Seasonal Herbaceous Wetlands (Freshwater) of the Temperate Lowland Plains - profile

Indicative distribution

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Key:

known

predicted

The areas shown in pink and/purple are the sub-regions where the species or community is known or predicted to occur. They may not occur thoughout the sub-region but may be restricted to certain areas. ( click here to see geographic restrictions). The information presented in this map is only indicative and may contain errors and omissions.

Scientific name: Seasonal Herbaceous Wetlands (Freshwater) of the Temperate Lowland Plains

Conservation status in NSW: Not listed

Commonwealth status: Critically Endangered

Gazetted date: 27 Mar 2012

Profile last updated: 19 Nov 2025

Description

Seasonal Herbaceous Wetlands (Freshwater) of the Temperate Lowland Plains is a community that occurs in isolated patches in south-western NSW. It occurs in areas that are usually inundated on a seasonal basis through rainfall then dry out, so surface water is not permanently present. The community is dominated by herbaceous species which are adapted to seasonal inundation. There is often a high graminoid component, commonly including species of Amphibromus, Deyeuxia, Glyceria and Lachnagrostis, as well as Poa labillardierei, Rytidosperma duttonianum, Carex tereticaulis, and occasionally Juncus spp. Other forb genera that typically occur include Allittia, Asperula, Brachyscome, Craspedia, Epilobium, Eryngium, Lobelia, Marsilea, Montia, Ornduffia, Pycnosorus and Ranunculus. Trees and shrubs are generally absent to sparse, and where they occur, are usually scattered emergents or restricted to wetland margins. Tree and shrub species may include Eucalyptus camaldulensis, E. largiflorens, Allocasuarina luehmannii or Muehlenbeckia florulenta. Most of the species in this community are absent from the surrounding dryer areas, which usually consist of dryland grasslands and woodlands.

Distribution

This threatened community is found in isolated patches in the south-western plains of NSW with its main distribution on lowland plains between Narrandera and Deniliquin, and other patches occurring south-west of Deniliquin. Its broadest distribution is in Victoria, with a few occurrences in far eastern South Australia. The ecological community is limited to plains and lower slopes and stony rises at elevations below 500 metres above sea level. Climate is mostly temperate, with most of the NSW distribution in areas of down to 350 millimetres rainfall per year.

Habitat and ecology

In NSW, the community occurs on generally fertile but poorly draining clays of alluvial deposits associated with grey or mixed soil types.
The depth, duration and frequency of inundation are highly variable and driven by rainfall. In ‘typical’ years, inundation may last for up to several months, with water levels usually less than one metre deep. Occasionally water can be brackish, and salinity levels may increase as water evaporates.
In many suitable areas this ecological community no longer exists, having been modified or removed by conversion to cropland, pasture, plantation forests, dams or changed hydrology.
Because Seasonal Herbaceous Wetlands are highly variable, a four-part test is used for assessing condition. Part A applies to a ‘typical’ seasonal pattern, whereby at least 50% plant cover of native species characteristic of the community need to be present. Part B applies to periods of prolonged drought, when presence of the community may be difficult to determine. In these conditions the Listing Advice promotes the diagnosis of the community using landscape position, inference from historical knowledge and the nature of surrounding vegetation. Part C relates to minimum wetland size and specifies 0.5 hectares for an isolated wetland or cluster of small wetlands in a gilgai terrain, or 0.1 hectares if the wetland is connected to remnant native vegetation which collectively sums to at least 1ha in size. Part D relates to assessing if the wetland is of high quality based on presence of indicator species.

Regional distribution and habitat

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Recovery strategies

Priority actions are the specific, practical things that must be done to recover a threatened species, population or ecological community. The Office of Environment and Heritage has identified 0 priority actions to help recover the Seasonal Herbaceous Wetlands (Freshwater) of the Temperate Lowland Plains in New South Wales.