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.

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

Published in

Functional Ecology
2010, Volume: 24, number: 3, pages: 524-533
Publisher: WILEY-BLACKWELL

UKÄ Subject classification

Climate Research


Publication identifier

DOI: https://doi.org/10.1111/j.1365-2435.2009.01683.x

Permanent link to this page (URI)

https://res.slu.se/id/publ/76336