ACTA UNIVERSITATIS UPSALIENSIS ACTA PHYTOGEOGRAPHICA SUECICA 76

Plant cover on the limestone Alvar of Oland Ecology - Sociology - Taxonomy

Editor Erik Sjogren

UPPSALA 1988

ACTA UNIVERSITATIS UPSALIENSIS

ACTA PHYTOGEOGRAPHICA SUECICA 76

Plant cover on the limestone Alvar of Oland Ecology - Sociology - Taxonomy

Editor Erik Sjogren

Almqvist & Wiksell International, Stockholm UPPSALA 1988 The publication of this volume has been economically supported by the "Axel och Margaret Ax:son Johnsons stiftelse".

ISBN 91-7210-076-1 (paperback) ISBN 91-7210-476-7 (cloth) ISSN 0084-5914

Respective author 1988 ©

Drawing of Hel ianthemum oelandicum on cover by Marie Widen.

Edidit: Svenska Vaxtgeografiska Sallskapet Box 559, 751 22 Uppsala

Editor: Erik Sjogren Technical editor: Gunnel Sjors

Phototypesetting: Textgruppen i U ppsala AB Printed in Sweden 1988 by Centraltryckeriet AB, Bon\s

Acta phytogeographica suecica 76 Contents

Studies of vegetation on Oland-changes and development during a century. By Erik Sj ogren . 5

Limiting factors on seed production in Crepis tectorum ssp. pumila. By Stejan Andersson. 9

The dry alvar grasslands of Oland: ecological amplitudes of plant spe­ cies in relation to vegetation composition. By Karin Bengtsson, Honor C. Prentice, Ej vind Rosen, Roland Moberg & Erik Sj ogren . 21

Calcicolous lichens and their ecological preferences on the Great Alvar of Oland. By Lars Froberg. 47

Floristic diversity and guild structure in the grasslands of Oland's Stora Alvar. By Eddy van der Maarel. 53

The effects of colonizing shrubs (Juniperus communis and Potentilla fructicosa) on species richness in the grasslands of Stora Alvaret, Oland. By Marcel Rejmdnek & Ejvind Rosen. 67

Das Naturschutzgebiet in Gosslunda. By Lars Rodenborg. 73

Shrub expansion in alvar grasslands on Oland. By Ej vind Rosen. 87

Plant cover in alvar junipers on Oland. Distribution features correlated to shrub size and shape. By Ej vind Rosen & Erik Sj ogren . 101

Reproductive regeneration in grazed and ungrazed limestone grassland communities on Oland. Preliminary results. By Graciela Rusch. 113

Biomass structure of limestone grasslands on Oland in relation to graz­ ing intensity. By Argenta Titlyanova, Gracie/a Rusch & Eddy van der Maarel. 125

Partitioning of variation in pubescens of a dwarf shrub, Helianthemum oelandicum. By Bj orn Widen . 135

Acta phytogeographica suecica 76 Abstract

Plant cover on the limestone alvar of Oland. Ecology, sociology, taxonomy. - Acta phytogeogr. suec. 76, Uppsala, 160 pp., ed. by Erik Sj<>gren. ISBN 91-7210-076-1.

A thematic volume on plants and vegetation on the limestone alvars of the Island of Oland, Sweden, is presented. Papers present recent results of botanical research (after 1982) in vari­ ous fields such as ecology, sociology and taxonomy. The continuous variation in pubescence of Helianthemum oelandicum is studied (Widen, B.). The most important bottlenecks in seed production of Crepis tectorum var. pumila are traced (Andersson, S.). Consequences of grazing of the alvar are discussed considering biomass structure (Titlyanova, A., Rusch, G. & van der Maarel, E.), shrub expansion (Rosen, E.) and reproductive regeneration (Rusch, G.). The pronounced decrease in species richness following an invasion of junipers and Potentilla fruticosa is described (Rejmanek, M. & Rosen, E.). The alvar vegetation of Oland is famous for a large number of species being either at the limits of their geographic ranges or characterized by highly disjunct distributions. Ecological amplitudes of such species within alvar plant communities of dry grasslands are studied (Bengtsson, K., Prentice, H. C., Rosen, E., Moberg, R. & Sj<>gren, E.). Studies on calcicolous lichens and bryophytes in the alvar vegetation are limited to the lichen flora on limestone rocks (Fr<>berg,L.) and bryophytes within juniper shrubs (Rosen, E. & Sj<>gren, E.) and in dry grasslands (Bengtsson, K. et al.). A comprehensive enumeration of vascular plant taxa (388) of dry habitats on Gland's Stora Alvar is given (van der Maarel, E.), these taxa being subjected to spectrum analyses regarding syntaxonomy, chorology, life-form, growth form and strategy type. The vegetation of juniper shrubs and juniper scrub is studied (Rosen, E. & Sj<>gren, E.) and correlated to variables such as shrub height, area, cover and plot positions. The survival of alvar plants within the shrubs is discussed, also from the nature conservation point Qf view. The management and actual status of grazed vegetation units in a protected area on Stora Alvaret have been comprehensively treated (Rodenborg, L.).

Keywords: alvar, A venetum, calcicolous lichens, calcicolous bryophytes, chorological spec­ trum, diversity, disjunct species, grazing, growth form, guild, Helianthemum oelandicum, juniper scrub, life-form, limestone grasslands , seed production, shrub expansion, strategy type, syntaxonomical spectrum.

Acta phytogeographica suecica 76 Studies of vegetation on bland­ changes and development during a century Erik Sjogren

The botanical exploration of the calcareous island the most unusual edaphic and climatic conditions of Gland in the Baltic started in 1741 when Carl of the alvar and their consequences for the com­ Linnaeus carried out his famous 'Glandska resa' position of its vegetation. Grevillius treated not (Linnaeus, C. 1745). During his stay on Gland, only the morphology and anatomy of typical alvar Linnaeus recorded 311 species of vascular plants plants but also the peculiar forms of mainland (cf. Sjostrand 1850), at that time a remarkably species participating in the calcicolous vegetation large number considering the taxonomical knowl­ of the island. This was a new approach. edge available. In 1821, Goran Wahlenberg iden­ A doctoral thesis on the vegetation of Gland was tified one of the most peculiar members of the published by Hemmendorff (1897). He described flora of Gland, the southeast European Plantago especially the alvar vegetation, which was arranged tenuiflora. More important, he became the first in different formations, using what then was a botanist to describe the Alvar of Gland, giving young terminology of the developing plant sociol­ comparisons to both African and Alpine condi­ ogy. He also described the relation between vegeta­ tions and vegetation. tion types of the alvar such as between shallow Further botanical investigations on Gland until lakes ('vatar') and mires, from a dynamic point of the beginning of this century were mainly concen­ view, which was a fairly modern approach at that trated on the hunting of species new to the island. time. Lots of valuable information was given by This floristic work was carried out by many skilled Hemmendorff, for example, in his description of botanists. Some of them spent decades of their grazing pressure on the alvar and cultivation of the lives with these floristic studies. In the 1930s at alvar margins ('horvor'). Furthermore, it is inter­ least 1100 species of vascular plants were esting to note that the most common tree forma­ documented from the island. One of the encourag­ tion on bland at that time was the wooded ing conditions inspiring so many botanists to go meadow. Hemmendorff was a pioneer in pointing plant-hunting on Gland was the fairly good chance out the vegetational and floristic differences be­ of finding species new to the country or at least tween the Stora Alvaret of southern bland, the new localities of species with widely disjunct Scan­ Borgholm alvar with locally high and dense juniper dinavian or even European distribution. The scrub, and the more species-poor alvar areas on results and the principal participants of the northernmost Gland. floristic research on Gland have been given a During the first twenty years of this century, detailed description by Ake Lundqvist in the studies on the bland vegetation became rapidly in­ largely revised and extended 2nd edition of tensified and also increasingly varied. The ecology Sterner's "Flora der Insel Gland" (1986). of the Swedish alvar plants was treated in a com­ prehensive way in a doctoral thesis by Witte Here I shall deal quite briefly with the start and de­ (1906). His publication greatly widened our knowl­ velopment of research on structure and ecology of edge of the alvar vegetation of Oland, which be­ vegetation on the island of Gland. came for the first time also compared to similar In 1896 Grevillius published his work on vegetation types in other parts of the country. He xerophilous vegetation on Gland. This work be­ gave comprehensive information on the known came a starting point for further investigations on European distribution of the most peculiar alvar

Acta phytogeographica suecica 76 6 Erik Sj ogren plants. Edaphic and climatic conditions in relation one of this country's most prominent plant to alvar vegetation became more efficiently treated sociologists, working with widely different types of than before. Witte summarized his description of vegetation in Scandinavia. He also described (Du the alvar vegetation, including important ideas on Rietz 1923) the famous Helianthemum oelandicum

its steppe or heath character. In his opinion the · associations of Gland, showing their different alvar vegetation has a steppe-like character and has composition on the southern and northern alvars nothing in common with typical heath vegetation, of the island. an approach maintained since then. His descrip­ During a time period of almost 30 years, until tion represents a modernized view and is worth the early 1950s, the most prosperous and intense quoting: ''. . . alfvarvegetationen ar en i ett mer investigations of vegetation and flora on Gland eller mindre insulart klimat forekommande af were carried out by R. Sterner. Already in 1926 he edafiska faktorer betingad steppvegetation, som published a comprehensive description of the har en hel del drag gemensamma med den vegetation types of Gland. Sterner's "Flora der In­ sydosteuropeiska steppvegetationen och afven sel Gland" (1938) became the Bible of all botanists foreter migon likhet med den hognordiska visiting the island for as long as almost half a cen­ fj allhedens (fjallsteppens?) vegetation, men dar­ tury. This flora contains 295 distribution maps of emot ingen eller atminstone en hogst obetydlig vascular plants. It also includes more or less sadan med den akta hedvegetationen" (Witte detailed autecological descriptions referring to all 1906, p. 17). (transl. ...the 'alvar' vegetation is species found on the island. Sterner's very detailed a steppe vegetation conditioned by edaphic factors information on earlier and recent records of in a more or less insular climate and which has sev­ species provided most valuable aspects on a flora eral features in common with the southeast Euro­ and vegetation subject to changes as a consequence pean steppe vegetation and also some similarities of rapid and far-reaching changes of landuse. with the mountain vegetation in the far north, but In 1950 botanists especially concerned with the no or at least a highly insignificant similarity with alvar vegetation of Gland got a most comprehen­ true heath vegetation.) sive sociological work to consult (Albertson 1950), In Witte's almost forgotten and certainly which is still in its main differentiation of associa­ underestimated publication the alvar vegetation tions a pioneer and a frequently quoted publica­ was described in an unusually precise and detailed tion. In the 1940s, Albertson was the leading way, widely different from the short description specialist on calcicolous vegetation in this country. given by the "father of plant geography", Goran He was the first plant sociologist to differentiate Wahlenberg (1821). It may be added that the alvar the alvar communities using also the lichens and vegetation became for the first time more com­ mosses of the bottom layer, completely listed in his pletely described in Witte's publication of 1906 as tables. Albertson's knowledge of the small numerous lichens and mosses were mentioned and acrocarpous mosses of calcareous soils was most included in his plant communities. remarkable, since these generally provide numer­ The correlations between environment and flora ous difficulties in determination. and vegetation on the alvar were continued by Investigations on the vegetation of Gland within Falck (1913). He stressed, for example, the import­ the time period of 1950 to approximately 1970 be­ ance of previously unmentioned environmental came less intense than expected, considering the conditions such as frostheaving. His main results rapid methodological development in plant were reached, however, in a presentation of the ecology and sociology. However, the macrophyte high osmotic values of several alvar plants such as vegetation of lakes and temporary pools on the Helianthemum oelandicum. Falck's investigations alvar got its description (Horn af Rantzien 1951). in this matter were probably inspired by Fitting Some ecosociological papers on deciduous forest (1911) who studied the water support of desert vegetation of the island were published (Sjogren plants. 1954, 1961, 1964). They were mainly concerned In the 1920s, work in the field of plant sociology with the earlier not differentiated bryo-communi­ became intense in Sweden. G.E. Du Rietz became ties of the large number of forest types of the

Acta phytogeographica suecica 76 Studies of vegetation on 0/and 7

island. The alvar obviously did not attract modern agglomerative classification technique to botanists to continue the work carried out by distinguish plant communities on bland. Albertson, but the history of its vegetation was in­ vestigated by Konigsson (1968). The 1980s meant a rapid expansion of widely dif­ ferent botanical investigations on bland, mainly During the 1960s, large areas of the southern Stora on the Alvar. Several of the investigation projects Alvaret became exploited for sheep grazing. have been initiated by Eddy van der Maarel (In­ Damages, as a consequence of locally severe stitute of Ecological Botany, Uppsala University). overgrazing, gradually became prominent. These The present volume of Acta phytogeographica conditions inspired the start of new investigations suecia provides some information on modern ap­ aimed to provide suggestions for protection of proaches in plant ecology, taken in its widest sense. parts of the Stora Alvaret, or at least recommenda­ It also indicates the rapidly growing multinational tions for suitable grazing pressure. The produc­ interest among botanists to study some of tivity of different types of alvar communities was Europe's most valuable and peculiar vegetation investigated. The susceptibility of some typical types, found on the southern alvar of bland. alvar species towards grazing also had to be Since the 1960s the Uppsala University Ecologi­ revealed. These investigations which started in cal Research Station at blands Skogsby has be­ 1969 (cf. Ljung 1970, Sjogren 1972, Rosen & Sjo­ come an increasingly valuable resource for botan­ gren 1973, 1974) continued until the beginning of ists working on the island. The excellent equipment the 1980s (Rosen 1982). During more recent years and the hospitality at the Ecological Station has Rosen continued his alvar studies, which lately facilitated the work of all participants of this vol­ have become extended to problems linked to ume in many ways. The internationalized teams of changes of alvar grasslands as a consequence of in­ biologists have found the Ecological Station at vasion of shrubs, mainly juniper, when grazing blands Skogsby an important base, not only from pressure is kept too low (Rosen 1988, Rosen & Sjo­ the practical point of view when treating. various gren 1988). sorts of often voluminous field material, but also Several valuable aspects on developing vegeta­ for valuable discussions of results obtained and tion types on bland appeared in Rodenborg's methods used. publications of the 1960s and 1970s, especially in his doctoral thesis of 1976. Work on conservation of vegetation types on bland became intensified in the 1950s. In many References cases it became obvious that methods for conserva­ tion had to become linked to results obtained from Albertson, 1950. Das grosse siidliche Alvar der lnsel N. studies of dynamics of vegetation. Dynamic bland. Eine pflanzensoziologische Ubersicht. - features of vegetation in deciduous forests on Svensk bot. Tidskr. 44: 269-331. Ammar, M. Y. 1978. Vegetation and local environment bland were studied in 1955-1980 (Sjogren 1964, on shore ridges at Vickleby, bland, Sweden. An Ekstam & Sjogren 1973). These studies principally analysis. - Acta phytogeogr. suec. 64: 1-94. aimed to distinguish changes of vegetation taking Du Rietz, G. E. 1923. Studien iiber die Helianthemum place during years with fairly stable environmental oelandicum-Assoziationen auf bland. - Svensk bot. conditions from changes induced by short-term or Tidskr. 17: 435-446. Ekstam, U. & Sjogren, E. 1973. Studies on past and pre­ long-term changes of conditions, such as single sent changes in deciduous forest vegetation on climatically extreme years or clearings. bland. - Zoon, Uppsala. Suppl. 1: 123-135. The vegetation on the Ancylus, Litorina and Falck, K. 1913. Iakttagelser ofver alfvarvegetationen pa more recent shore ridges at Vickleby on bland was bland, sarskildt med hansyn till alfvarvaxternas studied by Ammar (1978). Factors controlling the osmotiska tryck. - Svensk bot. Tidskr. 7: 337-362. Fitting, H. 1911. Die W asserversorgung und die vegetation as well as the differentiation of phyto­ osmotischen Druckverhaltnisse der Wiistenpflanzen. sociological units were treated using multivariate - Z. Bot. 3. analyses. Ammar was the first botanist to use a Grevillius, A. Y. 1896. Morphologisch-anatomische

Acta phytogeographica suecica 76 8 Erik Sj ogren

Studien iiber die xerophile Phanerogamenvegetation Rosen, E. & Sjogren, E. 1988. Plant cover in alvar der Insel Gland. - Bot. Jb. 23: 24-108. junipers on Gland. Distribution features correlated Hemmendorff, E. 1897. Om Glands vegetation. Nagra to shrub size and shape. - Acta phytogeogr. suec. utvecklingshistoriska bidrag. - Akad. afh. Uppsala. 76. 53 pp. Sjogren, E. 1954. Studien iiber die Gkologie der Horn af Rantzien, H. 1951. Macrophyte vegetation in radikanten Moosvereine in W aldsgebieten des Kirch­ lakes and temporary pools of the alvar of Gland, spiels Vickleby, Gland. - Oikos 5: 101-133. South Sweden. - Svensk bot. Tidskr. 45: 72-120, - 1961. Epiphytische Moosvegetation in Laubwaldern 483-497. der Insel Gland (Schweden). - Acta phytogeogr. suec. 1-149. Konigsson, L.-K. 1968. The holocene history of the 44: great alvar of Gland. - Acta phytogeogr. suec. 55: - 1964. Epilithische und epigaische Moosvegetation in 1-172. Laubwaldern der Insel Gland (Schweden). - Acta Linnaeus, 1745. earl Linnaei-olandska och phytogeogr. suec. 48: 1-184. c. gothlandska resa-forrattad Ahr 1741. - Stockholm - 1972. Naturvardsprojektet samband vegetation­ & Uppsala. betning pa Glands Stora Alvar. - Vaxtbiol. inst. Ljung, E. 1970. Artbytet omkring fallor och farhur pa Uppsala, 68 pp. (mimeogr.) Glands Stora Alvar. - Vaxtbiol. inst. Uppsala. 40 Sjostrand, M. G. 1850. Enumerativo plantarum on pp. (mimeogr.) Glandia sponte nascentium. - Nova Acta R. Soc. Rodenborg, L. 1976. Bodennutzung, Pflanzenwelt und Scient. Upsal 14: 455-516. ihre Veranderungen in einem alten Weidegebiet auf Sterner, R. 1926. Glands vaxtvarld. - Sodra Kalmar Mittel-Gland, Schweden. - Vaxtekol. stud. 7: lan. Ill. Kalmar. 237 pp. 1-210. - 1938. Flora der Insel Gland. - Acta phytogeogr. Rosen, E. 1982. Vegetative development and sheep graz­ suec. 9: 1-169. ing in limestone grasslands of South Gland, Sweden. - 1986. (>lands karlvaxtflora (ed. A. Lundqvist). 2nd - Acta phytogeogr. suec. 72: 1-104. rev. ed. of 'Flora der lnsel Gland' 1938. - Lund. - 1988. Shrub expansion in alvar grasslands on Gland. 400 pp. -Acta phytogeogr. suec. 76. Wahlenberg, G. 1821. Ytterligare anmarkningar om Rosen, E. & Sjogren, E. 1973 . Sheep grazing and Glands natur. - K. svenska Vetensk. Akad. Handl. changes of vegetation on the limestone heath of 1821: 305-3 19. Gland. - Zoon, Uppsala. Suppl. 1: 137-151. Witte, H. 1906. Till de svenska alfvarvaxternas ekologi. Rosen, E. & Sjogren, E. 1974. Samband vegetation­ Akad. avh. Uppsala. 119 pp. betning pa Glands Stora Alvar. Slutredogorelse, 7- 46/73.- Vaxtbiol. inst. Uppsala. 54 pp. (rnimeogr.)

Acta phytogeographica suecica 76 Limiting factors on seed production in Crepis tectorum ssp. pumila Stefan Andersson

Abstract

Andersson, S. 1988. Limiting factors on seed production in Crepis tectorum ssp. pumila. - Acta phytogeogr . suec. 76, Uppsala. ISBN 91-7210-076-l.

I examined how various components of yield in the winter annual Crepis tectorum ssp. pumila, were affected by variation in availability of physiological resources and pollen. Heads floweringearly gave matured seeds of higher quality than heads flowering late in the dry sum­ mer of 1986. Head number and the proportion of inflorescences that plants were able to develop to the fruit-stage were higher in 1987 than in 1986. On the other hand, head size, percentage seed-set and seed-quality were lower in 1987. Rosette size, head number and head size were all positively correlated and decreased when percentage grass cover and soil depth increased. The proportion and quality of seeds matured per head were not affected by these factors. In 1987, addition of fertilizer increased the number and size of heads initiated, percentage seed-set and seed-quality. Furthermore, by removing all but one head on a plant it was possible to increase percentage seed-set in the remaining one. The effect of halving the number of rosette leaves on seed-set was low in both years. Cultivation in a greenhouse (excess water and nutrients) increased head number considerably while the effect on other traits was low. Bagging and crossing experiments showed that plants used in this study were partly self­ sterile and thus dependent on external pollen transfer to set seed. However, in the field, seed production was probably limited by resources rather than by pollen.

Stefan Andersson, Department of Systematic Botany, Vallgatan 20, 223 61 Lund, Sweden. 0.

Introduction regulated (flower determination, fruit or seed de­ velopment) may not only be the stage when the en­ A plant's seed production is usually constrained by vironment is most limiting. It may also reflect environmental factors at one or several develop­ when it is most economic for a plant to adjust the mental stages. Insufficient resources (light, nu­ final seed production to prevailing conditions trients, water) commonly set a limit to the number (Lloyd 1980, Lloyd et al. 1980). Secondly, herma­ of flowers and ovules that a plant can initiate. phroditic plants may 'over-initiate' flowers or Plants may also abort flowers, fruits or seeds due ovules to increase pollen dissemination (male to lack of resources (Lloyd 1980, Lloyd et al. 1980, fitness), to provide an opportunity for selective Stephenson 1981). Finally, insufficient pollination abortion, or to increase the possibility to mature a sometimes limits seed production (Bierzychudek maximum number of seeds when conditions are 1981). The relative importance of these constraints unusually favourable (Willson & Price 1977, Ste­ probably reflect when natural selection is most in­ phenson 1979, Stephenson & Bertin 1983, Waser tense on characters associated with reproduction. 1983). Failure of a flower to produce seeds may For example, when fecundity is pollination­ not be too serious when these extra functions are limited, plants may be selected to increase their ca­ taken into account. This probably relaxes selection pacity for automatic self-pollination or to modify for maximum seed production in all flowers on a the floral display to attract more pollinators. How­ plant. ever, it is important to separate limitations due to In this study, I examined the extent of en­ lack of resources and pollination from possible vironmental limitation on seed production in a adaptive functions (Steph�nson 1981). Firstly, the determinate flowering plant, Crepis tectorum ssp. stage when the seed production is most strongly pumila on the Baltic island of Gland. More

Acta phytogeographica suecica 76 10 Stefa n Andersson

1 specifically I investigated how various traits associated with flower production and seed-set were affected by: 3 (1) year-to-year variation in weather conditions. (2) variation in the quality of the microhabitat as determined by grass cover and soil depth. (3) experimental manipulations of availability of pollen (exclusion of pollinators; hand-pollination) and nutritional resources (cultivation in favourable conditions in a greenhouse; fertilization; defolia­ tion; removal of developing ovules and seeds on the same plant). The main objective was to identify the stage at which the environment is most limiting for female Fig. 1. A schematic drawing of a plant of Crepis tee­ forum spp. pumila. Numbers refer to values assigned to reproduction in order to reveal the relative strength each of the head positions. They reflect roughly the of natural selection on various reproductive char­ order in which the heads flower on the plant. acters. I also discuss possible adaptive aspects of the observed seed-set pattern. number is therefore determined relatively early and cannot be continually adjusted to the prevailing

· conditions once flowering has begun. The number The plant and the area of buds that develop to inflorescences may, how­ ever, be lower. Each head has a variable number of Crepis tectorum L. (Asteraceae) is a highly hermaphroditic flowers. The most common insect polymorphic and widespread annual or biennial visitors are flies and solitary bees (pers. obs.). Each plant native to Eurasia. Besides weed ecotypes, flower develops into a one-seeded fruit (achene). others are adapted to more natural habitats (Bab­ The fruits are wind-dispersed and shed two or cock 1947). Characteristic forms of low stature are three weeks after flowering. In the following text, known from dry areas on Baltic islands. One very fruits will be termed 'seeds'. distinct ecotype is endemic on alvars on Oland The island of Oland is situated in the southern (ssp. pumila (Liljeblad) Sterner, hereafter referred Baltic, east of the Swedish mainland, consisting of to as Crepis). It usually occurs on shallow soil in a plateau of Ordovician limestone. Large parts of a distinct zone around bare rock or around tem­ the island are dominated by more or less treeless poral pools. Other characteristic plants in this areas (alvar) consisting of a mosaic of exposed habitat are Allium schoenoprasum var. alvarense, bedrock, a thin cover of weathered soil and Poa alpina and Bromus hordeaceus. A dense grass Quaternary deposits. Oland is situated in the rain cover (Festuca ovina, Agrostis stolonifera etc.) ex­ shadow of the Swedish mainland and has a low an­ cludes Crepis from deeper soil. It normally nual precipitation. The thin and exposed alvar soil behaves as a winter annual germinating in the is rapidly dried out in the spring and summer. autumn, overwintering as a leaf rosette and flower­ Most rainfall occurs from July to October (Widen ing in May-June before the summer drought. In 1980, Rosen 1984). rainy summers flowering plants can be found throughout the summer and in the autumn. The flowering pattern is determinate, i.e. in­ Methods florescences ('heads') flowerin a more or less fixed sequence on the plant, starting with the head ter­ The study was performed in 1986 and 1987 in an minating the main shoot and ending with heads on alvar area 1.5 km S of Vickleby on Oland. In 1986 the lowermost branches (Fig. 1). The initial bud four sites differing in grazing pressure, grass cover

Acta phytogeographica suecica 76 Limiting fa ctors on seed production in Crepis tectorum 11 and soil depth were chosen (S-1, S-2, S-3, S-4). The field experiment was partly repeated in 1987 They were separated by 100 m or more. In early at site 3. A larger number of randomly selected June a transect was laid out in each site consisting plants along a 100 m transect was assigned to seven of a row of 33 to 35 adjacent plots (0.6 0.4 m). different treatments: (1) Application of fertilizer at x In each plot I recorded the percentage grass cover rosette stage (April 29; hereafter 'Fertilized 1 '). (2) (to the nearest 10 OJo) and the soil depth at the Application of fertilizer during inflorescence in­ centre of the plot (mm). Randomly selected flower­ itiation prior to flowering (June 2; 'Fertilized 2'). ing plants along the transects were marked and (3) Removal of all heads but one during inflor­ assigned to one of six different treatments: (1) Ap­ escence initiation prior to flowering(June 2; 'Head plication of a dry NPK (14-4-17) fertilizer to the removal!'). (4) Removal of all heads but one when surface soil within 5 cm around the rosette (1-1.5 flowering had begun (June 17; 'Head removal 2'). g per plant). The plant was watered immediately (5) Removal of half the leaves in the leaf rosette after the application. (2) Removal of all heads but during inflorescence initiation prior to flowering one. (3) Removal of half the leaves in the rosette. (June 2; 'Leaf removal!'). (6) Removal of half the (4) Hand cross-pollination of one flowering head leaves in the rosette when flowering had begun using pollen from two or more neighbouring (June 17; 'Leaf removal 2'). (7) Control (no plants. (5) Exclusion of pollinators by bagging, us­ manipulation). Treatments nos. 4, 6 and 7 are ing nylon netting. (6) No manipulation (control). comparable to the corresponding treatments in the For each plant treated I recorded the number of 1986 field experiment (nos. 2, 3 and 6, respec­ leaves in the rosette, the number of heads initiated tively). and the position of the head that was flowering The following reproductive traits were measured: when the plant was treated. Leaf number is (1) The total number of heads initiated initial roughly proportional to leaf area (pers. obs.). The ( = position of a head was defined by the position of bud number). the node to which it was attached. The uppermost (2) The number of flowers initiated per head ( = one was assigned a value of 1, the second one 'head size'). closest to the top a value of 2 and so on. When a (3) Percentage of heads initiated per plant that branch had more than one head all heads on that developed to the flowering and fruit-stage (not branch were given the same value (Fig. 1). All the measured for plants which had heads removed ar­ plants along the four transects were collected when tificially). they were dead, including the ones used in the ex­ periment. (4) Percentage seed-set per head. Plants grown in a greenhouse at the University (5) 'Seed-quality'. This measure was estimated by of Lund in 1986 were used to determine the a simple germination test 2-3 months after breeding system and to estimate the reproductive harvesting. Ten to twenty seeds per head were output when conditions were favourable through­ placed on moist filter-paper in petri dishes at room out the life of the plants (excess water and temperature and checked two weeks later. The nutrients). These plants were grown from seeds percentage of germinated seeds per sample was collected near one of the sites used in the field ex­ used as a rough measure of seed-quality. A poten­ periment (S-3). Five to eight flowering heads on tial problem with this measure is that it may each plant were subjected to one of four treat­ underestimate viability due to various kinds of ments: (1) Hand cross-pollination of bagged heads dormancy. However, earlier germination tests using pollen from at least two other plants. (2) have shown that most seeds of this ecotype ger­ Hand self-pollination of bagged heads, using minate within a week at room temperature when pollen from heads flowering simultaneouslyon the moisture is sufficient (unpubl.). Secondly, prelimi­ same plant. (3) Open-pollination in the green­ nary results of a demographic study indicate that house. (4) Control (isolation in nylon bags). Each seedlings emerging early in the autumn have a head treated was marked and its position on the higher survival and reproduction rate than seed­ plant recorded. lings emerging later. Hence, the term 'seed-quality'

Acta phytogeographica suecica 76 12 Stefa n Andersson is still appropriate even if it reflects the proportion Table 1. Weather data for 1986 and 1987 from April to date of harvesting of plants. The average daily precipitation from 1965 to of rapidly germinating seeds rather than viable 1982 is also given (from Rosen 1984). All data are from the Ecological Station, Olands Skogsby. ones.

(6) In some cases I also estimated the total number Auer11ge Auer11ge Auer11ge AuerBge d8i ly delly dBIIY d8l ly of flowers and viable seeds produced per plant. minimum mBHimum cloudiness precipit8 tlon te mp. temp. of slc y (m m) ('7. Unfortunately, most plants had shed some of their couered with (oC) (oC) seeds when they were collected. Consequently, it cl ouds)

1986/ 87 1986/ 87 1986/ 87 1986 87/ 1965-82 was not possible to measure the total flower and I seed production per plant directly. Instead, I April 0.2 1.0 8.6 10 75 1.4 1.0 0.8 65 multiplied the estimates of the separate com­ M11y 6.9 4.5 18 13 41 56 0.9 1.6 1.3 June 7.9 20 0 73 0.8 2.3 1.1 9.3 17 4 ponents above (1-3 for total flower number, 1-5 July 11 19 - 66 2.0 1.6. for total seed number). (7) In 1986 I also determined the number of heads

Table Spear man correlation coefficients x 1 00) between that were lost due to herbivory. 2. ( reproductive characters and environmental variables for each site: top line Site 1, then follows Site 2, 3 and 4. I n some cases two values are Data analyses given for Site 3, one for 1986 (left) and one for 1987 (right). In 1986 all plants within each site were pooled to increase the sample size. Differences between experimental groups were Different treatments had no consistent effect on the correlation tested by analysis of variance (ANOVA) or t-tests. between any pair of the variables (P>0.05 in all cases, Friedman's test with coefficients for each treatment sample ranked within each site). In the 1986 field experiment I also used a two-way Only plants from the control group were used in 1987 due to a larger sample size. Sample sizes are 33 or 35 for values marked with an ANOVA to test (1) whether different treatments asterisk while the others are based on 115 to 278 observations. Values given in bold type are significant at the 1 level. had any effect on the trait, (2) whether there were % overall differences in the trait among the sites, and (3) whether the trait responded differently to the Uarl8b1e Soil depth treatments among the sites, i.e. whether there was I. a significant site x treatment interaction. In some cases I broke down the overall ANOVA into or­ 2. Gr8ss couer 5 • thogonal comparisons between the control and so9• (%) 32• each of the experimental groups. If the data was 53• too skew I used the Kruskal-Wallis test, Fried­ 3. Rosette -13 -14 size -10 man's test or Mann-Whitney's U-test. The Spear­ ·21 -8 ·12 -6 man rank correlation coefficient was calculated to ·12 estimate the degree of association between two 4. Numbe r -63• -75• 56 of heeds -40• -69• 77 variables. Percentage seed-set and seed-quality lnltl8ted -35• ·40• 71 were arcsine transformed and leaf number was -30• ·56• 65

5. Heads 15 5 -42 transformed to natural logarithms prior to the ·2 · deue loplng 17 18 -24 -39 analyses (Sokal & Rohlf 1981). to fruit- -2 5 -31 -43,-45 stege 3 -23 ('7.) -40 Head size -10 -14 42 48 -10 6. - 1 - 3 51 46 -13 -0 - 3 65 67,65 -24,-28 -0 -21 60 60 -14

Results 7. Seed-set -8 19 -5 -2 12 4 4 1 -13 22 2 ('7.) 1 8 9,1 -1, 3 20,7 Weather data and phenology -9 -12 20 9 30 1 The weather during the reproductive season of Seed-q ue li ty -14 13 16 s. 18 Crepis was sunnier, warmer and drier in 1986 than germlne- -16 24 8 ('7. 2 3 18 12 tlon) 13 -2 3 1,3 5,10 6, -9,·5 8 in 1987, especially in June. The first season was 12 4 16 4 10 10 8 probably more 'normal' for Crepis, at least with I. 2. 3. 5. 6. 7. respect to weather conditions in June (Table 1). In 4. 1986, an early summer drought shortened the Ue rl8ble flowering period conside,rably. Most plants used in

Acta phytogeographica suecica 76 Limiting factors on seed production in Crepis tectorum 13

Fig. 2. The distribution of the number of heads initiated per plant in 1986 (for sample sizes, see Table 4).

107 113 10 5 1987

�47

2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19

Head position

Table Characteristics of the study sites in the 1986 experiment. the experiment started to flower in the first week of 3. Average rosette size is also given. Standard deviations (left) and June and died about two weeks later. The cool, sample sizes (right) are shown in parentheses. rainy and cloudy summer of 1987 delayed and pro­ Site Gross Soil Rosette longed the flowering period considerably. At site 3 couer depth size (mm) it extended from the middle of June to September. (1.) (leof number) Experimental plants were collected at weekly inter­ S-1 14 (21, 35) 40 (21, 35) 5.0 (2.0, 229) S-2 9 (10, 33) 40 (13, 33) 5.8 (2.5, 193) vals in late July. S-3 20 (20, 33) 47 (12, 33) 5.4 (2.0, 277) S-4 11 (15, 33) 51 (12, 33) 6.0 (2.3, 243) Correlation analyses Spearman correlation coefficients between all pairs of environmental variables and plant characters -0.02, n 419, P >0.05) or for plants grown in are shown in Table 2. Plants with a large leaf = the greenhouse (Fig. 2, Spearman r 0.05, n rosette initiated more heads than plants with a = = 116, P >0 .05). These results are also shown small leaf rosette. There was a negative correlation graphically in Fig. 2. between plant size and percentage grass cover and a tendency for plants to be bigger on shallow soil Variation among sites and between years in where the grass cover was low. Larger plants pro­ reproductive characters duced larger heads than small plants but the pro­ In 1986 there were significant differences among portion of heads developing to the fruit-stage the sites in grass-cover (Table 3, P <0.0 5, Krus­ decreased with initial head number. Percentage kal-Wallis test), soil depth (Table 3, P <0 .01, seed-set increased with the number of flowers in ANOV A), the number of leaves per rosette (Table the head in 1986 but not in 1987. There was no 3, P <0.001, ANOVA), the number of heads in­ consistent association between seed-quality and itiated per plant (Table 4, P <0.00 1 , Kruskal­ any of the other variables (Table 2). Wallis test), the proportion of heads developed to The position value assigned to a head (Fig. 1) the fruit-stage (Table 4, P <0 .05, Kruskal-Wallis and its rank in the flowering sequence on the plant test), relative seed-set and seed-quality (Tables 5 were highly correlated (Spearman r 0.97, n and 6) but not in head size (Table 4, P >0.0 5, = = 934, P <0.001 for the 1986 data). In 1986, late­ ANOVA). The size distribution was highly skewed flowering heads (high position values) matured at all sites (Fig. 3). seeds of lower quality than early-flowering ones Site 3 was used in both years, which allows a (low position values) (Spearman r -0.33, n = = comparison of the reproductive success of un­ 183, P <0.001; r -0.15, n 138, P >0 .05; r = = manipulated plants in a dry and a rainy summer. -0. 19, n 223, P <0 .01; r -0. 16, n = = = = The number of heads initiated and the proportion 207, P <0. 01, for sites 1 to 4, respectively). This of heads developed into maturity were higher in effect was not found in 1987 (Spearman r = 1987 than in 1986 (Table 4, P <0.0 01 in both

Acta phytogeographica suecica 76 14 Steja n Andersson

4. 60 Table Means of some reproductive characters. Standard deviations (left) and sample sizes (right) are shown in parentheses.

Site Percentage of Numbe r of 50 Number of head s head s deueloplng flowers In itiated to fruit -stage per head Site 1 per piont 40 Site 2 1986 en Site 3 c111 S-1 1.9 (1. 4, 765) 77 (39, 765) 38 1, 229) 30 (t S-2 797) 72 (41, ) 39 (12, Q. Site 1.9 (2. 0, 797 193) 0 4 S-3 2.2 (1.9, 642) 72 (40, 642) 38 (12, 277) S-4 2. 9 (2.5, 41 79 (35, 418) 39 (12, 243) Q) B) Cl All sites pooled 2. 1 (2.0, 2622) 75 (3 9, 2622) 38 (12, 942) 111 20 c Greenh ou se 73 (39, 22) 82 (12, 22) 57 (12, 463) Gl � 1 987 (S-3) Q) a. 10 Fe rtilized 1 14 (6.4, 13 7) 84 (7.1, 137) 53 (12, 233) Ferti lized 2 10 (7. 0, 11 4) 83 (11, 11 4) 30 (8.4, 122) Control 3.0 (2.5, 98 1) 92 (1 6, 635) 29 (9. 9,11 87)

2 3 10 20 1 4 5 Number heads of Table 5. Two-way ANOVA to test the effect of site and treatment on Fig. 3. The average seed quality germination) as a seed-set and seed-qu ality (n.s.� not significant, P<0.01, (OJo ··= P<0.001). Transformations (arcsine) were applied prior to the analyses. function of head position (see Fig. 1). Sample sizes are also given. In 1986, all heads investigated in the field ex­ periment (excluding the bagged ones) were combined, Character Source of uariation df MS while the 1987 data is based on unmanipulated plants Seed -set Site 1.857 1 8.57 *** Treatment 5 12.69 83. 49 .... only. The greenhouse data are based on heads that were (%) Site Treatment 15 0. 152 1.518 n.s. H artificially pollinated (cross-pollinated and self-polli­ Error 919 0. 100 nated heads cornbined).

Seed -quality Site 2. 052 7. 5 45 ...... ger in ation) Treatment 1.3 75 6. 111 .. .. ('7. m Site H Treatment 15 0.22 5 0.827 n. s. cases, U-test). The reverse was true for head size, Error 72 7 0.272 percentage seed-set and seed-quality (Tables 4 and 6, P <0.0 01 in all three cases, t-test). In 1986, the average total number of viable seeds respective of site (Table 5). Bagged heads matured per plant ranged from 30 to 55. It was nearly a lower percentage of seeds than the control. Other halved in 1987 at site 3 (Table 7). treatments had no or inconsistent effects on relative seed-set. In one case, leaf removal Field experiment 1986 decreased seed-set significantly (Table 6). For seed­ In 1986, most plants had begun to flower when the quality, treatment effects were weaker though still experiment was started. The number of heads in­ significant (Table 5). For 3 of the sites, isolated itiated and head size were to a large extent fixed heads matured seeds of lower quality than the con­ and were therefore not included as response trol. At site 2, application of fertilizer resulted in variables in the experiment. The different a significantly lower seed-quality compared to the treatments had no consistent effect on the propor­ control (Table 6). tion of heads that a plant developed to the fruit­ stage (P >0.05, Friedman's test with treatment Greenhouse vs field (all sites pooled, 1986) means ranked within each site). In no case did Different reproductive characters responded dif­ plants in the 'head removal' group develop other ferently to cultivation in the greenhouse (Tables 4, heads into maturity than the one that was left in­ 6 and 8). Head number increased by a factor of 35 tact. The loss of heads due to herbivory (mostly by (P <0.0 01, U-test) while the size of the heads, the hares) was negligible at all sites (0.5-1.2 o/o). proportion of heads that developed to the fruit­ Percentage seed-set and seed-quality differed stage, and seed-quality were only 1.5, 1.1, and 1.2 greatly among the treatments. The interaction times higher than in the field, respectively. Never­ terms were not significant, indicating that plants theless, these increases were still significant responded in the same way to the treatments ir- (P <0.0 01, t-test, P <0. 01, U-test and P <0.0 01,

Acta phytogeographica suecica 76 Limiting fa ctors on seed production in Crepis tectorum 15

Table Means of seed-set and seed-quality for heads on plants used Table 7. The estimated total flower and seed production per plant. 6. in the field experiments. Standard deviation (left) and and sample sizes (right) are given in parentheses. The significance of F-values obtained from planned comparisons between the control and (ANOVA) each treatment group for each site and experiment is also given ' = Site TotBI number Total number Transformations (arcsine) were( P<0.05, ** a P<0.01 ' *** D P<0.001 ). of flowers per of uioble seeds applied prior to the analyses. plant per plant

1986 Seed-qu BIIty Slte/Tre Btment Seed-set ('7,) ('7, germinBtion) S- 1 1986 56 36 S-2 53 40 S-3 (I 986) 60 30 S-1 Fertilized 81 (I 8, 42) 75 (36, 34) S-4 89 HeBds remoued 87 (15, 37) 89 (18, 33) ss sites pooled 60 37 Leoues remoued 84 (20, 40) 82 (25, 37) All Greenhouse 341 2 Hand outcrosse d 88 ( 15, 31) 92 (I I' 26) 1956 Bogged 37 (36, 31)"*" 55 (41, 11)• 1987 (S-3) Control 83 (22, 48) 79 (32, 42)

Fertilized I 623 S-2 76 (25, 45) 73 (36, 39)" 21 1 Fertilized Fertilized 2 Heads remoued 80 (16, 26) 89 (18 , 23) 249 1 I 5 Control 72 (22, 31)"" 86 (27, 24) BD 16 leoues remoued Hand outcrossed 84 (22, 27) 84 (26, 22) BBgged 14 (23, 34)""" 39 (37, 4)""" Control 85 (13, 30) 89 (23, 26)

S-3 78 (15, 57) 72 (3 1, 46) Fertilized He11ds remoued 73 (22, 43) 61 (37, 35) The proportion of heads that developed to the Leaues re moued 75 (23, 53) 65 (38, 49) Hand outcrossed 76 (21, 36) 62 (3 8, 34) fruit-stage was not affected by halving the number Bogged 13 (16, 24)••• 22 (39, 3) Control 80 (18, 64) 63 (38, 56) of leaves in the rosette (P >0.0 5 in both cases, U­ test of difference between each of the 'Leaf S-4 Fertilized 83 (17, 40) 69 (35, 39) HeBds remoued 8 I (21, 35) 82 (27, 29) removal' groups and the control). However, there leoues remoued 83 (19, 38) 71 (37, 35) Hand outcrossed 92 (9, 34) 72 (3 8, 30) was a slight decrease in this trait after application Bagged 26 (29, 32)••• 46 (43, 1 4)" Control 87 (14, 64) 71 (34, 60) of fertilizer (Table 4, P <0.0 01 in both cases, U­

1987 (S-3) test of difference between each of the fertilized groups and the unfertilized group). In this year, Fertilized 1 77 ( 1 8, 233)••• 44 (29, 211)••• Fertilized 2 78 (1 6, I 22)""" 59 (30, 120) .... plants were able to develop 'new' heads when Heads remoued 1 81 (17, 203)""" 35 (26, 201) Heads remoued 2 76 (23, 132)""" 31 (28, 148) earlier ones were removed artificially. The average Leoues remoued I 70 (22, 1 58) 33 (25, 154) number of new heads was 2.2 3.1 (n 210; ex­ Leoues remoued 2 71 (2 1. 251) 36 (28, 254)" ± = Control 68 (24, 443) 30 (28, 439) cluding the one left intact) when the first heads were removed at the initiation stage (June 2) while the number was 0.9 1.5 (n 136) when they were ± = t-test, respectively). Percentage seed-set was lower removed at the flowering stage (June 17). This dif­ in the greenhouse (P <0.001, t-test on difference ference is highly significant (P <0.0 01, U-test). between heads on control plants in the field and Percentage seed-set differed significantly among hand-pollinated heads in the greenhouse). The the treatments (Table 6, P <0.0 01, ANOVA in­ estimated total seed production per plant in the cluding all groups). Fertilization as well as remov­ greenhouse was 1956, which is about 53 times ing competing heads increased seed-set compared higher than in the field (Table 7). to the control while leaf removal had no effect. Seed-quality was also different among the groups Field experiment 1987 (Table 6, P <0.0 01, ANOVA including all As shown in Table 4, application of fertilizer in­ groups). Seed-quality of fertilized plants was sig­ creased the number of heads initiated compared to nificantly higher than the control. It also increased the control, regardless of time of application slightly after halving the rosette size at the flower­ (P <0.0 01 in both cases, U-test). Plants fertilized ing stage (P <0.0 5). at the rosette stage initiated a somewhat higher number of heads than plants fertilized during in­ Breeding system (greenhouse) florescence initiation (P <0.0 01, U-test). Only There were large differences in relative seed-set plants in the first group initiated significantly among the treatment groups (Table 8, P <0 .001, larger heads than the control (Table 4, P <0.0 01, ANOV A). Unmanipulated heads produced t-test). relatively more seeds than bagged heads (control).

Acta phytogeographica suecica 76 16 Stefa n Andersson

Table 8. Seed-set and seed-quality in the greenhouse experiment. flower production. Cultivation in favourable Standard deviations (left) and sample sizes (right) are given in parentheses. The significance of F-values obtained from planned greenhouse conditions and fertilization of field comparisons (ANOVA) between the control and each of the other groups is given for percentage seed-set P<0.01, P<0.001 ) Data plants prior to flowering (1987) stimulated flower (**= ***= . were arcsine transformed prior to analysis. production considerably. However, plants in the field that were fertilized during inflorescence in­ Treatment Seed-set Seed-quality (%) germination) (% itiation produced fewer and smaller inflorescences Hand cross-pollination than plants fertilized at the rosette stage. This may 91 (13, 66) Hand self-pollination 63 (23, 115)*** 20 (23, 1 OS)*** 86 (21, 50) Open pollination partly be an effect of the determinate growth pat­ 9 (18, 124)** Isolation 2 (9, 112) tern in Crepis. The number of floral meristems is probably fixed at a fairly early stage and decreases once flower development starts. Consequently, it Outcrossing by hand yielded the highest percentage may be difficult for plants with a determinate seed-set. The effect of hand self-pollination was flowering pattern to make maximum use of weaker although still significant. Seed-quality was 'delayed' pulses of nutrients. However, the estimated for seeds produced by artificial cross­ tendency of plants to 'overinitiate' inflorescences pollination and self-pollination. It was high in (see below) suggests that the number of meristems both groups and was not statistically different be­ was not a factor which limited the response. More­ tween the two groups (Table 8, P >0.0 5, t-test). over, similar effects have been observed in plants with a more indeterminate growth pattern (Benner & Bazzaz 1985), indicating that other factors than growth pattern may be important. Discussion Favourable growth conditions increased in­ florescence number more than inflorescence size. Reproductive effort in plants can be described by When plants were grown in a greenhouse, head several components of yield. Each of these com­ number increased by a factor of over 30, while ponents can be constrained or regulated by differ­ head size was only 1.5 times higher than for field ent stress factors. In the following I discuss the plants. Application of fertilizer to field plants also relative importance of resource limitation on increased head number more than head size. More­ flower determination and on seed development over, head number was more variable among the and the extent of pollination limitation on seed de­ sites than head size. Head number also appears to velopment. Possible targets for selection and adap­ be more variable than head size within each site. tive interpretations will also be discussed. The relative variability (standard deviation/mean) Is flower production resource-limited? was 74 to 105 OJo for head number but considerably Many life-history traits affect the amount of nutri­ less for head size (29-32 OJo) (see Table 4 for stan­ tional resources accumulated by a plant that swit­ dard deviations and means used). These observa­ ches from vegetative growth to reproduction. Time tions show that plants of Crepis regulate flower of emergence (Black & Wilkinson 1963), growth number mainly by varying the number of heads in­ rate (Harper 1977) and final plant size (Gross & itiated, while keeping head size relatively constant. Werner 1983) may all influence the number of Similar observations were reported by Lloyd et al. flowers that a plant can produce. Selection to in­ (1980) for species of Cotula. A dense arrangement crease the availability of resources prior to flower­ of flowers in a head probably sets a limit on how ing can therefore modify several life-history traits large a head can be. It may be difficult for a plant not directly associated with reproduction. The to produce enough supporting structures (in­ potential of selection on these characters should at volucre, conducting tissues, etc.) for very large least be partly reflected by the extent of resource heads. The shattering of seeds may also be prob­ limitation on the number of flowers initiated. lematic if the head contains too many seeds at the The nutrient-deficient alvar habitat constrained time of dispersal. the number of flowers that plants of Crepis pro­ Plants of Crepis are monocarpic; they flower duced to a level that was far below their potential once and then die. Therefore, all resources ac-

Acta phytogeographica suecica 76 Limiting fa ctors on seed production in Crepis tectorum 17 cumulated prior to flowering are probably devoted than it was in the case of flower number. Finally, to reproduction. The early determination of both these traits were less affected by differences in the head number and head size suggests that these initial 'resource status' among the plants. Percen­ traits should reflect the resource 'status' prior to tage seed-set was only correlated with the number flowering as measured by, for instance, rosette of flowers in the head, suggesting that the propor­ size. This prediction was supported by strong tion of seeds matured reflected the nutritional positive correlations between rosette size and the status of the head rather than of the whole plant number and size of heads initiated. Variation in (as reflectedby rosette size or head number). Seed­ plant size was at least partly determined by habitat quality did not vary with grass cover or any of the differences. For example, a denser grass cover plant size parameters. Consequently, a Crepis usually resulted in smaller rosettes and thus fewer plant adjusts its reproductive effort to the avail­ and smaller heads initiated, probably owing to in­ able resources by regulating the flower number creased competition for light and nutrients. (especially head number) while minimizing the ef­ Surprisingly, plants initiated a larger number of fect of limited initial resources on seed maturation. heads in 1987 than in 1986 despite the unusually This is probably adaptive. More resources would cold and cloudy weather at the time of flower in­ be wasted on 'unproductive' flowers if the propor­ itiation. However, the number of heads initiated tion and quality of seed developed per head did probably reflects growth conditions prior to in­ reflect the initial nutritional status of the plant (see florescence initiation rather than the weather dur­ also Lloyd et al. 1980). ing the inflorescence initiation. Growth conditions It was more difficult for plants of Crepis to during the previous autumn or during the spring match the seed maturation to unfavourable were perhaps better for plants flowering in 1987 weather conditions. In the dry summer of 1986, than for plants flowering in 1986. Moreover, heads flowering early produced seeds of higher plants were collected from a larger and probably quality than heads flowering later on the same more heterogeneous area in 1987 than in 1986. plant. This effect was not found in the greenhouse Thus it is possible that the difference in head or in 1987 when soil moisture was high throughout number was a sampling effect. Since flower deter­ the season, indicating that it was caused by a de­ mination within the heads occurs after the deter­ crease in water availability. The proportion of mination of head number, there was probably a heads developing into maturity was also higher greater potential for head size to be adversely af­ when water was abundant. Hence, water was prob­ fected by unfavourable summer weather in 1987. ably a limiting factor on reproduction in Crepis in Despite the larger number of heads per plant in 1986 (see also Delph 1986, Mulroy & Rundel 1977). 1987, head size was indeed smaller this year. The However, the cool and rainy summer of 1987 was delayed and prolonged flowering period indicates probably more detrimental for reproduction, as that unfavourable weather conditions also shown by the slower rate of flowering, the smaller decreased the rate of inflorescence development. heads initiated, the lower seed-set and the lower overall seed-quality. The total estimated seed pro­ Is seed-maturation resource-limited? duction per plant was nearly halved compared to The number of flowers or ovules initiated com­ 1986 when these components were taken into ac­ monly exceeds the number that mature into fruits count. Some of these reductions were smaller when and seeds due to insufficient resources (Stephenson plants were fertilized or when competing heads 1981). In Crepis, however, the effect of resource were removed, suggesting that plants were limitation on the maturation of flowers into seeds deprived of nutrients at these stages. It thus ap­ was less severe than on flower production. The pears that Crepis is adapted to warm and dry sum­ percentage of heads developing to the fruit-stage, mers rather than to cool and rainy summers. It is percentage seed-set and seed-quality were usually not known whether other ecotypes of Crepis tee­ not very far from the corresponding value for foru m have the same requirements. Indirect plants grown in the greenhouse. Moreover, the re­ evidence that this may be a species characteristic sponse to addition of fertilizer was usually weaker rather than being 'unique' to spp. pumila is that

Acta phytogeographica suecica 76 18 Stefa n Andersson the species has a continental distribution in Eurasia Bertin 1983), or increase the possibility to develop and avoids the westernmost, oceanic parts of a maximum number of fruits or seeds in a 'good' Europe (Babcock 1947). season when resources are unusually abundant Variation in annual rainfall has potential im­ ('bet hedging') (Stephenson 1979). In Crepis, over­ plications for how selection acts on phenological initia ion of inflorescence buds may be an adapta­ traits. Individual plants of Crepis probably pro­ tion to take advantage of a season when soil duce more and better seeds if they complete their moisture is sufficient throughout the season. The life-cycle before the summer drought in a dry year. higher proportion of heads developed into fruit­ As a consequence, natural selection is likely to stage in 1987 as compared to 1986 supports this favour early flowering and rapid seed maturation. hypothesis. However, reductions in other traits Selection for earliness is probably relaxed in rainy and in the estimated total fecundity (see above) summers. However, several lines of evidence sug­ suggest that the gain from these extra heads was gest that dry summers have been more important low. Furthermore, a small proportion of buds still in the long term. Firstly, weather data show that failed to develop in the greenhouse despite excess early summer droughts are more common than ex­ water. A possible function of 'surplus' buds is to tended periods of rainfall. Secondly, large effects provide a possibility to develop new heads if the of summer droughts are known in other alvar first ones are grazed by animals. The occurrence of plants (Widen 1980, Rosen 1984). Finally, com­ 'new' heads after artificial head removal in 1987 mon garden experiments show that ecotypes of clearly indicates that this may be the case for Crepis tectoru m from alvar habitats flower earlier Crepis. Moreover, this loss was partly compen­ than 'weed' ecotypes (unpubl.), suggesting that the sated because heads that were left intact increased risk of desiccation in early summer has been a ma­ the proportion of flowers that matured into seeds, jor selection pressure on phenology. Too early apparently by using resources that were released flowering is probably also detrimental due to low when the first heads were removed. None of these temperatures in the spring. Thus stabilizing selec­ effects were observed in the dry summer of 1986, tion for flowering time is likely (Schemske 1977, indicating that plants fail to reallocate internal Schmitt 1983). resources to other inflorescences when the Decreasing the photosynthetic area is expected availability of water decreases too fast. Hence, this to have detrimental effects on seed maturation function would be important only if soil moisture (Harper 1977, Stephenson 1981). However, in is sufficient for a long period and if the risk of Crepis, halving the leaf area had no or inconsistent grazing is high. The low frequency of rainy sum­ effects on traits associated with seed development. mers on bland and the low level of herbivory This suggests that the remaining leaves increased observed in this study suggest that initiation of ex­ their photosynthetic efficiency and compensated tra inflorescences is not a mechanism to reduce the for the loss (Harper 1977) or that developing seeds effect of herbivory. Non-adaptive explanations of were at least partly nourished by photosynthetic inflorescence over-initiation are perhaps more tissues in stems and cauline leaves or by stored likely. There are indications that the number of resources in other parts of the plant. This func­ meristems initiated always increases dispropor­ tional shift may be adaptive since rosette leaves tionately when the availability of resources is high. commonly wilt once flowering has begun Plants that initiate many heads usually mature a (pers.obs., see also Mulroy & Rundel 1977). smaller proportion of heads into maturity than Constraints on reproduction are not always small plants, at least in field conditions. There was caused by environmental stress. A low ratio of also a weak decrease in the proportion of heads fruits to flowers may be adaptive if flowers have developing into maturity after nutrient application other functions than to set fruit. 'Surplus' flowers in 1987 despite the large number of heads initiated may increase a plant's visual display to pollinators on these plants. However, most heads that fail to (Waser 1983), increase pollen dissemination develop are arrested at a very early stage (pers. (Willson & Price 1977), provide the plant with a obs.), indicating that the resource waste associated choice of fruits or seeds to mature (Stephenson & with the over-initiation of heads is small. Selection

Acta phytogeographica suecica 76 Limiting factors on seed production in Crepis tectorum 19

against plants initiating 'too many' inflorescences · duced by heads on bagged plants to mature seeds is probably weak. of lower quality than open-pollinated heads, in­ dicating that inbreeding depression may occur in Breeding system and pollination limitation field conditions. Seed-quality did not increase after The number of seeds produced by a plant is some­ hand-pollination, suggesting that this character times limited by insufficient pollination in plants was not limited by lack of pollination either. It that lack automatic self-pollination (Bierzychudek should be stressed that 'seed-quality' only refers to 1981). This increases the potential for selection to germinability. The fitness of selfed or outcrossed modify the floral display to attract more seeds may be different when seedling growth, etc. pollinators, to shiftthe flowering curve to a period is also taken into account. when pollination is more reliable (Waser 1983) or No plants were hand-pollinated in 1987. How­ to favour autogamy to decrease the dependence on ever, the positive effect of fertilization and pollinators (Wyatt 1983). To assess the role of removal of competing heads on the proportion and selection to increase the pollination efficiency I ex­ quality of seeds matured (see above) would prob­ amined the breeding system and the extent of ably not be possible if the number of 'good' seeds pollination limitation on seed-set. developed were determined primarily by the Although a high rate of automatic self-pollina­ amount of pollen received. Hence, also in 1987 tion occurs in many ecotypes of Crepis tectorum nutritional resources were probably a more im­ (unpubl.), plants of ssp. pumila used in this study portant limiting factor on seed production than were at least partly self-sterile and dependent on pollination. external pollen transfer to set seed. Clearly, there The plant density was relatively high in both is a potential for seed-set to be pollen-limited. 1986 and 1987 when the experiments were carried There was, however, still a limited capacity for out. Seed-set may still be pollen-limited in situa­ self-pollination. Bagged heads had a significantly tions where the distance between flowering plants lower seed-set than unbagged ones, indicating that is too large for insect (or wind) pollination to be some pollination occurred in the greenhouse. It is reliable, that is, in the 'tails' of the flowering curve not known whether this was due to insects (very or during years when the overall plant density is few were seen in the greenhouse) or by pollen flow­ low. ing passively by air currents between the plants. Seed-set was relatively low (63 %) in the green­ house even when flowering heads were hand-polli­ nated, perhaps owing to the pollination method used. Detrimental effects of the bagging technique are also possible. Conclusions Despite a low seed-set in isolation, fruit-set was high in the field and did not increase by hand­ The results of this study indicate that the most im­ pollination, indicating that seed-set was not limited portant bottlenecks in the seed production of by insufficient pollination in 1986. This result is Crepis are lack of resources when plants switch surprising since strong winds on the alvar com­ from vegetative growth to reproduction, and un­ monly limited insect activity (pers.obs.). It is poss­ favourable weather conditions during the period ible that very few insect visits may be sufficient to from inflorescence initiation to seed maturation. fertilize the majority of the flowers in a head or Hence traits avoiding these constraints should be that some of the pollination was affected by the strong targets for selection in Crepis populations wind. Finally, some seed-set may still be partly at­ while selection on characters associated with tributed to self-pollination. pollination may be weaker. Demographic studies Seed-quality was not significantly higher for are being performed to reveal how the reproduc­ outcrossed seeds than for selfed seeds when pro­ tive success of individual plants is affected by duced by plants grown in a greenhouse. However, variation in various life-history characters (ger­ in the field there was a tendency for seeds pro- mination time, growth rate, flowering time, etc.).

Acta phytogeographica suecica 76 20 Stefan Andersson

Acknowledgements. I wish to thank H. Runemark, L. regulation of material investment. - New Phytol. Svensson and B. Widen for valuable comments on the 86: 81-92. manuscript. I am indebted to the staff of the Uppsala Mulroy, T. W. & Rundel, P. W. 1977. Annual plants: University Ecological Station at Olands' Skogsby for adaptations to desert environments. - Bioscience support in various ways. Linguistic advice by Karin 27: 109-114. Ryde is also acknowledged. The investigation was car­ Rosen, E. 1984. Some short-term changes in the ried out with grants from the Harald E. Johansson dynamics of limestone grasslands of South Oland, Foundation. Sweden. - Nova Acta R. Soc. Scient. upsal., Ser. V:C, 3: 189-205. Schemske, D. W. 1977. Flowering phenology and seed set in Claytonia virginica (Portulacaceae). - Bull. References Torr. Bot. Club 104: 254-263. Schmitt, J. 1983. Individual flowering phenology, plant Babcock, E. B. 1947. The genus Crepis - size, and reproductive success in Linanthus an­ 1-11. Berkeley. 1030 pp. drosaceus, a California annual. - Oecologia (Berl.) Benner, B. L. & Bazzaz, F. A. 1985. Response of the an­ 59: 135-140. nual Abutilon theophrasti (Malvaceae) to timing of Sokal, R. R. & Rohlf, F. J. 1981. Biometry. 2nd ed.­ nutrient availability. - Amer. J. Bot. 72: 320-323. San Francisco. 859 pp. Bierzychudek, P. 1981. Pollinator limitation on plant Stephenson, A. G. 1979. An evolutionary examination reproductive effort. -Am. Nat. 117: 838-840. of the floral display of Catalpa speciosa Black, J. N. & Wilkinson, G. N. 1963. The role of time (Bignoniaceae). - Evolution 33: 1200- 1206. of emergence in determining the growth of individual Stephenson, A. G. 1981. Flower and fruit abortion: plants in swards of subterranean clover. - Aust. J. proximate causes and ultimate functions. - A. Rev. Agric. Res. 14: 628-638. Ecol. Syst. 12: 253-279. Stephenson, A. G. & Bertin, R. 1983. Male competi­ Delph, L. F. 1986. Factors regulating fruit and seed pro­ I. duction in the desert annual Lesquerella gordonii. - tion, female choice and sexual selection in plants. - Oecologia (Berl.) 69: 471-476. Pollination Biology. New York. pp. 109-149. Gross, R. S. & Werner, P. A. 1983. Probabilities of sur­ Waser, N. M. 1983. The adaptive nature of floral traits: vival and reproduction relative to rosette size in the ideas and evidence. - Pollination Biology. New common burdock (Arctium minus, Compositae). - York. pp. 242-285. Am. Midi. Nat. 109: 184-1931. Widen, B. 1980. Flowering strategies in the Helian­ Harper, J. L. 1977. Population biology of plants. - themum oelandicum (Cistaceae) complex on Oland, London. 892 pp. Sweden. - Bot. Notiser 133: 99-1 15. Lloyd, D. G. 1980. Sexual strategies in plants: I An Willson, M. F. & Price, P. W. 1977. The evolution of hypothesis of serial adjustment of maternal invest­ inflorescence size in Asclepias (Asclepiadaceae). - ment during one reproductive session. - New Evolution 31: 495-511. Phytol. 86: 69-79. Wyatt, R. 1983. Pollinator-plant interactions and the Lloyd, D. G. & Webb, C. J., Primack, R. B. 1980. Sex­ evolution of breeding systems. - Pollination Biol­ ual strategies in plants: Data on the temporal ogy. New York. pp. 51-95. 11

Acta phytogeographica suecica 76 The dry alvar grasslands of bland: ecological amplitudes of plant species in relation to vegetation composition

Karin Bengtsson, Ho nor C. Prentice, Ejvind Rosen, Roland Moberg & Erik Sjogren

Abstract Bengtsson, K., Prentice, H. C., Rosen, E., Moberg, R. & SjOgren, E. 1988. The dry alvar grasslands of Oland: ecological amplitudes of plant species in relation to vegetation composi­ tion. -Acta phytogeogr. suec. 76, Uppsala. ISBN 91-7210-076-1.

The open, steppe-like alvar grasslands on the Baltic island of Oland contain many plant species which are on the margins of their geographic ranges or which have disjunct distribu­ tions. The present study provides an overview of the vegetation characteristics of the dry alvar grasslands, establishing a community-compositional framework for current studies on the evolutionary ecology and population biology of the phytogeographically distinctive alvar species. The survey also examines the ecological amplitudes of a range of these species within the alvar plant communities. There is no clear relationship between species' overall geographic distributions and their habitat tolerances or amplitudes in the alvar grasslands.

Karin Bengtsson, Ho nor C. Prentice, Ej vind Rosen, Erik Sj ogren, Institute of Ecological Botany, Up psala University, Box 559, 75 1 22 Upp sala, Sweden. Roland Mo berg, Th e Herbarium, Up psala University, Box 541, 751 21 Uppsa/a, Sweden.

