| dc.description.abstract | The Shigometer was evaluated as an instrument for detecting
red heart of paper birch. The Shigometer accurately detected the
presence of red heart at a 50% decrease from the maximum reading
rule but sometimes failed to precisely define its outer limits.
Although it did not always correctly detect the presence or precise
location of discoloured wood, it was able to correctly detect the
presence of discoloured wood within a few centimetres in
approximately 85% of attempts. There was a general increase in ion
concentrations in the red heart as compared to the clear wood. The
ions appear to accumulate in vessels along the clear wood to
discoloured wood transition zone, in the ray parenchyma in the
transition zone and in the discoloured wood. Following wounding
there was an increase in soluble and insoluble potassium. The
Shigometer readings were found to be correlated with mobile ion
concentrations of potassium and magnesium. Because few
microorganisms were found in association with the red heart, it is
felt that the initial accumulation of ions may be a wound response by
the tree. | |
