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  • 1.
    Backéus, Ingvar
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecological Botany.
    Blandmyr på kartbladen Örebro NV och NO1978In: Geologiska Föreningens i Stockholm Förhandlingar, Vol. 100, p. 407-408Article in journal (Refereed)
    Abstract [en]

    Six mire sites designated as mixed mires on the geological maps Örebro NV and NO have been surveyed. All of them were found to be entirely ombrotrophic bogs. The necessity of considering the composition of the vegetation in drawing the distinction between ombrotrophic and minerotrophic mire sites is pointed out. 

  • 2.
    Backéus, Ingvar
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecological Botany.
    Bog vegetation re-Mapped after sixty years: Studies on Skagershultamossen, central Sweden1972In: Oikos, ISSN 0030-1299, E-ISSN 1600-0706, Vol. 23, no 3, p. 384-393Article in journal (Refereed)
    Abstract [en]

    The author has re-mapped two areas on Skagershultamossen. The new maps have been compared with maps of the same areas from 1910, made by L. von Post. The vegetation changes are small. The open water surfaces have diminished in number and extent. The theory of cyclic succession on peat bogs finds no support from the maps. Plant communities have been delimited as to correspond to those on the old maps and defined through analysis of a number of sample plots

  • 3.
    Backéus, Ingvar
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecological Botany.
    Comments on Conservation, reclamation and grazing in the northern Negev: contradictory or complementary concepts? (paper 38a) by Avi Perevolotsky1995In: Pastoral Development Network. Network Paper, Vol. 38b, p. 21-24Article in journal (Refereed)
  • 4.
    Backéus, Ingvar
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecological Botany.
    Distribution and vegetation dynamics of humid savannas in Africa and Asia1992In: Journal of Vegetation Science, ISSN 1100-9233, E-ISSN 1654-1103, Vol. 3, p. 345-356Article in journal (Refereed)
    Abstract [en]

    A review is presented on the literature about the distribution of savannas in humid climates in Africa and Asia and their vegetation dynamics. Sections are devoted to African lowland and montane savannas (the latter divided into southern, eastern, western and northern African), Madagascar, Indian subcontinent, SE Asia and New Guinea. It is concluded that the extension of savannas under humid climatic conditions and the relation to the distribution of forests is a function of cultivation, grazing by domestic and wild animals, present and previous climate, geomorphology and soil characteristics. Once established, savannas are often maintained by fires, both natural and man-made.

    Montane savannas are generally brought about by man's clearing, cultivation and burning. Fire is a stochastic variable; it creates an ecotone sensu stricto (an environmentally stochastic stress zone) at the forest/savanna border. On the other hand, if geomorphology and soil are the determinants, the transition between forest and savanna would have the character of an ecocline (a gradient zone) with fundamentally different conditions.

    In humid African lowland climates forests expand into savannas if the latter are not maintained by man. Whether forests also expand in less humid climates is disputed. In montane areas forest expansion may be delayed on degraded soils and when diaspores are lacking

  • 5.
    Backéus, Ingvar
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecological Botany.
    Ecotone versus ecocline: vegetation zonation and dynamics around a small reservoir in Tanzania1993In: Journal of Biogeography, ISSN 0305-0270, E-ISSN 1365-2699, Vol. 20, p. 209-218Article in journal (Refereed)
    Abstract [en]

    Data from transects on the shores and drawdown area of a small reservoir in Tanzania with a strongly fluctuating water level were used to illuminate a spatial and shortterm temporalvariation in the vegetation of a borderzone. Vegetation data were related to the position of the sample plots in relation to a water level gauge and to time (seasonal changes and changes between two consecutive years).

    Few perennial species survived the rainy season in the zone exposed to the fluctuating water level. Most plants were annuals that colonized yearly. The vegetation under the full supply level (=FSL) was sparse and related to Eriochloetum nubicae and Ecliption albae. An observed great variation between sites and years of this kind of vegetation seems to be due to the unstable character of the sites with frequent recolonization of bare land.

    The need to distinguish formally between ecotones (in a strict sense) and ecoclines is stressed. The drawdown area has (a) a peak in β diversity just below FSL, (b) no β diversity in a zone below FSL that was not flooded the preceding rainy season and (c) a certain amount of β diversity further down.(a) and(b) are considered typical of an ecotone. (c) is interpreted as a 'shortterm ecocline' of colonizing annuals between two rainy seasons. The system belowFSL as a whole is an ecotone. The shore above FSL is an ecocline with high α and β diversity.

    A downward movement of plant species during the dry season is demonstrated using canonical correspondence analysis. Thus, this ecotone is driven by the environment and no internal (autonomous) control is likely to occur

  • 6.
    Backéus, Ingvar
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecological Botany.
    Effekter av myrdikning på flora och vegetation: En problemstrukturerad sammanställning av litteratur1981Book (Other academic)
  • 7.
    Backéus, Ingvar
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecological Botany.
    Flarks in the Maloti, Lesotho1989In: Geografiska Annaler. Series A, Physical Geography, ISSN 0435-3676, E-ISSN 1468-0459, Vol. 71, p. 105-111Article in journal (Refereed)
    Abstract [en]

    Flarks are reported to occur in mires in Qathlamba (the Drakensberg Range) of the Maloti, Lesotho at an altitude of 3200 m a.s.l. Flarks are not previously reported from Africa. Conditions for the formation and maintenance of flarks are discussed. It is argued that local waterlogging is a more likely explanation for the formation of flarks in Qathlamba than frost action.

