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.
KeywordsVegetation Dispersal Germination Seed morphology Seed viability
The authors gratefully acknowledge the use of data managed and collected by numerous organisations and individuals. In particular, for each location, the authors thank: Keith Ward and other staff from the Goulburn Broken CMA (Barmah Forest); Kathryn Stanislawski and other staff from the North Central CMA and staff from Australian Ecosystems Pty Ltd (Gunbower Forest); staff at The Murray-Darling Freshwater Research Centre and the Mallee CMA (Hattah Lakes and Lindsay-Mulcra-Wallpolla Islands); Jason Nicol and other staff at South Australian Research and Development Institute, (Chowilla Floodplain and the Lower Lakes). Data was collected and funded by the Murray-Darling Basin Authority as part of The Living Murray Monitoring program (contract number MD2556). The Living Murray is a joint initiative funded by the New South Wales, Victorian, South Australian, Australian Capital Territory and Commonwealth governments and coordinated by the Murray-Darling Basin Authority. The authors also gratefully acknowledge The Raukkan Natural Resources Management Team and Michael Diplock at Ngarrindjeri Regional Authority, Adrienne Rumbelow (SA DEWNR), Jan Whittle (SA DEWNR), Jason Nicol (SARDI), Keith Ward (GB CMA), Andrew Greenfield (Mallee CMA), Kathryn Stanislawki (NCCMA), Louisa Davis (DEPI) and Kate Bennetts for invaluable site related information. Paul Brown and Paul McInerney for their comments and feedback on early drafts of this paper and staff at the MDFRC, Jorge Portinho, Katherine Oliver and Cassie King for assistance with field work and sample processing.
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