04/09/2026
Thoughts of a Consulting Arborist
A slightly long-winded post from a consulting arborist wandering around looking at trees and probably thinking about them too much.
I’ve been thinking lately about where we’re heading with our urban trees, development and the increasing difficulty of balancing the built environment with the natural environment.
I certainly don’t have all the answers. I’m not sure anyone does.
So take it or leave it. These are simply some thoughts from someone who spends a fair amount of time walking around developments, construction sites, streets, commercial sites and backyards looking at trees.
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We all hear about the importance of urban canopy.
And there are good reasons for that.
Trees cool our streets and homes, reduce the urban heat-island effect, intercept stormwater, provide habitat and green corridors, improve amenity and contribute enormously to the character and value of the places in which we live.
Drive through many established suburbs and a large part of what makes them desirable is obvious.
Mature trees and established landscapes.
Yet there is an interesting contradiction.
We collectively value leafy suburbs, but individually we don’t always want the tree.
Trees drop leaves and branches. They require maintenance. They shade things. Their roots grow where we don’t necessarily want them. They occupy valuable space. They can constrain development and there can be genuine or perceived concerns about risk.
In Australia, we also have the very real issue of bushfire. Asset Protection Zones, vegetation management and the protection of people and property all need to be considered.
These aren’t imaginary problems.
Human safety obviously matters.
At the same time, our population continues to grow.
We need houses, apartments, roads, schools, utilities and infrastructure. Blocks become smaller, building footprints become larger and more things need to occupy the same finite amount of land.
People buying increasingly expensive property understandably want to make reasonable use of it.
So I don’t think the conversation can simply be reduced to development versus trees.
We need both.
The difficult part is finding the balance.
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One thing that is often misunderstood when arborists assess development around trees is that a tree doesn’t finish at ground level.
What we see above ground is only part of the organism we’re trying to retain.
Large trees require substantial functioning environments below ground.
Roots need soil volume, oxygen, moisture, nutrients and appropriate soil structure.
Then we ask that same piece of ground to accommodate foundations, basements, pools, driveways, retaining walls, stormwater, sewer, electrical infrastructure, telecommunications, roads and pavement.
Eventually everything starts competing for the same space.
Sometimes we technically “retain” a tree while progressively removing the conditions that allowed it to become a large tree in the first place.
The trunk remains.
The canopy remains.
The plans say TREE TO BE RETAINED.
But below ground, its functional environment may have changed considerably.
Trees are remarkably adaptable living organisms. They can tolerate disturbance, respond to injury and adjust to changing environments far better than they’re sometimes given credit for.
But they’re not magic.
There are limits.
And the consequences aren’t necessarily immediate.
Root loss, soil compaction, changes in grade, altered drainage, changes in soil chemistry and loss of usable soil volume can influence tree health and structural stability over many years.
Sometimes the tree that becomes a problem ten years after development wasn’t necessarily an inherently dangerous tree.
Perhaps we should also be asking:
What happened to the environment around that tree during the previous ten years?
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Then there is the practical reality of actually building around retained trees.
It’s relatively easy to draw a Tree Protection Zone on a plan.
It’s considerably harder to construct within one.
Modern construction is built around efficiency.
Excavators and other hydraulic machinery can move enormous quantities of material quickly. Trenches can be excavated and services installed in a fraction of the time previously required.
Then the arborist turns up and asks everyone to slow down.
Excavate carefully.
Expose roots.
Don’t tear through that one.
Move the footing.
Bridge across this area.
Hand excavate here.
Use non-destructive excavation.
Bring in a hydro-vacuum unit.
Have an arborist present while the excavation occurs.
None of that makes construction easier.
It takes time, labour and money.
And I understand why that can be frustrating.
We’re asking people whose job is to build something efficiently to deliberately work more slowly and carefully around a living system that they often can’t even see until the ground is opened.
Sometimes that additional effort is absolutely justified to retain a significant mature tree.
But ideally, good planning provides enough space that construction and tree protection aren’t constantly fighting over the same metre of ground.
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And then we come to replacement planting.
Development approvals commonly require new trees when established trees are removed.
That’s important.
But sometimes I wonder whether replacement planting becomes a little too much of a box-ticking exercise.
Remove one tree.
Plant one tree.
Requirement satisfied.
On paper, perhaps.
