Amazonian Tree Mortality during the 1997 El Niño Drought

Authors

  • G. Bruce Williamson,

    1. Department of Biological Sciences, Louisiana State University, Baton Rouge, LA 70803, U.S.A.,
      email btwill@lsu.edu
    2. Biological Dynamics of Forest Fragments Project, National Institute for Amazonian Research (INPA), C.P 478, Manaus, AM 69011–970, Brazil
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  • William F. Laurance,

    1. Biological Dynamics of Forest Fragments Project, National Institute for Amazonian Research (INPA), C.P 478, Manaus, AM 69011–970, Brazil
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  • Alexandre A. Oliveira,

    1. Laboratório de Botânica, Universidade Paulista, Av. Paulista 900, São Paulo, SP 01310–100, Brazil
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  • Patricia Delamônica,

    1. Biological Dynamics of Forest Fragments Project, National Institute for Amazonian Research (INPA), C.P 478, Manaus, AM 69011–970, Brazil
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  • Claude Gascon,

    1. Biological Dynamics of Forest Fragments Project, National Institute for Amazonian Research (INPA), C.P 478, Manaus, AM 69011–970, Brazil
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  • Thomas E. Lovejoy,

    1. Counselor to the Secretary for Biodiversity and Conservation, Smithsonian Institution, Washington, D.C. 20560, U.S.A.
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  • Luciano Pohl

    1. Biological Dynamics of Forest Fragments Project, National Institute for Amazonian Research (INPA), C.P 478, Manaus, AM 69011–970, Brazil
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Abstract

Abstract: In 1997, the Amazon Basin experienced an exceptionally severe El Niño drought. We assessed effects of this rare event on mortality rates of trees in intact rain forest based on data from permanent plots. Long-term (5- to 13-year) mortality rates averaged only 1.12% per year prior to the drought. During the drought year, annual mortality jumped to 1.91% but abruptly fell back to 1.23% in the year following El Niño. Trees dying during the drought did not differ significantly in size or species composition from those that died previously, and there was no detectable effect of soil texture on mortality rates. These results suggest that intact Amazonian rainforests are relatively resistant to severe El Niño events.

Abstract

Resumen: En 1997 la Cuenca Amazónica sufrió una de las sequías más severas de este siglo, asociada al fenómeno meteorológico El Niño. Usando parcelas permanentes determinamos la mortandad de árboles antes, durante, y después de El Niño de 1997. La tasa de mortandad de largo plazo (5-13 años) promedió tan solo un 1.12% anual antes de la sequía. Durante el año de la sequía, la mortandad anual aumentó a un 1.91%, pero disminuyó abruptamente a un 1.23% al año siguiente de El Niño. No se encontraron diferencias significativas en el tamaño ni en la composición de especies entre los árboles que murieron durante la sequía comparados con los árboles que habían muerto previamente. Tampoco se detectó un efecto de la textura del suelo sobre la tasa de mortandad. Concluimos que los bosques primarios de la Cuenca Amazónica son relativamente resistentes a los efectos asociados a eventos severos de El Niño.

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