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Enabling better global research outcomes in soil, plant & environmental monitoring.

Large Stem Point Dendrometer

Point dendrometers for trees/stems > 7cm in diameter.
The ZN11-T-WP frame is made out of one piece of carbon fibre (CFK), combined with stainless steel elements (rods and nuts). An electronic displacement sensor (linear motion potentiometer) is mounted on this frame.

The ZN11-T-IP is a point dendrometer with a sealed potentiometer (IP54), designed to operate under very wet conditions.

Two-potentiometer versions of both the WP and IP dendrometers are available. (ZN12-T-2IP and ZN12-T-2WP)

  • T-shaped carbon fiber (CFK) frame combined with stainless steel elements
  • Application to stems, branches and roots >7 cm in diameter
  • Easy to mount

ZN-11-T-WP

  • Weather proof linear motion potentiometer, < 1μm resolution

ZN11-T-IP:

  • Low power consumption
  • Sealed linear motion potentiometer (IP54), < 1μm resolution

 

ZN11-T-WP

Size of carbon fibre frame: 190 x 92 x 8 mm
Weight (without thread rods): < 100g
Frame: T-shaped carbon fibre frame, 3 stainless steel thread rods, 6 screw nuts, 6 washers, and 3 cap nuts.
Displacement transducer: Weatherproof but not sealed potentiometer for measuring in a μm resolution. Hub of the moving rod is 2 cm.
Power supply: 5V DC.
Output: 0-5V DC, single ended measurement
Voltage Sensitivity: 1 mV = 4.0 μm
Temperature Sensitivity: < -0.28 μm°C-1

ZN11-T-IP

Size of carbon fibre frame: 190 x 92 x 8 mm
Weight (without thread rods): < 200g
Frame: T-shaped carbon fibre frame, 3 stainless steel thread rods, 6 screw nuts, 6 washers, and 3 cap nuts.
Displacement transducer: Sealed potentiometer (IP54) for measuring in a μm resolution. Hub of the moving rod is 2cm. Weather proof plug on sensor.
Power supply: 5V DC.
Output: 0-5V DC, single ended measurement.
Voltage Sensitivity: 1 mV = 4.0μm


ZN11-T-2WP

Size of carbon fibre frame: 190 x 92 x 8 mm
Weight (with thread rods): 180g
Frame: T-shaped carbon fibre frame, 3 stainless steel thread rods, 6 screw nuts, 6 washers, and 3 cap nuts.
Displacement transducer: Two weather-proof but not sealed potentiometer for measuring in a μm resolution. The hub of the moving rod is 2 cm.
Power supply: 5V DC.
Output: 0-5V DC, single ended measurement.
Voltage Sensitivity: 1 mV = 4.0 μm
Temperature Sensitivity: < -0.28 μm °C-1

ZN-11-T-2IP

Size of carbon fibre frame: 190 x 92 x 8 mm
Weight (without thread rods): < 200g
Frame: T-shaped carbon fibre frame, 3 stainless steel thread rods, 6 screw nuts, 6 washers, and 3 cap nuts.
Displacement transducer: Two sealed potentiometer (IP54) for measuring in a μm resolution. Hub of the moving rod is 2 cm. Weather-proof plug on sensor.
Power supply: 5V DC.
Output: 0-5V DC, single ended measurement.
Voltage Sensitivity: 1 mV = 4.0 μm

What is detected?

Diurnal stem radius fluctuations are mainly influenced by changes of the thickness of living tissues of the bark (mainly phloem cells). However, the xylem also undergoes size changes.
The radial size changes depend on water tensions inside the stem and have an influence on the hydration status of the bark. While water is withdrawn from the bark through transpiration during the daytime, at night the tissue is replenished. As a result of this cycle, the diameter decreases during the day and increases at night. Over a period of weeks and months, this diurnal rhythm is altered by growth. New layers of xylem cells irreversibly increase the radius, particularly during wet periods in the growing season. In winter, ice formations in the wood induce strong decreases of the stem radius.

Advantages in comparison to other products

• No disturbances by deformations of the dead outermost layer of the bark, induced by temperature and air-humidity (a general argument in favour of point dendrometers and against band dendrometers).
• Materials and electronic parts insensitive to temperature allow for more accurate measurements.
• The point of measurement is not influenced by the thread rods because it is neither in the vertical nor in the horizontal line of the anchor points.
• The application to different stem expositions allows a spatial resolution of stem radius fluctuations.
• Compatibility to most logging systems and easy to power with a stable 5V DC supply.
• Easy to mount.
• Minor disturbance of the tree stem.
• Weatherproof materials.
• Constructed, produced and tested by experts in tree physiology. Made in Switzerland.

Mounting principle

The electronic part of the dendrometer is mounted on a carbon fibre frame which is fixed to the stem by three stainless steel thread rods implanted into the inactive heartwood.
Two sensing rods are pressed slightly against the tree stem by a spring. The combination of weatherproof materials and a solid anchorage in the stem make it possible to precisely detect changes in the stem radius with a resolution of less than 1μm with an accurate logging system.