- Monitoring water use
in irrigated orchards.
- Scheduling irrigation
- Estimating water use
by trees in agroforestry.
- Monitoring species specific
water requirements of trees in watersheds.
- Note: Probes are reusable
unless they become cemented in the tree. This is dependent on
the tree species and "wound response".
Dimensions: Handle is 45mm long, 15mm dia.
Needles are 35mm long, 1.27mm dia.
Heater Resistance: 44 ohms.
Cable length: 2m standard (additional cable
Heater control interface:
will run up to 5 sensors. Click here to view a schematic diagram.
Guide for precise
spacing of needles in the tree.
The East 30 Sensors Sap
Flow Sensor consists of a pair of 35mm long stainless-steel needles
spaced 6mm apart. One needle contains an Evanohm heater and the
other contains three precision thermistor sensors evenly spaced
at 5mm, 17.5mm, and 30mm. The needles are inserted into holes
drilled in the trunk of a tree with the heater placed below (upstream
from) the thermocouples. A current is applied to the heater for
8 seconds, after which the temperature of the thermistors is
monitored. The flowing sap carries the heat pulse to the sensors.
The time taken for the pulse peak to reach the temperature sensors
is monitored. This time is directly related to the sap flow velocity.
The velocity is used, along with the sapwood area, to compute
the transpiration rate of the tree. The three thermistors provide
measurements of flow at three depths in the sapwood, from which
the velocity profile can be deduced.
Cohen, Y., M. Fuchs,
and G.C. Green 1981. Improvement of the heat pulse method for
determining sap flow in trees. Plant, Cell and Environment 4:391-397