Introduction Range-margin isolates of widespread and con­ tinuously distributed species, and the separate The opent steppe-like alvar grasslands on the regional populations within species which have dis­ Baltic island of Oland contain a remarkable junct distributions are not only of interest to number of plant species which are either at the phytogeographers. Such populations are of par­ limits of their geographic ranges or which are ticular interest to evolutionary biologists who are characterized by highly disjunct distributions. studying problems associated with, for example, Some of these species are known to have been the process of speciation or the maintenance of widely distributed in the open habitats around the genetic diversity (see e.g. Soule 1973, Parsons margin of the Fennoscandian ice sheet during Late 1983, Brussard 1984). One model predicts that Weichselian and early Flandrian times (see e.g. range-margin populations are less variable geneti­ Berglund 1966, Iversen 1973). The disjunct species cally than range-centre populations, and that this in the alvar grasslands belong to a range of phyto­ lack of variability is associated with "ecological geographical groups (cf. Sterner 1922, 1938, Kra­ marginality" (cf. Brussard 1984) or reduced niche­ hulec et al. 1986) but have in common a require­ breadth (cf. Van Valen 1965). The results of at­ ment for open conditions which has led to their tempts to explore the nature of variation in isolation in islands of open habitat in a landscape marginal versus central populations and to test this which is predominantly forested or agricultural. prediction have been highly conflicting. Nearly all The alvar habitat on Oland has remained more-or­ such studies have been carried out on animal ma­ less open since early Flandrian times, partly as a terial, despite the fact that plants may provide result of cultural influences (Konigsson 1968, more suitable subjects for the investigation of Rosen 1982). possible relationships between genetic variation

Acta phytogeographica suecica 76 22 Bengtsson, Prentice, Rosen, Moberg & Sj ogren

and niche breadth (cf. H. C. Prentice & W. Material and methods Cramer in prep.). Field sampling Study of range-margin populations can also con­ Fieldwork was carried out during June and July tribute to an understanding of the relative roles 1984. A total of 431 (1 1 m) vegetation quadrats that history and ecology play in determining x were recorded using a modified Braun-Blanquet present-day species distributions (cf. Endler 1982). cover/abundance scale 1-2 individuals; 2 Studies of the demography and reproductive biol­ (i = = 3-10 individuals; 3 < 2 OJo cover; 4 2-6 Ofo ; ogy of range-margin populations can lead, for ex­ = = 5 6-12 %; 6 12-25 %; 7 25-50 %; 8 ample, to the identification of critical phases in the = = = = 50-75 OJo ; 9 75-100 cover). Most of the life cycle which may impose climatic limits on a = OJo quadrats were recorded from the main area of con­ species' total distribution. tinuous alvar vegetation (Stora Alvaret) which oc­ The alvar grasslands of Oland, with their con­ cupies the southern third of Oland. In addition, centration of disjunct and range-margin popula­ samples were also taken from isolated alvar frag­ tions, are the arena for a range of studies on the ments at the following localities: Karums alvar, determinants of both species diversity (e.g. van der Langalver (Olanda flygplats), Mensalvret, Noaks Maarel 1988, Rejmanek Rosen 1988) and genetic & ark, Oreby alvar, Vedby alvar, Vasteralver (Byxel­ diversity (e.g. Prentice White 1988, H. C. Pren­ & krok). tice & W. Cramer in prep.). Such studies require basic information on overall patterns of differen­ Sampling was restricted to dry grassland habitats tiation in plant community composition and on the and was not extended to cover the moist grassland habitat preferences of the individual species being communities in which Ses/eria caeru/ea is domi­ investigated. Assessment of conservation objec­ nant (cf. Albertson 1950) nor the seasonally inun­ tives and decisions about future management dated communities of limestone pans (cf. Rosen strategies for the alvar grasslands must also be 1982 p. 23) or more-or-less clayey depressions with based on a knowledge of the range of plant com­ Agrostis stolonifera and A/op ecurus genicu/atus munity variation and of the habitat ranges of the (cf. Albertson 1950 p. 313 ff., Rosen 1982 p. 23). individual species within those plant commuqities. We also excluded areas with extensive recoloniza­ The present survey had two principal aims. tion by Juniperus communis. Within this frame, First, we wanted to characterize the overall varia­ we attempted to cover the full spectrum of com­ tion pattern in the dry alvar vegetation, to provide munity variation and also to specifically include a basic habitat framework within which to locate samples from the habitats occupied by species with ecological and population studies. We have built disjunct or range-margin distributions. The on previous surveys carried out by Sterner (1925), samples contained a total of 310 species (188 Albertson (1950), Rosen (1982) and Krahulec et al. vascular plants, 83 bryophytes, and 39 lichens). (1986) and expanded our sample to include the full Many of the vascular plant species are illustrated in range of dry alvar grassland communities. We did Ekstam et al. (1984). Plant nomenclature follows not attempt to produce a formal vegetation Flora Europaea (Tutin et al. 1964- 1980) (vascular classification (cf. Krahulec et al . 1986). plants), Corley et al. (1981) (mosses), Grolle (1983) The second aim of the study was to characterize (hepatics), and Santesson (1984) (lichens). All the distributions of the individual species within bryophyte and lichen samples have been deposited vegetational space, and particularly to characterize in The Herbarium, Uppsala University (UPS). and compare the ecological amplitudes of species which have disjunct or range-margin populations Data analysis in the alvar grasslands. The vegetation data were analysed using the or­ dination technique detrended correspondence analysis (DCA) (Hill & Gauch 1980, White & Glenn-Lewin 1984). Although variation in plant community composition was continuous, the clustering technique two-way indicator species

Acta phytogeographica suecica 76 Th e dry alvar grasslands of 0/and 23 analysis (Gauch 1982) was used to provide a conve­ nient summary of the main features of the varia­ tion pattern. The cluster-membership of all the species in the survey is presented in Table 1 and the number of samples in each cluster is given in Fig. 1. To illustrate the ecological amplitudes of indi­ vidual species, the samples in which the species of & [I () interest occur are picked out by symbols superim­ 0 6 0 • • posed on DCA plots of the total sample ordina­ 1 2 3 4 6 5 7 8 tion. This approach allows visual comparison of Fig. 1. Cluster hierarchy from a two-way indicator the relative ecological amplitudes of different species analysis of 43 1 vegetation samples from dry alvar species; a more sophisticated approach to the grasslands on Oland. Variation within the alvar handling of ecological amplitudes using DCA is grassland communities is more-or-less continuous, but we use a cluster representation to summarize the varia­ given by 0kland (1986). Analyses were carried out tion pattern and simplify discussion. The number of using the programs DECORANA and TWIN­ samples in the clusters is as follows: (1)35, (2)30, (3)32, SPAN (Hill 1979a, b). The program ALVPLOT (4)87. (5)92, (6)89, (7)29, (8)37. (written by W. Cramer & R. Leemans) was used to produce the species distribution illustrations.

soil types and depths and are characterized by fine­ scale spatial heterogeneity. The second axis of the ordination in Fig. 2 picks The plant communities out variation in community composition that is associated with soil moisture content; soil moisture Variation in plant community composition is increases with axis score along axis 2. shown in Figs. 1 & 2. Variation is more-or-less con­ tinuous, but we have used the cluster representa­ Closed grasslands on silicious soils (Clusters 1-3) tion in Fig. 1 as a convenient means of simplifying The plant communities in this group of clusters are and summarizing the pattern. However, it should characteristic of glaciofluvial deposits (sands and be remembered that members of a particular gravels) which have been reworked by the sea into cluster may lie nearer to members of other clusters a series of low mounds an� ridges. The soils are than to samples at the opposite extreme of their mainly composed of silicious material and vary in own cluster (cf. the central region of the ordination depth (from around (5)15-50 cm) and permeabil­ plot in Fig. 2). ity (Konigsson 1968, Rosen 1982, p. 10); pH The dominant trend in the ordination in Fig. 2 usually ranges between 5 and 7 (Krahulec et al. is a progression along axis 1, from closed com­ 1986) although lower values are recorded locally in munities with up to forty vascular plant species association with Juniperus bushes. The major m-2, to open, species-poor communities. The trend in plant community composition is asso­ closed grasslands are associated with com­ ciated with soil moisture levels. High scores on axis paratively deep, weakly acidic to mesic soils which 2 (cluster 1) are associated with more-or-less moist contain a high proportion of silicious material. At habitats on deep, brown, humus-rich soils (cf. the opposite end of the habitat gradient are open Albertson 1950), whereas the samples with the communities on highly calcareous soils. These lowest scores on axis 2 (cluster 2) are associated communities are frequently waterlogged in the with dry, sandy soils with a relatively low humus autumn and spring, dry in the summer and may be content. The transition to communities on more subject to extensive frost action. Between these base-rich soils (via cluster 3) is characterized by two extremes is a range of habitats associated with soils which vary in both composition and pH and fissures and cracks in the limestone; these in­ which contain a certain proportion of material de­ termediate habitats contain a mixture of different rived locally from calcareous weathering soils.

Acta phytogeographica suecica 76 24 Bengtsson, Prentice, Rosen, Moberg & Sj ogren

3.0

0 0 0

0

N • . !! >< cc 0 • 0

0 0

•

•

• [J •

0

0 4.5 Axis 1 Fig. 2. Detrended correspondence analysis of 431 vegetation samples from dry alvar grasslands on Oland. The sym­ bols indicate cluster membership in the cluster analysis that is presented in Fig. 1. White symbols indicate weakly­ acid to mesic, closed grasslands on deep soil; piebald symbols indicate communities occurring in a habitat mosaic of limestone crevices (with deep soils) interspersed with patches of shallow soil, calcareous gravel or open limestone; black symbols indicate open, species poor communities on frost-disturbed weathering soils.

The vegetation is a more-or-less dense herb-rich nium affi ne (Fig. 7e), Pore/la platyphylla (cf. Sjo­ sward with a matrix of A venula pratensis and gren 1964), Rhodobryum roseum (cf. Rosen & Sjo­ Festuca ovina (see Table 1). Typical species include gren 1988) and Th uidium erectum). Cladina arbuscula (Fig. 8f),Dicran um scoparium (Fig. 7a), Filipendula vulgaris, Ga/ium verum, CL US TER 1 Phleum phleoides Veronica sp icata. Species number 141. Average cover values (OJo); (Fig. 5h), and = This type of grassland (see Fig. 9a) has been tradi­ total 99, vascular plant 96, bryophyte 19, lichens 3. tionally maintained by grazing and by the removal of Juniperus; grazing continues in many areas but This cluster contains plant communities that are encroachment by junipers is a problem wherever transitional to the moist, mesic grasslands of the grazing is abandoned. Of interest in these closed Molinietum (cf. Albertson 1950). Cluster 1 in­ grasslands are a number of bryophyte species cludes the Galium boreale subassociation of the

which are regarded as typical of field-layer, trunk­ Veronica sp icata - A venula pratensis association base, or epilithic communities in deciduous or rich of Krahulec et al . (1986). Soils are deep (15-50 coniferous forests (e.g. Barbilophozia barbata, cm) and with a good moisture-retaining capacity, Brachythecium glareosum and B. salebrosum (also and are often associated with lateral seepage. The present in the more base-rich grasslands), Plagiom- vegetation is dense, herb-rich and lush and the

Acta phytogeographica suecica 76 Th e dry a/var grass/ands of 0/and 25

a Allium schoenoprasum b Antherlcum ramosum • ·... . ·· ­ . . ·. '\ .

. . ·'��· : / . · · ...... · . . . :.: ���;<; · .-�;• ·:': ... �- � . .. : .. � ... . · ...... __ ...... :·. . .. �,j�.�-. :� .•.. . ·, ' . ·. . . · ..·' .· ...•• , , . 11_!! . .. ·. -. !11 ., • • ··'. . • • • .• : � ··'! • ·• ...... · • . • • • .. •

c Apera interrupta Artemisia oelandica d •

· .

. � · .... . · :-:. · ·

• . ..� . ' ... •

e Artemisia rupestris Asperula tlnctoria f • • • • • • . • �. .:... . .··. • � ;'I . . . I . . • . . · ...... ·· ·. ·., . � • • ��... · it. . ·.· . : 1\i�···: · . .. . � ...... • � . : .. ;.... : ..� . . • . . ': :: , ··:- ...... • • · . . ·. • . ,. ...liij_r. ._;. . ·., . ., ' -·: • • ·. ·..-:: . . ; . • • . .. �· ··-.;·, ·•,, I ' .· •· "' .- ·:. : : . . · � ...... : . . . . . ' . . �:{ � . � · : • .

Fig. 3. Habitat amplitudes of six vascular plant species. The samples in which the individual species occur are in­ dicated by filled squares on the plot of the DCA ordination (cf. Fig. 2) which shows the overall pattern of variation in plant community composition. Samples in which the selected species are absent are indicated by dots. Axes and their lengths are shown in Fig. 2.

Acta phytogeographica suecica 76 26 Bengtsson, Prentice, Rosen, Moberg & Sj ogren

.. a Ce•rastium .. pumilum b Crepis tectorum

. . : . . : �·. '. · • :· . . . . �· • .·• • if. • ·•. . ,.. it .. ·. • ...... ,..:·�: ...... ·· �· e-�·· . , ...; ..... "i� .,...... : : • " �. · ...... • . .. . . ��� .. .. . • . • •• • I ::. •- \ .. 1 • "t • • • •

• • •

c Festuca oelandica d Fumana procumbens

· ...... · · • . · · · . ..:& :. · . �=

· . . � .. � . .: . •

. e Galium oelandicum f Globularia vulgaris

. . ,.. ta. . . • . : · .. . . . ' , . .. .. ' . .· ·: . . :.'.:,,.i.:··._.··: ...... I . · · . ·.·�:. •.· . • • . ·.

...... I ... .• �� -. . .. :I�:�- � •' • . . · . "h:.���: · ::--: ' . .. ' �:;g.":·:�f�.. _:= · -': _ · • •• 1. . •

.. Gypsophila fastigiata h Helianthemum oelandicum 9 • -· -· • ...... M .,· : .. �...... · • '!\. . . .� � :.. � , .. . • , . . • •. ' .-.. . . . • . . . •• -� it ...... ·"' .. � . . -·"�-�� ...... , .. �. � - ·...... : . . . _-: · .. · ' .. . '.f ' . · . �- . · . • .. .::. -.... , .. •·:- :': •..:.....-- ...... · . ... ' '· • . , .. . •\- ...... I • ' . . • . : . ..• � � .. I . : , _': :·�M : � • . • ll!laC__III , '!;'.Y-.-. �.. . . :;.11:�� . ... - ...... : . .. ·-�-,. �� ...... • •• · . -:�t�·�.--...... ; ..I: · ·• : ' ' �·• · ii

Fig. 4. Habitat amplitudes of eight vascular plant species. See the caption of Fig. 3 for explanation of the plots.

Acta phytogeographica suecica 76 The dry alvar grasslands of Gland 27

a Hieracium praealtum b Hornungia petraea

...... �· • ..· ;- -: . . · ·· . : . .: . � : . : .. : . . ' ...... ·.· · 11.• •••.. .. • • .. ..• . t • · . ... ·�.: . · ' ,. •...... -,.�·rl"'W �.�� . I .: .. . . .• . ' . I . . . .. •. • • .:.•' I •._... •, _. • •• .. ... - · �

c Lychnis alpina d Melica ciliata

.. ...

... •'

e Orchis ustulata • Oxytropis campestris . . "' ...... · . 11{ .. . · ·.·� • .. . . : I • .j • . . .· .. • •

g Petrorhagia prolifera h Phleum phleoides

'· ...... � . •, · . . . · · ... .; • · .. ·. • . �= ·.�· '· .. . • , ., .· ·' .... •• ..

Fig. 5. Habitat amplitudes of eight vascular plant species. See the caption of Fig. 3 for explanation of the plots.

Acta phytogeographica suecica 76 28 Bengtsson, Prentice, Rosen, Moberg & Sjogren

a Poa alpina b Prunella grandiflora • • •

· . ,. . .. . ' .. ..:·• . • ·.·�·

' • . . ..

� �

c Pulsatilla pratensis d Ranunculus lllyrlcus

•

• •

e Sedum reflexum Sisymbrlum supinum

......

.. ' · . , _. . � .

g Trifolium striatum h Vlncetoxicum hlrundinaria

... . •·. . . . � . . .:'I . . • . . .. � ·. . �,;,.·rr .. . '·...... ·.· · · . · . ·. · . • t ·:· · ii ·.tt: ... ••... .-:.;:_·...,,-...', .:··: . -;,:· . : · • . • • ·• _:.-. .. - Ill! . • • �.a ' ' · : • • - • ·' . . ,.;. ' • ..it...· . · . . . • .� �If..·· :··· ... ·, :I ...... � . . • I •

•

Fig. 6. Habitat amplitudes of eight vascular plant species. See the caption of Fig. 3 for explanation of the plots.

Acta phytogeographica suecica 76 The dry alvar grasslands of 0/and 29

a Dicranum scoparium b Encalypta vulgaris

• • �· � . .,--,: .. . .

:f.�; . \��:,��H:-/.:.}· • . .. . --'·. · ·� . . ;.•· .... .--. .. • I I • • • . .. •, •'•' • ' • • : I · J • . · : ••:• • ·. •,, . ... � ...... • .�':· . ·. . . · .. "' • rl' : . . . · ..., • .. . • • • < � . . ..

c Homalothecium lutescens d Hylocomlum splendens • • • • • .. ·--.; '· . • ...... • •. rl . � ... � , . . . .-...., . . . . -�· . . .. . • � ':. • ..... · t:.-·:· � ' . �. . • :': . . · · . . . . • - Ill. . . .. • ·.r... �-.' .,.. . , � •i, �· ...... � . . . : • • 11!. . : . • .' . • . . " �!�...... ' · ...... · . ' . ·.. ... : •' : .. . . .':- .· . . :·; : :· : . . . . , . .. . • •

•

e Plagiomnium affine Racomitrlum canescens • . . • ...... ' •

·.t; . .. ·=· · . • • · 11!. ,• •.· . ·- • , . ,. "' • .;,• • • I • •

•

g Scapania calcicola h Scorpidium turgescens ...... :;�.. : ·

· .

. ' . . ..�. ··: · �. -: . . .· �-; :��.:�; , :... . �·�-�:· · · · ·� .'!' : . · · . . I :';...... � . . . .· ·- . .. . _. ... ·.�:. ·. .. , ... . , - . ..,.� ...... l ••• • · �. ...·: �...·: ·· � .... • � ,• . · ·:.. �-. . ·•. : . . . · \ . . ( .

Fig. 7. Habitat amplitudes of eight bryophyte species. See the caption of Fig. 3 for explanation of the plots.

Acta phytogeographica suecica 76 30 Bengtsson, Prentice, Rosen, Moberg & Sj ogren

a Tortella inclinata b Trlchostomum crispulum • . · .. �·. i · . :: ·, ·. ··.�· • . • .: . . it . ' • ' . . . .. �. ' . :: �i'·��'l :': · ' •• •• :...... ' t •.. •• • • · ·. ·...... �:-.'111..���.1.' · ' • • . ;, .,· � � · . ... . ·- . �". ..,..-:..!...... I • .. • ··o�� v ., • . . -· .,... ·� .. ..,.� • . .. . {. ...; . .· • • •

c Cetraria alvarensis d Cetraria cucullata

. . . . . ·. ...-. · . · , .· · " · . · . •.. :: . :-. . \1:�-:;�;{/:· :· ...: : - , : ; .. . ;· . .• .

e Cetraria nivalis f Cladina arbuscula •

. ' �.

• � , ..

Fulgensia bracteata h Thamnolia vermicularis 9 ' ..",: �· ·.

. . ,, · . .. �· . · i, . . � : . :·: ..... · ;_1. . . �· �{�iJ:,, .; ,"1 .. ·· . . ·...... : :: ..: . :��:..-.� �1 (-- : . ·- • ; � . ?_l •...... ' . . � .: . ..,.. :· : .. ' . •:.·• ·. . • . .

Fig. 8. Habitat amplitudes of two bryophyte and six lichen species. See the caption of Fig. 3 for explanation of the plots.

Acta phytogeographica suecica 76 Th e dry alvar grasslands of Gland 31 highest number of vascular plant species m-2 (40) cur in a variety of different base-rich habitats, was recorded in this cluster. Species that are typical ranging from bare limestone and thin weathering of this cluster (see also Table 1) include A venula soils to deeper, clayey soils with considerable frost pubescens, Helianthemun nummularium, Hy lo­ disturbance. These open calcareous, Agrostis/ comium sp lendens (Fig. 7d}, Prune/la grandiflora Festuca grasslands divide into two major groups of (Fig. 6b) and Sesleria caerulea. Botrychium luna­ communities. Clusters 4-6 are characteristic of ria, Trifolium montanum and Potentilla erecta habitats associated with fissured limestone bed­ only occurred in this cluster. rock (see Figs. 9b-e). The fissures in the limestone are soil-filled, and the surface is either covered CL US TER 2 over by a thin layer of stony soil or gravel with the Species number 134. Average cover values = (OJo); underlying fissures identifiable only by strings of total 99, vascular plant 94, bryophyte 22, lichens 3. deeper-rooting vegetation (Fig. 9d), or the fissures may stand out clearly as a network of dense vegeta­ This cluster belongs to the drier part of the tion with intervening pans of bare limestone (Fig. "Avenetum alvarense" (Albertson 1950) and cor­ 9c). The clusters associated with these fissure responds to the Sedum reflexum subassociation of systems are the most species-rich of those that we the Veronica sp icata - A venula pratensis associa­ surveyed and contain the highest proportion of tion of Krahulec et al. (1986). Soils are somewhat species with disjunct or range-margin distribu­ shallower than in cluster 1, have a superficial tions. humus layer and are freely-draining. The vegeta­ Clusters 7 and 8 occur on more-or-less frost­ tion is herb-rich and dense, with a higher cover of heaved soils. Plant cover is sparse, open and often cryptogams than in cluster 1. Species that are tussocky (see Fig. 9f) and these habitats are tem­ typical of this cluster include (see also Table 1) An­ porarily inundated in the spring and autumn. thoxanthum odoratum, Bromus hordeaceus, Cladonia fu rcata, Homalothecium lutescens (Fig. CL USTER 7c}, Racomitrium canescens (Fig. 7f), Trifoliu m 4 Species number = 176. Average cover values (%); campestre, T. striatum (Fig. 6g), Veronica arvensis total 73, vascular plant 46 , bryophyte 15, lichens and, locally, Ranunculus illyricus (Fig. 6d). 23. CL US TER 3 This cluster is rich in species and contains a high Species number = 148. Average cover values (OJo); concentration of species which have disjunct or total 97, vascular plant 86, bryophyte 17, lichens 9. range-margin distributions. The highest total This cluster is more heterogeneous than clusters 1 number of species m-2 (5 1) was recorded from this and 2; soil depth is less (5-15 cm) and the cluster cluster. The species-richness is associated with represents a transition to communities on habitats which have a high degree of fine-scale heterogeneity: a single 1 1 m quadrat can con­ shallower and more base-rich soils. There are few x species that are especially characteristic of this tain open limestone, thin (1-5 cm) gravelly cluster, however Acinos arvensis, Medicago weathering deposits on top of the limestone, and lupulina and Sedu m reflexu m (Figs. 6e and 9a) are cracks and fissures in the limestone with an infill of more frequent than in the other "Avenetum" clus­ fine, deep ( > 25 cm) soil (see Figs. 9b-d). Patches of closed "Avenetum" type grassland in fissures ters and Lychnis alpina (Fig. 5c) and Pleuridium occur within a few centimeters of communities subulatum are confined to this cluster. The liver­ wart Barbilophozia barbata which occurs in this typical of thin weathering soils (cf. cluster 6). Soils cluster is usually regarded as characteristic of com­ are mesic to base-rich (pH 7 and above) and soil munities on tree bases and stones in deciduous and moisture varies greatly with soil type and soil depth. This type of vegetation falls within the Gyp­ rich coniferous forests. soph i/a fastigiata - Globularia vulgaris associa­ Open grasslands on calcareous soils (clusters 4-8) tion of Krahulec et al. (1986). The plant communities in this group of clusters oc- On the margins of areas with large scale karst

Acta phytogeographica suecica 76 32 Bengtsson, Prentice, Rosen, Moberg & Sj ogren

Fig. 9a. Closed vegetation on deep silicious soils (showing A venula pratensis, Filipendula vulgaris, Phleum phleoides and Sedum ref/exu m): cf. clusters 2-3. (9a-f, photo E. Rosen.)

topography, these mosaic habitats can contain a Species typical of cluster 4 are Cetraria alvaren­ high proportion of exposed limestone slabs or bed­ sis (Fig. Se), C. is/andica, Cladonia gracilis, Coelo­ rock (Fig. 9b). Lichen cover is often high (reaching caulon acu/eatum, Globu/aria vulgaris (Fig. 4f), values of up to 70 OJo ). The driest samples in cluster Gypsophilafastigiata (Fig. 4g), Hornungia petraea 4 (those with low scores on axis 2) contain many (Fig. 5b), Silene nutans, Melica ciliata (Fig. 5d), annual, biennial and short-lived perennial species, and Th amnolia vermicu/aris (Fig. 8h). Euphorbia and represent sites that are subject to relatively exigua was only found in this cluster. heavy grazing and trampling by cattle.

Acta phytogeographica suecica 76 Th e dry alvar grasslands of Gland 33

Fig. 9b. South-facing slope on dry, fissured limestone (with Fumana procumbens, Globu/a­ ria vulgaris and Silene nutans) : cf. cluster 4.

CL US TER 5 bitats transitional to that in cluster 7) Helian­ Species number 182. Average cover values (o/o); = themum oelandicum (Figs. 4h 9e) and Thy mus total 60, vascular plant 43, bryophyte 20, lichens 7. & serpyllu m form elongated hassocks of vegetation which pick out the pattern of the hidden fissures. Vegetation cover is somewhat sparser than in The species composition of cluster 5 agrees well cluster 4 and the underlying system of fissures in with that of Albertson's (1950) Helianthemum the limestone is more-or-less concealed by super­ oelandicum - Festuca ovina - Tortel/a tortuosa ficial deposits of stony soil (2-10 cm) (Figs. 9d­ association and falls within the Helianthemum e). Habitats in this cluster are in general moister oelandicum - Galium oelandicum association of than those in cluster 4. The fissures often support Krahulec et al. (1986). This is the most species-rich moisture-demanding species such as Carex flacca cluster and Orobanche alba is confined to this and Sesleria caerulea, suggesting that water is more habitat on bland. Typical species include An­ freely available within the fissure system even dur­ thericum ramosum (Fig. 3b), Carex f/acca, ing dry periods. Superficial water movement may Ctenidium molluscum, Globularia vulgaris (Fig. be extensive during spring and autumn, and after 4f), Gypsophilafastigiata (Fig. 4g), Helianthemum heavy rain in the summer. Where the overlying oelandicum (Fig. 4h), Sesleria caerulea and blanket of soil contains a high proportion of fine Vincetoxicu m hirundinaria (Fig. 6h). material, it often develops an almost gruel-like consistency during wetter periods. These overlying CL US TER 6 soils are also subject to frost disturbance which Species number = 112. Average cover values (o/o); may lead to local concentrations of coarse gravelly total 65, vascular plant 54, bryophyte 14, lichens 5. material on the surface. Trampling by cattle is an­ other important disturbance factor in these habi­ Cluster 6 includes a gradient between the open tats. Where the layer of soil overlying the fissured Crepis pumila - Alliu m alvarense association of limestone is thicker and more frost-heaved (in ha- Krahulec et al . (1986) and the species-rich, "karst-

Acta phytogeographica suecica 76 34 Bengtsson, Prentice, Rosen, Moberg & Sj ogren

Fig. 9c. Vegetation on fissured limestone with bare rock between the fissures (showing G/obularia vulgaris) : cf. clusters 4-5.

edge'' communities in cluster 4 which contain Fulgensia bracteata (Fig. Sg), Psora decipiens, small flecks of Sedum album/lichen vegetation on Scapania calcicola (Fig. 7g), Sedum acre and S. exposed limestone patches. This cluster is charac­ album, Thamnolia vermicularis (Fig. Sh) and terized by extremely thin (1-5 cm) weathering Tortella inclinata (Fig. Sa). Many species are con­ soils which are moist in spring and very dry in sum­ fined to this cluster (Table 1). mer. These soils lie directly on limestone. The CL US TER driest variant of this cluster (with low scores on 7 axis 2) is often found on the margins of extensive Species number = 159. Average cover values (O!o); limestone pans where there are few fissures and total 59, vascular plant 39, bryophyte 23, lichens 5. where water lies in ephemeral surface pools during wet periods. Superficial frost disturbance in fine­ Cluster 7 consists of open, species-poor, tussocky grained calcareous gravel becomes more extensive Festuca vegetation. The soils are 5-10(15) cm in habitats on the transition to cluster S, creating deep heavy calcareous clays which also contain microhabitats that are suitable for annuals and some coarser material. The soil is often flooded for cryptogams. The highest number of cryptogam long periods in the spring and autumn and remains species m-2 (22) was recorded from this cluster. somewhat moist during the summer. Drainage is Species typical of the cluster (see Table 1) in­ poor and frost disturbance is widespread and pro­ clude Alliu m schoenoprasum (Fig. 3a), Cetraria nounced (see Fig. 9f & Rosen (19S2 Fig. 11)). nivalis (Fig. Se), Cladonia sy mp hycarpa, Crepis Typical species include (see Table 1) Anagallis tectorum (Fig. 4b), Poa alpina (Fig. 6a), Cerastium arvensis, Campy lium elodes, Festuca oelandica pumilu m (Fig. 4a), Didymodon jerrugineus, (Fig. 4c), Galium oelandicu m (Fig. 4e), Hieracium Ditrichum jlexicaule, Encalyp ta vulgaris (Fig. 7b ), cf. praealtum (Fig. 5a), Leontodon autumnalis,

Acta phytogeographica suecica 76 The dry alvar grasslands of Oland 35

Fig. 9d. Closed vegetation on fissured limestone with cal­ careous weathering soil between the fissures (showing Festuca ovina and Gypsophila fa stigia­ ta): cf. clusters 4-6.

Prune/la vulgaris and Sisymbrium supinum (Fig. are confined to this cluster. Plantago tenuiflora 6t). has its. only occurrence in this cluster (cf. Sterner 1922, Table 7). CL US TER 8 Species number 86 Average cover values (%); = . total 56, vascular plant 54, bryophyte 3, lichens 1. The species \ The vegetation in this cluster is even sparser than :,,' -... Ecological amplitudes of species within the alvar that in cluster 7. Soils are similar to those in cluster plant communities 7, but somewhat thinner and with a higher propor­ We have chosen to focus the discussion of tion of coarser material. Frost action is evident (see ecological amplitudes on a selection of species Ros� 1982 Fig. 1 0) but not as pronounced as in which. occur as disjunct or range-margin isolates cluste "'7. The habitat is seasonally flooded and the on Gland. These species are illustrated in Figures soil is baked dry in the summer. The vegetation 3-8 and show a wide range of distribution types contains a high proport�on of grasses; cover is pat­ within the alvar vegetation. Although no species chy with low Festuca and Agrostis tussocks. have precisely overlapping habitat tolerances, they Typical species (see Table 1) include Agrostis can be grouped into a series of broad categories ac­ gigantea/A. stolonifera, (most of the material in · cording to the range of plant communities (habitat this habitat is probably A. gigantea, cf. Appendix types) that they occupy. 1), Artemisia rupestris (Fig. 3e), Festuca oelandica (Fig. 4c), Hypnum bambergeri, Poa alpina (Fig. Widely distributed sp ecies (Clusters 1-7) fl) . 6a), Sagina nodosa, Schistidiu m ap ocarpum and Helitl�themum oelandicum (Fig. 4h) occurs almost Scorpidium turgescens (Fig. 7h). Several species throughout the dry grasslands and is absent only

Acta phytogeographica suecica 76 36 Bengtsson, Prentice, Rosen, Mo berg & Sj ogren

Fig. 9e. Vegetation dominated by Helianthemum oe/andicum (also showing Allium schoenoprasum, Cirsium acaule and Th amnolia vermicularis) : cf. clusters 5-7.

from the driest situations or most closed vegetation also have distributions that are transitional be­ (Table 1). tween the "Avenetum" grasslands and more calcareous habitats: Sedum rejlexum is character­ (2) Sp ecies of weakly acid to mesic grasslands on istic of the drier habitats and the other two species deeper soils (Clusters 1-2) of moister habitats. Orchis ustulata (Fig. 5e) is scattered throughout Sp ecies of open, calcareous grasslands the "Avenetum" grasslands, whereas Trifolium (4) (Clusters 4-8) striatum (Fig. 6g) and Ranunculus illyricus (Fig. Cerastium pumilum (Fig. 4a) and Trichostomum 6d) are restricted to the drier habitats. Artemisia crispulum (Fig. 8b) are widespread throughout the oelandica (Fig. 3d) is only present in the moister open, calcareous grasslands. Hornungia petraea habitats. (Fig. 5b) and Crepis tectorum (Fig. 4b) are wide­ , spread in the drier habitats. (3) Sp ecies of Htransitionar , mesic to calcareous grasslands (Clusters 1-4) (5) Sp ecies of communities on fissured limestone Cetraria cucullata (Fig. 8d), Lychnis alpina (Fig. (Clusters 4-6) 5c), Oxytropis campestris (Fig. 5f), Phleum Cetraria nivalis (Fig. 8e) and Th amnolia ver­ phleoides (Fig. 5h) and Pulsatilla pratensis (Fig. micularis (Fig. 8h) are general in this habitat. An­ 6c) have distributions more-or-less centred on thericum ramosum (Fig. 3b) is only found in the cluster 3. Oxytropis and Phleum show relatively moister habitats . Globularia vulgaris (Fig. 4f), wide habitat amplitudes; Lychnis alpina is more Gypsophila fastigiata (Fig. 4g) and Vincetoxicum restricted. Asperula tinctoria (Fig. 3f), Prunella hirundinaria (Fig. 6h) are centred on clusters 4 and grandijlora (Fig. 6b) and Sedum reflexum (Fig. 6e) 5, but avoid the moistest habitats. Allium

Acta phytogeographica suecica 76 Th e dry alvar grasslands of Oland 37

Fig. 9f. Tussocky, species-poor vegetation on frost-heaved calcareous soil (showing Festuca oelandica and F. ovina): cf. clusters 7-8. schoenoprasum (Fig. 3a) is characteristic of the supinum (Fig. 6t) are both restricted to the open drier habitats. Cetraria alvarensis (Fig. Se), and sparsely vegetated communities that occur in Fumana procumbens (Fig. 4d), Melica ciliata (Fig. habitats without fissures. Apera interrupta (Fig. 5d) and Petrorhagia prolifera (Fig. 5g) have ex­ 3c), Fulgensia bracteata (Fig. 8g) and Poa alpina tremely restricted amplitudes within the drier (Fig. 6a) occur in habitats that are summer-dry and habitats. not disturbed by extensive frost action; in contrast, Festuca oelandica (Fig. 4c ), Galium oelandicum (6) Species of open communities on calcareous (Fig. 4e) and Hieracium cf. praealtum (Fig. 5a) oc­ soils (Clusters 6-8) cupy the habitats that are subject to extensive frost Artemisia rupestris (Fig. 3e) and Sisymbrium disturbance.

Acta phytogeographica suecica 76 38 Bengtsson, Prentice, Rosen, Moberg & Sj ogren

Geographic distribution in relation to campestris (Fig. 5f) and Sisymbrium supinum (Fig. ecological amplitudes of range-margin 6f) are less extensively distributed. and disjunct populations on Oland The alvar grasslands include a number of taxa which are regarded as endemic to bland (or to The phytogeographical ranges of the vascular bland and Gotland). Most of these so-called plant species discussed above are mapped (on vari­ endemics are restricted to the open communities on ous geographic scales) in Sterner (1922, 1938), calcareous soils. The status 'endemic' is strongly Hulten (1971), Hulten & Fries (1986) and Jalas & dependent on the opinions of the systematists who Suominen (1972-1986). A large proportion of the have produced particular classifications, the de­ species illustrated in Figures 3-6 are represented gree of geographic isolation displayed by the taxon on bland by satellite populations on the northern and the detail in which the variation within a par­ or northwestern margin of their main distribu­ ticular species-complex has been investigated (cf. tions. The bland populations of species such as Prentice 1976). Detailed study of the disjunct Fu mana procumbens (Fig. 4d) and G/obularia bland populations of many species is likely to vulgaris (Fig. 4f), represent extreme northern dis­ demonstrate local morphological differentiation junctions from more southern ranges. Species such and 'alvar races' which can be distinguished from as Sedum reflexum (Fig. 6e) are on their northern material from elsewhere in the species' ranges. The range margin, but not markedly disjunct from bland 'endemics' Allium schoenoprasum var. their main distributions. Gypsophila jastigiata alvarense and Silene vulgaris ssp. maritima var. (Fig. 4g) is representative of a group of species petraea appear to represent poorly-differentiated whose northern and western distributional margin local races within widespread and variable species, in the Baltic region is represented by a constella­ while Galium oelandicum and Festuca oelandica tion of disjunct isolates. show more obvious morphological differentiation There is no clear relationship between geo­ and are recognized as species in Tutin et al. graphic range-marginality. and ecological ampli­ (1964-1980). Artemisia oelandica, which is char­ tude within the dry alvar communities. Range­ acteristic of closed "Avenetum" grasslands margin species such as Gypsophila fastigiata (Fig. seldom reproduces by seed and may represent a 4g) and Globularia vulgaris (Fig. 4f) are relatively more-or-less clonally reproducing isolate from the widely distributed within open communities on steppe species A. laciniata. fissured limestone whereas Ranunculus i/lyricus The tendency to equate range-marginality with (Fig. 6d), on the northwestern limit of this distri­ 'ecological-marginality' (cf. Brussard 1984) is an bution, is mainly restricted to more closed com­ oversimplification. That a population is on the munities on dry, non-calcareous soils. Range­ margin of a species' geographic distribution does margin populations as a group do not appear to not necessarily imply that the population is at the have especially restricted habitat amplitudes, nor is limit of the species' potential physiological or there a marked grouping of northern range-margin ecological distribution. Historical factors may also species into similar habitats. Hornungia petraea play an important role in determining the shape of (Fig. 5b), Sedum reflexum (Fig. 6e) and Trifolium a species' distribution. striatum (Fig. 6g) occur in the drier habitats; An­ For species which are dependent on open habi­ thericum ramosum (Fig. 3b), Asperula tinctoria tats, it is the availability of those habitats that is (Fig. 3f) and Prune/la grandiflora (Fig. 6b) are the primary constraint on the overall distribution confined to communities in moist situations. pattern. Physiological or phenological limits repre­ Species which have overall geographic distribu­ sent an absolute distributional limit which may tions that are internally disjunct also show a range never be approached for reasons of history or of habitat amplitudes within the alvar grass lands. habitat availability. That many of the phytogeo­ Helianthemum oelandicum (Fig. 4h) occurs in vir­ graphically celebrated alvar species on bland are tually the entire range of plant communities, on the margin of their geographic distributions Cerastium pumilum (Fig. 4a) and Hornungia does not indicate that they have reached an ab­ petraea (Fig. 5b) are also widespread; Oxytropis solute distributional margin beyond which they are

Acta phytogeographica suecica 76 The dry alvar grass/ands of 0/and 39 unable to reproduce and establish successfully. As contained the highest number of species in the a group these species are dependent on open habi­ survey. tats, and such habitats are rare in the forested Gypsophila jastigiata is extensively distributed landscape of northern Europe. on calcareous soils on bland, and the populations The group of disjunct species (Apera interrupta on Stora Alvaret are dense and numerically large; (Fig. 3c), Artemisia rupestris (Fig. 3e), Poa alpina seed production is high and seedling establishment (Fig. 6a) and Sisymbrium supinum (Fig. 6f) that predictable (K . Bengtsson, unpublished observa­ are restricted to the most open habitats all have tions). In northeastern Finland, G. fastigiata is classic, internally disjunct, geographic distribu­ restricted to dolomitic cliffs and, in seasons with tions. But the overall distribution patterns of these short summers, the individuals which are in more species differ markedly; Poa a/pina has a nearly shaded microhabitats are unable to produce ripe circumpolar arctic-alpine distribution, Artemisia seed (H. C. Prentice, unpublished observation). rupestris ranges from eastern Europe into central Both the bland and the northeastern Finnish and eastern Asia, and Apera interrupta is scattered populations are distributionally marginal, but only across Europe and extends into central Asia and the Finnish populations show obvious signs of North Africa. One can speculate that it is the rarity ''ecological marginality''. of suitable areas of nearly competition-free habitat Fumana procumbens (Fig. 4d) belongs to the that is responsible for the distinctive, fragmented small suite of northern range-margin species (see distribution patterns shown by these species. also Melica ciliata (Fig. 5d) and Petrorhagia pro­ Helianthemum oe/andicum, which is on its ex­ /ifera (Fig. 5g)) that are confined to sheltered treme northern range-margin on bland, is clearly habitats on limestone bedrock (cluster 4 in Figs. 1 not in an 'ecologically marginal' situation. The & 2, see also Fig. 9b). There is little microclimatic species occurs in a wide range of alvar habitats data from the alvar on bland, but the study by (Fig. 4h) and is represented by extensively Coulianos (1973) supports the prediction that distributed and numerically extremely large microhabitats on limestone bedrock may have populations (cf. Widen 1980). microclimates that are substantially warmer than However, on bland, it is difficult to separate the those in surrounding habitats. Melica ciliata and effects of regional or local climate and the Petrorhagia prolifera also occur in habitats outside availability of open habitats. bland has warm the scope of the present survey. M. ciliata is most summers, relatively low summer precipitation and characteristic of areas of karst habitat on the alvar, a high number of sunshine hours per year (see but also occurs on stony beach ridges and west­ Rosen 1982 p. 11-15 and Widen 1980 for refer­ and south-facing cliffs: P. prolifera occurs in ences). It is also probable that the climate associa­ open, sandy habitats and on south-facing morainic ted with the areas of limestone is locally warmer cliffs-again habitats that are both open and than in the surrounding areas as a result of the warm. relatively high heat retaining capacity of the lime­ There is a need for comparative demographic stone. There is a tendency for species with range­ studies of ecologically restricted species, such as margin or disjunct distributions to have com­ Fu mana procumbens, and of more widespread munity preferences centred on habitats associated species, such as G/obu/aria vulgaris and Gyp­ with fissured limestone bedrock (clusters 4-6 in sophila fastigiata, on bland. If data on reproduc­ Fig. 2). This habitat preference may be a result of tive performance and seedling establishment can a generally more favourable local climate. How­ be related to microclimatic measurements from a ever, the high concentration of distributionally range of alvar habitats, it may be possible to estab­ marginal or disjunct species in the calcareous lish to what extent these species can be regarded as habitats may also be a consequence of the fine­ 'ecologically' as well as distributionally marginal scale habitat diversity: these plant communities on bland.

Acta phytogeographica suecica 76 40 Bengtsson, Pren tice, Rosen, Moberg & Sj ogren

Table 1. Summary of the species occurrences in the different grassland vegetation types. The vegetation cluster numbers are those given in Fig. 1 (see also Fig. 2). Species are arranged alphabetically within each of five categories (gymno­ sperms/ferns, dicotyledons, monocotyledons, bryophytes, lichens). The status of each species in each cluster is summarized by a) the percentage of the samples in which it occures, b) its

SPECIES CLUS CLUS 2 CLUS 3 CLUS 4 CLUS 5 CLUS 6 CLUS CLUS 8 1 7 AVE AVE AVE AVE AVE AVE AVE AVE % MAX MAX MAX % MAX MAX % MAX % MAX % MAX

Junipe rus communis 14 3 17 31 7

Achillea mi llefolium 74 66 22

Ac inos arvensis 10 74 78 21 87 59

Anagallis arvensis 13 51 24

An drosace septentr. (1) 10

Antenna ria dioica 57 3 5

Anthyllis vulneraria 45 53 54 82 57 43

Arabis hirsuta 11 20 16 19 4 12

Arena ria serpyllifolia 25 80 54 88 24 84 10

Artemisia campestris 6 32 71 15 31

A. oelandica 7

A. rupes tris 7 24

Aspe rula tinctoria 94 30 22 70 52

Bupleu rum tenuissimum

Cal luna vulga�is 34

Campanu la rotundi folia 45 12 44 50 21

Carlina vu lgaris 1 4 6

Centaurea jacea

Cerastium pumi lum * 13 35 90 29 91 14 75

semidecandrum 40 73 35 34 11 c. Chaenorrhinum minus 1 14

Cirsium acaule 28 18

C. vulga �e 10

Convolvulus a�vensis 32 12 14 48

Crepis tectorum * 4 26 29

Daucus carota

Dianthus deltoides 30

E�igeron acer

Erodium cicutarium

Erophila verna 20 54 61 56

Eupho rbia exigua

Euphrasia stricta * 8 16 20 13 18 33 29

Filipendula vulgaris 1100 80 87 22 22 20 23 10 Fragaria viridis I Fumana procumbens I Galium boreale 1 45 5 32

G. oelandicum 2 3 13 40 10

G. ve rum 94 100 80 79 31 28 8

Gentiane lla uliginosa * 1 13

Ge ranium co lumbinum 21

G. mo lle

Globularia vul garis 25 40 47

Gypsophila fastigiata 73 71 64

Helianthemum nummularium l 71 36 5 25 14

H. oelandicum * 45 16 4 38 59 94 78 7 48 16

Herniaria glabra 3

Hieracium pilosella 65 5 40 58 48 28 18

H. cf . praealtum * 10 1 70 24

Hornungia pet raea 12 78 23 74 13

Hypericum pe rforatum 6 8 3

Hypochoeris maculata 19

Le ontodon autumnalis 59 35

Lina �ia vulgaris

Linum catharticum 40 58 45 81 46 96 83

Lo tus corniculatus 31 36 16

Acta phytogeographica suecica 76 Th e dry alvar grasslands of Oland 41

Table 1 (cont'd) maximum cover/abundance value (max), c) its mean cover/abundance (rounded to the nearest cover/abundance category) (AVE). The list of additional taxa at the end of the main table contains species which occurred less than three times in the survey, as well as occurrences of seedlings or non-flowering material which could only be assigned to genus.

SPECIES CLUS 1 CLUS 2 CLUS 3 CLUS 4 CLUS CLUS CLUS 7 CLUS

AVE AVE AVE AVE AVE AVE AVE AVE % MAX MAX % MAX MAX % MAX % MAX % MAX % MAX

Lychnis alpina * 9

Medicago lupulina 13 41 41 10 24 14

M. sat iva * 5

Myosotis stricta 50 9

OKyt ropis campestris 37 20 16 29

Petrorhagia prolifera 3

Plantago lanceo lata 80 90 67 20

P. ma ritima

Polygala vulgaris

Potentilla argentea

P. fruticosa 10

P. tabernaemontani 74 50 45 40 21 22 11 * Prunella grandi flora 45 8

P. vul ga ris 11 66 29

Prunus spinosa 10

Pu lsatilla pratensis 31 35 22

Ranunculus bulbo sus 40 73 58 18

R. illyricus 36 6

Rosa canina

RumeK acetosella

Sagina nodosa 13 22 59

SaKifraga granulata 5 46 16

tridactylites 6 26 26 13 s. Scabiosa columba ria

Scleranthus annuus 30

Sedum acre 14 70 41 24 20 71

album 12 86 17 64 33 70 s. refleKUm 11 33 61 s. Senecio jacobaea * 14 5

Silene vulgaris * nutans 39 s. Sisymbrium supinum 22 16

Sonchus oleraceus stellaria graminea 28 36

TaraKacum sp . 62 73 64 70 22 2 31 13

Thymus serpyllum 80 60 64 71 88 85 77 54 7 Trifolium arvense 13

T. campestre 20 86 51 10

T. dubium 16

T. pratense

T. repens 16

T. striatum 43 19

Veronica arvens is 5 70

V. spicata 60 53 51 11

Vicia tetraspe rma 36

Vincetoxicum hi rund. (2) 54 37 10 7 Viola arvens is 10 2

V. hi rta

V. rupestris 12

V. tricolor

Ag rostis capillaris 34 43

A. giganteajs tolonifera* 3 19 32 46 48 66 (100

A. vinealis 68 36 67 33 28 36 77 37 I Al lium schoenoprasum * 35 32 7 32 I A. vineale 13 29

Acta phytogeographica suecica 76 42 Bengtsson, Prentice, Rosen, Moberg & Sj ogren

Table (cont'd) 1

SPECIES CLUS 1 CLUS 2 CLUS 3 CLUS 4 CLUS 5 CLUS 6 CLUS CLUS AVE AVE AVE AVE AVE AVE AVE AVE % MAX MAX % MAX % MAX % MAX % MAX % MAX % MAX

------

Anthericum ramosum 18

An thoxanthum odoratum 28 56 41 Ape ra interrupta Avenu1a pratensis 97 80 70 37 42 21

A. pubescens 34 3 16 21 1

Briza medi a 54 13 12

Bromus ho rdeaceus 5 63 4 16 10 20

Carex cary.jeric. ( 3 ) . 88 63 5 64 33 5

c. f1acca 17 12 12 73 5 27 6 7 5

Dacty1orhiza sambucina 7

Danthonia decumbens 22 E1ymus repens 10 Festuca oe1andica 5 11 7 78 ·n F. ovina 100 96 100 7 96 95 96 9 91 lOO Luzu1a campestris 54 43 22 Me 1ica ciliata

Orchis mascu1a 1 4 22 5 ustu1ata 14 13 9 0. Ph1eum phleoides 31 26 29 12

P. pratense . 37

P1atanthera ch1orantha Poa a1pina 12 18 P. angustifo1ia 20 12 P. compressa 14 6 32 12 22 11 29 10 Ses1eria caerulea 22 3 3 37

Atha1amia hyalina * 21 13 10 Barbilophozia ba rbata 12 1 Ba rbu1a convoluta 14 16

B. sp . 12 27 40 Brachythecium glareosum

B. salebrosum

Bryum argenteum 12

B. capillare 3 10 7

B. sp. 8 22 45 5 26 41 7 21 Campylium calcareum 2 11 c. chry sophyllum 6 elodes 36 16 59 48 c. c. sp . 1

Cephaloziella div. ( 4) . 11 7 sp. c. Ce r atodon purpureus 12 12

Ctenidium mo lluscum 70 40 62 18

Oicranum scopa rium 62 63 58 42 1 2

Didymodon ferrugineus . 13 Di stichium capillaceum 2 3 Di trichum flexicaule 11 12 80 91 91 7 62 94 Drepanocladus sp .

Encalypta rhapdocarpa 12 E. streptocarpa 1 8

E. vulgaris 19 41 24 Fissidens adianthoides

F. cristatus var. 48 23 70 67 63 48 22 35 + Grimmia pulvinata 4 5 6 Homalothecium lutescens 57 7 70 32 26 38 35 37

H. sericeum 13 7 1

Hy1ocomium splendens 42 5 10

Hypnum bambergeri 22 27

H. cupressiforme 80 7 86 87 8 5 79 69 68 7 29 13

Acta phytogeographica suecica 76 The dry alvar grasslands of 0/and 43

Table (cont'd) 1

SPECIES CLUS 1 CLUS 2 CLUS 3 CLUS 4 CLUS CLUS CLUS 7 CLUS

AVE AVE AVE AVE AVE AVE AVE AVE % MAX % MAX MAX MAX % MAX % MAX % MAX % MAX

H. cupress.var.lacun . ( 5 ) 5 Lophozia excisa

L. sp . 12

Myu rella julacea 13 21 Phascum cuspidatum 6

Plagiomnium affine 34 60 19 * Pleuridium subulatum 12 Pohlia sp.

Polytrichum junipe r inum

Porel1a platyphylla 2

Pt ilidium ciliare 31 10 16

Racomitrium canescens 14 40 22

Rhodobryum roseum 31 20 12 Rhytidiadelphus triq.(6 ) 7

Rhyt idium rugosum 45 5 33 32 28 5 25 20 Riccia soroca rpa R. subbifurca • R. sp. scapania calcicola 26 42

Schistidium apocarpum 21 25 67 Scorpidium scorpioides 2

s. turge scens 11 67

Thuidium abietinum 45 63 16 14 23 30 11 10

T. erectum *

Tortella inclinata 34 25 7 45 14 43 8 5

T. tortuosa 78 80 75 51 72 8 5 Tortula ruralis 11 33 29 5 13 35 5 Trichostomum crispulum 4 13 11 24 Weisia bra chyca rpa 2 * W. sp . 12 27 11 3 7 14 Cet raria alvarensis 5 4 3 * cucul lata 11 5 5 3 c. C. islandica 62 60 77 97 8 46 45 * nivalis 9 21 20 30 c. 5 Cladina arbuscula 11 10 19 4

ciliata 31 10 25 5 c. C. rangiferina 17 13 12

C1adonia foliacea 3 16 67 14 * furcata 68 73 80 88 47 60 11 c. * macroceras 40 30 48 42 5 43 40 33 c. C. poci1lum 12 58 14 30

C. pyx idata 10 32 1 * symphycarpa 25 40 5 48 54 7 2 5 13 c. Coelocaulon aculeatum * 13 16 49 5 44 45 Collema sp.

Fulgens ia bracteata 7 54 32 Hypogymnia physodes 9 18 26

Pe ltigera rufescens 23 9 22 12

Psora decipiens 24

P. lurida 16 Squamarina cartilaginea

Thamnolia vermicularis 43 31 44

* See Appendix 1 (4) Cephaloziella divaricata (1 ) Androsace septentrionalis Hypnum cupressiforme var. lacunosum (5) (2) Vincetoxicum hirundinaria (6) Rhytidiadelphus triquetrus (3) Carex ericetorum/C. caryophyllea (additional taxa listed on p. 44)

Acta phytogeographica suecica 76 44 Bengtsson, Prentice, Rosen, Moberg & Sj ogren

Table 1 (cont' d) APPENDIX 1. Taxonomic and nomen­ Additional taxa. The numbers after the species names are clatural notes the codes for the clusters where they occur (see Fig. 1 ). Vascular plants Botrychium lunaria 1; Pinus sylvestris 5; Anthemis arvensis (1) Cerastium pumilum includes ssp. pumilum and ssp. 4; Bellis perennis 2; Carduus nutans 4; Campanula per­ pal/ens (C. glutinosum Fries). sicifolia Centaurea nigra Centaurium littorale 8; 1; 1; Cerastium sp. 1-3, 5-7; Cotoneaster integerrimus 5; Fragaria vesca 3; Galeopsis ladanum 7; Geranium dissec­ Crepis tectorum. The alvar material of this species dif­ tum 1, 6; G. pusillum 5; Hieracium sp. 8; lnula salicina 8; fers from the commoner, weedy taxon and is usually Knautia arvensis 4; Lappula squarrosa 7; Leontodon referred to ssp. pumi/a (Liljebl.) Sterner. See also hispidus 4; Medicago sp. 4, 6; Mentha aquatica 8; Andersson (1988). Myosurus minimus 6; Orobanche alba 5; Pimpinella saxi­ fraga 5; Plantago tenuiflora 8; Polygonum aviculare 6; Euphrasia stricta E. stricta var. stricta (cf. Karlsson Potentilla collina 4; P. erecta 1; P. reptans 2, 7; P. sp. 1-7; 1986). Ranunculus acris 4; Rhinanthus minor 2, 8; R. sp. 2, 8; Scutellaria hastifolia 6; Senecio vernalis 6; S. vulgaris 4; Succisa pratensis 4; Teesdalia nudicaulis 3; Thalictrum Gentianella uliginosa. Most of the material from (>land simplex 1, 5; Trifolium medium 1, 2; T. montanum 1; T. sp. previously assigned to G. amarel/a belongs in this taxon 2; Vicia cracca 2; V. hirsuta 2; Viola canina 1; Alopecurus (b. Nilsson, pers. comm. 1987). geniculatus 8; Arrhenatherum elatius 3; Carex panicea 8; Dactylis glomerata 3; Juncus bufonius 8; Orchis morio 1, 2; Helianthemum oelandicum. Includes material referred Orchis sp. 1; Polygonatum odoratum 4, 5; Brachythecium to H. canum and H. italicum ssp. rupifragum. Widen albicans 8; Bryum neodamense 8; Calliergonella cuspidata (1980, 1986) divides the H. oelandicum complex on 6, 7; Campylium stellatum 7; Climacium dendroides 6; bland into two groups on the basis of their flowering Dicranum bon eanii 1; D. fuscescens 2; muehlenbeckii 3; j strategies and variation in leaf hairiness, but we did not Distichium inclinatum 6, 8; Encalypta sp. 6; Fissidens sp. 5; Frullania dilatata 8; Orthotrichum rupestre 5, 6; Pohlia distinguish between the groups in the present survey. nutans 1, 4; Polytrichum piliferum 3; PottiaD. lanceolata 6; Reboulia hemisphaerica 6; Tortella rigens 5, 6; Tortula Hieracium cf. praealtum. Includes material previously subulata 4; Trichostomum sp. 8; Cladonia coccifera 1; C. assigned to Hieracium dichotomum Fries and H. floren­ coniocraea 3; C. gracilis 1, 3; C. macrocarpa 5; Collema tinum Naegli & Peter. The taxonomic status of this crispum 6; Endocarpon pusillum 4; Evernia prunastri 6; group of taxa in the Baltic region is uncertain (T. Fulgensia fulgens 6; Lecidea demissa 6; Lempholemma Karlsson, pers. comm. 1987). cladodes 6; Parmelia saxatilis 1, 3; Peltigera canina 2; P. elisabethae P. membranacea 2; Physconia muscigena 4; 1; Lychnis alpina. Alvar material of this taxon from bland Squamarina lentigera 6; Toninia caeruleonigricans 6. has been called var. oelandica Ahlquist.

Medicago sativa M. sativa ssp. fa lcata. =

Potentilla tabernaemontani. Includes P. cinerea and a range of intermediate forms between the two species. See Asker (1986) for further discussion of this apomictic species complex.

Senecio jacobea. All our material can be assigned to ssp. gotlandicus Neuman. Acknowledgements. We would like to thank Eddy van der Maarel for his guidance and support, and Rik Silene vulgaris. Alvar material of this species is often Leemans and W olfgang Cram er for statistical advice assigned to ssp. maritima var. petraea Fries, which is and for the programs that they wrote for us. We would supposedly endemic to bland (and possibly Gotland) also like to thank Lennart Agren and the staff at the (cf. Sterner 1938). However intermediates between Ecological Research Station of Uppsala University for typical ssp. vulgaris and ssp. maritima are widespread. providing such a fine base for the fieldwork, and Thomas Karlsson for nomenclatural advice. We are Agrostis gigantea/A. stolonifera. Most of our material grateful to Christian Andersson, Cajo ter Braak and probably belongs to A. gigantea, A. stolonifera being Bjorn Widen for help and/or discussion. The study was more characteristic of extensive seasonally-inundated supported by grants to H. C. P. and E. R. from the Na­ depressions which were not within the scope of the pre­ tional Swedish Environment Protection Board (SNV), sent survey. Because our survey was carried out in the and to H. C. P. from the Swedish Natural Science Re­ year after a severe drought, most of the Agrostis ma­ search Council (NFR) and the Axel and Margaret terial was newly-established from seed and therefore Ax:son Johnson Foundation. non-flowering. A proportion of our material could not

Acta phytogeographica suecica 76 Th e dry alvar grasslands of 0/and 45

be unambiguously assigned to one taxon or the other in Crepis tectorum ssp. pumila. - Acta phytogeogr. and we were forced to handle A. gigantea and A. suec. 76. stolonifera as a single taxon in the analyses. Asker, S. 1986. Variation in some apomictic Nordic Potentilla species. - Symb. bot. upsal. 27(2): Allium schoenoprasum. Alvar material of this taxon 199-205. from bland and Gotland has been called var. alvarense Berglund, B. E. 1966. Late-Quaternary vegetation in Hyl. eastern Blekinge, southeastern Sweden. I. Late­ Glacial time. - Op. bot. Lund 12(1): 1-180. Carex caryophyllea ericetorum. These species were Brussard, P. F. 1984. Geographic patterns and en­ I C. treated as a single taxon for the purpose of the analyses, vironmental gradients; the central-marginal model in since non-flowering material could not always be Drosophila revisited. - Ann. Rev. Ecol. Syst. 15: reliably assigned to one or the other taxon. 25-64. Corley, M. F. V., Grundwell, A. C., Diill, R., Hill, M. & Smith, A. J. E. 1981. Mosses of Europe Phleum pratense = P. pratense ssp. bertolonii. 0. and the Azores; an annotated list of species, with (2) Bryophytes synonyms from the recent literature. - J. Bryol. 11: Didymodon fe rrugineus (Schimp. ex Besch.) M. Hill is 609-689. a synonym for Barbula ref/exa (Brid.) Brid., Plagiom­ Coulianos, C.-C. 1973. Seed bugs (Het., Lygaeidae) nium affi ne (Bland.) T. Kop. for Mnium affi ne Bland., from the Great Alvar of bland, Southern Sweden. Th uidium erectum Duby for Th uidium delicatulum Some observations on their distribution in relation to (Hedw.) Mitt. and Weissia brachycarpa (Nees et food and microclimate . - Zoon, Uppsala, Suppl. 1: Hornsch.) Jur. for We issia microstoma (Hedw .) C. 115-122. Miill.; among the hepatics Cepha/oziella divaricata Ekstam, U., Jacobsson, R., Mattson, M. & Porsne, T. (Sm.) Schiffn. is a synonym for Cephaloziella starkei 1984. blands och Gotlands vaxtvarld.- Stockholm. (Funck ex Nees) Schiffn., Athalamia hyalina (Som­ Endler, J. A. 1982. Problems in distinguishing historical merf.) Hatt. for Clevea hyalina (Sommerf.) Lindb. and from ecological factors in biogeography. - Am. Riccia subbifurca Warnst. ex Crozals for Riccia oelan­ Zool. 22: 441 -452. dica C. Jens. Gauch, H. G. 1982. Multivariate analysis in community ecology. - Cambridge. 298 pp. (3) Lichens Cetraria alvarensis. The nomenclatural status of this Grolle, R. 1983 . Hepatics of Europe including the species depends on whether or not it is taken to include Azores; an annotated list of species, with synonyms ·Cetraria juniperinus var. terrestris. from the recent literature. - J. Bryol. 12: 403-459. Hill, M. 1979a. DECORANA-A FORTRAN pro­ 0. Cetraria islandica. Includes Cetraria ericetorum. gram for detrended correspondance analysis and reciprocal averaging. - Cornell University, lthaca. Cladonia fo /iacea. Includes Cladonia convoluta. N.Y. - 1979b. TWINSPAN-A FORTRAN program for ar­ C/adonia fu rcata. Includes two subspecies; ssp. fu rcata ranging multivariate data in an ordered two-way and ssp. subrangiformis. table by classification of the individuals and at­ tributes. - Cornell University, lthaca. N.Y. Hill, M. & Gauch, H. G. 1980. Detrended corre­ Cladonia rangiformis is included under C. fu rcata since 0. the two taxa were not separated during sampling. spondance analysis: an improved ordination tech­ nique. - Vegetatio 42: 47-58. Cladonia pyxidata. All Cladonia species with cup­ Hulten, E. 1971. Atlas over vaxternas utbredning i shaped podetia and brown apothecia have been included Norden. - Stockholm. here. Chemical analyses were not possible and thus pre­ Hulten, E. & Fries, M. 1986. Atlas of North European Vascular Plants, - Konigstein. liminary identifications could not be confirmed. 1-111. Iversen, J. 1973. The development of Denmark's nature Coe/ocaulon aculeatum. Includes C. muricatum. since the last glacial. - Danm. geol. Unders. V7-C. 126 pp. Jalas, J. & Suominen, J. 1972-1986. Atlas Florae Europaeae, 1-7. -Helsinki. Karlsson, T. 1986. The evolutionary situation of References Euphrasia in Sweden. - Symb . bot. upsal. 27: 61-71. Albertson, N. 1950. Das grosse siidliche Alvar der Insel Krahulec, F., Rosen, E. & van der Maarel, E. 1986. Pre­ bland. Eine pflanzensociologische Ubersicht. - liminary classification and ecology of dry grassland Svensk bot. Tidskr. 44: 269-331. communities on blands Stora Alvar (Sweden). Andersson, S. 1988. Limiting factors on seed production Nord. J. Bot. 6: 797-809.

Acta phytogeographica suecica 76 46 Bengtsson, Prentice, Rosen, Moberg & Sj ogren

Konigsson, L. K. 1968. The Holocene history of the vegetation in Laubwaldern der Insel bland Great Alvar of bland. - Acta phytogeogr. suec. 55: (Schweden). - Acta phytogeogr. suec. 48: 1-184. 1-172. Soule, M. E. 1973. The epistasis cycle: a theory of 0kland, R. H. 1986. Rescaling of ecological gradients. marginal populations. - A. Rev. Ecol. Syst. 4: Ill. The effect of scale on niche breadth measure­ 165-187. ments. -Nordic. J. Bot. 6: 671 -677. Sterner, R. 1922. The continental element in the flora of Parsons, P. A. 1983. The evolutionary biology of col­ South Sweden. - Geogr. Annlr. 4: 221-444. onizing species. -Cambridge. - 1925. Einige Notizen iiber die Vegetation der Insel Prentice, H. C. 1976. A study in endemism: Silene bland. - Svensk bot. Tidskr. 19: 303-322. diclinis. - Bioi. Conserv. 10: 15-29. - 1938. Flora der Insel bland. - Acta phytogeogr. Prentice, H. C. & White, R. J. 1988. Variability, suec. 9: 1-169. population size and isolation: the structuring of Tutin, T. G., Heywood, V. H., Burges, N. A., Valen­ diversity in bland Gypsophila fastigiata. - Oecol. tine, D. H., Waiters, S. M. & Webb, D. A. 1964- PI. (in press). 1980. -Flora Europaea, 1-5. -Cambridge. Rejmanek, M. & Rosen, E. 1988. The effects of coloniz­ van der Maarel, E. 1988. Species diversity in plant com­ ing shrubs (Juniperus communis and Potentilla munities in relation to structure and dynamics. - fruticosa) on species richness in the grasslands of Vegetational Structure. Dordrecht. Stora Alvaret, bland (Sweden). - Acta phytogeogr. Van Valen, L. 1965. Morphological variation and width suec. 76. of ecological niche. - Am. Nat. 99: 377-390. Rosen, E. 1982. Vegetation development and sheep graz­ White, J. A. & Glenn-Lewin, D. C. 1984. Regional and ing in limestone grasslands of south bland. - Acta local variation in tallgrass prairie remnants of Iowa phytogeogr. suec. 72: 1-104. and eastern Nebraska. - Vegetatio 57: 65-78. Rosen, E. & Sjogren, E. 1988. Plant cover in alvar Widen, B. 1980. Flowering strategies in the Helian­ junipers on bland. Distribution features correlated themum oelandicum (Cistaceae) complex on bland, to shrub size and shape. - Acta phytogeogr. suec. Sweden. - Bot. Notiser 133: 99-115. 76. - 1986. Biosystematics in the Helianthemum oelan­ Santesson, R. 1984. The lichens of Sweden and Norway. dicum complex on bland. - Symb. bot. upsal. -Stockholm. 333 pp. 27(2): 53-60. Sjogren, E. 1964. Epilitische und epigaische Moos-

Acta phytogeographica suecica 76 Calcicolous lichens and their ecological preferences on the Great Alvar of bland Lars Froberg

Abstract Froberg, L., 1988. Calcicolous lichens and their ecological preferences on the Great Alvar of bland. -Acta phytogeogr. suec. Uppsala. ISBN 91-7210-076-1. 76,

A floristic study of the lichen flora on calcareous rocks is carried out, including taxonomic elucidations and observation of habitat selection. The biotic and abiotic properties of the main habitats are described. Taxonomic problems are presented in the genera Aspicilia, Lecanora, Caloplaca, Protoblastenia and Verrucaria.

