Soil Seed Bank of Levee Forests of the Paraná River Frontal Delta (Argentina)

Abstract

A seed bank is made up of all viable and nongerminated seeds that are present in an environment, and its study is relevant to understanding a plant community. The levee forests of the Paraná River Frontal Delta are primary and secondary riparian forests that develop on relatively high banks and have been described in terms of their vegetation and successional behaviour. However, its seed bank has not been characterised, so the objective of the present work was to describe it in order to understand the regeneration potential of native and exotic species in the levees. To do this, soil samples were collected throughout the four seasons of a year in eight plots of 10 by 10 m (0.03 m² per plot, total sampled area 0.99 m²). Each sample included leaf litter up to 10 cm in depth. These were put to germinate for a year, both with their structure intact and disturbed. Results indicated that the seed bank of the forests under study is similar to that of other subtropical forests. It has greater species richness in autumn and greater total density in winter. Species with transient (genera Ligustrum and Ficus) and permanent (genera Rubus, Cyrtocymura and Morus) banks could be classified. Woody life forms are more abundant than herbaceous life forms, but the latter have a greater number of species. Alien species add a greater number of seeds, but the native ones are richer.