CONICET | Buscador de Institutos y Recursos Humanos

Polylepis tarapacana is a highly resistant tree speciesthat is well adapted to extreme conditions. This tree specie is growing in veryhigh altitude environments between 4000 and 5000 m a.s.l. and its distribution rangesfrom 16º S to 23ºS along the South American Altiplano. Tree-ring widthchronologies of P. tarapacana havebeen widely used for drought and precipitation reconstructions for SouthAmerica. Here, we present a 400-year tree-ring width chronology developed fromthe northernmost population of P.tarapacana located at 17º S and 69º W in southern Peru. This is the P. tarapacana tree-ring record closestto the equator. In order to study the influence of climate variability on P. tarapacana growth, precipitation andtemperature instrumental data were used for correlation analyses. Our resultsshow that this ring-width chronology is highly sensitive to the prior summerseason (Dec-Feb) precipitation variability when the South American monsoon (SASM)reaches its maximum intensity. In addition, we also found negative correlationwith temperatures for those months of the previous growing season. In theAltiplano, higher temperatures increase evapotranspiration and reduce wateravailability and thus, they may constrain radial growth,. Finally, strongrelationships were found between the El Niño Southern Oscillation (ENSO) andtree growth variability with positive correlations during the current growingseason and negative during the previous growth period. This result isconsistent with the well-known ENSO influence on climate conditions over theAltiplano, that is negative (positive) related to precipitation (temperature). Therefore,in this site the growth of P. tarapacanais strongly influenced by the amount of moisture availability that is linked tolarge-scale climate patterns such as the SASM and ENSO.