  • 8.
    Backéus, Ingvar
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecological Botany.
    Hedlav, Cornicularia aculeata på mossar1983In: Svensk Botanisk Tidskrift, ISSN 0039-646X, Vol. 77, p. 27-28Article in journal (Refereed)
  • 9.
    Backéus, Ingvar
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecological Botany.
    I västerled till Shetland1983In: Svensk Botanisk Tidskrift, ISSN 0039-646X, Vol. 77, p. 26-Article, book review (Other (popular science, discussion, etc.))
  • 10.
    Backéus, Ingvar
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecological Botany.
    Markförstöring I Afrika1987In: Upsala Nya TidningArticle, book review (Other (popular science, discussion, etc.))
  • 11.
    Backéus, Ingvar
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecological Botany.
    Milstolpe i västmanländsk botanik1982In: BergslagspostenArticle, book review (Other (popular science, discussion, etc.))
  • 12.
    Backéus, Ingvar
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecological Botany.
    Mires in the Thaba-Putsoa Range of the Maloti, Lesotho1988Book (Refereed)
  • 13.
    Backéus, Ingvar
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecological Botany.
    Myrar i Örebro län1984In: Svensk Botanisk Tidskrift, ISSN 0039-646X, Vol. 78, p. 21-44Article in journal (Refereed)
  • 14.
    Backéus, Ingvar
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecological Botany.
    Myten om tuvan som blev en hölja1987In: Fauna och flora : populär tidskrift för biologi, ISSN 0014-8903, Vol. 82, p. 114-122Article in journal (Refereed)
  • 15.
    Backéus, Ingvar
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecological Botany.
    Production and depth distribution of fine roots in a boreal open bog1990In: Annales Botanici Fennici, ISSN 0003-3847, E-ISSN 1797-2442, Vol. 27, p. 261-265Article in journal (Refereed)
    Abstract [en]

    The production of fine roots in originally root-free ingrowth cores was studied in an ombrotrophic mire ecosystem in central Sweden (14°42'N, 60°10'E). The estimated production values, which should be considered conservative , were 51 g.m-2 in hummocks and 86 g.m-2 in lawns (= upper hollow level). This represents 38% of the total measured production of vascular plants (increment in coarse roots not included) in hummocks and lawns, respectively. In the first year of study more than 50% of the fine root standing crop was found above 10 cm depth. In the second year, which was very dry, the roots penetated significantly deeper.

  • 16.
    Backéus, Ingvar
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecological Botany.
    Report on a study tour to the indigenous forests of the West Usambara Mts., Tanzania with special reference to regeneration1982Report (Other academic)
  • 17.
    Backéus, Ingvar
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecological Botany.
    The cyclic regeneration on bogs – a hypothesis that became an established truth1991In: Striae, Vol. 31, p. 33-35Article in journal (Refereed)
  • 18.
    Backéus, Ingvar
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecological Botany.
    The Nigerian environment. Report on a visit and background information1984Report (Other academic)
  • 19.
    Backéus, Ingvar
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecological Botany.
    Torvmarkskarteringen på kartbladen Örebro NV och NO: Replik till Magnusson1980In: Geologiska föreningens i Stockholm Förhandlingar, Vol. 100, p. 410-Article in journal (Refereed)
  • 20.
    Backéus, Ingvar
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecological Botany.
    Vegetation changes after fertilization on drained peatlands in central Sweden1980In: Acta Phytogeographica Suecica, ISSN 0084-5914, Vol. 68, p. 17-30Article in journal (Refereed)
  • 21.
    Backéus, Ingvar
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecological Botany.
    Weather variables as predictors of Sphagnum growth on a bog1988In: Holarctic Ecology, Vol. 11, p. 146-150Article in journal (Refereed)
    Abstract [en]

    When surrounded by growing Sphagnum the rhizomes of Scirpus cespitosus grow vertically upwards in pace with the Sphagnum. It was found that there is a considerablevariation in rhizome growth between years and it is assumed that this variation is determined by variation in Sphagnum growth. The latter variation is assumed to be dependent on the weather. Simple and multiple regression analysis of rhizome growth on various weather variables gave the following results:(1) Moisture conditions are decisive for the growth. (2) The distribution in time of the moisture is more important than mean values from a certain period. (3) Although moisture in June and Augus tof the current year was important, the moisture conditions of August of the previous year explained ca 60% of the variation. (4) A combination of the two variables Birot's wetness index in August of the previous year and the same index in current June gave r2 = 0.80.

  • 22.
    Backéus, Ingvar
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecological Botany.
    Grab, Stefan
    Mires in Lesotho1995In: Gunneria, ISSN 0332-8554, E-ISSN 1894-7859, Vol. 70, p. 243-250Article in journal (Refereed)
    Abstract [en]

    Soligenous mires are common at high altitudes in the mountains of Lesotho, southern Africa. The flora and vegetation are distinctive and the mires form ecosystems not found elsewhere. Peat is formed mainly from the roots of vascular plants and is generally shallow. Bryophytes play a subordinate role in the vegetation. Flarks and thufur occur at the highest altitudes. The mires are heavily grazed and are rapidly being destroyed, particularly through gullying caused by intense grazing upslope from the sites. A project to export water to South Africa is now being put into effect. This will severely affect the mires through inundation of sites and increased pressure on remaining land. The new infrastructure in these areas also causes destruction. An appeal is made for international pressure to save the remaining mires in Lesotho.

  • 23.
    Backéus, Ingvar
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecological Botany.
    Näslund, Barbro
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecological Botany.
    Edström, Eva
    Skyddsvärda myrar i Örebro län1978Report (Other academic)
  • 24.
    Backéus, Ingvar
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecological Botany.
    Rulangaranga, Z. K.
    University of Dar es Salaam.
    Skoglund, Jerry
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecological Botany.
    The dynamic interrelationship between vegetation and the environment on the formerly eroded Kondoa Irangi Hills1996In: Changing environments: research on man-land interrelations in semi-arid Tanzania / [ed] C. Christiansson & I.S. Kikula, 1996, p. 54-63Conference paper (Other academic)
  • 25.
    Backéus, Ingvar
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecological Botany.
    Rulangaranga, Z K
    University of Dar es Salaam.
    Skoglund, Jerry
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecological Botany.
    Vegetation changes on formerly overgrazed hill slopes in semi-arid central Tanzania1994In: Journal of Vegetation Science, ISSN 1100-9233, E-ISSN 1654-1103, Vol. 5, p. 327-336Article in journal (Refereed)
    Abstract [en]

