Fern spores in a grassland soil

Large numbers of fern spores germinated in soil samples from a grassland trail. The trail was established in central Sweden 35 years ago to study the effect of different treatments on grassland vegetation. The density of prothallia varied between 57 000 and 170 000 m−2 in the different treatments. There were no ferns in the treatment plots, and none of the three fern species identified from the spore bank were found in the surrounding area. This suggests that the large spore bank has accumulated over a long period of time and that fern spores are capable of remaining viable in the soil for several years. A large spore bank can enhance the chance for intergametophytic crossing in fern species.