Seed survival and persistence on a calcareous land surface after a 32-year burial

Of 34 species of vascular plants recorded in an unimproved calcareous grassland community in 1960 and subsequently buried for 32 yr, just six spp. were recovered as viable seeds from the original land surface, following excavation of an experimental earthwork. Five of the six are known or suspected to form persistent seed banks; the status of Carex flacca as a persistent seed is now established. The exceptionally low density of viable seeds at 35 seeds/m2 and the paucity of other plant remains confirm that these calcareous soils have supported rapid decomposition. The complete absence of viable seeds known to be short-lived indicated that the macro-fauna has played no significant role in the introduction of viable seeds from the modern-day surface down to depths in excess of 1.6 m, at least not in recent years. Because of the precise dates of burial and excavation, the results offer a rare opportunity to confirm laboratory and other indirect observations of long-term seed persistence following burial in temperate climate calcareous soils.