The seed bank as a mechanism for resilience and connectivity in a seasonal unregulated river

The seed bank of a seasonally flowing river was sampled to assess ecosystem resilience and evidence of connectivity. Seed banks were sampled from 'Floodplain', 'Top of Bank' and 'In Channel' hydrogeomorphic areas in seven reaches of the Wannon River, and the distribution of species and water plant functional groups (WPFGs) among these sites was assessed. The seed bank material was exposed to two treatments (damp and flooded) to stimulate germination of terrestrial (Tdr Tda), flooding-tolerant (ATe, ATl, ARp, ATw) and flooding-dependent (ARf, Se, Sr, Sk) species. There was a high degree of similarity among seed banks from all parts of the river, and all hydrogeomorphic areas. Few species were restricted to any one area (i.e., 'In Channel', 'Top of Bank', 'Floodplain') or any one reach of the river. This indicates that the wetland areas of the Wannon River have a high degree of longitudinal and lateral connectivity, and the riparian zone retains the capacity to provide resources to wetland fauna, even with large variation in the natural flow regime and long-term agricultural land-use. Provided the seed bank remains intact, the perennial vegetation is allowed to regenerate, and a natural flow regime is maintained, seasonal rivers like the Wannon are likely to be resilient to the consequences of climate change, despite the surrounding agricultural land-use and the influx of saline ground-water.