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Native vegetation

Native vegetation is vital for wetland and river health. Plants provide shelter, habitat, food and shade for a range of animals. They are vital for nutrient cycling, improving water quality and stabilising soil and riverbanks.

Different plants support different waterway functions and animal species. It is important to maintain a diversity of plant types in a healthy state to maintain healthy river systems.

Healthy floodplain forests, woodlands and wetlands need differing amounts of water throughout the year, including wet and dry periods. Water resource management, or how we use water in our rivers, has changed the wet and dry periods. This affects the type, diversity and nature of plant communities along the rivers. In many places like Murray River floodplains, this has meant a decline in river red gums, black box and lignum shrublands.

Basin annual environmental watering priorities for native vegetation

The Basin-wide environmental watering strategy includes objectives for water-dependent vegetation in the Basin. Water-dependent vegetation requires inundation, or high water levels to periodically cover wetlands and floodplains at least part of its life cycle. Our goal is to maintain and improve the health of this vegetation.

Annual environmental watering priorities for 2018-19

  • Maintain Ruppia tuberosa extent in the southern Coorong
  • Enable growth and maintain the condition of lignum shrublands 

The annual environmental watering priorities are the focus for the current year and are small steps in the short term to achieve the multi-year watering priorities in the long term.

 

Multi-year environmental watering priorities

The annual environmental watering priorities support multi-year environmental watering priorities that remain in focus over a number of years to achieve long term outcomes. Multi-year watering provides and relies on cumulative progress over time, e.g. watering in one year may only wet a dry riverbed, but follow up watering the next year provides more water to fill the river and reach wetlands either side of the river where it waters plants and animals.

More information

 

The multi-year priorities are listed below:
Expand the extent and improve resilience of Ruppia tuberosa in the southern Coorong

The Lower Lakes and Coorong is one of Australia’s largest wetland systems. It has 23 wetland types, covers 142,500 hectares and meets 8 of 9 criteria listed in the Ramsar Convention. Ruppia tuberosa, a submerged aquatic plant that was once widespread along the length of the southern Coorong, is a key indicator of the health of the Coorong and a defining component of the ecosystem’s ecological character. Many species in the Coorong, such as waterfowl and migratory waders, rely on the plant as a food resource. Ruppia tuberosa also provides habitat for other species in the Coorong.

The condition and extent of Ruppia tuberosa is influenced by a range of factors, such as water levels, water quality and the presence of filamentous algae within the Coorong. The millennium drought had a significant impact on the condition of the species, with Ruppia tuberosa disappearing from the southern Coorong. Although the species is showing signs of recovery, providing suitable habitat conditions and flow regimes for Ruppia tuberosa is essential to maintain this species that underpins the ecology of the ecosystem.

Ruppia tuberosa’s water requirements

Based on research by David Paton, University of Adelaide

Ruppia tuberosa’s water requirements vary between each stage of its life history. By late summer, Ruppia tuberosa persists as seeds and turions on the ephemeral mudflats on the shores of the southern Coorong. These seeds and turions germinate or sprout when the water levels rise during late autumn, and the plants continue to grow through winter. If the water levels in the southern Coorong remain adequate, the plant reproduces sexually (producing seeds) and asexually (producing turions) during spring and early summer.

Improve the condition and extent of lignum shrublands

Lignum grows along riverbanks, on floodplains and in wetlands across the Basin and can grow in woodlands under trees or as the dominant overstorey species in shrublands. Lignum shrublands provide important habitat and resources for a range of animals species, with dense, tall shrublands acting as ideal nesting and nursery habitat for many waterbird species during both wet and dry times.

Lignum requires periodic flooding to maintain good condition, promote growth and support reproduction. Lignum is found in a range of habitats which means that the lignum shrublands across the Basin experience a variety of inundation frequencies.

Maintain and improve the condition and promote recruitment of forests and woodlands

River red gum, black box and coolibah forests grow on riverbanks and floodplains. These forests provide habitat and resources for aquatic, amphibious and terrestrial animals. Forests contribute dissolved organic carbon into the nearby rivers. Roots and branches provide shelter and habitat for fish and help moderate water temperature by providing shade.

Water delivery to the floodplain in line with this priority will provide necessary water for saplings. It will also improve the condition of other understorey vegetation (i.e. shrubs and grasses) in these forests and woodlands. River red gum, black box and coolibah depend on flooding for growth and recruitment. This differs across species depending on their location on the floodplain.

Improve the condition and extent of Moira grass in Barmah-Millewa Forest

Moira grass is a rapidly growing, semi-aquatic grass that thrives in wetlands and floodplains. Barmah–Millewa Forest has one of the largest inland plains of Moira grass in Australia. The floodplain marshes are part of the Barmah Forest Ramsar Convention listing.

There has been a continual decline in the extent of, or the area covered by, Moira grass. Only around 182 hectares of Moira grass in the floodplain marshes in Barmah Forest was recorded in early 2014. This is about 12% of the amount recorded at the time of its Ramsar listing in 1982. Without environmental watering the Moira grass plains could be extinct in Barmah-Millewa Forest in a matter of years.

There are a number of other threats to Moira grass in Barmah–Millewa Forest, including grazing pressures (e.g. pigs, kangaroos and horses) and encroachment of river red gum and giant rush.  

The Barmah–Millewa Forest is on the River Murray between the towns of Tocumwal, Deniliquin and Echuca. It acts as a drought refuge in an otherwise arid to semi-arid region. The forest supports threatened species of plants and animals. It is part of bilateral migratory bird agreements. These agreements include JAMBA, CAMBA, ROKAMBA and the Bonn Convention on Migratory Species.

How does the MDBA decide where water needs to be delivered?

Where and how much water for the environment is delivered depends on a number of different factors including climate (e.g. rainfall and soil moisture). These factors are measured by the Resource Availability Scenario. For more information visit the Resource Availability Scenario page.