ImRa
profiles, diagnostics of living trees
The
ImRa-system can be used to detect the internal differences in humidity and density
conditions of a living tree. The radar measurement does not harm the tree at
all. It is an easy method to control the condition of a tree. The 1 GHz antenna
is the most suitable for tree diagnostics.
In living
trees there exists always humidity and density variations, which generate radar
reflections. If a tree is healthy and normal, then the reflections remain about
constant when the antenna is moved along the trunk. The radar profile is
regular and the reflections can be seen as continuous straight lines. Rot and
other damage, in the tree, generate variations to the radar profile. The
reflections are stronger or disappear, when measured from one point to another,
along the trunk. The radar profile shows broken or curly echo lines or there
can exist very clear extra lines.
Two
profiles of the same birch (Betula pubescens). The diameter near ground
was about 50cm. The measurements are made along the trunk from the base
upwards, in these profiles the antenna has been moved along the left side of
the profiles.
The
profile on the left is measured in early spring (in Finland), when the tree was
still resting. The profile on the right is measured later, at the end of April,
when the tree was preparing for leaves and growing season. The flow of the
organic fluids can be seen as intensive reflections inside the bark (the right
profile, diameter scale 5.15 cm).
The
profiles below show the measurements of two spruces. The measurements are made
along the stem downwards to the base, in these profiles the antenna has been
moved along the right side of the profiles.
The
profile on the left shows a rotten (Heterobasidion annosum) tree. The
rotten heart of the spruce can be seen in the profile in diameter scale between
10...20 cm, where the rotten part gives strong echoes.
The
profile on the right shows a healthy spruce. The bending of the echo-lines is
caused by thickness variations due to the large roots. Both spruces are
Scandinavian species, Picea abius.
