Tree Pruning with a Purpose

Why sustainability is changing the way arborists work.

In Western Australia, summer has a way of making people notice trees.

When the heat settles in and shade becomes valuable, residents suddenly become aware of which trees look healthy — and which appear messy, stressed or inconvenient. The instinct is often immediate: prune it, tidy it, fix it.

But according to professional arborists, that instinct can be exactly the problem.

Pruning, they say, is not cosmetic maintenance. It is a long-term biological decision — one that can either protect a tree for decades or begin its decline. Poorly planned pruning removes live tissue a tree needs to photosynthesise, regulate temperature and manage water stress, especially in Western Australia’s sandy soils and intense summer heat.

What may look like improvement can actually compromise the tree’s health.

The modern arboricultural approach is simple: every cut must have a purpose.

What arborists mean by “sustainability”

In arboriculture, sustainability is often misunderstood as simply planting more trees. In reality, it starts with keeping the ones we already have.

Sustainability means not passing today’s losses onto future generations. Tree retention ensures future communities inherit healthy urban forests. Mature trees provide immediate environmental, social and economic benefits, including shade, cooling and wildlife habitat — benefits newly planted trees may take decades to replace.

For arborists, sustainability influences daily decisions: whether to prune, how much to remove, how to manage risk, and whether removal is truly necessary.

Michael Byrne

Not all pruning is good pruning

An experienced arborist does not start with a chainsaw — they start with a question:

Why are we pruning this tree?

Pruning objectives include:

• reducing risk

• improving structure

• guiding future growth

• providing clearance from buildings and roads

Without a defined objective, pruning often removes excessive live crown and places a tree under unnecessary stress.

Trees depend on their canopy. Remove too much and the tree loses its ability to regulate temperature and water — critical functions during a WA summer.

The sustainability shift on the job site

For tree climber and arborist Michael Byrne of CPD Tree Services, sustainability isn’t a policy document — it’s a daily decision-making process.

“We avoid unnecessary pruning and look for alternatives to removal,” he says.

Before any dismantling takes place, inspection comes first.

“We inspect potential sites for fauna — usually by climbing or drone. If a section can’t be inspected thoroughly, we lower it to the ground by rope to minimise injury to animals that might be inside.”

Habitat protection has become a significant part of modern arboriculture. Tree hollows — often viewed as defects — are actually critical wildlife homes.

“We try to leave as many hollows as possible after careful assessment,” Michael explains.

Even when a tree must be removed, the work doesn’t necessarily end with a stump and a chipper.

“Timber can be milled into value-added timber products. Firewood can be retained or delivered to suitable locations, and mulch can be reused or sold. Sometimes logs can be left as habitat if the land use allows.”

In Western Australia, arborists must also consider quarantine restrictions when moving timber due to PSHB (polyphagous shot-hole borer).

In other words, sustainability in arboriculture is less about not cutting and more about what happens after the cut.

Every cut has consequences

One of the most common causes of premature decline in urban trees is over-pruning.

Damaging practices include:

• topping

• excessive thinning

• stripping inner canopy growth

These practices:

• weaken trees

• increase failure risk

• shorten lifespan

Arborists instead use recognised methods:

• deadwood removal

• selective crown reduction

• structural pruning

It is a shift from aesthetics to biology.

Proper pruning is applied plant science. Decisions depend on species, health, growth stage, root disturbance and pest pressures. Some Western Australian natives, particularly mature specimens, do not tolerate heavy pruning.

For this reason, summer is often used for assessment rather than action — observing how a tree handles heat stress helps determine what work, if any, should occur later.

Trees as long-term infrastructure

Increasingly, arborists describe trees not as landscaping, but as infrastructure.

Michael Byrne

Large established trees cool suburbs, improve livability and support biodiversity. Removing them cannot be offset quickly by planting replacements; young trees cannot provide the same environmental services for many years.

Pruning with purpose protects both public safety and canopy longevity. It removes dead or weak branches, improves structure and airflow, and encourages healthy growth while preserving canopy function. Improved airflow also helps reduce pest and disease.

A changing profession

Arboriculture has evolved from reactive tree cutting to preventative management. The goal is no longer simply removing hazards, but managing trees so hazards never develop.

Sometimes sustainability means:

• leaving habitat

• reusing timber

• delaying work

• doing less work

• or choosing not to prune at all

In a challenging climate, every cut influences the future urban forest.

Pruning with intent — guided by science, safety and ecological awareness — ensures Western Australia’s canopy survives not just the next summer, but the next generation.