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  • 1.
    Bengtsson, Fia
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Plant Ecology and Evolution.
    Granath, Gustaf
    Department of Ecology, Swedish University of Agricultural Sciences, Uppsala, Sweden.
    Rydin, Håkan
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Plant Ecology and Evolution.
    Photosynthesis, growth, and decay traits in Sphagnum – a multispecies comparison2016In: Ecology and Evolution, ISSN 2045-7758, E-ISSN 2045-7758, Vol. 6, no 10, p. 3325-3341Article in journal (Refereed)
    Abstract [en]

    Peat mosses (Sphagnum) largely govern carbon sequestration in Northern Hemisphere peatlands. We investigated functional traits related to growth and decomposition in Sphagnum species. We tested the importance of environment and phylogeny in driving species traits and investigated trade-offs among them. We selected 15 globally important Sphagnum species, representing four sections (subgenera) and a range of peatland habitats. We measured rates of photosynthesis and decomposition in standard laboratory conditions as measures of innate growth and decay potential, and related this to realized growth, production, and decomposition in their natural habitats. In general, we found support for a trade-off between measures of growth and decomposition. However, the relationships are not strong, with r ranging between 0.24 and 0.45 for different measures of growth versus decomposition. Using photosynthetic rate to predict decomposition in standard conditions yielded R2 = 0.20. Habitat and section (phylogeny) affected the traits and the trade-offs. In a wet year, species from sections Cuspidata and Sphagnum had the highest production, but in a dry year, differences among species, sections, and habitats evened out. Cuspidata species in general produced easily decomposable litter, but their decay in the field was hampered, probably due to near-surface anoxia in their wet habitats. In a principal components analysis, PCA, photosynthetic capacity, production, and laboratory decomposition acted in the same direction. The species were imperfectly clustered according to vegetation type and phylogeny, so that some species clustered with others in the same section, whereas others clustered more clearly with others from similar vegetation types. Our study includes a wider range of species and habitats than previous trait analyses in Sphagnum and shows that while the previously described growth–decay trade-off exists, it is far from perfect. We therefore suggest that our species-specific trait measures offer opportunities for improvements of peatland ecosystem models. Innate qualities measured in laboratory conditions translate differently to field responses. Most dramatically, fast-growing species could only realize their potential in a wet year. The same species decompose fast in laboratory, but their decomposition was more retarded in the field than that of other species. These relationships are crucial for understanding the long-term dynamics of peatland communities.

  • 2.
    Bengtsson, Fia
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Plant Ecology and Evolution.
    Rydin, Håkan
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Plant Ecology and Evolution.
    Hajek, Tomas
    Univ South Bohemia, Dept Expt Plant Biol, Fac Sci, Branisovska 1760, CZ-37005 Ceske Budejovice, Czech Republic;Czech Acad Sci, Inst Bot, Dept Funct Ecol, Dukelska 135, CZ-37982 Trebon, Czech Republic.
    Biochemical determinants of litter quality in 15 species of Sphagnum2018In: Plant and Soil, ISSN 0032-079X, E-ISSN 1573-5036, Vol. 425, no 1-2, p. 161-176Article in journal (Refereed)
    Abstract [en]

    Background and aims Sphagnum mosses are ecosystem engineers that create and maintain boreal peatlands. With unique biochemistry, waterlogging and acidifying capacities, they build up meters-thick layers of peat, reducing competition and impeding decomposition. We quantify within-genus differences in biochemical composition to make inferences about decay rates, related to hummock-hollow and fen-bog gradients and to phylogeny. Methods We sampled litter from 15 Sphagnum species, abundant over the whole northern hemisphere. We used regression and Principal Components Analysis (PCA) to evaluate general relationships between litter quality parameters and decay rates measured under laboratory and field conditions. Results Both concentrations of the polysaccharide sphagnan and the soluble phenolics were positively correlated with intrinsic decay resistance, however, so were the previously understudied lignin-like phenolics. More resistant litter had more of all the important metabolites; consequently, PC1 scores were related to lab mass loss (R-2 = 0.57). There was no such relationship with field mass loss, which is also affected by the environment. PCA also revealed that metabolites clearly group Sphagnum sections (subgenera). Conclusions We suggest that the commonly stated growth-decomposition trade-off is largely due to litter quality. We show a strong phylogenetic control on Sphagnum metabolites, but their effects on decay are affected by nutrient availability in the habitat.

  • 3. Bengtsson, J.
    et al.
    Fagerström, T.
    Rydin, Håkan
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Plant Ecology and Evolution.
    Competition and coexistence in plant communities1994In: Trends in Ecology & Evolution, Vol. 9, p. 246-250Article in journal (Refereed)
  • 4. Berendse, F
    et al.
    van Breemen, N
    Rydin, Håkan
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Evolution, Ecological Botany.
    Buttler, A
    Heijmans, M
    Hoosbeek, MR
    Lee, JA
    Mitchell, E
    Saarinen, T
    Vasander, H
    Wallen, B
    Raised atmospheric CO2 levels and increased N deposition cause shifts in plant species composition and production in Sphagnum bogs2001In: Global Change Biology, ISSN 1354-1013, E-ISSN 1365-2486, Vol. 7, no 5, p. 591-598Article in journal (Refereed)
    Abstract [en]

    Part of the missing sink in the global CO2 budget has been attributed to the positive effects of CO2 fertilization and N deposition on carbon sequestration in Northern Hemisphere terrestrial ecosystems. The genus Sphagnum is one of the most important groups of plant species sequestrating carbon in temperate and northern bog ecosystems, because of the low decomposability of the dead material it produces. The effects of raised CO2 and increased atmospheric N deposition on growth of Sphagnum and other plants were studied in bogs at four sites across Western Europe. Contrary to expectations, elevated CO2 did not significantly affect Sphagnum biomass growth. Increased N deposition reduced Sphagnum mass growth, because it increased the cover of vascular plants and the tall moss Polytrichum strictum. Such changes in plant species composition may decrease carbon sequestration in Sphagnum-dominated bog ecosystems.

