title: Shifts in plant respiration and carbon use efficiency at a large-scale drought experiment in the eastern Amazon.
abstract: *The effects of drought on the Amazon rainforest are potentially large but remain poorly understood. Here, carbon (C) cycling after 5 yr of a large-scale through-fall exclusion (TFE) experiment excluding about 50% of incident rainfall from an eastern Amazon rainforest was compared with a nearby control plot. *Principal C stocks and fluxes were intensively measured in 2005. Additional minor components were either quantified in later site measurements or derived from the available literature. *Total ecosystem respiration (R(eco)) and total plant C expenditure (PCE, the sum of net primary productivity (NPP) and autotrophic respiration (R(auto))), were elevated on the TFE plot relative to the control. The increase in PCE and R(eco) was mainly caused by a rise in R(auto) from foliage and roots. Heterotrophic respiration did not differ substantially between plots. NPP was 2.4 +/- 1.4 t C ha(-1) yr(-1) lower on the TFE than the control. Ecosystem carbon use efficiency, the proportion of PCE invested in NPP, was lower in the TFE plot (0.24 +/- 0.04) than in the control (0.32 +/- 0.04). *Drought caused by the TFE treatment appeared to drive fundamental shifts in ecosystem C cycling with potentially important consequences for long-term forest C storage.
authors.affiliation: Centre for the Environment, University of Oxford, Oxford, UK. daniel.metcalfe@ouce.ox.ac.uk
authors.forename: D B
authors.initials: DB
authors.lastname: Metcalfe
authors.forename: P
authors.initials: P
authors.lastname: Meir
authors.forename: L E O C
authors.initials: LE
authors.lastname: Aragão
authors.forename: R
authors.initials: R
authors.lastname: Lobo-do-Vale
authors.forename: D
authors.initials: D
authors.lastname: Galbraith
authors.forename: R A
authors.initials: RA
authors.lastname: Fisher
authors.forename: M M
authors.initials: MM
authors.lastname: Chaves
authors.forename: J P
authors.initials: JP
authors.lastname: Maroco
authors.forename: A C L
authors.initials: AC
authors.lastname: da Costa
authors.forename: S S
authors.initials: SS
authors.lastname: de Almeida
authors.forename: A P
authors.initials: AP
authors.lastname: Braga
authors.forename: P H L
authors.initials: PH
authors.lastname: Gonçalves
authors.forename: J
authors.initials: J
authors.lastname: de Athaydes
authors.forename: M
authors.initials: M
authors.lastname: da Costa
authors.forename: T T B
authors.initials: TT
authors.lastname: Portela
authors.forename: A A R
authors.initials: AA
authors.lastname: de Oliveira
authors.forename: Y
authors.initials: Y
authors.lastname: Malhi
authors.forename: M
authors.initials: M
authors.lastname: Williams
mesh_terms: D001419:Bacteria / Q000378:metabolism; D001938:Brazil; D002244:Carbon / Q000378:metabolism*; D002245:Carbon Dioxide / Q000378:metabolism; D019069:Cell Respiration; D055864:Droughts; D017753:Ecosystem; D012987:Soil; D013997:Time Factors; D014197:Trees / Q000378:metabolism*
chemical_list: D012987:Soil; D002245:Carbon Dioxide; D002244:Carbon