Alex Röll will focus on investigating the water use rates of different tree and palm species, ultimately comparing four different land-use systems in their water use characteristics: secondary tropical rain forest, jungle rubber, rubber plantations and oil palm plantations. Water use rates will be established by measuring sap flow with Granier-type sensors on 10 trees/palms in each plot. Individual water use will then be extrapolated to yield per-hectare transpiration rates of the respective land-use systems. Eddy covariance measurements in oil palm (A03 sub-project) will allow to differentiate between total transpiration and palm transpiration only. Together with biomass data raised by the B04 sub-project, water use efficiency rates of the different land-use systems will be derived. It is expected that they decrease in the order from forest over jungle rubber to rubber and finally oil palm. Alex will also be involved in the soil water uptake part of the A02 sub-project (Work Package 1), which will employ stable isotope analysis to investigate partitioning of water resources between species in the different land-use systems.