  • 5. Borgegård, S.-O.
    et al.
    Morander, R.
    Rydin, Håkan
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Plant Ecology and Evolution.
    Vegetationen på skär bildade vid Hjälmarsänkningen i hundraårigt perspektiv1987In: Årsbok 1987, Hembygdsföreningen Arboga Minne , 1987Chapter in book (Refereed)
  • 6. Borgegård, S.-O.
    et al.
    Rydin, Håkan
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Plant Ecology and Evolution.
    Biomass, root penetration and heavy metal uptake in birch in a soil cover over copper tailings1989In: Journal of Applied Ecology, Vol. 26, p. 585-595Article in journal (Refereed)
  • 7. Borgegård, S.-O.
    et al.
    Rydin, Håkan
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Plant Ecology and Evolution.
    Utilization of waste products and inorganic fertilizer in the restoration of iron-mine tailings1989In: Journal of Applied Ecology, Vol. 26, p. 1083-1088Article in journal (Refereed)
  • 8. Bragazza, L
    et al.
    Limpens, J
    Gerdol, R
    Grosvernier, P
    Hájek, M
    Hájek, T
    Hajkova, P
    Hansen, I
    Iacumin, P
    Kutnar, L
    Rydin, Håkan
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Faculty of Science and Technology, Biology, Department of Ecology and Evolution. Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Faculty of Science and Technology, Biology, Department of Ecology and Evolution, Plant Ecology.
    Tahvanainen, T
    Nitrogen concentration and delta(15)N signature of ombrotrophic Sphagnum mosses at different N deposition in Europe2005In: Global Change Biology, Vol. 11, p. 106-114Article in journal (Refereed)
  • 9. Bragazza, L
    et al.
    Rydin, Håkan
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Faculty of Science and Technology, Biology, Department of Ecology and Evolution. Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Faculty of Science and Technology, Biology, Department of Ecology and Evolution, Plant Ecology.
    Gerdol, R
    Multiple gradients in mire vegetation: a comparison of a Swedish and an Italian bog2005In: Plant Ecology, Vol. 177, p. 223-236Article in journal (Refereed)
  • 10. Bragazza, L
    et al.
    Tahvanainen, T
    Kutnar, L
    Rydin, Håkan
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Faculty of Science and Technology, Biology, Department of Evolutionary Biology. Department of Ecology and Evolution, Plant Ecology. Växtekologi.
    Limpens, J
    Nutritional constraints in ombrotrophic Sphagnum plants under increasing atmospheric nitrogen deposition in Europe2004In: New Phytologist, Vol. 163, p. 609-616Article in journal (Refereed)
  • 11. Bragazza, Luca
    et al.
    Freeman, Chris
    Jones, Timothy
    Rydin, Håkan
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Evolution, Ecological Botany.
    Limpens, Juul
    Fenner, Nathalie
    Ellis, Tim
    Gerdol, Renato
    Hajek, Michal
    Hajek, Tomas
    Lacumin, Paola
    Kutnar, Lado
    Tahvanainen, Teemu
    Toberman, Hannah
    Atmospheric nitrogen deposition promotes carbon loss from peat bogs2006In: Proceedings of the National Academy of Sciences of the United States of America, ISSN 0027-8424, E-ISSN 1091-6490, Vol. 103, no 51, p. 19386-19389Article in journal (Refereed)
    Abstract [en]

    Peat bogs have historically represented exceptional carbon (C) sinks because of their extremely low decomposition rates and consequent accumulation of plant remnants as peat. Among the factors favoring that peat accumulation, a major role is played by the chemical quality of plant litter itself, which is poor in nutrients and characterized by polyphenols with a strong inhibitory effect on microbial breakdown. Because bogs receive their nutrient supply solely from atmospheric deposition, the global increase of atmospheric nitrogen (N) inputs as a consequence of human activities could potentially alter the litter chemistry with important, but still unknown, effects on their C balance. Here we present data showing the decomposition rates of recently formed litter peat samples collected in nine European countries under a natural gradient of atmospheric N deposition from approximate to 0.2 to 2 g center dot m(-2)center dot yr(-1). We found that enhanced decomposition rates for material accumulated under higher atmospheric N supplies resulted in higher carbon dioxide (CO2) emissions and dissolved organic carbon release. The increased IN availability favored microbial decomposition (i) by removing N constraints on microbial metabolism and (ii) through a chemical amelioration of litter peat quality with a positive feedback on microbial enzymatic activity. Although some uncertainty remains about whether decay-resistant Sphagnum will continue to dominate litter peat, our data indicate that, even without such changes, increased N deposition poses a serious risk to our valuable peatland C sinks.

  • 12. Bragazza, Luca
    et al.
    Gerdol, Renato
    Rydin, Håkan
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Evolutionary Biology.
    Effects of mineral and nutrient input on mire bio-geochemistry in two geographical regions2003In: Journal of Ecology, ISSN 0022-0477, E-ISSN 1365-2745, Vol. 91, no 3, p. 417-426Article in journal (Refereed)
    Abstract [en]

    1 We assessed the role of climatic conditions and the effects of different, long-term atmospheric depositions in controlling the mineral and nutrient contents in pore-water, surface peat and in living Sphagna at a boreo-nemoral mire in Sweden and an alpine mire in Italy.

    2 The terrestrial contribution of Ca2+, Mg2+ and SO42- in bulk precipitation was much greater at the Italian mire, in accordance with the different bedrock in the region and the higher level of atmospheric pollution.

    3 At both mires, the contribution of bulk precipitation to the concentration of major ions in mire pore-water was much greater in the ombrotrophic than in the minerotrophic part, because of the raised morphology of the mires, which limited the inflow of mineral soil water to the margins. The only ions strongly depleted in mire pore-water compared with precipitation were K+, NO3- and NH4+ and these were therefore limiting to plant growth.

    4 Higher SO42- concentration in pore-water at the Swedish mire, which experienced lower atmospheric inputs of sulphate, was probably caused by oxidative processes during a long dry period in the summer before sampling.

    5 Higher rates of NO3-, NH4+, as well as SO42- atmospheric inputs at the Italian mire were reflected in significantly higher N and, partly, S concentrations in ombrotrophic Sphagna. Higher NO3- concentration in pore-water at the Italian mire was associated with a lower N retention coefficient of the ombrotrophic Sphagnum plants, suggesting a reduced nitrogen filtering ability of the moss layer.

  • 13. Bu, Z
    et al.
    Yang, Y
    Rydin, Håkan
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Faculty of Science and Technology, Biology, Department of Ecology and Evolution. Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Faculty of Science and Technology, Biology, Department of Ecology and Evolution, Plant Ecology.
    Lang, H
    Age structures of modules of clonal peatland sedge Carex middendorffii2005In: Chinese Geographical Science, Vol. 15, p. 269-274Article in journal (Refereed)
  • 14. Bu, Zhaojun
    et al.
    Chen, Xu
    Rydin, Hakan
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Plant Ecology and Evolution.
    Wang, Shengzhong
    Ma, Jinze
    Zeng, Jing
    Performance of four mosses in a reciprocal transplant experiment: implications for peatland succession in NE China2013In: Journal of Bryology, ISSN 0373-6687, E-ISSN 1743-2820, Vol. 35, p. 220-227Article in journal (Refereed)
    Abstract [en]

    Sphagnum dominates the moss layer in northern peatlands, but its dominance has decreased while there has been an expansion of other moss genera in some peatlands of NE China since the 1960s. To discover the mechanisms underlying this succession, we performed a four-month reciprocal transplant experiment in Hani Peatland with three Sphagnum species, Sphagnum palustre, S. magellanicum, and S. fuscum and one other moss Polytrichum strictum. Performance of the four mosses and the environmental factors: height above water table (HWT), vascular plant cover and pH, electrical conductivity, base cations, and N and P concentrations in water in the four moss habitats were measured. Biomass production in S. palustre was negatively affected by HWT. Phosphorus had a positive effect on biomass production in S. magellanicum and Polytrichum. None of the environmental factors had any effect on S. fuscum. Overall, the three Sphagnum species deteriorated in P. strictum hummocks, while P. strictum exhibited a wider ecological amplitude and maintained or increased its vigour levels in Sphagnum hummocks. Biomass production in S. palustre and S. magellanicum was negatively affected by P. strictum indicating the competitive ability of P. strictum. Our results suggest that its wide ecological amplitude and competitive ability may explain why P. strictum can expand and replace Sphagnum in some northern peatlands.

