0.2 0.3 Bistorta vivipara li 4.6 6.6 1.3 2.8 Hylocomium splendens var. a/ask. 2.0 26.6 .!L2. 13.2 Calamagrostis lapponica 0.5 2.9 Mnium blyttii 0.2 0.4 0.3

Carex bigelowii 1.0 4.5 12.0 Pleurozium schreberi 0.2

Carex rupestris 2.8 3.0 0.3 Pohlia cruda 0.6 0.3 0.3 Carex vaginata 0. 1 6.4 0.4 0.3 Pohlia spp. 0. 1 0.4 0.3 Cassiope tetragona 0. 1 0.4 0.4 15.5 Polytrichastrum alpinum 0.4 7.2 1.5 1.3 0.9 Cerastium alpinum 1.8 0.6 11.7 Polytrichumjuniperinum 0. 1 1.8

Draba daurica 0.4 Rhytidium rugosum 0.3 0.3 Dryas octopetala 19.7 3.9 9.3 Sanionia uncinata 6.8 2.2 Empetrum nigrum ssp. hermaphr. 0.9 5.8 Schistidium sp. 0. 1 0.3 Euphrasia fr igida 0.4 0.3 Festuca ovina 15.4 30.0 24.8 12.0 11.1 Anastrophyllum minutum Hieracium alpinum 0.3 0.5 0.3 Barbilophozia floe rkei 0.3 0.2

Linnaea borealis 1.8 10.3 0.4 4.4 Barbilophozia hatcheri 0.3 0.2

Luzula multiflora ssp. fr igida 0.5 0.2 Gymnomitrion concinnatum 2.5 Luzula spicata 0.3 0.4 Tritomaria quinquedentata 0.2 0.9 Oxyria digyna 0.3 0.3 Phyllodoce caerulea 1.8 9.3 Alectoria ochroleuca 0. 1 0.3 Poa alpina 2.3 0.3 Cetraria ericetorum l.J. 1.3 0.8 5.1 Potentilla crantzii lA 2.5 u 2.9 Cetraria islandica 0.3 0.3 1.3 Rhodiola rosea 0.0 0.2 Cladina arbuscula s p. mitis 0.5 0.5 0.2 0.4 0.6 Salix hastata 0.3 2.,_Q Cladina rangiferina 0. 1 0.6 Salix polaris 1.8 0.8 9.3 3.4 Cladonia chlorophaea 0.3 0.3 Salix reticulata 1.0 0.3 3.2 0.4 Cladonia gracilis 0. 1 1.3 Saussurea alpina 0. 1 0.4 3.8 0.3 Cladonia pocillum 0.4 0.3 0.3 Saxifraga cernua lA Cladonia pyxidata 0. 1 0.2 0.3 Saxifraga cespitosa 0.4 0.3 Cladonia uncia/is 0.6 Saxifraga nivalis 0.4 0.6 Flavocetraria cucullata 0.6 1.3 1.0 0.9 Saxifraga oppositifolia 0.3 0.3 Flavocetraria nivalis 1.1 0.2 0.6

Selaginella selaginoides 0.4 Peltigera malacea 0. 1 0.3

Silene acaulis 2.8 3.5 0.2 6.7 Stereocaulon alpinum 0. 1 0.2 0.3

Solidago virgaurea 1.1 2.3 1.5 0.3 Th amnolia vermicularis 0.3 0.3 Thalictrum alpinum 1.9 2.0 .Ll Trisetum spicatum 0. 1 0.3

Vaccinium uliginosum 0.3 4.7 Total 90.7 187.0 180.3 129.9 134. 1 Vaccinium vitis-idaea l.J. 4.0 9.1 8.8 Viola biflora 2.6 2.5 6.4 23.8 2.8

Additional species, occurring only in one cluster with a low frequency.

1:Antennar ia dioica (1.9), Campanula rotundifolia (0.4), Deschampsiaflexuosa ( 1.8), Geranium sylvaticum (0. 1 ), Juniperus communis (3.5), Lychnis alpina (0. 1),

Minuartia biflora (0. 1), Veronica fru ticans (0.4), Abietinella abietina (0. 1), Bryum argenteum (0. 1), Lescurea saxicola (0. 1), Pseudoleskeella tectorum (0. 1),

Saelania glaucescens (0. 1), To rtula norvegica (0. 1), Preissia quadrata (0. 1), Ptilidium ciliare (0. 1), Alectoria nigricans (0.9), Bryocaulon divergens (0. 1),

Hypogymnia physodes (0. 1), Ochrolechiafrigida (2. 1), Sp haerophorus globosus (0. 1)

2: Equisetum variegatum (0.3), Erigeron uniflorus (0.3), Solorina crocea (0.3)

3: Arctostaphylos alpina (3.0), Astragalus alpinus (3.0), Nephroma expallidum (0.2)

4: Cladonia ecmocyna (0.4)

5: }uncus trifidus (2.2), Salix herbacea (17.8), Cladina stellaris (0.3), Solorina saccata (0.3)

Acta Phytogeogr. Suec. 82 48 R. Virtanen & S. Eurola

Appendix 2. Mean percentage cover of plants in community types of the Alectoria group. 1 - Dryasoctopetala- Carex rupestris type, 2,3

- Empetrum-Cassiope tetragona-Alectoria type, 4 - Gymnomitrion type. For frequencies, see Appendix 1.

2 3 4 2 3 4

Betula nana 4.0 6.4 Gymnomitrion concinnatum 5.5 0.7 Calamagrostis lapponica <0. 1 0.2 Gymnomitrion corallioides 0.2 2.4 22.0 Carex rupestris 5.9 Hepaticae indet. 0.2 0.5 Cassiope tetragona .LQ 22.5 .LQ 0.7 Lophozia spp. 0.5 0.7 Dryas octopetala 32.4 0.4 Ptilidium ciliare 0.2 0.7 Empetrum nigrum ssp. hermaphr. 1.1 8.8 7.9 Tetralophozia setiformis 0. 1 3.0 <0. 1 Festuca ovina 9.7 <0. 1 0.2 Hieracium alpinum s. !at. 0.2 Alectoria nigricans 1.5 0.6 1.7 1.3 Huperzia se/ago 0. 1 <0. 1 A tectoria ochroleuca 0.6 0.3 0.6 1.3 Luzula arcuata ssp. confusa 0. 1 .LQ 0.9 Bryocaulon divergens 0.8 0.7 2.3 Luzula spicata 0. 1 Q,1 Cetraria aculeata 0. 1 Q,1 Salix herbacea 0.9 1.4 Cetraria ericetorum 1.4 0. 1 0.6 1.3 Salix polaris 1.2 L8 Cetraria islandica 0.2 u Saxifraga oppositifolia OA Cetraria islandica ssp. crispiformis 0.2 0.4 Silene acaulis 0� <0. 1 Cetraria nigricans Q,1 0.3 0.5 0.5 Vaccinium vitis-idaea 1.8 0.4 3.6 Cetrariella delisei <0. 1 Q,1 Cladina arbuscula ssp. mitis 0.5 0.6 0.5 Dicranum elongatum 0.5 2.8 Cladina rangiferina 0.2 0.5 Q,1 0.2 Die ranum fuscescens 0. 1 1.3 li Cladina stygia 0.3 0.4 Dicranum scoparium 0.2 <0. 1 2.9 Cladonia amaurocraea <0. 1 0. 1 Q,1 Dicranum sp. 0,1 0.4 Cladonia cervicornis <0.1 0.2

Ditrichum jlexicaule 0,1 Cladonia chlorophaea 0.2 0.7 Pogonatum dentatum 0.2 Q,1 Cladonia coccifera <0. 1 Q,1 0.3 0.9 Pogonatum urnigerum Q,1 Cladonia gracilis 0.3 0.2 1.1 Pohlia spp. 0,2 0.3 Q,1 0.7 Cladonia pocillum 0.5 Polytrichastrum alpinum 0. 1 Q,1 Cladonia uncia/is 0. 1 Q,1 0.9 Polytrichastrum sexangulare Q,1 Crustaceous black 5.5 Polytrichum hyperboreum Q,1 Crustaceous lichens 2.J. Polytrichum juniperinum <0. 1 0.6 0.5 Flavocetraria cucullata 1.0 0.3 1.2 1.1 Polytrichum piliferum 0.2 0.5 2.0 Flavocetraria nivalis 3.7 10.0 10.3 1.3 Polytrichum sp. 0.2 0.4 Ochrolechia fr igida 2.9 3.0 8.0 5.9 Racomitrium lanuginosum 0.5 2.6 <0. 1 0.7 Pertusaria sp. 1.3 Rhytidium rugosum O,Q Psoroma hypnorum 0. 1 0.2 Tortella fragilis 0,1 Solorina crocea Q,1 0.5 Sp haerophorus fragilis 0.1 0.2 Anastrophyllum minutum Q,1 0.2 0.5 Sp haerophorus globosus 1.0 0.5 1.5 3.4 Barbilophozia spp. 0. 1 0.7 Stereocaulon alpinum 0.3 <0. 1 0.2 Cephalozia sp. 0. 1 <0. 1 0.2 Thamnolia vermicularis 0.3 0.3 1.3 Diplophyllum taxifolium 0. 1 <0. 1 0.2

Gymnomitrion apiculatum 0.5 0.2 0.2 Total 85.6 60.5 53.7 92.5

Additional species, occurring only in one cluster with a low frequency. 1: Antennaria alpina (0.2), Carex glacialis (0.3), Cerastium alpinum (0.2), Festuca vivipara (0.2), Juniperus communis (4.4), Salix hastata(1 .3), Saxifraga nivalis (0.3), Vaccinium uliginosum (0.2), Aulacomnium turgidum (0. 1), Bartramia ithyphylla (0.2), Cnestrum schisti (0.2), Distichium capillaceum (<0. 1), Encalypta alpina (0.2), Hylocomium splendens var. alaskanum (0.2), Hypnum bambergeri (0.2), Hypnum revolutum (0. 1), Mnium marginatum (0.2), Plagiobryum zieri (0.2), Plagiothecium sp. (0.2), Pleurozium schreberi (0.2), Racomitrium canescens (0.2), Saelania glaucescens (0.2), Timmia austriaca (0.2), Tortella tortuosa ( <0. 1), Barbilophozia hatcheri (0.2), Cladonia pyxidata (0.3), Peltigera apthosa (0.2), Solorina saccata (0.2)

2: Pedicularis lapponica ( <0. 1), Phyllodoce caerulea ( <0. 1), Bistorta vivipara ( <0. 1), Pohlia nutans ( <0. 1)

4:Ar ctostaphylos alpina (0.4), Trisetum spicatum (0.2), Dicranoweisia crispula (0.4), Hypogymnia bitteri (0.7), Parmelia omphalodes (0.2), Stereocaulon sp. (0.2)

Acta Phytogeogr. Suec. 82 Middle oroarctic vegetation in Finland and middle-northern arctic vegetation on Svalbard 49

Appendix 3. Mean percentage cover of plants in community types of the ]uncus trifidus-Cassiope tetragona group. 1,3 - Empetrum-

Cassiope tetragona type, 2 - Empetrum-Flavocetraria nivalis type, 4-8 - ]uncus trifidus-Cassiope tetragona type, 4 - Carex bigelowii variant, 5,6 - typical variants, 7-graminoid variant, 8-Polytrichum hyperboreum variant. For frequencies, see Appendix 1.

