ACTA PHYTOGEOGRAPHICA SUECICA 74 EDIDIT SVENSKA V AXTGEOGRAFISKA SALLSKAPET

lngvar Backeus

Aboveground production and growth dynamics of vascular bog plants in Central Sweden

UPPSALA 1985

ACTA PHYTOGEOGRAPHICA SUECICA 74 EDIDIT SVENSKA V AXTGEOGRAFISKA SALLSKAPET

lngvar Backeus

Aboveground production and growth dynamics of vascular bog plants in Central Sweden

Almqvist Wiksell International, Stockholm & UPPSALA 1985 Doctoral thesis at Uppsala University 1985

ISBN 91-7210-074-5 (paperback) ISBN 91-7210-474-0 (cloth) ISSN 0084-5914

Backeus, I. 1985: Abovegroundproduction and growth dynamics of vascular bog plants in Cen­ tral Sweden. Acta Phytogeogr. Suec. 74, 98 pp. ISBN 91-7210-074-5; ISBN 91-7210-740-0.

Aboveground primary production and biomass of the field layer plants were studied on an om­ brotrophic mire in the central Swedish uplands. The study was made on the population level, and results on the population ecology of certain species were also obtained. The study included Andromeda polifolia, Betula nana, Calluna vulgaris, Drosera anglica, D. rotundifolia, Empet­ rum nigrum s.str., Eriophorum vaginatum, Rhynchospora alba, Rubus chamaemorus, Scheuchzeria palustris, Trichophorum caespitosum, Vaccinium microcarpum, V. oxycoccos and V. uliginosum. Production and biomass per unit area of each species and of modules (leaves, inflorescences, etc.) of certain species were determined from figures on mean individual weight and mean density. Aboveground biomass of vascular plants was estimated at 2700 kg· ha·1 on hummocks, 682 kg· ha·1 in 'lawns' and 310-390 kg· ha·1 in two kinds of 'carpets' (Cuspidatetum dusenietosum and C. tenelletosum Fransson, respectively). Total aboveground production of vascular plants was 830, 610, 360 and 340 kg · ha·1 • year·1, respectively. Growth in some species was followed throughout the growing season through repeated har­ vesting. Seasonal variation in weight of individual leaves was similarly followed in evergreen species. Length growth of shoots of six species and length growth of leaves in two monocots were followed through direct measurements. Length growth rate of B. nana and Calluna shoots and of Scheuchzeria leaves was shown to be closely dependent on temperature, while growth of E. vaginatum leaves was not. Two peaks in production were found: (1) during shoot formation in June and (2) in August when perennial leaves were becoming winter-hardened and wood increment in Calluna and An­ dromeda (remarkably late) took place. Seasonal changes in biomass were comparatively small because of evergreenness in the dominant species. Survivorship ofleaves of certain species was studied. Flowering was poor and seedlings absent in most species. Instead plants were propagated vegetatively, and different means for such pro­ pagation are discussed. The interactions between the field and bottom layer plants are also dis­ cussed, notably how the former avoid being overgrown by mosses.

Ingvar Backeus, Institute of Ecological Botany, Box 559, S-751 22 Uppsala, Sweden

© Ingvar Backeus 1985 Svenska Vaxtgeografiska Sallskapet Box 559, 75 1 22 Uppsala

Editor: Erik Sjogren Technical editor: Gunnel Sjors

Phototypesetting: Textgruppen i Uppsala AB Printed in Sweden 1985 by Borgstroms Tryckeri AB, Motala Contents

Th e study area 7 Topography and geology 7 Climate and weather 7 Temperature 7, Precipitation 11 Vegetation 12 Description of the sampling areas 15

Phenological development 17 Methods of collecting and presenting the phenological data 17 Results and discussion 17

Production and dy namics of individual species 20 Methods 20 Andromeda polifolia 21 Betula nana 26 Calluna vulgaris 28 Carex limosa 33 Carex pauciflora 33 Drosera anglica 33 Drosera rotundifolia 34 Empetrum nigrum 35 Eriophorum vaginatum 39 Rhynchospora alba 48 Rubus chamaemorus 51 Scheuchzeria palustris 56 Trichophorum caespitosum 60 Vaccinium microcarpum 62 Vaccinium oxycoccos 63 Vaccinium uliginosum 64

Field layer density, biomass and production 68 Discussion on methods 68 Density 72 Mean total aboveground biomass and production 72 The seasonal course of the total aboveground production and changes in the total aboveground biomass 77 The seasonal course of production 77, Seasonal changes in biomass 77 Variations between years in production 80 The dependence on environmental variables of length growth in stems and leaves 81 4 lngvar Backeus

Th e bog environment and the behaviour of plants 84 Rate of production 84 Flowering and reproduction 85 Vegetative propagation 86 Moss overgrowth 87 Grime's C-, S- and R-selection 88 Age structure of modules 89 Interdependence of ramets 90 Concluding remarks 91

References 92 Introduction

Works in production ecology, e.g.within the Inter­ possible to draw more general conclusions about the national Biological Programme, have often been response of plants to the particular environment ecosystem-oriented. Great efforts have been made that was studied. to obtain figures on the total biomass and produc­ The aim of my investigation has been to find out tion in various ecosystems. The work input in this the distribution of production in time and space kind of investigation is considerable also when only (within a plant and within the site) of all field layer moderate resolution is accepted and time-consum­ plants (including Betula nana) on an ombrotrophic ing harvesting, sorting and weighing are necessary. mire. The amount of work and numerous methodo­ It is also possible to make production ecological logical problems made it necessary to exclude the studies on the population level. By working out suit­ bottom layer and the rhizosphere as well as decom­ able techniques for all or the more important spe­ position at this stage. This limitation of course has cies, figures on total production can be obtained caused gaps in my results that will have to be filled also by such an approach, which is attempted in this before a reasonably good understanding of the pro­ treatise. duction on the bog can be obtained. The aim is somewhat different than in an The ombrotrophic mire is an extreme environ­ ecosystem-oriented study, even though populations ment. There is no input of nutrients except through of organisms are often used as a basis also in the lat­ precipitation. There are several reasons for this ter type of investigation. Other variables are choice of study object, besides the obvious fact that measured and information on density, age struc­ ombrotrophic mires constitute important ecosys­ ture, growth rhythm and growth rate is obtained. tems in Scandinavia and are interesting per se: In contrast to animals, higher plants do not have The vegetation is poor in species and all species a definite size. The size instead varies with the en­ are fairly well distributed within the community. vironment, both the abiotic and the biotic. The indi­ Such a simple system makes it easier to work out vidual 'modules' of the plant, leaves, flowers, etc. methods, and the low number of species makes it usually vary much less (cf. Harper 1978). The study possible to study all species. of these metapopulations (White 1979) refines the Few environmental factors vary within one site. production ecological methodology and increases The water level varies in space in an obvious and our knowledge of the survival potential of the indi­ easily understandable way and lack of water is rare vidual. for the field layer plants. The chemistry of the sub­ Population ecologists usually work with only one strate is very uniform. In time, temperature is an im­ or a few, similar or contrasting, species. Examples portant variable factor and in space (and time) the that will be discussed later are found in Fetcher overgrowth by mosses. & Shaver (1983), Flower-Ellis (1971), Karlsson (1982), The ombrotrophic bog is an unusually well-de­ Noble et al. (1979), Robertson Woolhouse fined ecosystem and this was also a reason for my & (1984a,b), Sarukhan Harper (1973) and Schmid choice. Within a restricted area this ecosystem re­ & (1984). The response of these species to environ­ curs from site to site with very little variation. In a mental factors in different environments is studied. larger area, e.g. Europe or Holarctis, the variation It has been less common to study the response to en­ is certainly greater but still moderate and usually vironmental factors of all the different populations successive. Comparisons with investigations from in a community. Evidently the work on each species other places are therefore easy to make. cannot be very intense in such a study and has to fo­ As a mire ecologist I should also explain why I cus on the main points, but nevertheless it might be have chosen to study production. The mire plants

Acta Phytogeogr. Suec. 74 6 lngvar Backeus form their substrate themselves through production I have had the opportunity to carry out the field and decomposition. Information on total produc­ work on a bog that was previously thoroughly inves­ tion and decomposition must therefore be essential tigated ecologically, the 'Special Area' of the Skatt­ for a better understanding of the mechanisms be­ losberg Stormosse (Sjors 1948). Sjors described in hind the rise of the mire surface and its differentia­ detail the vegetation and the distribution of plants tion into hydromorphological structures, of the re­ and mineral elements in this area. This made it poss­ lations between these structures and of their se­ ible for me to concentrate from the beginning on quence in time. Production and production proces­ production studies without lengthy data collections ses are therefore central problems in mire ecology. concerning the vegetation and environment. Here it must again be emphasized that my investiga­ The field work was carried out in 1980, 1981 and tion is still in its beginning. The aboveground parts 1982, thus giving figures from three successive of the vascular plants contribute very little to the growing periods. peat formation. Peat is mainly formed by mosses Nomenclature for vascular plants follows Moore and below ground parts of vascular plants and a lot (1982), except for Empetrum nigrum v. hermaphro­ of work therefore remains to be done. ditum, which is here treated as a species (E. her­ Important constituents of mire ecology are also maphroditum Hagerup) and Scirpus cespitosus, supply and transport of mineral nutrients (see e.g. which is here called Trichophorum caespitosum (L.) Malmer Nihlgard 1980) and translocations of or­ Hartm. Nomenclature for bryophytes follows Cor­ & ganic nutrients. Neither of these aspects are treated ley et al. (1981) and Grolle (1976) and for lichens here. Santesson (1984).

Acta Phytogeogr. Suec. 74 The study area

The bog Skattlosberg Stormosse is located in the of excentric bogs separated by fen soaks. The soaks, southwestern part of the province of Dalarna (Kop­ except the southern ones, run towards a central big parberg County) in central Sweden (Fig. 1). The soak sloping east and partly consisting of large physical conditions of Bergslagen (i.e. S Dalarna, N flarks. A map of the mire was presented by Sjors Vastmanland and E Varmland) in general and espe­ (1948). cially of the Skattlosberg Stormosse were dealt with by Sj ors (1948: 16-32 and 68-104 in Swedish; 277-278 and 282-284 in English). Also the vegeta­ Climate and weather tion and flora of the Skattlosberg Stormosse were

described in detail by Sjors (op. cit.: 105-171 in Temperature Swedish; 284-286 in English). For further details, In June 1981 I set up a temperature screen with a reference should be made to Sjors's publication. thermohygrograph in the middle of the Special Area (ea. 280 m a.s.l.). Data were collected during 1981 and 1982, but with several breaks. In some periods Topography and geology maximum and minimum temperatures were also re­ corded from thermometers. The Skattlosberg Stormosse is situated at an eleva­ The aim of these measurements was to achieve a tion of 265 to 285 m a.s.l. The geology of the area picture of the temperature conditions during the was described by Magnusson Lundqvist (1933). years of data collecting and to determine the local & The mire rests on glacio-lacustrine sand and sandy temperature climate. ablation till. The data had to be completed through a series of The SkattlOsberg Stormosse is a large, 450 ha, adjustments and interpolations. First the minimum mire complex (Sjors 1948). It consists of a number (n = 35) and maximum (n =52) temperatures read

\ \ ' ' I I "',, ',-,�:1 \ Dalarna

\ (/ \ \ I ' \ \ ' ' ' - "' ,... �--, .... ' ' ' )( I ; � _, '-' I ...... ',, I I ': \ .....'- I Uppland

:I vastmanland Viirmland I,

/; ...... ---- I / I

-- __ l-/5 \ - ,,_) ,' Fig. 1. Map of Central Sweden showing the lo­ - I ' cation of the Skattlosberg Stormosse.

Acta Phytogeogr. Suec. 74 8 Ingvar Backeus

from the thermometers were compared to minimum ries of data. It is situated ea. 70 m lower than the and maximum temperatures read from the graph on screen on the bog. All hours are given as GMT + the same day. The mean deviation was used to cor­ 1 h. rect the minimum temperature values given by the The difference in the daily means at the two sta­ graph on days when thermometer readings were not tions is small, as are the differences in maximum available. temperatures and temperatures at 1300 and 1900

Then minimum (n = 185) and maximum (n = 178) hours. The temperature at 0700 hours deviates and temperatures from the thermometers (when avail­ is-unlike all other temperatures-higher on the able) or from the graph and temperature values for bog than at SUilldalen. The readings at the meteoro­

0700 (n = 180), 1300 (n = 182) and 1900 (n = 183) logical stations are often made up to 15 minutes be­ hours read from the graph (corrected twice a week fore the full hour (E. Schmacke, in litt.). Tempera­ by means of a mercury thermometer) and daily ture rises rapidly in the mornings and the deviations mean temperatures (calculated according to SMHI can be explained in this way.

1966) (n = 157) were compared with values from the There is also a notable difference in minimum meteorological station at SUilldalen, ea. 30 km SE temperatures between the stations. The minima on of the Skattlosberg Stormosse (59° 57' N, 14 o 57' E; the bog are lower on average, certainly an effect of 210 m a.s.l. ; SMHI, unpubl.). The mean differences its situation in a depression. This effect depends were calculated (Table 1 a) . SUilldalen was chosen largely on the weather and the deviations from the because it is the nearest station with a fairly long se- mean are therefore pronounced (Table 1b). After thus having compared data from the Skatt­ Table la. Mean differences with standard deviations of the losberg Stormosse and SUilldalen, missing data (X) samples (s) and standard errors of the means (S.E.) between tem­ from the bog were calculated from the SUilldalen perature at Stalldalen and at the Skattlosberg Stormosse. is (X values by adding the mean differences between the positive when the Stalldalen value is higher.) stations. In that way a complete table for the bog X S.E. n was constructed which was used for estimating the 0700h 180 -0.5 2.2 0.2 number of frost nights (Table 2), length of growing 1300h 182 0.3 1.3 0.1 1900h 183 0.3 1.5 0.1 season (Table 3a) and the sum of effective tempera­ max 178 0.3 1.3 0. 1 tures (Fig. 4) in the years 1980- 1982. m in 185 1.1 1.8 0.1 Monthly mean temperatures (which differ from daily mean 157 0.2 0.8 0.1 the monthly means of the daily mean temperatures) for the months April to October were then calculat­ Table lb. Distribution of deviations between recorded tempera- ed for the years 1980- 1982. These temperatures tures on the Skattlosberg Stormosse and temperature values from were compared with the corresponding values from the same days using the mean difference between the bog and Stalldalen (Table la). Negative deviations mean that the recorded Stalldalen and were found to be 0.2°C lower. temperature was lower than the calculated. The mean temperatures at Stalldalen can be con­ deviation maximum minimum daily mean sidered normal for the area and elevation. Sj ors (1948) found (preliminarily) that the mean tempera­ -7 0 1 0 -6 1 2 0 ture in Bergslagen (the central Swedish uplands) -5 0 1 0 decreases ea. 0.65 °C per 100 m elevation. The dif­ -4 3 3 0 ference between Stalldalen and the bog is thus some­ -3 4 9 1 -2 10 18 4 what smaller than expected. -1 27 35 38 The means of the monthly mean temperatures at 0 72 55 73 Stalldalen over the years 1967-1982 (the station +1 48 31 35 +2 10 17 4 was not in use before 1967) were calculated from the +3 2 8 2 yearbooks of the Swedish Meteorological and +4 0 4 0 Hydrological Institute for the years 1967-1981 +5 0 2 0 +6 0 0 0 (SMHI 1968-1 982) and from their unpublished +7 0 1 0 lists for 1982 (Fig. 2). When the differences in +8 0 0 monthly means between the stations are added to

Acta Phytogeogr. Suec. 74 Production and growth dy namics of vascular bog plants 9

STALLDALEN -i (210m) 725mm CD 3 30 [16] "0 mm CD � c: ii) 80

20

a

10 b 40

c

20

d

e

-10 AM..JJASO AMJ ..JASO AM..JJASO 1980 1981 1982 Fig. 3. Means of the five highest maximum temperatures per month (a), monthly means of daily maximum tempe­ Fig. 2. Climate diagram in the sense of Waiter & Lieth rature (b), mean monthly temperatures (c), monthly (1960) for SHilldalen, ea. 30 km SE of the Skattlosberg means of daily minimum temperature (d) and means of Stormosse. the five lowest minimum temperatures per month (e) on the Skattlosberg Stormosse in 1980-1982. Only the months April to October are included. From own record­ ings and calculations based on figures from the meteoro­ logical station at SUilldalen. See further in text.

these figures the means of the monthly mean tempe­ mean temperature, on the other hand, the correla­ ratures of the Skattlosberg Stormosse are obtained. tion is much closer . This is to be expected, as this

It was found to be + l5°C in July and approxi­ temperature in itself is the (weighted) mean of three mately -6.5°C in January. or four recordings. The extrapolation made the temperature data The monthly mean temperatures and the monthly somewhat uncertain. Most recordings on the bog means of maximum and minimum temperatures for were made during the April - October period and 1980- 1982 are given in Fig. 3. The same figure also other months were therefore excluded from the shows the monthly mean of the five highest maxi­ calculations. Tables la and 1 b give information on mum temperatures and of the five lowest minimum the variation in the material. The rather poor corre­ temperatures. It was not considered meaningful to lation concerning the minimum temperatures is un­ depict the absolute maxima or minima, since the in­ fortunate, as it makes it difficult to estimate the dividual values are often calculated from the Stall­ number of frost nights for periods when records dalen record. from the bog are not available. As for the daily The estimated number of frost nights is given in

Acta Phytogeogr. Suec. 74 10 Ingvar Backeus

Table 2. Number of frost nights with minimum temperatures be- Table 3a. Start, end and duration in days of the growing season low different temperature limits in I980-I982. Numbers in pa- in 1980-1982. The start and end are defined as the four first and renthesis refer to values based on the records at Stalldalen. last consecutive days with a mean temperature on or above the Growing season defined according to Perttu et al. (I978a) with threshold value (according to Perttu et al. 1978a). threshold value + 5 ac. threshold value oc 0 3 5 6 10 temp. 1980 start 4.IV 12.IV 13.IV 3.V 15.V month limit I980 I98I I982 end 20.X I3.X I2.X 9.X 10.IX April 0 (24) (28) 10( + I6) duration 200 185 I83 I60 119 -I (24) (25) 8( + I2) I98I start 31.111 9.IV 6.V 8.V 10.V -2 (2 I) (22) 7( + 10) end 31.X 14.X IO.X 6.X I.X -3 (16) (2 I) 6( + 10) duration 2I4 189 158 I 52 I45 May 0 (I5) (9) 8 ( +3) I982 start 23 .Ill I5.IV 5.V 12.V 25 .V -I (13) (8) 4 ( +2) end 28.XI 13.XI 2.XI 7.X 2l.IX -2 (10) (7) 4 (+I) duration 25 I 213 I82 I49 120 -3 (8) (5) I (+I) June 0 0 0 II -I 0 0 II -2 0 0 6 Table 3b. Mean start, end and duration of the growing season -3 0 0 4 for the period I967-I982. The start and end are defined graphic­ July No frost ally (according to Langlet I935).

August 0 0 2 0 threshold value 3 5 6 10 -I 0 0 0 ac September 0 (2) 5 (5) I967-I982 start 18.IV 28.IV 2.V 22.V -I (I) 3 (3) end ea. 20.X 8.X 2.X 8.IX -2 0 2 (2) duration ea. 185 163 153 109 -3 0 2 (I) October 0 (19) 6( + 7) (5) -I (16) 5( +6) (3) mer frosts. From June 7 to June 23 frost occurred -2 (I2) 4( + 4) (2) eleven times. On six occasions the frost temperature -3 (I I) 3( + 3) (I) lasted four hours or more. growing 0 (26) (4) I8 season: -I (24) (3) I5 The autumn frosts of 1980 were few and light un­ spring -2 (20) (3) 9 til October. The first one probably occurred on Sep­ -3 (15) (2) 5 tember 1. In 1981 the first light frost occurred on growing 0 (6) 8 (10) August 25. In the unusually mild autumn of 1982 the season: -1 (2) 3 (6) autumn -2 ( 1) 2 (4) first frost probably occurred around September 6. -3 (I) 2 (2) Growing season: The start, end and duration of the growing season or period is given in Table 3. Sev­ eral threshold values are used. in the table, as the Table 2. It should be noted that an individual frost choice is rather arbitrary. There are different ways night deduced from the Stalldalen record is uncer­ of defining start and end of the growing season (cf. tain, especially if the calculated temperature is Tuhkanen 1980: 13). Supan (1887), Hamberg -2°C or higher. Light and more severe frosts have (1922), Langlet (1935) and others defined these therefore been separated in the table. Judging from dates graphically from the curve of the monthly Table la, an extrapolated value of -3°C is likely means. What these authors determined was the to correspond to a real value below zero. mean length of the growing season. Perttu et al. According to Sjors (1948: 23), spring frosts are re­ (1978a) defined the growing season as the time when markably rare in Bergslagen after the middle of the daily mean temperature continuously exceeds May. This holds true for 1981, when the last severe the threshold value. 'Continuously' means four frost occurred around May 10. There was an un­ consecutive days counting from the first day (in usual snowfall on June 12 this year but without spring) to the last (in autumn). This definition can frost. In 1980 there were at least two frost nights in be advocated especially when the start and end of the second half of May. The year 1982 was extreme. the growing season of a single year is to be defined, After some very hot days in early June, there was and it has been used in Table 3a. a long period with an unparalleled number of sum- The mean length of the growing season for the pe-

Acta Phytogeogr. Suec. 74 Production and growth dy namics of vascular bog plants 11

riod 1967- 1982 has been determined graphically (Langlet 1935) from the corrected data from SHill­ dalen. The results are shown in Table 3b. The figures are normal for the area according to Ang­ -1100 strom (1953). Perttu et al . (1978b), using their own method, obtained a mean length of the growing sea­ son at Stalldalen which is two weeks longer. I am aware that the growing season has a restrict­ -1000 ed ecological value (cf. e.g. Hytteborn 1975: 7). It is included here foremost as a means of comparing the temperature conditions of the Skattlosberg Stor­ mosse with other sites from which corresponding -900 data are available. The effective temperature sum was calculated (T) and is here, following i.a. Kolkki (1966) and Sarvas (1967), defined as the cumulative sum of daily mean -800 temperatures above 5°C during the growing sea- + son: n T+5°C = m�l Um- 5) -700 (n = number of days; tm = mean temperature of the m:th day). Results are shown in Fig. 4, following the ap­ � proach of Lindholm (1980). -eoo e ::I (I) Q) a Precipitation Ill a; Precipitation data from the years 1980-1982 are c. available from Stalldalen and from Fredriksberg (18 -500 Q)E 1- km W of the SkattlOsberg Stormosse; 60°08'N, 14°22'E; 300 m a.s.l.; SMHI 1982-83 and un­ publ.). The monthly precipitation at these stations

-400 is given in Table 4. Its percentage of the normal amount of precipitation is also given for Stalldalen (SMHI, unpubl.). No severe drought occurred dur­ ing these three years.

-300 The former precipitation station at the village of Skattlosberg recorded a mean yearly precipitation of 726 mm for the period 1921-1950 (Bergsten 1954). The rain gauge was placed ea. 3 km E of my

-200 sampling areas and at a higher level. The precipita­ tion in this hilly landscape varies considerably from place to place due to elevation and exposure (cf. Sj ors 1948: 25-32). A more elevated area with

-100 Fig. 4. The progression of the temperature sum (T+5oc) in 1980-1982. The beginning of each day is represented with a bar. + indicates frost nights (only between May 15 and Sept. 30). indicates weak frost (not below ( +) -0 -1 °C).

Acta Phytogeogr. Suec. 74 12 lngvar Backeus

Table 4. Precipitation at SUilldalen and Fredriksberg 1980- 1982. percent of normal precipitation. OJo = Jan. Feb. Mar. April May June July Aug. Sept. Oct. Nov. Dec. year

Stalldalen 1980 mm 12 18 23 24 34 114 40 84 92 121 66 57 686 77 210 m a.s.l. OJo 23 47 75 57 163 47 90 121 181 98 95 95 1981 mm 24 32 56 15 67 127 55 42 39 123 115 49 744 OJo 45 85 188 37 152 181 65 45 51 184 171 82 103 1982 mm 32 31 62 61 59 57 65 71 89 62 114 74 778 OJo 61 82 207 145 135 81 77 76 117 92 171 124 107 normal mm 53 38 30 42 44 70 85 93 76 67 67 60 725

Fredriksberg 1980 mm 12 19 31 24 37 171 50 114 61 162 82 70 833 300 m a.s.l. 1981 mm 25 29 74 16 61 195 68 31 52 125 123 48 847 1982 mm 34 35 78 59 74 50 46 88 101 53 118 77 813

some hills reaching about 470 m a.s.l. lies W of the trophic mire vegetation, i.e. he treated these entities as Skattlosberg Stormosse. This area probably re­ classes. Malmer (1968) pointed out that Du Rietz's classi­ ceives a precipitation exceeding 800 mm per year, as fication is very good "from the point of view of habitat ecology'' but ''as to phytosociology it is not so well found­ is suggested on the precipitation map published by ed" (transl.). Sjors (1948 : 26). The station at Skattlosberg was Nevertheless, due to its obvious ecological merits the situated at an elevation of 330 m a.s.l. on a hill which system is now in general use in Sweden and in several reaches 366 m a.s.l. This hill occupies a rather small places elsewhere. It should be considered primarily as an area and should have only a minor effect on the pre­ ecological classification rather than a sociological one and it is symptomatic that Du Rietz's syntaxonomical names cipitation, especially considering that the clouds of­ are rarely used. ten lose some of their moisture content already over An entirely different system has been developed in Cen­ the hills W of the mire. (Precipitation is highest tral and Western Europe, where both ombrotrophic and when winds are southwesterly.) The amount of pre­ minerotrophic vegetation are found in the same classes, Oxycocco-Sphagnetea Scheuchzerio-Caricetea cipitation in the sampling areas (at about 280 m the and nigrae (e.g. Westhoff & den Held 1969, Neuhausl 1972) a.s.l.) can thus be anticipated to be close to or some­ and sometimes also in the Vaccinio-Piceetea. Malmer has what lower than the amount at the former Skattlos­ adopted the Central-European syntax system, at least for berg precipitation station. S Sweden. An index of humidity cannot be very accurately Sjors (1948) pointed out the transitional position of determined from the data available. 'Humidity' de­ wooded bogs between moist dwarf shrub-conifer forest on mineral soil and treeless hummocks. In Finland (fol­ fined as surplus precipitation Tamm 1959) gives (0. lowing Cajander 1913) all wet forests have been classified a value close to or somewhat lower than 400 mm, as mires. In central Europe, on the other hand, it has been which is rather high for central Swedish conditions, common to emphasize the connections with forest types but typical for the area. and, as a consequence, to put wooded bogs and treeless bog hummocks in different classes, the Vaccinio-Piceetea and Oxycocco-Sphagnetea, respectively. Nevertheless, the phytosociological uniting of wooded and woodless Vegetation bog areas has got a footing also in Continental phyto­ sociology through Neuhausl (1972; cf. Malmer 1968). The ombrotrophic bog vegetation of the Skattlosberg Neuhausl's classification was, at least in this respect, ac­ Stormosse was described in detail by Sjors (1948: 107- cepted by Dierl3en (1977). The problem is further discus­ 116). Here I will attempt to put Sjors's descriptions into sed by Dier13en & Dierl3en (1982). the context of later works on bog vegetation. My investigation is only concerned with ombrotrophic Sjors followed the principle of separation between vegetation. The class Ombrosphagnetea was divided by ombrotrophic (bog) and minerotrophic (fen) communi­ Du Rietz (1949) into four regional types with relevance to ties which was first suggested by Du Rietz in 1933 and later Sweden south of the Norrland terrain. He treated them further elaborated on a number of occasions (Du Rietz as subformations (i.e. subclasses sensu Braun-Blanquet). 1949, 1950a-c, 1954). Du Rietz (1954) introduced the The subformations were further divided into alliances names Ombrosphagnetea for the ombrotrophic mire ve­ characterized by the presence or absence of Pinus sy lves­ getation and Sphagno-Drepanocladetea for the minero- tris. The same alliance sometimes occurs in more than one

Acta Phytogeogr. Suec. 74 Production and growth dy namics of vascular bog plants 13 subformation. The following alliances are of interest in Sphagnum rubellum small association and Eriophorum the present area: vaginatum - Cladonia small association and by Fransson (1) The Parvifolion alliance (Du Rietz in Waldheim (1972) under the name Calluno-fuscetum. 1944, Du Rietz 1949; cf. Du Rietz 1950a) of the pine bogs. In the Special Area Calluna vulgaris practically always A variant of this alliance without Ledum palustre charac­ dominates the hummock community. Empetrum nigrum terizes the southwest Swedish pine bogs. dominates locally, mostly on high hummocks. Otherwise (2) The Eufuscion alliance (Du Rietz in Waldheim the latter species usually occurs as a subordinate species 1944, Du Rietz 1949; cf. Du Rietz & Nannfeldt 1925, Du and in places it is entirely lacking. Andromeda polifolia, Rietz 1950c) of the open bog plains in eastern south Swe­ Eriophorum vaginatum and Rubus chamaemorus are pre­ den with Sphagnum fuscum hummocks and S. balticum sent more or less everywhere. Vaccinium uliginosum has and S. cuspidatum in the upper and lower parts of the hol­ an uneven distribution and mainly occurs near the scatter­ lows, respectively. ed pines. V. microcarpum, V. oxycoccos and plants inter­ {3) The Rubello-fuscion alliance {Du Rietz in Wald­ mediate between them occur frequently. Trichophorum heim 1944, Du Rietz 1949; cf. von Post & Sernander 1910, caespitosum is mostly lacking on higher hummocks but Du Rietz 1950b, Backeus 1972) of the open bog plains in is common in lower parts. Betula nana occurs sporadically the central parts of south Sweden, where Sphagnum ru­ and usually in patches. Drosera rotundifo lia is common bellum and, in some areas, S. magellanicum have super­ but absent from the lichen-dominated facies of the com­ seded the species of the former alliance from the lower munity. The bottom layer is usually dominated by Sphag­ parts of the hummocks and the higher parts of the hol­ numfuscum (S. fuscum facies Fransson 1972) but locally lows. by Cladina spp. (Cladonia facies Fransson) or liverworts The Skattlosberg Stormosse, being situated north of (esp. Mylia anomala; liverwort facies Fransson). the border of the north Swedish uplands (the 'Norrland terrain'), does not conform fully to any of these vegeta­ Lawns and carpets: The lawn vegetation of the Skattlos­ tion types. The wooded bog areas belong to the Parvifo­ berg Stormosse was described by Sjors (1948) as the Erio­ lion. Ledum palustre is rare but is abundant in similar ve­ phorum vagina tu m - Scirpus caespitosus Tricho­ getation a short distance to the east. The bog further devi­ ( = phorum caespitosum) - Sphagnum rubellum - balticum - ates from the typical Parvifolion in the presence of the cuspidatum association. The lawn communities are de­ northern species Betula nana. The community was called limited against hummock communities by the absence the Pinus - Vaccinium bog association by Sjors {1948 : Calluna vulgaris 107- 109). Fransson (1972: 35-36) put similar vegeta­ (except a few colonisers) of (cf. Du Rietz 1949). In Malmer's (1962) scheme of comparison with tion into the association Vaccinietum uliginosi. In treeless bog vegetation there are gradual changes other authors Sjors's limit between lawns and hummocks Calluna around the border of the north Swedish uplands as de­ is drawn higher than the limit, indicating that the Trichophorum caespitosum Eriophorum scribed by Sjors (1948), Fransson (1972) and Backeus variant of the vaginatum - Sphagnum rubellum (1984). The Sp hagnum rubellum zone of the hummocks small association would sensu of the Rubella-juscion vanishes towards the north and S. be a lawn community Sjors. The opinions of the exact position of the limit between hummocks and lawns majus occurs together with S. cuspidatum in wet hollows. are thus deviating, but the difference is probably some­ Cetraria delisei also occurs. what exaggerated in Malmer's scheme (Sjors, pers. The treeless bog areas on the SkattlOsberg Stormosse comm.). are intermediate between the Eufuscion and the Rubello­ The bog carpet vegetation constituted Sjors' s ( 1948) fuscion with the addition of the northern features just Scheuchzeria - Rhynchospora alba - Carex limosa - mentioned (cf. Sjors 1948: 111 and Malmer 1962: 148). Sphagnum cuspidatum - Dusenii { majus) association. Sphagnum rubellum here forms only a narrow zone along = Sjors used characters from the field layer when delimiting the border between hummocks and hollows. S. magellani­ the bog carpet communities from the bog lawn communi­ cum occurs both on hummocks and in hollows but is never ties. His differential species occurring in the carpets were dominant. Trichophorum caespitosum is an important Scheuchzeria palustris, Rhynchospora alba, Carex limosa constituent here as in the Rubello-fuscion. (The species and Drosera anglica. does not occur in the Eufuscion.) Du Rietz included all bog hollow vegetation in his asso­ The open bog areas on the SkattlOsberg Stormosse were ciation Cuspidate/urn (Du Rietz 1949). He described a divided by Sjors into one hummock and three hollow progressive upper hollow stage of the Rubello-fuscion as communities, corresponding to the lawns (upper parts), the subass. Magellanico-cuspidatetum (Du Rietz 1949) carpets (lower parts) and mud-bottoms (without Eufuscion Baltico-cuspidatetum sphagna). and of the as the subass. {Du Rietz 1950b). He further described a regressive upper Hummocks: The hummock vegetation was called by Sj ors hollow stage as Tenello-cusp idatetum (Du Rietz 1949, (1948) the Calluna - Cladonia - Sp hagnum fuscum as­ 1950a) in both alliances. The bog carpets of all the al­ sociation. Similar vegetation was described by Du Rietz liances were his subass. Eucuspidatetum (Du Rietz 1949, (1950b,c) as the association Calluneto-fuscetum, by Mal­ 1950c; cf. Du Rietz 1950b). Contrary to Sj ors's delimita­ mer (1962) under the names Eriophorum vaginatum - tions, the composition of the bottom layer determined the

Acta Phytogeogr. Suec. 74 14 Ingvar Backeus

boundaries between Du Rietz's subassociations of the natum - Sphagnum mage/lanicum small association (con­ Cuspidatetum (Du Rietz 1949). sidered progressive) and the Eriophorum vaginatum - Fransson (1 972) described similar lawn vegetation from Sphagnum tenellum small association (considered regres­ SW Varmland under the name Rubello-tenelletum. Car­ sive). Bog carpet vegetation is found in the Drosera ang­ pets and mud-bottoms together constituted another asso­ lica variant of his Eriophorum vaginatum - Sp hagnum ciation which he called the Cuspidatetum. Within this he magellanicum small association and in the Eriophorum distinguished three subassociations, two of which were vaginatum - Sphagnum cuspidatum small association carpet commumtles: Cuspidatetum dusenietosum (both considered progressive).

(Sphagnum dusenii = S. majus) and Cuspidatetum tenel­ In the lawns of the Skattlbsberg Stormosse Eriophorum letosum. The former, as described by Fransson, has a very vaginatum is the most common species and omnipresent. characteristic physiognomy with dense carpets of Sphag­ Vaccinium oxycoccos and Andromeda polifolia are also num cuspidatum and S. majus and a field layer with common, as is Trichophorum caespitosum which, how­ Scheuchzeria palustris, which is often the only field layer ever, is often lacking in the wetter parts of the community. species. Carex limosa occurs in places. Cuspidatetum te­ More or less typical Vaccinium microcarpum occurs to nelletosum is dominated by Rhynchospora alba in the some extent. In the bottom layer Sp hagnum balticum, S. field layer. Andromeda polifolia, Vaccinium oxycoccos cuspidatum, S. majus, S. tenellum and, locally, S. rubel­ and Drosera anglica appear more regularly here than in lum alternate as dominants. the preceding subassociation as well as Eriophorum vagi­ Most carpets of the SkattlOsberg Stormosse belong to natum. In the bottom layer Sphagnum cuspidatum and S. typical Cuspidatetum dusenietosum (Fransson). C. tenel­ tenellum are constants (Fransson, op. cit.). letosum (Fransson) vegetation was not described from Malmer (1962) put bog lawn vegetation into the Tri­ this locality by Sj ors (1948) and Fransson assumes this chophorum caespitosum variant of the Eriophorum vagi- community to be southern. Nevertheless, it does exist on

Table 5. Vegetation analyses from Cuspidatetum dusenietosum and C. tenelletosum (Fransson 1972) on the Skattlosberg Stormosse, 2 just east of the Special Area. Cover degrees ace. to the scale of Hult-Sernander-Du Rietz. Square size 1/4 m • Locations of squares not randomized. Vegetation intermediate between the subassociations was not analysed. Square B 10 is from the edge of a shallow pool in the extension of the lasiocarpa soak and thus deviating.

Cuspidatetum Cuspidatetum dusenietosum tenelletosum A B 2 3 4 5 6 7 8 9 10 1 2 3 4 5 6 7 8 9 10

FIELD LAYER Andromeda polifolia 2 3 2 2 2 2 Calluna vulgaris 1 Pinus sylvestris, seedling Vaccinium oxycoccos Drosera anglica Drosera rotundifolia Rubus chamaemorus Carex limosa Eriophorum vaginatum 1 1 1 2 1 Rhynchospora alba 3 3 2 2 2 2 2 3 Scheuchzeria palustris 2 2 2 2 1 Trichophorum caespitosum --1

BOTTOM LAYER Sphagnum balticum 2 3 2 2 4 3 4 3 2 Sphagnum cuspidatum 5 5 5 3 3 2 2 1 Sphagnum magellanicum Sphagnum majus 3 3 4 4 4 2 5 3 3 2 2 Sphagnum papillosum 1 Sphagnum rubellum 1 2 4 Sphagnum tenellum 2 3 5 5 Drepanocladus fluitans

Cephalozia spp. Gymnocolea inflata + Cladopodiella fluitans 2 2 2 2 5

Cladonia squamosa -1

Acta Phytogeogr. Suec. 74 Production and growth dy namics of vascular bog plants 15

a a 0 a ;:j a 2 Vl ;:j 2 § ...c 0 ..... o.o t: a ...c Cl! 0 .-::: ;:j O.c: ...c 0. o.Cl) .... 0 .... (.) Vl ·- 01) .... Cl) �-2 ..... Cl! r.I.l ;:.. � � hummocks

I I lawns I I I II I Cusp. tenellet. I Cusp. duseniet.