  • 15. Bu, Zhao-Jun
    et al.
    Rydin, Håkan
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Plant Ecology and Evolution.
    Chen, Xu
    Direct and interaction-mediated effects of environmental changes on peatland bryophytes2011In: Oecologia, ISSN 0029-8549, E-ISSN 1432-1939, Vol. 166, no 2, p. 555-563Article in journal (Refereed)
    Abstract [en]

    Ecosystem processes of northern peatlands are largely governed by the vitality and species composition in the bryophyte layer, and may be affected by global warming and eutrophication. In a factorial experiment in northeast China, we tested the effects of raised levels of nitrogen (0, 1 and 2 g m(-2) year(-1)), phosphorus (0, 0.1 and 0.2 g m(-2) year(-1)) and temperature (ambient and +3A degrees C) on Polytrichum strictum, Sphagnum magellanicum and S. palustre, to see if the effects could be altered by inter-specific interactions. In all species, growth declined with nitrogen addition and increased with phosphorus addition, but only P. strictum responded to raised temperature with increased production of side-shoots (branching). In Sphagnum, growth and branching changed in the same direction, but in Polytrichum, the two responses were uncoupled: with nitrogen addition there was a decrease in growth (smaller than in Sphagnum) but an increase in branching; with phosphorus addition growth increased but branching was unaffected. There were no two-way interactions among the P, N and T treatments. With increasing temperature, our results indicate that S. palustre should decrease relative to P. strictum (Polytrichum increased its branching and had a negative neighbor effect on S. palustre). With a slight increase in phosphorus availability, the increase in length growth and production of side-shoots in P. strictum and S. magellanicum may give them a competitive superiority over S. palustre. The negative response in Sphagnum to nitrogen could favor the expansion of vascular plants, but P. strictum may endure thanks to its increased branching.

  • 16. Bu, Zhao-Jun
    et al.
    Zheng, Xing-Xing
    Rydin, Håkan
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Plant Ecology and Evolution.
    Moore, Tim
    Ma, Jinze
    Facilitation vs. competition: Does interspecific interaction affect drought responses in Sphagnum?2013In: Basic and Applied Ecology, ISSN 1439-1791, E-ISSN 1618-0089, Vol. 14, no 7, p. 574-584Article in journal (Refereed)
    Abstract [en]

    The stress-gradient hypothesis (SGH) predicts that the relative importance of competition decreases and facilitation increases with an increase in abiotic stress. In peatlands, Sphagnum faces the threat of drought and differentiates into hummock species (drought-tolerant) and hollow species. Whether interspecific interaction affects the influence of drought on bryophyte composition in peatlands is unknown. We established an experiment by simulating drought and building bryophyte communities with two hummock species (S. palustre and S. capillifolium) and one hollow species (S. fallax). In all three species, drought decreased biomass production, height increment and side-shoot production. Sphagnum stores water in the hyaline cells, and leaf hyaline cell percentage (HCP) in the two hummock species increased with drought while no effect was found in S. fallax, suggesting that adjusting HCP is not an effective response to drought for the hollow species. Morphological traits and carbon and nitrogen contents in hummock species responded more to drought than in the hollow species, indicating a rapid response in phenotypic plasticity is an important strategy to resist drought in the hummock species. The presence of neighboring Sphagnum species, rather than drought, decreased carbon content for all three species. All three bryophytes showed interaction between drought and neighbor in two or more plant traits. Our study, however, did not support SGH, and there were no changes from competition under wet to facilitation under dry treatments in any of the six species combinations. On the contrary, when S. fallax was the target species, a change from facilitation under wet to competition under dry treatments was observed. The results suggest that hummock species can facilitate hollow species in wet environments but they could suppress hollow species under drought conditions by competing for water resources. Both drought and strong competition are the probable reasons why hollow species rarely grow in hummocks.

  • 17. Caruso, Alexandro
    et al.
    Rudolphi, Jörgen
    Rydin, Håkan
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Plant Ecology and Evolution.
    Positive Edge Effects on Forest-Interior Cryptogams in Clear-Cuts2011In: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 6, no 11, p. e27936-Article in journal (Refereed)
    Abstract [en]

    Biological edge effects are often assessed in high quality focal habitats that are negatively influenced by human-modified low quality matrix habitats. A deeper understanding of the possibilities for positive edge effects in matrix habitats bordering focal habitats (e.g. spillover effects) is, however, essential for enhancing landscape-level resilience to human alterations. We surveyed epixylic (dead wood inhabiting) forest-interior cryptogams (lichens, bryophytes, and fungi) associated with mature old-growth forests in 30 young managed Swedish boreal forest stands bordering a mature forest of high conservation value. In each young stand we registered species occurrences on coarse dead wood in transects 0-50 m from the border between stand types. We quantified the effect of distance from the mature forest on the occurrence of forest-interior species in the young stands, while accounting for local environment and propagule sources. For comparison we also surveyed epixylic open-habitat (associated with open forests) and generalist cryptogams. Species composition of epixylic cryptogams in young stands differed with distance from the mature forest: the frequency of occurrence of forest-interior species decreased with increasing distance whereas it increased for open-habitat species. Generalists were unaffected by distance. Epixylic, boreal forest-interior cryptogams do occur in matrix habitats such as clear-cuts. In addition, they are associated with the matrix edge because of a favourable microclimate closer to the mature forest on southern matrix edges. Retention and creation of dead wood in clear-cuts along the edges to focal habitats is a feasible way to enhance the long-term persistence of epixylic habitat specialists in fragmented landscapes. The proposed management measures should be performed in the whole stand as it matures, since microclimatic edge effects diminish as the matrix habitat matures. We argue that management that aims to increase habitat quality in matrix habitats bordering focal habitats should increase the probability of long-term persistence of habitat specialists.

  • 18. Cronberg, Nils
    et al.
    Rydin, Håkan
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Faculty of Science and Technology, Biology, Department of Ecology and Evolution. Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Faculty of Science and Technology, Biology, Department of Ecology and Evolution, Plant Ecology. Växtekologi.
    Sphagnum borde heta torvmossa på svenska2006In: Svensk Botanisk Tidskrift, Vol. 100, p. 299-300Article in journal (Other (popular scientific, debate etc.))
  • 19. Cronberg, Nils
    et al.
    Rydin, Håkan
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Faculty of Science and Technology, Biology, Department of Ecology and Evolution. Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Faculty of Science and Technology, Biology, Department of Ecology and Evolution, Plant Ecology.
    Torvmossa - ett nygammalt svenskt namn för Sphagnum2005In: Svensk Botanisk Tidskrift, Vol. 99, p. 290-294Article in journal (Refereed)
  • 20. Dahlström, A.
    et al.
    Borgegård, S.-O.
    Rydin, Håkan
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Plant Ecology and Evolution.
    Kärlväxtfloran på nedlagda ängar och åkrar vid torp i Kilsbergen efter 50 och 90 års igenväxning1998In: Svensk Botanisk Tidskrift, Vol. 91, p. 211-226Article in journal (Refereed)
  • 21.
    Dahlström, Anna
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Swedish Biodiversity Centre.
    Rydin, Håkan
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Ecological Botany.
    Borgegård, Sven-Olov
    Remnant habitats for grassland species in an abandoned Swedish agricultural landscape2010In: Applied Vegetation Science, ISSN 1402-2001, E-ISSN 1654-109X, Vol. 13, no 3, p. 305-314Article in journal (Refereed)
    Abstract [en]

    Questions: Which factors influence the persistence of vascular grassland plants in long-abandoned (at least 50 yr) arable fields and meadows? What might be the implications of current levels of species richness on abandoned arable fields and meadows for future restoration?