    Composition of hill slope vegetation was studied in a semi-arid part of upland Tanzania where all grazing had been banned for 12 yr. The hills had been severely overgrazed previously and suffered from heavy gully and sheet erosion. Eight vegetation types are described. Floristic gradients revealed by numerical ordination techniques were found to be related mainly to degree of erosion, soil type and succession. The more or less bare soil that prevailed after grazing had ceased is now covered by grassland, woodland and immature secondary forest. The grasslands are still characterized by early successional species and they will probably remain open grassland as long as frequent burning continues. Brachystegia woodlands may have developed during earlier periods when the field layer was sparse due to grazing. The grazing had reduced the frequency of fire which in turn promoted the establishment of Brachystegia spp. Secondary forests are believed to have developed mainly where fires were not frequent, particularly at higher altitudes.

  • 26.
    Backéus, Ingvar
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecological Botany.
    Stenbeck, Gösta
    Konsekvenser av skogs- och myrdikning. Påverkan på flora och vegetation1981Other (Other (popular science, discussion, etc.))
  • 27.
    Backéus, Ingvar
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecological Botany.
    Zhang, Liquan
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecological Botany.
    瑞典植物生态学研究简介: An outline of plant ecological researches in Sweden1984In: Acta Phytoecologica Sinica, p. 247-252Article in journal (Refereed)
  • 28.
    Bengtsson, Karin
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecological Botany.
    Prentice, Honor C
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecological Botany.
    Rosén, Ejvind
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecological Botany.
    Moberg, Roland
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Systematic Botany.
    Sjögren, Erik
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecological Botany.
    The dry alvar grasslands of Öland: ecological amplitudes of plant species in relation to vegetation composistion.1988In: Acta Phytogeographica Suecica, ISSN 0084-5914, ISSN 0084-5914, Vol. 76, p. 26p. 21-46Article in journal (Other academic)
  • 29.
    Berg, Henrik
    Uppsala University, Department of Ecological Botany.
    The ecological significance of cleistogamy1998Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Various aspects of cleistogamy, a reproductive system combining selfing in closed (cleistogamous) flowers and potential outcrossing in open (chasmogamous) flowers, were investigated in four perennial species. The main purpose was to shed some light on the adaptive value of having a dual reproductive strategy, and to test some hypotheses on the maintenance of xenogamy. In field studies including variation between years and sites, chasmogamous (CH) and cleistogamous (CL) flower and seed production were quantified in ramets of different size. Performance of CH and CL offspring under different conditions was examined in comparative field and garden studies, and an experiment on ballistic dispersal of CH and CL seeds was conducted.

    It was found that in Oxalis acetosella and Viola hirta, CL production is influenced by ramet size and reproductive success in the CH phase. Production in both phases varies considerably among years and sites in O. acetosella, and on the whole reproductive success is not greater in the CL phase than in the CH phase. In addition, the two phases seem to have their optima at different points along temporal and spatial variation scales in O. acetosella.

    In O. acetosella, Viola mirabilis, and V. riviniana, germination was found to be lower in CL seeds than in CH seeds, and in V. hirta and V. rivinana CL offspring were on average smaller than CH offspring. These differences may be attributable to inbreeding depression in selfed offspring, but regarding seedling survivorship there is no difference between the two offspring types. In the dispersal experiment CL seeds of O. acetosella were thrown farther from the mother plant than were CH seeds, in contrast to data from other species.

    The results of this study partly contradict the traditional view on cleistogamy and the relationship between xenogamy and autogamy, where perhaps the genetic aspects have been overrated. The main selective value of a dual reproductive system is probably in optimizing individual seed output by compensating for environmental stochasticity.

  • 30.
    Dai, Xiaobing
    Uppsala University, Department of Ecological Botany.
    Small-scale pattern and mobility of plant species in Alvar grassland1998Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Studies of the small-scale pattern, mobility of plant species and the effects of cattle dung deposition and decomposition on the soil seed banks and the above-ground vegetation were carried out in an alvar limestone grassland in Gettlinge, on the Baltic island of Öland, Sweden.

    A new method for pattern detection using transect data Patch Size Frequency Analysis (PASFRAN), was developed. Three transects, each 50 m long and consisting of 500 quadrats of 10 x 10 cm, were analysed to describe the pattern of vascular plant species (phanerogams), mosses and lichens (cryptogams), and the correlation between them. PASFRAN revealed that 42% of all significant species patches had mean patch sizes in the range of 26 - 50 cm in diameter, which match the size of dung patches. Use of PASFRAN in combination with species association analysis. is considered effective in detecting relations between species and between species and environmental factors.

    Multi-species patterns, analysed by PASFRAN and Detrended Correspondence Analysis (DCA), were found at sizes from 20 to 240 cm, and included both cryptogam and phanerogam species. The cryptogam and phanerogam layers were correlated and the correlation increased with increase in grain size. Results suggest interactions between cryptogams and phanerogams.

    Separate transect and seed bank analyses were conducted to investigate the effects of dung patches on the soil seed bank and the vegetation. A six-scale decompositon degree was developed to classify the decomposition status of dung. Depositian and subsequent decomposition of dung patches add small-scale heterogeneity to the habitat, cause changes in the soil seed bank and the above-ground distribution pattern, and contribute to seed dispersal of certain species. These factors enhance both species mobility and resource availability, and in this way contribute to the maintenance of high species richness of the grassland.

    The turn-around time, defined as the time a species need to reach all microsites, was proposed to quantify species mobility. It is calculated by a simulation procedure based on the year-to-year variation of the species frequency. Application of this approach to six alvar species demonstrates that the turn-around time could be a useful measure of species mobility.

