The diversity of plants, vegetation communities and mosaics of communities in Murray-Darling Basin wetlands and floodplains is tremendous. Environmental water managers seek to achieve a range of outcomes that reflect the diversity of functions and values supported by wetland and floodplain vegetation. For managers to achieve vegetation outcomes a process of social, ecological and economic consideration is required. As such, there is a need to clearly articulate the values that wetland-floodplain systems support, to improve predictive capacity based on an improved knowledge base and to provide rigorous evidence of the outcomes of environmental flows in achieving management goals and informing adaptive management.
The Vegetation Theme of the Murray-Darling Basin Environmental Water Knowledge and Research Project (MDB EWKR) sought to tackle these challenges. Research undertaken in this project provided guiding principles to help define function and value and select indicators across a range of spatial and temporal scales. Our research sought to improve predictive capacity and the underlying knowledge base by determining drivers of responses to flows, for i) extant understory communities; ii) seed bank diversity; iii) woody seedling establishment and iv) lignum structure.
This research demonstrates incredible variation in local plant communities and associated seed banks in space and time. Location is overwhelmingly the most important predictor of local community composition, followed by recent flow conditions. After location and recent flow, the story becomes more complicated and interactions between factors play a role. Other key findings include the influence of inundation timing on seedling development and the frequency of flows required to maintain structural characteristics in lignum.
By understanding what the significant drivers are, their relative importance and how they interact, we are improving our capacity to predict expected outcomes to environmental watering events and can use those predictions to help plan or prioritise watering actions.