    Location: Forested highlands of Kilsbergen, south central Sweden.

    Methods: The abundance of all vascular plant species was investigated in three habitat types: former arable fields, hay meadows and outlands (pastures) at 27 farms, abandoned for either approximately 50 yr or 90 yr. Time since abandonment, tree cover, soil depth, degree of soil podsol development, size of the infield area and two measures of connectivity were used as predictors for species richness and species composition.

    Results: Former outland had denser tree cover, fewer species and fewer grassland species than former arable fields and hay meadows, irrespective of time since abandonment. Former hay meadows and arable fields with a longer time since abandonment were less rich in species, more wooded and had greater podsolization than meadows and fields abandoned at a later stage. Species richness was higher in hay meadows and arable fields at farms with larger infield area and deeper soils compared with farms with smaller infield area and shallower soils. The greatest richness of species and most open habitat were former arable fields at larger farms abandoned 50 yr before the study. Former arable fields had the highest number of grassland species.

    Conclusion: After 50 yr of abandonment, former arable fields were the most important remnant habitats for grassland species and may be a more promising target for restoration than formerly managed grasslands.

  • 22. Ecke, F
    et al.
    Rydin, Håkan
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Evolutionary Biology, Plant Ecology.
    Succession on a land uplift coast in relation to plant strategy theory2000In: Annales Botanici Fennici, ISSN 0003-3847, E-ISSN 1797-2442, Vol. 37, no 3, p. 163-171Article in journal (Refereed)
    Abstract [en]

    Plant strategies under succession were evaluated for communities on rising seashores of the northern Gulf of Bothnia, Sweden, representing sites of primary succession. The succession could not be explained by Grime's CSR model. Early successional stages were neither characterized by high incidence of ruderals as proposed for secondary successions, nor by the dominance of stress tolerators, as proposed for primary successions. Short-lived species were almost totally absent. Instead, the shore habitat was characterized by species with an ability to tolerate and vegetatively recover from disturbance. The way in which different species experience one and the same form of stress or disturbance is an important reason why the classification on the basis of stress and disturbance seems to be insufficient to explain the course of this succession. Dominants of early and late successional stages differed with respect to root system, breeding system, leaf longevity and growth form (graminioid, herb).

  • 23. Ekbohm, G.
    et al.
    Rydin, Håkan
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Plant Ecology and Evolution.
    On estimating the species-area relationship: commenting Loehle1990In: Oikos, Vol. 57, p. 145-146Article in journal (Refereed)
  • 24.
    Emsens, Willem-Jan
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics. Univ Antwerp, Dept Biol, Ecosyst Management Res Grp, Univ Pl 1C, B-2610 Antwerp, Belgium.
    Aggenbach, Camiel J. S.
    Univ Antwerp, Dept Biol, Ecosyst Management Res Grp, Univ Pl 1C, B-2610 Antwerp, Belgium;KWR Watercycle Res Inst, POB 1072, NL-3430 BB Nieuwegein, Netherlands.
    Rydin, Håkan
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Plant Ecology and Evolution.
    Smolders, Alfons J. P.
    Radboud Univ Nijmegen, Inst Wetland & Water Res, Dept Aquat Ecol & Environm Biol, Heyendaalseweg 135-1, NL-6525 ED Nijmegen, Netherlands;B WARE Res Ctr, Toernootveld 1, NL-6525 ED Nijmegen, Netherlands.
    van Diggelen, Rudy
    Univ Antwerp, Dept Biol, Ecosyst Management Res Grp, Univ Pl 1C, B-2610 Antwerp, Belgium.
    Competition for light as a bottleneck for endangered fen species: An introduction experiment2018In: Biological Conservation, ISSN 0006-3207, E-ISSN 1873-2917, Vol. 220, p. 76-83Article in journal (Refereed)
    Abstract [en]

    Many endangered plant species remain absent in rewetted, previously drained fens. We performed a 3-year introduction experiment with endangered fen species (9 Carex- and 6 bryophyte species) in 4 hydrologically restored fens to investigate which factors hamper establishment and survival. Carex species were introduced as adults and seedlings, mosses as gametophytes. Introductions were done on (initially) bare soil, which allowed us to exclude excessive competition for light during the first year. First year survival of the transplants was high in all fens (mean survival = 96%), indicating that there were no direct abiotic constraints on establishment. However, survival analysis revealed that a decrease in relative light intensity (RLI) at the soil surface during consecutive years (indicating an increase in biotic competition for light) drove high mortality rates in most species. As a result, overall final survival was lowest in the two most productive (low light) fens (mean survival = 38%), while most transplants persisted in the two less productive (high light) fens (mean survival = 79%). Taller and faster-growing Carex species were able to outgrow light limitation near the soil surface, and thus had a higher overall survivability than smaller and slower-growing species. Light limitation also drove the loss of 5 out of 6 bryophyte species. We conclude that both dispersal limitation and asymmetric competition for light may explain the lack and loss of small and endangered plant species in rewetted fens. A minimum empirical threshold of c. 30% relative light intensity near the soil surface is required for successful introduction.

  • 25. Falkengren-Grerup, U.
    et al.
    Ericson, L.
    Gunnarsson, U.
    Nordin, A.
    Rydin, Håkan
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Plant Ecology and Evolution.
    Wallén, B.
    Does nitrogen deposition change the flora?2000In: Effects of nitrogen deposition on forest ecosystems, Stockholm: Naturvårdsverket , 2000Chapter in book (Refereed)
  • 26. Falkengren-Grerup, U.
    et al.
    Ericson, L.
    Gunnarsson, U.
    Nordin, A.
    Rydin, Håkan
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Plant Ecology and Evolution.
    Wallén, B.
    Förändras floran av kvävenedfallet?2000In: Effekter av kvävenedfall på skogsekosystem, Stockholm: Naturvårdsverket , 2000Chapter in book (Refereed)
  • 27.
    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.

  • 28.
    Frost, Ingela
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Evolutionary Biology, Plant Ecology.
    Rydin, Håkan
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Evolutionary Biology, Plant Ecology.
    Spatial pattern and size distribution of the animal-dispersed tree Quercus robur in two spruce-dominated forests2000In: Ecoscience, ISSN 1195-6860, Vol. 7, no 1, p. 38-44Article in journal (Refereed)
    Abstract [en]

    We investigated the degree to which the spatial distribution of oaks (Quercus robur L.) was related to habitat conditions, as reflected by vegetation type and structural features presumed to attract animal dispersers (trails, community borders). We hypothesized that the distribution pattern of oaks, with their potential to establish in many habitats, depends on the behaviour of the dispersing animals to a greater extent than micro-habitat conditions. One 100 m x 100 m plot was surveyed in each of two coniferous forests in east-central Sweden. No adult oak trees grew in the forests; all oaks were considered as dispersed into the plots by animals. We tested whether oak distribution was clumped with spatial autocorrelation analyses and whether oak distribution was related to vegetation type, species composition, tree cover, distance to nearest fertile oak tree, or distance to animal trails. Our study showed that oak trees were also spatially aggregated in a small-scale context. The spatial distribution of seedlings and older trees were associated with species richness and tree cover but not with any specific vegetation type, even though fewer oaks than expected grew in spruce forest habitats. Furthermore, we found that oak trees were associated with trails. There were differences in oak distribution between the two study sites in total number of oaks, the number of first-year seedlings, caches, and oak occurrence in relation to species richness and distance to nearest fertile oak. Seed-dispersing animals seem to be of importance for oak distribution even though animal activities seem to differ between sites.