  • 31.
    Frost, Ingela
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecological Botany.
    Rydin, Håkan
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecological Botany.
    Effects of competition, grazing and cotyledon nutrient supply on growth of Quercus robur seedlings1997In: Oikos, ISSN 0030-1299, E-ISSN 1600-0706, Vol. 79, no 1, p. 53-58Article in journal (Refereed)
    Abstract [en]

    In this greenhouse experiment we examined how competition and herbivory affects the growth of Quercus robur seedlings and if the cotyledon nutrient reserve is of importance for survival and growth during unfavourable conditions. We planted oak seedlings with or without a strong competitor (grass turf) and subjected them to factorial grazing and cotyledon removal, in a split-plot design. After one growing season (20 weeks) we found large negative main effects from competition, grazing and cotyledon removal on all biomass components of the seedling. Seedling mortality was also significantly increased by competition. We observed an additional effect of cotyledon removal if the seedlings were also grazed or were growing in competition with grass. This gives some support to the hypothesis that cotyledon nutrient reserves are used under unfavourable conditions, but the effect was often relatively small and not detectable in the growth of all plant parts.

  • 32.
    Grandin, Ulf
    Uppsala University, Department of Ecological Botany.
    Long-term studies of succession: Colonisation and seed banks1998Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Using data from long-term studies of the vegetation in two areas under primary succession, patterns of colonisation and the accumulated seed bank during plant succession were studied.

    At century-old small islands in Lake Hjälmaren, Sweden, the genetic structure of differently old populations of Moehringia trinervia and Lythrum salicaria was studied, using allozyme variation for M. trinervia and style-morph frequencies for the tristylous L. salicaria. Both species showed a low colonisation rate but differed in their genetic structure. For the highly selfing M. trinervia, the genetic structure of the colonisers was preserved due to a low immigration rate, and founder populations of different ages did not differ in their genetic structure but differed from mainland source populations. Neither the perennial self-incompatible L. salicaria showed a temporal trend, probably due to low seed set and high longevity of the colonisers, which retards frequency-dependent selection towards an even style-morph distribution.

    Small-scale seaward migration of species on a land uplift shore along the Baltic Sea was largely related to allogenic factors. Due to stochastic variation in the sea level and to wave action, the continuous seaward migration of species may be temporarily retarded. During the 15 years studied, Ellenberg indicator values related to allogenic vegetation change showed a greater temporal change than values related to autogenic vegetation change.

    At both study areas, the similarity between the seed bank and the extant vegetation decreased with increasing successional age. At Lake Hjälmaren, the deepest soil contained species only found in earlier successional stages. At the sea shore, the seed bank and the vegetation were completely dissimilar at sites older than 200 years.

    Species attributes and Ellenberg indicator values differed in most cases between seed bank and vegetation. Attributes connected with early successional species were associated with the deepest sampled seed bank while attributes of late successional species were associated with the surface soil, indicating that early successional species still after a century of primary succession were present in the deepest soil horizons.

    The Ellenberg indicator values indicated that the seed bank reflects several successional stages now extinct from the vegetation.

  • 33.
    Grandin, Ulf
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecological Botany.
    Rydin, Håkan
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecological Botany.
    Attributes of the seed bank after a century of primary succession on islands in Lake Hjalmaren, Sweden1998In: Journal of Ecology, ISSN 0022-0477, E-ISSN 1365-2745, Vol. 86, no 2, p. 293-303Article in journal (Refereed)
    Abstract [en]

    1  A large number of islands was created when the water table of Lake Hjälmaren, south central Sweden, was lowered between 1882 and 1886. We have complete lists of vascular plant species for 40 of these islands from 1886, 1892, 1903–04, 1927–28 and 1984–85.

    2   We have investigated the seed bank on nine of these islands and compared species composition at different soil depths with the species lists from the islands in 1886–1985, and with the present vegetation in the area of seed bank sampling. We have also investigated the distribution in the soil of seeds from species with different ecological attributes, including seed longevity, successional status, seed weight, seed form and species longevity.

    3  Seeds in soil samples were allowed to germinate over the course of two summers with an intermediate cold storage. We found 1944 seeds representing 65 taxa. The mean seed density was 84 seeds dm–2.

    4   The similarity between the surface soil (0–3 cm) seed bank and the vegetation at the different vegetation analyses increased from 1886 to 1993. The similarity between the present vegetation and the seed bank decreased with increasing soil depth, and the soil at 12–15 cm had no species in common with the present vegetation. Several species now absent from the vegetation were found in the seed bank.

    5   Deeply buried seeds came from early successional, annual species with long-term persistent and low-weight seeds, as expected from seed bank theories, but were slightly elongated, which was in contrast to theories. Spherical seeds were associated with the surface soil, as were short-lived and high-weight seeds from late successional, perennial species.

  • 34. Hazell, P
    et al.
    Kellner, O
    Rydin, Håkan
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecological Botany.
    Gustafsson, L
    Presence and abundance of four epiphytic bryophytes in relation to density of aspen (Populus tremula) and other stand characteristics1998In: Forest Ecology and Management, ISSN 0378-1127, E-ISSN 1872-7042, Vol. 107, no 1-3, p. 147-158Article in journal (Refereed)
    Abstract [en]

    The influence of the local density of aspen on the presence and abundance of four epiphytic bryophytes was investigated in four mixed forest stands in Central Sweden, each about 30 ha and aged 70-120 yr. Cover of the bryophytes Nyholmiella obtusifolia, Orthotrichum speciosum, Pylaisia polyantha and Radula complanata (the four most frequent aspen-specific epiphytic bryophytes in this region) was recorded on the bark of 155 systematically sampled aspen stems. In circular plots with 10 m radius surrounding each sampled aspen, information on ground vegetation, soil moisture and stand density was collected. In these plots, and also in plots with 5 m and 20 m radius, stem number and diameters of aspen trees were recorded together with an observation of the presence/absence of the four bryophytes. There was no general and consistent relation between aspen density and presence or abundance of the studied bryophytes. Site, host aspen diameter and forest stand structures were more important for the bryophytes. The site factor explained more of the variation than any of the studied variables. All species except N. obtusifolia were favoured by a large diameter of the host tree, and the density of the surrounding forest stand had a positive effect on the cover of Pyl. polyantha and R. complanata. The practical implications of the results are discussed.

