Tree lopping, topping and pruning

Why does everyone say lopping?

Because it's the everyday word. Plenty of people call anyone who works on trees a tree lopper, and "get it lopped" usually just means "make it smaller". There's nothing wrong with asking that way. What matters is where the cuts go.

Councils define it precisely. Whitehorse City Council in Melbourne calls lopping the removal of stems or limbs between nodes, the growing points, which usually makes the plant produce bushy growth. Wingecarribee Shire Council in NSW describes it as cutting between branch unions or at internodes, so the final cut leaves a stub. Topping is the same kind of cut made across the top of the tree.

Why do lopped trees regrow weakly?

Start with the wound. The branch collar, the slight swelling at the base of a limb, holds the tissue that grows over a cut, which is why pruning cuts go just outside it. Where the collar can't be seen, the branch bark ridge, a wrinkle in the bark on the trunk, is the guide. A lopping cut lands away from both, and Whitehorse says that makes it very difficult for the tree to seal the wound, potentially leaving it exposed to fungal infection.

Then the tree reacts. Buds around the stub push out a crowd of new shoots, and Whitehorse says that regrowth is often poorly attached to the main stem or trunk and can make the tree dangerous. Wingecarribee calls topping an antiquated practice that reduces a tree's strength and vigour and promotes premature decline.

Storms show it up. A report on Cyclone Yasi found that lopping before cyclones, a common practice, produces poorly formed regrowth that can make a tree more cyclone sensitive in the long term, and Townsville City Council's tree resilience sheet says poor practices such as lopping can weaken trees. The regrowth gets big and heavy on a weak join, and the cycle starts again.

What do the rules say about lopping?

Many tree rules treat lopping as damage, so lopping a protected tree can need approval just as removing it can. Brisbane's local law counts lopping or topping, as defined in AS 4373-2007, as interfering with vegetation. In Victoria, clause 52.37 needs a planning permit to remove, destroy or lop a canopy tree. South Australia lists topping and lopping among tree-damaging activities for regulated trees, and Northern Beaches Council in Sydney says it won't approve lopping or topping requests.

If the tree might be protected, ask the council before any cut, whatever the job is called. Tree removal permits has the rules by state.

Is cutting a tree back hard ever right?

Sometimes, on the right plant and on purpose. Gardening Australia says many small eucalypts have a lignotuber, a group of cells that lets them regenerate after damage or fire, so mallees can be coppiced, or cut back hard. Pollarding, a planned cut repeated from when a tree is young, is a pruning class in AS 4373. Neither is the same as topping a grown tree once to make it shorter.

An already lopped tree isn't a lost cause. Remedial pruning is a class in the Standard too: an arborist can thin out the weakest regrowth over time and build a better structure, or tell you honestly that replacing the tree makes more sense.