Austrocedrus chilensis response to mean and extreme climatic variability along a precipitation gradient in Northern Patagonia, Argentina

AMOROSO, M.; MARCOTTI, E.; VILLALBA, R.; MUNDO, I.A.

Melbourne

Conferencia; 9th International Conference on Dendrochronology; 2014

The steep west-to-east precipitation gradient in the rain shadow of the Andes drives dramatic changes in vegetation patterns. As a result of this abrupt gradient, Austrocedrus chilensis populations develop at sites widely ranging in moisture, receiving as much as 2000 mm in the western limit and as little as 600 mm in the eastern limit of its distribution in the forest-steppe ecotono. This remarkable change occurs in a narrow strip of only 40 kilometers making this precipitation gradient one of the most abrupt in the globe. We conducted a dendroclimatological study to quantify and compare the influence of mean and extreme climatic variability on the radial growth of A. chilensis populations growing across this precipitation gradient. We sampled sites along the gradient to build tree ring chronologies to study climate-growth relationships. Correlation function analyses were used to study the influence of macroclimatic factors on tree growth. The effect of extreme climatic events (droughts) was studied by comparing tree growth during drought and post-drought years with the mean growth of the previous decade. Preliminary analyses indicate a strong relationship between radial growth and precipitation but this might vary across the gradient. While the growth response to the past major droughts varied across the gradient depending on the drought type and the site conditions, stands at high precipitation sites appeared to be the most affected. Studies on such dramatic precipitation gradients are of great importance as these areas will be strongly affected under the future climate scenarios.