  • 29.
    Granath, Gustaf
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Plant Ecology and Evolution.
    Strengbom, Joachim
    Swedish University of Agricultural Sciences.
    Rydin, Håkan
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Plant Ecology and Evolution.
    Direct physiological effects of nitrogen on Sphagnum: a greenhouse experiment2012In: Functional Ecology, ISSN 0269-8463, E-ISSN 1365-2435, Vol. 26, no 2, p. 353-364Article in journal (Refereed)
    Abstract [en]

    1. Bogs are nutrient-poor peatland ecosystems that are sensitive to nitrogen (N) deposition. Production of peat mosses (i.e. the peat-forming genus Sphagnum) is known to decrease under elevated N deposition, but the causal mechanisms are poorly understood. 2. It is predicted that increased N deposition will cause changes in Sphagnum species composition, with fast-growing species benefiting from increased N availability in contrast to slow-growing species. Knowledge of species-specific responses to N availability can help us to understand interspecific competitive relationships. 3. We investigated the direct effects of N application on plant physiology in three Sphagnum species by exposing shoots to a range of N doses (corresponding to depositions of 0-5 6 g m) 2 year) 1), over 5 months, in a greenhouse experiment. The species investigated included one that grows high above the water-table (Sphagnum fuscum) and two that grow lower down (Sphagnum balticum and Sphagnum fallax). S. fuscum and S. balticum originate from ombrotrophic and S. fallax from minerotrophic environments. To estimate N responses, we measured the performance and light-capture kinetics of the photosynthetic apparatus (maximum photosynthetic rate and Fv/Fm), biomass production, shoot formation, and N and phosphorus (P) concentrations in the tissue. 4. Tissue nitrogen concentration generally increased with N application rate, and photosynthetic rate increased with N concentration, although S. balticum exhibited a unimodal response. With respect to production, a negative response to N application rate was found in S. fallax and S. fuscum (weak), while production in S. balticum was unrelated to application rate. S. fallax was the fastest-growing species, producing two to three times more biomass per shoot compared with the other species. 5. The mismatch between photosynthetic capacity and production could partly be explained by an increased N : P ratio following N application. Phosphorus limitation may not negatively affect photosynthetic capacity, but may hamper production. 6. The fast-growing species S. fallax is considered to benefit from increased N deposition, but we found a negative physiological response, suggesting stoichiometric constraints. Thus, we conclude that responses to N deposition cannot be predicted in a simple way from physiological traits related to growth rate without considering local environmental factors. 

  • 30.
    Granath, Gustaf
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Plant Ecology and Evolution.
    Strengbom, Joachim
    Rydin, Håkan
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Plant Ecology and Evolution.
    Rapid ecosystem shifts in peatlands: Linking plant physiology and succession2010In: Ecology, ISSN 0012-9658, E-ISSN 1939-9170, Vol. 91, no 10, p. 3047-3056Article in journal (Refereed)
    Abstract [en]

    Stratigraphic records from peatlands suggest that the shift from a rich fen (calcareous fen) to an ombrotrophic bog can occur rapidly. This shift constitutes a switch from a species-rich ecosystem to a species-poor one with greater carbon storage. In this process, the invasion and expansion of acidifying bog species of Sphagnum (peat mosses) play a key role. To test under what conditions an acidifying bog species could invade a rich fen, we conducted three experiments, contrasting the bog species S. fucsum with the rich-fen species S. warnstorfii and S. teres. We first tested the effect of calcareous water by growing the three species at different constant height above the water table (HWT; 2, 7, and 14 cm) in a rich-fen pool and measured maximum photosynthetic rate and production and difference in length growth as an indicator of competition. In none of the species was the photosynthetic capacity negatively affected when placed at low HWT, but S. fuscum was a weaker competitor at low HWT. In our second experiment we transplanted the three species into microhabitats with different and naturally varying HWT in a rich fen. Here, S. fuscum nearly ceased to photosynthesize when transplanted to low HWT (brown moss carpet), while it performed similarly to the two rich-fen species at the intermediate level (S. warnstorfii hummock level). In contrast to S. fuscum, the rich-fen sphagna performed equally well in both habitats. The brown moss carpet was seasonally flooded, and in our third experiment we found that S. fuscum, but not S. teres, was severely damaged when submerged in rich-fen water. Our results suggest two thresholds in HWT affecting the ecosystem switch: one level that reduces the risk of submergence and a higher one that makes bog sphagna competitive against the rich-fen species.

  • 31.
    Granath, Gustaf
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Evolution, Ecological Botany.
    Strengbom, Joakim
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Evolution, Ecological Botany.
    Breeuwer, Angela
    Heijmans, Monique M. P. D.
    Berendse, Frank
    Rydin, Håkan
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Evolution, Ecological Botany.
    Photosynthetic performance in Sphagnum transplanted along a latitudinal nitrogen deposition gradient2009In: Oecologia, ISSN 0029-8549, E-ISSN 1432-1939, Vol. 159, no 4, p. 705-715Article in journal (Refereed)
    Abstract [en]

    Increased N deposition in Europe has affected mire ecosystems. However, knowledge on the physiological responses is poor. We measured photosynthetic responses to increasing N deposition in two peatmoss species (Sphagnum balticum and Sphagnum fuscum) from a 3-year, north-south transplant experiment in northern Europe, covering a latitudinal N deposition gradient ranging from 0.28 g N m(-2) year(-1) in the north, to 1.49 g N m(-2) year(-1) in the south. The maximum photosynthetic rate (NPmax) increased southwards, and was mainly explained by tissue N concentration, secondly by allocation of N to the   photosynthesis, and to a lesser degree by modified photosystem II activity (variable fluorescence/maximum fluorescence yield). Although climatic factors may have contributed, these results were most likely attributable to an increase in N deposition southwards. For S. fuscum, photosynthetic rate continued to increase up to a deposition level of 1.49 g N m(-2) year(-1), but for S. balticum it seemed to level out at 1.14 g N m(-2) year(-1). The results for S. balticum suggested that transplants from different origin (with low or intermediate N   deposition) respond differently to high N deposition. This indicates that Sphagnum species may be able to adapt or physiologically adjust to high N deposition. Our results also suggest that S. balticum might be more sensitive to N deposition than S. fuscum. Surprisingly, NPmax was not (S. balticum), or only weakly (S. fuscum) correlated with biomass production, indicating that production is to a great extent is governed by factors other than the photosynthetic capacity.

