Articles tagged “Forest trees”

In addition to the signal’s transit time, the new impactor acoustic tomograph records other important characteristics that improve diagnosis.

To produce accurate and repeatable tomograms of trees with complex shapes, it is essential to measure the sensor positions precisely. Accuracy of the position of sensors affects estimated stress wave velocity, the shape of the tomogram, the size of the defect, and the estimated loss in load carrying capacity.

Provided that sensor positions are accurately recorded and documented, tomograms can reliably be repeated by different assessors over periods of years. Assessments based on complex calculations like loss of section modulus should be treated with caution, because they accumulate and amplify all sources of variation.

Static pulling tests were performed to compare the mechanical stability of Eurasian aspen (Populus tremula L.) and silver birch (Betula pendula Roth.) in both urban and peri-urban forests. The loading resistance of the species differed, with birch being more stable than aspen. Additionally, the mechanical stability of birch did not differ between trees growing in urban and peri-urban forests, suggesting static pulling tests are a suitable method for comparing trees from completely different growing conditions.

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.