Use este identificador para citar ou linkar para este item:
https://repositorio.inpa.gov.br/handle/1/17605
Título: | Mechanisms of water supply and vegetation demand govern the seasonality and magnitude of evapotranspiration in Amazonia and Cerrado |
Autor: | Christoffersen, Bradley O. Restrepo-Coupé, Natalia Arain, Muhammad Altaf Baker, Ian T. Cestaro, Bruno P. Ciais, Philippe Fisher, Joshua B. Galbraith, David R. Guan, Xiaodan Gulden, Lindsey E. Van Den Hurk, B. J.J.M. Ichii, Kazuhito Imbuzeiro, Hewlley Maria Acioli Jain, Atul K. Levine, Naomi Marcil Miguez-Macho, Gonzalo Poulter, Benjamin Roberti, Débora Regina Sakaguchi, Koichi Sahoo, Alok Kumar Schaefer, Kevin M. Shi, Mingjie Verbeeck, Hans Yang, Zongliang Araüjo, Alessandro Carioca de Kruijt, Bart J. Manzi, Antônio Ocimar Rocha, Humberto Ribeiro da Randow, Celso Von Muza, Michel Nobre Borak, Jordan S. Costa, Marcos Heil Gonçalves, Luis Gustavo de Zeng, Xubin Saleska, Scott Reid |
Palavras-chave: | Ecosystem Modeling Eddy Covariance Evapotranspiration Forest Ecosystem Light Effect Root System Seasonality Tropical Forest Water Demand Water Supply Amazonia |
Data do documento: | 2014 |
Revista: | Agricultural and Forest Meteorology |
É parte de: | Volume 191, Pags. 33-50 |
Abstract: | Evapotranspiration (E) in the Amazon connects forest function and regional climate via its role in precipitation recycling However, the mechanisms regulating water supply to vegetation and its demand for water remain poorly understood, especially during periods of seasonal water deficits In this study, we address two main questions: First, how do mechanisms of water supply (indicated by rooting depth and groundwater) and vegetation water demand (indicated by stomatal conductance and intrinsic water use efficiency) control evapotranspiration (E) along broad gradients of climate and vegetation from equatorial Amazonia to Cerrado, and second, how do these inferred mechanisms of supply and demand compare to those employed by a suite of ecosystem models? We used a network of eddy covariance towers in Brazil coupled with ancillary measurements to address these questions With respect to the magnitude and seasonality of E, models have much improved in equatorial tropical forests by eliminating most dry season water limitation, diverge in performance in transitional forests where seasonal water deficits are greater, and mostly capture the observed seasonal depressions in E at Cerrado However, many models depended universally on either deep roots or groundwater to mitigate dry season water deficits, the relative importance of which we found does not vary as a simple function of climate or vegetation In addition, canopy stomatal conductance (gs) regulates dry season vegetation demand for water at all except the wettest sites even as the seasonal cycle of E follows that of net radiation In contrast, some models simulated no seasonality in gs, even while matching the observed seasonal cycle of E. We suggest that canopy dynamics mediated by leaf phenology may play a significant role in such seasonality, a process poorly represented in models Model bias in gs and E, in turn, was related to biases arising from the simulated light response (gross primary productivity, GPP) or the intrinsic water use efficiency of photosynthesis (iWUE). We identified deficiencies in models which would not otherwise be apparent based on a simple comparison of simulated and observed rates of E. While some deficiencies can be remedied by parameter tuning, in most models they highlight the need for continued process development of belowground hydrology and in particular, the biological processes of root dynamics and leaf phenology, which via their controls on E, mediate vegetation-climate feedbacks in the tropics. © 2014 Elsevier B.V. |
DOI: | 10.1016/j.agrformet.2014.02.008 |
Aparece nas coleções: | Artigos |
Arquivos associados a este item:
Não existem arquivos associados a este item.
Os itens no repositório estão protegidos por copyright, com todos os direitos reservados, salvo quando é indicado o contrário.