Impacts of experimentally imposed drought on leaf respiration and morphology in an Amazon rain forest

Daniel B. Metcalfe, Raquel Lobo-do-Vale, Manuela M. Chaves, Joao P. Maroco, Luiz E. O. C. Aragao, Yadvinder Malhi, Antonio L. Da Costa, Alan P. Braga, Paulo L. Goncalves, Joao De Athaydes, Mauricio Da Costa, Samuel S. Almeida, Catherine Campbell, Vaughan Hurry, Mathew Williams, Patrick Meir

Research output: Contribution to journalArticlepeer-review

Abstract

P>1. The Amazon region may experience increasing moisture limitation over this century. Leaf dark respiration (R) is a key component of the Amazon rain forest carbon (C) cycle, but relatively little is known about its sensitivity to drought.

2. Here, we present measurements of R standardized to 25 degrees C and leaf morphology from different canopy heights over 5 years at a rain forest subject to a large-scale through-fall reduction (TFR) experiment, and nearby, unmodified Control forest, at the Caxiuana reserve in the eastern Amazon.

3. In all five post-treatment measurement campaigns, mean R at 25 degrees C was elevated in the TFR forest compared to the Control forest experiencing normal rainfall. After 5 years of the TFR treatment, R per unit leaf area and mass had increased by 65% and 42%, respectively, relative to pre-treatment means. In contrast, leaf area index (L) in the TFR forest was consistently lower than the Control, falling by 23% compared to the pre-treatment mean, largely because of a decline in specific leaf area (S).

4. The consistent and significant effects of the TFR treatment on R, L and S suggest that severe drought events in the Amazon, of the kind that may occur more frequently in future, could cause a substantial increase in canopy carbon dioxide emissions from this ecosystem to the atmosphere.

Original languageEnglish
Pages (from-to)524-533
Number of pages10
JournalFunctional Ecology
Volume24
Issue number3
DOIs
Publication statusPublished - Jun 2010

Keywords

  • tropical forest
  • climate change
  • moisture deficit
  • leaf dark respiration
  • night-time foliar carbon emissions
  • specific leaf area
  • leaf area index
  • through-fall exclusion experiment
  • SOIL CO2 EFFLUX
  • TROPICAL FOREST
  • DARK RESPIRATION
  • PLANT RESPIRATION
  • EASTERN AMAZONIA
  • CARBON-DIOXIDE
  • GAS-EXCHANGE
  • TEMPERATURE
  • CLIMATE
  • VARIABILITY

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