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, USA

Congreso; PAGES 1st Young Scientists Meeting & 3rd Open Science Meeting; 2009

PAGES - Oregon State University

Fires have been a recurrent disturbance in the Araucaria araucana forests from northernPatagonia during the past centuries. However, the influences of climate versus human activityon fire regimes in the Araucaria forest still remain poorly known. The objectives of this studywere to develop tree-ring and fire chronologies in the A.araucana forests from Ñorquinco,Minchén and Rucachoroi (Lanín National Park, northern Patagonia, Argentina) and todetermine the influences of climatic variability on tree growth and fire events. Partial crosssectionsfrom scarred trees were collected to develop the fire chronologies. Cores from nearbystands were used to develop the tree-ring chronologies of reference. All samples were processedfollowing the traditional dendrochronological methods. In all the sampling sites, an importantconcentration 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 withextremely low precipitation. This pattern is not clear in the other two sites, suggesting that fireevents in the Minchén and Rucachoroi are influenced by a combination of human activity andclimate. The establishment of the Lanín National Park in 1937 had a major influence on theregional fire regime, with a significant suppression in all sites. Variations in the tree-ringchronologies are directly associated with changes in the Palmer Drought Severity Index andnegatively with the Antarctic Oscillation Index during the current growing season, suggestinglarge potential of the Araucaria records to reconstruct regional variations in water balance andatmospheric circulation.