Teleconnection between tree growth in the Amazonian floodplains and the El Niño-Southern Oscillation effect
Jochen
Schoengart, Max-Planck-Institute for Limnology, jschoen@gwdg.de
(Presenting)
Maria Teresa
Fernandez
Piedade, Instituto Nacional de Pequisas da Amazônia, maitepp@inpa.gov.br
Wolfgang
Johannes
Junk, Max-Planck-Institute for Limnology, wjj@mpil-ploen.mpg.de
Martin
Worbes, Institute of Agronomy in the Tropics, mworbes@gwdg.de
There is a limited knowledge about El Niño-Southern Oscillation (ENSO) effects on the Amazon basin, the world's largest tropical rain forest and a major factor in the global carbon cycle. Seasonal precipitation in the Andean watershed annually causes a several month-long inundation of the floodplains along the Amazon River which induces the formation of annual rings in trees of the flooded forests. Radial growth of trees is mainly restricted to the non-flooded period and thus the ring width corresponds to its duration. This allows the construction of a tree-ring chronology of the long-living hardwood species Piranhea trifoliata Baill. (Euphorbiaceae). El Niño causes anomalously low precipitation in the catchment which results in a significantly lower water discharge of the Amazon River and consequently in an extension of the vegetation period. In those years tree rings are significantly wider. Thus the tree-ring record can be considered as a robust indicator reflecting the mean climate conditions of the whole Western Amazon basin. We present a more than 200-yr long chronology which is the first ENSO-sensitive dendroclimatic proxy of the Amazon basin and permits the dating of pre-instrumental El Niño events. Time series analyses of our data indicate that during the last two centuries the severity of El Niño increased significantly.
Submetido por Jochen Schoengart em 11-MAR-2004
Tema Científico do LBA: CD (Armazenamento e Trocas de Carbono)