Passive restoration relies on natural regeneration, which is typically facilitated by limiting deleterious disturbance and enabling key environmental factors to return toward historical conditions. Vegetation regeneration is highly contingent on seed availability, either through dispersal from neighbouring source populations or soil seedbanks.

We examined the composition of the soil seedbank in a passively restoring wetland that is part of the Macquarie Marshes, a Ramsar-listed wetland. Portions of the area experienced 12 different land use disturbances: ringbarked 1950s, cleared 1982, cleared 1998, bulldozed 2000, bulldozed 2002 and raked 2006, bulldozed and ploughed 2003, cropped 1985-2008, cropped 1997-2008, cropped 2002&2004&2006, cropped 2003, cropped 2005-2007, cropped 2006. Levee banks reduced flooding across the study area throughout this period. After the land was purchased in 2009, levee banks were breached to facilitate natural regeneration by enabling passage of environmental and managed flows. Several years of flooding led to variable restoration success.

This project examined whether restoration success was associated with seedbank composition or germination success. Within each of the 12 land use types, we sampled the soil seedbank from nine random sites, three in shallow distributary channels, three immediately adjacent to channels (riparian) and three 50-100m from channels on the floodplain (n=108). The soil samples were germinated under damp, saturated and flooded conditions in greenhouses for 12 weeks, with continual seedling identification and removal. Results suggest that both dispersal constraints (seedbank composition) and germination conditions affect the diversity, abundance and composition of vegetation germinating and reflect the varying disturbance types and flooding frequencies.