Lars Froberg, Dept. of Systematic Botany, University of Lund, Ostra Vallgatan 18, 223 61 Lund, Sweden.

Introduction few species thrive here, but lichens with The aim of my work is to make a list of the lichens cyanobacteria as photobionts, and also free-living occurring on limestone on the Great Alvar, de­ cyanobacteria dominate, probably due to their scribe their habitats and elucidate their relations to ability to cope with the extreme temperature fluc­ other species. Hitherto about 90 species have been tuations. Genera of cyanobacteria such as found, most of them crustaceous (including several Gloeocapsa, Aphanocapsa and Gloeothece give endolithic ones). Approximately 120 species have the rock-surface its characteristic dark colour. been reported growing on calcareous rocks on Typical lichens here are members of the genus Oland, excluding vertical surfaces (Santesson Col/ema with Nostoc as photobiont, and a 1984). Most records are from the last century, and foliaceous, as wet gelatinized thallus. Collema this work therefore will become the first modern tuniforme and C. multipartitum dominate, occu­ survey of an ecological group of species which has pying the free rock-surface, while C. cristatum has so far been neglected in Scandinavia. Although the a wider amplitude, also occurring on mosses and area is rather homogeneous without larger eleva­ gravel (cf. Degelius 1954). C. polycarpon, which is tions, several different habitats occur. They are less frequent, sometimes occurs in the same roughly divided into limestone pavements, gravel, habitat, but is also found on stone walls. Thyrea stone walls (including scattered rocks), and karst pulvinata, although superficially resembling Col­ areas, the richest and most varied habitat. lema, belongs to the family Lichinaceae which has other types of cyanobacteria as photobionts. It oc­ curs on more inundated areas than the Collema species, often together with Nostoc commune. Synalissa sy mphorea, which belongs to the same Description of the habitats family, is quite different in habit, consisting of Limestone pavement small branched tufts. Sometimes it occurs directly This habitat varies a great deal as to season and on the rock, but usually it grows epilichenically on weather, being frequently inundated during spring Psora lurida. Placynthium nigrum, another lichen and autumn, but otherwise usually dry. The with cyanobacteria as photobionts, has a temperature also varies between extreme values, crustaceous thallus. It consists of tiny lobules, due to the dark colour of the surface. Relatively which are connected into areolae. This lichen has

Acta phytogeograp hica suecica 76 48 Lars Froberg

Fig. Limestone pavement near Mockelmossen with Collema spp. and other cyanophilous lichens. The light patches 1. are exposed bedrocks earlier covered by moss-cushions.

a special growth system. It is delimited by a because of rainfall, freezing and variation in hypothallus consisting of fungal hyphae only, and temperature. The pebbles vary in dimensions be­ the lobules from adjacent parts of the thallus fall tween 0.5 and 2 cm, and about 50 07o of them are off and if they land on the hypothallus the photo­ colonized by lichens. Verrucaria nigrescens biont subsequently integrates with the hyphae here (Hensen & Jahns 1974). The species mentioned above are all typical of the Placynthium nigrum association (Haw ksworth et al . 1977, Wirth 1980) (Fig. 1). Among lichens with green algae as photobionts Verrucaria nigrescens occurs frequently, but the thalli are in very poor condition and usually over­ grown by other species. Aspicilia calcarea also oc­ curs, but only on slightly elevated patches which are less inundated (cf. Degelius 1954). Psora lurida, and the pyrenocarpous Ve rrucaria com­ pacta which are quite similar to each other, are also found on the limestone pavements.

Fig. 2. Area with gravel from Gosslunda. The dark­ Gravel coloured Ve rrucaria nigrescens dominates. Aspicilia This is an unstable habitat, with the grains moving calcarea grows only on larger stones.

Acta phytogeographica suecica 76 Calcicolous lichens on the Great Alvar of 0/and 49

Fig. 3. Karst-area with weathered rocks, north of Gosslunda. Aspicilia calcarea grows on those edges which are not too severely weathered.

dominates (Fig. 2), and other species occurring are cause it never develops apothecia before reaching Aspicilia contorta, Lecidea metzleri, Ca/oplaca a dimension of at least 5-10 cm . The pebbles /actea and Verrucaria muralis. Aspicilia ca/carea, never contain more than one individual, and are however, never occurs in this habitat, probably be- sometimes completely enveloped by it.

Karst areas The karst is a very variable habitat, consisting of limestone pavements intersected by up to 10 cm wide cracks, several elevated and more or less weathered rocks, and more or less weathered escarpments (Fig. 3). Juniperus communis, Cory­ lus avellana and other shrubs, mainly growing in the cracks, protect some parts of the karst from wind and to a lesser extent from sunshine, also producing damp niches. The pavements often extend with their typical vegetation to the edge of the cracks, usually with Aspicilia calcarea also occurring here. However, if the crack is weathered, a characteristic plant com­ munity dominated by Lecidea immersa is devel­ Fig. 4. Weathered crack at the Ekelunda karst. On both sides a typical lichen-community, dominated by Lecidea oped in the area around the crack (Fig. 4). Other immersa, has developed. typical species in this habitat are Collemaparvum,

Acta phytogeographica suecica 76 50 Lars Froberg lo naspis melanocarpa, Caloplaca chalybaea, Pro­ the upper side of stone walls, or on the top surface toblastenia incrustans and Thelidium decipiens. of scattered rocks. These species are otherwise Most of these species are endolithic, i.e. their often not calcicolous, but silicolous such as thallus penetrates the rock, and their ascocarps are Physcia caesia, Lecanora atra and L. muralis; cor­ also immersed. Aspicilia calcarea and Verrucaria ticolous such as Physcia adscendens; or more or nigrescens are also found, but they do not seem to less independent of the substrate such as Xanthoria thrive because of the weathering. The development parietina. Calcicolous species favoured by the of this habitat is probably also dependent on the manuring are Caloplaca citrina, C. flavovirescens fact that strips of snow, during the winter, only and Candelariella aurella. They are all typical for cover these broad cracks (Sjogren in lit.). Just at the Xanthoria parietina-Physcia caesia association the edge of the crack and extending a few cm (Hawksworth et al. 1977, Rodenborg 1977). Xan­ downwards, Protoblastenia calva, Lecidea thoria parietina, Lecanora muralis and Physcia hypocrita and Verrucaria dufourii are found fre­ adscendens, when growing old, often grow up­ quently. Deeper in the crack the lichen vegetation wards in the centre and fragments fall off, making decreases, but at a depth of about 5 dm Petractis a recycling of the community possible (cf. Roden­ clausa was once found in the Ek 1\mda karst. This borg 1977). species thrives in dark and damp habitats, as do Rocks from stone walls not manured by birds other species in the family Gyalectaceae. contain species such as Aspicilia calcarea, A. hoff ­ Weathered rocks and escarpments provide living mannii auct., Lecanora dispersa var. verrucosa, conditions for many species, and this is probably Lecidella stigmatea, Caloplaca variabilis, Ver­ the richest habitat in the investigation. Although rucaria nigrescens, V. fuscella s. l. and V. caerulea. rock fragments constantly fall off, the newly ex­ Since Aspicilia calcarea is a very strong competitor posed surfaces are quickly recolonized. Among it dominates the habitat at a later stage of succes­ others Squamarina cartilaginea, Lecania erysibe, sion, and finally often covers the surface com­ Acarospora glaucocarpa, Buellia epipolia, Calo­ pletely (cf. Rodenborg 1977). placa chalybeia, Verrucaria calciseda and V. bal­ densis, are found here. Also some lichen-parasites occur, such as Opegrapha rupestris growing on Verrucaria calciseda, and Polyblastia discrepans Some problematic lichen groups growing on Protoblastenia incrustans. At the Ekelunda karst two springs are found. Aspicilia The habitat here is thus damp and dark, and con­ The variable species A. contorta and A. hoff man­ tains for instance Gyalecta jenensis and Acrocor­ nii auct., which are quite abundant on the Alvar, dia conoidea, which thrive under these conditions. belong to the widespread A. calcarea group The former species, related to Petractis clausa, (Ozenda & Clauzade 1970). They have usually been consists of cream-coloured apothecia and endo­ regarded as two species, but Clauzade & Roux lithic thallus. Acrocordia conoidea is a pyrenocarp (1985) combine them without even separating them with clearly elevated perithecia. Both species have infraspecifically. Typical A. contorta has a white the orange-coloured genus Trentepohlia as photo­ thallus, as young divided into islands. The areolae biont. They also occur together in other protected, are rounded and separated by narrow fissures, and damp habitats, such as the underside of weathered the mature apothecia are immersed and small in rocks. relation to the size of the areola. Typical A. hoff ­ mannii auct. has a grey or brownish-grey, continu­ Stone walls and scattered calcareous rocks ous thallus. The areolae are sharp-angled and This habitat is characterized by its elevated posi­ separated by broad fissures, and the mature tion and is strongly influenced by bird-manuring. apothecia are elevated, almost covering the whole The birds choose their places to perch, the or­ areola. Many intermediates occur, and they nithocoprophilous lichens thus having a patchy possess intermediate characters as well as charac­ distribution (cf. Rodenborg 1977). They occur on ters typical for A. contorta or A. hoffmannii auct.

Acta phytogeographica suecica 76 Calcicolous lichens on the Great Alvar of 0/and 51

mingled in different ways. This strongly suggests (Arup, in preparation). However, the identifica­ that the variation is caused by hybridization and tion of some of the material, especially type­ subsequent introgression between the two taxa material, is difficult because of damage by snail­ (Ekman & Froberg 1987). Furthermore, A. con­ eating. torta is a strong competitor, often growing Protoblastenia epilichenically as young. A. hojj mannii auct., on This genus is represented on the Alvar by P. the other hand, is competitively weak, and grows rupestris, P. calva and P. incrustans. They have only on patches free of other lichens. usually been treated as three species, but Duncan Lecanora (1970) regards the first two of them as subspecies. On the Alvar this genus is mainly represented by L. P. rupestris has an epilithic, areolated and light­ albescens, L. crenulata and L. dispersa, belonging grey or brownish-grey thallus. The apothecia, to a critical group which should be revised. They which lack a thallus-rim in this genus, are light­ are quite abundant on mortar (Santesson 1984, orange, flattened, and often confluent with each Wirth 1980), but on the Alvar they are confined to other, making their shape irregular. P. calva has limestone. It seems that the species have been quite an endolithic or epilithic and granular thallus. The misinterpreted by many authors. L. crenulata is apothecia are dark-orange to almost red, more or characterized by sparsely located, circular less hemispherical, and usually covered by small, apothecia, which are small and have a blackish red particles. They are often surrounded by a disc, and a distinctly crenulated rim. L. dispersa shallow furrow. P. incrustans, finally, has an en­ also has the apothecia sparsely located and cir­ dolithic thallus, and light-orange, up to 0.5 mm cular, but they are larger and have a lighter disc large apothecia, which are immersed in the rock. (light to dark-brown), and a thick, usually entire P. rupestris and P. calva both have elevated rim. L. albescens usually has crowded apothecia apothecia which are usually larger than 0.5 mm. with a non-circular shape. The rim is thinner than Intermediates frequently occur, for instance P. in L. dispersa and not crenulated. They all have an incrustans-like specimens with epilithic, white endolithic thallus, and many intermediates occur thallus, and P. calva-like specimens with small, between them. However, on stone walls another flattened apothecia with a lighter colour. There taxon is found, which is quite distinct. It is seems to be little variation in secondary characterized by an epilithic, white thallus con­ metabolites, and the specimens examined mainly fined to small patches, and yellow-brown apo­ contain parietin. Individuals of different taxa are thecia immersed in the thallus, without any ele­ often found growing beside each other, suggesting vated rim. It has often been regarded as L. that phenetic variation is small. Perhaps the in­ albescens (Hoffm.) Brant. & Rostr., but is iden­ terspecific variation within the group could be ex­ tical with L. dispersa var. verrucosa (Leight.) plained by the occurrence of genetic exchange, but Laund., which occurs in Great Britain (Duncan further studies are required to elucidate the rela­ 1970). tionships of these species. Protob/astenia rupestris has a fairly wide Caloplaca ecological amplitude, occurring on stone walls, in Another taxonomic problem arises with the karst-areas, on limestone pavements, and on Caloplaca velana group. Its taxa are distributed gravel. It also grows in damp and shady habitats, throughout Europe and vary considerably and is there sometimes found sterile, producing (Clauzade Roux 1985). On bland, two & soralia instead P. calva and P. incrustans are homogeneous taxa are recognized. One of them usually found in karst-areas, mainly at the edges of has an unusual type of spores only known in a few the cracks, and P. calva also occurs growing on other species of Caloplaca, and will be described as stone walls. C. glomerata. The other taxon, earlier known as C. velana Mass., seems identical with the Mediter­ Verrucaria ranean species C. dolomiticola Hue, while true C. This pyrenocarpous genus is quite common on the velana is found on the island of Gotland instead Alvar, and consists of many extremely variable

Acta phytogeographica suecica 76 52 Lars Fr oberg taxa. The most abundant species, V. nigrescens, has an epilithic, areolated thallus which is dark­ brown or almost black. It can sometimes be con­ fused with V. macrostoma s. 1., but is clearly dis­ tinguished by having a dark paraplechtenchymatic hypothallus developed in the lower parts of the thallus. The photobionts are gathered into islands in the upper parts of the thallus. Verrucaria fu scella s. 1. also possesses a hypo­ thallus, which in this group extends at the sides of the areolae, and also penetrates the medulla, reaching the upper surface. The areolae, which have an ash-grey or brownish-grey colour, are thus Fig. 5. Ve rrucaria baldensis. The perithecia are im­ delimited and crossed by black lines from the mersed in the rock, and the thallus is endolithic and hypothallus. The species usually grows epilicheni­ chalky-white. cally on V. nigrescens. On Oland, typical V. fuscella is characterized by thick and large areolae, which contain several perithecia. These are small, Acknowledgement. I am greatly indebted to Ingvar lacking involucrellum, and they have a light wall Karnefelt, who has given valuable suggestions to the ( = the excipulum). The perithecia are thus visible manuscript. The work was supported by Craafordska on the areola surface only as small dark dots. Stiftelsen and Binnings Fond. Quite few specimens deviate in having smaller and thinner areolae, containing only 1-3 perithecia. They have a well-developed involucrellum, sur­ rounding the larger and dark-walled perithecia, References which are visible on the areola surface as clear, black patches. The whole group is widespread in Clauzade, G. & Roux, C. 1985. Likenoj de Okcidenta Europo. - Royan. 895 pp. Europe, and taxonomically and nomenclatorically Degelius, G. 1954. The lichen genus Collema in Europe. complex. - Symb. bot. ups. 13(2): 1-499. V. calciseda and V. baldensis, which are quite Duncan, U. K. 1970. Introduction to British Lichens. ­ similar to each other, have an endolithic, chalky­ Arborath. 366 pp. white thallus and immersed perithecia. V. balden­ Ekman, S� & Froberg, L. 1987. Taxonomical problems in Aspicilia contorta and A. hoffmannii-an effect sis 5), (Fig. however, can be distinguished by the of hybridization? - Int. J. Mycol. Lichen., in press. more densely located perithecia, most of them hav­ Hensen, A. & Jahns, H. M. 1974. Lichens. Eine Ein­ ing 4-5 fissures around their ostioles. In transec­ fiihrung in die Flechtenkunde. - Stuttgart. 467 pp. tion the perithecia are quite different in being fig­ James, P. W., Hawksworth, D. L. & Rose, F. 1977. shaped and on the top covered by a lid-shaped in­ Lichen communities in the British Isles. - Lichen ecology. London. pp. 295-413. volucrellum. V. calciseda has rounded perithecia Ozenda, P. & Clauzade, G. 1970. Les lichens, etude without involucrellum. V. baldensis belongs to the biologique et flore illustree. - Paris. 801 pp. critical Verrucaria sp hinctrina group, Rodenborg, L. 1977. Epilitische Vegetation in einem characterized by the features mentioned above. alten Weidegebiet auf Mittel-Oland, Schweden. - Probably the material from Oland can be divided Bibliotheca Lichenologica 8: 1-108. Santesson, R. 1984. The lichens of Sweden and Norway. into two or more taxa, but in order to elucidate -Stockholm. 333 pp. their relationships transection slides of high quality Wirth, V. 1980. Flechtenflora. - Uni-Taschenbiicher must be produced. 1062: 1-552.

Acta phytogeographica suecica 76 Floristic diversity and guild structure in the grasslands of bland's Stora Alvar Eddy van der Maarel

Abstract van der Maarel, E., 1988. Floristic diversity and guild structure in the grasslands of Oland's Stora Alvar. -Acta phytogeogr. suec. ISBN 91-7210-076- 1. 76.

The plant species occurring in more or less open and dry habitats on Oland's Stora Alvar are enumerated and subjected to spectrum analysis regarding syntaxonomy, chorology, life-form, growth form and strategy type. Three levels are distinguished. Stora Alvar species at large: 388; species occurring more or less frequently in the main grassland association on glaciofluvial deposits re-worked by waves, the Veronica spicata - Avenula pratensis associa­ tion, referred to as Avenetum by earlier authors: 227; and core species occurring exclusively in the Avenetum or more frequently there: 103 species. The more particular chorological groups, the East-European Continental species and the endemics, concentrate in open grassland associations bordering the Avenetum and to a lesser extent in the Avenetum itself. The life-form spectrum is near to average for Central Europe with a higher percentage, 21 against 18, of therophytes. The predominating strategy types are the stress-tolerant ruderals, the intermediate "CSR" strategists, and especially the core species. Life-form and strategy are clearly related: short-lived hemicryptophytes mainly fall into two strategy categories, the related SR and CSR ones; the longer-lived into three: CSR, S and CS; the geophytes have most of their representatives in the CSR and S types, the chamaephytes in the S, CSR and CS types. The guild concept and its use in plant ecology are discussed. The combinations of life-form and strategy type can be taken as a basis for a guild system which can be further differentiated according to growth form. The number of guilds obtained in this way is very high relative to the number of alvar grassland species. This can be interpreted in two contrasting ways: either the guild concept does not work for plant species, or the alvar grassland is a very subtle complex community with a high level of differentiation regarding spatial and temporal resource utilization and adaptation and a low level of competitive interaction.

Key-words: Avenetum, Chorological spectrum, Distribution range, Diversity, Epharmony, Growth form, Guild, Life-form, Strategy type, Syntaxonomical spectrum, Veronica spicata - Avenula pratensis association.

Eddy van der Maarel, Institute of Ecological Botany, Upp sala Un iversity, Box 559, 751 22 Uppsa/a, Sweden.

Introduction (Krahulec et al . 1986, Bengtsson et al. 1988; for cryptogams, see also Albertson 1950). Countings Alvar plant communities, especially the grasslands on local alvar sites gave values of 60-80 species on on deeper soils, are rich in species and contain a 100 m2, and a preliminary species list for typical number of geographically interesting taxa both on alvar grassland sites counted c. 150 taxa. These the level of species and on the lower levels of grasslands occur extensively and well-developed on subspecies and variety. (In the following text the the big limestone plateau of South Gland, called term species will be used as a general term although Stora Alvar, a huge almost uninterrupted open flat formally we should speak of taxa here.) Phyto­ landscape of c. 250 km2• (See Rosen 1982 for a re­ sociological releves made since 1982 showed cent and integrated description of the area.) The numbers of phanerogamic species up to 40 per present study will deal with this maj or area of alvar sq.m and up to 30 per 0.25 sq.m, with almost and not take into account many smaller pieces of equally high figures for mosses and lichens alvar further north on the island.

Acta phytogeographica suecica 76 54 Eddy van der Maarel

Plans were made in 1983 to start experimental be included as well, as peripheral species. Habitat research on the maintenance of such high species and community types to which such transitions oc­ numbers on small areas. These plans later became cur include rock and karst vegetation on the open merged with a broad research scheme proposed by alvar, alvar depressions with moist to wet grass­ R. K. Peet. The resulting project includes the lands and dwarf scrub, alvar woodland and heavily yearly analysis of species density on series of grazed alvar, usually potentially Avenetum. One nested plots varying from 10 sq.cm to 0.25 sq.m, further transition, to coastal grassland, has been laid down in transects of 1 2.5 m. Three sites neglected because there is little left of original alvar x are involved, which vary in soil depth and grazing vegetation bordering the sea. intensity. A series of fertilization experiments is The total list of phanerogamic taxa considered carried out on each site and gap experiments have typical, transitional or non-typical alvar species on been started (see Rusch 1988 for the latter aspect). Olands Stora Alvar includes 388 taxa. Naturally, All sites are characterized by the newly described this list is not fixed. Species could be deleted or Veronica sp ica fa - A venula pratensis association added according to the arbitrarily chosen limits, on a 1-5 dm deep slightly acid to neutral brown but this would not matter much for the statistics soil type in re-worked glaciofluvial deposits resting undertaken here. upon Ordovician limestone (Krahulec et al . 1986). One especially interesting aspect of species diver­ This vegetation type clearly belongs to the syntax­ sity is that, with species density on the community onomical order Brometalia erecti, which includes level already rather high, the total number of alvar dry grasslands, mainly on limestone over most of grassland species is still much higher. The question West, Central and Eastern Europe. This order is arises to which extent the local number of species related to the East-European-Siberian steppe could be increased in theory, for instance by order Festucetalia valesiacae, with which it forms creating more spatial and temporal differentiation the class Festuco-Brometea. The Veronico­ and by increasing the accessibility, i.e. promoting Avenetum has some links with this steppe order, species dispersal to local alvar grassland sites. One which is expressed in the choice of the steppe other question, the one to be elaborated here, con­ species Veronica sp icata as one of the character cerns the similarities and dissimilarities between species appearing in the associations name. It the species involved regarding immigration shows internal differentiation, as recognized by history, habitat specialization and resource utiliza­ Krahulec et al. (1986), who described two subasso­ tion. ciations, one with Galium boreale on deeper soils which do not dry up easily during summer, and one with Sedum reflexum on shallower soil. It is also spatially intermingled (notably the Sedum Definition and background of the guild subassociation) with open grasslands on shallow concept limestone soil, viz. the Gypsophila fastigiata - Globularia vulgaris and He/ianthemum oelan­ The guild concept has been developed in animal dicum - Galium oelandicum associations (Krahu­ ecology for groups of functionally similar species lec et al. 1986). These latter associations have been (Root 1967). Giller (1984) took the definition by preliminarily assigned to a new alliance Helian­ Miller (1980) as a starting point: a guild is an themo-Cetrarion, probably to be included in the assemblage of species utilizing a particular re­ order Alysso-Sedetalia (in the sense of Moravec source or group of resources in a functionally simi­ 1967), and are also related to steppe vegetation. lar manner. According to Pianka (1983), different The Avenetum grasslands will be the prime ob­ guild types can be recognized within one com­ ject of this study. The core species list to be treated munity, each of them based on one such particular will consist of species occurring exclusively or fre­ resource, and one and the same species can be a quently in the A venetum. In addition, these grass­ member of different guilds. Most animal ecologists lands show transitions in various directions and use the concept in a rather loose way (examples in species which overlap in any of these directions will Ecological communities 1984), often for small

Acta phytogeographica suecica 76 Floristic diversity and guild structure in the grass/ands 55 communities of taxonomically related animals vironmental preference as reflected in syntax­ such as birds, lizards, spiders and snails (tax­ onomical position and indicator values for essen­ ocenoses sensu van der Maarel 1965, Barkman tial factors and geographical distribution. A new 1978) using largely the same resources within a element can be derived from Grime's (1977, 1979) given community and its habitat. Essential in the theory on types of strategy towards stress and dis­ concept is that species within one guild interact turbance. All these elements express general much more intensively, mainly by competition, features of plant species adaptation to the environ­ than species from different guilds. ment on the level of the habitat. They may thus be For plant species this would mean that species used to define guilds and to delimit guilds towards within one guild share in any case the same local each other. In this study the relations between the habitat and will usually be further differentiated elements as represented in the alvar flora will be on the basis of adaptations to special outstanding explored in order to prepare a possible guild factors operating in a spatially varying way within system in which most of the alvar species can be the habitat, for instance moisture or grazing. In­ placed. deed, we see adaptation as a key feature and in fact The following elements have been considered the guild concept is historically linked with the and data on them for all species involved botanical life-form concept of Raunkiaer, and still systematically collected or estimated from the lit­ further back the epharmony concept of Vesque erature and field observations. from 1882 as introduced in plant ecology by Family Warming. With Vesque's words, epharmony is the 1. The traditional family concept, as for instance state of the adapted plant (see van der Maarel 1980 used in the Floras of Oberdorfer (1979) and Krok for an elaboration of these links and references). Almquist (1984) is followed here. Another relevant link exists with Grime's strategy & concept. Species with the same strategy type, i.e. Habitat 2. the same adaptation to prevailing stress and dis­ Only a few major habitat types are distinguished turbance factors, form a guild. Because plants are here in addition to that of the Avenetum grassland not mobile and usually restricted to a relatively type, G. The taxa mentioned for other habitat small volume of pedosphere and atmosphere it types may be found very rarely in the alvar would not be very realistic to consider different grassland proper, but only in transitional situa­ functional guilds within the same small volume of tions. A large number of taxa occur both in the potential interaction space. Rather would we con­ alvar grasslands and in one or more of the ceive integrated guilds for plant species in which neighbouring habitat types. These taxa are in­ various strategies of plants to cope with major en­ dicated with a combined habitat code including the vironmental factors are combined. letter G. If such species are more frequent in the The significance of the guild concept is that it Avenetum than in any of the other habitat types may help us to better understand how coexistence the indication will be GG. If they are about equally mechanisms function: plant populations belonging frequent in a neighbouring habitat the G will be to different guilds will not necessarily be in inter­ combined with the other habitat code. Species oc­ action because they can avoid interaction by ex­ curring almost entirely in a neighbouring habitat ploiting different resources or adapting differently will be indicated with a double-letter code for the to limiting (stress or disturbance) factors. habitat. For species of neighbouring habitats which occur regularly but not frequently in the Avenetum as well a combined code is used. A total of 388 taxa is recognized for the alvar grassland Elements for a guild system complex, of which 227, or nearly 60 OJo are con­ sidered more or less typical alvar grassland flora, Main elements for a guild system, as far as they i.e. appearing with a G code in the list. The latter can be derived from generally available sources, species are listed in Appendix 1. Data on the re­ may include life-form, growth form, general en- maining species are available on request.

Acta phytogeographica suecica 76 56 Eddy van der Maarel

G Closed alvar grasslands on shallow and ruderal, agricultural and woodland sites a related deeper soils in littoral deposits. well-represented syntaxon was chosen in order to L Alvar limestone habitat, i.e. with thin, reduce the total number of syntaxa to be com­ weathering soils, fissures in the bedrock and pared. The position of endemic taxa and other locally karst phenomena. Includes the two typical alvar species not treated in the above­ other associations mentioned above and the mentioned sources was judged according to fourth association described by Krahulec et Krahulec et al . (1986), Bengtsson et al. (1988) al. (1986), the Crepis pumilum -Allium and/or own phytosociological observations. In alvarense association. order to obtain more homogeneity in the local D Depressions on the alvar, occurring in direct groups some species were placed in a syntaxon spatial connection with alvar grasslands, neighbouring the one indicated for the species by where soil moisture is permanently avail­ the Central European sources. This affected the able. Here vegetation types (not yet properly Molinietalia, Tofieldetalia and Nardetalia groups described) with Potentilla fr uticosa, Sesleria to some extent. caerulea ssp. uliginosa and Carex species oc­ cur. Alvar pools, fens and lakes are not in­ Code Sy ntaxon Main habitat cluded. AP Asplenietea rupestris Rocks W Scrub and woodland· developing in alvar CP Chenopodietea Fields grasslands, mainly Ju niperus communis PG Plantaginetea majoris Trodden places, sites with fluctuations in scrub (see Rejmanek Rosen 1988, Rosen & water level & Sjogren 1988). Also Prunus sp inosa, Rosa AV Artemisietea Ruderal sites species and Corylus avellana and a number EP Epilobietea Woodland clearings Sedo-Scleranthetea Sandy and stony thin of xerothermic borderline species such as ss Vincetoxicum hirundinaria, Coronilla soils FS Festuco-Sedetalia Sandy neutral-acid emerus and Silene nutans are important. AS Alysso-Sedetalia Sandy basic-rich in lime Well-developed woodlands occurring over Festuco -Brometea Dry grasslands and larger areas, especially at the northern steppes border of the Stora Alvar, are not included. FE Festucetalia M Man-made or heavily influenced sites such vallesiacae Steppes BR Brometalia erecti Dry grasslands as verges of roads and paths, surroundings Molinio-Arrhenateretea Moist and wet grass- of sheep-barns, and especially cattle drink­ lands ing and milking places. AR Arrhenatheretalia Moist grasslands MO Molinietalia Wet grasslands The following core categories are distinguished: Parvocaricetea Fens and basic mires CN Caricetalia nigrae Neutral and acid fens GG, GL, GW and GM. The limestone habitat in­ TO Tofieldetalia Basic fens cludes the peripheral categories LL, LG, LW and NV Nardetalia (Violion LM ; the depression habitat includes DD and DG; caninae) Heath-grasslands the open scrub and woodland habitat includes WW OR Origanetalia Xerothermic scrub and WG and joins LW with the limestone habitat; borderlines PR Prunetalia Scrub the man-made habitat includes MM and MG and Querco-Fagetea Woodland on rich soil joins LM with L. QF In order to facilitate comparisons syntaxa were 3. Syntaxonomy grouped together for certain calculations into the The position of plant taxa is characteristic or dif­ following main categories: ferential taxa in the syntaxonomical system has been judged on the order and class level, on the UR: CH +PL+AV "Ruderal" and other unstable habitats basis of Ellenberg (1979), Oberdorfer (1979) and XO: SS +FS+AS+FV "Dry open grassland" Westhoff & den Held (1965), in the same way as in XG: BR +NV "Dry closed grassland" Krahulec et al. (1986). For some taxa of deviating VM: AR +MO "Hay meadows"

Acta phytogeographica suecica 76 Floristic diversity and guild structure in the grasslands 57

VF: CN +TO "Fens" a direct interaction factor for other plants with the WE: OR +PR+QF+AP+EP "Dry woodland", incl. same or another growth form. We will use a simple openings, fissures and growth form system, which is derived from a edges similarly simple system of van der Maarel (1966) and the elaborate system of Barkman (1979) in­ Life-form 4. cluding the former one. The total size of plants will Raunkiaer's life-form system has been adopted not be included here but in the next category. with only a few subdivisions and some adapted let­ ter symbols. With Du Rietz (1931), Barkman ea erecta - erect stems predominate (1979) and others we may see life-forms as expres­ ea caespitosa - tussock-building graminoids sions of environmental adaptation, but then ra rosulata - rosettes predominate ta tapeta - mainly low, horizontal extension especially of adaptation to stress. The judgement da diffusa - both horizontal and vertical exten­ on short-livedness of hemicryptophytes is based on sion the literature on grasslands and grassland species ma mini-diffusa - only a few cm high (e.g., Grime 1979) and on ·own observations and comparisons, in part from dune grasslands (e .g., Strategy type van der Maarel 1981). The difference between 6. Grime's system is adopted here, with the informa­ winter and summer therophytes is not as clear as in tion on about 100 grassland plants and some others more Atlantic regions. Some taxa were classified as in Grime Hunt (1975), and Grime (1979) as a therophytes in general because the time of ger­ & basis. The two axes of variation in Grime's scheme minating and flowering may vary. For easiness of are Rmax, the maximum relative growth rate per comparison in some calculations, therophytes, week, and M, the morphology index, rather an in­ chamaephytes and phanerophytes will be taken as dex of size, in which three parameters are com­ groups. bined: the maximum height of the plants canopy, the extent of lateral growth and the amount of lit­ T Therophyte Tm Therophyte flowering spring- ter produced. In view of the clear relations existing autumn with the Ellenberg (1979) indicator values for Ts Therophyte flowering summer- nitrogen and reaction, and regarding dry habitats autumn (serotinal) also with the moisture indication (van der Maarel, Tv Therophyte flowering spring (ver- in prep.), Grime's system could be extended to an­ nal) Hemicryptophyte other 100 species. For the remaining species the H Hb Hemicryptophyte short-lived strategy type was estimated on the basis of life­ Hemicryptophyte longer-lived HI form, estimations of the M- index and the local G Geophyte nitrogen status of the soil. In the following (own) Chamaephyte c definition of strategy types the respective intervals Ch Chamaephyte herb Cf Chamaephyte suffrutescent for Rmax, M, Reaction indication RI and Nitrogen Cc Chamaephyte succulent indication NI are listed. This system is only applied Phanerophyte p to non-woody species occurring in grasslands. The Pn Phanerophyte nano- dwarf shrub woody plants, although partly described by Grime, Ps Phanerophyte meso- shrub are taken separately (symbol W). Moreover, the Pt Phanerophyte macro- tree Pc Phanerophyte climbing liana saprophytes and parasites have been kept separated (symbol HP). 5. Growth fo rm It should be noted that there are gradual transi­ Growth forms are morphological types, which ac­ tions between strategy types, notably between the cording to Barkman (1979) should be an expres­ intermediate CSR type and the neighbouring types sion of the "general architecture of the plant". CS, S and SR. Some species may perhaps better be Still, they can be seen as adaptations, be it to dif­ placed in a neighbouring category. (In fact, some ferent environmental factors. Besides, the occur­ species are mentioned for two different neighbour­ rence of plants with a certain growth-form means ing types at different places in Grime's book.) One

Acta phytogeographica suecica 76 58 Eddy van der Maarel should also remember the criticism by Grubb species (considered submediterranean by Ober­ (1985) on the risks of generalization from separate, dorfer 1979) are of a limited areal extension and maybe entirely different environmental factors to could be considered central-European endemics. the environment as a whole; and question whether Some others of an Atlantic distribution are almost it is realistic to test growth rates for divergent confined to the Baltic and could be considered Baltic endemics. They are indicated with in the species in one general ''favourite'' experimental * environment for a short period of time. And still, respective groups and will be separately treated to­ the purpose of a general, preliminary typology of gether with the Gland and Gland-Gotland island species as desired here is very well served by endemics. Grime's strategy types. - After completion of the manuscript, Prof. J. P. Grime sent a newly revised ABM Arctic and European Boreal-Montane (8, 9, and extended species list with strategy indications 11, 12, 13/17) (ABM*: Central-European to me. This list is to appear in a book ''Com­ endemic) parative plant ecology-a functional approach to EBC Eurasiatic Boreal Circumpolar (28/32) common British species'' by J. P. Grime, J. WES West European Siberian (25/27, 34) ECA East European Central Asian (35/40) Hodgson R. Hunt. It is based on a more detailed & ASA Atlantic Subatlantic (19, 20) (ASA*: Baltic system of strategy types, but is on the whole simi­ endemic) lar to the Gland list regarding species common to END Endemic (END*: also on Gotland) both lists. DIS Disjunct occurrence (see next)

Rmax M RI NI 8. Distribution range boundary Stress tolerators <.8 2-4 <6 <4 The special phytogeographical character of Gland s CS Competitive Stress- includes the situation of the island near to the tolerators <.8 4-5 6-8 3-5 margin of the distribution range of a taxon. This SR Stress-tolerant is indicated as follows: Ruderals .8-1.4 <3 2-8 <4 I Intermediate, "CSR"- a Taxon occurs over larger areas all around Gland strategists .8-1.4 3-4 3-8 2-5 Taxon reaches part of its distribution boundary R Ruderals >1.4 <3 7-8 6-8 b in South Sweden CR Competitive Ruderals >1.4 4-5 >5 >6 c Taxon reaches part of its distribution boundary Competitors > 1.6 >5 >5 >7 c on Gland (or Gland and Gotland) Hemi-parasites, HP * Disjunct occurrence on Gland (can be combined Parasites with a, b or c, usually only with c, always corn- Woody species w bined with END)

Distribution type Frequency of occurrence 7. 9. Gland in general and its alvar in particular are The many species recorded for alvar grassland oc­ known for its phytogeographically outstanding cur with strongly varying frequencies. Most of the position with entirely different distribution ranges taxa listed occur only rarely in the alvar grasslands, represented, and a large number of taxa occurring either because the main distribution is in another with isolated populations, some of which having habitat type, or because it concerns an overall rare received separate taxonomical status (Sterner 1938, taxon. With the following scale some impression is 1986, Rosen 1982, Bengtsson et al. 1988). The fol­ provided on the variation in frequency and abun­ lowing distribution range typology, which is very dance. Category 1 includes peripheral species similar to the one used by Krahulec et al . (1985), which may be considered both rare and not typical. is based on Hulten (1950) and the assignment of It makes up no less than 45 OJo of the total; taxa to the typology on Hulten & Fries (1985). The category 5 represents the overall abundant and numbers added to the names refer to Hulten's dominant species which determine the aspect of (1950) groups. Some European boreal-montane alvar grasslands.

Acta phytogeographica suecica 76 Floristic diversity and guild structure in the grasslands 59

Rare, only in transitional habitats (peripheral Characterization of Stora Alvaret's flora species) Chorological and syntaxonomical spectra 2 Rare The chorological spectrum for the entire flora as 3 Occasional, locally more abundant 4 Frequent delimited above, comprising 388 taxa, is presented 5 Abundant in Table 1 and compared with the spectrum for the 227 grassland taxa and the 103 core taxa. Table 1. Geographical spectrum for StOraAivarets flora at large (SA) , Clearly, the spectrum is largely the same for the the grassland species (G) and the three species lists. The West-European-Siberian grassland core species (GG) . Figures are percentages of the and the European Boreo-Circumpolar species, respective totals. For explanation of abbreviations , see text. thus the species with a very large distribution range, make up the majority. Of the more typical SA G GG species with a narrower range the Continental ones ABM 5 4 5 EBC 13 9 11 (ECA) outnumber the Atlantic-Subatlantic ones, WES 51 51 119 ECA 18 21 1 but the latter element is still considerable. This B ASA 11 11 12 END 3 4 4 relatively high share has been remarked upon by Krahulec et al. (1986), especially for the Galium Species total 388 227 103 boreale subassociation of the Veronico-Avenetum, END s.l. 6 7 DIS 10 9 but it now appears that this holds for the alvar flora as a whole. The percentage of species with endemic or geographically particular status Table 2. Syntaxonomical spectrum for the three Alvar species G and GG. Figures are percentages of the respective 'l'i"St"S'SA , amounts to 16, which is probably higher than in totals. For abbreviations, see text. any other Eurosiberian local flora. SA _G Table 2 presents the syntaxonomical spectrum _ fQ_ UR Ruderal, unstable 16 9 1 for the three species assemblages. From the alvar xo Dry open grassland 21 28 28 Sedo-Scleranthetea 5 6 flora at large to the Avenetum core species the ss 7 FS Festuco-Sedetalia 3 5 2 ruderals and woodland species strongly decrease as AS Alysso-Sedetalia 11 14 17 FE Festucetalia vallesiacae 2 3 2 may be expected, and particularly the species of XG Dry closed grassland 18 30 51 closed grasslands increase their relative import­ BR Brometalia erecti 13 22 39 N V Nardetalia 4 7 13 ance. In Table 3 the joint distribution of geo­ VM Haymeadows 18 20 17 graphical and syntaxonomical categories is shown AR Arrhenatheretalia 11 13 13 for the alvar grassland species at large (core and MO Molinietalia 7 7 4 VF Fens 8 1 0 peripheral), where the East-European continental WE Woodlands 20 11 2 species are best represented. The ruderals are

Species total 388 227 103 largely species with a wide distribution range (BBC WES): 85 OJo against an expected 60 % + Table 3. Joint distribution of alvar grassland species {G) with equal representation of geographical groups over chorological and syntaxonimical categories . An asterix to the left of the figure means that representation of the over syntaxonomical groups. The woodland syntaxonomical category in the chorological one is consider­ ably larger than average, an asterix to the right means species are West-European-Siberian to nearly that the representation of the chorological category in the syntaxonomical one is co nsiderably larger than average . 70 OJo but hardly boreal-circumpolar. The hay­ (These are indications only; significance tests are not meadow species have near to average representa­ considered meaningful for this material.) tion of most geographical distribution types. Re­ UR xo XG VM VF WE Tot . garding the distribution of chorological categories ABM 0 5* 5* 2 0 0 12 EBC * 7* 5 7 6 0 1 26 the most pronounced pattern is presented by the WES 11 23 30* *28 1 *18 111 East-European and endemic/disjunct species, ASA 3 111* 12 8 2 2 41 ECA 0 10* 12* 1 0 5* 28 which concentrate in the open grasslands and to a END 0 * 7* 2 0 0 0 9 ------lesser extent also in the closed grasslands. In­ ------Species total 21 6.4 68 45 26 227 terestingly, the Atlantic-Subatlantic species which END s. l. *12* 0 18 chorologically contrast with the East-European DIS * 1 7* 1 28 ones have a similar optimum distribution. This

Acta phytogeographica suecica 76 60 Eddy van der Maarel confirms in a quantitative way the observation Table 4. Life-form spectra for Table 5. Spectrum of strategy the three alvar species lists types fo r the three alvar SA, and Figures are species lists SA, and made by earlier Oland botanists that Gland's Stora G GG. G GG. percentages of the respective Figures are percentages of the Alvar, and especially the open communities, form totals. For abbreviations see respective totals. For abbrevia­ text. tions see text. a meeting place for Atlantic-Subatlantic and East­

SA SA European species. G GG G GG T 21 21 20 R 3 0 0 Tm 16 16 12 SR 29 30 28 CR 6 6 Life-form and strategy spectra Ts 2 2 5 " 22 27 3!i Tv 3 3 I 4 16 18 21 Table presents the life-form spectra, which shows H 53 53 60 s Hb 18 18 26 CS 14 12 8 a typical Central-European picture. Figures HI 35 35 34 c 2 1 0 2 2 3 (1934) 12 12 10 HP presented by Raunkiaer for Denmark with G w 8 2 c 6 6 9 " Ch 4 4 3 ------1084 species and by Ellenberg (1982) for 1760 ------Cf 1 1 2 Species 388 227 103 vascular species listed in Ellenberg (1979) are near Cc 1 1 4 total p to identical. The only and interesting difference is Pn 1 Ps 1 the higher number of therophytes on the alvar: " Pt 2 0 Pc 0 21 OJo against 18 OJo• This must be seen in the light ------of the vast area of thin soils included in this study, Species where a relatively high number of therophytes is total 388 227 103 found. The spectrum of strategy types (Table 5) shows a preponderance of the ruderal stress-tolerators and the intermediate strategists with values of variation over most of the locally important around 30 OJo each. For the Avenetum core species strategy types, or these strategy types show varia­ also the stress-tolerators are an important tion over the life-form types. Such variation has category. The relative amount of stress-tolerators been mentioned by Grime (1979) for the ruderal and intermediate strategists increases as the species strategists and implied for the CSR strategists (see selection proceeds towards the core species. his Table 9), but not approached more systemati­ Neither ruderals nor competitors are of any signifi­ cally. cance in this environment. This agrees with pic­ Apart from some outlier-positions the following tures shown by Grime (1979, Fig. 20). pattern arises: the short-lived hemicryptophytes Table 6 shows the joint distribution of species mainly fall into two strategy categories, the related over life-form and strategy categories. The SR and CSR ones; the longer-lived into three: coherence between the two sets of categories is CSR, S and CS; the geophytes have most of their considerable. This does not surprise us because the representatives in the CSR and S types, the assignment of species to strategy types is partly chamaephytes in the S, CSR and CS types. based on indirect judgements on the nature of the decisive environmental factors, which are also im­ portant for the distinction between life-form types. Grime (1979, Fig. 18) had already concluded that there is a relationship between strategy and life­ Towards a guild system form, and he indicated the ruderal strategy of an­ nual herbs, and the semi-ruderal strategy of bien­ The combined scheme of life-form and strategy nials. However, the remaining non-woody vascular types for the Avenetum species at large, as plants are not specified and they appear over presented in Table 6 will form the basis of a ten­ almost the entire triangular diagram. This picture tative guild system. All combinations realized in can now be given some more detail. The this table are considered groups, only the therophytes and the suffrutescent and succulent therophytes and the phanerophytes have been chamaephytes are homogeneous as to the con­ taken together. Most of the 25 groups obtained in nected strategy type. On the other hand, the cryp­ this way are represented in the A venetum core tophytes and herbaceous chamaephytes show a species. Within many of such groups a subdivision

Acta phytogeographica suecica 76 Floristic diversity and guild structure in the grasslands 61

Table 6. Distribution of species over life-form Of the 87 guild types recognized for the alvar and strategy categories. Figures in bold are species numbers in species assemblage G, grasslands at large 40 are represented in the normal fi gures are species numbers in species assemblage Avenetum core species. The largest guild within GG. the core species is A03, the guild of Cerastium R SR CR S CS C HP I W semidecandrum , with nine species. The next largest Tm 25 12 ones are E04, the shorter-lived decumbent CSR­ Ts strategic hemicryptophytes and H03, the guild of 2 3 Tv 8 decumbent longer-lived stress-tolerating hemicryp­ 3 Hb tophytes, both with seven, and Y01, the guild of 279 21 25 77 HI 8 carpet-forming stress-tolerating suffrutescent 25 23 22 3 - 74 77 7 chamaephytes, with five members. On the other 8 6 G 43 2 3 2 4 hand, 15 guilds are represented with only one Ch 1 3 4 3 1 7 1 species in the core. Since the definition of the Cc 23 guilds is quite preliminary a further detailed C f 5 discussion of each of them seems premature. The

Pn,s,t, appendix as a whole may serve as a first functional 10 2 survey of alvar phanerogamic plant species which can be used for statistical-ecological purposes.

is realistic, either because of the variation in growth form or in combination with the differen­ tiation between graminoids and herbs. Discussion In this way no less than 67 guild types are distin­ guished. They are listed in Appendix 1 in a se­ The three main criteria used for the characteriza­ quence according to the sequence of life-forms. tion of plant species guilds, life-form, strategy­ Species with their ecological optimum outside the type and growth-form are all of a rather general Avenetum have been given a guild indication ac­ kind. They have not been checked for all species cording to the combination described above, but involved, and they have not been checked at all­ the habitat-indication has been added: L for the except for growth form-at the local alvar plant open limestone habitat, D for depressions, W for populations. This makes the guild typology open woods (shaded habitats) and M for human­ adopted here preliminary, at least as far as the influenced meadows. It remains an open question assignment of species to types is concerned. Also, whether one would consider life-form-strategy other more precisely defined plant features may be combinations in different habitats different guilds more relevant, such as extension of the root altogether or different guilds within one guild type. system, canopy height, leaf-area index and In any case: species with a different habitat indica­ (especially for the summer-dry alvar grasslands) tion do eo-occur only occasionally and if so, they hydrature sensu Iversen (1936). Finally, the apparently show micro-distribution patterns in number of guild types derived in this way may relation to habitat differentiation and do not share seem excessive as compared to animal guild types the same guild according to the guild definition. defined so far. For instance, the three Caryophyllaceae Cerastium Still, the plant performance features involved in semidecandrum, Arenaria leptoclados and the criteria used here are relevant to the central Scleranthus annuus are very small therophytes idea in the guild concept, viz. the utilization of with a SR strategy, but occur typically in different resources. Life-form type indicates how plants sur­ habitats, viz. the Avenetum, the open limestone vive unfavourable conditions, for the alvar both communities and ruderal places respectively. They summer drought and winter cold. In addition, the are thus habitat-differentiated though similar in differentiation into life span involved in the strategy. system, and the differentiation in regeneration ea-

Acta phytogeographica suecica 76 62 Eddy van der Maarel pacity connected to that, are important. The dif­ habitat utilization. This is what apparently hap­ ferent expressions of the two elements in the pens with the longer-lived species in our system. strategy system relative growth rate and morphol­ ii) Non-equilibrium coexistence, i.e. species share ogy index, while overlapping with the life-form the same resources but are shorter-lived and never and growth form systems, indicate more reach equilibrium before the local representatives specifically resource utilization, including major of the species involved have died again. This points nutrients, water and light. The stress adaptation to gap formation and gap regeneration sensu element involved relates to the adaptation to un­ Grubb (1977). This is apparently actual for the favourable conditions. shorter-lived species. Its significance for the local One special aspect of resource utilization con­ alvar system is under investigation (Rusch 1988). cerns the nitrogen-fixation by leguminosae. The iii) Equilibrium coexistence. With reference to capacity of potentially fast-growing Fabaceae of Tilman (1982) we conclude that even under condi­ an "R" strategy has been taken as an additional tions of longer-lasting competitive resource-shar­ guild characteristic. This is realistic for the alvar ing, micro-differences in availability ratios and system as appeared in the relative wet summer of adaptations to exploitation, these may enable 1987 when the Fabaceae Trifolium pratense and T. species to coexist. repens spread explosively in the experimental plots Interestingly, this type of eo-occurrence would treated with fertilizers but not with nitrogen. hardly be found according to a guild approach as Regarding the high number of guilds represented suggested here. And, also if we go along with the in the alvar grassland core species an interesting second alternative, i.e. of many guilds of highly dilemma arises. differentiated resource utilization and adaptation 1) We should reject this particular guild system to disturbance and stress, we conclude that in this for alvar grasslands and, more generally, for simi­ respect plants are entirely different from animals. lar plant communities rich in species and life­ This has interesting links with assumptions about forms, or even abandon the guild concept for plant species-importance, "size-hierarchy" relations, as communities altogether. Our system could of will be discussed elsewhere (van der Maarel, in course, still be maintained, for instance as an ex­ press). tended life-form system. This would be another It would be interesting and necessary to more ex­ way of expressing the fundamental differences be­ actly determine the various parameters introduced tween plants and animals which tend to be here as elements of a guild system, and moreover, underestimated by animal ecologists, but em­ to qualify the various forms of disturbance and phasized by botanists (see, e.g. Grubb 1977). stress operating in the alvar grassland system and 2) We should accept the consequences of the to investigate how plants respond to them. guild differentiation as suggested h,ere and rein­ force the conclusion drawn by Grubb (1977), Grime (1979) and others: Plant species and their local plant populations, at least in species-rich plant communities, can be extremely diversified in their resource utilization and thus also in their Acknowledgements. This study forms part of the joint guild structure. We can relate this to some recent project on Dynamics, Diversity and Coexistence considerations on coexistence, without aiming at mechanisms on (Hands Stora Alvar, together with E. Rosen, Uppsala, R. K. Peet, Chapel Hill NC, USA and any completeness. We start from the notion of eo­ J. H. Willems, Utrecht, NL, and associates supported occurrence, statistically verified jointness of occur­ by NFR, the Swedish Natural Science Research Council rence of plant species on relatively small areas (cf. (grant to E. van der Maarel) and by SNV, the Swedish National Environment Protection Board (grant to E. Noy-Meir & van der Maarel 1987). Braakhekke (1980) distinguished between three types of eo­ Rosen). I thank Marijke van der Maarel-Versluys for joint excursions and assistance in drafting a first check occurrence of plant species: i) Equilibrium non­ list of alvar species, Dr Ejvind Rosen and Dr Erik Sjo­ coexistence, i.e. micro-habitat differentiation, gren for comments on this draft, especially on the alvar both spatial and temporal, or differentiated micro- species list.

Acta phytogeographica suecica 76 Floristic diversity and guild structure in the grasslands 63

APPENDIX. List of taxa occurring on Olands Stora Alvar .

li11 � Ea l::lil. � u lil: S1 Ill !&Er.li11 � !&Er. A R E02 Centaurea jacea Ast AR Hb ea WES 66 AO I M Poa annua* Poa MG PG Tm da R EBC E02 Knautla arvensls Dip 66 AR Hb ea WES A02 Bromus hordeaceus* Poa Gl FS Tm ma SR ASA 4 EOJ Brlza media* Poa GG BR Hb da WES 5 AOJ Arenarla serpyll1folla Car GG BR Tm ma SR EBC EOJ luzuia multi flora Jun 66 NV Hb da WES J 3 AOJ Erodlum clcutarlum Ger GG FS Tm ma SR WES EOJ Anthoxanthum odoratum Poa MO Hb da WES GM 5 AOJ Medlcago lupullna Fab Gl AR Tm ma SR WES 4 EOJ Cynosurus crlstatus Poa GM AR Hb da WES AOJ Trifolium arvense Fab GG SS Tm da SR WES 2 EOJ Luzula campestris* Jun GG NV Hb da ASA 5 AOJ Trifolium dublum Fab GM AR Tm ma SR ASA 5 EOJD Cardamlne pratensls* Bra DG MO Hb ea EBC 2 AOl Trifolium striatum Fab GG FS Tm ma SR ASA 3 EOJD Succlsa pratensls Dip DG MO Hb ea WES AOJ Vlcla tetrasperma Fab GG FS Tm da SR WES l EOll Plmplnella sax1fraga* Ros L6 BR Hb ea WES AOJ Cerastlum semldecandrum Car GG FS Tm da SR ASA 5 EOll Prunella vulgaris* Lam LG AR Hb da WES 4 Fab GG FS Tm ma SR WES a 4 Lotus cornlculatus* Fab GG AR Hb da WES AOJ Trifolium campestre E04 5 AOll Arenarla leptoclados Car LG FS Tm ma SR WES b 4 E04 Polygala vulgaris Pog GG NV Hb da ASA AOll Chaenorrhlnum minus* Scr LG AS Tm ma SR WES l E04 Anthyllls vulnerarla* Fab GG BR Hb da WES AOJL Hornungla petraea Bra LG AS Tm ma SR ASA 4 E04 Asperula ttnctorla Rub GG BR Hb da ECA 5 AOJL Veronica praecox Scr LG SS Tm ma SR ABM* c* 2 E04 Prunella grand1flora* lam 66 BR Hb da ECA c* 4 AOJL VIola tricolor* Vlo LG FS Tm da SR WES E04 Ranunculus bulbosus* Ran GG BR Hb da ASA 5 AOJM Anagallis arvensls* Prl MG CP Tm ma SR ASA a E04 Stellaria graminea Car 66 Hb da WES 4 MO AOJM Geranium molle Ger MG AV Tm da SR ASA E040 Potenttlla erecta Ros . DG NV Hb da WES 3 3 AOlM Geranium puslllum Ger MG CP Tm da SR EBC 2 E04M Medlcago s.• falcata Fab MG Hb da WES 2 AR AOlM Scleranthus annuus Car MG FS Tm ma SR WES l E05 Hleraclum ptlosella* A5t 66 FS Hb ra WES 5 AOlM Vlcla 5.* nigra Fab MG FS Tm ma SR WES E05L Leontodon autumnalls* Ast L6 PG Hb ra WES 4 3 AOJM VIola arvensls Vlo MG AV Tm da SR WES 2 HI CR A04 Erlgeron acer* Ast 66 BR Tm ea SR WES FO IM Dactylls glomerata Poa MG AR HI ea CR WES A04 Satureja aclnos Lam GL SS Tm ea SR WES 4 F02D Agrostls gigantea* Poa DG MO HI ta CR EBC A04l Geranium columblnum Ger LG CP Tm ea SR ASA 2 F02L Agrostts stolonlfera Poa LG PG HI ta CR EBC 4 A04l Petrorhagla prollfera Car LG FS Tm ea SR ECA c* FOl Achtllea mtllefollum A5t HI ea CR WES 3 GM AR 5 A05 Genttanella campestrls Gen 66 NV Ts ma SR 2 FOJM Clrslum vulgare Ast MG AV HI ea CR WES 2 ABM A05 Unum cathartlcum lln Gl BR Ts ma SR WES 5 F04 Trifolium pratense Fab GG AR HI ta CR WES 5 A06 Myosotts 5trlcta Bor GG FS Tv ma SR EBC l F04 Trifolium repens Fab GG PG HI ta CR WES 5 A06 Erophtla v.* spathulata Car Gl SS Tv ma SR EBC 4 FOSM Ranunculus repens Ran MG PG HI ta CR WES A06 Veronica arven5is Scr GG FS Tv ma SR WES l 6 HI A06l Alra praecox Poa LG FS Tv ma SR ASA 2 GO I Agrostts vinealls Poa GG FS HI ea EBC 5 A06l Cerasttum pumtlum* Car LG SS TV ma SR ASA c* 4 GOIM Poa pratensis Poa MG AR ea EBC J HI A06l Myo5otl5 ramo5ls5lma Bor LG FS Tv ma SR ASA 3 G02 Festuca ovlna Poa 66 HI ea WES 5 ss A06L Sax1fraga trldactyllte5 Sax LG SS Tv ma SR ASA a GOl Agrostis captllarls Poa GG FS HI da WES 4 A06M Vlcla lathyroldes Fab MG FS TV ma SR ASA 604 6allum boreale Rub G6 BR HI ea EBC 4 B T HP G04 Veronica spicata* Scr GG BR HI ea WES 5 BOI Euphra5la 5trlcta Scr GL SS Ts ma HP ASA G04 Leontodon hispidus Ast GG BR HI ea ASA 5 BOI Rhlnanthus minor Scr 66 MO Ts ma HP WES 2 604 Scablosa columbarla• Dip GG BR HI ea ASA BO I Rhlnanthus serottnu5* Scr 66 MO Ts ma HP WES 2 6040 Potent ilia reptans Ros DG MO HI da WES BO IM Odontttes vulgaris Scr MG CP Tm ma HP WES 2 60411 Gallum mollugo Rub MG AR HI ea WES Hb SR G04W Hypericum montanum Hyp W6 OR HI ea ASA 2 c CO l Danthonla decumbens Poa 66 NV Hb ea SR WES 4 605 Fragarta vlrldls• Ros GG BR HI da ECA 4 CO IL Poa bulbosa Poa LG SS Hb da SR WES 2 605 Oxytropis campestrls* Fab GG BR HI da ABM c* 4 CO ll Poa compressa Poa LG FS Hb da SR WES l 605 Sangulsorba minor* Ro5 GG BR HI da ASA J C02 Senecio J.• gotlandlcus Ast Gl AS Hb ea SR END* c* l G05 Gallum saxattle Rub G6 NV HI da ASA 4 C02 Centaurea scablosa Ast 66 BR Hb ea SR WES 605 Gallum verum• Rub 6G BR HI da WES 3 C02D Gentlanella ullglnosa Gen DG TO Hb ea SR ASA* 2 605M Alchemtlla vulgaris Ros MG AR HI da ABM 2 C02l Crepl5 t.* pumtla Ast LG AS Hb ea SR END* c• l 605M Vlcla cracca Fab MG HI da EBC 2 AR C02M Senecio jacobaea Ast MG Hb ea SR WES l 605W Fragarla vesca Ros WG EP HI da WES J AR COl Potent tlla argentea Ros Gl SS Hb da SR WES 4 605W Trtrollum medium* Fab WG OR HI da WES 2 COl Scleranthu5 perennl5* Car 66 FS Hb da SR WES 605W Trifolium montanum Fab WG BR HI da ECA l COl Polygala comosa Pog 66 BR Hb da SR WES 605W VIola elatior Vlo WG OR HI da ECA c* 2 COlD Polygala amarella* Pog DG BR Hb da SR ECA 605W VIola hlrta Vlo WG OR HI da WES COlD Potentllla anserina Ros DG PG Hb da SR EBC 4 606 Primula verls* Prl GG BR HI ra WES COlD Saglna nodosa Car DG PG Hb ma SR EBC 606 Scorzonera humtlis Ast 66 NV HI ra WES COll Rumex acetosella Pog LG FS Hb da SR EBC H HI S COlM Ranunculus acrls* Ran MG AR Hb da SR WES a HO lD Seslerla c.* ullginosa Poa D6 MO HI ea S ECA 4 COlW Ranunculus polyanthemos* Ran WG OR Hb da SR ECA a 2 HO IL Fe5tuca oelandica Poa LG AS HI ea END c* C04 Arabl5 hlrsuta• Bra 66 BR Hb ra SR WES 4 HO IL Mellca ell lata• Poa LG AS HI ea S ABM* c* C04 Taraxacum s. Erythrosperma Ast G6 FS Hb ra SR ASA 5 H02 Armerla m.* eiongata Piu 66 FS HI ea S ECA C04 Taraxacum 5. Vulgaria A5t AR Hb ra SR ASA 4 H02 Dianthus deltoide5 Car GG FS HI ea S WES GM C040 Centaurlum erythraea Gen D6 TO Hb ra SR WES 2 H02 lychnls a.* oelandlca Car GG BR HI ea S END c* C040 Hleracium auricula Ast D6 NV Hb ra SR WES 2 H02 Campanula rotundtrola Cam GG FS HI ea S EBC 4 C04l Carllna vulgaris* Ast LG BR Hb ra SR WES c* H02D Aster llnosyrls Ast DG BR HI ea S ABM* c* 2 l C04l Hypochoeri5 maculata Ast l6 BR Hb ra SR ECA H02D Plantago maritima Pia DG TO HI ra S ASA C04M Bell Is perennis Ast MG AR Hb ra SR ASA H02l Hleractum dlchotomum Ast LG AS HI ea S END* c* C04M Plantago major* Pia MG PG Hb ra SR EBC HOJ Adonis vernal Is Ran GG FE HI da S ECA c* COSM Saglna procumbens Car MG PG Hb ma SR WES HOJ Carex obtusata Cyp GG BR HI da S EBC D Hb CR HOl Potentllla tabernaemontanl Ros GG BR HI da S ASA DO IM Holcus lanatus Poa MG AR Hb ea CR WES HOJ Pulsattlla pratensls* Ran GG BR HI da S ASA 4 D02 Plantago lanceolata Pia GM AR Hb ra CR WES 5 HOJ Pulsatilla vulgaris Ran GG BR HI da S ECA J E Hb HOl Ranunculus lllyrlcu5 Ran GG BR HI da S ECA c* 4 EO IL Phleum pratense• bertolonll Poa LG AR Hb ea ASA HOl VIola canlna* Vlo GG NV HI da S WES J E02 Hypericum maculatum* Hyp GG NV Hb ea WES 2 HOlD VIola pumtla Vlo 06 NV HI da ECA c* 2 E02 Rumex acetosa• Pog 66 MO Hb ea WES 2 HOlD Potent Ilia crantztl Ros DG BR HI da EBC 2

Acta phytogeographica suecica 76 64 Eddy van der Maarel

APPENDIX (contin.)

