UKTC Archive

Re: Diameter callipers

Subject: Re: Diameter callipers
From: Jonathan Astill
Date: Aug 14 2019 08:22:47
Where accuracy is not essential I have a ruler painted on the long edge of
my A3 weather-writer (43cm) with tippex. 0 cm held up against tangent of
left side of tree at desired height, note fissure / ivy stem /slug /
woodlouse at 40cm / 80cm etc. and reposition weather-writer to tangent of
opposite side. Repeat exercise at 90 degree bearing for asymmetrical, lumpy
and oval stems and take mean average of two readings. When double checked
with tape it’s about 95% accurate for trees under 1 metre diameter. Just
make sure that your survey key / methodology states that the diameter is
approximate. Takes seconds when you’re used to it. Simple, cheap, quick and
more than adequate for the task at hand.

Use tapes or callipers for 5837, veteran, ancient or champion trees as
someone will be quick to point out your error.

On the subject of rapid and cost-effective tree measurements, I bought a
digital measure last year (£30) for measuring canopy spreads and distances
of trees from other structures (adding half the stem diameter). Accurate to
10mm over 40m (checked). The red laser point can be difficult to see beyond
15 meters in bright light but usually fine under shade of tree crown or
typical British weather. Always keep ground tapes / loggers tape in the car
to fall back on when needed. Still using a Suunto for tree height (where
needed). I love a gadget as much as the next person but cant justify the
colossal expense for the Haglofs and others.


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