2 4 6 7

Antennaria alpina . 0.2 M Antennaria canescens 0.1 0.7 Anthoxanthum odoratum u Betula nana 21.7 u 0.2 0.3 Bistorta vivipara 0.4 0.4 0.6 Q2 M 0. 1 Calamagrostis lapponica 1.1 0.3 u M 0.3 0.3 Carex bigelowii 0.4 3.9 2.2 7.9 M 2.5 0.6 b.Q Carex vaginata 0. 1 <0. 1 0.2 Cassiope hypnoides 0.2 0.3 0.4 .LQ Cassiope tetragona 21.4 7.2 18.2 1.4,2 0.2 0.9 <0. 1 6.6 Empetrum nigrum sp. hermaphroditum 0. 1 6.6 42.0 11.7 1.1 0.5 Festuca ovina 3.1 0.4 0.5 L2 7.0 11.2 6.9 0.2 Gnaphalium supinum 0.2 Hierochloe alpina 0. 1 <0. 1 <0. 1 0.2 .LQ 0.3 <0. 1 Huperzia se/ago Q2 0.3 <0. 1 }uncus trifidus <0. 1 u lU 21.3 0.3 9.8 6.0 Luzula arcuata ssp. confusa 0.3 M 1.1 M M Luzula spicata 0.4 <0. 1 Pedicularis Lapponica 0.2 0.4 Phyllodoce caerulea 0.9 1.5 0.2 0.3 ,(U Salix herbacea 5.5 kQ .LQ L2 16.2 15.8 3.0 2.5 Sibbaldia procumbens 0.2 0.3 <0. 1 Solidago virgaurea 0.2 !U 0.3 Trisetum spicatum 0. 1 .u <0. 1 Vaccinium vitis-idaea 7.2 7.2 3.2 3.8 1.9 3.1 1.1 1.0

Andreaea rupestris .l.2 .LQ <0. 1 0.2 0.2 M 0.3 Aulacomnium turgidum 0. 1 Q2 Conostomum tetragonum 0.3 0.3 0.2 0.3 M <0.1 Dicranoweisia crispula 1.1 0.2 0.2 Dicranum elongatum 0.2 0.3 1.1 u Dicranum juscescens 0. 1 M 0.3 16.5 8.9 u 0.3 <0. 1 Dicranum majus 0. 1 0.2 0.3 Dicranum scoparium 1.1 2.3 !1.2 1.1 0.5 Dicranum sp. lA 2.8 0.2 2.2 0.3 Hylocomium splendens var.alaskanum 5.9 0.2 1.0 0.4 0. 1 Kiaeria starkei 0.9 2.8 0.3 M <0. 1 Pogonatum dentatum 1.1 0.2 <0. 1 Pohlia spp. !U M 0.2 0.4 M M M <0. 1 Polytrichastrum alpinum !U 1.5 fU 4.5 <0. 1 Polytrichum commune 0.2 0.2 0.2 Polytrichum hyperboreum 0. 1 4.6 Polytrichum juniperinum !U M !!.2 0.8 kQ 4.8 <0.1 <0. 1 Polytrichum piliferum 2. 1 3.9 <0. 1 � 0.3 5.0 0.5 Polytrichum sp. u 0.2 0.2 0.2 Racomitrium Lanuginosum 0.3 4.7 4.1 0.4 0.3 0.3 Sanionia uncinata 0.5 0.2

Anastrophyllum minutum 2.4 M 0.4 2.1 1.3 M Anthelia juratzkana 0. 1 0.3 0.2 Barbilophozia jloerkei 0. 1 <0. 1 u <0. 1 Barbilophozia hatcheri 0.4 !U 0.3 Barbilophozia kunzeana 0.1 0.3 0.2 0.3 Barbilophozia quadriloba 0.3 M 0.2 0.2 Barbilophozia sp. 0. 1 0.2 0.2 0.4 0.3 Blepharostoma trichophyllum 0.3 0.2 0.2 0.2 0.6 Cephalozia spp. Q2 0.2 0.9 <0. 1 Diplophyllum taxifolium 2.2 0.3 0.3 Gymnomitrion concinnatum 0.3 2.8 2.2 0. 1

Acta Phytogeogr. Suec. 82 50 R. Virtanen & S. Eurola

App. 3, continued. 2 4 6 7 8

Gymnomitrion corallioides 0.4 .L1 0.2 Lophozia spp. (12_ 0.5 0.4 0.4 0.9 2.2 0.3 <0. 1 Ptilidium ciliare 0. 1 0.3 u .L.2 13.9 0.3 Tritomaria quinquedentata 0.9 0.2 0.2 0.3

Alectoria nigricans 0.3 0.8 <0. 1 0.2 0.3 M Alectoria ochroleuca 0. 1 0.8 0.2 0.4 0.2 Bryocaulon divergens 0.3 Q2 <0. 1 0.2 Cetraria ericetorum 1.6 1.7 2.1 2.3 12.6 3. 1 M 5.2 Cetraria islandica 0.4 <0. 1 0.2 Cetraria islandica ssp. crispiformis Q2 Q2 1.9 0.9 1.& :i,2 Cetraria nigricans 0.9 0.2 M 0.2 0.2 Cetrariella delisei 0.4 0.4 0.2 0.2 0.6 M 3.8 Cladina arbuscula ssp. mitis 1.9 .u 0.7 2.1 1.1 0.6 u 0.4 Cladina rangiferina .3.,2 0.2 0.3 0.3 Cladina stygia M 0.3 0.2 0.2 Cladonia amaurocraea 0.8 0.3 0.2 0.4 M <0. 1 <0. 1 Cladonia bellidiflora 0.2 (12_ <0. 1 !U Cladonia coccifera 0.9 Q]_ 0.4 1.0 1.1 1.3 0.4 0.3 Cladonia crispata 1.9 0.4 0.3 Cladonia gracilis 2.0 1.2 0.9 2.3 2.2 0.6 0.3 0.3 Cladonia macrophylla 0.4 0.2 Q2 0.3 Cladonia merochlorophaea 0.1 0.2 0.2 0.3 0.3 Cladonia pyxidata 0.3 <0. 1 0.2 0.2 <0. 1 Cladonia squamosa 0.3 0.2 0.2 0.3 Cladonia subfurcata 0.4 0.2 0.2 M 0.3 0.2 Cladonia sulphurina 0. 1 0.2 0.2 !U Cladonia uncialis 1.1 1.0 0.8 0.8 1.1 0.9 0.4 QJ. Flavocetraria cucullata 1.6 1.2 4.4 1.0 0.3 0.6 0.3 <0. 1 Flavocetraria nivalis 0.4 3.4 0.5 0.4 Q2 0.3 0.7 Melanelia hepatizon Q...2 Q2 0.4 0.2 0.6 M Nephroma arcticum 0. 1 0.2 M 1.& 2.5 Ochrolechia frigida 1.0 .L.Q 1.3 3.9 5.3 M 25.4 Pertusaria spp. 0. 1 lA 0.2 0.3 Solorina crocea 1.1 1,2 0.2 0.3 Sphaerophorus globosus 0.4 1.1 0.9 0.8 0.2 0.3 <0. 1 Stereocaulon alpinum 0.1 0.3 0.4 4.7 ti 0.4 <0. 1 Stereocaulon paschale 4.5 <0. 1 0.2 0.3 Stereocaulon spp. 0.3 Q2 1.5 0.3 <0. 1 Thamnolia vermicularis 0.4 Q2 0.5 0.8 M 0.3 !U

Total 113.9 119.6 108.7 122.7 115.3 98.4 50.6 73.9

Additional species, occurring only in one or two clusters with a low frequency. I: Cardamine bellidifolia (0. 1 ), Dryasoctopetala (0. 1), Festuca vi vipara (0. 1 ), Linnaea borealis ( 1.9), Oxyria digyna (0. 1 ), Salix hastata ( 1.9), Salix polaris (0.9), Saussurea alpina (0.3), Saxifraga tenuis (0.3), Vaccinium myrtillus (0. 1), Viola biflora (0.4), Bartramia ithyphylla (0.4), Pogonatum umigerum ( 1.8), Polytrichastrum sexangulare (0. 1), Scapania sp. (0. 1 ), Sphagnum girgensohnii (7 .1), Cladina stellaris ( 1.9), Cladonia ecmocyna (0. 1 ), Cladonia pocillum (0.3), Peltigera scabrosa (0. 1)

2: Rubus chamaemorus (0.2), Racomitrium microcarpon (0.2), Scapania sp. (0.2), Cladoniafimbriata (0.2), Nephroma expallidum (0.2), Peltigera apthosa (0.2)

3: Dryasoctopetala (0.9), Linnaea borealis (0.2), Vaccinium uliginosum ( 1.1 ), Pleurozium schreberi (0.2), Sphagnum girgensohnii (3.0), Cetraria aculeata ( <0. 1 ), Nephroma expallidum ( <0. 1 ), Peltigera apthosa (0.2), Psoroma hypnorum ( <0. 1)

4: Festuca vivipara (0.2), Oxyria digyna (0.4), Pleurozium schreberi (0.3), Rubus chamaemorus (0.2), Salix polaris (5.8), Trientalis europaea (0.2)

5: Pyrola minor (0.2), Trientalis europaea (0.2), Vaccinium myrtillus (0.2), Polytrichastrum sexangulare (0.2), Racomitrium microcarpon (0.2), Peltigera scabrosa (0.2)

6: Cardamine bellidifolia (0.3), Lycopodium clavatum (0.3), Ceratodon purpureus (0.3)

7: Agrostis mertensii (0.3), Erigeron uniflorus( <0. 1), Minuartia biflora ( <0. 1 ), Silene acaulis (0.8), Cladonia defo rmis ( <0. 1 ), Cladoniafimbriata ( <0.1), Peltigera rufescens ( <0. 1 ), Psoroma hypnorum ( <0. 1)

8: Silene acaulis (0.6), Vaccinium uliginosum ( <0. 1), Cetraria aculeata ( <0. 1), Cladonia defo rm is ( <0. 1 ), Cladonia fimbriata ( <0. 1 ), crustaceous black (4.3)

Acta Phytogeogr. Suec. 82 Middle oroarctic vegetation in Finland and middle-northern arctic vegetation on Svalbard 51

Appendix 4. Mean percentage cover of plants in communitytypes of the Salix herbacea group. 1 - Salix herbacea-Kiaeria type, 2-Salix herbacea-Cassiope hypnoides type, 3-Salix herbacea-Kiaeria type, Carex bigelowii variant, 4-Carex bigelowii type, 5,6 - Cassiope hypnoides-Juncus trifidus type, 7 - Carex bigelowii-Salix polaris type, 8 - ]uncus trifidus-Cassiope tetragona type, Cetrariella delisei variant, 9 - Trisetum sp icatum-Sanionia type. For frequencies, see Appendix 1.

2 4 6 7 8 9

Agrosris mertensii 0. 1 0.5 Antennaria alpina !U 0.3 Anthoxanthum odoratum 2.2 0.6 <0. 1 <0. 1 <0.1 Bistorta vivipara 1.2 0.9 1.1 0.2 1.8 7.4 Cardamine bellidifolia 0.4 0. 1 <0. 1 Carex bigelowii 6.5 18.2 22.9 13.4 5.2 D 8.5 0.5 2.0 Carex lachenalii <0. 1 0.3 <0.1 !U 9.2 Cassiope hypnoides 7.8 0.5 8.4 1.8 19.5 6.6 2.0 Cassiope tetragona 0. 1 0.4 0.2 0.2 !U 27.5 Deschampsia flexuosa 0.9 <0. 1 0. 1 Diphasiastrum alpinum 0. 1 0.6 <0.1 <0. 1 2.0 Erigeron uniflorus <0. 1 0.5 0.2 Festuca ovina 0.3 0.9 1.8 <0. 1 4.2 4.8 Gnaphalium supinum 1.2 0.3 1.0 0. 1 0.4 !U 0. 1 Hieracium sp. <0. 1 <0. 1 0.3 Huperzia selago <0. 1 <0. 1 !U 0. 1 }uncus biglumis 0. 1 <0. 1 <0. 1 <0. 1 }uncus trifidus 0. 1 0.5 6.,2 0.7 5.0 Luzula arcuata ssp. confusa 0. 1 0.3 2.3 7.1 0.4 1.0 Luzula spicata 0. 1 1.0 <0. 1 0.2 Oxyria digyna 1.8 0.3 <0. 1 Phyllodoce caerulea <0. 1 0. 1 <0.1 <0. 1 <0. 1 Poa alpina <0. 1 <0. 1 1.1 Potentilla crantzii <0. 1 0.5 0.3 Ranunculus acris !U 3.7 Ranunculus glacialis 0.3 Ranunculus nivalis 0. 1 <0. 1 <0. 1 2.2 Rhodiola rosea <0. 1 <0. 1 <0.1 0.3 0.3 Salix herbacea 28.0 13.8 29.2 2.8 0.9 1.9 8.2 1.0 2.0 Salix polaris 0. 1 l.l <0. 1 0.4 2.5 0.6 Salix sp. Saussurea alpina 0.3 <0. 1 <0. I Sibbaldia procumbens 12.1 1.5 0.3 0.4 0.3 0.5 1.4 Silene acaulis 0.2 0.7 1.5 !U Taraxacum sp. <0. 1 <0. 1 0.2 Trisetum spicatum <0. 1 0. 1 0. 1 1.1 Va ccinium vitis-idaea 0.3 0.4 0.5 2.6 <0. 1 Vahlodea atropurpurea Q.j_ 0. 1 Veronica alpina <0. 1 <0. 1 <0. 1 Viola bijlora <0. 1

Andreaea rupestris 0.3 2.0 <0. 1 0.3 Bryum sp. 0. 1 0.5 Conostomum tetragonum 3.3 0.9 u <0. 1 <0. 1 Dicranoweisia crispula <0. 1 0.4 Die ranum fuscescens 1.9 7.3 0.2 0.3 1.0 Dicranum scoparium 0.3 0.4 <0. 1 1.0 M 0.5 u Hylocomium splendens var. alaskanum 0. 1 <0. 1 <0. 1 0.6 Kiaeria starkei 26.2 0. 1 <0. 1 0.2 <0. 1 Mnium blyttii <0. 1 M Oligotrichum hercynicum <0. 1 <0. 1 0.3 0.2 Pogonatum dentatum 2. 1 <0. 1 <0. 1 Pogonatum urnigerum <0. 1 0.3 0. 1 0.3 Pohlia cruda 0. 1 <0. 1 0.1 1.8 Pohlia spp. 0.7 0.8 1.1 0.7 0.4 0.5 0.2 0.8 Polytrichastrum alpinum 0.3 1.8 0.3 1.0 0.2 3.3 Polytrichastrum sexangulare 4.2 u 0.3 <0. 1 0. 1 <0. 1 <0. 1 0.7 Polytrichum commune 1.8 0.3 <0. 1 0.5 Polytrichum hyperboreum <0. 1 0.2 0. 1 Polytrichum juniperinum 0.3 ti 0.5 2.4 0.6 Polytrichum piliferurn 5.4 <0. 1 0.5 0.3 Polytrichum sp. 4.6 0.3 0.2

Acta Phytogeogr. Suec. 82 52 R. Virtanen & S. Eurola

App. 4, continued.

