El Niño signal in the northern Austrocedrus chilensis chronologies.

JOSE A. BONINSEGNA; MARIANO S. MORALES; FIDEL ROIG

Quebec, Canada

Conferencia; 6th International Conference on Dendrochronology. Dendrochronology, environmental change and human history.; 2002

Centre d`études nordique, Université Laval

Austrocedrus chilensis is the most northerly distributed conifer species of the Andean Patagonian forest. We visited several tree-line sites of Austrocedrus chilensis at El Asiento, San Gabriel, Río Cipreses, Río Clarillo in Chile, and Huinganco in Argentina . These Austrocedrus chilensis sites represent the northern limit of the dispersion of the specie in Argentina and Chile. Central Chile and the northwestern part of Neuquen Province of Argentina are two of the several regions of atmospheric teleconnection associated with EL NIÑO events. Studies of instrumental precipitation records indicate that precipitation in these regions tends to be significantly higher during EL NIÑO years, especially during the austral winter. However no significant changes in the temperature during EL NIÑO years have been reported. To examine if northern Austrocedrus tree-ring chronologies were producing a distinctive growth pattern during EL NIÑO events and how strong the EL NIÑO signal is these tree-ring chronologies, we ran an event analysis on the standard, residual, and first difference versions of the chronologies. We use the regional EL NIÑO occurrence according to Quinn (1992) and Ortlieb (1993) for the last 500 years before present to identify EL NIÑO events (119 events). In all chronologies we were able to find growth differences associated with the EL NIÑO events, with characteristic and sometime contrasting patterns but no patterns that are unique to EL NIÑO years.