The measurement of sap flow in trees enables the calculation of daily and seasonal water use. Using this, irrigation requirements (urban parks, orchards & forests), tree health, the impact of climate change and calculation of carbon storage can all be derived through sap flow measurement. The SFM1x Sap Flow Meter quantifies tree water use in litres by measurement of sap flow.
The SFM1x is a self-contained instrument comprising sensor, signal processing, data storage and data transmission. The SFM1x is available with Internet of Things (IoT) connection, including LoRaWAN, CAT-M1 and NBIoT. The standard Bluetooth connectivity enables quick wireless device configuration, and data transfer in the field once installed.
IoT connectivity enables the SFM1x to transmit data directly to the cloud. This allows for further processing and analysis, visualisation and presentation, or integration into existing dashboards through an Application Programming Interface (API).
Using the established Heat Ratio Method, the SFM1x can measure high, low, and reverse flow rates in small woody stems and roots, as well as large trees. The SFM1x remains key for both researchers and industry to understand tree water use. Typically raw temperatures are stored and converted to sap velocity.
The SFM1x can optionally measure sap flow using the Compensated Heat Pulse Method (CHPM) and TMax methods. These methods can be used because the SFM1x stores the raw temperature data (recorded every 1 second) as JSON or CSV files. The JSON or CSV file result in ease of data access for the additional processing required outside of the instrument. The use of Senaps can allow this processing to be undertaken in the cloud in real time (this will incur additional charges).
The Sap Flow Meter (HRM30 and SFM1) has over 400 listings in Google Scholar, highlighting the wide acceptance by the research community. ICT International has an active library of over 75 leading publications that can be accessed here.
The SFM1x is an IoT enabled Sap Flow Meter is available in the following versions:
The use of these communication technologies enables the SFM1x to be deployed wherever there is cellular network coverage, or if there is no cellular coverage, a network using LoRaWAN and subsequent internet connection via 4G or satellite backhaul.
All SFM1x versions contain a Bluetooth module with an internal antenna for wireless data access and configuration of the unit. The SFM1B has a dedicated external Bluetooth antenna allowing long range connection.
The principles behind the SFM1x – the Heat Ratio Method – have been used to measure plant and tree water use in many applications. Example applications of the SFM1 and HRM30 can be found in:
Data from the SFM1x can be downloaded to be analysed in many statistical packages or sent via an API to a data visualisation (dashboard) of choice. Data can be downloaded directly from the SFM1x, or from the cloud when using the SFM1C or SFM1L.
When data is downloaded from the cloud, subsequent analysis can be performed using statistical packages. Advanced cloud integration solutions, which provide programming and modelling environments for further scientific analysis, machine learning and management decision making applications are available. Please consult ICT International for more details.
ICT International have integration solutions for the analysis of SFM1x data (CSV or JSON) using:
Advanced cloud integration programming and modelling environments include:
These provide the ability to undertake all analysis in a cloud environment, removing the need for static processing with downloaded data.
For the static processing of data, data from the SFM1x can be downloaded and analysed using the proven ICT International Dataview and Sap Flow Tool software. This is ideal for those who are upgrading their SFM1 to an SFM1x.
Providing real time information of the tree condition and water use, SFM1x data can be integrated into specific tools. These tools can be web based or dedicated apps using the API and JSON feeds. The results are suitable for arborists and the public when visiting an arboretum or tree canopy walk.
Visualisation solutions include:
Data from the SFM1x can also be downloaded and processed using ICT International Sap Flow Tool software. The software also allows for instant visualising of sap flow in 2- and 3- dimensions.
Using the Heat Ratio Method, the SFM1x can measure plant water use when the stem or root diameter is greater than 10mm, including:
Advanced users may choose to use JSON files containing the raw temperature data for subsequent processing and analysis.
The dynamic reference list maintained by ICT International can be found here.
|Output Options||Raw Temperatures: °C
Heat Pulse Velocity: cm hr-1
Sap Velocity: cm hr-1
Sap Flow: cm3 hr-1 (Litres hr-1)
|Range||-100 to +100 cm hr-1|
|Resolution||0.01 cm hr-1|
|Accuracy||0.5 cm hr-1|
|Measurement Duration||120 seconds|
|User Adjustable Heat Pulse||20 Joules (default) approx. Maximum 40 Joules. 20 Joule pulse is equivalent to a 2.5 second heat pulse duration, auto scaling.|
|User Adjustable Logging Interval||Minimum interval 3 minutes, recommended minimum 10 minutes.|
|Needle Diameter||1.3 mm|
|Needle Length||35 mm|
|Measurement Positions||2 per measurement needle|
|Measurement Spacings||7.5 mm and 22.5 mm from the needle tip|
|Dimensions L x W X D||170 x 80 x 35 mm|
|Temperature Range||-10 to 50°C|
INTERNAL POWER AND POWER MANAGEMENT
|Battery Specifications||3300mAh Lithium Ion, 4.20 Volts fully charged|
|Fully Charged Battery||4.20 Volts|
|Low Power Mode||3.60 Volts – Instrument ceases to take measurements. Resumes measurement at 3.70 Volts|
|Discharged Battery||2.90 Volts – Instrument automatically switches off at and below this voltage when no external power connected. Reconnects when battery returns to 3.1 Volts.|
|Battery Life||At the recommended configuration of 20 Joules at 10-minute intervals, upto 40 hours battery life has been observed without additional power supply. With a recommended power source connected, operation can be continuous.|
|Bus Power Source||60mA – 200mA Variable internal charge rate, maximum charge rate of 200mA active when the external voltage rises above 16 Volts DC|
|USB Power Source||100mA fixed charge rate|
|External Power Requirements|
|Bus Power||8-30 Volts DC, non-polarised, current draw is 100mA at 20 volts per SFM|
|USB Power||5 Volts DC|
|Communications||Short Range Bluetooth||Yes||Yes||Yes|
|Long Range Bluetooth||Yes||–||–|
|LoRaWAN||–||–||Yes (L1 = Global, L2 = China)|
|Data||Output File Types||BIN, CSV||CSV, JSON||BIN, CSV|
|Data Storage||MicroSD Card|
|Memory Capacity||Up to 16GB, 8GB MicroSD card included.|
|Manufacturer’s Product Codes||SFM1x-UB||SFM1x-C||SFM1x-L1 or -L2|
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