2 3 4 6 7 8 9

Racomitrium microcarpon Q,2 <0.1 <0. 1 Sanionia uncinata 0.8 0.3 0.3 <0. 1 M 15.3

Anastrophyllum minutum 0.9 u J.,2 0.4 M 0. 1 {U Anthelia juratzknna J.,2 !1..8 4.6 4.9 <0. 1 0.3 Barbilophozia floerkei 8.9 0. 1 <0. 1 <0. 1 0. 1 2.& Barbilophozia hatcheri 0. 1 0.3 <0. 1 QJ. Blepharostoma trichophyllum 0.3 0.3 Q.j_ 0.2 <0. 1 Cephalozia spp. Q,2 0. 1 {U 0.4 1.1 0. 1 <0. 1 0.2 Cephaloziella sp. <0. 1 0.3 <0. 1 Diplophyllum taxifolium 0.3 0.3 0. 1 <0. 1 0.3 Gymnomitrion apiculatum 0. 1 <0.1 0. 1 Gymnomitrion concinnatum 2.0 Q,2 3.5 5.5 25.0 11.1 0.4 0.5 <0. 1 Lophozia sudetica 0.2 0.3 u 2.0 <0. 1 Lophozia wentzelii 0.3 0.2 Lophozia spp. 5.5 2.3 J.& Q,2 0.2 Marsupella brevissima 0. 1 2.2 0.6 <0. 1 Marsupella condensata 0.5 !1..8 Pleurocladula albescens 0.5 0.9 1.0 1.9 0.3 Ptilidium ciliare 0. 1 0.3 0.3 <0. 1 Tritomaria quinquedencata 0.3 <0. 1 0.4 0.2

Cetraria ericetorum 0.3 12 {U u D 2.7 0.5 Cetraria islandica 0. 1 <0. 1 u 0.3 2.5 u Cetraria islandica ssp. crispiformis 0.8 2.6 0.3 0.7 Q,2 .u Q,2 Cetrariella delisei 0.3 0.5 2.3 4.3 1.0 8.2 3.2 20.0 <0.1 Cladina arbuscula ssp. mitis 0.7 0.8 0.9 1.5 2.0 <0. 1 12.8 1.6 .L.Q Cladonia bellidifolia 0.4 0.6 0.2 <0. 1 <0. 1 Cladonia coccifera 1.0 0.8 0.5 0.4 !1..8 0.2 0.3 QJ. C/adonia ecmocyna 0.3 0.3 Q2 <0. 1 Q2 0.3 0.2 Cladonia gracilis 0.5 1.0 M 0.7 0.3 <0. 1 M 0.3 QJ. Cladonia macrophylla <0. 1 <0. 1 0.3 Cladonia pocillum 0.3 <0. 1 0.3 0.2 0.3 0. 1 Cladonia pyxidata 0.3 <0. 1 <0.1 0.3 Cladonia subfurcata Q,1 0.3 0.3 0.2 0.2 <0. 1 Cladonia uncia/is <0. 1 0.9 M 0.2 0.8 1.1 0.3 0.6 Crustaceous black 0.6 2.5 2..8 2J1 fL:1 Crustaceous lichens 0.2 1.7 .u u Ochrolechia frigida ll Q,1 3.4 3.6 13.2 11.9 16.5 D Pertusaria dactylina 0.3 <0.1 <0. 1 0. 1 <0. 1 Solorina crocea QJ. 0.3 QJ. Q,1 QJ. Stereocaulon alpinum 0.3 Q,2 0.2 QJ. 0.3 0. 1 0.8 Stereocaulon pp. Q,1 M M 0.2 0.2 <0. 1

Total 134.7 91.3 106.0 74.6 76.6 95.6 86.4 92.1 87.0

Additional species, occurring only in one or two clusters with a low frequency. I: Luzula multiflora ssp. frigida (0.3), Poa alpigena ( <0. 1 ), Diphysciumfoliosum (0.2), Moerchia blyttii ( <0. 1) 2: Calamagrostis Lapponica (0.9), Carex vaginata (0. 1), Vaccinium myrtillus (0. 1), Dicranum elongatum (2.7), C/adonia crispata (0. 1), Cladonia turgida (0. 1), Peltigera scabrosa (0.2), Stereocaulon paschale (0.9)

3: Calamagrostis lapponica (0.3), Diphysciumfoliosum (0. 1), Melanelia hepatizon (1.8), Peltigera scabrosa (0.3)

4: Antennaria canescens (0.1 ), Diapensia lapponica (0. 1 ), Racomitrium lanuginosum (0.1), Sphagnum fimbriatum (0. 1 ), Thamnolia vermicularis (0. 1)

5: Erigeron humilis (0. 1 ), Pohlia drummondii ( <0. 1 ), Cladonia cervicornis (<0. 1 ), Cladonia deformis (0. 1), Flavocetraria nivalis ( <0. 1)

6: Racomitrium lanuginosum ( 1.0), Sphagnum fimbriatum (0.1 ), Cladonia cervicornis (0. 1 ), Flavocetraria nivalis ( <0. 1)

7: Antennaria canescens (<0. 1), Antennaria porsildii (<0. 1), Cerastium arcticum (<0. 1), Erigeron humilis (<0. 1), Minuartia biflora (<0. 1), Poa alpigena (<0. 1), Thalictrum alpinum ( <0. 1 ), Bartramia ithyphylla ( <0. 1 ), Distichium capillaceum ( <0.1 ), Pohlia drummondii ( <0.1 ), Cladina rangiferina ( <0.1 ), Cladonia deformis ( <0. 1 ), Cladonia fimbriata (<0. 1), Flavocetraria cucullata (0. 1), Melanelia hepatizon (<0. 1), Nephroma expallidum (<0. 1)

8:Ant ennaria lanata (0.5), Cerastium arctic urn (0.5), Empetrum nigrum ssp. hermaphroditum (0. 1 ), Thamnolia vermicularis (0. 1)

9: Carex vaginata (0. 1 ), Cerastium cerastoides ( <0. 1 ), Erigeronhumilis (0. 1 ), Minuartia biflora (0. 1 ), Aulacomnium turgidum (0.3), Bartramia ithyphylla (0.3), Hylocomiastrum pyrenaicum (0.3), Nephroma expallidum (0.6), Peltigera leucophlebia (0.6), Peltigera malacea (0.3), Peltigera rufescens ( <0. 1)

Acta Phytogeogr. Suec. 82 Middle oroarctic vegetation in Finland and middle-northern arctic vegetation on Svalbard 53

Appendix 5. Mean percentage cover of plants in community types of the Ranunculus glacialis group. 1 - Anthelia-Polytrichastrum sexangulare type, 2-Koenigia islandica-Phippsia algida community. For frequencies, see Appendix 1.

2 2

Cardamine bellidifo lia !U Philonotis sp. 2.5 Carex bigelowii 0. 1 0. 1 Pohlia drummondii QJ. Carex lachenalii !U 0. 1 Pohlia spp. .Q2 1.8 Cassiope hypnoides 1.4 Polytrichastrum alpinum 0.2 0.3 Cerastium arcticum <0. 1 Polytrichastrum sexangulare 7.9 Cerastium cerastoides 1.8 Sanionia nivalis 4.0 Ep ilobium anagallidifolium <0. 1 1.0 Tortula norvegica <0. 1 Equisetum arvense 4.0 Warnstorfiaexannulata 10.1 Gnaphalium supinum 1.2 }uncus biglumis 0.4 Anthelia juratzkana 18.5 9.0 Koenigia islandica 5.1 Barbilophozia jloerkei 0. 1

Luzula arcuata ssp. confusa Q2 Cephalozia sp. 0.2 1.5 Oxyria digyna 0. 1 Gymnomitrion apiculatum <0. 1

Phippsia algida 0. 1 Gymnomitrion concinnatum 9.:1 Phleum alpinum 1.0 Gymnomitrion corallioides 6.2

Poa alpina !U. 0. 1 Lophozia sp. 1.1 Ranunculus acris 0. 1 Marsupella brevissima 0. 1

Ranunculus glacialis 0.3 Pleurocladula albescens .Q2 0.8 Ranunculus nivalis 0.4 Preissia quadrata <0. 1 Ranunculus pygmaeus <0. 1 Sagina nivalis <0. 1 Cetraria ericetorum <0. 1 Sali.x herbacea 1.5 Cetraria islandica 0.9 Sali.xpolaris 0.3 Cetraria islandica ssp. crispiformis 0.2

Saxifraga cernua 0. 1 Cetrariella delisei Q,2 0. 1 Saxifraga oppositifolia <0. 1 Cladina arbuscula ssp. mitis 0.4 Saxifraga stellaris 3.0 Cladonia coccifera 0.3 Saxifraga tenuis <0. 1 Cladonia ecmocyna <0. 1

Sibbaldia procumbens 2.,Q Cladonia gracilis !U Silene acaulis <0. 1 Cladonia pocillum 0. 1 Trisetum spicatum 0.3 Cladonia pyxidata 0. 1 Cladonia uncialis 0. 1

Andreaea rupestris Q,2 Crustaceous black 14.0 Bartramia ithyphylla <0. 1 0.5 Crustacous lichens 0. 1

Brachythecium sp. <0. 1 Ochrolechia frigida 0.4

Bryum sp. 8.5 Pertusaria sp. 0.4

Conostomum tetragonum 0.3 0. 1 Solorina crocea !U. Dicranoweisia crispula <0. 1 Stereocaulon rivulorum 0. 1

Kiaeria starkei 4,.0 Stereocaulon sp. M Oncophorus wahlenbergii 1.5

Total 91.7 59.3

Acta Phytogeogr. Suec. 82 54 R. Virtanen & S. Eurola

Appendix 6. Mean percentage cover of plants in community types of the Saxifraga oppositifolia group. 1 - Salix polaris-Silene acaulis type, 2 - Saxifraga oppositifolia-Ranunculus sulphureus type, 3 - Dryas octopetala-Cassiope tetragona type. For frequencies, see Appendix 1.

