Community Description

• Swamp Oak Floodplain Forest (SOFF) of the NSW North Coast, Sydney Basin and South-east Corner Bioregions is an Endangered Ecological Community (EEC) dominated by Casuarina trees. This community is associated with estuarine fringes and coastal floodplains.¹
• The structure of the community varies from open forests to low woodlands, scrub or reedlands with scattered trees.
• Generally occupies low-lying parts of floodplains, alluvial flats, drainage lines, lake margins and fringes of estuaries where flooding is periodic and soils show some influence of saline ground water.
• The plant composition and structure of this community is primarily determined by the frequency and duration of waterlogging and the level of salinity in the groundwater.¹
• The dominant species within this community is Casuarina glauca (Swamp Oak).
  
• Other trees including Acmena smithii (Lilly Pilly), Glochidion ferdinandi (Cheese Tree) and Melaleuca species (Paperbarks) may also occur.
  
• The understorey is characterised by frequent occurrences of vines such as Parsonsia straminea (Common Silkpod), Geitonoplesium cymosum (Scrambling Lily) and Stephania japonica var. discolor (Snake Vine).
  
• Prominent ground layer plants include forbs such Centella asiatica (Pennywort), Commelina cyanea and Persicaria decipiens (Slender Knotweed); graminoids such as Carex appressa (Tussock Sedge), Gahnia clarkei (Saw Sedge), Lomandra longifolia (Spiny-headed Mat-rush), Oplismenus imbecillis; and the fern Hypolepis muelleri (Batswing Fern).
• The composition and structure of the vegetation is influenced by disturbances such as: grazing, changes to hydrology and soil salinity, clearing and uncontrolled access. This community is also often affected by weed invasion.

Habitat Requirements

Landform: Saline or sub-saline waterlogged or periodically inundated flats, drainage lines, lake margins and estuarine fringes associated with coastal floodplains.

Distribution: Swamp Oak Floodplain Forest occurs in localised areas along the entire NSW coast.¹ Locally this community generally occurs along the margins of coastal lakes, lagoons, inlets and coastal streams.

Elevation: This community generally occurs below 10m elevation but sometimes up to 20m AHD.

Soil: The soils are usually grey-black clay-loams and sandy loams, where the groundwater is saline or sub-saline, on waterlogged or periodically inundated flats. Swamp Oak Floodplain Forest is most commonly found on estuarine soils such as those occurring in the Mangrove Creek and Cockle Bay Soil Landscapes of the Central Coast.²

Hydrology: This community is associated with areas affected by flooding, irregular inundation or waterlogged subsoils.¹

Where this Community can be Found

Gosford: Backswamps along the Hawkesbury River; Upper reaches of Avoca Lake; Floodplain of Erina Creek South of Wells Road.

Wyong: Geoffrey Road, Chittaway Point; Tuggerah Lake Foreshore, The Entrance; Louisiana Road, Kanwal.

Lake Macquarie: Foreshores of Dora Creek as far as Stingaree Point, and Foreshores of Warners Bay; Cockle Creek near Macquarie Park.

Where this Community is Protected

Small areas of Swamp Oak Floodplain Forest are contained within existing conservation reserves, including Wamberal Nature Reserve, Cockle Creek Nature Reserve, Wyrrabalong National Park and Pulbah Island Nature Reserve.

Threats to survival

• Alteration to natural hydrological regimes.
• 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.

Management Issues:

• Management of water flows in the future may result in the expansion of some drier communities at the expense of Swamp Oak Floodplain Forest.
• 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 will result in the increase of human impacts such as clearing, altered hydrological regimes, rubbish dumping, urban pollution and fires.

Useful Web Links:

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

Further Reading

• Bell, S.A.J. (2002) The Natural Vegetation of the Wyong Local Government Area, Central Coast, New South Wales. Vegetation Community Profiles.  Final Report to Wyong Shire Council.
• Bell, S.A.J. (2004) The natural vegetation of the Gosford Local Government Area, Central Coast, New South Wales: Vegetation Community Profiles. Final Report to Gosford City Council.
• National Parks and Wildlife Service (2003), Lower Hunter and Central Coast Regional Environment Management
  Strategy Vegetation Survey, Classification and Mapping: Lower Hunter and Central Coast Region. CRA Unit, National Parks and Wildlife Service, Hurstville.

Bibliography:

1. NSW Scientific Committee (December 2004) – Final determination to list Swamp Oak Floodplain 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.