caa a22 4500 44538428X CHVBK 20180317143027.0 cr unu---uuuuu 170323e20110301xx s 000 0 eng 10.1007/s10021-010-9403-9 doi (NATIONALLICENCE)springer-10.1007/s10021-010-9403-9 A Benchmark Test for Ecohydrological Models of Interannual Variability of NDVI in Semi-arid Tropical Grasslands [Elektronische Daten] [Philippe Choler, William Sea, Ray Leuning] Pulses of aboveground net primary productivity (ANPP) in response to discrete precipitation events are an integral feature of ecosystem functioning in arid and semi-arid lands. Yet, the usefulness of nonlinear, ecohydrological pulse response functions to predict regional-scale patterns of annual ANPP at decadal scales remains unclear. Here, we assessed how different pulse response (PR) models compete with simple linear statistical models to capture variability in yearly integrated values of Normalized Difference Vegetation Index (NDVIint), a remotely sensed proxy of annual ANPP. We examined 24-year-long time series of NDVIint calculated from Advanced Very High Resolution Radiometer (AVHRR) NDVI for 350,000km2 of tropical grasslands in northern Australia. Based on goodness-of-fit statistics, PR models clearly outperformed statistical models when parameters were optimized for each site but all models showed the same error magnitude when all sites were combined in ensemble simulations or when the models were evaluated outside the calibration period. PR models were less biased and their performance did not deteriorate in the driest areas compared to linear models. Increasing the complexity of PR models to provide a better representation of soil water balance and its feedback with plant growth did not improve model performance in ensemble simulations. When error magnitude, bias, and sensitivity to parameter uncertainty were all considered, we concluded that a low-dimensional PR model was the most robust to capture NDVIint variability. This study shows the potential of long time series of AVHRR NDVI to benchmark process-oriented models of interannual variability of NDVIint in water-controlled ecosystems. This opens new avenues to examine at the global scale and over several decades the causal relationships between climate and leaf dynamics in the grassland biome. Springer Science+Business Media, LLC, 2010 C4 grasslands nationallicence ecohydrology nationallicence phenology nationallicence precipitation pulses nationallicence semi-arid ecosystems nationallicence Choler Philippe CSIRO Marine and Atmospheric Research, PO Box 3023, 2601, Canberra, Australian Capital Territory, Australia aut Sea William CSIRO Marine and Atmospheric Research, PO Box 3023, 2601, Canberra, Australian Capital Territory, Australia aut Leuning Ray CSIRO Marine and Atmospheric Research, PO Box 3023, 2601, Canberra, Australian Capital Territory, Australia aut Ecosystems Springer-Verlag 14/2(2011-03-01), 183-197 1432-9840 14:2<183 2011 14 10021 https://doi.org/10.1007/s10021-010-9403-9 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1007/s10021-010-9403-9 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Choler Philippe CSIRO Marine and Atmospheric Research, PO Box 3023, 2601, Canberra, Australian Capital Territory, Australia aut NATIONALLICENCE 700 1- Sea William CSIRO Marine and Atmospheric Research, PO Box 3023, 2601, Canberra, Australian Capital Territory, Australia aut NATIONALLICENCE 700 1- Leuning Ray CSIRO Marine and Atmospheric Research, PO Box 3023, 2601, Canberra, Australian Capital Territory, Australia aut NATIONALLICENCE 773 0- Ecosystems Springer-Verlag 14/2(2011-03-01), 183-197 1432-9840 14:2<183 2011 14 10021 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer