JERRY: Spring Creek is in Brisbane.
In fact, it's just a 20-minute drive from the CBD.
It flows naturally from Belmont Hills to Bulimba Creek.
It's an important wildlife corridor,
and there are sugar gliders which breed here.
But even here threats are lurking, like behind me -
the notorious camphor laurel tree.
Native to Asia, the camphor laurel, Cinnamomum camphora,
is widespread in both NSW and Queensland,
where it's a declared noxious weed.
Stefan Hattingh is an ecologist
with the Bulimba Creek Catchment Coordinating committee,
and he knows all about this invasive tree and its history.
These camphor laurels, they were brought into Australia in the 1820s,
and that's the garden for you.
A very popular, very shady tree.
They grow quite high, they're tall, massive and dense shade.
They're very competitive with the native trees.
What's the best way to identify a camphor laurel?
If you take some of the leaves...
I mean, it's got a very glossy leaf like this.
But you just rub it in your hands and smell it.
It's got a very, very distinct camphor smell.
They produce a lot of fruit,
and that's a problem with a tree like the one behind me here.
They can produce about 100,000 seeds per season.
And it's spread by the birds.
They create a very, very thick foliage,
so very dense shade underneath,
and basically it out-competes all the native plants.
They have an ability to manufacture chemicals
which suppress the seedlings of other plants.
They're allelopathic, aren't they?
Yes, the oils that's in them, in the camphor laurel,
the alkaloids and things that's in the leaves
and in the root system,
which means the alkaloids leach out into the soil
and that kills all their competitor seedlings and plants.
And if you look around us, there's virtually no groundcover here.
It's bare, with no natural vegetation underneath,
and that becomes a real big problem for us,
especially in creek lands and in your natural bushland
because it creates process... or it can facilitate erosion.
Now, removing these trees is an option,
but it's not necessarily the best one.
Where we stand here, it would be extremely difficult
to get big machinery in, for instance, to come and remove this.
You'll have to cut a track through native vegetation
to get the machinery in.
And it is very expensive.
It's a challenge for us to control these camphor laurels.
And because they grow so dense, they become almost a monoculture,
and through time, you know,
you get constant degrading of the creek line.
For every problem, there's an opportunity,
and that's where arborist Steve Collom stepped in
to transform camphor laurels into unique habitat trees.
So, Stefan, how did you meet Steve?
I attended a conference on the Gold Coast,
and Steve presented his new out-of-the-box thinking
of cutting hollows into old eucalypt trees
instead of removing them.
And we need to get rid of these camphor laurels in this bushland.
I suggested we try and kill the trees standing
and cut hollows in them and create habitat
instead of turning it into mulch.
The camphor laurels are ringbarked at the base to kill them,
and then the canopy is reduced heavily for safety
to stop large limbs breaking off.
Then they're ready to get the hollows added.
Australia's got such a wide variety of fauna that depend on hollows.
There's over 300 different species.
And this is why we need to act now and really start taking note of
looking after the hollows that we have,
and then trying to create more.
How do you go about creating nesting hollows?
Well, Steve is going to take us through the process,
firstly, with a cut-down demonstration model
so we can take a closer look.
Is it possible to custom-make these to suit different species of animal?
Yeah, that's right, it is. It's important to do that as well.
We never do two the same. They're all slightly different.
We look for different features on the tree like this.
So we have to work with what the tree gives us.
So if there's a feature that we can utilise for an entrance,
or another feature that we can utilise for a larger nesting space,
they're the things that we will look at on the ground
and then plan how we are going to create the hollow within the tree.
Carving an actual hollow high up on a dead camphor laurel
takes special equipment, an arborist's skills,
and, of course, a head for heights.
Fortunately, Steve's younger brother, Ross, is up for the job.
Sections of the trunk are carved out, hollowed
and screwed back onto the tree,
forming a lid over an internal cavity.
It's a pleasure doing this on camphor
because it's such a pliable timber.
It's nice and soft. It's good for the equipment.
But also it means that we can do
twice as many hollows within a large camphor like this
than we would be able to in a eucalyptus.
So, how long would these hollows last on these trees?
I'm hoping these would last...
..I'd be confident to say 15 to 20 years.
This amazing project means less invasive trees
and more habitat hollows,
so it's a win-win for the environment and, of course, the native wildlife.
What do you think of Steve's work here?
I think it's amazing.
I mean, this is a tree that is actually creating problems for us
but now we're turning it almost into a benefit.
And it's almost an asset for bushland
because previously we didn't know what to do with these big trees.
And they provide such an opportunity here.
This much bulk timber for us to carve hollows in
and then for them to become active, it would be fantastic.