E.a IB�U lii: Sl lll HOJL Gallum oelandicum Rub LG AS HI da S END e* 4 N02 Carex erlcetorum Cyp 66 BR G da S ECA HOJL Potent Ilia arenaria Ros LG FE HI da ECA N03 Botrychtum lunaria Oph 66 NV G da S EBC 2 HOJL Potentllla co lllna Ros LG SS HI da S ECA N04 Coeloglossum vlrlde Ore 66 NV 6 ra S WES HOJL Viola rupestris Vto LG FS HI da S WES G CS p HI CS POI 0 Serratula tlnetorla* Ast 06 MO G ea CS ASA 10 I A venula pubescens* Poa GG AR HI ea CS WES 4 PO W Braehypodtum ptnnatum* Poa WG BR 6 ea CS WES 1 101 Phleum phleoldes Poa GG FE HI ea CS ECA 4 G a 101 Avenula pratensis* Poa GG BR HI ea CS ASA 5 QO IM Elymus repens Poa MG AV 6 ea WES 1 I M Festuca rubra* Poa MG AR HI ea CS EBC J o R 6 HP IOIM Lollum perenne Poa MG PG HI ea CS WES 3 RO IL Orobanche alba Oro LG FS G ea HP WES c* 10 I W Poa angustlfolla Poa WG BR HI ea CS EBC s Ch SR Poa 06 MO HI ea CS WES 2 s 1020 Mollnla caerulea* SO IM Cerastlum r.* trtvlale Car MG AR Ch da SR WES Poa MG AR HI ea CS WES 102M Festuca pratensls 2 T Ch CR 103 Flllpendula vulgaris Ros GG BR HI ea CS WES 5 TO IM Artemisia absinthium Ast MG AV Ch ea CR WES 103 Hypericum perroratum Hyp GG OR HI ea CS WES Ch u 103 Thallctrum simplex* Ran GG BR HI ea CS ECA UO tW Veronica chamaedrys* Scr WG OR Ch ea WES 103L Antherlcum llllago* Lll LG SS HI ea CS ECA UO IW Veronica orrlclnalls Scr WG OR Ch WES ea 103L Antherlcum ramosum Ltl LG FE HI ea CS ECA U02 Saxlfraga granulata* Sax GG AR Ch da ASA IOJL Vlncetoxlcum hlrundlnarla* Asc LG OR HI ea CS WES V Ch IOJL Sllene nutans* Car LG OR HI ea CS WES VO I L Globular la vulgaris Glo LG FE Ch ea ABM* c* 4 Ast MG AR HI ea CS WES IOJM Leucanthemum vulgare V02 Antennar la dlolca* Ros GG NV Ch ra EBC 4 2 IOJW Agrlmonla eupatorla* Ros WG OR HI ea CS WES V02L Gypsophlla rastlglata Car LG FS Ch da S ECA c* 4 103W Geranium sangulneum Ger WG OR HI ea CS WES 2 V03L Draba lncana Bra LG SS Ch ra S ABM 103W Hieraclum umbellatum Ast WG EP HI ea CS EBC 2 Ch CS w 103W Sesell llbanotls Apt WG OR HI ea CS ECA 2 WO I Artemisia oelandlca Ast GG BR Ch ea CS END c* 104W Astragalus glyeyphyllos Fab WG OR HI da CS WES W0 1L Artem isia campestrls* Ast LG FS Ch ea CS WES 4 105 Ast GG BR HI ra CS ECA Clrslum acaule* 5 W0 1L Artem isia rupestrts Ast LG FE Ch ea CS ECA c* 3 HI C J Cc JO IM Arrhenatherum elatlus* Poa MG AR HI ea WES XO I Sedum acre era GL FS Cc ea WES K SR s X0 1 Sedum rertexum era GL Cc ea ASA 4 KO I Orehls mascula* Ore GG BR G ea SR WES 4 ss s XO IL Sedum album era LG AS cc ea ASA 5 KO I Orchls morlo* Ore GG BR G ea SR ASA 4 y er KO I Orchls us tu lata Ore 66 BR G ea SR WES 4 s YO Hellanthemum canum Cls GG BR er ta S ABM* c* KO 10 Orehls mllltarls Ore 06 BR 6 ea SR WES 3 I YO I Hellan�hemum oeland1cum Cts GL AS er ta S END c* L 6 CR YO 1 Thymus serpyllum* Lam GG FS er ta S ASA* a 5 LOIM Ctrslum arvense Ast MG AV G ea CR EBC 2 YO Hellanthemum nummularlum* Cls 66 BR er ta WES 5 L02M Convolvulus arvensls Con M6 AV ta CR WES 3 I s YO I L Fumana procumbens Cls LG FE er ta ABM* c* 2 M 6 MO IO Carex rtaeca* Cyp 06 MO 6 ea ASA w ZO 1 Calluna vulgaris Er1 66 NV Pn da W WES 4 MO I W Oactylorhlza maeulata Ore W6 OR 6 ea WES Z0 1D Potenttlla rrutlcosa Ros DG MO Pn da ABM c* 4 M02 Allium vtneale Lll 66 AR G ea ASA 3 w Z02 Junlperus communis* Cup GW PR Ps ea W WES 5 M02 Alltum oleraceum Lll BR 6 ea WES 3 GM Z02W Euonymus europaeus Cel WG PR Ps ea W ASA 2 M02 Oactylorhlza sambuetna* Ore 66 BR 6 ea ABM 4 Z03W Prunus splnosa Ros WG PR Ps ea W WES 2 M020 Equlsetum palustre Equ DG MO 6 ea EBC 2 Z03W Rhamnus cathartlcus Rha WG PR Ps ea W WES M020 Platanthera ehlorantha Ore 06 NV 6 ea ASA Z03W Rosa canlna Ros WG PR Ps ea W WES M04W Llstera ovata Ore W6 OF 6 ra I WES Z03W Rosa dumalls Ros WG PR Ps ea W WES N 6 s Z04W Pleea abies Pin WG QF Pt ea W ECA NO IL Al lium s.* alvarense Lll LG AS G ea END e* 4 Z04W Plnus sylvestrls Ptn WG QF Pt ea W ECA 4 NO IL Eplpactls atrorubens Ore L6 BR G ea WES 2 N02 Carex earyophyllea Cyp GG BR G da S WES 5

References Braakhekke, W. 1980. On coexistence: a causal ap­ proach to diversity and stability in grassland vegeta­ Albertson, N. 1950. Das grosse siidliche Alvar der Insel tion. Thesis, Wageningen, also Agric. Res. Rep. 902: bland. Eine pflanzensoziologische Ubersicht. 1-64. Svensk bot. Tidskr. 44: 269-331. Du Rietz, G. E. 1931. Life-forms of terrestrial flowering Barkman, J. J. 1978. Synusial approaches to classifica­ plants. I. - Acta phytogeogr. suec. 3: 1-95 . tion. -Classification of plant communities, 2nd. ed. Ecological communities: conceptual issues and the The Hague. pp. 111-165. evidence. 1984. (eds. Stone et al.) - Princeton. 1979. The investigation of vegetation texture and 614 pp. structure. - The study of vegetation. The Hague. Ellenberg, H. 1979. Zeigerwerte der Gefasspflanzen Mit­ pp. 123-160. teleuropas. 2. Aufl. - Scr. geobot. 9: 1-122. Bengtsson, K., Prentice, H. C., Rosen, E., Moberg, R. - 1982. Vegetation Mitteleuropas mit den Alpen. 3. & Sjogren, E. 1988. The dry alvar grasslands of Aufl. - Stuttgart. 989 pp. bland: ecological amplitudes of plant species in rela­ Giller, P. S. 1984. Community structure and the niche. tion to vegetation composition. - Acta phytogeogr. -London. 176 pp. suec. 76. Grime, J. P. 1977. Evidence for the existence of three

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primary strategies in plants and its relevance to Pianka, E. R. 1983. Evolutionary ecology. 3rd ed. - ecological and evolutionary theory. -Am. Nat. 111: New York. 416 pp. 1169- 1194. Raunkiaer, C. 1934. The life forms of plants and - 1979. Competition and the struggle for existence. - statistical plant geography. - Oxford. 632 pp. Population dynamics. - Oxford. pp. 123-139. Rejmanek, M. & Rosen, E. 1988. - The effects of col­ - 1979. Plant strategies and vegetation processes. - onizing shrubs (Juniperus communis and Potentilla Chichester. 222 pp. fruticosa) on species richness in the grasslands of Grime, J. P. & Hunt, R. 1975. Relative growth-rate: its Stora Alvaret, Oland (Sweden). - Acta phytogeogr. range and adaptive significance in a local flora. - J. suec. 76. Ecol. 63: 393-422. Root, R. B. 1967. The niche exploitation pattern of the Grubb, P. J. 1977. The maintenance of species-richness blue-gray gnatcatcher. - Ecol. Monogr. 37: in plant communities: the importance of the 317-350. regeneration niche. - Bioi. Rev. 52: 107-145. Rosen, E. 1982. Vegetation development and sheep graz­ - 1985. Plant populations and vegetation in relation to ing in limestone grasslands of South Oland, Sweden. habitat, disturbance and competition: problems of - Acta phytogeogr. suec. 72: 1-104. generalization. - The population structure of Rosen, E. & Sjogren, E. 1988. Plant cover in alvar vegetation. Dordrecht. pp. 595-635. junipers on Oland. Distribution features correlated Hulten, E. 1950. Atlas over vaxternas utbredning i to shrub size and shape. Acta phytogeogr. suec. 76. Norden. - Stockholm. Sterner, R. 1938. Flora der lnsel Oland. - Acta Hulten, E. & Fries, M. 1986. Atlas of North European phytogeogr. suec. 9: 1-169. vascular plants North of the Tropic of Cancer, 1-3. Sterner, R. 1986. Olands karlvaxtflora. 2nd Ed. by A. - Konigstein. Lundqvist (English summary). - Stockholm. 400 Iversen, J. 1936. Biologische Pflanzentypen als Hilfsmit­ pp. tel in der Vegetationsforschung. - Meddr Skalling Tilman, D. 1982. Resource competition and community Lab. 4: 1-224. structure. - Monogr. Popul. Bioi. 17: 1-296. Krahulec, F., Rosen, E. & van der Maarel, E. 1985. Pre­ Titlyanova, A., Rusch, G. & van der Maarel, E. 1988. liminary classification and ecology of dry grassland Biomass structure of limestone grasslands on Oland communities on (>lands Stora Alvar. - Nord. J. in relation to grazing intensity. - Acta phytogeogr. Bot. 6: 797-809. suec. 76. Krok, Th. B. N. & Almquist, S. 1984. Svensk Flora. van der Maarel, E. 1965 . Beziehungen zwischen 0. 26th ed. by L. Jonsell & B. Jonsell. - Stockholm. Pflanzengesellschaften und Molluskenfauna. - Ber. 570 pp. int. Symp. int. Ver. Veg.-kunde 1960: 184-198. Miller, J. C. 1980. Niche relationships among parasitic - 1966. On vegetational structures, relations and insects occurring in a temporary habitat. - Ecology systems.- Thesis Utrecht. 170 pp. 61: 270-275. - 1980. Epharmony and bio-indication of plant com­ Moravec, J. 1967. Zu den azidophilen Trockenrasen­ munities. - Ber. int. Symp. int. Ver. Veg.-kunde gesellschaften Siidwestbohmens und Bemerkungen 1979: 7- 17. zur Syntaxonomie der Klasse Sedo-Scleranthetea. - - 1981. Fluctuations in a coastal dune grassland due to Folia geobot. phytotax. 2: 137-178. fluctuations in rainfall: experimental evidence. - Noy-Meir, & van der Maarel, E., 1987. Relations be­ Vegetatio 47 : 259-265. I. tween community theory and community analysis in - (in press) Species diversity in plant communities in vegetation science: some historical perspectives. - relation to structure and dynamics. - Proc. lnt. Vegetatio 69: 5-15. Symp. Vegetational Structure, Utrecht. SPB Publ. Oberdorfer, E. 1979. Pflanzensoziologische Exkur­ The Hague. sionsflora. 4. Aufl. - Stuttgart. 997 pp.

Acta phytogeographica suecica 76

The effects of colonizing shrubs (Juniperus communis and Potentilla fruticosa) on species richness in the grasslands of Stora Alvaret, Oland (Sweden)

Marcel Rejmdnek & Ej vind Rosen

Abstract Rejmanek, M. & Rosen, E. 1988. The effects of colonizing shrubs (Juniperus communis and Potentilla fruticosa) on species richness in the grasslands of Stora Alvaret, bland (Sweden). -Acta phytogeogr. suec., Uppsala. ISBN 91-7210-076-1 . 76.

Dependence of species richness of vascular plant communities on Stora Alvaret, bland, Sweden, on the total canopy cover of colonizing shrubs (Juniperus communis and Potentilla fruticosa) was studied. A series of plots 0.25, 1, 4, 16, 64, and 256 m2 in area were sampled in communities with 10 40-50 %, 70-80 % and >90 %of canopy cover of Juniperus < OJo , or Potentilla. The most important difference between the effect of these two colonizers on plant community composition is that species richness declines more dramatically with increas­ ing Potentilla cover than with increasing Juniperus cover. There is a monotonic decline of species number with increasing shrub cover in Potentilla plots of all sizes. The total species number in large (256 m2) Juniperus plots follows a unimodal curve with a peak at about 75 % shrub cover. The alvar species number in Juniperus plots of all sizes declines monotonically. The most dramatic decline of the alvar species number occurs between 75 and 100 OJo shrub cover of either of the colonizing shrubs.

Key-words: Grasslands, pastures, shrub colonization, species richness, alvar, bland, Juniperus communis, Potentilla fruticosa.

Marcel Rejmdnek, Department of Botany, University of California, Davis, CA USA . 95616, Ej vind Rosen, Institute of Ecological Botany, Uppsala University, Box Uppsala, 559, 751 22 Sweden.

Introduction 10.0 Ofo to 18.3 Ofo in the last 15 years. Naturally, Stora Alvaret is a large limestone plateau in the shrub colonization expressed either as density or as south of the Baltic island of bland. Both the rich cover will follow some sigmoid function (Holthuij­ flora and outstanding vegetation of this area are zen & Sharik 1985). In this paper, we address the well known (Du Rietz 1923, Sterner 1938, Albert­ following questions: (1) at which total shrub cover son 1950, Krahulec et al. 1986). Partly or com­ do various alvar species disappear, (2) how many pletely abandoned pastures within the Stora new species arrive, and (3) what is the resulting Alvaret grassland complex are recently becoming species richness of modified plant communities? colonized by the shrubs Juniperus communis L. Because of the remarkable species richness and (Cupressaceae) and Potentilla fruticosa L. phytogeographical uniqueness of alvar vegetation, (Rosaceae), their relative distributions varying shrub colonization poses a serious conservation with soil moisture conditions (Konigsson 1968, problem (Rosen 1982, 1987). Rosen 1982, 1985, 1988). The dry grasslands colonized by Ju niperus are In general, Juniperus forms dense stands on classified by Krahulec et al. (1986) as Veronica relatively dry soils 15 cm but <40 cm deep and sp icata A venula pratensis association (Mesobro­ > - Potentilla colonizes rather wet soils which are > 35 mion?, Brometalia erecti). The wet grasslands col­ cm deep. Using permanent plot data, Rosen (1988) onized by Potentilla apparently belong to the calculated that the Juniperus cover increased from alliance Molinion (Molinietalia).

Acta phytogeographica suecica 76 68 Re}mtinek & Rosen

Fig. 2. One of the Juniperus plots with 90 cover. - Fig. 1. One of the Juniperus plots with 40-50 OJo cover. > % - Alvar of Drostorp, July 1987. Photo: E. Rosen. Alvar of Drostorp. July 1987. Photo: E. Rosen.

Methods all vascular plant species. Usually at least two plots of the same size were analyzed in each cover Study sites. - We selected two areas for analysis, category. The plots were not nested. The shrub each of uniform soil depth: a dry grassland col­ canopy cover in each plot was estimated by onized by Ju niperus on soil 18-28 cm deep and a dividing the whole quadrat area into subplots wet grassland colonized by Potentilla on soil 55- where cover was estimated separately and an aver­ 70 cm deep. Homogeneity of soil depth was age value calculated. The maximum quadrat size checked using five to ten probes with a calibrated (16 16 m) was chosen with respect to the largest x metal pole in each sampled plot. The first area is homogeneous area available for > 90 OJo Juniperus located in the northern part of the Stora Alvaret, stands. The study was conducted during July and about 0.5 km NE of the abandoned village August, 1987. Drostorp. The second is in the southern part of the Stora Alvaret about 1 km W of Traby (Figs. 1-4). Within each area we selected four subareas, each Results differing in shrub canopy cover. The four cover categories correspond to four stages of shrub Data from 8 8 and 16 16 m plots are sum­ x x colonization: < 10 OJo , 40-50 OJo , 70-80 OJo , > marized in Tables 1 and 2 for Juniperus and Poten­ 90 OJo . Ring counts show that the oldest Juniperus tilla plots respectively. The most important differ­ stage ( > 90 OJo cover) is about 80 years old. We do ence between the effect of these two colonizers on not know a reliable method to age Potentilla plant community composition is that colonization stands. We assume that this sequence of four by additional species occurs only in Juniperus stages can be interpreted as a time series. stands. Mainly ruderal and forest species are ''new'' to the dense Juniperus stands (see the lower Vegetation analysis. - In each subarea, we placed part of Table 1). In this case, new species partially a series of randomly located quadrats, 0.5 0.5, balance the loss of other ones, so that overall x 1 1 m, 2 2 m, 4 4 m, 8 8 m, and species richness declines slowly with increasing x x x x 16 16 m, for presence/absence determination of Juniperus cover (Fig. 5). In contrast, stands col- x

Acta phytogeographica suecica 76 The effe cts of colonizing shrubs on species richness 69

Fig. 3. Potentilla fruticosa plot with 40-50 0,1o cover. ­ Fig. 4. Potentilla fruticosa plot with 90 O!o cover. - > Alvar of Traby. 7 August 1987. Photo: E. Rosen. Alvar of Traby. 7 August 1987. Photo: E. Rosen.

onized by Potenti/la lose species as shrub cover in­ plots) is apparently caused by its preferential col­ creases, and no species are gained. onization of elevated microhabitats, very often ac­ Fig. 5 shows the relationship between species tive or abandoned ant-hills, with dry grassland number and shrub cover in 2 2, 8 8, and species. These species contribute substantially to X x 16 16 m plots. There is a monotonic decline of the total species richness of these communities, x species number with increasing shrub cover in and consequently their elimination by Potentilla Potenti/la plots of all sizes. However, the results in a rapid decline of the total species dependence seems to change from linear or even number. Species typical of wet grasslands survive concave to convex as plot size increases. The total mainly in depressions between elevated patches species number in large (256 m2) Juniperus plots colonized by Potentilla. A detailed analysis of this seems to follow a unimodal curve with a peak at phenomenon will be presented in another paper. about 7 5 % of shrub cover. The alvar species Different species depletion rates in Juniperus number in Juniperus plots, on the other hand, and Potentilla stands correlate with different pro­ seems to decline monotonically and, with increas­ portions of incident global solar radiation ing plot size, in an increasingly similar fashion to penetrating through the shrub canopy: 2.1-2.9 OJo the curve representing Potentilla stands. The most in > 90 % Potenti/la stands versus 5.4-6.6 % in dramatic decline of the alvar species number oc­ > 90 OJo Juniperus stands, varying with the propor­ curs between 75 and 100 OJo of shrub cover. Results tion of direct and diffuse solar irradiation. (Each from 0.25, 1, and 16 m2 plots (not shown) are in number listed is a mean of 30 to 50 readings taken full agreement with the pattern described. along randomly located transects. The differences between means for Potentilla and Juniperus stands are significant at p<0.04 or p<0.01 levels using the two-tailed t test.) Greater available solar radia­ Discussion tion may be the main reason why many new species accompany Juniperus (e.g., Berberis vulgaris, A faster initial decline of species number recorded Galium aparine, Geum urbanum, Primula veris, in plots colonized by Potenti/la (especially in small Veronica officina/is, Viola hirta, V. riviniana,

Acta phytogeographica suecica 76 70 Rejmtinek & Rosen

Table Species frequency in quad rats of two si zes placed in four Table (cont'd) I. categories of Juniperus communis cover . Local range of habitats : (A). 1 species typical for the Alvar : (M) , species typical for semicultural and cultural meadows and ruderal plant communities : (W). species typical for woodland and dense shrub land . Frequency : (H). species found in all analyzed quad rats; (I ) , species found in on ly one out of two quad rats : 2 Quad rat size (m ) 64 256 (-) , species not fo und. Nomenclature follows Lid ( 1985) . Stem diameter ; mean of the 0 largest shrubs at 0 cm above ground . Juniperus cover <1 0 40- 70- )90 Helianthemum nummularium H H H H H H AMW Rosa canina dumalis H H H I H H I H I & A H. oelandicum AMW Senecio jacobaea ssp. got !. I A Oxytropis campestris H H I H H I M Alchemilla sp. A Phleum *bertolonii I I I I M Arrhenatherum elatius A Potentilla fruticosa I M Centaurea jacea A P. tabernaemontani H H H H H H M C. scabiosa H A Pulsatilla pratensis H H H H H H M Cynosurus cristatus H A Sedum album I I M Daucus carota A S. reflexum H H H H H M Elytrigia repens A Taraxacum gr. Erythrosp . I H H I I M Leucanthemum vulgare A Thymus serpyllum H H H H H H M Linaria vulgaris A Veronica spicata H H I H I I I M Medicago falcata H H H A Vincetoxicum hirundinaria I I H M Taraxacum officinale I A(M) Filipendula vulgaris H H H H H H H H A(M) Fragaria viridis H H H H H H H H M Trifol ium medium I A(M) Hieracium pilosella H H H H H H H M T. montanum I H I I A(M) Unum catharticum H H H H H M T. pratense H H I H H I I H MW Agrimonia eupatoria I H A(M) Orchis mascula I H H I H I I A(M) ustulata H H I MW Cotoneaster integerrimus H H H 0. l A(M) Prune lla grandiflora H H H H H H H MW Dactylis glomerata I I Achillea millefolium H H H H H H H MW Draba incana AM AM Agrostis gigantea I MW Epilobium angustifolium I AM A. vinealls H H l I MW Fragaria vesca I H AM Anthoxanthum odoratum H H H H I MW Ga lium aparine H H AM Anthyllis vulneraria H H H H H MW Geranium robertianum I AM Arenaria leptoclados H H H MW Geum urbanum H H I H H I M Poa compressa H H H H H AM Briza media H H H H H H \V M Primula veris I H I AM Carex flacca H I H I H H H \V M Solanum dulcamara I I AM Cerastium semidecandrum I H H H H H \V M Torilis japonica H H AM Dactylorhiza sambucina I \V M Valeriana officinalis AM Danthonia decumbens H I H \V I AM Festuca ovina H H H H H H H H MW Veronica chamaedrys Ga lium verum H H H H H H H H MW V. officinalis H I H AM AM Lotus corniculatus H H H H H H Berberis vulgaris H H H w AM Luzula campestris H H l H H H Carex muricata H w AM Medicago lupulina H H H H H H Crataegus laevig . monog . H w & AM Phleum phleoides I H I I H H Dryopteris fi lix-mas I w AM Pimpinella saxifraga I Lonicera xylosteum I w AM Plantago lanceolata H H H H H H Moehringia trinervia H w AM Polygala amarella I Mycelis muralis I w AM P. vulgaris H H H H H H Polypodium vulgare I w AM Ranunculus bulbosus l H H H I Pulmonaria officinalis I w AM Scabiosa columbaria l Rhamnus catharticus H H w AM Sedum acre H H I H H Ribes uva-crispa I H w AM Sesleria caerulea I Sorbus intermedia H H I w AM Stellaria graminea I H I H H H Viola hirta H H H H H H w Trifolium campestre l H H V. riviniana H H I I I AM w AM T. repens H H H H I AM Viola rupestris Phleum *bertolonii = P. pratense ssp. bertolonii.

Solanum dulcamara, Moehringia trinervia) but (e.g., Avenula pratensis, Carex caryophyllea, none accompany Potentilla. Part of these typical Filipendula vulgaris, Fragaria viridis, Hieracium Juniperus accompanying species are known as pilosella, Prune/la grandiflora). Approximately more-or-less nitrophilous. This is also known from the same number of species typical of wet alvar Juniperus scrub on poor heathland soil in the grasslands survive under Potentilla canopy (e.g., Netherlands (Barkman 1985). A good correlation Carex flacca, C. panicea, Geum rivale, Molinia has been found between plant cover composition caerulea, Selinum carvifolia, Sesleria caerulea), within junipers and size and shape of the shrubs but most do not reproduce. All species typical of (Rosen & Sjogren 1988). dry alvar grasslands are completely eliminated in Several alvar species survive (but many of them dense Potentilla stands (see Tables 1 and 2). do not reproduce) under dense Juniperus canopy Decline of species richness with woody species

Acta phytogeographica suecica 76 The effe cts of colonizing shrubs on species richness 71

Table 2. Species frequency in quadrats of two sizes placed in four categories of Potentilla fruticosa co ver . Local range of habi tats: (A) . species growing in dry alvar grass lands; (D ), species grow in� in moist alvar grasslands, �uch as depressions and fen surroundmgs. Frequency : (H), species found in all quad rats ; 11), species found ( in two out of three quad rats; (I), species found in only one out of two or three quad rats ; (-), species not found.

2 Quadrat size (m ) 256 20

Potentilla cover <1 0 40- 70- >90 <1 0 40- 70- )90 ( %) 50 80 80 so Potentilla height (cm) 50 50 90 11 0 60 60 95 100 10 Number of quadrats analysedS 2 2 2 2 2 1 2 3 44 38 23 53 33 18 Mean number of species 13 LIB 0 ��--�-,.-�,-�-.-,,-.-�-.�--.-�,-�----�� � A Achi llea millefolium H I H 60 A Agrostis capillaris H H H H Q) A A. gigantea I I u A A. vinealis H H H H 50 A Antennaria dioica H H Q) A Anthoxanthum odoratum Q. I 40 A Anthyllis vulneraria H H H c.n A Arabis hirsuta I I A Asperula tinctoria H H H H 30 A Avenula pratensis H I H H 0 A A. pubescens I H H H H 20 A Briza media H H I.. A Calluna vulgaris I Q) I H H H H H A Campanula rotundifolia 10 A Carex ericetorum I I I A Centaurea jacea H I H E A Ce�astium semidecandrum I H H ::l I H A Cirsium acaule z 70 A Danthonia decumbens I A Draba incana I ·A Festuca ovina H H H H H 60 I H 11 A Fragaria viridis I A Galium verum H H H H H 50 A Helianthemum nummularium I I A Juniperus communis I H H H H H 40 A Lotus corniculatus I H I H I A Lu zula campestris H 30 A Medicago lupulina H H H 256 m2 A Pimpinella saxifraga H 20 A Poa angustifolia I All species in Juniperus plots A P. compressa e A Polygala amarella H H 10 A er species in Juniperus plots • 0 lv A Potentilla tabernaemontani All species in Potentille plots A Ranunculus bulbosus o ��--�--.-�,-�-.--.-.-�-.-.--��-.�-,--.-4• A Thymus serpyllurn H H H 0 10 20 30 40 50 60 70 ao 90 A Veronica spicata I 100 AD Elytrigia repens I H H H I Shrub Cover (:.;) AD Filipendula vulgaris H H H H H H H H H I H H AD Galium boreale H H H AD G. oelandicum I I Fig. 5. Dependence of vascular plant species number on AD nu la salicina H H H H I AD Knautia arvensis I canopy cover of Juniperus communis and Potentilla AD Linum catharticum H H H H H AD Orchls mascula H fr uticosa. AD Prunella vulgaris H H H H AD Scorzonera humilis H I I AD Teucrium scorodonium I AD Trifolium pratense H I H H H AD T. repens I H H H H H H AD Vicia hirsuta H AD Viola pumila H I H H I D Betula pendula I I I H D I Carex elata I D H H H H H H H C. flacca H D colonization has been reported elsewhere (Hobbs C. flava I D C. hostiana I I I Mooney 1986, Prach 1981, Specht Morgan D C. lasiocarpa I I I H I & & D C. panlcea H H H H H I 11 D C. tomentosa I 11 1981). Unfortunately, results are not directly com­ I I D Deschampsia caespitos<> H H H H I D Equisetum pratense H I I parable because of different sampling methods I I D Festuca pratensis I I I H I D Galium palustre I I I 11 used. The sample size itself can have an important I D Geum rivale H H I H H I I H D lnula britanica I H H I effect on results obtained (Fig. 5). The largest plot D Mentha arvensis H I H I I I D Molinia caerulea H H H H H H H H analysis (256 m2) suggests that shrub colonization D Phalaris arundinacea H I I D Plantago maritima H H I H threatens alvar plant communities only with D Potentilla anserina I I D P. erecta H H H H H H H Juniperus or Potentilla cover 70 %, but plots D P. fruticosa H H H H H H H H > D P. palustris I 4-64 m2 in size showed declines in alvar species D Primula farinosa H D Ranunculus repens I H H at 50 % shrub cover. (Note that in Fig. 5 all species D R. flamula H H D Salix rosmarinifolia H H 11 in Potentilla plots represent the alvar species.) Scutellaria hastifolia D I D Selinum carvifolia H H I H I H 11 Small plot data reveal changes in species frequency D Sesleria caerulea H H I H H H H H D Succisa pratensis H H H H H H as influenced by shrub colonization. Frequency in D Veronica scutellata I I Crepls sp. I Hieracium spp . H H H H turn, together with other factors, determines the Orchis sp. I I Taraxacum sp. I H probability of species survival.

Acta phytogeographica suecica 76 72 Rejmanek & Rosen

Acknowledgement. This investigation forms part of a Konigsson, L. K. 1968. The Holocene history of the project supported by NFR, the Swedish Natural Science Great Alvar of Oland. - Acta phytogeogr. suec. 55: Research Council (to M. Rejmanek-guest scientist pro­ 1-172. gram) and SNV, the National Swedish Environment Krahulec, F., Rosen, E. & Maarel, E. van der 1986. Pre­ Protection Board (to E. Rosen) with the Uppsala liminary classification and ecology of dry grassland University Ecological Research Station on Oland as a communities on Glands Stora Alvar (Sweden). - basis. We thank E. van der Maarel, Uppsala University, Nord. J. Bot. 6: 797-809. and M. G. Harbour and G. R. Robinson, University of Lid, J. 1985. Norsk-svensk-finsk flora. - 5th ed. of California, for comments on the manuscript. "Norsk flora". Oslo. 837 pp. Prach, K., 1981. Selected characteristics of shrubby suc­ cessional stages of abandoned fields in Bohemian References karst. - Preslia 53: 159-169. Rosen, E. 1982. Vegetation development and sheep graz­ Albertson, N. 1950. Das grosse siidliche Alvar der Insel ing in limestone grasslands of south Oland, Sweden. Oland. Eine pflanzensoziologische Ubersicht. - - Acta phytogeogr. suec. 72: 1-104. Svensk bot. Tidskr. 269-331. Rosen, E. 1985. Succession and fluctuations in species 44: Barkman, J. J. 1985. Geographical variation in associa­ composition in the limestone grasslands of south tions of juniper scrub in the central European plain. Oland. - Miinst. geogr. Arb. 20: 25-33. - Vegetatio 59: 67-71. Rosen, E. 1987. Vaxtekologisk naturvardsforskning pa Du Rietz, G. E. 1923. Studien iiber die Helianthemum Olands Stora Alvar. - Acta Univ. Upsaliensis, Ser. 53: 53-65. oelandicum Assoziation auf Oland. - Svensk bot. c, Tidskr. 17: 69-82. Rosen, E. 1988. Development and seedling establish­ Ekstam, U., Jacobson, R., Mattson, M. & Porsne, T. ment within a Juniperus communis stand on Oland, 1984. Olands och Gotlands vaxtvarld. - Stockholm. Sweden. - Acta bot. neerl. (in press) 336 pp. Rosen, E. & Sjogren, E. Shrub expansion in alvar Hobbs, R. J. & Mooney, H. A. 1986. Community grasslands on Gland. - Acta phytogeogr. suec. 76. changes following shrub invasion of grassland. - Specht, R. L. & Morgan, D. G. 1981. The balance be­ Oecologia (Berlin) 70: 508-513. tween the foliage projective covers of overstorey and Holthuijzen, A. M. A. & Sharik, T. L. 1985. Coloniza­ understorey strata in Australian vegetation. - Aust. tion of abandoned pastures by eastern red cedar J. Ecol. 6: 193-202. (Juniperus virginiana L.). - Can. J. For. Res. 15: Sterner, R. 1938. Flora del Insel Oland. - Acta 1065-1068. phytogeogr. suec. 9: 1-169.

Acta phytogeographica suecica 76 Das Naturschutzgebiet in Gosslunda Lars Rodenborg

Abstract Rodenborg, L. 1988. Das Naturschutzgebiet in Gosslunda. Acta phytogeogr. suec., - 76, Uppsala. ISBN 91-7210-076-1.

The vegetation and in part the flora within a nature reserve of approximately 11 ha ("UG"), situated in the central part of the great Alvar of the island of (Hand, were investigated against a background of former and present-day land use. The bedrock consists of limestone but the soil has an appreciable amount of siliceous material and a weak to moderate acidity in the upper horizons. The area was mapped four times between 1641 and 1826. Formerly the area, being infields to the alvar-village of Gosslunda, mainly was meadow with scattered arable land. In the 20th century the area in the main has been used as pasture for cattle and some­ times horses. The times of pasture varied in different parts of the area. The epigeic vegetation has been described and divided into vegetational units, distin­ 13 guished by locally characteristic species. The epilithic vegetation, on siliceous or calcareous substratum, respectively, has been described briefly. Finally some interesting species have been commented upon.

Lars Rodenborg, Lappkttrrsvttgen Stockholm, Sweden. 48, 10405

Einleitung Lage und Einteliung des Naturschutzge­ bietes lm Jahre 1969 wurde am Pflanzenbiologisehen Institut zu Uppsala eine von mir verfaBte Arbeit mit dem Titel Das Natursehutzgebiet von Gosslunda (Fig. 1 und 2) , ,Flora oeh vegetation pa naturreservatet i Gosslunda pa wurde am 5 Sept. 1972 dureh Besehluss der Provinzialre­ sodra bland'' (Flora und Vegetation im Natursehutzge­ gierung zu Kalmar (,Lansstyrelsen i Kalmar lan") aus­ biet in Gosslunda im Siiden der Insel bland) in verviel­ gewiesen. Es hat ein Areal von ea 11 ha (Hohe iiberdem faltigten Exemplaren herausgegeben. Diese Arbeit war Meer ea 23 m). Es besteht aus sog. ,inagomark" der auf Gelandearbeiten in den Jahren 1966-1968 begriin­ Grundstiieke Gosslunda 1 :3 und 2:2 in der Gemeinde det. In den darauffolgenden Jahren habe ich diese Un­ von Hulterstad im SO von bland und wird begrenzt, im tersuehungen in unregelmaBigen Abstanden weiterge­ N und W vom ,GroBen Alvar", im 0 und S von anderer fiihrt, zuletzt im Sommer 1987. Dieser Beitrag soli eine ,inagomark" des Dorfes Gosslunda. Das UG ist auf al­ Zusammenfassung der Ergebnisse meiner Untersuehun­ Ien Seiten von Steinmauern umgeben (Fig. 1). gen dieses Natursehutzgebietes bilden. Das UG kann in vier Teilgebiete eingeteilt werden, ab­ Die Nomenklatur und die Artenabgrenzung folgen fiir gesehen von zwei A.ekern, die ebenfalls zum Reservat­ die Gefasspflanzen in der Regel Hylander (1955, 1966), areal gehoren und im SO liegen. Die vier Teilgebiete wer­ in einigen Fallen aber Tutin et al. (1964-1980), fiir die den unten A, B, C und D genannt. Sie grenzen im W un­ Moose Grolle (1983), bzw. Corley et al. (1981) und fiir mittelbar an das ,GroBe Alvar". Alle Teilgebiete wer­ die Fleehten Santesson (1984). den dureh Steinmauern voneinander abgegrenzt (Fig. 1). Die Kennarten (inkl. Praferenzarten) der lokalen Ge­ Das Teilgebiet A ist dureh Steinmauern in drei Unter­ sellsehaftseinheiten werden nur auf der Grundlage der gebiete geteilt. Durch eine in Richtung N-S gehende Vegetation des Natursehutzgebietes aufgestellt, sind also Mauer wird der 0-Teil von A abgegrenzt. Dureh eine in nur als lokale Kennarten zu betraehten. Richtung NW-SO gehende Mauer wird der W-Teil von Das Natursehutzgebiet (Untersuehungsgebiet) wird im A in einen NO-Abschnitt und einen SW-Abschnitt ge­ folgenden mit UG bezeichnet. teilt.

Acta phytogeographica suecica 76 74 Lars Rodenborg

Zweck aller dieser Mauern war, teils die Grundstiicke SW-Teil von D, in steppenartigem Trockenrasen mit Gosslunda 1:3 und 2:2, teils Gebiete mit verschiedener u.a. A venula pratensis, Trifolium montanum, Geranium Bodennutzung (Acker, Wiese, Weide) abzugrenzen. sanguineum, Artemisia oelandica (vgl. Sterner 1948, S. 128 f.: ,Vorkommen von sog. Kalkpflanzen auf Boden mit deutlich sauerer Reaktion"). Die beiden hochsten Werte, 6,8 und 6,9, wurden im 0-Teil von A unter Rain­ vegetation bzw. zerophiler Saumvegetation gemessen. Boden. Physikalische und chernische Ver­ Die vertikale Amplitude der pH-Werte ist oft sehr klein (0,2 oder sogar 0,1). Eine Auslaugung der oberen Bo­ haltnisse denschichten scheint in neuerer Zeit nur schwach zu sein oder gar nicht stattzufinden. Die oft ziemlich niedrigen Das Naturschutzgebiet als Ganzes ist schwach nach 0 pH-Werte des UG konnen von silikatreichem Moranen­ geneigt. Dariiber hinaus gibt es keine ausgepragten Ni­ material bedingt sein (vgl. die zahlreichen, erdfesten Sili­ veauunterschiede. Der Felsengrund besteht aus Kalk­ katblocke). stein, der hier und da in der Form ebener Felsplatten zum Vorschein kommt, vor all em nahe der W -Grenze Spezifische Leitfahigkeit. Die Werte liegen zwischen 40 des UG (am ,Gro.Ben Alvar") und auf dem ziemlich und 100 (16 Messungen, je in 10 cm Tiefe), sind also niedrig liegenden NO-Teil. Diese Kalkfelsplatten sind ziemlich niedrig. Der niedrigste Wert stammt aus dem 0- auf dem SW-Teil von A und auf B teilweise von tiefen Teil von A (entsprechender pH-Wert 5,9) in steppenarti­ Spalten durchzogen, wodurch der Boden ein karstahnli­ ger Trockenrasenvegetation mit azidophilen Einschlagen ches Aussehen bekommt. Auf dem N- und 0-Teil des (Artemisia campestris, Anthoxanthum odoratum, Se­ UG diirfte der Boden meistens recht tief sein. Feinerde­ dum rupestre; Cladina arbuscula. struktur scheint vorzuherrschen. Sandboden kommt Kalzium. Die Werte sind 520, 760, 800, 880 (4 Messun­ nicht vor. Zahlreiche erdfeste, gro.Bere und kleinere Sili­ gen in je 10 cm Tiefe). Der niedrigste Wert kommt von katblocke liegen im UG verstreut, besonders in C und D. derselben Stelle, an der auch die niedrigste spezifische In den Steinmauern sind sowohl Kalkstein als auch Sili­ Leitfahigkeit gemessen wurde (siehe oben). katgestein in wechselnden Proportionen vertreten. An einigen Stellen gibt es ziemlich tiefe Mulden im Bo­ Kalium. Die Werte liegen zwischen 5 und 16 (16 Messun­ den (natiirlich oder kulturbedingt); u.a. eine langge­ gen, je in 10 cm Tiefe). Eine der beiden Stellen mit dem streckte, grabenahnliche Vertiefung (altes Bachbett) niedrigsten Wert (5) hatte auch den niedrigsten Ca­ durch den NW-Teil des UG in Richtung NW-SO, in dem Gehalt (520) und den geringsten Wert der spezifischen stellenweise Kalkstein zu Tage tritt. Im NW-Teil des UG Leitfahigkeit (40). gibt es auch einige alten Graben, die einen alten Acker Phosphor. Die Werte liegen zwischen 0,9 und 1,2 (16 umgeben. Durch das UG geht au.Berdem ein Fahrweg Messungen, je in 10 cm Tiefe), sind also sehr einheitlich. vom Dorf zum ,Gro.Ben Alvar" im W. Gesamtstickstoff . Die Werte sind 545, 687, 461, 512 (4 Die Bodenreaktion ist schwach bis massig sauer (siehe Messungen, in je 10 cm Tiefe, an denselben Stellen, wo weiter unten). Im UG wurden am 6. Juli 1973 an 16 ver­ das Kalzium und der Humusgehalt gemessen wurden). schiedenen Stellen Bodenproben entnommen, und zwar Der hochste Wert fand sich an der Stelle, an der auch der an jeder Stelle an der Bodenoberflache (0- 1 cm) und in hochste Humusgehalt gemessen wurde, unter Hainvege­ einer Tiefe von 5, 10 bzw. 20 cm. An den Bodenproben tation mit Quercus und Corylus. wurden Korngro.Benverteilung (Textur), Humusgehalt (Gewichtsprozent), Reaktion (pH), spezifische Leit­ 6 fahigkeit (K20 • 10 ), HCI-losliches Kalzium (mg/100 g), AI (Ammoniumlaktat)-losliches Kalium und Phosphor (mg/100 g) und Gesamtstickstoff (mg/100 g) bestimmt Bodennutzung (vgl. Rodenborg 1976, S. 19-21 und 42 ff.). - Die Er­ gebnisse der Bodenanalysen konnen folgenderma.Benzu­ In vorigen Jahrhunderten sammengefa.Bt werden. Im Archiv des Vermessungsamtes (,Lantmateristyrel­ Textur. Der Anteil feinkornigen Erdmaterials (Ton, sens arkiv") fanden sich folgende Karten beziiglich des Schluff) ist verhaltnismassig hoch. Dorfes Gosslunda:

Hu mus. Der Humusgehalt ist verhaltnismassig hoch Geometrische Vermessung, 1641 (10,0-13,8 4 Messungen in je 10 cm Tiefe); der Geometrische Vermessung (Geometrisk Charta), 1682 OJo ; hochste Wert (13,8 %) unter Hainvegetation mit Quer­ Geometrische Vermessung (Geometrisk Charta), 1738 cus Corylus. Teilung der sog, ,inagomark" (,Enskifte inago­ und a mark"), 1826 pH- Werte. Sie schwanken zwischen 5,1 und 6,9 (64 Mes­ sungen, 16 in je 0- 1 cm, 5 cm, 10 cm und 20 cm Tiefe). Aus den Karten und Beschreibungen geht hervor, da.B Die niedrigsten Werte (5,1, 5,2, 5,1 und 5,3) stammen das Dorf Gosslunda aus zwei Hofen (,hemman") be­ aus 0- 1, 5, 10 bzw. 20 cm Tiefe an einer Probestelle im stand. Die ,inagomark" der Hofe umfasste hauptsach-

Acta phytogeographica suecica 76 Das Na turschutzgebiet in Gosslunda 15

1:12 2

1:2 1:3 2. 3 3:1

11

11

18:1 3 ---- I I • -- 1 - .._ I \\ \ \�- - r 6:1 ' I I - I 3 '4-�---.-' -� - I ---

I ,' I I / _;.. - --r�:l \

../( I _ . ..,.. .,. 37:2 ,· - - - - -�· -· ,' . - - - \ �-- - 6 - · - ·- -·-·- · - · -·-· - - - - ,,;.... \ � · · ·-· ·3(2 ·-· \ ------i t-- _ _ - - - _ _ J.DL \ _ 103._2 --- A.'> I

Fig. 1. Ausschnitt aus der Katasterkarte des Dorfes Gosslunda. Das Naturschutzgebiet mit den Teilgebieten A, B, C und D ist hervorgehoben (vgl. Fig. 2).

Acta phytogeographica suecica 76 76 Lars Rodenborg

lieh Wiesen. Zwisehen den Wiesen befanden sieh zer­ SW davon abzugrenzen. Der Zweck der in Richtung N-S streute Aeker. Als Weide seheint vor allem das ,,Grosse gehenden Steinmauer, die A in einen W- und einen 0- Alvar" gedient zu haben, das allseits das Dorf umgab. Teil teilt, ist nicht ganz klar. Der N-Teil dieser Mauer hat Das ,,GroBe Alvar" war Alimende (,,utmark") (Roden­ den alten Aeker gegen 0 abgegrenzt, aber der S-Teil borg 1976, S. 53). muB einen anderen Zweck gehabt haben. Die Vegeta­ In der Besehreibung zur , , Geometrisk Charta'' 1738 tionsverhaltnisse beiderseits der Mauer geben immerhin heiBt es mit Bezug auf die Wiesen, daB die Wiese sehr gewisse Andeutungen in dieser Frage. Westlich der steinig sei und aus ,stagg oeh starr" bestehe. Das Wort Mauer hat die Vegetation, abgesehen vom alten Acker­ ,stagg", nunmehr die sehwedisehe Benennung fiir Nar­ land und einem hainartigen Streifen nordlieh davon, ei­ dus stricto, bezeichnet offenbar nicht Na rdus stricto, nen heideartigen Charakter mit dominanter Juniperus sondern moglieherweise Festuca ovina oder Carex spp. und zerstreuter Calluna; altere Laubbaume fehlen. Die Laut dieser Besehreibung nahm das Aekerland des Dor­ Gebiischvegetation ist von stacheligen, dornigen oder fes eine FHiche von ea. 31 ,Tunnland" (ea. 15 ha) ein, niedriggewachsenen Arten beherrseht. Die Vegetation die Wiesen 135 ,Tunnland" (ea. 67 ha). bier ist sieherlich wahrend langer Zeit von ziemlich in­ tensivem Weidegang gepragt worden. bstlieh der Mauer In diesem Jabrhundert hat die Vegetation einen mehr laubwiesenartigen Cha­ Die friiheren Besitzer des Grundstiiekes Gosslunda 1:3 rakter. Juniperus und Calluna treten zuriiek. Laub­ haben in den seehziger Jahren dieses Jahrhunderts fol­ baume und hochgewachsene Straueher (Quercus, Rham­ gendes iiber die Nutzung der Teilgebiete A und B berieh­ nus cathartica, Cory/us) sind unter den Lignosen domi­ tet: nierend. Hier seheint der Weidegang erheblieh schwa­ Auf dem NW-Teil von A gab es friiher einen Aeker; cher gewesen zu sein als westlieh der Mauer. In spaterer der Rest von A war Weide. Der Aeker wird seit minde­ Zeit wurden jedoeh, wie oben erwahnt, die Gebiete west­ stens 30 Jahren nieht mehr bebaut; seitdem dient er als lich und ostlieh der Mauer in demselben Umfang bewei­ Weide. Danaeh wurde A nur als Weide verwendet, fiir det, wodureh die Untersehiede verwischt wurden. Rinder und mitunter aueh fiir Pferde (diese weideten im Die bedeutenden Unterschiede in der Zusammenset­ aligemeinen auf dem ,GroBen Alvar". Sehafe weideten zung der Vegetation beiderseits der Grenzmauer zwi­ nur auf dem Alvar). Die Anzahl von Rindern war hoeh­ sehen A und B zeigen auch, daB B in spaterer Zeit Ge­ stens 8-9, von Pferden hoehstens 2. Der Weidegang genstand nur schwachen W eideganges gewesen ist. Bei fing Ende Mai an und dauerte ununterbroehen ungefahr Untersuchungen in den Jahren 1965 und 1966 war B einen Monat. Darauf waren die Tiere abweehselnd teils nicht beweidet. auf A und B (die beiden Teilgebiete bildeten dann eine GemaB den Vorschriften fiir das Naturschutzgebiet Weideeinheit; siehe unten), teils auf einem Gebiet aus­ soli anderer W eidegang als mit Rindern und Pferden serhalb des UG. Die Tiere waren ungefahr eine Woehe nieht stattfinden. Der Weidegang soli denselben Umfang an jeder Stelle. Naehts hielten sic sieh jedoeh im allge­ haben wie bisher. Nach Angabe einer Ortsbewohnerin meinen nur in A und B auf. So dauerte der Weidegang (22 Mai 1987) wird das UG jahrlich von Anfang Juli bis wahrend des Sommers und des Herbstes bis Anfang Ok­ in November von 20-25 Rindern beweidet. Pferdeweide tober. Mahd kam auf A nicht vor, abgesehen vom alten findet nicht statt. Nach Beobachtungen des Verfassers Aeker, so lange er als solcher benutzt wurde. im August 1987 weideten Sehafe auf dem UG. Wenigstens seit der Jahrhundertwende (1900) kam im 14 Teilgebiet B Weidegang vor, doeh erst naehdem ein im 0 an das Gebiet grenzender Aeker abgemaht worden war. Dieser Aeker war sicherlich sehr alt. Der Zeitpunkt der Heuernte auf diesem Acker hatte von Mittsommer bis zu Mitte Juli gewechselt. Weidegang war also auf B Vegetation friihestens zur Mittsommerzeit vorgekommen, nie im Friihsommer, im Gegensatz zu A. Der Grund dafiir daB A. Flechtenvegetation auf Silikatgestein der Weidegang auf B nieht anfing, ehe der Acker im 0 Da Silikatgestein in grosser Menge im UG vor­ abgeerntet worden war, lag darin, daB B vom Acker kommt, teils als erdfeste Blocke in epigaischer Ve­ nieht vollig abgegrenzt war. Das Vieh konnte also von B getation, teils in Mauern, ist eine reich gegliederte aus auf den Aeker gehen. Wie oben angegeben bildeten Flechtenvegetation auf diesem Substrat vorhan­ A und B eine Weideeinheit, so lange Weidegang auf B dauerte. Mahd kam auf B nieht vor. Die Verhaltnisse den. Es wird bier nur eine kurze Ubersicht iiber die waren mit aller Wahrseheinlichkeit auch vor diesem Haupttypen dieser Vegetation gegeben. J ahrhundert gleichartig gewesen. Uber diese Angaben friiherer Besitzer von Gosslunda a. Flechtenvegetation an geneigten Fliichen in son­ 1:3 hinaus mag folgendes mit Bezug auf A und B er­ niger Lage wahnt werden: die in Riehtung NW-SO dureh den W­ Dominante Arten: Rhizocarpon geographicum, Lecidea Teil von A gehende Steinmauer hat sicherlieh dazu ge­ deustata, L. fu scoatra, Aspicilia cinerea, Lecanora rupi­ dient, den oben genannten alten Acker vom Weideland co/a.

Acta phytogeograph ica suecica 76 Das Na turschutzgebiet in Gosslunda 77

Weg chen in sonniger Lage. An maBig geneigten Fla­ U • • • Wacho 1 dergebiische chen dominieren Blattflechten, an stark geneigten QQ Q Eichenwald Flachen Krustenflechten.

d. Flechtenvegetation auf kalkimpriigniertem Sili­ katgestein Kennzeichnende Arten: Lecidella stigmatea, L. scabra, Scoliosporum umbrinum, Lecanora campestris, L. ceni­ sia, L. atra, L. dispersa, L. muralis var. versico/or, Ca­ loplaca holocarpa, C. flavovirescens, Buel/ia punctata, Physcia caesia, Phaeophyscia sciastra. Auf Silikatgestein unter Kalkstein in Mauern oder sonst fiir Kalkstaub exponiert, z.B. durch kalkhaltiges W asser an Silikatblocken herabflies­ send, entsteht ein besonderer Typus von Flechten­ vegetation, die sowohl azidophil (primar) als auch I kalziphil (sekundar) ist. Die Vegetation bekommt also ein gemischtes Geprage. Auf demselben Sili­ katgestein werden nicht nur typische Arten des Sili­

100 2Q0 m katgesteins sondern auch Arten des Kalksteins an­ getroffen. Nitrophile Arten spielen bier eine her­ Fig. 2. Karte iiber das Naturschutzgebiet in Gosslunda mit einer vereinfachten Vegetationsbeschreibung. Die vortretenden RoUe. Zur Frage der Verteilung von Ziffer 1-5 bezeichnen Gebiete verschiedener Pflege in­ Flechtenarten auf Silikatgestein bzw. auf Kalkstein nerhalb des UG. siehe Rodenborg (1977, S. 51-56).

B. Vegetation auf Kalkstein ohne Bodenauflage Dominante Arten: Verrucaria nigrescens und andere Andere Arten: Rhizocarpon distinctum (Pionierart), R. Verrucaria spp., Aspicilia ca/carea, Lecanora atra, Xa n­ /ecanorinum, Lecidea fu lvella, L. tesselata, Schaereria thoria parietina. tenebrosa, Acarospora fu scata, Candelariella vite/lina. Vegetation auf Kalkstein ohne Bodenauflage Lecanora badia, L. atriseda, L. polytropa, Um bilicaria gibt es teils auf nackten Kalkfelsen, teils auf losen po/yp hylla, Bue/lia aethalea, Catillaria atomarioides. Kalksteinen in Mauern. Sie besteht hauptsachlich Die Artenzahl ist ziemlich hoch. Krustenflechten a us Krustenflechten, z. T. endolithische Arten wie dominieren, Blattflechten treten zuriick, besonders einige Verrucaria spp. Blattflechten spielen eine an stark geneigten FHichen. untergeordnete RoUe im Hinblick auf Artenzahl b. Flechtenvegetation an Horizontalf/iichen (ink/. und Deckungsgrad, im Gegensatz zum Verhaltnis schwach geneigten Fliichen) auf Silikatgestein. Nitrophile (ornithokoprophile) Dominante Arten: Lecanora macrocyclos, Parmelia /ox­ Arten sind zahlreich (Rodenborg 1977, S. 15). Hier odes, P. omphalodes, P. saxati/is, P. sulcata, P. con­ und da treten Pionierarten des Kalkfelsenrasens spersa. (Sedetum) auf wie Grimmia pulvinata und Ortho­ Die Artenzahl ist niedriger als an geneigten FHi­ trichum spp. als Folge einer schwachen Humusan­ chen. Meistens dominieren Blattflechten. reicherung. Die nitrophile Lecanora atra ist oft dominant c. Flech tenvegetation an geneigten Fliichen in und bildet ein Endstadium der Sukzession auf schattiger Lage Kalkstein in sonniger Lage in Mauern. Die stark Dominante Arten: Ochrolechia pare/la, Parmelia saxati­ lis. nitrophile Xanthoria parietina ist oftdominant an Andere Arten: Pertusaria lactea, P. dealbescens, Huilia der Oberseite von Kalksteinen am Gipfel von Mau­ tuberculosa, Lecidea lactea, Lecanora cenisia, L. atra, ern. Die gleichfalls nitrophile Aspicilia radiosa bil­ L. rupicola. det ein Endstadium in der Flechtensukzession auf Die Artenzahl ist niedriger als an geneigten FHi- Kalkfelsen.

Acta phytogeographica suecica 76 78 Lars Rodenborg

Unter den zahlreichen iibrigen Flechtenarten auf auch das W achstum zu neuem Le ben erwecken Kalkstein im VG sollen genannt werden: Placyn­ und dann folgt ein besonderer Herbstaspekt, in thium nigrum, Col/ema cristatum, C. polycarpon, dem der Boden von neuen SchoBlingen der Winter­ C. tuniforme, Dermatocarpon leptophyllum, annuellen bedeckt wird. Die Aspektfolge hier erin­ Aspicilia hoff mannii, Lecanora albescens, L. ere­ nert sehr an die der siidlichen Federgrassteppen in nu/ala, Caloplaca flavovirescens, C. holocarpa, C. der Ukraine (Waiter 1943). citrina, C. chalybaea, C. variabilis, C. a/ociza, Moose bilden meistens eine geschlossene Decke Protoblastenia rupestris, Buellia venusta, Acaro­ aus ziemlich vielen Arten, hauptsachlich Akrokar­ spora g/aucocarpa, Candelariella aurella, Acrocor­ pen. Meistens dominieren Moose iiber Flechten in dia conoidea, Verrucaria fu scel/a. der Bodenschicht; seltener haben Flechten hoheren Deckungsgrad. Unter Flechten, die Moose iiber­ C. Kalkfelsenrasen wachsen, sollen Peltigera rufescens, Cladonia fo ­ (Sedo-Scleranthetalia Br.-Bl. 55, Alysso-Sedion /iacea s.l., C. sy mphycarpa, C. pocillum, To ninia Oberd. et Th. Mull. 61, Tortello-Sedion Hallberg und Physconia muscigena gennant werden. 71 prov., Sedetum tortellosum Albertson 50) D. Flechtenreiche Alvarheide Kennarten: Poa bulbosa, Sedum album, S. acre, Ero­ phila verna, Hornungia petraea, Saxifraga tridactylites, (Festucetum alvarense cetrariosum Albertson 50) Androsace septentrionalis, Cerastium semidecandrum, Kennarten: Helianthemum oe/andicum; Cladonia jo lia­ C. pumilum, Holosteum umbellatum; Ditrichum flexi­ cea, C. macroceras, Cetraria islandica (inkl. C. ericeto­ caule, Tortula ruralis, Tortel/a spp., Racomitrium ca­ rum), C. nivalis, Coe/ocaulon aculeatum, Th amnolia nescens, Schistidium ap ocarpum, Barbula spp.; Squa­ vermicu/aris. marina cartilaginea, S. /entigera, Fu/gensia fu lgens, Gemeinsame Kennarten: fiir F.a. cetrariosum und Festu­ Physconia muscigena, Cladonia convoluta, C. fu rcata. cetum alvarense rhacomitriosum Rhytidium rugosum; Gemeinsame Kennarten fiir Sedetum tortellosum und fiir F .a. cetrariosum und A venetum alvarense Artemisia Festucetum alvarense cetrariosum: Cladonia pocillum campestris. und C. rangiformis. Diese Gesellschaft tritt auf ziemlich hoch liegen­ Gemeinsame Kennarten fiir Sedetum tortellosum und den Kalkfelsen auf, die von einer diinnen Schicht Festucetum alvarense tortellosum: Bromus hordeaceus; Verwitterungsboden und Kalkkies bedeckt sind. Cladonia symphycarpa, To ninia caereuleonigricans, Sie ist auf ziemlich grossen Flachen des SW-Teiles Fulgensia bracteata; Barbu/a spp. von A und auf B ausgebildet. Dominante oder abundante Arten: Poa bulbosa, Bro­ Die Gesellschaft ist in der Krautschicht von nie­ mus hordeaceus, Sedum album, S. acre, Arenaria serpyl­ /ifolia, Erophila verna, Hornungia petraea; Tortu/a ru­ drigwiichsigen Graminiden sowie Sedum, Helian­ ralis, Tortel/a spp., Racomitrium canescens, Schistidium themum, Thymus und Artemisia, nebst einer gros­ apocarpum, Th uidium abietinum; Cladonia symphy­ sen Anzahl von winterannuellen Arten gekenn­ carpa. zeichnet. Chamaephyten und Therophyten treten Diese Gesellschaft tritt auf ziemlich hoch liegen­ hervor. Die Bodenschicht wird im allgemeinen von dem Kalkfelsboden mit sehr geringer Bodenmach­ Strauch- und Blattflechten von vielen Arten domi­ tigkeit auf. Sie ist im SW-Teil von A und in B gut niert, wahrend Moose eine mehr untergeordnete ausgebildet. Rolle spielen. Die einzige Moosart von grosserer Pionierarten der Gesellschaft sind Grimmia pul­ Bedeutung ist Rhytidium rugosum. Die Pflanzen­ vinata, Orthotrichum anomalum, 0. cupulatum, decke ist nicht geschlossen. Pseudo/eskeella catenulata, Schistidium apocar­ Auf B gibt es von dieser Gesellschaft eine Form, pum; Psora lurida. die durch die Anwesenheit von Sedum rupestre Friihlingsephemeren, hauptsachlich Winteran­ und C/adina arbuscula mit dem Festucetum alva­ nuellen, spielen eine grosse RoUe in der Gesell­ rense rhacomitriosum (siehe unten) verbunden ist. schaft. Wahrend des Friihlings und zu Beginn des E. Saisonhygrophile Alvarheide Friihsommers tritt hier der Hohepunkt der Vegeta­ (Festucetum alvarense tortellosum Albertson 50) tionsentwicklung ein. In den meisten Jahren ver­ Kennarten: Poa alpina, Phleum pratense spp. bertolonii, dorrt oder verwelkt die Vegetation spater im Som­ Agrostis gigantea, Allium schoenoprasum, Herniaria mer. Die Regen des Spatsommers konnen aber glabra, Sagina nodosa, Artemisia rupestris, Taraxaxum

Acta phytogeographica suecica 76 Das Naturschutzgebiet in Gosslunda 79

(Palustria), Tortella tortuosa, T. jragilis, Barbulafallax; tella spp., Scorpidium turgescens; Cladonia sym­ Catapyrenium lachneum. phycarpa, To ninia caeruleonigricans, Fulgensia Gemeinsame Kennarten: fiir F.a. tortellosum und Moli­ bracteata. nietum alvarense Fissidens adianthoides. Dominante oder abundante Arten: Fes tuca ovina, Bro­ F. Vegetation der ,Aivarvatar" mus hordeaceus, Agrostis canina (inkl. A. vinealis) , A. (Agrostis stolonifera - Alopecurus geniculatus - stolonifera, Phleum pratense spp. bertolonii, Allium Scorpidium turgescens - Ass. Albertson 50) schoenoprasum, Sedum album, Aster linosyris, Crepis Kennarten: Agrostis stolonifera, Alopecurus genicula­ tectorum var. pumila; Ditrichum flexicaule, To rtel/a tor­ Ius, Juncus articulatus, J. compressus, Scirpus uniglu­ tuosa, Th uidium abietinum; Cladonia symphycarpa. mis, My osurus minimus, Ranunculus trichophyllus, Mentha arvensis, Scutellaria hastifolia, Ve ronica cate­ nata, My osotis laxa, Ga/ium palustre; Fo ntinalis antipy­ Die Gesellschaft tritt auf vorhaltnismassig tief lie­ retica, Drepanocladus sendtneri, Scorpidium turgescens. gendem Kalkfelsenboden auf. Die Kalkfelsen sind . Abundante Arten: My osurus minimus, Veronica cate­ von einer ziemlich diinnen Bodenschicht bedeckt, nata. die von grobem Kalkkies durchsetzt ist. Sie ist im SW-Teil von A gut ausgebildet. Diese Vegetation tritt in einer NW -SO - orien­ U Winterannuellen sind verhaltnismaBig sparlich. tierten Mulde im W-Teil von A auf, im bergang In der Bodenschicht dominieren Moose. Flechten von Kalkfelsboden, der schwach gegen 0 geneigt nehmen einen mehr bescheidenen Platz ein, sowohl ist, zu Wiesen- und Gebiischvegetation im 0. Die in der Artenzahl als auch im Deckungsgrad. Die Vegetation ist hygrisch und iiberwiegend wie in den Pflanzendecke ist nicht geschlossen. Ein grosser , ,Alvarvatar''. Im Sommer diirfte der Boden hier Teil der Bodenoberflache ist vegetationslos. normalerweise stark ausgetrocknet und von einer Eine mehr wiesenartige Variante von Festuce­ Schicht sog. , ,Kalkbleiche'' (ausgefalltes Ca Co3) tum alvarense tortellosum findet sich an mehreren bedeckt sein. Stellen im 0-Teil von A. Hier wachsen u.a. Briza G. Azidophile Alvarheide media, Sesleria caerulea, Carex flacca, Filipendula (Festucetum alvarense rhacomitriosum Albertson vulgaris, Veronica sp icata, Aster linosyris (zer­ 50) streut bis reichlich). Kennarten: Agrostis vinealis, Anthoxanthum odoratum, Eine saisonhygrophile Vegetation mit Ankniip­ Rumex acetosella, Sc/eranthus perennis, Dianthus del­ fung an die ,Alvarvatar" (feuchte Stellen auf dem toides, Viscaria alpina, Sedum rupestre, Trifolium ar­ vense, T. striatum, Antennaria dioeca; Dicranum scopa­ sonst trockenen Alvar) ist auf ebenen Kalkfelsen rium, Polytrichum juniperinum; Cladina arbuscula. mit diinner Bodenschicht im ziemlich niedrig gele­ Gemeinsame Kennarten: fi.ir F.a. rhacom\triosum und genen NO-Teil von A entwickelt. Diese Vegetation A venetum alvarense Orchis ustulata, Dactylorhiza sam­ diirfte eine Variante des F.a. tortellosum sein, bucina, Viscaria vulgaris, Ranunculus i/lyricus, Poten­ namlich eine sog. ,Vatheide" (Albertson 1950, S. tilla argentea.

