Are the oxygen isotopic compositions of <i>Fitzroya cupressoides</i> and <i>Nothofagus pumilio</i> cellulose promising proxies for climate reconstructions in northern Patagonia?

Abstract

Abstract Tree ring δ 18 O chronologies from two native species ( Fitzroya cupressoides and Nothofagus pumilio ) in northern Patagonia were developed to assess their potential for paleoclimate reconstructions. The five annually resolved cellulose δ 18 O chronologies (two for F . cupressoides and three for N . pumilio ) are located on the Andes along the steep west‐to‐east precipitation gradient. Over the common 60 years long interval, the five site‐δ 18 O cell chronologies exhibit a strong common signal as indicated by the significant mean intercorrelation ( r = 0.61, p &lt; 0.05) and the high percentage (65%) of total variance explained by the first empirical orthogonal function. Although correlation analyses reveal that the two mean species‐δ 18 O cell chronologies are mainly modulated by December–May temperature, the N . pumilio chronology shows a greater sensitivity to record temperature variations ( r = 0.57, p &lt; 0.05). The δ 18 O cell of N . pumilio contains a regional temperature signal representative of a large area in southern South America under the influence of the Southern Annular Mode. This study indicates that δ 18 O cell in N . pumilio is a promising proxy to reconstruct past variations in temperature in South America south of 38°S.