2 3 2

Arabisalpina 0.3 <0.1 Mnium blyttii <0. 1 0.3 0.3 Bistorta vivipara 0.5 1.3 Platydictya jungermannioides <0.1 <0. 1 Cardamine bellidifolia <0. 1 <0. 1 Pogonatum umigerum <0. 1 <0.1 Carex bigelowii Q,2 0.3 <0. 1 Pohlia cruda 0.2 <0. 1 0.2 Carex lachenalii 1.1 Pohlia spp. tU <0. 1 <0. 1 Cassiope hypnoides 2.6 M 0.3 Polytrichastrum alpinum <0. 1 0.2 Cassiope tetragona M 0.7 11.7 Polytrichastrum sexangulare 0. 1 0.8 Cerastium arcticum 0.2 0.2 <0. 1 Polytrichum juniperinum <0. 1 <0. 1 <0. 1 Draba fladnizensis <0. 1 <0.1 0.2 Sanionia uncinata !U <0. 1 <0. 1 Dryas ocropetala 0.2 3.2 36.7 Tayloria froelichiana <0. 1 Equisetum variegatum Q,2 Timmia austriaca 0.6 Erigeron humilis <0. 1 0.2 To rtella fragilis !U 3.3 0.3 Erigeron uniflorus 0.3 <0.1 <0. 1 Tortula norvegica 0.2 Festuca ovina 0.4 0.3 0.4 Huperzia se/ago !U <0. 1 Anastrophyllum minutum 0.7 <0. 1 0.2 Luzula arcuata ssp. confu sa 0.3 !U Anthelia juratzkana 1.3 0.6 <0. 1 Luzula spicata <0. 1 <0. 1 <0.1 Barbilophozia hatcheri 0.2 <0. 1 Oxyria digyna 0.3 <0. 1 Barbilophozia kunzeana 0.3 <0. 1 Poa alpigena <0. 1 <0. 1 Blepharostoma trichophyllum tU 0.2 0.2 Poa alpina 0.5 0.3 Preissia quadrata 0.3 0.2 <0. 1 Poa arctica M Scapania sp. <0.1 <0. 1 Ranunculus nivalis 0. 1 <0. 1 Tritomaria quinquedentata 0.4 <0. 1 Ranunculus pygmaeus <0.1 <0. 1 Ranunculus sulphureus � Cetraria ericetorum 0.2 4.7 Sagina nivalis <0. 1 <0. 1 Cetraria islandica 0. 1 <0. 1 Salix polaris 8.0 1.4 .L.Q Cetraria islandica ssp. crispiformis Q,2 0.2 3.3 Salix reticulata 0.3 Q,2 0.5 Cetrariella delisei u 0.6 2. 1 Saussurea alpina <0. 1 0.3 Cladina arbuscula ssp. mitis 0.8 .L.Q 1.4 Saxifraga oppositifolia <0. 1 2.8 0.3 Cladonia coccifera ll <0.1 Saxifraga tenuis 0.3 ll Cladonia gracilis ll <0. 1 0.2 Sibbaldia procumbens 0.3 1.3 Cladonia pocillum tU 0.3 Q2 Silene acaulis 3.4 2.8 <0. 1 Cladonia symphycarpa Q2 Taraxacum sp. <0. 1 <0. 1 Cladonia uncialis <0. 1 <0. 1 Thalictrum alpinum <0. 1 0.3 Crustaceous black 2.& 29.8 5.3 Veronica alpina <0. 1 <0. 1 Crustaceous lichens <0. 1 1.& Ochrolechia frigida 2.8 2.6 1.1 Bryum p. 0.6 Q,2 Peltigera leucophlebia <0. 1 <0. 1 Dicranum scoparium 0.2 <0. 1 1.7 Psoroma hypnorum <0. 1 <0.1 Dicranum sp. 0.6 <0.1 Solorina bispora <0. 1 0.2 Distichium capillaceum 0.5 2.6 0.3 Stereocaulon alpinum <0. 1 Q2 Encalypta alpina <0.1 <0. 1 <0. 1 Stereocaulon botryosum <0. 1 <0. 1 Fissidens osmundoides <0.1 0.4 Stereocaulon sp. ll <0. 1 Meesia uliginosa 0.2 <0.1 Total 39.9 69.7 77.9

Additional species, occurringonly in one cluster with a low frequency.

I: Cerastium cerastoides ( <0. 1 ), Draba daurica (0.2), Equisetum arvense(0. 1 ), Minuartia biflora ( <0. 1 ) , Phyllodoce caerulea ( <0.1 ), Potentilla crantzii (0.2), Saxifraga cespitosa (0.2), Saxifraga nivalis (0.2), Trisetum spica rum (0. 1 ), Bartramia ithyphylla (0.2), Conostomum tetragonum ( <0. 1 ), Cyrtomnium hymenophylloides ( <0. 1 ), Distichium inclinatum (0.4), Hylocomium splendens var. alaskanum (0. 1 ), Kiaeria starkei ( <0. 1 ), Barbilophoziafloerkei (0.2), Cephalozia sp. ( <0. 1), Marsupella brevissima

(0. 1 ) , Odontoschisma macounii ( <0. 1 ), Cladonia pyxidata (0.2), Cladonia turgida ( <0. 1)

2: Antennaria porsildii (0.2), Gnaphalium supinum ( <0.1), Minuartia stricta ( <0.1), Dicranoweisia crispula (<0. 1 ), Loeskypnum badium (0.4), Mnium thomsonii (<0. 1 ), Peltigera rufescens (0. 1 ), Psora decipiens ( <0. 1 ), Stereocaulon rivulorum ( <0. 1)

3: Anthoxanthum odoratum ( <0. 1 ), Carex atrofusca ( <0. I), Dicranum elongatum (0.7), Tritomaria scitula ( <0. 1)

Acta Phytogeogr. Suec. 82 Middle oroarctic vegetation in Finland and middle-northern arctic vegetation on Svalbard 55

Appendix 7. Mean percentage cover of plants in community types of the Luzula confusa group. 1 - Luzula confusa-Gymnomitrion corallioides community, 2 - Luzula confusa-Racomitrium lanuginosum community, 3 - Luzula confusa-Sanionia community. For frequencies, see Appendix 1.

2 2 3

Alopecurus borealis <0. 1 <0. 1 Polytrichastrum alpinum 6.8 <0. 1 <0. 1 Bistorta vivipara 0.2 <0. 1 1.0 Polytrichum juniperinum <0. 1 0.3 Cardamine bellidifolia <0. 1 3.2 Polytrichum pilif e rum QJ_ Cerastium arcticum 0.4 Polytrichum strictum 0.8 <0. 1 Cochlearia groenlandica QJ_ Racomitrium canescens u 4.3 Draba alpina <0. 1 0.3 Racomitrium lanuginosum Qj_ l..U <0. 1 Draba oxycarpa <0. 1 <0.1 Sanionia uncinata 5.9 8.4 24.2 Draba subcapitata <0. 1 <0.1 Timmia austriaca <0.1 <0. 1 0.7 Dryas octopetala 0.2 0.8 To rtula ruralis 1.5 Ll Luzula arctica 0.3 Luzula arcuata ssp. confusa 11.6 1.2 11.4 Anastrophyllum minutum <0. 1 <0.1 Oxyria digyna 0.2 0.2 <0. 1 Cephaloziella arctica <0. 1 0.3 Pedicularis hirsuta QJ_ QJ_ Gymnomitrion concinnatum 2.9 <0. 1 Poa alpina <0. 1 0.5 Gymnomitrion corallioides 12.8 <0.1 Poa arctica <0. 1 <0. 1 Ptilidium ciliare 4.3 Qj_ <0. 1 Potentilla hyparctica <0. 1 <0. 1 Tritomaria scitula 0.6 2.5 Ranunculus pygmaeus <0. 1 <0. 1 Salix polaris 11.1 5.9 9.3 Bryocaulon divergens <0. 1 <0. 1 Saxifraga cernua <0. 1 0.2 Cetraria aculeata 0.2 <0. 1 <0. 1 Saxifraga cespitosa <0. 1 0.2 0.8 Cetraria islandica !U 1J. Saxifraga hieracifolia <0. 1 <0. 1 Cetrariella delisei 10.1 25.7 Q2 Saxifraga nivalis <0.1 <0. 1 0.2 Cladina arbuscula ssp. mitis 0.2 2.6 QJ_ Saxifraga oppositifolia Ll 9.6 2.0 Cladonia amaurocraea <0. 1 QJ_ Silene acaulis 0.2 <0. 1 Cladonia cltlorophaea <0. 1 0.5 Stellaria Longipes coli. <0. 1 <0. 1 Cladonia coccifera QJ_ <0.1 0.4 Cladonia ecmocyna <0.1 <0. 1 Andreaea rupestris <0. 1 <0. 1 Cladonia gracilis 0.2 QJ_ 0.6 Aulacomnium palustre <0. 1 <0. 1 Cladonia pocillum <0. 1 0.5 Aulacomnium turgidum u 0.2 0.3 Cladonia pyxidata <0. 1 <0. 1 Barbula sp. <0. 1 0.4 Flavocetraria cucullata 0.3 0.2 Bryum sp. 1.5 <0. 1 0.2 Flavocetraria nivalis 0.2 .L.1 Ceratodon purpureus 2.9 <0. 1 Ochrolechia frigida 7.9 5.4 1.0 Conostomum tetragonum M <0. 1 Peltigera leucophlebia <0. 1 <0. 1 Dicranum angustum 1.6 QJ_ 5.4 Peltigera rufescens Q2 0.4 Dicranum elongatum Q2 Psoroma hypnorum 3.,6 0.6 1.8 Dicranum fuscescens 2.1 1.5 <0. 1 Rinodina turfacea 0.2 1.7 Dicranum scoparium <0. 1 <0.1 Solorina crocea <0. 1 <0. 1 Dicranum spadiceum <0. 1 0.3 0.2 Sphaerophorus globosus <0.1 0.2 Distichium capillaceum 0.3 0.3 Stereocaulon alpinum 1.4 2.2 u Hylocomium splendens var. alaskanum 4.2 Stereocaulon rivulorum 1.4 0. 1 0.2 Hypnum revolutum 1.4 1.7 Stereocaulon saxatile 2.1 1.7 Oncophorus wahlenbergii <0.1 <0. 1 <0.1 Stereocaulon vesuvianum 0.5 <0. 1 Pohlia cruda <0. 1 <0. 1 Stereocaulon sp. 0. 1 0.2 Thamnolia vermicularis QJ_ 0. 1 0.2

Total 116.2 90.6 89. 1

Additional species, occurring only in one cluster with a low frequency. 1: Cassiope tetragona (10.7), Drabajladnizensis (<0. 1), Empetrum nigrum ssp. hermaphroditum (0. 1), Festuca brachyphylla (<0. 1), Huperzia selago (<0. 1), Minuartia rubella (<0. 1), Pedicularis lanata ssp. dasyantha (<0. 1), Phippsia algida (<0. 1), Poa alpigena (0.3), Saxifraga hyperborea (<0. 1), Trisetum spicatum (<0. 1), B1yum pallescens ( <0. 1 ), Kiaeria glacialis ( <0. 1 ), Polytrichum hyperboreum ( <0. 1 ), Odontoschisma macounii ( <0. 1 ), Scapania tundrae ( <0. 1 ), Tritomaria quinquedentala ( <0.1 ), Cetraria islandica ssp. crispiformis ( <0. 1 ), Cladonia cervicomis ( <0. 1 ), Cladonia macrophylla ( <0. 1 ), Cladonia macroceras ( <0. 1 ), Nephroma expallidum ( <0. 1 ), Peltigera apthosa ( <0. 1 ), Stereocaulon glareosum (0.4)

2: Draba corymbosa ( <0. 1 ), Papaver dahlianum ( <0. 1), Ranunculus nivalis (0. 1 ), Cratoneuron sp. (0.6), Dicranum majus (0. 1 ), Alectoria nigricans ( <0. 1 ), Collema tenax ( <0. J ), Peltigera malacea ( <0. 1 ), Physconia muscigena (0. 1)

3: Arenaria pseudofrigida ( <0. 1 ), Carex rupestris (3.3), Cerastium regelii ( <0. 1 ), Draba nivalis ( <0.1 ), Equisetum arvense ( <0. 1 ), Hierochloe alpina (0.7), Minuartia bijlora ( <0. 1 ), Bartramia ithyphylla ( <0. 1 ), Brachythecium turgidum ( <0. 1 ), Climacium dendroides (0.2), Encalypta alpina ( <0. 1), Encalypta rhaptocarpa ( <0.1 ), Hypnum vaucheri (

Acta Phytogeogr. Suec. 82 56 R. Virtanen & S. Eurola

Appendix 8. Mean percentage cover of plants in communities of the Papaver dahlianum group. 1 - Papaver dahlianum polar desert, 2-Papaver dahlianum-Racomitrium panschii community. For frequencies, see Appendix 1.