Fig. 5. Distribution of field layer plant species in different habitats in the Special Area on the Skattlosberg Stormosse.

the SkattlOsberg Stormosse in a hollow outside the Special rically eastwards, i.e. from the esker. In two places Area, near its W border. This hollow is to a very minor there·are springs at the edge of the esker. The south­ extent influenced by originally minerogeneous, here very ern springs considerably influence the vegetation in diluted water from the extension of the lasiocarpa soak, the Special Area. Their water flows in a narrow soak which can be seen in the presence of scattered, non­ flowering Carex pauciflora along its borders. Sphagnum (called the 'lasiocarpa soak' by Sj ors) out into the papillosum also occurs to some extent. mire. The soak is widened there into a series of Vegetation analyses from Cuspidatetum tenelletosum flarks and flark pools. Here the influence of the mi­ and from C. dusenietosum are presented in Table 5. C. nerogeneous water is very weak, although quite dis­ tenelletosum combines features from carpets and lawns tinctive. and the limit against the lawn vegetation is sometimes dif­ ficult to define. In places even scattered Calluna is grow­ There is also a more northern soak (the 'Scirpus ing intermingled with typical carpet species (cf. square B9 ( = Trichophorum) soak'; Sj ors, op. cit.) with a in Table 5). For tables on the other bog communities, see weak penetration of minerogeneous water. During Sjors (1948). periods of drought its flow of water ceases almost Mud-bottoms: The vegetation of the mud-bottoms was completely (Sjors 1948). Between the two soaks a called the Scheuchzeria - Rhynchospora alba - Carex li­ bog area occurs with hummocks and hollows of mosa mud-bottom association by Sjors (1948). Malmer lawn type extended in a N-S direction. My non-de­ ( 1962) described similar vegetation in his Eriophorum va­ structive sampling of hummocks and lawns was ginatum - Cladopodiella fluitans small association. Fransson (1972) treated the bog mud-bottom vegetation concentrated to this area. Even here, a sporadic in­ as a subassociation: Cuspidatetum zygogonietosum. The fluence of the minerogeneous water of the lasio­ mud-bottom community is characterized by the absence carpa soak can be deduced from the sparse occur­ of sphagna or other mosses. The same field layer species rence of non-flowering Carex pauciflora (see Sj ors are found as in the carpets. Mud-bottoms are not further 1948: map 14). The sampling area thus is probably discussed in this treatise. In my study I have followed Sjors's classification (with not strictly ombrotrophic in its entirety. It is as­ the addition of Cuspidatetum tenelletosum according to sumed, however, that the very minor influx of mine­ Fransson). In so doing a direct adoption of his vegetation rogeneous water did not influence the results signifi­ map of the Special Area has been possible. cantly. The minerogeneous influence is more ob­ For convenience, the distribution of the vascular plants vious in the carpets and pools along the extended in the bog communities of the Special Area is depicted in Fig. 5. lasiocarpa soak. Sphagnum papillosum is common here and Menyanthes trijoliata occurs sporadically. Trichophorum caespitosum is considerably more luxuriant here than in the purely ombrotrophic Description of the sampling areas areas. These carpets were therefore excluded from Sjors (1948) selected a 'Special Area' in the NW part my investigation. Instead, two carpet hollows just of the mire, 300x400 m large. A small esker runs outside the northern part of the eastern border of along the western border of this area. Most of the the Special Area were chosen for non-destructive Special Area is an ombrotrophic bog sloping excent- sampling, one with Scheuchzeria dominance Cus- ( Acta Phytogeogr. Suec. 74 16 Ingvar Backeus pidatetum dusenietosum Fransson) and the other able changes have occurred within the pools, mud­ with Rhynchospora dominance (C. tenelletosum bottoms, carpets and lawns. The wooded bog areas, Fransson) . on the other hand, have expanded somewhat over In the outer parts of the Scirpus soak the minero­ previously treeless hummock areas. This is evident geneous influence is also quite weak. Its presence is from Sjors's map and from several of his photos. indicated by richer occurrence of Carex pauciflora Destructive sampling in hummocks and lawns and the minerotrophic Sp hagnum fa /lax. Also the was made east of the Special Area, SE of Puukko­

Scirpus soak was excluded from the sampling. lam ( = Brittas hal on the new topographic map). It For a more comprehensive description of the also slopes eastwards. Hummocks and lawn hollows Special Area, see Sjors (1948: 77-104). dominate and are orientated in the contour direc­ The vegetation of the Special Area is evidently tion. In the southern and eastern parts carpets are stable. Sj ors's map of this area was established in also common. 1944-1 945 and my investigations were carried out Destructive sampling in carpets was made close to in 1980-1982. Within this period hardly any detect- the non-destructive sampling.

Acta Phytogeogr. Suec. 74 Phenological development

Phenological data were collected in order to make age yearly length in days of each phase should also it easier to choose suitable times for harvesting (cf. be calculated.) Persson 1975a). As harvesting however had to start The kind of information that can be obtained already during the first summer, the phenological from the spectra is evident from the key to the signs. results were only gradually incorporated into the Only a few comments are needed: harvesting schedule. A shoot was considered to flower when the first The phenological information is, of course, also flower bud had burst. In most species on the bog the of interest as such and is important in the discussion great majority of shoots did not flower at all. This on the dynamics of production in the different spe­ was the case in Andromeda polifolia, Betula nana, cies. Drosera anglica, D. rotundifolia, Eriophorum vagi­ natum, Rubus chamaemorus, Scheuchzeria palust­ ris and Vaccinium spp. It is therefore important to Methods of collecting and presenting note that the flowering and fruiting symbols are used when more than half of the fertile shoots had the phenological data reached the stage in question. The proportion be­ tween flowering and non-flowering shoots will be Data on phenological development were collected discussed in later chapters. In 1982 no fruits of R. through general visual inspections at intervals of chamaemorus and V. myrtillus reached a mature 5-7 days during the summer and less frequently stage, mainly due to severe night frosts, and during the spring and autumn. No exact measure­ Scheuchzeria did not flower at all. ments were attempted. The results are presented in qualitative phenologi­ cal spectra (cf. Dierschke 1972). Each studied prop­ erty is presented separately as I find such a presenta­ Results and discussion tion more easily interpretable than traditional dia­ grams. Similar diagrams were published i.a. by The results are presented in Fig. 6. They will be dis­ Perttula (1949), Falinska (1972) and Persson cussed together with other data in later chapters. (1975a). Only a few points will be taken up here. A property often presented in phenological dia­ Although May was much colder in 1982 than in grams is flower colour. This has been omitted here, 1981 (Fig. 3), the onset of growth seemed to be very since it is not important in a production study. It little later in 1982. After the cold and frosty month could be noted, though, that all conspicuous of June in 1982 the cessation of growth was hardly flowers on bogs in south and central Sweden are later than in 1981. A marked effect of the summer white or mauve. frosts was that Andromeda polifolia, Rubus Separate diagrams for the years 1981 and 1982 are chamaemorus, Vaccinium microcarpum and V. presented because (1) the 1980 material is incom­ oxycoccos formed new vegetative shoots in July to plete, (2) the period is too short for an average to replace damaged shoots. be meaningful and (3) the average of years with early Few species showed any activity before the end of development and other years with late development May. The exceptions were Eriophorum vaginatum, will give the false impression of prolonged phases Scheuchzeria palustris, Betula nana and Trichopho­ with an early and gradual beginning and a late and rum caespitosum. The two first-mentioned species gradual termination. (If averages are used the aver- have a long period of active growth and their leaves

Acta Phy togeogr. Suec. 74 18 Ingvar Backeus

MAY JUNE JULY AUG SEP OCT 1981 I I I I I Andromeda •••••:!:!!j,,,,,,,,,,,, ,,,,,,,,,,z,,,, ,, , , , ,, , ,,, , ,, polifolia 1982 I I r r I 1981 Betula nmP,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, nana r.l\�ll.}w�.t.�a>i11a 1 bilibbilol•?IJ}ii}j)\ j'iii)�:o: tl 1982 � I I I I I 1981 MM M M Call una •O!O!f l";lzzzI I II z z ,,,,,,,,,,,,,,,,,,,,4 vulgaris 1982 I I I I I 1981 Drosera Illllllllll 1111 Ill 11 anglica i!MMMMMMM,,Af#Z 1982 I I I I I 1981 Drosera ••••••••'yAP,,,, ,, z z z z z zz z z ,,,,.., rotundifolia 1982 IMM! I I r I I 1981 Empetrum ...... ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, nigrum 1982 I I I T I 1981 Eriophorum vaginatum 1982 I I I I I 1981 Rhynchospora alba 1982 IWiMIMIMIMIMIMI I I I I I 1981 Rubus ,,,,,,,,,.__ chamaemorus -m, 1982 �.. !!!!!\-·-·-·-·-·-· I I I I I 1981 Scheuchzeria �,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, palustris 1982 I I l I I 1981 Trichophorum caespitosum 1982 I I I I I 1981 Vaccinium micro'carpum 1982 I T I I I 1981 Vaccinium nu,,,,,,,,,,, myrtillus lllllllllllllllllllllllihhiliiiiiil 1982 !f!"!w•••••••• il I I I I I 1981 Vaccinium oxycoccos 1982 I I I I 1981 Vaccinium --��,,,,,,,,,,,,,,,,,� uliginosum 1982 --=---=R''''""''''''""'''''""'''''""''''''"''''''"'''''''""''''''"'''''''""''''''""'''''Iu::: I I I I I 1981 Vaccinium vitis-idaea 1982

2 3 4 5 , , , ...... _ ,,,,"'"" , '-'"'�••••nn ••••••••••••u•uuunn•-·-·-•-•••••••••• ••••••• •••••••••••••l llll l llllllll,/1

Acta Phytogeogr. Suec. 74 Production and growth dy namics of vascular bog plants 19 successively senesce and die throughout the growing had been desirable in evergreen shrubs to include season. In these species it was therefore considered late-season weight increase in the leaves. In some desirable to have an early harvest in May June in cases also wood increment was found to take place I addition to a late harvest in August. very late in the season. Dwarf shrubs were harvested in the middle or Herbs and Rhynchospora alba were sampled in later part of August. When the material had been late July or early August, before senescense became processed it was found that an even later sampling pronounced.

Fig. 6. Phenological spectra of field layer plants in the Special Area on the SkattlOsberg Stormosse. (1) Development of current shoots. (2) Green foliage present. (3) Foliage withering or withered (in autumn). (4) Flowering (at least one flower open in flowering shoots). (5) Fruits/seeds ripening or ripe (up to shedding or overripeness). A species is con­ sidered to be in a certain phase when more than half of the individuals (in 4 and 5: More than half of the fertile individu­ als) are in this phase. The horizontal bars denote initial and final stages (i.e. when 10-50 OJo of the individuals are within the phase in question). Data collecting ended on Sept. 24, 1982.

Acta Phytogeogr. Suec. 74 Production and dynamics of individual species

Methods in hummock and lawn vegetation were made along straight lines, running more or less perpendicular to The yearly aboveground production of each field the contour lines, in the Special Area north of the layer species (except Pin us sy lvestris, Carex limosa extension of the lasiocarpa soak. There were five and C. paucijlora) was determined. Other studies such lines traversing hummocks and lawns and in on certain species, including repeated sampling over addition a few shorter lines in lawns. Points falling the year and direct measurement of length growth on the limit between a hummock and a lawn were will be presented under the species in question. For disregarded. The quadrats of different sizes were the assessment of the yearly aboveground produc­ nested and placed at every second metre. In the larg­ tion (called 'the main sampling' below), the method est squares (200x200 cm) the vegetation was not put forward by T. Traczyk (1967a and b) was used. everywhere homogeneous. The analysed area was in The procedure is similar to the method commonly such cases extended perpendicularly to the baseline used for the estimation of tree and shrub layer pro­ until approximately 4 m2 of hummock or lawn ve­ duction. It implies two steps: the determination of getation were included. The intention was to keep the density of each species and of the average (D) the ends of the lines at fixed points, but in order to current year production of an individual of each avoid errors due to trampling, the lines had to be (G) species. The total production (P) of all (n) species moved slightly before the harvest in 1981. is then Carpet analyses were made in an area immediate­ n ly to the east of the Special Area. Cuspidate turndu­ = p G D senietosum was analysed in a carpet with more or �i= 1 i i less pure stands of Scheuchzeria. Thirteen quadrats Newbould (1967) suggested the same method under of 50x50 cm were analysed. In C. tenelletosum 30 the name the individual plant method. The same or squares were analysed, their size being 10x10 cm for similar methods for estimating biomass and produc­ Rhynchospora alba and 25x25 cm for other species. tion have been used in Poland by Aulak (1970), It cannot be claimed that the carpet analyses give a Plewczynska (1970), Moszynska (1970, 1973), true picture of the average density of the species in H.Traczyk (1971), Puszkar et al. (1972), T. Traczyk these communities. To obtain this an extensive and et al. (1973) and T. H. Traczyk (1977), in Czecho­ time-consuming sampling in the small carpets scat­ & slovakia by Brechtl Kubicek (1968), Kubicek tered over the bog would have been necessary. The & & Brechtl (1970) and Kubicek Jurko (1975), in Ger­ objective has been restricted to give examples of the & many by Eber ( 1971 ), in the Sovietic Far East by An­ production in the two carpet communities. dreev et al. (1972), on Greenland by Lewis Calla­ & Individual weight: Specimens of each species were ghan (1971) and in Canada by Reader Stew art & sampled at regular intervals along straight lines on (1972) and Stewart Reader (1972). A theoretical & hummocks and in lawns east of the Special Area interest in the correlation between biomass and den­ (eastern part of Slaktmossen). The number of col­ sity has also arisen with the establishment of the '3/2 lected specimens varied between species from 25 to power law' (White Harper 1970 and several later & 100 according to degree of variation in plant size. authors). The plants were taken to a refrigerator on the same Density: Plants were counted in quadrats, the size day and moved to a freezer not later than the next of which varied, depending on the species, from day. They were later fractioned, dried at 85°C for + -l 0x10 cm to 200x200 cm (see Table 6). The analyses 48 hours (dwarf shrubs) or 24 hours (others). After

Acta Phytogeogr. Suec. 74 Production and growth dynamics of vascular bog plants 21

Table 6. Quadrat sizes in cm in the density measurements.

1980 1981 1982 hummocks lawns hummocks lawns hummocks lawns

Andromeda polifolia 25 x25 25 x25 25 x25 25 x25 25 x25 25 x25 Betula nana 200 x 200 200 x 200 200 x 200 200 x 200 200 x 200 200 x 200 Calluna vulgaris 10x 10 10x 10 10x 10 10x 10 10x 10 10x 10 Carex pauciflora 10 x 10 10X 10 Drosera rotundifolia 50 X 50 50 X 50 50 x 50 50x 50 50 x 50 50 x 50 Empetrum nigrum 25 X 25 25 x25 25 x25 25 x25 25 x25 25 x25 Eriophorum vaginatum 10x 10 10x 10 10x 10 10x 10 lO x 10 10x 10 Ditto, flowering 200 x 200 200 x 200 200 x 200 200 x 200 200 X 200 200 x 200 Rubus chamaemorus 25 x25 50 x 50 25 x25 50x 50 25 x25 50 x 50 Ditto, with fruits 200 x 200 200 X 200 200 x 200 200 x 200 200 x 200 200 x 200 Trichophorum caespitosum 10x 10 10x 10 20 x 10 20 x 10 20 x 10 20 x 10 Vaccinium microcarpum 10x 10 10x 10 20 x 10 20 x 10 20 x 10 20 x 10 V. oxycoccos 25 x25 25 x25 20 x 10 20 x 10 20 x 10 20 x 10 V. uliginosum 25 x25 25 x25 50 x 50 50 x 50 50x50 50 x 50

Carpets: Cuspidatetum dusenietosum: All species 50 x 50 cm . C. tenelletosum: Rhynchospora alba 10 x 10 cm. All other species 25 X 25.

cooling in an exsiccator the plants were weighed in­ make the sampling easier. They affect biomass de­ dividually with an accuracy of 0. 1 mg. terminations only. The production measurements, In carpets only species not occurring in lawns or which have been considered more essential in this in­ hummocks were sampled. Therefore a full picture vestigation, were not affected. of the field layer production of the carpets has not Throughout this work attached dead is main­ been obtained. tained as a separate category and not included in biomass. 'C' means 'current year', 'C 1' means Wh at is an individual? Plants often differ from ani­ + 'previous year' etc. mals in not havin� distinct individuals (cf. Williams 1964). Seedlings of other species than Eriophorum vaginatum and Drosera rotundifo lia (and probably D. anglica) seem to be rare on bogs. Most of the pro­ Andromeda polifolia pagation must therefore be considered to be vegeta­ Material and methods tive and genetic individuals (genets) are usually im­ possible to distinguish. For practical reasons the At the main sampling current shoots of Andromeda ramets obtained when the plants are cut at ground were counted in 1980 and 1981 but individuals in level or at the first adventitious root are here called 1982. Individuals were harvested on hummocks and 'individuals'. Strictly, what has been studied is not in lawns, cut at the moss surface irt 1981, at the first populations of plants but metapopulations from an adventitious root in 1980 and 1982, but always so unknown number of genets (White 1979). In order that at least the whole current shoot was included. to avoid genetic bias it was considered important to On the collected individuals leaves were frac­ spread the sampling over a rather wide area. tioned into generations (C, C 1, C 2, C 3). + + + A few species form mats. In such cases no indi­ Current and older stems were separated in 1980; in viduals of any kind could be distinguished. Instead, 1981 and 1982 also C + 1 and C + 2 stems were kept current shoots or other units ('plant units' sensu as separate fractions. Attached dead also constitut­ Williams 1964) were considered. It has not been ed a separate fraction. possible-nor desired-to treat all species in the Each fraction was weighed and the number of same way during the sampling and procedures that leaves of each generation and of current shoots were were followed will be presented under each species . counted. The lengths of C (1981-1982 only) and

Some changes in the procedures were made from C + 1 (1982 only) stems were measured. In 1982 at­ year to year in order to improve the methods and tached dead in current shoots was weighed separate-

Acta Phytogeogr. Suec. 74 22 Ingvar Backeus ly. Shoot generations are easily separated by means damaged the shoots and therefore no results are pre­ of the remaining bud scales. sented. The production per individual was calculated as the sum of the following: Results and discussion (a) C stem weight The length growth of current shoots in 1981 and (b) weight increase in C 1 stems: 1982 commenced in the last week of May and ended + in late June (Fig. 6). Lindholm (1982) reports a (C 1 stem weight · length-1 - + longer period, from early May to late June. No bark - C stem weight · length-1) • - C 1 stem length formation takes place in the upper parts of the + shoots during their first summer (Segerstedt 1894). As estimates of shoot length were not available for The limit between the two parts of the shoot were all years, the existing estimates from 1981 and 1982 easily visible because of a sharp change in colour. were used for calculations over all three years. Esti­ Empetrum nigrum shows a similar situation, see mates for the weight increase in three-year-old stems further under that species. and older are not available. Weight increase in current stems continued dur­ (c) weight of C leaves at the end of the season: ing the whole growing season (Fig. 8). No weight in­ crease was found in the C 1 stems in the earlier part + weight of one C 1 leaf · number of C leaves + of the growing season but a remarkable increase in There was a considerable weight increase in C the weight of these stems occurred in August and leaves after harvest. As is shown below, in autumn September, thus indicating that this was the time they attained the same weight as the C 1 leaves. when wood increment took place. + The C 1 leaf weight times the number of C leaves The Andromeda shoots on the bog were usually + therefore gives an estimate of current leaf produc­ short. 75 of the shoots were shorter than 13 or OJo tion during the whole growing season. 17 mm in lawns and on hummocks respectively. The The figures from the 1980 and 1981 countings plants therefore ran the risk of being overgrown by were divided by the average number of current Sp hagnum. It was not uncommon to see Andro­ shoots per individual to obtain the number of indi­ meda shoots with only the upper parts of a couple viduals per unit area. of leaves showing above the moss surface. Some­ Besides the main sampling, 25 individuals from times, however, considerably longer shoots (run­ hummocks were harvested in 1981 twice a month ners) are formed (cf. Warming 1908). They origi­ with the purpose of studying weight changes in nate from a bud on a buried stem and grow oblique­ leaves and stems. This material was transported to ly upwards until they reach the surface, then gradu­ a freezer within three or four hours. Later the plants ally bend to a vertical position and form green were fractioned and then immediately dried at 85°C leaves. The tallest measured runner from a lawn was for 36 hours. The plants were fractioned into C 8 cm and from a hummock 15 cm. Subterranean leaves, C leaves, C stems and C 1 stems. Older runners that grew for more than one year before +I + leaves and stems were too few to give meaningful es­ reaching the surface and forming leaves were very timates. Stems and individual leaves were weighed seldom seen (cf. Keso 1908). With these runners the and measured after drying with an accuracy of 0.01 plant is both propagated vegetatively and escapes mg and 0.1 mm respectively. To avoid errors due to the rise of the bog surface. The shoots of the next chance fluctuations of leaf size in the samples, the summer will again be of normal length. According weight to length ratio was used in the calculations to Keso ( 1908) such shoots will live (in Hame, Fin­ (cf. Flower-Ellis 1975). Leaf weight is linearly re­ land) for 5 to 11 years before they die. Serebryakov lated to length according to Flower-Ellis (1973). (1962) reports (on Sp hagnum bogs in the Moscow In 1982 the length growth in current stems and region) 6 to 8 years. Rosswall et al. (1975) on the leaves was followed by direct measurement with ver­ other hand, report up to 30-year-old shoots in some nier calipers. This experiment was not very success­ microhabitats on the Stordalen mire in north Swe­ ful because of the summer frosts which substantially den. Due to the repeated forming of runners the to-

Acta Phytogeogr. Suec. 74 Production and growth dynamics of vascular bog plants 23

...(/) r- (I) (I) 0.4 Ol 3 ;o.4 :E (I) (I) <0' ::r ce· ... ;?; '0 '0 � � 0.3 s:::: § 2.0.3 ;:;· ... CD CD ::s ::s cc... cc ::r ;. 0.2 cc3 �3 0.2 3 3 3 3 � � 0.1 0.1

J A s 0 Time (month) J J A s 0 Time (month)

Fig. 7. Andromeda polifolia. Changes in mean weight Fig. 8. Andromeda polifo lia. Changes in mean weight (± 1 S.E.) per unit length of C and C 1 leaves (± 1 S.E.) per unit length of C and C 1 stems ( •) + <•> ( •) + <•> on hummocks during 1981. on hummocks during 1981.

tal length of a subterranean stem can be consider­ length in the first half of June but there was a con­ able. Keso (1908) reports up to 214 cm, Metsavainio tinuous increase in dry weight during the whole (193 1) up to 1.5 m. The old stems lie horizontally growing season (Fig. 7). In autumn the C leaves had due to the compaction of the peat. attained the same weight as the C + 1 leaves had at Leaves overwinter. From the material of the re­ the beginning of the season. Similar results were ob­ peated leaf sampling in 1981 (Table 7) it can be seen tained by Flower-Ellis (1975). The C +I leaves lost that there was no significant leaf mortality until July weight notably in June and July. This indicates a dry in the second summer (similar results in Malmer matter allocation to other tissue, presumably cur­ & Nihlgard 1980). Only few leaves lived during a third rent shoots (cf. Johansson 1974). According to Jo­ season. Estimates from the Stordalen mire by hansson translocation to the roots, on the other Flower-Ellis (1980a) based on a considerably larger hand, mainly takes place before the current leaves material gave a mortality of not more than 5 dur­ are formed. The surviving leaves then gradually re­ OJo ing the interval between their appearance and that sumed their former weight. Flower-Ellis (1975) of the next year's C leaves. About 60 % survived found a marked decrease in dry weight in September their second winter at Stordalen. in leaves of the second season (C + 1). My curve The current leaves of 1982 reached their full deviates in this respect. Table 7. Andromeda polifolia. Number of leaves per shoot in Leaves are xeromorphic but the degree of xero­ 1981. Hummocks only. Means of 25 shoots. morphy is variable and usually more accentuated in Average hollows. Simonis (1948) found that pot-cultured survival Generation Period number OJo specimens were more xeromorphic in wet cultures 15.VII-22.X 3.8 100 c than in dry. It is notable that some shoots have 16.VI-15.VII 3.5 90 C+1 broader and much less xeromorphic leaves. This is 15.VII-22.X gradually de- 90 to 50 creasing from also so in leaves attacked by Exobasidium karstenii 3.5 to 1.7 and E. sundstroemii (N annfeldt 1981; the latter spe­ 0.4 10 C+2 16.VI-22.X cies not seen on the bog).

Acta Phytogeogr. Suec. 74 24 Ingvar Backeus

Table 8. Andromeda polifolia. Quantities in individuals ± 1 S.E. Weights in mg. Lengths in mm. 1 Production in mg · yea( • n = 50. Harvest dates: 14 Aug. 1980; 21 Aug. 1981; 25 Aug. 1982. hummocks lawns yearly overall yearly overall year means mean means mean

1.44±0.09 1.72±0.10 1.25± 0.08 1.30±0.06 shoot c 1980 number 1981 1.42 ±0. 12 1.14±0.05 1982 2.31 ±0.26 1.14±0.15 5.25± 0.45 5.97±0.38 4.69±0.32 4.84±0.26 leaf c 1980 number 1981 5.60±0.65 4.67±0.35 1982 7.06±0.83 5.14±0.61 C+1 1980 2.73±0.44 3.06±0.25 1.90±0.28 2.33±0.17 1981 2.44±0.34 1.98±0.29 1982 4.02±0.47 3.10±0.29 C+2 1980 0.71±0.26 0.77±0. 15 0.04±0.03 0.12±0.04 1981 0.66±0.20 0 1982 0.96±0.32 0.32±0.10 C+3 1980 0 0.01±0.01 0 0 1981 0.02±0.02 0 1982 0 0 11.7 ±1.2 stem c 1980 n.d. 23.0 ±2.6 n.d. lengtha 1981 20.5 ±3.5 11.3 ±1.3 1982 25.6 ±3.9 12.2 ±2.0 C+1 1980 n.d. n.d. 1981 n.d. n.d. 1982 20.2 ±2.7 15.3 ±1.6 13.80± 1 .58 11.49 ±1.38 12.40±0.86 leaf c 1980 17 . 14± 1 .34 weight 1981 16.6 ±2.4 13.06±1 .49 1982 21.0 ±2.7 12.61 ± 1 .60 C+ 1 1980 11.9 ±2.2 13.84± 1.52 6.13±1.26 7.77±0.81 1981 10.45 ± 1 .26 5.62± 1.01 1982 19.4 ±3.6 1 1 .43 ± 1 .68 C+2 1980 3.78± 1 .56 4.14±1 .06 0.18±0. 14 0.34±0.10 1981 2.06±0.74 0 1982 6.6 ±2.7 0.83 ±0.25 C+3 1980 0 0.04±0.04 0 0 1981 0. 10±0.10 0 1982 0 0 4.57 ± 0.46 2.50±0.36 2.69±0.24 stem c 1980 4.19±0.64 weight 1981 4.77± 1 .03 2.87±0.44 1982 4.73 ±0.65 2.70±0.45 C+ 1 1980 n.d. 5.69±0.63 n.d. 3.66± 0.40 1981 5.31 ±0.89 2.60±0.48 1982 6.08±0.89 4.70±0.60 C+2 1980 n.d. 6.75± 1 .06 n.d. 2.09±0.37 1981 5.08± 1.34 0.32±0. 15 1982 8.48± 1.62 3.83±0.63 5.40±0.88 6.86±0.69 ;;;;:c+ 1 1980 13.9 ±2.3 19.9 ±2.6 1981 14.4 ±3.0 2.98±0.52 1982 31.5 ±6.8 12.07 ± 1 .52 flowers 1980 0.06 0.05 0 0.09 and fruits 1981 0 0 1982 0.09 0.26 biomass 1980 47 .6 ±5.9 59.6 ±5.5 25.7 ±3.0 30. 1 ±2.0 1981 48.4 ±7.6 24.5 ±2.8 1982 83.3 ± 12.9 39.9 ±3.9 1982 1.32±0.37 0.19±0.08 attached c dead

Acta Phytogeogr. Suec. 74 Production and growth dy namics of vascular bog plants 25

Table 8 (cont.)

hummocks lawns yearly overall yearly overall year means mean means mean

�C+ 1 1980 4.01 ±1.66 5.71 ± 1 .23 1.25±0.54 1.32±0.36 1981 3.32±0.89 0.86±0.35 1982 9.9 ±3.2 1.86±0.85 production 1980 17.99± 1.89 22. 13±1.72 13.99±1 .71 15.15± 1.07 of current 1981 21.4 ±2.7 15.94± 1 .84 shoots 1982 25.8 ±3.5 15.6 ±2.0 estimated weight increase in C leaves after harvest 7.0 2.6

estimated wood increment in C + I stems 2.0 1.2

a Total length of all stems.

Flowering individuals constituted 0-0.2 of lower than the average of 1980-1981 in spite of the OJo the number of individuals on hummocks and severe conditions. 0.1-0.3 % in lawns. The flower and fruit produc­ Lindholm Vasander (1981) found a markedly & tion was therefore negligible. lower production during a year with hard frosts in The biomass per individual was much higher on June. They also found more severe frost damage in hummocks than in lawns (p<0.001; Table 8) but lawns than on hummocks. Their explanation is that there was no significant difference in length growth the plant cover is denser on hummocks. My experi­ or production per shoot. The age structures of hum­ ence from 1982 (not quantified but obvious) is the mocks and lawns were different which can be seen opposite, which can be explained by differences in indirectly from the weight of older stems, this being water level. On my bog much of the lawns were filled much higher on hummocks. The smaller biomass in with water during the frost period whereas their bog lawns must therefore be attributed to a higher mor­ was ditched during the winter before the summer tality (cf. Rosswall et al. (1975) who found consider­ frosts. able differences in mortality between different The plants were cut a little higher in 1981 than in microsites). This, in turn, should be caused by recur­ 1980 and 1982 (see Material and methods). This can rent catastrophes rather than by more severe perma­ have resulted in minor errors only. The small weight nent conditions as production per shoot would of perennating stems in lawns in 1981 may possibly otherwise have been lower in the lawns. Long-last­ have been partly caused by this source of error. The ing high water levels are a likely cause of death in weight of older stems and, as a ·consequence, of the lawns. C shoot number per individual and of biomass, was The low biomass per individual is compensated considerably higher in 1982 than in previous years. by a higher number of individuals (p

The current shoots (leaves and shoot tips) were lawns (40 kg · ha-1 • year-1 on the Laaviosuo). On damaged or killed to a high degree during the severe the subarctic mire at Stordalen (Flower-Ellis 1973) frosts in June 1982. New shoots were subsequently the biomass was much higher (250 kg · ha-1) but often formed from lower buds. The production, production (7 10 kg · ha-1 • year-1) was on the same counted per shoot or per area, was not significantly level as on the Skattlosberg Stormosse. That the

Acta Phytogeogr. Suec. 74 26 Ingvar Backeus

production: biomass ratio is lower in the harsh en­ = where w the weight of older stems (C + 3 and old­ vironment at Stordalen is to be expected. The differ­ er). It cannot be verified that the radial growth had ence to the Laaviosuo is more surprising. ceased when sampling took place (end of July or The percentage of green biomass to total above­ early August) but it is assumed that this growth ground biomass is 68 in lawns and 59 on hummocks takes place in the earlier part of the season as is the (63 at Stordalen). case in other birch species (e.g. Zumer 1969, Hytte­ born 1975). The length growth in current long shoots and the development of the leaves were followed in 1981 and 1982 by measurements with vernier calipers. Betula nana

Material and methods Results and discussion Individuals of Betula nana were counted yearly and The distribution of Betula nana on the hummocks harvested at the first adventitious root. Harvesting is patchy. One such patch probably represents one was made on hummocks only, as the species is rare genetic individual which has been little by little bu­ in ombrotrophic hollows. ried in the peat. Individual shoots can always be fol­ On the collected individuals the leaves were frac­ lowed far down into the peat. tioned into leaves on short shoots and leaves on long Flowering and the commencement of shoot shoots. Current and older stems were separated in growth in Betula nana occurred in the second half 1980. In 1981 and 1982 also C 1 and C 2 stems + + of May (Fig. 6). Shoot growth ceased in the second were kept as separate fractions. Other fractions half of July, somewhat later in 1982 than in 1981. were fruits, flower buds and attached dead. Each The autumn colours appeared in early September. fraction was weighed. In 1981 and 1982 the lengths They are short-day induced (Biebl 1967, Kallio of C, C 1 and C 2 shoots were measured and & + + Makinen 1978). their number noted. Shoot generations were sepa­ About half of the leaves on the long shoots ap­ rated by means of the bud scars. peared before the first of June and the rest develop­ The wood increment in perennating stems was de­ ed one by one until the end of shoot growth at a termined in 1981 and 1982 as the sum of the follow­ mean rate of one per 16 or 17 days. The number of ing: leaves per long shoot usually ranged from four to (1) weight increase in C 1 stems: nine with a mean of 6. 7 (n = 38). + The second leaf was usually larger than the first. weight of C 1 stems - + The subsequent leaves usually were progressively - weight of C stems length of C 1 stems · + I length of C stems smaller although irregularities occurred. (Similar results in Johnson Tieszen 1976.) Hylander (1966) (2) weight increase in C 2 stems: & + reports normal leaf length to be ea. 1 cm. Such large leaves were rare on the bog where normal length was weight of C + 2 stems - 4-8 mm. The severe conditions in 1982 did not - weight of C 1 stems · length of C 2 stems + + I length of C 1 stems cause long shoot leaves to be significantly smaller or + fewer. (3) weight increase in older stems (C 3 and (Ll w) + Most of the leaves, however, are formed early on older): The diameter (D) of the wood and the width short shoots, normally two to four leaves per shoot. (l) of the outermost year-ring were measured on a The ratio between the weight of long shoot leaves disc on each individual taken from the middle of the and short shoot leaves per individual was 0.17 with stem (or in some cases one from the lower parts of no difference between years but with considerable the stem and one from the upper parts). Weight in­ variation between individuals. crease was calculated (Hytteborn 197 5: 3 7) as 35 of the individuals had only one long shoot, 4i(D-l) OJo Llw = ·w 22 had none at all and only 8 had seven or d OJo OJo more (n = 213). Branches were often few. It was

Acta Phytogeogr. Suec. 74 Production and growth dy namics of vascular bog plants 27

1 Table 9. Betula nana. Quantities in individuals ± 1 S.E. Weights in mg. Lengths in mm. Production in mg · year- • n == 50 in 1980; n == 85 in 1981; n == 75 in 1982. Harvest dates: 11 Aug. 1980; 12 Aug. 1981; 13 Aug. 1982. hummocks hummocks yearly overall yearly overall year means mean year means mean number of stems C 1980 2.74±0.49 2.53 stem weight total 1980 1460±300 1230 1981 2.60±0.38 1981 1020±149 1982 2.24± 1 .06 1982 1210±230 C+1 1980 n.d. 2.59 fruits 1980 5.4 ±3.7 4.0 1981 2.61± 0.47 1981 2.6 ±1.1 1982 2.56±0.37 1982 4.0 ± 1.7 C+2 1980 n.d. 1.87 flower buds 1980 4. 1 ±1.7 3.7 1981 1.82±0.28 1981 1.4 ±0.7 1982 1.91±0.22 1982 5.5 ±3.0 stem length a C 1980 n.d. 57.4 biomass 1980 1890±370 1610 1981 66.5 ±9.9 1981 1410±200 1982 48.2 ±7.1 1982 1540±280 C+1 1980 n.d. 64.2 attached dead 1980 137±56 107 1981 63.3 ±11.9 1981 63 ±19 1982 65.1 ±13.0 1982 120±52 C+2 1980 n.d. 46.8 production of current 1981 43 .4 ±6.6 shoots 1980 456±76 407 1982 50.2 ±6.5 1981 413±48 leaf weight: long shoots 1980 57.8 ±10.1 53.4 1982 351 ±52 1981 57.2 ±7.9 sec. wood increment: 1982 45 .1 ±6.0 C+1 1980 n.d. 22.2 short shoots 1980 355±62 318 1981 21.4 ±4.1 1981 325±39 1982 23.0 ±4.9 1982 276±41 C+2 1980 n.d. 20.1 stem weight C 1980 33.9 ±6.8 27.1 1981 17.3 ±3.1 198 1 26.5 ±4.1 1982 22.8 ±3.6 1982 20.9 ±3.5 ;;;;c+3 1980 n.d. 66.5 C+1 1980 n.d. 47.1 1981 80.7 ± 13.0 1981 44.6 ±8.3 1982 52.3 ±7.9 1982 49.5 ± 10.7 C+2 1980 n.d. 49.8 1981 42.6 ±7.1 1982 57.0 ±8.8

a Total length of all stems. common that long shoots changed into short shoots 'spotted sedge - shrub - dwarf shrub - moss tundra' and vice versa which is also known from Betula pu­ on the Taimyr Peninsula. bescens (Zumer 1969). The rate of length growth in current stems is Stem weight was 75 of the total summer above­ shown in Fig. 9 (cf. Fig. 51). Ungerson Scherdin OJo & ground biomass (Table 9). Of this 11 % had been (1962) state that Betula nana has a photosynthetic formed during the current year. Production of new optimum at only + 13°C at Kevo in subarctic Fin­ stems and secondary wood constituted 27 % of the land. The physiological stage when growth started total production, the rest mainly being leaves. to decrease evidently occurred around the tempera­ The ratio between leaves and other aboveground ture sum 400°C. biomass (0.29) was higher than reported from Alas­ The size of the apparent individuals varied con­ kan tundra by Chapin et al. (1980; 0.17), north Swe­ siderably from place to place. At some places dish tundra by Jonasson (1982; 0.04-0.14) and swarms of small individuals were found, at others from dwarf shrub tundra on the Kola Peninsula by a few tall plants (rarely more than 0.5 m high). This Chepurko (1972; 0.13). This is explained by the suc­ variation is probably connected with the growth rate cessive over growth of lower parts by mosses. Vassi­ of the mosses. Because of the considerable variation lj evskaja et al. (1975) obtained the ratio 0.26 on a in size of the individuals it had probably been feas-

Acta Phytogeogr. Suec. 74 28 lngvar Backeus

of J onasson (1982) who estimated more than 4000

kg · ha-1 in a Betula nana - rich My rtillion heath on the north Swedish mountain tundra. From the Tai­ myr tundra 1598 kg · ha·• is reported ('spotty sedge - shrub - dwarf shrub - moss tundra'; Vassiljevskaja et al. 1975) and from the tundra on the Kola Penin­ sula 1029 kg · ha·• (Chepurko 1972). The biomass of Betula nana on the ridges of a polygonal bog on

Taimyr was 279 kg · ha·• (Schamurin et al. 1972). Kosonen (1981) reports 78 kg · ha-• from a pine bog in south Finland and Liedenpohja (1981) 99 kg · ha-• from a south Finnish poor fen. The production was 25 kg · ha·• ·year·•. Of this 22 kg was shoot production. From Eriophorum vagi­ natum tundras in Yukon and Alaska, Wein Bliss & (1974) reported a shoot production of 10-53 kg · ha·• . year·•. Haag (1974) obtained an aboveground

net production of 230 kg · ha·• · year·• on a dwarf shrub tundra in Canada dominated by Vaccinium vitis-idaea, Empetrum hermaphroditum and Betula nana. The production:biomass ratio was 0.30 on the Skattlosberg Stormosse, notably lower than ob­ tained by Liedenpohja (1981) in various kinds of fen vegetation (0.4-0.5) but higher than reported by 200 400 600 Chapin et al. (1980) from Alaskan tundra (0.20; Temperature sum ( °C) wood increment excluded) but similar to values Fig. 9. Betula nana. Mean cumulative length growth of from the Taimyr tundra (0.26; Vassiljevskaja et al. vegetative shoots as a function of the temperature sum in 1975). 1981 and 1982 n=20. c•) (e).

Calluna vulgaris ible to divide the material into size classes. Detected differences in individual weight or num­ The four phases of a Calluna individual as described ber between years were few. Total weight per indi­ by Watt (1955) cannot be found on a bog with active vidual of current stems and the average weight of peat growth. It can be assumed, instead, that for one such stem was lower in 1982 than in 1980 Calluna as well as for several other bog species, (p<0.10 andp<0.05 respectively). The length of cur­ there is a steady state (Forrest 1971), mainly caused rent stems and the wood increment in C + 3 stems by the bog growth and the gradual dying off of old and older were smaller in 1982 than in 1981 (for both buried stems. p<0.10). All other differences were not significant. The complicated growth form of Calluna was elu­ For Betula nana a lower production in 1982 is easily cidated by Malme (1908) and Nordhagen (1937). On explained by the frosts in June as this species, unlike well-developed specimens the terminal long shoots Andromeda and Vaccinium oxycoccos, did not consists of (1) a lower zone with short shoots (often form new shoots in late June or July. The produc­ branched), (2) a middle zone with specialised short tion per shoot was higher than reported from mon­ shoots which carry flowers and (3) an upper zone tane tundra in central Alaska (11-27 mg · year-1; with small end-of-season short shoots. Next year's P.C. Miller 1982). long shoots will usually develop from one or more The biomass per area was small, only 86 kg · ha-1 of the latter short shoots, whose remaining close­ (Table 26). This can be compared with the figures packed leaves show the boundary between the gen-

Acta Phytogeogr. Suec. 74 Production and growth dy namics of vascular bog plants 29

erations. The other short shoots go on forming r-20 (1) :I leaves for a few years and then fall off. cc .... In the extreme ombrotrophic environment it is :r cc often difficult to divide the plants satisfactorily into a � 15 these categories. The flower zone is often absent or :r represented by one or a few flowers only. Sometimes 3 there is little difference between long shoots and 2.. branched short shoots. There are also weak plants that only produce short shoots during several subse­ 10 quent years.