But a newly planted tree doesn’t immediately replace the canopy, habitat, cooling, amenity and environmental functions of a mature tree that may have taken 50, 80 or 100 years to develop.
What we’re actually planting is the potential for future canopy.
Whether that potential is ever realised depends heavily on what we provide that tree.
We can specify an appropriate species and good-quality planting stock, but if it’s allocated a tiny opening surrounded by pavement, services, compacted subgrade and concrete, we’ve already placed a fairly substantial limitation on what that tree can become.
Modern urban tree engineering is certainly improving.
Soil cells, tree vaults, structural soils, suspended pavements, passive irrigation and other systems can provide considerably better growing environments beneath hard landscapes.
That’s fantastic progress.
In heavily urbanised environments, these systems can make the difference between meaningful future canopy and another struggling tree sitting in a small hole in the pavement.
But even sophisticated engineering doesn’t make the biological requirements of trees disappear.
Where we have the opportunity, large volumes of healthy, connected, uncompacted soil remain incredibly valuable.
Perhaps instead of simply asking:
“How many replacement trees did we plant?”
We should also ask:
“How many of those trees have genuinely been given the opportunity to become large, healthy, mature trees?”
Because planting numbers and future canopy aren’t necessarily the same thing.
A mature tree can be removed in a day.
Replacing the functions of that tree may take decades.
Sometimes longer than our own working lives.
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My own perspective on all of this has changed considerably.
I started as a climbing arborist.
I loved climbing trees.
I enjoyed the technical challenge of pruning and dismantling them. There is enormous skill involved in professional tree work, and good climbing arborists and tree crews remain an essential part of our industry.
But if I’m being truthful, earlier in my career my appreciation of a tree was often more about the challenge of climbing it and safely dismantling it than understanding its broader value within the landscape.
The more I’ve learnt about trees, the more that perspective has changed.
You start looking beyond the individual trunk and canopy.
You learn more about physiology, soils, decay, biomechanics, ecology, habitat, hydrology, development impacts and how individual trees collectively form much larger environmental systems.
And you realise that working on a tree and deciding the long-term future of a tree are two very different responsibilities.
Sometimes removal is absolutely the appropriate outcome.
Sometimes bushfire management, unacceptable risk, infrastructure requirements or development constraints mean a tree simply cannot reasonably remain.
Sometimes retaining a poor or unsuitable tree at enormous expense doesn’t make sense when removal and good replacement planning could provide a better long-term outcome.
And sometimes a healthy mature tree should be significant enough to influence the design around it.
Good arboriculture shouldn’t automatically mean save every tree.
But neither should our starting point always be:
How do we get this tree out of the way?
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Humans naturally assess our environment from our own perspective.
Does that tree threaten my house?
Does it interfere with my development?
Does it drop leaves into my pool?
Does it block my view?
Can I fit another dwelling here?
Can the driveway go there?
They’re understandable questions.
Everyone is entitled to place different values on trees, and I certainly haven’t always viewed them the way I do now.
But perhaps the more we understand about the natural environment, the easier it becomes to recognise that we aren’t the only things trying to live in it.
Trees, soils, fungi, insects, birds and countless other organisms form incredibly complex systems around us.
Our cities and houses have simply been constructed within those systems.
Finding the balance between human needs, development, safety and the natural environment is difficult.
And as our population grows and our cities become denser, I suspect it’s only going to become more difficult.
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One tree disappearing from a backyard doesn’t change a suburb.
Neither does the next one.
But repeat that process thousands of times across private properties, subdivisions, bushland developments, road upgrades and infrastructure projects and eventually the landscape changes.
And once mature canopy is gone, we can’t simply order another one and install it next Tuesday.
We can plant the next generation.
We can improve our engineering.
We can design better developments.
We can protect appropriate existing trees.
We can create better soil environments.
But ultimately, trees still need something increasingly valuable in our growing cities:
Space.
Space above ground.
Space below ground.
And perhaps most importantly, a recognised space within the way we think about and plan our built environment.
I don’t think there is a perfect answer.
It’s simply something worth thinking about.
Anyway, that’s enough pondering for one morning.
Just some thoughts from a consulting arborist wandering around looking at trees. 🌳
Take them or leave them.
And if you want to talk about trees, disagree with any of it, or have another perspective, I’m always happy to have the discussion.
Trees are what we do.
Chad Shakeshaft
Arbor Central