  • 32. Grandin, Ulf
    et al.
    Lönn, Mikael
    Rydin, Håkan
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Evolution, Ecological Botany.
    Allozyme variation at a PGI locus in differently aged populations of Moehringia trinervia (Caryophyllaceae) in a successional area2002In: Nordic Journal of Botany, ISSN 0107-055X, E-ISSN 1756-1051, Vol. 22, no 3, p. 303-311Article in journal (Refereed)
    Abstract [en]

    We studied genetic effects of the colonisation process during primary succession by analysing allozyme variation at a PGI locus in differently aged populations of Moehringia trinervia, which is a selfing annual with low dispersal ability. The populations studied come from islands and shores created in the 1880s by a drop in the water table of a Swedish lake and from old parts of a large island and of the mainland. The population age is known from five vegetation analyses over a century. We have also analysed the genetic composition of M. trinervia derived from seeds in the soil. Mainland populations had a higher genetic diversity than island populations that were little differentiated and differed genetically from the mainland populations. There was no temporal trend in the distribution of genetic variation on the new islands. The presence of alleles in the extant populations was associated with the proportion of that allele in the seed bank, indicating a main recruitment from the seed bank and not by repeated immigrations. We suggest that some of the new islands were colonised by a few early founders from the mainland. Later colonisation has occurred between adjacent islands, which preserves the founder effect and could explain the uniform, low genetic variation in the island populations.

  • 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.
    Gunnarsson, U
    et al.
    Uppsala University.
    Rydin, H
    Uppsala University.
    Demography and recruitment of Scots pine on raised bogs in eastern Sweden and relationships to microhabitat differentiation1998In: Wetlands (Wilmington, N.C.), ISSN 0277-5212, E-ISSN 1943-6246, WETLANDS, ISSN 0277-5212, Vol. 18, no 1, p. 133-141Article in journal (Other academic)
    Abstract [en]

    Scots pines (Pinus sylvestris) growing on open bogs occur preferentially on hummocks and on the margin of the bogs. To assess which life history stages lead to this uneven distribution, we studied how variation in the ground-water level influences recruit

  • 35.
    Gunnarsson, Urban
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Evolution, Ecological Botany.
    Boresjö Bronge, L
    Rydin, Håkan
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Evolution, Ecological Botany.
    Ohlson, M
    Near-zero recent carbon accumulation in a bog with high nitrogen deposition in SW Sweden2008In: Global Change Biology, ISSN 1354-1013, E-ISSN 1365-2486, Vol. 14, p. 2152-2165Article in journal (Refereed)
    Abstract [en]

    We present data on the accumulation of carbon and nitrogen into an open oceanic ombrotrophic bog, SW Sweden, with high levels of anthropogenic nitrogen deposition. The aim was to investigate if this peatland currently acts as a sink for atmospheric carbon. Peat cores were sampled from the top peat layer in five different vegetation types. Small pines were used to date the cores. The cores bulk density and carbon and nitrogen content were determined. A vegetation-classified satellite image was used to estimate the areal extent of the vegetation types and to scale up these results to bog level. The rate of current carbon input into the upper oxic acrotelm was 290 g m(-2) yr(-1), and there were no significant differences in accumulation rates among the vegetation types. This organic matter input to the acrotelm was almost completely decomposed before it was deposited for storage in the deeper peat layers (the catotelm) and only a small fraction (< , 1%) or 0.012 g m(-2) yr(-1) of the carbon would be left, assuming a residence time of 100 years in the acrotelm. Nitrogen accumulation rates differed between the vegetation classes, and the average input via primary production varied from 5.33 to 16.8 g m(-2) yr(-1). Current nitrogen input rates into the catotelm are much lower, 0-0.059 g m(-2) yr(-1), with the highest accumulation rates in lawn-dominated communities. We suggest that one of the main causes of the low carbon input rates is the high level of nitrogen deposition, which enhances decomposition and changes the vegetation from peat-forming Sphagnum-dominance to dominance by dwarf shrubs and graminoids.

  • 36.
    Gunnarsson, Urban
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Evolutionary Biology, Plant Ecology.
    Malmer, N.
    Rydin, Håkan
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Evolutionary Biology, Plant Ecology.
    Dynamics or constancy in Sphagnum dominated mire ecosystems? A 40-year study2002In: Ecography, ISSN 0906-7590, E-ISSN 1600-0587, Vol. 25, no 6, p. 685-704Article in journal (Refereed)
    Abstract [en]

    Traditionally mire ecosystems (especially bogs) have been viewed as stable systems with slow changes in the vegetation over time. In this study the mire Akhultmyren, south-central Swedenw as re-investigatedin 1997 after 40 yr of continued natural development. The results show a high degree of dynamics in a Sphagnum dominated bog and fen. Altogether 97 vascular plant and bryophyte species were recorded in the two inventories of the bog and poor fen vegetation ,p H and electrical conductivity in the mire water were also surveyed. In 1997 we found 10 new species and that 8 species had disappeared since 1954 but the over-all mean number of species per plot (size 400 m2) had hardly changed. However, 21% of the species increased and 21% decreased significantly in frequency. Most of the species that decreased in frequency were low-grown vascular plants, most common in wet microhabitats. Vascular plant species that increased in frequency included trees (defined as > 1.3 m in height) and were generally taller than the unchanged or decreasing species. The frequency of dwarf shrubs and hummock bryophytes increased too. Areas with an initial pH of 4.5-5.0 showed the strongest decrease in pH, coinciding with an enlarged distribution of some Sphagnum species. The species diversity increased on the bog, but decreased in the wettest parts of the fen, where the pH also decreased. Species with unchanged or increasing frequency often showed high capacity to colonise new plots. On average the sum of gains and losses of species in the plots in 1997 was ca 50% of the species number in 1954. The vegetation changes indicate a drier mire surface and anincreaseda vailability of nitrogen. The increased tree cover may have triggered further changes in the plant cover.

  • 37.
    Gunnarsson, Urban
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Evolutionary Biology.
    Rydin, Håkan
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Evolutionary Biology, Plant Ecology.
    Nitrogen fertilization reduces Sphagnum production in bog communities2000In: New Phytologist, ISSN 0028-646X, E-ISSN 1469-8137, Vol. 147, no 3, p. 527-537Article in journal (Refereed)
    Abstract [en]

    The effects of increased nitrogen influx on Sphagnum growth and on interspecific competition between Sphagnum species were studied in a 3-yr experiment in mires situated in two areas with different rates of airborne N deposition. Sphagnum growth was recorded after various supplementary N influxes (0, 1, 3, 5 and 10 g m −2 yr−1) in hummocks and lawn communities. Sphagnum biomass production decreased with increasing N influx in both areas. After the first season at the low-deposition site, Sphagnum showed an increased growth in length with the intermediate N treatment, but in the second and third seasons the control treatment had the highest growth in length. Capitulum dry mass increased with increasing N influx. Sphagnum N concentration and N/P quotient were higher at the high- than at the low-deposition site. The low quotient at the low-deposition site, together with the initial growth increase with intermediate N supplements, indicates that growth was N-limited at this site, but our lowest N supplement was sufficient to reduce growth. The N treatments had no effect on interspecific competition between the Sphagnum species. This indicates that the species have similar responses to N. The species studied all occur naturally on ombrotrophic, N-poor sites and show low tolerances to increased N influx. Reduced Sphagnum production may affect the carbon balance, changing the mires from C sinks to sources.

