title: Increased light-use efficiency sustains net primary productivity of shaded coffee plants in agroforestry system.
abstract: In agroforestry systems, shade trees strongly affect the physiology of the undergrown crop. However, a major paradigm is that the reduction in absorbed photosynthetically active radiation is, to a certain extent, compensated by an increase in light-use efficiency, thereby reducing the difference in net primary productivity between shaded and non-shaded plants. Due to the large spatial heterogeneity in agroforestry systems and the lack of appropriate tools, the combined effects of such variables have seldom been analysed, even though they may help understand physiological processes underlying yield dynamics. In this study, we monitored net primary productivity, during two years, on scales ranging from individual coffee plants to the entire plot. Absorbed radiation was mapped with a 3D model (MAESPA). Light-use efficiency and net assimilation rate were derived for each coffee plant individually. We found that although irradiance was reduced by 60% below crowns of shade trees, coffee light-use efficiency increased by 50%, leaving net primary productivity fairly stable across all shade levels. Variability of aboveground net primary productivity of coffee plants was caused primarily by the age of the plants and by intraspecific competition among them (drivers usually overlooked in the agroforestry literature) rather than by the presence of shade trees.
authors.affiliation: CONACyT research fellow, El Colegio de la Frontera Sur, San Cristóbal de las Casas, 29290, Chiapas, Mexico.|CIRAD, UMR Eco&Sols, F-34398, Montpellier, France.
authors.forename: Fabien
authors.identifier: http://orcid.org/0000-0002-2637-2457
authors.initials: F
authors.lastname: Charbonnier
authors.affiliation: CIRAD, UMR Eco&Sols, F-34398, Montpellier, France.|CATIE (Centro Agronómico Tropical de Investigación y Enseñanza), 7170, Turrialba, Costa Rica.
authors.forename: Olivier
authors.initials: O
authors.lastname: Roupsard
authors.affiliation: CIRAD, UMR Eco&Sols, F-34398, Montpellier, France.
authors.forename: Guerric
authors.initials: G
authors.lastname: le Maire
authors.affiliation: CIRAD, UMR Eco&Sols, F-34398, Montpellier, France.
authors.forename: Joannès
authors.initials: J
authors.lastname: Guillemot
authors.affiliation: CATIE (Centro Agronómico Tropical de Investigación y Enseñanza), 7170, Turrialba, Costa Rica.
authors.forename: Fernando
authors.initials: F
authors.lastname: Casanoves
authors.affiliation: Inra, Université Blaise Pascal, UMR 547 PIAF, F-63100, Clermont-Ferrand, France.
authors.forename: André
authors.initials: A
authors.lastname: Lacointe
authors.affiliation: CIRAD, UMR Eco&Sols, F-34398, Montpellier, France.|World Agroforestry Centre (ICRAF), United Nations Avenue, PO Box 30677, 00100, Nairobi, Kenya.
authors.forename: Philippe
authors.initials: P
authors.lastname: Vaast
authors.affiliation: CATIE (Centro Agronómico Tropical de Investigación y Enseñanza), 7170, Turrialba, Costa Rica.|CIRAD, Inra, SupAgro-Montpellier, UMR System, 34060, Montpellier, France.
authors.forename: Clémentine
authors.initials: C
authors.lastname: Allinne
authors.affiliation: CIRAD, UMR Eco&Sols, F-34398, Montpellier, France.
authors.forename: Louise
authors.initials: L
authors.lastname: Audebert
authors.affiliation: CIRAD, UMR Eco&Sols, F-34398, Montpellier, France.
authors.forename: Aurélie
authors.initials: A
authors.lastname: Cambou
authors.affiliation: CIRAD, UMR AGAP, F-34398, Montpellier, France.
authors.forename: Anne
authors.initials: A
authors.lastname: Clément-Vidal
authors.affiliation: CIRAD, UMR Eco&Sols, F-34398, Montpellier, France.
authors.forename: Elsa
authors.initials: E
authors.lastname: Defrenet
authors.affiliation: Hawkesbury Institute for the Environment, Western Sydney University, Penrith, 2751, New South West, Australia.
authors.forename: Remko A
authors.initials: RA
authors.lastname: Duursma
authors.affiliation: CIRAD, UMR Eco&Sols, F-34398, Montpellier, France.
authors.forename: Laura
authors.initials: L
authors.lastname: Jarri
authors.affiliation: CIRAD, UMR Eco&Sols, F-34398, Montpellier, France.
authors.forename: Christophe
authors.initials: C
authors.lastname: Jourdan
authors.affiliation: CIRAD, UMR Eco&Sols, F-34398, Montpellier, France.
authors.forename: Emmanuelle
authors.initials: E
authors.lastname: Khac
authors.affiliation: CATIE (Centro Agronómico Tropical de Investigación y Enseñanza), 7170, Turrialba, Costa Rica.
authors.forename: Patricia
authors.initials: P
authors.lastname: Leandro
authors.affiliation: Hawkesbury Institute for the Environment, Western Sydney University, Penrith, 2751, New South West, Australia.
authors.forename: Belinda E
authors.initials: BE
authors.lastname: Medlyn
authors.affiliation: CIRAD, UMR Eco&Sols, F-34398, Montpellier, France.|Inra, Biogéochimie des Ecosystèmes Forestiers, F-54280, Champenoux, France.
authors.forename: Laurent
authors.initials: L
authors.lastname: Saint-André
authors.affiliation: CIRAD, UMR Eco&Sols, F-34398, Montpellier, France.
authors.forename: Philippe
authors.initials: P
authors.lastname: Thaler
authors.affiliation: CIRAD, UMR Eco&Sols, F-34398, Montpellier, France.|CATIE (Centro Agronómico Tropical de Investigación y Enseñanza), 7170, Turrialba, Costa Rica.
authors.forename: Karel
authors.initials: K
authors.lastname: Van Den Meersche
authors.affiliation: Cafetalera Aquiares S.A., PO Box 362-7150, Turrialba, 7150, Costa Rica.
authors.forename: Alejandra
authors.initials: A
authors.lastname: Barquero Aguilar
authors.affiliation: Cafetalera Aquiares S.A., PO Box 362-7150, Turrialba, 7150, Costa Rica.
authors.forename: Peter
authors.initials: P
authors.lastname: Lehner
authors.affiliation: Inra, Université de Lorraine, UMR 1137 'Ecologie et Ecophysiologie Forestières', F54280, Champenoux, France.
authors.forename: Erwin
authors.initials: E
authors.lastname: Dreyer
mesh_terms: D000383:Agriculture; D018533:Biomass; D040503:Coffea / Q000502:physiology* / Q000528:radiation effects*; D016468:Forestry; D008027:Light; D016014:Linear Models; D008834:Microclimate; D018515:Plant Leaves / Q000502:physiology / Q000528:radiation effects; D014197:Trees / Q000502:physiology / Q000528:radiation effects
keywords: Coffea arabica; MAESPA; carbon allocation; light absorption model; net assimilation rate (NAR)