1.MAPPING OF PLANT LIGHT BUDGETS IN MULTISTRATA HETEROGENEOUS PLOTS Fabien Charbonnier1,2,3,4,*, Guerric le Maire1, Erwin Dreyer2,3, Fernando Casanoves4, Mathias Christina1, Jean Dauzat5, Jan U.H. Eitel6,7, Philippe Vaast1,8, Lee A. Vierling6, Karel Van den Meersche1,4, Jean-Michel Harmand1 & Olivier Roupsard1,4 1CIRAD,UMR Eco&Sols (Ecologie Fonctionnelle & Biogochimie des Sols et des Agro-cosystmes), 34060 Montpellier Cedex 2, France; de Lorraine, UMR 1137 Ecologie et Ecophysiologie Forestires, F 54500 Vandoeuvre, France; 3INRA, UMR 1137 Ecologie et Ecophysiologie Forestires, F54280 Champenoux, France; 4CATIE (Centro Agronmico Tropical de Investigacin y Enseanza), 7170 Turrialba, Costa Rica; 5CIRAD, UMR AMAP, 34000 Montpellier, France; 6 Dept. of Forest, Rangeland, and Fire Sciences, University of Idaho, Moscow, ID, United States; 7McCall Outdoor Science School, University of Idaho, McCall, ID, United States; 8ICRAF, United Nations Avenue, Gigiri, PO Box 30677-00100, Nairobi, Kenya 2Universit50 m

2. Study site: Coffee-flux platformCourtesy of: J. Eitel, U. IdahoCoffee: Planted in rows, Spatial heterogeneity, different plant heights Erythrina: Fabaceae, deciduous, large, free-growing, sparse 2 3. Study site: Coffee-flux platformCourtesy of: J. Eitel, U. IdahoCoffee: Planted in rows, Spatial heterogeneity, different plant heights Erythrina: Fabaceae, deciduous, large, free-growing, sparse 3 4. Choosing a model suitable for our experiment Sun areaShaded areaTREEScale CROPHomogeneous Sun Vs Shade Canopy Resolution # of parameters Complexity Time for simulation CAF2007 (van Oijen, 2010) WaNULCAS (van Noordwijk)Heterogeneous Simplified CanopiesMAESTRA/MAESPA Medlyn et al. , 2004 Duursma et al., 20123D Heterogeneous Canopy Dauzat et al., 2001 5. M&M - MAESPA Parameterization and verification strategyMedlyn, 2004 Duursma et al., 2012NDVI Sensor5 6. PPFD transmitted by shade trees 1N No clear azimuthal effect / Large effect distance / Effect of shade trees larger than the crown 6 projection / 14% of total irradiance intercepted 7. Mapping yearly absorbed PPFD of coffee canopy Fraction of absorbed diffuse PPFDAbsorbed PPFD (Mmol m-2 y-1)Fraction of absorbed diffuse PPFDYearly absorbed PPFDTransect lengthTransect length7 8. Effect of increasing tree densityFraction of absorbed radiation (coffee layer)On fraction of yearly absorbed PPFD0.6 Y=0.66*exp-0.34*X 0.50.40.30.2 0 (0%)0.5 (8%)1 (16%) 1.5 (24%) 2 (32%) Mean PAIsh (% Cover)2.5 (40%)3 (48%) 8 9. Main perspectives Light is now a continuous variable:Explanatory variable in experimental designs e.g. Study of disease development, crop productivity, crop quality ? Prospective analysis : e.g. Which spatial arrangement / densities for optimal light absorption?9 10. THANK YOU ! THIS EXPERIMENT WAS CONDUCTED WITHINFLUXNET/COFFEE-FLUX OBSERVATORYwww5.montpellier.inra.fr/ecosols/Recherche/Les-projets/CoffeeFlux MAESPA model: http://bio.mq.edu.au/maestra