  • 38.
    Gunnarsson, Urban
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Evolutionary Biology.
    Rydin, Håkan
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Evolutionary Biology, Plant Ecology.
    Sjörs, Hugo
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Evolutionary Biology, Plant Ecology.
    Diversity and pH changes after 50 years on the boreal mire Skattlosbergs Stormosse, Central Sweden2000In: Journal of Vegetation Science, ISSN 1100-9233, E-ISSN 1654-1103, Vol. 11, no 2, p. 277-286Article in journal (Refereed)
    Abstract [en]

    The Skattlosbergs Stormosse min was reinvestigated in 1995 after 50 years of natural development since the previous investigation. The undrained mire is situated in an area with low anthropogenic deposition. The distribution of 106 plant species was mapped in detail and pH was measured at 251 locations, providinga unique opportunity to quantify long-term mire dynamics. The resultss how decreased pH in the richer (high-pH) parts of the mire, but little or no change in the poor fen andombrotrophipca rts.1 4 species had disappeared while two news pecies were recorded. Most species had a more restricted distribution in the mire area in 1995 than in 1945. Species richness in lOm x 0Omp lots had decreased, especially in plots with higher pH. Most Sphagnum species had unchanged distributions over the mire, while 7 3 % of other bryophyt sepecies and 3 8% of vascular plant species had decreased by more than 20 % in plot frequency. There was a strong relationship between number of species and pH-value. The mean and standard eviation of pH in plots where the species occurred have both decreased since 1945. We interpret the changes in species richness in the richer fens to be mainly caused by acidification. This could partly be an autogenic succession, but may be enhanced by increased atmospheric deposition. The mire represents an almost untouched site which can act as a reference for mires in morepolluted areas.

  • 39. 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.

  • 40. Hedberg, Petter
    et al.
    Kotowski, Wiktor
    Saetre, Peter
    Mälson, Kalle
    Rydin, Håkan
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Plant Ecology and Evolution.
    Sundberg, Sebastian
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Plant Ecology and Evolution.
    Vegetation recovery after multiple-site experimental fen restorations2012In: Biological Conservation, ISSN 0006-3207, E-ISSN 1873-2917, Vol. 147, no 1, p. 60-67Article in journal (Refereed)
    Abstract [en]

    Large peatland areas have been drained for forestry and agricultural purposes, resulting in the decline of characteristic biodiversity. Two measures commonly suggested for restoring drained fens is ditch blocking and tree removal to raise the groundwater table and increase light availability, respectively. In 2002, we initiated factorial restoration experiments, including ditch blocking and tree removal, in three former rich fens that had been drained for forestry purposes. Species cover of vascular plants and bryophytes were monitored during 8 years in permanent plots along transects perpendicular to the ditch for all four treatment combinations. Both methods had positive and independent effects on the cover of wetland vegetation. Specifically, Sphagnum species and wetland bryophytes showed a persistent positive response to both clear cutting and rewetting. Wetland vascular plants and grasses showed a persistent positive response to clear cutting. Sedges and species number responded positively to both clear cutting and ditch blocking, but the response was partly transient, and for species richness the response was limited when restoration methods were applied separately. Rich fen indicators of vascular plants and bryophytes did not respond to any of the restoration treatments. This indicates that species introduction in combination with further habitat restorations may be necessary to re-establish the original rich fen flora. Nevertheless, we conclude that the combination of ditch blocking and clear cutting are effective measures to partly restore wetland vegetation on previously drained and forested fens, while peat subsidence along the ditch may restrict the success further away from ditches.

  • 41. Hedberg, Petter
    et al.
    Saetre, Peter
    Sundberg, Sebastian
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Plant Ecology and Evolution.
    Rydin, Håkan
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Plant Ecology and Evolution.
    Kotowski, Wiktor
    A functional trait approach to fen restoration analysis2013In: Applied Vegetation Science, ISSN 1402-2001, E-ISSN 1654-109X, Vol. 16, no 4, p. 658-666Article in journal (Refereed)
    Abstract [en]

    Questions: Ecological restoration has traditionally been evaluated with analyses focused on species identities and abundances. These analyses provide no ecological explanation to why certain species change in abundance. One solution may be a functional trait analysis. We asked whether shifts in functional traits could explain vegetation changes in fens restored through tree cutting and rewetting, and how the functional traits in the restored sites compare to those of the reference site? Location: Three former rich fens in east-central Sweden. Methods: Tree cutting and rewetting were applied in a factorial design, and species and abundance data were recorded for 8yrs. Abundance data and trait data of canopy height, specific leaf area (SLA) and diaspore mass were used to calculate functional richness (FRic), functional divergence (FDiv), functional dispersion (FDis) and community-weighted mean (CWM) of functional traits. Data were analysed in a linear mixed effect model for vascular plants and bryophytes jointly, and for vascular plants separately. Results of restoration treatments were compared to data from a reference site. Results: Among vascular plants, tree cutting caused a decrease in SLA, as shade-sensitive species increased. In accordance with the change in SLA, FDis increased. In the joint analysis, tree cutting led to increased FDis, FDiv and FRic, indicating reduced filtering caused by the removal of the shading canopy, which allowed shade-sensitive species to establish. The comparison to the reference site shows that even after 8yrs, the restoration treatments have higher trait diversity than the reference site, indicating that the restoration sites have a too relaxed trait filter compared to conditions in an undisturbed fen. Our interpretation is that this is primarily caused by insufficient rewetting (and increased nutrient availability) that allow species of both natural and degraded fen conditions to co-exist, and which failed to suppress the regrowth of trees. Conclusions: Analysis of functional diversity improves our understanding of the ecological mechanisms affecting restoration results, and allows comparison among regions and communities with different species composition.

  • 42. Hedenäs, L.
    et al.
    Herben, T.
    Rydin, Håkan
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Plant Ecology and Evolution.
    Söderström, L.
    Ecology of the invading moss species Orthodontium lineare in Sweden: Spatial distribution and population structure1989In: Holarctic Ecology, Vol. 12, p. 163-172Article in journal (Refereed)
  • 43. Hedenäs, L.
    et al.
    Herben, T.
    Rydin, Håkan
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Plant Ecology and Evolution.
    Söderström, L.
    Ecology of the invading moss species Orthodontium lineare in Sweden: substrate preference and interactions with other species1989In: Journal of Bryology, Vol. 15, p. 565-581Article in journal (Refereed)
  • 44.
    Hedwall, Per-Ola
    et al.
    Swedish Univ Agr Sci, Southern Swedish Forest Res Ctr, Sundsvagen 3, SE-23053 Alnarp, Sweden..
    Brunet, Jörg
    Swedish Univ Agr Sci, Southern Swedish Forest Res Ctr, Sundsvagen 3, SE-23053 Alnarp, Sweden..
    Rydin, Håkan
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Plant Ecology and Evolution.
    Peatland plant communities under global change: negative feedback loops counteract shifts in species composition2017In: Ecology, ISSN 0012-9658, E-ISSN 1939-9170, Vol. 98, no 1, p. 150-161Article in journal (Refereed)
    Abstract [en]

