Features
Multi-sensor integration: The system combines sensors for sap flow, trunk circumference, soil water potential and temperature, soil tension, temperature, and moisture, CO2/O2 gas levels, along with a datalogger. It is designed for woody plants with diameters greater than 1 cm (sap flow) or 5 cm (dendrometer), with improved comparability across different trunk sizes.
Precision and resolution: Sensors offer resolutions such as better than 10 µV for sap flow, 0.05 µm for dendrometer (with compatible loggers), 0.1 kPa for water potential, 0.1 °C for temperature, and gas resolutions varying from 0.001 to 5 (depending on type). Accuracies include ±(10% of reading + 2 kPa) for water potential in -100 to -5 kPa range, ±35 kPa for tension over -100 to 1500 kPa, and ≤ ±3% FS for gases.
Durability and adaptability: Suitable for outdoor conditions from -25 to 70 °C and 0 to 100% relative humidity; not for underwater or snow-covered use. Materials include stainless steel and aluminum. Power options include solar panels, internal lithium batteries (18-24V), or external batteries (12-16V), with low consumption (e.g., 0.28 µWh per dendrometer measurement).
Expandability: Datalogger supports 8 single-ended analog inputs (expandable to 60), 4 pulse counters, multiple communication protocols (e.g., Modbus, RS485, SDI-12), and 32 MB internal storage for about 7.3 days of 1-second interval data.
Limitations: Gas sensor performance varies by type; tension accuracy is calibrated at 4-30 °C and 100% saturation; system focuses on fast-growing trees and is unsuitable for extreme environments like submersion.
Functions
Tree physiology monitoring: Measures sap flow continuously to assess water transport and transpiration; tracks trunk circumference changes for growth monitoring, with ranges varying by diameter (e.g., 107 mm at 10 cm diameter).
Soil condition assessment: Detects soil water potential (-8 to -100,000 kPa) and temperature (-40 to 60 °C) to evaluate drought stress; measures soil tension (-100 to 1500 kPa), temperature (-40 to +80 °C), and moisture (0-40% with ±5% accuracy) for saturation analysis.
Environmental gas monitoring: Tracks CO2/O2 concentrations (ranges 0-50,000 depending on model) in units like PPM or PPB, for assessing respiration or air quality around trees.
Data collection and management: Logs data via multiple channels, with support for voltage excitation and pulse inputs; enables storage and potential remote access (indicated by cloud integration in diagrams).
Overall purpose: Provides real-time data on tree health indicators like water stress, growth rate, and environmental factors to support informed management.
Target Users
Researchers: Plant physiologists and ecologists studying tree responses to environmental changes, such as climate or water management.
Forestry and agriculture professionals: Forest managers and orchard operators monitoring tree health for irrigation and maintenance decisions.
Environmental monitoring organizations: Government or conservation groups for urban greening, forest protection, or air quality assessments.
Tree care specialists: Arborists focusing on fast-growing species for health diagnostics.
Educational and commercial users: University labs or companies (e.g., in Hong Kong or similar regions) involved in data-driven tree management projects, supplied by Dianjiang Group Limited.
Technical Specifications：
SF 20 SF-G Sap Flow Sensor | |
Scope of application | For continuous measurement of the sap flow in wood plants |
Suitable for diameter | > 1 cm |
Number of sensor needles | 2 |
Sensor dimensions | Needle diameter: 1.5 mm; |
Needle length//length heated in mm, available versions: | |
18//10; 33//20; 43//20; 63//20 | |
Output signal | Analog, DC voltage -100µV to +800 µV |
Required logger channels | 1x differential, resolution better than 10 µV |
Circumference Dendrometer 4 Type DC4 | |
Scope of application | Fast-growing |
Suitable for diameter | > 5 cm |
Special features/limitations | Comparability for different trunk diameters improved. |
Measurement range | 50.8 mm linear ≙ |
circumference (diameter-dependent): | |
107 mm (at Ø 10 cm) | |
80 mm (at Ø 50 cm) | |
65 mm (at Ø 100 cm) | |
Resolution | Data logger dependent e.g.: |
CR300 series: 0.05 µm | |
Dendrometer logger DL18: 1 µm | |
Accuracy | Dendrometer dependent: max. ± 0.98% of the measured value (stable offset) |
Output signal | Analogue, 0V to Vex (excitation supply voltage) |
Temperature drift of the sensor | < 0.2 µm/°C in the whole measurement range |
Temperature coefficient of the stem embracing cable wire | < 1.4 ×10-6/K |
Linearity | < 0.5% |
Operational conditions | Normal outdoor conditions, -25 to 70 ° C, 0 to 100% relative air humidity; unsuitable underwater and below the snow cover |
Weight (sensor without cable) | 47 g |
Power supply | Vex (! stabilized !) 0.5 to 10 VDC, |
Power consumption max. 0.28 µWh per measurement | |
Material | Stainless steel and aluminiu |
40271-P TEROS 21 Gen 2 Water Potential and Temperature Sensor | |
Water Potential | Range: –8 to –100,000 kPa (1.90 to 6.00 pF) Resolution: 0.1 kPa Accuracy: ±(10% of reading + 2 kPa) from –100 to –5 kPa NOTE: TEROS 21 Gen 2 can read up to 0 kPa when on a wetting path. The air entry of the soil limits the performance of the sensor to 0 kPa on the drying curve. |
Temperature | Range: -40.00 – 60.00 °C Resolution: 0.10 °C Accuracy: ±1.00 °C |
Dielectric Measurement Frequency | 70 MHz |
FRT 15D Fullrange Tensiometer | |
Dimensions | Ø25 mm Length FRT 15D: 150 mm Length FRT 15D-SM: 157 mm |
Measuring tip | cylindrical |
Cable length | 5 m potted |
Tension measuring range | -100 … 1500 kPa Accuracy over the measuring range ±35 kPa, Temperature range during calibration 4 … 30 °C (at 100 % water saturation) |
Temperature measuring range | -40 ... +80 °C Accuracy ± 0.2 %, resolution 0.01 °C between 0... +40 °C |
Soil mositure measuring range | 0...40 % (0...100 % with limited accuracy) Accuracy ± 5 % / accuracy after specific calibration ±3 %, resolution 0.1 % |
DJ-6095-EX Datalogger | |
Operating Temperature | Temperature-20 to 70°C, can be extended to -40°C with external battery |
Analog Inputs | Supports 8 single-ended inputs, individually configurable, for voltage measurement; up to 60 single-ended inputs with expansion board |
Pulse Counting | 4 channels |
Pulse Excitation Frequency | 1 channels |
Voltage Excitation Terminals | 3 channels |
12V Switch Outputs | 18 channels |
SDI-12 | 8 channels |
RS485/RS232 | 4 channels |
Analog Voltage Resolution & Accuracy | 12-bit resolution, range 5000mV, input impedance 50kΩ, basic resolution 1.47mV, accuracy ±(0.1% reading + 2 LSB) at -20 to 40°C |
Expansion Board Accuracy | 19-bit resolution, optional ranges: 5mV / 50mV / 500mV / 5000mV, input impedance |
Power Supply | Using internal lithium battery: 18–24V, max charging current 2A Using external battery: 12–16V power supply |
Communication Protocols | Modbus, RS485, RS232, SDI-12 and others |
Internal Storage | 32MB, can store 64,384 records; 1 record per second can be stored for approximately 7.3 days |
