Seed banks: ecological definitions and sampling considerations

Definitions of seed banks are discussed in the introductory part of the paper. In the second part, a literature review regarding sampling problems in soil seed bank ecology is presented. Regarding sampling depth, a rapid decline in soil seed content is demonstrated from example studies. The use of soil cores with 5 cm or 10 cm depth is suggested to ensure comparability of results. For determination of optimal sample volumes for various communities, the species saturation model is suggested such that minimal volume can be defined for soil seed banks in the same way that minimal area can be defined in phytosociological studies. Although sampling time may depend on research goals for vegetation types with a winter standstill period, late autumn sampling is suggested for detecting the entire soil seed bank, whilst late spring sampling is recommended for the examination of its persistent part. Studies looking at medium (plant community level) and fine scales (patch level) have demonstrated that soil seed bank distributions show horizontal aggregation for most of the cases and for most of the species. Seed dispersal processes which are among major factors responsible for such aggregated patterns are also discussed.