Seed-bank and dynamics of a Polygonum hydropiper L. community along the Po river (Central-West Italy).

The seed-bank and the dynamics of a Polygonum hydropiper L. community were investigated. The study area is located along the Po river in the Central-West Po plane (Northern Italy), in Piedmont, near Alessandria. The seed-bank in the sod was investigated by means of a simplified procedure of seasonal sampling and germination tests while the dynamics of the Polygonum community was investigated within a permanent square. Results indicate that: i) The Polygonum hydropiper community has strong growth potential because it has a source of biodiversity in its reservoir of germinable seeds of different species. River overflows act both as disturbance and as vectors for propagules, selecting the species that can grow and develop within the vegetation, and the species that will be left as seeds in the soil; ii) species diversity and dominance vary with vegetation stage (seed bank, pioneer stages and mature stages); iii) two types of seed-bank were present in the sod we analysed: a transient one and a persistent one.