2 2

Alopecurus borealis <0. 1 Dicranum spadiceum <0. 1 <0. 1 Bistorta vivipara <0. 1 Encalypta sp. <0. 1 Cerastium arcticum 0.2 0.2 Hypnum revolutum !U 2.9 Draba alpina <0. 1 Hypnum vaucheri <0. 1 Draba arctica Polytrichastrum alpinum <0. 1 <0. 1 Draba corymbosa <0. 1 Polytrichum hyperboreum <0. 1 Draba nivalis Q,l <0. 1 Polytrichum pi liferum <0. 1 <0. 1 Draba norvegica <0. 1 Polytrichum sp. <0. 1 Draba oxycarpa <0. 1 <0. 1 Racomitrium canescens Q,l Q,2 Draba subcapitata Q,l Racomitrium lanuginosum <0. 1 Dryas octopetala 0.3 0.2 Racomitrium panschii 4.9 Festuca hyperborea <0. 1 Sanionia uncinata <0. 1 Festuca rubra ssp. arctica !U Schistidium sp. <0. 1 Luzula arctica <0. 1 Tortula ruralis 0.6 Luzula arcuata ssp. confusa 1.6 2.9 Minuartia bijlora <0. 1 Gymnomitrion corallioides Q,l <0. 1 Minuartia rubella 0. 1 Q,l Oxyria digyna <0. 1 0.2 Alectoria nigricans <0. 1 Papaver dahlianum 0.7 0.3 Caloplaca sp. <0. 1 Pedicularis hirsuta Q2 Cetraria aculeata <0. 1 !U. Phippsia algida <0. 1 Cetraria islandica ssp. crispiformis 0.2 <0. 1 Poa arctica 1.6 0.4 Cetrariella delisei 0.6 Potentilla hyparctica 0.2 <0. 1 Cetrariella fa stigiata <0. 1 Potentilla pulchella <0.1 Cladonia coccifera <0. 1 Sagina nivalis 0.2 Cladonia chlorophaea Q,l Salix polaris 4.4 Cladonia macrophylla <0. 1 <0. 1 Saxifraga cemua <0.1 Cladonia pocillum 0.3 � Saxifraga cespitosa Q,l 0.7 Cladonia sp. <0. 1 0.3 Saxifragaflagellaris <0. 1 Lecidea sp. 0.7 Saxifraga nivalis Q,l 0. 1 Nephroma expallidum Q,l <0. 1 Saxifraga oppositifolia <0. 1 0.6 Ochrolechia frigida 0.4 10.4 Silene acaulis Q2 Peltigera rufescens <0. 1 Silene fu rcata <0.1 Physconia muscigena <0. 1 Stellaria longipes coli. <0.1 <0. 1 Psoroma hypnorum <0. 1 <0. 1 Rinodina turfacea 2& Bartramia ithyphylla <0.1 Sphaerophorus globosus QJ. Ceratodon purpureus <0. 1 Stereocaulon alpinum <0. 1 0.4 Conostomum tetragonum Q,l Stereocaulon rivulorum <0. 1 Cratoneuron sp. Q,l Stereocaulon sp. <0.1 <0. 1 Dicranoweisia crispula <0.1 Thamnolia vermicularis <0.1 0.2

Total 9.4 36.7

Acta Phytogeogr. Suec. 82 Middle oroarctic vegetation in Finland and middle-northern arctic vegetation on Svalbard 57

Appendix 9. Mean percentage cover of plants in communities of the Dryas octopetala group. 1 - Dryas octopetala-Tomentypnum community, 2-Dryas octopetala-Sanionia community, 3 - Dryas octopetala-Salix polaris community, 4-Saxifraga oppositifolia­ Hypnum revolutum community. For frequencies, see Appendix 1.

2 4 2 3 4

Alopecurus borealis 0.2 <0.1 <0. 1 Dicranum elongatum <0. 1 <0. 1 Bistorta vivipara 4.6 4.5 1.0 1.2 Dicranum fuscescens 0. 1 0.8 Cardamine bellidifolia <0. 1 <0. 1 Dicranum spadiceum u <0.1 Carex rupestris 0.3 <0. 1 Distichium capillaceum <0. 1 <0. 1 <0. 1 1.2 Cassiope tetragona 10.1 0.2 11.7 Distichium inclinatum <0. 1 <0. 1 Cerastium arcticurn 0.2 <0. 1 0.5 0.2 Ditrichurnjlexicaule Q,1 0.2 Cerastium regelii <0. 1 <0. 1 0. 1 Hylocorniurn splendens var. alaskanum 16.8 u <0. 1 Hypnum revolutum M <0. 1 b2 � Draba alpina Q,1 {ll Q,1 0.2 Polytrichastrum alpinum <0. 1 Q,1 0.2 <0. 1 Draba norvegica <0. 1 <0. 1 <0. 1 Polytrichum juniperinurn 0.5 Qd Draba subcapicata 0.2 <0. 1 <0. 1 {ll Polytrichum pilife rurn 0.2 <0. 1 Dryas octopetala 16.9 23.1 15.3 1.6 Racornitrium canescens 0.8 2.5 Equisetum scirpoides 4.5 Sanionia uncinata 0.2 29.9 5.0 u Festuca rubra ssp. arctica <0. 1 l.J. 0.5 <0. 1 Schistidium apocarpurn 0.3 <0. 1 Festuca vivipara <0. 1 <0. 1 0. 1 Timmia austriaca Q,1 Q,1 }uncus biglumis <0.1 <0. 1 <0. 1 To mentypnum nitens 10.8 7.0 10.8 Luzula arctica 1.0 {ll 0.2 <0. 1 Tortula ruralis <0. 1 M <0. 1 Luzula arcuata ssp. confusa 9.4 1.3 0.3 2.5 Minuartia rossii <0. 1 <0. 1 Gymnornitrion corallioides u Minuartia rubella <0.1 0.2 Oxyria digyna Qd <0.1 <0. 1 <0. 1 Buellia papillata <0. 1 2.2 Papaver dahlianum <0.1 {ll <0. 1 {ll Cetraria aculeata <0. 1 <0. 1 Pedicularis hirsuta 0.3 0.2 <0.1 Q,1 Cetraria islandica <0.1 {ll Pedicularis lanata ssp. dasyantha <0. 1 gu <0. 1 Cetraria islandica ssp. crispiformis <0. 1 <0. 1 Poa alpigena Q2 0. 1 Cetrariella delisei 0. 1 <0. 1 Poa alpina 0.2 <0.1 Cladonia chlorophaea Q,1 Poa arctica 0.3 Qd 1.1 0.2 Cladonia gracilis 0. 1 <0. 1 <0. 1 Potentilla hyparctica <0. 1 <0. 1 Cladonia pocilllurn Q,1 <0. 1 Sagina nivalis Q,1 <0. 1 Cladonia pyxidata <0. 1 <0. 1 <0. 1 Salix polaris 11.4 12.8 10.5 5.3 Flavocetraria nivalis <0. 1 <0.1 Saxifraga cemua <0. 1 <0. 1 0. 1 Q,1 Lecidea sp. <0. 1 1.7 0.7 Saxifraga cespitosa <0. 1 <0.1 <0. 1 0. 1 Nephroma expallidum 0.2 0.2 Saxifragajlagellaris <0.1 Q,1 Ochrolechia frigida 7.9 7.4 1.7 8.7 Saxifraga nivalis <0. 1 <0. 1 <0. 1 <0. 1 Peltigera leucophlebia Qd <0. 1 Q2 Saxifraga oppositifolia 0. 1 1.8 1.1 6.9 Peltigera rufescens ll 0.2 ll Silene acaulis <0. 1 0. 1 Physconia muscigena <0. 1 <0.1 <0. 1 Si le ne fu rcata {ll Psorornahypnorum 2.7 l.l Silene uralensis <0. 1 <0. 1 Rin.odina turfacea Qd <0.1 Stellaria longipes coli. 0.3 ll Q,1 <0. 1 Solorina crocea <0. 1 <0. 1 Sphaerophorus globosus <0. 1 <0. 1 Aulacomnium turgidum 5.9 0.4 (U Stereocaulon alpinum 0.8 <0.1 2.5 Bartrarnia ithyphylla 0.2 <0. 1 Stereocaulon rivulorurn <0. 1 lJ2 u Qd Brachytheciurn turgidum <0. 1 <0. 1 Stereocaulon saxatile <0. 1 <0. 1 Bryurnpallescens <0. 1 0.2 Stereocaulon sp. 3. 1 <0.1 Bryum spp. <0.1 <0.1 <0. 1 <0. 1 Thamnolia verrnicularis 0.2 {ll 0. 1 {ll Cratoneuron sp. <0.1 5.7 Cyanobacteria 2.3 13.6 Dicranum angusturn 0. 1 3.3 Total 122.5 114.8 75.2 60.6

Additional species, occurring only in one cluster with a low frequency.

1: Saxifraga fo liolosa (< 0.1), Ceratodon purpureus (<0. 1), Dicranurnrnajus (1.4), Kiaeria glacialis (<0. 1), Oncophorus virens (<0. 1), Oncophorus wahlenbergii (<0. 1),

Polytrichastrurn sexangulare ( <0.1 ), Polytrichum strictum ( <0. 1 ), Racomitrium ericoides (0. 1 ), Racornitrium panschii (0.2), Racornitriurn sudeticum ( <0. 1 ), Blepharostoma trichophyllurn (0.2), Gyrnnornitrion concinnaturn (<0. 1), Odontoschisma macounii (0.7), Ptilidiurn ciliare (0.8), Tritomaria scitula (<0. 1), Alectoria nigricans (<0. 1),

Arctocetraria nigricascens ( <0. 1 ), Cladonia amaurocraea ( <0.1 ), Cladonia macrophylla ( <0. 1 ), Cladonia rnacroceras( <0. 1 ), Peltigera malacea ( <0. 1 ), Solorina octospora

(<0. 1)

2: Draba corymbosa ( <0. 1 ), Equisetum variegatum (0.2), Phippsia algida ( <0.1), Trisetum spicatum ( <0. 1 ), Encalypta rhaptocarpa ( <0. 1 ), Timmia norvegica ( <0. 1 ),

Cephaloziella arctica ( <0. 1), Te tralophozia setiformis ( 1.1), Cladonia coccife ra ( <0. 1 ), Peltigera apthosa ( <0. 1)

3: Polemonium boreale ( <0. 1 ), Saxifraga hieracifo lia ( <0.1), Abietinella abietina ( <0. 1), Fulgensia bracteata ( <0. 1 ), Peltigera canina ( <0. 1 ), Solorina bispora ( <0. 1)

4: Festuca brachyphylla (<0. 1), Festuca hyperborea (<0. 1), Min.uartia bijlora (<0. 1), Potentilla pulchella (<0. 1), Campylium stellatum (0. 1), Encalypta alpina (<0. 1),

Encalypta streptocarpa (<0.1), Stereocaulon glareosum (0. 1)

Acta Phytogeogr. Suec. 82 58 R. Virtanen & S. Eurola

Appendix 10. Mean percentage cover of plants in the moss tundra communities. 1 - Sanionia-Saxifraga hyperborea community, 2-

Aulacomnium turgidum-Alopecurus borealis community, 3 - Aulacomnium turgidum-Hylocomium community, 4 - Racomitrium canescens-Oxyria community. For frequencies, see Appendix 1.

