title: Leaf development and demography explain photosynthetic seasonality in Amazon evergreen forests.
abstract: In evergreen tropical forests, the extent, magnitude, and controls on photosynthetic seasonality are poorly resolved and inadequately represented in Earth system models. Combining camera observations with ecosystem carbon dioxide fluxes at forests across rainfall gradients in Amazônia, we show that aggregate canopy phenology, not seasonality of climate drivers, is the primary cause of photosynthetic seasonality in these forests. Specifically, synchronization of new leaf growth with dry season litterfall shifts canopy composition toward younger, more light-use efficient leaves, explaining large seasonal increases (~27%) in ecosystem photosynthesis. Coordinated leaf development and demography thus reconcile seemingly disparate observations at different scales and indicate that accounting for leaf-level phenology is critical for accurately simulating ecosystem-scale responses to climate change.
authors.affiliation: Department of Ecology and Evolutionary Biology, University of Arizona, Tucson, AZ 85721, USA. jinwu@email.arizona.edu saleska@email.arizona.edu.
authors.forename: Jin
authors.initials: J
authors.lastname: Wu
authors.affiliation: Department of Ecology and Evolutionary Biology, University of Arizona, Tucson, AZ 85721, USA.
authors.forename: Loren P
authors.initials: LP
authors.lastname: Albert
authors.affiliation: Brazil's National Institute for Amazon Research (INPA), Manaus, Amazonas, Brazil.
authors.forename: Aline P
authors.initials: AP
authors.lastname: Lopes
authors.affiliation: Department of Ecology and Evolutionary Biology, University of Arizona, Tucson, AZ 85721, USA. Plant Functional Biology and Climate Change Cluster, University of Technology Sydney, Sydney, NSW, Australia.
authors.forename: Natalia
authors.initials: N
authors.lastname: Restrepo-Coupe
authors.affiliation: John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, MA 02138, USA.
authors.forename: Matthew
authors.initials: M
authors.lastname: Hayek
authors.affiliation: Department of Ecology and Evolutionary Biology, University of Arizona, Tucson, AZ 85721, USA. John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, MA 02138, USA.
authors.forename: Kenia T
authors.initials: KT
authors.lastname: Wiedemann
authors.affiliation: Department of Natural Resources and Environmental Science, University of Illinois at Urbana Champaign, Urbana, IL 61081, USA. Department of Earth System Science, Stanford University, Stanford, CA 94025, USA.
authors.forename: Kaiyu
authors.initials: K
authors.lastname: Guan
authors.affiliation: Department of Forestry, Michigan State University, East Lansing, MI 48824, USA.
authors.forename: Scott C
authors.initials: SC
authors.lastname: Stark
authors.affiliation: Department of Ecology and Evolutionary Biology, University of Arizona, Tucson, AZ 85721, USA. Earth and Environmental Sciences Division, Los Alamos National Lab, Los Alamos, NM 87545, USA.
authors.forename: Bradley
authors.initials: B
authors.lastname: Christoffersen
authors.affiliation: Department of Ecology and Evolutionary Biology, University of Arizona, Tucson, AZ 85721, USA.
authors.forename: Neill
authors.initials: N
authors.lastname: Prohaska
authors.affiliation: Brazil's National Institute for Amazon Research (INPA), Manaus, Amazonas, Brazil.
authors.forename: Julia V
authors.initials: JV
authors.lastname: Tavares
authors.affiliation: Brazil's National Institute for Amazon Research (INPA), Manaus, Amazonas, Brazil.
authors.forename: Suelen
authors.initials: S
authors.lastname: Marostica
authors.affiliation: Department of Environmental Geochemical Cycle Research, Japan Agency for Marine-Earth Science and Technology, Yokohama, Japan.
authors.forename: Hideki
authors.initials: H
authors.lastname: Kobayashi
authors.affiliation: Centro de Energia Nuclear na Agricultura, University of Sao Paulo, Piracicaba, SP, Brazil. Smart and Intelligent Cities Programme, University Nove de Julho, São Paulo, SP, Brazil.
authors.forename: Mauricio L
authors.initials: ML
authors.lastname: Ferreira
authors.affiliation: Department of Environmental Physics, University of Western Para (UFOPA), Santarem, Para, Brazil.
authors.forename: Kleber Silva
authors.initials: KS
authors.lastname: Campos
authors.affiliation: Department of Environmental Physics, University of Western Para (UFOPA), Santarem, Para, Brazil.
authors.forename: Rodrigo
authors.initials: R
authors.lastname: da Silva
authors.affiliation: Instituto de Pesquisa Ambiental da Amazônia (IPAM), Belem, Para, Brazil. Woods Hole Research Center, Falmouth, MA 02450, USA.
authors.forename: Paulo M
authors.initials: PM
authors.lastname: Brando
authors.affiliation: Western Geographic Science Center, U.S. Geological Survey, Flagstaff, AZ 86001, USA.
authors.forename: Dennis G
authors.initials: DG
authors.lastname: Dye
authors.affiliation: Ecology and Evolutionary Biology and Center for Environmental Biology, University of California, Irvine, CA 92629, USA.
authors.forename: Travis E
authors.initials: TE
authors.lastname: Huxman
authors.affiliation: Plant Functional Biology and Climate Change Cluster, University of Technology Sydney, Sydney, NSW, Australia.
authors.forename: Alfredo R
authors.initials: AR
authors.lastname: Huete
authors.affiliation: Brazil's National Institute for Amazon Research (INPA), Manaus, Amazonas, Brazil.
authors.forename: Bruce W
authors.initials: BW
authors.lastname: Nelson
authors.affiliation: Department of Ecology and Evolutionary Biology, University of Arizona, Tucson, AZ 85721, USA. jinwu@email.arizona.edu saleska@email.arizona.edu.
authors.forename: Scott R
authors.initials: SR
authors.lastname: Saleska
mesh_terms: D057231:Climate Change; D003710:Demography; D065928:Forests; D008027:Light; D010788:Photosynthesis; D018515:Plant Leaves / Q000254:growth & development* / Q000378:metabolism*; D012621:Seasons; D014329:Tropical Climate