Community Description

• River-flat Eucalypt Forest is an Endangered Ecological Community of the NSW North Coast, Sydney Basin and South-east Corner Bioregions.¹
• The structure of the community varies from tall open forests to woodlands, although partial clearing may have reduced the canopy to scattered trees.¹
• The composition of River-flat Eucalypt Forest on Coastal Floodplains is primarily determined by the frequency and duration of inundation, waterlogging and the texture, nutrient and moisture content of the soil.¹
• The dominant plant species within this community are Eucalyptus tereticornis (Forest Red Gum), E. amplifolia (Cabbage Gum), Angophora floribunda (Rough-barked Apple), E. saligna (Sydney Blue Gum) and E. grandis (Flooded Gum). A layer of small trees may be present, including Melaleuca decora, M. stypheloides (Prickly-leaved Teatree), Backhousia myrtifolia (Grey Myrtle), Casuarina cunninghamiana subsp. cunningham-iana (River Oak) and C. glauca (Swamp Oak).
• Scattered shrubs include Bursaria spinosa subsp. spinosa (Blackthorn), Solanum prinophyllum
•  (Forest Nightshade), Rubus parvifolius (Native Raspberry), Breynia oblongifolia (Coffee Bush), Ozothamnus diosmifolius and Acacia floribunda (White Sally). The groundcover is composed of abundant forbs, scramblers and grasses including Microlaena stipoides (Weeping Grass), Dichondra repens (Kidney Weed), Glycine clandestina, Oplismenus aemulus, Pratia purpurascens (Whiteroot), Entolasia marginata (Bordered Panic) and Oxalis perennans.¹
• The composition and structure of the understorey is influenced by grazing and fire history, changes to hydrology, soil salinity, weed invasion and other disturbance.¹

Habitat Requirements

Landform: Found on periodically inundated alluvial flats, drainage lines and river terraces associated with coastal floodplains.¹

Distribution: Occurs in localised areas along the NSW Coast. In the local area, this community occurs along major creeklines and rivers of local valleys.¹

Elevation: Generally occurs below 50m elevation.

Soil: Usually associated with silts, clay-loams and sandy loams of alluvial soils associated with the Hawkesbury River, Wollombi Brook, Wyong and Yarramalong Soil Landscapes.²

Hydrology: Associated with periodically inundated alluvial flats, drainage lines and river terraces.

Where this Community can be Found

Gosford: Along Hawkesbury River, Mangrove Creek, Narara Creek and in Dharug National Park,

Wyong: Ourimbah State Forest near Wyong Creek; Opposite Mountain Road, Warnervale; Jilliby and Yarramalong Valleys,

Lake Macquarie: South of Branter Road, along Crangan Bay Drive, Nords Wharf, Dora Creek west of the railway bridge.

Where this Community is Protected

Small areas of RFEF are contained within conservation reserves such as: Dharug National Park and Watagans National Park.

Threats to Survival

• Vegetation clearing.
• Fragmentation.
• Land filling and earthworks associated with development.
• Flood mitigation and drainage works.
• Pollution from urban and agricultural runoff.
• Weed invasion.
• Overgrazing, trampling and soil disturbances by livestock.
• Activation of Acid Sulphate Soils.
• Altered fire regimes.
• Rubbish dumping.

Riverflat Eucalypt Forest communities are identified as being affected by the following Key Threatening Processes.¹

• Clearing of native vegetation.
• Anthropogenic climate change.
• High frequency fire.
• Predation, habitat destruction, competition and disease transmission by feral pigs.
• Invasion of native plant communities by exotic perennial grasses.
• Removal of dead trees and dead wood.
• Alteration to the natural flow regimes of rivers, streams, floodplains and wetlands.

Management Issues

• Disturbance and activation of acid sulphate soils may result in changes to the extent and composition of this community.
• Coordinating planning and management practices across whole catchments to conserve, manage and improve this vegetation type.
• Urban expansion may result in the increase of human impacts such as clearing, altered hydrological regimes, rubbish dumping, urban pollution and bushfires.

Useful web links

• Department of Environment and Climate Change – www.dec.nsw.gov.au

Further Reading

• Keith, D. (2004) Ocean Shores to Desert Dunes: The Native Vegetation of New South Wales and ACT. Dept of Environment and Conservation (NSW).

Bibliography

1. NSW Scientific Committee (December 2004) – Final determination to list River-flat Eucalypt Forest of the NSW North Coast, Sydney Basin and South East Corner bioregions as an Endangered Ecological Community.
2. C.L. Murphy Ed. (1993) Soil Landscapes of the Gosford/Lake Macquarie 1:100,000 sheet, Soil Conservation Service of NSW.