2 4 2 3 4

Alopecurus borealis 0.3 10.3 8.8 2.3 Polytrichum pi life rum lU <0. 1 Bistorta vivipara <0. 1 1.4 1.3 2.5 Polytrichum strictum 0.5 0.2 0.2 Cardamine bellidifolia <0. 1 <0. 1 lU Racomitrium canescens <0. 1 1.1 17.3 Cassiope tetragona 20.2 Racomitrium ericoides <0. 1 <0. 1 Cerastium arcticum <0. 1 <0. 1 lU Racomitrium lanuginosum 0.3 <0. 1 Cerastium regelii lU Sanionia uncinata 35.2 6.3 16.6 10.1 Draba micropetala <0.1 <0. 1 Sarmentypnum sarmentosum 6.8 8.3 4.0 Equisetum arvense <0. 1 1.3 <0. 1 Scorpidium revolvens 6.3 <0.1 Equisetum variegatum <0. 1 <0. 1 Timmia austriaca <0. 1 <0. 1 .L.Q Luzula arctica 0.4 0.3 0.7 lU Tomentypnum nitens 4.1 0.7 8.0 Luzula arcuata ssp. confusa 2.4 3.8 7.4 10.6 Oxyria digyna M <0. 1 0.7 Anastrophyllum minutum <0. 1 0.5 lU Pedicularis hirsuta lU 0.3 <0. 1 Anthelia juratzkana lU Poa alpigena 0.5 il 1.7 Blepharostoma trichophyllum 0.9 3.1 5.2 Poa alpina <0. 1 <0. 1 Cephaloziella arctica <0. 1 2.5 .u <0. 1 Poa arctica <0. 1 1.3 0.3 0.3 Cephalozia sp. 0.8 0.7 Potentilla hyparctica <0. 1 <0. 1 Gymnomitrion concinnatum J..Q,_8_ Ranunculus pygmaeus 0.2 Gymnomitrion cora/lioides 1.3 0.2 0.6 0.4 Ranunculus sulphureus <0.1 0.3 lU <0. 1 Lophozia wenzelii 0.3 <0. 1 <0. 1 Sagina nivalis <0. 1 <0. 1 Marsupella boeckii 0.2 6.3 <0. 1 Salix polaris 2.3 15.0 25.5 13.2 Odontoschisma macounii lU <0. 1 0.5 <0. 1 Saxifraga cernua <0. 1 lU <0. 1 <0. 1 Ptilidium ciliare <0. 1 0.3 <0. 1 .L2 Saxifraga cespitosa <0. 1 lU <0. 1 Tritomaria quinquedentata 1.1 0.7 <0. 1 Saxifraga fo liolosa lU 0.2 0. 1 Tritomaria scitula 0.8 lU Saxifraga hieracifolia lU Saxifraga hirculus <0. 1 <0. 1 Candelariella sp. <0.1 <0. 1 Saxifraga hyperborea 0.2 <0. 1 Cetraria islandica <0. 1 lU Saxifraga nivalis <0. 1 lU <0. 1 Cetraria islandica ssp. crispiformis <0. 1 <0. 1 Saxifraga oppositifolia 1.0 <0. 1 <0. 1 Cetraria nigricans <0. 1 <0. 1 Stellaria longipes coli. 0.2 0.3 0.3 Cetrariella delisei <0. 1 <0. 1 <0. 1 <0.1 Cladonia amaurocraea <0. 1 lU Aulacomnium turgidum 0.5 17.8 21.8 13.7 Cladonia chlorophaea 0.2 <0. 1 0.2 <0. 1 Bartramia ithyphylla <0. 1 lU lU Cladonia coccifera 0. 1 lU <0. 1 Bryum cryophilum 0. 1 Cladonia gracilis 0.2 <0. 1 <0. 1 0.4 Bryum spp. <0. 1 3.8 Cladonia macrophylla <0. 1 <0. 1 lU Calliergon stramineum <0. 1 .u Cladonia pocillum lU <0. 1 0.2 Conostomum tetragonum 0.2 1.4 0.2 <0. 1 Cladonia pyxidata <0. 1 <0. 1 Cratoneuron sp. <0. 1 <0. 1 0. 1 Nephroma expallidum 0.2 0.7 Dicranum angustum lL.8. 7.5 .8.3. 2d Ochrolechia frigida 2.8 0.3 1.5 2.0 Dicranum elongatum <0. 1 2.2 0.8 Peltigera apthosa <0. 1 Q2 <0. 1 Dicranum fu scescens 0.8 M 2.4 Peltigera canina 0.2 Q,2 0.3 Dicranum majus <0. 1 12.6 <0. 1 Q,2 Peltigera leucophlebia 0.3 0.7 Qj_ Dicranum spadiceurn <0. 1 0.4 Q,2 Peltigera rufescens <0. 1 0.6 <0. 1 lU Distichium capillaceurn <0. 1 <0. 1 Psoroma hypnorum <0. 1 0.2 0.4 Q,2 Ditrichum flexicaule 3.1 <0. 1 Rinodina turfacea lU Hylocomium splendens var. alaskanum lU 7.2 3.7 Solorina crocea <0. 1 lU <0. 1 Kiaeria glacialis 0.7 0. 1 Stereocaulon alpinum 0.3 0.6 2.1 Meesia uliginosa 0.5 <0. 1 Stereocaulon glareosum 0.5 <0. 1 Oncophorus virens lU <0.1 <0. 1 Stereocaulon rivulorum 0.8 <0. 1 3.7 Oncophorus wahlenbergii 0.2 <0. 1 0.4 Stereocaulon saxatile <0. 1 0.4 Pohlia nutans <0. 1 <0. 1 Stereocaulon vesuvianum 0.5 <0. 1 Pohlia spp. 0.2 <0. 1 Stereocaulon sp. <0. 1 1.4 1.0 Polytrichastrum alpinum 10.1 D_ M Thamnolia vermicularis lU lU <0. 1 Polytrichurnjuniperinum 0.6 0.3 0.3 Total 101.3 130.1 134.6 144.3

Additional species, occurring only in one or two clusters with a low frequency. I: Campylium stellatum ( <0. 1), Dicranoweisia crispula ( <0. 1), Loeskypnum badium( <0. 1), Polytrichastrum sexangulare ( <0. 1), Lophozia opacifolia ( <0. 1), Scapania tundrae ( <0. 1 ), Cladonia bellidijlora ( <0. 1), Cladonia cervicornis ( <0. 1 ), Cladonia macroceras ( <0. 1), Cladina arbuscula ssp. mitis ( <0. 1), Physconia muscigena ( <0. 1) 2: Draba corymbosa ( <0. 1 ), Equisetum scirpoides (0.3), Aulacomnium palustre ( <0. 1), Cirriphyllum cirrosum ( <0. 1 ), Cynodontium strumife rum ( <0. 1 ), Hypnum vaucheri (<0. 1), Meesia triquetra (<0. 1), Orthothecium chryseum (<0. 1), Philonotis fo ntana (<0. 1), Platydictya jungermannioides (<0. 1), Tortula ruralis (<0. 1), Tetralophozia setiformis (2.5), Collema tenax (2.5) 3: Drabajladnizensis ( <0. 1), ]uncus biglumis (0. 1 ), Koenigia islandica (0.1), Papaver dahlianum ( <0. 1 ), Saxifraga jlagellaris ( <0. 1), Hypnum recurvatum ( <0. 1 ), Hypnum revolutum (0.6), /sopterygiopsis pulchella (<0. 1), Kiaeria starkei (<0. 1), Polytrichum hyperboreum (0. 1), Caloplaca sp. (<0. 1), Cetraria aculeata (<0. 1), Collema limosum ( <0. 1 ), Sphaerophorus globosus ( <0. 1 ), Stereocaulon tomentosum ( <0. 1) 4: Draba alpina ( <0.1 ), Draba norvegica ( <0. 1), Draba oxycarpa ( <0. 1), Draba subcapitata ( <0. 1), Dryas octopetala (0.4), Huperzia se/ago ( <0. 1), Pedicularis lanata ssp. dasyantha (<0. 1), Silenefurcata (<0. 1), Pogonatum dentatum (2.1), Scapania irriqua (<0. 1), Alectoria nigricans (<0. 1), Buellia papillata (<0. 1), Peltigera malacea (<0. 1)

Acta Phytogeogr. Suec. 82 Middle oroarctic vegetation in Finland and middle-northern arctic vegetation on Svalbard 59

Appendix 11. Mean percentage cover of plants in the Sanionia snowbed communities. 1 - Sanionia snowbed, 2-Sanionia-Poa alpigena snowbed. For frequencies, see Appendix 1.

2

Alopecurus borealis 0.5 0.4 Dicranum majus <0. 1 Bistorta vivipara 1.2 Dicranum spadiceum <0. 1 Cardamine bellidifolia <0. 1 Ditrichum jlexicaule <0. 1

Cardamine pratensis ssp. polemonioides <0. 1 Hylocomium splendens var. alask.anum 0.6 3.8 Cerastium arcticum 1.1 0.6 Hypnum bambergeri <0.1 Cerastium regelii 0.2 0.2 Oncophorus wahlenbergii 0.3 Cochlearia groenlandica 0.2 <0. 1 Philonotis tomentella 1.3 Deschampsia alpina <0. 1 Pohlia cruda <0. 1

Draba alpina <0. 1 Pohlia spp. 0.8 <0. 1 Draba corymbosa <0. 1 Polytrichastrum alpinum 0.2 4.5 Draba Lactea <0. 1 Polytrichastrum sexangulare 0.7 Draba subcapitata <0. 1 Polytrichum juniperinum 0.4 Dupontia fisheri u Polytrichum strictum <0. 1 Equisetum arvense bQ Racomitrium canescens <0. 1 <0.1 Equisetum variegatum 0.2 Racomitrium Lanuginosum <0. 1 Luzula arctica <0. 1 Sanionia uncinata 58.1 45.4 Luzula arcuata ssp. confusa u 2.0 Sarmentypnum sarmentosum <0. 1 Minuartia bijlora <0.1 Timmia austriaca 0.6 <0. 1 Oxyria digyna 0.3 Q,2 Tomentypnum nitens <0. 1 4.2 Pedicularis hirsuta <0. 1 To rtula ruralis 0.3 Phippsia algida <0. 1 <0. 1 Poa abbreviata <0. 1 Cephaloziella arctica 2.5 <0. 1 Poa alpigena <0. 1 10.1 Gymnomitrion corallioides 0.8

Poa alpina 0.2 <0. 1 Hepaticae spp. 5.0

Poa arctica 0.6 Marsupella sp. 0.3 Ranunculus pygmaeus <0. 1 0.3 Ptilidium ciliare 0.8 Ranunculus sulphureus 0.3 0.3 Tritomaria quinquedentata <0. 1 Sagina nivalis <0. 1 Salix polaris 2.9 2,.2 Cetraria islandica 1.9 Saxifraga cemua 0.4 Q2 Cctrariclla dclisei LQ <0. 1 Saxifraga cespitosa !U !U Cladina arbuscula ssp. mitis <0. 1 Saxifragafo liolosa <0. 1 <0. 1 Cladonia amaurocraea <0. 1 Saxifraga hieracifo lia <0. 1 Cladonia chlorophaea <0. 1 0. 1 Saxifraga hirculus <0. 1 Cladonia gracilis 0.2 <0.1 Saxifraga hyperborea 0. 1 !U Cladonia pocillum <0. 1 <0. 1 Saxifraga nivalis <0. 1 !U Cladonia sp. <0. 1 Saxifraga oppositifolia .L1 0.3 Flavocetraria cucullata <0. 1 Saxifraga rivularis 0.3 <0. 1 Flavocetraria nivalis <0. 1

Silene acaulis <0. 1 Lecidea sp. <0. 1 Stellaria longipes coil. 0. 1 0.2 Ochrolechia frigida <0. 1 0.3 Trisetum spicatum <0. 1 Peltigera apthosa <0. 1 Peltigera canina 0.4 Aulacomnium pa/ustre 5.7 0. 1 Peltigera leucophlebia 0. 1 Aulacomnium turgidum 3.0 2.8 Peltigera rufescens 0.7 <0. 1 Bartramia ithyphylla 0.2 Psoroma hypnorum <0. 1 Brachythecium turgidum 0.2 Rinodina turfacea <0. 1 Bryum cryophilum <0. 1 0.4 Stereocaulon alpinum u Bryum sp. <0. 1 0.5 Stereocaulon glareosum <0. 1 Calliergon stramineum 6.3 0.5 Stereocaulon rivulorum <0. 1 0.3 Campylium stellatum <0. 1 Stereocaulon tomentosum 1.3

Ceratodon purpureus 2.5 Stereocaulon sp. <0. 1 0.7

Cratoneuron sp. <0. 1 <0. 1 Thamnolia vermicularis <0. 1 <0. 1 Dicranum angustum 5.0 Dicranum fu scescens <0.1 Total 103.1 103.8

Acta Phytogeogr. Suec. 82 60 R. Virtanen & S. Eurola

Appendix 12. Mean percentage cover of plants in wet snowbed communities. The Scorpidium revolvens-Tomentypnumcommunity. For frequencies, see Appendix 1.

