The reduced stability also suggests that bark-stripped trees can act as the weak spots decreasing the collective stability of stands in the long term, thus increasing the susceptibility to storms.

Partially uprooted trees may re-establish stability over time, but some will not and may fail.

A wind-tilt-curve can be used to assess the anchorage of urban trees.

Almost all branches in urban trees exceed the slenderness criterion of VTA. A criterion, which identifies almost all branches in every tree as dangerous is not useful for hazard tree assessment.

Tilt of > 0,2° at wind speed of 50-60 km/h leads to critical tilt values at gale winds.

Often, the stem surface of mature London plane trees is bumpy. Our results, derived from a thorough characterization of the stem surface, tomography, and thermography, show that this does not indicate inner defects.

Our data do not support the use of a threshold value of slenderness in tree risk assessment.

In spruce, the effect of slenderness on maximum bending moments is negligible.