  • 35.
    Hemborg, Åsa M.
    Uppsala University, Department of Ecological Botany.
    Reproductive allocation and costs of reproduction in subarctic herbs: A resource-based perspective1998Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The influence of internal and external factors on two major plant life history components, i.e., reproductive allocation and costs of reproduction, was examined for nine perennial herbs in subarctic Swedish Lapland. In one study, comparisons were made between Sweden and the French Alps. Reproductive investment and costs were estimated in terms of biomass, nitrogen (N), and phosphorus (P). At high altitudes, reproductive effort (RE) was commonly lower and sexual shoots less frequently produced than at lower altitudes. However, effects of altitude were in some cases absent. This could be due to internal factors, such as meristem formation as in Ranunculus acris and low plasticity of reproductive structures as in Trollius europaeus.

    Reproductive investments varied between sexes in first-year Silene dioica plants. Female flowers produced more nectar than male flowers. At peak flowering, however, male plants offered 3.5 times mom nectar, due to their higher flower numbers. Pollen dry mass and N content per flower varied over the season, while the pollen P content remained constant. Sexual differences in allocation patterns depended on the resource used for comparison and whether absolute or proportional resource pools were assessed. Females and males had similar RE in terms of biomass and N, while males invested proportionally more P in reproduction. High allocation to flowers in males resulted in lower N content of over wintering parts compared to females.

    Reproductive investment was carried out at the expense of the somatic resource pool. However, the occurrence of a direct trade-off between reproductive and somatic functions depended on the focused resource. The traits expressing the trade-off between current and future reproduction varied between habitats for R. acris. Five out of nine examined traits expressed reproductive costs. Effects of experimental treatments may be hampered due to internal factors, e.g. meristem formation. It is important to select several resources, traits, and environments in future assessments of reproductive investments and costs of reproduction in plants.

  • 36.
    Köchy, Martin
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecological Botany.
    Rydin, Håkan
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecological Botany.
    Biogeography of vascular plants on habitat islands, peninsulas and mainlands in an east-central Swedish agricultural landscape1997In: Nordic Journal of Botany, ISSN 0107-055X, E-ISSN 1756-1051, Vol. 17, no 2, p. 215-223Article in journal (Refereed)
    Abstract [en]

    The increase of island species richness with area can be explained by an increase in habitat diversity or by an equilibrium of species immigration and extinction. We examined vascular plant species richness in 39 sites (24 habitat islands, 7 ‘habitat peninsulas’ and 8 comparable ‘mainland’ sites). We sampled at three scales: whole sites, meadows within sites and quadrats (4 m × 4 m) within meadows. All sites (10–104 m2) contained natural vegetation within arable fields in eascentral Sweden. There was a strong correlation between species richness and area for whole sites and for meadows There was no correlation, however, between species richness in quadrats and site area. The difference between site and meadow results on one side and quadrat results on the other suggests that species richness increases with whole site area primarily because large sites are more diverse than smaller ones. Speciearea relationships did not differ between islands, peninsula and mainland sites. Thus, patterns of species richness on our sites were more consistent with habitat diversity than an immigratioextinction equilibrium.

  • 37.
    Lyaruu, Herbert
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecological Botany.
    Eliapenda, Shadrack
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecological Botany.
    Mwasumbi, Leonard B
    University of Dar es Salaam.
    Backéus, Ingvar
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecological Botany.
    The Afromontane forest at Mafai in Kondoa Irangi Hills, central Tanzania. A proposal to conserve a threatened ecosystem1997Report (Other academic)
  • 38.
    Lyaruu, Herbert V. M.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecological Botany.
    Seed dynamics and the ecological restoration of hill slopes of Kondoa Irangi, Central Tanzania1998Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Improper agricultural practices such as bill slope cultivation, extensive clearing of vegetation using fire over a long period, and to some extent overgrazing have converted the once fertile hill slopes of Kondoa Irangi in central Tanzania into unproductive marginal land. It is 25 years now since reclamation measures were introduced to save the hills from further degradation, but the regeneration process, has been rather slow. The present study was initiated with the objective to explore alternative approaches to facilitate vegetation recovery in the hills. It consisted of a description of an Afromontane dry forest, soil seed bank, seed rain and seed longevity studies, and experiments on the influence of different soil treatments on regeneration.

    There was significant seasonal variation in the seed bank (p < 0.001), with dry-season samples having higher densities than wet-season samples. Annual species dominated the seed bank samples in most of Kondoa Irangi Hills, but perennial species were dominant in the soil seed bank of the Afromontane dry forest. In the seed rain, both density and species richness were negatively correlated with vegetation cover. This points to the important role of anemochory and active seed rain in disturbed sites.

    The intermittent and extended germination of buried seeds shown by i.e., Acacia tortilis, is an adaptation to prevent synchronous germination in unpredictable, harsh environments, whereas prompt germination after rains of e.g., Acacia seyal, is a strategy to avoid seed predation.

    Inorganic fertilisation is not an efficient means of improving short-term productivity in poor savanna soils. Nutrient-deficiency should be corrected by moderate grazing and controlled fires.

    Permanent and speedy vegetation recovery of degraded savannas such as in the Kondoa IrangiHills, may require (1) enhanced nitrogen mineralization and seed dispersal by grazing livestock, (2)selective soil seed bank enrichment, and (3) transplanting seedlings with desired traits.

