Preliminary assesment of Araucaria araucana resilience to extreme drought events

SERGIO PIRAINO; ARCO MOLINA J. G; HADAD M.; ROIG FIDEL

Land

Conferencia; Tree Rings in Archaeology, Climatology and Ecology; 2021

Extreme climatic events represent disturbance factors shaping forest dynamics,inducing decline in growth and die-off episodes, furthermore modifying treeresilience. Araucaria araucana (Molina) K. Koch, an iconic northern patagonian conifer,is considered an endangered species according to IUCN classification. Weapplied dendroecological and statistical methods to reconstruct resilience, in termsof resistance and recovery, of 10 forest stands to three successive extreme dry spellsoccurred during the 20th century, with particular attention to site conditions (xericvs. mesic environments). Resistance and recovery showed differences along theconsidered dry spells, with a decrease in resistance for the more recent drought,whereas recovery values on the opposite showed an increasing trend. Xericwoodlands were less resistant than forest located in mesic areas, while recovery didnot show any difference among the selected environments. At the tree-level, we found aninverse relation among resistance and recovery indices in xeric stands, suggestingpossible different strategies when facing extreme droughts. Resistance (recovery) inboth environments was positively (negatively) associated with tree growth,represented by basal area increment values. Tree age positively influenced growthresistance but only in mesic environment. These findings suggest that the A. Araucanais less resilient to extreme droughts in xeric than in mesic environments. The expectedincrease in frequency and intensity of extreme drought for northern Patagoniasuggests that the emerged results should be considered in conservation plans of thisnatural resource