An analysis of Granier sap flow method, its sensitivity to heat storage and a new approach to improve its time dynamics

摘要: Abstract Granier sap flow method is a simple and easily applicable to monitor in trees field conditions, thus wide use. However, it has been suggested that the slow capture transient changes actual flux density due heat storage release within stem. We show here how this may lead biases estimation of dynamics especially at low rates when thermal diffusivity low. also demonstrate traditional could be modified improve temporal precision measurement. In new system, temperature difference between heated reference needle kept constant by varying heating power calculated from consumption. This leads reduced content These modifications make more robust terms stability supply reduce consumption during conditions. The time “steady method” are simulated with previously published numerical model xylem balance tested laboratory experiment cut pieces used relation parameter K , instantaneous sensor maximum temperature, not for either or sensor, but dependent on range sapflow examined value diffusivity. Continuous measurements sapwood along temperature/power help accuracy measurements.