Carving Deadwood, Creating Wildlife
New and valuable real estate is being carved into our urban landscapes by the very experts trained to cut away the dead wood. Conservation Arborists on the NSW South Coast are turning their chainsaws and their passion for wildlife to creating tree canopies of the future.
by Cat Holloway / (for embedded content, view on the Spark website)
Terence Miller and Josh Anderson love climbing trees, especially when they encounter birds, possums, lizards and gliders. But what these South Coast arborists don't love doing, is cutting down those trees.
So, they found a better solution: turning dead trees into homes - for wildlife. One person's deadwood is another creature's lifeline.
Miller and Anderson started the South East Arborist Collective (SEAC) to encourage and support other tree care specialists into a groundswell of Australian conservation arborists creating hollow habitats for animals to live inside, while also making trees safe for the humans living next door.
Instead of immediately cutting down an entire dead tree, arborists can trim the unstable branches and carve or drill hollows into the remaining tree trunk, leaving what is called a "stag" tree standing.
Of course, SEAC's idea is exactly what nature has done in forests for millennia. Indeed, tree hollow habitats in dead or damaged trees are crucial for the survival of more than 300 species of native Australian birds, mammals, reptiles and amphibians.
The "failure" of a tree branch is exactly what makes a tree successfully form a hollow. But that essential natural process in Australian natives takes between 70-100 years.
A 2001 CSIRO study of Jarrah and Casuarina in Perth found that arthropod abundance and diversity on the stags were the same as on live trees. A University of Queensland study in the South East found that around half of the hollow-bearing trees used by gliders, bats, birds and reptiles were in dead but still-standing trees. Some glider species, that depend on multiple hollows in their home range, actually favoured stag hollows for their nests.
In Sydney, Brisbane and Melbourne the practice of using conservation arborists to secure stags and carve hollows into the trimmed stump, instead of getting rid of the tree altogether, has gained momentum.
But on the NSW south coast, the mindset is only just beginning to shift - with the Shoalhaven well behind the rest of the state as the only region with the "45 degree rule" that allows tree removal without council permission and without having to use a certified arborist.
"It's completely backwards...it should not have even been a rational thought on council's behalf," Miller said
"There's so much fearmongering.
"Trees are hotels for animals and they need to be thought of a bit differently - there's a lot more value to old trees than what people are putting onto them at the moment.
"The widespread word is that trees are dangerous and they're going to fall on your house and kill you. But professional tree care can mitigate those risks.
"Underpinning attitudes is that old school forestry mentality of viewing trees just as a resource .
"Councils manipulate the public's lack of understanding of tree management legislation so that council can build houses easier by clearing land easier and getting more council rates.
"It's about suiting their agenda and shifting responsibilty. It's got nothing to do with tree management."
With so much habitat clearing and bushfire damage, ecologists working in species recovery are building bird and possum boxes to install in key locations where tree hollows are depleted.
But that solution is expensive, slow and has less appeal to the animals than a real tree hollow.
While endangered Greater Gliders have taken well to nest boxes in one World Wide Fund for Nature (WWF) project, hundreds of nest boxes installed in Australian National Parks in recent years have had variable success with non-target species using the boxes, incorrect placement, heat and too small a supply of nest boxes proving the major hurdles yet to be overcome.
SEAC's Miller and Anderson believe there is great potential for climbing arborist skills to be used in fire or otherwise damaged National Parks and conservation areas to create much-needed hollows, quickly and cheaply.
Miller, an experienced Level 3 arborist and now Environmental Science student says forest fauna is more likely to use carved hollows than built boxes because "animals inherently know what to look for".
"We can create hollows that are more natural in appearance and more natural in where they sit in the tree."
"Animals are looking for security and safety when they're searching for hollows, so hollows with little lids in strategic places tend to have higher rates of residency.
Most people see a dead tree - or an old tree - as a dangerous tree.
However, while the mortality rate in Australia for falling out of bed was 1 in 420,000 in 2011. The mortality rate in Australia for accidental tree failure while inside a house was 1 in 189,000,000 in 2019.
Josh Anderson, also a Level 3 arborist, believes that with education and good communication from industry professionals, more people will embrace the concept of carving hollows into old trunks that don't need to be entirely removed and can house animals for another decade or much longer.
"Cutting down trees is only a part of our job. A lot of our job is pruning and mitigation," Anderson said.
"We'll definitely opt to at least talk to the client about removing a tree altogether, and suggest, 'you maybe want to think about it, because once it's gone, you can't put it back'.
"There are options to pruning your tree in a way that is beneficial to you, your finances, the tree, the environment, conservation, everything."
Anderson said that the skills and equipment required to prune a tree to make it safer are greater than the skills required to remove a tree.
"I think like a lot of people get into tree work purely based on the money in the removal side because that is an easy business model to achieve.
"Truck, chipper, a couple chainsaws - you can start running around doing anything from house height to main power line height - it doesn't take much technical skill or professional understanding.
"But if you start looking at how to manage a tree or a property or a group of trees, and do that well so that it causes the trees to thrive, that's sustainable.
"You could charge much more for a tree removal, but then the tree is gone."
Adding to the cut-it-down culture is the complication of liability and insurance. Anderson said that even with training, experience and due diligence to mitigate hazards, tree management is not an exact science.
"It's nature, so that there's always a chance that a tree could uproot or that a branch could still snap off.
"But you've got to think, that tree's been there for tens or hundreds of years, holding and supporting that structure.
So when you trim or prune to reduce that wind load and weight by such a large scale, the chances of it failing become a lot less."
The main question around introducing cavities into trees is: will it fail? Will the man-made hollow cause structural failure of the tree?
Arborists from Treetec in Melbourne have installed over 2000 cavities and said they have "learnt enough to know how much we haven’t learnt".
According to Treetec, "the host tree almost never fails if the cavity is well designed, carefully positioned and conservatively sized, and the hollow is placed in a suitable tree."
"Observations suggest that if properly designed and executed, introduced cavity projects are beneficial and well suited to urban settings and parklands." - Treetec
Mosman Council has produced a document encouraging residents to consider "habitat stag creation" and showing details of designs of carved habitats including "microbat chambers", hollowed-out branch stubs for birds and box hollows for possums.
Industry leader, Steve Collom of Habitec in the Gold Coast region, has written a How-To, Carved Hollow Creation:A Conservation Arborist’s Field Guide.
Habitec started working in 2015 with the City of Gold Coast on a carved hollow project. The outfit created Greater Glider habitat on grazing properties and a rehabilitated mining site.
Habitec arborists also created "habitat enhancement" at a wetland park in Brisbane. They removed the canopy and poisoned the trunks of the mature Camphor laurel "weed trees". This prevented them from reproducing but preserved their structure to maintain riparian bank stability, erosion control, and habitat value.
Arborists then created multiple carved hollows within the reduced limbs to accommodate local wildlife species. To encourage local native species to the hollows in the tree structure, several Ficus watkinsiana (native Strangler figs) were also planted.
Next, arborists engineered a structure of old brances to provide resources such as hunting, wing-drying, and resting points for birds that live in the dams on site, including Great Cormorants, Yellow-billed Spoonbills, Azure Kingfishers, and Great Egrets.
"We believe that with proper planning and design, man-made infrastructure and expansion can provide opportunities to improve the environment, rather than damaging it.
- Steve Collom, Habitec
On this year's International Day of Forests, March 21, Shoalhaven Council activated the "Gordon Timbs 45 Degree Rule" which allows residents to remove trees within a 45 degree angle from dwellings without seeking approval from council and without having to use professional arborists to do the job.