Material and methods

Because of their complicated growth form, indi­ viduals of Calluna vulgaris were not counted. In or­ der to measure density, units consisting of a C + 3 ( 1982 C 2) shoot and all younger shoots that had 200 400 600 800 + Temperature sum ( been formed on it were instead counted. If such °C) Fig. 10. Calluna vulgaris. Mean cumulative length growth units consisted of unbranched short shoots only, of shoots as a function of the temperature sum in 1981 c•) they were disregarded in the counting. Their num­ and 1982 n=20. ber was instead estimated in 1981 from the ratio be­ (e). tween branched and unbranched units on 200 col­ lected individuals. As very few shoots in the main sampling were in 1981. The harvested material was transported to flowering, units with flowers were counted sepa­ a freezer within three or four hours. Leaves of dif­ rately (1980 and 1982). ferent generations were taken from 25 short shoots, Since Calluna only occurs on hummocks the spe­ ten leaves per shoot and generation. These were cies was only harvested in such vegetation. The har­ dried at 85°C for 36 hours. The leaves were too vest was made in two steps. First individuals were small to handle one by one and instead the ten leaves sampled in the field in the usual way. In the labora­ from one shoot were weighed together with an ac­ tory one 'unit' as above was sampled at random curacy of 0.01 mg. This procedure was repeated from each individual. This procedure was chosen twice a month. because most of the units were small and it was diffi­ The length growth of long shoots was followed in cult to perform a correct sampling in the field with­ 1981 and 1982 on 20 selected specimens by measure­ out bias towards big units. ments with vernier calipers. One hundred individuals were cut at the first ad­ ventitious root. The chosen units were divided into the following categories: C vegetative parts; C Results and discussion flowers; C 1; and C 2/C 3 (in 1982 C 2 only). + + + + A separate set of 25 flowering units was also col­ The new shoots of Calluna vulgaris started to grow lected and fractioned as above. in late May and ended their growth in the second Other parts of the collected plants were kept only half of July or early August when flowering started in 1982 for determination of total biomass and sec­ (Fig. 6) . ondary wood increment. The latter was determined The length growth of selected shoots is shown in in the same way as for Betula nana. Fig. 10 plotted against the temperature sum (cf. Fig. In 1980 harvesting was made repeatedly twice a 52). Growth started earlier in 1981 than in 1982 but month in order to study the seasonal changes in bio­ still at a considerably higher temperature sum. May mass (n = 50-100). 1981 was warmer than May 1982 and this indicates Seasonal changes in leaf weight were investigated that the commencement of growth depends on a

Acta Phytogeogr. Suec. 74 30 Ingvar Backeus

tail. The seasonal sequence of the weight of ten cur­ rent and ten one-year-old leaves, as measured for a number of shoots, is depicted in Fig. 11. The leaf weights should be compared within the material

:E(t) only. They do not necessarily represent the average 10' 1.0 weight of Calluna leaves as only shoots with at least � ten living leaves were included in the material. g,.... 0 Fig. 11 shows a considerable rise in weight of cur­ Cb Ill rent leaves in September. A graph published by < (t) t/1 Grace Woolhouse (1973: Fig. 4b) shows a similar & � 0. 5 sequence of events. They, however, measured the total weight of current leaves per plant, and conse­ quently found a gradual rise in weight as long as shoots were still formed. The rapid weight increase in September, when the number of leaves is con­ stant, is evident also from their graph, whereas their ..J A S graph of the previous year's leaves (Grace Wool­ Time (month) & house (1973: Fig. 4c) shows a steady downward Fig. 11. Calluna vulgaris. Changes in mean weight (± 1 S.E.) of ten C and ten C 1 leaves during 1981. slope because of a gradual death of leaves. ( •) + <•) Ten leaves from each of 25 shoots. The one-year-old leaves of my study lost weight in July and again seem to have gained weight in Sep­ tember, thus having a development similar to the combination of calendar date and temperature sum corresponding leaves of Andromeda. Grace & (cf. Lindholm 1980). Woolhouse (1970) have shown that the soluble su­ The slope of the curve was markedly steeper in gar content of Calluna shoots is substantially re­ 1981 which can possibly also be explained by the duced in summer, thus being inversely proportional warmer spring. Grace Woolhouse (1970) have to photosynthesis. & shown that both net and gross photosynthesis are re­ Fig. 12a-b show the weight changes in Calluna duced in Calluna after low temperature pretreat­ plants over the growth period. In current shoots ment. The end of linear growth occurred around the there was naturally an increase in weight as long as 400°C temperature sum in both years, hence the fi­ new shoots and leaves were formed. The weight was nal shoot length was greater in 1981. This means then more or less the same until the second half of that the period of length growth is longer than for August when a drastic rise occurred. This is explain­ several other dwarf shrubs, like Vaccinium myrtil­ ed partly by the weight increase in the leaves but also lus, V. vitis-idaea, V. uliginosum and Andromeda by the radial wood increment which takes place at as seen in Fig. 6. this time of the year according to Grace Wool­ & According to Grace W oolhouse ( 1970) the tern­ house (1973). & perature optimum for net photosynthesis is + 18°C The weight of one-year-old shoots decreased at high light intensities. Optimum at lower light in­ gradually in July and the first half of August. This tensities is lower in such a way that the plant is al­ is explained by the death of leaves, which probably ways near its optimum on a typical summer day commenced in July (This is also suggested from the (Grace Woolhouse, op. cit.). G.R. Miller (1979) graph by Grace Woolhouse 1973: Fig. 4c.), and & & found that mean daily air temperature and mean by the loss of short shoots . According to Forrest daily sunshine taken together accounted for most of (1971: Fig. 6) there seems to be a maximum in the the seasonal variation in growth rate. This will be fall of short shoots in the summer, but the absolute discussed more in a later chapter. amounts are obscured by the percentage scale in his The study of Calluna leaves is complicated by figure. The net weight increase in late August is their small size. The leaves overwinter once or twice again explained by wood increment. but their survival curve has not been followed in de- The curve showing the weight changes in the two-

Acta Phy togeogr. Suec. 74 Production and growth dynamics of vascular bog plants 31

=ECD a ce· c C+1 C+2 and 3 '*:r "C 40 � c � ;:;:

3 30 �

20

10

b

stems and leaves

40

20

s 0 s 0 ,J S 0 ,J ,J A ,J ,J A ,J A Time (month)

Fig. 12. Calluna vulgaris. (a) Changes in mean weight (± 1 S.E.) of C, C + 1 and (C + 2 and 3) shoots during 1980. n All shoots per harvest unit, consisting of one C + 3 shoot with all attached younger shoots, are included. = 50-100. (b) Same as Fig. 12a in a separate sample of flowering units. n = 25 . Note different scales on the y axes.

to three-year-old shoots is similar to the curve for creased between June and July and from October to one-year-old shoots. The weight decrease in July February. In previous years' green shoots Miller should be due to the death of most of the remaining found considerable losses when the new shoots were leaves followed by litterfall of short shoots as the growing, followed by only a small increase in au­ dead leaves are normally not shed but retained on tumn. the plant until the whole branch falls off (cf. Cor­ The yearly sampling (Table 10) was done in the mack Gimingham 1964). latter part of August, when wood increments might & The graphs can be compared with a graph from not have been completed. All wood increments are Scottish material (G.R. Miller 1979: Fig. 2). Miller therefore probably not included in the biomass and found that weight of woody stems increased from production figures.

February to June and from July to October but de- The biomass is estimated to 1825 kg · ha-1 (Table

Acta Phytogeogr. Suec. 74 32 Ingvar Backeus

Table 10. Calluna vulgaris. Quantities in individual 'units' ± 1 report 9200 kg · ha·' and Wallen (1980) 5450-6690 1 S.E. Weights in mg. Production in mg · yea( • Non-flowering kg · ha·', both from south Sweden. Mork (1946) units: n = 53 in 1980; n = 100 in 1981-82. Flowering units: n · = 25 . Harvest dates: 14 Aug. 1980; 21 Aug. 1981; 12 Aug. 1982 found on average 11 000 kg ha·' in a Calluna­ (flower.) and 25 Aug. 1982 (random). N.B. Figures from 1982 dominated mountain forest in Norway. Persson not comparable with 1980 and 198 1 because of different harvest­ ( 1980) reported 2870 kg · ha·' in a relatively open, ing units. 15-20 year-old pine stand dominated by Calluna. hummocks Numerous reports from England and Scotland give year yearly means values of Calluna biomass of up to 23 000 kg · ha·' Units fr om the main sampling: C vegetative parts 1980 1 1.07 ± 1 .60 on (usually) regularly burned heaths and moors but 1981 15.1 ±2.4 with considerable variation depending on growth 1982 8.61 ± 1 .30 phase (Robertson Davies 1965, Bellamy Hol­ & & C flowers 1980 0.31±0. 19 land 1966, Kayll 1966, Chapman 1967, Barclay­ 1981 1.0 ±0.7 Estrup 1970, G.R. Miller Miles 1970, Gimingham 1982 0.19±0.16 & C+ I 1980 15.5 ±2.1 1972, Chapman et al . 1975, G.R. Miller 1979) and 1981 17.9 ±3.3 4500-7900 kg · ha·' on blanket bogs (Allen 1964, 1982 7.17±0.95 Gore Olson 1967, Rawes Welch 1969, Forrest C+2 1982 4.28±0.49 & & 1971, Forrest Smith 1975). It is concluded that C+2 and C+3 1980 15.98± 1 .69 & 1981 17.5 ±2.9 there is a considerable variation in biomass weight attached dead � C + 3 1980 1.30±0.29 of Calluna on different sites where it is the dominant 1981 3.43± 1 .02 species, the values from ombrotrophic bogs in Swe­ �C+2 1982 0.40±0.12 den and Finland being the lowest of them all.

Unbranched units: Shoot production on the Skattlosberg Stormosse c 1981 0.5 ±0.1 was 202-288 kg · ha·' · year·'. Of all available C+l 1981 0.8 ±0. 1 values only those from the Laaviosuo (Vasander C+2 and C+3 1981 1.6 ±0.2 1981) are lower (130-210 kg · ha·' · year-'). Forrest Smith (1975) report 710-2190 kg · ha·' · year·' at Individuals: & number of branched units 1981 8.47 Moor House. Scandinavian figures from mineral number of unbranched units 1981 6.77 soils are 1640 {Tyler et al. 1973), 1770 (Persson biomass 1982 1080±220 1980), 2870-3210 (Wallen 1980) and 2400-2600 attached dead 1982 176±34 (Mork 1946) kg · ha-1 • year·'. wood increments �C + 3 1982 76.2± 16.0 The shoot production:biomass ratio was 0. 15 on the Skattlosberg Stormosse. It is 0.24 on the Laavio­ Flowering units: C vegetative parts 1980 48.8 ±7.9 suo (Vasander 1981) and 0.20-0.41 on unburned 1982 44.3 ±5.9 blanket bogs at Moor House (Forrest Smith & C flowers 1980 7.95± 1 .20 1975). On a south Swedish heath the ratio was 0.18 1982 12.7 ±4.3 (Tyler et al . 1973) and Mark's (1946) figures from C+ 1 1980 40.0 ±6.0 1982 40.3 ±4.5 a Norwegian mountain forest give an average of C+2 and C+3 1980 40.6 ±6.1 0.22. In a central Swedish pine forest values from C+2 1982 20.8 ±2.7 0. 24 to 0. 30 were obtained (Persson 1980). In heaths attached dead 1980 2.9 ± 1.2 on dune sand in south Sweden the ratio was as high 1982 0.61 ±0.37 as 0.30-0.48, evidently because of the very low mean shoot age caused by moving sand (Wallen 26). This is much higher than Vasander's (1981) 1980). On British heaths the ratio drops to less than figures from the bog Laaviosuo (856 and 551 kg · 0.10 with increasing time after burning. The ratio is ha·' on high and low hummocks, respectively), but, likely to be higher on bogs with rapid overgrowth as will be seen later, there is instead much more Em­ by mosses than on other sites. My figure is therefore petrum on the Laaviosuo. Considerably higher lower than expected. values are reported from heaths, where nutrient Estimates of wood increment per area was com­ conditions are more favourable. Tyler et al. (1973) plicated due to incomplete sampling. As mentioned,

Acta Phytogeogr. Suec. 74 Production and growth dy namics of vascular bog plants 33

the result (12.9 kg · ha-' · year-') may be an under­ mosa - Sp hagnum cuspidatum - Dusenii associa­ estimate because of too early sampling. About 5 tion. It did appear in a few squares during the count­ OJo of the measured total production was wood incre­ ing of shoots in Cuspidatetum dusenietosum and C. ment. Data on wood increment in one- and two­ tenelletosum but not in sufficient quantities to make year-old stems are not available. Forrest Smith a meaningful sampling possible. & (1975) report wood production to be 3 % of total On the bog Laaviosuo C. limosa was one of the aboveground production (losses by burial taken major plants in carpets and its aboveground bio­ into account) but with very considerable variation mass (and yearly production) was 127 kg · ha-' (Va­ between sites. sander 1981). Liedenpohja (1981) arrived at 448 kg

Weight of current shoots per 'unit' was signifi­ · ha-' in a poor fen and 298 and 322 kg · ha-1 in two cantly higher in 1981 than in 1980 (p<0.001). Poss­ Scorpidium fens in south Finland. ible significance in weight changes per 'unit' be­ tween 1981 and 1982 was not technically calculable. The number of flowering shoots per area was con­ Carex pauciflora siderably lower in 1981 than in 1980 (p<0.001) and also lower in 1982 than in 1981 (p<0.05). Flowering Carex pauciflora in Sweden is almost exclusively a was generally poor. The flowers constituted 13 % fen plant but it can establish itself in areas where the of the shoot production in 1980, only 2 in 1982. influx of minerogeneous water is extremely small OJo G.R. Miller (1979) found that flowers amounted to and irregular. As mentioned in the description of the 18 % of the total shoot production (range between sampling areas, C. paucifl ora occurs in the area for years: 7-32 %) on a Scottish heath. non-destructive sampling, although sparsely. The It has already been noted that the shoots were specimens are small and without flowers. They oc­ shorter in 1982 than in 1981. It is therefore not sur­ cur mainly in lawns and on low hummocks, and the prising that shoot production per area was also distribution of the species in the Special Area can be lower in 1982. The summer frosts that year caused seen in detail on a map in Sjors (1948: map 14). only very limited damage to Calluna and new shoot The plants were counted in 1981 and their number 6 formation after the frosts was not seen. Lindholm amounted to (0.65 ± 0.17) · 10 per ha in lawns and (1980) and Lindholm Vasander (1981) found se­ (0.39 0.15) · 106 per ha on hummocks. Their bio­ & ± vere damage and an increasing growth of short mass can only slightly contribute to the total bio­ shoots following severe frosts in late spring, mass of the bog and no sampling for biomass or pro­ whereas Braid Tervet (1937) failed to induce frost duction was made. & damage to Calluna plants in a laboratory experi­ Liedenpohja (1981) reports a biomass (and yearly ment. Lindholm Vasander (1981) obtained a pro­ production) amounting to 11 kg · ha-' in a poor fen & duction:biomass ratio of0.17 in 1978, which was the and 29 kg · ha-1 in a Sp hagnum warnstorjii - rich year with frosts in June, but 0.31 during 1977, a fen in south Finland. more normal year. (Part of this difference may also be explained by differences in biomass per area in the samples from the two years, as there is probably not a linear correlation between production and bio­ Drosera anglica mass.) Material and methods

Drosera anglica by definition does not occur in Carex limosa hummock or lawn communities. Its occurrence in the sampled Cuspidatetum dusenietosum was also Carex limosa occurs in carpets and mud-bottoms. negligible and hardly quantifiable. It was collected It is common in flarks but in the studied bog vegeta­ in the C. tenelletosum only. tion it is a sparse constituent. It occurred only in 4 Flowering and non-flowering individuals were out of 21 sample quadrats in Sjors's (1948) analyses treated separately and 25 individuals of each cate­ of his Scheuchzeria - Rhynchospora alba - Carex li- gory were collected. The non-flowering individuals

Acta Phytogeogr. Suec. 74 34 lngvar Backeus were not fractioned but the flowering ones were The weight of non-flowering individuals was fractioned into (1) flowers with stalk and (2) leaves, much smaller in 1982 than in previous years, which current rhizome and vegetative bud. could be an effect of the cool summer. This result Overwintering, seemingly vegetative buds were is, however, obscured by the fact that the flowering also collected in the autumn of 1980. They were all individuals did not show a corresponding decrease from individuals with fruit capsules, because only in weight. such individuals are detectable above the ground at The overwintering buds are formed during the that time of the year. It is possible that some of these latter part of the summer. They had already com­ buds were not purely vegetative but may also have menced their development at the harvest but were contained initials for the next year's inflorescence. not separated as a special category. It is clear from the table that a considerable portion (ea. 25 of OJo ) the leaf biomass is formed already during the previ­ Results and discussion ous year. The morphology and growth form of Drosera ang­ The figure on production ( = biomass) per ha lica are similar to those of D. rotundifolia, to which (Table 26) clearly shows that D. anglica is only a mi­ reference should be made for details. nor contributor to the productivity of the bog. The Flowering was sparse. Only very few individuals figures are of the same magnitude as those given by were seen with flowers within the squares. The Liedenpohja (1981) from fens in south Finland. figures on their number per ha (Table 25) are there­ fore uncertain. The flowering individuals were considerably heavier than those without flowers (p<0.001; Table Drosera rotundifolia 1 1), thus indicating that the species develops flowers only under favourable conditions. Also the vegeta­ Material and methods tive parts of the flowering individuals were heavier Drosera rotundifo lia occurs on hummocks, in lawns than those of the non-flowering ones. and in the sampled Cuspidatetum tenelletosum. In­ dividuals were collected on hummocks and in lawns. As with D. anglica, flowering and non-flowering

Table 11. Drosera anglica. Quantities in individuals ± 1 S.E. individuals were treated separately and 25 individu­ 1 Weights in mg. Production in mg · year- • n = 25. Harvest als of each category were collected. The non­ dates: 11 Aug. 1980; 5 Aug. 1981; 29 July 1982 (non-flower.) and flowering individuals were not fractioned, whereas 12 Aug. 1982 (flower.). the flowering individuals were fractioned into (1) Cusp. tenelletosum flowers with stalk and (2) leaves, current rhizome yearly overall year means mean (=stem) and vegetative bud. It is often difficult to separate the C and C 1 Flo wering individuals: + leaves + C rhizome + generations on the rhizome, and this has caused vegetative bud 1980 26.4 ±2.2 31.2 some uncertainties in the clipping. The first leaves 1981 31.0 ±2.6 of the year die successively during the summer but 1982 36.2 ±2.6 flowers + stalk 1980 12.83±1 .13 13.7 have all been inc:luded in the biomass. 1981 15.7 ±2.6 1982 12.48± 1.44 Results and discussion biomass = production 1980 39.2 ±2_8 44.8 1981 46.6 ±3.6 1982 48.6 ±3.2 The morphology of Drosera rotundifolia was de­ winter buds (September) 1980 1 1 .07± 1 .53 scribed by Nitschke (1860). Its rhizome grows verti­ cally upwards in the earlier part of the growing sea­ Non-flowering indi- son, until it reaches the moss surface. Basal leaves viduals:

biomass = production 1980 23.9 ±2.1 20. 1 are formed along the rhizome. At the surface its 1981 22.81 ± 1.78 growth ceases and a rosette of normal leaves is 1982 13.57± 1.34 formed. In late summer, when the withered plant is

Acta Phytogeogr. Suec. 74 Production and growth dynamics of vascular bog plants 35

' Table 12. Drosera rotundifolia. Quantities in individuals ± I S.E. Weights in mg. Production in mg · year· . n = 25. Harvest dates: 11 Aug. 1980; 31 July 1981; 29 July 1982 (non-flower.) and 12 Aug. 1982 (flower.).

hummocks lawns yearly overall yearly overall year means mean means mean

Flo wering individuals: leaves + C rhizome + winterbud 1980 6.60±0.73 7.84 5.63±0.56 6.53 1981 7.47 ± 1 .05 7.85 ±0.75 1982 4.65±0.46 6.10±0.69 flowers and stalks 1980 6.15±0.89 5.11 4.42±0.53 4.99 1981 4.37±0.56 4.96±0.71 1982 4.80±0.83 5.58±0.71 biomass = production 1980 12.76± 1 .43 11.35 10.05±0.99 11.52 1981 11.85±1.41 12.82± 1 .29 1982 9.45± 1.14 11.68± 1.23 winterbuds (harvested in September) 1980 1.44±0.17 n.d.

Non-flowering individuals: biomass = production 1980 4.81±0.58 5.20 4.41±0.58 5.41 1981 5.05 ±0.70 6.61 ±0.72 1982 5.73±0.82 5.20±0.75

often fully overgrown by mosses, a bud is formed is low in hummock and lawn vegetation (Table 26). terminally which extends the rhizome during the Regrettably no plants were collected in the Cuspida­ next spring up to the new bog surface. Flowers are tetum tenelletosum. If it is assumed that the individ­ formed laterally on a long stalk (rarely two stalks). ual weight in this community is the same as in lawns, Among the analysed communities, rotundijo ­ then one would arrive at a production of 6, 11 and D. lia is by far the most common in the Cuspidatetum 8 kg · ha·1 • year·1 in 1980, 1981 and 1982 respective­ tenelletosum. In 1980 it was more common on hum­ ly. Most of the carpets, however, belong to C. duse­ mocks than in lawns. This difference was less pro­ nietosum and there this species is nearly absent. V a­ nounced in 1981. sander (1981) and Liedenpohja (1981) report 1-5

Most plants do not flower. As can be seen in Table kg · ha·1 • year·1 in various mire communities in 25, flowering was more common in hummock and south Finland. lawn vegetation than in the sampled Cuspidatetum tenelletosum. Flowering was also more sparse in the cool summer of 1982. The only clear variation in plant weight between years is in lawns between 1980 and 1981 (Table 12). Empetrum nigrum In 1981 the plants (both flowering and non-flower­ Material and methods ing) were heavier. The explanation is not clear. There was no difference in plant weight between Being a mat-forming species individuals of Empet­ hummocks and lawns. rum nigrum could not readily be counted. In 1980 Flowering individuals were much heavier than I counted C shoots. This was changed in 1981 in or­ non-flowering individuals. Also the vegetative parts der to avoid to have to count small side shoots. of the flowering individuals were heavier than those · Therefore, in 1981 and 1982 I counted units consist­ of the non-flowering individuals (in lawns in each ing of a C + 1 shoot and all C shoots attached to it. sampling not significantly so, but consistently). No attempts were made to estimate the above­ The weight of the overwintering bud in autumn ground biomass. Without data on belowground corresponds to ea. 10 % of the total summer bio­ biomass such measurements would have had limited mass of the flowering plants. This is smaller than for value as the determining of the limit between above­ anglica. ground and below ground stems is rather arbitrary. D. The yearly production = aboveground biomass) At harvest, current shoots were selected in the ( Acta Phytogeogr. Suec. 74 36 Ingvar Backeus usual way, the stems followed backwards and cut near the ground. At fractioning there were some in­ consistencies between the years. In 1980 one C shoot was chosen at random and older parts disregarded. In 1981 and 1982 a C 1 shoot was chosen at ran­ + dom and older parts again disregarded. This unit was further fractioned into C 1 stem, C 1 living + + leaves, C 1 dead leaves and C shoots . One of the + C shoots, the main shoot in 1981 but randomly chos­ en in 1982, was fractioned into stem, living leaves and dead leaves. All fractions were weighed and stem lengths measured. Flower buds and fruits were also weighed in 1982 when present, which was the case in a few instances only. The weight of leaves older than one year was not determined from this material but from data ob­ tained from the repeated sampling in 1981.

Wood increment was determined in the C + 1 gen­ eration only using length and weight of shoots in the same way as in Andromeda. In 1981, 25 shoots were harvested twice a month in order to study weight changes in leaves and stems. The material was transported to a freezer within 100 300 500 700 900 Temperature sum ( °C) three or four hours. Leaves and stems were separat­ ed into generations and leaves were counted. After Fig. 13. Empetrum nigrum. Mean cumulative length growth as a function of the temperature sum in 1981. fractioning, the plant material was dried at 85°C for 36 hours. After drying, individual stems were weighed, as also were the leaves from each genera­ tion, to an accuracy of 0.01 mg. Stems were Inshade one shoot normally dominates the others measured to 0. mm. and grows into a tall, straggling shoot while the side­ I In 1981 the length growth in current stems was shoots remain short and often die within a few followed on 20 selected shoots and measured with years. This growth form is common where Empet­ vernier calipers. rum is shaded by Calluna and makes it a poor com­ petitor in relation to that species. This kind of growth is even more accentuated in pine bogs, where Results and discussion the leading shoot is normally quite long and sparsely The morphology of Empetrum nigrum has been ex­ branched. tensively discussed by, i.a. Hagerup (1922 in Da­ The shoots develop from winter buds without cell nish, 1946 in English). Some authors, e.g. Hagerup division, as all cells were formed during the previous (1922), have divided the shoots of Empetrum spp. autumn (Bell Tallis 1973). Shoot elongation start­ & into long and short shoots. As pointed out by Gim­ ed on the Skattlosberg Stormosse around the first ingham (1972) and Bell Tallis (1973), the growth of June (Fig. 6) , somewhat later than Calluna start­ & form is greatly dependent on habitat. In open situa­ ed its growth. Hagerup (1922) claims that the tions, as on the top of a bog hummock where the growth comes to a standstill after some time and species is the dominant, all shoots are more or less that, after a short dormancy, cell-division starts of the same length and rather short. The plant then again at the apex to form a summer shoot. Such a "may spread outwards in all directions forming a break in the length growth could not be detected in circular patch or a dense cushion" (Gimingham my investigation. Instead, the growth curve in 1981 1972). was linear up to the middle ofJuly, i.e. at a tempera-

Acta Phytogeogr. Suec. 74 Production and growth dy namics of vascular bog plants 37

(J) (J) �0.4 c 3 < c:· � � CD :r ce· ;:r � "0 �80 � .... 1: :I �. 0.3 c 3 CT CD" • :I � cc ... 0 • :::r �60 •

cc3 � CD 3. §� 0.2 iD Ill < 40 g:

20 0.1 •

•

•

c C+1 C+2 C+3 A s 0 Leaf age Time (month)

Fig. 14. Empetrum nigrum. Changes in mean weight (± 1 Fig. 15. Empetrum nigrum. Survivorship curve for leaves. S.E.) per unit length of C C 1 (.) and C 2 Material collected in 1981. The curve is smoothed by (e), + + (_.) stems during 1981. hand.

ture sum of 550°C (Fig. 13). Neither could such a or less all leaves lived until July in their second sum­ break be traced on graphs of the growth of individ­ mer. About 60 survived their second winter and OJo ual shoots. about 10 their third winter. Very few leaves over­ OJo The end of growth occurred in early August, as wintered a fourth time. is reported from Finland (Lindholm 1980) and Den­ About 27 leaves were produced per shoot in 1981. mark (Hagerup 1922). Bell Tallis (1973) claim that Murray Miller (1982) report 30 leaves in a sedge­ & & growth proceeds untill September or October in moss community on Alaskan tundra but fewer England. (14-23) in other tundra communities. As in Andromeda, bark is formed only on the Current leaves rapidly increased their weight up lower parts of the current shoot, according to Hage­ to late autumn (Fig. 16) in the same way as inA ndro­ rup (1922) on the 'spring shoot' only. I found a meda leaves. Older leaves seemed to have a weak pe­ steady and linear increase in the weight per length riod in July to August, coinciding with the begin­ unit of the current stems up to late autumn (Fig. 14), ning of leaf death and similar to conditions in An­ attributable to this increment in bark and, prob­ dromeda (Fig. 7) and Calluna (Fig. 1 1). It is possible ably, wood. It is not very clear from Fig. 14 when that strong and big leaves survive longer than weak wood increment took place in older stems but it is and small ones. The apparent weight increase of ol­ likely that it was in the autumn as inAndromeda and der leaves in autumn can therefore, partly at least,

Calluna. be an artefact. The weight difference between C + 1 Leaf survival is shown in Fig. 15. Note that the and C 2 leaves may also be explained in that way. + material is from the leading shoots only. Leaves on More far-reaching conclusions could have been side shoots might possibly be more shortlived. More made had the leaf length been measured as well and

Acta Phytogeogr. Suec. 74 38 lngvar Backeus

Table 13. Empetrum nigrum. Quantities in units (consisting of one C + 1 shoot with attached C shoots) ± 1 S.E. Weights in mg. 1 Lengths in mm. Production in mg · year- • n = 50. N.B. In some quantities figures from different years are not comparable to each other (see text). In such cases overall means are not given. Harvest dates: 14 Aug. 1980; 21 Aug. 1981; 31 Aug. 1982.

hummocks yearly overall year means mean

Ratios of shoot numbers: 0.4 CIC+ 1 1980 1.16 1.26 1981 1.09 1982 1.54 C+ 1/C+2a 1980 1.12 1.30 1981 1.61 1982 1.18 0.3

Selected C shoot: stem length 1980 7.60±0.75 1981 12.92±2.2 1982 7.40±0.86 leaf weight 1980 4.90±0.50 0.2 22 1981 7.39±0.97 1982 4.60±0.55 stem weight 1980 1.129±0.128 1981 2.56±0.59 1982 0.954±0.142 0.1 flower buds 1982 0

Other C shoots: total weight 1981 2.37±0.97 1982 5.42± 1 .63

C +I shoot: J J A s 0 Time (month) stem length 1981 15.80±2.1 14.8 1982 13.7±2.2 Fig. 16. Empetrum nigrum. Changes in mean weight (± 1 leaf weight 1981 7.05±0.81 7.62 S.E.) of individual C ), C 1 and C 2 leaves 1982 8.19± 1.21 ( • + <•> + (A) during 1981. Numbers are mean number of living leaves stem weight 1981 4.72±0.77 4.76 per shoot having at least one leaf. 1982 4.79± 1.13 fruits 1982 0.01±0.01 attached dead C 1981 0 0 1982 0 C+ 1 1981 0.99±0.31 1.13 the leaves weighed individually as was done with 1982 1.26±0.37 Andromeda leaves (cf. Flower-Ellis 1973), but this shoot productionb 1981 12.32 11.65 would have been complicated considering the very 1982 10.97 small weights involved. wood increment C + 1 1981 1.59 2.31 1982 3.02 Collection of specimens for determination of the estimated weight in- 1980 2.18 3.43 yearly production took place in late August. The crease per unit in C 1981 4.07 figures (Table 13) are likely to be underestimates as leaves after harvest 1982 4.04 data on wood increment in older stems are not avail­ a Determined from whole 'individuals', see text. able. Weight increase in current leaves after harvest b Per unit. is estimated from Fig. 16. The production per shoot (6- 11 mg · year-') was similar to that reported by P.C. Miller (1982) from montane tundra in central Alaska (4-12 mg · year·').

Acta Phytogeogr. Suec. 74 Production and growth dy namics of vascular bog plants 39

Leaves constituted 81 and 83 of the shoot pro­ from a south Swedish Calluna heath. Available o/o duction in 1980 and 1982 respectively (not calcul­ figures from bogs range from 6 to 710 kg · ha·1 able from the 1981 figures). The leaf share of the (Kjelvik Wielgolaski 1974, Rosswall et al. 1975, & current shoot production was higher than found in Sims Stewart 1981, Vasander 1981). & north Sweden, where Flower-Ellis (1973) recorded The leaf biomass was 40 kg · ha·1 (mean of the 66 % in E. hermaphroditum. My figures show 6th and 7th leaf harvest in 1981) which would mean greater affinity to those of Mork (1946) who re­ ea 40 % of the total aboveground biomass; Mork ported 85 in central Norway (also E. hermaphro­ (1946) obtained 55 %, Kjelvik Wielgolaski (1974) o/o & ditum). 50 % and Flower-Ellis (1973) 31 % in E. herma­ The mean length of the current shoots (leading phroditum. The variation is to be attributed to dif­ and side shoots lumped together) was 7-8 mm in ferences in age structure. 1980 and 1982 and the mean length of the leading shoot was 13 mm in 1981. Due to the variation in growth form mentioned above there was a consider­ able variation in shoot length. Very few shoots were Eriophorum vaginatum taller than 30 mm and the tallest of all measured Material and methods shoots was 66 mm. Values of the same magnitude are reported in E. hermaphroditum from the Kola Vegetative tillers (below called 'individuals') of Peninsula (Kihlman 1890), from north Swedish Eriophorum vaginatum were counted and harvest­ Lapland (Haglund 1905) and from Disko in West ed. About 35 individuals were harvested on hum­ Greenland (Mentz 1909). In Denmark shoots are up mocks and in lawns, respectively, for estimations of to 10 or 20 cm (Mentz 1909, Hagerup 1922). On biomass and yearly production. The belowground ombrotrophic bogs in the Erzgebirge leading shoots parts of the leaves were included down to the rhi­ are reported to be 4-20 cm (Rauh 1938). zome. The individuals collected were fractioned As mentioned, biomass was not determined. into separate leaves. Each leaf was further fraction­ Other authors have found the production of current ed into sheath, living blade and dead blade. Entirely shoots to biomass ratio for Empetrum spp. to vary dead leaves were discarded. The sheath cannot be between 0.11 and 0.27 . Values from 0. 11 to 0.15 distinguished on the youngest leaf of an individual were obtained on a subarctic heath in north Finland and hence was not separated. The weight and length (Kallio Karenlampi 1971) and on a subarctic mire of each fraction was determined. It was also noted & in north Sweden (Flower-Ellis 1973, Rosswall et al. whether the leaf had been formed during the current 1975). Values ranging from 0.18 to 0.22 were ob­ or previous season. (On the latter leaves the upper tained at different sites at Moor House (Forrest dead parts are grey; dead leaves that have not over­ & Smith 1975). On hummocks on the bog Laaviosuo wintered are brown.) Spring growth in C 1 leaves + in south Finland the ratio was 0.19-0.23 (Vasander could not be measured. 1981) and on a south Finnish pine bog 0.26 (Koso­ Flowering individuals were harvested both in nen 1981). In a high-altitude Norwegian forest the May and June (in 1982 in June only). There are ratio was 0.24-0.25 (Mork 1946). usually three or four internodes on a flowering Assuming a ratio of 0.2 on the SkattlOsberg Stor­ shoot, easily distinguished through difference in mosse, the biomass would be approximately 100 kg colour. Each such part of the shoot was fractioned,

· ha-1• In subalpine heaths and forests in north Fin­ weighed and measured. The inflorescence was land, where E. hermaphroditum dominated, bio­ weighed separately.

mass ranged from 800 to 3300 kg · ha-1 (Kallio In 1980 these procedures were repeated twice a & Karenlampi 1971, Karenlampi 1973, Kallio 1975). month during the growing season in order to follow In a high-altitude forest in Norway, Mork (1946) ob­ seasonal changes. Repeated sampling was also un­

tained a biomass of 4700 kg · ha·1• dertaken in 1981 when 25 individuals were collected The biomass of Empetrum spp. depends of twice a month. After the length of each leaf had course on the relative dominance of Empetrum and been measured the lowest 25 mm of green tissue and

other species. Tyler et al. (1973) give 770 kg · ha·1 the upper 25 mm of the sheath were cut and dried

Acta Phytogeogr. Suec. 74 40 Ingvar Backeus

c. Ql <, 3

2

A 0 1981 Time (year and month) Fig. 18. Eriophorum vaginatum. Length growth rate dur­ ing 1980-1981 in seven consecutive leaves (I-VII) from \ the same shoot.

Data from this experiment were also used in certain demographic studies. Their performance might have been somewhat better than the average, as only healthy shoots were selected. The fact that the sheaths of dead leaves decom­

?B.\1ll.l'�U pose very slowly makes it possible to estimate the ap­ proximate age of individual tillers by dividing the to­ tal number of leaves and leaf remnants by the num­ ber of current leaves (cf. Goodman Perkins 1968, & Fetcher Shaver 1983). This was done in autumn Fig. 17. Eriophorum vaginatum. Specimen with a pro­ & longed rhizome. Photo: F. Hellstrom. 1981 . Tussocks were selected in different habitats and the age of each tiller in the tussock estimated. It is probable that all tillers in a tussock belong to the same genet. The results are therefore strictly at­ in the usual way. The purpose was to detect weight tributable to the selected tussocks only. It is poss­ changes in tissues that had obtained their full length. ible, on the other hand, that they originate from The length growth of leaves on 15 selected non­ more than one seed. Sernander (1901) reported that flowering individuals on hummocks was measured he had seen culms of E. vaginatum bend down to from July 1980 to May 1982. As the meristems are the ground, where seedlings developed while still basal and buried in the sheaths of the older leaves, within the inflorescence. a fixed point had to be found. The rising moss sur­ face was considered unsuitable for this purpose. The best method proved to be to make an ink mark Results and discussion on one of the outer dead leaves. These leaves, at least their lower parts, remain several years without Eriophorum tillers grow from short, more or less becoming obviously decomposed. Measurements vertical rhizomes. Daughter tillers are often formed were made to 1 mm with a measuring tape. At the from these rhizomes by branching. These are also end of the experiment the plants were dug up and short and grow vertically upwards. The result is a the absolute lengths of the leaves were measured. dense tussock as described, i.a. by Hopkins Siga- & Acta Phy togeogr. Suec. 74 Production and growth dy namics of vascular bog plants 41

Table I4. Eriophorum vaginatum. Mortality and survival of leaves. 30

Time of appearance July I5 - Aug. I5 - May-June, Observation Aug. 15, 1980 end of I980 1981 period A B A B A B

Winter I980-8I I 92 0 lOO May 1981 0 92 0 100 0 lOO June 1981 2 75 0 100 0 lOO July 1981 7 I7 I 93 0 IOO August 1981 2 0 2 79 0 100 Sept. 1981 0 0 6 36 3 86 Oct. 1981 0 0 4 7 9 45 Winter 1981-82 0 0 1 0 10 0

A = Number of deaths during the period.

B = Surviving leaves at end of period as percentage of the original number.

foos (195 1), but in growing Sp hagnum the tussocks are often rather loose and embedded in the peat and moss. In my study rarely more than 10 shoots per 100 cm2 were encountered. The absolute maximum was 20 tillers per 100 cm2 on hummocks and 26 in lawns. Eriophorum tussocks in Alaska may contain 100-400 tillers per 100 cm2 (data from Fetcher & Shaver 1982). Normally, interactions between plants result in an increased spatial heterogeneity (cf. Greig-Smith 1979). In the case of Eriophorum J A S 0 M J u A S 0 and Sphagnum we have the opposite situation. 1980 1981 Normally the length growth of the rhizome is Fig. 19. Eriophorum vaginatum. Age structure of leaves quite slow but in a rapidly growing moss layer a at different dates during 1981. Column with an asterisk: culm-like structure is sometimes formed below­ leaves that appeared before July 1980. Dates: May 27 (n 38); June 28 (n = 48); July 30 (n 52 Aug. 27 ground at the upper end of the rhizome (Fig. 17). = = ); (n =59) ; Sept. 27 (n 56 Oct. 21 (n 45). This can attain a length of ea. 5 cm whereafter a nor­ = ); = mal rhizome is again formed on top of this 'culm'. The structure is evidently found when the growth rate {Table 14). Leaves appearing in May or June point has come too far from the surface. died in the autumn or the next winter. Most of the It is known (Murray Miller 1982, Fetcher leaves that appeared between July 15 and August 15 & & Shaver 1983, Robertson Woolhouse 1984a) that survived the winter and died during the next sum­ & Eriophorum forms leaves throughout the whole mer. Autumn leaves lived until the next autumn. growing season and that leaves starting growth at Spring leaves thus died at a younger age than other the end of the season resume growth in the next leaves. It also follows that leaf mortality was low in spring. The present study confirms these findings. May and June when the number of living leaves was An example is given in Fig. 18. The growth of a leaf low (similar results in Robertson Woolhouse & could not be measured until it emerged above the 1984a). ground which means that the earliest growth phase The age structure at different times of the year is is not included. It can be seen that a new leaf has shown in Fig. 19. It can be seen that leaves that have its maximum growth at the same time as the preced­ overwintered naturally dominate in the spring. In ing leaf reaches its full length. July the leaves from the two latest months make up There was an obvious seasonal variation in death 58 of the sample and these two months still domi- OJo Acta Phy togeogr. Suec. 74 42 Ingvar Backf!us

Fig. 20. Eriophorum vaginatum. Mean number of living C ( ) to­ • , tal (0) and living 1 c c + c•> leaves per individual (n = 15) fol­ lowed throughout the season in 1981. Hummock plants only.