    Mires (bogs and fens) are nutrient-limited peatland ecosystems, the vegetation of which is especially sensitive to nitrogen deposition and climate change. The role of mires in the global carbon cycle, and the delivery of different ecosystem services can be considerably altered by changes in the vegetation, which has a strong impact on peat-formation and hydrology. Mire ecosystems are commonly open with limited canopy cover but both nitrogen deposition and increased temperatures may increase the woody vegetation component. It has been predicted that such an increase in tree cover and the associated effects on light and water regimes would cause a positive feed-back loop with respect to the ground vegetation. None of these effects, however, have so far been confirmed in large-scale spatiotemporal studies. Here we analyzed data pertaining to mire vegetation from the Swedish National Forest Inventory collected from permanent sample plots over a period of 20 yr along a latitudinal gradient covering 14 degrees. We hypothesized that the changes would be larger in the southern parts as a result of higher nitrogen deposition and warmer climate. Our results showed an increase in woody vegetation with increases in most ericaceous dwarf-shrubs and in the basal area of trees. These changes were, in contrast to our expectations, evenly distributed over most of the latitudinal gradient. While nitrogen deposition is elevated in the south, the increase in temperatures during recent decades has been larger in the north. Hence, we suggest that different processes in the north and south have produced similar vegetation changes along the latitudinal gradient. There was, however, a sharp increase in compositional change at high deposition, indicating a threshold effect in the response. Instead of a positive feed-back loop caused by the tree layer, an increase in canopy cover reduced the changes in composition of the ground vegetation, whereas a decrease in canopy cover lead to larger changes. Increased natural disturbances of the tree layer due to, for example, pathogens or climate is a predicted outcome of climate change. Hence, these results may have important implications for predictions of long-term effects of increased temperature on peatland vegetation.

  • 45. Herben, T.
    et al.
    Rydin, Håkan
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Plant Ecology and Evolution.
    Söderström, L.
    Spore establishment probability and the persistence of the fugitive invading moss, Orthodontium lineare: a spatial simulation model1991In: Oikos, Vol. 60, p. 215-221Article in journal (Refereed)
  • 46. Hytteborn, H.
    et al.
    Rydin, Håkan
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Plant Ecology and Evolution.
    Skoglund, J.
    Viable seeds in sediments in Lake Hjälmaren1991In: Aquatic Botany, Vol. 40, p. 289-293Article in journal (Refereed)
  • 47.
    Hytteborn, Håkan
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Plant Ecology and Evolution.
    Svensson, Brita M.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Plant Ecology and Evolution.
    Kempe, Kerstin
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics.
    Press, Andreas
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics.
    Rydin, Håkan
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Plant Ecology and Evolution.
    Century-long tree population dynamics in a deciduous forest stand in central Sweden2017In: Journal of Vegetation Science, ISSN 1100-9233, E-ISSN 1654-1103, Vol. 28, no 5, p. 1057-1069Article in journal (Refereed)
    Abstract [en]

    Question: We quantify tree dynamics over a century of free development in a small broadleaved forest dominated by Fraxinus excelsior and Ulmus glabra. What are the internal and external factors driving the changes, and how predictable are they? What were the time scale and effects of the spread of Dutch elm disease (DED)? Location: Vårdsätra, eastern central Sweden.

    Methods: The survival, growth and recruitment of all trees (≥ 12 cm in girth) were monitored in 1912, 1967, 1988 and 2013 (more often for a part of the forest). Woody species in the field and shrub layers were surveyed in permanent plots in 1976 and 2012. We used transition matrix models to project changes in population sizes and species composition within the century and for 2050.

    Results: The results indicate that the forest was in a successional development during the first period. The species composition had stabilised by 1967, except for an expansion of Acer platanoides and the drastic effect of DED that struck the forest around 2000. It took only a decade to kill virtually all large elms in the forest, leading to strong decrease in stem density and basal area. The evidence for effects of DED is still weak, but there has been an increase in saplings, notably of Fraxinus, Prunus padus, Ulmus, and of shoots of Corylus avellana. Several species that are abundant in the vicinity and as seeds fail to establish (Picea abies, Betula spp., Quercus robur, Populus tremula). Projections for 2050 based on the third period (1988-2013) are probably unrealistic since also Fraxinus may disappear because of the recent arrival of the ash dieback.

    Conclusions: Slow dynamics in forests that could follow from climate change will locally probably be overruled by unforeseen catastrophes, such as invasions by forest pathogens. These initiate changes with long lag phases difficult to quantify. Still, a dense deciduous forest can resist invasion of colonist species and of regionally dominant conifers; the reason being unfavourable conditions for establishment rather than dispersal limitation

  • 48. Johansson, Per
    et al.
    Rydin, Håkan
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Evolution, Ecological Botany.
    Thor, Göran
    Tree age relationships with epiphytic lichen diversity and lichen life history traits on ash in southern Sweden2007In: Ecoscience, ISSN 1195-6860, Vol. 14, no 1, p. 81-91Article in journal (Refereed)
    Abstract [en]

    We examined the influence of tree- and stand-level conditions on lichen diversity on 143 ash trees, varying in age from 11 to 140+ y, in 5 deciduous stands in southern Sweden. The number of lichen species per tree varied from 2 to 30 and was primarily explained by tree trunk diameter and to a lesser extent by tree age, crown cover, lichen cover, and stand identity. The positive relationship between species richness and lichen cover seems compatible with a random placement of species and suggests that similar factors affect both lichen growth and establishment. Species richness did not increase on trees above 65 y of age, while species composition changed with tree age. Together with the positive linear effect of trunk diameter, these results suggest a slight overall positive effect of area, but that species richness over time depends more on species turnover. In addition, we examined if lichens occurring on trees of different ages differed in life history traits, e.g., spore size, thallus height, and pH preference. The results indicate that lichens that most frequently occurred on old trees had larger spores and thicker thalli than other species, suggesting that lichen species' response to tree age can be understood to some extent from their life history traits. However, in this respect lichen ecology is still in its infancy.

  • 49. Johnson, Matthew G.
    et al.
    Granath, Gustaf
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Plant Ecology and Evolution.
    Tahvanainen, Teemu
    Pouliot, Remy
    Stenoien, Hans K.
    Rochefort, Line
    Rydin, Håkan
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Plant Ecology and Evolution.
    Shaw, A. Jonathan
    Evolution of niche preference in Sphagnum peat mosses2015In: Evolution, ISSN 0014-3820, E-ISSN 1558-5646, Vol. 69, no 1, p. 90-103Article in journal (Refereed)
    Abstract [en]

    Peat mosses (Sphagnum) are ecosystem engineersspecies in boreal peatlands simultaneously create and inhabit narrow habitat preferences along two microhabitat gradients: an ionic gradient and a hydrological hummock-hollow gradient. In this article, we demonstrate the connections between microhabitat preference and phylogeny in Sphagnum. Using a dataset of 39 species of Sphagnum, with an 18-locus DNA alignment and an ecological dataset encompassing three large published studies, we tested for phylogenetic signal and within-genus changes in evolutionary rate of eight niche descriptors and two multivariate niche gradients. We find little to no evidence for phylogenetic signal in most component descriptors of the ionic gradient, but interspecific variation along the hummock-hollow gradient shows considerable phylogenetic signal. We find support for a change in the rate of niche evolution within the genusthe hummock-forming subgenus Acutifolia has evolved along the multivariate hummock-hollow gradient faster than the hollow-inhabiting subgenus Cuspidata. Because peat mosses themselves create some of the ecological gradients constituting their own habitats, the classic microtopography of Sphagnum-dominated peatlands is maintained by evolutionary constraints and the biological properties of related Sphagnum species. The patterns of phylogenetic signal observed here will instruct future study on the role of functional traits in peatland growth and reconstruction.

  • 50.
    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.

123 1 - 50 of 127
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