Teleconnection between tree growth in the Amazonian floodplains and the El Niño–Southern Oscillation effect

Abstract

There is a limited knowledge about the El Niñ o-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 that induces the formation of annual rings in trees of the flooded forests. Radial growth of trees is mainly restricted to the nonflooded 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 Niñ o causes anomalously low precipitation in the catchment that 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-year long chronology, which is the first ENSO-sensitive dendroclimatic proxy of the Amazon basin and permits the dating of preinstrumental El Niñ o events. Time series analyses of our data indicate that during the last two centuries the severity of El Niñ o increased significantly.

Hydroclimatic variables associated with El Nino and La Nina events at the Curuá-Una hydroelectric reservoir, Central Amazonia

“…The results presented here should be interpreted as a "starting point", since the precipitation in the Amazon region are is influenced by the complexity of the dynamics and atmospheric teleconnections (i.e., recurring and persistent, large-scale pattern of pressure and circulation anomalies that spans vast geographical areas). (Giannini et al 2001;Schöngart et al 2004;Yoon and Zeng 2010).…”

The global footprint of persistent extra‐tropical drought in the instrumental era

“…For the southern South America region, evidence from tree-ring data (Villalba et al, 1998) and stream flow data (Preito et al, 1999) point to drier than normal conditions in the late 1850s to early 1860s, the 1870s and the early 1890s. To the north, tree ring records from the Amazonian floodplains indicate wetter than normal conditions at these times (Schoengart et al, 2004), while Allan and D'Arrigo (1999), as an extension to the study by Quinn (1993), register a lack of El Niño related northeast Brazil droughts or 'Secas' in the 1860s (Quinn and Neal, 1992). Drought in Europe, though fairly well represented by the GHCN data, is further documented in the 1860s by Hulme and Jones (1994), by Casty et al (2005) gridded precipitation reconstructions for the European Alps during the 1860s and 1890s, and by tree-ring reconstructions from the eastern Mediterranean during the late 1850s, the 1870s and the 1890s (Touchan et al, 2005).…”

Tropical forests in a changing environment

“…RAINFOR authors have also discounted El Niñ o events as a source of disturbance because two very strong events occurred during 1982-1983 and 1997-1998 after most tree plots were established [31,39]. The most severe regional drought coincided with the 1925-1926 El Niñ o event, however, when fires were widespread and the Amazon reached the lowest level yet recorded at Manaus [48,49]. More importantly, multiple sources of past disturbance need to be evaluated.…”