  • 39.
    Pokarzhevskaya, Galina A.
    Uppsala University, Department of Ecological Botany.
    Pattern and process in Alpine communities of the Northwestern Caucasus1998Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Patterns in vegetation reflect certain processes affecting plant communities. The present work aims at describing patterns and revealing mechanisms operating in alpine vegetation belonging to four vegetation types: alpine lichen heaths, Festuca varia grasslands, Geranium-Hedysarum meadows and snowbed communities. The main tasks of the present study are: (1) to outline the patterns in species occurrence and vegetation structure, (2) to describe the factors influencing the vegetation types; (3) to find differences between species, in terms of growth form, life-history strategy and other morphological traits.

    The four vegetation types studied showed different degrees of heterogeneity. The most homogeneous were alpine lichen heaths, the most heterogeneous ones Festuca varia grasslands. There were also considerable differences in species richness and frequency distribution of species.

    The plant species involved had several features in common: most of them are hemicryptophytes, possess a semi-rosette growth form and a sympodial model of shoot formation. Regarding the types of vegetative mobility, species with low mobility prevail in all four vegetation types. Species without mobility rank second and only a few species are highly mobile. Regarding the Serebryakov life-form system and life-history strategy approach, the vegetation types showed considerable differences in the expression offunctional groups.

    The most influential factors were largely linked to the snow-melting gradient. Harsh snowfree conditions prevail in alpine lichen heaths; tussock grasses influence the Festuca grasslands; burrowing activity of rodents is important in the Geranium-Hedysarum meadows and variation in topography/time of snowmelting controls the snowbed vegetation. Factors influencing all vegetation types include the "mass effect", i. e. the input of diaspores from adjacent habitats. Finally, the coexistence of species with different traits expressed in their populations contributes to the biodiversity of the communities.

  • 40.
    Rydin, Håkan
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecological Botany.
    Competition between Sphagnum species under controlled conditions1997In: The Bryologist, ISSN 0007-2745, E-ISSN 1938-4378, Vol. 100, no 3, p. 302-307Article in journal (Other academic)
    Abstract [en]

    Previous field experiments had revealed high between-replicate variability in the outcome of competition among bog inhabiting Sphagnum species. I performed an experiment to test whether competition is more consistent render controlled conditions. Carpets

  • 41.
    Rydin, Håkan
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecological Botany.
    Backéus, Ingvar
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecological Botany.
    Växtbiologi: nu och för 100 år sedan1998In: Svensk Botanisk Tidskrift, ISSN 0039-646X, Vol. 92, p. 1-10Article, review/survey (Other (popular science, discussion, etc.))
  • 42.
    Rydin, Håkan
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecological Botany.
    Diekmann, Martin
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecological Botany.
    Hallingback, T
    Biological characteristics, habitat associations, and distribution of macrofungi in Sweden1997In: Conservation Biology, ISSN 0888-8892, E-ISSN 1523-1739, Vol. 11, no 3, p. 628-640Article in journal (Refereed)
    Abstract [en]

    We conducted a statistical analysis of taxonomic and functional groups, of some ecological characteristics (edaphic factors, macro- and micro-habitats) and of the distribution of macrofungi in Sweden, based on an ecological data catalog of 3196 species. We placed particular emphasis on a comparison of threatened and non-threatened taxa. Differences in the proportions of threatened macrofungi were found among both taxonomic and functional groups, partly explained by a lack of information on some of the groups. A comparatively high proportion of threatened macrofungi is found on dry and base-rich soils. High relative numbers of threatened taxa occur in semi-natural open habitats such as calcareous grasslands and in southern deciduous hardwood forests on high-pH soils. Another habitat type of major importance for red-listed species is the boreal spruce forest. A high proportion of the wood-inhabiting species are red-listed; this is probably a result of the dramatic decrease in decaying wood in Swedish forests during this century. Both the absolute number of species and the absolute and relative numbers of threatened species decrease from south to north. Many functional and habitat characteristics differed between regions. Our overall results were largely consistent with those found for forest plants and animals. Some differences, however, were found when comparing macrofungal characteristics and levels of threat to macrofungi between Sweden and other European countries. Among the main threats to macrofungi in Sweden are modern forestry, the decrease of semi-natural open habitats as a result of changed land management practices, and, in southern Sweden, probably also air pollution.

  • 43.
    Schipperges, B
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecological Botany.
    Rydin, Håkan
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecological Botany.
    Response of photosynthesis of Sphagnum species from contrasting microhabitats to tissue water content and repeated desiccation1998In: New Phytologist, ISSN 0028-646X, E-ISSN 1469-8137, Vol. 140, no 4, p. 677-684Article in journal (Refereed)
    Abstract [en]

    The response of photosynthetic CO2 exchange to tissue water content in five spp. of Sphagnum from contrasting microhabitats (S. fuscum (Schimp.) Klinggr., S. papillosum H. Lindb., S. magellanicum Brid., S. balticum (Russ.) C. Jens. and S. cuspidatum Ehrh. ex Hoffm.) was measured in the laboratory using an infrared gas analyser technique. Experiments were designed to test recovery of net photosynthesis after periodic and long lasting desiccation.

    The contact between capitula and basal parts of the mosses seems to be important for survival. Isolated capitula cut off from any contact with the water table were not able to recover after complete desiccation (at 15°C for 2–4 d). When contact with the water table is lost, e.g. during long periods of desiccation, recovery of net photosynthesis can take place but only if the water content of the capitula does not fall too far below c. 10–20% of the water content at compensation point.

    There was no relationship between the ability of net photosynthesis to recover from desiccation and the wetness of the natural microhabitat. Sphagna survive dry periods by avoidance of drying out by high capillarity or dense growth form (as in S. fuscum).

  • 44.
    Selin, Eva
    Uppsala University, Department of Ecological Botany.
    Morphometric differentiation in Papaver radicatum (Papaveraceae): Geographic pattern and significance for refugial survival theory1999Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The morphometric pattern of variation among and within Scandinavian populations of the alpine species Papaver radicatum was studied. Results from analyses (including multivariate techniques) of capsule and leaf traits of wild-collected and cultivated plants as well as wild-collected seeds show correlated patterns of variation in capsule traits and partly corresponding patterns of variation between capsule and seed traits.

