Thermal dissipation probes (the Granier method) are routinely used in forest ecology and water balance studies to estimate whole-tree transpiration. This method utilizes an empirically derived equation to measure sap flux density, which has been reported as independent of wood characteristics. However, errors in calculated sap flux density may occur when large gradients in sap velocity occur al...

Recent studies have shown that stomata respond to changes in hydraulic conductance of the flow path from soil to leaf. In open-grown tall trees, branches of different heights may have different hydraulic conductances because of differences in path length and growth. We determined if leaf gas exchange, branch sap flux, leaf specific hydraulic conductance, foliar carbon isotope composition (delta...

This work is the first attempt at using Granier sap sensors on Populus nigra, Populus x euramericana cv I45/51 and Salix alba for the monitoring of sap flows in an active floodplain over two consecutive years. The main characteristic of these diffuse porous trees is their capacity to use several tree rings for xylem sap transfer. Results showed that the sap flux densities remained homogeneous o...

1 Linking sap flow in tree boles to plant transpiration continues to be a fundamental and 2 practical research problem in physiological ecology and forest hydrology. Many models have 3 been proposed to describe water movement within trees with varying degrees of success. The 4 prevailing resistance-capacitance (RC) circuit models have the advantage of being easy to 5 implement. However, RC mode...

We used 20-mm-long, Granier-type sensors to quantify the effects of tree size, azimuth and radial position in the xylem on the spatial variability in xylem sap flux in 64-year-old trees of Taxodium distichum L. Rich. growing in a flooded forest. This information was used to scale flux to the stand level to investigate variations in half-hourly and daily (24-hour) sums of sap flow, transpiration...