Influence of regional rainfall and Atlantic sea surface temperature on tree-ring growth of Poincianella pyramidalis, semiarid forest from Brazil

Abstract

A tree-ring width chronology was developed from samples of thirteen Poincianella pyramidalis trees from the Caatinga semiarid region of northeastern Brazil, where the climate is characterized by marked seasonality in precipitation levels. Although a thin continuous marginal parenchyma band represents the limit of seasonal xylem production, and in spite of the presence of false rings, cross-dating is possible. In this sense, an interseries correlation of 0.572 was found indicating a considerable degree of consistency in the variability found among trees. Precipitation between January and July has a direct influence on growth, while a five month dry season interrupts the active division of cambial cells. A significant positive correlation was also found between sea surface temperatures (SSTs) in the tropical Atlantic and tree growth, but with a lag of six months. As the rainfall regime of northeastern Brazil presents a great deal of inter-annual variability due to fluctuations in global factors such as the SSTs of the tropical Atlantic and the intertropical convergence zone, the close relationship observed between P. pyramidalis tree growth and regional climate fluctuations appears as a logical plant-environment interaction that can be used as a reliable parameter for dendroecological inferences on tree growth dynamics and the reconstructions of past droughts in the Caatinga region.