Rich-fen bryophytes in past and recent mire vegetation in a successional land uplift area

Abstract

Most rich-fen bryophyte species are currently declining and red listed in many European countries. Little is known about their past and current occurrence. We investigated past and recent bryophyte assemblages in mires in the land uplift coast of Finland. The study areas included primary succession areas where mire development started c. 6000 BP. In total, seven mires were studied in two successional transects along the land uplift coast. The past occurrences of rich-fen and other bryophytes were studied in 45 mire stratigraphic peat profiles, and recent occurrences were collected from 158 vegetation plots of 10 m × 10 m. Bryophyte subfossils indicated that the central parts of the basins developed first to wet rich fens with groundwater influence, which developed towards intermediate fens or poorer mire types. Most mire bryophytes occurred in about the same proportion in peat profiles as in recent vegetation. Five rich-fen species ( Hamatocaulis lapponicus, H. vernicosus, Meesia longiseta, M. triquetra and Pseudocalliergon trifarium) were clearly more common in peat profiles than in the present mire vegetation, where these species were very rare and appeared only in small patches without sporophytes. These rich-fen species have had markedly wider distributions in the past, probably linked to climate fluctuations, whereas current occurrences are becoming scarce because of multiple anthropogenic factors such mire drainage and climate change.