M J A s Time0 (month)

"'tt a 1.o ��� "8 "'-.'x\o.:�_:'\'":o�1 a. 0\��- g1./l ·\:<0�'\ :�" i \\ :�-�� � 0.1 � o - o �.. ;c· \� :;- x �� �0 -0 ;c "\ • ·�\\ 0.01 f •-9-u-rr- M J J A s 0 0 2 4 6 8 10 12 Time (month) Time (years) Fig. 21. Eriophorum vaginatum. Emergence rate of leaves Fig. 22. Eriophorum vagina turn.Age structure of vegeta­ in 15 individuals expressed as per 100 individuals. Ma­ tive tillers in tussocks from a Sphagnum fu scum hum­ terial from 1980 and 1981 ). mock (D; n 60; 2.50±0. 12 leaves per year), a lichen <•> ( • = hummock (0; 36; 2.86±0.18), a S. papillosum carpet in the Central fen soak ( 48; 2.27±0. 13), aS. balticum •; lawn 108; 2.65±0.10), a pine bog without other field c•; and bottom layer plants but with fungal mycelia 205; c•; 2.53± 0.07) and aS. majus carpet (X; 134; 2.44±0.10).

nate in the late autumn. The age structure of the is constant in May, falls slowly in June and then falls leaves has a decisive importance for the carbon up­ more rapidly down to zero in October. The number take in this species. Robertson Woolhouse of current leaves reaches a maximum in early Sep­ & ( 1984b) have shown that young leaves have a photo­ tember and then decreases again due to deaths. synthetic rate around midsummer that is more than There is an evident seasonal pattern in leaf emerg­ twice that of the overwintering leaves. The photo­ ence (Fig. 21). The course of the 1981 curve may synthesis in old, especially overwintering, leaves is seem rather arbitrary but when the 1980 curve is further reduced as the leaves gradually die from superimposed the similarity is evident. Also Robert­ their tips. son Woolhouse (1984a) found a marked seasonal & The seasonal changes in the number of leaves per variation in leaf emergence. My results are, never­ plant is shown in Fig. 20. The number ofC + 1 leaves theless, founded on too limited a material for far-

Acta Phytogeogr. Suec. 74 Production and growth dy namics of vascular bog plants 43

:\!! �· 50 a a :::r ...

40 40

30 30

20 20

10 10

/� 0 < ---- �------2 - o-Q ------0

b b 30

20

20

10

10

J A S J Time (month)

Fig. 23. Eriophorum vaginatum. Changes (a) in mean weight (± 1 S.E.) in mg per individual of C (living ( and J J A s •) Time (month) dead (0) parts) and 1 leaf blades and (b) in mean c + c•) weight (± 1 S.E.) per individual of living C ( and C 1 Fig. 24. Eriophorum vaginatum. As Fig. 23 but indi­ •) + leaf sheaths during 1980 on hummocks. n = 35. viduals from lawns. 35. c•) n = Acta Phytogeogr. Suec. 74 44 lngvar Backeus reaching conclusions to be drawn. The number of leaves formed per year was 3.2 and 3.1 in lawns and hummocks, respectively, from the material of the main yearly sampling (lower figures,

The apparent increase in weight of C + 1 leaves in the first two samplings is more likely to be due to 200 sampling errors. At this time I was not yet fully fa­ miliar with the species and probably underestimated

C + 1 leaves, thus overestimating C leaves. The curve for dead parts of C leaves does not include completely dead leaves, but such leaves hardly oc­ curred until September (cf. Fig. 20). The seasonal 100 course of the weight of leaf blades per individual (Figs. 23a and 24a) follow a similar course as the number of leaves per shoot (Fig. 20). The repeated sampling of 1981 showed that the weight of leaf blades of a particular generation per unit length is M J A S 0 stable throughout the year. Time of appearance (month) The peak biomass of leaves occurred around Sep­ Fig. 26. Eriophorum vaginatum. Final length in mm of tember 1, as also was the case at Moor House (For­ leaves appearing in different months in 1980 and 1981. rest 1971). In north Alaska, Chapin et al. (1980) Leaves from the same shoot are connected with lines.

Acta Phy togeogr. Suec. 74 Production and growth dynamics of vascular bog plants 45

Table 15. Eriophorum vaginatum. Individuals with leaves cut off by animals in 1980. Actual number and percentage of total num- ber of individuals. n ranges from 23 to 36. G) hummocks lawns as date no no OJo OJo !J June 14 56 5 22 �4 I CD 18 4 13 1 3 July I 7 20 3 9 16 11 32 3 �3 31 3 8 1 3 �2c.. Aug. 13 3 9 1 3 Sept. 3 6 17 0 0 16 3 9 3 Total 51 19 13 5

M J J A s 0 Time (month)

Fig. 27. Eriophorum vaginatum. Rate of length growth in the youngest leaf as a function of time in 1980 and c•) 1981 Measurements started in July 1980. The lowest ( • ). value in June 1981 included a day with snowfall. n = 16.

found the corresponding peak already in the middle to zero in October. Some of the short-term variation of July. may be caused by the variation in leaf emergence­ The considerable weight increase in current leaf the measured leaves being in different stages of sheaths per individual (Figs. 23b and 24b) is not only growth at different measurings. The long, gradual caused by an increased number of sheaths but also decline from July to October is however evident. by an increased weight per unit length which can be The final end of growth in autumn is likely to be in­ seen in Fig. 25. This is evidently important for the fluenced by temperature, but there is no correlation capability of the sheaths in protecting later leaf between the growth rate and the daily increment in generations. temperature sum. Johnson Tieszen (1976) found & The amount of biomass of Eriophorum is also the photosynthetic rate at 5°C to be as much as + somewhat influenced by grazing. Individuals with 75 of the maximum rate which occurred at OJo cut off leaves were often found, more often on hum­ + 10°C. At higher temperatures this rate again de­ mocks than in lawns and more often in June than creased (data from arctic Alaska). It is more likely later, as can be seen in Table 15. that the amount of light is decisive for the growth Leaves from different parts ofthe growing season rate. The fluctuations in June 1981 may be explain­ are not of the same length. As can be seen in Fig. ed by differences in light intensities as long periods 26, leaves that appear early become taller than of cloudy weather occurred during this month. The leaves that appear in July or August. The leaves that low value in the middle of June included one day appear in the autumn (although few) are again tal­ with snowfall, causing the plants to be partly cover­ ler. These latter leaves do not attain full length until ed with snow until late in the afternoon. Robertson next spring. Woolhouse (1984b) have shown that young leaves & There are also seasonal changes in length growth of E. vaginatum (unlike old leaves) respond posi­ per day in the leaves. It was seen in Fig. 18 that a tively to high light intensities. leaf rapidly decreases its growth at about the same The flowering shoots are formed during the sum­ time as the appearance of the next leaf. In Fig. 27 mer before flowering. Such shoots, collected in the the mean length growth per day of the youngest leaf autumn of 1980 had a mean weight of 116 mg. The in the 15 measured shoots is plotted against time. shoots rapidly extended their height in spring and The growth shows considerable fluctuations in May flowered in early May or even earlier. According to and June followed by a rather steady decline down Warenberg (1982) growth starts already while the

Acta Phytogeogr. Suec. 74 46 lngvar Backeus

Table 16a. Eriophorum vaginatum, non-flowering individuals. Quantities in individuals ± 1 S.E. Weights in mg. Lengths in mm. 1 Production in mg · yea{ • n = 35. Harvest dates: 3 Sept. 1980; 5 Sept. 1981: 8 Sept. 1982.

hummocks lawns yearly overall yearly overall year means mean means mean leaf number: c 1980 3.03 ±0.15 3.07±0.08 3.28±0. 15 3.23 ±0.08 1981 2.89±0. 14 3.27±0.13 1982 3.23±0.16 3.17±0.16 C+1 1980 0.49±0.10 0.49±0.06 0.53±0.09 0.41 ±0.05 1981 0.41±0.10 0.19±0.07 1982 0.54±0.09 0.51±0.10 leaf length: C blades, living parts 1980 427 ±25 410.9± 15.2 357±21 344. 1 ± 11.1 1981 370±24 344±17 1982 437±29 331±20 C blades, dead parts 1980 32.1 ±5.5 42.4 ±3.8 50.9 ±7.1 61.2 ±4.6 1981 59.3 ±7.3 81.7 ±8.3 1982 35.2 ±5.9 50.1 ±7.4 C + 1 blades, living parts 1980 50.5 ±12.5 47 .8 ±7.2 28.9 ±7.6 22.4 ±3.6 1981 44.0 ±11.8 10.1 ±3.7 1982 49.3 ± 13.4 28.7 ±6.5 leaf weight: C, living parts" 1980 76.7 ±7.3 75.1 ±3.8 71.6 ±6.0 71.8 ±3.4 1981 69.5 ±6.2 72.0 ±5.6 1982 79.3 ±6.2 71.8 ±6.1 C blades, living parts 1980 49.6 ±4.0 46.7 ±2.2 44.2 ±3.7 42.28± 1.93 1981 41.2 ±3.4 41.6 ±3.1 1982 49.4 ±3.7 41.1 ±3.3 b C blades, dead parts 1980 3.25± 0.67 4.12±0.45 4.58±0.70 6.14±0.70 1981 5.32±0.90 7.60± 1 .00 1982 3.76±0.70 6.20± 1.72 C + 1, living parts" 1980 12.0 ±2.7 11.43 ± 1 .58 10.8 ±2.6 7.45±1.15 1981 8.9 ±2.6 3.19±1.18 1982 13.5 ±3.0 8.47± 1.83 C + 1 blades, living parts 1980 5.88± 1.54 5.32±0.82 4.19±1.21 2.78±0.50 198 1 3.74± 1.12 1.04±0.40 1982 6.36± 1.56 3.16±0.76 biomass 1980 88.7 ±9.0 86.5 ±4.8 82.4 ±8.4 79.3 ±4.0 1981 78.4 ±7.6 75.2 ±6.4 1982 92.8 ±8.4 80.3 ±6.2

• Blades and sheaths.

b Completely dead leaves not included.

plants are still covered with snow. After flowering of dead upper parts of living leaves were higher in the culms grew until early June when they had lawns, both in C and C 1 leaves. The weight and + reached an average height of 295-375 mm and a length of the living parts of the C 1 leaves were + weight of 152-217 mg per individual (Table 16b). lower in lawns. As there were no significant differ­ The number of vegetative shoots (Table 25) is ences in number of leaves, this means that leaf tops, stable over the years and considerably higher in but not leaf bases, died at a younger age in lawns. lawns than on hummocks. The individual biomass on the Skattlosberg Stor­ The biomass per individual of non-flowering mosse was considerably higher than reported by Eriophorum is shown in Table 16a. There were cer­ Chapin et al. ( 1980). They obtained 20 mg per indi­ tain differences between hummocks and lawns, al­ vidual on an Alaskan tundra. Gore (1961) reported though not in total biomass. The weight and length 100 mg at Moor House.

Acta Phytogeogr. Suec. 74 Production and growth dy namics of vascular bog plants 47

Table 16b. Eriophorum vaginatum, flowering individuals. Quantities in individuals ± 1 S.E. Weights in mg. Lengths in mm. Produc-

tion in mg · year"1• n = 25 (1980-1981); n = 30 (1982). Harvest dates: 18 June 1980; 19 May and 17 June 1981; 16 June 1982. hummocks lawns yearly overall yearly overall year means means means means

Lengths: 1st (upper) internode 1980 185.4 ± 15.3 180.8 178.6 ±15.6 168.6 1981:1 113 .0 ±8.4 108.2 ±6.1 1981:2 179.7 ±12.1 185.0 ±7.6 1982 177.2 ±9.2 142.2 ±9.4 2nd internode 1980 143.4 ± 13.2 140.1 106.7 ± 14.9 124.1 1981:1 72.0 ±4.0 74.2 ±4.0 1981:2 121. 6 ± 13.9 135.8 ± 13.4 1982 155.2 ± 10.7 129.7 ± 10.5 3rd internode 1980 23.0 ±3.2 28.0 15.7 ±3.7 20.8 1981:1 27.1 ±3.5 24.8 ±3.9 1981:2 19.3±3.3 18.2±4.0 1982 33.8 ±3.6 21.8 ±2.9 4th internode 1980 9.2 ±3.2 7.1 2.74± 1.02 2.78 1981:1 4.92±1.17 2.16±0.88 1981:2 4.37± 1.63 2.04±0.91 1982 7.27±1 .29 3.45±0.94 Weights: inflorescences 1980 27.9 ±2.2 29. 1 25 .7 ±8.7 25.7 1981:1 26. 14±1.61 23.21 ± 1 .31 1981:2 24. 87±1 .97 24.2 ±2.3 1982 33.3 ±2.4 27. 17±1.65 1st internodea 1980 63 .7 ±2.2 61.9 61.8 ±8.7 51.2 1981:1 40.5 ±3.2 39.3 ±4.0 1981:2 60.2 ±5.2 50.7 ±3.6 1982 61.9 ±5.1 41.1 ±3.9 2nd internode3 1980 71.2 ±6.8 70. 1 51.8 ±4. 1 55.6 1981:1 46.4 ±3.7 47.4 ±4.2 1981:2 63 .3 ±6.5 57.6 ±6.1 1982 75.8 ±5.6 57.4 ±4.8 3rd internode3 1980 41.6 ±6.8 42.5 40.0 ±2.7 38.1 1981:1 42.7 ±3.2 41.3 ±3.5 1981:2 37.3 ±2.9 29.3 ±3.0 1982 43.1 ±2.2 32.98 ± 1 .89 4th internodea 1980 2.63 ±0.65 2.92 1.62±0.56 1.51 1981:1 2.84±0.59 1.18 ±0.47 1981:2 2.27±0.79 1.06±0.46 1982 3.30±0.53 1.72±0.34

a Including leaf, usually more or less dead.

The leaf length per individual was higher on hum­ mocks and 0.12 in lawns (Table 25). Certain dif­ OJo mocks than in lawns (also when dead parts were in­ ferences between years occurred. In 1982 inflor­ cluded). The difference is accentuated if taken as escences were somewhat more common on hum­ length per leaf. This is probably an effect of etiola­ mocks than in previous years, but less common in tion and the weight per unit length is higher in lawns lawns than in previous years. This variation cannot

(0. 120 0.003 mg · mm·1) than on hummocks be explained. Chester Shaver (1982) report 3 OJo ± & (0. 111 ± 0.002 mg · mm-1). The difference is small flowering shoots on an Eriophorum tundra in but significant (p = 0.02). The individual biomass Alaska. is similar in the two habitats. The weight of the flowering shoots was higher on The number of floweringshoots was small, on av­ hummocks in all three years. Changes also occurred erage 0.65 of the total number of shoots on hum- between years but no conclusions should be drawn OJo Acta Phytogeogr. Suec. 74 48 Ingvar Backeus from that as they might be due to differences in phe­ the ground and the total number of plants and buds nological development. within each block was determined. The weight of the The biomass per area (Table 26) was higher in winter buds was determined in 1982. lawns because of the high density. The biomass in Seasonal changes in biomass were studied in 1980 hollows was similar to that reported by Vasander through repeated counting and harvesting twice a

(1981) from the bog Laaviosuo (4 15 kg · ha-1 in month. upper hollows). C.O. Tamm (1954) obtained 260 In 1982 attempts were made to study the length and 279 kg · ha-1 respectively in two samples from growth in stems, leaves and peduncles. Horizontal a lawn community in south Sweden. bars were fixed above selected plants and the dis­ The biomass per area on hummocks was lower tance from the bar to the tip of the stem or leaf was than reported by Vasander (1981) (264-342 kg · measured repeatedly with vernier calipers. The same ha-1) and more similar to Kosonen's (1981) figure method was used successfully for Trichophorum

(135 kg · ha-1) from a south Finnish pine bog. Wa­ caespitosum (cf. Fig. 42) but for Rhynchospora it renberg (1982) reports spring values of 390-460 kg was difficult to obtain reliable results. The tramp­

· ha-1 from fens in high-altitude forest in north­ ling during the work caused the wet ground to quake central Sweden. She found a production in spring and dislocate the plants. From a few plants inter­ amounting to 5.23 kg · ha-1 • day-1• Forrest (1971), pretable records were obtained and one is included Forrest Smith (1975) and Robertson Wool­ here as an example. & & house (1984a) report biomass of Eriophorum rang­ ing from 10 to 750 kg · ha-1 on British blanket bogs Results and discussion at Moor House. Figures on biomass from Alaskan tundra ranges Rhynchospora overwinters by means of under­ between 80 and 300 kg · ha-1 (Chapin et al . 1979, ground vegetative winter buds. Thus this species is Sims Stewart 1981, Miller et al. 1982, Stoner et a 'functional annual' as no other perennial parts ex­ & al. 1982). Figures on production, being of the same ist. I never saw any propagation through seeds. The magnitude, range in Alaska from 107 to 327 kg · winter buds are in principle bulbs (Raunkiaer ha-1• year·1 (Wein Bliss 1973, 1974). A very high 1895-1899). Their leaves are thick and can be sup­ & biomass (ea. 1000 kg · ha-1) is reported from the posed to store nutrients. According to Sernander mouth of the Kolyma River in the Sovietic Far East (1901) they are often seen floating within the com­ (Andreev et al. 1972). munity during floods and therefore deserve to be called diaspores. The growth of a well-developed individual of Rhynchospora is illustrated in Fig. 28. The new Rhynchospora alba plant is first embedded in the basal leaves that form the winter bud. These leaves die early in the summer Material and methods but remain on the plant, usually in the moss layer. Rhynchospora alba does not occur in hummock or Initially a rosette of usually three leaves is formed. lawn communities. It was sampled in the Cuspidate­ In July the different internodia of the culm and also turn tenel/etosum, where it is the dominant species. the peduncle start their length growth more or less Flowering and non-flowering individuals were har­ simultaneously. The leaves die gradually in August vested and counted separately, 25-35 of each. and September. Robust plants retain the green Roots were removed and the plants were separated colour longer than weaker plants but in late Septem­ into (1) living parts of leaves and stem; (2) dead ber all aboveground parts are brown. leaves and dead parts of leaves and stem; and (3) Plants that do not flower have no culms and they spikes and peduncles. wither earlier, most of them in August. The number of belowground winter buds per in­ The seasonal course of biomass per unit area is dividual was estimated in the autumns of 1980 and shown in Fig. 29 and that of biomass per individual 1982. When a plant is dug up these buds readily fall and of density in Fig. 30. Note that standing dead off. Therefore whole blocks of peat were cut from is not included. It can be seen that some plants died

Acta Phy togeogr. Suec. 74 Production and growth dy namics of vascular bog plants 49

Fig. 28. Rhynchospora alba. Length growth in each stem, in­ ternode, leaf and peduncle in one individual as a function of time. Vertical bars represent the length in the scale given. a= leaf senes­ cent; b =leaf dead; c =start of fruit ripening.

a

a b

A Time (month)

Acta Phytogeogr. Suec. 74 50 lngvar Backeus

already in the first part of July but the rate was ac­ celerated in the latter part of August. Growth con­ tinued until the end of July. In August and Septem­ ber the curve in Fig. 30 becomes increasingly skewed by the fact that weak plants died earlier than large plants and thus left the sampled population. It is possible, but not proved, that this is an effect of :::r Q) .!. 200 crowding (cf. Harper 1977) . There was a reduction in density (Table 25) of non-flowering individuals from 1980 to 1982 (p<0 .05). Differences in the number of flowering in­ dividuals were not significant. There was consider­ leaves able between-year variation in the weight of indi­ viduals (Table 17). As can be seen from Figs. 29 and

100 30 a difference in phenological development of a NON - FLOWERING couple of weeks may have considerable influence on the biomass and no conclusions will therefore be made on this point. The number of winter buds per shoot was esti­ mated to 1.20 in 1980 and 1.52 in 1982. This means 6 that 34 · 10 buds were formed per ha in 1980. Only 6 J J s 18.8 · 10 individuals per ha were found in 1981, so Time (month) there had been a mortality of 44 OJo between Septem­ Fig. 29. Rhynchospora alba. The seasonal course of bio­ ber 1980 and end of July 1981. mass and attached dead per unit area in 1980. Dead indi­ The average dry weight of a winter bud was 6.02 viduals not included.

0.4 1 mg (n = 108) in 1982. This is 51 of the av- ± OJo

Fig. 30. Rhynchospora alba. Mean density and mean individ­ ual weight estimated twice a month throughout the season. Material from 1980. The line con­ nects samples in chronological or­ der. Open symbols include at­ tached dead. First sampling in 10 20 Density ( 1 o-s · ha-1 l early June.

Acta Phytogeogr. Suec. 74 Production and growth dy namics of vascular bog plants 51

Table 17. Rhynchospora alba. Quantities in individuals ± S.E. 1 I Rubus chamaemorus Weights in mg. Production in mg · year- • Flowering: n = 35 in 1980; n = 25 in 1981-1982. Non-flowering: n = 35 in 1980 and Material and methods 1982; n = 25 in 1981. Harvest dates: Non-flowering: 31 July 1980; 20 Aug. 1981; 29 July 1982. Flowering: 13 Aug. 1980; 20 Individuals of Rubus chamaemorus were counted. Aug. 1981; 13 Aug. 1982. It was not attempted to count the number of flower­ Cusp. tenelletosum ing individuals in the spring. Fruits are easier to yearly overall year means mean count, provided it is done before they are ripe and

Non-flo wering: cropped by local people. Fruiting individuals were biomass 1980 n.d. 3.30 counted in 1980 and 1981. In 1982 they did not 1981 3.06 ±0.87 occur. 1982 3.54±0.83 Fruiting and non-fruiting individuals were har­ attached dead C 1980 n.d. 2.13 1981 2.39±0.31 vested separately. The former were quite scarce and 1982 1.86±0.41 a statistically satisfactory sampling procedure could production 1980 9.21± 0.65 7.35 not, therefore, be maintained. They were mainly 1981 5.45 taken from hummocks where they were more fre­ 1982 7.40 quent. Non-fruiting individuals were sampled on Flowering: hummocks and in lawns. The plants were cut below­ number of inflorescences 1980 1.26±0.08 1.21 ground in such a way that all current year parts were 1981 1.16±0.08 1982 n.d. included. leaves + stem 1980 9.03±0.99 11.55 Harvested individuals were fractioned into (I) 1981 13.60±1 .24 stem below the lowest leaf stalk; (2) first leaf with 1982 12.01 ± 1 .78 stalk; (3) second leaf (when present) with stalk; (4) inflorescences + peduncles 1980 2.66±0.35 3.44 third leaf (when present) with stalk; (5) fruit (when 1981 3.68±0.44 present) with calyx and pedicel; and (6) dead parts 1982 3.99±0.54 of leaves. biomass 1980 11.69 14.99 1981 17.28 Winter buds were sampled on September 24, 1982 16.00 1982. attached dead C 1980 4.34±0.43 6.25 In 1980 counting and harvesting were repeated 1981 7 .63± 1.31 twice a month for studies on seasonal variation in 1982 6.78±0.72 biomass. production 1980 16.03 21.24 1981 24.91 The growth of stems and leaves was followed in 1982 22.78 1982 on selected individuals and measured with ver­ nier calipers.

erage dry weight of an individual (Table 17; counted over the three years), but this does not mean that Results and discussion half of the biomass of the plant measured at the end of July is already formed within the bud as parts of The morphology of Rubus was studied in detail by it are basal leaves that die early. lessen (1913) and Resvoll (1929). The species forms The mean standing crop was 254 kg · ha-1• As far subterranean runners that can grow horizontally in as I know there are only two other estimates of bio­ the soil for at least two metres (Resvoll, op. cit. and mass of R. alba in the literature, both given by Lie­ Metsavainio 1931) before turning upwards towards denpohja (1981) from south Finnish fens. She re­ the surface. When this happens a winter bud is ports 13 kg · ha-1 in a mesotrophic fen dominated formed at the surface (lessen, op. cit. and Resvoll, by Carex limosa, Sp hagnum angustijo lium and S. op. cit.) or, more often, a few centimetres below the obtusum and 3 kg · ha-1 in a poor fen dominated by surface. In the next spring this bud will develop an Carex lasiocarpa, C. rostrata, Sp hagnum angustifo­ aerial shoot, which will then die in the autumn while lium and S. magellanicum. No figures are available a new winter bud is formed sympodially from the from areas dominated by R. alba. rhizome.

Acta Phytogeogr. Suec. 74 52 lngvar Backeus

shown that the growth of Rubus is greatly de­ pendent on the temperature and light intensity. Ac­ cording to Zalenskij et al. (1972), maximum photosynthetic intensity is found at a temperature

of only + 8°C on Taimyr. As can be seen in Figs. 32 and 33, new shoots ap­ peared also in the latter part of June., About 30 o/o of the maximum number of individuals appeared during that period in 1980. Very few of these shoots flowered. The seasonal course of biomass per area is shown in Figs. 34 and 35. The attached dead fraction in­ cludes dead parts of leaves (i.e. brown leaves with­ out turgor). It is obvious from Figs. 32-35 that the peak biomass occurred in July and that the main a b growth occurred in June (cf. Wein Bliss 1974). & I Maximum density is simultaneous with maximum a b c individual biomass in July. Death occurred mainly I in the second half of August and early September. I There was no tendency for larger individuals to sur­ vive longer than smaller ones, which indicates that crowding was not involved in the mortality and that it is only a matter of season. The senescence of Ru­ bus leaves proceeded slowly through the latter part of the summer, as can be seen from the increasing M J J I attached dead fraction in Figs. 34 and 35. It is rea­ M J J sonable to assume this to be an effect of day length. Time (month) Saeb0 (1968) and Flower-Ellis (1980b) are of the opinion that there is no period of leaf maturity in this species but a prolonged senescence that starts immediately after the leaves have been formed, and this opinion is supported by my Figs. 32-35. The density was much higher on hummocks than in lawns (Table 25). In carpets this species is uncom­ Fig. 31. Rubus chamaemorus. Length growth in stem, leaf mon. stalks, leaves and pedicel in two individuals in 1982. Verti­ Biomass per individual (Table 18) was higher on cal bars represent the length in the scale given. a= leaf hummocks than in lawns (not significant in 1980; folded; b =leaf partly unfolded; c =leaf unfolded. p

Acta Phytogeogr. Suec. 74 Production and growth dy namics of vascular bog plants 53

Fig. 32. Rubus chamaemorus. :;­ Mean density and mean individ­ �150 ual weight estimated twice a 0: r:: month throughout the season on e!.. hummocks. Material from 1980. � The line connects samples in chro- �· no logical order. Open symbols in- ;:r '3 elude attached dead. First samp- re_ ling in early June.

100

8 0 50

0.1 0.3 0.5 0.7 0.9 Density ( 1 o-6 • ha-1)

50

25

Fig. 33. Rubus chamaemorus. As Fig. 32 but samples from lawns. 0.1 0.2 Density ( 1 Q-6 · ha-1) 54 lngvar Backeus

Fig. 34. Rubus chamaemorus. :E�. 110 The seasonal course of biomass cc ....:r and attached dead per unit area '0 on hummocks in 1980. Dead indi­ � viduals not included. I» (;j I» 100 � cc

80

60

40

20

M J J A s Time (month)

Fig. 35. Rubus chamaemorus. The seasonal course of biomass and attached dead per unit area in lawns in 1980. Dead individuals not included. later leaves

5

stems M A s Time (month)

Acta Phytogeogr. Suec. 74 Production and growth dy namics of vascular bog plants 55

' Table 18. Rubus chamaemorus. Quantities in individuals ± 1 S.E. Weights in mg. Production in mg · year" . n = 30 (lawns 1980-81); n = 35 (hummocks 1981-82, lawns 1982); n = 55 (hummocks 1980). Harvest dates: 31 July 1980; 31 July 1981; 13 Aug. 1982.

hummocks lawns yearly overall yearly overall year means mean means mean

Main sampling: leaf number 1980 1.25± 0.07 1.34 1.33±0.09 1.28 1981 1.41 ±0.09 1.23±0.08 1982 1.37±0.12 1.27±0.08 leaf weight: first leaf 1980 68.8 ±6.4 75.8 56.6 ±7.8 52.7 1981 99.4 ±12.0 64.0 ±8.3 1982 59.2 ±6.1 37.6 ±5.5 total 1980 85.3 ±9.6 104.0 67.5 ±9.7 65.2 1981 137.4 ±19.2 80.7 ±11.1 1982 89.3 ±13 .4 47.5 ±7.4 stem weight 1980 8.57± 1.37 10.6 4.92±1 .26 4.98 1981 14.4 ±2.5 5.46±1 .05 1982 8.8 ±2.0 4.57±0.83 biomass 1980 93.9 ±10.7 115 72.5 ±10.8 70.2 1981 152±21 86.2 ±11.3 1982 98.0 ±15.1 52.0 ±8.0 attached dead: first leaf 1980 3.1 ±1.1 4.1 5.2 ±2.3 3.5 1981 5.4 ±2.5 2.1 ±1.0 1982 3.8 ± 1.3 3.3 ± 1.2 total 1980 3.1 ±1.1 4.5 5.2 ±2.3 3.9 1981 5.5 ±2.5 2.3 ±1.0 1982 4.8 ±1.4 4.1 ±1.3

Fruiting individuals: leaf number 1980 2.15±0.12 1.96 1981 1.77±0.15 leaves + stem 1980 256±26 207 1981 158.4±16.2 fruits + calyx + pedicel 1980 183.1 ± 14.6 173.7 1981 164.2±13.1 biomass 1980 439±29 381 1981 323±22 attached dead 1980 n.d. 1981 8.56±4.2

The effect of the summer frosts in 1982 is not stead of the failed first one. These later shoots how­ quite clear from the figures in Table 18. On hum­ ever, at least on the Skattlosberg Stormosse, did not mocks the production per individual remained on flower. the same level as in 1980. In lawns the production The allocation to reproductive organs (incl. calyx was smaller than the previous years but significantly and pedicel) was 160 and 180 mg in 1980 and 1981 so only when compared with 1981 {p<0.05). Many respectively (Table 18), i.e. 42 and 51 ofthe bio­ OJo shoots died in June that year and these shoots were mass of fruiting individuals. Other fruit weights for not included in the density estimations. Apparently, comparison are 140-200 mg on an ombrotrophic rather many new shoots were formed in late June bog in SW Norway (Saeb0 1968) and 123-130 mg and in July that year although this was not quanti­ on blanket bogs at Moor House (Marks Taylor & fied. These shoots were usually easy to distinguish 1972). through their lighter colour. Such late shoot growth The production on hummocks (Table 26) was was also reported in the newspapers that summer, similar to Vasander's (1981) results from the bog raising expectations of a late cloudberry harvest in- Laaviosuo (82-98 kg · ha-1 • year-1). The produc-

Acta Phytogeogr. Suec. 74 56 Ingvar Backeus tion in lawns was also similar to the Laaviosuo (19 lected, as they were too few to allow a proper samp­ kg · ha-1 • year-1). Lohi (1974) reports 24 kg · ha-1 • ling. year·1 on a Sphagnum bog and 26 kg · ha-1 • year·1 On the collected individuals each current leaf was on a pine bog in NE Finland and Kosonen ( 1981) 19 weighed and measured separately, and it was noted kg · ha-1 • year·1 on a pine bog in S Finland. Up to whether it was healthy, senescent or dead.

22 kg · ha-1 • year·1 is reported by Forrest Smith Length growth of leaves was measured in 1981 & (1975) from blanket bogs at Moor House. High and 1982. The same method as for Eriophorum va­ values (105 and 180 kg · ha-1 • year-1) are reported ginatum was applied. The dead leaves of Scheuchze­ from Stordalen in N Sweden (Sonesson Bergman ria wither rapidly, which made it sometimes diffi­ & 1972, Rosswall et al. 1975). A yearly production of cult to obtain a reliable fixpoint. The periodically up to 38 kg · ha-1 is reported from Alaskan tussock high water table also made measurements compli­ tundra (Wein Bliss 1973, 1974). cated. The length measurements were made to the & On an area basis the allocation to fruits was very nearest millimetre but an inaccuracy of about ± 2 small as very few individuals were fruiting (Table mm had to be accepted because of the technical dif­ 25). The number of cloudberry fruits is known to ficulties. Only length differences in time were mea­ fluctuate very much from year to year (cf. data in sured, not absolute lengths. Lid et al. 1961, 0stgard 1964, Stavset 1981, Kardell Carlsson 1982). The years 1980 and 1981 are & Results and discussion known as poor cloud berry years and 1982 was even worse. On the investigated site, fruiting is poor also Scheuchzeria is a rhizomatous perennial with hori­ in good years such as 1979 (cf. Sjors 1948). On good zontal rhizomes a few centimetres beneath the moss cloudberry mires the yield averages 20 or 30 kg · surface (Raunkiaer 1895-1899, Metsavainio 1931). ha-1 (fresh weight). Cloudberry yields are reported The end of a rhizome bends upwards and forms by 0stgard (1964), Makinen Oikarinen (1974), shorter nodes with normal leaves. The leaves are & Veijalainen (1976), Huttunen (1978), Stavset (1981) nearly vertical. Such shoots live for several years. In and Kardell Carlsson (1982). certain wet carpets Scheuchzeria is the only field & The average weight of winter buds (including the layer plant. This seems especially to be the case in short , sympodial rhizome branchlet, formed simul­ such Sp hagnum majus and S. cuspidatum hollows taneously, on which it is borne) was 2.82 ± 0.36 mg where the bog surface does not move vertically with (n = 22) in 1982 on hummocks and 2.06 ± 0.37 mg the water table. During times with high water the

(n = 21) in lawns, which is 3-4 of the yearly pro­ leaves are therefore partly inundated. OJo duction of an individual. According to Saeb0 ( 1968) Except for the non-tussocky appearance the they are fully developed in the early part of Septem­ growth form of the aboveground shoots of ber. Scheuchzeria is similar to that of Eriophorum vagi­ natum but the growth rhythm is different. An ex­ ample is given in Fig. 36. Usually four or five leaves are formed in one season. It can be seen that length Scheuchzeria palustris growth of consecutive leaves is more overlapping in this species than in E. vaginatum (Fig. 18). Material and methods The periodicity in leaf emergence was more ob­ Scheuchzeria is mainly a carpet (and mudbottom) vious in Scheuchzeria (Fig. 3 7) than in Eriophorum. species. Individuals were counted in the Cuspidate­ The investigated five-leaved shoots in 1982 had very turn dusenietosum and C. tenelletosum but harvest­ clearly defined emergence periods. The first three ed only in the C. dusenietosum from where 25 non­ leaves developed in May and early June this year, flowering individuals were collected in August. At the fourth around the first of July and the fifth the harvest in 1980 it was discovered that the oldest around the first of August. The four-leaved shoots current year production was already withered. In had less clearly defined periods. 1981 and 1982 an additional harvest was therefore The survival of leaves can be seen in Table 19. The made in June. Flowering individuals were not col- first leaf died in July or early August. The second

Acta Phytogeogr. Suec. 74 Production and growth dy namics of vascular bog plants 57

Table 19. Scheuchzeria palustris. Mortality and survival of leaves.

third/third- youngest observation oldest leaf second leaf fourth leaf" leaf date A B A B A B A B

July 6 0 100 0 100 15 4 67 0 100 0 100 25 7 42 0 100 0 100 August 4 11 8 0 100 0 100 17 12 0 3 75 0 100 0 100 31 12 0 5 58 0 100 0 100

J A Sept. 16 12 0 12 0 14 13 0 100 1981 1982 Time (year and month} 24 12 0 12 0 15 6 92 Fig. 36. Scheuchzeria palustris. Length growth rate Total no throughout the season in seven (I-VII) consecutive of leaves 12 12 16 12 leaves from the same shoot. A = Number of dead leaves at date indicated. B = Surviving leaves at date indicated as percentage of the origi­ nal number.

a Third leaf in 4-leaved individuals, third and fourth leaf in 5-leaved individuals.

leaf died in August. Younger leaves died in Septem­ ber, except the youngest, the base of which survived the autumn. Such leaves often survived until the next summer. In the few cases when I could follow the fate of such leaves they lived until the middle of July of their second year, i.e. nearly one year. In au­

M J J A tumn, small leaves can be found enclosed in the leaf Time (month) sheaths of older leaves. These are probably the first Fig. 37. Scheuchzeria pa/ustris. Emergence of each leaf in leaves of next year. 1982 in 5-leaved 6) and 4-leaved ( •-•; n = ( •- --•; The seasonal changes in the number of leaves per 6) shoots as percentages of the total number. n = shoot is shown in Fig. 38. The maximum number of leaves was attained in early July and maintained through this month but the maximum of leaf area was attained in the latter part of July because of the differences in the length of different leaves on the shoot. The leaves on a shoot are of very different length (Fig. 39). The first and last leaves are considerably

-o -o-o-o-o-o -o-o 0

0/ 0-0 /

Fig. 38. Scheuchzeria palustris. 2 Mean number of living C ( ) to­ • , tal C (0) and living C 1 + <•) leaves per individual on 12 indi­ viduals followed throughout the M A s season in 1982. Time (month)

Acta Phytogeogr. Suec. 74 58 Ingvar Backeus

Fig. 39. Scheuchzeria palustris. Leaflengths (± 1 S.E.) in 5-leaved individuals. From the material of the main samplings. Sampling dates: (a) Aug. 11, 1980; (b) June 17, 1981; (c) Aug. 27 , 1981; (d) June 16, 1982; (e) Aug. 25, 1982. 200 The letter (f) denotes samples with means significantly different at the 95 level (t test). Within OJo each leaf in the sequence columns (a), (c) and (e) are compared to each other as are (b) and (d). 150

100

a b c d e a b c d e a b c d e a c e a c e 1 2 3 4 5 Leaf sequence

shorter than the middle leaves. The third and fifth month. The decrease continued at a slower rate leaves in five-leaved shoots deviated in 1982, being through August and all growth ceased in early Sep­ shorter and longer respectively than previous years. tember. Whether this is because of shorter days, The fifth leaf was probably not full-grown in 1980 cooler conditions or an inherent growth rhythm because sampling was earlier than in 1981 and 1982. cannot be said. The influence of temperature on It can also be seen that the second leaf was later in growth is obvious in the figure (cf. Fig. 53). In the its development in the middle of June 1982 than in cool month of June 1982 the growth was very slow, 1981. From Fig. 40 it can be seen that the leaf weight in contrast to the situation in June 1981. The same per unit length was higher in 1982 than in previous effect is seen in the aberrant curves of the second years. This is especially noticeable in the second leaf and third leaves of 1982 in Fig. 36. at the early sampling, considering the differences in The density was constant over the years (Table phenological state just mentioned. The differences 25). The proportion of flowering individuals was between the early and late sampling are due to sen­ low, 0. 14 OJo and 1.4 in 1980 and 1981 respec­ OJo escence in the second leaf and further growth in the tively. In 1982 no flowers were seen. third leaf. The biomass and production per individual The seasonal changes in length growth of the (Table 20) was higher in 1982 than in 1980 (p

Acta Phytogeogr. Suec. 74 Production and growth dy namics of vascular bog plants 59

Fig. 40. Scheuchzeria palustris. kl Leaf weight in mg (± 1 S.E.) per unit length in 5-leaved individ­ �0CD .20 uals. From the material of the ce· main samplings. Sampling dates ;:r "0 as in Fig. 39. Columns having the � 1: same letter are significantly dif­ :s ;::;: ferent at the 95 0,1o level (t test). CD" Columns are compared as in Fig. :s 0.15 c.c... 39. ::r

c.c3

3 3� - 0.10

0.05

c e c e 2 3 4 5 Leaf sequence

2 Fig. 41. Scheuchzeria palustris. Rate of length growth in the youngest leaf followed on the same shoots as a function of time M J A s in 1981 and 1982 ( ) . 13. <•) • n = Time (month) Acta Phytogeogr. Suec. 74 60 Ingvar Backeus

Table 20. Scheuchzeria palustris. Quantities in individuals ± 1 I S.E. Weights in mg. Production in mg · year- • n = 25. Harvest dates: 11 Aug. 1980; 17 June and 27 Aug. 1981; 16 June and 25 Aug. 1982.

