The flooding regime on floodplains, caused by fluctuations of flow in the natural flow regime is the main disturbance structuring the occurrence and distribution of vegetation on floodplains. In response to the high variability of the hydrological regime, many floodplain plants produce long-lived soil seed banks that enable them to persist through unfavourable conditions. These seeds are essential for the re-establishment and development of plant communities on floodplains during and following rewetting. As soil seed banks on floodplains rely on both flooding and drying conditions to be maintained, water resource development and climate change may alter the seed bank composition over time, leading to shifts in vegetation structure and a decline or change in species abundance and diversity. Although spatial patterns in the composition of the soil seed bank have been studied, greater knowledge of the temporal changes in soil seed banks related to hydrological conditions is needed. Understanding the influence of flooding and time since flooding on the soil seed bank of floodplains will improve our ability to predict the impacts of changes to flooding regimes on floodplain plant communities.
This project focuses on the temporal variation in the soil seed bank, through undertaking a soil seed bank germination procedure on soil collected from the floodplain of the lower Lachlan River, NSW, Australia. Data previously collected from 2016 and 2019 will be compared to data collected in 2020. The density, species richness and composition of the vegetation will be compared between years and across sites with varying flooding regimes.
This project will further our knowledge of how the flow regime influences the diversity, composition and species richness of the vegetation of semi-arid floodplains over time. It will assist in predicting the potential impacts of water resource development and climate change and aid in prescribing environmental flows to maintain diverse floodplain communities.