Development of a treed bog island in a minerotrophic fen

The development of a heavily treed bog island situated in a wooded fen was investigated. Macrofossils indicate that the central part of the island has supported oligotrophic treed bog vegetation almost since the beginning of its formation. Three volcanic ash layers allow the reconstruction of the position of the wetland surface at different times. The treed island was initiated on a slight rise and it was always slightly higher than the surrounding fen, maintaining oligotrophic conditions above the fen level. On the treed island, the peat above the fen level is low in such nutrients as calcium, magnesium, and sulfur, but below the fen level the chemical characteristics of the peat are similar to those of the fen peat.