Research notes on tree assessment and tomography
Three studies compared the wind load estimated from dynamic measurements of root plate tilt in storms to the results of a standard pulling test software. For most trees, both estimates were in close agreement.
The presence of Heterobasidion spp. had a significant negative effect on the bending moment at primary and secondary failure of the tested trees irrespectively of soil type.
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.