Competition between Sphagnum species under controlled conditions

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 of 1) S. fuscum + S. balticum, 2) S. balticum + S. tenellum, and 3) all three species in approximately equal proportions were transferred from a bog into pots in a growth chamber. The outcome of competition ,vas monitored by measuring the area covered by the different species at the start and after 8 and 14 months of growth. During the first 8 months S. balticum increased in all species combinations and in all replicates, while S. fuscum and S. tenellum decreased correspondingly Thereafter, changes were smaller and more variable between replicates. On average, S. balticum decreased during this period. The results were less variable than in the field, but variability between replicates increased during the experimental period. Although S. balticum initially was a strong competitor, it was unable to outcompete the other species, and coexistence was maintained in all replicates.