Sinais dendroclimáticos de Araucaria angustifolia (Bertol.) O. Kuntze em sítios ecologicamente semelhantes

Abstract

Dendrochronological studies have increasingly explored tropical and subtropical trees, mainly focusing on their climatic signs. In the Neotropics, growth ring width chronologies of Araucaria angustifolia have been developed at several localities in its range in the southern Atlantic Forest. However, the signals found in the studies do not show a clear pattern of growth response to climate. Understanding the causes of variability in dendroclimatic signals is relevant to direct dendrochronological studies in this species. The present work tests the premise that at independent sites but under similar environmental conditions, chronologies of A. angustifolia exhibit a common growth signal determined by limiting climatic conditions. A new ring width chronology was developed and compared to another preexisting one, in Curitibanos/SC, both under similar climatic, edaphic and vegetational conditions. The chronologies showed good internal level of synchronism and sampling effort. Yours trees had similar growth trajectories. The chronologies showed significant common signal, with moderate size. This common growth pattern, represented by a regional chronology, showed significant dendroclimatic signals with local climate variables and teleconnections with El Niño Southern Oscillation (ENSO), all weak size. Partial correlations showed that this set of climate variables was the determinant of the common signal between the sites. The results confirm the validity of the tested premise. Under the conditions studied, the growth response of A. angustifolia to climate arises from local variations in water and temperature availability, which operate at different stages of the annual growth cycle and are, to some degree, determined by ENSO. This low sensitivity of growth to climate is possibly related to the joint influence of these multiple factors and/or to the moderate variability of growth within sites. It is recommended that future dendroclimatic studies with species be based on comparing more than one site, with robust chronologies and replicating comparable ecological conditions, to avoid experimental biases arising from dating errors and the interaction between local factors with climate on growth.