Laura Williams, Paul Reich, Samantha J Capon, and Elisa Raulings. Monash University
The restoration and management of riparian plant communities and riparian
zones is the dominant focus of river restoration efforts globally. While
soil seed banks are understood to be integral to the vegetation dynamics
and restoration of many ecosystems, little is known of their role in
riparian zones, particularly in lowland areas. This study investigates
soil seed banks of riparian zones adjacent to small lowland streams and
their potential to influence riparian restoration. We compared the
composition and structure of the viable soil seed bank between cleared
and wooded reaches along three lowland creeks in south-eastern Australia.
The viable soil seed bank was characterised using the seedling emergence
method and compared to environmental variables and the extant vegetation.
Riparian condition (i.e., cleared or wooded) and the distance from the
channel both explained the variation in many characteristics of the soil
seed bank, including the total number of germinants, species and overall
community composition. Stream reaches cleared of riparian vegetation had
significantly more species than wooded reaches. Community composition of
the soil seed bank was significantly correlated with site openness and
was generally dissimilar to the extant vegetation. The floristic
composition of the extant vegetation may be less important than
structural characteristics in influencing soil seed bank dynamics within
these environments. The soil seed bank contributes to the diversity of
vegetation in these riparian zones. However, recruitment from the soil
seed bank will contribute toward restoring only some components of
riparian plant communities and may detract from restoration by
introducing undesirable species.