Transpiration and water uptake have a direct effect on systems productivity and hence food security
Limited knowledge on water use of different tree species
Quantify productivity of different components in a system to help advise the right tree for the right place
Information on this is critical to inform policy (irrigation requirements, limits of species range AEZ)
What is Sap Flow?
Sap is simply a fluid transported in xylem cells (tracheids or vessel elements)
Movement of water in plants is based purely on principles of physics
A gradient in water potential is the physical mechanism that drives water movement in plants
Water potential is the ability of water to do work
Plants can have some influence over the passage of water by closing stomata during periods of moisture deficit
Water moves from a region of high potential to a region of low potential
Pure water has the largest potential and is given a value of 0 (SI unit for water potential is Pascal (Pa); so water at its reference point has a value of 0Pa)
The gradient of water potential becomes more negative from the reference point of 0Pa