Alopecurus borealis 0.8 Campylium stellatum 1.8 Bistorta vivipara 8.0 Cinclidium arcticum 0.2 Calamagrostis stricta 0.8 Distichium capillaceum � Carex bigelowii 0.5 Ditrichum flexicaule <0. 1 Cerastium arcticum <0. 1 Fissidens osmundoides <0. 1 Cerastium regelii 0.2 Hygrohypnum luridum 0.8 Deschampsia alpina 0.2 Hylocomium alaskanum <0. 1 Draba alpina <0. 1 Meesia uliginosa <0. 1 Dupontia fisheri 0.2 Orthothecium chryseum lU Equisetum arvense 3.0 Sanionia uncinata 8.5 Equisetum variegatum 7.1 Sarmentypnum sarmentosum 5.0 Oxyria digyna 0.7 Scorpidium revolvens 28.4 Pedicularis hirsuta <0. 1 Tayloria Ungulata <0. 1 Phippsia algida <0. 1 Timmia austriaca <0. 1 Poa alpigena kQ Tomentypnum nitens 17.3 Poa alpina !U To rtella fragilis 0.5 Poa arctica 0.3 To rtula ruralis <0. 1 Ranunculus nivalis gu Ranunculus sulphureus 0.3 An thelia juratzkana 0.5 Salix polaris 2.4 Lophozia sudetica <0. 1 Saxifraga cemua Q2 Saxifragafo liolosa <0. 1 Cetrariella delisei <0. 1 Saxifraga hieracifo lia <0. 1 Cladonia pocillum <0. 1 Saxifraga hirculus Q,2 Cladonia sp. <0. 1 Saxifraga hyperborea <0. 1 Crustaceous black 10.1 Saxifraga nivalis <0. 1 Crustaceous bchens M Saxifraga oppositifolia .LQ Flavocetraria nivalis <0. 1 Silene acaulis 0.3 Peltigera apthosa <0. 1 Taraxacum sp. <0. 1 Peltigera leucophlebia <0. 1 Peltigera rufescens <0. 1 Aulacomnium turgidum Q2 Solorina bispora <0. 1 Brachythecium turgidum <0. 1 Stereocaulon alpinum <0. 1 Bryumpallescens 1.7 Stereocaulon sp. � Bryum sp. 7.5 Calliergon orbiculari·cordatum <0. 1 Total 118.7

Acta Phytogeogr. Suec. 82 Svenska Viixtgeografiska Sallskapet 61

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1. E. Almquist. 1929. Upplands vegetation och flora. (Veg- 11. N. Stalberg. 1939. Lake Vattem. Outlines of its natural etation and flora of Uppland.) Out of print. history, especially its vegetation. ISBN 91-7210-01 1-7. 2. S. Th unmark. 1931. Der See Fiolen und seine Vegetation. Price: 160 SEK. ISBN 91-7210-002-8. Price: 240 SEK. 12. G. E. Du Rietz, A. G. Hannerz, G. Lohammar, R. Santesson 3. G. E. Du Rietz. 1931. Life-forms of terrestrial flowering & M. Wa rn. 1939. Zur Kenntnis der Vegetation des Sees plants. I. ISBN 91-721 0-003-6. Price: 160 SEK. Talcem. ISBN 91-7210-01 2-5. Price: 160 SEK. 4. B. Lindquist. 1932. Om den vildvaxande skogsalmens 13. Vaxtgeografiskastudier tillagnade Carl Skottsberg pa sextio­ raser och deras utbredning i Nordvasteuropa. (Summary: arsdagen 1112 1940. (Geobotanical studies dedicated to C. The races of spontaneous Ulmus glabra Huds. and their Skottsberg.) 1940. ISBN91-7210-013-3. Price: 290 SEK. distribution in NW Europe.) Out of print. 14. N. Hy lander. 194l.De svenskaformema av Menthagentilis 5. H. Osvald. 1933. Vegetation of the Pacific coast bogs of L. coli. (Zusammenfassung: Die schwedischen Formen der North America. ISBN 91-7210-005-2. Price: 160 SEK. Mentha gentilis L. sensu coli.) ISBN 91-7210-014-1. 6. G. Samuelsson. 1934. Die Verbreitungderhoheren Wasser­ Price: 160 SEK. pflanzen in Nordeuropa. 1934. Out of print. 15. T. E. Hasselrot. 1941. Till kannedom om nagra nordiska 7. G. Degelius. 1935. Das ozeanische Element der Strauch umbilicariaceers utbredning. (Zusammenfassung: Zur und Laubflechtenflora von Skandinavien. Out of print. Kenntnis der Verbreitung einiger Umbilicariaceen in 8. R. Semander. 1936. Granskar och Fiby urskog. En studie Fennoscandia.) ISBN 91-7210-015-X. Price: 240 SEK. over stormluckomas och marbuskamas betydelse i den 16. G. Samuelsson. 1943. Die Verbreitung der Alchemilla­ svenska granskogens regeneration. (Summary: The primi­ Arten aus derVulgaris-Gruppe in Nordeuropa. ISBN 91- tive forests of Granskar and Fiby. A study of the part 7210-016-8. Price: 160 SEK. played by storm-gaps and dwarf trees in the regeneration of 17. Th. Arwidsson. 1943. Studien i.iber die Gefasspflanzen in the Swedish spruce forest.) ISBN 91-7210-008-7. Price: den Hochgebirgen der Pite Lappmark. ISBN 91-7210-017- 240 SEK. 6. Price: 240 SEK. 9. R. Stemer. 1938. Flora der Insel bland. Die Areale der 18. N. Dahlbeck. 1945. Strandwiesen am si.idostlichen Ore­ GefasspflanzenGlands nebst Bemerkungen zu ihrerOekologie sund. (Summary: Salt marshes on the S. E. coast of Ore­ und Soziologie. ISBN 91-7210-009-5.Out of print. sund.) ISBN 91-7210-01 8-4. Price: 160 SEK. 10. B. Lindquist. 1938. Dalby Soderskog. En skansk lOvskog i 19. E. von Krusenstjema. 1945. Bladmossvegetation och blad­ fomtid och nutid. (Zusarnmenfassung: Ein Laubwald in mossflora i Uppsalatrakten. (Summary: Moss flora and Schonen in der Vergangenheit und Gegenwart.) ISBN 91- moss vegetation in the neighbourhood of Uppsala.) ISBN 7210-010-9. Price: 240 SEK. 91-7210-01 9-2. Price: 290 SEK.

Acta Phytogeogr. Suec. 82 62 Svenska Viixtgeografiska Siillskapet

20. N. Albertson. 1946. 6sterplana bed. Ett alvaromrade pa the Langan drainage area, Jamtland, Sweden.) ISBN 91- Kinnekulle. (Zusarnmenfassung: 6sterplana bed. Ein 721 0-036-2. Price: 240 SEK. Alvargebiet auf dem Kinnekulle.) ISBN 91-7210-020-6. 37. M.-B. Florin. 1957. Plankton of fresh andbrackish waters Price: 240 SEK. in the Sodertalje area. ISBN 91-721 0-037-0. Price:160 21. H. Sj Ors. 1948. Myrvegetation i Bergslagen. (Summary: SEK. Mire vegetation in Bergslagen, Sweden.) ISBN 91-7210- 38. M.-B. Florin. 1957. Insjostudier i Mellansverige. Mik:ro­ 02 1-4. Price: 290 SEK. vegetation och pollenregn i vikar av Ostersjobackenet och 22. S. Ahlner. 1948. Utbredningstyper bland nordiska barrtrads­ insjoar fran preboreal tid till nutid. (Summary: Lake stud­ lavar. (Zusammenfassung: Verbreitungstypen unter fenno­ ies in Central Sweden. Microvegetation and pollen rain in skandischen N adelbaumflechten.) ISBN 91-721 0-022-2. inlets of the Baltic basin and in lakes from Preboreal time Price: 240 SEK. to the present day.) 1957. ISBN 91-7210-038-9. Price: 23. E. Julin. 1948. Vessers udde, mark och vegetation i en 160 SEK. igenvaxande lOvang vid Bjarka-Saby. (Zusarnrnenfassung: 39. M. Fries. 1958. Vegetationsutveckling och odlingshistoria Vessers udde. Boden und Vegetation in einer verwachsen­ i V arnhemstrakten. En pollenanalytisk undersokning i Vas­ den Laubwiese bei Bjarka-Saby in 6stergotland, tergotland. (Zusammenfassung: Vegetationsentwicklung Si.idschweden.) ISBN 91-7210-023-0. Price: 240 SEK. und Siedlungsgeschichte im Gebiet von V arnhem. Eine 24. M. Fries. 1949. Den nordiska utbredningen av Lactuca pollenanalytische Untersuchung aus Vastergotland (Si.id­ alpina, Aconitum septentrionale, Ranunculus platanifolius schweden).) ISBN 91-7210-039-7. Price: 160 SEK. och Polygonatum verticillatum. (Zusarnrnenfassung: Die 40. B. Pettersson. 1958. Dynarnik och konstans i Gotlands nordische Verbreitung von Lactuca alpina.) ISBN 91- flora och vegetation. (Zusarnrnenfassung: Dynarnik und 721 0-24-9. Price: 160 SEK. Konstanz in der Flora und Vegetation von Gotland, 25. 0. Gjte revoll. 1949. Sn�leievegetasjonen i Oviksfjellene. Schweden.) ISBN 91-721 0-040-0. Price: 400 SEK. (Summary: The snow-bed vegetation of Mts Oviksfjallen, 41. E. Uggla. 1958. Skogsbrandfalt i Muddus nationalpark. Jamtland, Sweden.) ISBN 91-7210-025-7. Price: 160 (Summary: Forest fu e areas in Muddus National Park, SEK. northernSwed en.) ISBN 91-7210-041-9. Price: 160 SEK. 26. H. Osvald. 1949. Notes on the vegetation of British and 42. K. Thomasson. 1959. Nahuel Huapi. Plankton of some Irish mosses. ISBN 91-7210-026-5. Price: 160 SEK. lakes in an Argentina National Park, with notes on terres­ 27. S. Selander. 1950. Floristic phytogeography of southwest­ trial vegetation. ISBN 91-721 0-042-7. Price: 160 SEK. em Lule Lappmark (Swedish Lapland). I. 1950. ISBN 91- 43. V. Gillner. 1960. Vegetations- und Standortsuntersuch­ 721 0-027-3. Price: 240 SEK. ungen in den Strandwiesen der schwedischen Westktiste. 28. S. Selander. 1950. Floristic phytogeography of southwest­ ISBN 91-7210-043-5. Price: 240 SEK. em Lule Lappmark (Swedish Lapland). II. Karlvaxtfloran 44. E. Sj ogren. 1961. Epiphytische Moosvegetation in Laub­ i sydvastra Lule Lappmark. (Summary: Vascular flora.) waldem der Insel Oland, Schweden. (Summary: Epiphytic ISBN 91-72 10-028- 1. Price: 160 SEK. moss communities in deciduous woods on the island of 29. M. Fries. 1951. Pollenanalytiska vittnesbord om senkvartar Gland, Sweden.) ISBN 91721 0-044-3 (ISBN 91-7210- vegetationsutveckling, sarskilt skogshistoria, i nordvastra 444-9). Price: 160 SEK. Gotaland. (Zusarnmenfassung: Pollenanalytische Zeugnisse 45. G. Wistrand. 1962. Studier i Pite Lappmarks karl vaxtflora, der spatquartaren V egetationsentwicklung, hauptsachlich med sarskild hansyn till skogslandet och de isolerade der Waldgeschichte, im nordwestlichen Gotaland, fj allen. (Zusarnrnenfassung: Studien i.iber die Gefasspflan­ Si.idschweden.) ISBN 91-72 1 0-029-X. Price: 240 SEK. zenflora der Pite Lappmark mit besonderer Beri.ick­ 30. M. w� m. 1952. Rocky-shore algae in the Oregrund Archi­ sichtigung des W aldlandes und der isolierten niederen pelago. ISBN 91-7210-030-3. Price: 290 SEK. Fj elde.) ISBN 91-72 10-045-1 (ISBN 91-7210-445-7). 31. 0. Rune. 1953. Plant life on serpentines and related rocks Price: 240 SEK. in the North of Sweden. 1953. ISBN 91-7210-03 1-1. Price: 46. R. lvarsson. 1962. Lovvegetation i Mollosunds socken. 240 SEK. (Zusarnmenfassung: Die Laubvegetation im Kirchspiel 32. P. Kaaret. 1953. Wasservegetation der Seen Orlangen und Mollosund, Bohuslan, Schweden.) ISBN 91-7210-046-X Trehomingen. ISBN 91-7210-032-X. Price: 160 SEK. (ISBN 91-721 0-446-5). Price: 160 SEK. 33. T. E. Hasselrot. 1953. Nordliga lavar i Syd- och Mellan­ 47. K. Thomasson. 1963. Araucanian Lakes. Plankton studies sverige. (Nordliche Flechten in Si.id- und Mittelschweden.) in North Patagonia, with notes on terrestrial vegetation. ISBN 91-7210-033-8. Price: 240 SEK. ISBN 91-721 0-047-8. Price: 240 SEK. 34. H. Sj Ors. 1954. Slatterangar i Grangarde Finnrnark. (Sum­ 48. E. Sj ogren . 1964. Epilitische und epigaische Moosvege­ mary: Meadows in Grangarde Finnrnark, SW Dalama, tation in Laubwaldem der Insel Gland, Schweden. (Sum­ Sweden.) ISBN 91-7210-034-6. Price: 160 SEK. mary: Epilithic and epigeic moss vegetation in deciduous 35. S. Kilander. 1955. Karlvaxtemas ovre granser pa fj all i woods on the island of Gland, Sweden.) ISBN 91-7210- sydvastra Jamtland sarnt angransande delar av Harjedalen 048-6 (ISBN 91-7210-448- 1). Price: 240 SEK. och Norge. (Summary: Upper limits of vascular plants on 49. 0. Hedberg. 1964. Features of afroalpine plant ecology. mountains in southwesternJamtland and adjacent parts of (Resume fran�ais.) ISBN 91-721 0-049-4 (ISBN 91-7210- Harjedalen (Sweden) and Norway.) ISBN 91-7210-035-4. 449-X). Price: 240 SEK. Price: 240 SEK. 50. The Plant Cover of Sweden. A study dedicated to G. Einar 36. N. Quennerstedt. 1955. Diatomeema i Langans sjo­ Du Rietz on his 70th birthday by his pupils. 1965. ISBN vegetation. (Summary: Diatoms in the lake vegetation of 91-7210-050-8. Price: 4112 SEK.

