Dendrometers explained

A dendrometer is a sensor used to measure growth of plants. Generally, the measurement is of the tree circumference or diameter but there are also dendrometers available for measuring fruit diameter. High resolution dendrometers are used to monitor the diurnal swelling and shrinkage of stems. During the day stems “shrink” as stomata open and the tree transpires. At night transpiration ceases and the stem “swells” as the trunk refills with moisture.

Two different instruments from ICT International will be considered here – the DBS60 Band Dendrometer and the DBS40 Pivot Stem Dendrometer. Both are available from HydroTerra.

DBS60 Band Dendrometer

The DBS60 Band Dendrometer uses a stainless-steel band surrounding the tree to provide high resolution measurements (1 µm) of trunk circumference. The stainless-steel band has a very low linear thermal coefficient so daily or seasonal temperature variations have no measurable impact. The sensor has an SDI-12 output that can be connected to external loggers and telemetry systems for recording and transmission of real time data. Find out more.

DPS40 Pivot Stem Dendrometer

The DPS40 Pivot Stem Dendrometer is a pivot-based sensor for measurement of small stems, from 5mm to 40mm. The DPS40 uses a spring-based lever clamp to fasten to the tree and to provide a measurement of tree diameter in millimetres. This is a high-resolution sensor that is designed to have a minimum impact from temperature and axial forces. The sensor has an SDI-12 output that can be connected to external loggers and telemetry systems for recording and transmission of real time data. Find out more.