Human-caused damage: what the standards and agencies describe

This page describes what published sources say about one group of conditions in trees. It gives no verdict on any tree and is not an assessment. The sources come from the United States and the United Kingdom. The parent page, structural defects in trees, compares the conditions that have pages here.

How the ISA lists it

The ISA Trees Are Good leaflet closes its list of defects, lettered A to H, with item H, human-caused defects. It says wounds, weak or damaged limbs, root loss and decay may be the result of construction, grade changes, soil compaction, poor pruning or other misguided practices. The leaflet's checklist asks separately whether the area has been altered by construction, changes in soil level or the installation of lawns or pavement, and whether the tree has been topped or heavily pruned.

What the other sources name

Source	Human activities it names and what it links them to
US Forest Service brochure	Severing or paving over roots, raising or lowering the soil grade, and driving or parking vehicles over roots, listed among root problems. The brochure lists more than half the roots under the crown cut or crushed as a reason to act. It says poor architecture often arises after years of damage from storms, unusual growing conditions, improper pruning and topping.
University of Kentucky	Bad pruning, topping and improper planting named as causes of poor form. The leaflet describes trail and road construction as able to damage the root system, and names stripping bark off the main stem, flush cuts and left stubs among pruning errors.
Illinois Extension	Drought, soil compaction, herbicide damage, overfertilization and improper pruning that hinders wound closure, and early stressors such as planting too deep or forgotten stakes and guy wires.
University of Florida	A buried root system caused by deep planting or by a rise in soil grade during construction, which the publication says can lead to root dieback or an increased likelihood of root disease. Girdling roots linked to improper container nursery production.
National Tree Safety Group	Building works and utility trenching as examples of compaction, physical disturbance and severance of roots.

Topping and tipping

The Forest Service brochure defines topping as pruning large upright branches at right angles to the direction of growth, and tipping as cutting lateral branches the same way to reduce crown width. It calls both practices harmful, says the wound inevitably leads to decay in the remaining stub, and says branches that form later on a topped tree are weakly supported. The brochure also says weak branch unions form after a tree or branch is tipped or topped. The Kentucky leaflet describes topping as complete removal of the upper branches.

Damage that shows late

The National Tree Safety Group guidance says roots are often unintentionally damaged because they are hidden from view and, in extreme cases, the consequences for anchorage and tree health can be severe. It says such damage tends to be progressive, and that while the first visible indications may come soon after the damage, they often only appear some years or decades later as poor leaf condition and dieback in the crown. It adds that damage to small-diameter roots, unlike damage to small branches, can have serious consequences for the whole tree over time. The Forest Service brochure similarly says that because most defective roots are underground, aboveground symptoms such as soil mounding, twig dieback, dead wood in the crown and off-colour or smaller leaves may serve as the best warning.

Where to read on

Root conditions have their own page on root damage and root plate lifting. For the methods and the credentials, see tree risk assessment methods and consulting arborist credentials.