    On the basis of capsule traits of wild-collected and cultivated plants, two groups are distinguished corresponding to their geographic origin. Such a separation is also, though more weakly, revealed by seed shape. Some of the northernmost populations from southern Norway are grouped together with populations from northern Scandinavia, which can be interpreted in terms of a successive fragmentation of a formely wider range of occurrence. A weak regional pattern of variation is found in the leaf characters of cultivated plants. The results do not support the hypothesis of an equivalent degree of intersubspecies differentiation, nor the idea of in situ refugial survival during the Weichselian glaciation.

    The pattern of differentiation indicates: (1) an older origin of the bicentric distribution, (2) separation into geographically isolated groups of populations within each region. The variation in capsule traits would support the idea of refugial survival at the Norwegian coast, but not that in seed shape.

    Maybe the most important factor influencing the dispersal ability and extent of the distribution area of P. radicatum is a change habitat conditions. Possibly open, stony, sparsely vegetated areas, left by the retreated ice-sheet restricted the previously more widely distributed populations during the post-glacial Hypsithermal. Hence, the differentiation pattern may reflect post-glacial events. Similarities in capsuleand seed traits between Icelandic and Scandinavian P. radicatum support mainly the hypothesis of survival on a former North Sea continent, followed by an immigration to Scandinavia, Iceland and the Faeroes.

  • 45.
    Sundberg, Sebastian
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecological Botany.
    Rydin, Håkan
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecological Botany.
    Spore number in Sphagnum and its dependence on spore and capsule size1998In: Journal of Bryology, ISSN 0373-6687, E-ISSN 1743-2820, Vol. 20, no 1, p. 1-16Article in journal (Refereed)
    Abstract [en]

    Spore number in eight species of Sphagnum, representing five taxonomic sections, was investigated in relation to capsule and spore size. Mean spore number ranged from 18,500 in S. tenellum to 243,000 in S. squarrosum. There was considerable intraspecific variation in spore number, which was mainly related to capsule size. The interspecific variation in spore number was determined by both capsule and spore size, with higher numbers of spores in species with large capsules and small spores. Capsule size among species seems to be positively correlated to the size of the capitulum. Spore size showed a strong, positive relationship to capsule size in three species studied, that was fitted by a quadratic regression. The smallest capsule analysed for each of the eight species always had the smallest spores, but in only two species did the largest capsule have the largest spores, further indicating a common curvilinear relationship between spore size and capsule size. The strong relationship (R2=O.98) obtained in a linear regression in which the capsule size to spore size ratio was used to predict spore number in different species, makes it possible to estimate the spore output of other species or populations of Sphagnum, from sizes of capsules and spores. The sizes of spores measured in this study agreed with results obtained in at least one previous study, but were generally smaller than those reported in several other studies. The discrepancy probably depends on the method of spore preparation. The present study identifies potential sources of errors in spore counts and measurements. Measures which help to avoid or correct for errors are evaluated to facilitate further studies.

  • 46.
    Tekle, Kebrom
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecological Botany.
    Ecological rehabilitation of degraded hill slopes in southern Wello, Ethiopia1998Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Clearing of vegetation has left large areas of southern Wello (Ethiopia) at a high risk ofland degradation. In this study, the causes, extent and consequences of land degradationproblems are reviewed. To see land cover changes, aerial photographs from 1958 and1986 were compared with the help of a GIS procedure. By applying multivariateclassification and ordination techniques on the vegetation and environmental datacollected from 65 plots (20x20 m big), the vegetation of the study area was analyzed.Possibilities of ecological rehabilitation were assessed by analyzing results from a soilseed banks experiment and from the study of vegetation dynamics in permanent plots.

    The land cover changes interpreted from the aerial photographs indicated adeterioration of forests, shrublands and riverine vegetation into open areas andsettlements. This deterioration was manifested in the present vegetation types whichincluded forests, woodlands, shrublands, grasslands, degraded and regenerating sites.

    The soil seed banks are dominated by herbs with very few tree and shrub seedlings.A low floristic similarity (Sørensen index 26%) was observed between the seed banksand the standing vegetation. Nevertheless, the seed banks' contribution to initial plantcover can not be underestimated.

    In the permanent plots, an increase in number of individuals and intercept lengthswas recorded. Moreover, there was a strong correlation (r = 0.77) between the interceptlength of the tree/shrub layer and the position of plots on CA - axis 1 of the field layer.

    Ecological rehabilitation of degraded areas in southern Wello will be successful ifthe goals are geared towards sustainable use of the hill slopes rather than focusing onrecovery of the original vegetation. Measures taken in this line can be helpful inwinning the confidence of the local people without whose participation much can not beaccomplished.

  • 47.
    Tekle, Kebrom
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecological Botany.
    Backéus, Ingvar
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecological Botany.
    Skoglund, Jerry
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecological Botany.
    Woldu, Zerihun
    Addis Ababa University.
    Vegetation on hill slopes in southern Wello, Ethiopia: Degradation and regeneration1997In: Nordic Journal of Botany, ISSN 0107-055X, E-ISSN 1756-1051, Vol. 17, no 5, p. 483-493Article in journal (Refereed)
    Abstract [en]

    A study was made of the vegetation in southern Wello (Ethiopia) in relation to human impact and the environment. 65 sample plots were laid out and analysed with respect to the cover value of vascular plant species. Altitude, slope, aspect and estimates of grazing pressure for each plot were also recorded along with physical and chemical soil properties analysed for samples taken from each plot. The following environmental factors, isolated by forward selection, show correlation with the axes of Canonical Correspondence Analysis (CCA): altitude, grazing, pH, K, Ca, Mg, slope and aspect.

