Growth, production and interspecific competition in Sphagnum: effects of temperature, nitrogen and sulphur treatments on a boreal mire

Authors

  • Urban Gunnarsson,

    Corresponding author
    1. Department of Plant Ecology, Evolutionary Biology Centre, Uppsala University, Villavägen 14, S−752 36 Uppsala, Sweden;
    2. Present address: Department of Biology, Norwegian University of Science and Technology, N−7491 Trondheim, Norway;
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  • Gunnar Granberg,

    1. Department of Forest Ecology, Swedish University of Agricultural Sciences, S−901 83 Umeå, Sweden
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  • Mats Nilsson

    1. Department of Forest Ecology, Swedish University of Agricultural Sciences, S−901 83 Umeå, Sweden
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Author for correspondence:Urban Gunnarsson Tel: +47 73551271 Fax: +47 73596100 Email: Urban.Gunnarsson@bio.ntnu.no

Summary

  • • Growth and production of Sphagnum balticum and interspecific competition between S. balticum and either Sphagnum lindbergii or transplanted Sphagnum papillosum, were studied in a 4-yr field experiment in a poor fen.
  • • Temperature and influxes of nitrogen (N) and sulphur (S) were manipulated in a factorial design. The mean daily air temperature was increased by 3.6°C with glasshouse enclosures. Nitrogen loads were increased 15-fold and S loads seven-fold compared with the natural loads up to influxes observed during the 1980s in south-western Sweden.
  • • Production of S. balticum decreased with increasing temperature and N-influx. The N treatment significantly reduced the incremental length of S. balticum, and this reduction was reinforced with time (24% in the first year to 51% in the final year). The area covered by S. lindbergii changed with time in all treatments and S. papillosum area increased significantly in the temperature-treated plots.
  • • Growth, production and competitive patterns change if the environmental conditions change. Increased N deposition and raised temperature may transform mires currently dominated by Sphagnum into vascular-plant-dominated mires.

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