291 ff.). Die Vatheide bildet einen Ubergang zur ei­ Dominante oder abundante Arten: Festuca ovina, gentlichen Vatvegetation. V or allem kommen vor: Agrostis vinea/is, Orchis ustulata, Scleranthus perennis, Agrostis stolonije ra (reichlich). A. canina (inkl. A. Sedum rupestre, Potenti/la argentea, Trifolium stria­ vinealis) (reichlich), A. gigantea, Phleum pratense tum; Rhytidium rugosum,· Cladina arbuscula. spp. bertolonii (reichlich), Bromus hordeaceus Diese Gesellschaft aus ziemlich azidophiler und (reichlich), Poa alpina, P. compressa, Alopecurus zugleich ausgesprochen xerophiler Vegetation ist geniculatus, Allium schoenoprasum, Rumex aceto­ vor allem im 0-Teil von A ausgebildet. Sie kommt sel/a, Hern iaria glabra, My osurus minimus, Ra­ an einigen ziemlich hoch gelegenen, plateauartigen nunculus bulbosus, Potentilla argentea, Sedum al­ Stellen mit zahlreichen erdfesten Silikatblocken bum, S. acre, Saxifraga tridactylites, Erophila vor. verna, Prune/la vulgaris, Artemisia rupestris, Die Vegetation dieses Teiles von A ist charakte­ Leontodon autumnalis, Crepis tectorum var. pu­ risiert durch ein sonderbares Gemisch azidophiler mila (reichlich), Taraxacum (Palustria); Th uidium Heidepflanzen (Rumex, Sc/eranthus, Antennaria; abietinum (reichlich), To rtula ruralis (zerstreut), Polytrichum; Cladina) und Steppenelementen (Ra­ Fissidens adianthoides, Ditrichum flexicaule, Tor- nunculus illyricus, Potentilla arenaria, Veronica

Acta phytogeographica suecica 76 80 Lars Rodenborg sp icata), sowie Orchideen. Die azidophilen Heide­ Kennarten: Phleum phleoides, Melica ciliata, A venula pflanzen diirften im allgemeinen ein seichtes Wur­ pratensis, Carex caryophyllea, C. ericetorum, Antheri­ cum li/iago, Silene nutans, Anemone pratensis, Draba zelsystem haben, was damit iibereinstimmt daB die muralis, Filipendu/a vulgaris, Fragaria viridis, Potentilla oberflachlichen Bodenschichten verhaltnismaBig tabernaemontani, Trifolium montanum, Anthyllis vul­ niedrige pH-Werte habe n, wahrend die tieferen neraria, Oxytropis campestris, Polygala vulgaris, P. co­ Horizonte, wohin das kraftiger entwickelte Wur­ mosa, Helian themum nummularium, Prune/la grandi­ zelsystem der Steppenelemente meistens reicht, f/ ora, Veronica sp icata, Globu/aria vulgaris, Galium verum, Scabiosa columbaria, Cirsium acaule, Carlina hohere pH-Werte (zirkumneutrale oder alkalische vulgaris, Hypochoeris macu/ata, Aster linosyris, Arte­ Reaktion) aufweisen diirften (vgl. Hoffmann 1959, misia oelandica. S. 106 und 110, Braun-Blanquet 1961 , S. 173 f.). Gemeinsame Kennarten: fiir Trockenrasen und meso­ O Die bereinstimmung zwischen der bier be­ phile Weiderasen A venula pubescens, Ranunculus bu/­ schriebenen Vegetation des UG und dem F.a. rha­ bosus, R. po/yanthemos, A/chemi//a glaucescens, Linum comitriosum von Albertson (1950) ist sehr gross. catharticum, Primula veris, Ga/ium borea/e, Knautia ar­ Fast alle die Arten, die Albertson als fiir diese Ass. vensis, Plantago /anceo/ata, Achillea millefolium, Chry­ santhemum leucanthemum, Centaurea jacea; Homa/o­ kennzeichnend ansah, werden bier angetroffen. thecium lutescens. Die Ursache des star ken azidophilen Einschlages Gemeinsame Kennarten: fiir Trockenrasen und xerophi­ in dieser Vegetation ist wahrscheinlich, daB die les GebiischAlli um o/eraceum, Polygonatum odoratum, Unterlage der Vegetation aus primar kalkarmen Medicago fa /cat a, Hypericum perforatum, Seseli libano­ Moranenablagerungen besteht, welche den Kalk­ tis, Galium triandrum, Centaurea scabiosa. grund iiberlagern. Solche Ablagerungen scheinen Dominante oder abundante Arten: Festuca ovina, die normale Unterlage des F .a. rhacomitriosum zu Ph/eum phleoides, A venula pratensis, Bromus hordea­ sein (Albertson 1950, S. 300 ff.). Auf das Vorkom­ ceus, Carex caryophyl/ea, Sedum acre, S. rupestre, Fili­ men solchen Moranenbodens deuten auch die zahl­ pendula vulgaris, Fragaria viridis, Potenti//a tabernae­ montani, P. argentea, Tr ifolium montanum, Medicago reichen Silikatblocke auf und in der Nahe des frag­ fa /cata, Helianthemum nummu/arium, Po/yga/a vulga­ lichen Teiles des UG hin. Die Wirkung des Mora­ ris, Geranium sanguineum, Linum catharticum, Primula nenbodens wird durch den Plateaucharakter des veris, Veronica sp icata, Ga/ium boreale, G. verum, G. Gebietes verstarkt, der verhindert, daB kalkhalti­ triandrum, Scabiosa co/umbaria, Plantago /anceo/ata, ges Bodenwasser von den Seiten her die oberflach­ Cirsium acau/e, /n u/a salicina, Aster linosyris, Artemisia oelandica; Ho malothecium lutescens. lichen Bodenschichten durchstromt. Dagegen diirfte es sich hi er, bei dem subariden Klima des Der ausgesprochen xerotherme, steppenartige ,GroBen Alvares", nicht urn eine klimatisch be­ Trockenrasen ist auf hochliegenden Kalkfelsen mit dingte V ersauerung urspriinglich kalkreichen Bo­ tieferem Boden und erdgefiillten kleinen Spalten dens handeln. im Kalkstein ausgebildet. Auf dem Kalkfelsboden Kennarten des F .a. rhacomitriosum sind, wie des SW-Teiles von A und auch auf B tritt dieser auch andere ziemlich azidophile Arten im Trockenrasen oft iiber erdgefiillten Spalten im Trockenrasen (Avenetum alvarense) auf C und D Kalkstein zwischen Sedetum und Festucetum auf vertreten. Das Festucetum alvarense diirfte sich bei den Felsflachen auf. Diese Form von Trockenrasen schwachem oder ganz beendetem Weidegang zum tritt auch im W-Teil von C und D auf. Avenetum alvarense entwickeln. Das Festucetum Der Trockenrasen in mehr mesophiler Ausbil­ ist deutlich weidebegiinstigt, wahrend das Avene­ dung (Halbtrockenrasen, maBig xerophile, step­ tum sich am besten bei schwachem Weidegang ent­ penartige Trockenwiese) ist im 0-Teil von A ausge­ wickeln diirfte. bildet, wo er an der Seite von mesophiler Wiesen­ vegetation (Ses/eria- Wiese) auftritt. Diese Form H. Trockenrasen von Trockenrasen tritt auch im ziemlich niedrig ge­ (Xerophiler und mesophiler Trockenrasen. Festu­ legenen SO-Teil von B auf; ausserdem im mittleren cetalia vallesiacae Br.-Bl. et Tx. 43, Cirsio­ Teil von D, unterbrochen von xerophilem Ge­ Brachypodion Had. et Klika 44, Festuco-Sedetalia biisch, und im mittleren Teil von C. Tx. 50 em. Krausch 61, Avenetum alvarense Al­ U nter den Gefal3pflanzen dieser Gesellschaft tre­ bertson 50) ten Annuellen und Sedum spp. meistens stark zu-

Acta phytogeographica suecica 76 Das Naturschutzgebiet in Gosslunda 81

Fig. 3. Das Naturschutzgebiet in Gosslunda. Teilgebiet B: gegen SO. lm Vordergrund Kalkfelsboden mit Sedetum. Im iibrigenFestucetum und Avenetum. Links, nahe am Acker, Fundstelle fiir Dracocephalum ruyschiana. - Photo im Sommer 1987.

riick. Statt dessen dominieren Graminiden mit Ein grosser Teil des Avenetum auf B ist wahr­ starkem Einschlag von Artemisia oelandica und scheinlich in spaterer Zeit aus Festucetum dadurch anderen perennen Krautern, oft mit kraftigem entstanden, dass kraftige perenne Graminiden und Wurzelsystem, das in die Spalten des Kalkfelsens Krauter, nachdem der Weidegang aufgehort hatte, herabdringt . Die Moose werden hauptsachlich von ganz dominant geworden sind und eine ziemlich groberen Pleurokarpen vertreten. Flechten spielen zusammenhangende Feldschicht haben bilden kon­ im allgemeinen eine unbedeutende Rolle. In der nen. Bodenschicht sind Homalothecium lutescens, Die Kennarten des Festucetum alvarense rhaco­ Th uidium abietinum und Rhytidium rugosum die mitriosum und andere ziemlich azidophile Arten bedeutendsten Arten. (Ptilidium ciliare, Barbilophozia barbata, Pleuro­ Wie aus dem oben Gesagten hervorgeht, hat der zium schreberi, Viscaria vulgaris) sind in grosse­ fragliche Vegetationstypus ein deutlich xerother­ rem oder minderem Ausmass in der ausgesprochen mes Geprage mit steppenartigen Ziigen. Ein gewis­ xerothermen Form des Trockenrasens auf C und D ser submediterraner Einschlag kommt auch vor, vertreten, was im Zusammenhang mit dem zahlrei­ wie z.B. Anthericum und Orchideen. Der Vegeta­ chen Vorkommen von erdfesten Silikatblocken in tionstypus entspricht am ehesten dem A venetum diesen Teilgebieten steht. alvarense (Albertson 1950). In der SW -Ecke von A gibt es eine weidebeein­ I. Mesophiler Weiderasen flusste Variante dieser Gesellschaft. Hier fallen be- (Mesophile Wiesenvegetation, Molinio-Arrhena­ sonders auf: Arenaria serpyllifo/ia, Alchemilla theretea Tx. 37, Arrhenatheretalia Pawl. 28) glaucescens, Sedum acre, Trifolium campestre, . Geranium molle, Draba mura/is, Satureja acinos, Kennarten: Ses/eria caerulea, Briza media, Sieglingia de­ Veronica arvensis, My osotis hisp ida, Cirsium cumbens, Cy nosurus cristatus, Calamagrostis ep igeios, Carex f/acca, Ranunculus acris, Potentilla crantzii, Me­ acaule und Hieracium pilosella. Auf die weidebe­ dicago /upulina, Trifolium pratensen, T. repens, Ononis giinstigten Annuellen soli hier besonders verwiesen hircina, Polyga/a amarella, Pimpinella saxifraga, Pru­ werden. ne/la vulgaris, Ga/ium boreale, /nu/a salicina; Plagiom-

Acta phytogeographica suecica 76 82 Lars Rodenborg nium affi ne, Th uidium philiberti, Rhytidiade/phus Wiesenvegetation und mesophiler bis hygrophiler squarrosus. Gebuschvegetation. Gemeinsame Kennarten: fiir mesophile Wiesenvegeta­ tion und hygrophile Wiesenvegetation Gymnadenia co­ L. Xerophiles Gebiisch nopsea, Scorzonera humilis, Potentilla erecta; Cteni­ (Xerophile Saum- und Gebuschvegetation; ,,Wald­ dium molluscum. steppensaum" Wendelberger 1954, Trifolio-Gera­ Gemeinsame Kennarten: fiir mesophile Wiesenvegeta­ nietea sanguinei Th. Muller 61, Origanetalia vulga­ tion und mesophile Saum- und Gebiischvegetation Or­ ris Th. Muller 61, Geranion sanguinei Tx. 60, Pru­ chis mascu/a, Veronica chamaedrys, Serratula tinctoria. netalia spinosae Tx. 52) Dominante oder abundante Arten: Sesleria caerulea, Kennarten: Allium scorodoprasum, Silene cucuba/us, Briza media, Ca/amagrostis ep igeios, Festuca ovina, Fi­ Sedum telephium, Agrimonia eupatoria, Vicia tenuifo­ lipendula vulgaris, Fragaria viridis, Potentilla erecta, /ia, Lathyrus niger, Geranium sanguineum, Ma lva a/cea, Anthy/lis vulneraria, Galium boreale, G. verum, Cir­ Viola hirta, Laserpitium latifolium, Cy nanchum vince­ sium acaule, /nu/a salicina; Homalothecium lutescens. toxicum, Lithospermum officinale, Origanum vulgare, Diese Gesellschaft kommt als Sesleria-Wiese im Dracocepha/um ruyschiana, Rosa villosa, Cotoneaster 0 von A und im SO von B vor, auch im 0 von C melanocarpus, Crataegus oxyacantha. und D. Als Sesleria - Wiese ist sie auBerdem, un­ Gemeinsame Kennarten: fiir xerophiles Gebiisch und terbrochen von entsprechender Gebuschvegeta­ mesophiles Gebiisch Tr ifo lium medium, Campanula tion, im W von A ausgebildet. Als Calamagrostis persicifolia, Prunus spinosa, Rosa duma/is, R. canina (inkl. R. obtusifolia), Rhamnus cathartica. epigeios - Wiese kommt die Gesellschaft im 0 von D vor, zusammen mit Sesleria-Wiese und me­ Dominante oder abundante Arten: Geranium sangui­ neum, Vicia tenuifolia. sophiler Gebuschvegetation. Die Vegetation auf dem ehemaligen Acker im Diese komplexe Vegetation (Saum und Gebusch) NW von A hat ein stark gemischtes Geprage, von ist am besten in A und D ausgebildet. Sie tritt im massig xerophilen zu schwach hygrophilen Ein­ N bis NW von A und nahe an der Alvarmauer von schlagen (Uberbleibsel eines Pionierstadiums). So D auf, ausserdem bei Silikatblocken im zentralen kommen z.B. A venula pratensis, Orchis ustulata. Teil von D. Als Bestandteil von Karstvegetation, Filipendula vulgaris, Fragaria viridis, Trifolium zusammen mit einigen Hainpflanzen, ist sie in montanum, Galium triandrum zusammen mit Sa­ Spalten des Kalksteins im SW-Teil von A und in B gina nodosa, Ranunculus acris, Geum rivale, Po­ zu finden. tentilla erecta, Hieracium auricula und Calliergo­ Auf dem mittleren Teil des nur schwach bewei­ nella cuspidata vor. Die Vegetation hat jedoch deten D tendiert der Trockenrasen in mehr meso­ uberwiegend den Charakter von mesophiler, stark philer Ausbildung (Halbtrockenrasen) dazu, in kulturbeinflusster Weidevegetation. xerophile Saum- und Gebuschvegetation uberzu­ gehen. Ein guter Indikator dafur ist das reichliche K. Feuchtwiesenvegetation Vorkommen von Geranium sanguineum. (Molinio-Arrhenatheretea Tx. 37, Molinietalia W. M. Mesophiles Gebiisch Koch 26, Molinion W. Koch 26, Molinietum alva­ (Mesophile Saum- und Gebuschvegetation; rense Albertson 50) Trifolio-Geranietea sanguinei Th. Muller 61, Ori­ Kennarten: Molinia caerulea, Carex panicea, C. hos­ ganetalia vulgaris Th . Muller 61, Trifolion medii tiana, Platanthera bifolia, Listera ovata, Geum rivale, Th. Muller 61, Prunetalia spinosae Tx . 52) Viola pumila, Primula fa rinosa, Succisa pratensis, Hie­ racium auricula; Drepanocladus revo/vens. Kennarten: Rubus saxatilis, Lathyrus pratensis, Vicia cracca, Viola canina, V. riviniana, Hypericum hirsutum, Gemeinsame Kennarten: fiir Feuchtwiesenvegetation Anthriscus sy lvestris, Calluna vulgaris, Hieracium um­ und Feuchtgebiisch Calliergonella cuspidata, Campy­ bellatum, Ju niperus communis, Pinus sy lvestris; Rhyti­ lium e/odes, C. protensum. diade/phus triquetrus, Hy /ocomium sp lendens. Dominante Arten: Ses/eria caeru/ea, /nu/a salicina. Gemeinsame Kennarten: fiir mesophiles Gebiisch und Diese Gesellschaft ist nur fragmentarisch und in Feuchtgebiisch Potentilla fr uticosa, Rosa majalis. schwach hygrophiler Form vertreten. Sie tritt im Dominante oder abundante Arten: Ju niperus commu­ W-Teil von A auf, im Wechsel mit mesophiler nis, Potentilla fr uticosa, Rosa majalis, Prunus sp inosa,

Acta phytogeographica suecica 76 Das Naturschutzgebiet in Gosslunda 83

Fig. Das Naturschutzgebiet in Gosslunda. Teilgebiet D: gegen W. Nunmehr sehr schwach beweidet. Im 4. Hintergrund rechts grosser Silikatblock, von xerophilem Gebiisch umgeben. Im iibrigen Avenetum, das in xerophile Saum- und Gebiischvegetation iibergeht. - Photo im Sommer 1987.

Rubus saxatilis; Rhytidiade/phus triquetrus, Hy loco­ vereinzelten Ex. als Schosslinge oder kleine Baume mium sp lendens. auf. Potentillafruticosa bildet dichte und hohe Be­ Die Gesellschaft ist im W und 0 von A und im stande. 0 von D, im Wechsel mit mesophiler Wiesenvege­ In der Bodenschicht wachsen Calliergonella cus­ tation (mesophilem Wiederasen), ausgebildet. pidata, Campylium elodes, C. protensum, Bra­ Es gibt in dieser Gesellschaft eine Baumschicht, chythecium mildeanum, B. salebrosum, Rhytidia­ die jedoch nur schwach entwickelt ist. Sie besteht delphus triquetrus. aus zerstreuten, jungen Ex. von Pinus sy lvestris 0. Meso-hygrophiler Gebiischwald und Quercus robur. (Querco-Fagetea Br .-Bl. et Vlieger 37, Prunetalia spinosae Tx. 52, Fagetalia sylvaticae Pawl. 28) N. Feuchtgebiisch Kennarten: Ulmus minor, Fraxinus exce/sior, Cornus (Hygrophile Saum- und Gebiischvegetation) sanguinea, Euonymus europaeus, Rhamnus frangu/a, Kennarten: Brachypodium pinnatum, Carex tomentosa, Viburnum op u/us, Rubus caesius, Ranunculus aurico­ Filipendula u/maria, Viola elatior, Cnidium dubium, Sa­ mus, Glechoma hederacea; Mn ium undulatum, Eurhyn­ lix rosmarinifolia; Brachythecium salebrosum. chium praelongum. Gemeinsame Kennarten: fiir Feuchtgebiisch und meso­ Gemeinsame Kennarten: fiir meso-hygrophilen Ge­ hygrophilen Gebiischwald Va /eriana officina/is; Bra­ biischwald und Hainvegetation Quercus robur, Geum chythecium mildeanum. urbanum.

Dominante oder abundante Arten: Potentilla fr uticosa, Dominante oder abundante Arten: Ulm us minor, Juniperus communis, Brachypodium pinnatum, Carex Fraxinus excelsior, Cornus sanguinea, Brachypodium tomentosa, /nu/a salicina. pinnatum, Anemone hepatica, G/echoma hederacea. Niedrig gelegenes GeUinde mit ziemlich tiefem Der Gebiischwald hat ein mesophiles bis Boden wird zum grossten Teil von Feuchtgebii­ schwach hygrophiles Geprage. Er ist nahe an der schen eingenommen, vor allem im ostlichen Teil Alvarmauer im N bis NW von A ausgebildet. In des UG. Im W von A gibt es Gebiischvon schwach der Baumschicht gibt es zahlreiche Ex. von Ulmus hygrophilem Charakter. minor und zerstreute von Quercus robur. Quercus robur und Fraxinus excelsior treten in In der Bodenschicht wachsen Rhytidiadelphus

Acta phytogeographica suecica 76 84 Lars Rodenborg triquetrus, Th uidium philiberti, Brachythecium Mercurialis perennis, Geum urbanum und Rhodo­ mildeanum, Campylium protensum, Mn ium undu­ bryum roseum. Die andere Gruppe bestebt aus Ar­ latum, Eurhynchium praelongum. ten der xerophilen Saum- und Gebiischvegetation. Eine scbwacb bygriscbe Variante des Gebiiscb­ Fiir beide diese Gruppen gewahren die Karstspal­ waldes ist sicberlicb in spater Zeit durcb abneb­ ten geeignete Bedingungen (vgl. Albertson 1950, S. menden Kultureinflul3 aus niedrigen Gebiiscben 320 ff.). von bauptsacblicb Potentilia fr uticosa und Junipe­ rus mit vereinzelten Ex. von Quercus robur ent­ standen. Ein auffallender Aspekt der jetzigen Ve­ getationsentwicklung ist die kraftige Verbreitung Floristische Anmerkungen von Fraxinus. Diese Baumart ist nur in jungen Ex. vertreten und diirftealso bier friiber gefeblt baben, Rumex acetosella vermutlicb aufgrund des intensiveren Weidegan­ Diese Art kommt im UG, wie erwahnt, teils in ges. Escbenblatter werden namlicb von den Weide­ mal3ig azidopbiler und zugleich ausgesprochen tieren mit Vorliel3e gefressen. xerophiler Vegetation, teils in der saisonhygropbi­ len Vegetation mit Ankniipfung an die ,Alvarva­ Hainvegetation P. tar" vor, die auf niedrig liegenden, ebenen Kalk­ (Querco-Fagetea Br.-Bl. et Vlieger 37, Fagetalia felsen mit diinner Bodenschicht ausgebildet ist. Im sylvaticae Pawl. 28) letztgenannten Vegetationstypus wird R. acetosella Kennarten: Corylus avellana, Gagea lutea, Conva/laria auf ziemlicb offenem Kalkboden angetroffen, zu­ majalis, Anemone hepatica, A. nemorosa, A. ranuncu­ sammen mit u.a. Allium schoenoprasum, Hernia­ loides, Mercurialisperenn is, Viola mirabilis, V. reichen­ bachiana. ria glabra, Sedum album, Aster linosyris, Artemi­ sia rupestris, Taraxacum (Palustria) und in der Bo­ Dominante oder abundante Arten: Mercurialis perennis, Anemone hepatica, A. nemorosa, A. ranunculoides, Ga­ denscbicht Cladonia symphycarpa, Fulgensia brac­ gea lutea, Convallaria majalis. teata (vgl. Sterner 1938, S. 91, Braun-Blanquet Diese Vegetation nimmt ein ziemlicb kleines Ge­ 1961, S. 193-195, Krauscb 1961, S. 195). biet im N von A ein. Die Baum- und Straucb­ Helianthemum oelandicum scbicbt werden vor allem von Quercus robur bzw. Diese Art scheint eine ziemlich weite okologische Corylus avellana gekennzeicbnet. Einige Hain­ Amplitude im UG zu haben. Aul3er in Festucetum­ pflanzen wie Mercurialis perennis und Geum urba­ Gesellschaften wird sie ziemlich reichlich in xero­ num sind aucb in Karstspalten im W des UG zu philer und mesophiler Wiesenvegetation (Avene­ finden. tum und Sesleria-Wiese) angetroffen. H. oelandi­ cum wird aber auch an mehreren Stellen in Vegeta­ Q. Vegetation in Karstspalten tion mit Einscblagen von hygropbilen Arten ange­ In Karstspalten von B und den angrenzenden Tei­ troffen. Dort wacbst die Art zusammen mit z.B. len von A werden u.a. folgende Arten angetroffen: Sesleria caerulea und Carex panicea. Juniperus communis, Prunus sp inosa, Rosa vil­ Betreffs der Standorte der Art siebe Sterner 1936 losa, R. dumalis, R. canina, Cotoneaster melano­ und 1938. Bei Sterner 1936, S. 198 gibt es iibrigens carpus, Cornus sanguinea, Anthericum liliago, Po­ eine Analyse einer Probeflacbe mit , , Cetraria is­ lygonatum odoratum, Melica ci/iata, Urtica landica - Helianthemum oelandicum Heide'' dioeca, Corydalis pumila, Geum urbanum, Gera­ - aus Gosslunda (am Rande des Alvars gleich west­ nium sanguineum, G. robertianum, Viola hirta, licb des Dorfes). Von der Artenzusammensetzung Seseli libanotis, Mercurialis perennis, Cy nanchum zu urteilen (u.a. Anthericum liliago) diirfte die vincetoxicum, Lithospermum officinale, Galium Probeflache im SW-Teil des UG gelegen gewesen boreale; Rhodobryum roseum. sein. Zwei okologiscbe Gruppen konnen bier unter­ schieden werden. Die eine Gruppe bestebt aus Ar­ Viola elatior ten, dir vor allem in Hainvegetation oder iiber­ Im UG wacbst V. elatior in scbwach hygropbiler baupt in Waldvegetation zu Hause sind, namlicb Gebiischvegetation und in damit nahe verwandter

Acta phytogeographica suecica 76 Das Naturschutzgebiet in Gosslunda 85

Hainvegetation. Dazu kommt eine Fundstelle in ei­ charakteristischer Graminide. In der Gehiischvege­ nem alten Grahen und eine in einer wahrscheinlich tation treten ausser Prunus sp inosa z.B. folgende natiirlichen Niederung (Bachhett) mit okologi­ Arten auf: Rosa dumalis (zerstreut), R. canina, Ju­ schen VerhiHtnissen, die denen in der genannten niperus communis, Potentilla fruticosa, Crataegus Gehiisch- und Hainvegetation ahnlich sind. An spp., Euonymus europaeus, Corylus avellana, Ru­ diesen Standorten wird die Art angetroffen zusam­ bus caesius, und in der Krautschicht (Saumvegeta­ men mit z.B. Potentilla fruticosa, Juniperus com­ tion) Calamagrostis ep igeios, Thalictrum simplex, munis, Prunus sp inosa, Cornus sanguinea, Bra­ Agrimonia eupatoria, Serratula tinctoria (zerstreut chypodium pinnatum (dom. in der Feldschicht), his reichlich). In ula salicina (reichlich). Rhytidium rugosum V. elatior ist also im UG, mit der angegehenen Diese als stark kalkhegiinstigt angesehene Moosart Ausnahme, auf Gehiisch- und Hainvegetation he­ (Alhertson 1946, S. 184 ff. , und dort angefiihrte schrankt, wo sie im Schutze verschiedener Ligno­ Lit�ratur) wachst im UG oft in ziemlich azidophi­ sen wachst. Ausserhalh solcher Gehiete wiirde sie ler Umgehung, z.B. an Silikathlocken zusammen sicherlich von den Weidetieren ahgeweidet werden. mit Dicranum scoparium und Hy locomium sp len­ Am Rande der Gehiische werden die hervorstehen­ dens. Sie tritt also, wie erwahnt, reichlich und do­ den Triehe nach und nach ahgehissen. Sie scheint minant in Vegetation von etwas azidophilem und also weideempfindlich zu sein. zugleich ausgesprochen xerophilem Charakter auf. V. elatior hei Gosslunda wird schon im Jahre Vgl. Alhertson (1950, S. 307), Rodenhorg (1965), 1850 in der von M.G. Sjostrand herausgegehenen Gams (1927, S. 632 ff.), Schmid (1936, S. 91 ff. Arheit , ,Enumeratio plantarum in Olandia sponte und 159 ff.). nascentium" angegehen (Sterner 1938, S. 129). Be­ ziiglich der Standortsamplitude und der Verhrei­ tung der Art wird auf Sterner (1922, S. 359 f. und 404) verwiesen. Vgl. auch Hulten (1950) und Oher­ Summary dorfer (1962, S. 624) . During the years 1966-1968 the author investigated the Dracocephalum ruyschiana flora and vegetation within an area of approximately 11 Das UG ist der einzige Fundort fiir die Art auf ha ("UG"), which consists of infields belonging to the small village of Gosslunda, situated in the central part of bland. Zur Entdeckungsgeschichte und zum Vor­ the Great Alvar (Stora Alvaret) of the island of bland in kommen der Art im UG siehe Rodenhorg (1968, S. the Baltic. This area was declared a nature reserve in 257-262). Zwei Fundstellen im UG sind his jetzt 1972 and the investigation of the UG was continued. The hekannt. Die eine, deren Vegetation in der genann­ main results of the investigation are presented in the pa­ ten Arheit naher heschriehen ist, liegt am 0-Rande per. The UG borders in the N and W to the Great Alvar, von B; die andere, die spater entdeckt wurde, liegt in the E and S to other infields of the village of Goss­ im mittleren Teil von D in xerophiler Gehiischvege­ lunda. For the purpose of investigation it is divided into tation. Trotz Nachforschungen wurde die Art we­ four main parts, designated A, B, C and D. These parts der 1986 noch 1987 gefunden. Die heiden Fundstel­ belong to different farms of the village or have been used len sind nunmehr nur schwach heweidet. Die Ursa­ in different ways. The entire UG area and each of the four parts are delimited by stone walls. Part A, which is che des (scheinharen?) Verschwindens der Art ist considerably larger than the others, is subdivided into unklar. three areas, also delimited by stone walls. The UG slopes gently towards the E. The bedrock Prunus spinosa consists of limestone that, in several places, mainly in Auf dem 0-Teil von A hildet diese Art wegen der the SW, lacks a cover of earth or is covered by only a nur schwachen Beweidung des Gehietes ausge­ thin layer. Karst formations of the limestone also occur dehnte, lichte oder dichte Gehiische. Sie ist meis­ in the SW. Deeper soils are found in the N and the E part tens dominant in der iiherwiegend mesophilen Ge­ of the UG. Numerous siliceous boulders and stones, with their hiischvegetation dieses Teiles von A. Diese Vegeta­ bases embedded in the soil, are scattered over the area, tion grenzt hauptsachlich an mesophile Sesleria­ mainly in C and D, which are situated in the SW of the Wiese mit, ausser Sesleria, auch Briza media als UG. The stone walls have both calcareous and siliceous

Acta phytogeographica suecica 76 86 Lars Rodenborg

components. In some places there are fairly deep depres­ - 1950. Das grosse siidliche Alvar der lnsel Oland. - sions in the ground, natural or man-made. Svensk bot. Tidskr. 44 : 269-331. Soil samples were collected in the UG on the 6 July Braun-Blanquet, J ., 1961. Die inneralpine Trockenvege­ 1973 from 16 different sites; near the surface (0-1 cm tation. - Geobot. selecta 1 : 1-27 3. deep) and from depths of 5, 10 and 20 cm. The samples Corley, M. F. V., Crundwell, A. C., Dull, R., Hill, were analyzed with respect to texture, humus, pH, speci­ M. 0. & Smith, A. J. E. 1981. Mosses of Europe fic conductivity, HCl-soluble calcium, potassium and and the Azores; an annotated list of species, with sy­ phosphorus (using the ammonium lactate method), and nonyms from the recent literature. - J. Bryol. 11: total nitrogen. The humus content is relatively high 609-689. (10.0-13.8 Ofo ; 4 samples). The pH values vary from 5.1 Gams, H., 1927. Von den Follateres zur Dent de Morc­ to 6.9 (64 samples); the vertical amplitude is often very les. - Beitr. geobot. Landesaufn. Schweiz 15: small (0.2 or only 0.1). Specific conductivity (16 1-760. 6 samples) varies from 40 to 100 (K20 • 10 ) and is thus Grolle, R., 1983. Hepatics of Europe including the Azo­ fairly low. The calcium levels range from 520 to 880 res; an annotated list of species, with synonyms from mg/100 g (4 samples), and those for potassium and the recent literature. - J. Bryol. 12: 403-459. phosphorus range from 5 to 16 mg/100 g (16 samples) Hofmann, G., 1959. Die Walder des Meininger Mu­ and 0.9 to 1.2 mg/100 g (16 samples). Total nitrogen schelkalkgebietes.- Feddes Repertorium, Beih. 138. ranges from 461 to 687 mg/1 00 g (4 samples). Hulten, E., 1950, 1971. Atlas over vaxternas utbredning Knowledge of the land use of the UG in ancient times i Norden. - Stockholm. could be compiled from four land-surveyors' maps of Hylander, N., 1953-1966. Nordisk karlvaxtflora 1-11.

Gosslunda village, dating from 1641, 1682, 1738 and - Lund. 1820. The maps indicate that the infields of the village - 1955. Forteckning over Nordens vaxter 1. Karlvax- were then mainly meadow-land with scattered arable ter. - Lund. 175 pp. fields. Krausch, H.-D., 1961. Die kontinentalen Steppenrasen In the 20th century the UG has not been used as mea­ (Festucetalia vallesiacae) in Brandenburg. - Feddes dow but mainly as pasture. The grazing animals were Repertorium, Beih. 139. cattle and sometimes horses (not sheep since they were Oberdorfer, E., 1962, 1970. Pflanzensoziologische Ex­ used to graze on the Great Alvar). The horses also gener­ kursionflora fiir Siiddeutschland und die angrenzen­ ally grazed on the Alvar. The pasture period began in den Gebiete. - Stuttgart. 987 pp. late May and lasted until early October. Grazing did not Rodenborg, L., 1965. Ny lokal pa Falbygden for Stipa take place uniformly throughout the entire UG area; the pennata. - Svensk bot. Tidskr. 59: 381-386. pasture period on A, for instance, began about a month - 1968. Dracocephalum ruyschiana L. aterfunnen pa earlier than on B. The differences in pasture period be­ Oland. - Svensk bot. Tidskr. 62: 257-262. tween various parts of the UG are reflected in corre­ - 1976. Bodennutzung, Pflanzenwelt und ihre Veran­ sponding differences in the present-day composition of derungen in einem alten Weidegebiet auf Mittel­ vegetation. oland, Schweden. - Vaxtekol. Stud. 7: 1-210. The epigeic vegetation as a whole has been described - 1977. Epilithische Vegetation in einem alten Weide­ and divided into 13 vegetational units (communities of a gebiet auf Mitteloland, Schweden. - Bibliotheca Li­ local character). The communities are distinguished by chenologica 8: 1-108. locally characteristic species. Dominant or abundant Santesson, R., 1984. The Lichens of Sweden and Nor­ species are added for each community. The epilithic ve­ way. - Stockholm. 333 pp. getation has been roughly divided into two major units: Schmid, E., 1936. Die Reliktfohrenwalder der Alpen. ­ vegetation on siliceous boulders (consisting of lichens Beitr. geobot. Landesaufn. Schweiz 21: 1-190. only) and vegetation on calcareous rocks and boulders. Sterner, R., 1922. The continental element in the flora of Some interesting species from ecological or plant geo­ South Sweden. - Geogr. Annr. 4: 221-444. graphical points of view have been briefly commented; - 1936. Ekologiska iakttagelser over Helianthemum inter alia Dracocephalum ruyschiana, which on Oland is oelandicum (L.) Willd. - Acta Horti gotoburg. 11: known only from the UG, where it had been found on 183-208. two places in the SW, in xerophytic fringe vegetation, - 1938. Flora der lnsel Oland. - Acta phytogeogr. but was not re-found in 1986 and 1987. suec. 9: 1-169. - 1948. Olands flora. - Oland I. Lund. pp. 89-235. Tutin, T. G. et al. 1964-1980. Flora Europaea, 1-5. - Cambridge. Waiter, H., 1943. Die Vegetation Osteuropas. 2. Aufl. - Berlin. 180 pp. Literaturverzeichnis

Albertson, N., 1946. Osterplana hed, ett alvaromnlde pa Kinnekulle. - Acta phytogeogr. suec. 20: 1-267.

Acta phytogeographica suecica 76 Shrub expansion in alvar grasslands on bland Ejvind Rosen

Abstract Rosen, E. 1988. Shrub expansion in alvar grasslands on Oland. -Acta phytogeogr. suec. 76, Uppsala. ISBN 91-7210-076-1.

Nature conservation research was carried out in the limestone grasslands of 'Stora Alvaret' on the island of Oland in the Baltic. Expansion of Juniperus communis as a consequence of decreasing cultural influence is also being studied. A total survey of the shrub and tree expan­ sion in Stora Alvaret was made. Examples of a map compiled are given. Expansion mainly takes place in areas with fairly deep silicious soils, e.g. on old beach-ridges, but also in fissures in the limestone bedrock. Permanent plots (4 m) established in a dense Juniperus communis scrub (mean age 79 x 4 yrs, canopy cover 95-100"lo ) were cut and regeneration of the field layer was recorded (1983-87). Grassland species appeared in the plots probably originating from a seed bank in the soil. A successful transplantation experiment was carried out (1983-87) with Oxytropis campestris, Pulsatilla pratensis and Orchis mascula. Nature conservation aspects are discussed with suggestions for management.

Key words: Juniperus scrub, permanent plots, transplantation experiment, regeneration, regional mapping, nature conservation, management.

Ej vind Rosen, Institute of Ecological Botany, Box Up psala, Sweden. 559, 75 1 22

Introduction munities due to the variation of soils and moisture. A comprehensive classification was made by Albertson The so-called 'Stora Alvaret' in the southern part of the (1950) and a modernized one by Krahulec et (1986). al. limestone island of bland (in the Baltic) is a large grass­ The climate situation on the Alvar becomes extremely land area. It forms a plateau of the Ordovician sedimen­ pronounced considering its thin soils. The influence tation period covered with the weathering calcareous from the Baltic creates a local maritime temperature soils and scattered gravelly deposits in the shape of lit­ climate on bland (Angstrom 1974). July is the warmest toral material. month with 16-17°C and February the coldest with The area is about 300 km2• According to Enckell et mean values for the whole island between -2°C and al. (1979) weathered deposits cover 54 of the area, -1 (Angstrom 1953). West and southwesterly winds OJo oc gravelly deposits 26 fens and wet meadows 18 and predominate throughout the year. The precipitation OJo, OJo about 1 is made up of karst areas with bare rock. Fur­ brought from the Atlantic ocean is mainly deposited OJo ther information on geology and soils is found in Ko­ over the Southern Swedish highlands, leaving only small nigsson (1968) and Rosen (1982). amounts for the SE coast and bland. Mean precipitation The flora is very rich due to the mosaic structure of for the Alvar is 437 mm (1965-84) according to the landscape. Several taxa have their main distribution Krahulec et (1986), with a wide variation between al. in other parts of Europe or in Asia, but are found as out­ years but also within years. For a comprehensive review posts or disjunct occurrences on bland. There are, of climate see Rosen (1982). e.g. SW-European, S- and SE-European, Continental/ The Stora Alvaret area has been grazed by cattle, Siberian and Arctic/Montane floral elements. Several sheep and horses for several thousands of years, but with taxa on subspecies or variety level are considered as varying intensity (Konigsson 1968). The vegetation on endemic to bland-in some cases shared with Gotland, weathering soils may be considered more or less as the other big Swedish limestone island in the Baltic. natural grassland while that on littoral deposits is semi­ More information is found in Sterner (1948, 1986), natural as it has been kept open by wood-cutting and Rosen (1982), Ekstam et al. (1984) and Bengtsson et al. grazing. (1988). The alvar vegetation includes several plant corn- In the last century the island became overpopulated

Acta phytogeographica suecica 76 88 Ej vind Rosen

and large areas were overgrazed, including the Alvar. 30 OJo ). Two of the dense plots were "fenced" During the big emigration period (1881-1910) almost (with the stems of the cut junipers) to prevent graz­ one-third of the inhabitants (around 13.000) left the ing (Nos. 2 a d 3), while the third plot (No. 1) was island for North America. After the drop in grazing � pressure and wood-cutting which followed, shrubs and located where it could be reached by cattle from trees started to regenerate and expand on deeper soils some glades in the scrub. The edge plot (No. 4) was and in fissures. This process is still going on (cf. Rosen open to grazing as well. 1982). In October 1983 three species were introduced by transplantation into the dense plots Nos. 1 and In 1983 the project: "Plant geographical and land­ 2. These species, Pulsatilla pratensis (5 in­ scape ecological planning of reserves for species dividuals), Orchis mascula (5) and Oxytropis and vegetation types-with emphasis on Oland's campestris (10) for each plot, were moved (to­ alvar landscape" was started with financial sup­ gether with a little soil) from the nearby open port from the National Swedish Environment Pro­ grassland. To the edge plot (No. 4) only Orchis tection Board. The project included a differen­ mascula (10) was transplanted as the other two tiated research on Juniperus communis. Establish­ species were already present. As a control, 5 in­ ment and growth of junipers has been reported in dividuals of each species were dug up in the Rosen (1982, 1985, 1987 and 1988). Correlation grassland and replanted a few decimeters away. All measurements between field layer diversity and species were marked with a small plastic peg. The cover of juniper shrubs show a drastic drop of third dense plot (No. 3) was untreated (and alvar plants especially in places where the juniper ungrazed). Into each of the two plots (Nos. 1 and cover is > 75 OJo . On the other hand, shrub- and 2) seeds of Pulsatilla pratensis (40), Oxytropis woodland species increase in number (Rejmanek & campestris (300) and Orchis mascula (high num­ Rosen 1988). Inventories inside junipers show that ber) were sown into small parcels, 60 60 cm re­ x there is correlation between plant cover and size spectively. and shape of the shrubs (Rosen & Sjogren 1988). The establishment and survival of these in­ Aims of the study: troduced species was recorded each year together (1) To trace a regeneration of alvar vegetation with other species in the plots. Also the total cover from a seedbank in the soil when a very dense of mosses, phanerogams and shrubs was recorded. juniper scrub is cut down. The fenced plots have only been visited a few times each year to avoid introduction of seeds. What is (2) To test the reintroduction of some alvar brought in by birds and hares cannot be con­ meadow species into a former scrub area by trolled, but may become of some importance after transplantation from nearby areas. a few years-the animals being attracted to the (3) To map the present distribution of juniper green open plots. In 1985 numerous sprouts of vegetation and stands of deciduous and coniferous Rosa dumalis and R. sp., Berberis vulgaris and trees in the Stora Alvaret. Prunus sp inosa were found in the plots. They were cut down in the autumn, in order to avoid interfer­ ing too much with the development of the field layer. Methods

Transplantation and regeneration Presence and absence of species was recorded in In order to find answers to the first two questions the plots during 1983-87. In the fenced and a very dense juniper scrub was chosen in the alvar ungrazed plot No. 3 also the cover of each taxon of Drostorp. Three plots (4 4 m) were cut out was recorded. In order to make the counts more x by chain-saw (October 1983) in the densest parts of accurate the plot was divided into four sub-plots. the scrub (cover of the Juniperus canopy between The five degree cover scale by Hult-Sernander-Du 95 and 100 OJo ). Some shrubs of Prunus sp inosa Rietz was used. The nomenclature of phanerogams were present in all plots. A fourth plot was opened follows Tutin et al . (1964-80). at the edge of the scrub (Juniperus cover about

Acta phytogeographica suecica 76 Shrub expansion in a/var grasslands on Oland 89

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:o · ·. 0 ? ·. 2:..� ...... �- ...... " • . .. • · . ·�o ·-' , , . • e e ; I � o • • • e • • !• o ··· o'' �o o . :,. "' ! . 0;( !�· .. . . 0�· � 0 ' ··: ;�. . . . . · · . • . . ..;,. . : . . � • • . � .· ..·P. · -:· . •·a�··· . . '0: " . ·: . .... · •• . • · 0::;• . .. . • • •• •• o,': ' · ; ' . o·.:': • . . .·• 'p)o:�'O�� • ·• ..• . �·;�:· •••-�: .. . · . . ·: ··��-- . . . . . · ...... � :· ...... • ��· . · �··· . ,.. ..� . . . 1 · • ••• •.• .•• . • : · ::.. ·. . :=- 0 -� / .: : . · : : ·.· . · . . -��� . ... · :'b . . . .· .· . . . • • . . . · . · ..:_:�. ."!-' • . .. Fig. 1. The map shows the distribution of shrubs and trees in the NE part of Stora Alvaret (1985 edition). Three classes are used to show the cover of the junipers. A small dot corresponds to a juniper cover of 25-49 within OJo an area of 25 25 m. A large dot means 5Q-74 and a larger black area �75 cover. Rings mark stands of x Ofo Ofo deciduous trees and crosses mark conifers. The straight lines are stone walls or fences which separate the different grazing units. Hatched areas represent fields.

Acta phytogeographica suecica 76 90 Ej vind R osen

Mapping of shrub and tree vegetation Table 1. Transp lantation and sowing experiment in cut permanent plots, situated within a dense juniper Black and white aerial photographs (1:20.000) scrub, and control plots (1983- 87) . Juniper cover (%) were used in combination with maps (1:10.000) and mean juniper age (years) in each plot are shown. Three species were transplanted (in plots no. 1, 2, 4 and field trips to produce a map mainly for the and control) and sown (in plots no . 1 and 2) in Octo­ ber 1983. Recordings in May- (June) each year. Num­ Juniperus vegetation in Stora Alvaret. At a late ber of flowers within brackets for surviving plants stage some minor corrections were made with in­ (1984- 87) . (5+2) indicates 5 old and 2 new flowering individuals . x means treated . Plot no . 3 was an un­ formation from infra-red photographs (1 :30.000). treated control plot within the scrub. Three classes of cover were used for the juniper vegetation: 25-50 %, 50-75 C1Jo and 75-100 CJfo Plot number 2 4 control ------(see Fig. 1). The cover was estimated over areas ap­ Cover 95- 100 95- 100 30 proximately 25 25 m. Small woods or groups of 78 79 56 x Mean age trees were marked, as well as scattered trees if there Grazed X X X were more than three individuals within a radius of Planted X X X X Sown about 25 m. A stereoscope instrument was used to X X examine structures on the photographs and a large Pulsatilla 1983 5( ?) 5( ?) 5( ?) number of slides from the area was used as an ad­ pratensis 1984 5(3) 5(2) 5(0) (plants) 1985 4( 0) 4( 1) 5( O) ditional aid. 1986 4( 0) 4( 1) 5( 0) 1987 4( 0) 4( 1 +1) 5(0)

1983 10( ?) 0(?) 5( ?) Oxytropis 1 campestris 1984 9(0) 7( 1) 5( 0) 1985 8( 5) 6( 1) 4(4) Results 1986 7(7) 4( 2) 4(4) 1987 6( 6) 4( 4) 4( 3) Transplantation (Table 1) Orchis 1983 5( 5) 5( 5) 10( 10) 5( 5) Pulsatilla became very influenced by frost heavings mascula 1984 5( 3) 5(2) 1 0( 9) 5( 3) 1985 5( 2) 5( 5) 1 0(7) 4(4) in winter and in spring 1984, both in plot nos. 1 1) 1986 5( 1) 5( 5+2) 8( 5 + 4( 4) and 2, as there was no sheltering plant cover. How­ 1987 2(0) 5(5+3) 8( 4+2) 4( 2) ever, all plants survived and some of them also got Pulsatilla 1984 - 6 pratensis 1985 7 flowers (3 and 2). In 1985 vigorous growth took (from seeds) 1986 8 place in the plots, both from seeds in the cleared 1987 7 plot and from seeds in the soil which was brought in with the plants. One individual of Pulsatilla disappeared in each of these two plots, probably as grandif/ora are competitive species, being in­ a result of competition for space and light. Four troduced with the soil brought in together with individuals were still alive in each of these plots in Oxytropis. In the control area, 1 Oxytropis died in 1987, but conditions were less favourable in plot 1985, probably due to drought aggravated by cattle no. 2 as Potentilla was extremely overgrown by trampling around the plant. In all plots there has other species, e.g. Plantago lanceolata. Potentilla been a high flowering frequency since 1986. managed somewhat better in the weakly grazed The number of leaves and branching on each in­ plot 1. In the control plantation all individuals sur­ dividual clearly increased over time for Oxytropis vived until 1987, but for some reason none in plot 1, which was not the case in plot 2. The flowered. range is 4-17 branches and 20-50 leaves (plot 1) and 4-8 branches and 11-30 leaves (plot 2) in Oxytropis campestris suffered the most from the 1987. For flowers the situation is 5-15 compared frost heavings and 1 and 3 individuals were lost with 1-6, indicating that conditions may have already during the first year in plots 1 and 2, been more favourable for Oxytropis in plot 1. respectively. In plot 2 only 4 of 10 Oxytropis were left in 1987 and in plot 1 there were 6. Although Orchis mascula has been most favoured in plot 2. the grazing is weak it makes it somewhat easier to The five individuals survived until 1987, and 3 new withstand competition in plot 1. Especially Filipen­ rosettes (also with flowers) were recorded. All in­ dula vulgaris, Asperula tinctoria and Prune/la dividuals were very strong. In plot 1 the situation

Acta phytogeographica suecica 76 Shrub expansion in alvar grasslands on Oland 91

Table 2. Species recorded 1983- 87 in the permanent plot no. 3 (4x4 m ) in a dense juniper scrub, cut in 1983. Species were recorded each year in September-October and in May 1984. From Sept. 1984 the plot was recorded as 4 subplots ( 2x2 m) . The 5-degree cover scale by Hult-Sernander- Du Rietz was used . (x means one single individual.) The species are classi­

fied as : A = alvar species, M = meadow species and W = shrub /woodland species.

Year 83 84 84 85 86 87 84 85 86 87 811 85 86 87 84 85 86 87 Sub�lot (2 x 2 m) 2 3 4

AM Achillea millefolium - - - -

------MW Agrimonia eupatoria X X X AMW Agrostis capillaris 2 - 1 1 Anthyllis vulneraria - - AM X X 1 AMW Arabis hirsuta - X - X Arenaria serphyllifolia - 1 AM X - AMW Asperula tinctoria 1 - - - Berberis vulgaris - - w X X X X X AMW Campanula persicifolia 1 1 1 1 1 C. rotundiforia - - 1 1 AMW X 1 1 X 2 - - - - AM Cardamine hirsuta 1 1 2 1 1 1 A Carex caryophyllea 1 1 1 1 1 1 AM c. flacca 1 1 1 Cerastium sp. 1 AM 1 1 - 1 Cirsium arvense ------AM X X vulgare - - AM c. X 1 X X 1 1 ------MW Cotoneaster integerrimus X X - - - - - AM Festuca ovina 1 1 1 - - - Filipendula vulgaris 1 1 1 AM 1 ' 1 1 1 X X 1 1 AM Fragaria viridis 2 2 2 2 4 4 4 3 11 2 3 3 3 1 1 MW Galium aparine 1 1 1 1 1 1 1 1 1 1 1 G. boreale 1 1 2 - AMW 1 X - - - - 1 - - - - AM G. verum 1 1 1 1 1 MW Geum urbanum 3 3 3 11 3 3 2 11 11 11 5 2 3 3 Hieracium sp. - - - - MW X AMW Juniperus communis - - X X 1 1 X 1 Lotus corniculatus 1 - AM X 1 1 1 1 Luzula cf. multiflora - - 1 - - MW X 1 X 1 - - AM Medicago lupulina X X Phleum phleoides - - - - 1 AM 1 X AM Plantago lanceolata 1 ------AMW Poa angustifolia 1 - 1 MW P. compressa AM Polygala vulgaris - X 1 X X X A Potentilla tabernaemontani 1 - 1 Primula veris ------MW X AMW Prunus spinosa 2 3 2 3 2 2 3 2 Rhamnus catharticus - w X X 1 AMW Rosa dumalis 1 1 1 3 3 2 3 AM Scabiosa columbaria ------1 - 1 AM Scleranthus perennis - - - Sonchus cf. asper - - - - AM - - AM Stellaria graminea 1 1 - - MW Taraxacum vulgare 1 1 1 1 X 1 1 1 MW Torilis japonica 2 3 2 2 1 2 2 2 - - - - AM Trifolium campestre 1 MW T. medium - - - - T. pratense - - AM X AM T. repens - - - - X 1 AM Veronica arvensi s ------X X X Viola hirta w 1 1 1

No. of species in subp lots: 23 29 30 28 20 26 26 28 29 211 25 26 22 29 30 30

Total number of species : 7 111 1984: 35 1985 : 44 1986 : 41 1987 : 43 was not satisfactory as the orchids were grazed marked orchids, 16 new rosettes have been noticed most of the time. In 1987 three of them disap­ (1986) and as many as 35 in the NE corner of the peared, probably as they became covered by small plot. The latter must have been there from the ant-hills. Such hills were very frequent in many beginning, but hidden for some time after the places in 1987. In the edge plot (no. 4) only 2 of 10 severe drought in the summer of 1983. In the con­ specimens were lost, although they were probably trol one orchid was lost. Table 1 gives the flower­ frequently eaten by grazing animals. Close to the ing frequency.

Acta phytogeographica suecica 76 92 Ej vind Rosen

Table 3. Species present i 4 permanent plots within a dense juniper scrub, on the Alvar of Drostorp 1983-87) . The juniper cover was 95- 100% for plots no. 1 - 3 and 30% for plot no. 4 ( - before the juniper removal in October 1983. Cover ( %) of the bottom , fi eld- and shrub­ layers and numbers of juniper seed lings and vascular plants are given .

Plot no. 2 3 4 Species Year 83 84 85 86 87 83 84 85 86 87 83 84 85 86 87 84 85 86 87

Achillea millefolium Agrimonia eupatoria Agrostis capillaris Allium vineale Anthoxanthum odoratum Anthylli s vulneraria Arabis hirsuta Arenaria serpyllifolia Artemisia oelandica Asperula tinctoria Avenula pratensis A. pubescens Berberis vulgaris Briza media Bromus mollis Campanula persicifolia C . rotundifolia Cardamine hirsuta Carex caryophyllea C . ericetorum C. flacca C. muricata Cerastium semidecandrum C. sp. Cirsium acaule C. arvense C. vulgare Convolvolus arven si s Cotoneaster integerrimus Crataegus oxyacantha Epilobium angustifolium E. sp. Festuca ovina Filipendula vulgaris 1 Fragaria viridis 1 1 Galium aparine 1 G. boreale �1 G. verum 1 1 Geum urbanum 1 1 Helianthemum nummularium 1 Hieracium pilosella H. sp. Hypericum perforatum I nu la salicina Juniperus communis Leontodon sp . Leucanthemum vulgare Linum ca tharticum Li thospermum officinalis Lotus cornicu latus Luzula campestris L. cf. multiflora Medicago falcata M. lupulina Myosotis stricta Orchis mascula 0. morio Oxytropis campestris Phleum bertoloni i P . phleoides Plantago lanceolata Platanthera chlorantha Poa angustifolia P. compressa Polyga la vulgaris Potentilla argentea P. tabernaemontani Primula veris

Acta phytogeographica suecica 76 Shrub expansion in alvar grasslands on Oland 93

Table 3 (contin.)

Plot no . 2 3 Species Year 83 84 85 86 87 83 84 85 86 87 83 84 85 86 87 84 85 86 87

Prunella grandiflora - 1 - 1

Prunus spinosa 1 1 1 1 1 Pulmonaria officinalis Pulsatilla pratensis - 1 1 - 1 1 1 1 1 Ranunculus bulbosus - 1 1 - 1 Rhamnus catharticus 1 1 - - 1 1 1 Ribes uva-crispa 1 Rosa dumalis 1 1 1 1 1 1 R. sp. 1 1 1 1 Rumex acetosa 1 1 R. sp . - 1 Scabiosa columbaria - 1 1 1 Scleranthus perennis 1 - 1 1 - Sed um acre 1 - - 1 S. reflexum - - 1 1 1 1 Sesleria caerulea - 1 1 1 1 Solanum dulcamara - 1 1 Sonchus cf. asper - 1 Stellaria graminea - 1 1 1 1 - 1 1 1 Taraxacum Eryth. - 1 T. vulgare - 1 1 1 1 - 1 - 1 1 1 Thymus serpyllum -- 1 Torilis japonica - 1 1 1 - 1 1 1 1 Trifolium arvense - 1 1 1 T. campestre 1 1 1 - T. medium 1 1 - 1 1 1 - 1 1 T. pratense 1 T. repens 1 - 1 Veronica arvensis - 1 V. officinalis - 1 1 V. spicata - 1 - 1 1 1 1 1 Viola cf. canina - - 1 V. hirta 1 1 1 1 1 1 1 1 1 1 - - 1

Cover bottom layer ( %) 50 20 30 30 25 50 25 50 50 60 25 25 40 45 40 5 Cover fi eld layer ( %) 50 50 67 70 70 82 60 65 8 Cover shrub layer 10 3 15 2 10 5 8 ( %) 1 7 No. of Juniperus seedlings 2 4 12 5 10 16 6

Total no . of vase. plants 11 49 59 63 66 10 45 49 55 61 7 35 44 41 43 38 38 43 44

The results of sowing were poor. In 1984 there lis, which were all present in 1983. They main­ were 6 seedlings of Pulsatilla in plot 2. They sur­ tained or even increased their cover in the subplots vived and in 1987 there were 7. In 1985 one Pulsa­ where they were present. The decrease of Prunus in tilla seedling appeared in plot 1 , and this plant is 1986 was caused by a second clearing in October still alive. 1985. Also Torilis japonica had a higher cover Regeneration (Tables 2 and 3) value than most of the other species, a cover which Plot no. 3 was undisturbed by transplantation and was maintained later. grazing. After the clearing in October 1983 the Some species occurred permanently, such as moss cover (total 25 OJo) was dominated by Asperula tinctoria, Campanula persicifolia, Carex Plagiomnium affine. There were only 7 vascular caryophyllea, C. flacca, Filipendu/a vulgaris, plant species growing scattered throughout the Galium aparine and Viola hirta (found in 3 or 4 of plot. the subplots). Earlier mentioned species with high The number of vascular plants increased to 14 cover also belong to this group of 'permanent' (in May) and to 35 (in September 1984); see Table species. 2. Some species had regenerated rapidly reaching A few species had a cover value of 2 during some high cover values, for example Fragaria viridis, years (or one single year), for example Trifolium Geum urbanum, Prunus sp inosa and Rosa duma- pratense, T. rep ens, Galium borea/e. Cardamine

Acta phytogeographica suecica 76 94 Ej vind Rosen

Fig. 2. Permanent plot no. 2 (4 m) in dense juniper x 4 scrub cut in 1983. Transplanted flowering orchids (Or­ Fig. 3. Permanent plot no. 2 (4 m). There has been chis mascula) may be identified. The field layer has x 4 started to regenerate from the seed bank in the soil. a strong regeneration of the field layer after the juniper Viola hirta, Filipendula vulgaris, Primula veris and removal in 1983. Poa angustifolia, Prunus sp inosa, Fragaria viridis may also be recognized. - Alvar of Filipendula vulgaris, Viola hirta and Plantago lanceolata Drostorp. 26 May 1985. Photo: E. Rosen. may be distinguished. - Alvar of Drostorp. 25 September 1987. Photo: E. Rosen.

hirsuta and Agrostis capillaris. The latter species niculatus, Potentilla tabernaemontani and Trifo­ was erroneously recorded as Brachypodium pin­ lium repens, were present already in 1984. Ceras­ natum (Rosen 1985), a species which was not tium sp., Medicago lupulina, Scabiosa colum­ found later. baria, Scleranthus perennis, Trifolium campestre Other species appeared in 1985, namely and Veronica arvensis appeared in 1985 and also Agrimonia eupatoria, Arabis hirsuta, Cerastium belong to this group. A few species, e.g. Berberis sp., Medicago lupulina, Poa angustifo lia, vulgaris, Geum urbanum and Viola hirta are Rhamnus catharticus, Scabiosa columbaria, almost exclusively shrubland plants. Some re­ Scleranthus perennis, Trifolium campestre, T. corded species have a wide ecological amplitude, medium and Veronica arvensis. Two species were covering open to shady areas, e.g. Campanula lost, namely Sonchus cf. asper and Poa compressa. rotundifolia, Galium boreale, and Prunus sp inosa. In 1986 Cirsium arvense, Cotoneaster integer­ A comparison of all the four ( 4 4 m) plots - x rimus and Phleum phleoides appeared, but An­ (Table 3) shows that during the investigation thy/lis vulneraria, Arabis hirsuta, Cirsium vulgare, period there was a remarkable increase in number Scleranthus perennis, Trojolium campestre and T. of species in plots 1 and 2, from 11 to 66 and 10 medium were not found. -In 1987 Arabis reap­ to 61, respectively (Figs. 2 and 3), while plot 4, peared and Hieracium sp. made its first ap­ having been grazed for many years, has a fairly pearance. stable number of species, only varying from 38 to Of the total number of species recorded in the 44. The much larger number of species in 1987 in plot (5 1), 27 may be treated as alvar/meadow plots 1 and 2 compared with plot 3 was probably species (code: A and AM in Table 2) . Some species caused by an unintentional introduction of species of that group, for example Achillea millejolium, in the soil accompanying the transplanted speci­ Anthyllis vulneraria, Arenaria serpyllifolia, mens. Altogether 16 species are found in both the Festuca ovina, Filipendula vulgaris, Lotus cor- grassland plot 4 and in one or both of plots nos.

Acta phytogeographica suedca 76 Shrub expansion in alvar grasslands on 0/and 95

Fig. Part of Stora Alvaret with 4. dense juniper scrub (more than 75 OJo cover) in an area with lit­ toral deposits. In the background the village of Gosslunda. Small juniper stands can be seen on a beach ridge between the village and the dense scrub. - Alvar of Barby. 8 October 1986. Photo: E. Rosen.

1 and 2, but are missing in plot no. 3, e.g., Anthox­ Most susceptible to colonization and shrub ex­ anthum odoratum, Helianthemum nummularium, pansion, mainly by junipers, are: Linum catharticum, Luzula campestris and the (1) Areas at the edge of the Alvar (also areas close transplanted species. to villages situated on the Alvar), on deep soil, gen­ Some other grassland species, however, occur in all erally places for former hay-meadows and four plots, e.g. Anthyllis vulneraria, Lotus cor­ cultivated land. niculatus and Potentilla tabernaemontani. They (2) Areas on the Alvar plain with glacial deposits, were not present in plots 1-3 in 1983. The slightly now appearing as slightly elevated beach ridges larger number of species in plot 1 may be a conse­ with littoral material. quence of grazing. Colonization also takes place in: At the end of Table 3, cover values are given for (3) Areas with high frequency of fissures in the separate layers of plots no. 1-3. Plot 4 was not bedrock, e.g. karst areas. recorded but has a field layer cover close to 98 OJo . Considering the cleared plots, nos. 2 and 3 (4) Depressions in the bedrock where ground (ungrazed) had higher cover values in both field­ water or temporary surface water is available. and bottomlayer than no. 1 (grazed). An establish­ (5) Areas surrounding the alvar lakes with more or ment of several juniper seedlings was also re­ less permanent water, around fens or large tem­ corded, indicating that no problems for regenera­ porary pools. tion of junipers exist in this area. On the contrary, There are now several areas covered by very regeneration is a problem in old stands in, e.g. dense and fairly large alvar scrubs (cf. Fig. 4). But Great Britain (Ward 1973); in some places due to areas where a rapidly increasing shrub expansion is heavy sheep grazing (Gilbert 1980). still going on are much larger (cf. Rosen 1988). Mapping of shrub- and tree vegetation Shrub colonization is very frequent in areas with The following general remarks are intended to deep soil where grazing is weak or has ceased. To summarize results obtained from the survey of some extent the shrub expansion in transitional shrub- and tree expansion on Stora Alvaret. zones between deep and thin soil is pushed back or

Acta phytogeographica suecica 76 96 Ej vind Rosen

Fig. 5. On old beach ridges or other littoral deposits there is, in some areas, a spontaneous col­ onization of Pinus sy lvestris to­ gether with the expanding juniper scrub. Colonized areas are limited by areas with thin soils. - Alvar of Barby. 8 Octo­ ber 1986. Photo: E. Rosen.

at least checked after extreme periods of drought, have very poor trees which today are rarely used such as in 1969, 1975 and in 1983 (cf. Rosen 1987). for fire-wood. Unfortunately there is a very big Deciduous trees are most common close to small spontaneous establishment locally of new pines . streams, fens and wet meadows. Betula pendu/a close to suc.h woodlands. Small groups or scattered and B. pubescens are very frequent. In some karst trees are now found frequently in fissures or places areas Fraxinus excelsior, Popu/us tremula and with deep soil. An example of an area with such a Sorbus intermedia are found. There is a big spontaneous establishment is shown in Fig. 5. population of Corylus avellana in a large karst Locally, Picea abies is also found in fissures or in area close to the village of Ekelunda. Salix spp. are wood- or shrub-land. found close to alvar lakes. In mesic parts of the The survey (and the map) show that areas with Alvar with junipers we may also find Sorbus in­ dense juniper scrub and tree establishment are termedia. It is locally accompanied by Prunus found in the N and NE parts of Stora Alvaret (Fig. sp inosa, Rosa spp. and Crataegus spp., which also 1), as well as in its western central part. In the occur in karst areas. south, the expansion is less pronounced due to In the beginning of the 20th century Pinus thinner soils. However, narrow strings of birch sylvestris was planted in small areas in various trees locally follow the small streams, which are a parts of the Alvar, in some cases on abandoned part of the drainage system of the Alvar. fields. These plantations were created with the pur­ The map (Fig. 1) is only part of the complete pose of providing fire-wood and also to give some map showing shrub and tree presence on the Alvar, shelter from the wind. Du Rietz expressed as early representing the situation in 1985, and which is as in 1921 a very negative opinion of these planta­ hoped to become brought up to date. tions as pines were not a natural part of the calcareous grassland ecosystem and furthermore disturbed the very open horizons of the Stora Discussion Alvaret. These plantations now form small enclaves of The tree and shrub expansion on the Stora Alvaret, woodlands in the alvar landscape. Usually they highly correlated with the grazing situation and

Acta phytogeographica suecica 76 Shrub expansion in alvar grasslands on 0/and 97

Fig. 6. Moist part of an ungrazed alvar with expansion of Juniperus communis and Potentilia fr uticosa. The domi­ nant grass is Sesleria caerulea. Birch trees in the background. - Alvar of Gettlinge. 7 November 1987. Photo: E. Rosen.

former wood-cutting, is a major nature conserva­ become almost entirely lost, a community with tion and management problem. some interesting species plant geographically such Today about 25 OJo of the area is grazed by sheep as Artemisia oelandica. Helianthemum oelan­ and 50 OJoby cattle, including a few horses. The re­ dicum. Viscaria alpina v. oelandica and Prune/la maining 25 % is ungrazed, grazing having ceased grandiflora. In this community there is also a large in some parts only fairly recently. abundance of Orchis mascula and Dactylorhiza sambucina. Less frequent are Orchis morio, 0. The sheep-grazed areas are in a fairly balanced ustulata and Plathanthera ch/orantha. situation, while shrub expansion is more pro­ Maintained grazing and shrub-cutting is the only nounced in cattle-grazed areas, usually subject to way to manage this problem. Burning is not ad­ lower grazing pressure. visable on the fairly thin and humus poor soils but As a result of shrub expansion, junipers will, has been used, and may be used, to control expan­ step by step, take over the grasslands of the sion of Potentilla fr uticosa in moist areas. Veronica sp icata - A venula pratensis association A similar expansion of juniper scrub is also tak­ (Krahulec et al. 1986) and the most valuable graz­ ing place in alvar areas of Estonia (Laasimer 1975, ing land area will decrease. This creates a pro­ 1981; Kalda 1981; Zobel 1984). The necessity of gressively weakening interest for maintained graz­ management in semi-natural grasslands in order to ing of certain areas. maintain a flora that has been established and From a nature conservation point of view, a stabilized for many years is also stressed by species-rich and interesting plant-community will Medwecka-Kornas (1977).

Acta phytogeographica suecica 76 98 Ej vind Rosen

Fig. 7. Re-introduced grazing in an alvar area with moist parts Gust to the south of the area in Fig. 6) being opened up after one year of cattle grazing. Potenti/la fruticosa shrubs are now easily seen. - Alvar of S. Mockleby. 7 November 1987. Photo: E. Rosen.

As a first step to solve the situation, the National given in Fig. 5). Of these 25 species about 17 would Swedish Environment Protection Board (SNV) is be alvar/meadow species. The same conditions for financially supporting the fencing of areas in a 2 2 m plot would give 17 and 12 respectively. x severe need of maintained grazing. My survey of In experiment plot no. 3 there were, on average, the Stora Alvaret furthermore includes the estab­ 22 species in the 2 2 m subplots (1984) of which x lishment of locally adapted recommendations for 11 are open grassland species. In 1985 the figures future management, which will form a basis for were 27 and 13 respectively. This single plot (no. 3) the next step of shrub clearing. No clearcuttings of does not really indicate the presence of a long-lived alvar areas are wanted, but at least there must be seedbank in the soil. However, during 1984-87 a a stop to the juniper expansion at the present level, total of 27 alvar species were recorded in the plot allowing a rich variety of shrubs and trees to still (4 4 m) which can be compared with an ex­ x exist. pected number of about 17. In plot no. 2 alto­ It was important for this management context to gether 33 open grassland species were recorded, in­ find out that several alvar or grassland species dicating an extra influence originating from the in­ disappear when the juniper canopy in an area ex­ troduced soil patches. Results of studies carried ceeds 75 o/o in cover (Rejmanek & Rosen 1988). out in Wharram Quarry in Great Britain show that Referring to the same publication, about 25 species Arenaria serpyllifolia, Cirsium arvense, C. vulgare would be expected in a plot of 4 4 m with a and Sonchus asper germinated from soil cores in x 95 % juniper cover (as calculated from the curves an area where they were not present in the field

Acta phytogeographica suecica 76 Shrub expansion in alvar grasslands on 0/and 99

layer of the plots. The same was valid for Car­ References domina hirsuta in the Kiplingcotes Chalk Pit (Jef­ ferson & Usher, in press). Soil samples must be Albertson, N. 1950. Das grosse siidliche Alvar der lnsel taken to check whether the same situation took Gland. Eine pflanzensociologische Ubersicht. - place with the species in my plots. Svenskt bot. Tidskr. 44: 269-331. A general conclusion is that several grassland Angstrom, A. 1953. Temperatur, humiditet. - Atlas over Sverige, map 25-26. Stockholm. species can survive either as suppressed species in - 1974. Sveriges klimat. 3rd ed.- Stockholm. 188 pp. a dense scrub or as a part of a seedbank. The fairly Bengtsson, K., Prentice, H. C., Rosen, E., Moberg, R. high number of grassland species recorded in my & Sjogren, E. 1988. The dry alvar grasslands of plots indicates that several grassland species were Gland: ecological amplitudes of plant species in rela­ stimulated to grow as a result of the canopy tion to vegetation composition. - Acta phytogeogr. suec. 76. removal. The same was valid for seeds of Du Rietz, G. E. 1921. Vegetationen och det olandska shrubland species. If necessary for the restoration landskapet. - Svenska Turistfor. Arsskr. 1921: of a cleared area, the transplantation into the area 73-91. of species, or rather tussocks, from open grassland Ekstam, U., Jacobson, R., Mattson, M. & Porsne, T. may assist. Such activities may be used in very 1984. Glands och Gotlands vaxtvarld.- Stockholm. 336 pp. special cases. Enckell, P. H., Konigsson, E. S. & Konigsson, L.-K. To avoid complicated methods of restoration it 1979. Ecological instability of a Roman Iron Age is necessary to maintain a traditional land use, as human community. - Oikos 33: 328-349. far as possible, probably combined with some Gilbert, 0. L. 1980. Juniper in Upper Teesdale. - J. management activities to ensure the survival of Ecol. 68: 1013-1024. Jefferson, R. G. & Usher, M. B. The seed bank in soils plants and animals in valuable biotopes. For Stora of disused chalk quarries in the Yorkshire Wolds: Alvaret a regular long-term schedule for manage­ Implications for conservation management. - Biol. ment is now urgently needed. Conserv. In press. Kalda, A. 1981. Human impact on the plant cover of Lahemaa National Park. - Anthropogenous changes in the plant cover of Estonia, Tartu, pp. 32-45. Krahulec, F., Rosen, E. & van der Maarel, E. 1986. Pre­ liminary classification and ecology of dry grassland communities on Glands Stora Alvar (Sweden). - Nord. J. Bot. 6: 797-809. Konigsson, L.-K. 1968. The Holocene history of the Great Alvar of Gland.- Acta phytogeogr. suec. 55: 1-172. Acknowledgements. This research was financially sup­ Laasimer, L. 1975. Rare plant communities and their ported by a grant from the National Swedish Environ­ conservation problems. - Some aspects of botanical ment Protection Board (SNV) for which I am most research in the Estonian S.S.R. Tartu, pp. 62-73. grateful. I also thank Uppsala University and the Axel - 1981. Anthropogenous changes of plant com­ and Margaret Ax:son Johnson Foundation for support munities and problems of conservation. - An­ with instrumentation. For use of advanced stereoscope thropogenous changes in the plant cover of Estonia. equipment for air-photographs I thank the Physical Tartu, pp. 18-31. Geography Departments at both Uppsala and Medwecka-Kornas, A. 1977 . Ecological problems in the Stockholm Universities. conservation of plant communities, with special ref­ Eddy van der Maarel is thanked for methodological erence to Central Europe. - Envir. Conserv. 4: suggestions. I have received various kinds of assistance 27-33. from staff and colleagues at Uppsala University Rejmanek, M. & Rosen, E. 1988. The effects of coloniz­ Ecological Research Station, Glands Skogsby, and from ing shrubs (Juniperus communis and Potentilla Lennart Nilsson, Kalmar; to all of you I extend my fruticosa) on species richness in the grasslands of warm appreciation of your help. Folke Hellstrom made Stora Alvaret, Gland (Sweden). - Acta phytogeogr. the photo copies, Ulla J ohansson and Marta Ekdahl suec. 76. typed the MS, Erik Sjogren gave various kinds of sug­ Rosen, E. 1982. Vegetation development and sheep graz­ gestions on the MS, Nigel Rollison helped me with the ing in limestone grasslands of south Gland, Sweden. linguistic revision. -Acta phytogeogr. suec. 72: 1-104.

