A seed bank inside a clonal plant: the case of the sedge Carex cespitosa on an unmowed grassland

This study examined a non-soil seed bank deposited inside the tussock cores of Carex cespitosa, a perennial plant with a tussock growth form. Based on the vertical structure of the seed bank in 20 tussock cores, the history of changes in plant species composition during succession in an unmowed grassland in the Białowieża National Park was reconstructed. Three horizontal layers were distinguished in each tussock core: upper (corresponding to the initial forest stage), middle (transitory stage—forb and swamp communities) and bottom (early successional stage—grassland). The results showed that seeds of both the parental species and other species were stored inside the C. cespitosa tussock cores. More than 50,000 seedlings were found, representing 42 vascular plant species. The highest number of seedlings was recorded in the middle layer. Seedlings of swamp species were dominant in the upper layer, whereas seedlings of grassland species were dominant in the other layers. The highest number of C. cespitosa seedlings was observed in the upper layer. The most common seedlings in the middle layer belonged to the species Epilobium palustre, Lythrum salicaria and Cirsium palustre. In the bottom layer, the most common species of seedlings were grassland species, e.g. Lychnis flos-cuculi and Ranunculus repens. The protected seed bank inside this tussock species reflected recorded changes in species composition of these grasslands through time. Seed banks in this and other tussock-forming species represent a potentially useful tool for reconstructing recent developmental history of plant communities.