SF-G / SF-L Granier Sap Flow Sensors

Sap flow sensors are used to continuously measure water uptake in woody plants. The SF-G model corresponds to the classic, two-needle model developed in 1985 by André Granier.

Our four-needle SF-L sensor is an updated Granier sensor. The patented improvements correct the naturally occurring and time-varying vertical temperature gradients in the sapwood. Without correction (i.e. the original Granier sensor, SF-G) and despite isolation, these natural temperature gradients can lead to a temporary over- or underestimation of the measured sap flow values of up to 50% in extreme cases (cf. Do, F., & Rocheteau, A., 2002). Additional temperature measurements with the SF-L sensor enable a correction of the measured sap flow values, which prevents errors caused by the natural vertical stem temperature gradients. This results in a significantly higher accuracy and a stabler zero-point (ΔTmax) of the xylem (sap) flow.

A very helpful option to exactly determine this zero-point would be to use a dendrometer in order to continuously measure the water saturation level of the tree body. This additional measurement allows for a precise determination of zero sap flow conditions: sap flow = 0 if the relative humidity in the crown at 100% and the tree body is 100% saturated with water (no change in diameter according to the dendrometer data). The improved SF-L sensor combined with dendrometer-aided precise determination of zero flow conditions, makes a running nocturnal zeroing of the sap flow (according to Granier) unnecessary. This process enables the recording of a nocturnal xylem flow.

Advantages

Specific to the SF-G model

  • Suitable for tree diameters > 1 cm

Specific to the SF-L model

  • Greater measurement accuracy
  • Correct determination of the xylem flow zero point when supplemented with dendrometer measurements
  • Allows measurement of nocturnal xylem flow
  • Additional information about tree growth provided by installing supplementary dendrometers

Limits

Specific to the SF-G model

  • The measured values are superimposed by naturally occurring vertical temperature fluctuations in the trunk (up to +/- 2.5 ° C). This leads to measurement errors greater than 50% and may impact the reliability of measurement results.
  • Nocturnal sap flow cannot be measured. Because of the temperature overlaps, nocturnal measurement values have to be set to zero.

Specific to the SF-L model

  • Not suitable for trees with a diameter < 8 cm
  • 3 logger channels are required per sensor

Models

Model name

Suitable for diameters

Sensor needle // heater element length in mm


SF-G
> 1 cm18 // 10

> 2 cm
33 // 20
43 // 20
63 // 20
SF-L> 8 cm18 // 10
33 // 20
43 // 20
63 // 20

Manual

Technical data sheets

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Accessories & Compatible Products

Compatible sensors and peripherals:

Our open and modular system is highly flexible and easy to expand in stages. In this case, virtually all sensors or other peripheral devices (such as a webcam) can be integrated.

Ecomatik sensors include:

  • Dendrometers
  • Sap flow sensors
  • Temperature sensors
  • Leaf sensors
  • Humidity and air temperature sensor
  • Soil moisture sensors
  • And many more…

Contact

You need a quotation, have questions about a product, or need extensive technical advice in the context of your project planning. Starting with an initial determination of your needs, through the detailed planning of the required measurement equipment and data transmission technology, up to professional implementation on site, we are at your disposal at any time with advice and action.

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General information on order processing

Thank you for your interest in our products and services! Here you will find important information about the ordering process:

To our international customers: Please note, we ship worldwide! If we do not currently have a listed distributor in your country (a list can be found here) , please feel free to contact us directly.

Assessment of your needs

With your consideration and input, we determine which of our products best meet your needs. We are also happy to design fully-integrated measuring stations (plant, climate, soil sensors), including an independent power supply and mobile data transmission, depending on your requirements.

Are you already familiar with our products and know exactly what you need?

Perfect, then just write us an email! In your order, please state the diameter of your measuring objects in addition to the required cable lengths.

Do you require our assistance before placing an order?

We’re happy to help! So that we can provide you with accurate and helpful advice, please first fill out the above online form with your request and send it our way. We will then immediately review your details and contact you.

Like so many things, everything started with an idea ...

In the case of the plant scientist and founder of ECOMATIK, Dr. Liu, it was the idea that modern measurement technology should enable crucial plant physiological parameters to be measured directly, precisely and with high temporal resolution on the plant itself. It was obvious to him that there is an information potential of immense value in the detailed understanding of immediate reactions of plants to their environment...