Data/hora: 19/06/2024 13:40:24

Biblioteca(s): 	Embrapa Meio Ambiente.	
Data corrente: 	17/08/2011	
Data da última atualização: 	31/01/2012	
Autoria: 	NEILL, C.; CHAVES, J. E.; BIGGS, T.; DEEGAN, L. A.; ELSENBEER, H.; FIGUEIREDO, R. de O.; GERMER, S.; JOHNSON, M. S.; LEHMANN, J.; MARKEWITZ, D.	
Afiliação: 	CHRISTOPHER NEILL, The Ecosystems Center; JOAQUIN E. CHAVES, The Ecosystems Center; TRENT BIGGS, San Diego State University; LINDA A. DEEGAN, The Ecosystems Center; HELMUT ELSENBEER, University of Potsdam; RICARDO DE OLIVEIRA FIGUEIREDO, CNPMA; SONJA GERMER, University of Potsdam; MARK S. JOHNSON, University of British Columbia; JOHANNES LEHMAN, Cornell University; DANIEL MARKEWITZ, University of Georgia.	
Título: 	Runoff sources and land cover change in the Amazon: an end-member mixing analysis from small watersheds.	
Ano de publicação: 	2011	
Fonte/Imprenta: 	Biogeochemistry, Dordrecht, v. 105, n.1-3, p. 7-18, 2011.	
Idioma: 	Inglês	
Conteúdo: 	Abstract: The flowpaths by which water moves from watersheds to streams has important consequences for the runoff dynamics and biogeochemistry of surface waters in the Amazon Basin. The clearing of Amazon forest to cattle pasture has the potential to change runoff sources to streams by shifting runoff to more surficial flow pathways. We applied end-member mixing analysis (EMMA) to 10 small watersheds throughout the Amazon in which solute composition of streamwater and groundwater, overland flow, soil solution, throughfall and rainwater were measured, largely as part of the Large-Scale Biosphere-Atmosphere Experiment in Amazonia. We found a range in the extent to which streamwater samples fell within the mixing space determined by potential flowpath endmembers, suggesting that some water sources to streams were not sampled. The contribution of overland flow as a source of stream flow was greater in pasture watersheds than in forest watersheds of comparable size. Increases in overland flow contribution to pasture streams ranged in some cases from 0% in forest to 27-28% in pasture and were broadly consistent with results from hydrometric sampling of Amazon forest and pasture watersheds that indicate 17- to 18-fold increase in the overland flow contribution to stream flow in pastures. In forest, overland flow was an important contribution to stream flow (45-57%) in ephemeral streams where flows were dominated by stormflow. Overland flow contribution to stream flow decreased in importance with increasing watershed area, from 21 to 57% in forest and 60?89% in pasture watersheds of less than 10 ha to 0% in forest and 27-28% in pastures in watersheds greater than 100 ha. Soil solution contributions to stream flow were similar across watershed area and groundwater inputs generally increased in proportion to decreases in overland flow. Application of EMMA across multiple watersheds indicated patterns across gradients of stream size and land cover that were consistent with patterns determined by detailed hydrometric sampling.	
Palavras-Chave: 	Cattle pasture; Flowpaths; Principal components analysis.	
Thesagro: 	Bacia hidrográfica; Desmatamento; Fluviometria; Impacto ambiental; Pastagem.	
Thesaurus Nal: 	Deforestation; Overland flow; Runoff; Soil solution; Tropical pastures; Water flow.	
Categoria do assunto: 	P Recursos Naturais, Ciências Ambientais e da Terra	
Registro original: 	Embrapa Meio Ambiente (CNPMA)	
Exemplares: 	CNPMA - (10407-1) - UPC - AP - DD -  -  -  - DIS