Acta phytogeographica suecica 76 100 Ej vind Rosen

- 1985. Succession and fluctuations in species com­ Sterner, R. 1948. blands flora. - bland I. Lund, pp. position in the limestone grasslands of South bland. 91-235. - Miinst. geogr. Arb. 20: 25-33. - 1986. blands karlvaxtflora. (ed. A. Lundqvist). 2nd - 1987. Vaxtekologisk naturvardsforskning pa blands rev. ed. of 'Flora der Insel bland' 1938. - Lund. Stora Alvar. - Acta Univ. Upsaliensis Ser. C, 53: 400 pp. 53-65. Tutin, T. G. et al. 1964-80. Flora Europaea 1-5. - - 1988. Development and seedling establishment Cambridge. within a Juniperus communis stand on bland, Ward, L. K. 1973. The conservation of juniper. I. Pre­ Sweden. - Acta bot. neerl. (in press) sent status of juniper in southern England. - J. Rosen, E. & Sjogren, E. 1988. Plant cover in alvar appl. Ecol. 10: 165-188. junipers on bland-distribution features correlated Zobel, M. 1984. Alvars, juniper scrubs and alvar juniper to shrub size and shape. - Acta phytogeogr. suec. scrubs. - Eesti Loodus 1984: 372-378. 76.

Acta phytogeographica suecica 76 Plant cover in alvar junipers on bland Distribution features correlated to shrub size and shape

Ej vind Rosen & Erik Sjogren

Abstract Rosen, E. & Sjl>gren, E. 1988. Plant cover in alvar junipers on Oland. Distribution features correlated to shrub size and shape. - Acta phytogeographica suec. Uppsala. ISBN 76, 91-7210-076- 1.

A survey of the plant cover inside junipers was carried out (1986-87) in the limestone grasslands of Stora Alvaret on the island of Oland, including small alvar areas in the northern part of the island. The dependence of the species composition was checked between plots (1 m2) and variables as height, cover, plot exposure in the shrubs and area of the shrub and scrub (Juniperus communis). Using multivate methods (CCA), a good correlation was found for shrub height and for shrub (scrub) area in determining the floristic variation. The total shrub cover and a central position of the plots in the shrub were somewhat less important. Other exposures as North, West, etc., seemed of minor importance in this survey. Four main clusters for juniper habitats were obtained by cluster analysis (TABORD). Small differences in plant cover due to the geographic position of investigated areas were found. The total number of bryophyte species recorded in the alvar junipers exceeds The 60. number of deciduous forest species with low drought tolerance and preference for high pH is unexpectedly high. Their epigeic or epiphytic presence within the shrubs is probably due primarily to the efficient shelter provided. Conditions of normally low bark and litter pH in the shrubs are compensated by frequent short-term supply of calcareous dust, thus being of minor importance as an obstacle to their colonization and survival. Several bryophyte species typical of shrubless alvar communities apparently survive in the junipers for several years. They become slowly outcompeted by species with more pronounced needs for shelter.

Keywords: juniper scrub, juniper field layer, shrub height, shrub area, shrub cover, exposure, bryophytes, multivariate analysis, alvar.

Ej vind Rosen and Erik Sj ogren, Institute of Ecological Botany, Up psala Un iversity, Box 559, Up psala, Sweden. 751 22

Introduction cording to Krahulec et al . (1986). The area is covered mainly by dry grasslands with a large In the southern part of the island of Oland there is number of phytogeographically interesting floral a large sedimentary limestone plateau, Stora elements (see Sterner 1948, Rosen 1982). Several Alvaret, dating back to the Ordovician period. species are disjuncts or at the edge of their distribu­ This limestone area is covered by thin soils of dif­ tion areas (see Bengtsson et al. 1988). About 18 OJo ferent origins: weathered soil (calcareous) and is fen or moist meadow areas according to Enckell glacial or glacio-fluvial material reworked by the et al. (1979). sea under littoral conditions (mainly silicious). In Stora Alvaret has been influenced by grazing, small lakes and fens there are lime-gyttja and marl. and also wood-cutting, for several thousands of One percent of the area is bare limestone rock with years, especially from the first centuries AD on. karst. Part of the area may be considered as semi-natural From a Scandinavian point of view the precipi­ grassland. The cultural influence was very strong tation is low, only 437 mm per year (1965-84) ac- during the 19th century, but changed drastically as

Acta phytogeographica suecica 76 102 Rosen & Sj ogren a result of a big emigration to North America (1881-1910). Shrubs and trees started to regener­ ate and the expansion especially of Juniperus com­ munis is still proceeding, now becoming a severe nature conservation problem (Rosen 1982). Areas of the species-rich Veronica sp icata - Avenula pratensis association (Krahulec et al . 1986) and also the best grazing land will decrease rapidly if this situation continues. For further information on geology, soils, vegetation and cultural influ­ ence, see Konigsson (1968) and Rosen (1982). The increasing juniper scrub gives rise to numerous questions about the future development of the landscape and of the composition and diver­ sity of the total plant cover. Diversity and juniper cover related to size of the research areas were studied by Rejmanek & Rosen (1988). Results show a drop in the number of alvar/meadow species in places where shrub cover Fig. 1. Sample plot (no. 56) showing a low shrub with exceeds 75 OJo. The species composition (vascular low cover. - Alvar of Gynge. 21 September 1987. Photo: E. Rosen. plants) inside junipers and the regeneration of the plant cover after clearing of the shrubs were studied by Rosen (1982, 1988 a) . Nonetheless, our (see Fig. 1). Plots were also recorded in order to knowledge of the composition of the fieldlayer and represent glades in shrubs and gaps between shrubs the bottomlayer in relation to junipers on the where they were situated in large stands. The area Alvar is still fairly small. In addition to the long­ of the shrub and its height were measured and so term research on juniper growth and scrub expan­ was the total shrub cover in the plots. In some sion (Rosen 1988 b) it was found important to cases Prunus sp inosa, or other deciduous shrubs/ make a detailed survey of plant cover and junipers. trees were present. The total cover was largely the same as the juniper cover in percent. The aims of the study were: For mosses, lichens and vascular plants (and if (1) To find out if there is a correlation between present, epiphytic mosses), a 1-9 cover-abun­ plant cover composition and shrub size and shape. dance scale (W esthoff & van der Maarel 1978) was (2) To distinguish a possible geographic variation used. Also the total covers of vascular plants, in plant cover, comparing localities mainly within mosses, lichens and total plant cover respectively the Stora Alvaret with other ones in alvars in the were estimated in percent. The 58 plots were north of the island. recorded in 1986 and 1987 (autumn). (3) To examine possible differences in plant cover The following sites were investigated: Nedre A 1-5, 6-9, 10-17 in the junipers due to different aspects and ex­ .Ieback plots Drostorp Gynge 54-58, 18-21, 22, posure. and Karum Borgholm Sandvik 23-24, Jordhamn 25-26, Vasteralvaret 27-28, Ebbegarde 29, Sodra Mockleby 30-32, Penasa 33-37, Ventlinge 38-41, Eriksore 42-44, Kalk­ stad 45-47, Norra Nasby 48-50 and Resmo 51- Methods 53. The nomenclature for vascular plants follows The samples were chosen to represent both central Tutin et al. (1964-80), for mosses Corley et al. parts of the shrubs and different aspects at their (1981), for hepatics Grolle (1983) and for lichens edges, as well as various sizes and shapes of shrubs Santesson (1984).

Acta phytogeographica suecica 76 Plant cover in alvar junipers 103

Fig. 2. Canonical Cor­ e 'i.e respondence Analysis 11 (CCA), axes 1 and 2. n Location of the sample ne plots (1-58) related to nw e exposure of plots within n n n ne n shrubs. Exposure: n = n north, nw northwest, nw = s = south, etc., c = centrality and g glade. = Arrows indicate the relative importance and 9 direction of various ex­ positions, marked with c c g c c c g capital letters (no arrow c c 9 c c c c for glade). All species are c c c included. 9

c

c

The floristic data, including cover values, were other ones. However, all these variables are less combined with variables such as exposure of the important than centrality. A residual in the ordina­ plots, height, area, etc. and treated with multi­ tion was occupied by plots with a pronounced variate methods to examine possible clusters, gra­ glade inside (g), forming a well separated group. dients and correlations within the data set. Clusters A combined ordination including both exposure were obtained with the T ABORD program (van and the variables area, height and total shrub cover der Maarel et al. 1978). The ordination was done has been given in Figs. 3-5. It is quite clear that with a Canonical Correspondance Analysis pro­ the latter variables are more important to species gram CANOCO (Ter Braak 1987) which is an ex­ composition than exposure, all getting high cor­ tension of the programme DECORANA (Hill relation values. The most important exposure vec­ 1979). tor is still centrality (see Fig. 3). The vectors for height (H) and area (A) seem to be fairly well linked, pointing in almost the same direction, a not unexpected result. Results The areas of the shrubs varied from 1-100 m2• Stands of 100 m2 or larger were treated as 100 m2• An ordination (Canonical Correspondence Large stands usually consist of high junipers, even Analysis, CCA) was run to check a possible cor­ if a single shrub with low area also may become relation between species composition of the vari­ quite high. There is a variation of high, erect and ous plots and their exposure in the shrubs (not in­ low, prostrate shrubs in the juniper vegetation of cluding cover, height and area). It was found that the alvars. Plotting of the shrubs with an area a central position of the plots in a juniper ('cen­ treated as 100 m2 in the diagram and the shrubs trality') obtained a high correlation. This is shown higher than 1 m gives a fairly good overlapping in Fig. 2 by an arrow (C) (a vector) indicating the (see Fig. 4). If glades are included they are all direction and its length indicating the relative im­ found in the plots representing large areas and, portance of the variable. The centrality plots with one exception, also in shrubs higher than 1 m. (marked c) form a fairly distinct group. Of the A high juniper scrub may be very dense (Rej­ other exposure variables an eastward position (E) manek & Rosen 1988), but there are also fre­ indicates somewhat more importance than the quently gaps where light may penetrate to the

Acta phytogeographica suecica 76 104 Rosen & Sj ogren

Fig. 3. CCA, axis 1 and 11 36 9 2. Location of sample 58 plots (1-58). Direction 37 6 8 and relative importance 40 54 of the variables H (shrub height), A (shrub area), 31 7 T (total shrub cover) and 57 35 47 exposure S, N, W, E and 56 4 55 28 4 C (centrality) are in­ dicated. All species are 43 included.

51 17 21 39 1 T 52 13 32 11 5 27 16 4 4 6 18 12 25 34 23 53 41 26

Fig. 4. CCA analysis (all 11 � species), axis 1 and 2. • Plots with an area of 100 m2 are indicated by large • "i black dots, plots higher i than 1 m by triangles .. • and shrubs with glades • by empty triangles. Re- • � .. versed empty triangles in- • • J A• dicate glades , but a shrub height less than • • A 1 m. Remaining plots are • • marked with small A squares. Arrows are the • • .. A same as for Fig. 3 (not A indicated here).

• -� • • • • • •

ground and make it possible for a field layer to ex­ tion, high shrub cover does not overlap with the ist, cf. light measurements (op. cit.). presence of glades, but high cover has been Centrality and total shrub cover also show a recorded in shrubs of small size as well as in large fairly positive correlation to each other. If plots shrub areas. About half the number of the shrubs with a central position and a high shrub cover higher than 1 m are also characterized by high (70-1 00 OJo) are plotted there is also a very good cover. Central position of the plots and high cover overlapping (Fig. 5). Shrub height is low for most are combined except in 6 cases. of the central plots. The shrubs are higher than 1 A similar ordination was tried for vascular m in only 5 out of 21 of these plots. In the ordina- plants only. The distribution pattern of the plots

Acta phytogeographica suecica 76 Plant cover in alvar junipers 105

Fig. 5. CCA analysis (all 11 • species), axis 1 and 2. • • Plots with a central posi­ • • • tion are mar ked by dots • and plots with total • shrub cover 70-100 IIJ'o • by a circle. Remaining • • • • plots are marked with • � • small squares. Arrows • • 0 are the same as for Fig. D 3 (not indicated here). · o • 0 0 0 0 0 o 0 0 0 �@ 0 0 0 0 0

was about the same as for the pattern including all in only one or just a few plots. To illustrate these plants, but correlation values for the variables species, some of them are listed below Fig. 6 in were higher as the plots appear slightly more four groups corresponding to their location within gathered (especially for centrality). Height and the diagram, indicated by 1-4. total shrub cover received the highest correlation A clustering of plots within this material has values in relation to the floristic composition, provided 4 main clusters and some inferior ones while centrality and area got somewhat lower (Table 1). The clusters are located in the ordination values. In contrast, if cryptogams are included, the figure for all species (as seen before) in order to distribution pattern of the plots, related to height facilitate their correlation to the variables. The and area, becomes more condensed. cluster location is given in Fig. 7. A plotting of single species within the ordination Cluster A seems to be correlated to high cover of of only vascular plants provides a useful assorting the shrubs and somewhat to central position of the of, for example, species connected with large area plots. Cluster B is correlated to large shrub area, and height of the shrubs (Fig. 6). Such species are, shrub height over 1 m and to presence of glades. for example, Viola hirta, Veronica officina/is, Cluster H is slightly heterogeneous, but seems to Rumex acetosa and a long record of others which be more related to large areas than cl. A. Both cl. manage well in large stands with glades or gaps. A and H are correlated to high cover. Draba incana and Silene nutans are more distinctly Cluster N represents plots in shrubs with small correlated with centrality of the plots and with area and low height, but there is also a correlation high cover of the shrubs. Species well correlated to to moderately high shrub cover and to central posi­ small shrub area and low height of the shrubs and tion of the plots. to some extent also to high cover are, for example, The small clusters 0-T all represent plots from Veronica spicata and Sedum reflexum , while the northern small alvar areas on Oland. They are others, for example, Carex caryophyllea, prefer gathered at a low position on axis 2 and to the left both small area, low height and low cover of the of the position for cluster A. These plots correlate shrubs. to small shrub area, low shrub height as well as to Several species received higher correlation values centrality and high shrub cover. than these species, but they were usually recorded Several species are in common to all these 4

Acta phytogeographica suecica 76 106 Rosen & Sj ogren

. 11 Sllene nutans

Draba lncana 2

Geranium robertlanum

Sedum reflexum

Veronica splcata Geum urbanum Prunus splnosa

H Stellarla gramlnea . . Veronica Fragarla vlrldls • offlclnalls

Carex caryophyllea

VIola hlrta .

Rumex acetosa . 3 4 Trifolium medium .

Fig. 6. CCA analysis (only vascular plants), axis 1 and 2. Positions of single species and the directions and relative importance of exposure (S, N, W, E and C centrality), the total shrub cover (T), height (H) and area (A) are = indicated. Species with high correlation but usually few occurrences are listed below for each of the sectors 1-4.

1. 2. 3. 4. Agrostis gigantea Berberis vulgaris Anthyllis vulneraria Agrimonia eupatoria Convolvolus arvensis Epilobium angustifolium Artemisia campestris Arrhenatherum elatius Erophila verna Fraxinus excelsior Betula pendula Botrychium lunaria Festuca oelandica Moehringia trinervia Calluna vulgaris Campanula persicifolia Galium oelandicum Rubus saxatilis Carlina vulgaris Cynosurus cristatus Lithospermum officinale Sorbus aucuparia Globularia vulgaris Galium aparine Sedum album Helianthemum oelandicum Geranium sanguineum Senecio jacobaea ssp. gotl. Linum catharticum Potentilla fruticosa Viola cf. elatior Pimpinella saxifraga Rhamnus frangula Pulsatilla pratensis Ribes uva-crispa Rumex acetosella Sorbus intermedia Sedum acre Trifolium montanum T. pratense Viburnum opulus Vicia cracca clusters (Table 1). Dicranum scoparium and Hyp ­ Rhytidiadelphus triquetrus, Fragaria viridis and num cupressiforme are frequent in clusters A and Agrostis capillaris have high frequencies in large N, probably favoured by sheltered although dry area shrubs with glades and in high shrubs (B). conditions. The high frequencies of Festuca ovina Homalothecium /utescens is more drought tolerant and Asperula tinctoria in N certainly depend on and consequently more frequent in clusters H and low height and cover of the shrubs characteristic of N. Drought tolerant species are also Potentilla this cluster. Hy locomium sp lendens in A and B is tabernaemontani and Rhytidium rugosum with probably favoured both by height and shadow of fairly high frequencies in N. The few recorded the shrubs but Rhodobryum roseum seems to lichens are also found in N. manage better in a darker situation, in A. In the plots in the northern alvars (0-T) species

Acta phytogeographica suecica 76 Plant cover in alvar junipers 107

Fig. 7. CCA analysis (all 11 • species), axis 1 and 2. B Plots belonging to the N B four main juniper • B clusters (A, B, H, N) are N B located in the total distri- bution of plots. Remain- H B N N H ing plots are indicated B N A with small squares. Ar- • N • N • B rows (not marked here) B are identical with those • N N N • A in Fig. 3. • H H B A H • N • A H • N H A A A H • • • • • A • such as Carexflacca, Hy locomium sp lendens, Pru­ Several of the bryophytes recorded in the alvar ne/la grandiflora, Artemisia oelandica and Platan­ junipers are the same as those recorded by thera chlorantha are not found at all, while Cli­ Barkman (1985) in the Dicrano-Junipereteum and macium dendroides f. depauperatum, Athalamia the Helichryso-Juniperetum. The bottom layer hyalina, Plagiomnium cuspidatum and Reboulia composition of the alvar junipers is close to hemisphaerica are only recorded in these fairly Barkman's DJ knautietosum (of S. Sweden, Ble­ dense shrubs. Poa angustifo lia and Tortula ruralis kinge) and Helichryso-Juniperetum (of Poland). are frequent in the north. There are, however, quite naturally an additional A summary of numbers and cover values of amount of several calcicolous species in the alvar species of the four clusters A, B, H, N is given in junipers, which motivate that they become referred Table 2. to a separate community. A few comments will be given below on some of Bryophytes in the juniper shrub vegetation the species which were not expected to be found at Altogether a fairly large number of bryophyte all in the alvar junipers, or at least not with such species ( > 60) were recorded in the plot material a fairly high frequency. (Table 1), both mosses and hepatics. The species Plagomnium affi ne. list includes: (1) Species of relict character, grow­ Generally growing in dense to ing preferably in shrubless alvar communities; open south Swedish deciduous forests, also in dry their survival within the junipers is certainly of to moist rich types of spruce forest. Locally fairly frequent in dry to moist meadow vegetation. - short term character (for example, Tortella tor­ tuosa, Pleuridium subulatum). (2) Species taking Now known to occur fairly frequently also in open A venula advantage of shelter from exposure, generally to dry to moist grasslands of the Alvar (cf. Bengtsson et al. 1988). There were numerous be regarded as deciduous forest species (for ex­ ample, Barbilophozia barbata, Pore/la platy­ records in the juniper shrubs, where shelter is more phylla); such species have a good chance of surviv­ efficient with regard to ecological demands of this ing and also extending their occurrences within the species. The occurrences of P. affi ne within the juniper shrubs. (3) Several species to be regarded shrubs will certainly remain more stable than in the as accidental (for example, Calliergonella cuspi­ open A venula grasslands. data, Athalamia hyalina); their chances of survival Brachythecium velutinum. Generally known as a are difficult to assess. deciduous forest species on silicious boulders and

Acta phytogeographica suecica 76 Table 1. Ordered phytosociological table by cluster analysis Four main clusters and are shown to­ H N gether with a number of small clusters obtained from plant cover analysis in Juniperus communis scrub ( 1986- 87) in alvar vegetation on Gland. Cover values according to a 1-9 abundance-cover scale (see text). Species with low frequency, not included in the table, are listed separately with indication of plot no. and cover value (within brackets). E epiphyte. (TABORD). A, B, =

Plot number 011134445 0000003444 3312113 02333444 45055 111123355555 2222222 515691890 2367893023 6790284 12128567 43421 034790545678 7534681

Cluster code A C D EFG IJKLM N OPQ RST B H 333333333 3333333333 0011122 22222222 33131 000000000000 2200222 000000000 2222222222 3344908 99999999 35843 111111111111 4255351

Number of phane rogams 011100101 0021211211 2222111 00221111 21000 121101222122 1101001 948068980 7948142376 6301220 69216316 40975 617894024835 7324993

Numbe r of mosses and lichens 110110110 0000000011 0010111 10110011 11101 000000000110 1100200 446026019 6376957410 8646324 08048861 10091 897645499056 3566087

Arabis hirsuta 1112-2 --­ ------1 - ---2221 - 1 ----11 142-- 22- 1 --1 - 2--- - 3 -- 3-- Dicranum scoparium -- 453-643 3 ---4 - 4 - 43444- 3 - 44-­ 45---21 Hypnum cupressiforme 43- 432 - 54 2 ------3 - -- 32442 2 ---- 2 -- -8614 - 36243- 27873 72--23- Avenula pratensis - 21- 2322- -453--55-- - 144-- 5 24-234-­ 4 - 43- 2554556 2 ------Carex flacca -- 42-42- 4 --2 - 552--4 44- 23-- --25--24 31174 525--5554424 . Festuca ovina - 3"42434.22 - 444- 2 - 445 44- 42- 1 - 4445423 3 ---- 344454477677 24- 44- 2 Filipendula vulgaris - 23232322 5553224353 5275- 24 3221 5 2 - 2 222-- 2 - 55- 2244544 2 ------Gal ium verum 1122---22 222---2 - 2 - 2 - 321- 1 22-4- 2 - 2 1 ---- 2222-23- 3424 ---1233 Hylocomium splendens 254223457 2545523345 33--7 - 2 1 -- 2 ---- - 343- 4 - 5------Plagiomnium affine 534575444 2 -72254 - 2 - 282--- 2 4552- 487 ---43 2 - 4 ----3 - 1 -- - 1 ----2 Rhodobryum roseum 54522- 432 - - 41385--- --122------21- ---17 4 -----42431------3 Rhytidiadelphus trique trus 314---5- 3 4488722465 3 ------7 - 443--6 --531 -----4 ------2 - Achillea mi llefolium - 11- 1 - 2 -- 1 - 22- 112-­ -- 21--1 - 1 - 2 - 2123- 2 - 3 - 4 ----- Fragaria viridis ------1 -46556- 5 - 2 -- 56- 12 41--- 223 1 - 21- 2 ----55 Geum urbanum 1 ------163- 2 - 1 ---2 ------51- 2 - 1 ----27 Agrostis capi llaris - 2 -22- 3 -- --13424523 54----2 -- 5342-- --2 ------1 - 2 --- Campanula rotundifolia 13- 22---­ --3 - 4 - 113- 2 ------2212- - 2331 4222- 42----2 Gal ium bo reale - 32---11- 43- 5--- 1 - 1 21------243--2 --254 3 - 21------2 Aspe rula tinctoria --2 --- 3 -- --1 - 3221- 1 1 - 41------22-- 1 ---- 32- 1 - 2223333 3 -----2 Prune lla grandiflora - 22------122-- 45-- 54------51---2 5- 4 --4 - 5- 2 - 5 Artemi sia oe landica - 554-- 5 -- - 1 ------5- Centaurea jacea --1 ------2 -- 1 ------2 ------2 ------Cir sium vulga re --11------12 1 2 Platanthe ra chlo rantha 12------1-1 ----- 11--1 -- Potentilla erecta -- 3 ------2 -- 24----­ -- 22---- 2 ------2 ------Rosa sp . 2 1 ----1----- 1 111 2 2 Prunus spinosa - 1 ------. --1 - 2 ----1 5------2 -2 ------4 ------1 Danthonia decumbens 2 ------2 -- 32------3- 2 -- 2- 3------Ve ronica officinal is ------2 -- -- 2 --2 - 1 -- 2 ------2 --- 23------Viola canina --22--2 ------11- 2 21----1 --41---- 2 ---- -1 ----2 ----- Ca1luna vulgaris ------5 --- - 2 ------2 ------5- 4 Plantago lanceolata ------2 ------51- 22------3 ---1 - ----2 - 234-- 3 12- 2 --- Ge ranium sanguineum 35----- Trifolium medium ------21 54----- Ve ronica chamaedrys ------2 1 ------Brachythecium rutabulum - 4 - 7 ---2 - --2 - 3 ----6 - 2 ----4 33---2 -- 6 --42 ------4 - 7 --- Pseudoscleropodium pu rum 1 ----- 1 ------3- 2 --- 55----1 --2 ------5 ------2 -- Lophocolea he terophyl la 2 -----4 ----2 -- Plagiochila porelloides 3 ------2 - Avenula pube scens --1 ------22------3 - 2 ------2 ---2 -- 2 ----- 2 --2 --- Carex ericetorum - 2 ------2 - 3343--- --3- 4 --- 1 ---- 2 ----1 - 32- 2 - Hieracium pilosella ---2 ----2 - 122------2 - 1 --211 ---1 --- Hype ricum perfo ratum 1 ----1 --­ --5- 1 ---2 - 223- 12------1 -- 2 ---- - 2 - 2 --4 ---33 Viola hi rta ------2 --2226---- 355722------5 ------5----- Homalothecium lutescens 2 - 2 - 1 - 4 -- --13--1 - 3- - 1 - 12-- 52845656 424- 3 28557577- 533 336652 - Pleurozium schrebe ri ------874 2 - 1 --2 --3 - 738 - 5-- -2 ------6-----24------1 ------Berberis vulgaris --1---- 2 Briza media --23------34------1 --- -2 -2 ---2 --23 Helianthemum nummularium --2 ----2 -- --22------2 -- --1 ------3 Helianthemum oelandi cum ---1 ------2 ---- Medicago lupulina --1 ------1 ------1 -- Poa angustifolia ------4 - 3 ---23---42 --23--- - 4 ---234 2 ------35------441544- Potentilla tabernaemontani --2 --- 2 - 1 ------2 ------2 - 2 --- 22- 2 - 1 - 423-- ---2 --- Primula ve ris ------3 - --22------2 -1 1 ------6 ------Ranunculus bu lbosus ------1 - --2 ---- - 1 - 1 --- Sedum reflexum ------2 ------2 ---4 - 4 ------4 ----43-- Barbilophozia barbata --3 ------1 - 1 -- Fissidens cristatus v. mu cr . 12------4 -----4 --­ --4 --64 2 --343-- - 1 ------3 - ----3 -- Rhytidium rugosum ------2 ------2 ------3-- 14- 2 ---71334 Drepanocladus uncinatus ---1 ------3 ------2 - Taraxacum sp . -- 2221- ---1 ---- - 1 --- - 2 ------1 - 22--212 Vincetoxicum hi rundinaria -- 5 - 52------45-- - 2 ----- 1 ---- Homalothecium sericeum - 3 ------4542------5 ------6 Porella platyphyl la 4 ------3 - 43- 4 ------Thuidium abietinum ---44-- - 1 - 2 -- 4 - - 4 - 43--41323 21764-- Hypnum cupressiforme E ----54------1 --- 43 --4 - 333 --463- 43 53- 33 ----- 2 ------333---4 Draba incana ------2 ------1 - 3 2 - 24---- - 3 --- - 3- 3 - 2 -- 32-- 2 ----1 - Silene nutans ----3------2 ------2 -----2 Ptil idium ciliare ---4 --26-- 1 ------2 ------1 --3 ------Ptil idium ciliare E - 1 ------2 -- Porella platyphylla E ----3 -- Homalothecium se riceum E - 4 ------33-

Acta phytogeographica suecica 76 Plant cover in alvar junipers 109

Table 1, cont .

Plot number 0111 34445 0000003444 33121 13 02333444 45055 111123355555 2222222 515691 890 2367893023 6790284 1 2128567 43421 034790545678 7534681

Cluster code A B C D H IJKLM N OPQ RST EFG 333333333 3333333333 0011 122 22222222 33131 000000000000 2200222 000000000 2222222222 3344908 99999999 35843 111111111111 4255351

Linum catharticum -----2------3 --33 ---2 --- Radula comp lanata - 2 --2 ------32 ----4 - 2 - --4 -- -- 2------3 - 3 ---- E Bryum capillare ------4 ---4 --1 - 43------3 --3 -- Radula complanata ------1 Brachythecium velutinum --- 4 - 4 ------4 22-5- 44- 3 ---3 -- Brachythecium velutinum - 4 --3 --2 - ---- 2 ----4 ------4 --2 - 3 - 43 33-- 3 E Junipe rus communis 1------1 - 1 - Rhamnus frangula --1 ------2 ---- Rumex acetosa ----2 ------3 ----- 1---2 Plagiothecium sylva ticum ---2 ----- 2 ---­ ------4 -- Poa compressa 4 --2---- - 2 --- -4----2 - 2 - 3 -- 4 ---4 - Ve ronica spicata 1------2 ------3------22--33- 2 ------To rtella tortuosa -1--- 2 3 3 Ditrichum flexicaule - 1 ------5- 3 --- 2 -- Barbilophoz ia barbata E - 3 --- Carex caryophyllea ------22------1 -- ---2 ----22- 3 Thuidium erectum 1 ------3 -----3 --23---4 --6-- Drepanocladus uncinatus E 1 ------1--2 - --4 -- Brachythecium rutabulum ------4 - ----3 ------3 - E Viola sp . --- 23 ------2 -111 Plagiomnium affine E ----2------2 ----2 Dicranum scopa rium E ----2 ------2 ------2 ----1 3 ------Ptil idium pulche rrimum ----2 --2 ------2 - ----1 3 -----2 E Thymus serpyllum ------2 ------3------2 -- 3- 343545 ---2 --- Mycelis mu ral is 2 - 11--- Torilis japonica ----3 --- 2 ------Homalothecium lutescens -- 3 ----- 2 - 41--- E Trifolium repens --3 ----1 21---1- To rtula ruralis - 3 ----2 - -2 ------426444- Anthoxanthum odoratum ------2--- - 2 ----1 Luzula campestris 2 ------1------2 ------2--- - 1 ----- Campylium calcareum -2 ----- E Lotus corniculatus ------1 -- ---1------1 --- Phleum phleoides ------22------3------2 --2 Festuca oelandica ----2 -- Ag r ostis gigantea ----4 -- Scapania calcarea -2 ------2 - ----3 -- Campyl ium calcareum -----2 - 2 ------3 - ----3 -- Cerastium sp. 1 ------1 --3 -­ --23---- - 1 --2 - 1 - 2 - 2 ------2 Pleurozium schreberi -2 ------E Bryum capillare - 1 ------1 ------4 --- 4 ------3- E Plagiothecium sylvaticum -----2 ------4 ---- E Tortula ruralis ---1 ---- E Lophocolea heterophylla --3 ----- E Mnium undulatum ------6 -6 ------2 - Rhyt idiadelphus squarrosus ------866 - 2 ------Botrychium lunaria ------1 - Trifolium pratense ------1 -- Cyno surus cristatus ------2-- Polygala vulgaris ----1 --- Sedum acre ------21---- Hieracium umbellatum ------1 -- ---1 ---- Vicia cracca ---1 ------1 ----- Trifolium montanum --2 - 2 ----- Carlina vulgaris ------1 ---- Globularia vulgaris ------1 ---- Artemi sia campe stris ------1 ---- Stellaria graminea ------1 -- - 1 --2 ---11 ------2 1 Sorbus inte rmedia ------1 ------Sesleria caerulea --4 -----1 --3 ---2 --- --42---- 5 - 3--2 - 5---- Senecio jacobaea ssp . gotland . ---3 ------Sanguiso rba minor -----1 ---- Ribe s uva-crispa ----1----- Pulsatilla pratensis ---1 ---- 3--3 Prunella vulgaris 1 ------Lithospe rmum officinale - 2 ------Anthyllis vulne raria ------1-1 - An tennaria dioica ------33- 2 Galium oelandicum -2------Galium aparine ----12------2 Erophila ve rna - 2 ------Convolvulus arvensis 1 ------Ci r sium acaule --2- 1 --- 1 -2 ------34 Campanula persicifol ia --215----- Ar rhenatherum elat1us -----2 ---- Agrostis vinealis ---1 ------2 ------33- 52 Pimpinella saxif raga ------11 Ag rimonia eupatoria ------2

(additional taxa listed on p. 110) Acta phytogeographica suecica 76 110 Rosen & Sj ogren

Table 1 (cont'd) Table Summarized information on the � main clusters ( A , B. No. of plots and loca2. lities for each cluster. Mean shrub and bottom- and fieldH, layer NJ. cover and (%) Additional taxa: mean height (cm) for shrubs are given , as well as number of groups of plants in each cluster. Lowest and highest recorded values are given within brackets. Acinos arvensis 18(1 ); Amblystegium serpens 44(3); A.

serpens E 44(3); Athalamia hyalina 25(3), 26(1 ); Barbula Cluster A ___ _e __ convoluta 57(1 ); B. sp. 26(3); Bellis perennis 27(2); Betula No. of sites Aleback N. Aleback 2 Aleback 1 Gynge 9 N.Gynge 1 Drostorp N.Borgholm Ebbegarde 3 4 1 1 Yentlinge Penha S. Meckleby2 S. Meckleby 1 pendula 57(1 ) Brachythecium albicans 42(3); B. populeum 2 1 ; N. Nasby Yentlinge 1 Yentllnge Penasa 3 1 1 52(3); B. populeum E 5( 1 ); B. salebrosum 48(4); B. sp. 5( 1 ); Eriksore 2 Kalkstad 3

Bryum sp. 44(2); Calliergonella cuspidata 47(2); Ceratodon Mean shrub cover ( 52-90) ( 20-90) 68 ( 40-90) 46 (23-75) Mean bottom +field cover 4772 ( 14-95) 7057 ( 8- 100) 57 ( 13-98) 75 (20- 1 00) purpureus 26(2); Cetraria glauca 19(2); C. islandica 18(3), Mean height 91 (30- 1 35) 158 ( 40-�50) 108 (50-200) 50 (20- 125)

56( 1 ), 58(3); Cladonia rangiformis 54(3), 58(3); C. Phanerogams 43 62 51 6� Eplgeic mosses 16 2� 23 sylvatica 55(4); C. symphicarpia 57(3); Climacium den­ Eplphyt ic mosses 20 6 12 4 Lichens 140 0 0 4 droides 43(2); C. dendroides f. depauperatum 25(2), 27(1 ); Total number of species 77 84 87 95 Crataegus oxyacantha 19(1), 40( 1); Ctenidium molluscum 13(4); Dicranum cf. montanum E 46(2); D. polysetum 36(4); sp. 28(3); Encalypta streptocarpa 26(1 ); D. Epilobium angustifolium 44(2); Eurhynchium sp. 31 (2); Fissidens cristatus var. mucronatus. This species of Fraxinus excelsior 44( 1 ); Geranium columbinum 27(2); G. robertianum 18( 1 ), 20(4), 21 (3); Hypogymnia physodes moderately high frequency in the junipers is worth 19(4); Lophocolea bidentata 46(4); L. sp. E 30(2); Metz­ mentioning as a relict species, being typical of the geria furcata 34(3); M. furcata E 50(4); Plagiomnium open calcareous grassland vegetation. Still, the cuspidatum 25(1 ), 28(6); Moehringia trinervia 44(4); Orchis mascula 20( 1); Orthotrichum fallax 21 (1); sp. E 4(2), fairly high and vigorous specimens recorded within 0. 5(1); Parmelia saxatilis 18(1); P. sulcata 19(4); Peltigera cf. the junipers provide an example of the well-known canina 24(1 ), 25(1 ); Pleuridium subulatum 18(2); Pohlia sp. ability of many bryophytes to withstand changes 26(2), 55(2), 57(1 ); P. sp. E 44(3); Potentilla fruticosa 36(2); Pottia intermedia 18(4); Ptilidium pulcherrimum of environmental conditions for many years, 16(3), 19(2); Racomitrium canescens 57(3); Reboulia finally becoming extinct, mainly as a consequence hemisphaerica 24(3), 25(3), 26(1 ); Rubus saxatilis 44( 1 ); of vigorous competition from invading, ecologi­ R. sp. 38(4); Rumex acetosella 57(1 ); Sedum album 25(4); Sorbus aucuparia 44( 1); Taraxacum vulgare 28(4), 43( 1); cally better adapted species. Viburnum opulus 9(1 ); Viola cf. elatior 41 (5); Weissia microstoma 18(3). Pore/la platyp hyl/a. A usually large hepatic characterizing the epiphytic-epilithic Anomodon­ tion vegetation of rich deciduous forests, generally growing in dark and extremely sheltered habitats (Sjogren 1964) . - A few records of this species moderately acid barks (cf. Isothecio-Velutinion; were made in alvar grassland (Bengtsson et al. Sjogren 1961, 1964). - Fairly frequent in the 1988), showing its unexpected ability to stand even junipers both as epigeic and epiphytic. The quite extreme desiccating conditions of open alvar large pH-amplitude of B. velutinum may facilitate habitats. The presence of P. platyp hyl/a in 5 of the its presence in such juniper shrubs on the alvar junipers recorded is also remarkable considering where sufficient shelter is provided. its ecological preferences. The pH-amplitude of Rhodobryum roseum. A species generally en­ this species is large but the preference is clearly above 5.5. Shelter provided by the juniper shrubs countered in the bottom layer of deciduous forests and in rich moist spruce forests.- The material of is apparently of principal importance and compen­ Bengtsson et al . (1988) shows an earlier unknown sates for the normally low pH of the juniper litter fairly frequent presence of R. roseum in A venula cover. However, pH of the litter carpet will cer­ and Festuca grasslands of the alvar. A high fre­ tainly accidentally become higher due to dust supply. Such conditions will most probably, at quency of the species in and around juniper shrubs was recorded. The presence of R. roseum in the least temporarily, facilitate the colonization and P. platyphylla, Mn ium open A venula and Festuca vegetation may be more survival of such species as undulatum, Rhytidiadelphus triquetrus, Th uidium unstable than in the junipers (cf. Plagiomnium af­ erectum. fine). The pH-amplitude of R. roseum is almost the same as that of Brachythecium velutinum. Barbilophozia barbata. Only one record of B. bar­ Thus, R. roseum will probably remain as a stable bata, from a type of Globularia vulgaris vegeta­ constituent of the epigeic bryophyte vegetation in tion, has been given by Albertson (1950). This the junipers, taking advantage of shelter provided. hepatic is primarily epiphytic and epilithic in

Acta phytogeographica suecica 76 Plant cover in alvar junipers 111

deciduous forests as well as in rich spruce forests

where it may occur also on the ground. - A few records of B. barbata have been given by Bengts­ son et al . (1988) from A venula pratensis grasslands. The specimens were small and poorly developed. B. barbata was also found in four of the junipers studied (always few and small specimens). This hepatic has a fairly wide pH­ amplitude (Sjogren 1964) although a substrate pH above 5.5 seems to be preferred. From that point of view, the presence of B. barbata in the juniper shrubs is not exceptional. The fairly low drought tolerance of the species makes its presence in sheltered habitats within the juniper shrubs more justified and also probably less accidental than in shrubless A venula vegetation. Radula complanata. On Oland, R. complanata is preferentially an epiphytic hepatic, growing on Fig. 8. Dense juniper with erect branches giving dry and trunks of deciduous trees such as Ulmus, Fraxinus dark conditions inside the shrub. - Alvar of Karlevi. 20 and Populus, characterized by the high pH of their September 1987. Photo: E. Rosen. bark surfaces. Moderately acid barks may become colonized if dust-impregnated. The pH preference

of R. complanata lies above 5.5. - The species was recorded as an epiphyte in several of the tween the northern and the southern parts of the junipers investigated. Its presence on acid juniper shrubs, with a correlation also to the various barks, not earlier recorded, is probably facilitated shapes of shrubs. only by supply of calcareous dust. R. complanata The present study aimed at a larger scale survey may colonize in alvar juniper shrubs at an earlier where also amplitudes of species and geographic stage than the much less drought tolerant hepatics differences could be found. There is a small Pore/la platyp hylla and Barbilophozia barbata. geographic difference between, for example, the four main clusters, considering that 9 samples out of 12 in cluster N are from Gynge. The dense shrubs known, for instance, from Kalkstad fall Discussion within cluster H, etc. There is a wide variation also on Oland in struc­ In this survey there were good correlations found ture of the shrubs, comprising very dense types and for all variables except exposure. The fairly low lush ones combined with either prostrate or erect number of samples combined with a big plot size growth. Moderately high junipers may have bran­ is probably the explanation. ches more or less at an angle of 45°, permitting Detailed studies have been made in Poland (by light to penetrate between them. Dense shrubs with E. Jaworska) showing various frequencies of cer­ upright branches permit much less light to tain species under the canopy or at the edge of dif­ penetrate (Fig. 8). ferently shaped Juniperus communis, also related In some shrubs light may reach the stembases to stages of succession (Falinski 1986). from the side whereas in others this is not the case. Clear differences in plant cover composition A more comprehensive recording of relations be­ related to junipers were found in a very large data tween plant cover composition and environmental set of microclimatic measurements made in the conditions would need a research program where Netherlands by Barkman et al. (1977). He found microclimatic as well as soil properties become pronounced differences in plant cover, e.g. be- carefully studied. Nonetheless, this survey has

Acta phytogeograp hica suecica 76 112 Rosen & Sj ogren

shown some clear correlations which may become Falinski, 1. B. 1986. Vegetation dynamics in temperate useful in work involving nature conservation. Also lowland primeval forests. Ecological studies in Bialowieza forest. - Geobotany 8: 1-537. our knowledge of ecological amplitudes of several Grolle, R. 1983. Hepatics of Europe including the species, vascular plants as well as bryophytes, has Azores; an annotated list of species, with synonyms improved. from the recent literature. - J. Bryol. 12: 403-459. From a phytosociological point of view, our Hill, M. 0. 1979. DECORANA: a FORTRAN program clusters have been compared with associations and for detrended correspondence analysis and reciprocal averaging. - Section of Ecol. and Systematics, Cor­ subassociations distinguished by Barkman (1985) nell Univ., Ithaca, New York. and found to be fairly different in their stocks of Krahulec, F., Rosen, E. & van der Maarel, E. 1986. Pre­ species. The closest similarities are with Barkman's liminary classification and ecology of dry grassland DiCrano-Juniperetum (NE subassociation knautie­ communities on blands Stora Alvar (Sweden). - tosum) and the Polish Helichryso-Juniperetum. Nord. 1. Bot. 6: 797-809. Konigsson, L.-K. 1968. The Holocene history of the Great Alvar of Oland. - Acta phytogeogr. suec. 55: Acknowledgements. For financial support of this in­ 1-172. vestigation, conducted within the framework of a larger Rejmanek, M. & Rosen, E. 1988. The effects of coloniz­ project, we are grateful to the National Swedish En­ ing shrubs (Juniperus communis and Potentilla fruti­ vironment Protection Board (SNV). cosa) on species richness in the grasslands of Stora For various kinds of assistance during computer Alvaret, Oland (Sweden). - Acta phytogeogr. suec. analysis we are most grateful to Eddy van der Maarel, 76. Christina Skarpe, Rik Leemans and Mikael Lonn. Folke Rosen, E. 1982. Vegetation development and sheep graz­ Hellstrom copied the photos and Marta Ekdahl typed ing in limestone grasslands of south Oland, Sweden. the MS. Nigel Rollison helped us with a linguistic revi­ -Acta phytogeogr. suec. 72: 1-104. sion of the MS. - 1988a. Shrub expansion in alvar grasslands on bland. - Acta phytogeogr. suec. 76. - 1988b. Development and seedling establishment within a 1uniperus communis stand on Oland, Sweden. - Acta bot. neerl. (in press) Santesson, R. 1984. The lichens of Sweden and Norway. · References - Stockholm. 333 pp. Sjogren, E. 1961. Epiphytische Moosvegetation in Laub­ Albertson, N. 1950. Das grosse siidlicheAlvar der Insel waldern der Insel Oland (Schweden). - Acta bland. Eine pflanzensoziologische Ubersicht. - phytogeogr. suec. 1-149. 44: Svensk bot. Tidskr. 44: 269-331. - 1964. Epilitische und epigaische Moosvegetation in Barkman, J. J. 1985. Geographical variation in associa­ Laubwaldern der Insel Oland (Schweden). - Acta tions of juniper scrub in the Central European plain. phytogeogr. suec. 48: 1-184. - Vegetatio 59: 67-7 1. Sterner, R. 1948. Olands flora. - Oland I, Lund, pp. Barkman, J. J., Masselink, A. K. & de Vries, B. W. L. 91-235. 1977. Uber das Mikroklima in Wacholderfluren. - Ter Braak, C. 1. F. 1987. CANOCO - a FORTRAN Ber. int. Symp. int. Verein. Veg.-Kunde 1975: program for canonical community ordination by 35-81. (partial) ( detrended) (canonical) correspondence Bengtsson, K., Prentice, H. C., Rosen, E., Moberg, R. analysis, principal components analysis and redun­ & Sjogren, E. 1988. The dry alvar grasslands of dancy analysis (version 2.1). - TNO, Inst. of appl. bland: ecological amplitudes of plant species in rela­ computer sci., Wageningen, 95 pp. tion to vegetation composition. - Acta phytogeogr. Tutin, T. G., Heywood, V. H., Burges, N. A., Valen­ suec. 76. tine, D. H., Walkers, S. M. & Webb, D. A. 1964- Corley, M. F. V., Grundwell, A. C., Diill, R., Hill, 80. Flora Europaea, 1-5. -Cambridge. M. 0. & Smith, A. J. E. 1981. Mosses of Europe van der Maarel, E., 1anssen, J. G. M. & Louppen, and the Azores; an annotated list of species, with 1. M. W. 1978. TABORD. A program for structur­ synonyms from the recent literature. - 1. Bryol. 11: ing phytosociological tables. - Vegetatio 38: 143- 609-689. 156. Enckell, P. H., Konigsson, E. S. & Konigsson, L.-K. Westhoff, V. & van der Maarel, E. 1978. The Braun­ 1979. Ecological instability of a Roman Iron Age Blanquet approach. - Classification of plant com­ human community. - Oikos 33: 328-349. munities, 2nd ed. The Hague. pp. 287-399.

Acta phytogeographica suecica 76 Reproductive regeneration in grazed and ungrazed limestone grassland communities on Oland Preliminary results Graciela Rusch

Abstract Rusch, G. 1988. Reproductive regeneration in grazed and ungrazed limestone grassland com­

munities on bland. Preliminary results. - Acta phytogeogr. suec., 76, Uppsala. ISBN 91-721 0-07 6-l.

The significance of reproductive regeneration in grazed and ungrazed limestone grassland communities was estimated by recording the number of seedlings of the different species oc­ curring in experimentally created gaps and control plots (10 cm 10 cm). x Seedlings of some perennial graminoids were only found in the close-turf canopy. Perennial herbs germinate mostly in spring and germination was enhanced in gaps. The closed turf of the ungrazed site constitutes a hinder for germination of the latter species . Germination of summer monocarpic species was particularly abundant in the short turf of the grazed com­ munity. Seedlings of winter monocarpic species occurred mainly in gaps. The results indicate that the persistence of these species is highly related to the possibility of finding a suitable environ­ ment for growing and producing seeds and that this possibility increases with increasing turn­ over of gap formation. The impact of gap formation on germination and the relationship between the formation of natural gaps and the possibilities of persistence of the species in the community are discussed.

Graciela Rusch, Institute of Ecological Botany, Uppsala Un iversity, Box Upp­ 559, 75 1 22 sala, Sweden.

Introduction proved to be satisfactory when trying to elucidate mechanisms of coexistence in plant communities. The mechanisms through which a particular com­ It appears to be easier to think of a large number munity persists have recently become the subject of of limiting resources in animal communities than a large number of experimental and theoretical in plant communities where all plant species de­ studies. pend on a small number of essential nutrients The earlier models of community organization (Grubb 1977, Newman 1982). suppose a system in equilibrium with its environ­ In later models, changes in the environment and ment. The environment is assumed constant, or their importance on the dynamics of some com­ fluctuations are considered to be irrelevant for the munities have been recognized (White 1979, Sousa community organization. Competition is the main 1984). Disturbance can be understood as a sudden interaction among species and thus controls species change in resource availability which is expressed diversity. At the equilibrium point, species coexist as a detectable change in population response because their requirements do not overlap each (Bazzaz 1983). Its significance has been recognized other in the use of limiting resources. Thus, there as an important factor in community organization. are at least as many limiting resources as species Efforts have been made to classify disturbance which can coexist (Chesson & Case 1986). regimes according to their intensity, frequency and Although possibly successful in describing cer­ predictability (Bazzaz 1983, Sousa 1984). tain animal communities, this model has not Hypotheses on patchily distributed resources

Acta phytogeographica suecica 76 114 Graciela Rusch

Fig. 1. The structure of the turf that is produced when the com­ munity is grazed is considered of particular significance in keeping large number of species coex­ isting. - Grazed site at Gett­ linge. November 1987.

and microsite scale disturbance related to species derstand mechanisms of coexistence because they regeneration in a community have been put for­ are usually very rich in species (Grubb 1976, ward as a possibility for species having the same Willems 1983, During et al . 1985, Mitchley & trophic niche to coexist (Platt 1975, Whittaker & Grubb 1986). Levin 1977, Auerbach & Shmida 1987). Related to This study was carried out on the calcareous these hypotheses is the "regeneration niche" grasslands occurring on "Stora Alvaret", the big theory put forward by Grubb (1977). It is stated limestone plateau of the island of Oland, in the that disturbance or internal forces (such as death Baltic. The great impact of man on this landscape of individuals) create vegetation gaps with differ­ began in the first centuries A.D. The settlers from ent environmental characteristics according to this time used some arable fields and had grazing their shape and size and to the moment when they animals. These people helped to create for the first are opened. Thus, the dynamics of gap formation, time a more coherent open landscape on the Great matched with the occurrence of propagules, would Alvar which is characterized by its flatness, its largely determine the persistence of a species in the shallow soils and the dominance of grassland community. In other words, the probability of per­ vegetation (Rosen 1982). It seems clear that graz­ sistence of a species in the community depends on ing has been and still is an important factor in the the density distribution of propagules, together organization of the structure and functioning of with the probability of occurrence of a place the grassland community. Species richness in the suitable for regeneration. grazed alvar communities is high, even down to -·. Calcareous grassla , ds have· .p-articularly at­ such smalPareas as 1 dm2 (van der Maarel, in tracted the att�rihon of ecologists who try to un- press). . Acta phytogeograpfii�i suecica 76 __-, ...... Reproductive regeneration in limestone grass/ands 115

Fig . 2. The exclusion of grazing implies the development of a denser and taller canopy and a change in gap formation dynamics. - Ungrazed site at Kleva. November 1987.

Fine-scale spatial heterogeneity has been con­ The aims of this contribution are: sidered of particular significance in the regenera­ To present some experimental evidence of the * tion phase of species in calcareous grasslands (Fen­ importance of reproductive regeneration in one ner 1978, Silvertown 1981a, Silvertown & Wilkins of the most conspicuous grassland communities

1983). When not grazed, the grassland develops of the Alvar, viz. the Veronica sp icata - into a closed turf (Rosen 1982). Low seedling den­ A venula pratensis association (Krahulec et al. sities have been noted in dense turfs (Miles 1973) 1986). and although experimental evidence is incomplete, To compare the significance of reproductive * the establishment of new plants from seed appears regeneration in grazed and ungrazed com­ to be rather uncommon in many closed herbaceous munities. communities (Miles 1972). Thus, the particular To estimate the impact of gap formation on the * structure of the turf that is produced when the reproductive regeneration of grassland species. community is grazed, concerning canopy density To interpret the relationship between the forma­ * and height, size of the individuals, size of vegeta­ tion of natural gaps and the probabilities of per­ tion gaps originated by death of individuals or by sistence of the species in the community. hooves, is considered of particular significance in This contribution is the first report on a larger keeping a large number of species coexisting. The study on reproductive regeneration associated with exclusion of grazing implies the development of a mechanisms of species coexistence. In it, the estab­ denser and taller canopy and a change in gap for­ lishment of seedlings in the turf of grazed and mation dynamics (Figs. 1 and 2). ungrazed communities and in gaps with different environmental characteristics (different sizes,

Acta phytogeographica suecica 76 116 Graciela Rusch

Fig. 3. Gap opened in the summer 1986. Seedlings were recorded when the cotyledons were present and some in­

dividuals were marked with plastic rings (e.g. Trifolium campestre, Festuca ovina). - Grazed site at Gettlinge. November 1987.

opened at different times of the year) are com­ only 10 cm. These areas are never flooded and they pared. undergo no or little frost action in the winter (Krahulec et al. 1986). The first site, at Gettlinge (56°23'N 16°27'E),

· had been grazed by cattle during summer and Materials and methods autumn until the beginning of the experiment. The turf is 3-10 cm tall and it is characterized by a tiny The study was carried out in two sites of calcareous micro-scale pattern. An average of 9 vascular grassland on bland's Stora Alvar, assigned to the species occur per 100 cm2 (Fig. 1). The second Veronica sp ica fa - A venula pratensis association. site, at Kleva (56°33'N 16°28'E), has not been The dominants are the grass species Festuca ovina, grazed by domestic herbivores since 1981. The turf Agrostis vinealis and Avenula pratensis, the cha­ pattern is now dominated by larger tussocks of the maephyte Helianthemum oelandicum, and the grasses and larger individuals of the forbs (Fig. 2) . perennial herbs Filipendula vulgaris, Helian­ Vegetative parts are 10-25 cm tall and a 2-6 cm themum nummularium and Anthyllis vulneraria. thick layer of mosses can cover the soil surface. Both sites are on relatively deep soils ( > 25 cm), According to the scale of the community pat­ with a pH between 5.5 and 6.8, with traces of free tern, largely determined by the size of the adult in­ carbonates in the profile, apparently in relation to dividuals, the most frequent sizes of the natural wind-transported material and to the calcareous gaps produced by the death of individuals and by bedrock which is sometimes found at a depth of local disturbance (as those produced by hooves)

Acta phytogeographica suecica 76 Reproductive regeneration in limestone grasslands 117

Fig. 4. Control plot laid out in late April 1986. The short turf produced by grazing is suitable for some seedlings which can profit of a less exposed environment than that of the gaps. - Grazed site at Gettlinge. November 1987.

were considered to be between 10 cm2 and 100 September correspond to those which were pro­ cm2• Gaps of both sizes were opened in the spring duced before the beginning of June (viz. in spring), and in the summer 1986, but only those 100 cm2 between June and July (viz. during the summer) large that were created in spring will be analysed in and between July and September (viz. in late sum­ the present contribution. The significance of mer and in autumn), respectively. reproductive regeneration was estimated by re­ Seedlings were recorded when the cotyledons cording the number of seedlings that occurred in were present and the species name identified after 10 cm 10 cm gaps and control plots of the same marking some of the individuals in the field or by x size (Figs. 3 and 4). growing them in the laboratory. Species that could Gaps were created in spring (late April) by cut­ not be identified and that occurred rarely and did ting the green biomass and removing the dead ma­ not survive were grouped as ''unidentified''. In the terial and the litter. The soil surface was then case of the monocotyledons, the seed cover re­ lightly disturbed with a knife. mains attached to the seedlings for a long time and Pairs of permanent control plots and gaps were this was used as a clue to differentiate between laid out at 10 cm distance from each other and 1 species. It was also possible to recognize a charac­ m between pairs, along 4 transects. Each plot was teristic morphology of the most frequent marked by using galvanized-wire frames. monocotyledonous seedlings. At each site 50 pairs of plots were recorded in Nomenclature follows Flora Europaea (Tutin et June and in July, and 35 pairs in September 1986. al . 1964-1980). The seedlings recorded in June, July and

Acta phytogeographica suecica 76 118 Grade/a Rusch

Fig. 5. Total number of seedlings recorded in June (Jun), July (Jul) and September (Sep) at the grazed site in 50 control plots (10 cm 10 cm). PG, PH, Sand W x correspond to species groups ac­ cording to Table 1.

0 Ill

Jun Jul Sep Jul Sep

PG PH w

Fig. 6. Total number of seedlings

1573 recorded in June and in Septem­ ber in 50 control plots (10 cm x 10 cm) at the grazed site (G) and the ungrazed site (UG). PG, PH, S and W correspond to species groups according to Table 1 .

... ci

PG PH s w

Results have been over-estimated at the first recording date due to the fact that Fes tuca ovina, the species that The complete species list for both sites includes 75 accounts for most of the recorded seedlings, forms species. Seedlings of 32 of these species were a bank with seedlings that remain as such for long recorded during one growing season in 200 plots periods. Thus, both newly germinated and several on an area of about 100 m2 (Table 1). months old seedlings were recorded in June. The relative importance of germination of the Perennial herbs present a marked germination different groups (viz. perennial graminoids, peren­ flush in spring and little germination in summer. nial forbs, summer and winter monocarpic species) Summer and winter monocarpic species showed during the growing season is shown in Fig. 5. clear concentrated flushes of germination in spring Perennial graminoids germinate during the whole and in autumn respectively. growing season although a larger number of seed­ The amount of seedlings of perennial lings were recorded in June. This number might graminoids was larger in the controls than in the

Acta phytogeographica suecica 76 Reproductive regeneration in limestone grasslands 119

Fig. 7. Total number of seedlings recorded in June and in Septem­ ber in 50 gaps (10 cm 10 cm) x at the grazed site (G) and the ungrazed site (UG). PG, PH, S and W correspond to species groups according to Table 1.

CD ci

.... ci

G UG G UG PG PH s w

Table 1: List of species germinating during the growing season 1986.1 same for the grazed and ungrazed sites and for the

1. Agrostis vinealis PH 18. Pulsatilla pratensis PG gaps and the controls. The differences between 2. Anthoxanthum odorat um 19. Ranunculus bulbosus 3. A venula pratensis 20. Sedum acre these treatments originated mainly in the relative Carex sp. and 21. Taraxacum - Erythrosperma 4. Luzula campestris 1 22. Thym us serpyllum contribution of the individual species and in the 5. Festuca ovina 23. Vero nica spicata absolute total numbers of each of them. Euphrasia stricta PH 6. Achillea millefolium 24. Antennaria dioica Linum catharticum Germination in autumn had a relatively differ­ I 7. 25. 8. Anthyllis vulneraria 26. Trifolium dubium 9. Arabis hirsuta ent significance for the species of this group in the 27. Arenaria leptoclados 10. Asperula tinctoria W 11. Filipendula vulgaris 28. Bromus hordeaceus gaps and the control plots for the grazed and 12. Galium verum 29. Cerastium semidecandrum 13. Helian themum nummularium 30. My osotis stricta ungrazed sites. A larger number of seedlings were 14. Helian themum celandicum 31. Trifolium campestre 15. Lotus corniculatus 32. Veronica arvensis produced in the gaps in the ungrazed site than in 16. Plantago lanceolata the controls, where only few species produced 17. Potentilla tabernremontani uI 33. Unidentified species seedlings (Figs. 9c and 9d). The grazed site showed 1 PG: Perennial graminoids, PH: perennial herbs, summer monocarpic 8: species, winter monocarpic species. a different pattern. Fewer species produced seed­ W: lings in the gaps than in the control plots but the total number of seedlings was larger in the gaps and strongly concentrated in one species, Poten­ tilla tabernaemontani. gaps in both the grazed and the ungrazed sites The numbers of seedlings of summer and winter (Figs. 6 and 7). These large numbers, in the case of monocarpic species showed similar trends in the the grazed site, were mainly due to one species, grazed and ungrazed sites (Figs. 6 and 7). The sum­ Festuca ovina (Figs. Sa, Sb, 9a and 9b). In the mer monocarpic species, particularly Linum ungrazed site, on the other hand, the amount of catharticum produced seedlings mainly in the con­ seedlings of graminoids was more evenly trol plots (Figs. Sa, Sb , Se and Sd) and, further­ distributed among other species (Figs. Se, Sd, 9c more, there was a large difference in the number of and 9d). seedlings between control plots and gaps in the An opposite trend was shown in the case of the grazed site. Winter monocarpic species, on the perennial herbs. A larger amount of seedlings grew other hand, occurred mainly in gaps (Figs. 6 and in the gaps than in the controls, both in the grazed 7). This group is represented by a larger number of and the ungrazed sites (Figs. 6 and 7). The number species than the summer monocarpic species (Figs. of species that produced seedlings was roughly the 9a, 9b , 9c and 9d). In the grazed site all the species

Acta phytogeographica suecica 76 120 Graciela Rusch

a c

w PG PH

b d

� �

� !

