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Advisor(s)
Abstract(s)
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 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 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.
Description
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
Citation
Functional Ecology, 24, 524-533