干旱区生态环境知识资源中心

Due to the scarcity of species with annual tree rings, the use of dendrochronological techniques has received little attention in tropical and subtropical montane dry areas. In this study, we assess the dendrochronological potential of Prosopis ferox, "churqui", through the analysis of its wood anatomy and the relationships between climate and tree growth variations from trees collected at 3,500 m, in the Humahuaca valley (23 degrees 13’ S, 62 degrees 20’ W), Jujuy province, Argentina. Microscopic observations show that annual rings are clearly defined by a relatively lighter parenchyma belt formed at the end of the annual band. Comparisons between the standardized ring-width chronology and the instrumental records from La Quiaca (22 degrees 06’s, 65 degrees 36’W) indicated that above-average rainfall and below-average temperature during summer (i.e., December to March) favor tree growth. This can be interpreted as a positive relationship between radial growth and abundant soil water content during the growing season. The chronology shown here represents not only the first dendrocronological record from P. ferox, but also the first tree-ring chronology for the Prepuna biogeographic province. The well-defined annual rings, the strong relationship between growth and climatic variables, the large range of distribution across northwestern Argentina and southern Bolivia (20 degrees to 25 degrees S), and the longevity observed in some individuals (c. 500 years), indicate that P. ferox is a very promising species for dendroclimatological and dendroecological studies in subtropical montane ecosystems.