Two meanings, one word
Ring ten Australians and ask what tree lopping is, and ten will say it means getting a tree cut back. That is the everyday meaning, and there is nothing wrong with using it.
In arboriculture the word means something narrower and much less flattering: cutting through a limb or a stem at an arbitrary point, without reference to where the branches are or whether the tree can seal the wound. It is the practice sometimes called topping or hat-racking.
So when you ring and ask for lopping, what a decent operator hears is "this customer wants a tree cut back" - and what they should offer is proper pruning, not literal lopping.
What a lopping cut does
A tree does not heal wounds the way an animal does. It compartmentalises them, walling off the damage with chemical and physical barriers. That process only works efficiently when the cut is made in the right place: just outside the branch collar, back to a lateral branch big enough to take over.
Cut through the middle of a limb and you leave a stub. The stub has no growing tip to draw resources, so it dies back. Decay organisms enter through the dead face and move downward into the parent stem.
Meanwhile, the tree has lost a large part of its leaf area and responds by pushing epicormic shoots from dormant buds under the bark. Those shoots grow extremely fast - a metre or more a season - and they are attached only to the outer few millimetres of wood.
The three-to-seven-year problem
That combination is why lopping is a delayed hazard rather than an immediate one.
For the first couple of years a lopped tree looks like it has bounced back. Dense regrowth, more leaf, looks healthy. Underneath, the stub is decaying and the attachment point is weakening.
Somewhere between three and seven years later there is enough weight on those shoots and enough decay at the base for the whole mass to tear out. On the Sunshine Coast that happens in a summer storm, and it is heavier and higher than the limb that was there originally.
What to ask for instead
Four defined operations from Australian Standard AS 4373-2007 cover almost everything people want:
Crown reduction shortens branches back to a suitable lateral, reducing height and spread while keeping the tree's form. This is what you want if the tree is too big.
Crown thinning removes a proportion of secondary branches to let light and wind through without changing the outline.
Crown lifting removes the lowest branches for clearance over a driveway, path or roof.
Dead-wooding takes out dead and dying material, which is pure safety work.
The full list of pruning types explains when each applies, and pruning technique covers where the cut actually goes.
If reduction cannot get you there
Sometimes it cannot. A tree that is fundamentally too large for its position cannot be made small by any legitimate pruning operation, and pretending otherwise is how people end up with the three-to-seven-year problem.
In that case the honest answer is removal and replanting with something appropriate to the space. On the Sunshine Coast, check the local rules before assuming you can, then ring (07) 5408 6029.
Frequently asked questions
What is tree lopping?
In arboriculture, lopping means cutting through branches or the trunk at arbitrary points, without regard to branch structure or the tree's ability to seal the wound. In everyday Australian usage it simply means having a tree cut back. The everyday meaning is harmless; the technical practice it describes is not.
Why is lopping bad for a tree?
A lopping cut leaves a stub that cannot seal. Decay enters through it and moves down into the stem. The tree responds with a dense flush of epicormic shoots attached only to the outer few millimetres of wood. Those shoots grow fast, get heavy, and tear out of the decaying stub - usually three to seven years later, usually in a storm.
What should I ask for instead?
Crown reduction, crown thinning, crown lifting or dead-wooding, depending on what you actually want. All four are defined in Australian Standard AS 4373-2007 and all four cut back to a living lateral branch that can take over as the new leader, so the tree seals the wound and keeps its structure.
Is it ever appropriate to lop a tree?
Very rarely, and usually as an emergency measure - dropping the top out of a storm-damaged tree to make it safe before it is removed properly. As a maintenance practice on a tree you intend to keep, it has no defensible use.