Acta Phytogeogr. Suec. 82 Svenska Viixtgeografiska Siillskapet 63

51. T. Flensburg. 1967. Desmids and other benthic algae of 240 SEK. Lake Kavsjon and Store Mosse. SW Sweden. ISBN 91- 67. S. Tuhkanen. 1980. Climatic parameters and indices in 7210-05 1-6 (ISBN 91-7210-451-1). Price: 240 SEK. plant geography. ISBN 91-721 0-067-2 (ISBN 91-7210- 52. E. Skye. 1968. Lichens and air pollution. A study of crypto­ 467-8). Price: 240 SEK. gamic epiphytes and environment in the Stockholm region. 68. Studies in plant ecology dedicated to Hugo Sjors. E. Sjogren ISBN 91-7210-052-4 (ISBN 91-7210-452-X). Price: 240 (ed.) 1980. ISBN 91-721 0-068-0 (ISBN 91-721 0-468-6). SEK. Price: 290 SEK. 53. J. Lundqvist. 1968. Plant cover and environment of steep 69. C. Nilsson. 1981. Dynamics of the shore vegetation of a hillsides in Pite Lappmark. (Resume: La couverture vege­ North Swedish hydro-electric reservoir during a 5-year tale et !'habitat des flancs escarpes des collines de Pite period. ISBN 91-721 0-069-9 (ISBN 91-7210-469-4 ). Price: Lappmark.) ISBN 91-7210-053-2 (ISBN 91-7210-453-8). 240 SEK. Price: 240 SEK. 70. K. Wa renberg. 1982. Reindeer forage plants in the early 54. Conservation of Vegetation in Africa South of the Sahara. grazing season. Growth and nutritional content in relation Proceedings of a symposium held at the 6th Plenary meeting to climatic conditions. ISBN 91-721 0-070-2 (ISBN 91- ofthe AETFAT, UppsalaSept. l2-16, 1966. 1968.ISBN91- 721 0-470-8). Price: 240 SEK. 721 0-054-0 (ISBN 91-721 0-454-6). Price: 290 SEK. 71. C. Johansson. 1982. Attached algal vegetation in running 55. L. -K. Konigsson. 1968. The Holocene history of the Great waters of Jamtland, Sweden. ISBN 917210-07 1-0 (ISBN Alvar of bland. ISBN 91-7210-055-9 (ISBN 91-72 10- 91-7210-47 1-6). Price: 240 SEK. 455-4). Price: 290 SEK. 72. E. Rosen. 1982. Vegetation development and sheep graz­ 56. H. P. Hallberg. 1971. Vegetation auf den Schalenablager­ ing in limestone grasslands of South bland, Sweden. ISBN ungen in Bohuslan, Schweden. (Summary: Vegetation on 91-7210-072-9 (ISBN 91-721 0-472-4). Price: 290 SEK. shell deposits in Bohuslan, Sweden.) ISBN 91-721 0-056- 73. Zhang Liquan. 1983. Vegetation ecology and population 7 (ISBN 91-721 0-456-2). Price: 240 SEK. biology of Fritillaria meleagris L. at the Kungsangen Na­ 57. S. Fransson. 1972. Myrvegetation i sydvastra Varmland. ture Reserve, easternSweden. ISBN 91-7210-073-7 (ISBN (Summary: Mire vegetation in southwestern Vlirmland, 91-7210-473-2). Price: 240 SEK. Sweden.) ISBN 91-721 0-057-5 (ISBN 91-7210-457-0). 74. I. Backeus. 1985. Aboveground production and growth Price: 240 SEK. dynamics of vascular bog plants in central Sweden. ISBN 58. G. Wa llin. 1973. Lovskogsvegetation i Sjuharadsbygden. 91-7210-074-5 (ISBN 91-721 0-474-0). Price: 240 SEK. (Summary: Deciduous woodlands in Sjuharadsbygden, 75. E. Gunnlaugsd6ttir. 1985. Composition and dynamical Vastergotland, southwestern Sweden.) ISBN 91-7210- status of heathland communities in Iceland in relation to 058-3 (ISBN 91-7210-458-9). Price: 240 SEK. recovery measures. ISBN 91-7210-075-3 (ISBN91-7210- 59. D. Johansson. 1974. Ecology of vascular epiphytes in 475-9). Price: 240 SEK. West African rainfor est. (Resume: Ecologie des epiphytes 76. Plant cover on the limestone Alvar on bland. Ecology­ vasculaires dans la foret dense humide d' Afrique Sociology-Taxonomy. E. Sjogren (ed.) 1988. ISBN 91- occidentale.) ISBN 91-7210059-1 (ISBN 91-721 0-459- 721 0-076- 1 (ISBN 91-7210-476-7). Price: 320 SEK. 7). Price: 290 SEK. 77. A. H. Bja mason. 1991. Vegetation on lava fields in the 60. H. Olsson. 1974. Studies on South Swedish sand vegeta­ Hekla area, Iceland. ISBN 91-7210-077-X (ISBN 91- tion. ISBN 91-721 0-060-5 (ISBN 91-721 0-460-0). Price: 721 0-477-6). Price: 290 SEK. 240 SEK. 78. I. Wa llentinus & P. Snoeijs (eds.). 1992. Algological 61. H. Hyttebom. 1975. Deciduous woodland at Andersby, studies of Nordic coastal waters - A festschrift to Prof. easternSweden. Above-ground tree and shrub production. Mats Wrem on his 80th birthday-. ISBN 91-7210-078-8 ISBN 91-7210-06 1-3 (ISBN 91-721 0-46 1-9). Price: 240 (ISBN 91-7210-478-3 ). Price: 290 SEK. SEK. 79. Tamrat Bekele. 1993. Vegetation ecology ofremnant Afro­ 62. H. Persson. 1975. Deciduous woodland at Andersby, east­ montane forests on the Central Plateau of Shewa, Ethiopia. em Sweden. Field-layer and below-ground production. ISBN 91-7210-079-6 (ISBN 91-7210-479- 1). Price: 290 ISBN 91-7210-062- 1 (ISBN 91-721 0-462-7). Price: 160 SEK. SEK. 80. M. Diekmann. 1994. Deciduous forest vegetation in Boreo­ 63. S. Brakenhielm. 1977. Vegetation dynamics of afforested nemoral Scandinavia. ISBN 91-721 0-080-X (ISBN 91- farmland in a district of south-eastern Sweden. ISBN 91- 72 10-480-5). Price: 290 SEK. 7210-063-X (ISBN 91-7210-463-5). Price: 240 SEK. 81. Plant root systems and natural vegetation. 1996. H. Persson 64. M. Y Ammar. 1978. Vegetation and local environment on & I.O. Baitulin (eds.) ISBN 91-721 0-08 1-8 (ISBN 91- shore ridges at Vickleby, bland, Sweden. An analysis. 7210-08 1-3). Price: 290 SEK. ISBN 91-721 0-064-8 (ISBN 91-7210-464-3). Price: 240 82. Middle oroarctic vegetation in Finland and middle-north­ SEK. em arctic vegetation on Svalbard 1996. R. Virtanen & S. 65. L. Kullman. 1979. Change and stability in the altitude of Eurola (eds.) ISBN91-7210-082-6. (9 1-721 0-482-5). Price: the birch tree-limit in the southernSwedish Scandes 1915- 290 SEK. 1975. ISBN 91-721 0-065-6 (ISBN 91-7210-465-1). Price: 240 SEK. A limited number of cloth-bound copies of Acta 44, 45, 46, 48, 66. E. Wa ldemarson Jensen. 1979. Successions in relationship 49, 51,52, 53, 56, 57, 61, 63, 66, 67, 68, 69, 70, 71, 72, 73, 74, to lagoon development in the Laitaure delta, North Swe­ 75, 76, 77, 78, 79, 80 and 81 is available at an additional cost of den. ISBN 91-721 0-066-4 (ISBN 91-721 0-466-X). Price: 75 SEK per volume. (Use ISBN n°S. within brackets to order.)

Acta Phytogeogr. Suec. 82 64 Svenska Viixtgeografiska Siillskapet

STUDIES IN PLANT ECOLOGY (VOL. 1-19)

1. S. Brakenhielm & T Ingelog. 1972. Vegetationen i Kungs­ 9. J. Lundqvist & G. Wistrand. 1976. Strandflora inom ovre hamn-Morga naturreservat med forslag till skotselplan. och mellersta Skelleftealvens vattensystem. Med en sam­ (Summary: Vegetation and proposed management in the manfattning betraffande botaniska skyddsvarden. (Sum­ Kungshamn-Morga Nature Reserve south of Uppsala.) mary: Riverside vascular flora in the upper and middle ISBN 91-7210-801 -0. Price: 112 SEK. catchment area of the River Skelleftealven, northern Swe­ 2. T. Ingelog & M. Risling. 1973. Kronparken vid Uppsala, den.) ISBN 91-7210-809-6. Price: 112 SEK. historik och bestandsanalys av en 300-ang tallskog. (Sum­ 10. A. Mii.ller-Haeckel. 1976. Migrationsperiodik einzelliger mary: Kronparken, history and analysis of a 300-year old Algen in Fliessgewassern. ISBN 91-7210-8 10-X. Price: pinewood near Uppsala, Sweden.) ISBN 91-7210-802-9. 112 SEK. Price: 112 SEK. 11. A. Sj odin . 1980. Index to distribution maps of bryophytes 3. H. Sjiirs et al. 1973. Skyddsvarda myrar i Kopparbergs Hin. 1887-1975. 1. Musci. (hard-bound). ISBN 91-7210-81 1-8. [Summary: Mires considered for protection in Kopparberg Price: 160 SEK. County (Prov. Dalama, Central Sweden.)] ISBN 91-7210- 12. A. S} Odin. 1980. Index to distribution maps of bryophytes 803-7. Price: 112 SEK. 1887- 1975. II. Hepaticae. (hard-bound). ISBN 91-7210- 4. L. Karlsson. 1973. Autecology of cliff and scree plants in 812-6. Price: 112 SEK. Sarek National Park, northern Sweden 1973. ISBN 91- 13. 0. Eriksson, T Palo & L. Soderstrom. 1981. Renbetning 721 0-804-5. Price: 160 SEK. vintertid. Undersokningar rorande svensk tarnrensnarings­ 5. B. Klasvik. 1974. Computerized analysis of stream algae. ekologi under snoperioden. ISBN 91-7210-81 3-4. Price: ISBN 91-7210-805-3. Price: 112 SEK. 112 SEK. 6. Y. Dahlstrom-Ekbohm. 1975. Svensk miljovards- och 14. G. Wistrand. 1981. Bidrag till Pite lappmarks vaxtgeo­ omgivningshygienlitteratur 1952-1972. Bibliografi och grafi. ISBN 91-7210-8 14-2. Price: 112 SEK. analys. ISBN 91-7210-806-1. Price: 112 SEK. 15. T. Karlsson. 1982. Euphrasia rostkoviana i Sverige. ISBN 7. L. Rodenborg. 1976. Bodennutzung, Pflanzenwelt und 91-7210-81 5-0. Price: 160 SEK. ihre Verlinderungen in einem alten Weidegebiet auf Mit­ 16. Theory and Models in Vegetation Science: Abstracts. ISBN tel-Oland, Schweden. ISBN 91-7210-807-X. Price: 112 91-7210-816-9. 1985. Price: 160 SEK. SEK. 17. /. Backeus. 1988. Mires in the Thaba-Putsoa Range of the 8. H. Sj ors & Ch. Nilsson. 1976. Vattenutbyggnadens effek­ Maloti, Lesotho. ISBN 91-7210-8 17-7. Price: 160 SEK. ter pa levande natur. En faktaredovisning overvagande 18. Forests of the world - diversity and dynamics (Abstracts) fran Umealven. (Summary: Bioeffects of hydroelectric 1989. (Ed. E. Sjogren) ISBN 91-7210-81 8-5. Price: 290 development. A case study based mainly on observations SEK. along the Ume River, northern Sweden.) ISBN 91-7210- 19. E. Sj ogren. 1994. Changes in the epilithic and epiphytic 808-8. Price: 160 SEK. moss cover in two deciduous forest areason the island of bland (Sweden). - A comparison between 1958-1 962 and 1988-1 990. ISBN 91-7210-819-3. Price: 200SEK.

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Acta Phytogeogr. Suec. 82