title: The variation of productivity and its allocation along a tropical elevation gradient: a whole carbon budget perspective.
abstract: Why do forest productivity and biomass decline with elevation? To address this question, research to date generally has focused on correlative approaches describing changes in woody growth and biomass with elevation. We present a novel, mechanistic approach to this question by quantifying the autotrophic carbon budget in 16 forest plots along a 3300 m elevation transect in Peru. Low growth rates at high elevations appear primarily driven by low gross primary productivity (GPP), with little shift in either carbon use efficiency (CUE) or allocation of net primary productivity (NPP) between wood, fine roots and canopy. The lack of trend in CUE implies that the proportion of photosynthate allocated to autotrophic respiration is not sensitive to temperature. Rather than a gradual linear decline in productivity, there is some limited but nonconclusive evidence of a sharp transition in NPP between submontane and montane forests, which may be caused by cloud immersion effects within the cloud forest zone. Leaf-level photosynthetic parameters do not decline with elevation, implying that nutrient limitation does not restrict photosynthesis at high elevations. Our data demonstrate the potential of whole carbon budget perspectives to provide a deeper understanding of controls on ecosystem functioning and carbon cycling.
authors: Environmental Change Institute, School of Geography and the Environment, University of Oxford, Oxford, OX1 3QY, UK.
authors: Yadvinder
authors: Y
authors: Malhi
authors: Environmental Change Institute, School of Geography and the Environment, University of Oxford, Oxford, OX1 3QY, UK.
authors: Cécile A J
authors: CA
authors: Girardin
authors: Ecosystem Fluxes Group, Laboratory for Atmospheric Chemistry, Paul Scherrer Institute, Villigen PSI, 5232, Switzerland.
authors: Gregory R
authors: GR
authors: Goldsmith
authors: Environmental Change Institute, School of Geography and the Environment, University of Oxford, Oxford, OX1 3QY, UK.
authors: Christopher E
authors: CE
authors: Doughty
authors: Environmental Change Institute, School of Geography and the Environment, University of Oxford, Oxford, OX1 3QY, UK.|Universidad Nacional San Antonio Abad del Cusco, Cusco, Peru.
authors: Norma
authors: N
authors: Salinas
authors: Department of Physical Geography and Ecosystem Science, Lund University, SE 223 62, Lund, Sweden.
authors: Daniel B
authors: DB
authors: Metcalfe
authors: Universidad Nacional San Antonio Abad del Cusco, Cusco, Peru.
authors: Walter
authors: W
authors: Huaraca Huasco
authors: Universidad Nacional San Antonio Abad del Cusco, Cusco, Peru.
authors: Javier E
authors: JE
authors: Silva-Espejo
authors: IIAP, Iquitos, Peru.
authors: Jhon
authors: J
authors: Del Aguilla-Pasquell
authors: Universidad Nacional San Antonio Abad del Cusco, Cusco, Peru.
authors: Filio
authors: F
authors: Farfán Amézquita
authors: Remote Sensing Division, National Institute for Space Research, Av. dos Astronautas, 1.758, São José dos Campos, SP, 12227-010, Brazil.|College of Life and Environmental Sciences, University of Exeter, Exeter, EX4 4QD, UK.
authors: Luiz E O C
authors: LE
authors: Aragão
authors: Centre for Ecological Research and Forestry Applications, CREAF c/o Universidad Autonoma de Barcelona, Edificio C, 08290, Cerdanyola, Barcelona, Spain.|School of Geosciences, University of Edinburgh, Edinburgh, EH8 9XP, UK.
authors: Rossella
authors: R
authors: Guerrieri
authors: College of Marine and Environmental Sciences, Centre of Tropical Environmental and Sustainabilility Science, James Cook University, Cairns, Qld, 4870, Australia.
authors: Françoise Yoko
authors: FY
authors: Ishida
authors: ARC Centre of Excellence in Plant Energy Biology, Research School of Biology, Building 134, The Australian National University, Canberra, ACT, 2601, Australia.
authors: Nur H A
authors: NH
authors: Bahar
authors: Department of Biology, Wake Forest University, Winston-Salem, NC, 27109, USA.
authors: William
authors: W
authors: Farfan-Rios
authors: School of Geography, University of Leeds, Leeds, LS2 9JT, UK.
authors: Oliver L
authors: OL
authors: Phillips
authors: School of Geosciences, University of Edinburgh, Edinburgh, EH8 9XP, UK.|ARC Centre of Excellence in Plant Energy Biology, Research School of Biology, Building 134, The Australian National University, Canberra, ACT, 2601, Australia.
authors: Patrick
authors: P
authors: Meir
authors: Department of Biology, Wake Forest University, Winston-Salem, NC, 27109, USA.
authors: Miles
authors: M
authors: Silman
mesh_terms: D000531:Altitude; D052818:Autotrophic Processes; D002244:Carbon / Q000378:metabolism*; D057486:Carbon Cycle; D065928:Forests; D010788:Photosynthesis; D014329:Tropical Climate
chemical_list: D002244:Carbon
keywords: 
  RAINFOR
  ; Global Ecosystems Monitoring network (GEM); climate; cloud forest; photosynthesis; physiology; temperature