Publicação
Impacts of experimentally imposed drought on leaf respiration and morphology in an Amazon rain forest
| Resumo: | 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. |
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| Autores principais: | Metcalfe, Daniel B. |
| Outros Autores: | Lobo-do-Vale, Raquel; Chaves, Maria Manuela; Maroco, João; Aragão, Luiz E. O. C.; Malhi, Yadvinder; Costa, António L. da; Braga, Alan P.; Gonçalves, Paulo L.; Athaydes, João de; Costa, Mauricio da; Almeida, Samuel S.; Campbell, Catherine; Hurry, Vaughan; Williams, Mathew; Meir, Patrick |
| Assunto: | Tropical forest Climate change Moisture deficit Leaf dark respiration Night-time foliar carbon emissions Specific leaf area Leaf area index Through-fall exclusion experiment |
| Ano: | 2010 |
| País: | Portugal |
| Tipo de documento: | artigo |
| Tipo de acesso: | acesso aberto |
| Instituição associada: | Ispa-Instituto Universitário |
| Idioma: | inglês |
| Origem: | Repositório do Ispa - Instituto Universitário |
| Resumo: | 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. |
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