Biogeosciences www.biogeosciences.net 1726-4170 1726-4189 7 3 2010 10.5194/bg-7-907-2010 http://www.biogeosciences.net/7/907/2010/ http://www.biogeosciences.net/7/907/2010/bg-7-907-2010.html http://www.biogeosciences.net/7/907/2010/bg-7-907-2010.pdf 907 920 2010-03-08 A simple ecohydrological model captures essentials of seasonal leaf dynamics in semi-arid tropical grasslands P. Choler philippe.choler@ujf-grenoble.fr W. Sea P. Briggs M. Raupach R. Leuning CSIRO Marine and Atmospheric Research, P. O. Box 3023, Canberra, ACT, 2601, Australia Laboratoire d'Ecologie Alpine, UMR CNRS-UJF 5553, Université J. Fourier, Grenoble I, BP53, 38041 Grenoble, France Modelling leaf phenology in water-controlled ecosystems remains a difficult task because of high spatial and temporal variability in the interaction of plant growth and soil moisture. Here, we move beyond widely used linear models to examine the performance of low-dimensional, nonlinear ecohydrological models that couple the dynamics of plant cover and soil moisture. The study area encompasses 400 000 km² of semi-arid perennial tropical grasslands, dominated by C₄ grasses, in the Northern Territory and Queensland (Australia). We prepared 8-year time series (2001–2008) of climatic variables and estimates of fractional vegetation cover derived from MODIS Normalized Difference Vegetation Index (NDVI) for 400 randomly chosen sites, of which 25% were used for model calibration and 75% for model validation. <br><br> We found that the mean absolute error of linear and nonlinear models did not markedly differ. 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