Is Nothofagus dombeyi successfully recruiting in declining Austrocedrus chilensis forests? The effect of overstory mortality and discrete climatic events on species establishment

AMOROSO, MARIANO; SUAREZ, MARIA LAURA; DANIELS, LORI

Rovaniemi, Finlandia

Congreso; WorldDendro 2010 - 8th Conference on Dendrochronology; 2010

WorldDendro 2010

In mixed Nothofagus dombeyi - Austrocedrus chilensis forests successful establishment of both species occurs as a consequence of large natural disturbance in wet conditions. However, little is known about regeneration of these species at the eastern drier limit of N. dombeyi distribution near the pure A. chilensis forests. The mortality process in A.  chilensis forests known as ‘‘mal del ciprés” generates conditions (i.e. gaps) for the recruitment of new individuals. The objective of this study was to examine the population dynamics of both species in these conditions. We sampled and described the structure of 6 symptomatic stands and used dendrochronological techniques to reconstruct basal area development and regeneration establishment over time. Bivariate event analysis was performed to examine the temporal relationships between mortality events, climate and forest establishment patterns. While the diameter class distributions show similar ranges of sizes for both species, basal area development over time indicates that N. dombeyi established gradually after most the A. chilensis trees did. Likewise, we observed that the recruitment of new individuals over the past 2 decades correspond primarily to N. dombeyi individuals. The result of this study shows that N. dombeyi has the ability for establishing in postfire pure A. chilensis forests resulting in mixed unevenaged forests. Although there is not enough evidence at the moment to indicate a replacement of one species by the other, it is clear that after 100 years since establishment there is an important shift in the composition of these stands.