Hattah Lakes, in the Hattah-Kulkyne National Park in north-western Victoria, are a refuge for flora and fauna in an otherwise semi-arid landscape. To support the health of key plant communities, environmental watering programs began in 2005. However, informed decisions about how much water to deliver, and when, require accurate predictions of how vegetation might respond to watering events. This can be difficult in complex systems such as semi-arid floodplains and wetlands, as plant abundance varies widely, plant growth can be slow yet is highly influenced by seasonal conditions. The quality of predictive models is also influenced by the amount and type of data that have been collected from the relevant communities.
ARI has been monitoring the response of three plant communities (Lakebed Wetlands, River Red Gum and Black Box Woodlands) to environmental watering to assess the success of the watering program and inform further water deliveries. A unique aspect of this work was the development of a complex model that took into account both individual plant and functional group responses.
The model showed that environmental watering at Hattah Lakes has led to:
- An increase in native water-dependent plants and functional groups
- An increase in eucalypt recruitment
- A decline in dryland plant encroachment on the floodplain
- A decline in herbaceous weeds
These are positive results as they demonstrate that environmental watering is sustaining this floodplain refuge, providing essential habitat, resources and public amenity. In addition, we found that plant functional group responses were driven by a few dominant species. This highlights the importance of monitoring both individual species as well as functional groups to obtain an accurate assessment of plant community responses to environmental watering.
Monitoring also revealed that, of the 140 native plants recorded, 26 are threatened species, including some new records for Hattah Lakes, reinforcing the importance of these plant communities for biodiversity conservation.
This work is occurring through The Living Murray Intervention Monitoring Program on behalf of the Mallee Catchment Management Authority. The Living Murray is a joint initiative funded by the New South Wales, Victorian, South Australian, Australian Capital Territory and Commonwealth governments, coordinated by the Murray-Darling Basin Authority.
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Some of the results of this work have been published in the following journal articles:
- Moxham, C., Kenny, S.A., Beesley, L.S., Gwinn, D.C. (2018) Large-scale environmental flow results in mixed outcomes with short-term benefits for a semi-arid floodplain plant community. Freshwater Biology
- Kenny, S.A., Moxham, C. and Sutter, G. (2017) The response of rare floodplain plants to an environmental watering event at Hattah Lakes, Victoria. Victorian Naturalist 134 (1):19-27
The journal article below details similar work under the same program, in the Murray Sunset National Park:
- Moxham, C., Duncan, M. and Moloney, P. (2018) Tree health and regeneration response of Black Box (Eucalyptus largiflorens) to recent flooding. Ecological Management and Restoration 19: 58–65