Seed dispersal and seed bank dynamics of the endangered Changium smyrnioides

Abstract

Changium smyrnioides is an endangered species of Umbelliferae. Its cytology, pollen morphology, geological distribution, and genetic diversity have been studied, but the ecological characteristics of its seeds still remain unknown. To understand the mechanism of endangerment of C. smyrnioides, seed production and dispersal and the dynamics of its seed bank were investigated by random sampling methods. Seed production of C. smyrnioides is 132 seeds/individual, 86.4% of which are from the top inflorescence. The kilo-grain weight of seeds is different between habitats. The scape (averaged 1.06 m in height) to C. smyrnioides often falls to the ground, so seeds fall far from their mother plant. The seed dispersal pattern is contagious. Compared with Anthriscus sylvestris, another species of Umbelliferae, seed production and seed bank density of C. smyrnioides in different periods is much less. Both seed banks are non-persistent. C. smyrnioides maintain the seed bank by multi-procreation, while A. sylvestris is maintained by clonal reproduction. C. symyrnioides has adopted a K=strategy, with low seed number, large seed size and dispersion far from the mother plant so as to avoid density competition among the seedlings. Therefore, when it is disturbed by humans, by digging for medicinal use and deforestation, the population cannot recover quickly. A sylvestris has adopted a r-strategy, with high seed number, small seed size, dispersion near the mother plant, and production of ramets. Its population can recover quickly when it is disturbed by humans.