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Enabling better global research outcomes in soil, plant & environmental monitoring.

Monitoring Tree Water Use in the Field

Why tree water use/ transpiration?

  • Water is a limiting factor to crop/tree growth
  • 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