Sub-tropical Coastal Floodplain Forest - profile

Scientific name: Sub-tropical Coastal Floodplain Forest of the NSW North Coast bioregion 
 Conservation status in NSW: Endangered Ecological Community

Description

This sub-tropical forest occurs on the coastal floodplains of the North Coast of NSW. It has a tall open tree layer of eucalypts, which may exceed 40 m in height, but can be considerably shorter in regrowth stands or under conditions of lower site quality.

While the composition of the tree stratum varies considerably, the most widespread and abundant dominant trees include Eucalyptus tereticornis (forest red gum), E. siderophloia (grey ironbark), Corymbia intermedia (pink bloodwood) and, north of the Macleay floodplain, Lophostemon suaveolens (swamp turpentine).

Other trees may be scattered throughout at low abundance or locally common at few sites, particularly where there is an influence from lithic substrates upslope. These include Eucalyptus moluccana (grey box), E. propinqua (grey gum), E. seeana (narrow-leaved red gum), Angophora subvelutina (broad-leaved apple), E. robusta (swamp mahogany), Eucalyptus resinifera subsp. hemilampra (red mahogany), E. acmenoides (white mahogany), Angophora woodsiana, A. paludosa and rainforest trees such as Ficus spp. (figs) and Cupaniopsis spp. (tuckeroos).

A layer of small trees may be present, including Allocasuarina torulosa (forest oak), Alphitonia excelsa (red ash), Glochidion ferdinandi (cheese tree), Callistemon spp., Melaleuca spp. and Casuarina glauca (swamp oak).

Scattered shrubs include Breynia oblongifolia, Acacia concurrens, Commersonia spp., and Hibiscus spp. Occasional vines include Eustrephus latifolius, Parsonsia straminea and Geitonoplesium cymosum. The groundcover is composed of abundant forbs, scramblers and grasses including Imperata cylindrica, Themeda australis, Vernonia cinerea, Dianella caerulea, Pratia purpurascens, Cheilanthes sieberi and Dichondra repens.

The composition and structure of the understorey is influenced by grazing and fire history, changes to hydrology and soil salinity and other disturbance, and may have a substantial component of exotic grasses, vines and forbs. For a comprehensive list of species that characterise the community open the Scientific Determination link in the top right box.

Location and habitat

Distribution
 Subtropical Coastal Floodplain Forest is known from parts of the Local Government Areas of Tweed, Byron, Lismore, Ballina, Richmond Valley, Clarence Valley, Coffs Harbour, Bellingen, Nambucca, Kempsey, Hastings, Greater Taree, Great Lakes and Port Stephens, but may occur elsewhere in this bioregion. Major examples once occurred on the floodplains of the Tweed, Richmond, Clarence, Macleay, Hastings and Manning Rivers, although smaller floodplains would have also supported considerable areas of this community.

The extent of the Subtropical Coastal Floodplain Forest prior to European settlement has not been mapped across its entire range. However, the remaining area of Subtropical Coastal Floodplain Forest is likely to be considerably smaller and is likely to represent much less than 30% of its original range. There are less than 350 ha of native floodplain vegetation on the Tweed lowlands.

Small areas of Subtropical Coastal Floodplain Forest are contained within existing conservation reserves, including Stotts Island, Ukerebagh and Limeburners Creek Nature Reserves and Bundjalung and Myall Lakes National Parks. These are unevenly distributed throughout the range and unlikely to represent the full diversity of the community.

• Occupies central or marginal parts of floodplains and sandy flats, including Pleistocene back-barrier flats; habitats where flooding is periodic and soils are rich in silt and sand, sometimes humic, and show little influence of saline ground water.
• Associated with clay-loams and sandy loams, on periodically inundated alluvial flats, drainage lines and river terraces associated with coastal floodplains.
• Generally occurs below 50 m, but may occur on localised river flats up to 250 m elevation.
• The structure of the community may vary from tall open forests to woodlands, although partial clearing may have reduced the canopy to scattered trees. Typically these forests and woodlands form mosaics with other floodplain forest communities and treeless wetlands, and often they fringe treeless floodplain lagoons or wetlands with semi-permanent standing water.

Regional information
This species is found in the following catchment management authority regions. Click on a region name to see more details about the distribution, vegetation types and habitat preference of the species in that region.

• Hunter/Central Rivers
• Northern Rivers

Threats

• Further clearing for urban and rural development, and the subsequent impacts from fragmentation
• Flood mitigation and drainage works.
• Management of water and tidal flows
• Landfilling and earthworks associated with urban and industrial development
• Grazing and trampling by stock and feral animals (eg. pigs)
• Changes in water quality, particularly increased nutrients and sedimentation
• Weed invasion
• Climate change
• Activation of acid sulfate soils
• Removal of dead wood
• Rubbish dumping
• Frequent burning which reduces the diversity of woody plant species

Recovery strategies

Priority actions are the specific, practical things that must be done to recover a threatened species, population or ecological community. The Department of Environment and Conservation has identified 2 priority actions to help recover the Sub-tropical Coastal Floodplain Forest in New South Wales.

What needs to be done to recover this species?

• Promote public involvement in restoration activities.
• Instigate feral animal control programs.
• Ensure that the fire sensitivity of the community is considered when planning hazard reduction and asset management burning.
• Protect habitat by minimising further clearing of the community. This requires recognition of the values of all remnants in the land use planning process, particularly development consents, rezonings and regional planning.
• Promote regeneration by avoiding prolonged or heavy grazing.
• Co-ordinated planning and management approaches across whole catchments will be required to address and resolve priorities between different management objectives.
• Weed control.
• Undertake restoration including bush regeneration and revegetation.

References

• NSW Scientific Committee (2004) Subtropical coastal floodplain forest of the NSW North Coast bioregion - Endangered ecological community determination - final. DEC (NSW), Sydney.