Potential of Schinopsis lorentzii for dendrochronological studies in subtropical dry Chaco forests of South America

摘要

The lack of knowledge about species with well-delimited annual rings has hampered the development of dendrochronological records in the subtropical Chaco region of South America. In this contribution, we present the first tree-ring chronology of Schinopsis lorentzii (Anacardiaceae), a dominant species in the semi-arid Chaco. Cross sections were collected near Las Lajitas, Salta, Argentina, and processed following the methods commonly used in dendrochronology. Annual growth variations between radii from a single individual and between radii from different trees were highly correlated. To determine the climatic parameters that control radial growth, we compared annual tree-ring variations against regional temperature and precipitation records. Correlation functions indicate that tree growth is highly influenced by spring-summer rainfall variations, which represent more than 80% of the total annual precipitation. The chronology, which covers the interval from 1829 to 2004, provides a context for the unprecedented increase in precipitation since the mid-1970s in the region. The climatic-sensitivity of S. lorentzii provides a unique opportunity to reconstruct precipitation variations during past centuries in the extensive semiarid regions of subtropical South America.