Data/hora: 13/06/2024 05:36:20

Biblioteca(s): | Embrapa Amazônia Oriental.
Data corrente: | 26/06/2013
Data da última atualização: | 07/11/2022
Autoria: | IVANOV, V. Y.; HUTYRA, L. R.; WOFSY, S.; MUNGER, J. W.; SALESKA, S. R.; OLIVEIRA JUNIOR, R. C. de; CAMARGO, P. B. de.
Afiliação: | Valeriy Y. Ivanov, University of Michigan / Harvard University; Lucy R. Hutyra, Harvard University / Boston University; Steven C. Wofsy, Harvard University; J. William Munger, Harvard University; Scott R. Saleska, University of Arizona; RAIMUNDO COSME DE OLIVEIRA JUNIOR, CPATU; Plínio B. de Camargo, USP.
Título: | Root niche separation can explain avoidance of seasonal drought stress and vulnerability of overstory trees to extended drought in a mature Amazonian forest.
Ano de publicação: | 2012
Fonte/Imprenta: | Water Resources Research, v. 48, n. 12, p. 1-21, Dec. 2012.
DOI: | 10.1029/2012WR011972
Idioma: | Inglês
Conteúdo: | Large areas of Amazonian evergreen forest experience seasonal droughts extending for three or more months, yet show maximum rates of photosynthesis and evapotranspiration during dry intervals. This apparent resilience is belied by disproportionate mortality of the large trees in manipulations that reduce wet season rainfall, occurring after 2?3 years of treatment. The goal of this study is to characterize the mechanisms that produce these contrasting ecosystem responses. A mechanistic model is developed based on the ecohydrological framework of TIN (Triangulated Irregular Network)-based Real Time Integrated Basin Simulator + Vegetation Generator for Interactive Evolution (tRIBS+VEGGIE). The model is used to test the roles of deep roots and soil capillary flux to provide water to the forest during the dry season. Also examined is the importance of ?root niche separation,? in which roots of overstory trees extend to depth, where during the dry season they use water stored from wet season precipitation, while roots of understory trees are concentrated in shallow layers that access dry season precipitation directly. Observational data from the Tapajós National Forest, Brazil, were used as meteorological forcing and provided comprehensive observational constraints on the model. Results strongly suggest that deep roots with root niche separation adaptations explain both the observed resilience during seasonal drought and the vulnerability of canopy-dominant trees to extended deficits of wet season rainfall. These mechanisms appear to provide an adaptive strategy that enhances productivity of the largest trees in the face of their disproportionate heat loads and water demand in the dry season. A sensitivity analysis exploring how wet season rainfall affects the stability of the rainforest system is presented.
Palavras-Chave: | Ecohidrologia; Estresse hídrico.
Thesagro: | Floresta Tropical; Seca.
Categoria do assunto: | P Recursos Naturais, Ciências Ambientais e da Terra
Registro original: | Embrapa Amazônia Oriental (CPATU)
Exemplares: | CPATU - (47796-1) - UPC - AP - DD -  -  -  - DIS