• Sphagnum;
  • nitrogen deposition;
  • global warming;
  • production;
  • acidification;
  • peatlands;
  • competition


  • • 
    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.