By Kris Grace-Hely
Ecological Restoration Strategies, Coffs Harbour NSW
Coramba Nature Reserve
At nine hectares, Coramba Nature Reserve is the largest intact remnant of Lowland Subtropical Rainforest on Floodplain in the southern Clarence Catchment. The Reserve is located west of Coffs Harbour on the NSW mid north coast, near the township of Coramba. In the early 20th century, it was reserved and was spared from the clearing that occurred on the rest of the Orara River Floodplain.
Declared a Nature Reserve in 1979, it wasn’t until 2001 that a restoration program commenced. I am forever grateful that I was one of the three regenerators privileged enough to be engaged by NPWS to work there.
The primary ecological threat was dense swathes of trad (Tradescantia fluminensis) preventing natural regeneration of rainforest trees and eliminating native groundcovers – creating large areas where no successional regeneration was occurring. Other invasive species present were canopy weeds large-leaf privet (Ligustrum lucidum) and camphor laurel (Cinnamomum camphora), and a small infestation of cat’s claw creeper (Macfadyena unguis-cati).
Rainforest trees at Coramba Nature Reserve
In the first four years, the restoration works were undertaken at regular intervals, greatly reducing the presence of trad allowing natural regeneration to take place. Privet, camphor and cat’s claw infestations were controlled, and the western edge was expanded with revegetation plantings. When however, there was a significant reduction in the scope of the works program the Tradescantia began to rapidly recolonise areas.
The recommended herbicide mix (50:1 Glyphosate with LI700) was not translocating effectively and respraying was required frequently, approximately every 6-8 weeks, to attain control. The frequent use of LI700 was concerning to me for several reasons. Health risks to the operator (frequent headaches were common after use), the effect on soil biota and the population of giant barred frogs in the Reserve. I knew from observations working on the cats claw control program on the Orara River that vegetable oil added to the mix instead of LI700 was effective, but there was still rapid reshooting eight or so weeks after application. This was presumably because the foliar spray didn’t translocate through past the nodes and any fragments covered by leaf litter etc simply kept on growing.
In about 2008 I became aware of a research paper from the Victorian viticulture industry that found adding fulvic acid to glyphosate foliar sprays was increasing efficacy of the glyphosate and mitigating damage to soil biota. I conducted some trials on trad on my own property and found that foliar spraying of glyphosate at 100:1 with fulvic acid (and vegetable oil as a surfactant) enhanced translocation, decreasing amounts of reshooting fragments substantially and increasing respray time to approximately 16 weeks. This greatly altered the resources required for trad control in the nature reserve and meant gains started to be made in the regeneration process despite the funding shortfalls.
However, covering 9 hectares with only 50 hours per year still meant the whole of the reserve could not be covered effectively. The dilemma was to either focus on areas where trad coverage was minimal to prevent its expansion or to focus on areas of higher light levels, e.g. edge areas or where tree falls had occurred, where trad growth was rampant. I chose the latter, but it was always a case of two steps forward and one back. And it wasn’t just trad that needed control. Upstream weeds such as cat’s claw creeper were a constant threat after every flood.
Then in 2023 two factors enhanced the restoration program. Firstly, the NSW Save Our Species (SOS) program had funding for Subtropical Lowland Rainforest which became available enabling the whole reserve to be covered with a follow up within 16 weeks. Secondly a new biocontrol agent called ‘leaf smut’ or ‘Trad Smut’ was released in the reserve. Combining these factors was a significant breakthrough.
Trad showing the effect of Trad Smut.
The introduction of the Trad Smut had a dramatic effect on trad presence and vigour. It didn’t eliminate trad, but it made it less of a threat. In areas where trad was covering regenerating native tree species, the smut made it possible for young trees and seedlings to grow through, instead of being smothered. Ground layer species, especially those in the Commelinaceae family, were able to gain dominance over trad. Overall, it prevented rapid trad growth in warm wet periods. In ecosystem restoration the concern is not about weed species per se but rather the effect that they have on natural ecosystem functioning (eg some weeds have no effect on natural regeneration processes; some assist it, especially relevant in rainforest restoration…but that’s another article).
With trad no longer dominating, and natural regeneration occurring, the change to the ground and mid layer is dramatic. Swathes of seedlings and saplings are now present throughout; native ground layer species dominate the flood channels. South and western edges have been expanded via revegetation and assisted natural regeneration. For myself it is a heartwarming experience to see this place, that I care for so deeply, flourishing.
Flood Channel at Coramba Nature Reserve
But despite these gains made, vigilance is always required as in each flood upstream weeds are deposited, including Anredera cordifolia (Madeira vine). Over the past four years I have found three small Anredera tuberlings and recently located a small vine on a neighbouring property that had formed tubers. Cats claw creeper seedlings also appear occasionally after floods as does small leaf and large leaf privet.
Unfortunately, adjoining landholders are problematic, not understanding the significance of what they have on their doorstep, with wandering stock and adjacent weed infestations a constant threat. Some of the adjacent land is zoned as riparian buffer, technically under Crown Land control, but this is not enacted on. In the past when adjacent properties have been for sale, I contacted NPWS acquisitions section, but due to its small size the reserve is not counted as a priority. To truly protect these precious rainforest remnants, they require continued management, expansion and advocacy.
Working there on hot summer days and leaving the cool moist canopy bursting with life you enter onto a hot baking floodplain dominated by setaria and Parramatta grass, interspersed with privet and camphor. The climatic and biodiverse disparity between the two is dramatic. Coramba Nature Reserve is a precious place, a small island representing what once was and what has been destroyed, and an inspiration to many of what could be.
Photos supplied by Kris Grace-Hely
Aerial View taken from a “Coffs Collection” video which can be seen Here
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