� �

e e

Fig. 8. Number of seedlings per species recorded in June in 50 gaps and control plots (10 cm 10 cm). Numbers x correspond to species according to Table 1. Species grouping (PG, PH, S, W and U) follows that in Table 1. (a con­ trol of the grazed site; b gap at the grazed site; c control of the ungrazed site; d gap at the ungrazed site.)

were more evenly represented and with larger contributes to the persistence of the species in the numbers than in the ungrazed site. community (Grubb 1977). For this reason the ex­ periment will be continued under different en­ vironmental conditions and the fate of seedlings Discussion will be followed. Nonetheless, these observations allow us to Observations made during one growing season evaluate the significance of regeneration provide only a partial description of the import­ mechanisms in communities with different canopy ance of reproductive regeneration in the com­ structures. The seasonality of the production of munities studied and it might lead to a static and seedlings of the different species, which is less sen­ simplified picture of its significance for the indi­ sitive to yearly variation of the environmental con­ vidual species. Production of seeds, germination ditions, can also be described. and establishment of seedlings can vary signifi­ The results presented show that germination is a cantly according to different climatic conditions process that occurs for a large number of perennial throughout the years and this variation may con­ and monocarpic species in these communities. The stitute an important source of heterogeneity which different significance that reproductive regenera-

Acta phytogeographica suecica 76 Reproductive regeneration in limestone grasslands 121

a c

132 122

� �

� � �

� � r

r-

e e

rf JJ\.. !7i1 I rr 1- 1 2 3 4 56 7 8 91011 12 131415161718192021 2223 2425 2627 28 29 30 31 32 33 � � w

b d

Fig. 9. Number of seedlings per species recorded in September in 35 gaps and control plots (10 cm 10 cm). x Numbers correspond to species according to Table 1. Species grouping (PG, PH, S, W and U) follows that in Table 1. (a-d, see Fig. 8.)

tion has in grazed and ungrazed communities is likely to be the factor delaying germination. It has also clearly illustrated. also been mentioned (see Results) that this species Fig. 5 shows how germination occurs for the dif­ forms a seedling bank and that this might have led ferent groups of species during the growing season. to an overestimation of the number of seedlings Perennial graminoids seem to be able to germinate occurring in the control plots in the spring, when during the whole season, although climatic condi­ the first observations were made. Fenner (1978) tions, particularly the occurrence of summer observed that many seedlings have the ability to droughts, probably are important factors that continue to live apparently without any growth. determine the amounts of seedlings occurring in He refers to the work of Chippindale ( 1948) where the summer. Festuca ovina is the species which the ability to suspend growth for long periods was mostly contributes to this group. It has been noted found only in grass species. in calcareous grasslands occurring in Britain that Fenner (1978) has shown in laboratory ex­ this species forms a transient seed bank, with seeds periments that closed turfs hinder germination of germinating in the autumn (Thompson & Grime both close-turf species and ruderals, although 1979). It has been argued by these authors that the twice as severe in the latter ones. Miles (1972, 1973) lack of moisture rather than high temperatures is has also noted the occurrence of very low seedling

Acta phytogeograp hica suecica 76 122 Gracie/a Rusch

densities in closed turfs and he argues that vacant and have a rapid growth, flowering and fructifica­ niches or "safe-sites" (sensu Harper 1977) are rare tion during the growing season. The relatively in undisturbed vegetation with a closed canopy. short and less dense canopy that develops under The results presented in this study show that the grazing is particularly favourable for the summer dense canopy that develops when grazers are ex­ monocarpic species. A much smaller number of cluded is particularly suitable for seedlings of the seedlings of this group was produced both in the perennial graminoids. A larger number of species undisturbed canopy of tJle ungrazed site and in the of this group produced seedlings in the ungrazed gaps of both sites, as compared with those pro­ site although the total number of seedlings of the duced in the grazed controls. whole group was smaller than in the grazed site. Winter monocarpic species constitute · a larger On the other hand, the gap environment was par­ group than the summer monocarpic species. ticularly unfavourable for the production of seed­ Regular occurrence of gap formation seems to be lings of this group in both sites. meaningful for their persistence. The observations Perennial herbs germinate mainly in spring and made on the alvar grassland show that seedlings of only little in summer and autumn. The number of the winter monocarpic species occurred largely in species of this group which produced seedlings was the gaps. The adult individuals of Arenaria lep­ the same in the grazed and ungrazed sites. The toclados, Bromus hordeaceus, My osotis stricta, number of seedlings produced was anyhow largely Trifolium campestre and Veronica arvensis were hindered by the closed canopy of the ungrazed usually not taller than 5 cm in the spring following community. This fact may be due to smaller these observations. They had almost always one amounts of available seeds and/ or to unfavourable stem (or 3 leaves in the case of B. hordeaceus), ex­ conditions for germination and production of tremely tiny leaves, usually 1 flower or fruit per in­ seedlings produced by a dense canopy. The exhaus­ dividual and a very simple root system. These tion of the seed bank when the chances of seed in­ phenotypical characteristics indicate low com­ put are reduced might be a reason for low germina­ petitive ability in these species. tion. Sarukhan (1974) studied the fate of seed Silvertown (1981b) showed that species having samples of three species of Ranunculus sown in a small seeds germinate in autumn, undergo the grassland canopy. The results showed that R. harsh conditions of the winter and grow and pro­ repens lost 50 per cent of its seed pool because of duce seeds, in the case of the annuals, in spring. predation in the first 6 months. The seed pool of Species having large seeds are able to establish in R. bulbosus was rapidly depleted as a result of ger­ closer canopies, they germinate in spring and can mination and, after 15 months, the seed pool was grow rapidly under more favourable conditions in reduced to about 20 per cent. These results indicate the same growing season. He argues that the that the seed bank can be greatly reduced if no seed species with small seeds have been displaced to rain occurs. open areas that occur more frequently at the end of The comparatively larger amounts of seedlings the growing season because of their low com­ of perennial herbs produced in the gaps of the petitive ability. Following Silvertown's argumen­ ungrazed site than in the controls show that, at tation for seed size, the occurrence of winter least partly, the structure of the closed canopy is a monocarpic species in gaps, the moment at which reason for the minor importance of the reproduc­ they germinate and the consequent exposure to tive regeneration of this group of species. Gross winter conditions before fruit-bearing might be ex­ (1984) argues that some species are sensitive to plained by their low competitive ability. both irradiance and spectral quality and that this mechanism acts as an effective "gap detector" which prevents emergence where seedling grow and survival would be low. Conclusions Monocarpic species have very determined ger- mination flushes in time. Summer monocarpic It may be concluded that the closed canopy of the species, as Euphrasia stricta, germinate in spring ungrazed site constitutes a hinder to germination

Acta phytogeographica suecica 76 Reproductive regeneration in limestone grasslands 123 for most of the species of the community. All the References species presented fewer numbers of seedlings both Auerbach, M. & Shmida, A. 1987. Spatial scale and the in control plots and gaps of the ungrazed site as determinants of plant species richness. - Trends in compared with the grazed plots. There were, none Ecology and Evolution 2: 238-242. the less, seedlings of some grasses that only oc­ Bazzaz, F. A. 1983. Characteristics of populations in curred in the closed turf. The short turf produced relation to disturbance in natural and man-modified ecosystems. - Ecol. Stud. 44: 259-275. by grazing was suitable for some species which can Chesson, P. L. & Case, T. J. 1986. Nonequilibrium probably tolerate some shade and thus profit from community theories: Chance, variability, history and a less exposed environment than that of the gaps. coexistence. - Community Ecology. New York. pp. Some species germinated largely in the gaps. This 229-239. shows that gaps constitute patches of particular en­ Chippindale, H. G. 1948. Resistance to inanition in grass seedlings. -Nature, London 161: 65. vironmental characteristics in the canopy matrix, During, H. J., Schenkeveld, A. J., Verkaar, H. J. & having an own dynamic in the abiotic conditions Willems, J. H. 1985. Demography of short-lived throughout the year. forbs in chalk grassland in relation to vegetation These preliminary results indicate that the per­ structure. - The population structure of vegetation. sistence of some species in the community is highly Dordrecht. pp. 341-370. Fenner, M. 1978. A comparison of the abilities of col­ related to their possibility of finding a suitable en­ onizers and closed-turf species to establish from seed vironment for growing and producing seeds and in artificial swards. - J. Ecol. 66: 953-963. that this possibility increases with increasing turn­ Gross, K. L. 1984. Effects of seed size and growth form over of gap formation. The low frequency with on seedling establishment of six monocarpic peren­ which gaps are formed in the ungrazed community nial plants. - J. Ecol. 72: 369-387. Grubb, P. J. 1976. A theoretical background to the con­ might thus be an important reason for the lower servation of ecologically distinct groups of annuals values in seedling production when compared with and biennials in the chalk grassland ecosystem. - the grazed site. Bioi. Conserv. 10: 53-76. - 1977. The maintenance of species-richness in plant communities: the importance of the regeneration niche. - Bioi. Rev. 52: 107-145 . Harper, J. L. 1977. Population biology of plants. - London. 892 pp. Krahulec, F., Rosen, E. & van der Maarel, E. 1982. Pre­ liminary classification and ecology of dry grassland Acknowledgements. This work is part of the project communities on bland's Stora Alvar (Sweden). - "Maintenance of species diversity and mechanisms of Nord. J. Bot. 6: 797-809. coexistence in Alvar grasslands". It is supported by Miles, J. 1972. Experimental establishment of seedlings grants from NFR (The Swedish Natural Science Re­ on a southern English heath. Ecol. 60: - 1. search Council). I thank E. van der Maarel for the super­ 225-234. vision of the work and for his comments on the manu­ - 1973. Early mortality and survival of self-sown seed­ script. I am particularly grateful to E. Rosen for his field lings in Glenfeshie, lnverness-shire. - J. Ecol. 61: assistance and for his help with the identification of the 93-98. seedlings. I also thank A. Reurslag for her assistance in Mitchley, J. & Grubb, P. J. 1986. Control of relative the field, C. Andersson and M. van der Maarel for the abundance of perennials in chalk grassland in south­ revision of the text and M. Natiello for his help with the ern England. - J. Ecol. 74: 1139-1166. figures. My work is being carried out during the tenure Newman, E. I. 1982. Niche separation and species diver­ of a Swedish Institute scholarship. sity in terrestrial vegetation. - The plant community as a working mechanism. Oxford. pp. 61-77. Platt, W. J. 1975. The colonization and formation of equilibrium plant species associations on badger disturbances in a tall-grass prairie. - Ecol. Monogr. 45: 285-305. Rosen, E. 1982. Vegetation development and sheep graz­ ing in limestone grasslands of South bland, Sweden. - Acta phytogeogr. suec. 72: 1-104. Sarukhan, J. 1974. Studies on plant demography: Ranunculus repens L., R. bulbosus L. and R. acris L.

Acta phytogeographica suecica 76 124 Graciela Rusch

Reproductive strategies and seed population 11. in the seed banks of herbaceous species in ten con­ dynamics. - J. Ecol. 62: 151-178. trasting habitats. - J. Ecol. 67: 893-921. Silvertown, J. W. 198 1a. Micro-spatial heterogeneity Tutin, T. G., Heywood, V. H., Burges, N. A., Valen­ and seedling demography in species-rich grassland. tine, D. H., Waiters, S. M. & Webb, D. A. 1964- -New Phytol. 88: 117-128. 1980). Flora Europrea, 1-5. - Cambridge. 1981b. Seed size, life span, and germination date as van der Maarel, E. (in press). Species diversity in plant coadapted features of plant life history. Nat. -Am. communities in relation to structure and dynamics. 118: 860-864. - Proc. Int. Symp. Vegetational Structure, Utrecht. Silvertown, J. W. & Wilkin, F. R. 1983 . An experimen­ SPB Publ. The Hague. tal test of the role of microspatial heterogeneity in the White, P. S. 1979. Pattern, process and natural disturb­ co-existence of congeneric plants. - Bioi. J. Linn. ance in vegetation. - Bot. Rev. 45: 229-299. Soc. 19: 1-8. Whittaker, R. H. & Levin, S. A. 1977. The role of Sousa, W. P. 1984. The role of disturbance in natural mosaic phenomena in natural communities. communities. -A. Rev. Ecol. Syst. 15: 353-391. Theoret. Pop. Bioi. 12: 117-139. Thompson, K. & Grime, J. P. 1979. Seasonal variation

Acta phytogeographica suecica 76 Biomass structure of limestone grasslands on Oland in relation to grazing intensity

Argenta Titlyanova, Graciela Rusch & Eddy van der Maarel

Abstract Titlyanova, A., Rusch, G. & van der Maarel, 1988. Biomass structure of limestone E., grasslands on bland in relation to grazing intensity. Acta phytogeogr. suec. ISBN - 76. 91-7210-076-1.

Alvar vegetation can be regarded as steppe vegetation both from the physiognomic, floristic­ geographical and ecological points of view. In this study, some biomass properties of alvar grassland under three intensities of human impact (ungrazed, moderately grazed and overgrazed) were compared with those of true steppes. The overgrazed community shows qualitative changes from the floristic point of view. Perennial and annual ruderal species replace the dominant alvar grassland species. Values of green biomass of vascular plants decrease with increasing grazing intensity, in agreement with results obtained for true steppes. Lichens, which are particularly conspicuous in alvar grasslands compared to true steppes, had highest biomass values in the moderately grazed community. Similarities and differences in above- and below-ground biomass between alvar grasslands and true steppes are discussed.

Argenta Titlyanova, Institute of Soils and Agrochemistry. Siberian Branch of the Academy of Sciences, No vosibirsk USSR . 630099, Graciela Rusch and Eddy van der Maarel, Institute of Ecological Botany, Uppsala University, Box Uppsala, Sweden. 559, 75 1 22

Introduction ous massif of limestone lying very close to the sur­ face explains the low water storage capacity of Alvar vegetation has been considered to be a these soils. Also later authors regarded Gland's unique steppe-like phytogeographic formation Alvar as a steppe (Du Rietz 1925: "the Baltic which resembles true steppes occurring in Eastern steppe region", see also Albertson 1950), and Europe and Asia. Witte (1906) was probably the Krahulec et al . (1986) pointed to the syntax­ first to argue that alvar vegetation should be re­ onomical relationship between alvar and true garded as steppe vegetation both from the physio­ steppe vegetation. gnomic, floristic-geographical and ecological A further similarity is that both alvar and east­ points of view: dominance of grassland vegetation, ern steppe are subject to grazing in various degrees absence of trees, presence of Southeast European of intensity. Grazing on the alvar by domestic elements in its flora, and the predominance of animals has occurred since the first centuries A.D. xerophytes. True steppes owe their xerophytic and this has contributed to maintain the character­ character mainly to climatic factors, especially a istic openness of the landscape. hot and dry summer, while alvar vegetation has In this study we were particularly interested in this character because of edaphic factors. Alvar comparing some biomass properties of alvar vegetation occurs on thin soils that originated grassland, at different intensities of human im­ mainly from the Ordovician limestone bedrock pact, with those of true steppe vegetation. Plant (Rosen 1982). The presence of an almost continu- biomass structure, considered as the pattern of dis-

Acta phytogeographica suecica 76 126 Titlyanova, Rusch & van der Maarel

tribution of plant material over the various above­ main part of the green phytomass is made up of ground and below-ground components of the eco­ species which are resistant to trampling and able to system, is specific for a grassland system and it regenerate rapidly after being grazed (Gorshkova changes together with species composition under 1954, Titlyanova et al. 1983). Under heavy graz­ grazing. ing, the species composition changes drastically as The description of these parameters of the well. In European true steppes the typical steppe grassland would also provide additional ecological species, notably tufted grasses, are replaced by information for the diversity studies which are be­ semidesert herb species, e.g. Tanacetum millefolia­ ing carried out (see van der Maarel 1988, in press). tum and Kochia prostrata (Gorshkova 1954). This contribution will deal with above-ground In Siberian true steppes under heavy grazing by components in some detail and with the below­ sheep the species composition does not change ground components in general. Details on the much but the abundance of most species changes below-ground components will be treated in a dramatically. The amounts of Festuca valesiaca separate paper {Titlyanova in prep.). and Carex pediformis increase, with the above­ Studies on different steppe communities in ground phytomass dominated by Festuca and the Europe (Bystriskaya & Osychnuik 1975), Kazakh­ below-ground phytomass by Carex pediformis stan {Titlyanova et al . 1983) and central Siberia (A vanasiev & Rotova 1986). The main steppe (Avanasiev & Rotova 1986) indicate the same species Stipa krylovii and Helictotrichon deser­ tendency of change in above-ground biomass para­ torum are still present, but change their ap­ meters from ungrazed to heavily grazed condi­ pearance totally. Bunches are small and leaves are tions: Maximum green biomass and dead standing short and narrow like the leaves of Festuca crop plus litter decrease with increasing grazing in­ valesiaca. They never flower under heavy grazing tensity. and may persist in a vegetative state for several The response of below-ground biomass does not decades. As soon as grazing stops such small bun­ follow the same tendency in all communities. Data ches develop rapidly into recognizable large bun­ from European true steppes (Bystriskaya & ches of Stipa krylovii and Helictotrichon deser­ Osychnuik 1975) show larger values for below­ torum respectively (Hakimsianova, in press). ground living biomass in moderately grazed com­ Thus, the species composition for Siberian grazed munities compared to ungrazed communities. Op­ and ungrazed steppe communities is similar, but posite results were obtained by Titlyanova et al . relative abundances change when grazing intensity (1983) and by Avanasiev & Rotova (1986) for increases. steppes in Kazakhstan and central Siberia respec­ tively. Regarding species composition, tall erect grasses are dominant in meadows and meadow steppes. Under increasing mowing and grazing pressure Study area they are replaced by short grasses. In meadow steppes under light grazing, number of species and The study was carried out on limestone grasslands species composition do not change on larger areas, within Stora Alvaret (The Great Alvar) of Oland. say 1000 m2• However, on smaller areas the The climate of Oland is characterized by a rather number of species will increase, from 60 (80) to 110 cold and late spring and a fairly warm and long (130) on plots of 100 m2, and from 25 (30) to 50 autumn (mean temperature for April is usually (88) on 1 m2 (Semeniuk & Gudyna 1986). below 10°C and for October above 10°C, from True steppes are characterized by large bunch data recorded at bland's Ecological Station). The grasses. Under moderate grazing the relative abun­ yearly mean temperature at Ekerum (1921-1950) dance of species changes considerably. Large is 7 .0°C. The coldest month is February with a bunch grasses are replaced by small bunch grasses, mean temperature of -1.8°C. July is the warmest the share of woody chamaephytes decreases, and month with 17.1 oc (Rosen 1982). On the basis of many herb species decrease in abundance. The Tuhkanen's (1980 p. 76) definition of the growing

Acta phytogeographica suecica 76 Biomass structure of limestone grasslands 127 season as the period over which the daily mean the otherwise low Festuca ovina, as well as some temperature remains above 5°C, (>land has a tall herbs, notably Filipendula vulgaris. + growing season of 210-220 days. 2. Moderately grazed site at Gettlinge (56°23 'N The mean yearly precipitation is 437 mm (at 16°27 'E) (MG), slightly elevated and on shallower Gland's Ecological Station for the period 1968- and somewhat drier soil, fairly heavily grazed by 1984) with a wide annual variation. The lowest and heifers (young cows) and some horses for at least highest values for this period are 326 and 574 mm 10 years, but only lightly grazed in 1985. The (Krahulec et al. 1986, see also Rosen 1982). Ac­ sward is fairly short with Festuca ovina as the cording to Bergsten (1955) and Sjogren (1961) be­ dominant grass and many herbs sharing eo­ tween 51 and 57 OJo of the annual precipitation is dominance. Since 1985 the site has been partly pro­ recorded from April to September. This amount tected from grazing during the period May­ was 58 OJo for the period 1965-1984 with a varia­ August in order to guarantee undisturbed tion in absolute values from 191 to 418 mm. measurements. Calculations were made from the data presented 3. Overgrazed site at Gynge (56°32 'N 16°30'E) by Krahulec et al. (1986). The latter authors con­ (OG), where after 25 years of very intensive sheep­ sider the May-July precipitation to be the grazing and manuring, the original Veronica - ecologically decisive precipitation figure. Fluctua­ A venula association has been almost entirely tion in water availability is the main determinant replaced by an anthropogenic open grassland com­ of biomass production and species composition munity with different grasses dominating, viz. (Detling 1979, van der Maarel 1981, Rosen 1982). Bromus hordeaceus ssp. hordeaceus and Poa The average May-July precipitation at Gland's pratensis, and different herbs eo-dominating, e.g. Ecological Station (1968-1984) is 128 mm and the Geranium molle. variation between 76 and 255 mm. The maximum value occurred in 1984, the year prior to the study. In 1985 this value was 132 mm. The potential evapotranspiration for the grow­ Methods ing season is 540-560 mm (Rosen 1982), which is higher than the annual precipitation. This implies Ten 0.25 m2 sample plots were laid out along a 30 that water availability is a limiting factor for plant m long transect at UG and MG. At Gynge, the OG growth during at least part of the growing season. site, 8 sample plots were chosen at random. At the The soils at the study sites have developed on end of August 1985 the plots were clipped and lit­ shallow gravelly deposits with some limestone ma­ ter, mosses and lichens were collected. The above­ terial. The humus profile is 10-20 cm deep and ground plant material was sorted into green roots grow down to 30 cm. phytomass (per species) and total standing dead The alvar vegetation is complex and rich in taxa, biomass. Litter, lichens and mosses were washed consisting of a mosaic of plant communities on a sieve to remove soil particles. (Rosen 1982). The vegetation on the research sites Soil monoliths with a surface area of 35 cm2 has been classified as Veronica sp icata - A venula were collected on each sample plot with a special pratensis association (Krahulec et al. 1986). steel cylinder to a depth of 15-18 cm, depending on the underlying layer of stones. From each Three sites were investigated: monolith one-fifth was cut off to analyse the com­ 1. Ungrazed site at Kleva (56°33 'N 16°28 'E) position of the below-ground plant material. The (UG) on moderately deep soil on gravelly deposits. monoliths were washed and below-ground plant This site was heavily grazed by sheep for at least 15 material was collected on a 0.5 mm sieve. The years between the early 1960's and the late 1970's. below-ground plant material from small monoliths Grazing was later gradually reduced and finally was dyed immediately after washing, following the stopped in 1981. The short sward developed into a technique proposed by Ward et al. (1978) for dense sward with tall grasses such as A venula cultivated annual species and successfully used by pratensis, Agrostis vinealis, Phleum phleoides, and Tesarova et al . (1982) for perennial meadow

Acta phytogeographica suecica 76 128 Titlyanova, Rusch & van der Maarel

Table Percentage dry weight contribution of vascular plant species grasses and herbs: Fresh roots are stained with 1. to the total green biornass in three sites on ands Stora Alvar.1 congo-red solution (1 mg congo-red per 100 ml of C>l water) and then fixed in alcohol. Living roots be­ Species Kleva Gettlinge Gynge UG MG OG come light red whereas dead roots become dark­ Anthoxanthum odoratum 3.24 Phleum phleoides red or brown-red. The share of living and dead ma­ 2.25 A venula pratensis 20.51 13.73 Agrostis vinealis terial was estimated for each monolith. All com­ 18.29 6.64 Carex spp.2 6.67 5.91 ponents of the above- and below-ground plant ma­ Sieglingia decum bens 0.51 0.04 Luzula campestris 0.01 0.49 terial were dried at 80°C for 24 hours and weighed. Festuca ovina 26.89 38.05 3.02 Poa pratensis 29.76 Nomenclature for vascular plants follows Flora Poa angustifolia 3.13 Poa compressa Europaea (Tutin et al . 1964- 1980). 0.02

Trifolium dubium 0.01 Helian themum nummularium 3.99 0.81 Sedum acre 0.02 0.01 Asperula tinctoria 1.27 2.58 Anthyllis vulneraria 1.21 2.00 Results Helian themum celandicum 0.37 7.25 Ve ronica spicata 0.73 0.35 Thym us serpyllum Species composition 1.87 3.83 Ranunculus bulbosus 0.01 0.50 Trifolium campestre Table 1 presents data on species composition and 0.01 0.01 Pulsatilla pratensis 0.34 distribution of above-ground biomass over species Euphrasia stricta 0.27 Trifolium pratense 0.13 and sites. The main dominant species in the Hieracium pilosella 0.02 Cirsium acaule 0.01 moderately grazed site is the perennial bunch grass Linum catharticum 0.01 Trifolium striatum Festuca ovina with 38 OJo of the green biomass, 0.01 Potentilla tabernzmontani 1.14 0.88 0.21 Lotus corniculatus followed by A venula pratensis and Agrostis 0.10 2.67 0.01 Filipendula vulgaris 4.62 5.82 0.86 vinealis, and the perennial suffrutescent chamae­ Plan tago lanceolata 1.64 0.59 5.49 Cerastium semidecandrum 0.05 0.11 4.31 phyte Helianthemum oelandicum and hemicryp­ Taraxacum spp. 3 0.01 0.01 5.54 Trifolium repens 0.18 0.01 1.03 tophyte herb Filipendula vulgaris (see van der Galium verum 2.95 0.96 11.07 Achillea millefolium Maarel 1988 for a survey of life-form and other 4.61 2.76 6.74 Stellaria graminea 0.02 0.03 Oxytropis campestris characteristics of alvar grassland species). Nearly 0.01 0.01 Potentilla argentea 0.05 Sedum album 60 OJo of the green standing crop is made up of the 0.01 Viola arvensis 0.01 three grass species. Many species contribute only Geranium molle 10.78

very little to the total living standing crop. In the Juniperus communis 0.01 Pin us sylvestris4 richest community, MG, at least 23 species occur 0.01 with less than 1 OJo , and 12 of them even with less ungrazed; moderately grazed; overgrazed. 1 UG: MG: OG: than 0.1 Values averaged over rn2 plots and respectively . OJo. 0.25 ( 10, 10 8 ) Carex caryophyllea and Carex ericetorum. 2 At the ungrazed site the same three grasses Taraxac um vulgaris sect. Vulgaria and sect. Erythrosperrna. 3 Seedling of Pinus sylvestris. dominate, and together they make up nearly 70 OJo 4 of the green biomass, with the tall grasses A venula pratensis and Agrostis vinealis together dominat­ ing over Festuca ovina. Here there is a smaller we find almost equal shares of the perennial number of low-represented species: 15 with less Galium verum and the annual Geranium mol/e. than 1 OJo.The difference in biomass distribution is The usual alvar dominants are reduced in biomass correlated with the total number of species en­ (Festuca ovina) or even disappear completely countered in the samples: namely 34 in the (Avenula pratensis, Agrostis vinealis) . Moreover, moderately grazed and only 29 in the ungrazed the total number of species is reduced further, with community. only 20 species left. The pattern in the community under heavy sheep Dominance diversity curves (Fig. 1) show dif­ grazing is completely different: The main ferences between the three sites. These curves can dominants are one perennial grass, Poa pratensis, be interpreted as an expression of the relative followed by the annual grass Bromus hordeaceus dominance relation of species, in other words as a ssp. hordeaceus, which together make up nearly size hierarchy (van der Maarel 1988, in press). The 50 OJo of the total green biomass. Among the herbs dominance structure under grazing shifts from a

Acta phytogeographica suecica 76 Biomass structure of limestone grasslands 129

• The amount of graminoid biomass decreased with • • .. increasing grazing intensity but the opposite • UG MG Ch OG tendency is found for the herbs. Cfn A .. Biomass figures for mosses plus lichens were highest for the MO site, intermediate for UG and lowest for 00. Moreover, the relative contribu­ tions of mosses and lichens to these values were 0 0 - 0 0 different: At the MG site lichens accounted for A 0 about 80 OJo of the biomass while at UG, mosses .. 0 A L>ttl • accounted for about 90 OJo of the biomass. There is 0 0 0 0 a tendency for moss biomass values to decrease A Ill. A an 0 with increasing grazing impact. However, we know iD) A that this tendency is not general (Rosen personal species sequence comm.) since acrocarpic mosses such as Bryum Fig. 1. Dominance-diversity curves based on percen­ and Pohlia increase under increased grazing. For tage dry weight contributions of species to green biomass lichens, the picture is clearer: lichen biomass (cf. Table 1). Lowest value recognized is 0.01 g m-2 • decreases both under ungrazed and overgrazed Filled squares: perennial grasses; empty squares: peren­ nial herbs; filled triangles: annual grasses; empty conditions. triangles: annual herbs; empty circles: other species. Lichens and mosses have a patchy distribution. According to the July cover estimations in the framework of the diversity project (unpublished), strong hierarchy to a more even biomass distribu­ values for moss plus lichens cover varied from < 1 tion under moderate grazing to a still stronger hier­ to 80 OJo in MO plots of 0.25 m2 and from < 1 to archy under heavy grazing. In terms of the main 50 OJo in UG plots. The standing crop of lichens groups of species, there is a shift from perennial to and mosses varied from 1 to 16 g m·2 in the annual species, and from grasses to herbs. The samples of the ungrazed community, from 15 to 63 ratio graminoids/herbs (on a green phytomass g m·2 in those of community MO and from 0.7 to basis) decreases from 3.7 in UG via 1.8 in MO to 24 g m·2 in community 00. 1.1 in 00. Differences of total green biomass values be­ Above-ground biomass tween the UG and MO sites were not statistically Table 2 presents data for above-ground standing different but the value for the 00 site was much crop at the end of August 1985. Green biomass lower. values of vascular plants were highest in the The values for above-ground dead biomass were ungrazed site and lowest in the overgrazed site. also similar for the UG and MO sites, and much higher than the ones for the OG site, both regard­ ing standing dead and litter. The amount of litter was higher for the MG than for the UG site.

Table 2. Above-ground standing crop components in the sites UG, MG and OG The total standing crop values for the ungrazed 1 (cf. Table 1) , late August 1985. and moderately grazed sites compare well with UG MG OG figures obtained in late July 1985 for the UG and

SE SE SE :t :t MO sites during the yearly transect analyses (in the Graminoids 156.12 9.1 115.84 4.2 85.80 8.5 framework of the Diversity project): 368 g m·2 for Herbs 42.48 4.2 63.28 3.9 74.16 7.6 Total vascular plants 198.60 10.5 179.12 8.7 159.96 11.4 UG and 370 g m·2 for MO. These figures are sup­ Mosses lichens 48.92 16.5 96.00 17.6 9.36 3.0 + Total green biomass 247.48 18.0 274.45 18.0 169.32 10.8 posed to represent maximum standing crop of

Standing dead 166.76 12.4 122.44 11.1 49.12 7.2 above-ground phytomass. They include standing Litter 92.64 10.6 134.44 12.3 62.52 9.4 dead which was n9t analysed separately. This To tal dead biomass 259.40 16.9 256.88 17.5 111.64 13.7 amount was estimated to be not more than 10 OJo Total above-ground biomass 508.68 28.0 531.33 28.6 280.96 22.4 of the total phytomass at UG and less at MO. At

1 Dry weight of components, in g m-�. the moderately grazed site, the corresponding late-

Acta phytogeographica suecica 76 130 Titlyanova, Rusch & van der Maare/

July figures for other plots included in the diversity Table 3. Below-ground standing crop components in the sites UG, MG and OG cf. Table 1 , late August 1985.1 studies occurring on thinner soil with a high cover ( ) UG MG OG of mosses and lichens, are not more than 280 g m-2. X CV X CV X CV Below-ground phytomass Standing crop of above-ground phytomass was 0-10 cm 1200 28 1847 21 1866 27 11-15 cm 216 31 336 22 207 40 roughly the same in the community without graz­ Total 1416 22 2183 20 2073 26 ing and with moderate grazing, despite the fact Living roots 871 23 1129 33 827 44 Dead phytomass 545 38 1054 22 1246 41 that the quantitative species composition was dif­ % living roots 62 51 18 40 35 ferent. In contrast, the overgrazed community had 1 Dry weight of components, in g m-2. much less standing crop: 218 g m-2, with only 22 OJo dead.

Below-ground plant material Living below-ground plant material consists of the values for the ungrazed and overgrazed sites stem-bases and tubers, as well as roots of different are lower and similar to each other. At the same lengths. Dead below-ground plant material in­ time, the share of living (especially long) roots cludes dead stem-bases and tubers, fragments of decreases with increasing grazing intensity. The dead big roots, seeds, as well as particles and ex­ spatial variation in the distribution of below­ crements of soil fauna. Dead small roots are ground plant material does not increase under seldom found in the soil because such roots decay grazing, as judged from the coefficients of varia­ rapidly. The distribution of living and dead below­ tion, lying between 20 and 26 OJo (Table 3). How­ ground plant material is presented in Table 3. ever, grazing seems to affect the heterogeneity in Total below-ground standing crop increases con­ distribution of the living roots, with the coefficient siderably from the ungrazed community to the of variation increasing from 23 % to 44 OJo . As grazed ones, with similar total values for the shown in Fig. 2, the difference is particularly clear moderately grazed and the overgrazed sites. The when comparing the percentage values for living amount of total living roots, on the other hand roots in individual samples. These values are close was highest for the moderately grazed site whil ; to each other, most of them lying between 57 and 65 OJo in the ungrazed grassland; they vary from 38 to 62 % in the moderately grazed grassland; and between 21 and 63 % for the overgrazed com­ munity.

� r-

r- .--

Acta phytogeographica suecica 76 Biomass structure of limestone grasslands 131 alvar "Avenetum" such as Festuca, Avenula and results were due to the high biomass values for the Agrostis are replaced by a ruderal annual grass, lichens. Although severely damaged when Bromus hordeaceus, and the mostly ruderal peren­ trampled, lichens occur normally in grazed alvar nial Poa pratensis. The dominant herbs, including grasslands (Witte 1906). Ljung (1970) analyzed the the semi-woody chamaephytes Helianthemum and species composition along grazing gradients on Thymus, are replaced mostly by ruderal herbs, Oland's Alvar in paddocks that were classified as some of them being annual (Geranium molle) . degree 4 or 5 of Sjogren's scale for damage by Thus, weeds and nitrophilous grasses and herbs grazing (from 1: no or irrelevant changes produced take over in overgrazed alvar grasslands, whereas by grazing, to 5: large changes produced by in true steppes the grazing-adapted species are trampling and grazing) (Sjogren 1966). Mosses and low-growing perennial graminoids including lichens appeared to be absent from the most Carex. This may be due to climatic differences: the trampled areas, but several species occurred true steppe region has an even lower rainfall than towards the central part of the paddocks in spite of Oland and longer, colder winters. Indeed, a part of the fact that the area showed signs of having been the anthropogenic replacement species are of the grazed heavily. This shows that even in heavily Atlantic-Subatlantic distribution type (van der grazed communities of the alvar grassland, lichens Maarel 1988). The trend of an increasing share of and mosses manage to persist. Although they are herbs at the expense of grasses with increasing damaged by trampling, lichens are not grazed by grazing intensity as reported by Rosen (1982) is domestic herbivores. Moreover, the occurrence of confirmed by our results. The xerophytic character short turfs and open areas in moderately grazed of the true steppe is due to the climate, whereas sites may favour the establishment of lichens. that of the alvar vegetation is due to the low water Mosses are favoured by the denser turf of the storage capacity of the soil. ungrazed community. Contribution to moss and Cooler and more humid summers on Oland also lichen biomass values under different grazing con­ allow a widespread occurrence of lichens and ditions is due to different species (Rosen 1982). mosses. Alvar vegetation is similar to the alpine Total green biomass of vascular plants was heathlands of the Scandinavian mountains regard­ highest at the ungrazed site and lowest at the ing this aspect (Witte 1906). However, because of overgrazed one, showing the same trend as found its phanerogam structure, alvar vegetation is more in meadows and true steppes (Bystriskaya & related to true steppes. Osychniuk 1975, Titlyanova et al. 1983). Total The amount of biomass of mosses and lichens dead biomass values are high in the moderately is largely reduced when the community is over­ grazed site and almost the same as those of the grazed. Ljung (1970) showed that mosses and ungrazed site. The fact that the moderately grazed lichens disappear from the community under con­ site was closed to grazing during a major part of ditions of extreme trampling. Rosen (1982) also the growing season may explain the accumulation suggests that large lichens are easily fragmented by for that year of dead material. trampling. The amount of living roots is also higher at the The values for all components of above-ground moderately grazed site than at the two other sites. biomass are reduced when the community is This result agrees with results obtained for true overgrazed. This agrees with the results obtained steppes in Europe (Bystriskaya & Osychniuk 1975) for true steppes in Europe (Bystriskaya & and for other grassland systems, as the shortgrass Osychnivk 1975), Kazakhstan (Titlyanova et al. prairie in North America (Redetzke & Van Dyne 1983) and central Siberia (Avanasiev & Roiova 1979). Productivity studies made on North 1986). American grasslands showed that grazing in­ Results for the moderately grazed site did not creased the overall grassland productivity (Parton agree entirely with those obtained from true & Risser 1979). The larger amount of light that is steppes. The green biomass values were highest at available at the base of the canopy and the higher the moderately grazed site although differences photosynthesis rate of new leaves may account for with the ungrazed site were not significant. These this response (Me Naughton 1979). Genetic limita-

Acta phytogeographica suecica 76 132 Titlyanova, Rusch & van der Maarel tions for shoot growth would induce an increase of Mosses and lichens constitute a conspicuous the below-ground productivity (Detling 1979). characteristic of alvar vegetation. Their biomass When the community is overgrazed the decrease values are largely reduced when the community is in the photosynthetic capacity induced by the loss overgrazed because they are very sensitive to of biomass may overrun the higher photosynthetic trampling. When the turf is maintained open and rate of new leaves. This fact accounts for the lower trampling is not heavy, as in the case of the values of living roots biomass in the overgrazed moderately grazed community, biomass values for site. Results from steppes in Kazakhstan (Titlyano­ lichens are high. va et al. 1983) and in central Siberia (Avanasiev & Differences between alvar vegetation and true Rotova 1986) show that increasing grazing inten­ steppes may arise mainly from the different factors sity resulted in a decreasing amount of below­ that originate their xerophytic character: soil and ground biomass. The response of grasslands that climatic characteristics, respectively. Summers are are grazed with different intensities may vary with cool and often rather humid on Oland but alvar changes in the availability of limiting factors. Par­ vegetation occurs on thin soils with a low water ton & Risser (1979) showed that above-ground pro­ storage capacity. On the other hand, summers are duction was greater with light grazing when rain­ warm and dry in Eastern Europe and central Asia. fall was 30 OJo below the normal and that maxi­ Moderate grazing of alvar communities resulted mum production occurred with extra heavy graz­ in higher biomass values for living roots. This ing when rainfall was above or slightly below the agrees with results obtained for true steppes in normal. Europe and for other grassland systems, as the Dead below-ground biomass was higher in both shortgrass prairie in North America. It has been grazed sites than in the ungrazed site. In the case shown for some of these communities that an in­ of the overgrazed site, high productivity cannot ac­ crease in productivity, induced by moderate graz­ count for this result. Decomposition of below­ ing, accounts for this result. ground biomass is largely dependent on soil struc­ When the community is overgrazed, on the other ture and water availability. Trampling modifies the hand, the decrease in photosynthetic capacity pro­ distribution of pore sizes. Small pores are formed duced by the loss of biomass overruns the effects and replace larger ones. As a consequence of this, that grazing may have on increasing the grassland gas and water dynamics in the soil matrix change productivity. (Taylor & Box 1960, Wood & Blackburn 1981). Decomposition rates may be largely influenced by Acknowledgements. This work forms part of a joint the characteristics of trampled soils. project on dynamics, diversity and coexistence Changes in the biomass structure of grasslands mechanisms of alvar vegetation with the Uppsala under different grazing intensity can be expressed University Ecological Research Station on bland as a as ratios, namely below-ground/above-ground, base. The project is supported by grants from the root/shoot, and dead below-ground/living roots Swedish Natural Science Research Council (to E. van der Maarel) and the National Swedish Environmental Pro­ ratios. All of these tend to increase with increasing tection Board (to E. Rosen). The research was made grazing impact as will be discussed in a subsequent possible by a grant from the Swedish Institute to A. paper. Titlyanova for a three months stay in 1985, which is gratefully acknowledged. We are grateful to Dr Ejvind Rosen for help during all phases of the field work; to Folke Hellstrom for assistance in the field; to Marijke van der Maarel for her share in the biomass analyses; to Conclusions Prof. Eliel Steen, Dr. Hans Persson and Dr. Lotta Hansson, Swedish University of Agricultural Sciences, Qualitative changes occur when alvar ''Avene­ Uppsala, for practical help with root sorting and discus­ tum" communities are overgrazed. Weeds and sions on root ecology; to Anita van Mierlo, Agricultural University of Wageningen, for assistance in dry weight nitrophilous grasses and herbs take over, whereas analysis of individual species, to Erik Sjogren and Harry the grazing-adapted species in the true steppe are Helmisaari for their help during the preparation of the perennial graminoids. manuscript.

Acta phytogeographica suecica 76 Biomass structure of limestone grasslands 133

References of management practices upon the tallgrass prairie. - Ecol. Stud. 32: 135-155. Albertson, N. 1950. Das grosse siidliche Alvar der lnsel Redetzke, K. A. & Van Dyne, G. M. 1979. Data-based, bland: Svensk bot. Tidskr. 44: 269-331. empirical, dynamic matrix modeling of rangeland Aranasiev, N. A. & Rotova, N. P. 1986. Grazing grazing systems. - Ecol. Stud. 32: 157-172. pressure influence on the steppe ecosystems. - Pro­ Rosen, E. 1982. Vegetation development and sheep graz­ ductivity of mown and grazed grasslands. ing in limestone grasslands of South bland, Sweden. Novosibirsk. pp. 59-62. (in Russian) - Acta phytogeogr. suec. 72: 1-104. Basilevich, N. I. & Semeniuk N. V. 1984. Experiences Rusch, G. 1988. Reproductive regeneration in grazed with anthropogenic gradients regarding separation in and ungrazed limestone grassland communities on material turnover in meadow steppe ecosystems with bland. Preliminary results. - Acta phytogeogr. different land use. - Pochvovedenie 5: 5-18. (in suec. 76. Russian) Semeniuk, N. V. 1986. Biological productivity of Basilevich, N. I. & Shmakova, E. I. 1984. Production­ rangeland ecosystems in the Central Chernosem destruction processes in protected meadow steppes of Nature Reserve. - Dynamics of biota in the central the Central Chernosem Nature Reserve. forest-steppe ecosystems. Moscow. pp. 134-155. (in Geosystems monitoring in biosphere nature reserves. Russian) Moscow. p. 124-147 (in Russian) Semeniuk, N. V. & Gudyna, A. N. 1986. Ecology of Bergsten, K. E. 1955. blands klimat. - Natur pa vegetation of rangeland ecosystems in the Central bland, Stockholm. pp. 36-41. Chernosem Nature Reserve. - Dynamics of biota in Bystriskaya, T. L. & Osychniuk, V. V. 1975. Soils and the central forest-steppe ecosystems. Moscow. pp. primary productivity in steppes near the Sea of Azov. 165-185. (in Russian) -Moscow. 109 pp. (in Russian) Sjogren, E. 1961. Epiphytische Moosvegetation in Laub­ Grassland ecosystems of the World. 1979 (ed. waldern der lnsel bland. - Acta phytogeogr. suec. Coupland, R. T.). - Int. Bioi. Progr. 18: 1-401. 1-149. 44: Cambridge. Sjogren, E. 1966. P.M. rorande vegetation och Detling, J. K. 1979. Processes controlling blue grama betestryck inom sydolandska alvaromraden jamte production on the shortgrass prairie. - Ecol. Stud. angelagenhetsgrad att skydda dessa omraden fran 32: 25-42. olika former av exploatering, speciellt farbetesex­ Du Rietz, G. E. 1925 . Die regionale Gliederung der ploatering. - Report to the Swedish Nature Conser­ skandinavischen Vegetation. - Svensk Vaxtsoc. vancy Council. Sallsk. Handl. 8: 1-60. Taylor, S. A. & Box, J. E. 1960. Influence of confining Gorshkova, A. A., 1954. Investigation of steppe pressure and bulk density on soil water matric poten­ pastures in the V oroshilovogradskii district in con­ tial. -Soil Sci. 91: 6-10. nection with their improvement. - Trudy bot. Inst. Tesarova, M., Fiala, K. & Studeny, V. 1982. Live and Akad. Nauk SSSR, Ser. 3, 9: 441-544. (in Russian) dead roots-their mass ratio in several grassland Hakimsianova, F. I. (in press). Restoration succession stands. - Folia geobot. phytotax. 17: 427-430. after removing the grazing pressure in the Hakassya Titlyanova, A. A., French, N. P., Zlotin, R. I. & steppe. - Biological productivity in grasslands­ Shatokhina, N. G. 1983. Anthropogenic transforma­ geographic regularities and ecological peculiarities. tion of grassland ecosystems in the temperate zone. (in Russian) - lzv. SO AN USSR, Ser. bioi. 2: 9-22. (in Rus­ Krahulec, F., Rosen, E. & van der Maarel, E. 1986. Pre­ sian) liminary classification and ecology of dry grassland Tuhkanen, S. 1980. Climatic parameters and indices in communities on blands Stora Alvar (Sweden). - plant geography. - Acta phytogeogr. suec. 67 : Nord. J. Bot. 6: 797-809� 1-105. Ljung, E. 1970. Artbytet omkring fallor och farhus pa Tutin, T. G., Heywood, V. H., Burges, N. A., Valen­ blands Stora Alvar. - Mimeographed, Dept. Ecol. tine, D. H., Waiters, S. M. & Webb, D. A. 1964- Bot. Uppsala Univ. 1980. Flora Europaea. - Cambridge. Makarevich, V. N. 1970. Change in the structure of a van der Maarel, E. 1981. Fluctuations in a coastal dune shortgrass-herb community affected by different grassland due to fluctuations in rainfall: experimen­ kinds of utilization. - Trudy bot Inst. Akad. Nauk tal evidence. - Vegetatio 46/47: 259-265. SSSR, Ser. 3, 18: 54-144. (in Russian) van der Maarel, E. 1988. Floristic diversity and guild Miles, J. 1973. Early mortality and survival of self-sown structure in the grasslands of bland's Stora Alvar. seedlings in Glenfeshie, lnverness-shire. - J. Ecol. Acta phytogeogr. suec. 76. 61: 93-98. van der Maarel, E. 1988. Species diversity in plant com­ McNaughton, S. J. 1979. Grazing as an optimisation munities in relation to structure and dynamics. Proc. process; grass-ungulate relationships in the Serengeti. lnt. Symp. Vegetational Structure. Utrecht. SPB Nat. 113: 691-703. Publ. The Hague. -Am. Parton, W. J. & Risser, P. G. 1979. Simulated impact Walker, B. H. & Noy-Meir, I. 1982. Aspects of the sta-

Acta phytogeographica suecica 76 134 Titlyanova, Rusch & van der Maarel

bility and resilience of savanna ecosystems. - Ecol. Stud. 42: 556-590. Ward, K. J., Klepper, B., Riokman, R. W., & All­ maras, R. R. 1978. Quantitative estimation of living wheat root lengths in soil cores. - Agron. J. 70: 675-677. Witte, H. 1906. Till de svenska alfvarvaxternas ekologi. Thesis Uppsala Univ. 119 pp. Wood, M. K. & Blackburn, W. H. 1981. Grazing systems: Their influence on infiltration rates in the rolling plains of Texas. - J. Range Manag. 24: 331-337.

Acta phytogeographica suecica 76 Partitioning of variation in pubescence of a dwarf shrub , Helianthemum oelandicum Bjorn Widen

Abstract Widen, B. 1988. Partitioning of variation in pubescence of a dwarf shrub, Helianthemum oelandicum. -Acta phytogeogr. suec., 76, Uppsala. ISBN 91-7210-076-1.

Pubescence at different levels has been studied in the concentrated flowering (CF) and pro­ tracted flowering (PF) strategies of the Helianthemum oelandicum complex on the Baltic island of Gland. Trichomes have been divided into stellate hairs, simple and fasciculate bristles and glandular hairs. They were quantified in different parts of the plant and a 'hair index' (HI) was constructed. The precision and reliability of this HI was tested. There is a

continuous variation ranging from wholly glabrous plants (HI = 0) to plants densely covered

with stellate hairs and bristles (HI = 14). The average HI of the two flowering strategies dif­ fers significantly, although there is much overlapping. In general, the average HI is much lower for CF plants than for PF plants. The variation in HI is geographically structured. Each local population (100m 100 m) has a characteristic distribution of HI's, and in c. 70 x OJo of the cases repeated samples at the same site did not differ significantly. There is a group

of CF sites dominated by plants with HI = 0 and another group where glabrous plants are rare. Glabrous PF plants are rare and most PF sites have an intermediate HI. In continuous populations of H. oelandicum significant differences in HI can occur over short distances, and areas with a homogeneous HI vary in size from a few hundred m2 to several km2• In areas with a disjunct distribution of H. oelandicum neighbouring alvar areas often differ sig­ nificantly. Estimated environmental conditions are expressed in an environmental index (El). There were significant correlations between HI and El. The more extreme the habitat (poor drainage) the lower the HI in both CF and PF plants. It is concluded that the variations in pubescence reflect adaptation to the unique environment on Oland.

Bj orn Widen, Department of Sy stematic Botany, Un iversity of Lund, Va llgatan 61 0. 20,223 Lund, Sweden .

Introduction absence of certain types of trichomes (Tutin et al. 1968). However, in many taxa variation in Trichomes are significant morphological charac­ pubescence is complex and shows considerable ters. They may occur in every part of the plant and geographic variation. In the H. canum-oelandicum in a variety of forms: unicellular or multicellular, complex, for instance, H. canum is distinguished glandular or eglandular, straight, spiral, hooked or from H. oelandicum on the presence of dense tortuous, simple, peltate or stellate. The adaptive stellate hairs on the lower surface of the leaves. significance of trichomes has long been con­ This seems to be a good diagnostic character in the sidered, in general their role in the water-balance central part of the distribution area of this complex and regulation of heat, but recently also their anti­ aggregate (C and S Europe), but not in marginal herbivory role (for a review see Levin 1973). areas such as Turkey (Davis 1965) and the Baltic Trichomes are often important diagnostic and island of Oland (Widen 1986). distinguishing characters at several taxonomic H. oelandicum is a prostrate dwarf shrub, levels. In the genus Helianthemum, for instance, dominating large areas of the open calcareous many taxa are distinguished by the presence or alvar grasslands of Oland. There is considerable

Acta phytogeographica suecica 76 136 B} orn Widen variation in pubescence, both qualitative and peaks of local adaptation in an area with a con­ quantitative (Widen 1986) as well as in flowering siderable degree of heterogeneity of environmental time (Sterner 1936 a, Widen 1980). The variation conditions. in the complex on Oland has been treated by a number of authors, mostly from a taxonomical point of view (Hartman 1820, Fries 1823, Material and methods Wahlenberg 1826, Neuman 1901, Grosser 1903, Janchen 1907, Sterner 1936 a). Sterner treated the Sampling procedure complex as three species: the early flowering H. The material for this study was selected in a oelandicum (endemic) without stellate hairs, the number of steps. First, the known distribution area late flowering H. canum (C European) with a of H. oelandicum was divided into 7 sections (A­ dense covering of stellate hairs on the lower sur­ G, Fig. 1). Secondly, in each or some of these sec­ face of the leaves and the late flowering H. tions four kinds of sampling were performed in italicum subsp. rupifragum (SE European) without order to describe variation in pubescence at differ­ a cover of stellate hairs. Proctor in Flora Europaea ent levels. (Tutin et al. 1968) distinguished H. oelandicum subsp. oelandicum and H. canum subsp. cane­ Population sampling. 25 sites of 100 100 m x scens, both endemic on Oland. Widen (1980, 1982, were selected so as to cover as much of the distri­ 1986) stressed that the most important diagnostic bution area as possible. A greater number of sites character is the flowering strategy. The plants have were chosen in section B because of the known either a concentrated flowering (CF) strategy with morphological variation in this area. The number a flowering period concentrated to a few weeks in of sites in the sections were: 2 (A), 11 (B), 4 (C), June, or a protracted flowering (PF) strategy, the 2 (D), 3 (E), 1 (F), 2 (G). Within each site three in­ flowering period extending from early June till Oc­ dependent and random samples of 20 plants were tober. Inflorescences are borne on the previous taken. In each sample all plants were collected within a 1 1 m quadrat, or in cases of less than year's growth in CF plants and both on the previ­ x ous year's and the current year's growth in PF 20 plants, in additional quadrats within an area of 10 10 m. The exact procedure in sampling sites plants. Most of the protracted flowering occurs in x two peaks (one in early June and one in late July), and plants was described in Widen ( 1980). the number of flowers in both peaks varying be­ tween populations and between years. The distri­ Transection sampling. Transections across the bution of CF and PF plants is mainly allopatric, whole or a part of the alvar areas were made in sec­ PF plants are restricted to a limited area of the tions B, C, and E (Fig. 1). The distance between southernmost part of Oland, CF plants are found the transections was c. 400 m in sections B and C and 200 m in E. Quadrats ( 1 1 m) were thrown in many places on the island (Widen 1980). Pre­ x liminary results from a biosystematic study (Widen at every 50 m along the transection if there were at 1986) suggest that CF and PF plants are closely least 5 mature plants of H. oelandicum per m2 related and probably represent different adaptive within a radius of 10 m. First, several environmen­ peaks (Widen 1980, 1982, unpublished). tal characteristics were classified and given scores In this paper I provisionally treat the complex on on a scale (see below). Secondly, one mature plant Oland as H. oelandicum s. lat. I describe methods was chosen in each corner and one in the middle of for estimating variation in pubescence and I use each quadrat. The morphological attributes of these methods to estimate variation at different these fiveplants and the environmental scores were levels: within plants, among plants within popula­ recorded on a tape recorder. Sections B and E were tions, among populations on a local scale and investigated in 1975, section C in 1976. among populations on a regional scale. I maintain Regional sampling. 120 sites of 100 100 m were that trichomes are poor taxonomic characters in x the H. oelandicum complex and my hypothesis is randomly selected: 5 (in section A), 54 (B), 20 (C), that variation in pubescence on Oland reflects 11 (D), 15 (E), 7 (F), 8 (G). One sample of 20

Acta phytogeographica suecica 76 Variation in pubescence of Helianthemum oelandicum 137 plants in 1 1 m quadrats was taken at each site. x A further 9 sites were sampled in sections B and E during the course of the field work (see Widen 1980).

Cultivation. The quadrats at 25 sites in the popula­ tion or regional sampling were permanently marked and the total seed production on the 20 G1 plants at each site was collected in 1973 or in 1974. Where possible 20 plants per site were raised from these seed cohorts (Widen 1980).

Classification and quantification of pubescence I used two methods to estimate variation in pubescence. A detailed laboratory method was G2 used in the population sampling, regional sampling and for the cultivated material. One twig with in­ G3 florescences and a terminal leaf rosette was ran­ domly chosen from each plant. Trichomes were classified and quantified on leaves in the terminal rosette, on the inflorescence axis and on the sepals of a mature flower(see Results). When quantifying the pubescence I compared each part under a microscope with a collection of leaves, inflorescen­ ces and flowers that had been prepared after a pre­ F1 liminary survey of some parts of the material. A quick and less precise method (the field F2 method) was used in the transection sampling. Based on my experience from other samplings I classified and quantified pubescence on plants in situ. F3 I estimated the precision and reliability of my quantification of pubescence. In the laboratory method I used one of the samples at each site in the population sampling. Two twigs were randomly E chosen from each plant, each was given a random code number and they were kept separate in two series A and B. Series A was measured first and D series B was measured 2-3 months later. Series B was measured again after 6 months. After decoding the code numbers the three measure­ c ments on each plant were compared. A com­ parison between the two measurements in series B \ B

A Fig. 1. Map of Oland showing sections where He/ian­ themum oelandicum was investigated. Sections F and G are shown as subsections 1-3 (cf. Fig. 1 in Widen 1980). 0 In sections B, C and E the transections across Stora km Alvaret are shown.

Acta phytogeographica suecica 76 138 Bj orn Widen gives an indication of how reliable my methods is Statistical analysis and a comparison between A and B indicates the Non-parametric methods (Sokal and Rohlf 1981) level of variation within a plant. were used to test differences between populations In the field method I used transections in section (Kruskal-Wallis and Mann-Witney). Correlations E (Fig. 1) to check the reliability of the measure­ are given as Spearman's rank correlation coeffi­ ments. When sampling along the transections I cient rs. marked out each 50 m distance with stones. After having finished one transection I repeated the sampling of 5 plants within a 1 1 m quadrat x Results when returning to the starting-point. Both samples at each site were taken within a radius of 10 m. Trichomes Three types of trichomes occur in H. oelandicum: Classification of the environmental factors - Glandular hairs (Fig. 2A) are scarcely visible to At each 50 m interval along the transections the the naked eye ( < 0.1 mm). The hair consists of dominant vegetation within a radius of 10 m was 2-3 cells and the terminal gland. They mainly oc­ classified (modified from Albertson 1950): (1) cur on leaves, inflorescence axes, pedicels and 'Karst', fissures in the limestone bedrock not filled sepals. - Simple and fasciculate bristles occur in with soil, (2) bare bedrock with vegetation only in groups of 1-4 on leaves, inflorescence axes, the soil-filled fissures, (3) dry meadow, (4) Helian­ pedicels and sepals (Fig. 2B). They are more or less themum heath, (5) Festucetum, (6) wet meadow straight. - Stellate hairs (Fig. 2C) are found on and (7) temporary pools. If H. oelandicum oc­ the lower surface of the leaves, on inflorescence curred within a radius of 10 m a quadrat (1 1 m) x axes, pedicels and sepals. Sometimes they can also was thrown and the type of soil within the quadrat be found on the outside of the ovary and capsule was classified: (1) Quarternary deposits, (2) wall. Intermediates between bristles and stellate weathered soil only in the fissure system, (3) a thin hairs are common. layer of coarse weathered gravel ('vittringsgrus'), and (4) a thin layer of fine weathered soil Quantification of pubescence ('alvarmo'). Then a judgement was made of the It proved to be a rather complicated procedure to drainage conditions within the quadrat: (1) good, count the number of bristles and stellate hairs be­ or (2) poor. Finally, the dominant topographical cause they often occur in a dense felt of inter­ features within a radius of 50 m were classified: (1) twined hairs. Instead, I constructed a scale to ridges of Quarternary deposits, (2) very uneven quantify variation in pubescence from wholy bedrock with low hills and depressions, the dif­ glabrous organs to organs with a dense covering of ferences between the top of hills and the bottom of hairs. I separately measured bristles on sepals and depressions being > 0.5 m, (3) less uneven bed­ leaves, and stellate hairs on sepals and on the lower rock, the differences < 0.5 m, (4) an even alvar surface of the leaves. The leaves used were those plain without depressions. on the current year's growth in the terminal rosette

Fig. 2. Trichomes in Helianthemum oelandicum and examples of scores for trichomes in different organs. A. Glan­ dular hairs in the inflorescence (a plant at CF site 82 in section C). B. Bristles on the upper surface of the leaf (PF 11 B). C. Stellate hairs on the lower surface of the leaf (CF 35 E). D. Glandular hairs in the inflorescence with upper limit of score 2.0 (CF 82 C). E. Glandular hairs in the inflorescence with lower limit of score 1.0 (CF 43 G). F. Bristles on sepals with score 1.0 (CF 26 C). G. Bristles with score 1.0 and stellate hairs with score 1.0 on sepals (CF 35 E). H. Bristles with score 1.5 and stellate hairs with score 2.0 on sepals (CF 267 E). I. Bristles with score 2.0 and stellate hairs with score 3.0 on sepals (PF 11 B). The scale is 0.01 mm in A, 0.1 mm in B and C, and 0.5 mm in D-1.

Acta phytogeographica suecica 76 Variation in pubescence of Helianthemum oelandicum 139

Acta phytogeographica suecica 76 140 B} orn Widen

Table Classification and quantification of Table Distribution (%) of scores for pubescence on 1. 2. pubescence. The scores are exemplified in Figs. and different organs (cf. Table 1 . All plants all field­ 2 3. ) = When the measurements were made by the laboratory sampled plants measured with the laboratory method. method the characters could be given scores between Cultivated populations, cult "' cultivated plants and the integers, i.e 1 . and (except for glandular field .. field-sampled plants at the sites of origin of 0.5, 5 2.5 hairs) but not in the field method (see text). cultivated plants.

Scores Character 0 2 3 All plants Cultivated populations Type of Organ Score Cult Field Stellate hairs No hairs Scattered A sparse cover A dense cover hair PF PF PF CF CF CF on the lower hairs of hairs, the of hairs which surface of surface of the prevents sight of Stellate Lower 0 82.3 23.8 68.1 25.5 82.7 39.0 the leaves leaf can be seen leaf surface leaf surface 0.5 5.4 6.4 6.6 3.7 3.1 5.0 1.0 7.5 17.7 13.5 16.9 8.1 19.8 1.5 3.2 12.3 5.5 15.1 3.8 11.0 Stellate hairs No hairs Scattered A sparse cover A dense cover 2.0 1.3 12.0 3.3 10.1 1.1 9.9 on sepals hairs of hairs of hairs 2.5 0.3 17.8 2.6 18.2 1.2 13.7 3.0 0.03 10.0 0.4 10.5 0.0 1.6 Bristles on No hairs Hairs only Hairs on the Hairs as in 2 , ( ) leaves the petiole petiole, midrib but many on Sepals 0 80.1 4.6 70.0 8.2 70.4 16.5 and sparse underneath, the upper side 0.5 4.5 3.1 5.1 3.7 3.1 3.3 on midrib leaf margin and 1.0 11.0 17.9 12.8 12.8 15.8 18.1 underneath scattered on the 1.5 2.0 14.3 5.1 11.4 3.4 14.3 upper side of 2.0 2.0 35.4 5.5 37.9 7.3 28.6 the leaf 2.5 0.3 15.6 1 .1 16.4 0.0 12.1 3.0 0.1 9.2 0.4 9.6 7.1 o.o Bristles on No hairs Scattered Many sepals Bristle Leaves 0 24.9 0.1 11.4 0.0 10.8 0.6 0.5 7.7 0.0 4.4 0.0 8.1 1.1 Pubescence No hairs Scattered A sparse cover A dense cover 1.0 14.0 1.9 15.0 2.7 16.5 7.7 in the 1.5 28.7 20.2 37.0 23.7 33.8 28.6 inflorescence 2.0 20.9 35.0 29.3 31 .1 25.8 25.8 2.5 3.7 27.4 1.8 31 .5 5.0 26.9 No hairs Scattered 10 hairs 3.0 0.1 15.4 1.1 11.0 0.0 9.3 Glandular > hairs mm·1 Sepals 0 25.8 0.4 11.7 1 0.6 o.o o.o 0.5 19.5 3.9 15.8 1.4 20.4 4.4 1.0 44.3 55.1 57.5 50.2 48.5 35.7 1.5 10.1 28.5 13.5 38.4 19.2 43.9 2.0 0.8 12.1 1.5 10.0 1.9 15.4 (at the 3-5th node). Because of the frequent in­ Stellate In- 0 35.1 0.1 20.5 0.0 15.4 0.6 termediates between bristles and stellate hairs on and florescences 0.5 13.2 0.3 12.1 0.5 13.8 0.6 the inflorescence axis I did not separate these two Bristle 1.0 21 .3 3.5 22.0 1.4 28.5 3.3 1.5 16.7 7.7 17.6 3.6 19.6 14.8 types of hairs there. Glandular hairs were 2.0 9.2 17.8 14.3 14.6 13.5 18.1 measured only on the inflorescence axis. A fixed 2.5 4.2 38.1 12.0 42.5 9.2 42.3 3.0 0.3 32.5 0.0 37. 4 0.0 20.3 part of the inflorescence axis was used for measurement (1/2 cm on both sides of the lowest Glandular In· 0 79.4 97.5 87.9 97.3 68.5 83.5 florescences 1 15.8 2.2 9.9 2.7 21 . 9 11.5 pedicel). The scores given to quantify pubescence 2 4.8 0.3 2.2 0.0 9.6 5.0 in different organs are shown in Table 1 and some of them are illustrated in Figs. 2 and 3. Number of plants 2985 1069 273 21 9 260 182

Fig. 3. Examples of scores for trichomes in different organs in Helianthemum oelandicum. A. Stellate hairs with score 1.0 and bristles with score 1.0 on the lower surface of the leaf (CF 35 E). B. Stellate hairs with score 2.0 and bristles with score 3.0 on the lower surface of the leaf (PF 5 B). C. Stellate hairs with score 3.0 and bristles with score 2.5 on the lower surface of the leaf (PF 11 B). D. Stellate hairs with score 3.0 and bristle with score 2.0 on the lower surface of the leaf (CF 267 E). E. Bristles with score 2.0 on the upper surface of the leaf (PF 5 B). F. Bristles with score 3.0 on the upper surface of the leaf (PF 11 B). G. Hairs in the inflorescence with score 1.0 (CF 35 E). H. Hairs in the inflorescence with score 2.0 (CF 36 E). I. Hairs in the inflorescence with score 3.0 (PF 11 B). The scale is 0.5 mm.

Acta phytogeographica suecica 76 Variation in pubescence of Helianthemum oelandicum 141

Acta phytogeographica suecica 76 142 Bj orn Widen

Table Spearman rank correlations between hair Distribution of 'hair' scores 3. scores on different organs. Significance at p< is In this section I describe variation based on all 0.01 shown in boldface; ns = nonsignificant. Sample size in Table Top row, CF; bottom row, PF plants. field-sampled plants measured by the laboratory 2. method. Glandular hairs were found in 21 OJo of the CF plants (n 2985) and in 2.5 % of the PF 2 3 4 5 6 = Stellate Stellate Bristles Bristles Stellate Glandular plants (n 1069). The scores for hairs on leaves, + = hairs hairs Bristles hairs sepals and inflorescences are mainly higher on PF in in in in in in leaves sepals leaves sepals inflorescences inflorescences plants than on CF plants, but there is much overlapping (Table 2). Most important is the varia­ 2 0.59 75 tion in stellate hairs because of its diagnostic use. o.

No stellate hairs on the lower side of the leaves 3 0.39 0.39 could be found on 82 % of CF plants and on 24 % 0.68 0.65 of PF plants. On the other hand, a dense covering 4 0.31 0.36 0.81 of stellate hairs (scores 2) was found in 40 OJo 0.41 0.36 0.44 = > of the PF plants, but only in 1.6 OJo of the CF 5 0.53 0.60 0.74 0. 72 plants. 0.71 0.75 0.57 0.43

Pubescence on different organs is highly cor­ 0.1 2 -0.14 -0.30 -0.30 -0.28 6 • 0 011 0.10 -0.1 1 -0.06ns -0.15 related (r5 significant at p < < 0.01) in both CF • • and PF plants (Table 3). Bristles and stellate hairs are positively correlated, but glandular hairs are negatively correlated with the other two kinds of are glabrous except for scattered glandular hairs hairs. ( 44 OJo of plants with HI 0 in Fig. 4 had glan­ = Hair index dular hairs). Most CF plants are either glabrous A hair index (HI) was constructed by summing (HI 0) or have a low HI (the average HI 3.8 = = scores for hairs on different parts of the plant if HI 0 is excluded). Only 6 CF plants with a = (Table 1). Glandular hairs were excluded because HI > 10 were found. PF plants, on the other hand, they are difficult to detect by the naked eye. The had a high HI (average HI 8.8). Only 2 PF = index constitutes the integer of this sum, and can plants wi th HI < 3 were found. There was a thus have 15 values (Fig. 4). Plants with HI 0 substantial overlap in HI between the two flower- =

A 8 800 1000 600 800 >. (.) c Q) 600 �g 400 ::I 0" Q) If "- u... 400 200 200

7 8 0 1 2 3 4 5 6 7 8 9 1011 12 1314 0 1 2 3 4 5 6 91011121314 HI HI Fig. 4. Distribution of hair indices (HI). Open bars, CF plants; filled bars, PF plants. A. Plants measured by the laboratory method (population and regional sampling, see text). B. Plants measured by the field method (transection sampling).

Acta phytogeographica suecica 76 Variation in pubescence of Helianthemum oelandicum 143

Table Differences in sum of hair scores Table Average for plants in natural populations and 4. 5. HI between measurements on the same plant. WD = cultivated plants derived from these plants. differences between measurements on the same p = probability that samples differ (Mann-Whitney U­ twig, and differences between the two test). () proportion of CF plants/ all plants in each 801 802 = twigs per plant (see text). The numerals are sample. percentages of plants in each interval. Site Section Field sampled Cultivated p no. plants plants Differences between measurements Number A 4.7 (0.0) 4.3 (0.0) 0.23 0.0 0.5 1.0 1.5 2.0 of plants 2 A 8.5 (0.0) 7.7 (0. 0) 0.53 HI 137 8 9.1 (0.0) 8.9 (0.0) 0.79

100.0 0 0 0 0 133 8 9.1 (0.0) 8.0 (0.0) 0.24 WO 801 99.1 0 0.1 0 109 25 8 8.7 (0.0) 7.1 (0.0) 0.14 802 99.1 0 0.1 0 0 15 8 8.7 (0.0) 6.6 (0.0) 0.001 83.9 12.9 3.2 0 0 11 8 11.7 (0.0) 11.2 (0.0) 0.56 WO 801 67.8 29.0 3.2 0 0 31 41 1 8 10.3 (0.0) 7.5 (0.0) 0.005 802 64.5 32.3 0 3.2 0 31 1 8 9.6 (0.05) 9.2 (0.05) 0.82 2 95.0 5.0 0 0 24 8 6.3 (0.25) 5.9 (0.40) 0.63 WO 801 60.0 37.5 2.5 0 0 40 16 8 10.2 (0.0) 9.3 (0.84) 0.71 802 60.0 37.5 2.5 0 0 6 8 6.8 (0.85) 5.8 (0.70) 0.1 1 3 71 .4 26.8 1.8 0 0 12 8 5.3 (0.85) 5.5 (0.75) 0.81 WO 801 58.9 39.3 1.8 0 0 56 17 8 6.5 (0.85) 6.7 (0.84) 0.80 802 48.2 48.2 3.6 0 0 21 1 8 6.1 (0.95) 5.4 (0.0) 0.27 4 47.2 30.6 13.9 8.3 0 9 8 3.2 (1 .0) 3.1 (1 .0) 0.44 WO 801 38.9 38.9 16.7 5.6 0 36 10 8 5.1 (1 .0) 4.0 (1 .0) 0.49 802 27.8 44.4 22.2 5.5 0 13 8 3.9 (1 .0) 3.8 (1 .0) 0.93 5 26.5 55 .9 17.7 0 0 20 8 2.8 (1 .0) 2.5 (1 .0) 0.97 WO 801 26.5 44.1 29.4 0 0 34 21 8 3.7 (1 .0) 3.2 (1 .0) 0.08 802 20.6 44.1 26.5 8.8 0 26 2.8 (1 .0) 2.4 (1.0) 0.66 c 36.8 36.8 26.4 0 27 0.2 (1 .0) 0.4 (1 .0) 0.51 WO c 801 36.8 39.5 21 .1 2.6 0 38 234 D 2.2 (1 .0) 1.7 (1.0) 0.34 802 23.7 52.6 18.4 5.3 0 36 E 4.9 (1 .0) 4.4 (1.0) 0.31 7 32.0 56.0 12.0 0 0 41 G 4.4 (1 .0) 3.8 (1 .0) 0.36 WO 801 16.0 56.0 24.0 0 4.0 25 802 16.0 56.0 20.0 8.0 0 8 44.0 37.0 18.5 0 0 WO 801 29.6 40.7 25.9 3.7 0 27 measurements made on one of the twigs (series B) 802 29.6 44.5 11 .1 14.8 0 with the measurement made on the other twig 52.4 33.3 4.8 9.5 0 WO 801 33.3 23.8 38.1 4.8 0 21 (series A) in population sampling 1. First, I 802 19.1 28.6 47.6 4.7 0 calculated the average HI based on the sum of 10 38.9 16.7 38.9 5.6 0 WO 801 27.8 44.4 22.2 5.6 0 18 scores for all three measurements on each plant. 802 44.4 27.8 16.7 11.1 0 Then, I calculated pairwise differences in the sum 11 33.3 42.9 14.3 9.5 0 WO 801 23.8 38.1 19.1 19.0 0 21 of scores between the two measurements on the 802 9.5 42.9 28.5 19.1 0 same twig (within difference = WD) and between 12 37.5 33.3 20.8 8.3 0 WO 801 29.2 45.8 12.5 12.5 0 24 the measurements on the twig in series A and each 802 12.5 45.8 29.2 12.5 0 of the two measurements in series B (between dif­ 13 7.1 57.1 35.7 0 WO ference one BD 1, and between difference two 801 42.9 28.6 21 .4 7.1 0 14 = = 802 14.3 64.3 21.4 0 BD2). WD, BD1 and BD2 for each average HI are listed in Table 4. TOTAL 62.4 25.1 10.5 2.0 0 WO 801 53.6 30.6 12.8 2.8 0.2 494 The differences between measurements on the 802 47.8 34.2 13.2 4.9 0 same twig (WD) were less than or equal to 0.5 scores in 87 OJo of all plants and 98 OJo of the dif­ ferences between measurements were less than or ing strategies. 55 OJo of the CF plants and 71 OJo of equal to 1.0. BD1 and BD2 were less precise than the PF plants were found in the main overlapping WD. On the whole, low HI's were more precise

interval HI = 3-10. than high HI's (Table 4).

