Tree rings Chronologies of queñoa (Polylepis tarapacana) for the last 500 years in the Altiplano of Arica and Parinacota Region, Chile

Abstract

The need to cover the dendrochronological research gaps in the Sub Tropical regions of South America motivated the search for new geographical areas and new species to investigate climatic variability. Polylepis tarapacana grows above 4,200 m a.s.l. in South America (16º- 23º S), permitting the expansion of dendrochronological studies in subtropical areas. Samples from living and dead trees were collected in January 2003, near Nasahuento village (17º 32´S, 69º 35´ W) at 4,313 m a.s.l. and Guallatire volcano (18º 48´ S, 69º 08´ W) at 4,750 m a.s.l. These samples rendered the first two tree-ring chronologies of P. tarapacana in Chile. Nasahuento and Guallatire chronologies date back 242 and 536 years, respectively. Both were compared with instrumental records of precipitation and temperature. Statistics obtained from these analyses showed that both sites are adequate to be used for dendroclimatic purposes. Correlation functions showed that growth is mainly regulated by precipitation, correlating positively with the previous summer and negatively with the current one. January shows the most significant coefficients for both years. On the other hand, temperature is negatively correlated with the previous summer and positively correlated with the current season, evidencing a relationship between tree growth and water availability. Tree-ring chronologies developed in this study provide high-resolution climate sensitive records that are valuable for future climate reconstructions.