Cusp. dusenietosum yearly overall mean year means June Aug. leaf number 1980 4.75±0. 12 4.84 1981:2 4.73±0.15 1982:2 5.00± 0.16 healthy leaves 1980 67.1 ±8.2 41 .7 48.6 1981:1 47 .0 ±4.6 1981:2 35.8 ±4.9 1982:1 36.4 ±3.9 1982:2 43.0 ±4.2 senescent leaves 1980 23.3 ±3.0 13.0 51.5 1981:1 4.12± 1.22 1981:2 60.4 ±6.1 1982:1 21.9 ±3.1 Fig. 42. Measuring the relative length of Trichophorum 1982:2 70.9 ±6.5 caespitosum culms as the vertical distance from the base dead leaves 1980 8.48±0.95 0.60 15.4 of the inflorescence to a fixed horizontal bar. Photo: S. 1981:1 0 Nordberg. 1981:2 17.4 ±2.5 1982:1 1.19±0.93 1982:2 20.2 ±2.9 current rhizome: weight 1980 4.77±0.61 6.76 1981:2 9.03± 1 .51 1982:2 6.47± 1 .22 length 1980 8.1 ±0.9

ing the rest of the growing season. As seen above, the difference is in weight per unit length rather than in absolute length. My figures on biomass and production per area Table 26) are from a site where Scheuchzeria is ( more or less the only field layer species. The average above ground biomass of this species in bog carpets is certainly lower. Vasander (1981) gives the figure

147 kg · ha-1 in wet hollows on the bog Laaviosuo. The below ground biomass is probably much higher.

Trichophorum caespitosum

Material and methods

Individual culms of Trichophorum caespitosum 400 600 Temperature sum ( °C) were counted on hummocks, in lawns and in the Fig. 43 . Tr ichophorum caespitosum. Mean cumulative Cuspidatetum tenelletosum. The species was har­ length growth on hummocks ( and in lawns (0) as a vested on hummocks and in lawns around the first •) function of the temperature sum in 1981. n = 8 (hum­ of August. In 1981 and 1982 it was also harvested mocks); n = 10 (lawns).

Acta Phytogeogr_ Suec. 74 Production and growth dy namics of vascular bog plants 61

1 Table 2I. Trichophorum caespitosum. Quantities in individuals ± 1 S.E. Weights in mg. Lengths in mm. Production in mg · year" • n = 25 . Harvest dates: I Aug. I980; I8 June and 31 July I981; I6 June and 29 July I982. hummocks lawns yearly overall yearly overall year means mean means mean culm length 1980 n.d. 1: I40.9 n.d. 1: I47.8 I98I: I I46.2±8.I 2: 230. I I50.0±7.2 2: I97.0 198I :2 235.6± 1l.I 206.0±9.9 1982: I 135.5±6.5 I45.6±7.I 1982:2 224.6± 10.4 I87.9± Il.3 culm and leaf weight I980 39.5 ±2.I I: 25.54 n.d. 1: 27 .I I98I:I 25.70± l .9I 2: 39.5 27.2 ±2.3 2: 3I.3 I98I :2 39.3 ±3.0 30.90± 1 .96 I982:I 25.38± 1 .67 26.90± 1.96 I982:2 39.6 ±2.5 31.6 ±2.5 inflorescence I980 0.32±0.02 I: 0.56 0.2I±0.03 I: 0.57 I98I: I 0.47 ± 0.07 2: 0.2I 0.52±0.08 2: O.I2 I98I:2 0.13±0.04 0.03±0.0I I982:1 0.64±0.06 0.6I±0.07 I982:2 0. 17±0.04 0.11±0.04 winter bud 1980 12.32±1 .02 2: 7.42 n.d. 2: 4.I7 1981:2 4.84±0.93 3.80±0.72 1982:2 5.09±0.72 4.53±0.59 biomass = production 1980 52.1 ±2.2 1: 26. IO 38.2 ±2.4 1: 27.6 1981:I 26.17± 1 .93 2: 47 .1 27.7 ±2.3 2: 36.4 1981:2 44.2 ±3.4 34.7 ±2.5 1982:I 26.02±1.70 27.51±1.99 1982:2 44.9 ±3.0 36.3 ±3.1 in the middle of June, before the fruits had fallen ceeded in 1981 to the middle of July (Fig. 43). At off. that time the fruits had usually fallen to the ground The plants were fractioned into (1) inflorescence; and the culms turned gradually yellow in their upper (2) culm and leaves (i.e. the single, minor green leaf parts. The senescence was completed in the latter and the basal leaves); and (3) winter bud, including half of September. its rhizome branch. The density was higher in lawns than on hum­ Length growth of the culms was measured on mocks (Table 25). The differences between years hummocks and in lawns in 1981 using the same were not significant because of the high standard de­ method as for Rhynchospora alba (Fig. 42). The dis­ viation of the samples. The coefficient of variation tance from the horizontal bar to the base of the in­ (s/x) was 2.9 on hummocks and in the Cuspidate­ florescence was measured repeatedly with vernier turn tenel/etosum and 1.8 in lawns. Such high values calipers on 18 selected plants (1 0 in lawns and 8 on are to be expected in a tussock-forming species. hummocks). Measuring errors up to ea. ± 3 mm had The weight per individual (Table 21) was higher to be accepted. When the experiment started, on hummocks than in lawns. The plants were also growth probably had already been going on for a taller on hummocks (p<0.1 in 1981; p<0.05 in couple of weeks. At the end of the experiment the 1982). As usual, etiolation is a likely explanation. plants were dug up and their absolute length mea­ The winter buds of hummock specimens were sured. very much heavier in 1980 than in later years (p<0 .001). Differences in culm weight were, on the other hand, very small between years. Also the Results and discussion variation in weight within each sample was small. The length growth of the culms of Trichophorum The coefficient of variation for individual biomass caespitosum started in May, probably as soon as the was 0.2-0.4 on hummocks and 0.3-0.4 in lawns. peat had thawed. Flowering occurred in late May Unlike other bog species, practically all shoots of and early June. The length growth of the culms pro- Trichophorum carried flowers. Culms without an

Acta Phytogeogr. Suec. 74 62 Ingvar Backeus inflorescence did occur but were rare. The species The harvesting units had to be consistent with the allocated between one and two per cent of its above­ counting units. Thus, in 1980 apical ends of shoots ground production to inflorescences. were chosen at random and followed backwards un­ In Table 21 I have equated production with bio­ til the first adventitious root where they were cut mass, which is not entirely correct. Parts of the bio­ (but always so that all living leaves were included mass were produced already in the previous year and also the whole current shoot). In 1981 and 1982 within the winter bud, but to what extent cannot be current shoots were chosen in the same way. The calculated. majority of the collected plants had not more than Pearsall Gorham (1956) reported that pure one current shoot. The leaves were separated into C, & stands of Trichophorum in Great Britain have an C 1 and older. In 1980 only C stems were kept; in + average standing crop of 45 kg · ha-1, which is quite 1981 also C + 1 stems. Older stems were discarded low compared to the 150 kg · ha-1 reported by For­ except in 1982. Attached dead constituted a separate rest Smith (1975) from a wet blanket bog at Moor fraction in 1981 and 1982 (discarded in 1980). & House. All fractions were weighed, stem length was mea­ sured to 0. 1 mm and the number of leaves counted. The number of shoots was also counted which was necessary for the conversion of biomass to an area Vaccinium microcarpum basis. The aboveground biomass was defined as the har­ Samuelsson (1922) claims that the distinction be­ vested parts of the plants. tween Vaccinium microcarpum and V. oxycoccos only rarely causes difficulties. This may be true for Results and discussion a taxonomist who is only concerned with good speci­ mens with flowers, but for an ecologist who has to The density of V. microcarpum (Table 25) was determine also weak, more or less languishing markedly higher on hummocks than in lawns plants without flowers the situation is different. The {p<0.001). This is in agreement with earlier authors reliable characters mentioned in the literature are (M.P. Porsild 1930, Sj ors 1948, etc.). I did not find floral (Samuelsson 1922, M.P. Porsild 1930, A.E. the species in any of my squares in carpets. There Porsild 1938). Most specimens on the bog were, were no flowering plants in the sampled quadrats. however, not flowering and I chose to classify all The production per individual (Table 22) was doubtful shoots among V. oxycoccos. higher in 1980 than in the later years. This applied The correlation coefficient of the density values to both stem length, stem weight per length, leaf of the two species on hummocks was -0.02. This number and weight per leaf. The differences were lack of correlation is remarkable considering that not significant throughout but were consistent in all between two species closely related in taxonomy, categories mentioned. In 1982, leaves made up morphology and life form ''the struggle will gener­ 52 of the biomass. Of the shoot production 60, OJo ally be more severe, if they come into contact with 64 and 63 respectively were allocated to leaves in OJo each other, than between species of distinct genera'' the different years. (Darwin 1859). The question arises whether we are Biomass and production per area in lawns were really dealing with two taxa on the species level. calculated from the assumption that there were no differences in individual weight between lawns and hummocks. The results (Table 26) can be compared Material and methods with values from the bog Laaviosuo where Vasan­

In 1980 apical ends of shoots of V. microcarpum der ( 1981) estimated a biomass of 17-18 kg · ha-1 were counted. This was changed in 1981 and 1982 on hummocks and 3 kg · ha-1 in upper hollows. to current shoots. Figures on density from 1980 are Production was 5-8 and 1 kg · ha-1 • year-1, respec­ therefore not exactly comparable with figures from tively. His production figures are similar to mine. 1981 and 1982. The differences in biomass are probably due to dif­ The species was harvested on hummocks only. ferent definitions of where to delimit above- and

Acta Phytogeogr. Suec. 74 Production and gro wth dy namics of vascular bog plants 63

Table 22. Vaccinium microcarpum. Quantities in individuals ± belowground parts of the plant. A biomass figure

S.E. Weights in mg. Lengths in mm. Production in mg · I 1 from a N. American dwarf shrub tundra is also year- • Harvest dates: 25 Aug. 1980; 21 Aug 1981; 25 Aug. 1982.

available (3 kg · ha-1; P.C. Miller et al. 1982) and hummocks yearly overall two production figures from Eriophorum vagina-

year means mean tu m tussock tundras (5 and 1 kg · ha-1 • year·1; Wein Bliss 1973). leaf number C 1980 7.00±0.96 5.83 & 1981 5.50±0.43 1982 5.00±0.44 C+l 1980 1.88±0.45 2.18 1981 2.23 ±0.54 1982 2.42±0.47 Vaccinium oxycoccos C+2 1980 0.27±0.17 0.35 1981 0.35±0.18 Material and methods 1982 0.42±0.20 shoot number C 1980 1.03±0.10 1.13 Counting, harvesting and fractioning of Vaccinium 1981 1.19±0.10 oxycoccos were made in the same way as for V. 1982 1.17±0.08 microcarpum. Because of the changes in sampling 1980 22.2 ±4.9 17.0 stem length C technique the figures on density from 1980 are not 1981 15.9 ± 1.8 1982 12.9 ±1.6 exactly comparable with 1981 and 1982. C+l 1980 n.d. 11.0 Length growth of current vegetative shoots was 1981 9.4 ± 1.8 measured in 1981 and 1982 with vernier calipers on 1982 12.6 ±1.7 ten selected specimens each in hummock and lawn leaf weight C 1980 1.38±0.33 0.91 1981 0.65±0.10 vegetation. The results from 1982, however, are of 1982 0.70±0.10 little value because most of the shoot tips were de- C+l 1980 0.59±0.17 0.53 stroyed in the summer frosts. Five of the hummock 1981 0.51±0.16 specimens did not develop any shoots in 1981 either 1982 0.49±0.12 C+2 1980 0.10±0.08 0.09 and were therefore excluded. 1981 0.07±0.05 1982 0.09±0.05 stem weight C 1980 0.92±0.23 0.56 Results and discussion 1981 0.37±0.07 1982 0.40±0.06 The shoot growth of V. oxycoccos commenced in C+l 1980 n.d. 0.46 late May and ended in July (Fig. 6), shorter shoots 1981 0.38±0.08 earlier than longer shoots. In 1981 growth ceased in 1982 0.55±0.10 the longer shoots at a temperature sum of between �C+2 1980 n.d. 0.34 1981 0.45±0.22 500 and 600°C (Fig. 44). The current shoots nor- 1982 0.24±0.06 mally attained a length of 30-70 mm but occasional biomass 1980 n.d. 2.58 shoots can be 100 or 200 mm long, especially in hol- 1981 2.70 lows. In 1981 I found an exceptional current shoot 1982 2.46 which was 508 mm long. Warming (1884) reported attached dead 1980 n.d. 0.23 1981 0. 19±0.08 shoots to be up to 65 cm and Rauh (1938) 60 cm. 1982 0.28±0.08 Adventitious roots are often formed already during shoot production 1980 2.30 1.47 the second year, but very seldom during the first 1981 1.02 1982 1.10 year. The older shoots are overgrown by mosses, wood increment C +I 1980 n.d. 0.16 usually within a few years. Leaves are overwinter- 1981 0.16 ing. From Table 23 it seems that mortality up to Au- 1982 0.16 gust in the second year is higher on hummocks than in lawns, probably because of more rapid over- growth. The species occurs in hummock and lawn vegeta- tion and, with lower density, in carpets (Table 25). There are no obvious differences in individual

Acta Phytogeogr. Suec. 74 64 Ingvar Backeus

veloping new shoots after the frosts, whereas in lawns low temperature caused less mortality in cur­ rent shoots but a considerable reduction in their pro­ duction. The production on an area basis (Table 26) was 3 lower than on the bog Laaviosuo in Finland (51 -34 �20 kg · ha-' · year-' on hummocks, 64 kg · ha-' · year-' in upper hollows; Vasander 1981). Higher values are certainly common in such fens where V. oxycoccos

dominates. Liedenpohja (1981) reports 130 kg · ha-' · year-' in an oligotrophic fen in south Finland. 10 Flower and fruit production has not been estimat­ ed but was quite small.

100 300 500 700 Temperature sum { °C) Vaccinium uliginosum Fig. 44. Vaccinium oxycoccos. Mean cumulative length growth of shoots as a function of the temperature sum in Material and methods 1981 on hummocks and in lawns (0). n 10 (hum­ ( •) = mocks); n = 10 (lawns). Individuals were counted and harvested at the first adventitious root. In 1980 and 1981, 25 individuals were harvested, in 1982, 34 individuals. Collected shoot weight between hummocks and lawns (Table plants were fractioned into (I) leaves; (2) current 23). The significant differences that do occur are not stems; (3) older stems; and (4) attached dead. Fruits consistent over the years. did not occur in the collected material. In 1982 at­ Certain differences between years are obvious. tached dead in current shoots was treated separately The plants were severely damaged by frost in June from attached dead on older plant parts. All frac­ 1982. Some shoots died entirely and others had their tions were weighed, the number of current shoots tips destroyed so that growth abruptly ended. Many was counted and the age was estimated by following plants responded by developing new shoots in late the branching systems backwards. June and in July. The damage was more serious on hummocks than in lawns (cf. Andromeda). The to­ Results and discussion tal number of current shoots (incl. killed shoots) per individual was higher on hummocks that year than Vaccinium uliginosum mainly occurs on hum­ in the previous year (p

Acta Phytogeogr. Suec. 74 Production and growth dy namics of vascular bog plants 65

1 Table 23 . Vaccinium oxycoccos. Quantities in individuals ± 1 S.E. Weights in mg. Lengths in mm. Production in mg · year· • n

= 25 on hummocks; n = 32-36in lawns. Harvest dates: 25 Aug. 1980; 21 Aug. 1981; 25 Aug. (lawns) and 31 Aug. (hummocks) 1982. hummocks lawns yearly overall yearly overall year means mean means mean leaf number c 1980 11.4 ±2.4 10.86 7.28±1.28 7.91 1981 10.00±0.97 9.68±1.25 1982 11.17±1.48 6.78±1 .04 C+1 1980 5.40± 1.43 6.16 6.64±0.78 6.24 1981 6.24±0.83 5.74±0.73 1982 6.83±1.24 6.34±0.83 C+2 1980 1.88±0.71 2.24 0.83±0.35 1.83 1981 2.72±0.74 2.44±0.81 1982 2.13±0.65 2.22±0.56 shoot number c 1980 1.48±0.19 1.64 1.28±0.12 1.30 1981 1.52±0. 12 1.27 ±0.10 1982 1.91 ±0.26 1.34±0.15 ditto, incl. dead shoots c 1982 2.17±0.31 1.44±0.14 stem length c 1980 46.6 ±10.3 40.8 30.8 ±9.9 36.2 1981 36.6 ±5.9 53.9 ±15.9 1982 39.1 ±8.4 24.0 ±6.8 C+1 1980 n.d. 31.1 n.d. 26. 1 1981 24.4 ±6.8 28.4 ±5.1 1982 37.7 ±10.3 23.8 ±4.0 C+2 1980 n.d. 15.4 n.d. 16.2 1981 14.0 ±3.8 19.4 ±9.0 1982 16.7 ±4.6 12.9 ±4.7 C+3 1980 n.d. 4.1 n.d. 2.5 1981 3.7 ±1.8 1.9 ±1.7 1982 4.5 ±2.0 3.1 ±1.4 leaf weight c 1980 7.85 ± 1.95 6.55 5.33±1.20 5.57 1981 4.99±0.88 7.73±1.27 1982 6.80±1 .29 3.65±1.15 C+1 1980 5.18± 1.48 5.56 6.00±0.94 5.31 1981 4.26±0.82 4.97±0.72 1982 7.24± 1 .64 4.95 ± 0.92 C+2 1980 1 .94± 1 .07 1.91 0.93 ± 0.45 1.73 1981 2.21±0.65 2.38±0.90 1982 1.57±0.52 1.88±0.64 stem weight c 1980 3.98±1.14 3.11 3.41 ± 1 .40 3.06 1981 2.27±0.52 3.74±0.70 1982 3.09±0.72 2.02±0.82 C+ l 1980 n.d. 3.31 n.d. 3.20 1981 1.98±0.47 3.60±0.75 1982 4.63 ± 1.32 2.79±0.63 C+2 1980 n.d. 1.79 n.d. 2.73 1981 1.34±0.36 2.79±1 .29 1982 2.24±0.60 2.66±1 .66 C+3 1980 n.d. 0.72 n.d. 0.36 1981 0.63 ± 0.28 0.22±0. 18 1982 0.80±0.38 0.51±0. 23 �C+4 1980 n.d. 0.41 n.d. 0.09 1981 0.75±0.50 0 1982 0.07±0.07 0.18±0.12

Acta Phytogeogr. Suec. 74 66 lngvar Backeus

Table 23 (cont.)

hummocks lawns yearly overall yearly overall year means mean means mean biomass 1980 n.d. 22.9 n.d. 22.4 1981 19.0 25.6 1982 26.8 19. 1 attached dead" 2:: C+l 1980 n.d. 0.38 0.09±0.09 0.35 1981 0.30±0.21 0.54±0.32 1982 0.46±0.21 0.43 ± 0.23 c 1982 0.32±0. 12 0.31±0. 18 shoot production 1980 11.8 9.7 8.7 8.6 1981 7.3 11.5 1982 9.9 5.7 wood increment C+ 1 and C+2 1980 n.d. 1.46 n.d. 1.69 1981 0.80 1.15 1982 2. 12 2.23

" Incl. leaves older than C + 2, which are not given as a separate category.

Table 24. Vaccinium uliginosum. Quantities in individuals 1 the last year and flowering occurred in the middle 1 ± S.E. Weights in mg. Production in mg · yea{ • Age in years. n and second half of June. Senescence ofleaves occur­ 25 in 1980-1981; 34 in 1982. Harvest dates: 11 Aug. 1980; = n = red in early September. 20 Aug. 1981; 13 Aug. 1982. Differences in density (Table 25) and in individual hummocks yearly overall biomass {Table 24) between years were not signifi­ year means mean cant. The higher figures from 1982 seem to be due age 1980 4. 12±0.32 4.19 to a few large individuals that happened to be in­ 1981 4.07±0.40 cluded in the sample and considerably increased its 1982 4.38±0.43 standard deviation. shoot number C 1980 8.19±1 .65 7.68 The summer frosts in 1982 caused considerable 1981 5.41 ±0.81 1982 9.44± 1.81 damage. Because of the rapid shoot elongation in leaf weight 1980 24 1±40 246 this species there had already been much shoot pro­ 1981 201 ±35 duction before the first frost nights and the shoots 1982 297 ±90 were killed to a considerable degree. The production stem weight C 1980 65 .2± 12.1 85.4 1981 56.1±14.7 figures from 1982 are therefore underestimates, al­ 1982 135±84 though current attached dead is included. 2:: C+1 1980 487± 115 453 A pure stand of V. uliginosum can have a biomass 1981 463 ± 135 of 5700 kg · ha-1 (Mork 1946). Chepurko (1972) ob­ 1982 408±110

tained 710 kg · ha-1 in a dwarf shrub tundra on the biomass 1980 792± 160 784

1981 721 ±180 Kola Peninsula. Kosonen ( 1981) estimated 410 kg · 1982 840±220 ha-1 in a pine bog where V. uliginosum was the sec­ attached dead total 1980 83±31 90 ond most important species after Empetrum nig­ 1981 84±22 1982 103±33 rum. My figures {Table 26) are more similar to those

c 1982 27.2± 13.4 from a north Finnish subalpine heath (180 kg · shoot production 1980 306±50 341 ha-1, Kallio Karenlampi 1971) and from tussock & 1981 257±49 tundra in Alaska (up to 190 kg · ha-1, Wein Bliss 1982 459± 137 & 1974). Rosswall et al. (1975) reported a standing

Acta Phytogeogr. Suec. 74 Production and growth dy namics of vascular bog plants 67

crop of 130 kg · ha-1 on the subalpine Stordalen centage on peat is evidently the moss growth that mire. successively rejuvenates the visible aboveground The yearly production constituted 40-50 of part of the population. OJo the biomass on the SkattlOsberg Stormosse. Figures The green biomass was 30-50 % of the total in the literature range from 21 to 36 % on mineral aboveground biomass. Figures from mineral soil soil (Mork 1946, Kallio Karenlampi 1971, Kallio are naturally lower (21 %, Kallio 197 5; 17 %, M or k & 1975, Karlsson 1982). In the Stordalen mire the per­ 1946; 12 %, Chepurko 1972). centage was 40. The reason for the higher per-

Acta Phytogeogr. Suec. 74 Field layer density, biomass and production

the individual weight of each single species. In the Discussion on methods individual plant method only the latter kind of vari­ ation is investigated through harvesting. The varia­ One of the purposes of my investigation was to test tion in density is studied through counting, which the applicability of the individual plant method in is much less time-consuming. This means both less a mire ecosystem. The method has been commonly work and more detailed information about the used for estimates of biomass and production of the study object. shrub and tree layer. Its applicability within the field Production estimated with the difference method layer has been discussed by T. Traczyk (1967a, b), does not account for the flux within the plant or the Brechtl Kubicek (1968), Kubicek Brechtl (1970) population. Very rapid growth may give zero net & & and Aulak (1970). The method can hardly be ap­ production if old parts are lost at the same speed (cf. plied in all kinds of vegetation. In species-rich com­ Noble et al. 1979). munities the harvesting and processing of an ade­ The individual plant method also enables the quate number of individuals would be very time work to be adjusted in various ways to the different consuming, unless a substantial number of them are species involved: so rare that they can be omitted. On the other hand, 1. The number of squares for density determina­ separation to species level in the harvest method is tion and the number of harvested individuals may also very laborious. be chosen for each species so that the standard error Another problem is how to distinguish individu­ is kept fairly low. In this way work input is further als. Genets, i.e. real genetic individuals, can seldom minimized. be distinguished in closed vegetation. The opera­ 2. The quadrat size may be chosen separately for tional definition of an individual as the unit (ramet) each species depending on its size, frequency and obtained when a plant is cut at ground level or at the pattern. In practise the quadrat size for a particular first adventitious root, is sometimes also difficult to species was a compromise between the wish not to apply. In prostrate species, where individuals may have a large number of units per square that were intermingle in mats, it is necessary to count and har­ too difficult to grasp and the wish to avoid a large vest other 'plant units' (Williams 1964) than appar­ number of empty quadrats. ent individuals. In my case this was done without 3. The time for counting and harvesting can also much difficulty. In other kinds of vegetation, e.g. be chosen separately for each species. It is therefore in grasslands, where several similar species of pro­ not necessary to make the compromises that are strate grasses may predominate, it is perhaps im­ unavoidable when the peak biomass of the whole possible to apply the method. community is to be determined. In vegetation where it can be applied the individ­ Repeated sampling is also made easier. The ual plant method has several advantages: counting can be done repeatedly in the same quad­ Standard errors in figures for production and bio­ rats, thus reducing random variation between samp­ mass from quadrat harvesting are often very large lings. When no differences in density are expected and it is often too laborious to harvest a sufficient over time the renewed counting may be omitted and number of quadrats in order to reduce the standard the field work is then reduced to collection of the re­ error. This problem has been discussed by, e.g. So­ quired number of individuals. nesson Bergman (1972, 1980). The variation in The information obtained on density and individ­ & biomass from one square to another, however, can ual weight is of course of interest per se. The greatly be regarded as being composed of two main vari­ reduced amount of collected material also makes it ables: the variation in density and the variation in easier to manage a more detailed fractioning. It is

Acta Phytogeogr. Suec. 74 Production and gro wth dy namics of vascular bog plants 69

�50 particularly important that the current year's pro­ Q) ::I duction can be separated, and thus measured di­ Q. a Q) rectly. a. � It was considered desirable that the standard er­ a :.4o rors in measurements of density and individual cf. weights did not exceed 10 of the mean (cf. Milner 0 OJo .... Hughes 1968). The density values in carpets are & considered as examples only and broader standard errors were therefore accepted there. However, also in lawn and hummock vegetation it was not always possible to keep within the 10 limit. It must also OJo be borne in mind that sampling had to start before the required sample sizes were known. The number of squares on hummocks and in lawns was 100 each for all species. As can be seen from Table 25, a larger number of squares would have been desirable for several species. The relia­ bility increases, however, very slowly with an in­ creasing number of squares, as can be seen in Fig. 45. To reduce the standard error in Eriophorum va­ ginatum on hummocks from 16 to 10 would have OJo necessitated ea. 140 extra squares. In Trichophorum caespitosum on hummocks ea. 650 extra squares 50 would have been needed. The higher reliab.ility of b the figures would not provide sufficient justifica­ tion for such a laborious analysis. Among the less important species high standard 40 errors had to be accepted in the density determina­ tions. For the estimations of total biomass and pro­ duction this had little importance. On the other hand, even a rare species may be interesting in itself 30 and high production and biomass figures are not ne­ cessarily more interesting than low figures. It would have been ideal to have the squares at 0 fixed points throughout the investigation but, due 20 '\ 0 \ to trampling damage, the transects along which the O - o squares were laid out had to be moved in 1981. Each

\ o, square was not marked permanently; there were o ..... o ...... o -o- o only markings on every 20 m along the transects. It 10 ' o O - 'o- o --=--­ - o - 0 -o-o should therefore be remembered that when density figures from the repeated sampling in 1980 are com­ pared the random variation between sampling is considerably smaller than at random sampling but 20 40 60 80 100 not zero. The same applies when figures from the Sample size main samplings in 1981 and 1982 are compared. Fig. 45 . Standard error (in of the density as a function OJo ) The number of collected units varied from 25 to of sample size in Trichophorum caespitosum , Erio­ ( • ) 100. Also here it was not always possible to reach phorum vaginatum (0), Andromeda polifolia Cal­ (•). luna vulgaris (D) and Vaccinium microcarpum (a) the desired reliability (Fig. 46). Variation was par­ (£). Hummocks. (b) Lawns. ticularly great in Calluna and the standard error re-

Acta Phytogeogr. Suec. 74 70 Ingvar Backeus

;C/) 50 50 :I Q. c Cl I a. t. � a � 40 40 � 0 .\ .... 3 CD Cl X 2. 30 � 30

0 R

" t...... �t."..... " " " 20 \ " 20 0 \ " ..... " "' " ' " 0 ; "' " - " \ u ...... , D- o-.a/o-...o \ 0 10 ..._ 0 10 o - o - o

40 60 80 100 20 Sample size

Fig. 46. Standard error (in as a function of sample size 07o ) in Vaccinium uliginosum (LI ), Calluna vulgaris (D), An­ dromeda polifo lia on hummocks A. polifo lia in (•). lawns (X) and Eriophorum vaginatum (0). (a) Individual biomass on hummocks. (b) Ditto in lawns. (c) Individual production.

mained large although as many as 100 plants were collected. This was unfortunate considering that Callunais the dominant species on hummocks. The possibility of changing to another counting and har­ vesting unit was considered but no other such unit was found practicable. To some degree the relia­ bility was improved by the separation of 'flowering units' as a special category. The homogeneity of the bog vegetation consider­ ably reduces the difficulties in sampling. In a more

2u 40 60 80 100 heterogeneous vegetation great care must be taken so that both density determinations and harvesting are made without bias. Not even bog vegetation is, of course, fully homogeneous. Fransson (1972) dis­ tinguished five fades on hummocks, three (or four) of which are present on the Skattlosberg Stormosse. There are also transitions between the open bog hummocks and the pine bog. At harvest the selection of specimens must be made with much care to avoid a bias towards large

Acta Phytogeogr. Suec. 74 Production and growth dy namics of vascular bog plants 71

4 Table 25 . Number of individuals or other units (see text) per ha x 10- ± 1 S.E. hummocks lawns carpets Cusp. dusen. C. tenellet. species year number S.E. number S.E. number S.E. number S.E.

Andromeda polifolia" 1980 266 41 496 30 n.d. 362 80 1981 328 30 499 24 n.d. 490 61 1982 317 28 490 30 n.d. 453 46 Betula nana 1980 4.46 0.55 0. 139 0.078 0 n.d. 1981 5.88 0.64 0.473 0.120 0 n.d. 1982 5.39 0.61 0.613 0.141 0 n.d. b Calluna vulgaris, total 1980 1515 129 n.d. 0 n.d. 1981 1342 120 n.d. 0 n.d. 1982 1413 140 n.d. 0

C. vulgaris, floweringb 1980 453 61 0 0 0 1981 59.4 12.0 0 0 0 1982 31.0 6.9 n.d. 0 n.d. Drosera anglica, non-flowering 1980 0 0 n.d. 14.9 8.0 1981 0 0 n.d. 18.7 5.9 1982 0 0 n.d. 12.8 3.5

D. anglica, flowering 1980 0 0 0 2.1 2.6 1981 0 0 0 1.07 0.74 1982 0 0 0 0.53 0.53 D. rotundifolia, non-flowering 1980 13.5 2.6 5.28 1.06 0 116 42 1981 16.4 3.4 10.3 3.0 0 146 24 1982 15.0 3.0 9.9 3.0 0 143 22 D. rotundifolia, flowering 1980 2.30 0.53 0.82 0.26 0 10.1 5.9 1981 2.61 0.51 1.76 0.38 0 11.7 2.5 1982 1.20 0.30 0.96 0.44 0 4.27 1.52

c Empetrum nigrum 1980 201 33 n.d. 0 n.d. 1981 196 36 n.d. 0 0 1982 197 33 n.d. 0 0 Eriophorum vaginatum, non-flowering 1980 222 33 527 56 n.d. 33.6 18.5 1981 216 33 535 48 n.d. 31.5 10.2 1982 262 35 484 38 n.d. 41 .1 14.0

E. vaginatum, flowering 1980 1.19 0.11 0.683 0.062 n.d. n.d. 1981 1.360 0.136 0.789 0.069 0 n.d. 1982 2.06 0.21 0.345 0.048 0 n.d. Rhynchospora alba, non-flowering 1980 0 0 0 1080 1981 0 0 0 1183 105 1982 0 0 0 993 109 R. alba, flowering 1980 0 0 0 1190 124 1981 0 0 0 703 160 1982 0 0 0 617 108 Rubus chamaemorus, non-flowering 1980 79.0 6.8 16.6 2.6 0 n.d. 1981 84.8 6.5 14.2 2.2 0 n.d. 1982 85.3 5.9 14.8 2.3 0 n.d.

R. chamaemorus, flowering 1980 0.170 0.032 0.0175 0.0075 0 0 1981 0.042 1 0.01 12 0.0075 0.0056 0 0 1982 0 0 0 0

Scheuchzeria palustris, non-flowering 1980 0 0 331 50 46 21 1981 0 0 260 25 34.7 8.4 1982 0 0 28 1 30 29 .9 8.0

S. palustris, flowering 1980 0 0 0.47 0.32 0 1981 0 0 3.69 1.06 0 1982 0 0 0 0 Trichophorum caespitosum 1980 93 24 220 36 0 17.6 16.9 1981 121 33 279 47 0 36.8 15.7 1982 161 53 256 55 0 53 37

Acta Phytogeogr. Suec. 74 72 lngvar Backeus

Table 25 (cont.)

hummocks lawns carpets Cusp. dusen. C. tenellet. species year number S.E. number S.E. number S.E. number S.E.

Vaccinium microcarpum d 1980 353 59 21.6 14.5 0 n.d. 1981 326 34 127 34 0 n.d. 1982 270 29 87.5 19.2 0 n.d. d V. oxycoccos 1980 143 .4 19.7 151.0 15.5 n.d. 60 30 1981 309 35 24 1 23 n.d. 117.3 17.6 1982 179 23 166 20 n.d. 84 20

V. uliginosum 1980 28.2 9.5 0 0 0 1981 15.0 4. 1 n.d. 0 0 1982 15.0 3.5 n.d. 0 0

a c shoots in 1980, individuals in 1981-82.

b C+3 with attached younger shoots in 1980-8 1. C+2 shoots with attached younger shoots in 1982.

c C shoots in 1980, C +I shoots with attached C shoots in 1981-82.

d Apical ends in 1980, C shoots in 1981-82. n.d. Not determined but small.

plants. To choose the closest plants to regularly three investigated years. Cases of significant differ­ spaced points is not enough. A specified spot on the ences are quite few. A rapid increase in density of plant must be chosen, e.g. the closest stem base or any species is not to be expected in a community the closest shoot tip. where the whole surface is already occupied by When production is to be measured at short inter­ plants and where nearly all propagation is vegeta­ vals random sampling is difficult to apply because tive. Sudden reductions density would have been in the small weight increments may be overshadowed less surprising. The frost in June 1982 killed many by the random variation. Instead, length growth of­ shoots of Andromeda, Vaccinium microcarpum, V. fers itself as a rapid and accurate method. It is the oxycoccos and Rubus chamaemorus but either the only way to determine when growth starts and ends killed shoots were fewer than seemed to be the case and also the growth rate and its dependence on daily at a visual inspection or they were replaced by new temperature. Only a part of the total shoot produc­ shoots. As discussed under the respective species, tion is measured in this way. Because of lignification the latter explanation seems more likely. and secondary cell wall formation and other proces­ During the course of the work it soon became ob­ ses, there is not likely to be a linear relationship be­ vious that spatial patterns on various levels occurred tween length growth and production. The radial in many species. The collected data are not suitable growth in already existing stems is much more diffi­ for discussions on this subject. A more thorough in­ cult to estimate. My estimates of wood increment in vestigation in this field would probably be reward­ Betula nana and Calluna were based on the assump­ ing. tion that the increment is similar throughout the plant. This is not necessarily the case, and especially not in the profusely branched dwarf shrub Calluna. Mean total aboveground biomass and production Density Results

The density of 'individuals' or 'units' of each species Figures on aboveground biomass and production of has been discussed previously. A compilation of all all investigated species based on figures on density density data is given in Table 25. and individual biomass are summarised in Table 26. There are no trends in density variation over the 'Shoot production' denotes production of current

Acta Phytogeogr. Suec. 74 Production and growth dy namics of vascular bog plants 73

' ' ' Table 26. Biomass in kg · ha· and shoot and total aboveground production in kg · ha· · year· of field layer species on the Skattlosberg Stormosse. Mean values for I980- I982.

hummocks lawns Cusp. dusenietosum Cusp. tenelletosum

shoot total shoot total shoot total shoot total species biomass prod. prod. biomass prod. prod. biomass prod. prod. biomass prod. prod. • 3 c c Andromeda polifolia 146 7LI 76_o 133 78.4 83.7 n.d. n.d. n.d. llt 67 74 Betula nana 86.3 21.6 25.6 n.d. n.d. n.d. 0 0 0 n.d. n.d. n.d. b Calluna vulgaris I825 259 272 n.d. n.d. n.d. 0 0 0 n.d. n.d. n.d. Drosera anglica 0 0 0 0 0 0 n.d. n.d. n.d. 3.05 3.05 3.05 c c c Drosera rotundifolia 1.02 1.02 1.02 0.60I 0.601 0.60I 0 0 0 I9.2 I9.2 I9.2 d g Empetrum nigrum 92 23.7 27.3 n.d. n.d. n.d. 0 0 0 n.d. n.d. n.d. " c Eriophorum vaginatum 202 I85 I85 409 408 408 n.d. n.d. n.d. 28 28 2t Rhynchospora alba 0 0 0 0 0 0 0 0 0 145 I45 I45 Rubus chamaemorus 95 .5 99.2 99.2 I0.7 Il.3 11.3 0 0 0 n.d. n.d. n.d. h h h Scheuchzeria palustris 0 0 0 0 0 0 311 355 355 42 45 45 c c c Trichophorum caespitosum 58.1 58.1 58.1 91.2 91.2 91.2 0 0 0 13 13 13 g f f r Vaccinium microcarpum 7.29 4.38 4.78 1.8 0.8 0.9 . & 0 0 0 n.d. n.d. n.d. • 3 c C C Vaccinium oxycoccos 31.9 11.9 14.o 36.2 12.4 17.8 n.d. n.d. n.d. 19 B lO e Vaccinium uliginosum 152 64.6 64.6 n.d. n.d. n.d. 0 0 0 0 0 0

Total 2697 799 827 682 603 614 310 360 360 390 328 340

a Wood increment in C +I and C + 2 only included. b Wood increment in �C + 3 only included. c Assumed the same individual weight as in lawns. d Assumed a production:biomass ratio of 0.2. e Wood increment not included. r Assumed the same individual weight as on hummocks. 8 Wood increment in C+ I only included. h Assumed the same individual weight as in C. dusenietosum. n.d. Not determined but small.

stems and current leaves. 'Total production' also in­ losberg Stormosse, i.e. in the southern boreal zone cludes increment in older stems and leaves when sensu Tuhkanen (1984). Vasander's figures on measured or estimated. It should be noted that the single species have been repeatedly discussed in the figures on individual biomass are from different preceding chapter. The limits between Vasander's dates in different species. communities do not seem to be exactly equivalent to mine and his 'upper hollows' contain rather large quantities of Calluna. Bearing this in mind, the Discussion figures from the Laaviosuo and the Skattlosberg To make comparisons with other sites easier a list Stormosse are strikingly similar. of selected published figures on field layer biomass On both sites biomass was higher on hummocks, and production from bogs, heaths and tundras has where dwarf shrubs with perennial woody stems do­ been compiled in Table 27. It must be borne in mind minate, than in hollows, where cyperaceous and that rather considerable discrepancies can arise be­ similar plants with short-lived shoots predominate. cause of different sampling techniques. The field layer biomass on a pine bog (or, more cor­ The field layer biomas.s on the SkattlOsberg Stor­ rectly in this case, it was a Carex globularis fen) in mosse was rather low. There are not many figures south Finland was found by Kosonen (1981) to be from other bogs with which my results can be com­ on the same level as on open hummocks. It was do­ pared but the investigation of Vasander (1981) on minated by Empetrum nigrum and higher values the bog Laaviosuo offers excellent possibilities. The might be obtained where taller dwarf shrubs domi­ Laaviosuo is situated in south Finland in a similar nate. phytogeographic and climatic region as the Skatt- Production was on the same level on hummocks

Acta Phytogeogr. Suec. 74 74 Ingvar Backeus

' Table 27 . Field layer biomass and production on selected sites compiled from the literature. Biomass in kg · ha· . Production in ' ' kg · ha· · year" .

prod.: biomass biomass or ever- deci- prod.: green duous grami- pro- stand. site shrubs shrubs herbs noids total duction crop

A: The Skatt!Osberg Stormosse hummocks 2102 238 97 260 2697 827 0.31 lawns 171 11 500 682 614 0.90 Cusp. tenelletosum 137 23 228 388 340 0.88 Cusp. dusenietosum 310 310 360 1.16 B: Ombrotrophic bog, S. Finland high hummocks 2454 + 98 264 28 16 898 0.32 low hummocks 1367 82 342 1791 796 0.44 upper hollows 753 20 415 1188 639 0.54 moist hollows 321 10 582 913 711 0.78 wet hollows 141 + 298 439 349 0.79 C: Pine bog, S. Finland 2110 78 19 157 2822 900 0.32 D: Oligotrophic mires, E. Karelia dwarf shrub-Sphagnum mire with E. vaginatum- Sphagnum 840 420 1260 n.d. dwarf shrub-Sphagnum mire with Scheuchzeria- Sphagnum 840 370 1210 n.d. pine-dwarf shrub-Sphagnum thin forest 1210 470 1670 n.d. E: Fens, S. Finland oligotrophic fen 512 99 287 1002 1900 1568 0.83 mesotrophic flark fen 120 196 515 831 780 0.94 herb-rich mesotrophic fen 101 29 1 433 242 1 3246 303 1 0.93

F: Subarctic mire, N. Sweden 1440 180 180 1800 590 0.33 G: Bog, S. Manitoba bog forest 2745 640 0.23 muskeg 5335 2673 0.50 bog 4233 3164 0.75

H: Subarctic wooded peatland, N. Manitoba 3948 + 345 104 4397 n.d.