    Through hierarchical and non-hierarchical clustering methods the vegetation was divided into eight types, from which one was secondary forest characterised by patch dominance of Juniperus procera and Olea europaea ssp. cuspidata. These forest patches are found at high altitude sites and because of their inaccessibility are usually characterised by low livestock density and consequently low grazing pressure. The presence of large boulders and stones in Podocarpus falcatus forest decreases accessibility and creates natural protection for the trees. The other vegetation types, most of which are found at lower altitude and associated with varying intensities of grazing, include grasslands (grazed and protected), regenerating sites dominated by Euclea racemosa and Dodonaea angustifolia, dense and open shrublands and Olea europaea ssp. cuspidata woodlands. Human interference has a major impact on the vegetation of the study area and its recovery will depend on the degree of participation of the local people.

  • 48.
    Weih, Martin
    Uppsala University, Department of Ecological Botany.
    The nitrogen economy of mountain birch: As related to environmental conditions and genotype1998Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Responses of mountain birch growth to changed environmental conditions arestrongly affected by birch genotype, and nitrogen economy is a key factor influencingthe winter survival of first-year seedlings. These are some of the findings of a series ofstudies, in which growth, nitrogen economy and winter survival were analysed usingpot-grown seedlings of mountain birch (Betula pubescens ssp. czerepanovii) exposedto various environmental conditions in northern Sweden. Differences between birchgenotypes were studied at the individual, ecotype and provenance levels. Theexperimental factors included temperature, nutrient availability and ultravioletradiation. In addition, the influence of neighbouring vegetation on birch nitrogeneconomy was evaluated. Nutrient availability and temperature were recorded in situduring one year in three mountain birch woodland soils.

    Environmental effects on nitrogen economy varied between years, during agrowing season and between seedling age groups. In many cases differences in growthbetween birch genotypes were only apparent under certain types of environmentalconditions. An interaction between genotype and environment was apparent in thecase of elevational ecotypes. Thus, an increase in leaf nitrogen content with altitudewas attributed to both a phenotypic adjustment and a genetic adaptation to decreasingtemperature.

    The rate of nitrogen accumulation in mountain birch during the growingseason determined the survival rate of first-year seedlings the following winter. Theenvironmental conditions, neighbouring vegetation, and genotype all affected thenitrogen accumulation rate of young seedlings and could influence their survival. Soiltemperature was concluded to have a major influence on the survival of young birchseedlings owing to its strong impact on the root nitrogen uptake rate.

  • 49.
    Woldu, Zerihun
    et al.
    Addis Ababa University.
    Backéus, Ingvar
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecological Botany.
    The shrubland vegetation in western Shewa, Ethiopia and its possible recovery1991In: Journal of Vegetation Science, ISSN 1100-9233, E-ISSN 1654-1103, Vol. 2, no 2, p. 173-180Article in journal (Refereed)
    Abstract [en]

    Shrubland vegetation and environmental data in western Shewa, Ethiopia have been analysed. Vegetation data include cover-abundance values of vascular plant species; en- vironmental data comprise physical and chemical properties of the soil, altitude, slope, grazing and browsing pressure.

    The vegetation data were subjected to hierarchical and non-hierarchical classification and ordination with correspondence analysis. The classification resulted in seven different vegetation types, ranging from grassland with scattered shrubs to degen- erated forest. Ordination of the data and biplot analysis showed that the vegetation is influenced by anthropogenic factors and altitudinal variation. Sand content is related to a low level of anthropogenic influence whereas silt content is related to a high level. This is explained by historical events rather than by the present situation. Total nitrogen, organic carbon, altitude and slope are positively correlated and these variables are negatively related to anthropogenic influences.

    The shrubland vegetation may have expanded from lower altitudes and drier sites as forests gradually disappeared.

    The recovery of an economically more rewarding vegetation type may be achieved through providing alternative sources of fuel and construction and through prohibiting cultivation and grazing in the shrublands on the hillsides. Regeneration can be accelerated by actively introducing seedlings of tree species that do not need a heavy canopy cover for establishment and growth.

  • 50.
    Zamfir, Manuela
    Uppsala University, Department of Ecological Botany.
    From pattern to process: Studies on limestone grassland, with emphasis on the bryophyte-lichen layer and its effects on vascular plants1999Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Patterns in space and time at different scales in the bryophyte-lichen layer, aud multi-species spatial patterns of bryophytes, lichens and vascular plants were studied in Avenetum limestone grassland on the Great Alvar of the Baltic Island of Öland, south-eastem Sweden.

    Spatiotemporal patterns of bryophytes and Iichens in grazed and ungrazed alvar grassland demonstrated that dominant species forming large patches were relatively stable in time, whereas less frequent species forming small patches were more mobile. Many species showed a high cumulative frequency at both sites, which supported the Carousel model concerning within-community species dynamics. In the grazed grassland none of the species showed a clear decline over time. Bryophytes characteristic of grazed grassland yet occurring in theungrazed site, had greater losses than gains at both small (16 cm2) and larger (1024 cm2) scales. This, together with an increase in the number of negative bryophyte associations over two years, suggests that competition between bryophyte species might occur in ungrazed grasslands.

    Multi-species patterns of bryophytes and lichens, vascular plants, and of all species together, based on 100 cm2 plots, were detected by Detrended Correspondence Analysis followed by pattern analysis with the program PASFRAN. Cryptogams and phanerogams together formed multi-species patterns that differed from those of the two vegetation layers when analysed separately. This suggests that interactions between cryptogams and phanerogams may occor.

    Greenhouse experiments with artificial bryophyte communities at different densities showed that alvar bryophytes are organised in a competitive hierarchy. There were significant effects of interactions at the community level; hence interactions between species may affect bryophyte community composition.

    Additional greenhouse experiments showed that both mosses and lichens might negatively affect seedling emergence of certain vascular plant species. Removal experiments conducted in the field also showed that mosses and lichens were able to hinder the recruitment and growth of both short-lived and long-lived phanerogams, and to reduce species richness. However, only lichens and not bryophytes affected phanerogam biomass negatively.

    In conclusion, it is suggested that interactions between species and vegetation layers might be one of the factors structuring both the bryophyte-lichen and the vascular plant layers in the studied limestone grassland community.

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