Lowland Rainforest on Floodplain in the New South Wales North Coast bioregion - Determination to make a minor amendment to Part 3 of Schedule 1 of the Threatened Species Conservation Act

The Scientific Committee is of the opinion that the amendment is necessary or desirable to correct minor errors or omissions in the Determination in relation to the Thackway and Cresswell (1995) reference.

NSW Scientific Committee - final determination

The Scientific Committee has found that:

1. Lowland Rainforest, in an undisturbed state, is a closed canopy forest characterised by its high species richness and structural complexity. In disturbed stands the canopy continuity may be broken, or the canopy may be smothered by exotic vines.

2. Lowland Rainforest on floodplains covers less than 1000 hectares in NSW and remaining stands are small and isolated. Stands occur in the New South Wales North Coast bioregion. Bioregions are defined in Thackway and Cresswell (1995).

3. Historically, the major cause of loss of rainforest on floodplains was clearing for agriculture.

4. Subsequent to clearing the disturbed and exposed edges of remnant stands were vulnerable to invasion by exotic plant species; nearly all surviving remnants are subject to this threat.

5. The effects of clearing, fragmentation and isolation on the functional ecology of the remnant stands has been little studied, but impacts on plant regeneration (including pollination and seed dispersal) are likely. Many of the tree and shrub species are obligate outbreeders so that disruption to pollinator systems could have long term, deleterious consequences.

6. Other threats, although not all are experienced at all sites, include fire, grazing, rubbish dumping, clearing for competing land uses (including clearing of understorey for recreational facilities ) and dissection by vehicular and foot tracks.

7. Although very few sites have been subject to detailed fauna survey, it is known that some sites possess an extremely rich insect fauna (documented in the case of Lansdowne Reserve by Williams GA (1993) Hidden Rainforests: subtropical rainforests and their invertebrate biodiversity. UNSW Press/Australian Museum, Sydney.) It is probable that other sites have comparable invertebrate diversity.

8. Although every stand of rainforest is unique in terms of biota, the similarity in structure and the presence of a core assemblage of species permit the definition of lowland floodplain rainforest as a distinct ecological community. This list of plants has been compiled to include species which are characteristic of NSW rainforest communities which occur on floodplains, although not all species occur in every stand, and individual species may be found in other communities. These include all or part of ten of Floyd’s Suballiances shown in Point 10.

9. The total species assemblage is much larger with many species restricted to one or a few sites, or present only in very low abundance. Not all the characteristic species are present at every site.

10. For particular purposes it may be appropriate to recognise categories within the lowland floodplain rainforest. The most widely used classification of rainforest types in NSW is that of Floyd, A.G. (1990) Australian Rainforests in New South Wales. Surrey Beatty and Sons, Chipping Norton. In this classification the major rainforest Suballiance within the nominated community is Suballiance 3: Cryptocarya obovata - Dendrocnide excelsa - Ficus spp - Araucaria. Elements of of Suballiance 1:Heritiera trifoliata, Suballiance 2: Toona - Flindersia, Suballiance 4: Elaeocarpus grandis, Suballiance 5: Castanospermum - Dysoxylum mollissimum, Suballiance 6: Archontophoenix - Livistona, Suballiance 23: Ficus-Streblus-Dendrocnide-Cassine, Suballiance 24: Castanospermum - Grevillea robusta, Suballiance 25: Streblus - Austromyrtus, Suballiance 26: Waterhousea floribunda - Tristaniopsis laurina and Suballiance 33: Ceratopetalum/Schizomeria - Heritiera/Sloanea also occur. These alliances are not restricted to lowland floodplains.

11. In any individual stand more than one Suballiance may be represented, and separation of Suballiances may, in some instances, be difficult as complex intergradations occur.

12. The following vertebrate species occur in, but are not restricted to, lowland rainforest on floodplains.

Birds

Mammals

Reptiles

13. A number of stands of the Community are found within the formal conservation reserves in the National Parks and Wildlife Service estate listed below, however the size of individual stands is small (only a few hectares). These stands are only a small proportion of the total distribution of the Community.

Andrew Johnston Big Scrub Nature Reserve

Boatharbour Nature Reserve

Brunswick Heads Nature Reserve

Coocumbac Island Nature Reserve

Coramba Nature Reserve

Hortons Creek Nature Reserve

Moore Park Nature Reserve

Stotts Island Nature Reserve

Susan Island Nature Reserve

14. The small and fragmented nature of these sites places them, as with stands outside NPWS estate, at risk of loss of integrity from weed invasion and other disturbances.

15. In the light of 2,3,4,5,6 and 14 the Scientific Committee is of the opinion that Lowland Rainforest on Floodplain within the New South Wales North Coast bioregion is likely to become extinct in nature in New South Wales unless the circumstances and factors threatening its survival or evolutionary development cease to operate.

Dr Richard Major
Chairperson
Scientific Committee

Proposed Gazettal date: 02/12/11
Exhibition period: 02/12/11 – 03/02/12

Reference:

Thackway R, Cresswell ID (1995) An interim biogeographic regionalisation for Australia: a framework for setting priorities in the National Reserves System Cooperative Program. (Version 4.0. Australian Nature Conservation Agency: Canberra.)