Instruction manual

2
Summary
Heat-pulse techniques can be used to measure sap flow in plant stems with minimal
disruption to the sap stream (Swanson and Whitfield, 1981; Cohen et al., 1981; Green and
Clothier, 1988). The measurements are reliable, use inexpensive technology, provide a
good time resolution of sap flow, and they are well-suited to automatic data collection
and storage. Sequential or simultaneous measurements on numerous trees are possible,
permitting the estimation of transpiration from whole stands of trees.
The HPV system described here is based on the ‘compensation’ Heat-Pulse method
(Swanson and Whitfield, 1981) and comprises a set of probes and associated electronics
connected to a data logger (model CR10, Campbell Scientific Inc., Utah, USA). Included
with the system is a set of computer programs to CAPTURE and ANALYZE the heat-
pulse measurements, which are recorded automatically by the data logger. The purpose of
this document is to describe how to successfully install and operate the HPV system.