The precision of HI Cultivation In order to quantify the precision and the Cultivated plants usually get lower scores for indi­ reliability of the HI, I compared the two vidual characters than plants sampled in the field

Acta phytogeograp hica suecica 76 144 Bj orn Widen

A � ..... ·... ·5 ...... 1 Hl=6.1 p.O.O HI 6 . 3 . HI .0 Hl-2.8 .,.:;ll,ll"�J. nOLJ,L n.J,....A"Hl,...... ,...... ,-3.0 ....,....,.., S -,- ···'··· -Wl,J.J,Il,..,LJ,...IIJ,....-.,...... , }1 n l..,....,....,� l.,... --- ...... , 4JI...,IJ,IOLJ,oo,IJ"-..,....,..,,...... ,...... ,...,. ..,...... J .J...,...... ,....,.., - ·• ...... · 1.,-, ..,-A �...... Hl-9.6 ..,....,..,.,H ��,�I�.,.8 .8.,...... , 4LJ,a, ...... HI O• _..�_,.,_H I-0 . 2 ..... ,...... ,...... ,...... ,...... , � .....B . 77 I � � ...... I ...... ,� ,...... 3 HI=8 4 p-0 Hl-8.3 l.,....,....,.fi.JH ...... I,II -8 .0 ...... � �n H1=0.2 �...... Hl-0.0 ...... I- ...... ·•··· ....,....,..... ---....., � .-J ,_ ,...... Hl=8.6 . l Hl=8.3...... ¥-,a,!JJ..lJ..y.,u,...... ,,....,...... nn nHl=3.5 +_nn...,.n'l-'n,..,nHl=3.8,...... ' ..I. I I..... n n ...... +-.-...... ��� ...... I +.,....,....,. fi.J' ...... ,...... I ...... , . /&Al.,_, ...... H..O.B � I - Hl=9.8 l...... - .-.H .II.II=11,10 1,1,.1 t" Hl-<16 +...... �o ..,....,....,�.,._ ...... ,...1 ...... "'· · Hl=9.5 ...... -.-.H IIrl=1�01,1,.3,.,.,..,_, �,Ll,[l,...,...,..,...... ,...,....,..,...... , "�2.1 1 5 .....----...... �� ,.,...,...... - ••• ••• l..... I •• I noD H1=4.3 1 ...... 1 t tnon ...... -+-r-. Hl 2.1 H =1 2.... . 0 4-.-.PJ-JJ.-I,LI,-,IJ,oo,...... l1i=� l,lln �n nLJ,L nJ,C" I-,....Hl=3.0..,....,..,,...... ,.. ..,..... +.-.�"n�.�,�-n�n-..,....,.., �--. -1 ...... +I ...... =... 1 .. � �·1 I ����� �����Hl-12.6 ·�� �����Hl 12.7 �- l+-.-. ....I"[J,oo,llni-J,OHl•6.0 l n n Hl=5.6 I +.-,,....,ll,..,o,LJJIJ,.,Ili,C,....,...... "ll,I "J.-.-, ,...... ,...... , n n" ������� �+ �"�n·�n�:�l -�7 .--7 ��+��" 2 l OL.I,I.ni,LI0 An Hl-3.9..,....,.. l n HI=S.O .....�: ��-:�- �·� +.-,,-J.JJ.I,LI,-,..,....,...,....,..,..._...... �n l,-,ll,ln .,....,....,...... n0 0

� l Onn�Hl=2.1 �" Hl=1.8 �LJ,l.I,LI,....,...... ,,...,....,...,...... , �l0\Ui nn...,..,..,,...,....,...Hl-1.4 ...., ..,..n.,...,"l-¥n Hl-2.5 � �0 I� ...... I .,..n.,...,"...... ,....,....,....,...,....,....,..., -f-lr-IU,U,U,,...,_,.. .,...... ,...,...... 41JO IU.IO OLJ,Ln ...... _"T"T"""H1=1.4...... ,oJ.I.ln O Hl=2.4 �,LI,ll,l.Y.,....,.....,...,....,....,...... , -'!Lnl�,-..., �0 "J,Lni,U,nHl=4.2- l Hl-3.9 ...... � LJ,Lni,LI,n ,...,....,...,...... ,...... ,...,...... ,_n.,..,_,.....,.On..,..n.,...,n,....,...... ,....,....,....,....,.., G ...... I ...... �-l�" �" O� n�nHl=3.2..,....,..,...... , +�On� a�n Hl-��2.8 ..... 2: 51 Hl-<1.1p.. 0.35 �...... H.... I· 0 . 3 ..,....,...... HI ...,.· O..-.O,...... � ���--...... � �+ 0 14 Hair index .,....,...., -h-...... ,. ,...... O� n�n.-,....,...... ,..,....,..Hl-3.6 ..., +...-J.J�nnLJ,LO�n iA"Hl-4.3-...... !JJ..lJ.. __ ...... ��n I Fig. 5. Distribution of hair indices in three samples at each site (rows in each column). Open bars, CF plants; filled bars, PF plants. Horizontal axes, hair indices; vertical axes, number of plants. In the first diagram in each row site no. and section are first shown, then average hair index for the first sample and p probability that the average (HI) = HI of the three samples differ. The differences among samples within sites were tested with the Kruskal-Wallis test. Average hair index (HI) per sample is shown in the other two diagrams in each row.

(Table 2). Average HI is smaller in the cultivated (the population sampling) indicate that the fre­ material for most sites (Table 5). All cultivated CF quency of plants with different HI's remains the plants have an average HI 3.7 and PF plants HI = same within a site. The three samples did not differ 7 .9. The corresponding figures for field significantly at 68 OJo of the sites (Fig. 5). When sampled plants at the sites of origin of the they differed significantly, however, the ranges of cultivated plants are 4.0 and 8.9. The differences HI's were very similar among samples within sites. are significant only for PF plants (M ann-Whitney, Thus, each site has its own characteristic distribu­ p <0.001). tion of HI's. Among CF sites there is a group of sites with a high frequency of glabrous plants and Geographical variation another group where glabrous plants are almost Variation within sites absent. Among most PF sites a medium HI is most The results of the repeated sampling within a site common and there is a great variance at most sites

Acta phytogeographica suecica 76 Variation in pubescence of Helianthemum oelandicum 145

HI Section PF sites Section Mixed sites Section CF sites AVERAGE 8 8 8 oQs() � 10 23 1 (99� � � CJ 105 CJ 104 2 1 0 a ()106 � 108 � 18 � 17 107 Cl 3 11 a () 4 �200 � 12-- () 400 �508 5 �30 c.-, 1 3 . 9 211cg �� () 311 (J 113 114 6 14 . 415 12 315 � 7() �118� ra ... �21 �127 123� ,... (J �124\..J125 2 ...15 122 � � 128 � 131 () 5 ()120 132�133 00 ()136 134 135 Section A �137 � 138 () � 9 3 () 140 �147 � 2 ()3 �1 .. 2

Section Section C Section D E 59 C)82 � (!),. ()61 �30 � (!)90 (971 60 (!)., (!) �75 72 C'J264 3 � (!)97 (931 : .2 028 CJ86 (962 � � 64 q. � 74 � Cl C) 73 � 196 � 36 � � 27 63 � (!) 65 (!) �100 C) � gg 101 .. C)n C.\. �26 Cl83 �78 �5 (979 80 �68 �.. �·· (!) �102 � .. Section G 367 �103 2 3 33 35 � 235 Section F

3 3 2 �0 � 234 "�" � �4 55 �258 � 70

Fig. 6. The�� average HI at each site in section A to G (see Fig. 1). The position of sites is indicated in each section (for position of sites in sections A and B see also Fig. 11 in Widen 1980). 20 plants were sampled at each site (popula­ tion and regional sampling).

Acta phytogeographica suecica 76 146 B} orn Widen except at a few sites with a high average HI (11 and 1980). The average HI's are low in this area (0- 115). 4.2) and there is a significant difference between sites in the western and eastern part of this section. Variation between sites In the eastern part many sites are dominated by The differences among CF sites and among PF glabrous plants but glabrous plants are found in a sites in the population sampling are highly signifi­ low frequency in the western part. cant (p <0.001, Kruskal-Wallis). In this section I will describe variation among sites within each Section D. The average HI varies between 0.6 and geographical section (Fig. 1). I use the regional 4.4. A low average HI is found at many sites in the sample and one sample from each site in the SE and NE parts of the section. population sample, and the result is presented as average HI's in Fig. 6. Section E. In this section several sites are dominated by plants with a high HI for being CF Section A. Only PF plants have been recorded in plants. The average HI varies between 1.4 and 6.4. this section. The sites represent four more or less In small areas around sites 35 and 235 (west of the isolated alvar areas south of the main alvar area village of Stenasa) and site 61 in the northernmost Stora Alvaret. The average HI's (Fig. 6) are in­ part of Stora Alvaret the highest average HI termediate (4.7-8.5) if compared with all sites (cf. recorded for CF sites are found. Some of them Fig. 4) but low compared with PF sites in section have even higher HI's than some PF sites in section B. In reality, site 1 has the lowest average HI (4. 7) A. recorded for any PF site. If the sites are grouped within isolated alvar areas (surrounded by arable Section F. This area is situated north of Stora land or large areas without H. oelandicum) the Alvaret in the middle part of bland. H. oelan­ groups differ significantly (Kruskal-Wallis, dicum occurs in small isolated alvar areas (sites 39, p <0.01). 57, 59), in remnants of open vegetation (39, 258) surrounded by forests or in some parts of the Section B. This area comprises the main distribu­ Greby alvar . The average HI varies between 1.2 tion of PF plants which occupy the central and and 4.2 with a tendency to differ between alvar southern part of the area. CF plants occur in the areas. northern part and in marginal parts of the alvar south to the village of Sebberneby. Three kinds of Section G. H. oelandicum occurs in some of the sites can be separated: CF sites with only CF small alvar areas in northern bland, but not in plants, PF sites with only PF plants and mixed sites others (Sterner 1936 b). Some of these alvar areas with both CF and PF plants. Mixed sites occur are dominated by wholly glabrous plants with con­ along the boundary between the two distribution sequently low average HI's (0-0.9). However, in areas. The average HI varies from 5.7 to 12.8 one area south of the village of Djupvik glabrous among PF sites. There is a tendency for PF sites in plants are rare, with consequently higher average the southern part to have a lower average HI than HI's (3 .7-4.8). The differences among the three sites in the northern part of the distribution area of alvar areas are significant (Kruskal-Wallis, PF plants. However, there are sometimes consider­ p <0.01). able differences between adjacent sites, e.g. be­ tween sites 142 and 143 in the southern part (HI Local variation = 6.8 and 10.1 respectively). The average HI at CF Description of local variation in the three sites varies between 1.2 and 5.4 and at mixed sites geographical areas (sections B, C and E) is based between 2.7 and 10.7. on the transection sampling (Fig. 4B). The HI determined by the field method was less accurate Section C. In this section and in the other sections than the HI determined by the laboratory method, to the north no PF plants were recorded in any because pubescence was assesed by the naked eye sampling procedure. However, on rare occasions I or with the help of a pocket lens in the field and have observed a few PF plants in section C (Widen with fewer intervals on the scale measuring

Acta phytogeographica suecica 76 Variation in pubescence of Helianthemum oelandicum 147

11 1 1 � _ Transection : --+-: Transection 0.0 1.0 �2.0 3.0 4.0 5.0.. 0.0l �""-1.0 2.0r.:-. -. 3.0 --o4.0; 5.0 12 1 1 : :::::::: ono Transection 0.0 1.0 2.0 3.0 4.0 5.0 0.01 1.0 2.0 3.01 4.0 :5.. ..0 3

Transection 0.0 1.0 2.0 3.0 4.0 5.0 0.0 1.0 2.0 3.0 4.0 5.0I'

,,,,,,, � 0.0 1.0 2.0 3.0 4.0 5.0 0.0 1.0 2.0 3.0 4.0 5.0 1:1 �5 0 l-tT>. I"TT"rT"111-""'"_,_._...r,.f!�TI'"'r'U'"T4i� ... """""-"'""'-..- O.O 1.0 2.0 3.0 4.0 5.0 1.0 2.0 3.0 4.0 5.0

0.0 1.0 2.0 3.0 4.0 5.0 17

Transection 0.0 1.0 2.0 3.0 4.0 5.0 0.0 1.0 2.0 3.0 4.0 5.0 1 l � _ 8 18

: Transection Transection 0.01...... �-1.0 2.0 3.0..�.. :� . -�4.0- . illlljl5.0 0.0 1.0 2.0 3.0I cue 4.0 5.0 9 19 l 1: 00 00f!A::...... --:� Transection Transectioncu 0.0l 1.0 2.0 3.0 4.0 5.0 0.0 1.0 2.0'I'' 3.0,, 4.0 5.01 1 0 20

Transection Transection 0.0 1.0 2.0 3.0 4.0 5.0,, 0.0 1.0 2.0 3.0 4.0 5.0 Fig. 7. The average HI ( 0, vertical axis) of 5 plants (CF PF) at each site in transections across Stora Alvaret + in section B; number of PF plant <•, vertical axis) at each site. For position of transections see Fig. 1 (see also Fig. in Widen 1980). Transections are numbered from north to south. Distance from the westernmost site on the 12 horizontal axis (km).

Acta phytogeographica suecica 76 148 Bjorn Widen

40 • PF � MIX 30 10 cf. >. (.) 20 HI a5 ::J rr Q) 5 Lt 10

0 4 2 3 5 6 7 8 9 o +-���--�� Proportion of inflorescences borne on the 1 6 11 16 Transection no. (north to south) current year's growth (classes)

Fig. 8. The average HI ( ± S.E.) of plants at PF sites in Fig. 9. Frequency of PF plants (o/o) in different classes transections from north to south in section B. For refer­ of proportion of inflorescences borne on the current ence to number of PF sites in each transection see Fig. 7. year's growth. PF, PF sites and MIX, mixed sites (transection sampling).

pubescence in different organs (see Table 1). Scat­ tered stellate hairs, for instance, are difficult to see

even with a pocket lens. Consequently, the field HI 10 is an underestimation of pubescence. However, the reliability of the field HI was good (Fig. 12). The HI correlation between the two measurements at each 5 site along transections in section E was significant (rs 0.71, p < <0.01). =

Section B. The average HI for CF plants was 3.0 (N 1190) in CF sites and 4.0 (N 165) in mixed 2 3 4 5 6 8 9 = = 7 sites. Only 18 Ofo of the CF plants were glabrous (HI 0) . HI's for CF plants were highest at the = margin of the alvar in most transections (Fig. 7). Proportion of inflorescences borne on Small areas in the central parts have sometimes a Fig. 10. The average HI ( ± S.E.) for PF plants in differ­ ent classes ofthe proportion current year's of inflorescences growth (classes) borne on the low average HI, for instance, at 3.0 to 3.3 km from current year's growth. PF, PF sites and MIX, mixed the westernmost site in transection 2. sites (transection sampling). There is a pronounced difference between CF and PF sites in most transections. There is a change from 100 Ofo CF plants to 100 % PF plants over a distance of 50 m in a few transections (5- and the largest HI's were found in transections 5-8. There is a significant (rs 0.42, p < 0.001) 8), but more gradual changes in others. The aver­ = age HI for PF plants was 8.1 (N 1330) in PF north-south decrease in average HI. = sites and 6.0 (N 115) in mixed sites. Only 4 PF plants vary in proportion of inflorescences = glabrous PF plants were found, all in mixed sites. borne on the previous year's and the current year's There are significant differences in the HI of PF growth (Widen 1980). The number of inflorescen­ plants in PF sites between transections (Fig. 8, ces were estimated and plants were classified in the

Kruskal-Wallis, p <0.001). The most northern PF following 9 classes: 1 = all inflorescencesborne on sites in transection 3 had a low average HI (5 .0) the previous year's growth CF plant), 2 only ( = =

Acta phytogeographica suecica 76 Variation in pubescence of Helianthemum oelandicum 149

5 1 4 3 Transection 2

0.0 1.0 2.0 3.0 4.0 5.0 6.0 0.0 1.0 2.0 3.0 4.0 5.0 6.0

�

l � Transection M J...... o �Ji� 0.0L 1.0 2.0 3.0 4.0 5.0 6.0 0.0 1.0 2.0 3.0 4.0 5.0 6.0

5 3 5 4 4 3 3 Transection 2 2 1 o��Tn���Tn���Tn.. �� �����n 0.0 1.0 2.0 3.0 4.0 5.0 6.0 0.0 1.0 2.0 3.0 4.0 5.0 6.0

5 4 L ��Transection ...... 0.0 1.0 2.0 3.0 4.0 5.0 6.0 0.0 1.0 2.0 3.0 4.0 5.0 6.0

5 1 5 5 4 4 3 3 Transection 2 2 1 O �Tn���nT���Tn� 0.0 1.0 2.0 3.0 4.0 5.0 6.0 0.0 1.0 2.0 3.0 4.0 5.0 6.0

Fig. 11. The average HI ( 0) and number of glabrous plants (0) of 5 plants at each site in transections across Stora Alvaret in section C. For position of transections see Fig. 1. Transections are numbered from north to south. Distance from the westernmost site on the horizontal axis (km).

one well-developed inflorescence on the current more than 50 % but less than or equal to 70 OJo of year's growth, 3 more than one inflorescence the inflorescences borne on the current year's = growth, 7 more than 70 but less than or equal but less than or equal to 5 OJo of the inflorescences = OJo borne on the current year's growth, 4 more than to 90 of the inflorescences borne on the current = OJo 5 40 year's growth, 8 more than 90 OJo but less than OJo but less than OJo of the inflorescences borne = the current year's growth, 5 40-50 %, 6 100 on = = % of the inflorescences borne on the current

Acta phytogeographica suecica 76 150 Bj orn Widen

5 1 4 3 Transection 2

o ;-��--�r-r-T-T-�

1

50.0 1.0 0.0 1.0 2 4 3 Transection ]� 2 1 o ;-��r-T-� � o �� ��������

0.0 1.0 5 0.0 1.0 4 3 Transection 3 10 2 : l +0-r---r---r---

Fig. 12. The average HI (vertical axis) of 5 plants at each site in transections in section E. Two independent samples were0.0 taken at each site ( 0, + ).1. Number0 of glabrous plants0.0 (D) in the two samples. For1.0 position of transections see Fig. 1. Transections are numbered from north to south. Distance from the westernmost site on the horizontal axis (km).

year's growth, 9 100 % of the inflorescences Section E. The average HI is 2.4 and the frequency = borne on the current year's growth. In general, PF of glabrous plants is 26 OJo . The trend in average plants at mixed sites have a lower proportion of in­ HI is the same in all three transections (Fig. 12). In florescences on the current year's growth than PF the western part of Stora Alvaret there is a c. 100 plants have at PF sites (Fig. 9). The average HI m wide zone with a high average HI. After c. 150 varies among classes (Fig. 10, Kruskal-Wallis, PF m the average HI is low and rises again after c. 400 sites p <0.001, mixed sites p <0.02). In general, m. Another less distinct area with a low average HI low classes have low HI's, but there is a significant occurs at a distance of 800 to 1100 m from the correlation only for mixed sites (r5 0.2257, alvar margin. = p <0.01). Habitat and pubescence Section C. The average HI is low ( 1.9) mainly be­ The four environmental factors, vegetation type, cause 57 OJo of the plants are glabrous. There is sig­ soil condition, drainage and topography were sig­ nificant geographical partitioning of the variation nificantly correlated (Table 6). There are some im­ in HI. In the eastern part of this section large areas portant differences between geographical regions are dominated by glabrous plants, except at the in frequency of scores for the four factors (Table most extreme eastern boundary of the alvar, where 7). For instance, the topography in section C is pubescent plants are more common (Fig. 11). The very even over large areas (scores 3-4) with conse­ western part of this section is dominated by pub­ quently poor drainage (2). In section B, on the escent plants. other hand, uneven topography (2) is more corn-

Acta phytogeographica suecica 76 Variation in pubescence of Helianthemum oelandicum 151

Table Spearman rank correlation coefficients for 6. 40 environmental factors. Top row, PF sites; then mixed PF • sites; CF sites in section B; CF sites in section C; MIX bottom row, CF sites in section Significance at p< � E. D CF 0.01 is shown in boldface; ns= nonsignificant. For 30 sample size see Table 7. l >. () Vegetation Soil Drainage c 20 Cl> ::J 0" Cl> Soil 0.69 U: 0.68 10 0.66 0.64 0.41

. Drainage 0.58 0.47 2 3 4 5 6 . 8 . 9 0.56 0.59 7 0.61 0.54 El 0.46 0.50 72 0.56 Fig. 13. Frequency of PF sites, mixed sites (MIX) o. (OJo) and CF sites (transection sampling) in different classes Topography 0.23 0 11ns 0.26 . of the environmental index (El). For reference to 0.56 0.50 0.55 number of sites see Table 7. 0.42 0.31 0.66 0.26 0.39 0.49 0.43 0.38 0.59 mon, and PF sites are more frequent than CF sites in well-drained, uneven bedrock. To summarize the environmental conditions, I calculated an environmental index (El). Vegetation types were excluded and will be treated in greater detail in a forthcoming paper. The scores for the Table Distribution (Ofc,) of scores for four 7. other three factors were summed. Drainage was environmental factors in the transection sampling in given more weight by multiplying individual scores sections B, C and PF (B) sites with only PF plants E. = in section B; mixed (B) = sites with both PF and CF by 2. By subtracting 3 from this sum an index (El) plants in section B, etc. The samples differ ranging from 1 to 9 was created. The average El significantly for all environmental factors (Kruskai­ Wallis, 0.001). was 5.2 for PF sites, 6.5 for mixed sites, 6.4 for CF P< sites in section B, 6.6 for CF sites in section C and

Environmental Sites: 6.0 for CF sites in section E (the differences being factor Score PF (B) Mixed (B) CF (B) CF (C) CF (E) significant at p <0.001, Kruskal-Wallis). The distribution of El is bimodal (Fig. 13). PF Vegetation 1 0.4 0.0 0.4 0.0 5.5 2 8.3 1.8 4.2 3.0 2.0 sites are most frequent at medium El's, CF and 3 16.9 3.6 9.2 6.1 18.0 mixed sites at high El's. There is a significant de­ 4 54.9 60.7 50.0 52.5 23.5 5 19.6 33.9 36.2 38.4 51 .0 crease in HI with increase in El at PF and CF sites but not at mixed sites (Fig. 14, r5 -0.224, Soil 0.8 0.0 1.3 5.6 3.6 = 2 16.5 1 .8 5.0 11 .6 11.0 p <0.01 at PF sites, rs -0.174, p <0.01 at CF = 3 69.9 58.9 57.6 46.5 38.2 sites and r5 = -0.024, ns at mixed sites). 4 12.8 39.3 36.1 36.3 47.2 The proportion of inflorescences borne on the

Drainage 71 .1 33.9 41 .2 33.2 45.5 current year's growth in PF plants decreases with 2 28.9 66.1 58.8 66.8 54.5 an increase in El (Fig. 15, r5 -0.29, p <0.01). =

Topography 1 0.0 0.0 0.8 0.0 3.6 2 35.7 28.6 26.1 8.6 30.9 Mixed sites 3 62.4 60 .7 55.0 64.7 50.9 Mixed sites mainly occur close to the boundary be­ 4 1.9 10.7 18.1 26.7 14.6 tween the distribution areas of the two flowering

Number of strategies (Fig. 7). The El is usually greater in sites 266 56 238 198 55 mixed sites than in PF sites {Table 8). Plants at

Acta phytogeographica suecica 76 152 Bj orn Widen

these sites are often intermediate between CF and Table 8. Average El and average HI of CF and PF plants and strategy of PF plants (proportion of inflorescences borne PF plants. PF plants have a higher proportion of on the current year's growth) at mixed sites. The sites are inflorescences on the previous year's growth and a grouped according to frequency of PF plants. Number of plants and SD in brackets. lower HI than PF plants in PF sites. CF plants Frequency of PF plants have a higher HI than CF plants in CF sites. There 2 3 is a correlation between frequency of PF plants at Average El 6.5 6.8 6.2 6.3 mixed sites and the average HI of both PF and CF plants (Table 8). PF strategy 3.9{26,1.53) 3.8{26,1.78) 4.4{15,1 .72) 5.2{48,2.05)

HI of PF plants 5.2{26,3.02) 5.0(26,1.97) 5.7(15,2.55) 7.1 {48,2.76)

Hl of CF plants 3.8{104,1 .86) 4.1 {39,2.04) 4.7{10,2.58) 4.8{1 2,1 .64) Discussion

There is a continuous variation in pubescence in H. oelandicum on Oland, as is illustrated by the distri­ on Oland, based on both flowering strategy and bution of HI (Fig. 4). The average HI of the two pubescence. J anchen (1907), on the other hand, flowering strategies differs, but there is much questioned the variation in flowering time and sug­ overlapping. The HI is an exact and reliable gested one species with two forms based on varia­ estimate of the frequency of trichomes (Table 4), tion in pubescence only. Widen (1986}, in a pre­ that summarizes the variation in the two main liminary report on biosystematic studies of the types of trichomes, stellate hairs and bristles. Al­ group, suggested that the morphs on Oland are though several authors (Tornblom 1908, Du Rietz closely related, and that the important evolutio­ 1923) have stressed the discontinuity between the nary character is flowering strategy (Widen 1980, two types of trichomes, intermediates occur 1982). especially in the inflorescence. The third type of Several authors have noted the continuous varia­ trichomes, glandular hairs, has not been reported tion in pubescence. Janchen (1907) stressed the earlier for plants on Oland (cf. Widen 1986}, but continuous variation in the covering of stellate is an important taxonomic character in some taxa hairs on the lower surface of the leaves. Tornblom of the group (Tutin et al. 1968). The small size of (1908) observed the continuous variation in stellate these hairs makes them less easy to quantify and hairs, and also the continuous variation from they are thus not included in the HI. wholly glabrous plants to more densely pubescent Cultivation in a controlled environment revealed plants. Sterner (1936 a) considered that interme­ that variation in pubescence is genetically deter­ diates with respect to stellate hairs were rare. mined, although most sites had a lower average HI The variation in pubescence is not randomly in cultivation than in the field. The lower HI in distributed on Oland, but significantly spatially cultivation is probably explained by my tendency structured. Each local population is characterized to underestimate the number of hairs on the larger by its own 'finger-print' in distribution of plants leaves in cultivated plants. with different HI's (Fig. 5). There is a group of CF

The great variation in pubescence has long been sites dominated by glabrous plants (HI = 0}, for recognized. Many authors have stressed discon­ instance sites 27 and 28 in section C and site 51 in tinuities, and several taxa have been described. section G (Fig. 6). In most CF sites glabrous plants Hartman (1820) recognized f. canescens, with are not more common than plants with other HI's dense pubescence and Fries (1823) f. praecox, with and in some sites there are no glabrous plants. CF sparse pubescence. The wholly glabrous plants plants with a high HI are common in some restric­ were early recognized as f. denudatum (Ahlquist ted areas, such as the alvar area west of the village 1821). The differences in pubescence between of Stemisa (sites 35, 235, 67, 267, 367). Plants col­ flowering strategies (Fig. 4) were early observed lected here are often reported as H. canum (Sterner (Fries 1823). From the taxonomical point of view, 1938). However, all plants I have seen in this area Sterner (1936 a) represents one extreme. He sug­ are CF plants. Glabrous PF plants are rare and are gested three species in the H. oelandicum complex only found at mixed sites. Sites dominated by PF

Acta phytogeographica suecica 76 Variation in pubescence of Helianthemum oelandicum 153

plants with a high HI ( > 12) are relatively rare and plants represent the only morph present in north­ at most PF sites the average HI is 8-10. A few PF ern bland. In reality, glabrous plants dominate in sites, especially south of Stora Alvaret, have a low section G, but there are areas dominated by pub­ average HI, for instance site 1 in section A (Fig. 5), escent plants (Fig. 6). which cannot be distinguished from CF sites with The edaphic and other abiotic conditions of the a high average HI, such as site 61 in section E (Fig. open alvar grasslands of bland are unique. The 5). more or less horizontal bedrock and the low ridges Variation in HI is constant over both large and of Quarternary deposits (Konigsson 1968 p. 49) small areas. Variation in isolated alvar areas, for create a mosaic of vegetation types (Sterner 1925, instance in sections A, F and G, often differs sig­ Albertson 1950), in some of which H. oelandicum nificantly (Fig. 6). In areas with more or less con­ is one of the most common species. Sterner (1936 tinuous populations of H. oe/andicum homogen­ b) listed the most important environmental factors eous areas can be very extensive, the best example influencing the distribution of the species: (a) par­ being the eastern part of section C which is domi­ tial waterlogging in winter, (b) up-lifting through nated by glabrous CF plants (Figs. 6 and 11). In alternate freezing and thawing in winter and early the northern part of the distribution of PF plants spring, (c) drought in summer and (d) the pH and there is an area of c. 1 km2 characterized by a nutritional status of the soil. The three factors a-c high average HI (Figs. 6-8). are more or less dependent on the local drainage Changes in HI can be gradual, for instance the conditions. The annual precipitation is low (400- significant southwards decrease in the average HI 450 mm) with periods of drought in most years (see of PF plants (Fig. 8), or abrupt. The most specta­ Widen 1980, Rosen 1982). Precipitation is especial­ cular example is the change in HI when crossing ly low in spring, and well-drained habitats domi­ the boundary between the distribution areas of CF nated by coarse weathered soil ('vittringsgrus') or and PF plants in section B (Fig. 7). Here the aver­ Quarternary deposits dry up earlier than poorly age HI changes by 5 units over 50 m (e.g. in tran­ drained habitats such as shallow basins dominated section 5). A more gradual change over the bound­ by fine-grained soil ('alvarmo'). The frost-induced ary can be seen in transection 9. Abrupt but less movements in the soil are more pronounced in the spectacular changes can be found within flowering poorly drained, shallow basins than in the well­ strategies. This is illustrated by the transections in drained habitats. Thus, early drought is negatively section E (Fig. 12). At the western margin of the al­ correlated with degree of waterlogging and frost­ var few plants are glabrous (site 36 in Figs. 5 and induced movements in winter and early spring. 6). At a distance of 150 m to the east of the margin There is a mosaic distribution of well-drained and there is a significant decrease in the average HI poorly drained habitats with homogeneous en­ (Fig. 12). This trend is the same in all three transec­ vironments over large or small areas in which dis­ tions, i.e. at least within a distance of 400 m in a ruptive natural selection probably favours differ­ north-south direction. ent morphs of H. oelandicum. Several botanists have observed the spatial vari­ The environmental parameters estimated in the ation in pubescence. Most interest has been paid to transection sampling were given scores intended to the variation within PF plants. The dominance of reflect the increasing harshness of the habitat with PF plants without a dense covering of stellate hairs respect to the winter conditions (Table 7). The in­ on the lower surface of the leaves in the southern­ vestigation was carried out during the summer; an most part of Stora Alvaret caused Sterner (1936 a) unsuitable time for estimating drainage conditions, to suggest the presence of the SE European H. ita­ and I therefore classified drainage as good or poor licum subsp. rupijragum. The first to document only. However, soil type, topography and drainage the mosaic distribution of different morphs in sec­ are highly correlated (Table 6). By adding together tion B was Erik Sjogren (in an unpublished re­ the scores of individual environmental factors in port). Sterner (1938) pointed out the dominance of the El, I place the emphasis on drainage condi­ different morphs of CF plants in different parts of tions. This is, of course, a very crude way of mea­ bland. He claimed, for instance, that glabrous suring environmental conditions. A better method

Acta phytogeographica suecica 76 154 B} orn Widen

would be a vegetation analysis (Widen unpub­ 10 lished). However, it could give some preliminary .... PF ..... MIX indications of the environmental background in 8 -o- CF which H. oelandicum has differentiated. It is evident from Fig. 13 that CF and PF plants have different optimal distributions with respect to 6 the environmental index (El). PF plants are the HI most common in well-drained, uneven topo­ 4 graphy, and CF plants in poorly drained, flat areas. However, both flowering strategies have a bimodal distribution, and the average HI decreases 2 the more extreme the habitat becomes (increasing El, Fig. 14) . This can be illustrated by CF sites in 0 1 the northern part of Oland (section G) . Most sites 3 5 7 9 represent poorly drained alvar areas dominated by El glabrous plants (Fig. 6) as at Byerum (sites 45, 50, Fig. 14. Average HI (±S.E.) for PF sites, mixed sites 51). The only area with a high average HI is found (MIX) and CF sites (transection sampling) in different on well-drained gravel on the western coast, south classes of the environmental index (El). of the village of Djupvik (sites 41, 53, 54). In the Stora Alvaret area marginal sites are often better drained and have a higher average HI than sites riation in this complex. It is probable that the dif­ further away, for example, in section E and the ferentiation in pubescence on Oland occurred after eastern part of section C (Fig. 11). The PF site with the arrival of the plant as an adaptation to the spe­ the lowest average HI (no. 1) is found in section A cific edaphic conditions on the island. in a very flat poorly drained alvar area (Fig. 6). There are several reports of ecogeographical va­ The alvar area west of the village of Sebberneby in riation in pubescence (for a review see Levin 1973). section B changes gradually from poorly drained, Clinal variation in indumentum often occurs over flat ground in the eastern part to a better-drained, large geographical areas (Fassett 1942 , MacClin­ uneven topography in the western part. The aver­ tock and Epling 1946, Baker 1954, New 1958, age HI of PF plants is low here (transections 14 Dahlgren 1963). However, microgeographical dif­ and 15 in Fig. 7) and increases slightly from east to ferentiation has also been reported, e.g. in Galium west. On the basis of these results I suggest that na­ pumi/um (Ehrendorfer 1953). In G. pumilum glab­ tural selection favours pubescent plants in well­ rous morphs occur on north-facing slopes and at drained habitats that dry up early in summer, and high altitudes, whereas pubescent forms grow on glabrous or sparsely pubescent plants in poorly south-facing slopes and at lower altitudes. drained habitats that are waterlogged in winter and Plants vary in proportion of inflorescences early spring. The same selective forces act on both borne on the previous year's and the current year's CF and PF plants. growth. At one extreme of the range of variation H. oelandicum belongs to a complex aggregate all inflorescences are borne on the previous year's growth ( CF plants by definition, Widen 1980) which has its main distribution in S and C Europe = (Tutin et al. 1968). The continental H. canum, cha­ and at the other extreme all inflorescences are racterized by a dense covering of stellate hairs on borne on the current year's growth (class no. 9 in the lower surface of the leaves, is the probable an­ Fig. 10). PF plants have at least one well-developed cestor of the Oland morphs (Widen 1986). Extra­ inflorescence on the current year's growth. Rarely, Scandinavian populations of the complex vary in CF plants have one of a few subnormal inflor­ pubescence, e.g. H. canum varies in the covering escences on the current year's growth (1 of 10,000 of stellate hairs on the upper surface of the leaves. plants according to Sterner 1936 b). These plants Thus, the glabrous and sparsely pubescent morphs could be misinterpreted as being PF plants. Inflor­ on Oland represent one extreme of the range of va- escences borne on the current year's growth in PF

Acta phytogeographica suecica 76 Variation in pubescence of Helianthemum oelandicum 155

9 One supporting fact is the gradual increase in HI and proportion of inflorescences borne on the cur­ rent year's growth with the increased proportion of 8 (/) Q) PF plants at mixed sites (Table 8). Another evi­ (/) (/) dence is the PF sites located far from any CF popu­ �(.) 7 lation, reducing the chance of pollen flow. Site 1 in >. g> section A has a very low average HI (Fig. 6) and � 6 in cultivated plants derived from this site a high U5 proportion of inflorescences are borne on the pre­

5 �--�--�--�--�--�--�--�---, vious year's growth (Widen 1982). Thus, plants at 1 3 5 7 9 site 1 resemble CF plants in this respect. Site 1 is El characterized by poor drainage, a condition that favours CF plants (Fig. 13). Thus, the same envi­ Fig. 15. Proportion of inflorescences borne on the cur­ rent year's growth for all PF plants in the transection ronmental factors that favour glabrous and sparse­ sampling (average strategy classes, ± S.E.) in relation to ly pubescent plants also favour early flowering the environmental index El (see text). (CF). This raises the question of whether the CF strategy arose from the PF strategy on Oland. However, the question of if and when the CF stra­ tegy arose from the PF strategy and if so whether plants are retarded during dry years, such as 1975 this occurred before or after the migration of the (see Table 2 in Rosen 1982). Plants in category 2 complex to Oland, cannot be answered on the basis (only one well-developed inflorescence on the cur­ of material presented in this paper. rent year's growth) were interpreted as CF plants in Widen (1980). However, because of the fact that these plants only occur in section B and mainly along the boundary between the distribution areas of CF and PF plants I now interpret them as PF Conclusions plants. This changes the proportion of PF, mixed and CF sites only slightly (cf. Table 7 and Widen 1. There is continuous variation in pubescence in 1980 p. 112). H. oelandicum ranging from wholly glabrous to Plants at mixed sites are intermediate between densely pubescent plants. The variation can be CF and PF plants (Table 8). PF plants there have summarized in a hair index (HI). In general CF a greater proportion of inflorescences borne on the plants are less pubescent than PF plants. previous year's growth and a lower HI than PF 2. Each local population has a characteristic dis­ plants at pure PF sites. Thus PF plants at mixed tribution ('finger-print') of HI's. sites resemble CF plants in this respect. This trend 3. There is a significant correlation between HI was confirmed in cultivation (Widen 1980). There and estimates of the environmental conditions. are two reasonable explanations for this. (1) There 4. The variation in pubescence has arisen on is introgression between CF and PF plants at Oland as an adaptation to the unique habitats mixed sites. Plants of the two flowering strategies in the alvar areas. Natural selection favours are easy to cross artificially and the F1 offspring glabrous or less pubescent plants in poorly have the protracted flowering strategy, but with a drained habitats which are waterlogged in win­ higher proportion of inflorescences borne on the ter and early spring, and pubescent plants in previous year's growth than the PF parents have well-drained habitats that dry up early in sum­ (Widen unpublished). (2) The environmental con­ mer. ditions at mixed sites are intermediate between CF 5. Stellate hairs are poor taxonomical characters and PF habitats, and natural selection favours one in the H. oelandicum complex-the character or the other flowering strategy. There are several of greatest importance for evolution on Oland lines of evidence supporting this interpretation. is flowering strategy.

Acta phytogeographica suecica 76 156 Bj orn Widen

Acknowledgements. Financial support was provided by Konigsson, L.-K. 1968. The holocene history of the the Enander Foundation, the Anna and Svante Murbeck Great Alvar of bland. - Acta phytogeogr. suec. 55: Foundation, the C. F. 0. Nordstedt Foundation, the 1-172. Lund Botanical Society and the University of Lund. The Levin, D. A. 1973. The role of trichomes in plant de­ field work was carried out at Uppsala University Ecolo­ fense. - Q. Rev. Bioi. 48: 3-15. gical Station at blands Skogs by. I wish to thank Hans MacClintock, E. & C. Epling, 1946. A revision of Teuc­ Runemark for valuable discussions during the work, rium in the New World with observation on its varia­ Margaret; Greenwood-Petersson for linguistic advice and tion, geographical distribution, and history. - Brit­ Marie Widen for technical assistance. tonia 5: 491-510. Neuman, L. M. 1901. Sveriges flora. - Lund. 832 pp. New, J. K. 1958. A population study of Spergula arven­ sis. -Ann. Bot. N. S. 22: 457-477. Rosen, E. 1982. Vegetation development and sheep graz­ ing in limestone grasslands of south bland, Sweden. -Acta phytogeogr. suec. 72: 1-104. References Sokal, R. R. & Rohlf, F. J. 1981. Biometry. The prin­ ciples and practice of statistics in biological research. Albertson, N. 1950. Das grosse siidlicheAlvar der Insel - San Francisco. bland. Eine pflanzensoziologische Ubersicht. - Sterner, R. 1925 . Einige Notizen iiber dieVegetation der Svensk bot. Tidskr. 44: 269-331. Insel bland. - Svensk bot. Tidskr. 19: 303-346. Ahlquist, A. 1821. Anmarkningar om blands fysiska be­ - 1936 a. Helianthemum oelandicum (L.) Willd. och skaffenhet och vegetation. - K. svenska Vetensk. dess anforvanter pa bland. - Svensk bot. Tidskr. Akad. handl. 1821: 278-304. 30: 419-432. Baker, H. G. 1954. Report of meeting of British Ecolo­ - 1936 b. Ekologiska iakttagelser over Helianthemum gical Society, April 1953. - J. Ecol. 42: 570-572. oelandicum (L.) Willd. - Acta Horti gotoburg. 11: Dahlgren, R. 1963. Studies on Aspalathus. Phytogeo­ 183-208. graphical aspects. - Bot. Notiser 116: 43 1-472. - 1938. Flora der Insel bland. - Acta phytogeogr. Davis, P. H. 1965. Flora of Turkey and East Aegean is­ suec. 9: 1-169. lands. 1. -Edinburgh. Tutin, T. G. et al. 1968. Flora Europaea 2. - Cam­ Du Rietz, G. E. 1923. De svenska Helianthemum­ bridge. arterna. - Bot. Notiser 76: 435-446. Tornblom, G. 1908. Iakttagelser ofver Helianthemum Ehrendorfer, F. 1953. bkologisch-geographische Mikro­ canum (L.) Baumg. och H. oelandicum (L.) Willd. differzierung einer Population von Galium pumilum pa blands alvar. - Svensk bot. Tidskr. 2: 32-37. Murr. s. str. - bst. bot. Z. 100: 616-638. Wahlenberg, G. 1826. Flora suecica. - Uppsala. 1117 Fassett, N. C. 1942. Mass collections: Diervilla lonicera. pp. - Bull. Torrey Bot. Club. 69: 317-322. Widen, B. 1980. Flowering strategies in the Helianthe­ Fries, E. 1823. Novitiae Florae suecicae. - Lund. mum oelandicum (Cistaceae) complex on bland, Grosser, W. 1903. Cistaceae. - Pflanzenreich IV: 193. Sweden. -Bot. Notiser 133: 99-115. Leipzig. - 1982. Reproductive biology in the Helianthemum oe­ Hartman, C. 1820. Handbok i skandinaviens flora. - landicum (Cistaceae) complex on bland, Sweden. - Stockholm. 488 pp. Ph.D. Thesis, University of Lund. Janchen, E. 1907 . Helianthemum canum (L.) Baumg. - 1986. Biosystematics in the Helianthemum oelandi­ und seine nachsten Verwandten. - Abh. zool.-bot. cum complex on bland. - Symb. bot. upsal. 27: Ges. Wien 4: (1). 53-60.

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ACTA PHYTOGEOGRAPHICA SUECICA

1. E. Almquist, Upplands vegetation och flora. 8. R. Sernander, Granskar och Fiby urskog. En studie (Vegetation and flora of Uppland.) 1929. ISBN over stormluckornas och marbuskarnas betydelse i 91-7210-001-X. den svenska granskogens regeneration. (Summary: 2. S. Th unmark, Der See Fiolen und seine Vegetation. The primitive forests of Granskar and Fiby. A study 1931. 60:-. ISBN 91-7210-002-8. of the part played by storm-gaps and dwarf trees in 3. G. E. Du Rietz, Life-forms of terrestrial flowering the regeneration of the Swedish spruce forest.) 1936. plants. I. 1931. 40:-. ISBN 91-7210-003-6. 65:-. ISBN 91-7210-008-7. 4. B. Lindquist, Om den vildvaxande skogsalmens 9. R. Sterner, Flora der Insel Oland. Die Areale der raser och deras utbredning i Nordvasteuropa. (Sum­ Gefarsspflanzen Olands nebst Bemerkungen zu mary: The races of spontaneous Ulmus glabra ihrer Oekologie und Soziologie. 1938. ISBN Huds. and their distribution in NEW. Europe.) 91-7210-009-5. 1932. ISBN 91-7210-004-4. 10. B. Lindquist, Dalby Soderskog. En skansk lovskog 5. H. Osvald, Vegetation of the Pacific coast bogs of i forntid och nutid. (Zusammenf.: Ein Laubwald in North America. 1933. 30:-. ISBN 91-7210-005-2. Schonen in der Vergangenheit und Gegenwart.) 6. G. Samuelsson, Die Verbreitung der hoheren 1938. 70:-. ISBN 91-721 0-010-9. Wasserpflanzen in Nordeuropa. 1934. ISBN 11. N. Stdlberg, Lake Vattern. Outlines of its natural 91-7210-006-0. history, especially its vegetation. 1939. 30:-. ISBN 7. G. Dege/ius, Das ozeanische Element der Strauch­ 91-7210-011-7. und Laubflechtenflora von Skandinavien. 1935. 12. G. E. Du Rietz, A. G. Ha nnerz, G. Lohammar, R. ISBN 91-7210-007-9. Santesson & M. Wrern, Zur Kenntnis der Vegetation

Acta phytogeographica suecica 76 158 Svenska viixtgeograjiska siillskapet

des Sees Takern. 1939. 30:-. ISBN 91-7210-012-5. Karlvaxtfloran i sydvastra Lule Lappmark. (Sum­ 13. Vtixtgeografiska studier tilllignade Car! Skottsberg mary: Vascular flora.) 1950. 45:-. ISBN pa sextioarsdagen 1112 1940. (Geobotanical studies 91-7210-028-1. dedicated to C. Skottsberg.) 1940. 75:-. ISBN 29. M. Fr ies, Pollenanalytiska vittnesbord om senkvar­ 91-7210-013-3. tar vegetationsutveckling, sarskilt skogshistoria, i 14. N. Hy lander, De svenska formerna av Mentha gen­ nordvastra Gotaland. (Zusammenf.: Pollenanalyti­ tilis L. coil. (Zusammenf.: Die schwedischen sche Zeugnisse der spatquartaren Vegetationsent­ Formen der Mentha gentilis L. sensu coil.) 1941. wicklung, hauptsachlich der Waldgeschichte, im 30:-. ISBN 91-7210-014-1. nordwestlichen Gotaland, Siidschweden.) 1951. 15. T. E. Hasselrot, Till kannedom om nagra nordiska 60:-. ISBN 91-7210-029-X. umbilicariaceers utbredning. (Zusammenf.: Zur 30. M. Wcern, Rocky-shore algae in the bregrund Ar­ Kenntnis der Verbreitung einiger Umbilicariaceen in chipelago. 1952. 75:-. ISBN 91-7210-030-3. Fennoscandia.) 1941. 40:-. ISBN 91-7210-015-X. 31. Rune, Plant life on serpentines and related rocks 0. 16. G. Samuelsson, Die Verbreitung der Alchemilla­ in the North of Sweden. 1953. 40:-. ISBN Arten aus der Vulgaris-Gruppe in Nordeuropa. 91-7210-03 1-1. 1943. 50:-. ISBN 91-7210-016-8. 32. P. Kaaret, W asservegetation der Seen Orlangen und 17. Th . Arwidsson, Studien iiber die Gefasspflanzen in Trehorningen. 1953. 30:-. ISBN 91-7210-032-X. den Hochgebirgen der Pite Lappmark. 1943. 70:-. 33. T. E. Hasselrot, Nordliga lavar i Syd- och Mellan­ ISBN 91-7210-017-6. sverige. (Nordliche Flechten in Siid- und Mit­ 18. N. Dahlbeck, Strandwiesen am siidostlichen Ore­ telschweden.) 1953. 55:-. ISBN 91-7210-033-8. sun d. (Summary: Salt marshes on the S. E. coast of 34. H. Sj ors, Slatterangar i Grangarde finnmark. (Sum­ bresund.) 1945. 40:-. ISBN 91-7210-01 8-4. mary: Meadows in Grangarde Finnmark, SW. 19. E. von Krustenstjerna, Bladmossvegetation och Dalarna, Sweden. . ) 1954. 45:-. ISBN bladmossflora i Uppsalatrakten. (Summary: Moss 91-7210-034-6. flora and moss vegetation in the neighbourhood of 35. S. Kilander, Karlvaxternas ovre granser pa fjall i Uppsala.) 1945. 80:-. ISBN 91-7210-01 9-2. sydvastra Jamtland samt angransande delar av Har­ 20. N. Albertson, bsterplana bed. Ett alvaromrade pa jedalen och Norge. (Summary: Upper limits of Kinnekulla. (Zusammenf. : bsterplana hed. Ein vascular plants on mountains in Southwestern Alvargebiet auf dem Kinnekulle.) 1946. 50:-. ISBN Jamtland and adjacent parts of Harjedalen 91-7210-020-6. (Sweden) and Norway.) 1955. 50:-. ISBN 21. H. Sj ors, Myrvegetation i Bergslagen. (Summary: 91-7210-035-4. Mire vegetation in Bergslagen, Sweden.) 1948. 36. N. Quennerstedt, Diatomeerna i Langans sjovegeta­ 75:-. ISBN 91-7210-021-4. tion. (Summary: Diatoms in the lake vegetation of 22. S. Ahlner, Utbredningstyper bland nordiska barr­ the Langan drainage area, Jamtland, Sweden.) tradslavar. (Zusammenf. : Verbreitungstypen unter 1955. 50:-. ISBN 91-7210-036-2. fennoskandischen N adelbaumflechten.) 1948. 70:-. ISBN 91-7210-022-2. 37. M. -B. Fl orin , Plankton of fresh and brackish waters in the Sodertalje area. 1957. 40:-. ISBN 23. E. Julin , Vessers udde, Mark och vegetation i en 91-7210-037-0. igenvaxande lOvang vid Bjarka-Saby. (Zusammenf.: Vessers udde. Boden und Vegetation in einer ver­ 38. M.-B. Florin , Insjostudier i Mellansverige. wachsenden Laubwiese bei Bjarka-Saby in Mikrovegetation och pollenregn i vikar av bster­ bstergotland , Siidschweden.) 1948. 50:-. ISBN sjobackenet och insjoar fran preboreal tid till nutid. 91-7210-023-0. (Summary: Lake studies in Central Sweden. 24. M. Fries , Den nordiska utbredningen av Lactuca Microvegetation and pollen rain in inlets of the alpina, Aconitum septentrionale, Ranunculus Baltic basin and in lakes from Preboreal time to the platanifolius och Polygonatum verticillatum. present day.) 1957. 25 :-. ISBN 91-7210-038-9. (Zusammenf. : Die nordische Verbreitung von Lac­ 39. M. Fr ies, Vegetationsutveckling och odlingshistoria tuca alpina ...) 1949. 30:-. ISBN 91-7210-24-9. i Varnhemstrakten. En pollenanalytisk undersok­ 25. Gjcerevoll, Sneleievegetasjonen i Oviksfjellene. ning i Vastergotland. (Zusammenf. : Vegetationsent­ 0. (Summary: The snow-bed vegetation of Mts Oviks­ wicklung und Siedlungsgeschichte im Gebiet von fj allen, Jamtland, Sweden.) 1949. 40:-. ISBN Varnhem. Eine pollenanalytische Untersuchung aus 91-7210-025-7. Vastergotland (Siidschweden).) 1958. 35:-. ISBN 26. H. Osvald, Notes on the vegetation of British and 91-7210-039-7. Irish mosses. 1949. 30:-. ISBN 91-7210-026-5. 40. Bengt Pettersson, Dynamik och konstans i Gotlands 27 . S. Selander, Floristic phytogeography of South­ flora och vegetation. (Resume: Dynamik und Western Lule Lappmark (Swedish Lapland). I. Konstanz in der Flora und Vegetation von Gotland, 1950. 55:-. ISBN 91-7210-027-3. Schweden.) 1958. 90 :-. ISBN 91-7210-040-0. 28. S. Selander, Floristic phytogeography of South­ 41. E. Uggla, Skogsbrandfalt i Muddus nationalpark. Western Lule Lappmark (Swedish Lapland). 11. (Summary: Forest fire areas in Muddus National

Acta phytogeographica suecica 76 Svenska viixtgeografiska siillskapet 159

Park, Northern Sweden.) 1958. 40:-. ISBN 56. H. P. Hallberg, Vegetation auf den Schalenbla­ 91-7210-041-9. gerungen in Bohuslan, Schweden. (Summary: Vege­ 42. K. Th omasson, Nahuel Huapi. Plankton of some tation on shell deposits in Bohuslan, Sweden.) 1971. lakes in an Argentina National Park, with notes on 70:-. ISBN 91-7210-056-7 (ISBN 91-7210-456-2). terrestrial vegetation. 1959. 40:-. ISBN 57. S. Fransson, Myrvegetation i sydvastra Varmland. 91-7210-042-7. (Summary: Mire vegetation in south-western Varm­ 43. V. Gillner, Vegetations- und Standortsunter­ land, Sweden.) 1972. 70:-. ISBN 91-7210-057-5 suchungen in den Strandwiesen der schwedischen (ISBN 91-7210-457-0). Westkiiste. 1960. 55:-. ISBN 91-7210-043-5. 58. G. Wa llin , Lovskogsvegetation i Sjuharadsbygden. 44. E. Sj ogren , Epiphytische Moosvegetation in Laub­ (Summary: Deciduous woodlands in Sjuharadsbyg­ waldern der Insel Gland, Schweden. (Summary: den, Vastergotland, south-western Sweden.) 1973. Epiphytic moss communities in deciduous woods on 70:-. ISBN 91-7210-058-3 (ISBN 91-7210-458-9). the island of Gland, Sweden.) 1961. 45:-. ISBN 91- 59. D. Jo hansson , Ecology of vascular epiphytes in 7210-044-3 (ISBN 91-7210-444-9). West African rain forest. (Resume: Ecologie des 45. G. Wistrand, Studier i Pite Lappmarks karlvaxt­ epiphytes vasculaires dans la foret dense humide flora, med sarskild hansyn till skogslandet och de d'Afrique occidentale.) 1974. 80:-. ISBN 91-7210- isolerade fj allen. (Zusammenf.: Studien iiber die 059-1 (ISBN 91-7210-459-7). Gefasspflanzenflora der Pite Lappmark mit 60. H. Olsson, Studies on South Swedish sand vegeta­ besonderer Beriicksichtigung des W aldlandes und tion. 1974. 95:-. ISBN 91-7210-060-5 (ISBN der isolierten niederen Fjelde.) 1962. 55:-. ISBN 91-721 0-460-0). 91-7210-045-1 (ISBN 91-7210-445-7). 61. H. Hy tteborn, Deciduous woodland at Andersby, 46. R. Ivarsson , Lovvegetation i Mollosunds socken. Eastern Sweden. Above-ground tree and shrub pro­ (Zusammenf.: Die Laubvegetation im Kirchspiel duction. 1975. 70:-. ISBN 91-7210-061-3 (ISBN Mollosund, Bohuslan, Schweden.) 1962. 50:-. 91-7210-461-9). ISBN 91-7210-046-X (ISBN 91-7210-446-5). 62. H. Persson, Deciduous woodland at Andersby, 47. K. Th omasson, Araucanian Lakes. Plankton studies Eastern Sweden: Field-layer and below-ground pro­ in North Patagonia, with notes on terrestrial vegeta­ duction. 1975. 60:-. ISBN 91-7210-062- 1 (ISBN tion. 1963. 55:-. ISBN 91-7210-047-8. 91-7210-462-7). 48. E. Sj ogren , Epilitische und epigaische Moosvegeta­ 63. S. Brdkenhielm, Vegetation dynamics of afforested tion in Laubwaldern der lnsel Gland, Schweden. farmland in a district of South-eastern Sweden. (Summary: Epilithic and epigeic moss vegetation in 1977. 80:-. ISBN 91-7210-063-X (ISBN deciduous woods on the island of Gland, Sweden.) 91-7210-463-5). 1964. 70:-. ISBN 91-7210-048-6 (ISBN 64. M. Ammar, Vegetation and local environment on 91-7210-448-1). shore ridges at Vickleby, Gland, Sweden. An 49. Hedberg , Features of afroalpine plant ecology. analysis. 1978. 80:-. ISBN 91-7210-064-8 (ISBN 0. (Resume fran�ais.) 1964. 70:-. ISBN 91-7210-049-4 91-7210-464-3). (ISBN 91-7210-449-X). 65. L. Kullman, Change and stability in the altitude of 50. The Plant Cover of Sweden. A study dedicated to G. the birch tree-limit in the southern Swedish Scandes Einar Du Rietz on his 70th birthday by his pupils. 1915-1975 . 1979. 80:-. ISBN 91-7210-065-6 1965. 130:-. ISBN 91-7210-050-8. (ISBN 91-7210-465-1). 51. T. Flensburg, Desmids and other benthic algae of 66. E. Waldemarson Jensen , Successions in relationship Lake Kavsjon and Store Mosse. SW Sweden. 1967 . to lagoon development in the Laitaure delta, North 60:-. ISBN 91-7210-05 1-6 (ISBN 91-7210-451-1). Sweden. 1979. 80:-. ISBN 91-7210-066-4 (ISBN 52. E. Skye, Lichens and air pollution. A study of cryp­ 91-7210-466-X). togamic epiphytes and environment in the 67. S. Tuhkanen , Climatic parameters and indices in Stockholm region. 1968. 80:-. ISBN 91-7210-052-4 plant geography. 1980. 80:-. ISBN 91-7210-067-2 (ISBN 91-7210-452-X). (ISBN 91.7210-467 -8). 53. Jim Lundqvist, Plant cover and environment of 68. Studies in plant ecology dedicated to Hugo Sjors. steep hillsides in Pite Lappmark. (Resume: La Ed. Erik Sjogren. 1980. 110:-. ISBN 91-7210-068-0 couverture vegetale et !'habitat des flancs escarpes (ISBN 91-7210-468-6). des collines de Pite Lappmark.) 1968. 70:-. ISBN 69. C. Nilsso n, Dynamics of the shore vegetation of a 91-7210-053-2 (ISBN 91-7210-453-8). North Swedish hydro-electric reservoir during a 5- 54. Conservation of Vegetation in Africa South of the year period. 1981. 80:-. ISBN 91-7210-069-9 (ISBN Sahara. Proc. of symp. at 6th plen. meeting of 91-7210-469-4). AETFAT. Ed. by lnga and Olov Hedberg. 1968. 70. K. Warenberg, Reindeer forage plants in the early 90:-. ISBN 91-7210-054-0 (ISBN 91-7210-454-6). grazing season. Growth and nutritional content in 55. L.-K. Konigsson, The Holocene history of the Great relation to climatic conditions. 1982. 80:-. ISBN Alvar of Gland. 1968. 90:-. ISBN 91-7210-055-9 91-7210-070-2 (ISBN 91-7210-470-8). (ISBN 91-7210-455-4). 71. C. Johansson, Attached algal vegetation in running

Acta phytogeographica suecica 76 160 Svenska viixtgeografiska siillskapet

waters of Jamtland, Sweden. 1982. 85:-. ISBN 91- 75. E. Gunnlaugsd6ttir, Composition and dynamical 7210-071-0 (ISBN 91-7210-47 1-6).- status of heathland communities in Iceland in rela­ 72. E. Rosen , Vegetation development and sheep graz­ tion to recovery measures. 1985. 95:-. ISBN 91- ing in limestone grasslands of south bland, Sweden. 7210-075-3 (ISBN 91-7210-475-9). 1982. 100:-. ISBN 91-7210-072-9 (ISBN 76. Ed. Erik Sj ogren . Plant cover on the limestone 91-7210-472-4). Alvar on Gland. Ecology-Sociology-Taxonomy. 73. L. Zhang, Vegetation ecology and population biol­ 1988. 120:-. ISBN 91-7210-076-1 (ISBN ogy of Fritillaria meleagris L. at the Kungsangen 91-7210-476-7). Limited number of cloth-bound copies of Acta 45, Nature Reserve, Eastern Sweden. 1983. 95:-. ISBN 44, 91-7210-073-7 (ISBN 91-7210-473-2). 46, 48, 49, 51, 52, 53, 56, 57, 61, 63, 66, 67, 68, 69, 70, 74. Backeus, Aboveground production and growth 71, 72, 73, 74, 75, 76 are available through the Society I. dynamics of vascular bog plants in central Sweden. at an additional cost of 20:- per copy. ISBN nos. in 1985. 95:-. ISBN 91-7210-074-5 (ISBN brackets refer to cloth-bound copies. Nos. 1, 4, 6, 7, 9 91-7210-474-0. are out of print.

STUDIES IN PLANT ECOLOGY (vols. 1-15 V AXTEKOLOGISKA STUDIER)

1. S. Brdkenhielm & T. lngelog, Vegetationen i 9. J. Lundqvist & G. Wistrand, Strandflora inom ovre Kungshamn-Morga naturreservat med forslag till och mellersta Skelleftealvens vattensystem. Med en skotselplan. (Summary: Vegetation and proposed sammanfattning betraffande botaniska skydds­ management in the Kungshamn-Morga Nature varden. (Summary: Riverside vascular flora in the Reserve south of Uppsala.) 1972. 30:-. ISBN upper and middle catchment area of the River 91-7210-801-0. Skelleftealven , northern Sweden.) 1976. 35:-. 2. T. Inge/Ov & M. Risling, Kronparken vid Uppsala, ISBN 91-721 0-809-6. historik och bestandsanalys av en 300-Arig tallskog. 10. A. MiU/er-Haeckel, Migrationsperiodik einzelliger (Summary: Kronparken, history and analysis of a Algen in Fliessgewassern. 1976. 20:-. ISBN 300-year old pinewood near Uppsala, Sweden.) 91-7210-810-X. 1973. 30:-. ISBN 91-7210-802-9. 11. A. Sj odin , Index to distribution maps of bryophytes 3. H. Sj ors och medarb., Skyddsvarda myrar i Kop­ 1887-1975. I. Musci. 1980. 60:- (hard-bound). parbergs lan. (Summary: Mires considered for pro­ ISBN 91-7210-811-8. tection in Kopparberg County (Prov. Dalarna, Cen­ 12. A. Sjodin , Index to distribution maps of bryophytes tral Sweden).) 1973. 30:-. ISBN 91-7210-803-7. 1887-1975. 11. Hepaticae. 1980. 40:- (hard­ 4. L. Kar/sson, Autecology of cliff and scree plants in bound). ISBN 91-7210-812-6. 13. Eriksson, T. Palo & L. Soderstrom, Renbetning Sarek National Park, northern Sweden 1973. 40:-. 0. ISBN 91-7210-804-5. vintertid. Undersokningar rorande svensk tamrens 5. B. K/asvik, Computerized analysis of stream algae. naringsekologi under snoperioden. 1981. 30:-. 1974. 30:-. ISBN 91-7210-805-3. ISBN 91-7210-813-4. 6. Dahlstrom-Ekbohm, Svensk miljovards- och 14. G. Wistrand, Bidrag till Pite lappmarks vaxt­ Y. omgivningshygienlitteratur 1952-1 972. Bibliografi geografi. 1981. 35:-. ISBN 91-7210-814-2. och analys. 1975. 30:-. ISBN 91-7210-806-1. 15. T. Karlsson, Euphrasia rostkoviana i Sverige. 1982. 7. L. Rodenborg, Bodennutzung, Pflanzenwelt und 40:-. ISBN 91-7210-815-0. ihre Veranderungen in einem alten Veidegebiet auf 16. Th eory and models in vegetation science: Abstracts. Mittel-Oland, Sweden. 1976. 30:-. ISBN Ed. Rik Leemans, I. Colin Prentice & Eddy van der 91-7210-807-X. Maarel. 1985. 50:-. ISBN 91-7210-816-9. 8. H. Sj ors & Ch. Ni/sson, Vattenutbyggnadens ef­ 17. Backeus, Mires in the Thaba-PutSoa Range of I. fekter pa levande natur. En faktaredovisning over­ the Maloti, Lesotho. 1988. 50:-. ISBN vagande fran Umealven. (Summary: Bioeffects of 91-7210-8 17-7. hydroelectric development. A case study based mainly on observations along the Ume River, north­ ern Sweden.) 1976. 45:-. ISBN 91-7210-808-8.

Distributors: Svenska Vaxtgeografiska Sallskapet, Box 559, S-751 22 Uppsala, Sweden. Almqvist & Wiksell International, Box 62, S-101 20 Stockholm, Sweden.

Acta phytogeographica suecica 76

Distributor: Almqvist & Wiksell International, Stockholm, Sweden ISBN 91-72 10-076-1 ISSN 0084-5914