Effects of the 2011 Puyehue-Cordón Caulle eruption on the length and radial growths of Nothofagus pumilio

AMARU MAGNIN; RICARDO VILLALBA; CRISTIAN TORRES; MARINA STECCIONI; ALFREDO PASSO; CLAUDIA SOSA; JAVIER PUNTIERI

Mendoza

Conferencia; Third American Dendrochronology Conference; 2016

Tree-Ring society y IANIGLA

Volcanic eruptions can trigger plant responses that have beenlittle investigated compared to those resulting from the effects ofmore frequent and less extreme environmental factors. Weassessed the effects of the June 2011 eruption of the Puyehue -Cordón Caulle Volcano on the length and radial growths ofjuvenile-adult Nothofagus pumilio trees at two sites located 20and 75 km from the Volcano. At the site nearest to the Volcano(with >40 cm ash accretion), the effects of the eruption weretested on trees with two contrasting architectural conditions:forked and unforked trees. Variations in length and radial growthwere evaluated, respectively, for the periods 1999-2013 and1993-2013; pre- and post-eruption growth rates were computed.The length growth of the N. pumilio trees located close to theVolcano increased significantly after the eruption: shootextensions during the growth season after the eruption were, onaverage, two to three times longer than average according toontogenetic trends. Variations in radial growth after the eruptionwere comparatively less noticeable than those in length growth.The trunk of forked trees was thicker than that of single-trunktrees; the June-2011 eruption did not seem to affect suchdifferences. No significant effects of the eruption were observedin those trees located 75 km from the volcano. In order toexplain the exceptionally positive response of N. pumilio to thevolcanic eruption, several non-excluding explanations areproposed, among them the increase in soil moisture caused bythe fresh ash deposition. The comparatively lower level ofsensitivity of radial growth to this extreme event is alsonoteworthy.