1: Blanket bogs, N. England mean of 4 sites with dominating Sphagnum 6720 1053 7773 3945 0.51 J: Heath, S. Sweden Calluna ecosystem 9200 n.d. Erica ecosystem 6300 n.d. K: Calluna heath, NE Scotland pioneer phase 3734 933 4668 2759 0.59 building phase 15246 241 15488 4714 0.30 mature phase 19592 164 19756 3926 0.20 degenerated phase 10888 376 11264 1948 0. 17 L: Pine forest, central Sweden young stand, 15-20 years with Calluna 6268 6268 1869 0.30 without Calluna 178 178 42 0.24 young stand, 20-25 years with Calluna 4593 + 3 4596 1112 0.24 without Calluna 9 2 72 83 4 0.05 mature stand, 120 years 1961 1961 1380 0.70 M: East European arctic and subarctic arctic tundra 100 220 420 740 Production estimated northern subarctic tundra 1460 160 350 1970 to 1/10 of dwarf- southern subarctic tundra 1470 30 210 1710 shrub biomass + thin forest tundra 1610 30 190 1830 total biomass thin forest 1690 30 220 1940 of other groups.

Acta Phy togeogr. Suec. 74 Production and growth dynamics of vascular bog plants 75

Table 27 (cont.)

prod.: biomass biomass or ever- deci- prod.: green duous grami- pro- stand. site shrubs shrubs herbs noids total ducti on crop

N: Montane tundra, Kola Peninsula spotted alpine tundra 1700 200 0. 12 dwarfshrub tundra 4750 940 0.20 alpine meadow 5360 2250 0.42 valley tundra with Calluna 4890 545 0.11

0: Arctic tundra, Devon Island, Canada hummocky sedge-moss meadow 860 447 0.52 wet sedge-moss meadow 780 456 0.58 dwarf-shrub heath 530 58 0.11 P: Alpine heaths, Austria Vaccinium heath 10020 110 10130 4220 0.42 Loiseleuria heath 10820 10820 2770 0.26 Loiseleurietum 5620 120 5740 1180 0.21

Sources: A: The present work. B: Vasander 1981. C: Kosonen 1981. D: Yelina 1974. E: Liedenpohja 1981. F: Rosswall et al. 1975. Biomass includes standing dead. G: Reader & Stewart 1972. Biomass includes standing dead. H: Sims & Stewart 1981. 1: Forrest & Smith 1975. J: Tyler et al. 1973. K: Barcley-Estrup 1970. L: Persson 1975b. High production:biomass ratio in the mature stand because of recent thinning. M: Andreev 1966, 1971. N: Chepurko 1972. 0: Bliss 1977. P: Larcher et al. 1975.

and in lawns both on the Skattlosberg Stormosse Figures for the different microsites are not avail­ and on the Laaviosuo. This means a considerably able. Dwarf shrubs dominate and Rubus chamae­ higher aboveground production: biomass ratio in morus and Eriophorum vaginatum almost ex­ lawns, and the reason is evidently the different do­ clusively constitute the herb and graminoid frac­ minating life-forms. The production:biomass ratios tions, respectively. The standing crop was similar to were also high in various fen communities in south the biomass of the Skattlosberg Stormosse and also Finland investigated by Liedenpohja (1981). In production was on the same level. The small differ­ fens, hummocks are few and graminoids and, in ence between these two sites is remarkable consider­ places, herbs dominate. ing the differences in climate. Biomass figures from oligotrophic (probably There are also figures from two peatlands in Ma­ ombrotrophic) mires in eastern Karelia (Yelina nitoba. The first (Reader Stew art 1972) is situated & 1974) are similarly low. Yelina's figures are mean in the southern part of the state, i.e. in the hemi­ values from all microsites in the hummock/hollow boreal zone sensu Tuhkanen (1984). The 'bog mosaic. forest' mentioned in the table was occupied by ma­ The Stordalen mire in subarctic north Sweden ture Picea mariana. The 'muskeg' was more similar was thoroughly investigated within the IBP Tundra to a normal wooded bog with rather sparse trees. Biome Project. It is a mixed mire (cf. Sjors 1950). The stratum called 'bog' consisted of hummocks

Acta Phytogeogr. Suec. 74 76 lngvar Backeus with dwarf shrubs. The biomass was high compared differences in climate or in age structure, or both. to Fennoscandian figures from the boreal zone and Most of the authors mentioned have estimated the field layer was dominated by the relatively tall the biomass of the bottom layer. The corresponding species Chamaedaphne calyculata and Ledum figures for the Skattlosberg Stormosse. so far un­ groenlandicum. The production:biomass ratio was known, can be expected to be of the same magnitude also comparatively high. as those found on the bog Laaviosuo by Vasander Sims Stew art ( 1981) investigated a peatland on ( 1981). There the moss biomass:field layer biomass & permafrost in north Manitoba. They called it a 'sub­ ratio rose from 0.5 on high hummocks (moss bio­ arctic bog' although it was not ombrotrophic ac­ mass 1536 kg · ha-1) to 10.3 in wet hollows (4530 kg cording to the species composition (cf. Sj ors 1963). · ha-1). Ratios from wooded bogs are lower: 0.2 in The biomass was on the same level as the one studied south Finland (Kosonen 1981), 0.2-0.7 in south by Reader Stew art ( op. cit.) and the same species Manitoba (Reader Stewart 1972) and 0.1 in north & & dominated. Manitoba (Sims Stewart 1981). Yelina (1979) ob­ & Blanket bogs in the British Isles have been investi­ tained intermediate ratios on open bogs in East Ka­ gated, i.a., by Forrest Smith (1975). The com­ relia (5.0 and 5.9) but also from pine bog (4.6). & paratively mild climate with a long growing season From the available figures it is probable that the makes them much more productive than Fenno­ moss biomass on the Skattlosberg Stormosse is ea. scandian bogs. 2000 kg · ha-1 on hummocks, ea. 3000 kg · ha-1 in

Dwarf shrub communities on mineral soil usually lawns and 3000-5000 kg · ha-1 in carpets. The re­ have a considerably higher aboveground biomass sults greatly depend on where the limit between dead than similar communities on peat, evidently because and living parts of the moss plants is drawn. there is no overgrowth by mosses. Examples from Little is known about the rhizome and root bio­ Tyler et al. (1973) and Barclay-Estrup (1970) are mass in mire ecosystems. Several species have very given in Table 27. Barclay-Estrup gave figures from extensive rhizome or root systems (see Metsavainio sites with different growth phases of Calluna. The 1931). The over-growth by mosses also continu­ production:biomass ratio of Fennoscandian bog ously causes substantial amounts of previously hummocks is similar to heaths with Calluna in the aboveground stems of vascular plants to be added 'building phase' according to Barclay-Estrup. to the belowground biomass, as in Menyanthes tri­ The biomass and production within pine stands fo liata (Sjors, pers. comm.). Figures from the Stor­ in the southern boreal zone in Sweden were investi­ dalen mire (Flower-Ellis 1980b) and from Eriopho­ gated by Persson (197 5b). In Calluna-dominated rum vaginatum tundra in Alaska (Shaver Cutler & young stands the field layer biomass was high, al­ 1979) on Rubus chamaemorus indicate that the though lower than on the south Swedish heath. In weight of the underground parts of that species may a closed, mature stand the biomass was consider­ be more than twenty times the weight of above­ ably lower. ground parts. Taken over all vascular plants, the ra­ The biomass in tundra ecosystems is very de­ tio of above- to belowground phytomass was ap­ pendent on local- and microconditions. Examples proximately 1 to 4 at Stordalen (Sonesson Berg­ & are given in Table 27 from the East European sub­ man 1972). Reader Stewart (1972) obtained a ratio & arctic (Andreev 1966, 1971), mountain tundra on of 1 to 4.5 in their bog community in north Mani­ the Kola Peninsula (Chepurko 1972) and from a toba. higharctic tundra on Devon Island (Bliss 1977). In Underground production is totally unknown. the far north, as on Devon Island, biomass is Persson (1978 and 1979) showed that root produc­ naturally low, as is also the production:biomass ra­ tion of Pinus sy lvestris, Calluna and Vaccinium tio. In more favourable conditions, as on the Kola vitis-idaea in a pine stand on mineral soil was con­ Peninsula, biomass on a dwarf shrub tundra and on siderably higher than previously believed. It is prob­ a valley tundra with Calluna was found to be double able that older figures for several other species, that of the hummocks on the Skattlosberg Stor­ based on an assumed similarity between above- and mosse but production was on the same level. The belowground production, are also too low. low production:biomass ratio may be due either to

Acta Phytogeogr. Suec. 74 Production and growth dy namics of vascular bog plants 77

The seasonal course of the total On hummocks E. vaginatum was less important aboveground production and chan­ but its continuous growth throughout the season still influenced the shape of the curve of the total ges in the total above ground biomass production. The dwarf shrubs, especially Calluna, were the most important constituents. Growth start­ The seasonal course of production ed simultaneously in late May in most species. B. Earlier I have presented results on the seasonal nana and Scheuchzeria were ea. 10 days earlier course of production in each of the treated species. whereas the two graminoids E. vaginatum and T. In 1980 I repeatedly harvested individuals of Cal­ caespitosum started much earlier, seemingly as soon luna vulgaris (Fig. 12), Eriophorum vaginatum as the most superficial peat layer was free from (Figs. 23-24), Rhynchospora alba (Figs. 29-30) frost. and Rubus chamaemorus (Figs . 32-35) and also de­ As to new shoot formation all species, except E. termined density as often as was considered neces­ vaginatum, had their growth concentrated to June sary. These species were chosen as to represent dif­ and, partly, July. This, together with the maximum ferent life-forms: a dwarf shrub, a perennial grami­ of growth in leaf blades of E. vaginatum caused a noid, a functional annual and a herb. In 1981 I har­ sharp peak in the rate of production in June. In the vested leaves of Andromeda polifo lia (Fig. 7), latter part of August the winter-hardening of the Calluna (Fig. 11), Empetrum nigrum (Fig. 16) and leaves of the wintergreen dwarf shrubs and in the E. vaginatum (Fig. 25) in order to follow weight leaf sheaths of E. vaginatum caused another rise in changes in perennial leaves. Material collected from production. At the same time the wood increment Vaccinium oxycoccos was not processed because I in Calluna and Andromeda stems commenced and found the sampling unsatisfactory. Length growth it is here assumed that the other dwarf shrubs of Eri­ was followed on single shoots in 1981 and/or 1982 cales also performed their wood increments at this inA ndromeda (not published), Betula nana (Fig. 9), time. These two simultaneous events caused a high Calluna (Fig. 10), Empetrum (Fig. 13), Trichopho­ late season peak in the rate of production. rum caespitosum (Fig. 43) and V. oxycoccos (Fig. The late season wood increment in Calluna and 44). Length growth of leaves of E. vaginatum (Figs. Andromeda is a remarkable feature and is not, as 18, 26-27) and Scheuchzeriapalustris (Figs. 36, 41) far as I know, found in any trees. It ought to be in­ was similarly followed. Phenological notes were vestigated further. The autumn increase in leaf and also made continuously (Fig. 6). stem weight is considerable. In Calluna my diagram All the mentioned data have been compiled in an (Fig. 47) shows a production in August twice as high attempt to follow the rate of total production in the as in June and July, although the real height of this hummock and lawn communities. Data from carpet peak is uncertain. Also the results of Grace Wool­ & communities were too incomplete to allow a similar house (1973) show that more than half ofthe above­ treatment. The results are presented diagram­ ground production in Calluna takes place after the matically in Figs. 47 and 48. middle of August. In lawns the total production was largely deter­ Some of the measured weight increases might mined by E. vaginatum. This species represented have been translocations from belowground tissues, two-thirds of the total production. There were two but in this investigation it has not been possible to peaks in the production. The first was in June when separate such translocations from real production. the growth of E. vaginatum leaf blades was at its maximum, which also coincided with the shoot Seasonal changes in biomass growth of all other lawn species. Later in the season the growth of E. vaginatum leaf blades gradually The seasonal changes in aboveground biomass have declined but in August there was a substantial not been followed systematically, since my main in­ weight increment in the leaf sheaths of this species. terest has been in production. For Eriophorum vagi­ This, together with the late season weight increase natum, Rhynchospora alba and Rubus chamaemo­ in leaves and stems of Andromeda, caused a second rus the data from the repeated sampling in 1980 pro­ peak in the rate of total production. vide information not only about production but

Acta Phytogeogr. Suec. 74 78 lngvar Backeus

Ci) Fig. 47. Accumulated production � 1000 throughout the growth period in ;:, Andromedapolifolia <•). Betula · er s· nana Calluna vulgaris <+). 3 (_.), Q) Drosera rotundifolia Em- VI VI (0), • ·- • petrum nigrum Eriophorum ------(�). ;? vaginatum (X), Rubus chamae­ CQ . --- • 100 morus ) , Trichophorum caes­ ( • pitosum Vaccinium micro­ (\7), carpum (D.), V. oxycoccos ( + ), V. uliginosum (0) and total (upper curve) on hummocks. Partly tentative. 10

M J J A s Time (month)

(") 3 1000 c:

�c:· (I) 'tl a c. c: !l 100 ;:,c:r ;? CQ

------+ ------

Fig. 48. Accumulated production throughout the growth period in �------�� ------�------� ------� M J J -- A � 5 � �wns . For exp nations of �m- Time (month) bols, see Fig. 47 . Partly tentative.

Acta Phytogeogr. Suec. 74 Production and growth dy namics of vascular bog plants 79

Fig. 49. Green biomass through­ C) out the growth period on hum­ m 1000 :I mocks. For explanations of sym­ C" bols, see Fig. 47. Partly tentative. s· 3 Ql (/) (/) ';? (Q

10

6 -----

J A

�1000 CD :I C" x -- x --- x s· x -- - 3 Ql (/) (/) ';? (Q 100

10

6 ------+--4------���------+-----�-- 6

Fig. 50. Green biomass through­ out the growth period in lawns. l. For explanations of symbols, see _____. ,::....______� Fig. 47. Partly tentative. A

Acta Phytogeogr. Suec. 74 80 lngvar Backeus

also about biomass. For other species only an esti­ leaf weight in evergreen shrubs in early August was

mate of the peak biomass is available. produced in earlier years, but only 10 %in E. vagi­ Nevertheless, some conclusions can be drawn natum. from the available data. Changes in the above­ Deciduous plants are represented by R. chamae­ ground biomass on the bog can be divided into four morus, B. nana, V. uliginosum and D. rotundifolia, components: production, translocations, litter fall the latter being of little importance. It is assumed and overgrowth by mosses. These components have that the weight of leaves of V. uliginosum and B. been discussed when appropriate in the chapter on nana is on the same level throughout the summer. the individual species. The weight of R. chamaemorus leaves gradually The aboveground parts of Drosera anglica, D. ro­ rises to its maximum and gradually decreases during tundifo lia, R. alba, Scheuchzeria palustris (nearly) the long senescence due to gradual changes in both and Trichophorum caespitosum are completely the weight of individual leaves and density. This has converted to standing dead or litter each autumn. In been shown in the chapter on that species. T. caespi­ plants with perennial aboveground parts but low tosum is functionally also deciduous, although stature, i.e. Empetrum nigrum, Va ccinium micro­ nearly leafless. Its green stem gradually turns yellow carpum, V. oxycoccos and (often) Andromeda poli­ from the middle of July . fo lia, litter fall mainly consists of leaves as stems and branches often change into belowground bio­ mass rather than to litter. In the more tall-growing dwarf shrubs Betula nana, Calluna vulgaris and V. Variations between years in produc­ uliginosum woody stems and twigs can be expected tion to contribute more to the litterfall, in the case of Calluna also short shoots with attached leaves. In The measured production per individual was lower E. vaginatum dead blades break off and fall to the in 1982 than in previous years in Drosera anglica, ground but the leaf sheaths generally remain as at­ Betula nana, Calluna vulgaris, Vaccinium micro­ tached dead for many years until they finally be­ carpum, V. oxycoccos and Rubus chamaemorus, in come decomposed or overgrown. the latter two species in lawns only. It must be re­ The seasonal changes in green biomass in the membered, however, that many figures from 1982 hummock and lawn communities are shown in Figs. are likely to be underestimates because killed pro­ 49 and 50. In lawns (Fig. 50) the curve of the total duction was rapidly converted to litter which was green biomass is mainly determined by E. vagina­ not estimated. During a persistently cool summer turn. In the middle of July this species contributes the rate of production can be expected to be lower 70 of the total green biomass. than normal, which may result in a lower total pro­ OJo On hummocks (Fig. 49) the seasonal changes in duction if this slow growth rate cannot be compen­ green biomass are rather small because evergreen sated by a longer period of active growth. A sudden dwarf shrubs form a major constituent. In Andro­ catastrophe, like a frost night, does not necessarily meda there is an initial rise in leaf biomass followed has this effect. If a shoot is damaged or killed, a new by a decline in July when the plants shed some of shoot (or several shoots) may grow out instead from their older leaves. Late in the season there is again undamaged buds. The result may well be that the to­ a rise caused by the winter-hardening of the leaves. tal production is normal or even higher than nor­ In Calluna the course of the curve is similar to that mal. Such replacement was common in 1982 in An­ of Andromeda. In Empetrum the death of two­ dromeda polifo lia, V. microcarpum, V. oxycoccos year-old leaves starts early in the season, causing the and R. chamaemorus. Of these, only lawn plants of curve to descend in spite of the new leaves formed V. oxycoccos and R. chamaemorus showed a re­ in June and July. duced production in 1982. The different behaviour Because of the evergreenness, 57 and 37 of the of V. oxycoccos on hummocks and in lawns was al­ OJo amount of green biomass in early August was pre­ ready discussed in the chapter on that species and sent already at the beginning of the season on hum­ supports the above hypothesis: The severely da­ mocks and in lawns, respectively. About half of the maged shoots on hummocks were replaced by new

Acta Phytogeogr. Suec. 74 Production and growth dy namics of vascular bog plants 81

shoots. The less damaged shoots in lawns were not G) replaced, but as they were formed in cool weather 0 � the total production became lower than normal. It :r is possible that the different behaviour of R. cha­ Cij... CD maemorus on hummocks and in lawns can be explai­ 3 ned in the same way. 3 0.6 Other species did not form new \_hoots after the frosts. This was the case in B. nana, Calluna and Empetrum nigrum. The frost damage in these spe­

cies was apparently limited. As mentioned earlier, 0.4 I did not see any increase in short shoot growth of Calluna as was found by Lindholm ( 1980) and Lind­ holm Vasander (1981) after frosts in late spring. & It should be noted that there are no evident vegeta­ tive buds in Calluna (e.g. Nordhagen 1937). The 0.2 growth point is therefore unprotected. In Vacci­ nium uliginosum frost damage was considerable but production was on the same level as in earlier years although new shoots were not formed. My results on the effect of frost on dwarf shrubs 5 10 15 Daily increase in temperature sum ( °C) partly deviate from those obtained by Lindholm & Fig. 51. Betula nana. Length growth per day as a function Vasander (1981). They found a marked decrease in of daily increase in the temperature sum. The line con­ production in a year with late springfrosts in all stu­ nects points in chronological order. Each point represents died species, i.e. Andromeda, Calluna, Empetrum the mean of 13 growth measurements and the mean of the nigrum, V. microcarpum and V. oxycoccos. daily increase in temperature sum between two measure­ In Eriophorum vaginatum, Scheuchzeria palus­ ments. Measurements were made in 1982 on May 26, June 1, 8, 13, 17, 22, 28, 30, July 6, 15, 21,25 , 30, Aug. 4 and tris and Trichophorum caespitosum no effect of the 10. frost could be seen, neither visually nor in the tables. In these species the growth point is well protected by leaf sheaths. The generally low temperature had 1966). The respiration during mild nights should a marked effect on the length growth rate of leaves make less energy available for forming structural in the case of Scheuchzeria, but leaf weight per unit tissues. Wielgolaski (op. cit.) found night tempera­ length was instead higher (Figs. 40 and 41). In E. va­ ture to be of only limited importance for growth rate gina tum the low temperature seemed to have no ef­ but different species may react differently. On the fect at all. SkattlOsberg Stormosse most plants ceased their elongation growth before the nights became notably longer in August. Scheuchzeria palustris and Erio­ The dependence on environmental phorum vaginatum are exceptions to this. It is very variables of length growth in stems likely that the prolonged successive decrease in leaf and leaves growth in these species (Figs. 27 and 41) was caused by the longer nights and/or by shorter days which It is reasonable to assume that temperature is the decreased the total daily amount of light. main factor affecting growth rate among field layer The light intensity may also influence growth. I plants on a boreal ombrotrophic bog. Lack ofwater have argued in an earlier chapter that the short-term is not likely to be common. Although the surface variations in growth rate of E. vaginatum leaves in may dry out and the mosses become desiccated, June 1982 (Fig. 27) were caused by differences in water is usually still available for the rooted plants. light intensity. It was shown that this species re­ The length of nights and night temperature are sponds very little to changes in temperature. In likely to influence growth rate (cf. Wielgolaski other species, possible influences of light intensities

Acta Phytogeogr. Suec. 74 82 lngvar Backeus

G') 0 ...:E ::r ii) 0.3 ...� 3 3 3 3 . 6 c. c. D) D) < < l �0.2 5

4 0.1

3

7 5 15 2 Daily increase in temperature10 sum ( °C) ig. 52. Calluna vulgaris.· Length growth per day on 19 F shoots as a function of daily increase in the temperature sum. Measurements were made in 1982 on May 26, June 1, 8, 13, 17, 22, 28, 30, July 6, 9, 15, 21, 25, 30, Aug. 4, 10, 17 and 24 . See further Fig. 51. 5 15 Daily increase in temperature10 sum ( °C) Fig. 53. Scheuchzeria palustris. Length growth per day in the youngest leaf of 12 individuals as a function of daily increase in the temperature sum. The line connects points in chronological order. Measurements were made in 1982 on May 21, 26, June 1, 8, 13, 17, 22, 28, 30, July 6, 9, 15, 21, 25, 30, Aug. 4, 10, 17, 25, 31, Sept. 7, 16, 24.

are likely to be obscured by the effect of tempera­ being quoted in these papers. In the model de­ ture. It is not, however, necessary to assume a direct veloped by these authors it was assumed that growth correlation between photosynthesis and growth. is dependent on two factors: temperature and in­ Stored energy may be used when photosynthesis is herent, physiological growth stage. Three physio­ inadequate and the mobilisation of these stores is logical phases were distinguished: an initial phase also likely to be correlated with temperature (cf. when growth is accelerating, a second phase when Hari Leikola 1974). growth is linear at constant temperature and a final & The dependence of length growth on temperature phase when growth is declining. At a given growth in various plants in an arctic and an alpine tundra stage growth rate was assumed to be wholly depend­ was studied by Bliss (1956, 1966). He found soil and ent on temperature. air temperature to be the most influential of the en­ Works based on this simple principle have given vironmental factors and obtained high correlation very reliable results (Hari Leikola 1974, Kello­ & between temperature and length growth in several maki et al . 1977, Vuokko et al. 1977, Hari et al . species. In other cases correlation was poor. 1977, Lindholm 1980, 1982). Nevertheless, it evi­ The importance of temperature was further inves­ dently cannot be applied to all plants and to plants tigated by, i.a., Hari et al. (1970), Hari Leikola in all environments but it should be justifiable where & (1974) and Hari et al. (1977), several earlier works there is no lack of water and in plants at high lati-

Acta Phytogeogr. Suec. 74 Production and growth dy namics of vascular bog plants 83 tudes which complete their growth while nights are growth declined gradually irrespective of tempera­ still short. ture. 'Temperature' in the works of Hari and his col­ In Scheuchzeria (Fig. 53) length growth of the legues means meteorological temperature. It is, youngest leaf was plotted against the temperature therefore, necessary to assume that the air, soil and sum. A less close regression was to be expected in water temperature near the plants are linearly corre­ this species considering that the growth point is un­ lated to the meteorological temperature, at least der water. Furthermore, the majority of the leaves when the means from one observation to the next were in different growth phases on different mea­ are considered. surement occasions because of the fluctuations in The considerable day-to-day variation in tempe­ leaf emergence (cf. Fig. 37). As already discussed, rature during the shoot elongation period in 1982 growth in this species slowly decreased during late made it possible for me to investigate the depend­ July and August down to zero. ence of length growth on temperature (here expres­ It is possible that the dependence of length growth sed as the increment in temperature sum) in the spe­ on temperature would have been less close if the ob­ cies measured that year. Results for Betula nana, servation interval had been shorter. The differences Calluna vulgaris and Scheuchzeria are shown in in temperature near the plants and in the screen may Figs. 51-53. have levelled out as means of (usually) five to seven In B. nana and Calluna the plants seem already days were used. to have passed through the first physiological phase The poor regression of growth on temperature in of Hari et al. (1977) when measurements started. E. vaginatum has already been discussed and the

The dependence is evidently close in 1 une (Figs. 51 principle of Hari et al. is evidently not applicable to and 52), especially considering the difficulties in plants which are active at very low temperatures. measuring the small increments accurately. In uly, 1

Acta Phytogeogr. Suec. 74 The bog environment and the behaviour of plants

The ombrotrophic mire is generally considered to be Rate of production an extreme environment with regard to low levels of available plant nutrients, acidity and, for deeper It is reasonable to assume (and often easy to ob­ parts of the rhizosphere, oxygen deficiency. This is serve) that a plant in the low-nutrient environment also apparent from the very low number of species. on a bog has a lower production than plants of the It is important to note that no single species is wholly same species in other environments, although few confined to ombrotrophic vegetation, a point that data are available to prove this. It is also reasonable has often been put forward by the Central European to assume that ability to survive with a moderate phytosociologists, who have refused to accept such amount of production has a positive value in the vegetation as a high-ranked plant community of its ombrotrophic environment. own. The plasticity is perhaps more striking in pine (Pi­ Calluna vulgaris, Empetrum nigrum and Vacci­ n us sylvestris) than in other species. Arnborg ( 1943: nium uliginosum are common also in forests and, 153) gave examples of this. Darwin (1859: 72), when as are Betula nana and Rubus chamaemorus, on studying a British heath, noticed a pine that ''had treeless heaths and tundra. Eriophorum vaginatum during twenty-six years tried to raise its head above is also an important tundra species, occurring in the stems of the heath, and had failed". I myself most kinds of minerotrophic mires as well. Andro­ came across a tiny pine on the bog, ea. 1 dm high, meda polifo lia, Drosera anglica, D. rotundifolia, which had 48 visible scars from subsequent apical Rhynchospora alba, Scheuchzeria palustris, Tri­ short shoots, was completely devoid of branches chophorum caespitosum and V. oxycoccos occur and possessed three unhealthy-looking needles at its commonly in various kinds of both ombrotrophic top. On good soil a pine of this age would be 10-20 and minerotrophic mires. The only two field layer m high. This example is extreme; very small pines species that seem to have their main occurrence on cannot maintain a long-term position on the bog bogs (chiefly hummocks) are V. microcarpum and without a permanent input of diaspores from the Pinguicula villosa (the latter species not in the inves­ surroundings. tigated area), but at higher elevation both become In the case of Calluna vulgaris it is easily seen in more ubiquitous as to type of mire (Sjors, pers. the field that shoots are much shorter than on plants comm.). from neighbouring mineral soil. Trichophorum With this background it is hardly appropriate to caespitosum culms are much taller in the lasiocarpa talk about adaptations to ombrotrophy. It is more soak than on the ombrotrophic bog. Leaves of Vac­ likely that even though the plants are not adapted cinium oxycoccos are often markedly larger in fens. to ombrotrophy through evolution they can still In other species studied, exact measurements would withstand it. Even in the case of Sp hagnum cuspida­ be needed to detect differences in individual growth tum, which very rarely occurs in minerotrophic en­ between ombrotrophic and minerotrophic sites. It vironments, it has been shown (Boatman 1977) that is known (e.g. Grime Hunt 1975, Grime 1979) that & the ombrotrophic mire is a suboptimal environ­ the slow growth of species typical of sites with low ment. I will return to this problem later in this chap­ nutrient levels is often inherent. The difference in in­ ter. dividual production between sites might therefore

Acta Phytogeogr. Suec. 74 Production and growth dy namics of vascular bog plants 85 not always be considerable. There are also large dif­ the rhizomes and winter buds. Goodman Perkins & ferences in plant size between sites within the om­ ( 1959) made similar observations in Eriophorum va­ brotrophic vegetation, e.g. Betula nana and Va cci­ ginatum. nium uliginosum are larger in pine bogs than in open Bog plants often have very extensive below­ bogs; Andromeda polijolia and Rhynchospora alba ground parts. R. chamaemorus is a striking example are much larger at the edge of pools, etc. These dif­ and it is difficult to understand how its few tiny ferences (except in R. alba) are probably caused by leaves can support all rhizomes and roots. It is likely differences in age structure rather than in produc­ that one of the explanations of the low aboveground tion. production on bogs can be found in the existence of I sympathize with Grime's (1979) theory that ''the these very considerable root systems. ability to conserve the resources which have been captured and to resist the severe hazards to sur­ vival" are more important in low-productive habi­ tats than the ability of high production. One way of reducing the need to produce more tissue and to maximise the use of photosynthates is evidently to Flowering and reproduction retain photosynthetic tissues as long as possible. It is therefore not surprising-although much debated Flowering was generally poor. I have written earlier in the older ecological literature, see Firbas that flowering in Calluna vulgaris and Eriophorum (1931)-to find a high degree of sclerophyllous vaginatum was poorer than reported by others in evergreenness within the bog flora. Miiller-Stoll populations on mineral soil. In other species no lit­ (1947) and Simonis (1948) showed that the xero­ erature data on abundance of flowers seem to be morphy of bog plants was accentuated in pot­ available. Whether the species flower more readily cultures with low nitrogen levels. Loveless (1961, in other habitats is therefore unknown. Because of 1962) suggested that a sclerophyllous leaf is an ex­ the high density of most species, flowers were never­ pression of a metabolism found in plants that can theless readily seen. To give an example, 0.12 OJo tolerate low phosphate levels. Monk (1966) found flowering shoots of E. vaginatum in lawns still higher degrees of evergreenness on non-productive means one inflorescence in less than 2 m2• Only in sites in Florida than on more productive sites. one case did a species fail to flower entirely: Evergreenness is most prominent on hummocks Scheuchzeria palustris in 1982. because of the dominance of Calluna and/ or Em­ The germination of seeds was not investigated. petrum nigrum. Most of the total populations of Seeds of Rubus chamaemorus germinate readily ac­ these species are found in forests or heaths with aci­ cording to Lid et al. (1961), 0stgard (1964) and Tay­ dic soils. As far as I am aware, no studies have been lor (1971). Calluna seeds also have a high viability made into whether there are genetic differences be­ and germination percentage (Gimingham 1960 and tween the stunted heather shrubs of bogs and their several authors quoted therein). Seedlings of Dro­ more vigorously growing neighbours on mineral sera spp. and E. vaginatum are often seen on bogs. soils. On alpine tundra, where the mobilisation of Sernander (1901) saw seedlings of Scheuchzeria. nitrogen is hampered chiefly by low temperature, Scarcity of seedlings on bogs is therefore probably Calluna has a restricted distribution and the genus not due to poor germination of seeds. Similar condi­ Empetrum is represented by E. hermaphroditum, tions in other closed vegetation have been reported the tetraploid counterpart of E. nigrum s.str. The by, e.g. Malmstrom (1949; boreal forest), C.O. latter probably has experienced natural selection for Tamm (1956; boreal forest and meadows) and Eric­ such habitats but is obviously genetically different son (1977; boreal forest) but these authors suggest from E. nigrum . that reproduction may take place after disturbance High ability of retention of nutrients is also prob­ that creates empty spaces on the ground. This also ably common among bog species. In Rubus seems to be the case in mires, e.g. when the moss chamaemorus it has been shown (Saeb0 1968) that layer disintegrates after artificial draining (own un­ phosphorus is transported from senescent leaves to publ. observations).

Acta Phytogeogr. Suec. 74 86 Jngvar Backeus

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Fig. 54. Map of a clone of Calluna vulgaris f.fl. albae on the bog Digerskyttmossen, near the research site. The area was divided into squares with the size 1 dm2 and the presence of white-flowered Ca/luna ), red-flowered Calluna ( • and non-flowering Calluna (0) was recorded in each square. means Calluna absent. (.6.) x

Vegetative propagation clones that send out runners and intermingle with other species. They could be called the 'massive' and Regardless of presence or absence of flowers and 'wandering' modes of clonal growth. A less aggres­ fruits, the bog plants are propagated vegetatively sive mode of growth is by simple, slow partition of (rarely Drosera spp.). How this is effectuated in the scattered individuals ('subsistent' growth, see be­ different species has been described in detail above. low). Excellent examples of the massive mode of Clegg (quoted in Harper 1978) and Lovett Doust propagation are found among the sphagna in the (1981a) distinguished between two types of clonal bottom layer. The tufted cyperaceous plants Erio­ growth. They gave them names borrowed from hu­ phorum vaginatum and Trichophorum caespitosum man warfare. I find it inappropriate to attribute are also typical, although the clones are usually bro­ murderous human characteristics to plants and will ken up to some extent by the mosses. not use these terms, but the concepts as such are use­ Calluna vulgaris also seems to have (on bogs) a ful. They distinguished between clones that form rather massive clonal growth. Usually it is imposs­ tight monotonous masses of invading shoots and ible to distinguish which Calluna ramets belong to

Acta Phytogeogr. Suec. 74 Production and growth dy namics of vascular bog plants 87

the same clone but I had the opportunity to map a leaves (Nitschke 1860, Swales 1975). This is said to clone of C. vulgaris f.fl. albae on the bog Diger­ occur mainly in the autumn when the plants are skyttrnossen near the research site (Fig. 54). It had normally buried in Sp hagnum, but I have not seen a maximum diameter of ea. 7 m. The outer limits it myself. of the clone were fairly, but not entirely, sharply de­ fined. There was a tendency for the configuration to be ring-like, indicating a concentric, centrifugal Moss overgrowth growth. This phenomenon is well known from other

plants, e.g. Va ccinium myrt us (Flower-Ellis 1971) One of the main factors that influences the perform­ ill and Pteridium aquilinum (Watt 1947, Oinonen ance of the field layer plants on a bog is the length 1967). What is left in the centre is less clear from my growth of the mosses, mainly Sp hagnum. The map, especially considering that only flowering plants must be able to keep pace with the moss rarnets were included. In the case of bilberry growth in order not to be strangled. It was therefore (Flower-Ellis,op . cit.) and bracken (Watt, op. cit.) of interest to study the amount of moss growth or, a mosaic of growth phases is left behind the front. more precisely, the changes in the position of the Empetrum nigrum, as has been discussed earlier, bog surface from one year to another in relation to has both modes of growth: massive where it is domi­ the field layer plants. nant, wandering where it is a subordinate. Betula A way of studying this is to measure the vertical nana is somewhat intermediate. It does not form distance between morphological structures that are runners but also seldom forms really massive fronts. formed at regular time intervals at the moss surface Other species give typical examples of the on a single plant. Arnborg (1943: 153) pointed out wandering propagation: Andromeda polifolia, that small pines (Pinus sylvestris) on Sp hagnum Scheuchzeria palustris and Rubus chamaemorus mires often do not grow faster than the mosses and have underground runners. Vaccinium oxycoccos only have their tips above the moss surface. Boat­ and V. microcarpum are propagated by means of man Tornlinson (1977) determined the age of ad­ & branching of their horizontal shoots. In certain ventitious roots on Calluna sterns at different fens, where V. oxycoccos dominates, the plants may depths below the present surface. I tried a similar more or less cover the ground and appear to have approach on Trichophorum caespitosum, already massive clones, but such mats can probably be sepa­ suggested by Weber (1902). The rhizome of a T. rated into more than one genet. Normally, V. oxy­ caespitosum plant grows upwards each summer un- coccos and V. microcarpum are subordinate spe­ cies. Rhynchospora alba can hardly be put into any of Table 28. Mean length of rhizome segments in mm of Trichopho­ the two types of clonal growth. The genets survive rum caespitosum during the last 10 years in different habitats. by forming easily detached bulbs, usually one or two Measured in 1981-1982.

per individual. It is not known whether a group of habitat length R. alba individuals usually consists of a few vigor­ A Hummock with Dicranum affine and some ous genets or of a large number of genets that merely Sphagnum fuscum 7.7 survive by forming one or two new plants that re­ B Hummock with rapidly growing S. fuscum 6.3 c place the old one. The latter kind of growth may be Hummock with S. fuscum 5.6 D Lawn with S. rubellum 4.7 called 'subsistent'. E Hummock dominated by Cladina spp. 3.4 Drosera spp. survive from year to year by de­ F Hummock with poorly growing Sphagnum, partly dead 3.4 veloping a new leaf rosette rnonopodially. Branch­ G Lawn with S. balticum 3.3 ing is seldom seen. This is also a subsistent growth. H Hummock dominated by Cetraria crispa 3.1 It must be combined with a successful establishment Low hummock 3.0 J Lawn with S. rubellum 2.8 of seedlings; otherwise the species would disappear K Lawn with S. tenellum (a) in the long run. It is however noteworthy that D. ro­ L Trichophorum tussock in a mudbottom (a)

tundifo lia has been reported to be able to form ad­ (a) Rhizome segments short and growing obliquely upwards or ventitious plants from old, seemingly withered horizontally.

