Aiming to assess, identify and protect Swamp Mahogany forests in New South Wales
Read about the recent listing of Swamp sclerophyll forest on coastal floodplains of the NSW North Coast, Sydney Basin and South East Corner bioregions - endangered ecological listing - to which this project contributed.
The Swamp Mahogany Project (SMP) was commenced in 1996 by volunteers following observations that much of these forests and other coastal lowland types were being lost to development. The project aims to promote the conservation of these forests by determining their range, composition, regional variations and conservation status (adequacy of reservation, threatening processes, ecological condition, threatened species, populations and communities). Data is being gathered from councils, agencies, ecological consultants and by community members working through the Nature Conservation Council's extensive community network.
The Community Environment Network (CEN) in partnership with the Nature Conservation Council of NSW and the Coastal Ecology Unit of the University of Newcastle at Ourimbah are cooperating to continue the project. The main aims are: to assess, identify and protect the Swamp Mahogany and associated coastal lowland forests of the NSW coast and to bring the SMP project to a conclusion. At that time an assessment will be made of how best to study the remaining coastal lowland forest types. The Swamp Mahogany Project seeks to answer several important questions....
- Is it possible to develop a series of definitions of a vegetation community for Swamp Mahogany and/or Coastal Lowland Forests that meets the requirements of the Threatened Species Conservation Act (1995)
- Are these communities either ‘critical habitat’ or an ‘endangered community’ ?
- What area of these forests remain, are these remnants sustainable?
- What is the regional distribution of these forests and how much is protected in National Parks or other conservation reserves?
- How important are these forest communities to the survival of threatened species both migratory and sedentary?
* Status refers to whether the land in which the community resides has an insecure tenure or if the forest has or is likely to become degraded through anthropogenic activities
Ecological Significance of Swamp Mahogany Forests
The Swamp Mahogany coastal forests are not only rare as an ecological community but are also important habitat for threatened species such as Yellow-bellied Glider and Koala.
They are often relatively small and disjunct remnant patches. They are of added ecological importance as Swamp Mahogany (Eucalyptus Robusta) is a prolific Winter flowering tree that provides a good supply of nectar at a time of year when there are few other such resources for the many species which require such a diet.
Swamp Mahogany is recognised as a major feed tree for Koala in SEPP44. Swamp Mahogany is not formally protected by SEPP14 (Coastal Wetlands) instrument and as a result is primarily under threat from urbanisation on the coastal strip. The coastal lowland forest’s role as a buffer to protect wetlands from adverse biotic and abiotic factors should be recognised.
Swamp Mahogany (Eucalyptus Robusta) extends from near Bundaberg, Queensland to Broulee, NSW.
As the name suggests Swamp Mahogany forest prefers low-lying swampy soil conditions. The species is commonly found fringing both freshwater wetlands and estuarine environments. The species is generally found within 50km of the coast. Clearing for rural and urban development has seen the forest become highly fragmented.
Consultant Notes Robert Payne (1997)
The Ecological Community- Eucalyptus Robusta
Swamp Mahogany Forest which occurs now only as remnants on the alluvial flats around Brisbane Water in Gosford City and the lakes within the Wyong Shire. It has a structural form ranging from Closed Forest to occurring as emergent's associated with Melaleuca Forest. It does not have a varied Understorey component due to its specialised waterlogged ecological conditions. However, its main vascular plant component includes: Gahnia clarkei, Baumea juncea, Carex appressa, Parsonsia straminea, Melaleuca quinquinervia, Melaleuca biconvexa, Melaleuca styphelioides, Melaleuca linariifolia, Melaleuca sieberi, Hypolepsis muelleri, Viola hederacea, Baumea articulata and Eleocharis sphacelata.
The Swamp Mahogany Forests have a very high interrelationship with fauna. Therefore, it is considered to be a 'keystone' species and essential to the survival of many species of nectivorous fauna. This is because it is the only major winter flowering community in the region and during this time many nectar seeking species flock to these forests to feed. This fact can be observed during any winter period. My surveys have shown that these Forests are habitat in this region for at least ten species listed under the Threatened Species Conservation Act (1995) and associated schedules: Yellow Bellied Glider, Squirrel Glider, Regent Honeyeater, Swift Parrot, Osprey, Wallum Froglet, Common Bent-wing Bat, Little Bent-wing Bat, Fishing Bat, (Large-footed Mouse-eared bat), Yellow-bellied Sheath-tail Bat. At Bensville for example, the Regent Honeyeaters return to feed each year and I am regrading this area as critical habitat for this species.
However, it is not only important for threatened fauna species, but for the general nectivorous component which is sometimes overlooked. This in particular includes the Grey-Headed Flying fox of which one known colony occurs in the area. (This area is subject to DA approval for a Golf Course by Gosford City Council in 1999 Editor.)
I have mapped the flowering periods of all the eucalypt communities in the region over five years. I found that Eucalyptus robusta was the only winter flowering community with Eucalyptus tereticornis flowering to a lesser extent. Corymbia maculata flowered in winter also but only once in every four to six years. Eucalyptus robusta was found to be the only consistent winter flowerer and the fauna appeared to rely upon this species.
I have mapped the vegetation in the Wyong Shire including these forests. I have also mapped the Swamp Mahogany Forests in Gosford using a GPS technique as part of a the upgrading of SEPP14 areas. Both information is available by contacting the relevant councils.
The forests are highly fragmented and very little of the remaining remnants occurs in National Parks. A small population occurs only in Wyrrabalong National Park. The conservation of this small amount will not ensure the survival of this community nor will it ensure the survival of our fauna which depend on these forests for survival. If the current trends continues the vegetation community will disappear from the region within the next decade. The community occurs in areas subject to inundation and which is generally unsuitable for development.