Responses of tree-ring growth in Schinopsis brasiliensis to climate factors in the dry forests of northeastern Brazil

Abstract

The Brazilian Northeast is a region of low rainfall and high temperatures and evaporation. The surface temperature of the Atlantic Ocean (STA) modulates the rains in the Northeast in association with El Niño and La Niña (ENSO) events. Tree species that grow in this region, forming the tropical Caatinga dry forests, are subjected to long periods of drought. This study investigated the influence of climatic events on the secondary growth of a typical Caatinga tree species. The analysis was based on 39 samples of Schinopsis brasiliensis , from which we derived a chronology of tree-ring growth between 1963 and 2015, with an inter-correlation of 0.56, mean sensitivity of 0.53, and mean growth rate of 3.33 mm per year. Our results indicate that growth ring chronology is related directly to the rainy season, in addition to peaks in humidity associated with isolated downpours occurring during the dry season. On the other hand, air temperature, insolation, and evaporation revealed an inverse relationship with the chronology. Inter-correlations with ENSO events, STA, and precipitation were negative, while those between ENSO events and temperature were positive. Growth in S. brasiliensis is associated with the climatic anomalies of the region. Leaf-fall and cambial shutdown occur during the dry season, while the plant is predisposed for potential growth spurts during the intermittent rains that may occur from December onwards