Acta Phytogeogr. Suec. 74 88 Ingvar Backeus

til it reaches the bog surface where it forms a winter­ In Rhynchospora alba the basal part of the culm, bud. The growth of this rhizome branch is then which carries basal leaves, originating from the terminated. In later years new rhizome branches will bulb, is prolonged where there is moss growth. The be formed sympodially. bulbs are formed in the leaf axils of the basal leaves Details on methods and results of this study will and will thus be placed higher than the bulbs of the be published elsewhere but the main results are re­ previous year. produced here (Table 28). The tallest rhizome seg­ Apart from Andromeda and Vaccinium uligino­ ments were found in sample A at a place dominated sum (and also Ledum palustre), the bog dwarf by Dicranum affi ne. Already in the field it is con­ shrubs have no special means of escaping over­ spicuous that this moss grows very rapidly. The seg­ growth by the mosses, but my observations suggest ments were also tall on hummocks with healthy that they allocate comparatively more to the length Sp hagnumfuscum (samples B and C) but shorter in growth of the main shoots in places where the risk lawns (samples D, G and J). It is possible that these of overgrowth is high. Physiologically this is prob­ differences reflect differences in winter compaction ably an etiolation reaction. rather than in length growth of the mosses. The Massive clonal growth of Empetrum nigrum is snow pressure can be expected to be less under a ca­ only seen where Sp hagnum growth is poor, this nopy of Calluna than in the more open lawns. The probably being a prerequisite. The short shoots that different Sphagnum species are also likely to be dif­ are developed where Empetrum is dominant would ferently susceptible to compaction. Sample E is be completely buried where Sp hagnum growth is from a lichen-dominated hummock where rhizome high. That Empetrum is seldom a dominant may growth is rather small. In the samples from a S. therefore be the result not only of interactions with tenellum-dominated lawn (sample K) and in a mud­ Calluna but also with Sp hagnum. bottom (sample L) the rhizome segments were quite The horizontal growth of Vaccinium oxycoccos short and not growing vertically. and V. microcarpum makes these species very sus­ Several species have certain properties that make ceptible to overgrowth and their leaves often die be­ it easier for them to escape from being overgrown cause of this rather than from old age. It is likely, by mosses. Drosera spp. and T. caespitosum have however, that their distal ends are often lifted up on rhizomes that grow vertically upwards and keep top of the Sphagnum capitula. This can of course pace with the moss surface. The rhizomes of Rubus only happen distally to the youngest adventitious chamaemorus and Scheuchzeria palustris first grow root. The current shoots of these species often seem horizontally but after some distance the rhizomes to grow upwards. This may, partly at least, be turn upwards and produce aboveground shoots. In caused by such uplift, the proximal end being an­ Scheuchzeria the rhizomes then continue to grow chored in the ground by roots and the distal end be­ upwards more or less concurrently with the moss for ing lifted like a seesaw. It seems that V. oxycoccos several years. In R. chamaemorus the growth is ter­ and V. microcarpum have found a niche of their minated in the first aboveground shoot, but new own near the Sphagnum moss surface, where there shoots are formed sympodially from buds near the is not much interference from other field layer distal end of the rhizome. Andromeda polifolia also plants. forms belowground runners that grow obliquely up­ wards towards the surface. The abovementioned structures are normally Grime's C-, S- and R-selection found in most individuals. Also Eriophorum vagi­ natum has the ability to form prolonged vertical rhi­ Grime (1979) distinguished three different forms of zomes as described earlier (Fig. 17) but they are natural selection that plants have experienced in dif­ found rarely and apparently only where moss ferent habitats. "The first of these (C-selection) has growth is high and the growth point of the shoot involved selection for high competitive ability which comes into a position far below the surface. It would depends upon plant characteristics which maximize be interesting to know how this structure is induced the capture of resources in productive, relatively un­ physiologically. disturbed conditions. The second (S-selection) has

Acta Phytogeogr. Suec. 74 Production and growth dy namics of vascular bog plants 89

brought about reductions in both vegetative and re­ i.a. , My lia anomala and Cephalozia spp. In Dur­ productive vigour, adaptations which allow endur­ ing's (1979) system of life history traits ('life strate­ ance of continuously unproductive environments. gies' sensu During) in mosses these plants may fit The third (R-selection) is associated with a short life­ among the 'perennial shuttle species', although, as span and with high seed production and has evolved pointed out by During, the distinction between them in severely disturbed but potentially productive en­ and the 'perennial stayers' is not clear. The Sp hag­ vironments." (Grime, op. cit.) num spp. belong to the latter group. It may also hap­ It is obvious that bog plants possess several of the pen that the liverworts actively spread and kill the characteristics of Grime's S-selected species: they Sp hagnum. This is more evident among the lichens tolerate suboptimal amounts of nutrients; leaves are Cladina spp. and lcmadophila ericetorum and often small or leathery; the lifespan of a genet is among certain algae. long; leaves are often overwintering; flowering is in­ termittent; small amounts of photosynthates are al­ located to seed production; propagation is by vege­ Age structure of modules tative growth. Again it must be emphasized that all bog plants also occur in other habitats, that ombro­ Selection takes place on the genet level but I have trophic bogs were scarce or non-existent during long studied ramets. Schmid (1984), using the concepts

periods of the Pleistocene, and that the present-day r- and K-selection, extended the use of these terms properties of the plants have been developed in to modules of clonal plants. He carefully stated that other environments, at least as regards morphologi­ when used on the module level these terms were only cal adaptations. However, it is also clear that the 'labels' for 'rapidly developing, early reproducing' ombrotrophic bog is an environment where these and 'slowly developing, late reproducing'. properties are very suitable. I would feel somewhat uneasy if I had to use the I wrote earlier in this chapter, in agreement with word 'x-selection' together with the reservation that Grime, that the ability to survive with a minimum it does not imply selection. It seems that these terms of production probably has a positive value on bogs. are sometimes used in this deformed sense, even When this is coupled to high ability to economize the when real genets are discussed. I think it is urgent limited resources, such a plant is likely to be success­ to maintain the difference between ''the behaviour ful. of the organism as explained in terms of its present Still, there are of course interactions between properties and the explanation of how it comes to plants also in unproductive habitats. The most evi­ possess such properties" (Harper 1982). dent of these in our case, as has been repeatedly dis­ The approach of Schmid (1984) is nevertheless cussed, is the interactions between the sphagna of useful. The timespan of my investigation was too the bottom layer and the field layer species. It must short to obtain meaningful information about the be remembered that these interactions are not only lifespan of the ramets of most of the species. In negative to the vascular plants. The presence of many cases it is also not very useful to estimate the sphagna is a prerequisite for the very existence of age structure of existing ramets because of the con­ the bog. tinuous 'juvenilisation' through overgrowth. In Disturbances do also occur. Die-backs may be other cases it was not technically possible. In a few caused for instance by abnormous water levels. It is cases the lifespan is obvious: when the species over­ important to note that a disturbed spot on a bog winters belowground. This is the case in Drosera hardly ever creates possibilities for new sp ecies out­ spp., Rhynchospora alba, Rubus chamaemorus, side the clearly defined group of 'facultative bog Scheuchzeria palustris (except the base of the plants' to become established-not even to appear youngest leaf) and Trichophorum caespitosum. R. as ephemeral seedlings. Among mosses and lichens alba is the only species that overwinters as bulbs some of these bog plants mainly occur on hum­ (sometimes detached). The others have overwinter­ mocks without Sp hagnum growth, i.e. where the ing rhizomes. peatmoss has died. Such microsites may be termed Age determination of dwarf shrubs is possible disturbed and species commonly found there are, through ring counts but this was not attempted. The

Acta Phytogeogr. Suec. 74 90 lngvar Backeus age of Vaccinium uliginosum was, however, easily other species, i.a. Ranunculus repens (Lovett Doust determined by following the shoot system back­ 1981 b). "This pattern of development is similar to wards. that of animals with extended parental care. It is It may be possible to determine the age of therefore not surprising that survival curves for ra­ Scheuchzeria shoots with the help of leaf remains mets and leaves and for animals with extended pa­ but neither was this attempted. A similar approach rental care should have similar shapes" (Fetcher & to Eriophorum vaginatum shoots was presented un­ Shaver 1983). der that species. Evergreen shrubs were found to shed very few Pearl Miner ( 193 5) distinguished three basic leaves in winter when conditions were harsh. All & types of survivorship curves. These were adapted by leaves were shed in summer. The reason may simply Deevey (1947) and are often called 'Deevey curves' be that leaf shedding is an active process. In Andro­ of types I-III, although Deevey explicitly quoted meda polifolia the shedding of one-year-old leaves the original authors. The first type implies that most started in July (Table 7). In Empetrum nigrum it individuals die at a high age. In type 11 there is equal took place from June to August (Fig. 15). These re­ risk of death at all ages and in type Ill the death risk sults can be compared to the seasonal changes in the is highest among young individuals. death risk of ramets of Ranunculus spp. (Sarukhan Figure 22 which shows the age structure of E. va­ Harper 1973), of Carex arenaria (Noble et al. & ginatum shoots, also illustrates the survivorship 1979) and several other species described in the lit­ curves, if it is assumed that the age structure is stable erature, where the greatest death risk was shown to over the years. The curves are similar to curve type be more or less synchronous with the highest 'birth

11 with a tendency towards type I. Survivorship rate' for ramets. curves of individuals of other species would prob­ ably give similar results. This has been shown for ra­ mets in other species (Bernard 1976, Noble et al . Interdependence of ramets 1979). Curves of type Ill are not likely to occur in this environment where seedlings do not play a sig­ Throughout this treatise ramets have been termed nificant role. The number of new ramets is limited 'individuals'. The operational definition of an indi­ and they must have a good chance to survive if the vidual has been the unit obtained when a plant is cut species is to keep its position within the society. at ground level or at the first adventitious root. A On the other hand, there are not many individuals crucial question is, however, which is the functional that attain a high age. The interactions with the bot­ individual: the ramet or a group of ramets or the tom layer plants mean a constant death risk that genet (cf. Hartnett Bazzaz 1983).If ramets are in­ & should cause a survivorship curve similar to those tegrated it would mean that 'individuals' can sur­ found in E. vaginatum. vive outside the normal range of the species. This The survivorship of leaves has been discussed especially applies to plants with a wandering propa­ above for the evergreen species (Tables 7 and 14, gation like Rubus chamaemorus. Ramets of Betula Fig. 15). In 'deciduous' species where leaves are de­ nana in lawns usually grow near a hummock and veloped in spring and die in autumn, their survivor­ usually seem to be connected with other ramets on ship curves are, of course, of type I. Also the leaves this hummock. The same often applies to lawn colo­ of the investigated evergreen species follow similar nists of Calluna vulgaris and Empetrum nigrum. curves. The evergreen dwarf shrubs have a very low Some kind of integration therefore probably exists. mortality during the winter, which contrasts with This would mean that the performance of a ram et Karlsson's (1982) findings in Vaccinium vitis-idaea. of a clonal plant would be partly due to environmen­ In E. vaginatum, Scheuchzeria and, to some de­ tal conditions at some distance from this ramet it­ gree, R. alba, the leaves both develop and die succes­ self. One consequence, especially evident in R. cha­ sively during the active growth period, but also in maemorus, is that the same genet can develop inter­ these species leaves of a certain generation have a connected shoots in two or more plant communities survivorship curve of type I (Tables 14 and 19). on the bog. When a genet crosses the limit between Similar results have been obtained for leaves of a hummock and a lawn the somewhat disturbing si-

Acta Phytogeogr. Suec. 74 Production and growth dy namics of vascular bog plants 91

tuation arises that the same genet occurs in two com­ lations were not considered.) But variations in any munities which Central European phytosociologists of the studied properties of a species do not neces­ even consider as different classes. Furthermore, Du sarily follow phytosociological limits. A proper Rietz ( 1954) claimed that one and the same Eriopho­ study of the population ecology of a particular spe­ rum vaginatum tussock could survive all stages in cies should try to detect variation within the whole the supposed 'regeneration' of bogs (von Post plant population of the site. Such variation might & Sernander 191 0). be caused by other factors than species composi­ How ramets of a bog species depend on each other tion, e.g. rate of moss overgrowth or degree of shad­ would be an interesting field for further studies. ing. At the same time it was necessary in my investiga­ tion to divide the site in the same way for all species Concluding remarks and in my case the phytosociological limits were not only the easiest to adopt but probably also the most The basis for this work, as described in the introduc­ appropriate ones. The floristic limit between hum­ tion, has been that synecological results can be ob­ mocks and lawns corresponds to an abrupt environ­ tained as the sum of the 'ecologies' of all popula­ mental limit, the upper limit of inundation, and tions of species of the sites and their interactions (cf. comparisons between hummocks and lawns have Harper 1978). It is, of course, the populations on the been useful throughout my work. studied site only that are considered. Ecological interrelations over the border are, The study site was divided according to phyto­ however, conspicuous and the practise among phy­ sociological units. When a species occurred in two tosociologists to put the two communities into dif­ or three of these units it was treated as two or three ferent classes certainly does not correspond to lack statistical populations. (Genetically different popu- of ecological interdependence.

ACKNOWLEDGMENTS

Prof. Hugo Sjors and Dr. Hakan Hytteborn have been my supervisors during my post­ graduate studies and their help has been of a very great value, in particular their numer­ ous valuable comments on the manuscript. The head of the Institute of Ecological Botany in Uppsala, Prof. Eddy van der Maarel, also has critically read the manuscript. I want to thank warmly these persons as well as all other collegues at our institute for their cooperation and interest in my work. I am also extremely grateful to several other persons who have contributed in different ways: Mr. Villy Jungskar introduced me into the mysteries of computers, Mrs. Agneta Nordgren drew the figures, Mr. Folke Hellstrom did photographic work and Dr. Kuno Thomasson revised the reference list. Dr. Erik Sjogren and Mrs. Gunnel Sjors made a thorough editorial scrutiny of the manuscript and Mr. Nigel Rollison helped me with the linguistic revision. The staff of the university library helped in tracing numerous use­ ful references in different libraries. Mrs. Rut Persson, Abborrberg in Grangarde was my host during the field work. Financial support from C.F. Liljewalch's foundation, Anna and Gunnar Vidfelt's fund for biological research, Sernander's research fund, K.O.E. Stenstrom's foundation and Uppsala University is gratefully acknowledged.

Institute of Ecological Botany, Uppsala University January 1985 Ingvar Backeus

Acta Phytogeogr. Suec. 74 References

Allen , S.E. 1964. Chemical aspects of heather burning. - the net annual aerial production of Calluna vulgaris 1. appl. Ecol. 1: 347-367 . (L.) Hull, in northern England. - Oikos 17: Andreev, V.N. 1966. AH.upeea, B.H. 1966. Oco6eHHOCTH 272-275. 30HaJihHOfOpacnpe.ueJieHH� Ha ,ll3eMHOH ij>HTOMaCCbl Bergsten, F. 1954. Nederborden i Sverige. Medelvarden Ha BOCTOliHOeaponeiicKoM ceaepe. (Summary: Speci­ 1921-1950. (English summary.) - Meddn SMHI, fic features of the zonal distribution of the superterra­ ser. C 5: 1-21. nean mass of vegetation in the northern regions of East Bernard, 1 .M. 1976. The life history and population dy­ Carex rostra fa. Europe.) - Eor. )1(. 51: 1401-1411. namics of shoots of - 1. Ecol. 64: - 1971. Methods of defining overground phytomass on 1045-1048. vast territories of the Subarctic. - Rep. Kevo subarc­ Biebl, R. 1967. Kurztag-Einfliisse auf arktische Pflanzen tic Res. Stat. 8: 3-1 1. wahrend der arktischen Langtage. - Planta 75: Andreev, V.N., Galaktionova, T.F. , Zakharova, V.I. & 77-84. Neustrueva, A. I. 1972. Methods of estimation of sea­ Bliss, L.C. 1956. A comparison of plant development in sonal changes in above-ground phytomass of herbs. - microenvironments of arctic and alpine tundras. - In: Wielgolaski, F.E. & Rosswall, T. (eds.): Tundra bi­ Ecol. Monogr. 26: 303-337. ome. Proc. IV. int. Meeting on the biological Pro­ - 1966. Plant productivity in alpine microenvironments ductivity of Tundra, Leningrad, USSR, Oct. 1971, pp. on Mt. Washington, New Hampshire. - Ibid. 36: 102-110. 125-155. Angstrom, A. 1953. Maximi- och minimitemperaturer, - 1977. General summary. Truelove Lowland ecosys­ arstider' vegetationsperioden, temp.-klimatets fOr­ tem. - In: Bliss, L.C. (ed.): Truelove Lowland, andring. (Summary: Maximum and minimum tempe­ Devon Island, Canada: A high arctic ecosystem, pp. ratures, seasons, the vegetation period, variation of 657-675. Alberta. the temperature climate.) - Atlas_o ver Sverige, sheet Boatman, D. 1. 1977. Observations on the growth of 27-28. Sp hagnum cuspidatum in a bog pool on the Silver Arnborg, T. 1943. Granberget. En vaxtbiologisk under­ Flowe National Nature Reserve. - 1. Ecol. 65: sokning av ett sydlapplandskt granskogsomrade med 119-126. sarskild hansyn till skogstyper och foryngring. (Zu­ Boatman, D.1. & Tomlinson, R.W. 1977. The Silver sammenfassung: Granberget. Eine pflanzenbiololgi­ Flowe. II. Features of the vegetation and stratigraphy sche Untersuchung eines siidlapplandischen Fichten­ of Brishie Bog, and their bearing on pool formation. waldgebietes unter besonderer Beriicksichtigung von - Ibid. 65: 531 -546. Waldtypen und Verjiingung.) - Norrlandskt Hand­ Braid, K.W. & Tervet, I.W. 1937. Certain botanical bib!. 14: 1-282. aspects of the dying-out of heather. - Scott. 1. Agric. Aulak, W. 1970. Studies on herb layer production in the 20: 365-372. Circaeo-Alnetum Oberd. 1953 association. - Ekol. Brechtl, 1. & Kubicek, F. 1968. Prispevok k meraniu pri­ pol. 18: 411-427. marnej produkcie bylinnej vrstvy lesnych spolocens­ Backeus, I. 1972. Bog vegetation re-mapped after sixty tiev. (Zusammenfassung: Beitrag zur Messung der pri­ years. Studies on Skagershultamossen, Central Swe­ maren Produktivitat der Krauterpflanzenschicht von den. - Oikos 23: 384-393. W aldgesellschaften.) Biol6gia Bratisl. 23: - 1984. Myrar i Orebro lan. (Summary: Mires in Orebro 305-3 16. county, Central Sweden.) - Svensk bot. Tidskr. 78: Cajander, A.K. 1913. Studien iiber die Moore Finnlands. 21-44. -Acta for. fenn. 2 (3): 1-208. Barclay-Estrup, P. 1970. The description and interpreta­ Chapin, F.S., Cleve, K. van & Chapin, M.C. 1979. Soil tion of cyclical processes in a heath community. Il. temperature and nutrient cycling in the tussock growth Changes in biomass and shoot production during the form of Eriophorum vaginatum. - 1. Ecol. 67: Cal/una cycle. - 1. Ecol. 58: 243-249. 169-189. Bell, 1.N.B. & Tallis, 1.H. 1973. Biological Flora of the Chapin, F.S., 1ohnson, D.A. & McKendrick, 1.D. 1980. British Isles. Empetrum nigrum L. - Ibid. 61: Seasonal movement of nutrients in plants of differing 289-305. growth form in an Alaskan tundra ecosystem: implica­ Bellamy, D.1. & Holland, P.1. 1966. Determination of tions for herb ivory. - Ibid. 68: 189-209.

Acta Phytogeogr. Suec. 74 Production and growth dy namics of vascular bog plants 93

Chapman, S.B. 1967. Nutrient budgets for a dry heath Stigsbo Rodmosse, die letzten lebenden Hochmoore ecosystem in the south of England. - Ibid. 55: der Gegend von Upsala. - Svenska vaxtsoc. Sallsk. 677-689. Handl. 3: 1-22. Chapman, S.B., Hibble, 1. & Rafarel, C.R. 1975. Litter During, H.1. 1979. Life strategies of bryophytes: a pre­ accumulation under Calluna vulgaris on a lowland liminary review. - Lindbergia 5: 2-18. heathland in Britain. - Ibid. 63 : 259-271. Eber, W. 1971. The primary production ofthe ground ve­ Chepurko, N.L. 1972. The biological productivity and getation of the Luzulo-Fagetum. - Ecol. Stud. 2: the cycle of nitrogen and ash elements in the dwarf 53-56. shrub tundra ecosystems of the Khibini mountains Ericson, L. 1977. The influence of voles and lemmings on (Kola Peninsula).- In: Wielgolaski, F.E. & Rosswall, the vegetation in a coniferous forest during a 4-year T. (eds.): Tundra biome Proc. IV. int. Meeting on the period in northern Sweden. - Wahlenbergia 4: biological Productivity of Tundra, Leningrad, USSR, 1-115. Oct. 1971, pp. 236-247. Falinska, K. 1972. Fenologiczna reakcja gatunk6w na Chester, A.L. & Shaver, G.R. 1982. Reproductive effort zr6znicowanie fitosocjologiczno-ekologiczne gr:;1d6w in cotton grass tussock tundra. - Holarct. Ecol. 5: (Tilio-carpinetum) w Bialowieskim Parku Narodo­ 200-206. wym. (Summary: The phenological reaction of species Corley, M.F.V., Crundwell, A.C., Diill, R., Hill, M.O. to phytosociological-ecological differences in the & Smith, A.1.E. 1981. Mosses of Europe and the Tilio-carpineta of the Bialowieza National Park.) - Azores; an annotated list of species, with synonyms Phytocoenosis 1: 5-35. from the recent literature. - 1. Bryol. 11: 609-689. Fetcher, N. & Shaver, G.R. 1982. Growth and tillering Cormack, E. & Gimingham, C.H. 1964. Litter produc­ patterns within tussocks of Eriophorum vaginatum. tion by Calluna vulgaris (L.) Hull . - 1. Ecol. 52: - Holarct. Ecol. 5: 180-186. 285-297. Fetcher, N. & Shaver, G.R. 1983. Life histories of tillers Darwin, C. 1859. On the origin of species by means of na­ of Eriophorum vaginatum in relation to tundra dis­ tural selection. -London. turbance. - 1. Ecol. 71: 131- 147. Deevey, E.S., 1947. Life tables for natural populations of Firbas, F. 1931. Untersuchungen iiber den Wasserhaus­ animals. - Q. Rev. Bioi. 22: 283-314. halt der Hochmoorpflanzen. - Jb. wiss. Bot. 74: Dierschke, H. 1972. Zur Aufnahme und Darstellung pha­ 457-696. nologischer Erscheinungen in Pflanzengesellschaften. Flower-Ellis, J .G.K. 1971. Age structure and dynamics in - Ber. int. Symp. int. Verein. Veg-Kunde 1970: stands of bilberry ( Vaccinium myrtillus L.). - Res. 291 -304. Notes Dep. For. Ecol. and For. Soils Stockh. 9: Dieri3en, K. 1977. Klasse Oxycocco-Sphagnetea Br.-Bl. et 1-108. Tx. 43. - In: Oberdorfer, E. (ed.): Siiddeutsche - 1973. Growth and morphology in the evergreen dwarf Pflanzengesellschaften 1: 273-292. shrubs Empetrum hermaphroditum and Andromeda Dieri3en, K. & B. 1982. Kiefernreiche Phytoconosen oli­ polifo lia at Stordalen. - In: Bliss, L.C. & Wielgolas­ gotropher Moore im mittleren und nordwestlichen Eu­ ki, F.E. (eds.): Primary production and production ropa - iiberlegungen zur Problematik ihrer Zuord­ processes, tundra biome. Proc. of the Conf., Dublin, nung zu hoheren synsystematischen Einheiten.- Ber. Ireland, April 1973, 123-135. int. Symp. int. Verein. Veg-Kunde 1981: 299-331. - 1975. Growth in populations ofAn dromeda polifo lia Du Rietz, G.E. 1933. De norrlandska myrarnas vaxt­ on a subarctic mire. - Ecol. Stud. 16: 129-134. varld. - Sver. Nat. Arsb. 1933: 56-68. - 1980a. Diurnal dry weight variation and dry matter al­ - 1949. Huvudenheter och huvudgranser i svensk myr­ location of some tundra plants. 1. Andromeda polifo­ vegetation. (Summary: Main units and main limits in lia L. - Ecol. Bull. (Stockh.) 30: 139-162. Swedish mire vegetation.) - Svensk bot. Tidskr.43: - 1980b. Diurnal dry weight variation and dry matter al­ 274-309. location of some tundra plants. 2. Rubus chamaemo­ - 1950a. Phytogeographical mire excursion to the rus L. - Ibid. 30: 163-179. Billingen-Falbygden district in Vastergotland (south­ Forrest, G.I. 1971. Structure and production of North western Sweden). - 7th int. Bot. Congr. Stockh., Pennine blanket bog vegetation. - J. Ecol. 59: Exc. guides, Sect. PHG, A II b 1: 1-54. 453-479. - 1950b. Phytogeographical mire excursion to north­ Forrest, G.l. & Smith, R.A.H. 1975. The productivity of eastern Smaland and Ostergotland. - Ibid. A II b 2: a range of blanket bog vegetation types in the northern 1-22. Pennines. - Ibid. 63 : 173-202. - 1950c. Phytogeographical excursion to the Ryggmos­ Fransson, S. 1972. Myrvegetation i sydvastra Varmland. sen mire near Uppsala. - Ibid. A II b 3: 1-24. (Summary: Mire vegetation in south-western Varm­ - 1954. Die Mineralbodenwasserzeigergrenze als land, Sweden.) - Acta phytogeogr. suec. 57: 1-133. Grundlage einer natiirlichen Zweigliederung der nord­ Gimingham, C.H. 1960. Biological flora of the British und mitteleuropaischen Moore. - Vegetatio 5-6: Isles . Calluna vulgaris (L.) Hull. - J. Ecol. 48: 571-585. 455-483 . Du Rietz, G.E. & Nannfeldt, J.A. 1925. Ryggmossen und 1972. Ecology of heathlands. - London.

Acta Phytogeogr. Suec. 74 94 Ingvar Backeus

Goodman, G.T. & Perkins, D.F. 1959. Mineral uptake Harper, J.L. 1977. Population biology of plants. - Lon­ and retention in cotton-grass (Eriophorum vaginatum don. L.). - Nature, Lond. 184: 467-468. - 1978. The demography of plants with clonal growth. Goodman, G.T. & Perkins, D.F. 1968. The role of nu­ - Verh. K. Akad. Wet., Afd. Natuurk., 2de Reeks 70: trients in Eriophorum communities. Ill. Growth re­ 27-48. E. vagina­ sponse to added inorganic elements in two - 1982. After description. - Spec. pub I. Brit. Ecol. Soc. turn communities. - J. Ecol. 56: 667-683. 1: 11-25. Gore, A.J .P. 1961. Factors limiting plant growth on high­ Hartnett, D.C. & Bazzaz, F.A. 1983 . Physiological inte­ level blanket peat. I. Calcium and phosphate.- Ibid. gration among intraclonal ramets in Solidago cana­ 49: 399-402. densis. - Ecology 64: 779-788. Gore, A.J .P. & Olson, J .S. 1967. Preliminary models for Havas , P. & Lohi, K. 1972. Hillan [Rubus chamaemorus] accumulation of organic matter in an Eriopho­ ekologiasta. (Summary: On the ecology of the cloud­ rum/Calluna ecosystem. - Aquilo, ser. Bot. 6: berry [Rubus chamaemorus] .) - Lapin Tutkimuss. 297-3 13- Vuosik. 1972: 15-20. Grace, J. & Woolhouse, H.W. 1970. A physiological and Hobbs, R.J. & Gimingham, C.H. 1984. Studies on fire in mathematical study of the growth and productivity of Scottish heathland communities. I. Fire characteris­ a Calluna-Sphagnum community. I. Net photosynthe­ tics. - J. Ecol. 72: 223-240. sis of Calluna vulgaris (L.) Hull. - J. appl. Ecol. 7: Hopkins, D.M. & Sigafoos, R.S. 1951. Frost action and 363-381. vegetation patterns on Seward Peninsula, Alaska. A Grace, J. & Woolhouse, H.W. 1973. A physiological and study of the geomorphic significance of vegetation mathematical study of the growth and production of patterns as related to frost action at high latitudes and a Calluna-Sphagnum community. Ill. Distribution of in areas of perennially frozen ground. - Bull. U.S. photosynthate in Calluna vulgaris (L.) Hull. - Ibid. Geol. Surv. 974-C: 51-101. 10: 77-91. Huttunen, A. 1978. Hilla- ja karpalosadoista Siuruan Greig-Smith, P. 1957. Quantitative plant ecology. - alueella. (Summary: On the cloudberry and cranberry London. yields in Siurua district, N-Finland.) - Suo 29: - 1979. Pattern in vegetation.- J. Ecol. 67: 755-779. 17-21. Grime, J.P. 1979. Plant strategies and vegetation proces­ Hylander, N. 1966. Nordisk karlvaxtflora. 11. - Stock­ ses. - Chichester. holm. Grime, J .P. & Hunt, R. 1975. Relative growth-rate: its Hytteborn, H. 1975. Deciduous woodland at Andersby, range and adaptive significance in a local flora. - J. Eastern Sweden. Above-ground tree and shrub pro­ Ecol. 63: 393-422. duction. -Acta phytogeogr. suec. 61: 1-96. Grolle, R. 1976. Verzeichnis der Lebermoose Europas Jessen, K. 1913. The structure and biology of arctic und benachbarter Gebiete. - Feddes Reprium 87: flowering plants. 11. 8. Rosaceae. - Meddr Gmnland 171-279. 37: 1-126. Haag, R.W. 1974. Nutrient limitations to plant produc­ Johansson, L .-G. 1974. The distribution and fate of 14C tion in two tundra communities. - Can. J. Bot. 52: photoassimilated by plants on a subarctic mire at Stor­ 103-116. dalen. - Techn. Rep. of the Swed. Tundra Biome Hagerup, 0. 1922. Om Empetrum nigrum L. En naturhis­ Proj . 16: 165-172. torisk Studie. (Summary: On Empetrum nigrum.) ­ Johnson, D.A. & Tieszen, L.L. 1976. Aboveground bio­ Bot. Tidsskr. 37: 253-304. mass allocation, leaf growth, and photosynthesis pat­ - 1946. Studies on the Empetraceae. - Bioi. Meddr 20 terns in tundra plant forms in arctic Alaska. - Oeco­ (5): 1-49. logia 24: 159-173. Haglund, E.E. 1905. Ur de hognordiska vedvaxternas Jonasson, S. 1982. Organic matter and phytomass on ekologi. - Diss. Uppsala. three north Swedish tundra sites, and some connec­ Hamberg, H.E. 1922. Termosynkroner och termoisokro­ tions with adjacent tundra areas. - Holarct. Ecol. 5: ner pa den skandinaviska halvon. (Resume: Thermo­ 367-375. synchrones et thermoisochrones dans la peninsule Kallio, P. 1975. Kevo, Finland. - Ecol. Bull. (Stock­ scandinave.) - Meteorol. iakttagelser i Sverige, Bih. holm) 20: 193-223. 60 (1918): 1-39. Kallio, P. & Karenlampi, L. 1971. A review of the stage Hari, P., Kellomaki, S. & Vuokko, R. 1977. A dynamic reached in the Kevo IBP in 1970. - In: Heal, O.W. approach to the analysis of daily height growth of (ed.): IBP, Tundra Biome. Working Meeting on ana­ plants. - Oikos 28: 234-241. lyses of ecosystems, Kevo, Finland, Sept. 1970, pp. Hari, P. & Leikola, M. 1974. Further development of the 79-91. dynamic growth model of plant height growth. - Kallio, P. & Makinen, Y. 1978. Vascular flora of Inari Flora, Jena 163: 357-370. Lapland. 4. Betulaceae. - Rep. Kevo subarctic Res. Hari, P., Leikola, M. & Rasanen, P. 1970. A dynamic Stat. 14: 38-63. model of the daily height increment of plants. - Annls Kardell, L. & Carlsson, E. 1982. Hjortron, tranbar, bot. fenn. 7: 375-378. lingon. Forekomst och barproduktion i Sverige

Acta Phytogeogr. Suec. 74 Production and growth dynamics of vascular bog plants 95

1978-1980. (Summary: Cloudberry, cranberry, Liedenpohja, M. 1981. Avosuotyyppien kasvillisuus, kas­ lingonberry. Occurrence and production in Sweden vibiomassa ja tuotos Janakkalan Suurisuolla. (Sum­ 1978-1980.) - Rep. Sect. environm. For., Uppsala mary: Vegetation, biomass and production of fens in 25: 1-156. Suurisuo mire, Janakkala, southern Finland.) - Suo Karenlampi, L. 1973. Biomass and estimated yearly net 32: 100-103 . production of the ground vegetation at Kevo. - In: Lindholm, T. 1980. Dynamics of the height growth of the Bliss, L.C. & Wielgolaski, F.E. (eds.): Primary pro­ hummock dwarf shrubs Empetrum nigrum L. and duction and production processes, tundra biome. Calluna vulgaris (L.) Hull on a raised bog. - Annls Proc. of the Conf., Dublin, Ireland, April 1973, pp. bot. fenn. 17: 343-356. 111-114. - 1982. Growth dynamics and the effect of frost in A n­ Karlsson, S. 1982. Ecology of a deciduous and an ever­ dromeda polifo lia on a raised bog. - Ibid. 19: green dwarfshrub: Vaccinium uliginosum and Vacci­ 193-201. nium vitis-idaea in subarctic Fennoscandia. - Dept Lindholm, T. & Vasander, H. 1981. The effect of summer Plant Ecol., Lund. Diss. (Mimeogr.) frost damage on the growth and production of some Kayll, A.J. 1966. Some characteristics of heath fires in raised bog dwarf shrubs. - Ibid. 18: 155-167. North-East Scotland. - J. appl. Ecol. 3: 29-40. Lohi, K. 1974. Variation between cloudberries (Rubus Kellomaki, S., Hari, P., Vuokko, R., Vaisanen, E. & chamaemorus L.) in different habitats. - Aquilo Ser. Kanninen, M. 1977. Above ground growth rate of a Bot. 13: 1-9. dwarf shrub community. - Oikos 29: 143-149. Loveless, A.R. 1961. A nutritional interpretation of scle­ Keso, A. 1908. Ober Alter und Wachstumsverhaltnisse rophylly based on differences in the chemical composi­ der Reiser in Tavastland. - Acta Soc. Fauna Flora tion of sclerophyllous and mesophytic leaves. - Ann. fenn. 31 (1): 1-49. Bot. 25: 168-184. Kihlman, A.O. 1890. Pflanzenbiologische Studien aus - 1962. Further evidence to support a nutritional inter­ Russisch Lappland. Ein Beitrag zur Kenntnis der pretation of sclerophylly. - Ibid. 26: 551-561. regionalen Gliederung an der polaren Waldgrenze. ­ Lovett Doust, L. 1981a. Population dynamics and local Ibid. 6 (3): 1-264. specialization in a clonal perennial (Ranunculus re­ Kjelvik, S. & Wielgolaski, F.E. 1974. Biomass, nutrient pens) . I. The dynamics of ramets in contrasting habi­ content and energy of some dwarf shrubs in a Norwe­ tats. - J. Ecol. 69: 743-755. gian subalpine birch forest. - Rep. Kevo subarctic - 1981 b. Population dynamics and local specialization Res. Stat. 11: 47-5 1. in a clonal perennial (Ranunculus repens). 11. The dy­ Kolkki, 0. 1966. Taulukoita ja karttuja suomen lampo­ namics of leaves, and a reciprocal transplant-replant oloista kaudelta 1931-1960. {Tables and maps of experiment. - Ibid. 69: 757-768. temperature in Finland during 1931-1960.) - Liite Magnusson, N.H. & Lundqvist, G. 1933. Beskrivning till suomen meteorol. Vuosik. 65, la (1965). kartbladet Grangesberg. - Sver. geol. Unders. Ser. Kosonen, R. 1981. Isovarpuisen rameen kasvibiomassa ja Aa 177: 1-133. tuotos. (Summary: Plant biomass and production in Makinen, Y. &Oikarinen, H. 1974. Cultivation of cloud­ a dwarf-shrub pine bog.) - Suo 32: 95-97. berry in Fennoscandia. - Rep. Kevo subarctic Res. Kubicek, F. & Brechtl, J. 1970. Production and pheno­ Stat. 11: 90-102. logy of the herb layer in an oak-hornbeam forest. - Malme, G.O. A:n 1908. Om forgrenade arsskott hos Cal­ Biol6gia Bratisl. 25: 651 -666. luna vulgaris (L.) Salisb. (Zusammenfassung: Ober Kubicek, F. & Jurko, A. 1975. Estimation of the above­ verzweigte Jahrestriebe bei Calluna vulgaris (L.) Sa­ ground biomass of the herb layer in forest communi­ lisb.) - Svensk bot. Tidskr. 2: 85-94. ties. - Folia geobot. phytotax. 10: 113-129. Malmer, N. 1962. Studies on mire vegetation in the Ar­ Langlet, 0. 1935. Till fragan om sambandet mellan tem­ chaean area of southwestern Gotaland (South Swe­ peratur och vaxtgranser. (Zusammenfassung: Ober den). I. Vegetation and habitat conditions on the Ak­ den Zusammenhang zwischen Temperatur und Ver­ hult mire. - Op. bot. Soc. bot.Lund 7 (1): 1-322. breitungsgrenzen von Pflanzen.) - Meddn St. - 1968. Ober die Gliederung der Oxycocco-Sphagnetea Skogsf-Anst 28: 299-412. und Scheuchzerio-Caricetea fuscae. Einige Vor­ Larcher, W., Cernusca, A., Schmidt, L., Grabherr, G., schlage mit besonderer Beri.icksichtigungder Verhalt­ Notzel, E. & Smeets, N. 1975. Mt. Patscherkofel, nisse in S-Schweden. - Ber. int. Symp. int. Verein. Austria. - Ecol. Bull. (Stockholm) 20: 125-139. Veg-Kunde 1964: 293-305 . Lewis, M.C. & Callaghan, T.V. 1971. Bipolar botanical Malmer, N. & Nihlgard, B. 1980. Supply and transport project. Primary production studies on Disko Island, of mineral nutrients in a subarctic mire. - Ecol. Bull. West Greenland. - In: Heal, O.W. (ed.): Working (Stockholm) 30: 63-95. meeting on analyses of ecosystems, Kevo, Finland, Malmstrom, C. 1949. Studier over skogstyper och trad­ Sept. 1970, pp. 34-50. slagsfordelning inom Vasterbottens lan. (Zusammen­ Lid, J., Lie, 0. & L0ddes0l, A. 1961. Orienterende fors0k fassung : Studien i.iberWaldtypen und Baumartenver­ med dyrking av molter. - Meddr norske Myrselsk. teilung im Lan Vasterbotten.) - Meddn St. Skogsf­ 59: 1-26. lnst. 37 (1 1): 1-231.

