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

MAGNIN AMARU; TORRES D; STECCONI M; SOSA C

AUSTRAL ECOLOGY

WILEY-BLACKWELL PUBLISHING, INC

Año: 2016 vol. 42

1442-9985

Extreme environmental events such as volcanic eruptions can trigger plant responses that largelyexceed those recorded for moderate-intensity disturbances. We assessed the effects of the June 2011 eruption ofthe Puyehue ? Cordon Caulle volcano on the length and radial growths of juvenile Nothofagus pumilio trees attwo sites located 20 (with >40 cm ash accretion) and 75 (without ash) km from the volcano. Variations in lengthand radial growth were evaluated for the periods 1999?2013 and 1993?2013 respectively; pre- and post-eruptiongrowth rates were computed. The length growth of the N. pumilio trees located close to the volcano increasedsignificantly after the eruption: shoot extensions during the growing season after the eruption were, on average,two to three times longer than average according to ontogenetic growth trends. Variations in radial growth afterthe eruption were comparatively less noticeable than those in length growth. No significant effects of the eruptionwere observed in those trees located 75 km from the volcano. In order to explain the exceptionally positiveresponse of N. pumilio?s length growth to the volcanic eruption, three non-exclusive explanations were proposed:(i) thick ash layers increase water retention in the soil; (ii) volcanic ash facilitates the access of plants to nutrients;and (iii) volcanic ashes decrease herbivory and competition. The comparatively lower sensitivity of radialgrowth to this extreme volcanic event is also noteworthy. These findings highlight the need to further examinehow large-scale volcanic events influence structure and/or functioning of ecosystem in the Patagonian forest.