The main study objectives were: (1) to determine the spatial
distribution of sap velocities in Qinghai spruce stems, in
order to describe and analyze its radial profile; (2) to detect
the probe inserted depth, in order to make accurate estimate
of whole-tree water use; (3) to characterize the effects of climatic
factors (e.g., vapor pressure deficits, temperature, radiation,
wind, precipitation) and soil moisture on Qinghai spruce sap
flow.