This is a sap flow station that is used along with other instruments to collect data on urban biogenic CO2 fluxes for the European project UrbaNature.
Sap flow sensors measure the water transported from the roots to the leaf crown of a tree. For this purpose, three small needles with a diameter of approximately 1 mm and the length of 3 cm are inserted into the tree trunk. The three needles derive the quantity of water transported using thermal conductivity. The central needle is a heater and the other two measure the difference in temperature in downstream and upstream positions.
This is a method largely used in research, measuring the water transport allowing one to understand the tree's behavior and its response to its environment.
The white box contains a battery to make the sensor work and a logger that stores and transmit the sensor information.
The sensors are installed professionally and they don't affect the tree's normal functionality.
For questions or further information, please contact:
Prof. Dr. Nina Buchmann : nina.buchmann@clutterusys.ethz.ch , +41 44 632 3959
Sophie Emberger : sophie.emberger@clutterusys.ethz.ch , +41 44 632 85 13