Seed bank dynamics in wetland complexes associated with a lowland river

The existence of a dormant “bank” of plant seeds plays an important role in maintaining and preserving species and genetic diversity. However, information on the spatial heterogeneity of the pool of dormant seeds among wetland complexes along riverine systems is limited. In this study we collected sediment from 18 wetlands within six wetland complexes along the Murray River, Australia. The germinable, residual and viable seed banks in each wetland complex were assessed by undertaking a germination trial, counting seeds (morphotypes) and viability testing. A diverse and viable seed bank exists within all the complexes however seed bank communities differed among wetland complexes. There was no difference in the viability of seeds within the sediment profile, however more seeds occurred in the surface layers of sediment and communities differed with sediment profile depth. In general, the number of species germinating was fewer than the number of seed morphotypes counted. Management actions need to be targeted not only at preserving the extant plant communities but also to ensure the seed bank is replenished. This may also involve allowing wetlands to dry sufficiently to enable cracking of wetland sediment and seeds to become buried to maximise the longevity of the seed store.