Abstract
Forest seed banks mostly studied in managed forests proved to be small, species poor and not reflecting aboveground species composition. Yet studies conducted in undisturbed communities indicate a different seed bank characteristic. Therefore we aimed at describing soil seed bank in an undisturbed forest in a remnant of European lowland temperate forests, the Białowieża Forest. We compared similarity between the herb layer and seed bank, similarity of seed bank between different patches, and dominance structure of species in the herb layer and in the seed bank of two related oak-hornbeam communities. We report relatively high values of Sorensen species similarity index between herb layer and seed bank of both patches. This suggests higher species similarity of the herb layer and soil seed bank in natural, unmanaged forests represented by both plots than in fragmented communities influenced by man. Although there was a set of core seed bank species present at both plots, yielding high Sorensen species similarity index values, considerable differences between plots in seed bank size and dominance structure of species were found, indicating spatial variability of studied seed bank generated by edaphic conditions. Dominance structure of species in the herb layer was not reflected in the underlying seed bank. This stresses, that natural forest regeneration cannot rely only on the seed bank, although some forest species are capable of forming soil seed banks. While forest seed banks may not reflect vegetation composition of past successional stages, they may inform on history and land use of a specific plot.
Highlights
In spite of several decades of intensive research on seed banks, temperate deciduous forest seed banks are still incompletely studied
Seed bank species richness recorded in both plots was lower than reported in earlier studies of oak-hornbeam forest in Bia3owie¿a conducted with seedling emergence method herb layer 0-5 cm seed bank 5-10 cm seed bank
Comparison of results concerning seed bank size obtained by different authors is difficult due to methodological differences (Brown 1992), seed bank size recorded by us seems to be of the same magnitude as in other oak-hornbeam seed bank studies conducted with seedling germination method (Jankowska-B3aszczuk and Grubb 1997; Jankowska-B3aszczuk 1998; Jankowska-B3aszczuk et al 1998), and seed extraction method (Piro¿nikow 1983; Table 4)
Summary
In spite of several decades of intensive research on seed banks, temperate deciduous forest seed banks are still incompletely studied. Forest soil seed banks are characterized by dominance of pioneer species absent from the forest floor and typical of open, early successional communities (Thompson 1978; Brown and Oosterhuis 1981; Warr et al 1993; 1994; Halpern et al 1999; Hyatt 1999; Bossuyt and Hermy 2001; Bossuyt et al 2002). These findings are in accordance with the widely accepted idea that the strategy of spreading risk in time associated with maintaining a soil seed bank is reserved mainly for small seeded and light demanding species.
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