EXTINCTION AND REINTRODUCTION OF THE BRYOPHYTE SCORPIDIUM-SCORPIOIDESIN A RICH-FEN SPRING SITE IN THE-NETHERLANDS

A survey of historical records revealed that the disappearance of char acteristic rich-fen bryophytes such as Scorpidium scorpioides, S. revo lvens and Campylium stellatum from the springs of De Mosbeek, the Neth erlands, has taken place between 1951 and 1956. A study of the present ecohydrological situation suggests that the present water chemistry ( pH, EC and Ionic Ratio) and trophic status (P concentrations) fall wit hin the range suitable for S. scorpioides and that the water is well-b uffered. To test the hypothesis that the present absence of rich-fen b ryophytes is due to past habitat change rather than ecohydrological co nditions, a transplantation experiment with S. scorpioides was carried out. Reintroduction of the species resulted in establishment of new s hoots throughout the spring channel up to a distance of 2 m from the i nitial transplants within three years, which confirmed that the water composition is not detrimental to the species. It is unknown what caus ed the disappearance of the species in the 1951-1956 period An unusual rainfall pattern, increased atmospheric deposition and changes in man agement all could have played a role. Historical data suggest a strong expansion of Sphagnum spp. and, via this, the disappearance of S. sco rpioides and associated species. The present absence of S. scorpioides seems to be due to poor dispersal and establishment rather than habit at conditions.