ROBIN OSBORNE reports from Lismore, in northern NSW, on the efforts to control a persistent import.
The war room was at the NSW Department of Agriculture's North Coast headquarters at Wollongbar, near Lismore, and the briefing was conducted by officers bearing charts and photos taken at the front lines.
After hearing talks from eight experts, who agreed that chemical attack provided the best hope of success, and inspecting the scene of two earlier battles, one victorious, the other less so, the 60-strong audience left the seminar keen to swing into action.
Their hatred of the camphor laurel tree had been confirmed, and they would take up arms against it on their own land.
While Cinnamomum camphora has a high reputation amongst woodcarvers, the "camphor" began to be viewed with concern not long after its introduction, when plantings for windbreak purposes were encouraged by government authorities.
In time it would become one of the most despised intruders on Australia's eastern seaboard — the local, botanical, version of the rabbit, with a breeding ability to match.
Starting from a handful of source trees, camphors have spread so rapidly that many patches have become closed canopy forests that could be cleared only with great difficulty and at huge cost. The worst local example covers 500 hectares with 70-plus-year-old trees that permit no growth underneath.
This renders the land useless for agriculture and creates an environment hostile to most rainforest species, once the dominant feature of far north coast ecology. In large stands, very few seedlings of the original rainforest species are found, or are likely to regenerate.
The reason for this is the camphor laurel's production of toxic substances that affect the growth of other plant species and give it a competitive edge. To achieve this, the tree relies on cineol and camphor, the latter accounting for its distinctive smell when cut.
Survival ability
According to Agriculture's Darryl Firth, who researched the camphor for his graduate thesis at the University of New England, Armidale, the tree has no natural enemies in this country and an amazing ability to survive.
"Cut one down and it will sucker up new growth nearby. Cut and poison most of a large tree, but miss a branch, and a vascular strand process will enable the surviving wood to make a new tree."
A native of China and Japan, it was brought here, via the Royal Kew Gardens in England, in 1822. While footholds exist in places as widespread as Spain, Egypt, Madagascar and California, nowhere has it gingly as on the Australian east coast.
Major communities now occur between Cooktown in the north and Nowra in the south. In Sydney, it is a problem only on neglected sites such as beside railway lines, but if ignored it could spread quickly in urban areas too.
Camphor's greatest concentration is in the 20 to 30 km wide, elevated red soil strip bounded by the Richmond and Tweed rivers in northern NSW. Here it thrives on a rainfall exceeding 1400 mm a year, taking over swathes of rainforest land that was cleared by farmers and turn-of-century loggers.
Such soil, with high acidity, seems to provide an advantage for the camphor laurel. But while it likes the rain, it detests wet feet and will not grow well in the often-flooded lowlands.
It revels in such disturbed environments as abandoned banana plantations and poorly utilised rocky hillsides. A mature tree can produce an incredible 100,000 viable seeds in a season, and these are fancied by many birds, which help the spread by excreting the kernels.
Because paddock fences provide ideal resting points for birds, they have become the camphor's launching pads in colonising more land. Seedlings are so tough that they can even defeat the thick grass competition which makes growing desirable trees almost impossible without the use of herbicides or constant attention.
On the coastal strip between Lismore and Mullumbimby, under-grazed or untended paddocks are seldom without camphor outbreaks, and knowledge that the tree has a lifespan of some 500 years has fuelled fears that camphors will win the battle unless challenged seriously.
Herbicide
Hence the department's latest campaign aimed at recruiting landholders — few of whom need convincing, but many of whom require advice.
"Bulldozing is a no-no in most situations", a soil conservation expert told the recent seminar, "because of the risk of exposing vulnerable soil to the erosive effects of rain and the likely recolonisation of bare ground by other weeds, including camphors".
Recommended is poisoning with a glyphosate herbicide — one common brand is Roundup — which can be injected into the tree's trunk, poured into axe cuts or painted onto the cut stump of smaller trees. Even so, a follow-up treatment might be needed, and then there's the problem of what to do with the eventual dead tree.
"Of course you can try to redeem the timber for cabinetmaking purposes, as in the East", said Darryl Firth, "but the catch is that trees need to have a bole or straight limbs of at least 30 cms in diameter. Trees must often be 20 years old before they reach this size, and many are still unsuitable because of deformed growth."
According to experts, only one camphor laurel in 20 has a stem worth harvesting, or can be described as having strong aesthetic value, with an evergreen and symmetrical canopy. Fortunately, I have two such grand specimens in my garden. Less happily, their seeds sprout in profusion in many unwanted places and are very hard to remove once the taproots have become established.
Woodcarving
Inspired by the famed camphorwood chests of Asia and the ready availability of the timber here, local woodcarvers are producing some superb furniture and decorative works. Camphor has a blonde hue, often bearing highlights of dark brown grain.
One fan of this region's most devastating "woody weed" is Sandra Heuston, who runs a cooperative called Wooden Works, which markets the carvings of North Coast artists.
Often they use rainforest timber, even the prized red cedar, which has been recovered from trees that fell because of disease or storm damage. But camphor laurel is increasingly on their workbenches, partly because of availability but also because of what Heuston calls its "reverse snob value".
"You can't be more environmentally sound than working with a timber which is both hostile to our environment and in no danger of becoming extinct. Yet artistically, it has a superb appearance and is very durable."
She has shaped tables, bowls and boxes from it, outlaying little for the raw material, an important consideration at a time when dollars are not flowing freely. Clients have been delighted with the result, she reports. Like all local residents, however, she is surrounded by evidence of the tree's spread, and agrees that control measures are vital.
Alternate view
What these should be is seldom disputed, although Richard Staples of the Byron Environment Centre told the seminar that chemical control could be more environmentally damaging than the camphor laurel itself. He wondered whether the problem was too many trees capable of seeding or too much cleared land that could foster seedling growth.
Living on a farm near Bangalow, Staples follows the permaculture method — which advocates landholdings of around 3 ha per family — and believes that the "small is better" ideal enables landholders to keep better control of affairs, including weed spread.
Predictably, he took issue with Ron Bollard of the Monsanto company (the maker of Roundup) and regretted the presence of a chemical multinational at such a seminar.
However, even professional environmentalists felt that glyphosate control of camphors was acceptable, saying that the product does, as claimed, break down into harmless components when in contact with the soil.
Staples, in turn, referred to Monsanto's allegedly suppressed research data in the USA, and circulated leaflets urging camphor control by encouraging root rot with heavy, wet mulching. Ironically, it would be undesirable to aim at camphor's eradication, according to Robert Kooyman, the district forester from Murwillumbah.
"If we blitzed the camphor we'd have wildlife problems, because the seed is now a valuable food for birds which have lost their access to rainforest seeds, and it provides sanctuary for small animals, many of them threatened species. (The reverse applies in plantation forests of imported pines.) That's why we advocate replacement plantings, done on a phased basis."
Kooyman is promoting native hoop pine, which can also be reliably harvested, and mixed rainforest trees which, despite their reputation for fragility, can be planted in unprotected sites unless conditions are exceptionally severe.
The natural seed bank that remains under the ground should also be encouraged to spring forth, he said. "This is rainforest country and the trees are waiting to get going."
A cheering thought is that camphors, being, in the words of Firth, "a product of the disturbed ecosystem", will not invade existing forests.
As in so many environmental areas, the message is clear: repair the damage and the symptomatic problems are likely to diminish.