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Evaporation from a Themeda Grassland. II. Resistance Model of Plant Evaporation
F. X. Dunin, A. R. Aston and W. Reyenga
Journal of Applied Ecology
Vol. 15, No. 3 (Dec., 1978), pp. 847-858
Published by: British Ecological Society
Stable URL: http://www.jstor.org/stable/2402780
Page Count: 12
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(1) A model, incorporating resistances to water vapour transport, was developed to account for controls on grassland evaporation in the Southern Tablelands region of New South Wales, Australia. A relationship describing aerodynamic resistance was derived from short-term data on wind profiles. A second relationship, involving surface resistance as a function of solar radiation and soil moisture content, was obtained using short-term measurements from a lysimeter and of associated meteorological variables. (2) Model simulations corresponded well with evaporation from a lysimeter over a 5-year period. (3) Sensitivity analyses of parameters in the model indicated that aerodynamic resistance was not critical. Seasonal adjustments in the rainfall intercepted by the canopy improved estimates of weekly evaporation. (4) The role of the resistance model in land management is discussed. An example is given of the way in which the model may be used to predict changes in runoff resulting from the conversion of Themeda grassland to improved pasture.
Journal of Applied Ecology © 1978 British Ecological Society