• Other tools
• Bark

• Avoid twisting the tool when it is embedded in the tree. The chisel tip on the Bark Gauge in particular is easily fractured;


• Trees with rough and fissured barks should have their bark thickness measured on the ridges (this is where girth tapes will contact the bole). However, if calipers are used for measuring diameter, measure bark thickness at the points of caliper arm contact;


• Ensure the flange of the tool is flush with the bark before reading;


• Because bark thickness tends to vary from one side of a tree to another, take 3-4 readings around the stem and average.

Place the chisel end of the gauge against the bark and apply pressure to the handle until the chisel penetrates to the wood interface. The operator must "feel" the change in pressure as the chisel is pushed through the wood. Once the wood interface has been reached, push the flange against the bark and read the thickness from the scale.

Considerable experience is needed to ensure the chisel reaches the interface but is not pushed too far through the wood.

The probe is placed against the bark and the plunger struck lightly until the needle penetrates to the wood interface. The user must "feel" or listen for the change as the needle reaches the woody material. Read the depth from the scale while the needle is still embedded in the tree. Withdraw the instrument straight out from the bark to avoid bending or breaking the needle.

The measuring technique is virtually non-destructive and is simpler, more accurate and precise than most other commonly used techniques (Gill et al. 1982).