Current issue: 54(2)
The physical methods currently available for measuring the internal decay of living trees is examined in this study. Although this is mainly a review, it can be concluded that some measurements shed more light on the problem. Examination of ultrasonic methods reveals that the coupling of ultrasonic energy from the transducer to the tree is not efficient. Both impulse and ultrasonic testing work best with decayed and hollow trees. The electrical resistance measurements of stumps gave resistance values for sound wood 300–400 kΩ, for decayed and discoloured wood about 12 kΩ and for cambium about 12 kΩ. The neutron activation gives good results, and in particular it reveals nicely the increasing concentration of potassium in decayed wood. The internal decay of living trees was not examined.
The PDF includes a summary in Finnish.