Data/hora: 20/06/2024 04:08:17

Biblioteca(s): 	Embrapa Amazônia Oriental; Embrapa Meio Ambiente.	
Data corrente: 	03/12/2013	
Data da última atualização: 	07/03/2014	
Autoria: 	RESTREPO-COUPE, N.; ROCHA, H. R. da; HUTYRA, L. R.; ARAUJO, A. C. da; BORMA, L. S.; CHRISTOFFERSEN, B.; CABRAL, O. M. R.; CAMARGO, P. B. de; CARDOSO, F. L.; COSTA, A. C. L. da; FITZJARRALD, D. R.; GOULDEN, M. L.; KRUIJT, B.; MAIA, J. M. F.; MALHI, Y. S.; MANZI, A. O.; MILLER, S. D.; NOBRE, A. D.; RANDOW, C. von; SÁ, L. D. ABREU; SAKAI, R. K.; TOTA, J.; WOFSY, S. C.; ZANCHI, F. B.; SALESKA, S. R.	
Afiliação: 	NATALIA RESTREPO-COUPE, University of Arizona / University of Technology Sydney; HUMBERTO R. DA ROCHA, USP; LUCY R. HUTYRA, BOSTON UNIVERSITY; ALESSANDRO CARIOCA DE ARAUJO, CPATU / INPA; LAURA S. BORMA, USP; BRADLEY CHRISTOFFERSEN, UNIVERSITY OF ARIZONA; OSVALDO MACHADO RODRIGUES CABRAL, CNPMA; PLINIO B. DE CAMARGO, University of Technology Sydney; FERNANDO L. CARDOSO, UFTO; ANTONIO C. LOLA DA COSTA, UFPA; DAVID R. FITZJARRALD, State University of New York; MICHAEL L. GOULDEN, University of California Irvine; BART KRUIJT, Wageningen University and Research Centre; JAIR M. F. MAIA, INPA / UEAM; YADVINDER S. MALHI, Oxford University Centre for the Environment; ANTONIO O. MANZI, INPA; SCOTT D. MILLER, State University of New York; ANTONIO D. NOBRE, INPA; CELSO VON RANDOW, Wageningen University and Research Centre / Brazilian National Institute for Space Research; LEONARDO D. ABREU SÁ, INPE; RICARDO K. SAKAI, State University of New York; JULIA TOTA, INPA; STEVEN C. WOFSY, HARVARD UNIVERSITY; FABRICIO B. ZANCHI, Vrije Universiteit Amsterdam / UFAM; SCOTT R. SALESKA, UNIVERSITY OF ARIZONA.	
Título: 	What drives the seasonality of photosynthesis across the Amazon basin: a cross-site analysis of eddy flux tower measurements from the Brasil flux network.	
Ano de publicação: 	2013	
Fonte/Imprenta: 	Agricultural and Forest Meteorology, v. 182-183, p. 128-144, Dec. 2013.	
DOI: 	http://dx.doi.org/10.1016/j.agrformet.2013.04.031	
Idioma: 	Inglês	
Conteúdo: 	We investigated the seasonal patterns of Amazonian forest photosynthetic activity, and the effects thereon of variations in climate and land-use, by integrating data from a network of ground-based eddy flux towers in Brazil established as part of the ?Large-Scale Biosphere Atmosphere Experiment in Amazonia? project. We found that degree of water limitation, as indicated by the seasonality of the ratio of sensible to latent heat flux (Bowen ratio) predicts seasonal patterns of photosynthesis. In equatorial Amazonian forests (5° N?5° S), water limitation is absent, and photosynthetic fluxes (or gross ecosystem productivity, GEP) exhibit high or increasing levels of photosynthetic activity as the dry season progresses, likely a consequence of allocation to growth of new leaves. In contrast, forests along the southern flank of the Amazon, pastures converted from forest, and mixed forest-grass savanna, exhibit dry-season declines in GEP, consistent with increasing degrees of water limitation. Although previous work showed tropical ecosystem evapotranspiration (ET) is driven by incoming radiation, GEP observations reported here surprisingly show no or negative relationships with photosynthetically active radiation (PAR). Instead, GEP fluxes largely followed the phenology of canopy photosynthetic capacity (Pc), with only deviations from this primary pattern driven by variations in PAR. Estimates of leaf flush at three non-water limited equatorial forest sites peak in the dry season, in correlation with high dry season light levels. The higher photosynthetic capacity that follows persists into the wet season, driving high GEP that is out of phase with sunlight, explaining the negative observed relationship with sunlight. Overall, these patterns suggest that at sites where water is not limiting, light interacts with adaptive mechanisms to determine photosynthetic capacity indirectly through leaf flush and litterfall seasonality. These mechanisms are poorly represented in ecosystem models, and represent an important challenge to efforts to predict tropical forest responses to climatic variations.	
Palavras-Chave: 	Sazonalidade.	
Thesagro: 	Floresta Tropical.	
Thesaurus Nal: 	Amazonia.	
Categoria do assunto: 	--
K Ciência Florestal e Produtos de Origem Vegetal	
Registro original: 	Embrapa Meio Ambiente (CNPMA)	
Exemplares: 	CPATU - (48782-1) - UPC - AP - DD -  -  -  - DIS
CNPMA - (12949-1) - UPC - AP - DD -  -  -  - DIS