ESTIMATES OF ALPINE SEED BANK SIZE IN 2 CENTRAL-EUROPEAN AND ONE SCANDINAVIAN SUB-ARCTIC PLANT-COMMUNITIES

Seed bank sizes of two alpine plant communities in the Central Alps with differing substrates and of one subarctic alpine site were estimated on the basis of the emergence of seedlings. Estimates of seed bank size to 5 cm depth were 1350 +/- 177 and 1521 +/- 236 seedlings m-2 for the Austrian alpine communities on silicaceous and calcareous substrates, respectively. Diaspores of 27 to 45% of all the species present in the communities germinated from a total of 50 soil samples. All seed bank taxa were present in the existing vegetation, as well. The overall relative frequency of established taxa in a given community is a weak predictor for the abundance in the seed bank. Seedling density also is not related to the extent of vegetative cover at the sampling location. Emergence of diaspores from the Swedish subarctic alpine site amounted to merely 37 +/- 19 seedlings m-2, suggesting that seed bank size is low or germination requirements of subarctic/alpine taxa are inherently different, compared to temperate alpine species.