The effect of rainfall amount and timing on annual transpiration in a grazed savanna grassland

Abstract. The role of precipitation (P) variability with respect to evapotranspiration (ET) and its two components, transpiration (T) evaporation (E), from savannas continues draw significant research interest given relevance a number ecohydrological applications. Our study reports on 6 years measured ET estimated T E grazed savanna grassland at Welgegund, South Africa. Annual P varied significantly amount (508 672 mm yr?1), dry characterized by infrequent early-season rainfall. was determined using annual water-use efficiency gross primary production estimates derived eddy-covariance measurements latent heat flux net ecosystem CO2 exchange rates. computed for the 4 wet frequent early wet-season rainfall nearly constant, 326±19 yr?1 (T/ET=0.51), but lower more variable between 2 (255 154 yr?1, respectively). T/ET were linearly related storm frequency. constancy during is explained moderate water stress C4 grasses as well trees' ability use deeper layers. During extreme drought, respond availability dieback–regrowth pattern, reducing leaf area and, thus, increasing proportion contributed trees. works suggest that distribution explains interannual in T, which should be considered when managing grazing fodder these grasslands.