DR Radius Dendrometer
The DR series dendrometers are used for high-precision and continuous measurement of stem diameter changes. These devices are suitable for long-term use in outdoor conditions. Due to their extremely low power consumption, Ecomatik dendrometers are ideal for battery-powered solutions, e.g., in IoT applications. DR dendrometers are specially designed for tree trunks with medium to very large diameters (> 8 cm; or DC3, > 5 cm). DR dendrometers are mounted with one (DR3, DR3W) or two special screws (DR1, DR2, DR1W) anchored in the tree stem. The changes outside the trunk wood correspond to then radial growth and the daily variation of the trunk diameter, which is associated with tree water status. Screw-mounting ensures extreme stability for long-term measurements with limited maintenance options. DR dendrometers are available in five different versions:
1. DR1: with standard mounting frame and measuring range from of 11 mm for species with slow and average growth rates
2. DR1W: hermetically sealed to withstand extreme environmental conditions (under snow cover, underwater, elevated exposure to dust and corrosive agents), with standard mounting frame, measuring range of 11 mm for species with slow and average growth rates
3. DR2: with standard mounting frame and larger measuring range of 25 mm for fast-growing species
4. DR3: quick assembly frame with only 1 screw, suitable for treediameters >5 cm, measuring range of 11 mm for species with slow and average growth rates
5. DR3W: hermetically sealed to withstand extreme environmental conditions (under snow cover, underwater, elevated exposure to dust and corrosive agents), quick assembly frame with only 1 screw, for tree diameters >5 cm, measuring range of 11 mm for species with slow and average growth rates
Advantages of the DR series
- Suitable for large stem diameters (> 8cm)
- Minimal contact pressure on tree trunk surface
- Maximum stability against wind, snow, falling branches and fruit
- Ideal for long-term measurements with limited maintenance work
Specific to the DR2 model
- Extended measuring range; reduced maintenance effort (i.e. longer time interval between readjustment of the dendrometer frame) for fast-growing species
Specific to the DR3 & DR3W models
- Quick mounting frame with only 1 screw
- Can be used for trunk diameters >5 cm
Specific to the DR1W & DR3W models
- Hermetically sealed to withstand extreme environmental conditions: e.g. high humidity, underwater, below snow cover, near the ground surface, elevated exposure to dust or corrosive agents (e.g. coastal sands, volcanic ash), etc.
Limits of the DR rangeseries
- Drilling and installing the anchoring screws in the trunk may injure the tree (the damage can be minimized by using wound closure resin)
- Not suitable for small trunk diameters (<8 or < 5 cm)
Models
| Model name | Suitable for diameters | Measurement range |
|---|---|---|
| DR1 | > 8 cm | 11 mm |
| DR1W (gekapselt) | > 8 cm | 11 mm |
| DR2 | > 8 cm | 25 mm |
| DR3 (Schnellspannrahmen, 1 Schraube) | > 5 cm | 11 mm |
| DR3W (Schnellspannrahmen, 1 Schraube, gekapselt) | > 5 cm | 11 mm |
Technical data
Sensor model name | Radius dendrometer Type DR1 and DR1W (hermetically sealed) | Radius dendrometer | Radius dendrometer |
Scope of application | Slow/average growth rates | Fast-growing | slow/normal growth rates |
Suitable for diameter | > 8 cm | > 8 cm | > 5 cm |
Special features/limitations | 2x trunk screws for mounting | Extended measurement range for fast-growing species, 2x trunk screwsfor mounting | Only 1 trunk screw for mounting, less invasive; dual point installation possible: separate measurement of wood and bark (requires 2 DR3 sensors) |
Measurement range | 11 mm linear | 25,4 mm linear | 11 mm linear |
Resolution | Data logger dependent e.g.: | Data logger dependent e.g.: CR300 series: 0.03 μm Dendrometer logger DL 18: 0.5μm | Data logger dependent e.g: CR300 series: 0.01μm Dendrometer logger DL18: 0.2μm |
Accuracy | Dendrometer dependent: max. ± 4.5% of the measured value (stable offset) Data logger dependent e.g.: CR300 series: ± (0.04% of the measured value +0.3 μm) Dendrometer logger DL18: ± (0.1% of the measured value +0.45 μm) | Dendrometer dependent: max. ± 1.97% of the measured value (stable offset) Data logger dependent e.g: CR300 series: ± (0.04% of the measured value +0.6μm) Dendrometer logger DL18: ± (0.1% of the measured value +1 μm) | Dendrometer dependent: max. ± 4.5% of the measured value (stable offset) Data logger dependente.g:CR300 series: ± (0.04% of the measured value +0.3 μm) Dendrometer logger DL18: ± (0.1% of the measured value +0.45 μm) |
Output signal | Analogue, 0V to Vex (excitation supply voltage) | Analogue, 0V bis Vex (excitation supply voltage) | Analogue, 0V to Vex (excitation supply voltage) |
Temperature drift of the sensor | < 0.2 µm/°C in the whole measurement range | < 0.2 µm/°C in the whole measurement range | < 0.2 μm/°C in the whole measurement range |
Linearity | < 1% | < 0,7% | < 1% |
Operational conditions | All Models: normal outdoor field conditions, -25 to–70 °C, 0 to–100% relative air humidity; Hermetically Sealed Model DR1W: even under extreme environmental conditions (underwater, below snow cover, under exposure to strongly corrosive substances e.g. saltwater, ash, aggressive agricultural chemicals) | All Models: normal outdoor field conditions,-25 to 70 °C, 0 to 100% relative air humidity | All Models: normal outdoor field conditions, -25 to70 °C, 0 to 100% relative air humidity; Hermetically Sealed Model DR1W: even under extreme environmental conditions (underwater, below snow cover, under exposure to strongly corrosive substances e.g. saltwater, ash, aggressive agricultural chemicals) |
Weight (sensor without cable) | 13 g (DR1), 17 g (DR1W) | 33 g | 13 g |
Power supply | Vex (! stabilized!) 0.5 to 10 VDC, Power consumption max. 0.28 μWh per measurement | Vex (! stabilized!) 0.5 to 10 VDC, Power consumption max. 0.28 μWh per measurement | Vex (! stabilized!) 0.5 to 10 VDC, Power consumption max. 0.28 μWh per measurement |
Material | Stainless steel and aluminium | Stainless steel and aluminium | Stainless steel and aluminium |
Sensor cable length | 5 m, extendable on request to max. 100 m | 5 m, extendable on request to max. 100 m | 5 m, extendable on request to max. 100 m |