Acta Phytogeogr. Suec. 74 96 Ingvar Backeus

Marks, T.C. & Taylor, K. 1972. The mineral nutrient sta­ Nordhagen, R. 1937. Studien i.iberdie monotypische Gat­ tus of Rubus chamaemorus L. in relation to burning tung Calluna Salisb. I. Ein Beitrag zur Bicornes-For­ and sheep grazing. - J. appl. Ecol. 9: 501-511. schung. - Bergens Mus. Arb., naturv. rekke 1937 (4): Mentz,, A. 1909. The structure and biology of arctic 1-55. flowering plants. I. 3. Empetraceae. Empetrum nig­ Oinonen, E. 1967. Sporal regeneration of bracken (Pteri­ rum L. - Meddr Gmnland 36: 157-167. dium aquilinum (L.) Kuhn.) in Finland in the light of Metsavainio, K. 1931. Untersuchungen i.iberdas Wurzel­ the dimensions and the age of its clones. - Acta for. system der Moorpflanzen. - Annls bot. Soc. zool.­ fenn. 83 (1): 1-96. bot. fenn. Vanamo 1 (1): 1-422. 0stgard, 0. 1964. Molteunders0kelser i Nord-Norge. Miller, G.R. 1979. Quantity and quality of the annual (Summary: Investigations on cloudberries (Rubus production of shoots and flowers by Calluna vulgaris chamaemorus L.) in North-Norway.) - Forskning og in North-East Scotland. - J. Ecol. 67: 109-129. fors0k i Landbruket 1964: 409-444. Miller, G.R. & Miles, J. 1970. Regeneration of heather Pearl, R. &Miner, J .R. 1935. Experimental studies on the (Calluna vulgaris (L.) Hull) at different ages and sea­ duration of life. XIV. The comparative mortality of sons in North-East Scotland. - J. appl. Ecol. 7: certain lower organisms.- Q. Rev. Bioi. 10: 60-79. 51-60. Pearsall, W.H. & Gorham, E. 1956. Production ecology. Miller, P.C. 1982. Environmental and vegetational vari­ I. Standing crops of natural vegetation. - Oikos 7: ation across a snow accumulation area in montane 193-201. tundra in Central Alaska. - Holarct. Ecol. 5: 85-98. Persson, H. 1975a. Deciduous woodland at Andersby, Miller, P.C., Mangan, R. &Kummerow, J. 1982. Vertical eastern Sweden: field-layer and below-ground produc­ distribution of organic matter in eight vegetation types tion. - Acta phytogeogr. suec. 62: 1-71. near Eagle Summit, Alaska. - Ibid. 5: 117-124. - 1975b. Dry matter production of dwarf shrubs, Milner, C. & Hughes, R.E. 1968. Methods for the mea­ mosses and lichens in some sects pine stands at Ivan­ surement of the primary production of grassland. - tjarnsheden, Central Sweden. - Techn. Rep. Swed. IBP Handbook 6: 1-42. coniferous Proj. 2: 1-25. Monk, C.D. 1966. An ecological significance of ever­ - 1978. Root dynamics in a young sects pine stand in greenness. -Ecology 47: 504-505. Central Sweden. - Oikos 30: 508�519. Moore, D.M. 1982. Flora Europaea check-list and chro­ - 1979. Fine-root production, mortality and decompo­ mosome index. - Cambridge. sition in forest ecosystems. - Vegetatio 41: 101-109. Mork, E. 1946. Om skogbunnens lyngvegetasjon. (Sum­ - 1980. Structural properties of the field and bottom mary: On the dwarf shrub vegetation on forest layers at Ivantjarnsheden.- Ecol. Bull. (Stockholm) ground.) - Meddr norske Skogfors0ksv. 33: 32: 153-163. 269-356. Perttu, K., Odin, H. & Engsjo, T. 1978a. Bearbetade kli­ Moszynska, B. 1970. Estimation of the green top produc­ matdata fran SMHI-stationerna i Sverige. 1. Vegeta­ tion of the herb layer in a bog pinewood Vaccinia tionsperioder, temperatursummor och vaxtenheter uliginosi-Pinetum. - Ekol. pol. 18: 779-803. for enstaka ar perioden 1961-1976. - Res. Notes - 1973. Methods for assessing production of the upper Dept. Reforestation, Stockholm 100: 1-344. parts of shrubs and certain perennial plants. - Ibid. Perttu, K., Odin, H. & Engsjo, T. 1978b. Bearbetade kli­ 21: 359-367 . matdata fran SMHI-stationerna i Sverige. 2. Vegeta­ Mi.iller-Stoll, W.R. 1947. Der Einfluss der Ernahrung auf tionsperioder, temperatursummor och vaxtenheter die Xeromorphie der Hochmoorpflanzen. - Planta som medelvarden med standardavvikelser for perio­ 35: 225-251. den 1961-1976.- Ibid. 101: 1-115. Murray, C. & Miller, P.C. 1982. Phenological observa­ Perttula, U. 1949. Ober die Phanologie und Vermeh­ tions of major growth forms and species in montane rungsokologie einiger ostlichen Pflanzenarten in Juk­ and Eriophorum vagina turntussock tundra in Central sowo si.idlich des Swir. I. - Oikos 1: 83-1 13. Alaska. - Holarct. Ecol. 5: 109-116. Plewczynska, U. 1970., Herb layer production and plant Nannfeldt, J.A. 1981. Exobasidium, a taxonomic re­ fall in the association Pino-Quercetum, Kozlowska assessment applied to the European species.- Symb. 1925 in the Pisz forest. - Ekol. pol. 18: 757-778. bot. upsal. 23 (2) : 1-72. Porsild, A.E. 1938. The cranberry in Canada. - Can. Neuhausl, R. 1972. Subkontinentale Hochmoore und ihre Fld. Nat. 52: 116-117. Vegetation. - Studie CSAV 13: 1-121. Porsild, M.P. 1930. Stray contributions to the flora of Newbould, P.J. 1967. Methods for estimating the prim­ Greenland 1-V. - Meddr Gmnland 77: 1-44. ary production of forests. - IBP Handbook 2: 1-62. Post, L. von & Sernander, R. 1910. Pflanzen­ Nitschke, T. 1860. Wachstumsverhaltnisse des rundblatt­ physiognomische Studien auf Torfmooren in Narke. rigen Sonnenthaues. - Bot. Ztg 18 (7): 57-61. - Livretguide des exc. en Suede du Xle Congr. geol. Noble, J .C., Bell, A.D. &Harper, J.L. 1979. The popula­ int. 14: 1-48. tion biology of plants with clonal growth. I. The mor­ Puszkar, L., Traczyk, T. & W6jcik, Z. 1972. Primary phology and structural demography of Carex arena­ production of the herb layer and plant fall in the Vacci­ ria. - J. Ecol. 67: 983-1008. nia myrtilli-Pinetum forest association in the Pisz fo-

Acta Phytogeogr. Suec. 74 Production and growth dy namics of vascular bog plants 97

rest (North-East Poland).- Ekol. pol. 20: 253-285. skyddsvafnader. - Bih. K. svenska Vetensk-Akad. Rauh, W. 1938. Ober die Verzweigung auslauferbilden­ Handl. 19 1II (4) : 1::-87. der Straucher mit besonderer Berucksichtigung ihrer Serebryakov, I.G. 1962. Cepe6pHKOB, M.r. 1962: Beziehungen zu den Stauden. - Hercynia 1: 3KonorHqecKaH MoponorHH pacTeHHH. - MocKBa. 187-231. Sernander, R. 1901. Den skandinaviska vegetationens Raunkiaer, C. 1895-1899. De danske Blomsterplanters spridningsbiololgi. (Resume: Zur Verbreitungsbiolo­ Naturhistorie. 1. Enkimbladede. - Kj0benhavn. gie der skandinavischen Pflanzenwelt.) - Uppsala. Rawes, M. & Welch, D. 1969. Upland productivity of ve­ Shaver, G.R. & Cutler, J.C. 1979. The vertical distribu­ getation and sheep at Moor House National Nature tion of live vascular phytomass in cottongrass tussock Reserve, Westmorland, England. - Oikos, suppl. 11: tundra. - Arct. alp. Res. 11: 335-342. 1-72. Simonis, W. 1948. C02-Assimilation und Xeromorphie Reader, R.J. & Stewart, J.M. 1972. The relationship be­ von Hochmoorpflanzen in Abhangigkeit vom Wasser­ tween net primary production and accumulation for und Stickstoffgehalt des Bodens. - Bioi. Zbl. 67: a peatland in southeastern Manitoba. - Ecology 53: 77-83 . 1024-1037. Sims, R.A. & Stewart, J.M. 1981. Aerial biomass distri­ Resvoll, T.R. 1925. Rubus chamaemorus L. Die geo­ bution in an undisturbed and disturbed subarctic bog. graphische Verbreitung der Pflanze und ihre Verbrei­ - Can. J. Bot. 59: 782-786. tungsmittel. - Veroff. geobot. Inst. Zurich 3: Sjors, H. 1948. Myrvegetation i Bergslagen. (Summary: 224-252. Mire vegetation in Bergslagen, Sweden.) - Acta phy­ - 1929. Rubus chamaemorus L. A morphological - bio­ togeogr. suec. 21: 1-299. logical study. - Nyt Mag. Naturvid. 67: 55-129. - 1950. Regional studies in North Swedish mire vegeta­ Robertson, K.P. & Woolhouse, H.W. 1984a. Studies of tion.- Bot. Notiser 1950: 173-222. the seasonal course of carbon uptake of Eriophorum - 1963. Bogs and fens on Attawapiskat River, northern vagina tu m in a moorland habitat. I. Leaf production Ontario. - Bull. natn. Mus. Can. 186: 45-133. and senescence. -J. Ecol. 72: 423-435. SMHI (Swedish meteorological and hydrological Insti­ Robertson, K.P. & Woolhouse, H.W. 1984b. Studies of tute) 1956- 1983. Nederborden i Sverige. (Precipita­ the seasonal course of carbon uptake of Eriophorum tion in Sweden).- Arsb. Sver. meteorol. hydrol. Inst. vaginatum in a moorland habitat. II. The seasonal 37 (1955)-63 (1981), 2.1. course of photosynthesis. - Ibid. 72: 686-700. - 1962-1982. Meteorologiska iakttagelser i Sverige. Robertson, R.A. & Davies, G .E. 1965. Quantities of plant (Meteorological observations in Sweden.) - Ibid. 37 nutrients in heather ecosystems. - J. appl. Ecol. 2: (1955)-63 (1981), 2.2. 211-219. Sonesson, M. & Bergman, H. 1972. Phytomass changes Rosswall, T., Flower-Ellis, J.G.K., Johansson, L.G., between two samplings. Stordalen 1970. - Techn. Jonsson, S., Ryden, B.E. & Sonesson, M. 1975. Stor­ Rep. Swed. Tundra Biome Proj. 2: 1-23. dalen (Abisko), Sweden. - Ecol. Bull. (Stockholm) Sonesson, M. & Bergman, H. 1980. Area-harvesting as a 20: 265-294. method of estimating phytomass changes in a tundra Saeb0, S. 1968. The autecology of Rubus chamaemorus mire. - Ecol. Bull. (Stockholm) 30: 127-137. L. I. Phosphorus economy of Rubus chamaemorus in Stavset, K. 1981. Avlingskontroll av molter. Registre­ an ombrotrophic mire. - Meld. Norges Landbruks­ ringer, ara 1971-1980 i And0y. - Jord og Myr 5: h0gsk. 47 (1): 1-67 . 60-65. Samuelsson, G. 1922. Zur Kenntnis der Schweizer Flora. Stew art, J .M. & Reader, R. 1972. Some considerations of - Vjschr. naturf. Ges. Zurich 67 : 224-267. production: accumulation dynamics in organic ter­ Santesson, R. 1984. The lichens of Sweden and Norway. rain. - Proc. 4th int. peat congr. 1: 247-258. - Stockholm & Uppsala. Stoner, W.A., Miller, P. & Miller, P.C. 1982. Seasonal Sarukhan, J. & Harper, J. L. 1973. Studies on plant de­ dynamics and standing crops of biomass and nutrients mography: Ranunculus repens L., R. bulbosus L. and in a subarctic tundra vegetation. - Holarct. Ecol. 5: R. acris L. I. Population flux and survivorship. - J. 172-179. Ecol. 61: 675-716. Supan, A. 1887. Die mittlere Dauer der Haupt­ Sarvas, R. 1967. The annual period of development of fo­ Warmeperioden in Europa. - Petermanns Mitt. 33: rest trees. - Sber. finn. Akad. Wiss. 1965: 21 1-23 1. 165-172. Schamurin, V.F., Polozova, T. G. & Khodachek, E.A. Swales, D .E. 197 5. An unusual habitat for Drosera rotun­ 1972. Plant biomass of main plant communities at the difolia L., its over-wintering state, and vegetative re­ Tareya station (Taimyr). - In: Wielgolaski, F.E. & production. - Can. Fld Nat. 89: 143-147. Rosswall, T. (eds.): Tundra biome. Proc. IV. int. Tamm, C.O. 1954. Some observations on the nutrient meeting on the biological productivity of tundra, Le­ turn-over in a bog community dominated by Eriopho­ ningrad, USSR, Oct. 1971, pp. 163-181. rum vaginatum L. - Oikos 5: 189-194. Schmid, B. 1984. Life histories in clonal plants ofthe Ca­ - 1956. Further observations on the survival and flower­ rex flava group. - J. Ecol. 72: 93-114. ing of some perennial herbs. I. - Ibid. 7:273-292. Segerstedt, P. 1894. Studier ofver buskartade stammars Tamm, O.F.S. 1959. Studier over klimatets humiditet i

Acta Phytogeogr. Suec. 74 98 lngvar Backeus

Sverige. (Studien iiber die HumidiHit des Klimas in Warenberg, K. 1982. Reindeer forage plants in the early Schweden.) - K. Skogshogsk. Skr. 32: 1-48. grazing season. Growth and nutritional content in re­ Taylor, K. 1971. Biological flora of the British Isles. Ru­ lation to climatic conditions. - Acta phytogeogr. bus chamaemorus L. - J. Ecol. 59: 293-306. suec. 70: 1-71. Traczyk, H. 1971. Relation between productivity and Warming, E. 1884. Om Skudbygning, Overvintring og structure of the herb layer in associations on ''The Foryngelse. - Naturhist. For. Festskr. Kj 0benhavn. Wild Apple-tree Island" (Masurian Lake District).­ - 1908. The structure and biology of arctic flowering Ekol. pol. 19: 333-363. plants. 1. Ericineae (Ericaceae, Pirolaceae). 1. Mor­ Traczyk, T. 1967a. Studies on herb layer production esti­ phology and biology. - Meddr Gmnland 36: 1-71. mate and the size of plant fall. - Ibid. Ser. A 15: Watt, A.S. 1947 . Contributions to the ecology ofbracken 837-867. (Pteridium aquilinum). IV. The structure of the com­ - 1967b. Propozycja nowego sposobu oceny produkcji munity. - New Phytol. 46: 97-121. runa. (Summary: A proposed new way of estimating - 1955. Bracken versus heather, a study in plant socio­ the production of the forest herb layer.) - Ibid. Ser. logy.- J. Ecol. 43 : 490-506. B 13: 241 -247. Weber, C.A. 1902. Uber die Vegetation und Entstehung Traczyk, T. & Traczyk, H. 1977. Structural characteris­ des Hochmoors von Augstumal im Memeldelta mit tics of herb layer and its production in more important vergleichenden Ausblicken auf andere Hochmoore forest communities of Poland.- Ibid. 25: 359-378. der Erde. - Berlin. Traczyk, T., Traczyk, H. & Moszynska, B. 1973. Herb Wein, R.W. & Bliss, L.C. 1973. Changes in arctic Erio­ layer production of two pinewood communities in the phorum tussock communities following fire. - Eco­ Kampinos national park. - Ibid. 21: 37-55. logy 54: 845-852. Tuhkanen, S. 1980. Climatic parameters and indices in Wein, R.W. & Bliss, L.C. 1974. Primary production in plant geography. - Acta phytogeogr. suec. 67: arctic cottongrass tussock tundra communities. - 1-105. Arct. alp. Res. 6: 261-274. - 1984. A circumboreal system of climatic-phytogeo­ Westhoff, V. & den Held, A.J. 1969. Plantengemeen­ graphical regions. -Acta bot. fenn. 127: 1-50. schappen in Nederland. - Zutphen. Tyler, G., Gullstrand, C., Holmquist, K.-A. & Kjell­ White, J. 1979. The plant as ametapopulation. - A. Rev. strand, A.-M . 1973. Primary production and distribu­ Ecol. Syst. 10: 109-145. tion of organic matter and metal elements in two heath White, J. & Harper, J.L. 1970. Correlated changes in ecosystems. - J. Ecol. 61: 251 -268. plant size and number in plant populations. - J. Ecol. Ungerson, J. & Scherdin, G. 1962. Untersuchungen iiber 58: 467-485. den Tagesverlauf der Photosynthese und der Atmung Wielgolaski, F.E. 1966: The influence of air temperature unter natiirlichen Bedingungen in der Subarktis on plant growth and dev�lopment during the period of (Finnisch-Lappland). - Annls bot. Soc. zool. bot. maximal stem elongation. - Oikos 17: 121-141. fenn. 'Vanamo' 32 (7): 1-22. Wielgolaski, F.E. & Kjelvik, S. 1973 . Production of Vasander, H. 1981. Keidasrameen kasvibiomassa ja tuo­ plants (vascular plants and cryptogams) in alpine tos. (Summary: Plant biomass and production in an tundra, Hardangervidda. - In: Bliss, L.C. & Wielgo­ ombrotrophic raised bog.) - Suo 32: 91-94. laski, F.E. (eds.): Primary production and production Vassiljevskaja, V.D., lvanov, V.V., Bogatyrev, L.G., processes, tundra biome. Proc. Conf. , Dublin, Ire­ Pospelova, E.B., Shalaeva, N.M. & Grishina, L.A. land, April 1973, pp. 75-86. 1975. Agapa, USSR. - Ecol. Bull. (Stockholm) 20: Williams, C.B. 1964. Patterns in the balance of nature. 141-158. - London & New York. Veijalainen, H. 1976. Effect of forestry on the yields of Yelina, G.A. 1974. Biological productivity of Karelian wild berries and edible fungi. - Ibid. 21: 63-65. peatlands. - Proc. int. Symp. on forest drainage, Vuokko, R., Kellomaki, S. & Hari, P. 1977. The inherent Sept. 1974, Jyvaskyla - Oulu , Finland, pp. 71-79. growth rhythm and its effects on the daily height incre­ Zalenskij, O.V., Shvetsova, V.M. & Voznessenskij , V.L. ment of plants. - Oikos 29: 137-142. 1972. Photosynthesis in some plants of western Tai­ Waldheim, S. 1944. Die Torfmoosvegetation der Provinz myr. - In: Wielgolaski, F.E. & Rosswall, T. (eds.): Narke. - Lunds Univ. Arsskr. N.F. avd. 2 40 (6): Proc. IV. int. Meeting of the biological Productivity 1�91. of Tundra, Leningrad, USSR, Oct. 1971, pp. Wallen, B. 1980. Structure and dymanics of Calluna vul­ 182-186. garis on sand dunes in South Sweden. - Oikos 35: Zumer, M. 1969. Vekstrytme hos noen skogstraer i for­ 20-30. skjellige h0ydelag. (Summary: Growth rhythm of Waiter, H. & Lieth, H. 1960. Klimadiagramm-Weltatlas. some forest trees at different altitudes.) - Meldr Nor­ 1. Lieferung. - Jena. ges Landbruksh0gsk. 48 (5): 1-31.

Acta Phytogeogr. Suec. 74 99

SVENSKA V AXTGEOGRAFISKA SALLSKAPET SOCIETAS PH YTOGEOGRAPHICA SUECANA Adress: Vaxtbiologiska institutionen, Box 559, S-75 1 22 Uppsala, Sweden

Sallskapet har till andamal att vacka och underhalla intresse The object of the Society is to promote investigation in flora fOr vaxtgeografien i vidstracktaste mening, att framja utfors­ and vegetation, their history and their ecological background. kande av flora och vegetation i Sverige och andra lander och Through publication of monographs, and other activities, the att havda geobotanikens praktiska och vetenskapliga betydel­ Society tries to stimulate geobotanical research and its appli­ se . cation to practical and scientific problems. Membership is Sallskapet anordnar sammankomster och exkursioner samt open to all who have a personal interest in the advancement of utger tva publikationsserier. Medlemskap kan erhallas efter phytogeography. anmalan hos sekreteraren. Foreningar, bibliotek, laroanstalter Individual members and subscribers (societies, institutes, och andra institutioner kan inga som abonnenter. Arsavgift 50 libraries, etc.) receive the Acta Phytogeographica Suecica for kr (35 for studerande). annual dues of 50 Skr plus postage. There are additional fees Sallskapet utger arligen Acta Phytogeographica Suecica . in years when more than one volume are issued. For member­ Medlemmar och abonnenter erhaller arets Acta mot postfor­ ship please apply to the Secretary. skott pa arsavgiftenjamte porto oc h expeditionskostnader. The Society al so issues Viixteko/ogiska studier, which ap­ Vissa ar utges extraband av Acta, som erhalls mot en till­ pear irregularly and are available upon request or standing laggsavgift. order. Sallskapet utger ocksa den ickeperiodiska serien Viixteko­ Both series can be received by exchange for other scientific logiska studier. Den kan fo rvarvas efter bestallning eller ge­ publications. Please apply to the Institute Library (address as nom staende abonnemaog hos Sallskapet. above). Bada serierna kan ocksa erhallas i byte mot andra publika­ tioner efter hanvandelse till Vaxtbiologiska institutionens bib­ liotek.

ACTA PH YTOGEOGRAPHICA SUECICA

0. B. Lindquist, Dalby Soderskog. En skansk lovskog i I. E. Almquist, Upplands vegetation och flora. (Vegetation I and flora of Uppland.) 1929. ISBN 91-72 10-001-X. fo rntid och nutid . (Zusammenf. : Ein Laubwald in Scho­ 2. S. Th unmark, Der See Fiolen und seine Vegetation. 1931. nen in der Vergangenheit und Gegenwart.) 1938. 56:-. 46:-. ISBN 91-72 10-002-8. ISBN 91-7210-010-9. 11. Lake Vattern. Outlines of its natural history, 3. G. E. Du Rietz, Life-forms of terrestrial flowering plants. N. Stalberg, I. 1931. 28:- ISBN 91-7210-003-6. especially its vegetation. 1939. 20:-. ISBN 91-72 10-01 1-7.

4. B. Lindquis t, Om den vildvaxande skogsalmens raser och 12. G. E. Du Rietz, A. G. Hannerz, G. Lohammar, R. San­ deras utbredning i Nord vasteuropa . (Su mmary : The races tesson & M. Wtl'rn, Zur Kenntnis der Vegetation des Sees of spontaneous Ulmus glabra Huds. and their distribution Takern. 1939. 20:-. ISBN 91-7210-012-5. in NW. Europe.) 1932. 23:-. ISBN 91-7210-004-4. 13. Viixtgeografiska studier tilliignade Cart Skottsberg pa 5. H. Osvald, Vegetation of the Pacific coast bogs of North sextioarsdagen 1/12 1940. (Geobotanical studies dedica­ America. 1933. 18:-. ISBN 91-7210-005-2. ted to C. Skottsberg.) 1940. 62:-. ISBN 91-72 10-013-3.

6. G. Samuelsson , Die Verbreitung der hoheren Wasser­ 14. N. Hylander, De svenska fo rmerna av Mentha gentilis L. pflanzen in Nordeuropa. 1934. 49:-. ISBN 91-7210-006-0. coli. (Zusammenf. : Die schwedischen Formen der Men­

7. G. Degelius. Das ozeanische Element der Strauch- und tha gentilis L. sensu coli.) 194L 20:-. ISBN 91-7210- Laubflechtenflora von Skandinavien. 1935. 62:-. ISBN 014-1.

91-72 10-007-9. 15. T. E. Hasselrot , Till kannedomen om nagra nordiska um­ 8. R. Sernander, Granskar och Fiby urskog. En studie over bilicariaceers utbredning. (Zusammenf. : Zur Kenntnis der stormluckornas och marbuskarnas betydelse i den sven­ Verbreitung einiger Umbilicariaceen in Fennoscandia.) ska granskogens regeneration. (Summary: The primitive 1941. 26:-. ISBN 91-72 10-015-X. fo rests of Granskar and Fiby. A study of the part played 16. G. Samuelsson, Die Verbreitung der Alchemilla-Arten by storm-gaps and dwarf trees in the regeneration of the aus der Vulgaris-Gruppe in Nordeuropa . 1943. 35:-. Swedish spruce forest.) 1936. 52:-. ISBN 91-7210-008-7. ISBN 91-72 10-016-8. 17. Th . Studien iiber die Gefasspflanzen in den 9. R. Sierner, Flora der Insel Oland. Die Areale der Ge­ Arwidsson, fa sspflanzen Glands nebst Bemerkungen zu ihrer Hochgebirgen der Pite Lappmark. 1943. 60:-. ISBN Oekologie und Soziologie . 1938. ISBN 91-72 1 0-009-5. 91-7210-0 17-6.

Acta Phytogeogr. Suec. 74 100

18. N. Dahlbeck. Strandwiesen am sudostlichen bresund . Norge . (Summary: Upper limits of vascular plants on (Summary: Salt marshes on the S. E. coast of bresund .) mountains in Southwestern Jamtland and adjacent parts 1945. 30:-. ISBN 91-7210-018-4. of Harjedalen (Sweden) and Norway.) 1955. 40:-. ISBN 19. 91-7210-035-4. E. von Krusenstjerna, Bladmossvegetation och blad­ mossflora i Uppsalatrakten. (Summary : Moss flora and 36. N. Quenners!edt. Diatomeerna i Uingans sj ovegetation. moss vegetation in the neighbourhood of Uppsala.) 1945 . (Summary : Diatoms in the lake vegetation of the Umgan 65:-. ISBN 91-7210-0 19-2. drainage area, Jamtland, Sweden.) 1955. 40:-. ISBN 20. N. Albertson, bsterplana hed. Ett alvaromdide pa Kin­ 91-72 10-036-2. nekulle. (Zusammenf. : bsterplana hed. Ein Alvargebiet 37. M.-B. Florin, Plankton of fresh and brackish waters in the aufdem Kinnekulle.) 1946. ISBN 91-72 10-020-6. Sodertalje area. 1957. 30:-. ISBN 91-72 10-037-0. 21. H. Sjo rs , Myrvegetation i Bergslagen. (Summary: Mire 38. M.-B. Florin , Insjostudier i Mellansverige. Mikrovegeta­ vegetation in Bergslagen, Sweden.) 1948. 62:-. ISBN tion och pollenregn i vikar av bstersj obackenet och insjoar 91-72 10-02 1-4. fran preboreal tid till nutid. (Summary : Lake studies in 22 . S. Ahlner, Utbredningstyper bland nordiska barrtradsla­ Central Sweden. Microvegetation and pollen rai n in inlets var. (Zusammenf. : Verbreitungstypen unter fe nnoskandi­ of the Baltic basin and in lakes from Preboreal time to the schen Nadelbaumflechten.) 1948. 56:-. ISBN 91-72 10- present day.) 1957. 16:-. ISBN 91-72 10-038-9. 022-2. 39. M. Fries , Vegetationsutveckling och odlingshistoria i 23. E. Julin, Vessers udde, Mark och vegetation i en igen­ Varnhemstrakten. En pollenanalytisk undersokning i vaxande lovang vid Bj arka-Saby. ( Zusammenf. : Vessers Vastergotland. (Zusam men f. : Vegetationsent wicklung udde. Boden und Vegetation in einer verwachsenden und Siedlungsgeschichte im Gebiet von Varnhem. Eine Laubwiese bei Bjarka-Saby in bstergotland, Sudschwe­ pollenanalytische Untersuchung aus Vastergotland den.) 1948. 44 :-. ISBN 91-72 10-023-0. (Sudschweden) .) 1958. 26:-. ISBN 91-72 10-039-7. 24. M. Fries , Den nordiska utbredningen av Lactuca alpina, 40. Benxt Pettersson, Dynamik och konstans i Gotlands flora Aconitum septentrionale, Ranunculus platanifolius och och vegetation . (Resume: Dynamik und Konstanz in der Polygonatum verticillatum. (Zusammenf. : Die nordische Flora und Vegetation von Gotland, Schweden.) 1958. ) 1949. 20:-. 75:-. 91-72 10-040-0. Verbreitung von Lactuca alpina . . . ISBN ISBN 91-72 10-24-9. 41 . E. Uxxla. Skogsbrandfalt i Muddus nationalpark. (Sum­ 25 . 0. Gj tPrevo/1 , Sn�leievegetasjonen i Oviksfjellene. (Sum­ mary: Forest fire areas in Muddus National Park , North­ mary : The snow-bed vegetation of Mts Oviksfjallen , Jamt­ ern Sweden.) 1958. 33:-. ISBN 91-72 10-041-9. land, Sweden.) 1949. 30:-. ISBN 91-72 10-025-7. 42 K. Th omasson, Nahuel Huapi. Plankton of some lakes in 26. H. Osvald, Notes on the vegetation of British and Irish an Argentine National Park, with notes on terrestrial mosses. 1949. 20:-. ISBN 91-7210-026-5 . vegetation. 1959. 30:-. ISBN 91-72 10-042-7. 27. Floristic phytogeography of South-Western S. Selander, 43. V. Gillner. Vegetations- und Standortsuntersuchungen in Lule Lappmark (Swedish Lapland). I. 1950. 46 :-. ISBN den Strandwiesen der schwedischen Westkuste . 1960. 91-72 10-027-3. 48:-. ISBN 91-72 10-043-5 . 28. S. Selander. Floristic phytogeography of South-Western 44. E. Sjijgren, Epiphytische Moosvegetation in Laubwal­ Lule Lapp mark (Swedish Lapland). 11. Karlvaxtfloran i dern der Insel bland. Schweden. (Summary : Epiphytic sydvij.stra Lule Lappmark . (Summary: Vascular flora.) moss communities in deciduous woods on the island of 1950. 38:-. ISBN 91-72 10-028- 1. bland, Sweden.) 1961. 38:-. ISBN 91-72 10-044-3 (ISBN 29. M. Fries, Pollenanalytiska vittnesbord om se nkvartar ve­ 91-72 10-444-9). getationsutveckling, sarskilt skogshistoria. i nordvastra 45. G. Wistrand, Studier i Pite Lappmarks karlvaxtflora. med Go tal and . (Zusammenf. : Pollenanalytische Zeugnisse der sarskild hansyn till skogslandet och de isolerade fjallen. spatquartaren Vegetationsentwicklung, hauptsachlich der (Zusammenf. : Studien i.iber die Gefasspflanzenflora der Waldgeschichte, im nordwestlichen Gotaland , Si.id­ Pite Lappmark mit besonderer Berucksichtigung des schweden.) 1951. 49:-. ISBN 91-72 10-029-X. Waldlandes und der isolierten niederen Fj elde.) 1962 . 30. M. W lPrn , Rocky-shore algae in the bregrund Archipe­ 49:-. ISBN 91-72 10-045- 1 (ISBN 91-72 10-445-7). lago. 1952. 62 :-. ISBN 91-7210-030-3. 46. R. lvarsson, Lovvegetation i Mollosunds soc ken. (Zu­ 31. 0. Rune, Plant life on serpentines and related rocks in the sammenf. : Die Laubvegetation im Kirchspiel Mollosund. Northof Sweden. 1953. 30:-. ISBN 91-72 10-03 1-1. Bohuslan, Schweden.) 1962 . 40:-. ISBN 91-72 1 0-046-X 32. 91-7210-446-5). P. Kaaret, Wasservegetation der Seen Orlangen und Tre­ (ISBN horningen. 1953. 20:-. ISBN 91-72 10-032-X. 47 . K. Th omasson, Araucanian Lakes. Plankton studies in 33. T. E. Hasselrot, Nordliga lavar i Syd- och Mellansverige . North Patagonia, with notes on terrestrial vegetation. (Nordliche Flechten in Si.id- und Mittelschweden.) 1953. 1963. 45:-. ISBN 91-72 10-047-8. 46:-. 91-7210-033-8. 48. ISBN E. S} oxren , Epilitische und epigaische Moosvegetation in 34. H. Sjo rs , Slatterangar i Grangarde finnmark. (Summary: Laubwaldern der Inset bland , Schweden. (Summary: Meadows in Grangarde Finnmark, SW. Dalarna, Swe­ Epilithic and epigeic moss vegetation in deciduous woods den.) 1954. 36:-. ISBN 91-7210-034-6. on the island of bland, Sweden.) 1964. 60:-. ISBN 35. S. Kilander, Karlvaxtemas ovre granser pa fjall i sydvast­ 91-72 10-048-6 (ISBN 91-72 10-448- 1). ra Jamtland samt angransande delar av Harjedalen och 49. 0. Hedberg , Features of afroalpine plant ecology . (Re-

Acta Phytogeogr. Suec. 74 101

sume fram;ais.) 1964. 60:-. ISBN 91-7210-049·4 (ISBN 63. S. Br/ikenhielm , Vegetation dynamics of afforested farm­ 91-7210-449-X). land in a district of South-eastern Sweden. 1977. 65:-.

50. The Planr Cmw of Sweden . A study dedicated to G. ISBN 91-72 10-063-X (ISBN 91-7210-463-5). Einar Du Rietz on his 70th birthday by his pupils. 1965. 64 . M. Ammar, Vegetation and local environment on shore 110:-. ISBN 91-72 10-050-8. ridges at Vickleby, bland, Sweden. An analysis. 1978.

51. T. Flensburg, Desmids and other benthic algae of Lake 65:-. ISBN 91-72 10-064-8 (ISBN 91-72 10-464-3). Kavsjon and Store Mosse, SW Sweden. 1967 . 50:-. ISBN 65 . L. Kuflman, Change and stability in the altitude of the 91-72 10-05 1-6 (ISBN 91-72 10-45 1-1 ). birch tree-limit in the southern Swedish Scandes 1915- 52. E. Skye, Lichens and air pollution. A study of cryptoga­ 1975. 1979. 65 :-. ISBN 91-7210-065-6 (ISBN 91-7210- mic epiphytes and environment in the Stockholm region. 465- 1). 1968 . 70:-. ISBN 91-72 10-052-4 (ISBN 91-72 10-452-X). 66 . £. Waldemarson Jensen, Successions in relationship to 53. Jim Lundqvist, Plant cover and environment of steep lagoon development in the Laitaure delta, North Sweden. hillsides in Pite Lappmark. (Resume : La couverture vege­ 1979. 65:-. ISBN 91-72 1 0-066-4 (ISBN 91-72 10-466-X). tate et !'habitat des fl ancs escarpes des collines de Pite 67 . S. Tuhf..:anen, Climatic parameters and indices in plant Lappmark.) 1968 . 60:-. ISBN 91-7210-053-2 (ISBN 91- geography. 1980. 65:-. ISBN 91-72 1 0-067-2 (ISBN 91- 72 10-453-8). 721 0-467-8). 54. Conserva tion of VeRefation in Africa South of rhe Saha­ 68 . Srudies in piant ecoloRY dedicated to Hugo Sj ors. Ed. ra . Proc . of symp. at 6th plen . meeting of AETFAT. Ed. Erik Sj ogren. 1980. 95:-. ISBN 91-72 10-068-0 (ISBN 91- by Inga and Olov Hedberg. 1968 . 80:-. ISBN 91- 72 1 0-468-6).

72 10-054-0 (ISBN 91-72 10-454-6). 69. C. Nilsson, Dynamics of the shore vegetation of a North 55. L.-K. K()niRsson , The Holocene history of the Great Al­ Swedish hydro-electric reservoir during a 5-year period . var of bland. 1968 . 75:-. ISBN 91-721 0-055-9 (ISBN 1981. 65:-. ISBN 91-72 1 0-069-9 (ISBN 91-72 1 0-469-4).

91-72 10-455-4). 70. K. Warenberg, Reindeer forage plants in the early grazing 56. H. P. HaflherR. Vegetation auf den Schalenablagerungen season. Growth and nutritional content in relation to cli­ in Bohuslan, Schweden. (Summary: Vegetation on shell matic conditions. 1982. 75:-. ISBN 91-72 10-070-2 (ISBN deposits in Bohuslan, Sweden.) 1971. 60:-. ISBN 91- 91-721 0-470-8). 72 1 0-056-7 (ISBN 91-72 10-456-2). 71. C. Johansson , Attached algal vegetation in running wa­

57. S. Fra nsson. Myrvegetation i sydvastra Varmland . ters of Jamtland , Sweden. 1982. 75:- ISBN 91-72 Je-07 1-0 (Summary: Mire vegetation in south-western Varmland , (ISBN 91-72 10-47 1 -6) .

Sweden.) 1972. 55:-. ISBN 91-72 10-057-5 (ISBN 91- 72 . E. Rosen , Vegetation development and sheep grazing in 72 1 0-457-0). limestone grasslands of south bland, Sweden. 1982. 95: -. 58. G. Wallin . Lovskogsvegetation i Sj uharadsbygden. ISBN 91-7210-072-9 (ISBN 91-7210-472-4).

(Summary: Deciduous woodlands in Sj uharadsbygden, 73. L. Zhang, Vegetation ecology and population biology of Vastergotland, south-western Sweden.) 1973 . 55:-. ISBN Fritillaria meleagris L. at the Kungsangen Nature Reserve , 91-72 10-058-3 (ISBN 91-72 10-458-9). Eastern Sweden. 1983 . 90:-. ISBN 91-7210-073 -7 59. D. Johansson. Ecology of vascular epiphytes in West (ISBN 91-7210-473 -2). African rain forest. (Resume: Ecologie des epiphytes 74. /. Backeus, Aboveground production and growth dynamics vasculaires dans la foret dense humide d'Afrique occiden­ of vascular bog plants in central Sweden. 1985. 90:-. ISBN tale.) 1974. ISBN 91-72 10-059- 1 (ISBN 91-72 10-459-7). 91-7210-074-5 (ISBN 91-7210-474-0). 60. H. 0/sson , Studies on South Swedish sand vegetation. 1974. 80:-. ISBN 91-72 10-060-5 (ISBN 91-7210-460-0). 61. H. Hyr reborn. Deciduous woodland at Andersby , Eastern Sweden. Above-ground tree and shrub production. 1975. Limited number of cloth-bound copies of Acta 44, 45 , 46, 48 55:-. ISBN 91-72 10-061-3 (ISBN 91-72 10-46 1-9). 49, 51, 52, 53, 56, 57, 61, 63 , 66, 67 , 68, 69, 70, 71, 72, 73 are 62. H. Persson , Deciduous woodland at Andersby, Eastern available through the Society at an additional cost of 15:- per Sweden: Field-layer and below-ground production. 1975. copy. ISBN nos. in brackets refer to cloth-bound copies. Nos. 1, 50:-. ISBN 91-72 10-062- 1 (ISBN 91-72 10-462-7). 9, 20, 59 are out of print.

Acta Phytogeogr. Suec. 74 102

V A.XTEKOLOGISKA STUDIER

I. 5. Brakenhielm & T. /nge/Og, Vegetationen i Kungs­ Umealven. (Summary : Bioeffects of hydroelectric de­ hamn-Morga naturreservat med forslag till skotselplan . velopment. A case study based mainly on observations (Summary: Vegetation and proposed management in the along the Ume River, northern Sweden.) 1976. 35:-. Kungshamn-Morga Nature Reserve south of Uppsala.) ISBN 91-72 10-808-8.

1972. 25:-. ISBN 91-72 10-801-0. 9. 1. Lundqvist & G. Wistrand, Strandtlora inom ovre och 2. T. lngelog & M. Risling, Kronparken vid Uppsala, histo­ mellersta Skelleftealvens vattensystem. Med en samman­ rik och best�mdsanalys av en 300-arig tallskog. (Summary : fattning betraffande botaniska skyddsvarden. (Summary : Kronparken, history and analysis of a 300-year-old pine­ Riverside vascular flora in the upper and middle catch­ wood near Uppsala, Sweden.) 1973. 25:-. ISBN ment area of the River Skelleftealven, northern Sweden.) 91-7210-802-9. 1976. 30:-. ISBN 91-72 10-809-6. 3. H. Sjors och medarb. , Skyddsvarda myrar i Kopparbergs 10. A Miiller-Haeckel, Migrationsperiodik einzelliger Algen Jan. (Summary: Mires considered for protection in Kop­ in Fliessgewassern. 1976. 15:-. ISBN 91-72 10-810-X. parberg County (Prov. Dalarna, Central Sweden).) 1973 . 11. Sjo din, Index to distribution maps of bryophytes A.. 25:-. ISBN 91-72 10-803-7. 1887-1975. I. Musci . 1980. 60:- (hard-bound). ISBN 4. L. Karlsson , Autecology of cliffand scree plants in Sarek 91-72 I 0-8 1 1 -8. National Park, northern Sweden 1973. 30:-. ISBN 12. Sjd din , Index to distribution maps of bryophytes A. 91-72 10-804-5. 1887-1975. 11. Hepaticae . 1980. 40:- (hard-bound). ISBN 5. B. Klasvik, Computerized analysis of stream algae . 1974. 91-72 10-8 1 2-6. 25:-. ISBN 91-72 10-805-3. 13. 0. Erif.:.sson , T. Palo & L. Shderstrdm, Renbetning 6. Y. Dahlstrom-Ekbohm, Svensk miljovards- och omgiv­ vintertid. Undersokningar rorande svensk tamrens na­ ningshygienlitteratur 1952-1972. Bibliografi och analys. ringsekologi under snoperioden. 1981. 25:- ISBN 1975. 25:-. ISBN 91-72 10-806- 1. 91-7210-8 1 3-4.

7. L. Rodenborg , Bodennutzung, Pflanzenwelt und ihre 14. G. Wistrand, Bidrag till Pite lappmarks vaxtgeografi . Veranderungen in einem alten Veidegebiet auf Mittel­ 1981. 25:-. ISBN 91-72 10-8 14-2. Oland, Schweden. 1976. 25:-. ISBN 91-72 10-807-X. 15. T. Karlsson, Euphrasia rostkoviana i Sverige. 1982. 35:-. 8. H. Sj ors & Ch . Nilsson, Vattenutbyggnadens effekter pa ISBN 91-72 10-8 1 5-0. levande natur. En fa ktaredovisning overvagande fran

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Acta Phytogeogr. Suec. 74

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