Fire and climate variations inferred from Araucaria araucana chronologies in northern Patagonia

MUNDO, I.A.; KITZBERGER, T.; ROIG JUÑENT, F.A.; VILLALBA, R.

Corvallis, Oregon

Jornada; PAGES 3rd Open Science Meeting; 2009

PAGES

Fires have been a recurrent disturbance in the Araucaria araucana forests from northern Patagonia during the past centuries. However, the influences of climate versus human activity on fire regimes in the Araucaria forest still remain poorly known. The objectives of this study were to develop tree-ring and fire chronologies in the A.araucana forests from Ñorquinco, Minchén and Rucachoroi (Lanín National Park, northern Patagonia, Argentina) and to determine the influences of climatic variability on tree growth and fire events. Partial cross-sections from scarred trees were collected to develop the fire chronologies. Cores from nearby stands were used to develop the tree-ring chronologies of reference. All samples were processed following the traditional dendrochronological methods. In all the sampling sites, an important concentration of fire events was recorded during the second half of 19th century. In Ñorquinco, fire events were significantly related, based on superposed epoch analysis, to years with extremely low precipitation. This pattern is not clear in the other two sites, suggesting that fire events in the Minchén and Rucachoroi are influenced by a combination of human activity and climate. The establishment of the Lanín National Park in 1937 had a major influence on the regional fire regime, with a significant suppression in all sites. Variations in the tree-ring chronologies are directly associated with changes in the Palmer Drought Severity Index and negatively with the Antarctic Oscillation Index during the current growing season, suggesting large potential of the Araucaria records to reconstruct regional variations in water balance and atmospheric circulation.