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Camphors – The Silent Killers

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Camphor Laurels – the silent killers of biodiversity.

It’s been nearly 200 years since the first Camphor Laurel (Cinnamomum camphora) was planted in Australia. Native to Asia, the tree was introduced in the early 1820s and first recorded at the Sydney Botanic Gardens.

When people noticed its rapid growth and attractive light green foliage, it quickly became a popular tree to plant for much needed shade. In 1872, the introduction of Arbor Day saw hundreds of thousands of Camphor laurels being planted in schools, church and courthouse grounds and in council parks and gardens. Many of these long-lived trees still line streets of cities and towns today, some being heritage listed. Little did we know that this evergreen beauty would become the most invasive weed species ever to reach Australian shores.

New visitors to the North Coast Region of NSW would be unaware that the picturesque sea of light green they see spreading along creek lines and over hillsides was once a darker shade. The ‘Big Scrub’ covered 75,000 hectares and was the largest subtropical lowland rainforest in eastern Australia until it was cleared for agriculture in the 1840s. The contraction of dairying and banana farming since the 1960s has resulted in large areas becoming infested with camphor laurel. This region includes one of Australia’s 15 biodiversity hotspots and is considered the most biodiverse area in the state. It supports the greatest number of plant and animal species of any area of NSW, and includes the greatest number of threatened species.

The Camphor laurel has divided communities for many years and there have been heated debates as to whether century old trees should stay or be removed.

Gold Coast botanist and consultant David Jinks, like many others, has strong views about Camphor laurels; his work brings him into contact with them almost on a daily basis. He said the need for shade isn’t so immediate that it should override the lethal threat Camphors are to local biodiversity.

“They are a beautiful tree. Where I lived in suburban Sydney, I spent much of my childhood climbing them and I have no doubt they had a very strong impression and positive influence on my long-term career in and love of all things plants.

“But I’m now very aware of their rapidly increasing threat to our rapidly decreasing local biodiversity. Of all the threatening weeds, they are enemy No.1 – by a long-shot. And they’ve yet to reach their epic peak.

“Camphor Laurels are in almost every local vegetation type from urban to wilderness hinterland. I’m currently working on an 85 hectare hinterland property of mostly good bush. We thought we’d have a hundred or so Camphors to deal with but, 18 months later, we’ve killed nearly 400 seeding trees plus taken out thousands of saplings and seedlings. Of the many weed species on site, the only one at every monitoring plot is Camphor Laurel. I’m sure this could be repeated on every similar adjoining property.”

“The need for shade isn’t so immediate that it should override the lethal threat Camphors are to local biodiversity.”

David said Camphor laurel is, without doubt, a slow-motion silent killer of local biodiversity that most people don’t get to see. This highly invasive tree has a tendency to form single species communities and exclude most other desirable native vegetation.

“The only way to reverse the spread of Camphor Laurel is to kill as many trees as possible, as soon as possible. To be completely effective there must be no more Camphor Laurel seed to spread. Put the effort instead into immediate control.

Kill the Camphor Laurel and replace it with a fast growing shade tree,” David said.

A passionate artist and tutor Matty George with his prized turtle chainsaw carving at Camp Creative, Bellingen, earlier this year. Organisers had to reassure some participants that the Camphor laurel timber being used didn’t come from the controversial Church Street tree that was recently chopped down in the main street. Teddy Reynolds shows off dad Paul’s work of art at the chainsaw carving workshop at Bellingen.

A spokesperson from the NSW Department of Primary Industry said Camphor laurel has never been a priority weed at the state level because it is well established in NSW and is very commonly used as an ornamental tree and council street tree. It is therefore not a prevention target.

Weeds are regulated by NSW local government and any efforts to reduce numbers would have to be done at a local or regional scale. Regional Weed Committees prepare and maintain a priority weed list, which includes state priorities; however, it is up to each Regional Weed Committee to determine what is a regional priority for control programs.

Federal Government Grant for project on deflowering Camphor laurels.

The introduction of the Biosecurity Act 2016, which specifically focuses on the shared liability relating to the containment and control of weeds, has been encouraging for weed committees.

A federally funded project commenced in July 2017 to undertake research to scope a handful of chemicals to de-flower or prevent fruit from developing on Camphor Laurel.

The Weed Society of New South Wales Inc. reported in its newsletter ‘A good weed’ there would be potential to use this technique, if successful, on other species.

How To Kill Camphor Laurel?

Contact your local Weed Advisory Service for correct chemical application before cutting a 20-30cm high strip into the outer bark and moist cambium layer to expose the heartwood (approximately 3-5cm deep) all of the way around the trunk. Return to check for suckers in 3-6 months.

Other uses of Camphor laurels Camphor laurel is being trialled as a potential fuel biomass in a north coast cogeneration project to produce electricity. Proposals are advanced to use woodchip for fuel to generate electricity at the Condong and Broadwater Sugar Mill cogeneration plants. This will involve the harvest of camphor laurel on a significant scale to supply this project.

Camphor laurel can be a valuable resource as a commercial timber and is used for a range of products and furniture and various items that can be turned on a lathe.

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