First Amburana cearensis (Fabaceae) tree-ring chronology in Brazil in a dry forest shows great potential for climate reconstruction

Tree-ring chronologies are an excellent climate archive for their spatial and temporal resolution. While networks of chronologies have been built outside the tropics helping to understand past regional climate trends, tropical regions still lag behind in terms of spatial coverage. Dendrochronological studies, however, may succeed in seasonally dry tropical forests where the growing season is well defined. Amburana cearensis, found in both dry and wet forests in South America, is poorly explored for dendrochronological purposes, with no previous study in Brazil. Therefore, we sampled trees growing in a seasonally dry forest in a karstic area in Central-Eastern Brazil, under the South American Monsoon domain, in order to explore this species potential for dendroclimatological studies in the region. We build a tree-ring width chronology using 26 trees. We found a strong common growth signal among trees, with an r-bar of 0.51 and an average mean sensitivity of 0.50. The standard tree-ring width chronology showed a significant negative correlation with Vapor-Pressure Deficit during the entire wet season (0.54), negative correlation with temperature at the end of the wet season (0.45), and a positive correlation with the sum of precipitation during the wet season (0.46). Further stable isotopic analysis will provide additional records of climate variability in the region. Since Amburana cearensis occurs across most of the seasonally dry forests and savannas from South America, it has a great potential to be used to develop climate reconstructions and verify the effects of climate change currently affecting the region.